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Simulations of contrast effects from free microbubbles in relation to their size, concentration and acoustic properties

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JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 1997年第5B期36卷 3242-3245页

作者： Chan, M Soetanto, K Okujima, M Department of Control and System Engineering Faculty of Engineering Toin University of Yokohama Toin Human Science and Technology Center (HUSTEC) 1614 Kurogane-cho Aoba-ku Yokohama 225 Japan

To gain a deeper in sight into the diagnostic images produced by microbubbles as ultrasound contrast agents, the basic acoustical properties such as the scattering cross section, extinction cross section and the expected backscattered power from different sized microbubbles are calculated. The results proved that the ratio of scattering to extinction cross section, size and concentration of microbubbles are the factors determining the maximum backscattered power received from microbubble dispersions. When microbubbles decrease in size, the energy loss by microbubbles upon ultrasound exposure gradually changes from loss by scattering to loss by absorption. As a result, the concentration of microbubbles required to produce a B mode image of the comparable brightness is increased. However, an increased concentration of microbubbles does not necessarily produce a clearer image. In this paper, it is further established that an optimum concentration exists at which the microbubbles give maximum backscattered power. The optimum microbubble concentration and the maximum backscattered power also depend on the depth of the microbubbles in the microbubble dispersion. In addition, the concentration of microbubbles necessary to produce the maximum backscattered power during resonance is less than that at other frequencies.

关键词： microbubbles ultrasound contrast agent backscattered power optimum concentration microbubble dispersion

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Change in size and number of sodium laurate microbubbles with time in saline at different air concentrations

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JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 1997年第5B期36卷 3238-3241页

作者： Soetanto, K Chan, M Okujima, M Department of Control and System Engineering Faculty of Engineering Toin University of Yokohama Toin Human Science and Technology Center (HUSTEC) 1614 Kurogane-cho Aoba-ku Yokohama 225 Japan

The study of the annihilation mechanisms of microbubbles is a very important topic in the development of ultrasound contrast agents. To gain better insight into the annihilation mechanisms, knowledge of the change in the number and size of microbubbles with time in saline is necessary. In this study, the use of a Coulter Multisizer is proposed, and the change in number and size of microbubbles is accurately measured. As a result, mechanisms for longevity and annihilation are suggested. Sodium laurate is used for the coating layer of the microbubbles. The measured longevity of sodium laurate microbubbles is compared with the results of a simulation of free air microbubbles. Although the coating layers lower the diffusion rate of air from microbubbles, diffusion still occurs. The diffusion of air contributes to the size of the microbubbles and the dissolution of the surfactant coating layer causes a decrease in the number of microbubbles. The reasons for these assertions are discussed in this paper. When the concentration of dissolved air in saline is close to saturation, the annihilation mechanism of sodium laurate microbubbles changes to the dissolution of the coating layer into the solution. In addition, it is proposed from the experimental results that small particles less than 10 mu m in size which dissolve slowly in saline are formed after the shrinking of microbubbles by diffusion.

关键词： ultrasound contrast agent sodium laurate Coulter Multisizer annihilation mechanisms microbubble longevity diffusion dissolution

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Effect of ultrasound acoustic characteristics in cattle liver under ultrasound exposure

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JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 1997年第5B期36卷 3228-3232页

作者： Soetanto, K Saisu, Y Okujima, M Department of Control and System Engineering Faculty of Engineering Toin University of Yokohama Toin Human Science and Technology Center (HUSTEC) 1614 Kurogane-cho Aoba-ku Yokohama 225 Japan

The effects of ultrasound exposure on the living body can be divided into thermal and non-thermal effects. In this study, the thermal effect was considered and temperature elevation due to ultrasound exposure was examined. First, experimental apparatus for measurement of temperature elevation was considered. Then, fundamental experiments to record the thermal effect of ultrasound waves on different substances were carried out. These included measuring the acoustic characteristics and temperature elevation of degassed water, tissue samples and samples made from agar, having properties similar to those of tissues. It was clarified on noted that the attenuation constant of tissue decreases after ultrasound exposure. Finally, it proposed that the viscosity of a target changes according to ultrasound exposure, and the proposition was investigated experimentally.

