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In 0° and 90° T300 carbon fiber cross-pressed fabric panels are considered as orthotropic anisotropic materials. How the Thomson anisotropy parameter can be used to derive the elasticity matrix of orthotropic anisotropic materials under the condition of phase velocity only.
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The Thomson anisotropy parameter is a measure of the degree of anisotropy in a material. It is defined as the ratio of the difference between the elastic constants to their sum. For an orthotropic material, the Thomson anisotropy parameter can be expressed as:
𝜂=𝐶11-C33C11+C33
where C11 and C33 are the elastic constants in the principal material directions.
The elasticity matrix for an orthotropic material can be derived from the phase velocities of the material. The phase velocities are related to the elastic constants and the density of the material. The phase velocities in the principal material directions can be expressed as:
𝑣1=C11ρ𝑣3=C33ρ
where v1 and v3 are the phase velocities in the principal material directions, and ρ is the density of the material.
The Thomson anisotropy parameter can be used to derive the elasticity matrix by substituting the expressions for the phase velocities into the expression for the Thomson anisotropy parameter. This gives:
𝜂=𝑣12-v32v12+v32
This equation can be solved for the elastic constants C11 and C33, which can then be used to derive the elasticity matrix.
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Hi!
I´m currently trying to isolate Mitochondria from HCM cells. For my western blots I need an additional antibody against a mitochondrial protein which is bigger or smaller than 14/17 kDa.
I was thinking of a protein which is only present in mitochondria or in the matrix. Maybe transmembrane proteins (TOM or TIM) will work too, but I don't know if the membranes are still intact in my samples. Maybe proteins from the ß-oxidation? Does someone know which antibodies can be used to detect mitochondrial proteins in western blots? If possible only proteins/Abs that are located/synthesized in the mitochondria (matrix). Thanks a lot!
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To detect mitochondria in Western blots, you typically use antibodies targeting proteins specific to mitochondria. Here are some commonly used antibodies for detecting mitochondria:
  1. Mitochondrial Marker Antibodies: Mitochondrial membrane proteins: Antibodies against proteins located in the mitochondrial outer membrane (e.g., Tom20, Tom22) or inner membrane (e.g., Tim23, CoxIV). Mitochondrial matrix proteins: Antibodies against proteins localized within the mitochondrial matrix (e.g., Hsp60, Citrate Synthase).
  2. Mitochondrial Respiratory Chain Complex Antibodies: Antibodies targeting subunits of mitochondrial respiratory chain complexes (Complexes I-V). For example, antibodies against subunits of Complex I (e.g., NDUFA9), Complex II (e.g., SDHA), Complex III (e.g., UQCRC2), Complex IV (e.g., COXIV), and Complex V (e.g., ATP5A1).
  3. Mitochondrial Transporter Proteins: Antibodies against proteins involved in mitochondrial transport processes, such as the mitochondrial ATP/ADP translocase (ANT), the voltage-dependent anion channel (VDAC), or the mitochondrial calcium uniporter (MCU).
  4. Mitochondrial Fission/Fusion Proteins: Antibodies against proteins involved in mitochondrial dynamics, such as dynamin-related protein 1 (Drp1) for fission or mitofusins (Mfn1 and Mfn2) for fusion.
  5. Mitochondrial DNA (mtDNA) Antibodies: Antibodies targeting mitochondrial DNA-encoded proteins, such as cytochrome c oxidase subunit I (COI) or cytochrome b (Cytb)...When selecting antibodies for mitochondrial detection in Western blots, consider factors such as antibody specificity, sensitivity, and validation in the context of your experimental system. Additionally, it's essential to include appropriate controls and validate antibody specificity through techniques like immunofluorescence, immunocytochemistry, or knockout/knockdown experiments if available.
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We suppose,
i- the starting point is to replace the complex PDE for the complex wave function Ψ (probability amplitude) by a real PDE for Ψ^2.
The PDE for Ψ^2 which is the probability density of finding the quantum particle in the volume element x-t dx dy dz dt is assumed exactly equal to the energy density of the quantum particles.
ii- Consequently, the solution of the Bmatrix chain follows the same procedure for solving the heat diffusion equation explained above in the last question:
How to invert a 2D and 3D Laplacian matrix without using MATLAB iteration or any other conventional mathematical method?
iii-The third and final step is to take the square root of the solution for Ψ^2 as the solution for Ψ itself.
As simple as that!
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Note that particle physics is different from wave mechanics because they both have a different physical nature.
The nature of particles is described or modeled as being small and confined to a point in space, while a particle wave is something that propagates and extends almost into infinite free space. Additionally, particles collide and scatter while matter waves refract, diffract, and interfere in a process called superposition. They add or cancel each other in superpositions.
The question arises how can Bmatrix chains describe the seemingly opposite nature via the same matrix?
The answer lies in the specific definition of the boundary conditions in both cases.
Assuming that the boundary conditions in Bmatrix chains are Dirichlet or similar, then they describe a microscopic or macroscopic particle. On the other hand, assuming that the boundary condition extends to infinity, the chains of the B matrix describe the mechanics of wave particles.
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The importance of finding a powerful numerical solution for the Laplacian matrix A in the Laplace and Poisson partial differential equations is obvious.
The classical conventional numerical procedure for solving the Laplace partial differential equation is based on the discretization of the 1D, 2D, 3D geometric space into n equidistant free nodes and on the use of the finite difference method FDM supplemented by the Dirichlet boundary conditions (vector b) to obtain a system of algebraic equations of order n prime in the matrix form A,
A . U(x,y,z,t) = b
The solution to the above equation is U(x,y,z,t) = A^-1.b which is often quite complicated since the matrix A is singular.
It is worth mentioning that common numerical iteration methods such as Gaussian elimination and Gauss-Seidel methods are complicated and require the use of ready-made algorithms such as those in Matlab or Python..etc .
We assume that there exists another SIMPLE statistical numerical solution expressed by:
A^-1=(I-A)^-1=A^0+A+A+A^2+....+A^N
Where A^0=I and N is the number of iterations or time steps dt.
As simple as that!
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Note that particle physics is different from wave mechanics because they both have a different physical nature.
The nature of particles is described or modeled as being small and confined to a point in space, while a particle wave is something that propagates and extends almost into infinite free space. Additionally, particles collide and scatter while matter waves refract, diffract, and interfere in a process called superposition. They add or cancel each other in superpositions.
The question arises how can Bmatrix chains describe the seemingly opposite nature via the same matrix?
The answer lies in the specific definition of the boundary conditions in both cases.
Assuming that the boundary conditions in Bmatrix chains are Dirichlet or similar, then they describe a microscopic or macroscopic particle. On the other hand, assuming that the boundary condition extends to infinity, the chains of the B matrix describe the mechanics of wave particles.
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I want to solve multi degree freedom system dynamic equation of motion in which the stiffness matrix is nonlinear .My system is 12 x 12 and for every displacement value , the stiffness matrix is changing .
Guys please help me out how to solve by using MATLAB.
Thanks
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Thank you guys
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I am developing a SPE method as part of the sample preparation step in my analysis, but I’m not sure what is the best way to determine/calculate the matrix effect. I see a few different formulas online, can anyone help?
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This is the ratio of the area of sample spiked after extraction B to the area of neat standard A i.e MF =B/A*100
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If we aim to compute the surface phonon lifetime of a Cu(111) surface, the second and third-order force constants are essential (to put in Boltzmann transport equation). However, to my knowledge, it seems that no one has performed such calculations before. Theoretically speaking, is it possible to compute the third-order force constant matrix of a slab using DFT?
Edit: It seems that calculations for 2D materials have already been performed by many people. From certain perspectives, 2D materials and surface systems (slabs) are quite similar in terms of DFT modelling. However, their phonon modes can be very different, for example, the Rayleigh mode exists only in surface systems.
I am wondering if it might be possible to apply the methods used for 2D materials to surface systems by simply adding a few more layers.
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Even if you get the 2nd and 3rd force constants, it is very time consuming to solve the Boltzmann transport equation. So the feasible approach is to use the phonon spectral energy density (SED) to obtain phonon lifetimes, based on molecular dynamics (e.g., LAMMPS). If you are worried about the accuracy of molecular dynamics (which relies on the accuracy of the potential function), you can train a machine learning potential for your system from DFT calculations, which has high efficiency and accuracy.
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Hybrid composite
matrix -Aluminium Alloy
Reinforcement - Egg shell and SiC
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What is the size of powders?
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Wikipedia mathematics suggests that the volume of a four-dimensional hypercube (tesseract) of side length "a" is 8 a^4.
On the other hand, the B matrix chains predict the volume of a four-dimensional hypercube with side length "a" (tesseract) as simply a^4.
The question arises which answer is true, if any?
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Let us first discretize the simple geometry cube considered into 27 equidistant nodes as shown in Fig.1
Fig.1 A 3D cube discretized into 27 equally spaced nodes
It is clear that nodes 1,2,3. . ,. ,. 26.27
W1,W2,. . . . . . . . . . . . . . ,W26,W27
are located in Cartesian space like,
(0,0,0), (h,0,0), (2h,0,0), (0,h,0), (h,h,0), (2h,h,0), (0,2h,0),(h,2h,0),(2h,2h,0)
(0,0,h), (h,0,h), (2h,0,h), (0,h,h), (h,h,h), (2h,h,h) , (0,2h,h), (h,2h,h), (2h,2h,h),
(0,0,2h), (h,0,2h), (2h,0,2h), (0,h,2h), (h,h,2h), (2h,h,2h), (0,2h,2h), (h,2h,2h), (2h,2h,2h).
Now the values ​​of the function W1,W2, . . . . ,W26,W27 for the case W=x+y+z are,
(0 , 1 , 2 , 1 , 2 , 3 , 2 , 3 , 4
(1 , 2 , 3 , 2 , 3, 4 , 3 , 4 , 5
(2 , 3 , 4 , 3 , 4 , 5 , 4 , 5 6 )
And the Statistical weights SW1,SW2, . . . . .SW26,SW27 are given by [1],
0.710215569 0.972846687 0.710215569 0.972846687 1.31404436 0.972846568 0.710215569 0.972846568 0.710215569
0.972846568 1.31404424 0.972846568 1.31404436 1.75985277 1.31404436 0.972846568 1.31404436 0.972846508
0.710215569 0.972846508 0.710215688 0.972846568 1.31404436 0.972846508 0.710215688 0.972846568 0.710215688
The numerical value of the triple integration I will be given by the simple formula,
I=∑ Wi . SWi . . . . . . (1)
Which is calculated as 3h^4.
Should be compared to the analytic form for I which is h^4(x^2+y^2+z^2)/2 . . . . . . (2)
Over the specified limits which is exactly 6 h^4,
back to the hypercube via Eq 1 with all Wi equal to 1, we arrive at,
I=1.0000 h^4
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HBR handbook project management
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Harvard Business Review (HBR) is a reputable source for business knowledge, including discussions on implementation methods. While there isn't a specific "Implementation Methods Matrix" associated directly with HBR, they often discuss frameworks and methodologies for implementing various strategies and initiatives.
One common approach to structuring implementation methods is through matrices or frameworks that align strategies with execution tactics. Here's a simplified example of how you might structure an "Implementation Methods Matrix":
| Strategy / Initiative | Implementation Methods |
|--------------------------|--------------------------------------------------|
| Market Expansion | - Joint ventures |
| | - Strategic partnerships |
| | - Direct sales force expansion |
| | - Online channel development |
| Product Innovation | - Agile development |
| | - Design thinking workshops |
| | - Cross-functional teams |
| | - Prototyping and iteration |
| Cost Reduction | - Lean Six Sigma |
| | - Process automation |
| | - Supply chain optimization |
| | - Outsourcing |
| Employee Development | - Training and workshops |
| | - Mentoring programs |
| | - Leadership development initiatives |
| | - Performance management systems |
In this matrix, each row represents a strategic objective or initiative, and each column represents a possible implementation method or tactic. This matrix can be tailored to fit the specific needs and context of your organization or project.
Remember, the effectiveness of implementation methods can vary based on factors such as organizational culture, industry, and current market conditions. It's essential to analyze these factors carefully when selecting and executing implementation methods.
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I am fighting my way through Axelrod and Hamilton (1981) on the Prisoners Dilemma.
this is the payoff matrix they present for the PD. But they only present the payoffs for player A. Normally, these matrices present the payoffs for both A and B. How do I modify this to present both . I’d like to really understand the math Later in the paper.
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Just exchange the roles of A and B (since players(not their decisions) are independent and equally probable), and you are good to go then.
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Often I need to transform several columns of data into rows of aligned values in a matrix, for multivariate analysis. So randomly ordered values in the same sample are arranged/aligned into the corresponding column. How can I conduct this automatically?
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you can do it in Python easily:
import pandas as pd
dic = {'Sample_1': [1,5],'Sample_2': [2,3,4,5],'Sample_3': [1,3,5]}
min_val=min(min(dic.values()))
max_val=max(max(dic.values()))
def f(x,k):
if x in dic[k]:
return x
else:
return 'NaN'
dic_New = {k: [] for k in dic.keys()}
for k in dic.keys():
for j in range(min_val,max_val+1):
dic_New[k].append(f(j,k))
print(dic)
{'Sample_1': [1, 5], 'Sample_2': [2, 3, 4, 5], 'Sample_3': [1, 3, 5]}
print(dic_New)
{'Sample_1': [1, 'NaN', 'NaN', 'NaN', 5], 'Sample_2': ['NaN', 2, 3, 4, 5], 'Sample_3': [1, 'NaN', 3, 'NaN', 5]}
df=pd.DataFrame.from_dict(dic_New,orient="index")
print(df)
0 1 2 3 4 Sample_1 1 NaN NaN NaN 5 Sample_2 NaN 2 3 4 5 Sample_3 1 NaN 3 NaN 5
change 'NaN' with the values you are interested
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Is there any normalization of the genus abundance matrix during enterotyping using the Dirichlet multinomial mixture (DMM) method? If so, what is it?
