Designing multiprotocol label switching networks

Multiprotocol label switching adds to the capabilities of IP networks in several ways. Despite new capabilities, MPLS technology has much in common with ordinary IP networks. In turn, the design process for MPLS networks has much in common with the design of any IP network. This article examines MPLS and IP technology with particular emphasis on what is common between them. The common design steps of MPLS networks and other IP networks are outlined briefly, and those issues specific to MPLS networks are covered in more detail. This article emphasizes MPLS point of presence design, routing design issues for MPLS, and provisioning of sufficient label space     

A heuristic for decomposition in multilevel logic optimization

A heuristic for finding common subexpressions of given Boolean functions based on Shannon-type factoring is proposed. This heuristic limits the search space considerably by applying a top-down approach in which synthesis of a Boolean network flows from the primary outputs to the primary inputs. The common subexpressions and their complements in N variables are extracted before common subexpressions and their complements in (N-1) variables. This decomposition of the network depends on a permutation of Boolean variables and has a polynomial complexity for restricted extraction of complements. A multilevel logic optimization system, MULTI, has been implemented using this heuristic. Good results on several benchmark circuits show its effectiveness     

Transistor behavior at high frequencies

The tee equivalent circuit for junction transistors has been modified to take account of electric field in the base region. This electric field is the result of a graded impurity density in the base region of the transistor. It is shown that a graded base improves the high-frequency performances of the common base stage; however, the improvement in common emitter performance is considerably less because of the increased "excess" phase which accompanies the improved high-frequency performance. The complex hybrid parameters are calculated for the common base and common emitter configurations; these calculations take into account the parasitic interterminal capacities of the transistor. The common emitter calculations are compared to measured data, and substantial agreement is obtained.     

电信端传导共模骚扰测试问答

以问答形式探讨广受关注的有关电信端传导共模骚扰测试的问题,介绍了电信端传导共模骚扰来源、阻抗稳定网络的作用及选用、电信端口和传输电缆分类、测试原则及测试安排的案例、测试软件影响和辅助设备要求。     

建筑结构工程钢筋混凝土结构加固设计常用方法探讨

本文介绍了建筑工程钢筋混凝土结构常用的加固方法,分析各种加固方法的优劣性及加固中加固人员所需要注意的常见问题,对建筑工程钢筋混凝土结构常见的加固设计方案进行比较分析。     

基于云计算的电子政务公共平台的功能和性能要求

基于云计算的电子政务公共平台是下一代信息化基础设施的重要组成部分,也是电子政务服务的支撑平台。为使组建的基于云计算的电子政务公共平台更好地满足政务部门的需要,需要规范基于云计算的电子政务公共平台的功能和性能。本文介绍了基于云计算的电子政务公共平台的功能和性能要求。     

精密零件氢气保护扩散钎接焊工艺研究

本文阐述的是,铜及其合金精密零件氢气保护扩散钎接焊工艺问题。这是一种界于TLP扩散焊和钎焊工艺之间的一种新型先进工艺,兼有两者之长。文中对扩散元素,共晶相系的选取、筛选和扩散——共晶反应过程机理分析作了重点论述,并对其接头组织,性能和焊接质量及本工艺的应用情况作了简要介绍。     

VxWorks下基于辅助时钟的通用定时器设计

VxWorks操作系统以其强实时性、可剪裁性等特点得到了广泛应用,但其并未提供通用的定时器模块。为解决某机载发射装置控制盒中VxWorks系统的精确定时问题,文中在分析多种定时方式的基础上,利用辅助时钟中断,通过创建定时节点,构造节点链表,设计了基于辅助时钟的通用定时器模块。经测试表明,该模块实现了毫秒级定时,满足了某发射装置的定时需求,并为今后类似系统的精确定时需求提供了方便。     

并行LED驱动电路的多SITE测试方法

并行LED驱动电路的多SITE测试对系统资源和测试速度有较高要求,文章介绍了并行LED驱动电路的工作方式、常见测试参数以及常见参数的测试方法。探讨了在中测阶段进行多SITE测试的方法,对该类电路多SITE测试中的一些难点进行了分析,并提出了一种新的测试方案。该测试方案通过资源复用的方式,采用最新的切换技术,可以有效提高测试准确性,并提高测试效率,降低测试成本。最后介绍了多SITE测试的一些其他要点以及最终的测试结果。     

Antenna Evaluation by Normalized Analogical Technique

The impedance of a vertical antenna (monopole) normalized to 189 ?, or its reciprocal, is equal to that of three different antennas in half space. This equality derived by the formulation of a common effective height, and therefrom a common Q, offers a technique for antenna evaluation in electromagnetic compatability (EMC).     

