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# Stability Analysis - Science topic

Explore the latest questions and answers in Stability Analysis, and find Stability Analysis experts.
Questions related to Stability Analysis
Question
I have two years and three location data. How to prepare file for stability analysis?
The data were recorded on different agronomical traits on wheat crops with two years and three location. the question is that how to calculate stability, means GxE interaction. And suggest to me which is the best method for stability analysis.
Question
Nonlinear Differential equations, stability analysis
Firstly, try to change the second-order nonlinear system of equations into a first-order linear/nonlinear system of equations, then calculate the eigenvalues of jacobian matrix, if all the eigenvalues have a negative real part , implies the system is stable otherwise unstable.
Question
Most of the researchers use performance standards for stability analysis such as Integral square error (ISE), Integral absolute error (IAE), Integral time absolute error (ITAE), and Integral time square error (ITSE). So how can we know which one would be the best for my work, especially for power system applications when selecting an objective function?
In fact the ISE, IAE, ITSE, and ITAE indexes depend on the control system performance requirements. Usually, they are used to tune the controller and are problem-dependent. So the controller optimally tuned for ITAE can give worse results in other indexes, and shouldn't be compared with the controller tuned for ISE (for example).
Question
Two synchronous machines with different mechanical torque inputs of say 2 Nm to 17 Nm for machine 1 and 5 Nm to 15Nm for machine 2 are to be specified in the form of droop control for stability analysis. An idea on how this could be implemented in MATLAB would be so much appreciated. Any relevant journals that could be of help would also be appreciated..
Irfan Qaisar thank yor for the recommendation
Question
Researchers. I want to make a global stability analysis to a prey-predator system, which includes eco-evolutionary feedbacks. After literature survey, I found that Lyapunov function and Krasovsky method may be the suitable ways to that question. So, is there any Software or Package can be used resolve that question? Or, I have to analyze it by hand?
hi,
kindly refer this lik:
Question
I know that tensile strength can reduce crack length in a dam joint, but does it help fix overturning of a dam? or is it necessary to use post-tension anchor to fix overturning.
Thank you
Chengyong Gong Thank you professor. I am still an entry level engineer. graduated from school just recently. Looking for some mentoring from fellow engineers here.
Question
Hello everyone.
I am currently doing a dam stability analysis. I am analysing dam piers indepently of the spillway. According to the results, the piers are not stable in slip. But my design criteria are too conservative, because I did not take into account shear keys.
I tried to find documents on how to consider shear keys at the admissible limit state, but couldn't find anything. Can anyone guide me?
I agree with the responses! Additionally, all the factors influencing the shear key resistance should be taken into account in the calculation, in order to get high precise results and thus properly ensure the dam stability!
Question
As riaxial test is used for determination of soil cohesion and friction angle etc. through three different procedures viz., Unconsolidated Undrained, Consolidated Drained and Consolidated Undrained (UU, CD and CU). Now my query is that which of the above three procedure is best suited for testing of soil samples for the purpose of slope stability analysis.
My samples are from Sikkim in Eastern Himalaya, India, which is basically a metamorphic terrain.
Dear Kuldeep,
Nice to hear about your research work..your question is what type of triaxial test is to be conducted for soil samples collected from landslide. It is simple understanding that if you need to verify the short term stability of slope than you need to conduct CU test or if you want to verify the long term stability slope than use CD test results. As you know CU test is quick as compared to CD test..so depending upon your design requirements you have to use either CU or CD test..ok all the best..
Question
FEM has widely been used for large scale point specific slope stability analysis. I am looking for a program to perform FEM that is available for free and also stands up to research standard.
Question
Can anyone share articles and papers that use Lyapunov's direct method to prove global stability analysis? Or is there any technique for constructing Lyapunov functions, especially for equations with saturation treatment functions. Your help will be greatly appreciated. Thank you!
Yes, there is. You can find many articles in the engineering journals, typically in the field of systems and control. In electrical and mechanical systems, many Lyapunov function candidates can be constructed using the 'energy' concepts. For constrained systems, Barrier Lyapunov Function candidates are usually proposed.
Question
If you build a parameter learning algorithm based on the Lyapunov stability theorem for updating the parameters of an adaptive fuzzy controller, how to determine the cost function and Lyapunov function? Is there a physical connection between them?
Lyapunov function is a point-wise measure of energy, whereas, cost-functional is an interval-based measure of energy. In this sense, you may connect them by assuming Lyapunov function as an explicit function in time which could get a negative decay-rate assuming V=x^2, and then a closed-form dissipation as; V_dot=-K*V(t) for stabilizing a system, see my pre-print at the URL:
Meanwhile, optimal quadratic cost functional, minimizes energy as a sum of the squared state and control signal during a time-interval as; J=int(x^2+u^2).dt, from zero to T. Please see the paper:
Nonlinear Optimal Control: A Control Lyapunov Function and Receding Horizon Perspective (1999)
The control performance could be different through the two scopes, and the energy consumption could be also different.
