Science topic

# Engineering, Applied and Computational Mathematics - Science topic

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Questions related to Engineering, Applied and Computational Mathematics

Here I would like to sort of gauge how much extrapolation techniques are still being studied/ used to estimate or predict the remaining life of components that are subjected to creep.

I have come across what is called the Theta projection technique. I have found literature that supports the method impressively well. I was wondering if anybody here used the method or worked with the method closely, so I can ask a couple of questions that I have in my mind when I am applying the method.

I want to learn the basics of B-spline curve in order to better understand the NURBS.

Hello,

Suppose we know the quaternions describing orientation of PIP,DIP and MCP respectively at every instant of time, how can we use the same to estimate the joint angle ie, how much flexion/extension, abduction/adduction ?

I know relative orientation can be found and Euler angles can be decomposed if we know the euler angle sequence or finding the rotation matrices for respective segement and using the dot product of the aligned axes (not sure this part).

Can anyone suggest a method of finding the joint angle or reading material to find the same.

Thanks and Regards,

Akhil

I Have Digital maps in PDF files and I would like to convert them into either Vector formats or Raster Formats. Any idea or any software that can help me?

Hi all,

I have a basic doubt in linear algebra. The determinant of a 2x2 matrix can be considered as the area of a parallelogram. Similarly what could be the physical interpretation of a characteristic equation and roots of the characteristic Equation (Eigen Value)?

This question is bugging my mind for a long time now. Can any one here enlighten me?

Regards,

Balaji

Hi

in ansys fluent's dacuments it has been said that : (( ANSYS Fluent has taken steps to offer more advanced wall formulations, which

allow a consistent mesh refinement without a deterioration of the results. Such -independent formulations are the default for

all omega-equation-based turbulence models. For the epsilon-equation-based models, the Menter-Lechner and Enhanced Wall Treatment (EWT)

serve the same purpose. A -insensitive wall treatment is also the default for the Spalart-Allmaras model and allows you to run this model

independent of the near-wall resolution. ))

so, is it true that for models mentioned above like k-omega or k-epsilon(EWT,Menter-lechner)there is no need to check y+ value to be in a certain range ?

for example can i use k-epsilon model with enhanced wall treatment and y+ value changes between 0.5 to 600 ?

if my assumption is'nt true , what is the certain range of y+ value for all turbulence models like k-epsilon with wall functions or k-omega

without wall functions ? please give me a reliable source ...

thanks...

Many times after the paper is published, the authors note that a major flaw has taken place in published work. . The flaw can either be in formulating the problem or in the methodology or assumptions or errors in measurement. The published results are totally wrong. In such cases, do authors on their own accept the mistake and withdraw the published paper?

Dear All,

I modeled a rotating blade in the Abaqus/CAE 6.14-2 x64. The blade is generated using the properties of different sections of the airfoils along the span. The generalized beam section is used for different sections of the blade. The mass of the blade is given as a longitudinal mass in line with its length. The material used for blade has an elastic modulus of 13.1 GPa, and a shear modulus of 8 GPa. The properties of this generalized section consisted of the area (A), the moment of inertia along two axes (I11, I22), and polar moment of inertia (J). Element type B31 was used to meshing the blade.

The blade was then spun by the Displacement/Rotation boundary condition of Abaqus around an axis through one end perpendicular to its length. The rotation was modeled in both Static-General and Dynamic-Explicit methods. In both cases, there was a significant increase in the length of the blade.

How to prevent the elongation of the generalized beam section in the Abaqus? It is noted that the natural frequencies of the blade should not change. For example, the amount of elastic modulus should not be increased.

Sincerely,

If X is a quasi-Banach space without a separating dual that is no p-normable for some 0<p<1. Is it possible for there to exist a p-norm making X into a p-Banach space such that this new space is not isomorphic to X. In other words, are there non-trivial examples quasi-Banach envelopes.

If 0<p<1 then p-normability is equivalent to having Rademacher type p. So, if the ability to equip X with an p-norm implies X has type p in with its original quasi-norm then X is its own p-Banach envelope.

This question is uninteresting in the case X has a separating dual as such spaces may be equipped with r-norms for all 0<r<=1. And, it may be that many of these are not equivalent to X's given quasi-norm.

I'm working on some dynamic problems, and often we need to determine the inverse of a matrix of order 50x50 and larger. I need to speed up the process.