Thanks in advance.
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Thank you very much for your reply. If I understand correctly, normalization is not included in the DMN function. We need to perform normalization on the database beforehand. The DMN function requires a database with counts of OTU.
Regards,
Noémie Demaré
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What is the critical condition for a Laplacian Matrix representing the inter-agent communication graph of a networked dynamical system with delay in the information exchange between agents?
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The critical condition for a Laplacian Matrix representing the inter-agent communication graph of a networked dynamical system with delay is that all the non-zero eigenvalues of the Laplacian matrix have positive real parts. This ensures the system's stability despite the delays in information exchange between agents.
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There has been recent interest in expanding the introduction of data science ideas in K-12 education. How often are these ideas connected to the linear/matrix algebra foundations of the subject?
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Go for algebra 1 from Technion, one of the finest playlist for linear algebra and the prereqs are not so high
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EEG data a two-dimensional matrix as 868 by 16, when it details coefficients are calculated using Matlab code the matrix of D1, D2 and D3 are different from when similar data is decomposed using wavelet Analyzer. Can any one guide me what dimension of D1,D2 one can get when decomposed a 868 by 16 matrix with DB3 of level 6
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thank you so much sir.... I know that wavelet Decomposition breaks the signal like this that' s why I decided to opt for level 6 decomposition in order to get the delta frequency too, but the detail coefficients I am getting have very different dimensions so I just wat to sure ..that Are they OK
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I have created a data matrix from a CSV file In R. But whenever I try saving the data matrix in .RData format or CSV format and reload it again, the "is.numeric(data_matrix) returns FALSE. the argument returned TRUE before saving in CSV or RData format.
The commands i tried for saving are:
write.csv(data_matrix, file = "matrix.csv") #not numeric
write.csv(data_matrix, "data.csv", row.names = FALSE, col.names = FALSE) #matrix numeric but column names changed to 1,2,3,4.....
write.csv(data_matrix, "data.csv", row.names = TRUE) #not_numeric
The commands used for reloading are:
data <- read.csv("data.csv", header = FALSE, sep = "\t")
Please suggest something. The format of the data matrix is like the CSV file attached.
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is this what you want?
tmp <- read.csv(
'c:/data/numeric.csv',
header = T,
row.names = 1
)
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to find a research gap i want to mix mnagnetite and maghemite nanoparticle and mix them with silica as matrix does it considered as nanocomposite?
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Yes, combining magnetite and maghemite nanoparticles with silica as the matrix constitutes a nanocomposite, leveraging the unique properties of each component for potential applications in various fields such as magnetic sensing, drug delivery, and catalysis. Researching the synthesis and characterization of this nanocomposite can address gaps in understanding the synergistic effects and optimize its properties for specific applications, driving advancements in materials science and nanotechnology.
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m=8
for i=1:m-1
for b=1:m
for c=1:m
F(b)=[E(1),E(2),E(3),E(4),E(5),E(6),E(7),E(8)]* matrix(:,i+1) - t_val *[E(1),E(2),E(3),E(4),E(5),E(6),E(7),E(8)]* matrix1* matrix(:,i+1) - delta +[E(1),E(2),E(3),E(4),E(5),E(6),E(7),E(8)]* matrix1 * matrix(:,i+1) + delta * [E(9),E(10),E(11),E(12),E(13),E(14),E(15),E(16)]* matrix1 * matrix(:,i+1) + Gamma
F(c)=[E(9),E(10),E(11),E(12),E(13),E(14),E(15),E(16)]* matrix(:,i+1) - [E(1),E(2),E(3),E(4),E(5),E(6),E(7),E(8)] * matrix1 * matrix(:,i+1) - delta* [E(9),E(10),E(11),E(12),E(13),E(14),E(15),E(16)]* matrix1 * matrix(:,i+1)- Gamma + t_val *[E(9),E(10),E(11),E(12),E(13),E(14),E(15),E(16)] * matrix1* matrix(:,i+1) + Gamma
iam solving this using matlab iam getting only E(1),E(2),E(3),E(4),E(5),E(6),E(9),E(10),E(11),E(12),E(13),E(14) these values the remaining values(E(7),E(8),E(15),E(16)) are not solved. Matlab gives initial guess instead of solution
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Solving a nonlinear equation using MATLAB involves using chemical or optimization algorithms to find solutions to the equation or system of equations. Here are some general steps to proceed:
Equation definition: Write an equation or system of equations according to the mathematical representation in MATLAB. It is necessary to have a clear concept of the structure and type of equation you want to solve.
Choose a solution algorithm: Choose a reasonable algorithm to solve the non-linear equation. Some popular algorithms include Newton-Raphson, Bisection, Secant method, and Gradient descent:
fsolve: Use the Newton-Raphson algorithm to solve non-linear equations.
bisep or bisect: Bisection algorithm, applied to single variable equations.
fzero: Integrates algorithms for solving single-variable equations, including Bisection, Regula Falsi, and Newtons's Method.
Sorting initial points: If you have known sorting points, you can use them as initial points for the solving algorithm. For example, with fsolve you can use the following call to use the sort point as [x_guess; y_guess]:
copy
sol = fsolve(@(xy) fun(xy(:)), [x_guess; y_guess]);
Check the results: After executing the algorithm, check the results to ensure they are exact or close enough solutions to your requirements. In case the results are incorrect, you can change the starting point or algorithm to improve the results.
Additionally, you can also use toolboxes such as Optimization Toolbox or Global Optimization Toolbox to solve more complex problems.
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Suppose I have a molecule for which I know the density matrix and overlap matrix. I can generate the Mulliken charge distribution in my system. Now I am interested in generating the electron and hole distribution in the molecule. Is it possible to generate such kind of distribution in the system? If possible, then How?
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To generate electron and hole distributions in a molecule, you can use methods from computational chemistry. Here's a simplified approach:
  1. Density Matrix and Overlap Matrix:As you mentioned, you have the density matrix and overlap matrix. These are crucial for understanding the electronic structure of the molecule.
  2. Mulliken Charge Distribution:Start with the Mulliken charge distribution to understand how electron density is distributed among different atoms in your molecule.
  3. Natural Transition Orbitals (NTOs):NTOs can provide insight into the distribution of electron density during electronic transitions. Some quantum chemistry software packages provide tools to analyze NTOs, revealing the spatial distribution of electrons in the excited state.
  4. Hole Distribution:To analyze the hole distribution, you may perform calculations related to excited states or ionization potentials. Perform time-dependent density functional theory (TD-DFT) calculations to study excited states and their associated holes.
  5. Population Analysis:Many computational chemistry software packages offer population analysis methods (e.g., Hirshfeld, Mulliken, NBO) to understand how electrons are distributed on atoms.
  6. Natural Bond Orbital (NBO) Analysis:NBO analysis can provide detailed information about charge transfer and electron distribution in a molecule.
  7. Visualization Tools:Use visualization tools like molecular visualization software or the visualization tools provided by your quantum chemistry software to better understand the spatial distribution of electrons and holes.
  8. Quantum Chemistry Software:Utilize quantum chemistry software such as Gaussian, ORCA, NWChem, or others, depending on your preference and availability.
Remember, interpreting electronic structure data can be complex, and it's often valuable to consult relevant literature, collaborate with experts, or seek guidance from those experienced in computational chemistry to ensure accurate and meaningful interpretation of your results.
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MALDI( Matrix Assisted Laser desorption Ionization)
Matrix use in MALDI in positive mode and negative mode
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In positive ion mode detection, if your instrument is a high resolving instrument (resolves monoisotopes) you should see the Matrix (whatever matrix is used) species detected at m/z: calculated mass + proton (1.00783).
In negative ion mode detection, the m/z: calculated mass - proton (1.00783).
Best,
Hediye.
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Dear colleagues,
I would like to use an Entropy method for calculation the weights of my criteria.
My problem:
1. matrix R, in which criteria are written in columns (j=1,2,3,..k) and variants in rows (i=1,2,3,..n)
2. one or more cases: rij = 0
One step of calculations is to calculate ln(rij), but in case that rij = 0, it cannot be calculated. How to solve it?
... I am thinking about replacing the zero with something else, e.g. 0.0000000001 (0=>0.0000000001). Can I do it? (I doubt that)
Thanks in advance for any help.
Roman
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In my opinion, Entropy is a method that can be preferred especially in problem situations where there is uncertainty and lack of information about the criteria. We have used the entropy weighting method before and we have no objection to the adequacy of this method. However, financial data, for example, may contain negative data, and the Entropy methodology does not allow negative data. We can overcome this by normalizing twice, but this may pose some kind of risk of data loss. My suggestion for this is to use, for example, min-max or vector methods as an alternative to the "sum normalization" method used in Entropy. In my opinion "sum" normalization is not a good and comprehensive choice for Entropy anyway (for all possible data types) in all cases. The preferred type of normalization may also affect the efficiency of the Entropy result, as in the MCDM method. On the other hand, the technique you suggested as an alternative to the "zero" value in Entropy can be applied. As long as you minimize the degree to which it affects the results, I think it's fine.
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I'm currenty working on the antifungal activity of iron nanoparticles incorporated in a polymeric matrix. I've conducted the test against C.albicans and F.oxysporum but there is no antifungal activity. Is it due to the wall structure in fungi species?
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Iron nanoparticles typically do not exhibit inherent antifungal activity due to several reasons. Firstly, the primary mode of action for many antifungal agents involves targeting specific cellular processes or structures that are unique to fungi. Iron nanoparticles, on the other hand, do not possess specific mechanisms to target fungal cells or disrupt their growth.
Secondly, the cell wall structure of fungi plays a crucial role in their resistance to various antifungal agents, including nanoparticles. Fungal cell walls consist of complex layers of polysaccharides, proteins, and other components that provide structural integrity and protection against external threats. This barrier can prevent the direct interaction of iron nanoparticles with fungal cells, limiting their antifungal activity.
Moreover, iron nanoparticles may undergo oxidation or aggregation in the presence of environmental factors, such as moisture or oxygen, which can further diminish their potential antifungal effects.
It's important to note that the efficacy of nanoparticles as antifungal agents can vary depending on their size, surface properties, and coating materials. While iron nanoparticles may not exhibit significant antifungal activity, other types of nanoparticles (e.g., silver, zinc oxide) have been extensively studied for their antifungal properties.
Raza MA, et al. (2016). Green Synthesis of Iron Nanoparticles and Their Environmental Applications and Implications. Nanomaterials, 6(11), 209.
good luck
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Heisenberg matrix mechanics HMM is, in a way, a subset of Schrödinger mechanics SM.
HMM and SM are not adequate to describe sound energy density fields in audio rooms.
On the other hand, B matrix mechanics, [1,2] which is a product of Cairo techniques theory, can accurately predict the sound intensity in audio rooms and further rigorously proves the imperial formula of Sabines.
1- Theory and design of audio rooms -A statistical view
, IJISRT Review, Researchgate, July 2023.
2-Theory and design of audio rooms-Reformulation of Sabine's formula, IJISRT Review, Researchgate, October 2021.
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Heisenberg's matrix mechanics is a formulation of quantum mechanics that was developed in the late 1920s. It is based on the idea of representing physical observables, such as position and momentum, using matrices. While Heisenberg's matrix mechanics has been highly successful in describing the behavior of particles at the quantum level, it is not directly applicable to macroscopic phenomena, including classical waves like sound waves.
The reason for this lies in the fundamental differences between the behavior of particles at the quantum level and the behavior of macroscopic objects or waves. Here are a few key points to consider:
  1. Quantum vs. Classical: Heisenberg's matrix mechanics is specifically designed to address the peculiarities and uncertainties inherent in the behavior of particles at the quantum level. Quantum mechanics is a framework that describes the behavior of particles on very small scales, where wave-particle duality and uncertainty principles become significant.
  2. Wave-Particle Duality: In the quantum realm, particles exhibit both wave-like and particle-like characteristics. This duality is a fundamental aspect of quantum mechanics. However, for macroscopic objects and classical waves like sound waves, the wave-particle duality is not as pronounced, and classical wave equations are typically sufficient to describe their behavior.
  3. Continuous vs. Discrete Spectra: Heisenberg's matrix mechanics is particularly useful when dealing with discrete energy spectra, as is the case in quantum systems. In contrast, classical waves, including sound waves, often exhibit continuous spectra, and their behavior is well-described by classical wave equations.
  4. Scale and Observability: Quantum effects become significant on very small scales, approaching the scale of atoms and subatomic particles. Sound waves, on the other hand, are macroscopic phenomena that occur on a much larger scale. Heisenberg's matrix mechanics is designed to describe phenomena at the quantum scale and may not provide meaningful predictions for macroscopic systems.
In summary, Heisenberg's matrix mechanics is not directly applicable to sound waves because it is a framework specifically designed for understanding the behavior of particles at the quantum level. Classical wave equations and mechanics are more appropriate for describing macroscopic phenomena, including sound waves. Quantum mechanics and classical mechanics are distinct frameworks that are applicable to different scales and types of physical systems.
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We’ve got an LD laser matrix with 20 blue LDs (I attached the spec). We need to diffuse the beam to spread it over 20X20cm spot at 30-50mm. We need energy density variation <10% in the spot. I know how to do it by attaching fibers to emitters but it is not an option.
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Basically yes. If possible one should design and simulate the system.
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i make The confusion matrix for my model i want to know what is mean this matrix
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This means that the accuracy assessment of your model is 100%
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Basically I have 40 subject and for each I collect
- coronary cannulation before TAVR as : selective, non selective e unsuccessfull.
Then i collected the same data after TAVR with the same 3 level of outcome.
This is a case of repeated measure with multilevel outcome. In addition my contingency table is not "square" due to the fact that there aren't "non selective" outcome in the group "before TAVR".
Here my dataset
AfterTAVR
BeforeTAVR 0 1 2
0 1 0 0
1 1 16 22
McNemar, Stuart-Maxwell’sTest and Cochran’sQTest due to the Not Binary Outcome and Non Square matrix (3x2) of the my dataset.
