VLSI栅阵列单元生成系成

本文介绍一个新的ＶＬＳＩＣＭＯＳ电路栅阵列布图系统ＧＭＳ（ＧａｔｅＭａｔｒｉｘｌａｙｏｕｔＳｙｓｔｅｍ），它可以作为单元生成器在ＶＬＳＩ布图中自动产生基本单元。ＧＭＳ的布图过程包括：栅排序、线网分配和版图压缩，在考虑了许多实际约束条件的基础上，ＧＭＳ使用了一个新的栅排序算法，对Ｌｉ［６］算法做了较大改进，ＧＭＳ还把线网分配问题，转化为扩展的一维分配问题，在给出扩展一维分配问题定义的基础上，开发了一个线网分配算法，取得了较好的结果，ＧＭＳ允许用户对布图结果作叠代改进，对布图结果进行了压缩，从而减小了布图面积，ＧＭＳ已在ＭｉｃｒｏＶａｘＩＩ上用Ｃ语言实现，我们测试了许多实例，取得了较好的结果。     

A generalized state assignment theory for transformations on signal transition graphs

In this article, we propose a global assignment theory forencoding state graph transformations. A constraint satisfaction framework is proposed that can guaranteenecessary and sufficient conditions for a state graph assignment to result in a transformed state graph that is free of critical races. Performing transformations at the state graph level has the advantage that the requirements imposed on the initial STG are very weak. Unlike previous methods, the initial STG need not be a live, safe, nor a free choice net. The only requirement is that the corresponding initial state graph is finite, connected, and has a consistent state assignment. Hence, a very broad range of signal transition graphs can be synthesized. The transformations achievable using the proposed framework correspond to very complex transformations on signal transition graphs. Even transformations that convert a free choice net into a correct non-free choice net and a 1-safe net into a correct 2-safe net are feasible. Addition of transitions that do not follow the Petri net firing rule is also possible. Even though our method can search a large solution space, we will show that it is possible to solve the problem in an exact way in acceptable CPU times in many practical cases.Research supported by the ESPRIT 2260 (SPRITE) program of the EC.     

Net-based force-directed macrocell placement for wirelength optimization

We propose a net-based hierarchical macrocell placement such that "net placement" dictates the cell placement. The proposed approach has four phases. 1) Net clustering and net-level floorplanning phase: a weighted net dependency graph is built from the input register-transfer-level netlist. Clusters of nets are then formed by clique partitioning and a net-cluster level floorplan is obtained by simulated annealing. The floorplan defines the regions where the nets in each cluster must be routed. 2) Force-directed net placement phase: a force-directed net placement is performed which yields a coarse net-level placement without consideration for the cell placement. 3) Iterative net terminal and cell placement phase: a force-directed net and cell placement is performed iteratively. The terminals of a net are free to move under the influence of forces in the quest for optimal wire length. The cells with high net length cost may "jump" out of local minima by ignoring the rejection forces. The overlaps are reduced by employing electrostatic rejection forces. 4) Overlap removal and input/output (I/O) pin assignment phase: Overlap removal is performed by a grid-based heuristic. I/O pin assignment is performed by minimum-weight bipartite matching. Placements generated by the proposed approach are compared with those generated by Cadence Silicon Ensemble and the O-tree floorplanning algorithm. On average, the proposed approach improves both the total wire length and longest wire length by 18.9% and 28.3%, respectively, with an average penalty of 5.6% area overhead.     

有关无功负荷最优分配的一个常用算例的修正

本文讨论了"电力系统分析"课程中有关无功功率最优分配的一个常用算例,指出了目前解析中的问题,并作了修正.由于系统中没有平衡节点来补充线路中的有功损失,确定各发电机的有功出力时需要考虑有功网损的影响.分配无功负荷时应将无功平衡方程、有功平衡方程和等微增率准则建立的方程联立求解.计算结果显示,考虑了线路有功网损之后,能够同时满足有功功率平衡和无功功率平衡,无功负荷的最优分配与有功负荷的分配有关.     

