Modeling - Science topic

Model selection and modeling using MATLAB

For Modeling of Visco-Elastic Damper using link element in SAP2000, how can I get visco-elastic behaviour to the element.

Hello,

Can anyone suggest books/projects understand from basics about the grid following and grid forming inverters control in a microgrid?

I have been following papers, but I want a detailed description of the control and modeling.

Thank you

Throughout the literature, the Curve Number (CN) has been identified as the most sensitive parameter in hydrological models. However, in my project, when I conducted a sensitivity analysis, the CN number did not show the expected level of sensitivity. What could be the reason for this occurrence? Thank you.

Hello, fellow researchers!

I am currently experiencing an issue while conducting structural equation modelling on Jamovi software. The software is displaying an error message stating that 'this analysis has been terminated, likely due to hitting a resource limit.' I am curious to know if anyone else has encountered this issue before and if so, how they addressed it?

Any insights or suggestions would be greatly appreciated. Thank you in advance for your help.

I have thickness of nano membrane filter, pour size of membrane filter and initial & final concentration of wastewater.

Kindly suggest the names of the software used for Dynamic wastewater treatment modeling and energy analysis (for research purposes)?

Respected RG members

What are the pros and cons of modeling dynamics using psuedo- stochastic matrices as the transition matrix units?

I would like to ask if anyone could write a procedure of the modelling process for a NSM CFRP strip including part type, section assignment, material type to choose, interaction with the epoxy adhesive and the model choices of the epoxy..?

Hi, I have a small sample panel data consists of T=21 years and N=7 countries, with heterogenous slops and cross section dependence of my y and  most of my x's . I did the unit root test my variables are mixed stationary I(0) and I(1). What is the best modeling method? Thanks for your replies.

I am working on the project involving nucleate boiling . I am trying to model the same in the ANSYS Fluent software. Can some one help me with the steps for modeling nucleate boiling in this case.

I would be very happy to have suggestions from you all. Thanks in advance.

Regards.

Hi everyone,

I'd like to hear from anyone having advice on how to choose priors when modeling doing Bayesian stats using MCMCglmm or similar.

Any help would be great appreciated.

Thanks,

–PJ

Climate scientists have for over 20 years focused on emissions in their modeling of future scenarios of the global climate. These models, are based entirely on the level of greenhouse gases, particularly CO2, and include also the simulation of other factors such as El Nino and La Nina, the Great Conveyor belt, and ocean temperatures and the CO2 absorption by the oceans in the most advanced cases. Nevertheless, the modeling of future events is purely statistical.

However, the globe is undergoing dramatic changes in its core, and magnetosphere. First of all, the magnetic North Pole is drifting very fast away from the Canadian region and over to the Siberian region. It crossed recently the geological North Pole some years ago, and it is moving at an alarming speed of 8 meters pr day on its path. At the same time, the southern part of Africa is generating a massive anomaly on the magnetosphere which started exactly 160 years ago, coincidentally with the advent of the Industrial revolution and beginning of the massive emissions of CO2 from industry (1). At the same time, the Earth has started to spin faster around its axis, in fact so much faster that the clocks may have to be adjusted of some milliseconds. This is an increase in rotation speed of massive scale, considering the size of the planet, and it is attributed to the activity of the core of the planet (2).

40.000 years ago a similar dramatic event took place, where the climate changed very fast, and it may be connected to the arise of Homo Sapiens, and death of Neanderthals, by the rapid change in climate, the ability of the emerging Homo Sapiens to adapt to it, and perhaps, the effects the new climate had on the biological fitness of the new species to adapt to it.

In context with the multitude of changes that are occurring in the magnetosphere now in this period, and started to do so at the beginning of the increase in global CO2 emission, and the fact that we know it happened before, and generated changes in the atmosphere and also changes in climate gas composition, how is it possible that climatologists are solely basing their models on everything but the most widespread force of the planet, and also how is it possible that they don't include spin-effect of the globe on weather patterns (3)?

At the same time, there are very few studies on these aspects of the climate, and it seems they are also not popular in the realm of sources that are harvested by climatologists when they make their grim predictions.

Is the climatological field driven by bias and ignoring important physical phenomena on climate change?