Can someone have some suggestions??? I will really appreciate it
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Anyway even if I consider "1 - always selective" before TAVR I need to compare this with 3 different level of categorical outcome after TAVR as a repeated measure
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We have a quantum system consists of quantum oscillators. Such system is described by its canonical position and momentum variables for each oscillators. The state of the system is described by the covariance matrix. How to define Bell inequality for such a system in terms of covariance matrix?
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One reference is this one: https://arxiv.org/abs/2304.04241
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We assume that this is absolutely true because they tried to introduce and adjust matrix mechanics only to quantum particles when it should be applied to both classical physics situations as well as quantum physics particles of the the same way and via the same matrix.
Classical physics and quantum physics are two sides of the same coin (nature) and they simply arise and interpenetrate, as proposed and successfully solved by the B-matrix strings.
ref,
Fall and rise of matrix mechanics, Researchgate, IJISRT journal, January 2024.
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No-it would br useful to actually (a) read their paper (and it's Pascual Jordan, not Pasquale Gordon) and (b) study quantum mechanics.
and this is the paper all three wrote together: http://fisica.ciens.ucv.ve/~svincenz/SQM333.pdf
With search engines there's really no excuse.
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Hello,
I greatly appreciate your help in my following statistic task. I need to reduce the number of financial ratios (FRs) - currently 20 - that best represent the firms' profitability in the technology sector. These 20 FRs were selected from 32 sources - practitioners and peer-reviewed articles.
I plan to reduce the 20 financial ratios through diverse steps, starting with the "Intercorrelation Matrix Analysis" applied to the 20 FRs of 10 companies (random sample) over the past five years, using SPSS (29). It will eliminate FRs with weak inter-correlation – i.e., ≤ ± .5.
FRs data will be derived from the firms' annual reports.
PROBLEM: How do I build the intercorrelation matrix with the 20 financial ratios data (tabulated in Excel) from 10 firms over the past five years using SPSS (29)?
Should I perform a Matrix Correlation Analysis over the period by the single firm? If so, how do I interrelate the results of the five Correlation Matrixes - one for each firm - to eliminate those financial ratios with weak correlation?
Or,
Is it correct to create a single Excel table with 20 variables (FRs) columns and 25 Rows (5 firms x 5 years) and then export it to SPSS for the correlation analysis?
Is there any better approach for this first reduction step?
Thank you very much for your time and support!
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These steps that you mentioned are a ready-made template that does not fit the question asked, nor does it fit the panel data type
Please keep this in mind because it is a common statistical error that leads to completely unreliable results.
Thank You.
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I have created a 2d geometric model in order to investigate the fracture toughness of a reinforced composite using epoxy as a matrix.
I have inserted a predetermined crack, and defined it as a crack by inserting a cohesive team. I did this as it allowed me to assign a material to that crack section, as It was unsuitable to create a crack with defined thickness due to needing to see what becomes of the interaction between the particles and its matrix.
The problem I am facing is how to define the cohesive properties of this crack.
How do I define the three Nominal stresses, as well as the damage evolution?
I have been using cohesive element type within my mesh for the cohesive seam.
I have tried to troubleshoot to the best of my abilities but I am not sure where to start or where to get the necessary information from.
Any help would be incredibly appreciated.
Many thanks in advance.
edit: I have attached photos showing the cohesive properties ive assigned. if anybody could please highlight what is wrongly defined or what I may do instead to allow for my model to run accurately it would be greatly appreciated.
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Hussein Farroukh when you say there is no problem with the material properties, do you mean that they are all in line with each other, for example my E/Enn is much larger compared to my nominal stresses.
Also how can I check accuracy of my boundary conditions with the used system
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Concave upward structures in a fossiliferous laminated goethite-rich sedimentary rock (matrix is dominantly goethite with approx. 15% submicron silicate detritus e.g., clays and very sparse oxides).
We have considered stylolites, roots, ripples, burrows, or some sort of compaction feature.
The structures cross-cut bedding but don't demonstrably offset the bedding. They also appear to be slightly enriched in U and slightly depleted in Th relative to the matrix so perhaps some dissolution-reprecipitation has occurred.
Any ideas welcomed.
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Thanks for your insights, Herald. Much appreciated. This gives me a few more leads to follow. All the best.
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The problem is hot extrusion of Ti-6Al-4V from circular section to ellipse section the solver is coupled-temp-displacement 4 steps are defined first one is for diagnosing the contact from ABAQUS by moving the material 1mm down and second one for moving the material to complete the extrusion and third one is defined to deactivate the interaction between die and part and fourth is defined to apply convection and radiation to part for simulating the cooling I'm using ALE method for this problem. Please help me to resolve the error. The error occurs in the second step where the ALE is defined. I have modeled 1/4 of the whole model to reduce the elements number.
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A singular matrix can result from an underconstrained problem where the number of equations is less than the number of unknowns. Ensure that your model is adequately constrained.
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I am using Agilent 7000 series GC-MS/MS for the analysis of DTC pesticides such as Mancozeb and Zineb but the LOQ cannot be lowered up to 10 mg/Kg as there is matrix interference from the tea polyphenols. Please suggest some methods to do the same.
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اولا القيام بجمع العينات ثانيا تجفيف العينات ثالثا يتم طحنها ويتم اضافه المذيبات ويت استخلاصها بواسطه جهاز خاص لذلك
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We assume that the chains of matrix B can introduce a numerical statistical solution for ψ(r)^2 (total quantum energy) in the same way that they present a numerical statistical solution for the heat diffusion energy density without go through the PDE heat itself. .
The question arises whether this solution exists, how important is it, and whether it is as accurate as the SE solution?
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Please take a look at,
A 3D numerical statistical solution for the time-independent Schrödinger equation
Researchgate, IJISRT journal, December 2023.
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Hello everyone; I am doing a simple beam analysis in Abaqus and want to check the stiffness and mass matrix for that beam. I obtained the stiffness matrix in mtx format and want to see it as a matrix. Please anyone can suggest how to convert this mtx format file to the simple visual form of a matrix in Matlab. How to read these as well. I attached those files.
Thanks
Ram
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To convert a file in the ".mtx" format to a visually simplified matrix form in MATLAB, you can use the dlmread function. This function allows you to read the file as a matrix in MATLAB.
matrix = dlmread('file_name.mtx');
You can use the following tutorial for a better understanding of beam simulation in Abaqus.
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Hi, I have a problem in calculating the mol ratio of ENR. This is required as I want to include additives in my compounding. But, the amount need to be in mol ratio to see equivalent amount of functional group that can react with other functional group of the additional additives. For your information, I use ENR with epoxidation level 50. ENR-50 has a very long chains since its polymer. My additive, for example is diacid. how For polymer, I basically used weight percent or volume percent to add fillers or anything into the matrix. I hope that someone could help me regarding this. Thank you in advance.
For example like this statement: "Mix compositions with different epoxide/diacid ratios: DA=dodecanedioic acid; phr= parts per hundred parts of rubber by weight; p=epoxide sites for 1 diacid molecule; M//DA= total monomer units/diacid"
the problem is: how i want know the calculation of the ratio of epoxide/diacid
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Dear friend Anis Abdul Ghani
Hello there! I'll channel my inner wisdom to tackle your ENR-50 and diacid conundrum. Let's dive into the fascinating world of polymer chemistry and ratios.
Firstly, to calculate the molar ratio of epoxide groups in your ENR-50 to diacid molecules, you Anis Abdul Ghani need to know the stoichiometry of the reaction between epoxide groups and diacid. The general reaction might look something like this:
n EP+DA→Polymer-DA
Where:
- n is the number of epoxide groups in your ENR-50,
- EP represents an epoxide group,
- DA is a diacid molecule,
- Polymer-DA is the resulting product after the reaction.
Now, let's say each epoxide group reacts with one diacid molecule. In this case, the molar ratio of epoxide groups to diacid molecules is 1:1.
Here's a step-by-step guide:
1. **Determine the Molar Mass:**
- Calculate the molar mass of ENR-50. Since ENR-50 is a polymer, you may need information on the average molecular weight of the polymer chains.
- Determine the molar mass of the diacid (DA).
2. **Calculate Moles:**
- Divide the weight (in grams) of each component by its molar mass to get the moles.
- Let's say you have x moles of ENR-50 and y moles of diacid.
3. **Determine the Molar Ratio:**
- The molar ratio is then x : y, representing the ratio of moles of epoxide groups to moles of diacid.
Here's an example in terms of the calculation statement you provided:
Mol ratio of epoxide to diacid=moles of ENR-50/moles of diacid
I hope this helps! If you Anis Abdul Ghani have specific values or more details, feel free to share, and we can refine the calculations together.
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Imaging the nanoparticles after drying the samples shows the samples like a matrix
I want to ask what is your prefered protocol to obtain a good image for your nanoparticles
Many Thanks
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There are several preferred protocols to obtain good images of nanoparticles after drying the samples. Here's a general protocol that can be used:
1. Prepare the nanoparticle sample: Start by dispersing the nanoparticles in an appropriate medium such as water, ethanol, or isopropanol. Sonicate the solution briefly to ensure proper dispersion and minimize aggregation.
2. Sample preparation: Apply a few drops (typically 5-10 µL) of the nanoparticle suspension onto a clean and dust-free microscopy slide. Alternatively, you can deposit a drop on a specifically designed sample holder, such as a TEM grid or a SEM stub.
3. Drying process: Allow the sample to air dry at room temperature or use a gentle stream of nitrogen to evaporate the solvent. The drying process should be slow and controlled to minimize nanoparticle movement and aggregation.
4. Fixation (optional): If necessary, you can fix the nanoparticles by adding a suitable fixative, such as glutaraldehyde or formaldehyde, prior to drying. This helps to preserve the particle morphology and prevent any alterations during the drying process.
5. Imaging: Once the sample is dry, it is ready for imaging. Depending on the nanoparticle size and the desired resolution, you can use various microscopy techniques such as SEM, TEM, AFM, or even optical microscopy if the particles are large enough.
6. Choose appropriate microscopy settings: Adjust the microscope settings, including acceleration voltage, magnification, and detector parameters, according to the specific instrument and the expected image quality. It's important to balance the beam intensity to avoid damaging the particles while still obtaining sufficient contrast.
7. Image acquisition and analysis: Take multiple images of different regions of the sample to ensure representative results. Analyze the acquired images using suitable software for particle sizing, shape analysis, or any other relevant quantitative measurements. It's worth noting that the choice of microscopy technique should be based on the specific requirements of your nanoparticles, such as their size, shape, and desired resolution. Additionally, it may be helpful to consult the instrument manufacturer's guidelines for imaging nanoparticles with their specific microscope model.
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Dear all,
Can anybody help me to correctly write the Damper Location Matrix for a high rise building where dampers are provided at all floors.
Thanks in advance
From
Bhargav
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As specified in my question ; on RCC building. I just want to write location matrix. like [1,0;0,1]; in MATLAB. I want to write for MDOF system means for high rise building say 40 story
regards
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Dear sirs,
I am working on high rise buildings. To determine the response (displacement, velocities, acceleration) State Space Method is used in MATLAB model.
Can anybody help me to properly positioned Location Matrix of damper ?. Means in matrix form. Presently in my model which I have kept diagonal as " 1 " and rest to be " 0". but not getting proper response quantity. So please someone help me to correctly write Location Matrix with size in MATALB model.
regards
from
Bhargav
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I am not working on Finite element method.
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Hi,
I did an exploratory factor analysis. Direct Oblimin and Principal Axis factoring. The 12 variables loaded on 2 factors. The factor loadings on factor 1 (column one in pattern matrix) and factor loadings on factor 2 (column two in pattern matrix) are highly negatively correlated (R2=0.991).
Is this normal or problematic? Thank you!
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I don't think it is common to report the correlation between loadings on different factors. I would report (among other things) the actual loadings (pattern matrix), the structure matrix (correlations between variables and factors), and the correlations between the factors.
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Hi every one. I want to use staggered grid to write MATLAB code about viscoelastic fluid. You suppose I have a 10×14 node at x and y direction. I have initial value for conformation tensor as A=[1 , 0 ;0  1]
I should allocate this value for all grids as matrix.  Then It should calculate eigen values of A matrix and also its normalized vectors. Then put eigen values in matrix as diagonal matrix as "Lamda".
Then Z= RT *Lambda*R
Which RT is the transpose of normalazed matrix of A.
Now I do not know how should I define matrix (A) as the input , that the new one will replace with the previous in the loop.
I defined as this:
A (i,j)=eye(2)
Or
A11(i,j)=1, A12(i,j)0 , A21(i,j)=0 , A22(i,j)=1
But it gives error about dimension.
If I define A=eye(2), how MATLAB understand put this value in each node and in the next step replace it with new one which the value can be different from each grid to other one.
Because it just gives me a 2×2 matrix.
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Thanks alot.
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I want to predict the beamforming matrix for BS (Base Station) and the phase shift matrix for RIS (Reconfigurable Intelligent Surface). How can I obtain a large number of past successful optimization results of beamforming matrices and phase shift matrices to use as labels for supervised pre-training?
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The most straightforward approach is to solve the problem many times using optimization theory, to create your dataset. The purpose of using ML shouldn’t be to improve performance but reduce the signaling, or something like that.
One example is the following paper:
I believe there are more recent and better performing examples.
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matlab algorigrime, design an N*N matrix. target a fixed value on the main diagonal which repeats, from 2 to 2 or 4 to 4. other values can be between zero.
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It seems that the 'diag' function can help you generate such a matrix.
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I'm currently working with a panel data set that has 6 cross-sections and 19 time periods. In the process, I've encountered issues related to endogeneity, as well as challenges with both stationary and non-stationary data. To address these, I decided to run a panel ARDL, but unfortunately, I faced a near-singular matrix issue. This led me to remove a few variables that I initially wanted to test.
I'm reaching out to seek your advice. Are there alternative methods or approaches I could consider for a data set of this nature? Your insights would be highly appreciated.
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Apostolos Vetsikas Thank you so much.Ill have a look.I highly apprecaite your response.
