An Optimal Threshold Control for a BMAP/SM/1 System with Map Disaster Flow

A BMAP/SM/1 queueing system with two operation modes, a Markov disaster flow, and a modified threshold control strategy is studied. The stationary state probability distribution of the imbedded Markov chain is determined. An algorithm for finding the optimal modified threshold control strategy for the system is designed.     

改进的OVM交通流模型及数值模拟研究

传统的最优速度模型(OVM)中驾驶员灵敏度系数均取常数,这与实际情况不完全相符,为此,提出一种基于驾驶员灵敏度系数概率分布的最优速度模型(PDDS-OVM)。该模型根据概率统计理论,将驾驶员的灵敏度系数归纳为按一定概率分布的函数,交通流队列中的每辆车对应该分布的一个值。在Matlab7.0仿真平台上,对驾驶员灵敏度系数在定值、均匀分布、正态分布3种情况下,分别进行反复数值模拟仿真,结果表明PDDS-OVM模型能更好地描述交通流的波动特性。     

Multithreshold control of the BMAP/G/1 queuing system with MAP flow of Markovian disasters

Consideration was given to the BMAP/G/1 queuing system with a controlled mode of operation and flow of disasters interrupting servicing and emptying the system. The multithreshold strategies were used to control the mode of operation. For a fixed control strategy, determined were the stationary distribution of the system state probabilities at the instants of servicing completion and the performance characteristics such as the mean times between the customer departures, mean fraction of using a mode, mean number of customers lost in unit time because of disasters, and the probability that an arbitrary customer will be safely serviced. A numerical example illustrating the results was presented.     

合作连锁营销下随机需求的分销系统双层补货优化控制模型

研究在每一补货间隔内需求为服从有限区间上渐变对称分布的随机变量的各零售商集体与一个地区分销中心组成的地区分销系统.分销系统中各零售商可独立决定所经营卖场的补到水平,补货周期是固定值;分销中心给各零售商送货,送货循环周期固定,各零售商补货周期等于分销中心送货循环周期.假定零售商顾客需求是均匀发生的,给出了零售商补到水平优化控制策略和分销中心进货控制策略.最后,通过一个算例验证了该模型的有效性.     

Flow analysis in valve with moving grids through CFD techniques

The compressible air flow in a typical puffer chamber with moving contact between fixed electrodes has been studied using computational fluid dynamics techniques. Moving grid methods in CFD process not only plays a pivotal role in understanding the flow behavior in time domain but also helps for fixing the internals at optimal locations. A typical laboratory puffer chamber geometry has been extracted from the published literature and generated multi-block structured grid using Altair’s HyperMesh software. Flow simulation in axi-symmetry duct comprises fixed electrodes, moving contact and exit duct has been carried out with ANSYS-CFX software. It has been observed that, due to steps and curvature in the geometry, flow takes different turns from inlet and velocity distribution between fixed electrodes indicates vortex flow with turbulent eddies. CFD simulation with valve element mesh motion indicates that pressure history is significantly affected by the velocity of moving contact in the puffer chamber. The results obtained for a typical puffer chamber with the mesh motion are qualitative in nature and forms the sound basis for future design studies of electro-fluid dynamics of circuit breakers.     

Convergence and Consistency of Fuzzy c-means/ISODATA Algorithms

The fuzzy c-means/ISODATA algorithm is usually described in terms of clustering a finite data set. An equivalent point of view is that the algorithm clusters the support points of a finite-support probability distribution. Motivated by recent work on the hard version of the algorithm, this paper extends the definition to arbitrary distributions and considers asymptotic properties. It is shown that fixed points of the algorithm are stationary points of the fuzzy objective functional, and vice versa. When the algorithm is iteratively applied to an initial prototype set, the sequence of prototype sets produced approaches the set of fixed points. If an unknown distribution is approximated by the empirical distribution of stationary, ergodic observations, then as the number of observations grows large, fixed points of the algorithm based on the empirical distribution approach fixed points of the algorithm based on the true distribution. Furthermore, with respect to minimizing the fuzzy objective functional, the algorithm based on the empirical distribution is asymptotically at least as good as the algorithm based on the true distribution.     

