In this method, the closest trajectory input derived a priori from the nonstationary optimal control theory to the object distance is used as a feedforward control and the positioning error at the terminal point is co...
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In this method, the closest trajectory input derived a priori from the nonstationary optimal control theory to the object distance is used as a feedforward control and the positioning error at the terminal point is compensated by the nonstationary robust feedback control to which it is smoothly switched. By applying the method to a positioning control of a flexible structure, the usefulness of the method is verified theoretically and experimentally. Moreover, from a comparison between the nonstationary robust control and a conventional robust servo control for a positioning control of a two-mass-spring system, the advantage of the former one is demonstrated.
Compact reconstruction of hologram is an important technique to popularize the hologram widely. Edge illumination methods to realize this are reviewed and the features are discussed. The method to illuminate the holog...
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ISBN:
(纸本)0819422622
Compact reconstruction of hologram is an important technique to popularize the hologram widely. Edge illumination methods to realize this are reviewed and the features are discussed. The method to illuminate the hologram at large angle in air is also discussed and some experimental results are presented.
In order to stabilize microbubbles without coating layers to be used as ultrasound contrast agent, the viscosity of the liquid for storage has to be increased. Sodium alginate is a material which forms viscous liquid ...
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In order to stabilize microbubbles without coating layers to be used as ultrasound contrast agent, the viscosity of the liquid for storage has to be increased. Sodium alginate is a material which forms viscous liquid when its powder is dissolved in water. The viscosity may vary from 1 cP to about 100 cP when the amount of material used is increased from 0.1% to 1%. However, the viscosity is still not enough to make stable microbubbles which can be stored for over several weeks. In this paper, by adding calcium chloride to the sodium alginate solution, a gel-type solution is produced which has a high viscosity capable of holding microbubbles for a long time. By measuring the viscosity of the sodium alginate solution and the solution with calcium chloride solution added, it is known that the solution is changed from a Newtonian liquid to a non-Newtonian liquid when calcium chloride solution is added. Since the attenuation coefficient of microbubble dispersion is proportional to title number of microbubbles, the disappearance of microbubbles lowers the attenuation coefficient. Therefore, in this study the attenuation coefficient is used as an estimating parameter for the lifetime of microbubbles.
An algorithm that derives tool access directions for machining free-form shapes is presented. A free-form shape to be machined is given by a preliminary B-spline model. We allow that the Bspline surface data are as in...
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In this study, to make microbubbles less than 10 mu m and to extend their lifetime, sodium laurate is chosen as the material for the coating of microbubbles. In studies of ultrasound contrast agents, the authors are t...
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In this study, to make microbubbles less than 10 mu m and to extend their lifetime, sodium laurate is chosen as the material for the coating of microbubbles. In studies of ultrasound contrast agents, the authors are the first to report on the use of sodium laurate as the material for manufacturing the microbubble contrast agent. In addition, the method of producing microbubbles using a syringe is proposed. Using sodium laurate and the syringe method, microbubbles with diameter less than 10 mu m are produced. From the result of simulation, it is found that the dissolved gas concentration in the solution surrounding microbubbles plays an important role in determining microbubble lifetime. Microbubbles without coating are calculated to have a lifetime of less than 1 min when the dissolved concentration of gas is about 90%. On the other hand, the lifetime of microbubbles made from sodium laurate is about 5 min longer than the calculated lifetime. Therefore, it is hypothesized that when the dissolved gas in the solution is above a certain level, the mechanism governing annihilation of microbubbles is the dissolution of the surfactant coating layer into the solution, instead of the diffusion of gas from the microbubbles. Since the dissolution time of surfactants is longer than the dissolution time of gas, the lifetime becomes longer.
The role of fluctuations in the disorder-lamellar transition in a block copolymer melt is investigated using a cell dynamical system simulation by measuring the propagation velocity of the interface between ordered an...
