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IEEE Symposium (IUS) Ultrasonics

作者： J.-U. Kluiwstra Y. Zhang P. VanBaren S.A. Strickberg E.S. Ebbini C.A. Cain Electrical Engineering and Computer Science Department And Bioengineering Program University of Michigan Ann Arbor MI USA

Catheter based ablation of cardiac tissue has been shown to provide an immediate and long lasting cure for cardiac arrhythmia. However, the procedure does not always allow placing the catheter in close proximity to the pathological tissues requiring ablation. Use of non-invasive focused ultrasound ablation in the moving heart is an attractive potential alternative to catheter based ablative therapy. In this paper, initial studies have been performed to explore the feasibility of using ultrasound phased array technology for this application. A 3-D treatment planning software package was developed to study the available acoustic windows allowing ultrasound to be focused on the myocardium. Numerical simulation studies of the feasibility of precise beam forming by propagating ultrasound around the ribs shows that the beam, even though formed by an irregularly shaped subset of phased array elements not blocked by ribs and air, was very sharply focused at the target. Using invasive phase aberration correction algorithms developed in the authors' lab, experiments with pork and human rib phantoms confirm the ability to precisely form beams with phased array through the available noncontiguous windows.

关键词： Phased arrays Ultrasonic imaging Myocardium Catheters Acoustic beams Ribs Cardiac tissue Pathology Heart Medical treatment

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THE ABSOLUTE VALUE OF THE CHERN-SIMONS-WITTEN INVARIANTS OF LENS SPACES

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JOURNAL OF KNOT THEORY AND ITS RAMIFICATIONS 1995年第2期4卷 319-327页

作者： YAMADA, SJ Department of Computer Science Kyoto Sangyo University Motoyama Kamigamo Kita-ku Kyoto 603 Japan Supported by Natural Science and Engineering Research Council of Canada (NSERC) International Fellowship Program.

An explicit formula for the absolute value of the Witten invariants is derived. We discuss the relation between homotopy equivalence and the absolute value of Witten invariants for lens spaces. We also give examples o... 详细信息

关键词： 3-DIMENSIONAL MANIFOLDS WITTEN INVARIANTS TURAEV-VIRO INVARIANTS LENS SPACES

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Comparison of phased array strategies for ultrasound surgery

Comparison of phased array strategies for ultrasound surgery

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IEEE Symposium (IUS) Ultrasonics

作者： Hong Wan P. VanBaren E. Ebbini C. Cain Bioengineering Program University of Michigan Ann Arbor MI USA Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

The possibility of using phased array generated multiple-focus patterns to reduce the overall treatment time in ultrasound surgery while restraining prefocal heating was investigated by simulating the performance of different possible schemes, i.e., single-focus scans, multiple-focus scans, and simultaneous multiple focusing without scanning, when used to "ablate" a 10/spl times/10/spl times/10 mm/sup 3/ volume 100 mm deep. In all cases, forty-one foci were used to cover the treatment volume. Multiple-focus scans were arranged into nine groups which were scanned in a raster fashion, as with single-focus scans. Keeping the treatment time constant, the maximum intensities, maximum thermal doses, dose distributions and prefocal heating zones for the different schemes were compared. It was found that the non-scanned simultaneous multiple-focus case required the smallest maximum intensity and dose, and resulted in the most even dose distribution. Single-focus raster scanning of individual lesions, as currently used with fixed-focus transducer, gave the worst results. These results show that multiple-focus patterns help considerably in reducing the maximum intensity and dose, and in generating a more even dose distribution assuming the same treatment time and prefocal heating. Alternatively they can be used to significantly reduce treatment time while keeping the maximum intensity and prefocal heating below predetermined limits.

关键词： Phased arrays Ultrasonic imaging Surgery Heat treatment Power generation Lesions Heat engines Cooling Biomedical engineering computer science

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2D large aperture ultrasound phased arrays for hyperthermia cancer therapy: design, fabrication and experimental results

2D large aperture ultrasound phased arrays for hyperthermia ...

