第 5章

本 COE プログラムへの期待と助言

本COEプログラムへの期待と助言

本拠点に対しては様々な機会を通じて外部の有識者から率直なご批判とご助言をいただいている．本章ではその中でも特に海外の研究者からいただいたレポートを紹介する．平成 17年度は以下のレポートをいただいた．

• IIASA–Technische Universitat Munchen–Kyoto University: The Second Joint InternationalSeminar on Applied Analysis and Synthesis of Complex Systems参加者のレポート

– Report from Dr. Andrew D. Gilbert [University of Exeter: 英国]

• 招聘外国人研究者のレポートReport 1 招聘者: 木田重雄 (機械理工学専攻教授,複雑流体現象の解明とそのモデリン

ググループ)研究者: Professor John Steinhoff [University of Tennessee Space Institute: 米

国]内容: 研究に対するコメント．

Report 2 招聘者: 永田雅人 (航空宇宙工学専攻教授,複雑流体現象の解明とそのモデリンググループ)研究者: Professor Patrick Huerre [Ecole Polytechnique: フランス]

Professor Alessandro Bottaro [University of Genova: イタリア]Professor Friedrich Busse [Unversitat Bayreuth: ドイツ]

内容: 研究に対するコメント．

Report 3 招聘者: 松久寛 (機械理工学専攻教授,複雑系の制御・設計論グループ)研究者: Professor Nguyen Dong Anho [Vietnamese Academy of Science and

Technology: ベトナム]内容: 研究に対するコメント．

Report 4: 招聘者: 青木一生 (機械理工学専攻教授,複雑流体現象の解明とそのモデリンググループ)研究者: Professor Luc Mieussens [University of Toulouse 3: フランス]

Professor Giovanni Russo [University of Catania: イタリア]Professor Tai-Ping Liu [Stanford University:米国]

内容: 博士課程学生 2名 (吉田広顕，Tor Laneryd)の研究に対する評価．未収録．

なお，21世紀ＣＯＥプログラム「動的機能機械システムの数理モデルと設計論」第 3回シンポジウム（平成 17年 4月 23日開催）における評価・諮問委員を交えた討論会の記録については平成 16年度年次活動報告書で，中間評価の結果については日本学術振興会のホームページ (http://www.jsps.go.jp/j-21coe/index.html)でそれぞれ公開されているので参照されたい．

IIASA – Technische Universität

München – Kyoto University

The Second Joint International

Seminar on Applied Analysis and

Synthesis of Complex Systems

21st Century COE Program for Research and Educationon Complex Mechanical Systems, Kyoto University.

IIASA – TUM – Kyoto University:The Second Joint International Seminar on

Applied Analysis and Synthesis of Complex Systems,30th July – 1st July, 2005, Munchen, Germany.

Report from Dr. Andrew D. Gilbert.

This 2-day meeting covered 3 areas:

(1) Robotics/Control Theory/Teleoperation,

(2) Fluid Mechanics,

(3) Solid Mechanics/Fabrication,

with a number of talks in each area. The scientific level of the meeting was very high,as was the level of presentation of the research. I was particularly pleased that someof the German research students/postdoctoral research fellows (i.e., without permanentpositions) gave presentations, of an excellent standard.

The meeting was highly interdisciplinary, allowing scientists from different fields to interactand discuss problems, in an informal workshop atmosphere. As an outsider, not previouslyinvolved in the COE program, I found the meeting very stimulating, and enjoyed the TUMrobotics/telepresence laboratory tour. The meeting was very well organised, with goodtiming, social events, and well thought-out program.

In terms of the mission and scope of the COE program, the meeting worked well in fulfillingthese objectives, i.e., bringing together high-level scientists to exchange ideas/promoterecent research. Possible scope for future enhancements:

(a) It may make sense to develop projects that combine fundamental mathematics/physicswith engineering applications. An example would be the generation of gold nanoparticles(presentation of Prof. Tabata) which could bring in expertise of those in fluid mechanics.

(b) It may be worth bringing in experts in optimisation methods to the next meeting, asmany of the issues faced in robotics and mechanics (e.g., presentation of Prof. Korvink)involve optimisation problems, for which there are a wide variety of methods, old and new.

1

(c) I think it is always valuable to encourage younger researchers, including postgraduatesto travel and present their work. I hope that the organisers will pursue all opportunitiesfor interchange of such personnel between the various institutes, and for them to attendscientific meetings such as this one.

Finally I would like to thank the organisers for inviting me to a very valuable meeting.

12th July 2005.

Dr. Andrew D. Gilbert,Department of Mathematical Sciences,

School of Engineering, Computer Science and Mathematics,University of Exeter,

Exeter EX4 4QE, U.K.

2

The 21st Century COE Program for Research and Education on

Complex Functional Mechanical Systems, Kyoto University

IIASA – Technische Universität München – Kyoto University

The Second Joint International Seminar on Applied Analysis and

Synthesis of Complex Systems

June 30-July 1, 2005.

Technische Universität München München, Germany.

Kyoto University Graduate School of Engineering

Departments of Mechanical Engineering, Precision Engineering, Engineering Physics & Mechanics and Aeronautics & Astronautics

Graduate School of Informatics Dept. of Applied Analysis and Complex Dynamical Systems

International Innovation Center

Preface

The 21st Century COE (Center of Excellence) Program is an initiative by the Japanese Ministry of Education, Culture, Science and Technology (MEXT) to support universities establishing discipline-specific international centers for education and research, and to enhance the universities to be the world’s apex of excellence with international competitiveness in the specific research areas. The program of “Research and Education on Complex Functional Mechanical Systems” was successfully selected to be awarded the fund for carrying out new research and education as Centers of Excellence in the field of mechanical engineering in 2003 (five-year project), and is expected to lead Japanese research and education, and endeavor to be the top in the world.

