融合网络编码的无线协作中继网络资源分配

综述融合网络编码的无线协作中继网络资源分配的研究进展,总结了已有典型资源分配策略的特点、性能及系统设计要求,分析了网络编码技术(包括数字网络编码和物理层网络编码)的引入对无线协作中继网络资源分配策略设计的影响,给出了一种实用化的系统级跨层优化框架及设计基本原则,并探讨了无线协作中继网络资源分配研究的发展趋势及其走向实用化所亟待解决的关键问题.     

Cooperative group optimization with ants (CGO-AS): Leverage optimization with mixed individual and social learning

We present CGO-AS, a generalized ant system (AS) implemented in the framework of cooperative group optimization (CGO), to show the leveraged optimization with a mixed individual and social learning. Ant colony is a simple yet efficient natural system for understanding the effects of primary intelligence on optimization. However, existing AS algorithms are mostly focusing on their capability of using social heuristic cues while ignoring their individual learning. CGO can integrate the advantages of a cooperative group and a low-level algorithm portfolio design, and the agents of CGO can explore both individual and social search. In CGO-AS, each ant (agent) is added with an individual memory, and is implemented with a novel search strategy to use individual and social cues in a controlled proportion. The presented CGO-AS is therefore especially useful in exposing the power of the mixed individual and social learning for improving optimization. The optimization performance is tested with instances of the traveling salesman problem (TSP). The results prove that a cooperative ant group using both individual and social learning obtains a better performance than the systems solely using either individual or social learning. The best performance is achieved under the condition when agents use individual memory as their primary information source, and simultaneously use social memory as their searching guidance. In comparison with existing AS systems, CGO-AS retains a faster learning speed toward those higher-quality solutions, especially in the later learning cycles. The leverage in optimization by CGO-AS is highly possible due to its inherent feature of adaptively maintaining the population diversity in the individual memory of agents, and of accelerating the learning process with accumulated knowledge in the social memory.     

Coordinating distributed organizational knowledge

As organizations move from hierarchical towards market-like structures, their distributed units also take a larger role in the design and evolution of organizational information systems. This requires strategies which support the cooperative creation, evaluation and evolution of global information flow structures among autonomous organizational units through local knowledge acquisition and maintenance. Three such strategies are presented: cooperative conceptual modeling, multi-simulation, and explicit process support. These strategies are formally embedded in a meta modeling framework and implemented with a repository-based architecture. They are intended for the analysis of business processes in networked organizations, and as a basis for designing and evolving their federated information systems.     

Modeling of shape memory alloy shells for design optimization

A three-dimensional phenomenological constitutive model for the analysis and design optimization of shape memory alloy (SMA) structures is presented. This model specifically targets the pseudoelastic behavior due to the R-phase transformation in NiTi alloys, but also applies to similar SMA materials with low hysteresis. A history-independent formulation is presented, which allows cost-effective sensitivity analysis. The possibility to efficiently compute design sensitivities is essential for enabling the use of gradient-based optimization algorithms, which will allow design optimization of complex SMA structures. The use of the constitutive model in a problem of realistic complexity is illustrated by the analysis of a SMA miniature gripper, modeled using shell elements. The sensitivity analysis of SMA structures using the presented model is addressed in an accompanying paper.     

Optimization of high-speed VLSI interconnects: A review (invited article)

Today's electronic systems such as computers and digital communication systems, have necessitated a rapid increase in operating frequency. Because of this, VLSI interconnects have become one of the critical issues in an overall system design. Improperly designed interconnects lead to signal integrity degradations such as signal delay, cross talk and ground noise, limiting the overall system performance. In recent years, research into the interconnect optimization problem has been very active, and much important progress has been made. This article presents a review of the current status of this subject area. The formulations of signal-integrity oriented optimization of interconnects at different levels of electronics systems, that is; chip, multichip module (MCM), and printed circuit board (PCB) levels, are reviewed, together with various optimization techniques. Highlights on parallel and multilevel optimization for interconnect networks and the use of macromodeling techniques are also presented. Advanced formulations of interconnect optimizations featuring manufacturability oriented and multidisciplinary design objectives are reviewed. A discussion on the future challenges in the area is included at the end. © 1997 John Wiley & Sons, Inc. Int J Microwave Millimeter-Wave CAE 7: 83–107, 1997.     