变频器的组成与常见故障及维修对策

本文介绍了变频器组成结构及相应故障与维修对策。     

用共有峰率和变异峰率双指标序列分析法分析百合的红外指纹图谱

利用共有峰率和变异峰率两个指标,以不同产地的百合样品的红外指纹图谱为标准,计算出10个样品之 间的共有峰率和变异峰率,建立了共有峰率和变异峰率双指标序列分析方法。结果表明,产地相近的L1与L2之间、L8与L7、 L3之间具有很高的共有峰率和很低的变异峰率;产地相近的另外几个区域的百合L9与L8、L5、L6之间和L10与L5之间的共 有峰率均≥80.0%,变异峰率均≤25.0%;产地相距较远的L1与L10、L6、L9、L3的共有峰率≤60.0%, 变异峰率≥15.8%。该方法比色谱鉴别法更加简便、快速,可以准确地区分不同产地的百合,也为中药质量评价 提供了一种新方法。     

Packing algorithm inspired by gravitational and electromagnetic effects

Wireless Networks - This paper introduces a faster and more efficient algorithm for solving a two-dimension packing problem. This common optimization problem takes a set of geometrical objects and...     

A Space Vector Modulation Scheme to Reduce Common Mode Voltage for Cascaded Multilevel Inverters

Multilevel inverters can reduce the common mode voltage generated. Schemes have been reported for multilevel inverters that reduce the common mode voltage. However, most of the schemes result in reduced modulation depth, high switching losses, and high harmonic distortion. This paper proposes a space-vector modulation scheme to reduce common mode voltage for cascaded multilevel inverters. The proposed scheme can increase the voltage range of operation by about 17% and can produce lower total harmonic distortion than the previously proposed schemes. The scheme is explained for five-level inverter. The scheme can be easily extended to a n-level inverter. Both experimental and simulation results are provided.     

A fast noise and Z-parameter transformations between common emitterand common base InP DHBT

A new approach has been developed that uses only a simple set of formulas to transform noise and Z-parameters between common emitter and common base configurations. This technique is based on the typical T-model of InP double-heterojunction bipolar transistor and calculated results agree with the experimental results, demonstrating that this approach is useful for many broad-band low-noise communication circuit designs     

The new possibilities of telephone switching

Switching system architectures have evolved to be responsive to the needs of the user. Their design has been constrained by the existing environment which treats terminals, transmission channels, and switching entities as separate "black boxes." Telephone switching circuits have used relatively expensive discrete components, and hence, system designers used common control techniques to minimize the system cost. This was done by providing the circuits in common whenever this was possible. Such common circuits were associated with a switched path for the period of time for which the functions of the circuit were required. This was followed by "one at a time" operation and by the use of stored program controls. The advent of low-cost electronic circuit components has resulted in the application of digital techniques to switching systems. For the first time, the combination of switching and transmission is possible. This is the near-term objective. The long-term objective, made possible by forecasts of low-cost memory and electronic gate circuits, is the combination of switching, transmission, and the terminals. This will result in much more complex terminals.     

MIRAI architecture for heterogeneous network

One of the keywords that describe next-generation wireless communications is "seamless." As part of the e-Japan Plan promoted by the Japanese Government, the Multimedia Integrated Network by Radio Access Innovation project has as its goal the development of new technologies to enable seamless integration of various wireless access systems for practical use by 2005. This article describes a heterogeneous network architecture including a common tool, a common platform, and a common access. In particular, software-defined radio technologies are used to develop a multiservice user terminal to access different wireless networks. The common platform for various wireless networks is based on a wireless-supporting IPv6 network. A basic access network, separated from other wireless access networks, is used as a means for wireless system discovery, signaling, and paging. A proof-of-concept experimental demonstration system is available     

支持多模块的DVB通用接口的实现

具有支持多模块的DVB通用接口是机顶盒的必然趋势。介绍DVB通用接口标准，阐述接口中各层的功能，给出一个实现支持多模块的DVB—CI接口的实例及最后的测试结果。     

脉冲雷达发射机常见故障分析与排除

随着雷达的广泛应用,其性能也在快速提高,而对脉冲雷达发射机中电子元器件常见故障分析与排除研究较少。作为雷达的核心部件之一,脉冲雷达发射机是雷达性能以及安全使用的关键。文中针对脉冲雷达发射器的工作原理以及电子元件易出现的故障现象和原因进行了分析,并提出了相应的解决措施,为雷达的安全使用提供了依据。     

Simultaneous Estimation and Testing of Sources in Multiple MEG Data Sets

The proposed Extended Couple Dipole Model (ECDM) is a trilinear component model that can be used to analyze multiple, related MEG data sets simultaneously. Related MEG data sets are data sets that contain activity of the same sources or activity of sources that have proportional source amplitudes. The simultaneous model uses a set of common sources and a set of common source time functions (wave shapes) to model the measured data in each data set. The set of common sources contains all sources that are active in at least one of the data sets to be analyzed. The number of common spatial and temporal components is specified by the user. The model for each data set is a linear combination of these common spatial and temporal components. This linear combination is estimated in a coupling matrix. Unlike the Coupled Dipole Model, where the user selects certain entries of the coupling matrix to be zero, the entire coupling matrix is estimated in the ECDM. This yields a more objective and statistically transparent estimation method, of which the identifiability constraints do not depend on the user's chosen design as in the CDM. CramÈr–Rao Bounds are derived for the ECDM, and the significance of the estimated source activity is computed and illustrated by confidence regions around estimated source time functions.