基于动态规划的红外弱小运动目标的实时检测方法研究

文章针对低信噪比下红外弱小运动目标的特点,提出了一种正向动态规划算法。分析了算法的检测性能,并对算法实现中的一些关键问题进行了讨论。实验表明,该算法适应性强,能有效地完成对低信噪比下弱小运动目标的实时检测、识别与跟踪。     

矩阵分解的多变量模型参考自适应控制

研究了基于高频增益矩阵分解的多变量模型参考自适应控制 .为此首先基于矩阵分解构造出新的参数化方程 ,选取必然等价自适应控制律 .然后 ,引入规范化信号和类Lyapunov函数 ,获得了规范化自适应律 .并进一步给出了虚拟规范化信号的有用性质 .最后 ,严格地给出了闭环系统的稳定性和收敛性分析     

Using mega-fuzzification and data trend estimation in small data set learning for early FMS scheduling knowledge

Provided with plenty of data (experience), data mining techniques are widely used to extract suitable management skills from the data. Nevertheless, in the early stages of a manufacturing system, only rare data can be obtained, and built scheduling knowledge is usually fragile. Using small data sets, this research's purpose is improving the accuracy of machine learning for flexible manufacturing system (FMS) scheduling. The study develops a data trend estimation technique and combines it with mega-fuzzification and adaptive-network-based fuzzy inference systems (ANFIS). The results of the simulated FMS scheduling problem indicate that learning accuracy can be significantly improved using the proposed method involving a very small data set.     

Flow boiling in small diameter channels

Many studies have been carried out on two-phase flow heat transfer in channels with hydraulic diameter bigger than 6 mm, but relatively little work has been done for small diameter channels in the meso and compact range (diameter from 0.1 to 3 mm). The use of exchangers with small channels in refrigeration units, which are very numerous besides, could bring a significant reduction of the internal volume of the exchanger, and therefore diminish the refrigerant charge of the whole refrigerating system. One can imagine the interest to widen knowledge on the flow and the heat transfer in small-diameter tubes. This paper examine the thermal behavior of refrigerants boiling in small pipes. The correlations available for in-tube evaporation heat transfer coefficient are discussed and evaluated, when possible, and new research areas of relevance than can contribute to expand the use of small-diameter channels evaporators in refrigeration units are suggested.     

Analysis of the mechanical performance of a cardiovascular stent design based on micromechanical modelling

Stents are very commonly used in the treatment of coronary heart disease. They are permanent vascular support structures that offer a preferred alternative to bypass surgery in certain situations. The purpose of this work is to examine the mechanical behaviour of a stainless steel balloon expandable stent design using computational micromechanics in the context of the finite element method. Deployment and cardiac pulsing loading conditions are considered. Classical phenomenological plasticity theory (J₂ flow theory) and physically based crystal plasticity theory are used to describe the stent material behaviour. Parametric studies are carried out using both constitutive theories with a view to determining important stent deployment characteristics such as recoil and foreshortening. Comparisons of the results obtained using both theories illustrate differences, with the crystal plasticity theory models showing closer agreement to published performance data. The implications of this for stent design are discussed.     

A fully Bayesian approach for combining multilevel failure information in fault tree quantification and optimal follow-on resource allocation

This paper presents a fully Bayesian approach that simultaneously combines non-overlapping (in time) basic event and higher-level event failure data in fault tree quantification. Such higher-level data often correspond to train, subsystem or system failure events. The fully Bayesian approach also automatically propagates the highest-level data to lower levels in the fault tree. A simple example illustrates our approach. The optimal allocation of resources for collecting additional data from a choice of different level events is also presented. The optimization is achieved using a genetic algorithm.     

Predicting Organizational Success within a Project-Based Joint Venture Alliance

Project-based joint ventures (a special type of alliance) are an often-used method to form competitive organizational structures in the global market; they allow participants to quickly assemble project-needed assets on a short-term basis without substantial investment. However, published discussions of joint ventures describe mixed success and focus on factors that affect the ventures after they are formed. This paper exposes factors, which may be observed at joint venture inception, that are predictive of organizational success within the joint venture. The survey research of U.S. architecture/engineering/construction (A/E/C) firms indicates that smaller partners in a joint venture experience more market growth and are more successful. Also, a firm with strength in legitimacy (client trust) is more likely to gain in short-term income but will likely suffer some long-term market loss in comparison to its less-legitimized partners. It is further concluded that culture match among partners plays a significant role in ensuring profitable joint venture returns.     

A comparison between classical robust stability conditions

The paper is focused on the comparison between some classical robust stability conditions for continuous‐time linear time‐invariant systems. Such conditions are given as lemmas in the paper, since their statements include some generalizations, needed in order to better compare (and use) them. The analysis is carried out by comparing pairwise the families of systems whose stabilization through a given compensator is guaranteed by each of the considered robust stability conditions. Some properties of the families are formally derived and stated, and some very simple examples arc exhibited in order to illustrate the presented properties and comparisons. A theorem, representing an extension of one of the considered conditions, is proposed in order to overcome some difficulties arising in the use of the classical result. Copyright © 2004 John Wiley & Sons, Ltd.     

考虑饱和的发电机单机无穷大系统有限增益镇定

摘要：研究了一类具有饱和及外部干扰的发电机单机无穷大系统的鲁棒增益镇定问题.首先基于哈密顿能量理论将电机系统模型转化为广义耗散 哈密顿系统模型,然后运用静态输出反馈得到闭环哈密顿系统.在某增长条件下,证明了闭环系统可以达到渐近稳定和有限增益镇定, 同时得到了有限增益的估计值.仿真结果验证了所提方法的有效性.     

共面栅碲锌镉探测器读出电路设计及性能研究

为有效读出共面栅碲锌镉(CPG-CZT)探测器的核脉冲信号,本文结合CPG-CZT探测器工作原理及国内外研究,设计了可用于CPG-CZT探测器的读出电路,主要包括高压偏置电路、前置放大电路、增益调节及减法电路。为研究读出电路性能,本文测试了各单元电路的性能及探测系统能量分辨率随偏置电压、增益调节电路中两路信号的相对增益G的变化规律。结果表明：高压偏置电路两路输出偏压与输入偏置电压的相关系数R²均为0.998;前置放大电路输出噪声为5 mV;增益调节及减法电路输出信号噪声为10 mV;输入偏置电压、相对增益G的变化均会影响探测系统能量分辨率,当偏置电压为-1650 V、相对增益G为0.7时对¹³⁷Cs源产生的γ射线能量分辨率最佳,可达3.65%,且无明显拖尾现象。