Biomimetic Characteristics of Active Deployable Structures

...and the Award Goes to...

2011-12-20T11:50:00.000+01:00

My research is among the candidates for a prestigious award. Let's cross our fingers and wait!

New Scientific Article by Korkmaz et al: Configuration of Control System for Damage Tolerance of a Tensegrity Bridge

2011-11-17T11:12:00.002+01:00

In a fresh article published by Advanced Engineering Informatics, I and my co-authors are demonstrating how to configure an active control system for a tensegrity bridge. Here is the abstract and the keywords of this study:

Abstract

Tensegrity structures are spatial, discrete, and lightweight structures that are composed of struts in compression and pre-stressed cables. Stability is provided by the self-stress state between elements independently of external actions. Tensegrity structures are attractive due to their potential for deployability, ease of tuning and high precision control. Since tensegrity structures have highly coupled behavior, placement of actuators is a primary concern when designing active control systems. This study investigates the active control performance of cable members of a tensegrity bridge. The actuation efficiencies of cable members are evaluated through a multi-criteria approach. The configuration of the control system is thus identified through outranking candidate active members. A multi-objective damage tolerance strategy is then proposed and optimally directed control solutions are identified using stochastic search. Case studies for several damage scenarios are examined to validate results. The most efficient active cable configuration is compared with that needed for deployment. This study is divided into two phases. After the description of a 16 m-span tensegrity bridge, optimally directed locations of active cables are determined in the first phase. Secondly, a procedure to ensure damage tolerance of the structure is proposed. The multi-objective self-repair procedure provides damage tolerance minimizing both maximum deflections in the structure and stresses in the structural members. Results indicate that the control strategy for deployment is a near-optimal solution for damage tolerance. The proposed methodology is applicable to a range of complex active structures.

Keywords: Structural control; Optimum active control; Control efficiency; Damage tolerance; Pareto optimum; Multi-criteria decision making

Full article can be accessed using the following DOI: http://dx.doi.org/10.1016/j.aei.2011.10.002

A Cool Tool: tensegrity

2011-10-09T11:04:00.000+02:00

Recommended:

A brief introduction to the applications of tensegrity: Beading Crimp Tubes and Monofilament by Phil Earnhardt

My Article Featured on VerticalNews Defense & Aerospace Section

2011-08-01T02:20:00.000+02:00

"Reports on Structural Engineering Findings from Ecole Polytechnique Provide New Insights":

http://defense-and-aerospace.verticalnews.com/articles/5559185.html

Engineering Education in Turkey

2011-04-06T00:38:00.000+02:00

2011 QS University Rankings are now available:

Civil & Structural Engineering Rankings
Chemical Engineering Rankings
Electrical Engineering Rankings
Mechanical, Aeronautical & Manufacturing Rankings
Computer Science & Information Systems Rankings

As expected, MIT tops in all subject rankings. On the other hand, despite all the buzz Turkish universities create in national media, no Turkish university except Istanbul Technical University (ITU) is listed in top-200 list. ITU is ranked

101-150. in Civil & Structural Engineering
101-150. in Chemical Engineering
151-200. in Electrical Engineering
151-200. in Mechanical, Aeronautical & Manufacturing

Although scientific research has become utterly more productive over the past decade in Turkey (please see the relevant statistics here), the gap between the quality of Turkish universities remains wide. Thanks to the booming economy and changing socio-cultural system, many top-notch Turkish researchers prefer to go back to Turkey. This potential has to be harnessed in a systematic way.

It would be too naive to expect ITU and a couple of other decent Turkish universities, such as Bilkent University and Sabanci University, to educate the huge army of good engineers that the quickly growing economy desperately needs. Time and again, concerns are raised on the quality of the vast majority of Turkish engineers, and for good reason. Let's face it - Among the ~170 Turkish universities, only ITU is listed in the engineering subject rankings! Turkey has potential for more, uhm, better science...

New Scientific Article by Korkmaz et al: Determining Control Strategies for Damage Tolerance of an Active Tensegrity Structure

2011-03-31T12:54:00.003+02:00

My new scientific article is published online by Engineering Structures. Some folks have been asking about this study since last year. Here is the abstract of the paper:

Tensegrity structures are spatial, reticulate and lightweight systems composed of struts and cables. Stability is provided by a self-stress state between tensioned and compressed elements. Tensegrities have received interest among scientists and engineers in fields such as architecture, civil and aerospace engineering. Flexibility and ease of tuning make these systems attractive for controllable and adaptive structures. However, tensegrities are often prone to difficulties associated with meeting serviceability criteria and with providing adequate damage tolerance when used as civil engineering structures. This paper extends research on active control of tensegrity structures to study self-repair of a tensegrity pedestrian bridge that is damaged. Self-repair is intended to meet safety and serviceability requirements in case of cable damage in the pedestrian bridge. Intelligent control methodologies that implement stochastic search with active member grouping are proposed. Case studies for several damage scenarios are presented to show the effectiveness of the methodology. Results from simulated damage scenarios show that self-repair can be successfully performed with a minimum number of active members leading to a reduction in control complexity.

