HEPAPS:A PCB Automatic Placement System

HEPAPS is composed of constructive placement,improving placement,equivalence pins reassignment and same function elements reassignment.Based on practical demands,this paper implements the constructive procedure within a set of engineering constraints and resolves the reassignment problems of equivalence and same function elements.A new topological improving method combined min-cut algorithm with simulated annealing algorithm is presented.In addition,the two-dimensional relaxed method is introduced to solve the geometrical optimization problem.     

Sensor Placement for Sensing Coverage and Data Precision in Wireless Sensor Networks

We present a novel paradigm of sensor placement concerning data precision and estimation. Multiple abstract sensors are used to measure a quantity of a moving target in the scenario of a wireless sensor network. These sensors can cooperate with each other to obtain a precise estimate of the quantity in a real-time manner. We consider a problem on planning a minimum-cost scheme of sensor placement with desired data precision and resource consumption. Measured data is modeled as a Gaussian random variable with a changeable variance. A gird model is used to approximate the problem. We solve the problem with a heuristic algorithm using branch-and-bound method and tabu search. Our experiments demonstrate that the algorithm is correct in a certain tolerance, and it is also efficient and scalable.     

A novel adaptive backstepping design of turbine main steam valve control

The problem of transient stability for a single machine infinite bus system with turbine main steam valve control is addressed by means of a novel adaptive backstepping method in this paper. The recursive design procedure of the proposed controller is much simpler than that of the existing controller based on conventional adaptive backstepping method. In the system, the damping coefficient is measured inaccurately, and the reactance of transmission line also contains a few uncertainties. A nonlinear robust controller and parameter updating laws are obtained simultaneously. The system does not need to be linearized, and the closed-loop error system is guaranteed to be asymptotically stable. The design procedure and simulation results demonstrate the effectiveness of the proposed design.     

A simple method of tuning series cascade controllers for unstable systems

A simple method is proposed to design P/PI controllers for a series cascade control system for unstable first order plus time-delay （FOPTD） systems. In this paper, the controller design for unstable FOPTD systems cascaded in series with stable/unstable FOPTD systems is considered. The proposed method is based on equating the coefficients of corresponding powers of s and s2 in the numerator to α1 and α2 times those of the denominator of the closed-loop transfer function for a servo problem. The open loop system consists of an unstable FOPTD system cascaded in series with a stable/unstable FOPTD system. Only two tuning parameters （α1 and α2） are required for the design of controllers. The closed-loop performances are evaluated for both the servo and regulatory problems and the performances are found to be better than that of the well established synthesis method. The robustness for uncertainty in the model parameters is studied and compared with that of the controllers designed by the synthesis method.     

Robust H-infinity fuzzy control for uncertainMarkovian jump nonlinear singular systems withwiener process

This paper deals with the problems of robust stochastic stabilization and H-infinity control for Markovian jump nonlinear singular systems with Wiener process via a fuzzy-control approach. The Takagi-Sugeno (T-S) fuzzy model is employed to represent a nonlinear singular system. The purpose of the robust stochastic stabilization problem is to design a state feedback fuzzy controller such that the closed-loop fuzzy system is robustly stochastically stable for all admissible uncertainties. In the robust H-infinity control problem, in addition to the stochastic stability requirement, a prescribed performance is required to be achieved. Linear matrix inequality (LMI) sufficient conditions are developed to solve these problems, respectively. The expressions of desired state feedback fuzzy controllers are given. Finally, a numerical simulation is given to illustrate the effectiveness of the proposed method.     

QFT prefilter design for multivariable systems using interval constraint satisfaction technique

In this paper, a computationally efficient method is proposed for automated design of the prefilters for multivariable systems. In quantitative feedback theory （QFT） method, proposed by Horowitz, the prefilter is designed to achieve the desired tracking specifications. In the proposed approach, we pose the prefilter design problem as an interval constraint satisfaction problem and solve it using the well-established interval constraint satisfaction techniques. The proposed method finds optimal values of the parameters of fixed structure prefilter within the initial search domain. An approach based on prefilter synthesis for single-input single-output is already developed. The purpose of this paper is to extend this approach to QFT prefilter design for general multivariable systems. To validate the above design approach, we applied the method to a laboratory setup of magnetic levitation system.     

