In a previous paper[1] we described the use of a bus impedance matrix approach for determining the signal strength of distribution line carrier signals. The technique used bus impedance matrices to calculate transimpe...
详细信息
In a previous paper[1] we described the use of a bus impedance matrix approach for determining the signal strength of distribution line carrier signals. The technique used bus impedance matrices to calculate transimpedances which are the ratios of the voltage at any point on the line to the current injected at any point on the line. In the current paper we apply sensitivity analysis to this bus impedance approach and show how simply new transimpedances can be obtained from the original values when changes in the distribution line are made.
The inverse problem of reconstructing the resistivity of the earth, varying both laterally and with depth, from direct current measurements is considered. The problem is formulated as a multidimensional inverse scatte...
详细信息
The inverse problem of reconstructing the resistivity of the earth, varying both laterally and with depth, from direct current measurements is considered. The problem is formulated as a multidimensional inverse scattering problem and solved using a layer stripping algorithm. This algorithm recursively reconstructs the resistivity and electrical potential on horizontal planes of increasing depth by downward continuation. This is the first exact solution to the inverse resistivity problem for resistivity varying laterally as well as with depth. The algorithm is an extension of an algorithm proposed by Levy for resistivity varying in one dimension.
A fast algorithm for recovering profiles of density and compressional (P) and shear-vertical (SV) wave speeds as functions of depth for the inverse seismic problem in a continuous layered elastic medium is obtained. T...
详细信息
A fast algorithm for recovering profiles of density and compressional (P) and shear-vertical (SV) wave speeds as functions of depth for the inverse seismic problem in a continuous layered elastic medium is obtained. This algorithm differs from previous fast algorithms for this problem since it requires only the compressional wave P-P reflection response at the surface of the medium, for three different slownesses or angles of incidence. Previous algorithms have required shear stress data in the form of the P-SV and SV-SV reflection responses, making them unsuitable for an ocean environment. This algorithm is thus much more suitable for reconstructing the ocean floor from pressure data taken in the ocean. The algorithm is exact, and it includes the effects of multiple reflections and mode conversions. A computer run illustrates the performance of the algorithm on synthetic data.
The phase reconstruction problem in the trispectrum domain is addressed in this correspondence. In particular, three different reconstruction algorithms are discussed and their performance is evaluated. The first two ...
详细信息
The phase reconstruction problem in the trispectrum domain is addressed in this correspondence. In particular, three different reconstruction algorithms are discussed and their performance is evaluated. The first two algorithms are recursive in nature and are shown to be sensitive to initial condition estimates.
In computerized tomography, certain type of artifacts can be detected if the consistency of the reconstruction is checked using the available information. A reconstructed image is said to be consistent if it satisfies...
详细信息
The three‐dimensional Schr?dinger equationinverse scattering problem is solved using an orthogonalization approach. The plane waves propagating in free space are orthogonalized with respect to an inner product define...
详细信息
The three‐dimensional Schr?dinger equationinverse scattering problem is solved using an orthogonalization approach. The plane waves propagating in free space are orthogonalized with respect to an inner product defined in terms of a Jost operator. The resulting integral equation is identical to the generalized Gel’fand–Levitan equation of Newton, although the present derivation is simpler and more physical than that of Newton. Newton’s generalized Marchenko equation is derived from the defining integral equation for the Jost operator. These integral equations are shown to be solved by fast algorithms derived directly from the properties of their solutions. This paper thus presents a simple interpretation of Newton’s two integral equations, two fast algorithms for solving these integral equations, and relations between the various approaches. This is a generalization of previously obtained results, which are also reviewed here, for the one‐dimensional inverse scattering problem.
This paper introduces a new method of analysis for Delta-Sigma Modulators based on modeling the nonlinear quantizer with a linerized gain, obtained by minimizing a mean-square-error criterion[7], followed by an additi...
详细信息
This paper introduces a new method of analysis for Delta-Sigma Modulators based on modeling the nonlinear quantizer with a linerized gain, obtained by minimizing a mean-square-error criterion[7], followed by an additive noise source representing distortion components. In the paper, input-signal amplitude dependencies of Delta-Sigma Modulator stability and signal to noise ratio are analyzed. It is shown that due to the nonlinearity of the quantizer, the signal-to-noise ratio of the modulator may decrease as the input amplitude increases prior to saturation. Also, a stable third-order Delta-Sigma Modulator may become unstable by increasing the input amplitude beyond a certain threshold. Both of these phenomenon are explained by the nonlinear analysis of this paper. The analysis is carried out sinusoidal excitations.
A new segmentation method based on the properties of the human visual system is described in this paper. The segmentation method is part of a new second generation image coder. In addition, one of the properties is th...
详细信息
A new segmentation method based on the properties of the human visual system is described in this paper. The segmentation method is part of a new second generation image coder. In addition, one of the properties is that it is not necessary to transmit (or store) the visual residual for use in reconstructing the received signal. It is assumed that the characteristics of this visual residual are known at the receiver and can be used in the reconstruction process.
Recently, ways to obtain a new generation of image-coding techniques have been proposed. The incorporation of the human visual system (HVS) models and tools of the image analysis, such as segmentation, are two definin...
详细信息
Recently, ways to obtain a new generation of image-coding techniques have been proposed. The incorporation of the human visual system (HVS) models and tools of the image analysis, such as segmentation, are two defining features of these techniques. In this paper, a new image coding technique is presented which utilizes a human visual system model and a image analysis criteria together with the technique of projection onto convex sets (POCS). The human visual system model is used to determine the most probable perceptual information of an image and the removal of irrelevant information. The projection onto convex sets operation is used as a restoration technique aimed at correcting the degradations caused by the conventional coders in the transmitter part of the channel. And finally, the image analysis based technique is used as an interpolator in order to predict the unknown regions of the received image. This new technique can be used in single frame image coding applications to obtain acceptable images at extremely high compression rates.
A planar or quadric surface can be fit to a segment of range data in a locally optimal sense by selecting the minimum eigensolution of a scatter matrix for that segment. We obtain a globally optimal fit by perturbing ...
详细信息
A planar or quadric surface can be fit to a segment of range data in a locally optimal sense by selecting the minimum eigensolution of a scatter matrix for that segment. We obtain a globally optimal fit by perturbing the local eigensystems with constraints reflecting relations among the corresponding primitives of a model. These pairwise relations define a view-invariant description of the model. For segments containing a few hundred pixels, the resulting perturbation is small enough to justify a linear treatment of the coupled system. From this globally optimal fit, we determine the pose of the object algebraically.
暂无评论