Question
I'm Performing slope stability analysis using FLac3D. 6.0. the constitutive and seismic waves seem correct, but the software still refuses to perform
Hello
Check the dynamic boundary conditions and damping and mesh size.
Best,
Rashiddel
Lecturer FLAC 2D - 3D software
Question
For the discrete-time Extended Kalman filter (EKF), a stochastic stability analysis is discussed by Reif et al. in their paper "Stochastic stability of the discrete-time extended Kalman filter" (https://ieeexplore.ieee.org/abstract/document/754809). Recently, there have been works on EKF with unknown inputs, in particular, for arbitrary unknown inputs. Are there any works providing such stability analysis similar to Reif's work available for these EKF with unknown input filters?
Yes, these articles might be useful to connect all the dots together, have a look:
Kind Regards
Qamar Ul Islam
Question
sign(t), normally, does not have a Laplace representation. In sliding mode observer based approach, we use the sign of the estimation error. Then, a Lyapunov stability analysis follows to ensure stability of the particular observer. However, if one wants to evaluate the overall closed-loop stability analysis, Laplace transformation is conveniently used. Now, sign of the estimation error in digital environment is like a unit impulse function at kth sampling time. Therefore, would it be correct to represent sign(error) in Laplace domain as a shifted Laplace of a unit impulse function? Does anyone has a particular idea about this concept? I would be happy to have any information regarding this.
Kind regards to you all.
I suggest that you graph the function in question and try to find the Laplace transform of the graph.
Question
How can one do slope stability analysis in FEM or FDM for unsaturated soil conditions and fully saturated conditions?
Dear Pandit,
In order to model the unsaturated soil behaviour, we have to model it hydromechanically. It means that first, we have to model the hydraulic behaviour of soil in which the soil-water characteristic curve and unsaturated hydraulic is vital to be found. Then, must include the SWCC and unsaturated hydraulic conductivity to simulate the soil behaviour mechanically. For doing this, we can use ABAQUS, Plaxis, GeoStudio package, and ... For more details, you can refer to follows papers:
Question
Contiguous pile design?
Like
1. how to find pile stability analysis below the dredge level.
2.How to find Young's modulus and Poisson ratio of soil.
3. if i have "n" Number of pie value and cohesion value. In which value may I use to calculate the stability analysis like higher pie value or else lower pie value and also cohesion higher value are lower value.
Question
In mathematics and physics, a nonlinear partial differential equation is a partial differential equation with nonlinear terms. They describe many different physical systems. I'm especially seeking the stability approaches of fractional nonlinear partial differential equations that do not require linearization. Share your opinion.
Azhar Iqbal
Thanks
Question
Employing the terminal slidning mode technique (S. Yu, X. Yu, et.al., doi: ) for the second-order uncertain system to achieve finite-time or fixed-time stability, the control input and the velocity state will overshoot by a large amount during the system evolution. See the attached graph for details.
Is there a effective scheme to avoid such phenomenon?
Chang-Duo Liang, try to reduce the value of K. But, as long as Ksign(s) is a bound term, I don't think it can cause any problems or overshoot.
Rember that in sliding mode, one constraint the motion of system to lower-dimensional sliding manifolds. So, overshoot is not commonplace in a good design. i,e. suitably designed sliding surfaces.
Finally, check the initial conditions. Try to choose the ICs on the sliding manifolds.
Regards,
Question
can anybody help me to brief about how to do stability analysis in plant breeding, based on wheat rust data how can i do the stability analysis for wheat rust resistance and how much time it take to do that
AMMI and GGE biplot analysis can be used
Question
Can we check the positive definiteness of a multivariable polynomial using MATLAB functions? Of course in literature, there are few complex methods that use tensor algebra. However, before going to such methods if you have some simple suggestions that will be appreciated. In a stability analysis of systems, It is usually required to check that whether the obtained Lyapunov function is positive or not for x>0. For example, if we obtained the following Lyapunov function with these parameters:
a1 = 0.689 a6 = 0.368 a7 = -0.238 a8=-0.336
That particular example is in a homogeneous form. But if the obtained polynomial is in a nonhomogeneous form then what will be the way to proceed? If we have more than two variables (e.g x1, x2, x3, x4,...)? Please correct me if I am wrong in statements.
Thanks for the suggestion.
Question
Hi
I'm looking for a book for discretization schemes in dropwise condensation and stability and consistency analysis of it.
thanks
Question
1-In System Frequency Stability Analysis(SFR), what is the difference between the Deltaf, DeltaP and RoCoF? What is their connections together? For example, if one parameter increases and another decrease, what should I get from it?
2- In a microgrid, if the total inertia of the system increases, what is its impact on DeltaP(Active Power Injection) of each Distributed Energy resources response? what is its frequency response requirement in Mw?
Thanks :)
As I know, Governors, who are tasked with increasing or decreasing the output of generators in the event of a decrease or increase in network frequency, set up a Dead Band so that they do not act in exchange for small changes in frequency. This will prevent the equipment from malfunctioning. Because the governor is a mechanical device anyway, and if he wants to react to any small change in the network frequency, it will break down very quickly.