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IEEE Symposium (IUS) Ultrasonics

作者： P. VanBaren J.-U. Kluiwstra R. Seip Y. Zhang E.S. Ebbini C.A. Cain Electrical Engineering and Computer Science Department University of Michigan Ann Arbor MI USA Bioengineering Program University of Michigan Ann Arbor MI USA

Ultrasound has proven to be an effective modality for inducing hyperthermia for cancer therapy because of the spatial control of the SAR that may be achieved. The use of phased-array ultrasound applicators provides additional benefits because the ultrasound field may be changed rapidly (at electronic speeds) and may be used to focus the field at several locations simultaneously. To obtain these qualities, large apertures with element counts exceeding several hundred are needed. However, with the increase in the number of elements, both the control and fabrication process involve greater complexity. Therefore the construction of phased array systems, especially those using geometric focusing to increase intensity gain, has proven technically difficult. In order to avoid complex machining and mounting procedures, a modular approach to array construction has been developed. To test this approach, phased arrays with 192 and 512 elements have been designed, fabricated and characterized in the authors' laboratory. These arrays are composed of flat panels arranged to approximate a spherically shaped aperture. Experimental acoustic measurements for both arrays are presented and compared with computer simulations, showing good agreement. In addition, experimental results using these arrays, in conjunction with a control algorithm developed in the authors' lab, to induce and maintain hyperthermia in in vivo canine thigh muscle are presented. These results demonstrate the flexibility of such applicators, and the control which they can achieve over the SAR field.

关键词： Phased arrays Apertures Ultrasonic imaging Hyperthermia Cancer Applicators Medical treatment Process control Fabrication Machining

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Identifying significant frequencies in surface EMG signals for localization of neuromuscular activity

Identifying significant frequencies in surface EMG signals f...

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

作者： E.F. LoPresti R.A. Jesinger V.L. Stonick Electrical and Computer Engineering Department and Biomedical hgineering Program Carnegie Mellon University PittSburgh PA USA School of Medicine University of Pittsburgh Pittsburgh PA USA

Presents two methods for determining significant frequencies in surface EMG recordings. In the first method, time-frequency distributions (TFDs) are analyzed to determine the ten most powerful frequencies (over time). The TFD frequencies are further analyzed using a "cyclostationary" approach. In the second method, AR modeling is used to evaluate how significant spectral components in the surface EMG signals change over time. These methods are important for identifying significant spectral components in multichannel surface EMG recording so that these excitations can be localized within the muscle.

关键词： Frequency Electromyography Signal processing Neuromuscular Muscles Electrodes Biomedical measurements Medical diagnostic imaging Biomedical computing Power engineering computing

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Body surface Laplacian mapping of ventricular depolarization from potential recordings in humans

Body surface Laplacian mapping of ventricular depolarization...

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

作者： M. O'Hara X. Yu N. Mehdi C. Schwartz D. Wu B. Avitall B. He Bioeng. Program Illinois Univ. Chicago IL USA Department of Electrical Engineering and Computer Science University of Illinois Chicago Bioengineering Program University of Illinois Chicago Department of Medicine University of Illinois Chicago

We investigated the feasibility of obtaining body surface Laplacian maps (BSLMs) from unipolar electrocardiographic recordings in humans. The overall pattern of the BSLMs during ventricular depolarization is reproducible for subjects examined and for multiple sets of maps within a single subject. Right and left ventricular activities are well resolved in the BSLMs over the anterior chest as compared with body surface potential maps (BSPMs). Our experimental results demonstrate the feasibility of performing body surface Laplacian electrocardiographic mapping from potential recordings. The effects of measurement noise and electrode position uncertainty on the Laplacian derivation were also evaluated by computer simulation.

关键词： Laplace equations Humans Electrodes Bioelectric phenomena Electric potential computer simulation Position measurement Noise measurement Signal processing Gaussian noise

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Shape from motion decomposition as a learning approach for autonomous agents

Shape from motion decomposition as a learning approach for a...

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IEEE International Conference on Systems, Man and Cybernetics

作者： R.M. Voyles J.D. Morrow P.K. Khosla Robotics Ph.D. Program Carnegie Mellon University Pittsburgh PA USA Department of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh PA USA

This paper explores shape from motion decomposition as a learning tool for autonomous agents. Shape from motion is a process through which an agent learns the "shape" of some interaction with the world by imparting motion through some subspace of the world. The technique applies singular value decomposition to observations of the motion to extract the eigenvectors. The authors show how shape from motion applied to a fingertip force sensor "learns" a more precise calibration matrix with less effort than traditional least squares approaches. The authors also demonstrate primordial learning on a primitive "infant" mobile robot.

