A unique and accurate approach for modeling semiconductor device characteristics and estimating IC parametric yield is described. Multilayer perceptron neural networks (MLPNN) are trained using error back propagation ...
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A unique and accurate approach for modeling semiconductor device characteristics and estimating IC parametric yield is described. Multilayer perceptron neural networks (MLPNN) are trained using error back propagation to model DC device characteristics measured at the final fabrication stage. Measurements of material and/or device characteristics taken at earlier fabrication stages are used to develop neural network models of the final DC parameters. A very good agreement has been found between the actual measurements and the MLPNN modeled parameters, and the resulting yield estimations are in excellent agreement with the actual yield.
Presents a new distorted Born iterative algorithm for diffraction tomography which introduces kernel distortions only at carefully selected pixel locations. This algorithm attains the performance levels achieved by ex...
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Presents a new distorted Born iterative algorithm for diffraction tomography which introduces kernel distortions only at carefully selected pixel locations. This algorithm attains the performance levels achieved by existing distorted Born iterative techniques, while maintaining the robustness of the Born iterative technique, especially in noisy situations. In addition, the algorithm has lower computational complexity and faster convergence rate when compared with existing distorted Born iterative algorithms. The authors present numerical simulations of the algorithm in noisy and noise-free environments. They also discuss an elementary experimental setup which is being used to validate their tomographic imaging algorithms.
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 d...
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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.
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 ad...
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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.
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...
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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 of arbitrarily finitely many lens spaces which have the same Witten invariants for any level r.
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 reproduci...
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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.
Tissue elasticity can be estimated from displacement and strain images acquired under controlled deformation. We extend this approach for coronary arteries, deformed and imaged by an integrated angioplasty balloon and...
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Tissue elasticity can be estimated from displacement and strain images acquired under controlled deformation. We extend this approach for coronary arteries, deformed and imaged by an integrated angioplasty balloon and ultrasonic imaging probe. Because the lumen cross section of a severely occluded artery is generally not circular, we have also developed a technique to perform all motion computations in the reference frame of the lumen's geometric center. This coordinate system is independent of the imaging catheter, and consequently referencing to this frame removes artifacts associated with probe motion within the balloon during deformation. Displacements and strains estimated by phase-sensitive correlation-based speckle tracking were used to distinguish arterial plaques in simulated coronary arteries of differing elastic moduli: hard, soft, and homogenous. We have also applied these methods to images of a homogeneous gelatin phantom collected with the integrated probe. The spatial dependence of these quantities shows good agreement with theoretically predicted values.
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 construc...
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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.
The characterization of microemboli located in whole blood is attempted by determining the Legendre coefficients of phase function from the scattered light distribution around the medium. In the radiative transport eq...
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The characterization of microemboli located in whole blood is attempted by determining the Legendre coefficients of phase function from the scattered light distribution around the medium. In the radiative transport equation, a microembolus is represented as a secondary source and assumed to have a spherical form and the first order transport approximate solution of the equation is used to describe the scattered intensity distribution. After the scattered intensities are determined at the surfaces of the medium, the orthogonal property of Legendre polynomial is used to extract the coefficients out of the intensities. From the obtained coefficients, the size and complex index of refraction of microemboli are determined.
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