1. https://www.sciencealert.com/mysterious-anomaly-under-africa-is-weakening-earth-s-magnetic-field?fbclid=IwAR2cULy_PJemofm9EqxXiN-H57DMoLyD2ddBcR4FEsnHCMgP6pkvGFDQFGA

2. https://www.forbes.com/sites/jamiecartereurope/2022/10/21/is-earth-spinning-faster-how-ancient-solar-eclipses-are-shedding-new-light-on-earths-rotation/

3. https://education.nationalgeographic.org/resource/coriolis-effect

Hello everybody, I am interested in catchment modelling and starting to read the research articles. However, I find it hard to conduct an experiment with GLUE estimate uncertainty in catchment modelling. Does anyone have a specific example that can help me with?

Thank you!

How to select bed material along with flow during the modeling of local scour around the bridge pier in ANSYS FLUENT?? Please provide some sources to tackle this issue.

i have a problem with reaction modeling by Ansys Fluent. when i change the Arrenius parameters, nothing change and it makes me confuse. can anybody help me?

I'm modeling a 4-point beam in ABAQUS, and I am wondering what the best way is to connect the reference points to supports (As shown in the picture below) is it a Rigid body (pin) or coupling?

I am trying to assess the quantitative impact of climate change on hydrological regime of a semi-arid subbain; and I can not select among different customary models.

please help me based on your knowlege and experience in water resources modeling.

SWAT? SWAT+? WEAP? HEC-HMS? IHACRES? or something else?

I would like to get your opinion about which open source tool is more reliable for battery aging simulation and performance evaluation? There are various open source tools such as PyBaMM or OpenFOAM. I would like to get advice upon your experience.

Thank you in advance!

there are six reactions that they are not linear or Arrhenius, so i need use some txt program to insert in app, but i don't know how? can anybody help me?

hello everyone I am modeling an impact problem via Abaqus. and my model consists of an impactor and a solid ball. The impactor impacts the ball through three different forces. and I extracted energy plots for all of these forces but I think they are not true because internal energy and kinetic energy didn't show an ending at the end of the plots. does anyone know if these plots are true or not and what should I do to have a better plot?

In structured equation modeling, we use latent variables.

Hi

I am modeling the compression of a plate in honeycombs on abaqus, but I find problems concerning the latter, my objective is to compare the results found experimentally and numerically, for the experiment takes place in a duration of 150S, but this period is very long for modeling and I couldn't manage to use all of this period in the step part!

Hi

I am trying to model a poro-hyperelastic material, but the problem is, this kind of physics is not present in any of the FEM software including COMSOL or ABAQUS,the comsol have a module only for poro-linear elasticity, but there are few papers on its modelling and they are using subroutine for that.

please help

I am an undergraduate student doing a thesis regarding slope stability analysis using PLAXIS 2D. My study area is at Kajang, Malaysia. I only assumed the phreatic water level because I don't have any borehole data. I have already done the model but I have questions regarding my model:

1. Is the water level that I have marked and assumed logical? (40 m above flat land)

2. What does the legend on the right represent, and is it the FOS? (The FOS that I obtained from the model is 1.780 as shown in the picture below)

3. Is the part that I have marked in the picture the critical slip surface (Picture 3)?

Thank you in advance for your help.

I'm trying to solve a set of equations of motion of a system by ode45 in Matlab.

My phyisical memory is 24 GB. Matlab can use up to 100% of the memory but it only uses less than 50% of it and surprisingly I face an 'Out of memory' error!

What do you suggest as the cause of this problem?

Hello everyone, I'm trying to understand the nondimensionalization of the study "Modelling cholera transmission dynamics in the presence of limited resources" by Farai Nyabadza, Jennifer Mawunyo Aduamah1 and Josiah Mushanyu. I just wanna know how the substitutions were derived in order for them to nondimensionalize the model. Please see the pictures for your reference. Thank you in advance.

Hello everyone.

I have data with three outcomes (two is binary and one is continous with poisson distribution) and around 10 independent variables. My objective is search for factors predicting one main outcome and two secondary outcomes. I came across structural equation modeling (SEM) and it has very interesting concept. I want to ask that putting all variable to fit correlation in one SEM (with all three outcomes) equation is more suitable than separately putting variables in each regression equation (totally three equations)? (Actually, I have tried to analyze accordingly and found that some significant variables in logistic/ linear regression turned to non-significant in SEM.) I want to ask your opinion that technically and scientifically using only one model should be more suitable than three models especially in single study?

Thank you.