New constant service time Polya/D/n traffic model with peaked input stream

In this paper, we study the buffer queueing behaviour in high-speed networks. Some limited analytical derivations of queue models have been proposed in literature but their solutions are often a great mathematical challenge. We propose to use the Polya distribution to overcome such limitations. The specific behaviour of an IP interface with bursty traffic and long-range dependence is investigated by a version of the “classical” M/D/n queueing model called Polya/D/n. This is queueing system with a Polya input stream (a negative binomial distributed number of arrivals in a fixed time interval), a constant service time, multiple servers, and infinite waiting rooms. The model is considered a renewal process because of its quasi-random input stream and constant service time. We develop balance equations for the state of the system and obtain results for the packet loss and delay. The finding that the Polya distribution is adequate to model bursty input streams in IP network interfaces has motivated the proposal to evaluate the Polya/D/n system. It is shown that the variance in the input stream significantly changes the characteristics of the waiting system. The suggested model is new and allows defining different bursty traffic and evaluating losses and delays relatively easily.     

复杂失效分布下的动态检查点设置

检查点技术是保障计算机系统可靠性的一种常用方法.通常假定系统失效的发生服从泊松分布,因此检查点是等间隔设置的.但近几年公布的现场数据表明以上假定不合实际.因此,首先利用现场失效数据对固定检查点间距方法的适应性进行分析,并提出两种检查点动态设置方法,它们根据系统前个阶段的失效信息动态地设置下一个检查点.模拟实验结果表明,所提出的方法在复杂失效分布下所获得的效果达到或者优于最优固定检查点的水平.     

Weighted modeling of the probability of monotone failure of a system with substantially different reliability characteristics of its elements

The probability of monotone system failure on a fixed time interval is studied. The failure and repair distribution functions are assumed to be of a general form. A new accelerated simulation method is proposed, which makes it possible to investigate systems consisting of components with essentially different reliability characteristics. Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 45–54, March–April, 2000.     

非接触IC卡手持读写器上验卡软件的开发

本文介绍了在G-6102手持智能读写器上开发的一套验卡软件系统。所开发的系统能够实现读卡、写卡、管理验卡数据以及与上位机的数据通信等功能,解决了一些娱乐场所验票地点灵活多变,固定没备难以满足其需求的问题     

气/液两相流相关法测速系统的仿真研究

气/液两相流是自然界和工业过程中广泛存在的一种非常典型、复杂的两相流形态。本文以气液两相凝固流为模型将电容层析成象(ECT)技术和相关流速测量技术相结合,针对采样运算所得的电容信号分别采用象素相关、归一化互相关、差动自相关和极性互相关四种相关算法进行了相关测速系统的Matlab仿真。结果表明采用相关测量技术可较好的实现两相流离散相速度的测量。     

Power-Law Distributions of Component Size in General Software Systems

This paper begins by modeling general software systems using concepts from statistical mechanics which provide a framework for linking microscopic and macroscopic features of any complex system. This analysis provides a way of linking two features of particular interest in software systems: first the microscopic distribution of defects within components and second the macroscopic distribution of component sizes in a typical system. The former has been studied extensively, but the latter much less so. This paper shows that subject to an external constraint that the total number of defects is fixed in an equilibrium system, commonly used defect models for individual components directly imply that the distribution of component sizes in such a system will obey a power-law Pareto distribution. The paper continues by analyzing a large number of mature systems of different total sizes, different implementation languages, and very different application areas, and demonstrates that the component sizes do indeed appear to obey the predicted power-law distribution. Some possible implications of this are explored.     

G/M/1 queue study of buffer behavior in the decoding system of computer communication

This paper deals with the buffer behavior at the decoding center of a computer communication system in which the messages are in the Huffman code of English text. It is assumed that the arrival of messages has an arbitrary distribution, with the message lengths having negative exponential distribution. The situation is well described by the G/M/1 model of queue theory. The waiting time model is simulated on the EC-1030 computer, assuming the HP2100A computer is the decoding machine. The simulation results are used for estimation of buffer size in a character-oriented system and block-oriented system for a very low overflow probability.     