Nonlinear inversion-based output tracking control of a boiler-turbine unit

The capability to perform fast load_following has been an important issue in the power industry. An output tracking control system of a boiler_turbine unit is developed. The system is composed of stable inversion and feedback controller. The stable inversion is implemented as a feedforward controller to improve the load_following capability, and the feedback controller is utilized to guarantee the stability and robustness of the whole system. Loop_shaping H_∞ method is used to design the feedback controller and the final controller is reduced to a multivariable PI form. The output tracking control system takes account of the multivariable, nonlinear and coupling behavior of boiler_turbine system, and the simulation tests show that the control system works well and can be widely applied.     

Numerical optimization method for HJI equations derived from robust receding horizon control schemes and controller design

This paper addresses how to numerically solve the Hamilton-Jacobin-Isaac(HJI)equations derived from the robust receding horizon control schemes.The developed numerical method,the finite dierence scheme with sigmoidal transformation,is a stable and convergent algorithm for HJI equations.A boundary value iteration procedure is developed to increase the calculation accuracy with less time consumption.The obtained value function can be applied to the robust receding horizon controller design of some kind of uncertain nonlinear systems.In the controller design,the finite time horizon is extended into the infinite time horizon and the controller can be implemented in real time.It can avoid the on-line repeated optimization and the dependence on the feasibility of the initial state which are encountered in the traditional robust receding horizon control schemes.     

Nonlinear inversion-based output tracking control of a boiler-turbine unit

The capability to perform fast load-following has been an important issue in the power industry. An output tracking control system of a boiler-turbine unit is developed. The system is composed of stable inversion and feedback controller. The stable inversion is implemented as a feedforward controller to improve the load-following capability, and the feedback controller is utilized to guarantee the stability and robustness of the whole system. Loop-shaping H∞ method is used to design the feedback controller and the final controller is reduced to a multivariable PI form. The output tracking control system takes account of the multivariable, nonlinear and coupling behavior of boiler-turbine system, and the simulation tests show that the control system works well and can be widely applied.     

树形全光网络中波长转换器配置算法

配置有限数量的波长转换器使网络阻塞率最低,是全光网络中需要解决的一个关键问题.通过考虑网络的直径、中心以及节点和链路的通信量,采用网络分解和迭代的方法,提出树形网络中基于赋权直径的波长转换器配置算法、基于节点加权中心的波长转换器配置算法,以及基于光路加权中心的波长转换器配置算法.算法演示表明,提出的3个算法总是将波长转换器放置在阻塞率较高的节点上,从而大大降低网络整体阻塞率.     

高层次综合的实有化逻辑图自动生成关键技术的研究

研究的逻辑图自动生成系统是“九五”微电子重点科技预研项目的成果“实用化专用集成电路高层次自动化设计系统－Talent系统”的子系统,该系统通过对电路网表有效的识别与划分、逻辑单元的布局及互连信号线的布线等,自动生态具有一定逻辑功能且布局美观规范的逻辑原理图。该文重点研究逻辑图自动生成实用化过程中的关键技术,将人工智能基于规则的知识表示与形式化算法相结合,提出有效的自动布局方法;应用模式识别理论和方法解决逻辑图的自动布线问题,提出基于决策树的通道分配方法,并设计一套完整的规则体系;进而,文中给出详细的划分模型,并在此基础上,结合逻辑原理图的特点实现了两种有效的划分算法：（1）种子生成的构造式划分算法;（2）迭代改进划分算法。其中算法（1）的设计思想主要源于贪婪构造,而算法（2）则对经典的最小分割划分算法Kernigham－Lin算法进行改进。基于上述研究实现的逻辑图自动生成系统,能够在很短的时间内生成美观规范、可读性好的逻辑图,为整个系统实用化做出了贡献。     

岛式FPGA线长驱动快速布局算法

传统的FPGA布局箅法需要花费大量时间,影响了FPGA物理设计效率.为了在保证布局质量的前提下缩短布局时间,提出一种岛式FPGA快速布局算法.首先考虑终端传输的迭代二划分,然后进行最小费用流初始布局和低温模拟退火的布局优化.在每一个划分层次中,考虑了线网的终端对线网权重的影响;对于每一个划分的区域,使用最小费用流来确定初始的布局;在布局的最后阶段使用低温模拟退火来提高初始布局的质量.实验结果表明,该算法布局结果的质量高、速度快.     