Dear all,

I am modeling PCM in heat transfer solids and fluids using COMSOL 5.6, but I am facing some problems with the solution in the initial time steps (within 20 seconds).

The domain temperature goes below the initial temperature of the domain.

I am using a time-dependent PARDISO solver and time-stepping BDF. I am attaching an image for your reference.

Your answer will be highly obliged.

Thanking you all

Historical data feed

Hello,

I'm undergraduate student in my final year. I'm stuck with my thesis on how to get pareto formula because in journal only have the final function not how to get it. I used Journal from EMEL KIZILOK KARA (A Study on Modeling of Lifetime with Right-Truncated Composite LognormalPareto Distribution: Actuarial Premium Calculations). Attached are my work so far. Sorry if my english is bad. Please help me to solve this.

In rainfall-runoff modeling, it is often not possible to find the unique best parameter set, different parameter sets may be given similar good results during calibration. To reduce uncertainty and to define the optimum parameter set, it is a fundamental analysis of model parameters.

Remote sensing, mapping, modeling, Disaster

Hello everyone,

I need your help for the modeling of the alternator coil. i use lumped paramter model and distributed parameters model.

I would like to know how, t is what you do for the calculation of the different parameters; because I did it, I can't find results that agree with the laboratory tests.

Please can you help to have the good values of parameters?

I would like to simulate a k-tier Hetnet or Self organized network (SON). Let’s say if k = 2, then we would have macro cells and small cells. UEs may connect to macro or small cells per certain mobility load balancing conditions. How can this be simulated in NetSim or in some other network simulator? Are there any good reference papers?

I am modeling an underground structure with fixed support conditions around the exterior walls. I would like to apply different ground acceleration time history data into specific nodes (joints) of the structure. Is this possible in SAP 2000? I would appreciate any guidelines. Thank you very much!

Industry 4.0 technologies, including Big Data Analytics technology, are used in multi-criteria processing, analyzing large data sets. The technological advances taking place in the field of ICT information technology make it possible to apply analytics carried out on large sets of data on various aspects of the activities of companies, enterprises and institutions operating in different sectors and branches of the economy.

Before the development of ICT information technologies, IT tools, personal computers, etc. in the second half of the 20th century as part of the 3rd technological revolution, computerized, partially automated processing of large data sets was very difficult or impossible. As a result, building multi-criteria, multi-article, big data and information models of complex structures, simulation models, forecasting models was limited or impossible. However, the technological advances made in the current fourth technological revolution and the development of Industry 4.0 technology have changed a lot in this regard. More and more companies and enterprises are building computerized systems that allow the creation of multi-criteria simulation models within the framework of so-called digital twins, which can present, for example, computerized models that present the operation of economic processes, production processes, which are counterparts of the real processes taking place in the enterprise. An additional advantage of this type of solution is the ability to create simulations and study the changes of processes fictitiously realized in the model after the application of certain impact factors and/or activation, materialization of certain categories of risks. When large sets of historical quantitative data presenting changes in specific factors over time are added to the built multi-criteria simulation models within the framework of digital twins, it is possible to create complex multi-criteria forecasting models presenting potential scenarios for the development of specific processes in the future. Complex multi-criteria processes for which such forecasting models based on computerized digital twins can be built include climatic, natural, social, economic, pandemic, etc. processes, which can be analyzed as the environment of operating specific companies, enterprises and institutions.

In view of the above, I address the following question to the esteemed community of researchers and scientists:

What is your opinion on this issue?

Please answer,

I invite everyone to join the discussion,

Thank you very much,

Best wishes,

Dariusz Prokopowicz

Dear All

I am trying to simulate the bond behavior between concrete beam and CFRP using ABAQUS.

I tried different ways to do so, but no one works. I got the following errors as in the attached pictures.

Thanks

Leakages of frigo fluid, will alter the COP of a chiller.

Is there a modelisation of this ?

something like COP = f(frigo fluid completion), whatever simple or complex ?

many thanks !

Dominique

The soil properties such as soil pH, moisture, temperature, NPK, Carbon content, texture, etc forms important parameters for the growth and distribution of a plant. And for distribution modelling of a species, the raster dataset is required. How can I acquire that?

in the flexural 3PB test, a concentrated displacement load would be applied to the top middle point of a beam. For modeling one-half of the beam using symmetry, which nodes or edges do you think should the roller and load point be assigned to avoid coincident of the BCs and errors relating to stress concentration in a nodal load point (after meshing, image attached)? is it not a better idea to assign the displacement load directly to the whole side edge using these BCs ( U1=0, U2=Value, U3=0, UR1=0, UR2=0, UR3=0)?

any idea would be appreciated.