Hi everyone,

As we know, the formulas of the natural frequencies and their corresponding mode shapes for the uniform linear elastic soil (without damping) on the rigid bed are as follows [1]:

f_n = (2n - 1)vs / (4H)

vs = sqrt(G/ρ)

φ_n = sin((2n - 1)πz / (2H))

where f_n is the natural frequency of the corresponding mode in Hertz, φ_n is the mode shape of the corresponding mode, n is the mode number, H is the depth of the soil column, vs is shear wave speed, and z is the height from the rigid bed.

I create the finite element model (FEM) of soil using the commercial finite element (FE) program Abaqus/CAE 6.14-2 x64. The soil was modeled according to the geometric properties using the C3D8. It has a depth of over 50 meters and a horizontal distance of over 100 meters. The soil element size is 2 meters. The total model consisted of 62500 soil elements. Fig. 1 shows the 3D of the soil model. The unit weight of soil is taken 15 kN/m^3, Young’s modulus is 1000 kN/m^2, Poisson’s ratio is 0.35, Cohesion is 5 kN/m^2.

In order to closely match the theoretical solution, some assumptions have been made for the modeled soil. The soil rests on the rigid bed, modeled as boundary conditions restraining the bottom against translations and rotations at all directions. Further, the outer nodes of the model at the same level (Y equal) are tied using the MPC-Tie constraint to move together.

According to the theoretical formulas mentioned above, the first and second natural frequencies of soil column are obtained 0.0786 Hz and 0.2357 Hz, respectively. Nevertheless, the FE results do not conform to this order as the mode number. The first twenty-two natural frequencies of the soil FEM are shown in Fig. 2. The selected 3D mode shapes of the soil FEM are illustrated in Fig. 3. As can be seen in Fig. 1 and Fig. 2, the 1st frequency of the model occurs at mode numbers 1 and 2 and in two horizontal directions perpendicular to each other. This result is consistent with the theoretical results. However, the 2nd mode shape as the model occurs in modes 11 and 12, which is contrary to the theoretical results. Interestingly, the behavior of other mode shapes of the soil model is also strange.

Why do the order of the fundamental mode shapes and their frequencies of the soil FEM differ with theoretical values? Should further assumptions be made to fully simulate the FEM with the theoretical soil model?

The figures and the Abaqus/CAE FEM file are attached.

Thanks a lot in advance.

References

[1] Steven L. Kramer. Geotechnical Earthquake Engineering. Pearson Prentice Hall, 1 edition, 1996.

I get two quaternions streamed from IMU-sensors. How do I calculate the (smallest) angle between them?

I wish to learn meshfree methods. Please recommend some good tutorials and example codes.

While optimizing machining parameters through GRA, in the final step GRG of initial, predicted and experimental parameters were compared to find the effect of GRA. In this regard on what basis the initial parameter combination selection has been made. In articles there is no explanation about this.

Is Entropy Shanon a good technique for weighting in Multi-Criteria Decision-Making?

As you know we use Entropy Shanon for weighting criteria in multi-criteria decision-making.

I think it is not a good technique for weighting in real world because:

It just uses decision matrix data.

If we add some new alternatives, weights change.

If we change period of time weights change.

For example we have 3 criteria: price, speed, safety

In several period of time weights of criteria vary

For example if our period of time is one month"

This month may price get 0.7 (speed=0.2, safety=0.1)

Next month may price get 0.1 (speed=0.6, safety=0.3)

It is against reality! What is your opinion?

for linear control systems x_dot=Ax+Bu the reachability set can be calculated using the Image of the controllability matrix, i.e

R=([B AB A^2B,....,]) and reachability set=Im(R)

when rank(R)=n, and we do not have any control constraint the reachibilaty set of linear system is R^n (n is the dimension of states)

if we have a non-linear affine-control system

x_dot=f(x)+g(x)*u

R can be calculated using Lie algebra

R=[g1,g2,[f,g1],[f,g2],...]

my question is, in this case reachability set is again Im(R)?

and if reachability set=Im(R), how can we compute the rachability set, because here R will be a matrix with function arrays (function of states)

I am simulating (CFX) a pipe with a turbulence promoter in it. I am using RNG k-e turbulence model yplus is lower than 1. For mesh independency analysis I am using turbulence kinetic energy as a output. The problem is, as I increase the mesh size, relative difference is getting higher up to certain mesh size (solution is getting mesh dependent). After that mesh size the relative difference is decreasing. For example from 4 to 12 million, relative change increases and from 12 to 25 million, it decreases. This values are coming because of the region where is just after the turbulence promoters (dominant anisotropic flow).

