Adiabatic shear localization: occurrence, theories, and applications

基于有限状态机与Petri网的系统分析与设计

从系统组成、功能需求和体系结构方面介绍了航天器空间对接仿真系统的实时多任务控制系统,基于有限状态机和Petri网方法对其进行了单任务级和多任务级的分析建模,并以此为基础完成系统的详细设计,其中应用分叉和资源共享模型实现了系统的同步和互斥问题。实际应用中应用工程化和模块化的方法完成系统设计,系统运行性能良好。试验证明这种分析设计方法合理可行。

Variational Approach to the Lane-Emden Equation

By the semi-inverse method, a variational principle is obtained for the Lane-Emden equation, which gives much numerical convenience when applying finite element methods or Ritz method.

On dispersion-controlled principles for non-oscillatory shock-capturing schemes

The role of dispersions in the numerical solutions of hydrodynamic equation systems has been realized for long time. It is only during the last two decades that extensive studies on the dispersion-controlled dissipative (DCD) schemes were reported. The studies have demonstrated that this kind of the schemes is distinct from conventional dissipation-based schemes in which the dispersion term of the modified equation is not considered in scheme construction to avoid nonphysical oscillation occurring in shock wave simulations. The principle of the dispersion controlled aims at removing nonphysical oscillations by making use of dispersion characteristics instead of adding artificial viscosity to dissipate the oscillation as the conventional schemes do. Research progresses on the dispersion controlled principles are reviewed in this paper, including the exploration of the role of dispersions in numerical simulations, the development of the dispersion-controlled principles, efforts devoted to high-order dispersion-controlled dissipative schemes, the extension to both the finite volume and the finite element methods, scheme verification and solution validation, and comments on several aspects of the schemes from author's viewpoint.

Calculation of valence subband structures for strained GaInP/AlGaInP quantum wells without axial approximation

Usually in the calculation of valence subband structure for III-V direct bandgap material, axial approximation had been used in the Luttinger-Kohn model to simplify the computational efforts. In this letter, the valence subband structure for the GaInP/AlGaInP strained and lattice-matched quantum wells was calculated without axial approximation, on the basis of 6x6 Luttinger-Kohn Hamiltonian including strain and spin-orbit splitting effects. The numerical simulation results were presented with help of the finite-difference methods. The calculation results with/without axial approximation were compared and the effect of axial approximation on the valence subband structure was discussed in detail. The results indicated that there was a strong warping in the GaInP valence band, and axial approximation can lead to an error when k was not equal to zero, especially for compressively strained and lattice-matched GaInP/AlGaInP quantum wells.

When is `partial' adequate? A logic-based proof technique using partial specifications

A technique is presented for ascertaining when a (finite-state) partial process specification is adequate, in the sense of being specified enough, for contexts in which it is to be used. The method relies on the automatic generation of a modal formula from the partial specification; if the remainder of the network satisfies this formula, then any process that meets the specification is guaranteed to ensure correct behavior of the overall system. Using the results, the authors develop compositional proof rules for establishing the correctness of networks of parallel processes and illustrate their use with several examples

ISO 2022的有限状态机描述

ISO 2022编码体系对字符集国家标准的制订有很大影响,然而标准条款存在不确定性,有时难于理解。本文引入有限状态机(FSM)模型来形式化地刻画ISO 2022的特征。针对FSM五元组,详细说明了其状态空间的构成,提出了输入字母表的等效分类方法,给出了初始状态以及终结状态集合,分析了状态转移函数的规模,并采用FSM描述方法分析了ISO-2022-CN、EUC-CN、复合文本等标准,揭示了这些标准与ISO 2022的内在联系。这些工作有助于ISO 2022标准符合性检测、扩展标准的制订与系统实现复杂度评估。鉴于形式化描述方法在编码字符集标准领域未得到广泛应用,本文工作为该类研究引入了新的思路和方法。

Optical analysis of AlGaInP laser diodes with real refractive index guided self-aligned structure

Optical modes of AlGaInP laser diodes with real refractive index guided self-aligned (RISA) structure were analyzed theoretically on the basis of two-dimension semivectorial finite-difference methods (SV-FDMs) and the computed simulation results were presented. The eigenvalue and eigenfunction of this two-dimension waveguide were obtained and the dependence of the confinement factor and beam divergence angles in the direction of parallel and perpendicular to the pn junction on the structure parameters such as the number of quantum wells, the Al composition of the cladding layers, the ridge width, the waveguide thickness and the residual thickness of the upper P-cladding layer were investigated. The results can provide optimized structure parameters and help us design and fabricate high performance AlGaInP laser diodes with a low beam aspect ratio required for optical storage applications.

