User login

You are here

Comments

Subscribe to Comments feed
Comments
Updated: 6 hours 30 sec ago

Earlier today, I was giving a

Tue, 2018-08-28 11:38

In reply to Who was PhD advisor of Prager?

Earlier today, I was giving a lecture on frontier research in mechanics to the sophomore at Zhejiang University. During the lecture, I spent several minutes talking about our academic ancestors, from Klein to Gauss and finally to Friedrich Leibniz. Unfortunately, I just realized I mistakenly recognized Friedrich Leibniz as Gottfried Wilhelm Leibniz who 'invented' calculus independently of Newton. Actually, Friedrich Leibniz was the father of Gottfried Wilhelm Leibniz. The lesson I learned is that I need to be very careful otherwise I may identify wrong ancestors.

For a while, I was a little bit concerned about if Wilhelm Schlink really was Prager's advisor since it is hard to find information (and photo) about Wilhelm Schlink online in English. But I recently ran into a Wikipedia page written in German, saying Wilhelm Schlink moved to TU Darmstadt in 1921 and served as a professor of mechanics there until his retirement in 1948/1949. The information is consistent with the fact that Prager obtained his Dr.-Ing. at TU Darmstadt in 1926. I think my puzzle is resolved.

other source of informations

Mon, 2018-08-27 15:55

In reply to YOUR OPINION MATTERS!

other source of informations https://www.kiensueno.com

(spanish language)

e-books of proceedings

Mon, 2018-08-27 08:45

In reply to 9th GRACM Intern. Congress on Computational Mechanics, 4-6 June 2018, Chania, Greece (deadline January 31)

The book of abstracts and the book of full-length papers have been published by the Technical University of Crete Press. Both are available at the repository of the University Library:  http://dias.library.tuc.gr/view/78631 http://dias.library.tuc.gr/view/78634

Self-financed or publicly

Sat, 2018-08-25 22:17

In reply to There is another benefit,

Self-financed or publicly funded?

--Ajit

There is another benefit,

Sat, 2018-08-25 04:29

In reply to Sharing data by theory/computation mechanicians

There is another benefit, besides enabling reproducibility, intrinsic to code sharing in computational mechanics. Essentially, by sharing our codes, we are providing the community with tools that should speed up scientific progress. Based on these two motives (allow people to reproduce my results and, hopefully, help them in their research efforts), I decided some time ago to release the codes employed in all my papers (www.empaneda.com/codes). While this is a time-consuming process (I had to clean the codes and write a documentation), it has proven to be rewarding; I received many e-mails from users around the globe thanking my openness and explaining what they have achieved by using or extending my codes. 

​​​​Emilio Martínez Pañeda​

Re: Disclosing raw data

Fri, 2018-08-24 17:52

In reply to Re: Disclosing raw data

Interesting comments. My thoughts never went in that direction. I agree with you that if you construct something and claim some advantages then Camden's "all the proof of a pudding, is in the eating" might be applicable. And you may not want to reveal the recipe.

The scientist who claims having proved a theory by the outcome of an experiment needs to present the theory, the experimental setup and the direct measurements. Apart from being a proof of a successful theory or an experiment, it will also give credit if others can use the data to find something additional yet not discovered.

Per

Hi Douglas, I agree. Thanks

Fri, 2018-08-24 17:48

In reply to More sharing across the board

Hi Douglas, I agree. Thanks also for pointing out DataVerse and Jupyter Notebooks. I will look into both. This has prompted me to reexamine how I do business and see what I can do on my side. The key issue is your observation that doing it well takes time and effort and there is not much in the way of incentive other than a personal sense of communal service.

Re: Across the board?

Fri, 2018-08-24 15:44

In reply to Sharing data by theory/computation mechanicians

Dear Douglas,

Across. the. board. ? ... What precisely do you mean by that?

Do you---by any chance---mean to say: mixing up the private with the public, as in reference to sheer size of the computational data and purported scholarly. interests. ? [The reference is to what I said here [^]]

[Indian languages]  ``Tch!''

--Ajit

 

 

More sharing across the board

Fri, 2018-08-24 13:00

In reply to Sharing data by theory/computation mechanicians

I would certainly welcome greater transparency across all aspects of mechanics research - experimental data, computational code, and mathematical calculations (e.g. Mathematica notebooks). I think the Jupyter Notebooks (laregly use with Python) are a great step forward on the computational side. For experimental data, what do we do with terabytes of high resolution photographs that are later analyzed with image processing tools (tools that always aren't shared nearly enough). The DataVerse project seems intriguing, but I'm just learning about it now (https://dataverse.org/).