What could be the reason?

One of the main stability theories for stochastic systems is stochastic Lyapanuv stability theory, it is the same as Lyapanuv theory for deterministic systems.

the main idea is that for the stochastic system:

dx=f(x)dt+g(x)dwt

the differential operator LV(infinitesimal generator- the derivative of the Lyapanuv function) be negative definite.

there is another assumption for this theory:

f(0)=g(0)=0

and this implies that at equilibrium point (here x_e=0) the disturbance vanishes automatically.

what I want to know is that is it a reasonable assumption?

i.e in engineering context, is it reasonable to assumed that the disturbance will vanish at the equilibrium point?

Imagine we have an ODE system

x_dot=[f1(x,u), f2(x,u), f3(x,u),....fn(x,u)]

where f1,..,fn are nonlinear functions of control input u and states x,

x is member of R^n and u is member of R^m

under which conditions we can change the dynamic of the system to arbitrary dynamic x_dot=[f1_des(x) f2_des(x),...,fn_des(x)]

where f1_des(x) f2_des(x),...,fn_des(x) are arbitrary pre-defined nonlinear functions.

is input to state controllability enough to do that?

*Example*

*consider the 2-D system:*

*x1_dot=f1(x1,x2)+g1(x1,x2)*u1*

*x2_dot=f2(x1,x2)+g2(x1,x2)*u2*

*by choosing*

*u1=(f1_des(x1,x2)-f1(x1,x2))/g1(x1,x2)*

*u2=(f2_des(x1,x2)-f2(x1,x2))/g2(x1,x2)*

*we can change the dynamic of the system to*

*x1_dot=f1_des(x1,x2)*

*x2_dot=f2_des(x1,x2)*I'm studying the tensile behavior of a composite cylinder made of two different materials. The cylinders are concentric and placed one over the other. I want to assign an absolute stiffness to the contact elements between the outer surface of inner cylinder and inner surface of outer cylinder in Ansys. But as far I know one can only assign the normal stiffness factor in Ansys workbench.

I'm teacher and suffering a lot to complete my MS. I need to write an MS level research thesis. I can work in Decision Making (Preference relations related research work), Artificial Intelligence, Semigroups or Γ-semigroups, Computing, Soft Computing, Soft Sets, MATLAB related project etc. Kindly help me. I would be much grateful to you for this. Thanks.

in most cases for continuous time stochastic systems which are modeled by SDE, the Lyapunov stability conditions can guarantee the stochastic stability of the system,

another definition In stochastic literature is detailed balance which guarantee the convergence of the probability of the states of SDE to a stationary probability density.

I want to know which one is more strong stability condition?

First a large size matrix requires sufficient memory to inverse the matrix. Secondly, there are several mathematical techniques are available to solve the inverse of a matrix. But in handling a large matrix, still I couldn't find any faster and accurate method which can solve this problem with less memory consumption as well.

In optimization problem often we use local optimum but is it global? Or are there any meta-heuristics algorithm to obtain global solution? If there any then what is the name of that algorithm and if possible how we can get that solution?