Keywords: Tensegrity structures; Active control; Self-repair; Damage tolerance; Stochastic search

Full paper can be accessed using the following DOI: http://dx.doi.org/10.1016/j.engstruct.2011.02.031.

Biomimetics in Distributed Computing

2011-02-04T15:10:00.000+01:00

A "traditional" application field of biomimetics is computer science. Computer scientists have been using biomimetic approaches in subfields such as stochastic search. A new study by Yehuda Afek et al. aims to provide simple and efficient algorithms in the subfield of distributed computing using a technique inspired from the nervous system of the fly. The original paper can be accessed here.

Photo by Valter Jacinto

Coming Up: a 1.6m-Span Tensegrity Bridge

2011-02-02T11:43:00.001+01:00

A 1.6m-span tensegrity bridge model is currently under construction at EPFL. Timber struts and nylon cables are used as compression and tension members in the lab structure, which will be used for damage-tolerance research.

Peer Review vs Twitter Verdict

2011-01-25T11:19:00.004+01:00

An article by Apoorva Mandavilli questions a new trend in academia: peer-review via online social networking sites and blogs. The following two instances are given to illustrate the emerging online peer-review:

Sebastiani, P. et al. Science doi:10.1126/science.1190532 (2010).
Wolfe-Simon, F. et al. Science doi:10.1126/science.1197258 (2010).

In both examples, the papers are ripped apart online. Although disadvantages of the current peer-review system decrease productivity, I do not find the new unruly, unstructured and often anonymous procedure constructive. As Wolfe-Simon mentions, "Any discourse will have to be peer reviewed in the same manner as our paper was, and go through a vetting process so that all discussion is properly moderated". Hard-earned scientific information should not be wasted with chit-chat level "scientific commentary" via Twitter.

Times Higher Education and Reuters Rank EPFL Top in Europe

2010-12-07T15:47:00.003+01:00

Swiss Federal Institute of Technology (EPFL) is ranked first in Top European Universities in Engineering, which is prepared by Times Higher Education and based on the publication and citation performance of universities. Data is provided by Thomson Reuters.More information is available at the following link:

http://www.timeshighereducation.co.uk/story.asp?sectioncode=26&storycode=414302&c=1

Zero-Emmission Walking Vehicle

2010-12-01T12:02:00.000+01:00

Yet another biomimetic legged vehicle: Mondospider. Zero emission!

For more information, please visit the website dedicated to this project: www.mondospider.com.

Biomimetic Robots

2010-11-30T17:57:00.003+01:00

Robotics is an application field of structural control. Here are two videos featuring two biomimetic robots developed by Boston Dynamics:

Leiden Ranking 2010

2010-11-12T11:14:00.000+01:00

Leiden Ranking 2010 is revealed. According to the size-independent, field-normalized average-impact based methodology, the top 5 universities in Europe are listed as follows:

1. Swiss Federal Institute of Technology, Lausanne (EPFL)
2. Swiss Federal Institute of Technology, Zurich (ETHZ)
3. University of Cambridge
4. University of Oxford
5. University of Lausanne (UNIL)

Further information is available here.

Popularity of Civil Engineering (Revisited)

2010-11-05T16:49:00.000+01:00

The video below is part of an effort by The Institution of Civil Engineering (UK) to let people know a little more about the profession of civil engineering:

2010-10-28T11:07:00.001+02:00

Tensegrity mechanisms are used in a number of applications. Yet another tensegrity application is coming up: headphones. Teague 20/20 headphones make use of flexibility and self-stress mechanisms of tensegrity to make it automatically form to the user's head. The designer of the headphones is Dana Krieger.

More information is available at http://www.teague.com.

Popularity of Civil Engineering

2010-10-26T15:31:00.008+02:00

CNN Money (a service of CNN, Fortune and Money) published the "best jobs in America". Among the 100 job titles listed, civil engineering is ranked only 6th (2nd among engineering disciplines). It is highlighted that huge construction projects and aging infrastructures are bolstering demand for civil engineers. Median salary of civil engineers is noted to be $80,000.

Why does the society not appreciate the profession of civil engineering (more generally, engineering) as much as some other 5 professions?

I believe that there is a serious image problem of (civil) engineers in the society. (Civil) engineers trained at universities of low quality give an impression that being a civil engineer is an easily achievable goal. On the other hand, almost all engineering students of good universities could be accepted to the departments of which graduates are more appreciated. Let's have a closer look at them:

1. Software architect

2. Physician assistant

3. Management consultant

4. Physical therapist

5. Environmental engineer

6. Civil engineer

A significant amount of software architects and management consultants are engineers. What about the two healthcare professions? All (civil) engineers that are trained at decent universities had the choice to go to any department. They did not choose to do it due to several personal and some common reasons (e.g. in some countries, only engineers have had the image of "smart people").