But, my Question is how can it be implemented in a system and how can we do System Frequency Response assessment with that?
Question
The time step constraint is not sufficient to guarantee the stability of numerical scheme in any case. This constraint is only for the convection terms. Additional constraint is required for the source term. Can you please help me that what are those additional constraints if source term?
If by 'stability constraint' it is meant 'restriction on the Courant number', clearly this only refers to discretized convection (I prefer to say 'advection') equations. Any other term that you have in your (spatially) discretized problem may entail other, possibly more restrictive, stability conditions. A linear source term like
the right hand side of
y'=-k*y
entails a stability restriction of the kind | k* h| < constant where h is the time step
and the constant depends on the time discretization method (constant =2 for explicit Euler). A source term that does not depend on the solution, like the right hand side of
y'=f(t)
where t is time interpreted as the independent variable strictly speaking does not entail a stability constraint, since the discretization of this equation is equivalent to the computation of a definite integral of f. However, if your time step h is such that the behaviour of f is not properly sampled (imagine for example f(t)=cos(omega*t) with omega = O(10) and h=O(1) ) then your discretization will never be giving you accurate results and h must be reduced to sample f properly.
Question
I want to simulate IPFC for small signal stability analysis in SMIB and Multi-machine power system.
Very interesting question! Follow
Question
I would like to assess the stability of the 18 papaya varieties growing in the same environment for two years.
I am not aware of this model since i hail from Agronomy background. You can read the following article for further information.
Question
How can one do slope stability analysis in Plaxis or RS2 for debris slopes, during and after rainfall if the rainfall intensity is known?
Mr.Koushik,
Slope stability analysis in PLAXIS software can be performed by varying the ground water level with respect to time and study the response due to change in ground water level. This depicts the water level before and after rainfall. If you want to simulate debris flow in analysis, first you need to select the region that would fall after rainfall..this can be simulated by applying displacement as boundary conditions and study the response due to change in displacements within the selected region. i suggest you to read PLAXIS manual and collect literature related to your study is available. Find attached the paper related to the work for your reference. all the best in your research..
Question
I'm doing my project on slope stability analysis under earthquake load and building load using Plaxis 2D software. For the earthquake input load a would like to Know how to form the earthquake input load from the response spectrum as I mentioned above and also I would like to know about the procedures for doing dynamic analysis for the slope under earthquake load.
If you still didnt get response then my answer is applicable.
1. Try to look for velocity spectrum in Kangra Earthquake papers. Even if papers dont share data, get the figures.
2. Extract data from figures.
4. Select time query points.
5. Run the analysis.
Question
In eart slope stability analysis by SLOPE/W Analysis
Dear Dr. Maysam,
I think that the probabilistic and sensitivity analysis may be enough. But, for intensive results and comparisons, you have to consider the statistical analysis. The choice may depend on the nature of your application and research work.
Good Luck!
Question
I am working on an algorithm that receives 4 pulsating inputs to produce two continuous outputs. A numerical model that enables numerical simulation is all that I have in hand. However, the practical value of the system can't be assured unless a stability analysis can be conducted. My question is: how to assess such algorithm stability while I don't have a dynamic model of the algorithm in the frequency domain?
Hi Dr. Chak,
Thank you for your answer. It will be highly appreciated if you can support further (if possible, please examine the attached Simulink file in Matlab208A format).
My algorithm (the block with light-blue background) receives three-phase bipolar signals in addition to a fourth slowly changing positive signal. The frequency of the three-phase signal can change between zero to a known upper bound (changing rate is limited to a known limit as well). The algorithm's objective is to continually track the phase angle of the input three-phase signals. By stability is meant, the algorithm can keep tracking of the phase angle of the input signals infinitely!
The process within the algorithm is highly nonlinear and as I said only the Simulink numerical model is available (attached)
Question
I have some varieties and there performance in relation to the yield and contributing character are varrying across th location and season. Canany one suggest free and best software for cropyield stability analysis?
PROGRAM GENES:
Here are many methods, select according to your need.
Good luck.
Question
I have designed an observer based control strategy. Now I want to analyze its stability analysis. So my query is; that we must sort out the stability of the closed-loop system or we can find it for a separate section.
First, before designing an observer-based control scheme, you have to ensure that the separation principle holds for that. If the separation principle holds, then we can say the stability can be guaranteed individually, i.e for controller and observer.
Question
To verify the model simulation data is not enough. To support the research, I need to authenticate and synchronize the model with the original data. If anyone is familiar with it, please help me out.
Ok, l understand
Question
Whath does a pair of equal floquet multipliers signify in stability analysis
Pl. go through attached article.
Question
Hello Sir/Mam
i have query regarding designing of SRAM cell
1. What are the parameters those should be analyzed in designing of SRAM cell?
Average power consumption, leakage power, leakage current, delay, stability analysis, pdp
2. how can be performed process corner analysis or monte carlo simulation in sram cell design ?
what it will provide?
how can be performed process corner analysis or monte carlo simulation in sram cell design ?
what it will provide?