关键词： diagnostic ultrasound bioeffects thermal effect viscosity attenuation constant temperature elevation

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Unsteady signal analysis by using wavelet transform

Unsteady signal analysis by using wavelet transform

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IEEE International Conference on Intelligent Processing systems, ICIPS

作者： Zhong Zhang H. Kawabata Department of System Engineering Industral Technology Center of Okayama Prefecture Haga Japan Faculty of Computer Science and System Engineering Okayama Prefectural University Soja Japan

In this paper, we will pay attention to the spline wavelets which are real-type wavelets and have good characteristics such as compact support, the symmetric property and so on. We propose an RI-Spline wavelet which is complex-type wavelet and has the compact support, and we confirm the effectivity of this wavelet in the continuous case by a model signal. Next, for the application of the spline wavelets to control golf sound, we examine the relation between golf impact sound and vibration velocity of golf club. As a result, it is found that using the continuous and discrete wavelet transform together is effective for the analysis of the sound and the vibration. This technique will be useful for the unsteady signal analysis.

关键词： Signal analysis Wavelet analysis Wavelet transforms Continuous wavelet transforms Spline Discrete wavelet transforms Velocity control Vibration control

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Digital Adaptive Motion Control for a Servo Mechanism

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IFAC Proceedings Volumes 1997年第11期30卷 323-328页

作者： T. Suehiro F. Ohkawa T. Hokamura S. Sagara Electronics Division Mechanics & Electronics Research Institute Fukuoka Industrial Technology Center 3-6-1 Norimatsu. Yahatanishi-ku Kitakyushu-shi 807 Japan Department of Control Engineering and Science Faculty of Computer & System Engineering Kyushu Institute of Technology lizuka 820 Japan Department of Control Engineering Faculty of Engineering Kyushu Institute of Technology Tobata Kitakyushu 804 Japan

This paper is concerned with an application of a digital adaptive control system to a servo mechanism. Mechanical systems in general include nonlinearities and additional uncertainties and which result from inertia and friction. So it is difficult to ensure robust performance and high accuracy for motion control. The digital adaptive control system presented here is considered to overcome the above stated problem. Experimental results from a feed drive system demonstrate the effectiveness of the proposed control scheme.

关键词： Adaptive Control Servomechanism Nonlinearity Uncertainty Friction

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A fast minimum cost flow algorithm for VLSI layout compaction

A fast minimum cost flow algorithm for VLSI layout compactio...

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IEEE International Symposium on Circuits and systems (ISCAS)

作者： I. Arungsrisangchai Y. Shigehiro I. Shirakawa H. Takahashi Department of Electronic Engineering King Mongkut's Institute of Technology Bangkok Thailand Department of Information Systems Engineering Faculty of Engineering Osaka University Suita Japan Department of Communication Engineering Faculty of Computer Science and System Engincering Okayama Prefectural University Japan

Since the layout compaction problem is dual to the minimum cost flow problem, flow algorithms can be applicable to the layout compaction. In this paper, an existing flow algorithm is investigated in terms of the layout compaction, and a fast flow algorithm is devised on the basis of the primal-dual method. Experimental results show that the proposed algorithm is the fastest dedicatedly for the compaction problem.

关键词： Costs Very large scale integration Compaction Constraint optimization Information systems systems engineering and theory Computer science Productivity Linear programming Constraint theory

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A rough set approach for planner evaluation

A rough set approach for planner evaluation

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IEEE International Conference on systems, Man and Cybernetics

作者： B.K. Sy Wang Jiaxin Pattern Analysis and Machine Intelligence Group System Design Engineering Department University of Waterloo Waterloo ONT Canada Department of Computer Science CUNY Flushing NY USA The State Key Laboratory of Intelligent Technology and Systems Department of Computer Science and Technology Tsinghua University Beijing China

This paper discusses a rough set approach for evaluating solutions of scheduling problems. Algorithms for solving scheduling problems are planners and the scheduling problems are modelled as constraint satisfaction problems. Conventional approach for the analysis of algorithms often focuses on the time and representational complexities, and assumes an identical cost on all operations. The proposed rough set approach augments conventional approaches for the analysis of algorithms in two ways: 1) it permits the consideration of different costs arising from different operations; and 2) it allows one to define a new utility for a complexity analysis.