The image of being #6 is ascribed to civil engineers for a reason. We need to eradicate this bad image that bad "engineers" have given to the society.

Galloping Gertie

2010-10-20T14:34:00.004+02:00

Engineering education matters... Here is one of the numerous disasters resulting from engineering mistakes:

The Tacoma Narrows Bridge (Gallopin' Gertie (!)) was opened in 1940 in Washington. There was apparently a problem in the design of the bridge:

Once the bridge was built and it was recognized that "there was a problem", the engineers attempted to control the bridge passively using hydraulic dampers. However, the effectiveness of the hydraulic dampers was nullified since the seals of the units were damaged when the bridge was sand-blasted before being painted.

Aeroelastic fluttering induced the failure of the suspender cables 5 days after Prof Frederick Burt Farquharson (University of Washington), proposed to give a more aerodynamic shape to the transverse section of the deck by adding fairings or deflector vanes along the deck, attached to the girder fascia, the bridge collapsed due to 64 kmh wind.

It took 10 years to build a new bridge due to material and labor shortages as a result of the involvement of the United States in World War II. The new replacement bridge was opened to traffic on October 14, 1950. Here is a panorama of the bridge, which is still in service:

Source: Wikipedia, Youtube

European Group for Intelligent Computing in Engineering Workshop 2011

2010-09-03T15:05:00.000+02:00

Yet another meeting to present results of intelligent computing research: European Group for Intelligent Computing in Engineering (EG-ICE) Workshop 2011. More information about the program, deadlines and the committees of the workshop can be found under the following link:

http://www.utwente.nl/ctw/eg-ice/People/

2011 ASCE International Workshop on Computing in Civil Engineering

2010-08-12T11:46:00.002+02:00

Click image to enlarge

International Workshop on Computing in Civil Engineering will take place in Miami next year. It could be a good opportunity to present results on the role of informatics in adaptive structures.

An Interdisciplinary Research Field: Active Tensegrity Structures

2010-08-09T12:09:00.008+02:00

Research into “active tensegrity structures” has been carried out since decades by aeronautical engineers, civil engineers and mechanical engineers. Keeping in the mind the productive nature of interdisciplinary work, I believe that the interaction between research groups composed of researchers from merely one of these categories should be enhanced. Ultimately, an ideal research group working on active structures would comprise civil engineers, aeronautical engineers, mechanical engineers and computer scientists. Also, there is a gap between the research conducted in Europe and the research conducted in the US. Most of the researchers in the field of “active tensegrity structures” are civil engineers in Europe (e.g. Ian F.C. Smith, René Motro, Simon Guest*). On the other hand, almost all of the scholars working on active control of tensegrity structures (e.g. Robert E. Skelton, Cornel Sultan, Hillary Bart-Smith) are from aeronautical or mechanical engineering field. Also, other aspects of tensegrity structures are studied by medical doctors (e.g. Donald Ingber). Collaboration among these groups is very important in the context of transatlantic research cooperation, as well. Therefore, it is worth to step up efforts toward such collaboration.

*Simon Guest is not a “civil engineer” but an “engineer” since University of Cambridge does not award any other engineering title.

When Scientists Sin

2010-07-17T15:39:00.000+02:00

After The Fraud Epidemic (page 20), yet another article on fraud, deception and lies in scientific research: When Scientists Sin, by Michael Shermer.

Smart Structures for Undergrads?

2010-07-14T15:42:00.003+02:00

The concept of "smart structures" has been implemented in aeronautical engineering for a long time. However, most of the civil engineering students are hardly aware of this terminology. In most higher education institutions, subjects such as adaptive structures, active structures and smart structures are considered to be "luxurious".

At Lehigh University Department of Civil and Environmental Engineering , Dr Yunfeng Zhang offered a "Smart Structural Systems" course to undergrad and grad students during the Spring 2006 semester. Here is how it went!

Smart Structure at Swiss Federal Institute of Technology, Lausanne

"Uniform Material Law: Extension to High-Strength Steels" by Sinan Korkmaz

2010-05-08T15:15:00.002+02:00

My new book is published: Uniform Material Law: Extension to High-Strength Steels. The book presents a refined methodology to predict fatigue life of high-strength steels. It is intended to be a useful reference for mechanical and structural engineers as well as researchers of related disciplines.

Tensegrity Wiki: The Encyclopedia of Tensegrity

2010-04-10T15:07:00.002+02:00

There is an online gathering point for people working on tensegrity:

http://tensegrity.wikispaces.com/

Highly recommended!