The program covers general backgrounds in diverse fields as well as a more in-depth grasp of specific branches such as complex system modelling and analysis of the problems including; nonlinear dynamics, micro-mesoscopic physics, turbulent transport phenomena, atmosphere-ocean systems, robots, human-system interactions, and behaviours of nano-composites and biomaterials. Fundamentals of those complex functional mechanical systems are macroscopic phenomena of complex systems consisting of microscopic elements, mostly via nonlinear, large-scale interactions, which typically present collective behaviour such as self-organization, pattern formation, etc. Such phenomena can be observed or created in every aspect of modern technologies. Especially, we are focusing upon; turbulent transport phenomena in climate modelling, dynamical and chaotic behaviours in control systems and human-machine systems, and behaviours of mechanical materials with complex structures.

Kyoto University and IIASA (International Institute of Applied System Analysis) has exchanged Consortia Agreement in 2003 to collaborate to explore this new engineering field through joint academic activities by mechanical engineers and system engineers. This annual seminar has been regularly held to introduce the outline of the COE program of Kyoto University to worldwide researchers and to deepen the shared understandings on novel complex system modelling and analysis, and the first seminar was held in June 28-29 at IIASA, 2004.

In exploring the venue for the second seminar, Prof. Martin Buss, who is a professor at Technische Universität München and is one of the advisers and contributors to our COE program, has kindly offered us to host the second seminar in 2005 at Technische Universität München in collaboration with IIASA and Kyoto University.

In this seminar, we will invite the distinguished researchers in Europe as keynote speakers, and the new developments of the COE will be introduced by the project leader as well as by the core active members. Also the emerging novel technologies ongoing at TUM will be presented. All research staffs of Institute of Automatic Control Engineering of TUM and IIASA research staff are cordially invited to attend this seminar.

IIASA – Technische Universität München – Kyoto University The Second Joint International Seminar on Applied Analysis and Synthesis of Complex Systems. June 30-July 1, 2005. Technische Universität München, München, Germany.

Seminar Organizers

Seminar Program

IIASA – Technische Universität München – Kyoto University The Second Joint International Seminar on Applied Analysis and Synthesis of Complex

Systems

The 21st Century COE Program for Research and Education on Complex Functional Mechanical Systems, Kyoto University

June 30-July 1, 2005.

Technische Universität München, München, Germany.

Building N5 Ground Floor Seminar Room 0507 Technische Universität München

29 June, 2005.

19:00 – 21:00 Welcome Reception at Loewenbraeukeller

30 June, 2005. SESSION 1: OPENING SESSION

9:00 – 9:10 Opening Address I Prof. Martin Buss (Honorary Adviser of the COE Technische Universität München, Germany)

9:10 – 9:20 Opening Address II Prof. Gunnar Johannsen (Honorary Adviser of the COE, Universityof Kassel, Germany)

9:20 – 9:30 Opening Address III Dr. Marek Makowski (IIASA, Austria)

9:30 – 10:00 An Overview of the COE Program, Kazuo Tsuchiya, COE Leader (Kyoto University, Jp.)

SESSION 2: Complex System Control and Design I 10:00 – 10:20 Overview of Control and Design of Complex Systems Group,

Tetsuo Sawaragi (Kyoto University, Jp.)

10:20 – 11:00 "Teleoperation and Haptic Virtual Reality" -Human-Machine Interaction in Real and Virtual Environment- Assoc. Prof. Yasuyoshi Yokokoji (Kyoto University, Jp.)

Coffee Break SESSION 3: Complex System Control and Design II 11:15 – 12:15 "Closing loops: Unified View from Control to Information Science"

Prof. Dirk Söffker (University Duisburg-Essen, Ge.)

12:15 – 13:30 Lunch SESSION 3: Complex Fluid Mechanics I 13:30 – 13:50 Overview of Complex Fluid Mechanics Group,

Satoru Komori (Kyoto University, Jp.)

13:50 – 14:30 "Unstable Periodic Motion: A New Research Tool of Turbulence" Prof. Shigeo Kida (Kyoto University, Jp.)

14:30 – 15:15 "Aspects of Scalar Mixing in Coherent Vortices" Prof. Dr. Andrew D. Gilbert (University of Exeter, UK)

15:15 – 15:50 Coffee Break SESSION 4: Complex Fluid Mechanics II 15:50 – 16:30 "Anomalous Fluid-Dynamic Limits in Kinetic Theory of Gases"

Prof. Kazuo Aoki (Kyoto University, Jp.)

16:30 – 17:15 "From Kinetic Theory to Hydrodynamics" Prof. François Golse (Université Paris 7, France)

18:00 Social event

1 July, 2005.

SESSION 4: Emerging Complex System Control Technologies 9:00 – 9:30 "Invariance Control and State Constraints"

Dr. Jan Wolff and Prof. Martin Buss (LSR, TU München, Ge.)

9:30 – 10:00 "Torque Controlled Robots - From Space to Surgery" Dr.Alin Albu-Schaeffer and Prof.Gerd Hirzinger (DLR/Institute of Robotics and Mechatronics, Ge.)

10:00 – 10:40 "Vision-Guided Humanoid Robot Walking: Methodological Aspects - Experimental Results" Prof. Guenther Schmidt (LSR, TU München, Ge.)

10:40 – 11:00 Coffee break

SESSION 5: Special Session on "Telepresence and Teleaction from the Munich Center-Of-Excellence"

11:00 – 11:30 "A Human-Factors Study on Telepresence Systems" Dr. Barbara Deml (LSR, TU München, Ge.)

11:30 – 11:50 "A Psychophysical Study of A Telemedicine Scenario" Mrs. Franziska Freyberger and Prof. Berthold Faerber (Universität der Bundeswehr München, Ge.)

11:50 – 12:10 "A High Performance Multi-Focal Camera Head for Humanoid Robots" Mr. Kolja Kuehnlenz and Prof. Martin Buss (LSR, TU München, Ge.)LSR, TU München

12:10 – 13:15 Lunch SESSION 6: Materials with Complex Structures I 13:15 – 13:35 Overview of Complex Material Group,

Prof. Takayuki Kitamura (Kyoto University, Jp.)