Question
This is a monetary question:
There are products like the Phoenix LiDAR Systems. Attached to a drone it is possible to mine highly precise geospatial data very fastly.
Would universities around the globe buy these data sets for research purposes? Is it conceivable to sell them or to get a job from universities or other companies to investigate a certain area as a freelancer? How much would they pay approximately per squaremeter?
Geologists could also mine the data with these Systems and subsequently analyse it on site or at least in reachable distance with their knowledge e.g. for terms of slope stability analysis and then sell their findings and reports. Does this sound anyware feasible or is it complete and utter nonsens in terms of organisation or financially?
There are many companies around the world flying different Lidar scanners for different purposes and they only exist because indeed someone is prepared to pay good money for the data. Many of those are multi-million dollar aerial systems in aircraft or helicopter, i think you are looking at UAV based solution though.
To attempt any freelance work with the Lidar unit you mentioned would be a waste of time however, the data precision and accuracy would not be considered good enough for the majority of end users.
A much higher level unit such as the Riegl Mini-VUX or the VUX-1UAV would operate well in that environment and with an appropriate IMU and GNSS/RTK system produce survey grade results of some value to an end user.
Question
Hello,
I plan on investigating whether serum/plasma/exosomes is a better model to study miRNAs. For this, I would want to perform a stability analysis on my serum and plasma samples, that are enriched with exosomes and those that are not enriched. I know that addition of RNAse inhibitor would indicate the stability in samples enriched in exxosomes, but can someone let me know how much amount of this inhibitor should be added to each of the samples? And a detailed process on how to go about with this? Suggestions and inputs on this would be greatly helpful.
Thanks,
Hello Lv July ,no I haven't got to resolve the question. I was only able to compare the total RNA yield between the serum and plasma samples, and on an average I found that plasma had way more higher RNA than the serum. In general, people are inclined more towards using plasma for exosome studies, because serum is subject to coagulation.
Question
What are the assumptions involved in idealising the earthquake forces as static forces and what are the shortcomings of this method?
Idealizing the earthquake forces by static forces is an approximate approach and is applicable only when there is one dominant mode shape of the structure.
Question
I am working on oil in water emulsion. i wanted to know that if i make a 250 ml emulsion of 60% oil and 40% water containing 1000 ppm surfactant and remove 50 ml from it for stability analysis. so i am left with 200 ml containing 60% oil and 40% water with some surfactant while rest of the surfactant in 50 ml sample i removed. so inorder to convert the 200ml of 1000 ppm surfactant emulsion to 2000 ppm emulsion, I just need to add required extra surfactant according to total volume i.e. 200 ml. is this the right way? i am assuming complete mixing since i am mixing for 1 hour
Please elaborate why you want to do it this way
Question
Hi,
I would like to know if there is any free or paid software that includes the effect of the plants (hydrological and mechanical) in the slope stability analysis?
Question
SLOPE/W is a limit-equilibrium based software used to find FOS of a slope against instability. I am not sure what FLAC is used for and what is the difference between the two?
Hi, there are pro and cons for each software.
Slope/w is widely used tool due to easiness and less cost. This program is developed based on Limit Equilibrium methods. The limit equilibrium method of slices is based purely on the principle of statics; that is, the summation of moments, vertical forces, and horizontal forces. The method says nothing about strains and displacements, and as a result it does not satisfy displacement compatibility. Due to this, we don't know the deformation of stable and unstable slope.
FLAC is finite difference method and needs a lot of time to generate model, meshing and assiging suitable constitutive model and to run. In FLAC you can write the program as per your /client requirement. It is more versatile and much costlier than Slope/w.
Question
Am using an IEEE 14 bus as case study for voltage stability analysis, and i noticed that the lengths of transmission lines always considered as zero in some papers while any transmission line has its own actual values. Thanks in advance
OK, thanks a lot Engineers
Question
Am using an IEEE 14 bus for voltage stability analysis with wind turbine , so i need the mdl file of original IEEE 14 in PSAT, not the in simulink matlab
Attached you will find the required model. You will find four versions of identical main network. We already used this system for studying the dynamical aspects of integrating solar-PV sources to this system,
Good luck
Question
Hi,
I am looking for a good reference for hybrid continuous-discrete dynamic stability analysis using linear matrix inequality approach.
Best,
Thank you, Mohamed-Mourad Lafifi and DJILANI KOBIBI Youcef Islam.
Question
Please provide me more about Evans function for stability analysis with different examples. I will be grateful to those who will share their knowledge and work of related to the Evans function.
Thanks to all.
Good morninhg
I found those reaserches
Ingrid
Question
The generally used performance criteria in stability analysis includes Integral time absolute error(ITAE), Integral square error (ISE), Integral time square error(ITSE) and Integral absolute error (IAE). What is the physical significance of ITAE, ISE, ITSE and IAE?
Norms don't go to zero, unless error is always zero at all time instants.