World’s Largest Retractable Aluminum Dome

2010-03-25T16:28:00.005+01:00

Openaire, a Canadian company is currently building the largest retractable aluminum dome in Donetsk, Ukraine. Aluminum is not a commonly used material in civil engineering. However, its certain characteristics such as corrosion resistance could be advantageous in some harsh environments. Below is the press release explaining the project:

Donetsk, Ukraine will soon boast the largest aluminum-domed indoor waterpark in the world. Scheduled to open in the fall of 2011, the Royal Marine Aquapark dome is the creation of Oakville-based OpenAire, which specializes in totally unique structures that incorporate retractable roofing systems. OpenAire has created retractable roofing enclosures for water parks, hotels, community centers and other commercial applications.

“At 26m / 86’ high and 85m / 278’ in diameter, it’s the largest free-standing aluminum dome structure in the world,” says OpenAire president Mark Albertine, “And the unique retractable design makes it the first park of its kind. There is simply nothing else like it.”

The waterpark had initially been planned as a steel/polycarbonate structure with a fixed dome. “Things were already in the planning stages when we were brought on board,” says Albertine. “When the developers heard about OpenAire, they loved the idea of a retractable roof. To them, it opened the park up to a whole new world of possibility.”

There are great benefits to OpenAire’s approach of using aluminum for water parks. Unlike steel, aluminum doesn’t corrode, doesn’t need to be painted, withstands chlorine, and requires zero maintenance. In addition, the retractable roof offers flexible, year-round enjoyment. People don’t want to be inside on a beautiful day; opening the roof instantly transforms it into an outdoor facility, giving users the best of both worlds. Plus, opening it up to outside air helps reduce

dehumidification costs for water facilities.

“It will be a gorgeous, light-filled space that takes advantage of the outdoors whenever possible,” says Deborah Baker, OpenAire COO. “Families will love being able to get a break from the cold in winter – and feel the sun on their faces in the warmer months.”

The Royal Marine is a joint venture between the City of Donetsk and private sector investors. The Royal Marine is OpenAire’s second Ukrainian project. The company previously built a retractable skylight for the Terminal Water Park in Kiev-area Brovary Park, the country’s first major indoor water park. In the Donetsk water park, OpenAire’s role has been more significant, with the company providing the entire design and manufacture of the retractable structure.

A computer animation of the Royal Marine Aquapark is available here. For further information, please visit the website of the company at www.openaire.com.

Tensegrity Bridge in Washington

2010-01-26T16:19:00.001+01:00

Wilkinson Eyre Architects proposed a tensegrity for the National Building Museum in Washington. According to the architectural firm, "The bridge is to be constructed from a network of glass tubes acting as compressive elements and joined together by cables in a ‘tensegrity’ structure. The underlying geometry is based on a series of tetrahedral cells, replicated numerous times to accumulate a visual mass capable of asserting itself within the extraordinary scale of the museum’s courts while remaining essentially light."

Increased Creativity in Research

2010-01-12T16:07:00.016+01:00

I have come across Craig Loehle's paper called "A Guide to Increased Creativity in Research--Inspiration or Perspiration?", which could be very useful for the purpose of increasing research creativity. I believe that it can impact researchers' short- and long-term research ambitions. It can be accessed here .

Religion-Biomimetics

2010-01-11T10:41:00.000+01:00

I am thinking about links between (any kind of) religions and biomimetics. Nature-worship may have influenced design processes. For instance, Gaia philosophy is based on that living organisms on a planet will affect the nature of their environment in order to make the environment more suitable for life. Buckminster Fuller has been credited as the first to incorporate scientific ideas into a Gaia theory, which he did with his Dymaxion map (Fuller map) (see the photos above) of the Earth.

Any ideas?

Source: Wikipedia, www.bfi.org

World's First Bionic Finger

2009-12-21T10:47:00.000+01:00

A West Lothian-based company, Touch Bionics, announced the commercial launch of ProDigits. ProDigits is claimed to be the first powered bionic finger for people with missing digits (see the videos below). Detailed information is available here.

Biomimetic Civil Structures

2009-12-09T14:18:00.000+01:00

A way of creating biomimetic civil structures is integration of methodologies that allow civil structures to adapt to the alterations in their environments by using self-diagnosis and self-repair techniques. Ian F.C. Smith brings together active control and biomimetics in "Control Enhancements of a Biomimetic Structure", which is published in June, 2009. Full paper can be accessed for free under the following link:

http://www.itcon.org/data/works/att/2009_17.content.00372.pdf

* Figure by Ernesto Bueno (Pear Biomimetics Project)

Floating Structures

2009-11-18T15:48:00.000+01:00

The interview with Prof. Ian F.C. Smith, which was published in Reflex (science and technology magazine of EPFL) in September 2008, can be accessed at the 73th page of the pdf file under the following link:

http://www.reflexmagazine.ch/pdf/Reflex_n5_EN.pdf

Golden Boy's Heartbeat

2009-11-06T11:34:00.000+01:00

Structural health monitoring (SHM) is an integral part of active structures. According to Daniel Barageas from the French National Aerospace Research Establishment (ONERA):

“SHM aims to give, at every moment during the life of a structure, a diagnosis of the state of the constituent materials, of the different parts, and of the full assembly of these parts constituting the structure as a hole. Thanks to the time-dimension of monitoring, which makes it possible to consider full history database of the structure, and with the help of usage monitoring, it can also provide a prognosis (evolution of damage, residual life, etc.)”.