基于特征的三维参数化产品造型系统ZD－MCAD Ⅱ

本文介绍了浙江大学人工智能研究所在产品造型研究基础上完成的一个面向机械产品设计的实用化计算机辅助设计（ＣＡＤ）系统ＺＤ－ＭＣＡＤⅡ。首先我们结合实际从事ＣＡＤ系统的经验提出了一套开发实用化、商品化ＣＡＤ系统的设计方法学，然后介绍了ＺＤ－ＭＡＣＤⅡ的系统结构以及总体功能，并就某些重要的模块的结构及实现进行了广泛的讨论。     

Designing and Analyzing a Flash File System with Alloy

Alloy is a lightweight modeling language based on .rst-order relational logic. The language is expressive enough to describe structurally complex systems, but simple enough to be amenable to fully automated analysis. The Alloy analyzer, with its SAT-based analysis engine, allows one to simulate traces of a system, visualize them, or search for counterexamples to a property. This article illustrates key concepts of Alloy using, as an example, the construction and analysis of a design for a .ash .le system. In addition to basic .le operations, the design includes features that are crucial to NAND .ash memory but contribute to increased complexity of the .le system, such as wear leveling and erase-unit reclamation. The design also addresses the issues of fault-tolerance by providing a mechanism for recovering from unexpected hardware failures. The article describes the modeling process and discusses the results of the design analysis, which has been carried out by checking trace inclusion of the .ash .le system against a POSIX-compliant abstract .le system.     

Stable controller design of MIMO systems in real Grassmann space

A new design method of a stable dynamic output feedback (DOF) controller in linear MIMO systems is presented on the frame of real Grassmann spaces. For the analysis, the DOF systems are decomposed into augmented static output feedback (SOF) systems using signal flow graph analysis of all DOF loops. For synthesis and design, the characteristic polynomial of the augmented SOF system for the system’s stable poles and the sub-characteristic polynomial of the sub-SOF system for the controller’s stable poles are parametrized within their Grassmann invariants in real Grassmann spaces, whose coordinates are defined in the real coefficient function spaces of their augmented SOF variables. The numerical parametrization and computation algorithm for a stable controller design is illustrated over a MIMO plant of a practical aircraft carrier model.     

A small gain framework for networked cooperative force-reflecting teleoperation

For cooperative force-reflecting teleoperation over networks, conventional passivity-based approaches have limited applicability due to nonpassive slave–slave interactions and irregular communication delays imposed by networks. In this paper, a small gain framework for stability analysis design of cooperative network-based force reflecting teleoperator systems is developed. The framework is based on a version of weak input-to-output practical stability (WIOPS) nonlinear small gain theorem that is applicable to stability analysis of large-scale network-based interconnections. Based on this result, we design a cooperative force-reflecting teleoperator system which is guaranteed to be stable in the presence of multiple network-induced communication constraints by appropriate adjustment of local control gains and/or force-reflection gains. Experimental results are presented that confirm the validity of the proposed approach.     

Finite‐time stability and stabilization of semi‐Markovian jump systems with time delay

Semi‐Markovian jump systems are more general than Markovian jump systems in modeling practical systems. On the other hand, the finite‐time stochastic stability is also more effective than stochastic stability in practical systems. This paper focuses on the finite‐time stochastic stability, exponential stochastic stability, and stabilization of semi‐Markovian jump systems with time‐varying delay. First, a new stability condition is presented to guarantee the finite‐time stochastic stability of the system by using a new Lyapunov‐Krasovskii functional combined with Wirtinger‐based integral inequality. Second, the stability criterion is further proved to guarantee the exponential stochastic stability of the system. Moreover, a controller design method is also presented according to the stability criterion. Finally, an example is provided to illustrate that the proposed stability condition is less conservative than other existing results. Additionally, we use the proposed method to design a controller for a load frequency control system to illustrate the effectiveness of the method in a practical system of the proposed method.     