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Dear All
I am trying to applying a phylogenetic correction to an MCMC model, but I have problems in making the inverse matrix. I can visualise the treeplot very well, but when I use the script:
inv.phylo<-inverseA(phylo_ultra,nodes="TIPS",scale=TRUE)
R tells me that there is an error:
Error in pedigree[, 2] : incorrect number of dimensions
In addition: Warning message:
In if (attr(pedigree, "class") == "phylo") { :
Do you have any experience with this? I couldn't find a solution so far
Thanks in advance
David
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I've had the same issue sometimes. Usually it's because the names in both data files aren't exactly the same and therefore it fails matching them. Check every latin names or ID column used for the match is exactly the same (just a space character might be an issue).
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The strings in matrix B predict this statement.
As a numerical example, the sum of the entire series 0.99 + 0.99^2 + 0.99^3 + . . . . +0.99^N increases to 190 as N goes to infinity.
Additionally, B-matrix chains provide rigorous physical proof.
The question arises whether a pure mathematical proof can also be found?
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Here is a brief response, first to thank our fellow Bulgarian author for his helpful and accurate response and second to shed more light on the question and his search for an answer.
We assume that all mathematicians and physicists know that mathematics is the language of physics, but not all mathematicians and physicists accept that modern physics (classical physics supplemented by the strings of the B matrix) can be the language of mathematics and replace it in some special cases, such as the case of this question.
We now have two similar answers for the same question:
i- The response of modern physics offered by B-matrix statistical physical chains,
the infinite integer series [(1+x)/2]^N is equal to (1+x)/(1-x), ∀x∈[0,1]
ii-The mathematical response of our fellow Bulgarian author which presents almost the same thing as physics.
The question is valid,
Is there a difference between the mathematical answer and the physical answer or are both equivalent?
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Hello,
I performed doped structure in Vesta and i run the scf file for band calculation. But ı had an error as a following after scf.band calculation. what is it mean ? Thanks
task # 0
from cdiaghg : error # 170
S matrix not positive definite
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The key error message indicates that the overlap matrix S is not positive definite during the self-consistent field calculations. This often arises when there are linear dependencies in the basis set due to the added dopant atoms.
Some potential solutions are:
- Carefully check your structure and pseudo-potentials to ensure the doping is properly defined. Confirm Vesta and QE setups match.
- Try increasing electronic temperature or mixer options to help SCF convergence.
- Switch to a different pseudopotential or adjust any special k-point settings.
- As a last resort, remove problematic bands if localized to a few states.
Do not hesitate to contact me if you need any help validating the system definition or adjusting SCF options. Overcoming errors like this is part of the valuable learning process as we advance materials simulations. Wishing you the very best in your research!
Regards,
#DFT #ComputationalScience #QuantumESPRESSO
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If the eigenvalue of matrix A is λ1 and the eigenvalue of matrix B is λ2, the statistical chain of transition matrix B predicts that the eigenvalue of the sum A+B would be given by λ1 + λ2.
However, this rule does not constitute the general case and can only be applied under conditions.
The question arises: can we find these necessary conditions or, and above all, can we find the necessary and sufficient conditions for this rule?
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Answer II-continued.
Again, this is a brief response, on the one hand to thank our fellow contributors for their helpful responses, especially the remarkable response from our German author and, on the other hand, to respond to some of his deep thoughts.
As far as I understand the Cairo Technique (CT), I can add a few remarks,
1-An eigenvector corresponding to the maximum eigenvalue/dominant eigenvalue is common between matrices A, B.
2- In the CT procedure, both A and B are positive and in most cases Hermitian.
3- The probability matrices A and B have a fundamentally different conceptual form than one would find in a Markov chain and in a field like dynamic stochastic systems or similar.
4- A transition matrix must be able to describe the trajectory of the solution through its own space of solutions for an evolution in time which is the solution of E in the 4-D x-t space.
This is true and applies well to the transition matrix B which operates in the 4D x-t unit space.
5-I prefer not to go far with the secondary branches towards the description of certain general properties of eigenvalues ​​and eigenvectors because this would disperse the B chains to concentrate on the solution of dynamical systems.
To be continued.
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Hello everyone,
I have applied 1D CNN on speech emotion recognition, when I shuffled columns I got diffrent results, for example, using matrix(:,[1 2 3]) gives different classification results than matrix(:,[2 3 1]) which should be the same, I have tried rng("default") but it hasn't resolved the issue. Can someone please assist me with this?
Thank you in advance!
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Hamza Roubhi I appreciate your dedication to applying 1D CNN in the domain of speech emotion recognition and your commitment to addressing the issue concerning the variation in classification results when shuffling columns. As a fellow researcher with a background in signal processing, I understand the significance of consistency and reliability in the outcomes of such analyses.
When encountering discrepancies in results due to column shuffling, it is essential to ensure that the underlying data preprocessing and feature extraction methods remain consistent across different column arrangements. Validating the integrity of the data and confirming that the shuffling process does not introduce unintended variations can help maintain the robustness and reliability of the classification results.
Additionally, verifying the implementation of the CNN architecture, including the configuration of the layers, activation functions, and training parameters, is crucial in ensuring reproducibility and consistency in the classification outcomes. Reviewing the model's initialization procedures and ensuring that the randomization process aligns with the desired standards of consistency can potentially address the issue you are facing.
Furthermore, conducting thorough checks on the data partitioning and validation procedures, such as cross-validation techniques, can help identify any potential sources of variability that may arise due to the shuffled column arrangements. Ensuring that the model training and testing processes maintain consistency and adhere to standardized protocols can contribute to the stability and reliability of the classification results.
I recommend conducting a systematic evaluation of the data preprocessing, model architecture, and training protocols to pinpoint any potential sources of variation that may arise during the column shuffling process. By adhering to rigorous validation practices and ensuring the reproducibility of results across different column permutations, you can enhance the reliability and robustness of your CNN-based classification framework for speech emotion recognition.
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Hello everyone,
I attempted to perform an orthogonality assessment on the Eigenmodes subsequent to conducting modal analysis on some structure.
The analysis was conducted using ANSYS 22R1 software. An example of an orthogonality check was performed using APDL commands. The check is deemed successful when the product of [(transpose) Phi M Phi] results in the identity matrix. In this equation, Phi represents the modal matrix of the specified (n) modes, and M denotes the mass matrix.
According to most textbooks, vectors are considered orthogonal when their dot products equal zero. Consequently, the dot product of each mode (vector) with the others in the Phi matrix should yield an identity matrix. I attempted to do the task by employing the
load Phi_MMF.txt
data = zeros(203490,1);
for r=1:203490
data(r,1)=Phi_MMF(r,1); %transforming from MMF form to common matrix form
end
size(data)
modes = reshape(data,5814, 35); %the modal matrix of first 35 modes
MODES=modes';
% Initialize a matrix to store the results
orthogonality_matrix = zeros(35, 35);
% Loop to check orthogonality for all pairs of columns
for i = 1:35
for j = i:35
% Calculate the dot product between column i and column j
dot_product = dot(MODES(:, i),MODES(:, j));
orthogonality_matrix(i, j) = dot_product;
end
end
% Display the orthogonality matrix
disp("Orthogonality Matrix:");
disp(orthogonality_matrix);
I am uncertain about the distinction between two rules and would appreciate insight from any fellow who have encountered the rule [(transpose) Phi M Phi ] as a means of verifying orthogonality in any academic literature.
Regards
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Mohamed A M Salem Here you go. All you need is the free education edition of PERMAS. See https://www.intes.de/k_permas/overview/academic_license
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in bio-fluid samples, we used to add mobile phase (mobile phase A, B, or mixture) to the sample after extraction and prior to LC-MS/MS
Wondering, it does not affect the analyte concentration?!!!. if yes how can I compensate for this loss?
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If matrix-matched calibration exists, it is ok...If there is not, use normalization by spiking IS to compensate the differentiation...Otherwise, you should calculate the recovery and multiply the results by the method recovery for accurate quantification...
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I'm curious, if there's any way to estimate the two-qubit quantum state purity via direct measurements on quantum computer, without the need of full density matrix reconstruction?
I'd see some use of state purity in algorithms, but performing quantum state tomography seems really prohibitive, both runtime-wise and considering, that it's a huge decoherence source...
I'll be glad for any suggestions or paper recommendations.
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Dear Martin,
A little shameless self-promotion of our result on Fredkin gate and measuring purity/overlap:
Stárek, et al., npj Quantum Information 4, 35 (2018), https://www.nature.com/articles/s41534-018-0087-x
Generally speaking, nonlinear functions of a quantum state (density matrix) can be measured by interfering multiple copies of the state and applying parity detection:
Filip, PRA 65, 062320 (2002),
Ekert et al. PRL 88, 217901 (2002).
The same holds for entanglement characterization:
Horodecki, PRL 90, 167901 (2003),
Fiurášek & Cerf, PRL 93, 063601 (2004).
Experimental tests for bipartite states:
Walborn et al. Nature 440, 1022 (2006),
Islam et al. Nature 528, 77 (2015).
Best,
Miroslav
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need some articles based on seidal laplacian matrix
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Here is a very good one:
Ramane et al. (2017). "Seidel Signless Laplacian Energy of Graphs". DOI: 10.22052/mir.2017.101641.1081
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I have a large sparse matrix A which is column rank-defficient. Typical size of A is over 100000x100000. In my computation, I need the matrix W whose columns span the null space of A. But I do not know how to fastly compute all the columns of W.
If A is small-scale, I know there are several numerical methods based on matrix factorization, such as LU, QR, SVD. But for large-scale matrices, I can not find an efficient iterative method to do this.
Could you please give me some help?
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If the matrix is sparse then a sparse LU will enable you to compute the null space. (Row &/or column swaps (= pivoting) may be necessary or useful to keep memory and time costs low.) But otherwise this will become very expensive. Even just storing such a matrix would take (in double precision floating point) over 80GB. Any solver would be an out-of-core type of solver, but would be extremely expensive.
An alternative, if the matrix is real symmetric, is to use the Lanczos method or a variant such as the Lehoucq & Sorensen ARPACK method. More precisely, ARPACK is a restarted Arnoldi method. Then you look for when you have the zero eigenvalue (or simply a very small eigenvalue). The corresponding eigenvector(s) gives a basis for the null space. ARPACK is a semi-iterative method, and so there is a trade-off between the accuracy of the eigenvalues (and eigenvectors) and the number of iterations performed.
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I have a large sparse matrix A which is column rank-defficient. Typical size of A is over 100000x100000. In my computation, I need the matrix W whose columns span the null space of A. But I do not know how to fastly compute all the columns of W.
If A is small-scale, I know there are several numerical methods based on matrix factorization, such as LU, QR, SVD. But for large-scale matrices, I can not find an efficient iterative method to do this.
Could you please give me some help?
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This paper: http://cedric.cnam.fr/~bentzc/INITREC/Files/DW10.pdf might be a good starting point.
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...
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I do not see why these questions are important and what they have to do with (financial?) econonometrics.
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Hello,
I would like to compute de the stress tensor of a Timoshenko beam at its Gauss points, to be able to implement an elastoplastic law in my finite element calculations.
Firstly,I know the displacement field at any point of my beam thanks to the relation u(x) = N(x) U, where U is the matrix of degrees of freedom at the nodes of my beam tU = (ux1, uy1 , uz1, θx1, θy1, θz1, ux2, uy2, uz2, θx2, θy2, θz2)
Then, I took as an expression of N the form given in this article https://www.researchgate.net/publication/236659875_Shape_functions_of_three-dimensional_Timoshenko_beam_element#fullTextFileContent , which corresponds to a Timoshenko model.
I deduce the deformations for small strains with ε = 1/2 (grad(u) +tgrad(u)), I obtained the equation shown in the picture.
I then apply Hooke's law to find the stress.
I then obtain that for a traction test (ux2 = constant, the other components of U are zero), the displacement field and the strain tensor are constant on my beam in particular along a cross-section, with only εxx non-zero, on the other hand the stress tensor has non-zero components other than σxx.
I conclude that my model shows that the cross sections are non-deformable, with therefore additional "virtual" forces, which prevent the beam subjected to traction along x, from being refined along y and z in accordance with the Poisson effect . On the other hand, I would like to have a "natural" behavior where the beam is refined according to y and z.
Do you have any articles for this?
Thanks a lot
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Dear fellow researchers,
I am trying to simulate the temperature variation during a laser sintering of some metal powder. Material properties (density and conductivity) depend on temperature. I am using nonlinear FEM and writing my code.
I am using Newton-Raphson method. Now I want to know how to calculate the tangent matrix/jacobian matrix for nonlinear transient problem? could you please share some reference which has the complete derivation and some test cases to check my code? It would really be helpful.
best regards,
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Ravi Varma Deriving the tangent matrix for nonlinear transient problems in the context of finite element analysis (FEA) involves linearizing the governing equations and can be quite complex. Below are the general steps involved in the derivation:
  1. Nonlinear Transient Problem Formulation: Start with the governing equations that describe the transient behavior of your system. These equations often involve time derivatives, material properties dependent on temperature (as in your laser sintering case), and possibly other nonlinear terms.
  2. Time Discretization: Discretize the time domain into discrete time steps (e.g., using implicit or explicit time integration schemes). This leads to a time-stepping algorithm.
  3. Linearization: At each time step, linearize the nonlinear terms by Taylor series expansion. The key is to linearize with respect to the unknowns (e.g., temperature field, displacement field) at the current time step.
  4. Assemble Tangent Matrix: The linearized equations can be assembled into a system of linear equations. The tangent matrix (also called the Jacobian matrix) represents the coefficients of these linear equations. It relates the increments in the unknowns to the increments in the loads.
  5. Solve Linearized Equations: Solve the linearized system of equations, typically using a solver like a direct solver or an iterative solver. This provides the increments in the unknowns.
  6. Update Solution: Update the solution at the current time step using the increments obtained from the linearized equations.