13:35 – 14:15 "Computational MEMS Process Design and Process Development" Prof. Osamu Tabata (Kyoto University, Jp.)

14:15 – 14:30 Coffee break

SESSION 6: Materials with Complex Structures II 14:30 – 15:15 Prof. Dr. Jan G. Korvink (University of Freiburg, Ge.)

15:15 – 15:55 "Thin Films with Tailored Nano-Morphology and Functions" Associate Prof. Motofumi Suzuki (Kyoto University, Jp.)

15:55 – 16:00 Concluding Remarks, Prof. Kazuo Tsuchiya (Kyoto University, Jp.)

Lab. Tour 16:00 – 17:30 Lab. Tour,

Prof. Martin Buss (TUM)

17:30 – Farewell Party 1 SEMINAR ORGANIZERS Dr. Marek Makowski

Senior research scholar of IIASA Email. marek@iiasa.ac.at

Prof. Dr.-Ing./Univ. Tokio Martin Buss Director of Institute of Automatic Control Engineering, Technische Universität München Email. mb@tum.de

Prof. Tetsuo Sawaragi Sub-Leader of the COE, Dept. of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University Email. sawaragi@me.kyoto-u.ac.jp

2 SEMINAR ORGANIZING COMMITTEE MEMBERS Prof. Kazuo Tsuchiya (Project Leader of the COE, Dept. of Aeronautics &

Astronautics, Kyoto University, Japan) Prof. Satoru Komori (Sub-Leader of the COE, Dept. of Mechanical Engineering

and Science, Kyoto University, Japan)

Prof. Takayuki Kitamura (Sub-Leader of the COE, Dept. of Mechanical Engineering and Science, Kyoto University, Japan)

Prof. Tetsuo Sawaragi (Sub-Leader of the COE, Dept. of Mechanical Engineering and Science, Kyoto University, Japan)

Dr. Marek Makowski (IIASA, Austria) Prof. Gunnar Johannsen (Honorary Adviser of the COE, University of Kassel,

Germany) Prof. Martin Buss (Honorary Adviser of the COE Technische Universität

München, Germany) 3 SEMINAR HOTEL FOR THE PARTICIPANTS

HOTEL EUROPA MUNICH Dachauer Strasse 115, D-80335 Munich, Germany. Tel: +49-(0)89-542420 Fax: +49-(0)89-54242500 Reservation Fax: +49-(0)89-54242267

4 LIST OF THE PARTICIPANTS

1. Prof. Kazuo Tsuchiya (Dept. of Aeronautics & Astronautics, Kyoto University, Japan)

2. Prof. Satoru Komori (Dept. of Mechanical Engineering and Science, Kyoto University, Japan)

3. Prof. Takayuki Kitamura (Dept. of Mechanical Engineering and Science, Kyoto University, Japan)

4. Prof. Tetsuo Sawaragi (Dept. of Mechanical Engineering and Science, Kyoto University, Japan)

5. Dr. Marek Makowski (IIASA, Austria) 6. Prof. Gunnar Johannsen (University of Kassel, Germany) 7. Prof. Martin Buss (Technische Universität München, Germany) 8. Prof. Shigeo Kida (Dept. of Mechanical Engineering and Science, Kyoto

University, Japan) 9. Prof. Kazuo Aoki (Dept. of Mechanical Engineering and Science, Kyoto

University, Japan) 10. Prof. Osamu Tabata (Dept. of Micro Engineering, Kyoto University,

Japan) 11. Associate Prof. Motofumi Suzuki (Dept. of Micro Engineering, Kyoto

University, Japan) 12. Associate Prof. Yasuyoshi Yokokoji (Dept. of Mechanical Engineering

and Science, Kyoto University, Japan) 13. Prof. Dr.-Ing. Dirk Söeffker (Chair of Institute for Mechatronics and

System Dynamics, University Duisburg-Essen)

14. Prof. François Golse (Université Paris 7, France) 15. Prof. Christos Vassilicos (Imperial College, UK) 16. Mr. Jan Wolff (Technische Universität München, Germany)

(wolff@lsr.ei.tum.de) 17. Mr. Kolja Kuehnlenz (Technische Universität München, Germany)

(kuehnlen@lsr.ei.tum.de) 18. Mr. Mathias Bachmayer (Technische Universität München, Germany)

(bachmayer@lsr.ei.tum.de) 19. Dr. Gebhard Geiger (Technische Universität München, Germany)

(g.geiger@wiso.tu-muenchen.de) 20. Dr. Jan Wolff (LSR, TU München, Ge.) 21. Dr. Alin Albu-Schaeffer (DLR/Institute of Robotics and Mechatronics,

Ge.) 22. Prof. Guenther Schmidt (LSR, TU München, Germany) 23. Dr. Barbara Deml (LSR, TU München, Germany) 24. Mrs. Franziska Freyberger (Universität der Bundeswehr München,

Germany) 25. Prof. Dr. Jan G. Korvink (University of Freiburg, Germany) 26. Prof. Dr. Andrew D. Gilbert (University of Exeter, UK)

招聘外国人研究者のレポート

Report 1 Opinions on Talks

Kyoto University Jan. 9, 2006

John Steinhoff

Talk 1 Sizes of Voids in Multiparticle Distributions for Convected Polyethylene Spheres in Turbulent Flow Hiroshi Yoshimoto and Susumu Goto Talk was very well presented. Language was as easily understood as if it had been given by American student. Subject seems to be very significant and work was well done, both in visualization and in deriving pdf’s for void sizes. Since small vortices eject the particles, which are heavier than the fluid, these distributions seem to be a way to quantify the vortices. Hence, these pdf quantities could be a new (I believe), useful measure of turbulence. a. - I think it may be useful to relate the void size distributions to measure of fractal dimensions, which is a very useful way to describe many types of sets of points. b. – I think it would be important to do some simple numerical simulations with a number of distributions of vortices to determine the resulting void distributions. For example, it may be that a set of vortices, each exactly the same size and strength, result in a complex, non-trivial void distribution, merely because of multiple vortex effects – i.e., particles that are ejected from one vortex, are entrained in another, and then ejected a second time, and a third time, etc. Talk 2 Turbulent Flow in Rotating Sphere Nobukazu Ishii Again, talk was well presented, with language as easily understood as if presenter had been an American student.