SHM is used at a variety of structures. Aircrafts and bridges are two of the typical structures at which SHM is used commonly. On the other hand, there are also some “uncommon” fields of SHM usage. In Monitoba, Canada, an SHM system is installed inside a statue: the “Eternal Youth (Golden Boy)”. According to Dr. Mufti, the SHM system for the Golden Boy comprises four types of gauges: accelerometers, electric resistance strain gauges, fiber optic strain gauges, and thermocouples. The internal stress, vibration, and inclination of the structure can be monitored and its response to loading can be examined by using these sensors. At the central control site, located at ISIS Canada SHM Lab in Winnipeg, an application program on the data server is continuously running to subscribe the data from the remote site. The new data are transferred and analyzed every 5s. Currently, around 1GB of data per day on the Golden Boy is reported. A software program uses statistical analysis to sort through and interpret the data. If data patterns remain basically the same, the software does not store the data. Data are stored when the patterns change significantly, and researchers are notified if something completely new happens.

Source: The Monitor

Academic Ranking of World Universities 2009

2009-10-29T17:13:00.001+01:00

Academic Ranking of World Universities (ARWU) in Engineering/Technology and Computer Sciences - 2009 has been revealed. As can be estimated, Massachusetts Institute of Technology (MIT) is the best in the world and Swiss Federal Institute of Technology (EPFL) is the best in Europe. Further information is available on the official website of ARWU:

http://www.arwu.org/ARWUFIELD2009ENG.jsp

Clustered Actuation

2009-10-19T17:05:00.000+02:00

According to K.W. Moored and H. Bart-Smith:

"Clustered actuation exploits the existence of cable elements in a tensegrity structure by allowing cables to be run over frictionless pulleys or through frictionless loops at the nodes".

Clustering of active cables has its strengths and weaknesses. If the active cables are clustered, the damage in one cable leads to greater displacements since all cables in the same cluster go slack. On the other hand, the disadvantages of embedded actuation such as added mass and cost, increased control complexity and energy consumption mean that grouping of active cables is preferable.

I am currently working on self-repair of a tensegrity bridge by means of clustered actuation. This is a promising subject, which has the potential to provide more efficient structures.

Reference: K.W. Moored and H. Bart-Smith, "Investigation of clustered actuation in tensegrity structures", 2009

Is The Kurilpa Bridge Safe?

2009-10-13T12:54:00.000+02:00

There is a controversy between politicians on safety of the Kurilpa Bridge:

http://www.abc.net.au/news/stories/2009/06/17/2600744.htm

Some people even deemed the project scandal:

http://www.news.com.au/couriermail/story/0,27574,25652724-3102,00.html

However, these discussions are not to be taken seriously since they are based on speculations of non-engineers.

Largest Tensegrity Bridge in The World

2009-10-13T11:42:00.000+02:00

Tensegrity "Kurilpa Bridge" was opened on October, 4. The solar-powered Kurilpa Bridge provides an environmentally-friendly and enjoyable walking and cycling pathway to the city from South Brisbane. The structure is 425m long and more than 1050 people were employed on the project. It is expected that 36500 people will cross Kurilpa Bridge each week. Here are some videos of the bridge in function:

The Robot Scientist Adam

2009-10-09T18:04:00.000+02:00

The Computational Biology research group at Aberystwyth University developed a "Robot Scientist": Adam. According to King et al, "Robot scientists are a natural development of the trend toward ever-greater computer involvement in science. They are physically implemented laboratory automotion systems that apply techniques from AI to automatically execute cycles of scientific experimentation." Adam is claimed to be fully automate microbiological experiments. Detailed information can be obtained via the following link:

http://www.aber.ac.uk/en/cs/research/cb/projects/robotscientist/

THE-QS World University Rankings-2009

2009-10-09T10:08:00.000+02:00

The latest THE-QS university rankings have been revealed:

http://www.topuniversities.com/university-rankings/world-university-rankings/2009/results

Here is a link to the engineering/technology rankings:

http://www.topuniversities.com/university-rankings/world-university-rankings/2009/subject-rankings/technology

Artificially Intelligent Structures

2009-09-19T16:54:00.000+02:00

According to Patrick H. Winston:

“The engineering goal of artificial intelligence is to solve real-world problems using artificial intelligence as an armamentarium of ideas about representing knowledge, using knowledge, and assembling systems."

and

"The scientific goal of artificial intelligence is to determine which ideas about representing knowledge, using knowledge, and assembling systems explain various sorts of intelligence.”