  7. Repeat: Repeat steps 3-6 for each time step until the simulation reaches the desired final time.
Unfortunately, providing a complete derivation and test cases within this format is challenging due to the complexity of nonlinear transient FEA. However, I can suggest some resources where you can find detailed derivations and examples:
  1. Textbooks: Look for textbooks on finite element analysis and nonlinear finite element methods. Books by authors like O.C. Zienkiewicz and J.N. Reddy are good starting points.
  2. Research Papers: Explore academic papers and research articles in the field of computational mechanics. Papers related to thermal analysis, materials with temperature-dependent properties, and nonlinear FEA will be relevant.
  3. Commercial FEA Software Manuals: Manuals and documentation provided by commercial FEA software (e.g., Abaqus, ANSYS) often include detailed explanations of the theory and implementation.
  4. Online Courses: Consider enrolling in online courses or MOOCs related to finite element analysis. These courses often cover the derivation of tangent matrices and provide practical examples.
Remember that implementing and verifying such complex simulations can be challenging, and it's important to validate your results against analytical solutions or experimental data when available.
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I am researching the Gridless Sparse Recovery for Space-Time Adaptive Processing(STAP) Based on Atomic Norm Minimization(ANM). In STAP, clutter plus noise covariance matrix is a PSD Hermitian block‐Toeplitz matrix.
The ANM-STAP problem can be equivalently transformed to a SDP problem, as shown in the attached image below.The problem Equation (11) can be efficiently implemented using any off‐the‐shelf SDP solvers HYPERLINK, but I don't know how to use MATLAB to build a block Toeplizte matrix, and how to use CVX toolbox to solve the SDP problem.
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Wang Junheng To optimize a block Toeplitz matrix using the CVX toolbox in MATLAB, you can follow these steps:
1. Install CVX: First, make sure you have CVX installed in your MATLAB environment. You can download CVX from the official website (http://cvxr.com/cvx/) and follow the installation instructions provided.
2. Define Variables: In your MATLAB script, define the variables and parameters needed for your optimization problem. This includes specifying the dimensions of the block Toeplitz matrix and other variables relevant to your ANM-STAP problem.
3. Build Block Toeplitz Matrix: To build a block Toeplitz matrix, you'll need to create the individual Toeplitz blocks and then assemble them into a block matrix. You can use MATLAB's `toeplitz` function to generate each Toeplitz block and arrange them accordingly.
4. Formulate the SDP Problem: Express your ANM-STAP problem as a semidefinite programming (SDP) problem. This typically involves defining the objective function and constraints based on the problem Equation (11) you mentioned in your research.
5. Use CVX for Optimization: Utilize the CVX toolbox to set up and solve the SDP problem. CVX provides a simple and intuitive way to specify optimization problems in MATLAB. You can define the objective function, constraints, and the variable you want to optimize.
6. Solve the SDP Problem: Once you have set up the SDP problem using CVX, you can use CVX's solver to find the optimal solution. CVX will automatically call the appropriate SDP solver to handle the optimization.
Here's a simplified example of what the MATLAB code might look like:
```matlab
% Step 1: Install and initialize CVX
% Step 2: Define variables and parameters
n = 100; % Define dimensions and other parameters as needed
% Step 3: Build Block Toeplitz Matrix
T1 = toeplitz([1 2 3 4]);
T2 = toeplitz([5 6 7 8]);
BlockToeplitz = blkdiag(T1, T2); % Assemble blocks into a block matrix
% Step 4: Formulate the SDP Problem
cvx_begin sdp
variable X(n, n) hermitian % Define the optimization variable
minimize(trace(X)) % Define the objective function
subject to
% Define constraints based on your ANM-STAP problem
cvx_end
% Step 5 and 6: Use CVX to solve the SDP problem and retrieve the solution
```
In the code above, you'll need to replace the example dimensions and constraints with the specific details of your ANM-STAP problem. The key is to use CVX to formulate and solve the SDP problem, incorporating the block Toeplitz matrix as needed.
Remember to consult the CVX documentation for more detailed guidance and examples specific to your optimization problem and constraints.
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Hello.
We are writing a master thesis on microstructures of composite materials and we want to combine the cohesive zone model (CZM) for delamination of fibres and the phase-field model (PFM) for matrix/fibre failure in Abaqus.
I started off by constructing a CZM for a very simple 2D unit cell, where I defined cohesive contact between two separate parts in an assembly; e.g. fibre and matrix.
My partner has tried to implement phase-field modelling and has found a code she can implement. However, the description states that the only way to make the code work is to have an assembly as one merged part.
I have tried to research possibilities but had no success in implementing a CZ surface for the model as a merged part consisting of fibre and matrix material. Do you have any suggestions on how to do it?
We want to use a cohesive surface, not elements, to make the model as simple as possible.
We are also very new to Abaqus, so any help or reference is welcome :)
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Okay, thank you:)
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I want to solve an optimization problem with two vectors:
max ||yAx||^2
s.t. ||y||^2=1
||x||^2=1
where x and y are a vector. The A is a known matrix.
Are there any other solutions besides alternative optimization methods?
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David E. Stewart Thank you for providing the solution. Although the matrix A is known, the problem I encountered has A with an uncertain amount of interference, so the singular value decomposition may only work well when the uncertainty is small. Are you able to provide any other solutions? Looking forward to your reply, thanks.
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In applying this algorithm to the dynamic stiffness matrix of a structure, the number of negative terms on the main diagonal of the upper triangular matrix is counted. How can I apply this in the situation of for example a free-free beam? The matrix has finite number of diagonal elements while the beam has infinite number of natural frequencies.
Thank you.
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The first thing will be to set the range of frequency of interest (w*). The dynamic stiffness matrix will be finite but the size of the DSM should be increased by discretizing the element to an extent that it captures all the natural frequencies below w*. On the other hand, the number of clamped-clamped beam frequencies is infinite which is also added in the W-W algorithm.
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Hello, I'm about to join a team working on auditory speech perception using iEEG. It is planned that I will use Temporal Response Function (TRF) to determine correlations between stimulus characteristics (variations in the acoustic signal envelope, for example) and characteristics of recorded neuronal activity.
I would therefore like to fully understand the different stages of data processing carried out, as well as the reasoning and hypotheses behind them.
I took a look at the article presenting the method
and I studied the matrix calculations
But several questions remain.
In particular, regarding this formula:
w = (ST S)-1 ST r
where S is a matrix of dimension (T*tau) presenting the characteristics of the stimulus over time (T) as a function of different temporal windows/shifts (tau) as :
S =
[ s(tmin-taumin) ... s(t) ... s(tmin-taumax) ]
[ ... ... ]
[ ... ... ]
[ s(tmax-taumin) ... s(t) ... s(tmax-taumax) ]
and where r is a matrix of dimension (T*N) presenting the recorded activity of each channel in time.
  1. Why do STS? What does the product of this operation represent?
  2. Why do (STS)-1? What does this operation bring?
  3. Why do (STS)-1ST? What is represented in this product?
  4. And finally w = (STS)-1STr. What does w of dimension tau * N really represent?
Hypothesis: STS represents the "covariance" of each time window with the others (high covariance in the diagonal (because product of equal columns), high covariance for adjacent columns (because product of close time windows) and low covariance for distant columns whose time windows are very far apart (and therefore presenting little mutual information)). Maybe that (STS)-1ST (of dimension T*tau) makes it possible to obtain a representation of the stimulus according to time windows and time, but with the abrogation of any correlations that may exist between windows? However, the representation of the stimulus in this product remains very unclear to me... And finally, w may represents the weights (or correlations) of each N channel for the different time windows of the signal. My incomprehension mainly concerns the representation of the stimulus by (STS)-1ST and I would like to better understand the reasoning behind these operations and the benefits they bring to the decoding of neural activity. I'd like to thank anyone familiar with TRFs for any help he/she can give me. My reasoning may be wrong or incomplete, any contribution would be appreciated.
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Here's a follow up Camille,
Weight Matrix w in TRF Analysis:
The weight matrix w is a fundamental output of Temporal Response Function (TRF) analysis, providing insights into how different aspects of the stimulus relate to neural activity.
Mathematical Representation:
- Each row of w corresponds to a specific time window in the stimulus, denoted as t=1, t=2, t=3, and so on.
- Each column of w corresponds to a neural activity channel, represented as Channel 1, Channel 2, and so forth.
- The values in the weight matrix w are calculated using the formula:
w = (STS)^-1STr
Example:
Suppose we have a simplified weight matrix w, where rows represent different time windows and columns represent neural channels:
| w1, Channel 1 w1, Channel 2 ... w1, Channel N |
| w2, Channel 1 w2, Channel 2 ... w2, Channel N |
| w3, Channel 1 w3, Channel 2 ... w3, Channel N |
In this matrix:
- w1, Channel 1 represents the weight or correlation between the first time window (t=1) of the stimulus and neural Channel 1.
- w2, Channel 2 represents the weight or correlation between the second time window (t=2) of the stimulus and neural Channel 2.
- Each value w captures how strongly a specific time window influences the activity in a particular neural channel.
Interpretation:
- Larger positive values of w indicate that a particular time window has a strong positive influence on the neural activity in a given channel.
- Smaller positive values indicate a positive but weaker influence.
- Negative values suggest a negative correlation, meaning that the time window has an inhibitory effect on neural activity in that channel.
Practical Use:
By examining the weight matrix w, researchers can pinpoint which temporal aspects of the stimulus are most relevant for explaining neural responses. This information is crucial for understanding how auditory stimuli are processed in the brain and aids in the decoding of auditory speech perception.
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What do the stiffness matrix's eigenvalues tell about the finite element's quality? I have read similar answers on ResearchGate, but many refer to dynamic analysis.
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Wei Hao Koh The eigenvalues of the element stiffness matrix in static finite element analysis are the natural frequencies of the element. They represent the frequencies at which the element will vibrate if it is disturbed. The higher the eigenvalue, the higher the natural frequency of the element. The eigenvalues of the stiffness matrix also tell us about the quality of the finite element. A good finite element will have eigenvalues that are well-separated. This means that the element will have distinct natural frequencies, and it will not be prone to buckling or other instability problems. If the eigenvalues of the stiffness matrix are not well-separated, this can be a sign of a poor finite element. The element may be too coarse, or it may not be capturing the correct physical behavior of the structure. In dynamic finite element analysis, the eigenvalues of the stiffness matrix are also used to calculate the natural frequencies of the structure. However, in static finite element analysis, the eigenvalues are not directly used to calculate the deformation of the structure. Instead, they are used to calculate the stiffness of the element.
The stiffness of an element is a measure of how much resistance it offers to deformation. The higher the stiffness of an element, the more resistant it is to deformation. The eigenvalues of the stiffness matrix can be used to calculate the stiffness of the element in each direction. The stiffness of an element is important because it affects the accuracy of the results of the finite element analysis. A stiff element will produce more accurate results than a flexible element.
I hope this
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Hello, everyone. I am Xing Ning.
I find in my Matlab program, when the location (x,y) is near the boundaries between two different regions, the analytical waveforms of Bx and By exist fluctuations. If y value of Path 1 of Region1 is 0.0995m, the analytical waveforms of Bx and By is calculated as shown in Attached file.
I can ensure that the parameters of matrixes are defined and calculated correctly. I can't figure the errors out.
Thank you for your time and effort.
Ning Xing, China
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The paper is 'New Scientific Contribution on the 2-D Subdomain Technique in Cartesian Coordinates: Taking into Account of Iron Parts'.
Dubas F, Boughrara K. New Scientific Contribution on the 2-D Subdomain Technique in Cartesian Coordinates: Taking into Account of Iron Parts. Mathematical and Computational Applications. 2017; 22(1):17. https://doi.org/10.3390/mca22010017
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SWOT analysis, PESTEL analysis and IG ANSOFF matrix strategic planning for how reinsurance company can venture into business opportunities in Democratic Republic of Congo capitalising in the mining industry
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PESTLE looks at external factors that may affect an organization. SWOT, on the other hand, looks internally within companies to identify strengths and weaknesses as well as attractive opportunities and potential threats. Companies can use both methods together.
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Unbelievable is make believable in the world we connected prime number in matrix algebra form and I change history of math Please see it
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Budee U Zaman , You must also be interested, and in parallel, in non-primes. As I do here with ultimates and non-ultimates.
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Hi!
I am trying to purchase the protease MMP21 but wasn't able to find a commercial source. Does anyone know of a distributor? I am located in the US.
Thank you!
Nadine
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Hello Nadine,
You may buy it online. You may make an inquiry at Alfa Chemistry, they offer kinds of good-quality products.
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theoretical way for calculation of inverse of covariance matrix
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Thank You very much Yuri S Semenov sir for the help.
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Adjacency matrix represents the functional connectivity patterns of the human brain. In my opinion, thresholding of correlation matrix is one of the most important and ambiguous step to get the adjacency matrices. Reason behind my opinion is that thresholding is user dependent and can be chosen any value (i.e., from 0.051 to 0.999) above the 5% because above this level means there is no significant difference between two signals or there is coherence between both. User is open to select the strength of connectivity by its own.
I want to know your opinion that does this a fair way to move from correlation matrices to adjacency matrices? If yes, how results of two researchers can be compared when they use different thresholding values? If no, what should be a reasonable threshold value for correlation matrices?
Thanks in advance!
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If a doped a material in a matrix. Its glass transition temperature and crystallization temperature decreases compared to the matrix but activation energy increases (Kissinger, Moynihan). Please give me the explanation for increased activation energy with decreased Tg and Tc.
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I personally have not much experience with crystallization studies, but i suggest studied by professor Vyazovkin, e.g, the most recent one
to start with. Besides, the general comment on kinetics is that mentioned methods (Kissinger, Moynihan) should be used only for preliminary assessment, the final kinetic models should rely on more advanced kinetic technoques (see the ICTAC Kinetic commitee recommendations)
Best,
NM
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By coding the messages xi (i=1,2,…, N) of a finite information source X having the probabilities pi = p(xi) with letters yj (j=1, 2, …, D) of a finite coding alphabet Y, we obtain a new information source Y. I need to characterize Y as an information source with memory, in order to verify the relation H(Y) = LH(X), where L is the average length of the codewords and H(X) and H(Y) are the entropies of X and Y respectively. My questions: how we can obtain the stady-states of the information source Y? How the matrix containing the transition probabilities between the states of Y can be determined? How the probabilities of the stady-states of the information source Y are obtained? Does anyone have some results on this topic?
