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  • Mohammad Azizipour asked a question in Toolbox:
    Does MATLAB have a toolbox for solving MINLP?

    Does anyone know about the MINLP in MATLAB? I have a mixed-integer non-linear problem that should be solved by MATLAB. Does MATLAB have a toolbox to solve such problems?

  • Mohamad Hoseiny asked a question in Electricity:
    (Lay Out) in electricity substations What does it mean to be determined based on what?

    Please guidance me out

  • Ramachandran Manickam asked a question in PLA:
    How we improve the glass transition temperature of PLA polymer?

    how we improve the glass transition temperature of PLA polymer?

  • Mohamad Hoseiny asked a question in Electricity:
    What when the electricity substations is GIS?

    Please guidance me out

  • Anthony G Gordon added an answer in Bile:
    Does bile end up in earwax?

    Wax and bile are the only two secretions that taste bitter.  Bearing in mind that cases are known of urine and menstrual blood travelling up through the body and ending up in the external auditory meatus, does bile get excreted there physiologically as part of earwax? 

    Anthony G Gordon · Independent Researcher

    A very striking feature of cases where substances from lower in the body end up in the ear canal is the extreme pain involved.  I do not know much about endometriosis other than it is very painful and mysterious, but I wondered if womb tissue made use of this non-vascular head-to-toe pathway.  So I Googled Endometriosis Otitis Externa.  Not only are these connected, there is actually a Mobile Support Group for those with both conditions!

  • Mahmoud Zouaoui added an answer in Open Innovation:
    Do you know studies of open innovation applied to industry associations?

    I'm doing a thesis on this issue and I have not found many studies about open innovation and its relationship with industry associations. If you want to see my project, you can look at my profile, its name is "The role of industry associations as drivers of strategic management of innovation in industry".

    Mahmoud Zouaoui · University of Manouba, Tunis, Tunisia

    See the article "The Role of Intermediating Institutions in the Diffusion of Electronic Data Interchange (EDI): How Industry Associations Intervened in Denmark, Finland, and Hong Kong", The Information Society: An International Journal
    Volume 17, Issue 3, 2001
    Jan Damsgaard, Kalle Lyytinen

    You can get it, directly, from authors. Look at their profiles on ResearchGate.

  • HUILONG Yu added an answer in Functional Genetics:
    How can I tune fuzzy membership function with genetic algorithm?

    How to chose genetic parameters and how can I code a triangular memberships functions? I am working with Matlab.

    HUILONG Yu · Politecnico di Milano

    Have you solved your problem? I have similar experience to tune membership functions with GA, if you need, you can contact me by email~

  • Interested in novel approaches for training modeling and requirements analysis skills?

    We are presenting a 1 day tutorial at RE’15 conference using an innovative approach for training/learning requirements analysis and modeling skills with feedback-enabled simulation of models. The incorporated feedback links simulation results to their causes in a model design thus making simulation results easily interpretable. As a simulation technique we refer to executing of UML models by means of MDE fast prototyping. The principles of execution and feedback incorporation will be discussed. If interested see the expanded description below.

  • Gary Liu asked a question in Sensors:
    ANSYS Workbench: why am I seeing unrealistically large deformation in my model? And how do I model frictional contact with >0.2 coefficient?

    Hi everyone,

    First of all, I am not a mechanical engineer by training, and am completely new to ANSYS, so I may be getting something really basic really wrong here. My description may be a bit long so I apologize for that in advance and I would appreciate your patience.

    I am trying to replicate the simulation in the following paper for my school project:

    J. R. Lee, S. Y. Chong, C. Y. Yun, D. J. Yoon, A lasing wavelength stabilized simultaneous multipoint acoustic sensing system using pressure-coupled fiber Bragg gratings, Optics and Lasers in Engineering, 49, pp. 110-120, 2011.


    The results shown in the attached image “Paper” are what I am supposed to get.

    I have attached my model in the image “Geometry”, as you can see, I have 6 components here, all having the same length in z-axis (7mm), which then sit on a much larger base plate. In the actual physical model, the silicone is supposed to be a bit thicker than the gap between sensor cover and sensor head, and the sensor cover is pressed down and bonded to the base plate by epoxy (not simulated in the model). So in fact the silicone starts in a compressed state, producing a downward pressure on the sensor head. My model is a simplified version of this actual state, in which the silicone fits nicely in the gap from the beginning, and the compressed state is simulated by applying a downward pressure on the top surface of the silicone layer.