Interest in artificial intelligence has been great since mankind envisaged robots. On the other hand, artificial intelligence methods are generally not associated with structural engineering applications. However, intelligent control methodologies such as self-diagnosis, self-repair and learning could be integrated into structural systems to provide innovative solutions that can also be applied to a range of other systems. We, EPFL Applied Computing and Mechanics Laboratory researchers, are going for a deployable tensegrity bridge that is able to take self-repairing actions thanks to an integrated active control and reasoning system. We believe that this research will be an important cornerstone toward the ultimate aim of intelligent structures.

2 Post-Doctoral Positions Available at Applied Computing and Mechanics Laboratory, EPFL

2009-09-11T11:52:00.000+02:00

The Applied Computing and Mechanics Laboratory at Swiss Federal Institute of Technology, Lausanne (EPFL), Switzerland is looking for two structural/construction engineers with a recent PhD to work on research at the interface of structural engineering and engineering informatics. Current research topics include:

deployable structures, bio-mimetic structures, model-based structural identification and data interpretation for continuously monitored structures.

The positions involve collaborative supervision of doctoral candidates, independent research and some teaching responsibilities. The working language is English or French. Excellent working conditions, travel possibilities as well as generous salaries and benefits are available. While the initial contract is for one year, this can be extended to a maximum total of four years. EPFL is consistently ranked in the top forty of the World's engineering universities. Lausanne is situated at the edge of the Alps on Lake Geneva in the center of Western Europe and benefits from one of the highest qualities of life. Wide ranges of cultural and sporting opportunities are within easy reach.

Please send your CV and a cover-letter indicating your motivation along with the month you would be available to the head of the institute: Ian[dot]Smith[at]epfl.ch

Search Methods and Poor Kangaroos

2009-08-28T17:12:00.000+02:00

I have come across "kangaroo analogy" at Prof. T.J. McCarthy's (University of Wollongong, Australia) presentation, of which subject was “Soft Computing in Structural Optimization” . After a short talk with him about it and then some googling, I have found out that the kangaroo analogy was first proposed at a posting of the usenet newsgroup comp.ai.neural-nets by Warren Sarle in 1993. Afterward, it was cited by Prof. Michalewicz in publications. The analogy is akin to “x for dummies” texts and is great for people who already know the basics of the problem of "search", and would like to get more familiar with stochastic search algorithms. The original text is as follows:

Newsgroups: comp.ai.neural-nets

From: saswss@hotellng.unx.sas.com (Warren Sarle)

Subject: Re: Kangaroos [long]

Message-ID: CE0xty.B9K@unx.sas.com

Date: Mon, 27 Sep 1993 17:56:21 GMT

Organization: SAS Institute Inc.

Keywords: Kangaroos

Training a network is a form of numerical optimization, which can be likened to a kangaroo searching for the top of Mt. Everest. Everest is the global optimum, but the top of any other really high mountain such as K2 would be nearly as good. We're talking about maximization now, while neural networks are usually discussed in terms of minimization, but if you multiply everything by -1 it works out the same.

Initial weights are usually chosen randomly, which means that the kangaroo may start out anywhere in Asia. If you know something about the scales of the inputs, you may be able to get the kangaroo to start near the Himalayas. However, if you make a really stupid choice of distributions for the random initial weights, or if you have really bad luck, the kangaroo may start in South America.

With Newton-type (2nd order) algorithms, the Himalayas are covered with a dense fog, and the kangaroo can only see a little way around his location. Judging from the local terrain, the kangaroo make a guess about where the top of the mountain is, and tries to jump all the way there. In a stabilized Newton algorithm, the kangaroo has an altimeter, and if the jump takes him to a lower point, he backs up to where he was and takes a shorter jump. If the algorithm isn't stabilized, the kangaroo may mistakenly jump to Shanghai and get served for dinner in a Chinese restaurant.

In steepest ascent with line search, the fog is _very_ dense, and the kangaroo can only tell which direction leads up. The kangaroo hops in this direction until the terrain starts going down again, then chooses another direction.

Using an ODE (ordinary differential equation) solver, the kangaroo crawls on all fours to the top of the nearest mountain.

In standard backprop or stochastic approximation, the kangaroo is blind and has to feel around on the ground to make a guess about which way is up. He may be fooled by rough terrain unless you use batch training. If the kangaroo ever gets near the peak, he may jump back
and forth across the peak without ever landing on the peak. If you use a decaying step size, the kangaroo gets tired and makes smaller and smaller hops, so if he ever gets near the peak he has a better chance of actually landing on it before the Himalayas erode away. In backprop with momentum, the kangaroo has poor traction and can't make sharp turns.

I have been unable to devise a kangaroo analogy for cascade correlation.
Any ideas, Scott?

Notice that in all the methods discussed so far, the kangaroo can hope at best to find the top of a mountain close to where he starts. There's no guarantee that this mountain will be Everest, or even a very high mountain. Various methods are used to try to find the actual global
optimum.