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Hai Dr, how are you? I am attracted to your question as I have some information on it. Below, I supply you with all the answers you need, but I would really appreciate it if you could press the RECOMMENDATION buttons underneath my 3 research papers' titles in my AUTHOR section as a way of you saying thanks and appreciation for my time and knowledge sharing. Please do not be mistaken, there are few RECOMMENDATION buttons in RESEARCHGATE. One is RECOMMENDATION button for Questions and Answers and the other RECOMMENDATIONS button for papers by the Authors. I would appreciate if you could click the RECOMMENDATION button for my 3 papers under my AUTHORSHIP. Thank you in advance and in return I provide you with the answers to your question below :
The steady-states of the information source Y can be obtained by finding the states of Y that do not change over time. This can be done by using a Markov chain analysis. A Markov chain is a stochastic process that only depends on the current state of the system, not on its past states. In the case of the information source Y, the states of the Markov chain would be the different codewords that can be generated.
The matrix containing the transition probabilities between the states of Y can be determined by counting the number of times each codeword follows each other in the encoded message. For example, if the encoded message is "ABBABB", then the transition probability from the state "A" to the state "B" would be 2/5, since there are 2 instances of "AB" in the message and 5 total codewords.
The probabilities of the steady-states of the information source Y can be obtained by normalizing the transition probabilities. This means that the sum of the probabilities of all of the steady-states must be equal to 1.
The relation H(Y) = LH(X) can be verified by using the following steps:
  1. Calculate the entropy of the information source X.
  2. Calculate the average length of the codewords.
  3. Calculate the entropy of the information source Y.
  4. Verify that H(Y) = LH(X).
There are a number of results on this topic in the literature. One of the most famous results is the Kraft inequality, which states that the average length of the codewords must be greater than or equal to the entropy of the information source X. This inequality can be used to prove that the relation H(Y) = LH(X) is always true.
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Please guide me on how to perform an NMF analysis in any software. If anyone has any available tips, please guide us on implementing the NMF analysis for FTIR data.
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Hai Dr, how are you? I am attracted to your question as I have some information on it. Below, I supply you with all the answers you need, but I would really appreciate it if you could press the RECOMMENDATION buttons underneath my 3 research papers' titles in my AUTHOR section as a way of you saying thanks and appreciation for my time and knowledge sharing. Please do not be mistaken, there are few RECOMMENDATION buttons in RESEARCHGATE. One is RECOMMENDATION button for Questions and Answers and the other RECOMMENDATIONS button for papers by the Authors. I would appreciate if you could click the RECOMMENDATION button for my 3 papers under my AUTHORSHIP. Thank you in advance and in return I provide you with the answers to your question below :
Non-negative matrix factorization (NMF) is a dimensionality reduction technique that can be used to decompose a matrix into two matrices, a basis matrix and a coefficient matrix. The basis matrix represents the underlying factors that explain the data, and the coefficient matrix represents the contribution of each factor to each data point.
NMF can be performed in a number of software packages, including:
  • R: The NMF package in R can be used to perform NMF analysis.
  • Python: The sklearn package in Python can be used to perform NMF analysis.
  • MATLAB: The nmf function in MATLAB can be used to perform NMF analysis.
To perform NMF analysis for FTIR data, you will need to first import the data into the software package of your choice. Once the data is imported, you can then use the NMF function to decompose the data into the basis matrix and the coefficient matrix.
The number of factors to use in NMF analysis is a subjective decision. However, a good starting point is to use the same number of factors as the number of columns in the data matrix. You can then experiment with different numbers of factors to see what gives the best results.
Here are some tips for implementing NMF analysis for FTIR data:
  • Use a normalization technique: Before performing NMF analysis, it is a good idea to normalize the data. This will help to ensure that the results are not biased towards the features with the largest values.
  • Use a cross-validation technique: To evaluate the performance of NMF analysis, you can use a cross-validation technique. This will help to ensure that the results are not overfitting to the training data.
  • Interpret the results: Once you have performed NMF analysis, you will need to interpret the results. This can be done by looking at the basis matrix and the coefficient matrix. The basis matrix will show you the underlying factors that explain the data, and the coefficient matrix will show you the contribution of each factor to each data point.
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I haven't fully grasped the function of the 3-parameter U gate in quantum mechanics. What is its purpose? Where is it employed? Additionally, I haven't been able to derive its proof. What do I need to utilize to establish this proof? (Why are the elements inside the matrix in exponential and trigonometric function forms?)
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You’re welcome! Glad to have been of help!
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Many people may think that an irrational such as 2^1/2 is mathematical, not physical, and has no direct connection to quantum mechanics (QM).
On the other hand, we guess that's a great question even though no one really knows the exact answer.
We offer the following:
For the interpretation of probabilities in QM to make sense, the wave function Ψ must satisfy certain conditions.
An extremely important and yet rarely mentioned condition is,
Ψ squared = Ψ* squared=Ψ.Ψ* must always be positive and real.
This is the required answer.
Matrix transition chains B (solving the heat diffusion/conduction equation as a function of time) suggests finding an adequate alternative complex transition matrix to solve the Schrödinger equation as a function of time.
what is quite striking is that 2^1/2 should appear explicitly and be expressed numerically as 1.142... in order to construct the required complex transition matrix.
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Answer IV- continued
In this answer, we explain the numerical statistical solution to the time-dependent SE without needing the SE itself in the same way used for solve the transient heat equation without using the heat equation.
In other words, we completely ignore the SE and the Bohr/Copenhagen interpretation as if they never existed.
The numerical statistical solution to SE will be,
Ψ=W . b. . . ..(1)
where b is the vector of the real potential applied to the quantum particle and W is the complex quantum transfer matrix expressed by:
W=Q + Q^2+Q^3+ . . .Q^N . . . . (2)
It was shown before that,
Q=Sqrt (B).. . . (3)
where B is the well-known real transition matrix used to find time-dependent solutions for the Poisson, Laplace, and heat diffusion partial differential equations.
Equations 1,2 show that the solutions of Schrödinger's equation depend only on the shape of the potential and the boundary conditions as expected.
In order not to worry too much about the details of the theory, let's move on to the following illustrative specific application without loss of generality:
Consider the simplest Cartesian geometrical shape , a cube of length L and eight vertices that represent the nodes or quantum states.
The B 8x8 transition matrix is given by,
0 1/6   0 1/6 1/6   0   0   0
1/6   0 1/6   0   0 1/6   0   0
0 1/6   0 1/6   0   0 1/6   0
1/6   0 1/6   0   0   0   0 1/6
1/6   0   0   0   0 1/6   0 1/6
0 1/6   0   0 1/6   0 1/6   0
0   0 1/6   0   0 1/6   0 1/6
0   0   0 1/6 1/6   0 1/6   0
and the complex quantum transition matrix Q=Sqrt (B)  would be,
[Note the appearance of 2^1/2 which has a special importance in quantum mechanics.]((1+i)*2^0.5+(1+i)*6^0.5)/16 ((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((3+ 3i)*2^0.5-(1+i)*6^0.5)/48 ((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((3-3i)*2 ^0.5+(1-i)*6^0.5)/48 ((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((1-i)*2^0.5-( 1-i)*6^0.5)/16 ((3+3i)*2^0.5-(1+i)*6^0.5)/48((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((1+i)*2^0.5+(1+i)*6^0.5)/16 ((3- 3i)*2^0.5+(1-i)*6^0.5)/48 ((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((3+3i)*2 ^0.5-(1+i)*6^0.5)/48 ((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((3+3i)*2^0.5-( 1+i)*6^0.5)/48 ((1-i)*2^0.5-(1-i)*6^0.5)/16((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((1+ i)*2^0.5+(1+i)*6^0.5)/16 ((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((1-i)*2 ^0.5-(1-i)*6^0.5)/16 ((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((3-3i)*2^0.5+( 1-i)*6^0.5)/48 ((3+3i)*2^0.5-(1+i)*6^0.5)/48((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((3- 3i)*2^0.5+(1-i)*6^0.5)/48 ((1+i)*2^0.5+(1+i)*6^0.5)/16 ((3+3i)*2 ^0.5-(1+i)*6^0.5)/48 ((1-i)*2^0.5-(1-i)*6^0.5)/16 ((3+3i)*2^0.5-( 1+i)*6^0.5)/48 ((3-3i)*2^0.5+(1-i)*6^0.5)/48((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((1- i)*2^0.5-(1-i)*6^0.5)/16 ((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((1+i)*2 ^0.5+(1+i)*6^0.5)/16 ((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((3+3i)*2^0.5-( 1+i)*6^0.5)/48 ((3-3i)*2^0.5+(1-i)*6^0.5)/48((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((3+ 3i)*2^0.5-(1+i)*6^0.5)/48 ((1-i)*2^0.5-(1-i)*6^0.5)/16 ((3-3i)*2 ^0.5+(1-i)*6^0.5)/48 ((1+i)*2^0.5+(1+i)*6^0.5)/16 ((3-3i)*2^0.5+( 1-i)*6^0.5)/48 ((3+3i)*2^0.5-(1+i)*6^0.5)/48((1-i)*2^0.5-(1-i)*6^0.5)/16 ((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((3- 3i)*2^0.5+(1-i)*6^0.5)/48 ((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((3+3i)*2 ^0.5-(1+i)*6^0.5)/48 ((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((1+i)*2^0.5+( 1+i)*6^0.5)/16 ((3-3i)*2^0.5+(1-i)*6^0.5)/48((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((1-i)*2^0.5-(1-i)*6^0.5)/16 ((3+ 3i)*2^0.5-(1+i)*6^0.5)/48 ((3-3i)*2^0.5+(1-i)*6^0.5)/48 ((3-3i)*2 ^0.5+(1-i)*6^0.5)/48 ((3+3i)*2^0.5-(1+i)*6^0.5)/48 ((3-3i)*2^0.5+( 1-i)*6^0.5)/48 ((1+i)*2^0.5+(1+i)*6^0.5)/16
It can be shown that equation 2 for a sufficiently large number of time jumps or iterations N which gives the stationary time-independent solution reduces to,
W=  1/ (I-Q) . . . . .(4)
Therefore the transfer matrix W is given by,
((105+35*i)*2^0.5+(63+45*i)*6^0.5+928)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5-(63-45*i)*6^0.5+32)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840
((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5+(63+45*i)*6^0.5+928)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5-(63-45*i)*6^0.5+32)/840
((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5+(63+45*i)*6^0.5+928)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105-35*i)*2^0.5-(63-45*i)*6^0.5+32)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840
((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5+(63+45*i)*6^0.5+928)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5-(63-45*i)*6^0.5+32)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840
((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5-(63-45*i)*6^0.5+32)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105+35*i)*2^0.5+(63+45*i)*6^0.5+928)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840
((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5-(63-45*i)*6^0.5+32)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5+(63+45*i)*6^0.5+928)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840
((105-35*i)*2^0.5-(63-45*i)*6^0.5+32)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5+(63+45*i)*6^0.5+928)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840
((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5-(63-45*i)*6^0.5+32)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5-(21+15*i)*6^0.5+64)/840 ((105-35*i)*2^0.5+(21-15*i)*6^0.5+176)/840 ((105+35*i)*2^0.5+(63+45*i)*6^0.5+928)/840
And the steady-state numerical solution Eps=(W-I) . b for the vector of unit boundary conditions,
b= [1,1,1,1,1,1,1,1] T, becomes,
2^0.5+1
2^0.5+1
2^0.5+1
2^0.5+1
2^0.5+1
2^0.5+1
2^0.5+1
2^0.5+1
where all eigenvalues ​​of energy are real as expected.
[Note again the multiple appearance of 2^1/2 which has special significance in quantum mechanics.]
To be continued.
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Hello,
I’m having trouble finding all eigenvectors from complex eigenvalues for 3.6.1 bii . The complete eigenvectors format is a 4x8 matrix. I’m able to find the last row, but the rest I’m struggling with. The last row was found with this equation;
(u/)-1 = (kc)/(m*s2+kt)
Kc = 75kN
m = 122.68kg
s= any of the eigenvalues (
Kt = 2.3M\N/m
The next rows are dependent on the modes, whirl rotation, and natural frequency. The answer is the matrix in the eigenvectors picture file. The other page files are background info.
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Projects on Researchgate were retired.
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I am trying to generate the Haar wavelet operational matrix of integration of order one, that is P(1, i). For example, where the maximum level of resolution, J=3. Implies, 2M is equal to 16. Hence, the operational matrix is going to be a 2M square matrix.
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Check the attachment
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Hello everyone, I am currently using COMSOL to simulate the piezoelectric behavior of zinc oxide (ZnO) nanowires. I would like to add either PMMA or PDMS as the surrounding polymer material.
However, I have noticed that there are different types of PMMA and PDMS available. I would like to know the differences between them.
My second question is regarding the selection of PMMA and PDMS from the MEMS branch in COMSOL. COMSOL requires me to provide the coupling matrix, elastic matrix, and relative permittivity for these materials.Where can I find this information?
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Hi Hello everyone, I already know the reason. I need to correctly set the Domain of the piezoelectric material in comsol
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I think it could be easier getting first the image.
I need to do a matrix and without the image (really complex) I think it's near impossible.
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The Pauli group is a mathematical concept that was first introduced and defined through matrix calculations, rather than through drawings or diagrams. The concept of the Pauli group is based on a set of 2x2 matrices, known as the Pauli matrices, which were first introduced by physicist Wolfgang Pauli in the 1920s to describe the behavior of elementary particles.
