Fluid-structure interaction analysis of a hypothetical core disruptive accident in LMFBRs

To ensure safety, it is necessary to assess the integrity of a reactor vessel of liquid-metal fast breeder reactor (LMFBR) under HCDA. Several important problems for a fluid-structural interaction analysis of HCDA are discussed in the present paper. Various loading models of hypothetical core disruptive accident (HCDA) are compared and the polytropic processes of idea gas (PPIG) law is recommended. In order to define a limited total energy release, a “5% truncation criterion” is suggested. The relationship of initial pressure of gas bubble and the total energy release is given. To track the moving interfaces and to avoid the severe mesh distortion an arbitrary Lagrangrian–Eulerian (ALE) approach is adopted in the finite element modeling (FEM) analysis. Liquid separation and splash from a free surface are discussed. By using an elasticity solution under locally uniform pressure, two simplified analytical solutions for 3D and axi-symmetric case of the liquid impact pressure on roof slab are derived. An axi-symmetric finite elements code FRHCDA for fluid-structure interaction analysis of hypothetical core disruptive accident in LMFBR is developed. The CONT benchmark problem is calculated. The numerical results agree well with those from published papers.     

还原铜粉之注射成形

平均粒度约10μm的微细还原铜粉因不规则粉末形态及残留有较高的氧含量，而不易以注射成形工艺来制备高性能产品。本研究发现，采用具较多量之主干高分子为基础的多元粘结剂能克服不规则粉末形态所导致之严重粉末间之磨擦，而将这种微细还原铜粉顺利的注射成形。烧结时，若能在烧结孔洞封闭之前将粉末中的残留氧化物有效的予以还原，如在低于900℃之温度下给予适当保温，则注射成形组件之烧结密度可高达95％理论密度。在此条件下，注射成形组件的导电率可达纯铜导电率的80％以上。     

Boundary-conformed toolpath generation for trimmed free-form surfaces

In this paper, we adopt a 2D reparameterization procedure to regenerate boundary-conformed toolpaths. Three methods for the 2D reparameterization of trimmed boundaries in parametric space are examined and compared. They are the Coons method, the Laplace method, and a newly developed boundary-blending method. These three methods represent three different approaches to 2D surface parameterization, namely, the algebraic interpolation approach, the partial differential equation approach, and a geometric offsetting approach, respectively. Complete algorithms for surface reparameterization and toolpath generation are developed and implemented. The results showed that the Coons method is relatively simple yet might cause anomalies when the complexities of the boundary are high. The Laplace method is robust but takes relatively more computational time and also has the problem of uneven distribution of iso-parametrics. For the newly developed boundary-blending method, both the computational efficiency and parameterization robustness are quite good, in addition, it alleviates the uneven distribution problem appeared in the Laplace results.     

MobiPADS: a reflective middleware for context-aware mobile computing

Traditionally, middleware technologies, such as CORBA, Java RMI, and Microsoft's DCOM, have provided a set of distributed computing services that essentially abstract the underlying network services to a monolithic "black box." In a mobile operating environment, the fundamental assumption of middleware abstracting a unified distributed service for all types of applications operating over a static network infrastructure is no longer valid. In particular, mobile applications are not able to leverage the benefits of adaptive computing to optimize its computation based on current contextual situations. In this paper, we introduce the Mobile Platform for Actively Deployable Service (MobiPADS) system. MobiPADS is designed to support context-aware processing by providing an executing platform to enable active service deployment and reconfiguration of the service composition in response to environments of varying contexts. Unlike most mobile middleware, MobiPADS supports dynamic adaptation at both the middleware and application layers to provide flexible configuration of resources to optimize the operations of mobile applications. Within the MobiPADS system, services (known as mobilets) are configured as chained service objects to provide augmented services to the underlying mobile applications so as to alleviate the adverse conditions of a wireless environment.     

基于模糊逻辑的ABR显式流量控制算法

面向连接的ATM网络通过一系列的流量管理机制为各种应用提供纯粹的服务质量(QoS)保证，其中ABR业务流量控制的作用尤显重要．显式速率(Explicit Rate,ER)控制是一种有效的机制，有效性、公平性和算法复杂度是各种显式速率控制算法所面临的主要问题．该文将ABR业务流基于速率的端到端闭环反馈控制抽象为控制理论中典型的调节系统，运用不依赖对象模型的模糊控制理论设计了一种新的流量控制算法——模糊速率控制算法(FRCA)．仿真试验表明FRCA的综合性能良好：保证了最大—最小公平性的实现；在LAN和WAN上均有较好的适应能力；算法的复杂度低；队列长度的控制能力强；易于硬件实现．     

ATM网络基于队列长度阀值的传输调度

本文提出了ATM网络的一种实时传输调度和信元丢失控制的综合方案.这种方案是基于队列长度阀值而设计的,它适应于ATM网络面向连接的特性.本文给出了这种方案的随机Petri网性能模型,并给出模型分解和迭代的近似求解方法.     

Adaptive polygonization of geometrically constrained surfaces

n -dimensional space, where n>3. This definition can be used for given surfaces that are implicit or parametric. This paper presents a robust, adaptive polygonization algorithm for evaluating and visualizing geometrically constrained surfaces. Let be the constrained surface, a 2-surface in n-space, and let π() be its projection into the subspace spanned by the first three coordinates. Our polygonization algorithm computes π(). The method works directly with the n-space representation, but performs all major computations in 3-space. Techniques for triangulation, polygon decimation, and local refinement are also presented.     

Control of Discrete Fuzzy Systems: Uncertainty and Guaranteed Performance

Robust control designs for a discrete Takagi and Sugeno (T-S) fuzzy model are proposed. The T-S fuzzy model contains (possibly fast) time-varying uncertainty. First, a switching-type robust control is shown to stabilize the T-S fuzzy model asymptotically. Second, a saturation-type robust control is shown to render the T-S model practically stable. In both designs, only the bound of uncertainty is needed. The effectiveness of proposed designs is analyzed rigorously and illustrated by simulations.     

湖南有色金属工业发展战略评述

概述了湖南有色金属工业发展的基本现状和所存在的主要问题，分析了其面临的战略形势。指出湖南有色金属工业必须走产业结构总体优化、产业全面升级和大集团层面资本运营发展之路，并详细提出了相应的战略措施。