事件驱动的BPEL引擎架构设计与实现

WS-BPEL(Web Service Business Process Execution Language，简称BPEL)是Web服务规范族中服务复合层的重要标准。BPEL支持通过对Web服务的编制(Orchestration)来构建业务流程，从而使编程人员能够集中关注业务逻辑。BPEL引擎系统是一个支持BPEL语言描述的业务流程运行的服务器中间件系统，使用BPEL引擎可以执行BPEL语言编写的业务流程。作为一个网络服务器系统，BPEL引擎将不可避免的处理大量的并发请求。如何设计实现BPEL引擎使之能高效的处理并发将是高性能BPEL引擎设计的关键问题。 并发服务器系统通常采用多线程和事件驱动两种并发模型。传统上大多数服务器软件都建立在多线程(或多进程)模型的基础上。但在高负载条件下，过多的线程和线程间的上下文切换会造成系统较大的开销，这些开销是导致系统性能下降的主要原因。事件驱动模型是一种只采用少量固定数量线程的并发模型，一般说来，它的伸缩性更好，并且有更高的处理效率。 本文对高并发服务器系统中所使用的事件驱动模型进行了分析和研究，并且结合BPEL语言规范的特点，提出了事件驱动的BPEL引擎实现技术方案。论文重点研究了BPEL事件结构和有限状态机(Finite State Machine，简称FSM)刻画BPEL流程和活动行为的原理，针对BPEL语言语法特点，构造了完整的BPEL FSM模型，包括了状态空间和基于ECA(Event-Condition-Action)模式的状态转移规则。 在基于事件驱动模型的BPEL引擎架构原理的指导下，我们设计并实现了基于事件驱动模型的OnceBPEL2.0引擎系统。并且，我们对采用多线程模型实现的OnceBPEL1.0系统和采用事件驱动模型实现的OnceBPEL2.0系统进行了性能测试和分析比较。从我们的测试数据和分析结果可以看出，采用事件驱动模型的OnceBPEL2.0系统比采用多线程模型的OnceBPEL1.0有了较大的性能提升。

生成诊断公式的有限状态进程等价验证

分析有限状态进程互模拟等价判定技术,探讨了诊断公式的生成问题。给出了将有限状态进程转化为带标号的迁移系统,修改了Paige和Trajan求解最粗划分的算法,使其适用于带标号的迁移系统。给出生成Hennessy-Milner逻辑描述的诊断公式的算法,当两个进程不能互模拟时,产生两个诊断公式。算法的时间复杂度为O(mlogn),空间复杂度为O(m+n)。

Structures and physical properties of n=3 Ruddlesden-Popper compounds Ca4Mn3-xNbxO10 (0 <= x <= 0.2)

The Ruddlesden-Popper series of compounds Ca4Mn3-xNbxO10(x = 0-0.2) have been prepared by solid-state methods. Structural, magnetic, electrical, and magnetoresistive studies were performed on the compounds. Nb doping caused increases in both unit cell volume and octahedral distortion. The magnetization measurements indicated that the doped samples displayed ferromagnetism-like behavior, which could be explained by the double-exchange interaction between Mn4+ and Mn3+ induced by the charge-compensation effect.

一种输电线路巡检机器人控制系统的设计与实现

介绍了一种超高压输电线路巡检机器人控制系统的设计与实现方法.根据巡检作业任务的要求,采用遥控与局部自主相结合的控制模式实现巡检机器人沿线行走及跨越障碍.设计了巡检机器人有限状态机模型,实现了机器人遥控与局部自主控制的有机结合.采用基于激光传感器定位的方法实现了巡检机器人的自主越障控制.实验结果表明,该机器人可实现沿线行走及自主跨越障碍,从而验证了控制系统设计的有效性与合理性.

基于有限状态机的空间对接仿真平台控制系统设计

给出了一种基于分层式有限状态机的五自由度空间对接仿真平台控制系统设计方法,对状态机进行了扩展定义.增加了一个定义于状态上的变量属性集合,使其有利于系统的代码实现.结合控制系统采用的10 ms定时中断机制,将状态机层次划分到了可以分析每个10 ms硬件中断程序所需实现的控制功能状态及其转移、继承关系的程度,可以更清晰地设计出中断程序所需要的构成结构.系统的实际应用结果证明了上述方法的有效性.

双足爬壁机器人壁面凹过渡步态规划研究

针对腿足式爬壁机器人在壁面过渡时的步态规划问题,以一种真空吸附式双足爬壁机器人为研究对象,在步态分析的基础上,基于有限状态机建立了机器人的步态模型,进而提出了基于加权插值和BP神经网络的双足爬壁机器人壁面凹过渡在线步态规划算法,为提高机器人壁面过渡的自主控制能力奠定了基础.仿真分析和实验结果表明,该步态规划算法对于实际的机器人系统是有效的和可行的.

一个面向复杂任务的多机器人分布式协调系统

基于多智能体系统理论，研讨在非结构，不确定环境下面向复杂任务的多机器人分布式协调系统的实现原理，方法和技术。提出的递阶混合式协调结构，基于网络的通讯模式和基于有限状态机的规划与控制集成方法，充分考虑了复杂任务和真实自然环境的特点，通过构建一个全实物的多移动机器人实验平台，对规划，控制，传感，通讯，协调与合作的各关键技术进行了开发和集成，使多机器人分布式协调技术的研究直接面向实际应用，编队和物料搬运的演示实验结果展示了多机器人协调技术的广阔应用前景。