Dear Researchers,

As you know, it is possible to generate the code of modeling in SpaceClaim and FE analysis in Ansys. However, I do not know how can I connect the codes of these sections.

I Ansys Apdl, it can be generated completely but I do not know how can I do it in Ansys workbench.

In majority of current literatures, the two words are used interchangeably. Although some works distinguish the semantic difference between them (Tumeo, Mark. 1994. “The Meaning of Stochasticity, Randomness and Uncertainty in Environmental Modeling.” In , 10/4:33–38.), the difference in the detailed modeling techniques is still unclear.

Is alphafold able to incorporarte ptm data ?

How can we calculate the number of dimensions in a discrete space if we only have a complete scheme of all its points and possible transitions between them (or data about the adjacency of points)? Such a scheme can be very confusing and far from the clear two- or three-dimensional space we know. We can observe it, but it is stochastic and there are no regularities, fractals or the like in its organization. We only have access to an array of points and transitions between them.

Such computations can be resource-intensive, so I am especially looking for algorithms that can quickly approximate the dimensionality of the space based on the available data about the points of the space and their adjacencies.

I would be glad if you could help me navigate in dimensions of spaces in my computer model :-)

Advice on tsunami modeling using COMCOT Software...

Applying mathematical knowledge in research models: This question has been in my mind for a long time. Can advance mathematics and applied mathematics solve all the problems in modeling research? Especially the formula derivation in the theoretical model part, can the analysis conclusion be obtained through multiple derivations or other methods? You have also read some mathematics-related publications yourself, and you have to admire the mystery of mathematics.

I am having difficulty in modeling interface in VASP so that I can relax it.

I could not find an example of inputs for modeling interface.

If anybody can check my inputs in the attachments or guide me in any other way, I would appreciate it.

Which of the following is the best for estimating phonon contribution: a non-magnetic analogue or Debye-Einstein model?

Hi!, I'm currently on a investigation project that consist in production of charcoal by slow pyrolysis of wood. As we know, the products of this process is char, syngas and tar. The thing is that we want to minimize this tar production because its complicated usage. For what we saw, the tar can be degraded to volatile non-condensable gases and avoid that liquid phase. The temperature we are modeling the process is about 400-450 ºC,. My question is: is this enough to only have coal and syngas at the end of te process?. If not, how can we avoid the tar production and only have syngas as byproduct? I hope I have explained myself well.

Thanks!

📷

I am working on modeling of Direct Contact Membrane Distillation system with COMSOL Multiphysics software. I have some problems with the mass transfer part of the simulation because I don't know which boundary condition is appropriate for boundaries between membrane-cold and membrane-hot channels. Is anybody knows how I can solve this problem?

When modelling the softening behavior of quasi-brittle materials as concrete, mesh sensitivity is very important unless we use a regularization technique. In tension there are many available in the literature, but what are the techniques available for compression?

I had written a paper few months ago and its prepreint is floating online.

Query: I want to add more additional results along with modeling in that paper and submit it to some other journal. Can I do the same because a preprint is already floating online? Won't it count in the plagiarism count by the detector? I mean I know preprint is also my earlier version of the same paper but software dont.

Kindly help me with this.

Actually I am new in this field. Also this research topic is readily new. So, I need a preferable software to work with this topic. I can't progress my work without any reliable software

Hello, I am looking for documentation related to the WinITDB model for tsunami simulation, I have not been able to find results on the web. I hope to have your help, thank you.

I am working on modeling coronal discharge formation and electric breakdown in a non-uniform electric field with air as an increasing velocity medium. I can find plenty of tutorials and articles about electric breakdown in air, and transformer oil, but none of them are moving. I am using COMSOL.

Modeling how coronal discharge onset and breakdown voltages change as a function of air velocity moving through the cylinder between electrodes is the question. To be honest, it seems more straightforward and useful to set up the experiment and get empirical data since we need to know this for the next steps of research. However, worth asking.

How do I scale and translate the model, OR how can I adjust the dynamic range to accommodate my model size. I have this problem when trying to simulate an antenna in CST in micros. Anyone, to assist?

