多径传播环境下的无源UHF RFID系统电波传播模型

针对自由空间模型在预测射频识别系统识别距离时存在的偏差,综合考虑射频识别系统应用的多径传播环境,建立一种无源超高频射频识别系统电波传播模型,并重点分析了前向链路路径损耗的主要影响因素及其计算方法。基于该电波传播模型,探索性地提出实际环境下的无源超高频射频识别应用模拟思路。仿真和测量结果表明,该模型在预测无源超高频射频识别系统识别距离时更为准确。     

考虑驾乘人员公平性的网约出租车合乘路径优化模型

为了充分发挥合乘出租车承载率高、运营效益高及交通资源省等优点, 缓解城市打车难问题, 对网约出租车合乘路径优化问题开展研究. 首先针对路网中网约出租车的供需情况, 以系统路径最短为优化目标建立目标函数, 其次考虑网约出租车额定载客量、路径合理性、乘客利益及驾驶员收益与时间窗因素, 构建优化模型的约束条件, 并结合绕行距离与乘客公平性原则进行费用约束, 使得绕行距离长的合乘子路径获得更多的费用补偿, 然后基于遗传算法思想, 针对合乘路径中乘客需求起终点的次序问题, 设计了改进的交叉与变异算子. 最后依据大连市区局部路网高峰时段内的出租车供需数据, 利用合乘路径优化模型及算法进行求解. 研究表明, 优化模型及算法可以短时间寻求到系统近似最优解, 所得合乘方案较非合乘出行模式有效减少了出租车空驶率与乘客的出行成本, 提高了驾驶员的平均收益.     

An inexact fuzzy-queue programming model for environmental systems planning

In this study, an inexact fuzzy-queue programming (IFQP) model is developed for municipal solid waste (MSW) management under uncertainty, where fuzzy queue (FQ) model is introduced into the interval-fuzzy linear programming (IFLP) framework. The proposed IFQP model can not only handle uncertainties that are presented in terms of fuzzy sets and discrete intervals, but also reflect the influence of FQ in decision-making problems. Moreover, it can help quantify the satisfaction degrees of the system cost and constraints under uncertainty. It improves upon the existing optimization model with advantages in data availability, uncertainty reflection and result analysis. In its solution process, the model is transformed into two deterministic submodels based on an interactive algorithm. Interval solutions which are stable in the decision space can be obtained by solving the two submodels sequentially. The developed model is applied to a case of long-term planning of MSW management systems to demonstrate its applicability. It can effectively reflect dynamic, interactive, and uncertain characteristics of municipal waste management systems. The decision variable solutions provide optimal schemes for waste flow allocation corresponding to lower and upper bounds of system cost. The results indicate that reasonable solutions have been generated. They are helpful for supporting: (i) decision making or justification of waste-allocation patterns of MSW management system, and (ii) in-depth analysis of tradeoffs among system cost, satisfaction degree, and environmental constraint under uncertainty.     

Systematic modeling and model handling for manpower planning systems

The primary purpose of this paper is to show an efficient way of handling models and model data in a decision support system, in which it is usual to consider several variants of a model. The model data primarily consist of model-defining data, but the same approach may be used for the generated results as well. By efficient handling is meant the handling by the computer as well as by the user. For the user it is particularly important that new models can be conveniently defined as variants of existing models. The approach is introduced within the context of a decision support system for manpower planning based on Markov models. In the mean time the same approach has been used for the implementation of other decision support systems and has been found to be more generally applicable.     

A machining process planning activity model for systems integration

A key issue of integrating process planning systems with design systems and production planning systems is how to overcome barriers in data exchange and sharing amongst software systems. A machining process planning activity model was developed to address some of the barriers. This model represents functional components and data requirements in process planning systems. The purpose of the model is to create the context in which data requirements and data flow for numerically controlled machining process planning are defined. Furthermore, the model was developed as a unification of many previously developed process planning activity models.     

滑模等式约束的时滞系统广义预测控制

提出了一种滑模等式约束的广义预测控制方法.该方法将广义预测控制与离散滑模控制结合起来用于具有大惯性、大时滞、时变和非线性的热力站换热机组的供水温度控制系统中,并采用柔化输入信号的方法,可避免广义预测控制算法中的矩阵求逆,有效缩短了预测时域,减小计算量.最后给出了稳定性分析并通过仿真验证了该方法的有效性.     

Generalized route planning model for hazardous material transportation with VaR and equity considerations

Recently, the Value-at-Risk (VaR) framework was introduced for the routing problem of a single hazmat trip. In this paper, we extend the VaR framework in two important ways. First, we show how to apply the VaR concept to a more realistic multi-trip multi-hazmat type framework, which determines routes that minimize the global VaR value while satisfying equity constraints. Second, we show how to embed the algorithm for the single hazmat trip problem into a Lagrangian relaxation framework to obtain an efficient solution method for this general case. We test our computational experience based on a real-life hazmat routing scenario in the Albany district of New York State. Our results indicate that one can achieve a high degree of risk dispersion while controlling the VaR value within the desired confidence level.     

