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61.
P. A. Stubberud E. Awad J. W. Adams C. T. Leondes 《Journal of Optimization Theory and Applications》1993,79(2):253-272
Many digital signal processing applications require linear phase filtering. For applications that require narrow-band linear phase filtering, frequency sampling filters can implement linear phase filters more efficiently than the commonly used direct convolution filter. In this paper, a technique is developed for designing linear phase frequency sampling filters. A frequency sampling filter approximates a desired frequency response by interpolating a frequency response through a set of frequency samples taken from the desired frequency response. Although the frequency response of a frequency sampling filter passes through the frequency samples, the frequency response may not be well behaved between the specific samples. Linear programming is commonly used to control the interpolation errors between frequency samples. The design method developed in this paper controls the interpolation errors between frequency samples by minimizing the mean square error between the desired and actual frequency responses in the stopband and passband. This design method describes the frequency sampling filter design problem as a constrained optimization problem which is solved using the Lagrange multiplier optimization method. This results in a set of linear equations which when solved determine the filter's coefficients.This work was partially funded by The National Supercomputing Center for Energy and the Environment, University of Nevada Las Vegas, Las Vegas, Nevada and by NSF Grant MIP-9200581. 相似文献
62.
63.
Mark J. Ablowitz Gino Biondini Sarbarish Chakravarty Rudy L. Horne 《Optics Communications》1998,150(1-6):305-318
Collision-induced timing shifts in a wavelength-division multiplexed soliton system are computed when damping, amplification, filtering and positive dispersion management following the loss profile are included. A statistical analysis is presented which takes into account the resulting effect of the large number of collisions occurring in the fiber. Analytic expressions are derived for the root mean square timing jitter and the maximum length of error-free transmission with an arbitrary number of channels. An extensive analysis of system performance corresponding to situations with and without filters and/or dispersion management is carried out. 相似文献
64.
The annular binary pupil filters consist of two transparent annuli obstructed by an annular mask. The optical transfer functions for them are analytically derived under paraxial approximation, and three- and two- as well as one-dimensional numerical plots are presented. It is shown that by changing the parameters of transparent regions it is possible to improve the axial resolution whilst the transverse resolution remains unchanged, compared with an annular lens. Results indicate, as is well known, that this kind of filters can be applied to three-dimensional confocal microscopy. 相似文献
65.
In this paper, the issue of optimal defuzzification which is advocated in the Optimality Principle of Defuzzification (Song and Leland (1996)) is addressed. It was shown that defuzzification can be treated as a mapping from a high dimensional space to the real line. When system performance indices are considered, the defuzzification mapping which optimizes the performance indices for the given fuzzy sets is known as the optimal defuzzification mapping. Thus, finding this optimal defuzzification mapping becomes the essence of defuzzification. The problem with this idea, however, is that the space formed by all possible continuous defuzzification mappings is so large to search that the only recourse is an approximation to the optimal defuzzification mapping. With this, learning algorithms can be devised to find the optimal parameters of defuzzifiers with fixed structures. The proposed method is rigorously examined and compared with some well-known defuzzification methods. To overcome the resultant enormous computational load problem with this algorithm, the concept of defuzzification filter is additionally proposed. An application of the method to the power system stabilization problem is presented. 相似文献
66.
ZENG Dingli XIE Shizhong SUN ChengchengMAO Weiming ZHOU Bingkun 《Chinese Journal of Lasers》1997,6(6):499-505
DesignandCharacterizationofNovelCombFiltersBasedonPeriodicalFiberBraggGratingsZENGDingliXIEShizhongSUNChengchengMAOWeimingZHO... 相似文献
67.
A method to design a corrugated optical waveguide filter by modulating the corrugation width profile is proposed. This method is based on combined applications of the Fourier transformation and the F-matrix formalism. The method achieves the spatial profile of the corrugation width required to design a filter with any specified spectral profile of the reflection coefficient. The idea of the technique is that the spatial variation of the effective refractive index can be transformed, with the help of the F-matrix formalism, to variation of the corrugation width while maintaining a constant amplitude of the refractive index variation. Two examples are given applying the technique to the design of optical waveguide filters with reflectivity profiles of two- and four-rejection bands. 相似文献
68.
Non-linear rank order and morphological filtering can be achieved in optical-digital processors. In these processors, all convolutions are performed in inherently parallel optical correlators. Arithmetic and logic operations are made digitally. Due to the threshold decomposition concept, grey scale images are sequentially treated slice by slice. The optical-digital method of local histogram calculation within both binary and weighted neighbourhoods allows local non-linear operations. We derive rank order and morphological filters from optically calculated convolutions. Several configurations of optical convolvers are discussed. Further improvements in the technology of spatial light modulators and encoded light sources are needed before these processors' practical uses will appear. 相似文献
69.
70.
本文提出了一种彩色图像相减的新方法.该方法利用互相错动半个周期的两组三色光栅,在黑白底片上分别对待处理的两幅图像进行一次编码记录,然后在白光处理器上对黑白编码片进行彩色译码,即可实现彩色图像的强度相减,文中讨论了三色光栅实时生成和两组三色光栅条纹自动错动半个周期的方法,并给出了实验结果。 相似文献