The challenge is always the same - sharing code/data takes time and energy to do well, and there is no strong incentive. I, for one, would gladly welcome a change to this status quo.

Re: Disclosing raw data

Thu, 2018-08-23 23:19

In reply to Discussion of fracture paper #21 - Only 6% of experimentalists want to disclose raw-data

Thanks for highlighting the issue.

The idea that raw-data should be available seems quite fine by me, at least on the face of it, though let me hasten to add that personally, I mostly work only in theory, and for that reason, this is more or less a complete non-issue for me. Further, as a programmer, the closest thing that comes to sharing data in my case is: sharing the raw output of programs---though I would have strong objections if all parts of algorithms themselves also were to be disclosed to be able to publish a paper.

As to the latter, I was thinking of this hypothetical scenario. Suppose I invent a new algorithm for speeding up certain simulations. I want to sell that algorithm to some company. I want to get the best possible value for my effort (which is not necessarily the same as the most possible money in the immediate present). But the market is highly fragmented, and so, I don't want to go through the hassle of contacting every potential customer. So, a good avenue for me is to publish a paper about it. Clearly, here, I can share some data but not all. Especially if the raw data itself can be enough for someone else to figure out at least the kind of algorithm I was using. Data can be a window into the algorithm, which I don't want to open just yet. How does the proposal work out in this case?

The parallel of the programmer's case to that of the ``hard'' experimental research is obvious.

Thus, in some cases, I do anticipate that there could be some IPR-related issues related to the design of the experimental apparatus itself, or of algorithms. Disclosing even just the raw-data could be, in some cases, tantamount to disclosing some other data or ideas that in themselves have some commercial value (present or future), implications for the confidentiality clauses with the clients, and/or patents.

Overall, private organizations pursuing cutting-edge research may have good reasons to pursuing a policy that has both these components: (i) not disclosing the raw data itself, and yet (ii) publishing some of their findings in a summary form, so as to keep the interested public informed about the more distinct stages that their research has reached. The twin policy results, because qua research, it needs to be published (say to gain or retain credibility); qua private data, it anyway cannot a property ``owned'' by ``the public.''

Further, in any case, what is meant by raw-data also needs to be discussed by the research community and clarified. No one would want a worthless explostion in the amount of data. ... One sure way to hide ``real'' information is to cover it under tons of worthless data. You can at least buy some time that way! (To wit: media reports about the Right to Information act in India.)

With all that said, in general, however, I do find the idea that ``grant providing organizations should ensure that experimental data by public funded projects is available to the public'' very appealing. [Emphasis added]. ... Poetic justice! :-)

Best,

--Ajit

 

3 PhD scholarships in Structural Engineering at Melbourne Uni

Mon, 2018-08-13 21:41

In reply to PhD Scholarship in Structural Engineering and Computational Mechanics

Description

Three PhD scholarships are immediately available in the Department of Infrastructure Engineering, The University of Melbourne. The candidates will work on the following topics: (1) high strength concrete-filled steel tubular structures; (2) high strength steel-concrete composite sandwich panels; and (3) structural reliability of steel-concrete composite frames.  

Eligibility criteria

This opportunity is open to both Australian and international students who (1) hold a Bachelor (first class honours) or Master degree in Civil or Structural Engineering with a GPA over 80/100; and (2) meet the English requirements (for internal applicants only) with overall IELTS 6.5 with no band below 6.0 or TOEFL 79. Candidates with experiences in one of the following areas will have advantages:

o   nonlinear analysis of steel and steel-concrete composite structures

o   experimental tests on steel and concrete structures

o   FE simulation using commercial packages such as ABAQUS and LS-DYNA

Stipend

There are three available positions, and each scholarship is valued at $30,000/annum for three years.

Open date

Applications are now open.

Close date

Applications close until the positions have been filled.

How to apply

Please email your cover letter, CV and academic transcript to Dr Tai Thai at tai.thai@unimel.edu.au.

deadline for application postponed to sept.7

Mon, 2018-08-13 04:13

In reply to several phd positions at the Dept Mech Engineering Politecnico di BARI

There is plenty of time still to apply. Please contact me at mciava @ poliba.it for any query.   Most important you are asked to write a small "proposal of research" so please hurry up.

Energies

Sun, 2018-08-12 17:01

In reply to Journal club for August 2018: X-Mechanics – An Endless Frontier

Dear htwang,

In any system and specifically in solids the strain energy is a result of interacting internal forces generating stresses and strains and this energy is then formulated with the displacements. This form of energy has to be calssified in the scales that you have cited. It is also important to notice that if we touch a deformed solid we find it hot : is this strain energy a calorific one resulting from a transformation of energy as it is stated in the conservation theorem of the mechanical energy ? The otherforms of energy are the kinetic and interestingly the convection energy which has an origin a a transformation state. A local energy in solids can be generated from local dislocations or from unsufficiently energy in the overall domain during its development from the source.