The basic concept seems to be very important. The fact that a small additional rotation along a different axis is enough to make the flow transition from solid body rotation to turbulence should have far-reaching consequences, particularly for mixing. A set of film clips was shown of images of visible, passive particles being convected with the flow. These demonstrated the presence of turbulence well. However, the clips were very hard to correlate with the particular experiment (orientation of axes of rotation, etc.). It would have been very helpful to the audience to have a diagram showing the particular rotational configuration being shown displayed on the side, next to the film. Another recommendation I have involves the camera view: I understand that a laboratory – fixed view may be important for comparing with computation – particularly concerning boundary conditions, and if only ONE view were allowed, perhaps this would be the preferred one: However, to get a physical feeling for the flow from the films, I think it would be important to display a view fixed with the rotating sphere, in addition. This would be even more valuable if it could be synchronized with the other laboratory-fixed view. An example I have in mind involves viewing the transition from solid body rotation to turbulence as the second rotation is turned on, since the particles would be initially stationary. Talk 3 Stretching and Rotation of Material Lines in Turbulent Flow: Hyperbolic Fixed Points Takeshi Watanabe As in other two talks, the language was as easy to understand as if presented by an American student. I think I understand how difficult this must have been and how much of an accomplishment for a student busy with studies and research. The initial description of the reason for looking at the orientation of sets of lines attached to individual fluid parcels was a little difficult to understand. I think the orientations found represent a new discovery, however, this was not made as clear as it could have been. Also, the relation with any theories should have been mentioned, or, if none exist, this should have been discussed. The possibility of a Galilian invariant theory that is independent of stagnation points would also have been interesting. However, it was clear that a considerable amount of good technical work had been done to obtain the data.

Student: Kazuaki HIWATASHI (D1) Title: Experimental study of rotating plane Couette flow Professor Patrick HUERRE (2/17/’06) Very interesting comparison between theory and experiment confirms many of the theoretical predictions. Elegant experimentdeserve to be published in the peer – reviewed literature. As a possible extension, it could be worthwhile to look at higherthe parameter regime where pure plane Couette flow expeturbulence. References to other studies in pure plane Couette flow: MANNEVILLE et al. at LadHyX, Ecole polytechnique, DAVIAUD et al. Groupe “Instabilities & Turbulence” CEA, Saclay Professor Alessandro BOTTARO (2/21/’06) Very professionally conducted study on the formation of rolls atertiary structures for the case of Couette flow rotating about Coriolis force produces longitudinal rolls that are observed expethreshold is found to agree rather well with theory. At larger Re, of stationary waves are observed, in close agreement with the th1990). The strong point of this study is the conjugation of theorexperimental approaches, conducted in collaboration with the teaat KTH, Stockholm, Sweden. These kinds of interactions/collaboration should be encouraged. Fof view some issues remains to be resolved on the origins of the ( and relatively large Re ). Further (tertiary) stability theory may Professor Friedrich BUSSE (3/2/’06) In this experimental investigation of the onset of longitudinal roflow in rotating plane Couette flow some unusual phenomenwavelength of the longitudinal rolls decreases from bottom to top ofluid is bounded by a rigid bottom plate and by a free surface analogous Taylor-Couette experiments with similar boundary conchange in the wavelength of Taylor vortices has been observed. It the onset of wavy vortices occurs intermittently. It will be ofwhether this behavior persists at higher Reynolds number

Report 2

which validates and al observations which

Reynolds numbers in riences transition to

, France

nd on the creation of a spanwise axis. The rimentally and whose structures in the form eory by Nagata(1988, etical approaches and m of Prof. Alfredsson

rom the physical point instability at small Ω be required.

lls and of wavy vortex a are observed. The f the experiment. The

at the top. But in the ditions no significant

is also surprising that interest to find out, s. Unfortunately the

experimental apparatus is in Stockholm and it is thus difficult to find out whether some of its properties may be responsible for the unusual results. It is recommended that experiments are carried out with the Taylor Couette apparatus in Kyoto.

Student: Kensuke SAKAKI (M2) Title: Nonlinear Analysis of Internally Heated Flow in an Inclines Plane Parallel Channel Professor Patrick HUERRE (2/17/’06) Comprehensive investigation of the state diagram and bifurcation structure of internally heated flow down an inclined parallel channel. This is an impressive study which demonstrates the expertise of the student in the use of bifurcation analysis. It might be worthwhile to investigate the case of non-zero mass flux to determine domains of absolute versus convective instability. Professor Alessandro BOTTARO (2/20/’06) Piece of work strongly related to that by student Ryota Horie: in place of the Reynolds number the control parameter is the inclination angle of the fluid layer. The student has come to the meeting well prepared, with a text written in English and several illustrations of flow structure and bifurcation diagrams. The work is complete and worthy of publication. Like for the case of other student, also in this case it would be interesting to investigate the competition among different patterns by feeding an initial condition to a Navier-Stokes code, composed by a few elementary patterns plus small amplitude noise; to study the dynamics of defects seems to me like a worthwhile task to pursue. Professor Friedrich BUSSE (3/2/’06) Convection patterns in an inclined heated fluid layer have received relatively little attention so far. In particular the case of an inclined internally heated is treated here for the first time. Already the case of small inclinations exhibits a rich bifurcation structure. Surprisingly, the bifurcation of square convection is subcritical indicating a change of sign of the coefficient of the cubic term in the amplitude equation relative to the Rayleigh-Bénard case. As expected, subcritical hexagons are stable on their upper branch, but at higher values of Gr they become unstable to rolls. The stability analysis of rolls will probably reveal a region where both hexagons and rolls are stable simultaneously (see Busse, 1967). It would be useful if the maximum of the temperature would be used instead of the energy norm. First, it is easily measured in experiments. Secondly it is of interest in applications: internal heat generation in chemical reactions etc.