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The role of fluctuations in the disorder-lamellar transition in a block copolymer melt is investigated using a cell dynamical system simulation by measuring the propagation velocity of the interface between ordered and disordered regions. Our results strongly suggest that near the transition temperature, in the absence of noise, the velocity increases with quench depth as v∼τ [τ=(Tc−T)Tc is the reduced temperature measured from the transition temperature Tc], while in the presence of noise, the velocity increases as v∼τ. These results lead us to conclude that the addition of noise causes the disorder-lamellar transition to change from second order to first order. This conclusion is consistent with the prediction of Brazovskii [Sov. Phys. JETP 41, 85 (1975)].
This paper presents the mathematical analysis and measured results of a novel practical MMIC negative resistance structure. This structure operates at X and Ku bands. The measured results show a negative resistance (d...
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This paper presents the mathematical analysis and measured results of a novel practical MMIC negative resistance structure. This structure operates at X and Ku bands. The measured results show a negative resistance (down to -50 /spl Omega/) over a 6 GHz bandwidth centered at 11 GHz.
This paper describes a decoupling force control strategy of redundant manipulator by workspace observer. In general, the calculation process of the redundant manipulator becomes complex as the number of degree-of- fre...
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A method of motion segmentation in RGB image sequences is presented in details. The method is based on moving object modeling bq a six-variate Gaussian distribution and a hidden Markov random field (MRF) framework. It...
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A method of motion segmentation in RGB image sequences is presented in details. The method is based on moving object modeling bq a six-variate Gaussian distribution and a hidden Markov random field (MRF) framework. It is an extended and improved version of our previous work. Based on mathematical principles the energy expression of MRF is modified. Moreover, an initialization procedure for the first frame of the sequence is introduced. Both modifications result in new interesting features. The first involves a rather simple parameter estimation which has to be performed before the use of the method. Now, the values of Maximum Likelihood (ML) estimators of the parameters can be used without any user's modifications. The last allows one to avoid finding manually the localization mask of moving object in the first frame. Experimental results showing the usefulness of the method are also included.
作者：
Ueda, KTakahashi, SFaculty of Science and Technology
Keio University Yokohama Japan 223 Shin-ichi Takahashi graduated in 1962 from the Department of Electrical Engineering
Faculty of Engineering Keio University. He received his Dr. of Eng. degree from Keio University in 1967. Presently he is Professor of Electrical Engineering Faculty of Science Technology and is engaged mostly in research on network theory and system theory. He is the author of Network System theory and the co-author of Exercise in Linear System 7heory (Corona Publ. Co.) and Basis of Signal lleory (Jikkyo Publ. Co.).
This paper shows that two complex coefficient transfer functions can be realized by a single hypercomplex coefficient network, utilizing all four outputs of the hypercomplex network. The realization is considered for ...
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This paper shows that two complex coefficient transfer functions can be realized by a single hypercomplex coefficient network, utilizing all four outputs of the hypercomplex network. The realization is considered for the case where the two arbitrary complex coefficient transfer functions do and do not have a common denominator. It is shown that the transfer functions can be realized by the hypercomplex coefficient network of the same order in the former case and by the hypercomplex coefficient network with the half-order in the latter case. The realization of the transfer functions with the common denominator is interesting, but the general method to derive the transfer functions is not known. From such a viewpoint, this paper proposes the discrete-type Kautz approximation with the positive frequency as the domain of approximation, including the optimal pole determination algorithm. By this approach, two complex coefficient transfer functions with an n-th-order common denominator are derived from the two 2n-th-order real or complex coefficient transfer functions. The method can be considered as one that simultaneously approximates the amplitude and the phase. The proposed approximation method is an approximation only for the positive frequency domain, and the property of the analytic signal that the negative frequency component is zero can be utilized. As a result, the method proposed in this paper has the advantages that the degree of freedom in the filter design is enhanced and the sampling frequency can be halved. In addition, the network structure can be simplified.
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