I know that few people use Dymola's commercial library thermal power, but I ask a detailed question with a try attitude. If anyone understands and answers, thank you very much.
Question: how to set the steam side heat transfer coefficient of condenser assembly (divided into three condensation sections) in thermal power to ensure that it will meet different application environments as much as possible. I know this is an empirical value, but I still want to find some basis.
Finally, I just contacted this community (but it doesn't mean I didn't retrieve relevant questions), so I don't ask standardized questions. I hope to get understanding. Thank you.
Related
Using a neural network (LSTM) I'm making an objective features prediction (I have multiple features). Good accuracy is observed during operation. But can I show the effect of any feature on the target feature?
For example, I am predicting a user purchase on a site and want to estimate the impact of a discount on a purchase. That is, to show that such and such a discount will or will not be such a purchase. How to do this using an existing neural network for prediction?
Neural Networks are black box models, they do not provide explanation for their decisions. Answer to such a question is essentially a whole research area.
There are indeed techniques to get insights like that for a already trained model.
You can start with
Partial Dependence Plots (will show you how a change in your feature's value will effect the target variable). A great explanation can be found here: https://www.kaggle.com/dansbecker/partial-dependence-plots
Permutation Importance (will show you how important the feature is for the model to make its prediction). A great explanation can be found here: https://www.kaggle.com/dansbecker/permutation-importance
I need to simulate a fully functional AS/RS in warehousing. Moreover, I am a complete beginner in this field. Can some please let me know if I could get readymade simulation file? Or if not, please let me know how to learn to do it.
I have checked out the Anylogic website and it's tutorials (They are too lengthy).
fortunately for you, i have developed an AS/RS example that is a ready-made downloadable model for you, available at https://cloud.anylogic.com/model/1f5c7d1f-8782-40ac-957d-d3ba97bf6bf0?mode=SETTINGS
In general, when you want a model example, the first thing you should do is check the anylogic cloud, and if you are lucky the model is downloadable. Unfortunately, most people don't share
It really depends on what type of ASRS you are modeling (shuttle versus unit load) and level of detail you need. Do you need specific slotting and inventory tracking, or simplier black box delays with the assumption inventory is always available? The level of detail you need depends on questions you are asking, and should be addressed prior to starting development. If results from the model are critical and urgent, and you need anything more than simple black box delays, you should consider outsourcing to an experienced professional until you can get your AnyLogic skills up to speed.
How do you do reconstruction by threshold decomposition in Matlab? Is there a function for it?
Can you provide some more details of the steps in such a procedure? Some of us are not well versed in DSP theory. I did find a link from a book in Google books here.
If this is exactly what you want it does not seem difficult to code it up. On the other hand if you want something reliable and optimized for speed maybe on of the DSP toolkit users knows a way.
I will be entering my third year of university in my next academic year, once I've finished my placement year as a web developer, and I would like to hear some opinions on the two modules in the Title.
I'm interested in both, however I want to pick one that will be relevant to my career and that I can apply to systems I develop.
I'm doing an Internet Computing degree, it covers web development, networking, database work and programming. Though I have had myself set on becoming a web developer I'm not so sure about that any more so am trying not to limit myself to that area of development.
I know HCI would help me as a web developer, but do you think it's worth it? Do you think Neural Network knowledge could help me realistically in a system I write in the future?
Thanks.
EDIT:
I thought it would be useful to follow-up with what I decided to do and how it's worked out.
I picked Artificial Neural Networks over HCI, and I've really enjoyed it. Having a peek into cognitive science and machine learning has ignited my interest for the subject area, and I will be hoping to take on a postgraduate project a few years from now when I can afford it.
I have got a job which I am starting after my final exams (which are in a few days) and I was indeed asked if I had done a module in HCI or similar. It didn't seem to matter, as it isn't a front-end developer position!
I would recommend taking the module if you have it as an option, as well as any module consisting of biological computation, it will open up more doors should you want to go onto postgraduate research in the future.
The worthiness depends on three factors:
How familiar are you with the topic already?