There are lots of Optimization method /Evolutionary algorithms (EAs) in literature. Some of them is more effective (for solving linear/nonlinear problem) compared to other. But we don’t know which will fit our model. As a result we checked for everything as we can do. But cant get the desire result. Some of those methods are 1. Genetic algorithms (GA) ; Haupt and Haupt (2004) 2. Pattern search (Mathlab) 3. Particle swarm optimization (PSO), Binary Particle Swarm Optimization (BPSO); Eberhart and Kennedy (1995) 4. Bee optimization; Karaboga and Bosturk (2007) Pham et al (2006) 5. Cuckoo algorithm; Yang and Deb (2009, 2010) 6. Differential evolution (DE) ; Storn and Price (1995, 1997) 7. Firefly optimization; Yang (2010) 8. Bacterial foraging optimization; Kim, Abraham and Cho (2007) 9. Ant colony optimization (ACO) ; I Dorigo and Stutzle (2004) 10. Fish optimization; Huang and Zhou (2008) 11.Raindrop optimization ; Shah-Hosseini (2009) 12.Simulated annealing ; Kirkpatrick, Gelatt and Vecchi (1983) 13.Biogeography-based optimization (BBO), 14. Chemical reaction optimization (CRO) 15. A group search optimizer (GSO), 16. Imperialist algorithm 17. Swine flow Optimization Algorithm. 18. Teaching Learning Based Optimization (TLBO) 19. Bayesian Optimization Algorithms (BOA) 20. Population-based incremental learning (PBIL) 21. Evolution strategy with covariance matrix adaptation (CMA-ES) 22. Charged system search Optimization Algorithm 23. Continuous scatter search (CSS) Optimization Algorithm 24. Tabu search Continuous Optimization 25. Evolutionary programming 26. League championship algorithm 27. Harmony search Optimization algorithm 28. Gravitational search algorithm Optimization 29. Evolution strategies Optimization 30. Firework algorithm, Ying Tan, 2010 31. Big-bang big-crunch Optimization algorithm, OK Erol, 2006 32. Artificial bee colony optimization (ABC), Karaboga,2005 33. Backtracking Search Optimization algorithm (BSA) 34. Differential Search Algorithm (DSA) (A modernized particle swarm optimization algorithm) 35. Hybrid Particle Swarm Optimization and Gravitational Search Algorithm (PSOGSA) 36. Multi-objective bat algorithm(MOBA)
Binary Bat Algorithm (BBA) 37. Flower Pollination Algorithm 38. The Wind Driven Optimization (WDO) algorithm 39. Grey Wolf Optimizer (GWO) 40. Generative Algorithms 41. Hybrid Differential Evolution Algorithm With Adaptive Crossover Mechanism 42.Lloyd's Algorithm 43.One Rank Cuckoo Search (ORCS) algorithm: An improved cuckoo search optimization algorithm 44. Huffman Algorithm 45. Active-Set Algorithm (ASA) 46. Random Search Algorithm 47. Alternating Conditional Expectation algorithm (ACE) 48. Normalized Normal Constraint (NNC) algorithm 49. Artificial immune system optimization; Cutello and Nicosia (2002) 50. fmincon .

Besides this there are many other optimization algorithm recently invented which are generally called Hybrid optimization Technique because it’s a combination of two method. If we share our experiences then it will be helpful for all of us who are in the field of optimization. I may be missing some methods, researcher are requested to add those algorithms and the way of use like many model needs initial value, weight, velocity, different type of writing objective function etc. I am facing some problems that’s why I make this format which will definitely help me as well as all other researchers in this field. Expecting resourceful and cordial cooperation.

Is it possible to manage with supply chain in a more effective way?

Like wave propagation in magneto-thermoelastic media. In Finite element formulation I found the second derivative. I am little bit confuse about continuity of the second derivative for linear element.

I have two stationery time series that I want to see are they correlated or not. I decided to work with cross correlation, there is a good answer in Correlation between two time series but I dont know how to calculate p-value(as http://stats.stackexchange.com/users/11032/michael-chernick said) and decide that its a good answer, if there are correlated do something. I dont know how to do this. I want to code it with C++ and use it for simulation in Omnet++ . Could someone help me to find a way or introduce a document to me to understand the mathematical way to calculate it and program it in C++? P.s : My data are the number of packets which send from two nodes to an OLT in a network continuously. something like this:

from time 0 to 10:

series 1 : 2 5 3 7 9 2 0 1 8 4

series 2: 3 4 6 0 5 9 2 5 3 7 . series 2 has 6 min delay. or maybe there is no delay in other case, I must calculate the delay also (I can calculate delay with omnet++ but I dont know are they correlated at the end or not)

I have an image with a bigger scale in Y than in X. In this image I want to measure several areas. Now I need to know, if the true area is dependent of the orientation of the object / area I want to measure.

Look at my example:

A is the original picture. All bars are of the same size and area.

B is picture A with a bigger height (Y) scaling

Do all three bars (horizontally vs. vertically vs. diagonally) in B have the same area?

So to summarize my question again: A picture with objects of the same size gets changed in Y-scale. In this changed picture, do all objects still have the exact same size?

Thank you very much!

What are the applications of Diagonalization of a matrix?

Model Predictive Control is a receding control approach, that basically does online dynamic optmisation on a finite horizon while implementing online, the first control optimal action of the control sequence. The online dynamic optimisation is repeated based on the measure system states with a sliding finite-horizon window.