云计算中能耗和性能感知的虚拟机优化部署算法

优化虚拟机部署是数据中心降低能耗的一个重要方法。目前大多数虚拟机部署算法都明显地降低了能耗,但过度虚拟机整合和迁移引起了系统性能较大的退化。针对该问题,首先构建虚拟机优化部署模型。然后提出一种二阶段迭代启发式算法来求解该模型,第一阶段是基于首次适应下降装箱算法,提出一种虚拟机优化部署算法,目标是最小化主机数;第二阶段是提出了一种虚拟机在线迁移选择算法,目标是最小化待迁移虚拟机数。实验结果表明,该算法能够有效地降低能耗,具有较低的服务等级协定(SLA)违背率和较好的时间性能。     

动态虚拟盘阵数据分布算法

尽管当今的磁盘等外存储设备容量增加得很快，但还是无法满足用户应用程序的需要；在性能上，外存储设备已经成为计算机系统的瓶颈；为此，在集群环境下，将分布式的外设构成动态虚拟盘阵系统是一种较好的解决方案，而数据分布算法是动态虚拟研究的一项重要内容。也就是说，采用优化的数据分布算法，使得盘阵的性能和容量随盘阵的扩展而扩展。研究的主要工作是综述以往对动态盘阵数据分布算法，并对以往SCADDAR算法进行了扩充，提出了D／H(Double／Halve)数据分布算法。     

Cuckoo search based resource optimization of datacenters

With advancements in virtualization technology, datacenters are often faced with the challenge of managing large numbers of virtual machine (VM) requests. Due to this large amount of VM requests, it has become practically impossible to search all possible VM placements in order to find a solution that best optimizes certain design objectives. As a result, managers of datacenters have resorted to the employment of heuristic optimization algorithms for VM placement. In this paper, we employ the cuckoo search optimization (CSO) algorithm to solve the VM placement problem of datacenters. Firstly, we use the CSO to optimize the datacenter for the minimization of the number of physical machines used for placement. Secondly, we implement a multiobjective CSO algorithm to simultaneously optimize the power consumption and resource wastage of the datacenter. Simulation results show that both CSO algorithms outperform the reordered grouping genetic algorithm (RGGA), the grouping genetic algorithm (GGA), improved least-loaded (ILL) and improved FFD (IFFD) methods of VM placement.     

基于遗传算法的布局问题求解

布局问题是VLSI布图设计中的重要问题,传统的方法很难得到满意的解答。针对该问题,文中提出了一个基于遗传算法的求解方法,并将它应用到VLSI门阵列模式布局设计中,构造了一个较完备的综合布局目标函数,引入并定义了通道拥挤度。实验结果表明,所提出的方法能在较短的时间内提供优化解,为VLSI布局设计提供了一种新的思路。     

Placement Strategies for Internet-Scale Data Stream Systems

Optimally assigning streaming tasks to network machines is a key factor that influences a large data-stream-processing system's performance. Although researchers have prototyped and investigated various algorithms for task placement in data stream management systems, taxonomies and surveys of such algorithms are currently unavailable. To tackle this knowledge gap, the authors identify a set of core placement design characteristics and use them compare eight placement algorithms. They also present a heuristic decision tree that can help designers judge how suitable a given placement solutions might be to specific problems.     

A performance guarantee heuristic for electronic components placement problems including thermal effects

In this work, Benders decomposition algorithm is used to deal with a computer motherboard design problem. Amongst all the possible formulations for the component placement problem, the chosen one creates an instance of the extensively studied Quadratic Assignment Problem (QAP). This problem arises as a great challenge for engineers and computer scientists. The QAP inherent combinatorial structure makes the most efficient optimization algorithms to exhibit low performance for real size instances. It is also considered here the important addition of linear costs. This approach is directly responsible for the performance gain presented by our decomposition method. Coupled with the placement problem, it is under investigation the maximum temperature rising on the board surface. In order to solve the Energy Conduction Equation the Finite Volume Method is implemented, becoming possible to derive a secondary quality solution criterion. A set of test instances is then solved and the corresponding results are reported.     

An augmented Lagrangian method for VLSI global placement

By ignoring some cell overlaps, global placement computes the best position for each cell to minimize the wirelength. It is an important stage in very large scale integration (VLSI) physical design, since circuit performance heavily depends on the placement results. In this paper, we propose an augmented Lagrangian method to solve the VLSI global placement problem. In the proposed method, a cautious dynamic density weight strategy is used to balance the wirelength objective and the density constraints, and an adaptive step size is used to obtain a trade-off between runtime and solution quality. The proposed method is tested on the IBM mixed-size benchmarks and the International Symposium on Physical Design 2006 placement contest benchmarks. Experimental results show that our global placement method outperforms the state-of-the-art placement approaches in terms of solution quality on most of the benchmarks.