    The core and acrylic make up an optical fiber, which is bonded to the sensor head with epoxy.

    In the ANSYS model, I used frictional contact between epoxy and base plate, and between sensor head and base plate (as is the actual situation); and all other contact regions were set to “bonded”.

    For the analysis, I set the analysis type to “direct” because when I left it as program controlled, it gave me a warning that says an iterative solver was used but a direct solver may enhance performance.

    And the results I got are shown in the attached image “My results” showing normal elastic strain in z axis. I have also attached the ANSYS report for your reference. Please note that the load I applied here was merely a 6 Pa downward pressure on the top surface of the silicone, while the load in the paper was 0.06 MPa (Quote: “the over-dimensioned silicone layer should generate, in theory, a distributed pressure of about 0.06 MPa”). As you can see, the deformation of the silicone was so huge that it came out of the gap and went all the way to the base plate, as if it were liquid (Young’s modulus for the silicone in my model was 0.621 MPa).

    Here are my questions:

    1.    Why is the deformation so large when the applied load was so small? What I find most puzzling is how the deformation can be so dramatic when the calculated strain was so small (10e-7 at max).

    2.    In the paper, the coefficients of static friction at the epoxy-base plate and sensor head-base plate interfaces were 0.23 and 0.61 respectively, when I used those values, the system gave a warning that the coefficients were >0.2, and the mathematical model could not be solved due to “insufficient memory”. I then changed both coefficients to 0.2 in my model and obtained the result shown. Is there a way to carry out the analysis with the large coefficients above?

    I have also attached my model files in the zip file, in case anyone would like to take a look.

    Thank you for reading such a long post and any comment and help would be much appreciated.

    Best regards,


  • Doris Elster added an answer in Science Education:
    How can someone's ability to explain scientific content be measured?

    It is a core competence of teachers to explain scientific content target group related. What are the skills of a good explainer? How can we measure if someone is a good explainer or not? Do you know empirical research about this theme?

    Doris Elster · University of Bremen, Bremen, Germany

    Thank you all for your contributions. I summarize that the following key components make a good explainer: subject (content) knowledge, knowledge about the preconcepts of the target group, empathy for recognizing the laerning processes of the target group, flexibility to change the explaination (target-group-related), communication skills. Something missing?

  • Jimoh Taobat Adekilekun added an answer in Ponds:
    What method can be used to measure the amount of biomass undergoing aeration in an high rate algal pond?

    I have tried the MLSS method, but I didn't seem to be getting a satisfactory result. The concentration keeps flunctuating instead of increasing. Please help me out.

    Jimoh Taobat Adekilekun · Rhodes University

    Thank you very much Eler,  for your response. I am working with a pilot scale HRAP that treats wastewater, I'm trying to measure the amount of biomass in the pond. I think the method m using is not gud enough. i'll try and check the references you gave. Thanks

  • James Varghese added an answer in Space Flight:
    Is there any hope that living matter will be discovered over the Solar System, and does humanity need to continue its search?

    Each human activity should have an achievable aim. Is there today, after 60 years of space flights, any premise for considering that the aim to discover life over the Solar System is achievable? 

    James Varghese · Universiteit Twente

    On a philosophical note, I believe searching for extraterrestrial life is an innate instinct of humans. Long before we set our foot in space, our ancestors carried on the same aspiration. The desire to know the unknown, the fascination for the cosmos and the curiosity to find the faintest signs of life as we peek into the oblivious universe presents an overwhelming excitement. Most of all it gives us a 4 letter word called hope. I like to see it in the same way as seeking immortality!

    On a scientific note, I'm amazed to see the progress we have made with space feats like the CURIOSITY, MOM, ROSETTA missions to name a few. And I'm sure there are more marvellous missions in the pipeline. I also believe collaboration is key rather than competition. The idea of presenting an 'Earth Passport' as an identity proof to the first life form we may ever meet in the future is spellbinding.

  • Bert F. Quin added an answer in Nutrient Uptake:
    What is an effective corn Nitrogen availability test?

    What do you think is the best measure of N availability to corn in a humid temperate climate?

    Bert F. Quin · Group ONE Ltd, Auckland, New Zealand (www.groupone.co.nz)

    Hi Jessica 

    I published a soil incubation test for estimating wheat N requirements back in '79. I think it would work pretty well for corn as well. You can print it off my profile, Authors were Quin, Drewitt and one other. Let me know if you try it. Regards, Bert Quin

  • How can I deal with a randomization issue in Echo State Networks ?