Student: Ryota HORIE (M2) Title: Convection with an Internal Heat Source under the Influence of Poiseuille Component Professor Patrick HUERRE (2/17/’06) Again, this is a very complete study of the effect of a thru-flow component on the stability of convection induced by an internal heat source. It is known that thru-flow in classical Rayleigh-Bénard convection induces a change from convective to absolute instability, as demonstrated by Carriére & Monkevitz. It might be worthwhile to investigate the same phenomenon in the present situation, since absolute instability ultimately determines whether a given flow pattern is observable or not. Professor Alessandro BOTTARO (2/20/’06) Very nice piece of work, presented in good English. The student has conducted linear and non-linear analysis of mixed convection flow in a channel, focussing on the zero and low Reynolds number regimes. The most interesting part of the work concerns the pattern selection and the bifurcation diagram. For Re=0 the bifurcation from the steady state is subcritical and hexagonal texures are produced. A secondary subharmonic bifurcation of the hexagons ensues at large values of the Grashof numbers (studied via Floquet analysis). At (slightly) larger Re the bifurcation structure is even more complex. My feeling is that this contribution is worthy of publication in anchival Journal. Further topics which could possibly be explored are the onset and evolution of defects, and the characterization of phase turbulence (i.e., mediated by defects). Of course, this could not be handled by continuation/Newton, but would require full N.S. computations. Professor Friedrich BUSSE (3/2/’06) The bifurcation structure of convection in a horizontal internally heated layer has been analyses with particular emphasis on the case when the layer is subject to a Poiseuille flow. In the presence of the patter the bifurcation structure become wuite complex and an analytical approach based on coupled amplitude equations could help to separate the different branches of solutions. As in the case of the similar problem analysed by Sakaki it must be expected that the rolls become stable at higher values of the Grashof number and that there will be region where both rolls and hexagon solution will be stable (Busse, 1967). At finite values of the Reynolds number R the streamwise wavelength tends to lengthen and the hexagon pattern becomes enlarged in the streamwise direction. Hence not √3, but the lower value 1.5 must be expected at R=3 as the streamwise wavenumber

of the most stable hexagon pattern. Further investigations of this problem are recommended.

Student: Toshiya KIJIMA (M1) Title: Experimental results for rotating coaxial cylinders with density stratification Professor Patrick HUERRE (2/17/'06) Original experimental configuration designed to investigate the effect of a density jump or of a density stratification on the onset of Taylor vortices. A reliable PIV method has been setup and tested. It will lead to new insight on this novel study where very little is presently known Professor Friedrich BUSSE (3/2/'06) PIV-measurements of Taylor vortices in a Taylor-Couette apparatus filled with a stably stratified fluid are carried out. So far the case of a jump in the density of the fluid at about half the height of the cylinders has been measured. Because of the mixing owing to the onset of the Taylor vortices the density jump is quickly eroded. More interesting will be the case of a linear variation of density with height. The Taylor vortices should then create a stepwise change of density with height. The density variation exacts a stabilizing influence of the onset of Taylor vortices. One expects that the wavelength of the Taylor vortices will be smaller than in the case of a homogeneous fluid. It may be easier to observe the wavelength with Kalliroscope particles than with PIV-measurements.

Student: Kouji KITAGAWA (M1) Title: Stability of modulated rotating plane Couette flow Professor Patrik HUERRE (2/17/’06) Impressive study by bifurcation analysis and direct numerical simulation of a complicated flow problem where both rotation and modulation come into play. Would spatial modulation introduce different features, as for instance in the studies of Floryan for spatially modulated plane Couette flow or Poiseuille flow ? Professor Friedrich H. BUSSE (3/2/’06) This is an interesting analysis of the influence of modulated boundaries on the onset of instability. The oscillatory motion of the boundary has been investigated experimentally in the case of the Taylor-Couette-system. The present analysis is applicable to the experiment even though the small gap limit is not well approached in the experiment. Since the subharmonic instability has not been observed in an experiment as far as I know, it will be of interest to find the lowest value of ε and for which the subharmonic mode is preferred. Of course, an analysis of the onset of transverse modes needs to be carried out first, in order to confirm that the transverse modes may not precede the one of the subharmonic longitudinal mode.

2γ

Student: Shuichi MASUDA (M1) Title: Plane Poiseuille Flow with Streamwise System Rotation Professor Patrick HUERRE (2/17/’06) Very good primary instability study of plane Poiseuille flow in the presence of rotation around a streamwise axis. The investigation reveals a stabilizing effect of rotation. It might be worthwhile to determine if the “non-modal” growth of disturbances is enhanced or suppressed by rotation, thereby promoting on delaying transition to turbulence. Professor Alessandro BOTTARO (2/21/’06) This student is conducting a linear and non-linear stability analysis of rotating channel flow. The axis of rotating is along the streamwise direction x (so that 2 contributions to the momentum equation arise along the y and z directions) and the base flow is maintained to be the Poiseuille base flow. The interesting new result in the linear analysis is that a 3D instability mode (certainly of Coriolis origin) is found for small Re and large Ω. As Ω↑ the region of instability gets closer to the α→0 axis, and this may suggest a long wavelength asymptotic approximations of the problem. The nonlinear results are quite preliminary and are, for the moment, limited to the 2D case. Professor Friedrich BUSSE (3/2/’06) Shear flow instabilities often occur in a rotating system at much lower Reynolds number than in a non-rotating system. I would have thought that a fundamental problem such as Poiseuille flow with streamwise axis of rotation would have been investigated a time ago since T. Pedley investigated the analogous problem for pipe flow already in the 1960ies. The results obtained so far show a very broad minimum of the Reynolds number in the space of the rotation parameter and of the streawise and spanwise wavenumbers. Rolls which are slightly oblique with respect to the streamwise direction are preferred. It will be of interest to learn about their finite amplitude properties.