关键词： Shape Calibration computer vision Force sensors Matrix decomposition Autonomous agents Ontologies Singular value decomposition Robustness Principal component analysis

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Vision and force driven sensorimotor primitives for robotic assembly skills

Vision and force driven sensorimotor primitives for robotic ...

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Proceedings 1995 IEEE/RSJ International Conference on Intelligent Robots and Systems. Human Robot Interaction and Cooperative Robots

作者： J.D. Morrow B.J. Nelson P.K. Khosla Robotics Ph.D. Program Carnegie Mellon University Pittsburgh PA USA Department of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh PA USA

Integrating sensors into robot systems is an important step towards increasing the flexibility of robotic manufacturing systems. Current sensor integration is largely task-specific which hinders flexibility. The authors are developing a sensorimotor command layer that encapsulates useful combinations of sensing and action which can be applied to many tasks within a domain. The sensorimotor commands provide a higher-level in which to terminate task strategy plans, which eases the development of sensor-driven robot program.. This paper reports on the development of both force and vision driven commands which are successfully applied to two different connector insertion experiments.

关键词： Force sensors Robotic assembly Robot sensing systems Robot program.ing Connectors Libraries computer aided manufacturing Sensor systems Manufacturing systems Robot vision systems

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Tactile gestures for human/robot interaction

Tactile gestures for human/robot interaction

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Proceedings 1995 IEEE/RSJ International Conference on Intelligent Robots and Systems. Human Robot Interaction and Cooperative Robots

作者： R.M. Voyles P.K. Khosla Robotics Ph.D. Program Carnegie Mellon University Pittsburgh PA USA Department of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh PA USA

Gesture-based program.ing is a new paradigm to ease the burden of program.ing robots. By tapping in to the user's wealth of experience with contact transitions, compliance, uncertainty and operations sequencing, we hope to provide a more intuitive program.ing environment for complex, real-world tasks based on the expressiveness of nonverbal communication. A requirement for this to be accomplished is the ability to interpret gestures to infer the intentions behind them. As a first step toward this goal, this paper presents an application of distributed perception for inferring a user's intentions by observing tactile gestures. These gestures consist of sparse, inexact, physical "nudges" applied to the robot's end effector for the purpose of modifying its trajectory in free space. A set of independent agents-each with its own local, fuzzified, heuristic model of a particular trajectory parameter observes data from a wristforce/torque sensor to evaluate the gestures. The agents then independently determine the confidence of their respective findings and distributed arbitration resolves the interpretation through voting.

关键词： Human robot interaction Robot sensing systems Robot program.ing Educational robots Painting Spraying Education Voting Service robots Fixtures

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A Model For The Relative Environmental Stability Of A Series Of Polyimide Capacitance Humidity Sensors

A Model For The Relative Environmental Stability Of A Series...

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International Conference on Solid State Sensors and Actuators (TRANSDUCERS)

作者： A.R.K. Ralston C.F. Klein P.E. Thomas D.D. Denton Central Research Johnson Controls Inc. Milwaukee WI USA Materials Science Program Department of Electrical and Computer Engineering and Department of Chemistry University of Wisconsin Madison Madison WI USA

A capacitance humidity sensor is used as a test de- vice to characterize the performance of thirteen polyimide films in relative humidity sensing applications. This sensor has a multilayer, free-standing film construction. It consists of a humidity sensitive polyinfide dielectric core and conductive layers consisting of carbon filled polysul- fone on each side of the polyimide film to form a capacitor. Thirteen polyimide films, including commercial polyimides and films of novel chemistry, are investigated to determine the long term stability of sensors using the films exposed to 85'C/85% RH for a total of 28 days. Differences in film chemistry are used to interpret trends in the environmental stability of the films.

关键词： Stability Polyimides Capacitance Humidity Sensor phenomena and characterization Chemical sensors Chemistry Capacitive sensors Aging Conductive films

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