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Performance of a muscle-like “leaky” pneumatic actuator powered by modulated air pulses

Journal of Field Robotics 1996年第6期13卷

作者： Jan H. Cocatre-Zilgien Fred Delcomyn John M. Hart Department of Entomology University of Illinois Urbana IL 61801 Department of Entomology Neuroscience Program University of Illinois Urbana IL 61801 Department of Electrical and Computer Engineering University of Illinois Urbana IL 61801

There is current interest in the development of legged robotic devices inspired by biological walking systems. We have developed an actuator for this type of device that closely emulates the performance of muscle. The actuator is a “leaky” single-effect air cylinder controlled through a 3-way valve that either permits charging the cylinder with compressed air or opens it to the atmosphere. To emulate muscular activation with trains of identical nerve impulses that vary in frequency, we controlled the pressure in the cylinder through pulse frequency modulation. To allow a comparison between our cylinder and muscle, we evaluated the open loop performance of the cylinder and valve system in isometric (no motion) and linear isotonic (constant load) conditions. We demonstrate that this mode of activation of the cylinder makes its behavior quite close to that of muscle. Furthermore, our cylinder/valve system generated twice the tension developed by muscle of the same cross-sectional area, with half its power-to-weight ratio. © 1996 John Wiley & Sons, Inc.

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Finite element analysis of plane wave diffraction from anisotropic dielectric gratings

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ELECTRONICS AND COMMUNICATIONS IN JAPAN PART II-ELECTRONICS 1996年第1期79卷 1-10页

作者： Ohkawa, Y Tsuji, Y Koshiba, M Faculty of Engineering Hokkaido University Sapporo Japan 060 Received his B.S. and M.S. degrees in 1991 and 1993 respectively from the Department of Electronic Engineering Hokkaido University where he is currently in the doctoral program. He has been engaged in research on opto- and wave electronics. Currently in the doctoral program at Hokkaido University (Department of Electronic Engineering) where he received his B.S. and M.S. degrees in 1991 and 1993 respectively. He has been engaged in research on quantum wave phenomena in semiconductor nanostructures such as quantum wires and quantum dots. Received his B.S. M.S. and Ph.D. degrees in 1971 1973 and 1976 respectively from the Department of Electronic Engineering Hokkaido University. In 1976 he became a Lecturer at Kitami Institute of Technology where he was promoted to an Associate Professor in 1977. In 1979 he became an Associate Professor of the Department of Electronic Engineering Hokkaido University where he was promoted to Professor in 1987. He has been engaged in research on opto- and wave electronics. In 1987 he received a Best Paper Award. He is the author ofFundamentals of Finite Element Method for Opto- and Wave Electronics(Morikita)Optical Waveguide Analysis(Asakura)Optical Waveguide Analysis (McGraw-Hill) andOptical Waveguide Theory by the Finite-Element Method(KTK Scientific Publishers/Kluwer Academic Publishers). He is the co-author of one book and jointly authored six others. He is a member of the Institute of Television Engineers of Japan the Institute of Electrical Engineers of Japan the Japan Society for Simulation Technology the Japan Society for Computational Methods in Engineering and the Japan Society of Applied Electromagnetics. He is also an IEEE Senior Member.

In this paper, the formulation of the analysis based on the finite element method is presented for the first time for an anisotropic dielectric grating. By this analysis method, the diffraction characteristics of a plane wave by an anisotropic dielectric grating with an arbitrary shape can be computed easily. The finite element method is applied to the region corresponding to one period containing an anisotropic dielectric grating. The analytical relationships are applied to the boundaries on the incident and transmitted sides while the periodic boundary condition is applied to all other boundaries. Specifically, an index modulated grating and a groove grating are chosen for the analysis of the diffraction characteristics when the TE and TM waves are coupled. From the comparison with the analysis results by the coupled-mode theory and the spatial harmonic expansion method, the validity of the present method is confirmed.