关键词： Algorithm design and analysis Processor scheduling Set theory Machine intelligence Computer science Costs Search problems Educational institutions Pattern analysis system analysis and design

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Adaptive Speed Control Using an RBF Network for a Servo Motor in the Presence of Angle Dependent Disturbances

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IFAC Proceedings Volumes 1997年第11期30卷 59-64页

作者： Zi-jiang Yang Koichi Hirata Teruo Tsuji Faculty of Computer Engineering and System Science Kyushu Institute of Technology Iizuka Fukuoka 820 Japan TEL: +81-948-29-7672 FAX: +81-948-29-7651 Department of Electrical Engineering Kyushu Institute of Technology 1-1 Sensui-cho Tobataku Kitakyushu 804 Japan

It is well-known that the angle dependent disturbances in a servo motor caused by nonuniformity of field windings, armature cogging, rotor imbalance, nonuniform load etc., may influence the speed control performance greatly. This often leads to large speed fluctuations which are undesired in practical situations. Therefore speed fluctuation reduction techniques in the presence of angle dependent disturbances are strongly required and have been being challenged by a lot of researchers. In this paper, the authors propose a new approach to this problem via adaptive control with the aid of a radial basis function (RBF) network composed of gaussian basis functions. The angle dependent disturbances which are viewed as a periodic nonlinear function with a period of 2π[rad] in the angle-domain, is approximated by a RBF network in the domain of [0, 2π)[rad]. Then an adaptive linearization control system employing the RBF network which compensates the disturbances is proposed. The RBF network has the advantage that it is linear-in-parameter and hence the parameter adaption is very fast and easy to implement. It is proved through theoretical analysis that the stability of the adaptive control is guaranteed by the Lyapunov stability theory. Finally, simulational and experimental results are included in the paper to show the excellent performance of the proposed method.

关键词： Servo motor speed control angle dependent disturbance RBF network adaptive control stability

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Subspace Model Identification for Continuous-Time systems

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IFAC Proceedings Volumes 1997年第11期30卷 1567-1572页

作者： Zi-Jiang Yang Setsuo Sagara Kiyoshi Wada Faculty of Computer Engineering and System Science Kyushu Institute of Technology Iizuka Fukuoka 820 Japan TEL +81-948-29-7672 FAX +81-948-29-7651 Department of Communication Computer Engineering Fukuoka Institute of Technology Wajirohigashi Higashiku Fukuoka 811-02 Japan Department of Electrical and Electronic Systems Engineering Graduate School of Information Science and Electrical Engineering Kyushu University Hakozaki Fukuoka 812 Japan

Usually, the subspace-based state-space system identification algorithms are focused on discrete-time models, which may cause some numerical problems when the sampling interval is small. This paper proposes an algorithm of subspace-based state-space system identification for continuous-time systems from sampled input-output data. The ω — operator ω = ( p - α)/( p + α) where p denotes a differential operator and α > 0, is introduced to avoid direct numerical differentiations. And the ω — operator state-space model identified by the 4SID method can be transformed back to the common continuous-time state-space model. The numerical superiority of the ω — operator approach compared to some other methods is verified through simulation study.

关键词： Subspace model identification continuous-time system ω—operator sampled data

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Impedance control for articulated robot of 6 degree-of-freedom in consideration of critically damped condition with an object dynamics

Impedance control for articulated robot of 6 degree-of-freed...

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SICE Annual Conference

作者： F. Nagata K. Watanabe K. Sato K. Izumi T. Suehiro Interior Design Research Institute Fukuoka Industrial Technology Center Fukuoka Japan Department of Mechanical Engineering Faculty of Science and Engineering Saga University Saga Japan Mechanics and Electronics Research Institute Fukuoka Industrial Technology Center Fukuoka Japan

This paper presents a new position-based impedance control that can take into account of a desired position in the force control, and gives a transformation technique from the position command to the torque command in order to apply the control to an industrial robot whose servo system is opened or to implement it in computer simulations. In order to determine a suitable compliance without trial and error, this paper introduces a new method that produces the desired time-varying compliance, giving the critical damping in contact with an object, by using information on inertia matrices. Simulation results have shown that the proposed methods are very effective for realizing it in industrial robots and for deciding the desired compliance without any complicated tuning.

关键词： Impedance Robot control Service robots Force control Torque control Computer industry Electrical equipment industry Industrial control Servomechanisms Computer simulation

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