In simulated annealing, the kangaroo is drunk and hops around randomly for a long time. However, he gradually sobers up and tends to hop up hill.

In genetic algorithms, there are lots of kangaroos that are parachuted into the Himalayas (if the pilot didn't get lost) at random places. These kangaroos do not know that they are supposed to be looking for the top of Mt. Everest. However, every few years, you shoot the kangaroos at low altitudes and hope the ones that are left will be fruitful and multiply.

A New Deployable Satellite Reflector

2009-08-25T15:26:00.000+02:00

NASA's Jet Propulsion Laboratory (JPL) will use a deployable satellite reflector for the purpose of mapping soil moisture and the freezing and thawing cycles globally with unprecedented accuracy, resolution and coverage. The deployable reflector will be produced by Northrop Grumman Corporation. It will be used on JPL's Soil Moisture Active/Passive (SMAP) mission targeted for launch in 2014. This mission is planned to use a combined radiometer and high-resolution radar in order to make direct measurements of soil moisture and freeze/thaw state to give support to understanding of regional and global water cycles, ecosystem productivity, and the processes that link water, energy and carbon cycles.

Source: www.wateronline.com

Remembering to Forget

2009-08-19T12:37:00.000+02:00

The utility problem arises when the cost of search for relevant knowledge outweighs the benefit of applying this knowledge. In case-based reasoning (CBR) systems, the impact utility problem is greatly dependant on the size and growth of the case base. Larger case bases lead to more expensive retrieval stages. In order to solve this problem, the CBR system must forget some past cases. At this point, the crucial question is: "Which cases must be forgotten to obtain a more efficient system?". Smyth seeks answer to this essential question in "Remembering To Forget, A Competence-Preserving Case Deletion Policy for Case-Based Reasoning Systems", presented in 1995 at International Joint Conferences on Artificial Intelligence (IJCAI). This paper could be very helpful to people who would like to design efficient CBR systems.

Source: B. Smyth, M.T. Keane, "Remembering To Forget, A Competence-Preserving Case Deletion Policy for Case-Based Reasoning Systems", 1995

Biotensegrity Interest Group (BIG)

2009-08-17T10:21:00.000+02:00

Biotensegrity Interest Group (BIG) is an interdisciplinary group comprising members from a number of countries and disciplines from artists to clinicians, researchers, engineers and computer programers. The first "meeting of minds" event is going to take place on 4 September 2009, in St. Malo, France. It is too late to register for this year's event but anyone interested in joining the group for the coming annual events can contact me for the contact information of the person in charge.

Functional or Aesthetic Biomimetics?

2009-08-13T11:29:00.000+02:00

Field of bio-inspired artificial devices is growing. When the number of examples gets larger, need for categorization arises. Christopher Harris, a professor of neuroscience at Plymouth University calls attention to the distinction between functional biomimetics and aesthetic biomimetics. According to him, the biology has to be understood when functional biomimetics is the primary concern. On the other hand, when the details of the problem that is being solved by nature is not known, nature is being copied aesthetically and for its own sake. For instance, mimicking a structural system that exists in biological cells, human shoulder, elbow and toe joints, cat flexor and extensor tendons as well as in the molecular structure of spider webs is classified under functional biomimetics: Tensegrity systems are mimicked by engineers because of their numerous functional advantages, such as ease of tuning, deployability, being lightweight and thus, being efficient. Then again, Kenneth Snelson's "Free Ride Home" is a fruit of aesthetic biomimicry. Having this distinction in mind could facilitate communication among researchers and practitioners working on biomimetics, which are from a number of different fields.

Reference: Christopher M Harris, "Biomimetics of human movement: functional or aesthetic?", Bioinspiration & Biomimetics, 2009

University and Department Rankings

2009-08-12T09:53:00.001+02:00

Engineering education is so important that it should not be left to people who are not from engineering field. On the other hand, engineering faculty members are too busy to be involved in the decisive processes such as university and department choice process of high school graduates. Thus, students look for something else during this vital personal choice. For instance, in Germany, students generally prefer to study at universities that are close to their home city. Taking into account the homogeneous quality of German universities in comparison with other countries, this choice could be acceptable to some extent. What about the other countries that have some huge gaps between the quality levels of the universities, such as Turkey? In Turkey, students make their “once-a-lifetime choice” considering almost only the minimum National Student Selection Exam score requirements of the departments. That is, the students in Turkey pick their university and department relying on only choice behavior of other students. What if Adam Smith’s invisible hand does not exist in this field? At this point, need for statistical analysis arises. Despite all the objections, which argue that the institutions that prepare the rankings favor the universities that are in the same country with them, worldwide university rankings made by independent organizations should be the major reference rather than word of mouth. The ranking forum of Swiss universities systematically compiles the major analyses worldwide:

http://www.universityrankings.ch/en/results/results_main_rankings

This issue, I believe, should be of interest for high school graduates, university students as well as faculty members. Otherwise, wrong motivations would lead to lower efficiency not only in the academia but also in the industry.