Report 3 May 2005

Report on

COE Research at Kyoto University on Vibration Control of Inverted Pendulum Systems and Stayed Cables

Nguyen Dong Anh

Professor, Head of Department of Vibration and Structure Institute of Mechanics

Vietnamese Academy of Science and Technology

1. Introduction Kyoto University and my host, Professor Dr. Hiroshi Matsuhisa of the Department of Precision Engineering, kindly invited me to work as a Visiting Scholar in a new COE Project at Kyoto University. My research stay was scheduled for the two months of April and May 2005; more precisely, I visited Kyoto University from April 4, 2004 to May 26, 2005. The COE project "Center of Excellence for Research and Education on Complex Functional Mechanical Systems" belongs to the COE (Center of Excellence) Program of the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). During the visit Prof. H. Matsuhisa and I have been working in two research problems, namely:

- Problem of vibration control of inverted pendulum systems - Problem of vibration control of stayed cables

The following sections of this report describe research discussions and results, lectures held in Kyoto University, and technical visits outside Kyoto University. 2. Research Discussions and Results 2.1 Problem of vibration control of inverted pendulum systems A tuned-mass damper (TMD), or dynamic vibration absorber (DVA), is found to be an efficient, reliable and low-cost suppression device for vibrations caused by harmonic or narrow-band excitations. This device comprising a mass, springs, and viscous damper was proposed in 1909 and has been widely used in many fields of engineering [1-3]. The dynamic absorber for wind induced vibration of ropeway carriers was investigated theoretically by Matsuhisa [4]. The ropeway carrier can be regarded as a rigid-body pendulum and the theory of location was established in 1993. The theory indicates that the effectiveness is proportional to the square of the distance of the absorber from the center of oscillation consequently the effectiveness of the dynamic absorber depends much on its location. In the case of gondola, the center of oscillation is around the mid point between the center of gravity and the bottom

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of the gondola. It means that the absorber at the bottom of gondola does not work well. The absorber must be located as high as possible, and even if the absorber is at the fulcrum, it works very well. Since the first in the world installation (1995) of the dynamic absorber on the ropeway chair lifts the dynamic absorbers have been installed on about 20 ropeways. The pendulum type systems have high interest in research and engineering application. Thus, the purpose of this research cooperation is to extend the theory of location [4] as further as possible to those systems. In fact, an alternative class of pendulum systems is so called inverted pendulum is well-known. The research phenomena involved in the inverted pendulum systems are much larger than those in the conventional pendulum type ones, namely, the first can be stable or unstable while the later can be stable only. The (single and multiple) unstable inverted pendulum is an example dealing with classical as well as modern control and in Robotics. It is challenging to design/tune stabilizing controllers for this inherently unstable system [5-10]. The based-excited inverted pendulum has occurred in many control problems [11-13]. An aspect in the study of human locomotion is to simulate the unstable equilibrium of the trunk about the upright position and to relate to the control law that human use during walking. The human trunk is modeled as an inverted pendulum with up to 3 degrees of rotational freedom. The base point of the pendulum corresponds to the centre of the pelvis and is allowed to move in three directions [14]. The problem “man–machine” closely related to the balancing of an inverted pendulum has noteworthy consequences in biology, which relates to the explanation of self-balancing of the human body [15, 16] or in the construction of biped robots [17, 18].

The stable invested pendulum type systems can be an adequate model in civil engineering. The model of beam supported by a linear-elastic torsion spring at one end and with a point mass at the other end is representative of numerous applications, for example, in the analysis of the dynamic response of soil-structure [19] or fluid-structure interactions [20]. The soil-structure interaction can be modeled by tension springs while in the fluid-structure interaction the torsion springs are due to buoyancy forces. If the bending stiffness of the beam is large enough one may use the model of inverted pendulum with a linear linear-elastic torsion spring. In [20] the response of an articulated tower in the ocean subjected to deterministic and random wave loading was investigated. The tower was modeled as an upright rigid pendulum with a concentrated mass at the top and having one angular degree of freedom about a hinge with Coulomb damping which can be replaced approximately by an equivalent linear viscous one. Compliant platforms such as articulated towers are economically attractive for deep-water conditions because of their reduced structural weight compared to conventional platforms. The foundation of the tower does not resist lateral forces due to wind, waves and currents; instead, restoring moments are provided by a large buoyancy force, a set of guy-lines or a combination of both [21-24].

It should be noted that in all above mentioned researches the use of dynamic absorbers as an additional tool for vibration control was not considered. Thus, the control problem of unstable and stable inverted pendulum type systems using different kinds of dynamic absorbers such as passive, semi-active, and active ones might be an aspect of high interest.

Several discussions with my host, Professor Hiroshi Matsuhisa were held. He introduced the theoretical and experimental research carried out at his Laboratory on the problem of vibration control of conventional pendulum systems. Further, we have been extending intensively to the vibration control problem for a stable inverted pendulum with passive mass-spring-pendulum type DVA with an application to the articulated tower in the ocean. The following manuscript was completed for subbition to publication:

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N. D. Anh, H. Matsuhisa, L. D. Viet , M. Yasuda, Vibration control of an inverted pendulum type structure by passive mass-spring-pendulum dynamic vibration absorber