    Dear All 

    I am using Echo State Networks(ESN) as a Q-function in a Reinforcement Learning task. I have managed to achieve high accuracy, 90% in average, on the test phase with particular reservoir topology (spectral radius =0.9, regularization coefficient = 10, #input unit = 2, #output units = 1, #reservoir units = 8, and no leaking rate).

    The system achieved high accuracy in test phase after training for 100 episodes. But when I initialized the networks weights with different random seeds, it's behavior became very unstable and failed to achieve high performance as before. I want to know how can I overcome this randomness issue and have ESN that is robust to the different random initialization of its input and reservoir weight and can generalized well ?

    here how I initialized my network.  Input weights and reservoir weights sampled from Normal Distribution (mean = 0 and std = 1). Input weight matrix is normalized with unified variance and the reservoir weights normalized by division with maximum of absolute Eigen values and multiplied with spectral radius.  

    Thanks In Advance


    Ramin Zohouri · University of Freiburg

    So Far The best Idea I have is to use large number of neurons in reservoir and an empirical approach for setting spectral radius, small enough then it can compensate to the different random seeds in input and reservoir weight initialization.a practical approach for implementing echo state networks. Beside there are some other approaches for training the input and reservoir eights. Then question is What are the general principle for designing ESN? (rather than empirical parameter searching.)

  • Eric Lord added an answer in Special Relativity:
    Is relative simultaneity a misinterpretation of Special Relativity?

    I really need a lot of feedback on this particular issue.

    I think that relative simultaneity is a computational effect of no consequences to real temporal relations. This is based on my analysis of simultaneous trajectories.

    My claim of apparent nature of relative simultaneity is based on the assertion that relative lengths of rigid objects or points moving at a constant relative distance to each other in a stationary system are not conserved (in general ) in the moving system after Lorentz transformation when expressing multiple points trajectories in terms of common time of the moving system.

    More details in the linked document and relevant draft article available from my RG profile

    Eric Lord · Indian Institute of Science

    Dear Jean Claude ~

    Sorry for the delay. I saw your response of 7 days ago only today (for some reason the “intimations” from RG have stopped coming…).

    It seems clear that there is nothing wrong with either the maths or the physics of what either of us have been saying. We have been misunderstanding and confusing each because we have attached different meanings to the symbols A and O. I see it like this:

    A single point in Minkowski spacetime is an “event”. Interpreted physically, an “event” is something that happens at a particular place at a particular time. It doesn’t “move”! In terms of a coordinate system (x, y, z, t) in Minkowski spacetime, it is labelled by a set of four constants.

    I took O to mean the “event” labelled (0, 0, 0, 0) by the observer employing the coordinate system K. That observer has a clock and stays at the same spatial origin (x, y, z) = (0, 0, 0). Hence his worldline is given parametrically by (x, y, z, t) = (0, 0, 0, t). A sequence of “events” − a trajectory x(t)= y(t) = z(t) = 0.

    I think we have been at cross-purposes in that I have been using O to denote the fixed spacetime origin (x, y, z, t) = (0, 0, 0, 0) while you have been taking O to mean the moving 3-space origin (0, 0, 0, t).

    Similarly, I take A to mean the “event” that the observer in K labels (x, y, z, t) = (a1, a2, a3, a4) while the observer in K′ labels it  (x′, y′, z′, t′) = (0, 0, 0, 0).

    Thus, in my description O and A are fixed points in the 4-dimensional spacetime.

    The worldlines of the two moving spatial origins are given in the by (x, y, z, t) = (0, 0, 0, t) and (x′, y′, z′, t′) = (0, 0, 0, t′), respectively. Their relative velocity is v.

    When considering the SO(3, 1) Lorentz transformations, the 4-vector (a1, a2, a3, a4) really has no significance and there is no harm done if we take it to be (0, 0, 0, 0). It belongs to the translational subgroup of the Poincaré group and is unrelated to the vector v whose components are parameters of the SO(3, 1) transformations. The vector v is not a “translation” in the Poincaré group sense.

    The differences in our ways of thinking are differences in notation and nomenclature, not disagreements about the maths or the physics.

  • Luca Malatesta added an answer in Interpolation:
    Which raster spatial interpolation technique is best suitable for rainfall and temperature data interpolation where the weather station is equispaced?

