Potts models with magnetic field: Arithmetic,geometry, and computation

We give a sheaf theoretic interpretation of Potts models with external magnetic field, in terms of constructible sheaves and their Euler characteristics. We show that the polynomial countability question for the hypersurfaces defined by the vanishing of the partition function is affected by changes in the magnetic field: elementary examples suffice to see non-polynomially countable cases that become polynomially countable after a perturbation of the magnetic field. The same recursive formula for the Grothendieck classes, under edge-doubling operations, holds as in the case without magnetic field, but the closed formulae for specific examples like banana graphs differ in the presence of magnetic field. We give examples of computation of the Euler characteristic with compact support, for the set of real zeros, and find a similar exponential growth with the size of the graph. This can be viewed as a measure of topological and algorithmic complexity. We also consider the computational complexity question for evaluations of the polynomial, and show both tractable and NP-hard examples, using dynamic programming.     

彩色AC-PDP运动图像仿真系统的开发

开发了彩色AC-PDP运动图像仿真系统,通过利用本系统的运动图像仿真功能可以对现有的各种显示技术、与子场有关的各种因素进行仿真及比较,为人们开发提高彩色AC-PDP图像显示质量的新型技术及子场提供了理论上的依据;通过利用本系统的Gamma特性研究功能可以对彩色AC-PDP中视频信号的反Gamma特性进行研究,并对反Gamma相关编码进行子场逼近,为选择符合要求的子场编码提供了判据.     

低温送风系统末端装置诱导器的研究及性能评价

研究了在低温送风系统中诱导器(IDU)的结构特点、工作原理、送风方式,分析了诱导器送风口射流速度的特性,得出了诱导器空调系统的优缺点。     

目标RCS动态数据的分布特征研究

复杂目标在不同视向的RCS分布特征是不同的，传统模型对此都没有给出详细的结果。文中以某歼击机和直升机为对象，应用X^2。分布、对数正态分布和瑞利分布模型，以及Kolmogomv拟合优度检验方法，研究其RCS动态测量数据的统计分布特征，得到了在一定显著性水平下，两种目标在不同视向角下对三种模型的拟合效果，同时得到应用X^2。分布拟合时模型半自由度随视向角的分布情况。在显著性水平为0．05时，对于在较短时间内录得的复杂目标动态RCS数据，应用X^2分布可以取得较好的拟合效果。文中结果精确地描述了目标RCS的起伏特征，能够为目标回波的精确模拟与检测提供可靠的依据。     

一种联合信源信道匹配的视频传输方法

介绍了一种实现联合信源-信道编码的通用的新方法—联合信源-信道匹配。该方法思想巧妙,通过将有限的通信系统资源在信源和信道编码器之间进行巧妙合理的分配,从而获得最优的系统整体传输性能。并且,该方法并不仅局限于特定的信源-信道编码器对,可适用于任何一种信源-信道编码器对共享有限系统资源的情况,具有很好的通用性。仿真实验证明了JSCM通用视频传输系统能获得比传统的固定码率分配系统更高的整体性能增益。     

Invariants of Characteristics of Some Systems of Partial Differential Equations

We introduce the notion of an invariant of characteristics for a system of first-order partial differential equations. We prove that the existence of invariants is connected with passiveness of some systems. We describe a few methods for construction of new invariants from those already known. We give a scheme for application of the invariants to reduction and integration of systems of partial differential equations. As an application we consider the equation of gas dynamics.     

Analysis of S-SEED''s characteristics in optical switch

This article introduces the basic structure of a symmetric self-electrooptic effect device （S-SEED）, and applies the Kirchoff＇ s current law and a purely equivalent capacitive model, to analyze S-SEED＇s switch characteristics. Linear approximation and N-segment approximation are utilized to obtain S-SEED＇s voltage-time （V-T） and characteristics. Theoretical analysis is verified by simulations, and the results demonstrate that the precision of S-SEED＇s switch time can satisfy the requirement in applications with linear approximation. Moreover, the simulations compare S-SEED＇s switch characteristics with different input powers and input contrast ratios, which reveal that increasing input contrast ratio is an effective way to improve S-SEED＇s switch characteristics.     

Negative luminescence from mid-wave infrared HgCdTe diode arrays

A self-referencing, optical modulation technique was used to measure the negative luminescence efficiencies of an array of mid-wave infrared HgCdTe photodiodes with cutoff wavelength 4.6 μm as a function of sample temperature. The internal efficiency at a wavelength of 4 μm was 93% at 295 K, and nearly independent of temperature in the 240–300 K range. This corresponds to an apparent temperature reduction >50 K at room temperature and >30 K at 240 K. Moreover, the reverse-bias saturation current density was only 0.13 A/cm². The measured transmission and emission spectra were simulated using empirical HgCdTe absorption formulas from the literature.     

Investigation of thin-film electroluminescent structures on rough subsrates

Results of experimental investigations of the volt-brightness characteristics, frequency dependences of brightness, and the directional radiation pattern of electroluminescent MSDM, MSCM, and MSDCM emitters, where M stands for the first transparent and second nontransparent electrodes, S is a semiconductor, D is a thin-film dielectric, and C is a silicone-based composite liquid dielectric with a powdered segnetoelectric filler, developed on conventional “smooth” and rough glass substrates are presented. It is shown that electroluminescent structures on rough surfaces have a brightness approximately two times higher than that of similar structures developed on a “smooth” substrate. Ul’yanovsk State University, 42, L. Tolstoi St., Ul’yanovsk, 432700, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 507–512, July–August, 1997.     

非线性控制系统的最小实现

对于那些由代数微分方程描述的具有输入输出关系的非线性控制系统，本文采用两种方法讨论了其最小实现问题：一种方法是直接计算系统的特征列；另一种方法则采用了本原元定理．两种方法给出的最小实现所需的状态变量最小数目是相等的．文中的大量代数与微分运算则可利用数学机械化来完成