Reference 1. J.P. Den Hartog. Mechanical Vibration (4th Edition ed.), McGraw-Hill, 87-106, (1956). 2. J.C. Snowdon. Vibration and Shock in Damped Mechanical System, Wiley, New York (1968). 3. R.G. Jacquot and D. Hoppe, Optimal random vibration absorbers. Journal of Engineering Mechanics Division, American Society of Civil Engineers 99 (1973), pp. 612–616 4. H. Matsuhisa, R. Gu, Y. Wang, O. Nishihara, and S. Sato, Vibration control of a ropeway carrier by passive dynamic vibration absorbers, JSME International Journal (Series C), 38-4, 657-662, (1995). 5. S.R. Bishop and D.J. Sudor, The ‘not quite’ inverted pendulum, Int. J. Bifurcat. Chaos 19 (1999) (1), pp. 273–285. 6. Niemann, H., & Poulsen J. K., Analysis and design of controllers for a double inverted pendulum. In Proceedings of the American control conference, Denver, CO, (2003), USA pp. 2903–2808. 7. H. Su and C. A. Woodham, On the uncontrollable damped triple inverted pendulum. J. Computational and Applied Mathematics, Volume 151, Issue 2, 2003, Pages 425-443. 8. C. Anderson, Learning to control an inverted pendulum using neural network, IEEE Control Systems Mag. (1989) 31–36. 9. V. Williams and K. Matsuoka, Learning to balance the inverted pendulum using neural networks, Proceedings of the International Joint Conference on Neural Networks, Singapore (1993), pp. 214–219 10. A. Bradshaw and J. Shao, Swing-up control of inverted pendulum system, Robotica 14 (1996), pp. 397–405. 11. E. Koyanagi, S. Iida, K. Kimoto and S. Yuta, A wheeled inverse pendulum type self-contained mobile robot and its two-dimensional trajectory control. In: Proc. of ISMCR'92 (1992), pp. 891–898. 12. O. Matsumoto, S. Kajita and K. Tani, Attitude estimation of the wheeled inverted pendulum using adaptive observer. In: Proc. of 9th Academic Conf. of the Robotics Society of Japan (1991), pp. 909–910 (in Japanese). 13. Yavin Y., Fragos C., On a horizontal version of the inverted pendulum. Comput.Methods Appl.Mech.Engrg. 121 (1997), pp. 297-309. 14. C.K. Chow and D.H. Jacobson , Studies of Human Locomotion via Optimal Programming. Math. Biosc. 10(1971), pp. 239–306. 15. D. McRuer, Human dynamics in man–machine systems, Automatica 16 (1980), pp. 237–253. 16. B. Widrow and T. Viral, An adaptive (broom balancer) with visual inputs, Proceedings of the IEEE International Conference on Neural Networks, San Diego, CA (1998), pp. II-641–II-647. 17. H. Hemami, F.C. Weimer, C.S. Robinson, C.W. Stockwell and V.S. Cvetkovic, Biped stability considerations with vestibular models, IEEE Trans. Automat. Control 23 (1978), pp. 1074–1079. 18. D.T. Higdon and R.H. Cannon, On the control of unstable multiple-output mechanical systems, ASME Publications 63-WA-48 (1963), pp. 1–12. 19. Wen-Hwa Wu, Equivalent fixed-base model for soil-structure interaction systems, Soil Dynamics and Earthquake Engineering 16 (1997) pp 323-336. 20. P. Dong, H. Benaroya and T. Wei, Integrating experiments into an energy-based reduced-order model for vortex-induced-vibrations of a cylinder mounted as an inverted pendulum Journal of Sound and Vibration, Volume 276, Issues 1-2 , pages 45-63 21. P. Bar-Avi and H. Benaroya, Non-linear dynamics of an articulated tower submerged in the ocean. Journal of Sound and Vibration 190 (1996), pp. 77–103 22. P. Bar-Avi and H. Benaroya, Stochastic response of a two DOF articulated tower International Journal of Non-Linear Mechanics, Volume 32, Issue 4, July 1997, Pages 639-655 23. S.K. Chakrabarti and D.C. Cotter, Motion analysis of articulated tower. Journal of the Waterway, Port Coastal and Ocean Division, ASCE 105 (1979), pp. 281–292. 24. O. Gottlieb, C.S. Yim and R.T. Hudspeth, Analysis of non-linear response of an articulated tower. International Journal of Offshore and Polar Engineering 2 (1992), pp. 61–66. 2.2 Problem of vibration control of stayed cables In recent years, construction of cable-stayed bridges has been very active in the world. Vietnam and Japan develops an intensive cooperation in cable bridges construction, namely Can Tho Bridge funded by JBIC (Japan Bank for International Cooperation) with cost to 38 billion JY and Bai Chay Bridge funded through ODA with an estimated cost to 70 million USD (Japanese partners of Shimizu and Sumutomo Mitsui). The problems of monitoring, maintenance and vibration control of cable bridges are of high interest [1,2].

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Stayed cables used in long span bridges are flexible and hence they may lead to large-amplitude cable vibrations induced by direct environmental loads such as those from moving vehicles, wind or wind-rain combination. The significant influence of cable vibration on the dynamics of cable-stayed bridges has been shown by many authors [3,4]. Thus, the cable vibration control problem is a serious concern to engineers in the design of new bridges and for retrofit of existing bridges. Full-scale measurements show that vibrations of moderate amplitude can occur over a wide range of cable modes [5].

Damping elements is an efficient tool for structures to achieve high performance at relatively low cost when the structures are subjected to external disturbances. To suppress undesired cable vibrations subjected to dynamic loadings one may install passive, active or semi-active energy dissipation devices close to the cable end at bridge desk [6]. In recent years, serious efforts have been undertaken to investigate energy dissipation systems, such as friction, metallic, viscous, tuning mass or liquid dampers, which are characterized by a capacity to dissipate energy when subjected to deformation or motion [7]). The energy dissipation may be achieved either by convention of kinetic energy to heat or by transferring of energy among vibration modes. When a stayed cable is subjected to moderate external disturbance, a good performance may be expected when connected to linear fluid damper. A fluid VS damper dissipates energy by forcing a fluid through an orifice causing a damping pressure and a force. In the linear VS dampers this force is proportional to the relative velocity between the damper ends. As it was shown by Lee and Taylor [8] the addition of currently available dampers to a structure could provide damping as high as 35% critical. Fluid VS dampers have been investigated and numerically modeled by many authors [9-12]. Nonlinear VS dampers design has recently been addressed by [13]. Some studies have been published regarding VS dampers design methodologies control of structures. Gluck et al. [14] suggested a design method for supplemental dampers in multi-story structures, adapting the optimal control theory by using a linear quadratic regulator (LQR).