Tensegrity Structure for Offshore Use

2009-08-10T14:35:00.000+02:00

Tensegrity structures have certain strengths that can be vital in especially harsh environments. For instance, aerospace industry benefits from the easily deployable nature of tensegrity structures. Now, aquaculture and fish farming industry is getting to know tensegrity concept. Flexible and reliable net cage structures are very important in aquaculture and fish farming industry. However, such structures can hardly be established with conventional structural systems. A research team at Norwegian University of Science and Technology (NTNU) applied tensegrity phenomenon to offshore structure design in order to obtain more flexible solutions in 2006.

As it is described in the patent of this innovative approach:

"The present invention relates to a design concept for flexible offshore structures. An extraordinary freedom to maintain control of shape, motion and vibration can be achieved by designing the system as a tensegrity structure (TS) and by introducing appropriate actuation, sensing and control. The invention also relates to interconnected units of flexible offshore structures."

The inventor team consist of the following researchers:

Professor, Asgeir Sørensen, NTNU
• PhD, Anders Sunde Wroldsen , NTNU
• PhD, Anne Marthine Rustad, NTNU
• PhD, Tristan Perez, NTNU
• Senior scientist, Pål Lader, Sintef
• Research scientist, Arne Fredheim, Sintef
• Research fellow, Vegar Johansen, Sintef
• Research scientist, Mats Augdal Heide, Sintef

Robofish to Rediscover Swimming

2009-08-08T11:24:00.000+02:00

Mimicking creatures does not only let humankind benefit from miracles of trial and error optimization that is carried out through natural selection, but also urges it to learn more about the nature of species. Dr. William Megill's team is working on a robotic fish on a €1.8M-project at University of Bath. The FILOSE (Robotic FIsh LOcomotion and SEnsing) project is financed by the European Union 7th Framework Program. According to Dr. Megill:

"This project is interesting on two levels. Firstly we want to understand more about how the fish manages to react to changes in current, and secondly we want to create a robot that mimics this artificially."

The scientists hope to have results by 2012.

Source: www.bath.ac.uk

A Bridge That Can Generate Energy

2009-08-07T14:44:00.000+02:00

Tensegrity structures are more effective when they are equipped with an active control system. The active control system comprises mainly sensors, processors and actuators. In order to maintain the active control system in service, a power supply is needed.

Since human-beings are now well aware of energy saving concept, researchers from various fields work on new energy saving procedures. One of these research projects is currently going on in New Jersey. The $14-million project is run by Mistras Group, Inc, and partially funded by the National Institute of Standards and Technology's Technology Innovation Program (TIP). It is aimed to develop a working system within the next five years.

According to Dan Inman, Ph.D. , a professor at Virgina Tech, the envisioned system will tap both wind- and traffic- induced vibrations for its power supply.

Source: Civil Engineering, The Magazine of the American Society of Civil Engineers, April 2009

Deployable Video Screen for the U2 360° Tour

2009-08-06T13:27:00.000+02:00

New York-based design firm, Hoberman Associates, Inc., designed centerpiece for the U2 360º tour – the Expanding Video Screen – that debuted on June 30, 2009 during the band’s opening night in Barcelona, Spain. It is constructed of stainless steel and aircraft aluminum and the display is made of 888 LED screens. Its height expands from 7 m to 22 m when fully deployed.

This design is based on Hoberman sphere and his patented “Iris Structure”. Hoberman is aware that foldable, retractable or shape-shifting objects have functional benefits such as portability, instantaneous opening, and intelligent responsiveness to the built environment.

Such innovative design projects have the potential to introduce deployable structures into daily life of people and bridge the gap between research on deployable structures and real life.

Robot Cars Racing

2009-08-05T15:56:00.000+02:00

Darpa Urban Challenge program is promoting the progress of unmanned ground vehicles. The ultimate target is providing safely, reliably, and robustly self-driving vehicles in traffic.

Kurilpa Bridge Ready Soon

2009-08-05T15:24:00.000+02:00

Kurilpa Bridge is an application of tensegrity concept in South Brisbane. According to the officials, the pedestrian and bicycle bridge is going to be ready for Queensland's 150th year anniversary celebrations in September 2009.

Quality of Engineering Education Matters

2009-08-04T23:46:00.000+02:00

Well, it is a little bit off the topic but this video demonstrates the importance of engineering education:

What is this blog for?

2009-08-04T22:55:00.000+02:00

I've decided to share the new challenges and their resolutions during my research into "Biomimetic Characteristics of an Active Deployable Structure", as well as news from all over the world related to my research topic on this blog. The posts will generally include news on the following subjects:
-Biomimetics
-Active Structures
-Deployable Structures
-Tensegrity Structures
-Artificial Intelligence

Besides, there will be some posts related to engineering education.