However, can't we say that

**in principle due to the finite-horizon nature of MPC**, the solution result obtains d**oes not guarantee global optimality**in the infinite horizon time scale as the control sequence found between A-B will not be necessarily optimal if the horizon A to C (A-B-C) was considered ? It seems to be some kind of**corrective greedy search**where the best control sequence at any branch is selected and because the control sequence is not fully implemented at the finite horizon, there is a possibility for escaping a bit the danger of the greedy search at the next iteration?Given an undirected(weighted) graph depicted in the attached diagram which is a representation of relationships between different kinds of drink, how best can I assign weight to the edges? Is there a technique that I can use?

I am a researcher of materials science and metallurgical engineering. I am interested to work with atomic level and electronic modeling of the structure and properties of materials,materials informatics and simulation in future. Currently i am learning

**. I have basics of***Python***and***C***. What will be the useful programming languages to learn for me?***MATLAB*What I want

____________

Circulation = path integral of the velocity around the boundary of surface --> (Stoke's Theorem)--> Circulation= surface integral of curl of the velocity field over the surface

What I have

____________

* A number of N points defined by their coordinates (x, y,z). These points are on the surface (not the contour of the surface)

* velocity field components u,v,w for these points

* Form (visually observable) of the surface. Is not rectangular. It is more like a circumference.

(I'm using Matlab)

Thanks in advance.

We can think of the circle center as a "focus" of points of its circumference given by distance to center = constant. In case of an ellipse we have sum of distance from points on boundary to the two foci =constant, Can this be generalized ? In fact the reverse problem is of interest i.e. given an arbitrary closed curve, is it possible to determine such criteria( or numerical algorithm to identify such foci and also conditions when it exists). This is a general exploratory question. and all are welcome to comment.

Often computational time estimation for a numerical operation is based on analytic data. And the sparse matrices are often considered in engineering structural analysis. Thus, the operation counts of matrix analysis (including matrix multiply, matrix decomposition, and solution of linear systems) are often needed to be known in a analytic way. Therefore, anyone who would like to suggest some literatures and opinion are encouraged to discuss them to me.

- Could you please point me out to some successful Medical sciences applications using partial differential equations?

- Preferably, involving heat, reaction-diffusion, Poisson, or Wave equation.

- If possible in fuzzy environment.

Best regards

Sarmad.

What is the fastest way to learn about neural networks? there types? how to use them? full solved examples? real life applications?

Many thanks

Could you please point me out to some successful Signal, image, or video processing real life applications using partial differential equation?

Preferably, involving heat, reaction-diffusion, Poisson, or Wave equation.

If possible in fuzzy environment.

Best regards

Sarmad.

We are trying to simulate mixing of two streams of different chemical concentrations.

Mathematics is fundamental in all sciences and mainly in Physics, which has even had many contributions. It seems that the capacity to be applied would be the motor to be create. But this not what good mathematicians as Henry Poincarè or Hardy has said. What is the beauty in mathematics, in theoretical physics or in others which could be related subjects?

For me there are very beautiful mathematical results which sounds difficut to be applied or even against our reality, which are full of "beauty" or at least "surprise".

1.Sum of natural numbers = a negative number as - 1/12.

2. Polynomials with degree five or higher are without analytical expression of their roots.

3. Banach-Tarsky theorem

4. There cannot exit more than five regular polyhedra in three dimensions.

Which analysis could use for this problem?

currently some colleagues and I have been working on these issues and the curious thing is that we do not find articles or works that are not more than 10 years, it is as if the enthusiasm for this subject would have died.

thanks for any help.

I want to study the flow pass two squirmers, which corresponds to solve the Stokes equations for two spherical bodies (some distance apart) with prescribed tangential velocity on their surfaces, in an otherwise static fluid. (You can find these equations in the attachment)

We can find analytical solution when there is only one squirmer at play, but exact solution become hopeless for two squirmers. Due to the linearity of the equation, I once considered the superposition of two one-squirmer solutions (After some shift of the coordinate), but this would break the boundary condition and make the squirmer unrealistic.

So now I am looking for the solution of aforementioned equations numerically, I also restrict myself to 2-dimension. But it is still hard to express the boundary condition on two circles simultaneously (the polar coordinate won't work). My plan is to find another coordinate system that transforms these two circles into two lines at infinity, then try to solve it with Mathematica or Matlab (not sure whether it will work).

Could you please share your thought on this problem? Is there any other method/software I am unaware of that can crack it easily?