关键词： diffraction grating anisotropic medium finite element method isoparametric elements Floquet's theorem

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A finite-element beam-propagation method for strongly guiding optical waveguides with magnetooptic materials

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ELECTRONICS AND COMMUNICATIONS IN JAPAN PART II-ELECTRONICS 1996年第7期79卷 22-29页

作者： Tsuji, Y Koshiba, M Tanabe, T Faculty of Engineering Hokkaido University Sapporo Japan 060 Graduated in 1991 from the Department of Electronic Engineering Hokkaido University and received his M.S. degree in 1993. He is currently working toward a doctoral degree. He has been engaged in research on the computer-aided design of optical and quantum-wave phenomena and quantum-effect devices. Graduated in 1971 from the Department of Electronic Engineering Hokkaido University and received his M.S. and Dr. of Eng. degree in 1973 and 1976 respectively. In 1976 he became a Lecturer at Kitami Institute of Technology where he was promoted to an Associate Professor in 1977. In 1979 he became an Associate Professor in the Department of Electronic Engineering Hokkaido University where he was promoted to Professor in 1987. He has been engaged in research on opto- and wave-electronics. In 1987 he received a Best Paper Award. He is the author ofFoundations of Finite Element Method for Opto- and Wave-Electronics(Morikita Publ.)Optical Waveguide Analysis(Asakura Publ.)Optical Waveguide Analysis(McGraw-Hill Book Co.) andOptical Waveguide Theory by the Finite Element Method(KTK Scientific Publishers/Kluwer Academic Publishers). He has co-authored one book and written Graduated in 1995 from the Department of Electronic Engineering Hokkaido University and is currently in the Master's program. He has been engaged in research on opto- and wave-electronics.

To the best of the knowledge of the authors, the formulation is carried out for the first time on the finite-element beam-propagation method for the analysis of the magnetooptic waveguide in which the structure varies along the propagation direction. The present method is applicable not only to the case in which refractive index difference is small but also to the case for the TE mode and the TM mode propagating in a waveguide with a large refractive index difference. To suppress the spurious reflection from the computational window edges, the transparent boundary condition is applied.

关键词： seam-propagation method finite-element method magnetooptical material optical isolator

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A correction to common advice given to young students

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INTERNATIONAL JOURNAL OF electrical engineering EDUCATION 1995年第4期32卷 366-367页

作者： Gluskin, E Department of Electrical and Computer Engineering Ben-Gurion University of the Negev Beer-Sheva Israel and The Electrical Engineering Program The College of Judea and Samaria Ariel Israel

The usual advice given to a first year student is that while the student is reading lectures notes or working with a textbook at home, he has to try to perform the derivations on his own, and even to try to first find his own way to solve the problem example, and only after that to study these details in the source. It is thought, reasonably, that in this way, the study will be effective and the student will acquire good comprehension and obtain new tools which could then be actively used. However, this advice is only a part of more complete and self-consistent advice. This paper presents more complete advice which consists of three parts, of which the first is the advice already considered.

关键词： engineering education

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UNSUPERVISED MEASUREMENT OF BRAIN-TUMOR VOLUME ON MR-IMAGES

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JMRI-JOURNAL OF MAGNETIC RESONANCE IMAGING 1995年第5期5卷 594-605页

作者： VELTHUIZEN, RP CLARKE, LP PHUPHANICH, S HALL, LO BENSAID, AM ARRINGTON, JA GREENBERG, HM SILBIGER, ML Department of Radiology 12901 Bruce B Downs Blvd. MDC 17. University of South Florida Neuro-oncology Program. H. Lee Moffitt Cancer Center Tampa FL 33624 Department of Computer Science and Engineering. University of South Florida Tampa FL 33624

We examined unsupervised methods of segmentation of MR images of the brain for measuring tumor volume in response to treatment. Two clustering methods were used: fuzzy c-means and a nonfuzzy clustering algorithm, Results were compared with volume segmentations by two supervised methods, k-nearest neighbors and region growing, and all results were compared with manual labelings, Results of individual segmentations are presented as well as comparisons on the application of the different methods with 10 data sets of patients with brain tumors. Unsupervised segmentation is preferred for measuring tumor volumes in response to treatment, as it eliminates operator dependency and may be adequate for delineation of the target volume in radiation therapy. Some obstacles need to be overcome, in particular regarding the detection of anatomically relevant tissue classes. This study shows that these improvements are possible.

关键词： MR IMAGING TUMOR VOLUME SEGMENTATION PATTERN RECOGNITION CLUSTERING K-NEAREST NEIGHBORS

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All-Fiber Image-Rejection Receiver Front-End for Optical Communication Systems Using High-Birefringence and Polarizing Fibers

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Optical Fiber Technology 1995年第3期1.0卷 247-263页

作者： Chandra, Nilanjan Daut, David G. Department of Electrical and Computer Engineering Fiber Optics Materials Research Program Rutgers University Piscataway NJ 08855-0909 P.O. Box 909 United States