Agent-based modelling (ABM) is a widely used modelling approach in different areas.

By allowing the simulation of several heterogeneous "agents" and their interactions, the ABM approach has been used in a lot of research.

In this question, I am trying to conclude the application of ABM in different disciplines, and conclude why these researchers use it.

I ask the same question in Zhihu(知乎)

多主体建模（ABM）可以用在什么课题的研究上？ - 知乎 https://www.zhihu.com/question/551001659

Hi,

I am looking at the three-way interaction of a latent variable (F) with ordered-categorical indicators (mostly likert scales) and two observed variables (M1, M2), using Mplus. The two following issues arise:

1. How do I account for the ordered structure of the indicators? Do they need to be defined as categorical?

2. What does this mean for the standardization of the latent construct (F)? Standardizing the indicators does not seem appropriate!

Any advice or guidance is greatly appreciated. Thank you in advance!

Is there is any differences between modeling using Mplus and HLM

Hello:),

for the above inquiry which software is most accurate/easy to implement?

Thanks:)

Joel 💡

If I have a protein sequence without any structural information. Can I determine the oligomer forming capacity of the molecule after modelling? Are there any tools or calculations to determine this as well?

I want to model a plate spring model in comsol , a type of model attached with this discussion.

How can I model this type of geometry ?

Hello dear all,

We want to set-up a CFD -Discrete Particle Modelling case for a bubble column where liquid is eulerian and gas bubbles and solid particles are discrete phases (three-phases total holdup <10 %) as given in attached diagram. In this case only gas bubbles are flowing with velocity UG <1 cm/s while liquid and solid particles have no initial velocity (means batch mode). Boundary condition (DPM) for gas phase at outlet is pretty straight forward "escape" but we want to retain second discrete phase "particles" with in column volume. However, Boundary condition panel in Ansys Fluent do not show "escape" or "wall" or "reflect" for an individual DPM (injection) phase but one for all DPMs.

We want to model the effect of gas bubble induced flow behavior (in one-way coupling) on liquid and solid phases, so we need to keep liquid in batch mode and solid phase (one-time injection). Any suggestion on how to set-up DPM-BC for two discrete phases (two different injections) separately in Ansys Fluent?

When I was a Student, I used to find the modelings of mechanical systems unclear. The problem of students is that they can't find easilly the suitable modellings for their studies.

Hence, I am inviting mechanical engineering Professors to be volunteers in a New Project that gathers very simple and clear modelings of all the mechanical systems that students may encounter in their high Studies. The Project will obviously need endorsers of mechanical engineering in order to make the gathered works available even in Arxiv community.

Hello,

I am working on growth in an avian species. The model that fits the best on my data is the Morgan-Mercer-Flodin (MMF) model. I am surprised to note that this model is compared with others so rarely in the majority of the studies, rather than Gompertz, Logistic, Richards or Von Bertalanffy models. I tried to understand why but I was unable to find a reason.

Would someone have an idea about this issue?

Thanks a lot.

Hello,

I have credit risk/default data for probability of default modeling. Indeed I need to give credit score each costumer. As I know, initially I should model scores and then calibrate it into PDs.

Can you share me some materials/literature about how to estimate/calculate credit scores?

Thanks

Hello everyone,

I am modeling an RC bridge pier under constant axial and cyclic load in ABAQUS software. The concrete is modeled with the CDP model. The step analysis is used as Dynamic implicit Quasi-static.

The result of the hysteresis curve is different from the experimental result as shown in the figure. I tried several methods but could not get the desired result.

Any recommendation on why the results are not matching?

Thank you.

I was trying to model a system with several chlorophyll molecules and carotenoids. For adding hydrogens, I used chimera which is working perfectly well for carotenoids. However, the chlorophyll molecules are not getting pronated in the desired manner. There are discrepancies in the number of hydrogen atoms. Sometimes, these packages fails to identify the valencies correctly. The results were even worse when Pymol is used. Previously, I used HAAD for this purpose. Unfortunately, HAAD is not giving any outputs this time (only getting 0 KB files). I need to add hydrogens to these molecules before setting up a system in GROMACS. How can I model these chlorophyll molecules accurately?

I'm studying about this issue and would like to modelling it in Econometrics moreover modelling it with various Energy Modeling.