  

Sun, 2018-08-12 10:09

In reply to PhD studentships available in mechanical behaviour of materials at Birmingham University (UK)

  

Please find attached more detailed project descriptions as well as contact address. 

Thanks!

Sat, 2018-08-11 20:49

In reply to What are the natures of global and local energy in solids?

Thanks!

In solids, the energy has not a precise definition without given the scale. From my view, if we consider a multiscale system, the energy has a multiscale architecture as well.

Thanks for comment!

Sat, 2018-08-11 20:24

In reply to The interaction between

Thanks for comment!

We are desperate for new actuating and control mechanisms in building a workable and useful robot. But we are left with desperation most of time with the “new” mechanisms. Truly interesting is the intricate relation among various subjects. It is worth mentioning that Bellman equation (named after Richard E. Bellman), a necessary condition for optimality, lays the foundation of reinforcement learning (RL). It was first applied in the 1950s to engineering control theory. A recent demonstration is that AlphaGo Zero vanquishes its predecessors by employing RL. Deep mimic is another example showing the capability to train multiple characters (human, Atlas robot, bipedal dinosaur, dragon) in simulation to imitate a large variety of skills, including locomotion, acrobatics, and martial arts. In mechanics, we call it dynamic programming, a weird name given by Bellman. I did not realize at the first time that the two fields have such a close relation.

Thanks!

Sat, 2018-08-11 20:02

In reply to What is the information between different scales?

Thanks!

In fields of computational mechanics, the information is well defined by the governing equations for each method. A smooth transition across domains modelled by different methods requires accurate interpretation of state variables, which is notoriously known as an artistic and demanding handcraft. For example, ab initio and molecular dynamics methods calculate atomic forces by considering the electron density and the empirical potential, respectively. The information is different at two different scales. Recently, we have proposed an accurate interatomic force field for molecular dynamics (MD) simulation by hybridizing classical and machine learning potentials. A dynamic procedure has been adopted by evaluating the centro-symmetry parameter of evolving microstructures during MD simulations and accordingly modifying the highly distorted regions depicted by ML potentials. Atomic force field calculation in near-perfect or perfect lattices remain sticking to the fast EAM potential, which precisely captures the long range elastic interactions. A handshaking region is introduced in order to enforce the continuity in atomic interactions. The MD simulations using a dynamic multiscale scheme can achieve the ab-initio accuracy without raising considerable computational cost. The foundation of this approach deeply roots in the facts that the ML method has comparable accuracy to ab-initio MD simulations and possesses the same order of computation complexity to the classical MD (O(N)). The proposed multiscale method attains both high accuracy and efficiency simultaneously. In this way, the information is defined by MD method and extended to the other domain. In this example, all calculations are based on the atomic configurations, which is the only required information. To extend to macroscale, we believe that the deep data analysis on the atomic configuration may help as well. But there is no clear answer right now.

One solution is to use the

Sat, 2018-08-11 12:44

In reply to Parallel computing for non-local damage model in abaqus

One solution is to use the ABAQUS URDFIL subroutine to update the common block after each increment. This subroutine is automatically called at the end of any increment in which new information is written to the results file. In the next increment, each processor can access that common block for the converged results in previous increment.  To make sure all processors update and access the same common block, they need to share the same memory, which can be guaranteed by requesting processors from the same computation node if we are running the analysis on clusters. 

The interaction between

Thu, 2018-08-09 12:15

In reply to Journal club for August 2018: X-Mechanics – An Endless Frontier

The interaction between various subjects and mechanics are truelly interesting. Take the  oft robotics and mechanics as the example, the mechanical analysis of large deformation and multifield coupling can  only guide the design of structure and systems, but can also propose new actuating and control mechanisms.

What are the natures of global and local energy in solids?

Wed, 2018-08-08 22:30

In reply to Journal club for August 2018: X-Mechanics – An Endless Frontier

The authors raised an interesting question of the interactions between glocal and local energy in solids. Unlike the fluids where the heritages over which the energy can propagation are clear, say, a large-scale swirl and a small-scale vortice, in solids it seems not so. I wonder what are the natures of global and local energy in solids. Is the global energy associated with a glocal "area" of the system or with a certain level in the system's hierarchy? Thanks.

Pages

More comments

Syndicate

Subscribe to Syndicate