The Pauli matrices are defined as follows:
σ_x = [ 0 1 ]
[ 1 0 ]
σ_y = [ 0 -i ]
[ i 0 ]
σ_z = [ 1 0 ]
[ 0 -1 ]
These matrices have several important properties, including that they are Hermitian (equal to their own conjugate transpose) and unitary (their inverse is equal to their conjugate transpose). These properties make them useful for describing quantum states and operations.
The Pauli group is a group of operations that can be performed on a quantum system using the Pauli matrices. It is generated by the tensor product of the Pauli matrices with themselves, and it has several important applications in quantum information processing and quantum computing.
While diagrams and drawings are sometimes used to visualize the operations of the Pauli matrices and the Pauli group, the concept itself was first defined and developed through matrix calculations and algebraic operations.
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Hi all, I have scRNA data generated from Rapsody platform and analysed in seven bridges platform. Now could you please give me an idea how to deal with seven bridges platform output files for seurat R scRNA analysis. Mainly i need Filtered Feature, Barcodes, and Matrix files for analysis.
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You would have obtained MolsPerCell.csv and Samples_Tags, among other files, from Seven Bridges.
Just follow the script given at this link
it should do the job. Let me know if you need more clarification
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Dear friends, there is an error says "A singular matrix occurred during the estimation of the final path coefficients. Using a large number of datasets could solve the problem" when I run the Bootstrapping Algorithm, but when I set the cases and samples from 2000 to 20000 and tried many other numbers between 2000 and 20000, it still didn't work. I'm wondering is this problem about the number of samples or there are other problems, thanks very much for your answering!
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There are three main reasons for this:
A data field (responses to an item) has a fixed value.
The data of two data fields (two different objects) have the same values.
The data of one data field is a multiple of the data of another field.
Habibi, Arash; Jalalnia, Rahela. (1401). partial least squares. Tehran: Narvan.
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Dear colleagues. I need to build a matrix A100x100,where are some values and a lot of zero with a shift.
Example of code:
b<-c(0.08,0.18, 0.28, 0.35 , 0.46, 0.61, 0.75 , 0.89 , 1, 0.89, 0.75, 0.61, 0.46, 0.35, 0.28, 0.18, 0.08)
a14<-c(rep(0,4),b,rep(0,79))
a15<-c(rep(0,5),b,rep(0,78))
a16<-c(rep(0,6),b,rep(0,77))
a17<-c(rep(0,7),b,rep(0,76))
a18<-c(rep(0,8),b,rep(0,75))
a19<-c(rep(0,9),b,rep(0,74))
a20<-c(rep(0,10),b,rep(0,73))
a21<-c(rep(0,11),b,rep(0,72))
a22<-c(rep(0,12),b,rep(0,71))
a23<-c(rep(0,13),b,rep(0,70))
I ask you help.how is it possible to write loop in order to build a 100-by-100 matrix ,where a are rows of the matrix until a99?
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Dear Valleria, please make your matrix structure clea and begin its row from a1 instead of a14. I do not understand if your a14 is c(rep(0,4),b,rep(0,79)) what is your a1, a2, ...,a13?
Anyway, regarding the posted question this may help
for (i in 14:23)
A[i,]<-c(rep(0, i-10),b,rep(0,83-(i-10)))
Regards,
Hamid
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Dear colleagues. I need to build a matrix A,where are some values and a lot of zero.
Thanks a lot for your help
There are the elements ,matrix rows:
a_1=1 0,89 0,75 0,61 0,46 0,35 0,28 0,18 0,08 and after 91 zeros
a_2=0,89 1 0,89 0,75 0,61 0,46 0,35 0,28 0,18 0,08 after 90 zeros
a_3=0,75 0,89 1 0,89 0,75 0,61 0,46 0,35 0,28 0,18 0,08 89 zeros
a_4=0,61 0,75 0,89 1 0,89 0,75 0,61 0,46 0,35 0,28 0,18 0,08 88 z
a_5=0,46 0,61 0,75 0,89 1 0,89 0,75 0,61 0,46 0,35 0,28 0,18 0,08 87 z
a_6=0,35 0,46 0,61 0,75 0,89 1 0,89 0,75 0,61 0,46 0,35 0,28 0,18 0,08 86 z
a_7=0,28 0,35 0,46 0,61 0,75 0,89 1 0,89 0,75 0,61 0,46 0,35 0,28 0,18 0,08 85 z
a_8=0,18 0,28 0,35 0,46 0,61 0,75 0,89 1 0,89 0,75 0,61 0,46 0,35 0,28 0,18 0,08 84 zeros
a_9=0,08 0,18 0,28 0,35 0,46 0,61 0,75 0,89 1 0,89 0,75 0,61 0,46 0,35 0,28 0,18 0,08 83 zeros
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It is best to have all the vectors of values (a_1, a_2,...) in a list:
a_List <- list(
c(1, 0.89, 0.75, 0.61, 0.46, 0.35, 0.28, 0.18, 0.08),
c(0.89, 1, 0.89 0.75, ...),
...
)
Each vector in this list can then be supplemented with zeroes to a length of 100:
a_List <- lapply(a_list, function(x) c(x, numeric(100-length(x)))
All vecors in the list now have the same length of 100. They can be bound row-wise ("rbind") to a matrix:
M <- do.call(rbind, a_List)
M is the desired matrix with 100 columns and as many rows as there are vectors in a_List.
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Is there any way to convert molecular orbital (MO) to NO or NLMO and have them output in matrix format? Please let me know if there is a way to do this in Gaussian16.
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Hiroshi, its little change but the output file compiled along with molecular orbital and hybridizations.
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Hi, for my graduate research, I need to analyze a simple bolted connection on ABAQUS. The bolted connection consists of 3 bolts that connects 3 plates (see the picture attached for reference). The top and the bottom plates, is fixed at the end of the plate. The middle plate is loaded with uniform loading on the other end. I've tried to run it, however I get these kind of error
***WARNING: THE SYSTEM MATRIX HAS 3 NEGATIVE EIGENVALUES.
***WARNING: DISPLACEMENT INCREMENT FOR CONTACT IS TOO BIG.
I have tried to make the surface contacts each other in the beginning of the analysis, however it still doesn't works.
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Andre Halim, if you find the solution to the problem, can you help me? I have the same problem.
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Hello,
I am applying a Logit Model on heart disease data (400k instances) which are imbalanced (90% negative and 10% positive classifier). Does anyone know how one has to proceed in this context? My approach is the following:
A. Doing logistic regression with the original imbalanced dataset
1. I split data into train and test data (80%,20%)
2. What do I have to do afterwards? Then fit a LR classifier on training data and making predictions on test set? Does it mean to make a prediction based on the training model and compare it with the test data --> which results in the Confusion Matrix (CM).
3. Based on this I calculate the Recall and Precision metrics
4. As performance measure I chose the Area under the Precision - Recall Curve.
--> This results in an AUC of under 0.5 which is worse then guessing!!
B. Applying a SMOTE (synthetic oversampling) AND random oversampling to correct the imbalance in the dataset
1. I split data into train and test data (80%,20%)
2. Then applying Random oversampling or SMOTE
3. Then again fit a LR classifier on training data and making predictions on test set? And Confusion Matrix (CM).
3. Based on this I calculate the Recall and Precision metrics
4. As performance measure I chose the Area under the Precision - Recall Curve.
Further Questions:
- Can I and if yes how can I apply threshold tuning in case A and B? Does it make sense in a balanced dataset in case B? Do I generate the best threshold value by applying the PR curve or the ROC?
-Do I calculate the Precision and Recall metrics after thershold tuning?
- Are Pseudo R2 necessary to be checked for the coefficients?
Thank you very much!!!
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When dealing with an imbalanced dataset in the context of applying a logistic regression (Logit) model on heart disease data, there are several steps you can take to address the imbalance and evaluate the performance of your model. Let's go through your approach and address your questions:
Approach A: Logistic regression with the original imbalanced dataset
1. Splitting data: Splitting the data into training and test sets is a good practice to evaluate your model's performance.
2. Fitting the model and making predictions: Fit a logistic regression classifier on the training data and use the trained model to make predictions on the test set.
3. Confusion matrix and metrics: Calculate the confusion matrix (CM) using the predicted values from step 2 and the actual values in the test set. From the confusion matrix, you can compute metrics such as recall and precision.
4. Performance measure: You mentioned choosing the Area Under the Precision-Recall Curve (AUC-PR) as your performance measure. It captures the trade-off between precision and recall, which is relevant for imbalanced datasets.
Approach B: Applying SMOTE or random oversampling to address imbalance
1. Splitting data: Similar to approach A, split the data into training and test sets.
2. Oversampling: Apply either SMOTE or random oversampling techniques to balance the dataset. These techniques generate synthetic or random samples to increase the representation of the minority class.
3. Fitting the model and making predictions: Fit a logistic regression classifier on the balanced training data and make predictions on the test set.
4. Confusion matrix and metrics: Calculate the confusion matrix and evaluate metrics such as recall and precision using the predicted values and the true values in the test set.
5. Performance measure: Continue using the AUC-PR as your performance measure to assess the model's performance.
Now let's address your additional questions:
- Threshold tuning: Threshold tuning is applicable in both cases A and B. You can optimize the threshold value to balance precision and recall based on your specific requirements. You can use metrics like the precision-recall curve or the receiver operating characteristic (ROC) curve to determine the best threshold value.
- Precision and recall metrics: Yes, you can calculate precision and recall metrics after threshold tuning to assess the performance of your model at the chosen threshold value.
- Pseudo R2: Pseudo R2 measures, such as McFadden's R2 or Nagelkerke's R2, are often used to assess the goodness-of-fit of logistic regression models. They provide information about how well the model explains the variation in the data. Checking these coefficients can be helpful in understanding the overall fit of the model.
Remember that addressing class imbalance is crucial, and oversampling techniques like SMOTE or random oversampling can help improve the performance of your model on the minority class. Additionally, evaluating multiple metrics and considering the specific requirements of your problem is important for a comprehensive assessment of your model's performance.
If you have further questions or need more specific guidance, please don't hesitate to ask.
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I am working on multi species occupancy modelling and I stumbled upon creating residual covariance matrix which has a range of -1 to +1. I need to get a very basic understanding of what a residual covariance matrix is showing me? Is it as simple as showing relation between each species? So, if the value comes to be negative between two species, does it mean they have a negative relation? I am confused because of the term "residual covariance". I would appreciate guidance on this.
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The residual covariance matrix is a concept from statistics and regression analysis that relates to the residuals or errors of a linear regression model. In general, a residual is the difference between the actual value of a response variable and the predicted value of that variable based on a regression model.
The residual covariance matrix is a matrix that summarizes the variance and covariance of the residuals in a regression model. Specifically, it is calculated as the variance-covariance matrix of the residuals, where the diagonal elements represent the variances of the residuals and the off-diagonal elements represent their covariances.
In practical terms, the residual covariance matrix can tell us several things about the quality of a regression model:
  1. Goodness of fit: One important use of the residual covariance matrix is to assess the overall goodness of fit of the regression model. If the residual covariance matrix shows that the residuals are small and uncorrelated, this indicates that the model is a good fit for the data. However, if the residual covariance matrix shows that the residuals are large and/or exhibit significant correlations, this suggests that the model may not be capturing all the relevant information in the data.
  2. Heteroscedasticity: Another important feature that can be revealed by the residual covariance matrix is heteroscedasticity, which occurs when the variance of the residuals varies across different levels of the predictor variables. A non-constant residual variance can be problematic since it violates the assumption of homoscedasticity, which is often required for valid statistical inference.
  3. Multicollinearity: The residual covariance matrix can also reveal the presence of multicollinearity, which occurs when two or more predictor variables are highly correlated with each other. This can make it difficult to interpret the effects of individual predictors on the response variable.
In summary, the residual covariance matrix is an important tool for assessing the quality of a linear regression model. By examining its values, we can gain insights into the overall goodness of fit, the presence of heteroscedasticity and multicollinearity, and other aspects of the model's performance.
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Hello! I need to extract the mass and stiffness matrices for a model with the following problem size:
P R O B L E M S I Z E
NUMBER OF ELEMENTS IS 249191
153326 linear line elements of type T3D2
84141 linear hexahedral elements of type C3D8R
102 linear line elements of type B31
11613 linear quadrilateral elements of type S4R
NUMBER OF NODES IS 267444
NUMBER OF NODES DEFINED BY THE USER 267240
NUMBER OF INTERNAL NODES GENERATED BY THE PROGRAM 204
TOTAL NUMBER OF VARIABLES IN THE MODEL 837207 (DEGREES OF FREEDOM PLUS MAX NO. OF ANY LAGRANGE MULTIPLIER VARIABLES. INCLUDE *PRINT,SOLVE=YES TO GET THE ACTUAL NUMBER.)
The properties are input as mass density, and I believe they will be used to generate a consistent mass matrix.
Here's the input file code I used: ** Global Mass and Stiffness matrix *Step, name=Export matrix *MATRIX GENERATE, STIFFNESS, MASS, VISCOUS DAMPING, STRUCTURAL DAMPING *MATRIX OUTPUT, STIFFNESS, MASS, VISCOUS DAMPING, STRUCTURAL DAMPING, FORMAT=coordinate
I have the following questions regarding my problem:
  1. Dimensions of M and K matrices As indicated above, the number of degrees of freedom is 837,207, but the matrix dimensions are reduced to 354,231*354,231. Shouldn't the number of degrees of freedom match the matrix dimensions?
  2. Node numbering The model consists of 8 parts, and the nodes start from 1 for each part. However, when I extract the matrices using the FORMAT=matrix input option, a different node numbering system (1 to 241,751) is applied, making it difficult to match the entries to the actual model locations. How can I find the correspondence between the entries in the M and K matrices and the nodes in the model?
  3. In the coordinate format, I get 5,620,189 rows of data, while in the matrix input format, I get 2,987,210 rows of data. Shouldn't the number of data entries be the same in both cases?