The time-integral criteria are generic and comprehensive tools to evaluate the performance of a control system.
a system may have good rise time, but poor settling time. or vice versa. other basic criteria to evaluate the performance of a system are the overshoot, the steady state error. but all of these describe only one characteristic
time-integral criteria are generic and comprehensive. they allow comparing between different controller designs or even different controller structure.
as mentioned in an earlier answer, the physical meaning of these criteria is: each one is a function of the error profile (in time) of the output.
Question
I want to link matlab to opensees to complete the dynamic stability analysis of a 2D frame
You can use the following command and put your file name instead of "Dynamic.tcl"
! OpenSees.exe "Dynamic.tcl"
Question
1. What are the benefits of the current slope stability software programs, to solve the problems? what are the shortages of these software programs?
2. Why we need this review ; why we still need to new methods on slope stability? what are the limitations of current methods especially limit equilibrium method ?
3. what are the  Limitations of Limit Equilibrium Methods; how can we find new methods; what should we do in the future?
Dear Muhammed,
Slope stability consists of numerous methodologies including Limit Equilibrium Method (LEM), Finite Element Method (FEM), Boundary Element Method (BEM), Rigid Element Method (REM), Limit Analysis Method (LAM), Discrete Element Method (DEM) as well as hyprid methodologies such as Finite-Discrete Element Method (FDEM) and many others that I may have forgot to mention.
These methodologies have all some advantages and disadvantages over one another. Infact hyprid theories have been continuously developed to overcome these facts. Many software packages have been written over the years but almost all of them have some limitations in every methodologies they represent, because developers need to simplfy the complex algortihms as much as possible to decrease mainly the time consumption of the development. Also please bear in mind that they are generally written commercially.
As I mentioned every theory have some limitations, considering LEM cannot represent the post failure situation of an instability nor the mechanism. Also, It ignores the deformation characteristics of the materials and many assumptions need to be made such as inter-slice force fucntions to represent the magnitude of forces between each slice.
Additionally, you need to have decent understanding of each theories to be able to develop a new method, which I honestly think that there is no need at this time since many analytical solutions are already present.
Best Regards
Bekir SF
Question
I have a small query and I would be glad if you could answer it. I would like to know, is there any official document/guidelines, they may be by the FDA or any other regulatory authority, which states about the minimummass balance you have to achieve during forced degradation studies.
None as I recall. No mass balance is 100% since we don't count the water produced as an example. Thus, 85% is acceptable if it can be justified scientifically.
Question
I am working on oil in water emulsion. i wanted to know that if i make a 250 ml emulsion of 60% oil and 40% water containing 1000 ppm surfactant and remove 50 ml from it for stability analysis. so i am left with 200 ml containing 60% oil and 40% water with some surfactant while rest of the surfactant in 50 ml sample i removed. so inorder to convert the 200ml of 1000 ppm surfactant emulsion to 2000 ppm emulsion, I just need to add required extra surfactant according to total volume i.e. 200 ml. is this the right way? i am assuming complete mixing since i am mixing for 1 hour
' I just need to add required extra surfactant ' - ideally you remove part of the continuous phase for dilution. It's surfactant content is different from the overall surfactant content because depending on droplet size distribution considerable amount is adsorbed onto oil droplets or even distributed into the oil phase.
Should be better to dilute with plain water.
Question
I am looking for a slope stability analysis software package with at least 10 licenses with reasonable cost for my advanced soil course (student's vergin). Is there any free online one??
GeoStudio is fine. You don't need a license to use the (limited) students version
Question
I want to know about good statistical packages for analysis of plant breeding trials like multivariate analysis, generation mean analysis and stability analysis. I am using R, SPSS and PBTools but I am not getting the desired results due to certain limitations. Please let me know is there any free version available for GENSTAT or any other biometrics packages for smooth analysis.
Dear Dr. Kaushik Kumar,
Yes, you can check equality of means using MINiTAB.
Regards
Vishwanath
Question
On what parameters the selection of continuation method depends ?
We have proposed a numerical method (denoted as MEM) for solving the
Nonlinear Dynamic problems. If you would like, you can view our published articles in this field entitled "dynamic analysis of SDOF systems using modified energy method". By the way, the presented idea is also generalized to MDOF systems in another study, which is available on my research-gate account.
Regards,
Jalili
Question
I have a soil moisture data of a soil profile (9meter) that is prone to landslides which we measure moisture content per meter. I would like to use it to assess Factor of safety using slope stability. Is there a way to put the specific water content at every meter on the rocscience software or any other related geotech slope stab software?
Question
Dear colleagues
I am trying to acquire the graph of probability of failure versus factor of safety. In other words, I would like to depict a figure in which the vertical axis shows the probability of failure and the horizontal axis shows factor of safety.  As a result of random set theory, the cumulative density function for factor of safety has been calculated. That is to say, there has been a graph in which the vertical axes shows cumulative density function and the horizontal axis shows factor of safety. The question arises here, how the probability of failure for each factor of safety would be derived from cumulative density graph of factor of safety?
Should I use fragility function in order to obtain probability of failure?