广电城域网中IP地址的规划

介绍广电城域网IP地址规划、分配的原则和方法以及利用IP地址计算器工具软件协助实现IP地址的计算等。     

大容量广电网的P圈启发式算法研究

结合广电网大容量的发展要求,考虑较为复杂的网状网结构,网络生存性问题日益凸显。对经典的预置圈(P圈)容量算法进行了改进,并选用COST239网络拓扑对改进算法进行编程仿真。结果证明,改进算法在减少预置圈数量的同时能够提高资源利用率,性能有所提高,可以较好地解决广电网的生存性问题。     

串扰噪声约束下的过点分配算法

提出了一种在过点分配阶段解决噪声耦合效应问题的算法.该算法采用优先队列同拆线重布策略相结合的方法,控制由互连线耦合电容引起的串扰噪声.算法中,首先按照线长和约束限制,将线网划分到若干个优先队列中.然后,将每个优先队列的过点分配问题转换为线性分配问题.在完成一个线网队列的分配后,通过过点分配后处理过程检查串扰约束满足情况,对违反约束的线网对进行拆除,放入后续线网队列进行重新分配.实验数据表明,该算法能够取得好的效果.     

串扰噪声约束下的过点分配算法

提出了一种在过点分配阶段解决噪声耦合效应问题的算法.该算法采用优先队列同拆线重布策略相结合的方法,控制由互连线耦合电容引起的串扰噪声.算法中,首先按照线长和约束限制,将线网划分到若干个优先队列中.然后,将每个优先队列的过点分配问题转换为线性分配问题.在完成一个线网队列的分配后,通过过点分配后处理过程检查串扰约束满足情况,对违反约束的线网对进行拆除,放入后续线网队列进行重新分配.实验数据表明,该算法能够取得好的效果     

Comment/correction: dependability modeling using Petri nets

Two arcs are missing in a figure of Malhotra & Trivedi (see ibid., vol. 44, p. 428-40, 1995); these arcs are necessary for the proper functioning of the generalized stochastic Petri net (GSPN). Also, priorities of immediate transitions in that figure must be clearer. This note presents a correctly drawn GSPN and describes the priority assignment to immediate transitions in this GSPN     

Extended global routing with RLC crosstalk constraints

In this paper, we study an extended global routing problem with RLC crosstalk constraints. Considering simultaneous shield insertion and net ordering, we propose a multiphase algorithm to synthesize a global routing solution with track assignment to satisfy the RLC crosstalk constraint at each sink. The key algorithm phase is global routing synthesis with shield reservation and minimization based on prerouting shield estimation. Experiments using large industrial benchmarks show that compared to the best alternative with postrouting shield insertion and net ordering, the proposed algorithm with shield reservation and minimization reduces the congestion by 18.4% with a smaller runtime. To the best of our knowledge, this is the first in-depth study on global routing synthesis with RLC crosstalk constraints.     

长线网预处理的过点分配算法

提出了一个长线网预处理的过点分配算法.该算法不仅考虑了过点和物理连接端的连接费用、总体布线单元边界上不同过点之间的互斥费用,而且考虑了同一线网不同过点之间的错位费用.实验结果表明,该算法极大地提高了详细布线阶段的布线质量和速度,特别是对于长线网而言,效果更为显著.     

长线网预处理的过点分配算法

提出了一个长线网预处理的过点分配算法.该算法不仅考虑了过点和物理连接端的连接费用、总体布线单元边界上不同过点之间的互斥费用,而且考虑了同一线网不同过点之间的错位费用.实验结果表明,该算法极大地提高了详细布线阶段的布线质量和速度,特别是对于长线网而言,效果更为显著.     

Board-level multiterminal net assignment for the partial cross-bar architecture

This paper presents a satisfiability-based method for solving the board-level multiterminal net routing problem in the digital design of clos-folded field-programmable gate array (FPGA) based logic emulation systems. The approach transforms the FPGA board-level routing task into a Boolean equation. Any assignment of input variables that satisfies the equation specifies a valid routing. We use two of the fastest Boolean satisfiability (SAT) solvers: Chaff and DLMSAT to perform our experiments. Empirical results show that the method is time-efficient and applicable to large layout problem instances.     