How can I compare the shape of two curves? I was reading about techniques like the Fréchet distance, but I do not think that is useful, because some curves look alike, but are for example positioned more to the left on the X-as. How can I compare only the shape, not the position on the X-as? Thanks in advance.

Dear All,

I have a question regarding the the existence and uniqueness of a system of linear Volterra integral equations.

Does the solution exist? Is it unique?

What are the conditions on the kernels for the existence and uniqueness of this system of equations?

**The equation is written in the attached file.**

I would appreciate your help greatly. Thank you.

Sarah

Dear all,

I have developed a new technique which solves

**linear**integro-differential equations of fractional type. This includes Fredholm and Volterra equations.I am looking for an application which can be modeled into such equation so I can apply my method. It can be any kind of application.

I also solve mixed system of equations e.g.1. A system of multiple Fredholm equations of different order of fractional derivatives (0, 1/2, 1, 3/2, etc..) or e.g. 2. A system of same or different kinds of Volterra equations. So, if there is an application to this kind of equation, it would be great!

I would appreciate your help. Please refer me to an article.

P.S.

**Only linear equations please.**Thank you very much in advance.

Sarah

As stated in the documentation of the "distributed parameter line" block: "This model does not represent accurately the frequency dependence of RLC parameters of real power lines. Indeed, because of the skin effects in the conductors and ground, the R and L matrices exhibit strong frequency dependence, causing an attenuation of the high frequencies."

Is there a third party model of transmission line, compatible with SimPowerSystems, dealing with skin effect and other nonlinear behavior?

I need to model a DC load, that is connected to a 3-terminal DC grid. The other 2 terminals provide the needed power. As far as I know, the load can be modeled as a pure resistance, but I don't know how its value should be determined or if there are better and more accurate ways to model it.

For analysis of engineering structures like geometrically nonlinear beams and plates in statics, I consider two main approaches: finite element method (FEM) and finite difference method (FDM). Since I am just starting, could you please explain me:

1. if I use FEM, is it possible to obtain a discretized system of the form Ax=b, where x is the displacement of the structure? As I understand, FEM reduces the problem to Kx=f, where K is the stiffness matrix and x is the coefficients of the approximation of the displacement with ansatz function. Am I right?

2. What are the advantages of FDM over FEM especially for nonlinear problems?

Currently I am working on Computational Fluid Dynamics and Heat Transfer study of a mixing T junction. I have carried out analysis and have obtained results for the same.

My query is I want to convert the model made into 1 part 1 body instead of 1 part 2 body so that the grid generation becomes feasible and smooth.

Please guide me for the same by describing the steps against how to overcome the problem.

I am conducting a survey of analytical methods, from engineering cycle analysis to 3D full N-S coupling detonation, turbulence, multi-specie fluids, codes having the capability to assess propulsive performance, and to model/simulate computationally any detonation-based propulsion systems such as PDEs and RDEs.

In addition to the capability of the tool, I'd like to know if the code is proprietary, ITAR, commercially available, or if it can be obtained for academic research.

Thank you!

I want to know how to calculate the Gibbs free energy in VASP . I have 1 T phase 2D materials structures and I want to know which kind of parameters I need to fixed in the INCAR file through I can get it. Where I will find these energies in VASP calculations? Please some one guide me about this.

Hi,

In FEM, I imposed the Dirichlet as essential and Neumann as natural boundary conditions for the heat equation with some specific values. My question is : Once the solution is obtained for the temperature distribution, how to know whether the boundary condition is satisfied or not? As far as Dirichlet boundary condition is concerned, it satisfies exactly with respect to the domain since it is explicitly applied and in the solution, the values are same. What about Neumann Boundary condition?

I need to know if there are some emperical equations or any kind of formulations that can be used to model and analyse masonry structure as a nonlinear anisotropic and homogeneous material.

what are the parameters( mechanical properties of the masonry) needed to do so?

hi

How find centroids vertices using LOF function in highlighted section(Definition 3) in attached file ?

If possible, I needed comparison in solver capabilities, material database, accuracy of simulation output, licensing cost etc. What software would be recommended for specific Sheet Metal Forming Simulations?

I have developed a system dynamic model containing approximately 66 parameters. I have a reviewer who thinks the model is too simple as I could have added more inputs. However, my decision to exclude such inputs was based on the fact they do not provide any significant information about the performance of the model.

I want to try out numerical modelling of helical soil nails.