I would be pleased to give you any further information that you may request.
By definition, a slope fails with a FoS going below 1.0. As long as the FoS is above 1.0, a slope is considered stable. Thus, I do not see how your figure could be drawn.
Of course, the FoS is a simplification and can not be measured directly. However, the definition is rather clear and if you follow it a FoS>1 relates to zero probability of failure.
Question
How to analyze the stability of stagnation point flow over stretching /shrinking sheet, i mean i have seen some papers on which they find dual solution for certain range of parameters. Can anyone suggest me some good books or papers on stability analysis for fluid flow?
I think the following papers may helpful for you.
Question
I am trying to reproduce the the examples of "Stability Analysis and state-feedback control of LPV systems with Piecewise constant parameters subject to spontaneous poissonian jumps", i am trying to implement them, on SOS tools, but somehow it seems to be impossible, Any help and suggestion will be highly appreciated, Thanks
best regards
Question
Dear Sir,
Dear Syir,the main differences between 2D and 3D slope Stability analysis in terms of factor of safety.
Dear Mr.Hassan,
The influence of intermediate stress in 3D analysis will influence the factor of safety of slope. The factor of safety of 3D based analysis is lower than the 2D based slope analysis. all the best in your research..
Question
Bode plot of system can be used to explain its stability instead of pole zero plot? Bode plot can be used in paper for stability analysis?
I think the remarks are relevant. Pointing out Nichols chart (by Itzhak) was really nice. Let me add a few remarks which could turn out to be important. I mention them from many years experience in class room... I know these are recurrent doubts.
1) Bode diagrams are one way of graphically representing the frequency response of a LTI (linear time-invariant) system, which is by definition, the Fourier Transform of the impulse response of the system;
2) Although Matlab will provide a Bode Plot for an unstable system, such a plot should not be interpreted as a frequency response, because an unstable system does not respond sinusoidally to a sinusoidal input. Mathematically, the impulse response of an unstable system is not an absolutely integrable signal and the corresponding Fourier Transform does not converge.
3) Out of technicalities and into stability... Supose a system with frequency response G(jw), if it has a frequency response then it is stable by definition;
4) Now what seems to be implied in your question is how to use a Bode Diagram of G(jw) to establish the stability of G(jw)/1+G(jw), which is the frequency response of the closed-loop system. Practically all the answers given were provided assuming this (which is the most natural interpretation).
5) Making a long story short: if the system is open-loop unstable, then Bode Diagrams are not the best way of addressing stability either of the open or of the closed-loop. If the loop transfer function is open-loop stable, then, yes, you will find the answer to the stability of the closed-loop system by measuring the gain and or phase-margins.
6) This is valid for both, continuous- and discrete-time systems, although we cannot use the concepts of asymptotes (straight line approximations) to plot Bode Diagrams for discrete-time systems.
Regards.
Luis
Question
I am interested in the motivated stability analysis of magnetized rotating spherical nonuniform inhomogeneous dust molecular clouds on the Jeansean scales of space-time. The components of the Lorentz and Coriolis forces are the complicating factors. Can anyone extend any help in terms of suggestion for simplification, or literature for execution?
While doing some research incident to producing a scientific biography of Galileo [cf. citation in my profile], I came across a Coriolis-type phenomenon that Galileo investigated, that is, the apparent deflection of an object moving along a longitude line or, to a lesser extent, moving in a direction that has a north-south component, which can be expected to deflect to the right in the northern hemisphere and to the left in the southern. This Coriolis deflection can be attributed in part to Earth’s eastward rotation -- a phenomenon that Galileo strove mightily to demonstrate with many arguments -- and I would expect this deflection to apply to your " dust molecular clouds".
To use one of Galileo’s favorite examples, that of a projected cannonball, if fired to the north from the equator it would land somewhat east of the meridian on which it was fired. Due to the tangential velocity of a point on Earth varying with latitude the cannonball can be expected to travel eastward faster at the Equator than does its more northerly target or landing point. And mutatis mutandis for a cannonball fired to the South.
Here I have only “scratched the surface” of the issue; i.e., there is much more to be said about Coriolis force. For the sake of brevity I will resist the temptation to further discuss it here but instead refer you to a scholarly article that has the most comprehensive history and development of this topic of which I am presently aware [Anders O. Persson, “The Coriolis Effect: Four centuries of conflict between common sense and mathematics”, History of Meteorology 2, 2005”]. I hope this helps.
Question
Dear All
I have multi-environment data and would like to do stability analysis in R? I found two R function and respective packages like Agricolae and plant breeding? I tried both and got different Anova table. what is the basis to select between this two package? Is there any other package and R codes available for stability analysis?
My data has 12 locations, 8 genotypes and 3 replications in each location.