深亚微米条件下的多层VLSI／MCM层分配的遗传算法

本文提出了一个深亚微米条件下的多层ＶＬＳＭＣＭ有约束分层层分配的遗传算法。该算法分为两步：首先进行超层分配，使各线网满足Ｃｒｏｓｓｔａｌｋ约束，且超层数目最少；然后进行各超层的通孔最少化二分层。与目前的层分配算法相比，该遗传算法具有目标全面，全局优化能力强等特点，是一种可应用于深亚微米条件下的ＩＣ ＣＡＤ的有效分层方法。     

Pricing and power control in a multicell wireless data network

We consider distributed power control in a multicell wireless data system and study the effect of pricing transmit power. Drawing on the earlier work of Goodman and Mandayam (see IEEE Personal Commun. Mag., vol.7, p.48-54, 2000), we formulate the QoS of a data user via a utility function measured in bits per Joule. We consider distributed power control, modeled as a noncooperative game, where users maximize their utilities in a multicell system. Base station assignment based on received signal strength as well as received signal-to-interference ratio (SIR) are considered jointly with power control. Our results indicate that for both assignment schemes, such a procedure results in an inefficient operating point (Nash equilibrium) for the entire system. We introduce pricing of transmit power as a mechanism for influencing data user behavior and our results show that the distributed power control based on maximizing the net utility (utility minus the price) results in improving the Pareto efficiency of the resulting operating point. Variations of pricing based on global and local loading in cells are considered as a means of improving the efficiency of wireless data networks. Finally, we discuss the improvement in utilities through a centralized scheme where each base station (BS) calculates the best SIR to be targeted by the terminals it is assigned     

基于量子遗传算法的航空通信频率动态分配

为了更加有效地对航空通信频率进行分配,提出了一种基于量子遗传算法的航空通信频率动态分配方法。通过对频率动态分配思路进行分析,建立了频率动态分配框架,给出了频率动态分配的具体流程。在此基础上,讨论了航空通信频率动态分配问题,定义了航空通信频率动态分配约束条件,建立了航空通信频率动态分配模型。最后,运用量子遗传算法和遗传算法对算例进行仿真对比。结果表明：量子遗传算法在种群适应度和收敛速度上具备明显的优越性,频率动态分配模型能够根据不同种群数量条件动态调整适应度,能够较好满足航空通信频率分配问题动态性、准确性、时效性等实践运用要求。     

智能雷达干扰决策支持系统中资源分配技术

雷达干扰资源分配是否合理是影响雷达干扰效果的重要因素。本文详细介绍了智能雷达干扰决策支持系统（IDSSRJ）中的几种雷达干扰资源分配技术,包括多级优化动态资源分配技术、全空间搜索以及随机抽样资源分配技术。     

Layer assignment for printed circuit boards and integrated circuits

The layer assignment problem arises in printed circuit board (PCB) and integrated circuit (IC) design. It involves the assignment of interconnect wiring to various planes of a PCB or to various layers of interconnect wires in an IC. This paper reviews basic techniques for layer assignment in both PCBs and ICs. Two types of layer assignment are considered: (1) constrained layer assignment in which routing of interconnections is given and the objective is to assign wires to specific layers, and (2) unconstrained, or topological, layer assignment, in which both the physical routing of interconnections and assignment of the wires to layers is sought. Various objective functions, such as via minimization and minimization of signal delays through interconnect lines are discussed     

A Two-Step Heuristic Algorithm for Minimum-Crosstalk Routing Resource Assignment

This brief deals with the crosstalk minimization problem in an integrated routing resource assignment stage containing several operations between global routing and detailed routing. A two-step heuristic algorithm consisting of coarse assignment and detailed assignment is proposed. In coarse assignment, shield lines are planned based on the chromatic number of a light coarse coupling graph, and the assignment of segments that are longer than a predefined threshold is solved with semidefinite programming. In detailed assignment, a strategy based on a dynamic priority queue is introduced to mitigate common problems caused by sequential routing. Experimental results on a set of benchmarks show significant reduction in coupling length between sensitive segments compared to a prevalent bipartite-matching-based algorithm     

基于遗传算法的多侦察传感器目标优化分配

针对电子战系统试验与训练任务中的多个侦察传感器的目标分配实际应用,讨论了多目标分配规划问题,建立了一对多目标分配规划模型。将多个侦察传感器的总侦察效率作为目标函数,分析了相关约束条件,采用遗传算法进行求解得到了优化后的侦察目标分配方案,为合理地进行武器系统的作战目标分配研究以及为试验与训练任务节约资源、提高效率提供了有益的帮助。