多个线性时滞系统的关联稳定与协调控制

研究线性时滞系统的时滞无关关联稳定性和协调控制问题.利用双线性矩阵不等式(BMI),给出了两个系统关联稳定和协调镇定的充分条件,将关联和协调控制器的设计问题转化为具有BMI约束的非凸优化问题,并给出了求解这类问题的交替算法.最后,通过一个数值例子来说明本文结果的有效性.研究结果表明,不稳定的时滞系统可以通过设计关联或协调控制构成稳定的组合系统.     

支持多学科设计优化的集成产品过程建模方法

针对当前主要的设计过程建模方法缺乏表达复杂产品多学科设计过程中资源的组织调用和协作方式等信息,提出一种支持复杂产品多学科设计优化的设计路线图框架过程建模方法.从全面表达设计过程信息的角度出发,描述产品多学科设计优化过程中的主要活动及其协同关系,建立支持多学科设计优化的过程模型;在此基础上,给出了多学科设计优化的过程规划方法,以降低产品设计过程中的迭代,通过构建支持多学科设计优化的集成产品设计过程结构框架,实现产品多学科设计优化的过程集成.最后通过已开发的多学科系统集成平台,应用具体设计实例验证了整套方法的有效性.     

基于有向图的信息拓扑独立的二阶系统一致性判据

针对可能存在拓扑切换情形的有向图, 研究了多个二阶系统在没有领航者时的一致性问题. 提出了两个使用不同合作策略的一致性算法, 并得到了若干与信息拓扑参数无关的一致性判据. 采用基于特征值分析的方法对第一个一致性算法进行了分析, 得到了该算法在固定有向图条件下一致性可达的充分必要条件. 对于第二个一致性算法, 如果切换网络拓扑的并图存在一棵有向生成树的频率足够高, 则系统仍然可以实现一致性. 利用等价模型变换将原系统转化为级联系统的方法, 给出并简化了该算法的收敛性分析. 采用同样的策略, 针对切换无向图的一致性问题进一步推导得到了一个新颖的充分必要条件. 另外, 本文还分别针对固定有向图研究了这两个算法对时延的鲁棒性. 论文最后给出了仿真示例, 验证了所得理论结果的正确性和算法的有效性.     

基于数据库的支持群体工作CAD软件的设计与实现

目前ＣＡＤ系统多是面向单个设计者，而实际的设计工作往往由多个设计者协同完成。ＣＡＤ系统应该支持多个设计者协同工作以提高工作效率。作者采用在现有的ＣＡＤ系统中加入支持设计者协同工作的模块的方法。利用这种方法将ＢＩＣＡＤ中的结构建模模块ＭＯＤＥＬ修改为ＣＷＭＯＤＥＬ，它可支持多个设计者协同工作并能缩短设计周期。实践证明这种方案是可行的。     

Towards a complementary balanced energy harvesting solution for low power embedded systems

The specific technical challenges associated with the design of an ambient energy powered electronic system currently requires thorough knowledge of the environment of deployment, energy harvester characteristics and power path management. In this work, a novel flexible model for ambient energy harvesters is presented that allows decoupling of the harvester’s physical principles and electrical behavior using a three dimensional function. The model can be adapted to all existing harvesters, resulting in a design methodology for generic ambient energy powered systems using the presented model. We also present a solution for the mathematical problem involved with the optimization of generator sizes when more than two harvesters are used, and demonstrate the ease of use of this solution for implementations on embedded systems with few system resources. Concrete examples are included to demonstrate the versatility of the presented design in the development of electronic appliances on system level.     