Thanks
Anshuman
Dear Mr. Tiwari. Yes, I runned AMMI1 analyses.However, in my opinion, GGE is superior than AMMI1, because GGE isolate environmental (E) effects (Did not use aditive effect of E). Thus, the model of GGE consider only the main effect of Genotype plus Genotype Environemnt Interaction (G + GE). If you see articles that used AMMI1, you can see that the E effect correspond for the big part of the sum of square, i.e., you make inference about E and not about genotypes.Thus, I recommend use GGE analyses. In R plataform, you can performed mean vs. instability and ideal genotypes analyses to evaluate genotypes and representativeness vs. discriminating power to evaluate test location. As cited before, for each analyses, different scaling methods can change the inferences of analyses.
Article 1: "GGE Biplot vs. AMMI Analysis of Genotype-by-Environment Data"
Article 2: "Statistical Analysis of Yield Trials by AMMI and GGE: Further Considerations".
Question
In the reference ''On stability analysis of active disturbance rejection control for nonlinear time-varying plants with unknow dynamics '',
why when A is Hurwitz, there exists a finite time T1 > 0 such that
Eq.(19) exists?
Even when A is hurwitz, there exists positive elements in the A matrix. How to explain this?
\$e^{w_0 A t}\$ is bounded by and exponential decreasing function in the case of A hurwitz. so after some time \$T1\$will be less than any constant , in particular 1/(w_0^{n+1}).
Question
Hi, All
I am doing the project about slope stability analysis considering climate change. I need the project data and historical data of singapore. Where can i get these data?
Hi Tang ,
You might be interested in the "ready to use" CMIP5 data for climate change impact modeling we provide.
There is also daily min/max temperature and solar radiation (and soon wind and relative humidity).
Please note that those are not high resolution data (scale is 50km x 50km). Our "City data" are useful for quick exploration of past and future climate conditions at a specific location. There are intended to inform about possible trends and support qualitative assessments.
The methods and process we use to generate this data from the original CMIP5 data are described in this report: https://www.researchgate.net/publication/322888233_Bias_Adjusting_Climate_Model_Projections
All the best
Question
Hello everyone,
I am trying to simulate the breaching process of earth embankments during overtopping by performing a stability analysis in PLAXIS 2D. I was wondering if it is possible to remove the blocks that have collapsed and continue on the modified mesh.
I think it is the simplest way.
Initially you have to do a little attention, but once you understand the system it is very simple. In these years I have done many tests of stability using this system.
Question
While ascertaining stability of genotypes, how to estimate the % variation due to environments, genotypes and their interaction. Can it be calculated manually (in MS Excel)?
ANOVA partitions total variability represented by total sum of squares SSt into four components: (1) sum of squares due to genotype SSg (2) sum of squares due to environment SSenv (3) sum of squares due the genotypexenvironment interaction SSgxe (4) sum of squares due to error SSe. The ratio of each sum of squares to SSt is the proportion each variable contributes to the total variability respectively. Note that the proportions add up to 1.
Question
1. What are the significance of singular value decomposition?
2. What do we understand about a matrix from singular value decomposition.?
3. What is the specialty of SVD for stability analysis of a system?
Please explain me with detail but easy explanation. I will be really grateful
When a matrix is multiplied with a vector, it does do things 1. rotation 2. scaling. you can easily visualize it by multiplying a two dimensional vector with a 2x2 matrix (y=Ax) and see that y is a rotated and scaled version of x. When the dimension increases then you can't visualize it. SVD kind of helps u in finding out the the basis for the axis of rotation (U and V*) and singular value matrix (S) says the importance of that basis. So from SVD of matrix A, u can say that how it will rotate or scale the x.
The straight forward application is PCA or dimension reduction. If u can find that in certain axis there is no change then u can simply ignore that because they are not important. You can link the SVD to eigen value decomposition where eigen value decomposition is only for square matrix where as the SVD is valid for all the matrices.
This is my intuition to SVD and hope it helps.
BW
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My research area is low frequence oscillation damping in multimachine system.
Yes, I used the original PST by Chow in stability analysis of muli-machine systems. This was during my PhD study in 2003. Later, I decided to use the PSAT as it has a GUI, more capabilities, and more components. Currently, the PST is significantly developed, but I didn't use it yet. I am also thinking to try the POUYA package.
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Need help regarding stability analysis, hovering simulations and trajectory tracking of small scale helicopter.
Also refer prefiltering concept
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I have designed a controller using Integrator backstepping method and that controller is based on Lyapunov Theory. I have a question How I can check stability of resulting controller?
Hi Waheed,
Since you have designed a Lyapunov-based integral backstepping controller for the 4th-order MISO system, what exactly is your difficulty in checking the stability of the control system?
Question
Hello!
I am carrying out the Slope Stability Analysis of a Highway Slope using 2D Limit Equilibrium Analysis in SLIDE (rocscience package). I was wondering if it is necessary to check the model for FOS & critical surface of the analysed slope (highway slope not embankment) for drained & un-drained case. Or if the drained & un-drained case check should be carried out in analysis highway slope.
Your support shall be highly appreciated.
Sumit
The type of analysis depends on the type of soils, on groundwater flows and hydrogeological conditions.
For granular soils (i.e sand or gravel), the slope must be checked only in drained conditions.