In this paper, we investigate in detail the conditions necessary for proper image-rejection operation and characterize the performance of a single detector, all-optical image-rejection mixer for use in heterodyne receivers. The principal component of the all-optical image-rejection receiver is a length of high-birefringence fiber. A polarizing fiber is also considered as an alternative to the high-birefringence fiber. The image-rejection performance is based on meeting certain required ideal conditions for polarization states of the desired and image channels. To study this, we examine, using the Stokes parameter approach, the evolution of certain figures of merit with distance in single-mode high-birefringence and polarizing fibers. Due to the nearness of the frequencies of the desired, image, and local oscillator (LO) signals, the mismatches from the ideal conditions are very small compared to the beat lengths. Therefore, there is negligible receiver error rate performance degradation. Our results indicate that this all-optical image-rejection receiver implementation is a robust device that is also highly insensitive to temperature variations. © 1995 Academic Press, Inc.

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A 590,000 transistor 48,000 pixel, contrast sensitive, edge enhancing, CMOS imager-silicon retina 16

A 590,000 transistor 48,000 pixel, contrast sensitive, edge ...

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16th Conference on Advanced Research in VLSI, ARVLSI 1995

作者： Andreou, A.G. Boahen, K.A. Department of Electrical and Computer Engineering Johns Hopkins University BaltimoreMD21218 United States CNS Program Caltech PasadenaCA91125 United States

We present an experimental analog VLSI focal plane processor for the phototransduction, local gain control and edge enhancement of natural images. The single chip system incorporates 590,000 transistors in 48,000 pixels, and it has been fabricated on a 9.5×9.3 mm die in a 1.2 μm n-well double metal, double poly, digital oriented CMOS technology. The organization of the system abstracts from the structure and function of the vertebrate distal retina. The adopted design style, current-mode subthreshold CMOS using circuits of minimal complexity offers the possibility of ultra low power dissipation and area efficiency, commensurate with VLSI integration. © 1995 IEEE.

关键词： Pixels

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Combined diagonal/Fourier preconditioning methods for image reconstruction in emission tomography

Combined diagonal/Fourier preconditioning methods for image ...

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IEEE International Conference on Image Processing

作者： S.D. Booth J.A. Fessler Bioengineering Program and Department of Electrical Engineering and Computer Science University of Michigan MI USA

Iterative methods for tomographic image reconstruction often converge slowly. Preconditioning methods can often accelerate gradient-based iterations. Previous preconditioning methods for PET reconstruction have used either diagonal or Fourier-based preconditioners. Fourier-based preconditioners are well suited to problems with near-circulant Hessian matrices. However, due to the nonuniform Poisson noise variance in PET, the circulant approximation to the Hessian is suboptimal. This paper shows that a particular combined diagonal/Fourier preconditioner yields a more accurate approximation to the Hessian and gives significantly faster convergence rates than does either preconditioner used alone.

关键词： Image reconstruction Tomography Character generation Symmetric matrices Equations Iterative methods Minimization methods Covariance matrix Spatial resolution Yield estimation

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Body surface derivative electrocardiographic mapping

Body surface derivative electrocardiographic mapping

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Bin He Department of Electrical Engineering and Computer Science and Bioengineering Program University of Illinois Chicago Chicago IL USA

ISBN: (纸本)0780324757

The authors have developed a new approach to imaging cardiac electrical activity by measuring and visualizing body surface distributions of the higher-order spatial derivative of the potential. Numerical algorithms have developed to construct body surface maps of the spatial derivative of the potential from potential data. computer simulation studies have been conducted to test the feasibility of this approach. Experimental exploration has also been made in healthy human subjects. The authors' experimental and theoretical studies indicate the superior performance of the body surface higher-order derivative electrocardiographic mapping for localizing and imaging spatially separated cardiac electrical sources.

关键词： Bioelectric phenomena Electric potential Electrodes Laplace equations computer simulation Helium Biomedical engineering Electric variables measurement Data visualization Testing

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A complex arithmetic digital signal processor using CORDIC rotators

A complex arithmetic digital signal processor using CORDIC r...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： S. Freeman M. O'Donnell Electrical Engineering and Computer Science Department and Bioengineering Program University of Michigan Ann Arbor MI USA

A versatile signal processor has been designed that can perform multiple rotations, multiplications and additions within one clock cycle. The computational elements of this processor include four pipelined CORDIC rotators, two pipelined fast multipliers and two adders. A combination of register files, SRAM, and ROM provides on chip storage for coefficients, running sums and program.. The chip architecture and its applicability to complex valued signal processing tasks are discussed.

关键词： Digital arithmetic Digital signal processors Signal processing Process design Signal design Clocks Adders Registers Random access memory Read only memory

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