How good is the course/class you want to take?
What are your interested in more?
Especially for HCI, there is a broad range of "common sense" information you would also easily obtain from reading a good book or a wider range of articles about it also published on the internet. On the other hand, there indeed exist many deeper insights mostly obtained by Psychology studies. If the course is done right, you can indeed learn a lot about the topic and the real considerations to use for developing an interface.
For Neural Networks, one has to say that this is a typical hype topic. It would be mainly interesting in what application domain the course wants to deal with neural networks. You can be quite sure that you won't program or use any neural networks for web development. On the other hand, if the course is done right, this could be a good opportunity for you to broaden your knowledge. Especially, deepening your understanding about the theory of computer science. This highly depends on how the course is laid out, though.
HCI is a topic which helps your career as a web developer, but only if you feel incompetent in that topic (then it is a must) or it is done very well. Neural Networks is a topic which has more potential of being really interesting hardcore computer science stuff, where you indeed learn a better understanding about something. If you are interested in NN, you should not pass the opportunity to get an education which is not narrowly concentrated on the domain of web development -- and, after all, perhaps find more interest in other stuff (it is always good to know other directions you would perhaps like to go into for the future).
Neural networks sound cool until you read the fine print:
In modern software implementations of
artificial neural networks the
approach inspired by biology has more
or less been abandoned for a more
practical approach based on statistics
and signal processing.
This is something that has mystified me for years. Here you have an amazingly complex and powerful control system (real-world biological neural networks), and an academic discipline that appears to be about modeling these systems in software but that has in reality abandoned that activity.
If you're doing web development, your time is probably better spent in the HCI course.
Go with what interests you the most. The HCI stuff will be much easier to pick up later as needed, you'll likely never get another chance to learn about neural networks!
For prospective employers (at least the good ones!) you need to show a passion and excitement about what you do. I'd sooner hire someone who can enthusiastically talk about neural networks than someone who has an extra credit in HCI.
Unless you want to do the research end of the world, ie, get a Masters/PhD, go HCI.
I studied Neural Computation at University when I studied AI. I now run my own company. The number of times since I studied that I have used my NN skills equals zero. I'm glad I did it, as it was quite fascinating, but I would have found HCI much more useful from the position I'm at now. I think that you'd pick up a lot more insight from an HCI course relevant to the software industry, but if you think you experience should be more on the esoteric/almost arty side of development, go for NN.
Which sounds like more fun? Or, equivalently, which will you work harder at? Pick that one.
Did two courses in NN and some other AI-courses - its fun to poke round with that stuff and I actually managed to implement the stuff in some of the things I've done like face-recognition, and it's useful in some other areas to if you wanna plot your lab data etc. I have never used the NN:s in my web development career though I am sure it could be used for something however what it all really boils down to is to find a client or employee willing pay for it when you can just take the straight path. So I would rather read book about it if I wasn't that hardcore about it.
Fundamental Neural Networks doesn't take to much knowledge in math, and was what I used in my first course.
as a programmer to be you need the knowledge of neural network. if parallel processing is the way to go in hardware then future programmers must be knowledgable in neural network. don't forget that NN works better with noise or imprecise data but other systems may not. Note that most data we use for analysis are sample data which is a fraction of the whole and you could imagine if some in the sample are way off. so you need knowledge of NN if you want to last in computer programming field.
I would like to make a list of remarkable robot simulation environments including advantages and disadvantages of them. Some examples I know of are Webots and Player/Stage.
ROS will visualize your robot and any data you've recorded from it.
Packages to check out would rviz and nav_view
This made me remember the breve project.
breve is a free, open-source software package which makes it easy to build 3D simulations of multi-agent systems and artificial life.
There is also a wikipage listing Robotics simulators
Microsoft Robotics Studio/Microsoft Robotics Developer Studio 2008
Also read this article on MSDN Magazine
It all depends on what you want to do with the simulation.
I do legged robot simulation, I am coming from a perspective that is different than mobile robotics, but...