I have applied torque to the beam and want to see the deflection, not deformation. But, I have seen only deformation in the solution list. So, can anyone help me to find the deflection of the beam in ansys?

There is a multitude of well balanced schemes for the shallow water models with source terms.

Which five of them can you recommend? The hydrostatic reconstruction is actually top on my list. So what do you think?

I need to optimize a function of several variables moving in

**, under the costraint that only 2 of these variables can have a contemporary deviation with respect to the nominal value (In other words, N parameter variations must be explored, but only 2 at the same time, while others N-2 keep a known value). Do you have any suggestion about a method, or a paper which faces this problem using GA or PSO. Thanks.***R*Well, it is about underwater vehicles moving on the concentric circles for tracking. Let the vehicles be XA on circle A, and XB on circle B, XC on vehicle C and so on. (There could be more than one vehicle on each concentric circle).

Since the circumference on A is smaller than that of the others, the vehicles will finish the tracking on A faster. After finishing the tracking, they will move to B to assist in finishing the tracking the vehicles on B have not yet finished.

When the vehicles XA and XB now finish the tracking on B, they will also all move to the next circle to assist in the remaining tracking the the vehicles there have not yet finished. This will move on until the last circle is tracked.

I am trying to do some finite element dynamic model of the foot and ankle during running. One of the critical model inputs in my thoughts is the magnitude of foot extrinsic muscle forces during running. I have seen the same data for barefoot walking. However, till now I couldn't find any for running. Is there a data source or reference for the above mentioned data? Thanks in advance.

I have 450000 data from gyroscope and I want to model stochastic noises of it and at bias instability modeling I need time correlation to model bias instability and I don't know who can I compute it?

I am doing a very simple simulation in COMSOL consisting of piezo, matching layer and water. It calculates transmission coefficients for a range of frequencies given a constant matching thickness. The maximum of the curve matches with the analytical result ( Which I am pretty sure is right since it matches with the experiment) but the minimum values differ by 50%. i don't know why it is happening? Can anybody help me with that?

I calculated the band structure of O2 adsorbing in CH3NH3PbI3. I got the result as the following attach. who can tell me why it appear the fat band. anyone has suggestion?

Hi all, I'w working with meshing using VisCART of ESI-Group. I have this problem: 32GB of RAM is not enough for my complex geometry. I set the file paging dimension to 80GB on the SSD drive. So now the system has almost 110GB of memory available. Anyway VisCART crashes without reaching all the available memory: I'm watching the 'Commit' tab of the Memory on the monitoring resource display of Win10, and never it reach 80GB; it crashes when it reaches about 55GB. Does it depends on VisCART? Or Windows? Anyway is it useful to do this for very complex meshes? Is it possible that a software is not able to manage all that memory?

Is there a free tool to optimize the performance of the memory utilization? Is there a method to understand the problem? For example a tool that gets all memory status when a process crashes?

Is it true that this operation is dangerous for the SSD drives? Is better to use an old hard disk?

Thanks

Please give some input if u can.

I m getting higher value of natural frequency of shell structure following TSDT than that with FSDT using Finite element method. It should be the other way. I double checked my code written in MATLAB but could not find any fault or error.

How can calculate fracture load of three-point bending testing through strength and ductility data obtained from tensile testing?

and in three-point bending testing ,how to calculate stress distribution of crosssection beyond elasticity scope?

A q-ary necklace of length n is an equivalence class of q-coloured strings of length n under rotation. The number is

N

_{q}(n)=(1/n) \sum_{i|n}\varphi(n/i) q^iFor example q=3, n=3, N

_{3}(3)=11000 000 000

001 100 010

002 200 020

011 101 110

012 201 120

021 102 210

022 202 220

112 211 121

122 212 221

111 111 111

222 222 222

But

**if the first bit must take modulo 2**, then the answer is 4. For example001

002

011

122

Here 210=010, 001=201 , 000=200 and so on. Note: the first bit must take modulo 2.

What is the number of Necklaces in length n and beading of q different colors with the first bit taking modulo 2?

The collocation method is one of expansion methods which is used to approximate the linear and non-linear integral equations. This method can be used with basis functions such as standard polynomials {1,x,x^2,x^3,...}, Taylor polynomials, Chebyshev polynomials (first, second, third and fourth kinds) and others. What are the orders of convergence of collocation method with standard polynomials and Chebyshev polynomials ( second, third and fourth kinds)?