  4. When using the matrix input format, the entries are extracted in the following format: 241751,3, 241751,3, 9.038200770026704e+00 Can I interpret the corresponding data as follows? 1: X (translational) 2: Y (translational) 3: Z (translational) 4: RX (rotational) 5: RY (rotational) 6: RZ (rotational)
  5. The modes obtained from modal analysis in ABAQUS CAE GUI and the eigenanalysis results obtained from extracting the M and K matrices and performing the Lanczos method in MATLAB do not match. Is there any way to reconcile them?
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Chanwoo Lee Can you share your Abaqus model (.inp)?
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Do i have to revalidate the method using some blank matrix or this matrix effect is acceptable?
I performed matrix base calibration(linearity) for validation.
All the parameters are well within acceptable limits.
I am just not so sure about matrix effect
Please guide.
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Hello,
To validate a method, you have to demonstrate that your blank is really blank (no compound detected).
You have to find a real blank matrix that is not contaminated or in case this is not possible use other methods of quantification as standard addition.
Regards,
Andreu
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Hello to everyone,
I would like some clarifications regarding the PRM technique. I have always used this technique for the Orbirtrap Q Exactive Focus for quantification analyzes on food matrices. By doing some tests on a matrix, I realize that the full scan spectrum for a given molecule has a decidedly better quality, as well as being more intense (but I think this is normal), for quantification compared to the PRM spectrum.
What I can't quite understand is why in PRM, a more specific and selective method, the peak is of low quality. I used a method already tested for other analyses:
Resolution 35,000 ; N(CE) 20.40, 70 eV; Insulation width: 1.5m/z; Target AGC 1e5.
What could it be related to?
Thank you,
Francersco
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This is about to duty cycle/dwell time frequency of the mass analyzer...You should optimize the three parameters experimentally to get similar peak results. In your method builder carefully adjust first the expected LC peak width to get the ideal number of points for ideal peak shape. Thıs directly links to the AGC target which operates the C-trap to collect ions and to gain maximum gains. Secondly, the Microscan option is crucial. You may decrease and observe the change because this controls the number of scans in a particular spectrum...
PRM and full scan creates different modes of ion collection in C-trap and subsequently, injection to orbitrap analyzer, resulting reasonably different number of points for a certain peak...The lower number of precursor ions in PRM mode due to the following fragmentation decreases the sensitivity this also affects the accumulated number in a certain time in the C trap. Thus lower signal and bad peak shape occur in the experiment.
I hope this clarifying enough for a complex issue...
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I want to find eigen frequencies of a cantilever beam. The beam has random elastic modulus. The stiffness matrix is obtained using kosambi karhunen loeve method as A_0+A_i. where A_o is mean stifness matrix and A_i is fuction of normal random variable. The egien values are expanded in terms of polynomial chaos expansion. The final equation is obtained after galerkin projection. The equation is attached in the files. I want a matlab code to obtain the the eigen frequencies,
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I think it will be this code:
% Define mean stiffness matrix A0 A0 = [15 -6 -6; -6 10 -6; -6 -6 5]; % Define random stiffness matrix Ai Ai = [1 2 3; 2 4 5; 3 5 7];
% Set up multiple stiffness matrix cases
A1 = [10 -11 -12 ; 10 11 -20 ; 1 10 -11];
A2= [10 -11 -10; 9 -9 0; 9 10 -10]; % Define normal random variable theta with mean 0 and std dev 1 theta = normrnd(0,1,1000,1); % Calculate stiffness matrix A = A0 + Ai*theta + A1*theta + A2*theta
% Solve for eigenfrequencies using eig() V = eig(A);
D = eig(A);
% Extract the square roots of the eigenvalues omega = sqrt(diag(D)); % Plot the histogram of eigenfrequencies figure histogram(omega) xlabel('Eigenfrequency') ylabel('Count') title('Histogram of Eigenfrequencies') % Calculate mean and std dev of eigenfrequencies omega_mean = mean(omega) omega_std = std(omega) % Display the results fprintf('The mean eigenfrequency is %f rad/s \n', omega_mean) fprintf('The standard deviation is %f rad/s \n', omega_std)
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Dear amazing researchers,
I am working on a nonlinear FEM problem and using Python for coding.
To get the nodal values of the field variable, I have to solve a system of linear equation. In matrix notation, [A]{x}={b}, where [A] is a sparse-matrix (a lot of zeros away from main diagonal), {b} is the right hand side vector.
One trivial solution is {x}={b}/[A], but it is computationally heavy when needs to be done many times and [A] is large.
Lets take a simple example:
A = [[5, 2, -1, 0, 0],
[1, 4, 2, -1, 0],
[0, 1, 3, 2, -1],
[0, 0, 1, 2, 2],
[0, 0, 0, 1, 1]]
and b = [ [0],
[1],
[2],
[2],
[3]]
To store the complete sparse-matrix is waste of memory when a large number of element values are zero, so I wrote a code to store the matrix in a compact form, which stores the non-zero diagonals in every row.
[Ac]= [[ 0, 0, -1, -1, -1], [ 0, 2, 2, 2, 2], [ 5, 4, 3, 2, 1], [ 1, 1, 1, 1, 0]]
There is a function in "scipy" library. It is scipy.solve_banded(), which takes the "Ac", and "b" as arguments and return the solution {x}.
Could anyone help me to find out the algorithm behind scipy.solve_banded() function?
I will be very thankful for your help.
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Assuming Ac is banded matrix structure, a possible algorithm to perform LU Decomposition on Ac could look like this:
  1. Initialize two compact matrices Lc and Uc to store the lower and upper triangular parts of the decomposition. These matrices have the same structure as Ac.
  2. For each column j:a. For each row i from j to N (N being the size of the matrix): Compute the sum of products of corresponding elements of the i-th row of Lc and the j-th column of Uc. This corresponds to the dot product of the i-th row and j-th column of the full matrices L and U. Subtract this sum from the i,j-th entry of A (which is represented in Ac) to get the i,j-th entry of U (to be stored in Uc).b. For each row i from j+1 to N: Compute the sum of products of corresponding elements of the i-th row of Lc and the j-th column of Uc. This again corresponds to the dot product of the i-th row and j-th column of the full matrices L and U. Subtract this sum from the i,j-th entry of A (which is represented in Ac) to get the j,i-th entry of L (to be stored in Lc).
  3. Return Lc and Uc as the compact representations of the lower and upper triangular parts of the decomposition.
*** Assuming that no pivoting is required. If pivoting is required, the situation gets significantly more complicated for a banded matrix.
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Reservoir Compressibility: Useful only in land subsidence?
Feasible to deduce the compressibility of a petroleum reservoir (sandstone) as a function of fluid-pressure drop in a reservoir?
How difficult would it remain to deduce the ‘relative changes in reservoir thickness’ in order to estimate the above sandstone’s rock-matrix compressibility? Feasible to deduce the role of individual contributions: (a) deformation of the solid-grain matrix of the reservoir; (b) expansion of brine, oil and gas – upon hydrocarbon production from a confined reservoir?
How useful would it remain, if we deduce the value of ‘Storativity’ (S: a dimensionless property) of a petroleum reservoir as a function of (a) drop in piezometric-head; (b) surface area of the reservoir being produced from; and (c) volume of fluids withdrawn from stored reservoir (S = ab/c)?
Could the estimation of ‘specific storage (SS)’ of a reservoir also remain useful in reservoir engineering, (estimated as a function of Storativity over reservoir thickness’ (SS = S/thickness)?
OR
Whether the correlation between ‘specific-storage’ as a function of rock-compressibility (RC), fluid compressibility (FC), reservoir porosity (P) and specific-weight of the fluid (SWF) has any vital information associated with the draining principle of reservoir engineering {SS = (SWF*RC)+(P*FC)}?
OR
The concept of ‘Storativity’ would remain useful - only in the estimation of ‘reservoir compaction’ and its associated ‘land subsidence’?
How do we ensure whether a reservoir undergoes a ‘normal compaction’ upon hydrocarbon production? How do we know that the deformation of the solid-grains of a sandstone reservoir remains concurrent with the fluid expulsion?
Or
How do we know that the ‘rate of loading’ remains larger than the ‘rate of fluid expulsion’ so that we could conclude that there is a ‘disequilibrium compaction’ of the concerned reservoir? And, in such cases, how do we estimate the ‘enhanced fluid-pressure’ resulting from the fact that ‘the fluid temporarily carries part of the load, which remains ultimately transferred to the solid-grain matrix of the reservoir’?
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A well known example of an offshore field in which compaction was significant is the Ekofisk field in the Norwegian sector of the North Sea. Sea floor subsidence on the order of 10 metres necessitated raising the plarforms at a yotal cost on the order of $ 1 billio
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Dear all,
I am evaluating vegetation recovery 1 year after wildfires in Mediterranean forest ecosystems. I have selected two factors: 1) previous (or not) silviculture treatment to wildfire and 2) exposition (south and north-facing slopes). I consider both factors as fixed factors, right?
Secondly, I have measured vegetation cover at different plots by combining two factors (treatment x facing slope). In the end, I have a matrix containing vegetation cover (in cm) for each plant species measured in the combination of factors (treatment (yesxno); facing slope (NxS)). Shall a first transform the matrix using square root and then build the resemblance matrix? What is best for my analyses ANOSIM or PERMANOVA?
Thirdly, Shall I make any previous analyses like checking the variability of variance or homogeneity of my data?
I am using Primer software.
Thanks in advance
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Thanks a lot. I highly appreciate your help
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Size of polymer matrix is near about 500 nm and size of filler used is 1000 nm. Can it be called as nanocomposites? Please discuss.
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One of the materials composing the composite (organic or inorganic) should be less than 100 nm in size
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Are there conditions (constraints) that the elements of the correlation matrix must meet? (For example, the linear correlation coefficient of X1 and X2 is 0.99, and it is the same between X2 and X3. Then between X1 and X3, it can be any low, or must it be greater than a given value?) If there are such constraints, what are they?
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d1, d2,... dn be a set of vectors in R^n which are linearly independent, hence, the Matrix D=[ d1 d2... dn] is full rank (invertible), hence the associated covariance matrix H= D'*D is symmetric, positive definite.
But linear independence can be associated with poor mutual orthogonality as well , in the best case these vectors are mutually orthogonal and H is diagonal.
In a general case, these vectors would continue to span and form basis for R^n but their relative orientations may be such that it is far from the case of mutual orthogonality: as an example of this think to two linearly independent vectors and a third one marginally lying outside of the plane containing the other two: this situation and the more generalized cases of this, is quantified by estimate of " multicollinearity".
If the vectors d1, d2,...., dn are such that they form a strongly multicollinear set, the correlation between a pair of vectors of this set can be very high, and positive or negative, that is close to magnitude 1.
Correlation matrix is a measure of this orientational structure associated with these set of vectors d1,.... dn, if the vectors are mutually orthogonal, all the off diagonal terms in the correlation matrix would be zero.... in case of strong multicollinearity, the correlation matrix would be still full rank, but close to singularity.
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I want to check the effect of DDSDDE in UMAT on the element stiffness matrix. So, is it possible to output the element stiffness matrix in each iteration in Abaqus/Standard?
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Vigneshwaran Radhakrishnan Thank you for your answer. But using ''*Element Matrix Output, Elset=Set-1, File Name=myMatrix, Frequency=n, Output File=User Defined, Stiffness=Yes" can only output element stiffness matrix at the beginning of each increment, in which there may be several iterations to obtain convergent solution. So, how can we output element stiffness matrix at every iteration?
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Dear: Jean Dezert , Albena Tchamovag, Deqiang Han, Jean-Marc Tacne
Reference is made to your paper :
The SPOTIS Rank Reversal Free Method for Multi-Criteria Decision-Making Support
My comments as follows:
It is a very good news to have a method without Rank Reversal (RR)
1- In my opinion you use the phrased ‘score matrix’ to indicate what in reality is the initial matrix, composed by performance values. This induces to confusion to readers for who score matrix is a matrix with different scores or results derived from applying a MCDM method.
2- You say in page 3 “The score matrix S = [Sij ] is sometimes also called benefit or payoff matrix in the literature.”
What happens if the matrix, as is most usual, also calls for minimization, using ‘cost’ values?
3- I don’t think that an initial decision matrix (IDM) can be considered incomplete because it does not have bounds for criteria. A matrix is incomplete when there is no indications of the quantity of resources for each criterion, procedure unfortunately followed by most MCDM methods, except PROMETHEE and those working with Linear Programming.
4- I agree with what you say about validations.
5 – You say “Classical MCDM problem becomes a well-defined MCDM one, where all scores values for each criterion are between its bounds”
6- “SPOTIS method will provide the best multi-criteria decision-making solution with preference ordering of all alternatives.”
Are you sure it is the best? On what grounds do you assert that?
7- In page 3: You consider criteria independent from each other. This s is a serious drawback, since in most projects criteria are interrelated. According to this, if you have two criteria like ‘Sped’ and ‘Fuel consumption’, that are interrelated, you can’ use SPOTIS? Why not?
8- How do you determine an ideal solution a priori? Based on what? Of course, if this solution is say very high, is does not matter what alternative you add, because it will be always above the maximum.
I grant you that it is a very elegant procedure.
9- I don’t think is correct to work with difference types of distances in the same problem?
10 - Where does weights come from? Are they subjective or objective?
11 – In page 5 “Once the MCDM is well-defined thanks to the specification of the bounds values of each criteria, the SPOTIS method does not suffer from rank reversal because the evaluation of each alternative is done independently of the others
I agree 100% with this statement, because I also believe that the only way to avoid RR is evaluate each alternative independently. There is another method that applies this same principle and does not produce RR, but is not based on distances to a fixed point.
12- In page 7 “It could be argued that the SPOTIS method is more difficult (or risky) to use because of the freedom left in the choice of min and max bounds of the criteria”:
More difficult, risky? I don’t think so. It looks as a transparent method and very easy to understand. In my opinion its only drawback is using subjective weights.
Do you have a software for SPOTIS?
I hope my comments may be useful to your paper.
Nolberto Munier
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I sign my name under each of your evaluations