    Among the available spatial interpolation technique, like kriging, IDW, natural neighbor, spline etc which one is best suitable for rainfall and temperature data interpolation. 

    Luca Malatesta · University of Camerino

    Dear Srikanta,

    I suggest you to read this interesting paper, in which your question is thoroughly analysed and discussed:

    Attorre, F., Alfo, M. & De Sanctis, M. (2007) Comparison of interpolation methods for mapping climatic and bioclimatic variables at regional scale. International Journal of Climatology, 27, 1825–1843.

    The authors compare the effectiveness of different methods for interpolating and/or predicting climatic and bioclimatic variables. Universal kriging with external drift obtained the best performances for seventeen variables of the twenty-one analysed, neural network interpolator has proven to be more efficient for three variables and D-IDW for only one.

    You can find the paper at the following link:


    Alternatively, you can directly ask one of the authors to provide you with a copy of the manuscript via ResearchGate.

    I really hope this helps.

    Best regards.


  • Mehdi Kargar asked a question in Transformers:
    Where the use of ynd11 transformer?

    ynd11 transformer

  • May gravito-electromagnetism be an alternative to Einstein's theory of general relativity?

    Gravito-electromagnetism (GEM) describes gravitation starting from the idea (suggested in 1893 by Oliver Heaviside and further developed by Olev Jefimenko) that there is a formal analogy between the gravitational and the electromagnetic phenomena.  This implies that - relative to an inertial reference system O - a gravitational field is characterized, in analogy with an electromagnetic field, by two vectorial quantities: the gravitational field Eg and the gravitational induction Bg.  The spatial mass destribution is the source of Eg  and the motion of the masses relative to O that of Bg

    According to GEM, a gravitational field is just like an electromagnetic field (Maxwell's equations) mathematically described by a set of four partial differential equations, the GEM-equations.   They describe how Eg  and Bg   vary in space due to their sources and how they are intertwined.  The action of a gravitational field on particles is described by a law analogous to Lorentz's force law: the force law of GEM.

    It has been shown that GEM can explain a number of phenomena (precession of planets and binary pulsars, gravity probe B experiment, ...) that are inexplicable in the context of Newton's description of gravitation what makes that GEM can be considered as a possible alternative to GRT.

    In line with the original idea of Heaviside GEM can be seen as an extension and a refinement of the "classical theory of the gravitational field", an extension that - besides the effect of the spatial distribution of the gravitating bodies - takes into account the effect of their motion.  GEM can theoretically be founded and explained by the theory of informatons. (https://www.researchgate.net/publication/268576021_GRAVITO-ELECTROMAGNETISM_EXPLAINED_BY_THE_THEORY_OF_INFORMATONS?ev=prf.pub)

    Let us still mention that GEM has been discussed within the context of general relativity by a number of authors and that it has been shown that  the GEM equations can be derived in the weak field approximation of Einstein's description of gravity.

    Daniele Sasso · Progetto Indipendente ARS

    AKira, it is right that you criticize the Theory of Reference Frames like I criticize modern and postmodern physics, classical and neoclassical physics.

  • I need some examples of fermented medicinal plants, any help?

    Does any one know other examples of medicinal plants need to be fermented or aged for a period before use? such as Casacara Sagrada which need to be aged at least one year in order to use it.

  • Nicola Tartaglia added an answer in Pelvic Floor:
    What is your physiotherapic management of pelvic floor after inter sphincteric resection?

    Very low rectal cancer

    Nicola Tartaglia · Università degli studi di Foggia

    thank you Fernando,

    i'll do it.

  • Mehdi Kargar asked a question in Facebook:
    What is the social networks?

    social network

  • Pakop Sovo added an answer in Typing:
    I have collected 3 sets of dependent variable data from 3 treatments (n=30 for each group). What is the best way to analyse this information?

    n = number of plants

    dependent variable data = fresh weight

    treatments = control, mulch type 1 & mulch type 2

    Pakop Sovo · Pacific Adventist University

    Thank you for that Muayed Fadhil Abbas.

  • How can I solve this pair of partial differential equations: dc/dt=d2c/dx2-dc*/dt-dc/dx; dc*/dt-c+c*=0?