A contingency model for estimating success of strategic information systems planning

Strategic information system planning (SISP) has been identified as a critical management issue. It is considered by many as the best mechanism for assuring that IT activities are congruent with those of the rest of the organization and its evolving needs.     

基于E-CARGO模型的共乘出行匹配建模与优化方法

共乘出行应用系统通过提高汽车可用座位容量利用率来减少交通拥堵、缓解停车位紧张,提高社会效益和环境效益。司机和乘客的实时匹配和优化技术是共乘系统的核心内容。基于角色的协同（RBC）是一种用于促进组织结构、提供有序系统行为和协调系统内活动的新方法。为了减少乘客和司机的动态实时匹配时间、提高匹配效率,提出结合RBC和环境-类、代理、角色、群组和对象（E-CARGO）模型形式化共乘问题的方法。在资源容量约束和利润收入给定的情况下,对共乘匹配问题进行建模和仿真实验,提高可用座位容量利用率,实现平台收益最大化,资源匹配合理化。实验结果表明,基于E-CARGO模型的形式化方法可以应用于共乘出行匹配问题建模,最优匹配矩阵和时间可以采用Kuhn-Munkres（K-M）算法和Java中的优化软件包（ILOG）解决方案获得。与ILOG软件包算法相比,K-M算法所用平均时间至少减少了21%;当代理规模大于一定数值（大于600）时,算法时间开销急剧增大。     

Fast frequency-domain equalization for single-carrier V-BLAST systems over multipath channel

A low complex minimum mean-square error frequency-domain decision feedback (MMSE-FDDF) equalization algorithm is proposed in this paper for the single-carrier V-BLAST systems. Exploiting the factor that the discrete Fourier transform (DFT) is unitary, the proposed receiver can equalize the signals by the MMSE detecting to the spectrums in the frequency domain instead of the waveforms in the time domain. In order to obtain the right decisions, the detector must be able to equalize the overall spectrum with regard to each layer. This work can be performed very efficiently since the system matrix has been designed as a special block-circulant-block matrix. Similar to other V-BLAST-like systems, the detecting order has strong impact on the performance of MMSE-FDDF. Therefore, we further give a fast optimally sorting scheme for the MMSE-FDDF architecture. By using the newly constructed matrix, the coefficients computation and the sorting can be combined into one process, and then we employ the modified Gram-Schmidt (MGS) to simplify the process. The simulation results and the computational complexity analysis show that the proposed MMSE-FDDF has better tradeoff between the performance and the complexity than the existing algorithms. In addition, MMSE-FDDF can avoid the performance floor caused by the overlap-and-save technique in the severe dispersive channel. Supported partially by the National Natural Science Foundation of China (Grant Nos. 60572046, 60502022, 60772095), the National High-Tech Research and Development Program of China (“863” Program)(Grant No. 2006AA01Z220)     

Modified Generalized Autocorrelation based Estimator for time delays in multipath environment - A tradeoff in estimator performance and number of multipath

In this paper, the existing Generalized Autocorrelation based Estimator (GAE) has been modified for estimation of time delays in multipath environment in the presence of uncorrelated noise. Here the multipath propagation output signal is modeled as a superposition of the delayed, attenuated, and filtered versions of the stationary Gaussian stochastic input signal. Accuracy Percentage (AP) performance measure has been used to characterize the performance of the estimators. The modified GAE performance has been compared, obtained both analytically and via simulation, with AP_CRLB the equivalent CRLB expressed in AP. Simulation results show that the performance of the proposed estimator improves with the increase in SNR but deteriorates with the increase in number of multipath.     

A mathematical programming model for AGVS planning and control in manufacturing systems

In this paper, problems of the planning and control of automated guided vehicles in manufacturing systems are discussed. A mixed integer programming model is developed to minimize the total material handling cost in manufacturing systems. In order to solve this NP-complete problem efficiently, a decomposition approach following the Lagrangian relaxation method is used. The decomposed sub-problems can be solved by a dynamic programming method. An efficient algorithm is developed to solve the entire problem and a numerical example is presented to illustrate the method of solution.     