点式超声波流速仪设计

点式超声波流速仪根据超声相位偏移测量原理设计而成。其核心是装在壳体内的单片机测控系统，能实时、连续、自动测量及显示特定测点的流速和流向。由于采用了声速补偿方法，保证了测量精度。     

A System to Define and Allocate Health Care Resources on a Territory to Improve the Life Quality of the Populations in Developing Countries

In this paper the health resource allocation problem is discussed. An object-oriented system is proposed and its implemented prototype is illustrated. It consists of two parts: a Geographical Information System, which is able to acquire and store both geographical and social-epidemiological information (including the resource distribution on that territory), and a Decision Support System, able to decide, using optimization algorithms, the new resource allocation in order to obtain a quasi-optimal solution for the cost/benefit ratio minimization problem, after having fixed the goal (e.g., the decrease of the incidence of a given disease) and constraints (e.g., a fixed budget, a given set of available resources, etc.). The object-oriented database which is part of the system can simulate and store different scenarios, depending on the different goals and constraints defined in input, by means of a user friendly interface.     

无人机飞控/导航系统便携式测试仪设计

针对当前某型无人机飞控/导航系统现场联调发生故障时无法快速定位故障点而造成调试周期过长的问题,根据有固定航姿参数输入的飞控/导航系统会产生固定输出的原理,提出并实现了一种基于现场测试仪的快速诊断方法;基于DSP和CPLD的便携式飞控/导航系统测试仪通过实验电缆把测试仪与被测设备相连,可以方便、直观、快捷、可靠地确定出被测设备是否存在故障。     

Z脉冲信号在光电编码器位移校正中的研究与应用

分析光电编码器脉冲信号A/B/Z,对定尺机自动定尺系统因反馈信号受外界信号干扰而存在测量误差进行研究并提出解决方案,利用光电编码器Z脉冲信号对反馈信号进行校正,消除累积误差造成的影响,提高定尺机自动定尺的准确性。     

Adaptive uniform finite-/fixed-time convergent second-order sliding-mode control

ABSTRACT

This paper presents an adaptive gain algorithm for second-order sliding-mode control (2-SMC), specifically a super-twisting (STW)-like controller, with uniform finite/fixed convergence time, that is robust to perturbations with unknown bounds. It is shown that a second-order sliding mode is established as exact finite-time convergence to the origin if the adaptive gain does not have the ability to get reduced and converge to a small vicinity of the origin if the adaptation algorithm does not overestimate the control gain. The estimate of fixed convergence time of the studied adaptive STW-like controller is derived based on the Lyapunov analysis. The efficacy of the proposed adaptive algorithm is illustrated in a tutorial example, where the adaptive STW-like controller with uniform finite/fixed convergence time is compared to the adaptive STW controller with non-uniform finite convergence time.     

放射形配网潮流计算的一种新的牛顿法

前推回推法是放射形配网潮流计算最基本的算法.通过对前推回推法求解过程的数学演化,导出一种新的牛顿类型的算法及其雅可比矩阵直接分解公式.利用比较原理,间接证明该算法是一种具有超线性收敛性的近似牛顿法.与经典牛顿法相比,该算法无须计算雅可比矩阵、无须三角因子分解等过程,直接由前代/回代或回代/前代过程就能完成;与前推回推法相比,该算法无须特定的节点和支路编号过程.文中以一个实际的中等规模配电系统为例,分析、比较前推回推法、导出的近似牛顿法、经典牛顿法等的收敛性和计算速度,证实上述研究结论.     

Stochastic analysis of the LMS algorithm for cyclostationary colored Gaussian and non-Gaussian inputs

This paper studies the stochastic behavior of the LMS algorithm in a system identification framework for a cyclostationary colored input without assuming a Gaussian distribution for the input. The input cyclostationary signal is modeled by a colored random process with periodically time-varying power. The generation of the colored non-Gaussian random process is parametrized in novel manner by passing a Gaussian random process through a coloring filter followed by a zero memory nonlinearity. The unknown system parameters are fixed in most of the cases studied here. Mathematical models are derived for the behavior of the mean and mean-square-deviation (MSD) and the excess mean-square error (EMSE) of the adaptive weights as a function of the input cyclostationarity. The models display the dependence of the algorithm upon the input nonlinearity and coloration. Three nonlinearities that are studied in detail with Monte Carlo simulations provide strong support for the theory.