The purpose of the research cooperation is to outline in detail principal theoretical and technical aspects in the problem of taut cable vibration mitigation by using linear viscous damper in order to apply to real structures such as My Thuan Bridge in Mekong delta. The first result of cooperation is written in a manuscript ready for publication:

H. Matsuhisa, N. D. Anh, P.X. Khang, T. X. Khiem, N. N. Long, N.C. Sang, P.X. Son, N.C. Thang, T.H.Vinh, K. Yamad, Vibration control of stayed cables using fluid dampers. Reperences 1. D.L. Balageas (Ed.), Structural Health Monitoring 2002, Destech Publications, Lancaster, 2002. 2. Y. Fujino, Vibration, control and monitoring of long-span bridges-recent research, developments and practice in Japan, Journal of Constructional Steel Research, Volume 58, Issue 1, January 2002, Pages 71-97. 3. Abdel-Ghaffar A.M., Khalifa M.A., Importance of cable vibration in dynamics of cable-stayed bridges. ASCE J. of Engineering Mechanics, 1991, 117, 2571-2589. 4. Caetano E. et al., The role of stay cables in the seismic response of cable-stayed bridges, 16th Int. Conf. on Modal Analysis, Santa Barbara, California, USA, 1998, vol.2, 1346-1352. 5. Main, J. A., and Jones, N. P., Full-scale measurements of stay cable vibration, 10th Int. Conf. on Wind Engineering, Balkema, Rotterdam, The Netherlands, 1999, 963–970. 6. Premont, A. Vibration control of active structures, Second Edition, Kluwer, Dordrecht. 7. Soong T.T., Supplemental energy dissipation: State-of-the-art and state-of-the-practice, Int. Conf. on Advances in Structural Dynamics, Eds. Ko J.M. and Xu Y.L., Elsevier, 2000, 109-120. 8. D. Lee and D.P. Taylor, Viscous damper development and future trends. Struct Des Tall Buil 10 5 (2002), pp. 311–320. 9. D.P. Taylor and M.C. Constantinou, Testing procedures for high-output fluid viscous dampers used in building and bridge structures to dissipate seismic energy. Shock Vib 2 5 (1995), pp. 373–381.

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10. Aiken, I.D. and Kelly, J.M., Cyclic Dynamic Testing of FVDs. Proceedings, Caltrans, Fourth Seismic

Research Workshop, Sacramento, California, July, 1996.

11. Fu, Y. and Kasai, K. (1998), Comparative Study of Frames Using Visco-elastic and Viscous Damper,

Journal of Structural Engineering, ASCE, 124(5), 513-522.

12. Constantinou, M.C., Tsopelas, P., Hammel, W. and Sigaher, A.N. (2000), “New Configurations of Fluid

Viscous Dampers for Improved Performance”, Symposium of Passive Control Structures – 2000, Tokyo Institute

of Technology, 261-272.

13. Pekan, G., Mander, J.B. and Chen, S.S. (1999), “Fundamental Considerations for The Design of Nonlinear

Viscous Damper”, Earthquake Engineering and Structural Dynamics, 28, 1405-1425.

14. N. Gluck, A.M. Reinhorn, J. Gluck and R. Levy, Design of supplemental dampers for control of structures. J

Struct Eng 122 12 (1996), pp. 1394–1399.

3. Lectures in Kyoto University During my research stay, I presented two lectures within Kyoto University. The first one, called the COE-Lecture, was dedicated to all doctoral students of the whole COE Project and was held on May 6, 2005. The modified version was given to students of Matsuhisa Lab and was held on May 18, 2005. The title of the COE-Lecture was "Vibration mitigation for taut stayed cables; From theory to practical experiment”. The lecture provides an overview on design and experiment techniques which can be used for the damper-cable system. The abstract of the lecture is the following: The purpose of the lecture is to outline some principal steps in the problem of taut cable vibration mitigation by using linear viscous damper. The structure and concept for fluid viscous damper are presented with numerical and experimental comparison for a two-way fluid viscous damper. The damper performance in the cable vibration modes is of particular interest. The problem is to investigate the dynamics of the cable-damper system in vibration modes depending on the parameters under consideration and to obtain results for the modal damping ratios and for optimal tuning of the damper. The experiments with fluid dampers-cables are carried out at the Laboratory and at Ben Coc stayed cable bridge in Hatay province. Some technical aspects in the field of taut cable vibration control are presented in order to show how the scientists from mechanical and civil engineering may cooperate. Further, possible activities and proposals for developing Vietnam-Japan scientific and friendship cooperation are discussed. A short introduction to Vietnam, its landscapes and people, Vietnamese Academy of Science and Technology is also presented. On May 23, 2005 I participated in the Seminar on Vibration and Control organized by the Sociaty of Vibration and Control in Kansai area and presented one-hour-report on my ongoing research at Kyoto University. 4. Visits outside Kyoto University Four technical visits inside and outside Kyoto University were made during my stay. The visit to the Shimadzu Head-office in Kyoto was held on April 27 with the participation of Prof. Masuhisa. During the visit, Dr. Ken Emori, General Manager, introduced shortly about main activities of Shimadzu Corporation. We discussed then the possibility of buying for Institute

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of Mechanics Hanoi a Jack System in late 2005. Some valuable understandings were obtained for both sides. My second visit was held at MTS Japan LTD in Osaka. The purpose of the visit was to have more information and discussion on the shaking table products of MTS. The next visit was to Tokyokiki Corporation in Amagasaki City where many isolation and vibration equipments are produced. Dr. Masashi Yasuda, Senior Vice President introduced me many useful information and research materials in the field of vibration control. Both second and third visit were made on April 28. My fourth visit was made in order to meet Professor Dr. Masaru Matsumoto of the Department of Civil and Earth Resources Engineering at the Kyoto University. The Laboratory of Professor Matsumoto has been working actively in the field of cable bridges under wind loadings. Many interesting materials and opinions were exchanged at the visit. 5. Acknowledgment I would like to express deep thanks to the Kyoto University, particularly to my host Professor Dr. Hiroshi Matsuhisa, to the whole staff and students of his lab, and administrative staffs for their kind support and friendships during my visit at Kyoto University. I have very good atmosphere for research cooperation and learning interesting Japanese life.

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