If you are interested in dynamics, then the one of the oldest but most difficult to use is sd/fast. The company that originally made it was acquired by a large cad outfit.
You might try heading to : http://www.sdfast.com/
It will cost you a bit of money, but I trust the accuracy of the simulation. There is no contact or collision model, so you have to roll you own. I have used it to simulate bipeds, swimming fish, etc.. There is also no visualization. So, it is for the hardcore programmer. However, it is well respected among us old folk.
OpenDynamics engine is used by people http://www.ode.org/ for "easier" simulation. It comes with an integrator and a primitive visualization package. There are python binding (Hurray for python!).
The build in friction model.. is ... well not very well documented. And did not make sense. Also, the simulations can suddenly "fly apart" for no apparent reason. The simulations may or may not be accurate.
Now, MapleSoft (in beautiful Waterloo Canada) has come out with maplesim. It will set you back a bit of money but here is what I like about it:
It goes beyond just robotics. You can virtually anything. I am sure you can simulate the suspension system on a car, gears, engines... I think it even interfaces with electrical circuit simulation. So, if you are building a high performance product, than MapleSim is a strong contender. Goto www.maplesoft.com and search for it.
They are pretty nice about giving you an eval copy for 30 days.
Of course, you can go home brew. You can solve the Lagrange-Euler equations of motion for most simple robots using a symbolic computation program like maple or mathematica.
EDIT: Have not be able to elegantly do certain derivatives in Maple. I have to resort to a hack.
However, be aware of speed issue.
Finally for more biologically motivated work, you might want to look at opensim (not to be confused with OpenSimulator).
EDIT: OpenSim shares a team member with SD/Fast.
There a lots of other specialized simulators. But, beware.
In sum here are the evaluation criteria for a simulator for robot oriented work:
(1) What kind of collision model do you have ? If it is a very stiff elastic collision, you may have problem in numerical stability during collisions
(2) Visualization- Can you add different terrains, etc..
(3) Handy graphical building tools so you don't have to code then see-what-you-get.
Handling complex system (say a full scale humanoid) is hard to think about in your head.
(4) What is the complexity of the underlying simulation algorithm. If it is O(N) then that is great. But it could be O(N^4) as would be the case for a straight Lagrange-Euler derivation... then your system just will not scale no matter how fast your machine.
(5) How accurate is it and do you care?
(6) Does it help you integrate sensors. For mobile robots you need to have a "robot-eyes view"
(7) If it does visualization, can it you do things like automatically follow the object as it is moving or do you have to chase it around?
Hope that helps!
It's not as impressive looking as Webots, but RobotBasic is free, easy to learn, and useful for prototyping simple robot movement algorithms. You can also program a BasicStamp from the IDE.
I've been programming against SimSpark. It's the open-source simulation engine behind the RoboCup 3D Simulated Soccer League.
It's extensible for different simulations. You can plug in your own sensors, actuators and models using C++, Ruby and/or RSG (Ruby Scene Graph) files.
ABB has a quite a solution called RobotStudio for simulating their huge industrial robots. I don't think it's free and I don't guess you'll get much fun out of it but it's quite impressive. Here's a page about it
I have been working with Carmen http://carmen.sourceforge.net/ and find it useful.
One of the disadvantages with Carmen is the documentation with all respect I think the webpage is a bit outdated and insufficient. So I like to hear from other people with experience in working with Carmen, or student reports/projects dealing with Carmen.
You can find a great list with simulation environments http://www.intorobotics.com/robotics-simulation-softwares-with-3d-modeling-and-programming-support/
MRDS is one of the best and it's free. Also LabView is good to be used in robotcs
National Instruments' LabView is a graphical programming environment for developing measurement, test, and control systems.
It could be used for 3D control simulation with SolidWorks.
MRDS is free and is one of the best simulation environment for robotics. Workspace also can be used, and please check this link if you want a complete list with robotics simulation software
Trik Studio has a nice and clear 2D model simulator and also visual and textual programming programming environments for them. They also soon will support 3D modeling tools based on Morse simulator. Also it is free and opensource and has multi-language interface.