Optimal design of reconfigurable parallel machining systems

A reconfigurable machining system is usually a modularized system, and its configuration design concerns the selections of modules and the determination of geometric dimensions in some specific modules. All of its design perspectives from kinematics, dynamics, and control have to be taken into considerations simultaneously, and a multidisciplinary design optimization (MDO) tool is required to support the configuration design process. This paper presents a new MDO tool for reconfigurable machining systems, and it includes the following works: (i) the literatures on the computer-aided design of reconfigurable parallel machining systems have been reviewed with a conclusion that the multidisciplinary design optimization is essential, but no comprehensive design tool is available to reconfigurable parallel machining systems; (ii) a class of reconfigurable systems called reconfigurable tripod-based machining system has been introduced, its reconfiguration problem is identified, and the corresponding design criteria have been discussed; (iii) design analysis in all of the disciplines including kinematics, dynamics, and control have been taken into considerations, and design models have been developed to evaluate various design candidates; in particular, the innovative solutions to direct kinematics, stiffness analysis for the design configurations of tripod-based machines with a passive leg, and concise dynamic modelling have been provided; and (iv) A design optimization approach is proposed to determine the best solution from all possible configurations. Based on the works presented in this paper, a computer-aided design and control tool have been implemented to support the system reconfiguration design and control processes. Some issues relevant to the practical implementation have also been discussed.     

Autonomic tracing of production processes with mobile and agent-based computing

Tracing items in a supply chain, across different enterprises and through the full processes scope, is today an inherently complex design task. Enterprises are typically comprised of hundreds of applications that are custom built at different times, acquired from third parties and parts of legacy systems, and also operating in multiple tiers of different manufacturing and information system platforms. Further, traceability is characterized by a goal-oriented approach, in which business-process analyses are driven by goal achievements rather than by systematic engineering processes. The use of a classical enterprise integration approach mostly needs tailoring to different applications. Due to the number and diversity of the systems and of their interactions, and to their dynamicity, it is difficult, costly, and therefore often not convenient to develop in large scale distributed systems.To overcome these issues, a supply chain traceability system with a high level of automation is discussed in this paper. In particular, the system adopts an agent-based approach, in which cooperative software agents find solutions to back-end tracing problems by self-organization. Such cooperative agents are based on a business process aware traceability model, and on a service-oriented composition paradigm. Furthermore, an interface agent assists each user to carry out the front-end tracking activities. Interface agents rely on the context-awareness paradigm to gain self-configurability and self-adaptation of the user interface, and on ubiquitous computing technology, i.e., mobile devices and radio-frequency identification, to perform agile and automatic lot identification. The paper comprises real-world experiences on the fashion supply chain.     

Cooperative and Competitive Multi-Agent Systems: From Optimization to Games

Multi-agent systems can solve scientific issues related to complex systems that are difficult or impossible for a single agent to solve through mutual collaboration and cooperation optimization. In a multi-agent system, agents with a certain degree of autonomy generate complex interactions due to the correlation and coordination, which is manifested as cooperative/competitive behavior. This survey focuses on multi-agent cooperative optimization and cooperative/non-cooperative games. Starting from cooperative optimization, the studies on distributed optimization and federated optimization are summarized. The survey mainly focuses on distributed online optimization and its application in privacy protection, and overviews federated optimization from the perspective of privacy protection me- chanisms. Then, cooperative games and non-cooperative games are introduced to expand the cooperative optimization problems from two aspects of minimizing global costs and minimizing individual costs, respectively. Multi-agent cooperative and non-cooperative behaviors are modeled by games from both static and dynamic aspects, according to whether each player can make decisions based on the information of other players. Finally, future directions for cooperative optimization, cooperative/non-cooperative games, and their applications are discussed.      

A theoretical model for single-phase silicon-controlled rectifier systems

A linear model for use in determining stability, relative stability, and dynamic response of phase-angle modulated SCR systems is presented. The model is based on sampled-data control theory and assumes 1) a system bandwidth that is small relative to sampling frequency, and 2) limited excursion of the SCR triggering angle. These assumptions are justified for practical systems. The theory leads to a simple equivalent transport-lag representation. If the triggering angle varies over a relatively wide range, a "worst-case" analysis is necessary using the linear model. An example is included to illustrate use of the model for system design and is supported by experimental data.