    Initial conditions: both C and C* are zero at t=0;

    Boundary conditions: at x=0, -C0=-C+dc/dx; at x=1; dc/dx=0

    Jun-Wei Wang · University of Science and Technology, Beijing

    According to your description, PDEs dc/dt=d2c/dx2-dc*/dt-dc/dx; dc*/dt-c+c*=0 can be rewritten as 


    For this PDE, we can use the finite difference method to solve it. Please provide a email address to me. I'll send a matlab code to you

  • Tarik Ömer Oğurtani added an answer in Stress:
    Why do brittle materials fail at a stress level below the theoretical cohesive stress of the material?

    fracture mechanics

    Tarik Ömer Oğurtani · Middle East Technical University

    The mechanism of fracture in brittle materials is closely related to the stress concentration  at the tips of surface cracks and /or internal  flaws, where  the local stress   becomes  SigmaLocal  = SigmaAppl  2 SQR (a/ rho).   2a  is the crack length, and  rho  is tip radius of curvature. 

    The stress intensity also  given by  K = Sigma SQR( Pi x a).  İf  KC   is greater than the fracture toughness defined as  KC  =SQR(E GC ) that the failure starts at the crack tip and propagates. 

    Where  E  is the Young modulus,  GC  is the measure of fracture energy, and its value depends on the size of the plastic zone around the crack tip. For brittle materials   GC   is approaches the theoretical surface free energy  Gama, which may be estimated by   Gama   = E  ao /20.  ao  is the lattice parameter.

  • Anand Moorthy asked a question in Printing:
    I want to know how to print temperature in Liggghts. I have tried thermo_style, but it's printing zero value in all steps. How do I proceed ?

    Also, when I use 'Dump' command for saving temperature using custom style, it is showing error that "dump custom does compute values for per atom".

  • Arvind Kumar asked a question in Geobacillus:
    Why pH of medium raising higher from 6-8, 7-8 when cells of Geobacillus sp. grown in Nutrient Broth of pH 6 and 7 ?

    Dear All I am growing Geobacillus sp. cells in nutrient broth of pH 6 and 7 but after overnight incubation the pH of medium become 8 of each tube. but of negative control (medium without cells )remain constant. Can anyone suggest me why this is happening? 

  • Sudha Balagopalan added an answer in Drawing:
    Does the transformer draw any current when its secondary is open ?

    hi,Does the transformer draw any current when its secondary is open ?

    Sudha Balagopalan · Vidya Academy of Science & Technology

    True. The no load current is also called the magnetizing current because of its functional role, though a misnomer. The magnetizing current being purely reactive, lags the applied voltage by 90 degrees. Because this current is alternating both hysteresis and eddy current losses occur resulting in drawing an active current component in addition to that  drawn due to Cu loss due to the resistive part of the primary coil only.

    The transient inrush current at switch on is dependant on the cut-in angle as well.

  • Haneen R. Khreis asked a question in Odds Ratio:
    How can I convert odds ratios calculated for an X increase in air pollution exposure to odds ratios for another air pollution increase interval?


    I am undertaking a meta-analysis of risk estimates between exposure to air pollution and asthma diagnosis in childhood. The studies I collected in my review calculated the risk estimates based on different increase intervals in air pollution exposure and I want to standardize that so as to be able to tell what air pollution interval the pooled estimate relates to.

    For example, in one study an increase of 10.3 µg/m3 nitrogen dioxide was associated with an OR of 1.18 (0.93, 1.50) for asthma diagnosis - I want to find out what OR is associated with a 10.0 µg/m3 nitrogen dioxide instead? Can you please advise on how to do that?

    Many thanks,


  • Is there any numerical solution to solve nonlinear coupled PDEs?

    Is there any numerical solution to solve nonlinear coupled PDEs?

    Vahid Mosallanejad · University of Science and Technology of China

    Hi, Mrs. Mohsen

    Yes, there are quite different methods. I believe COMSOL software make big progresses for solving system of PDE's. you can use module "Mathematic", "Coefficient Form of PDEs". there is a tutorial video about that in internet.  As Mrs. samuli  described, there are other software as well. I like to add MATLAB too. If you want to learn about numerical method I recommend you to focus first on Newton-Raphson method which is involve making Jacobian matrix, because it is very fast. If you are going to write a code( instead od using software) it is better to first select appropriate solution method which is depend on the type of PDE( like, Eigen value PDE or Time dependency, or number of dimension) then try to implement different steps of an individual method.

    good luck

  • Yaser Gohari asked a question in Induction Motor:
    What is the principle of operation of shaded-pole induction motor?

      What is the principle of operation of shaded-pole induction motor?