广义Voronoi图求解多机器人运动规划

在拥挤环境中,由于障碍物的边界形状比较复杂,需要使用广义Voronoi图表示空间环境。且在多移动机器人的运动规划过程中,需要协调多个机器人的运动,必须得到Voronoi图通道的宽度。为此提出了一种计算拥挤障碍物环境中生成的广义Voronoi图及其通道宽度的算法。并在生成的Voronoi图上利用A*算法对多个机器人进行路径规划,并利用分布式方法协调多个机器人运动。对协调两个机器人运动的过程进行了仿真,仿真结果表明利用提出的算法生成的具有通道宽度信息的Voronoi图能够满足多移动机器人运动规划的需要。     

一类非线性系统的广义模糊双曲正切模型自适应控制器设计

针对一类非线性系统的稳定控制器设计问题, 根据广义模糊双曲正切模型的万能逼近性质, 提出一种带有可调参数的广义模糊双曲正切模型的自适应控制器设计方法. 该设计方法的优点是使得自适应律的个数不依赖于广义模糊双曲正切模型的线性基函数的输出形式, 可以有效减少在线估计的参数数目, 并且能够保证被控系统的状态一致终极有界. 最后通过数值算例表明了所提出的设计方法的有效性.

     

Generalized fixed-interval smoothers for discrete-time systems

The generalized fixed-interval smoothing problem involves predictive information concerning the final state in addition to a priori information concerning the initial state. Forwards and backwards Markovian models which incorporate the predictive and a priori information, respectively, are constructed by simply using the standard smoothing formulae. The generalized backward- or forward-pass fixed-interval smoothing algorithm and two-filter smoothing algorithm are described in a unified manner. It is then shown that the generalized smoothers include as special cases almost all existing smoothers, e.g., Rauch–Tung–Striebel smoother, Mayne–Fraser two-filter smoother, Wall–Willsky–Sandell two-filter smoother and Desai–Weinert–Yusypchuk smoother. Simulation examples are included to illustrate the characteristics of the present fixed-interval smoothers.     

An efficient multipath routing for distributed computing systems with data replication

In distributed computing environments, executing a program often requires the access of remote data files. An efficient data routing scheme is thus important for time-critical applications. To ensure a prior desired communication quality, we present a connection-oriented routing scheme, the multipath routing, which allows multiple routes to be established between the source and the destination. Based on the multipath routing scheme, the problem of finding a collection of routing paths for an application to minimize its data transmission time is addressed. Such a problem becomes a complex combinatorial one when the application accesses multiple replicated data sources. Since finding an optimal solution is computationally infeasible in practice, we thus propose a heuristic method to get a sub-optimal solution.     

An optimization model and multiple matching heuristics for quality planning in manufacturing systems

Planning quality control operations for parts assigned to a manufacturing system is an important decision-making process. It involves the selection of quality tools and assignment of the tools and quality operations to machine centers or inspection stations. The problem is complicated by multiple variables involved and the interactions between the variables. Trade-off must be made to minimize the total cost and satisfy demands and resource constraints. Mathematical formulation can be used to integrate the decisions and characterize the problem. More efficient heuristic algorithms are developed based on a tripartite graph representation of the original problem. Experimental results showed that the algorithms proposed are effective and efficient in their computational performance.     

Developing an analytical model for planning systems verification,validation and testing processes

System VVT (verification, validation, and testing) are three tasks of System Engineering that focus on ensuring that systems are designed and delivered to meet customer and engineering requirements in the best way possible. Most organizations use sub-optimal VVT processes and methods. The literature does not offer an effective approach for associating VVT methods to VVT activities in order to satisfy customer and engineering requirements. In many large and complex projects, the project manager faces the dilemma of how best to validate and verify customer and engineering requirements, respectively. In many cases, decisions are made in an intuitive manner. For a project with a small amount of requirements (e.g., design of a new chair, table, or a simple toy), optimum decisions for VVT methods to be included within the project are feasible. For projects with large amount of requirements, for example, design of a new payload (e.g., captive carriage of a fuel tank, camera pod or other equipment) on an aircraft, a structured process to evaluate the overall impact of VVT methods implemented in order to satisfy those requirements, and the risk involved by performing these and not other methods, is necessary. This paper proposes a model for selecting an appropriate VVT approach depending on the phase or the level of the product in the system hierarchy; the model is independent of project size or precedence. We present an analytical model that not only structures the decision process but also outputs the optimal VVT methods given Cost and Risk constraints. The analytical model was formulated as an optimization problem, where a function that associates Quality derived from incorporating VVT methods is maximized subject to Cost and/or Risk constraints. The use of the model is demonstrated on a sample problem.     

Generalized L systems

This paper proposes the concept of generalized L systems, GL systems for short, which can describe asynchronized concurrent phenomena. We have proved that the GL systems are proper extensions of the traditional L systems. We have also defined a classification of GL systems and proved a sufficient and necessary condition for the equivalence of two subclasses of GL systems: two GPD0L (a class of deterministic GL systems) systems L[m ₁, m ₂, …, m _j ] and L[n ₁, n ₂, …, n _k ] are equivalent, iff k = j and there exists a common divisor g of all m _l and a common divisor h of all n _l such that ? i: m _i/g = n _i/h.