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131.
解线性及二次型规划问题增广的神经网络 总被引:3,自引:1,他引:2
本文提出了一个解线性及二次型规划问题的神经网络模型,证明了该网络是全局稳定于平衡点,而平衡点就是线性及二次型规划问题的解,该网络的优点是能够实时获得问题的精确解,且可以同时获得带等式不式约束的对偶问题解,该网络易于电路实现。 相似文献
132.
Tzong-Lin Wu Hung-Chun Chang 《Lightwave Technology, Journal of》1995,13(9):1926-1934
Based on vectorial formulations which combine the surface integral equation method and the finite-element method, a novel numerical approach is proposed for calculating the dispersion coefficients of dual-mode elliptical-core fibers with arbitrary refractive index profiles. By differentiating the original formulations involving the propagation constant β and the guided mode fields Hx and Hy once and twice with respect to the normalized frequency V, the new formulations for {dβ/dV, dHx/dV, dHy/dV} and for {d2β/dV2, d2 Hx/dV2, d2Hy/dV2 } are obtained respectively. Once {β, Hx, Hy } is solved through the eigenvalue procedure which dominates the computing time, only a few matrix manipulations are required to obtain {dβ/dV, dHx/dV, dHy/dV} and {d2β/dV2, d2Hx/dV2 , d2Hy/dV2}. Some numerical examples are examined to see the influence of different refractive index distributions with dips on the dispersions of the four nondegenerate LP 11 modes for elliptical-core fibers 相似文献
133.
A new simplified threshold-voltage model for n-MOSFETs with nonuniformly doped substrate and its application to MOSFET's miniaturization 总被引:1,自引:0,他引:1
Jiin-Jang Maa Ching-Yuan Wu 《Electron Devices, IEEE Transactions on》1995,42(8):1487-1494
The formulation, verification, and application of a new simplified 2-D threshold voltage model for n-MOSFETs with nonuniformly doped substrate profile are provided, in which the averaged normal field at the Si/SiO/sub 2/ interface in the active channel is quoted from a simplified solution of two-dimensional Poisson equation using the Green function technique. Starting with the expression of this average normal field, a simple threshold-voltage model for short-channel n-MOSFETs with nonuniformly doped substrate profile is explicitly expressed in terms of device structures and terminal voltages by considering parabolic source-drain boundary potentials. Moreover, the effects of the junction depth on the threshold voltage are examined in detail. It is shown that the DIBL effect cannot be completely eliminated by simply increasing the substrate doping concentration. Comparisons among developed model, 2-D numerical analysis, and experimental data have been made and the accuracy of the developed analytical model has been verified. In addition, a direct extension of our model to the case of uniformly doped substrates leads to a new constraint equation for device miniaturization.<> 相似文献
134.
器件尺寸按比例缩小是实现超大规模集成电路的有效途径,但寄生和二级效应却将器件限在一定的水平,本文在对比分析常温与低温下小尺寸器件效应的基础上,重点研究了MOS器件亚阈特性对器件性能及按比例缩小的影响,并根据低温工作的特点,提出了MOS器件一种低温按比例缩小规则,该原则对低温器的优化设计,从而更大程度在提高电路与系统性能具有重要的指导意义。 相似文献
135.
A new millimeter-wave omnidirectional dielectric rod metallic grating antenna is investigated theoretically and experimentally, in this paper. The radiation characteristics of the antenna are carefully investigated by a rigorous formulation for the TE01-mode and TM01-mode excitation in the Ka-band frequency range. Based on the analysis, an omnidirectional antenna excited by the TE01 mode is designed and measured. The measured results are compared with theoretical predictions and good agreement is found. Extensive numerical results are given to establish some useful guidelines for the design of the omnidirectional antenna 相似文献
136.
137.
The Hawking radiation of Dirac particles in an arbitrarily rectilinearly accelerating Kinnersley black hole with electromagnetic charge and cosmological constant is investigated by using the generalized tortoise coordinate transformation. Both the location and the temperature of the event horizon depend on the time and the polar angle. The Hawking thermal radiation spectrum of Dirac particles is also derived. 相似文献
138.
139.
Dagan Feng Koon-Pong Wong Chi-Ming Wu Wan-Chi Siu 《IEEE transactions on information technology in biomedicine》1997,1(4):243-254
Positron emission tomography (PET) is an important tool for enabling quantification of human brain function. However, quantitative studies using tracer kinetic modeling require the measurement of the tracer time-activity curve in plasma (PTAC) as the model input function. It is widely believed that the insertion of arterial lines and the subsequent collection and processing of the biomedical signal sampled from the arterial blood are not compatible with the practice of clinical PET, as it is invasive and exposes personnel to the risks associated with the handling of patient blood and radiation dose. Therefore, it is of interest to develop practical noninvasive measurement techniques for tracer kinetic modeling with PET. In this paper, a technique is proposed to extract the input function together with the physiological parameters from the brain dynamic images alone. The identifiability of this method is tested rigorously by using Monte Carlo simulation. The results show that the proposed method is able to quantify all the required parameters by using the information obtained from two or more regions of interest (ROIs) with very different dynamics in the PET dynamic images. There is no significant improvement in parameter estimation for the local cerebral metabolic rate of glucose (LCMRGlc) if there are more than three ROIs. The proposed method can provide very reliable estimation of LCMRGlc, which is our primary interest in this study 相似文献
140.
测量了Cr^4+,YAG、Cr^4+,Mg2SiO4晶体在室温和液氮温度下的荧光光谱,吸收光谱和激发态寿命,讨论了温度变化时,两种晶体中Cr^4+近红外辐射积分强度变化与激光发态寿命变化的关系,得出结论:在77K ̄300K范围内,Cr^4+的^3T2能级荧光辐射截面本身受温度影响不大,Cr^4+辐射荧光的变化,主要是由无辐射弛豫速率随温度变化而引起的。 相似文献