For cohesive soils (i.e.clay and silts), there are two possibility. If the soils are dry the slope must be checked only in drained conditions. If the soils are saturated or with groundwater flow the slope must be checked in both undrained and drained conditions.
Question
Why we use of Non-dimensional parameter in stability analysis of a fluid layer?
The idea of dimensionless form is intimately associated with the concept of similarity. Two flows having different values of length scales, flow speeds, or fluid properties can apparently be different but still dynamically similar. Therefore, it is standard to non-dimensionalize the equation by scaling each variable by a “characteristic unit”. This scaling process naturally produces certain non-dimensional combination of these units.
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I want analyse the stability of chaotic systems and design a controller for such systems.
A book which deal with more general nonlinearities is the one written by Drainkov and Hellendorn: http://www.springer.com/gp/book/9783540606918.
With all respect, but although LMI approach is very nice, it has some drawbacks. I actually like it but you may wish to see the book I told you about,
Question
We have solved two-dimensional eigenvalue problem for the stability analysis of axisymmetric boundary layer. The spectrum of the eigenvalues shows that the flow is temporally stable for a given eigenmode at particular Reynolds number. The associated eigenvector gives the two-dimensional spatial structure of the disturbance velocity. The 2d structure of the streamwise disturbance velocity disturbances is attached herewith. If the magnitudes of the disturbances increases in the streamwise direction then can we say it is unstable?
which terminology one should use.
1. Spatially unstable
2. convectively unstable ..however, it is local stability concept.
How one can explain this phenomenon in term of global stability analysis.
Pl. Send your email so we can communicate properly.  Thanks for response.
Question
I have been working on MIMO gain scheduling control, but I cant find any references to the stability analysis of SISO or MIMO gain scheduling specially for the desired properties of the controller if its modify.
y(t) = Kp(t) u(t) + int{Ki(t)u(t)}, if the gain is before the integration, and
y(t) = Kp(t) u(t) + Ki(t) int{u(t)}, otherwise.
Hi Luis,
Your question is a fundamental question.
Many systems are using gain scheduling and... they work, and even fly.
However, the guarantee of stability is something else, SISO or MIMO.
Suppose that you know that your system is stable for any gain from Kmin=1 to Kmax =20.
You have been using the gain K1=5 and, at some point in time, you decide that the gain K2=10 is better. So, if you just switch from K1 to K2 and then STAY at K2, you have a simple LTI stable system with the fixed gain K2=10, which, coming from K1=5, may have a transient response, yet otherwise is stable.
Things are different when your policy requires the system to keep switching between K1 and K2, (or to keep going through other various gain values) when you have no guarantee of stability. Your system may happen to remain asymptotically stable, yet may also perform some limit cycle or even just simply diverge, although the gains remain within the so-called “stable domain.”
Yes, this is the shock that people met when they move from constant gains to nonstationary gains.
People here mentioned adaptive control. Because I am coming from the adaptive control field, I had to deal with this problem. A first adaptive rule, called MTI rule, did exactly this: let the gain change within the admissible domain and use an adaptation rule to fit the right gain to the right situation. The algorithm was implemented on a plane, which flew nicely until… it just crashed.
In spite of the known history, at some point in time, I also “almost” had a proof that stability is guaranteed. I wrote “almost” because it was only until I found my own counterexample. I call this my best and happiest mistake ever, because it forced me to learn a lot about stability with nonstationary and nonlinear systems, and such concepts as passivity, etc, which are essential for stability of nonstationary systems, including adaptive control systems. I does not mean that you cannot guarantee stability with nonstationary gains, yet you must first learn to satisfy the prior conditions that can allow you to guarantee it.
You may want to have a look at the paper
I.  Barkana: “Adaptive Control? But it’s so simple! A Tribute to the Efficiency, Simplicity and Beauty of Adaptive Control,” Journal of Intelligent and Robotic Systems, Vol, 83, No. 1, pp-3-34, July 2016 (Published On-Line October 2015) DOI 10.1007/s10846-015-0299-7
It is about adaptive control, yet this only says that, instead of just switching gains, the tracking error is used to compute the appropriate gains such that the error tends to zero. If you cannot get the paper, you can see the report with same name in my list of publications on Research gate.
Regards,
Itzhak
Question
I would like to start understanding this topic from the very basic level and then move on to the advanced level where I will have to deal with using this technique for stability analysis of non-linear systems. Please point me towards some good resources in this field. Is there any online courses that deal with cell-to-cell mapping ?
Hello Biswajit Debnath,
I think the following thesis can help you know the basic level of cell mapping method.
van der Spek JAW.  Cell mapping methods: modifications and extensions. Ph.D. thesis (Technische Universiteit Eindhoven, 1994)
Shan Yin
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I would like to analyse the stability of a closed-loop system in which the controller is built around a Smith predictor. I am interested in particular with the stability analysis with respect to uncertain time-delay in the plant. Thank you.
interesant question, I want to proof stability with nonlinear smith predictor. I think is necessary to use Lyapunov method
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