Modelling digital circuits with delays by Stochastic Petri Nets

The analysis of the behaviour of digital circuits, with special reference to signal propagation delays, is performed by means of the Petri Nets (PN) formal model. In particular, concurrent signal changes in the circuit which may give rise to possible functional errors such as races or hazards, are represented by this model. Moreover, the delays, assumed to be random variables with assigned probability distributions and Stochastic Petri Nets (SPN), which are an extension of classical PN's, are employed. By the resulting model, a great flexibility of representation is achieved, matching also the requisites of the particular technology employed.It is also possible to account for time varying inputs both in combinational and sequential circuits, reconvergent fanouts and conflicting events.The algorithm derived from this model allows to obtain a static logic verification of the circuit and exhibits shorter simulation times as compared to those of classical simulators.     

工作流挖掘与Petri网表示的对偶交换

将对偶交换的观点引入工作流挖掘的研究可以获得新的认识。其在工作流结构验证中并行和选择互换后仍保持结构的正确性。工作流挖掘α算法先挖掘选择结构,余下并行结构,通过对偶交换得到算法,先挖掘并行结构,余下选择结构,算法能够减少非自由选择结构。不同情况下两种算法结果比较取优,能够使工作流挖掘的并行和选择的嵌套关系更为简练。以任务为变迁的Petri网能够最简洁地表示α算法挖掘结果,以任务为库所的Petri网能够最简洁地表示算法的挖掘结果。这两种Petri网表示也体现出对偶性。     

Petri网理论及其在自动制造系统中的应用

文中详细综述了Ｐｅｔｒｉ网理论的发展、应用领域、基本定义以及分析方法和建模方法。重点介绍了Ｐｅｔｒｉ网在自动制造系统控制中的应用、发展方向，指出了Ｐｅｔｒｉ网在自动制造系统中的应用前景和作者的看法     

主体计划的Petri网方法及正确性验证

主体计划的生成问题是多主体系统实现的一个关键问题.为了实现多主体系统中的计划自动生成以及对生成的计划进行验证,以任务有效分解的Petri网模型为基础,提出了计划提取的方法并对相关的正确性运用同步器进行验证.首先,通过对网系统的可达性分析得到所有计划的集合,组成多主体系统的计划库.其次,根据同步网的相关思想,对计划库中的每一个计划的正确性进行了形式化的验证,从而为多主体系统的实现提供了保证.     

基于模型构件和Petri网的企业整体建模方法

模型复用是提高建模质量和效率的主要手段，而模型构件是复用的核心和基础。在对构成企业这一社会技术系统的各种要素进行分析的基础上，首先将组成系统的要素分为功能构件、资源构件和人力构件等三类模型构件。然后以Petri网作为建模工具，给出一种以模型构件作为变迁和库所的企业整体建模方法。由此方法建立的企业模型具有良好的整体性和可复用性，能够全面反映构成企业的技术实体、资源和人等要素的配置和相互关系。最后给出一个企业建模实例。     

随机高级Petri网用于计算机网络传输协议的模型与性能评价

本文讨论了具有标记变量的随机高级Ｐｅｔｒｉ网（ＳＨＬＰＮ）以及标识类型，标记变量和等价标记变量的概念，给出了具有等价标记变量可达树构造算法，并证明了等价标记变量可达集与合并状态的马尔可夫链状态空间之间的同构。本文着重描述了ＳＨＬＰＮ在计算机网络传输协议的模型与性能评价中扩，通过这个例子充分显示了这些概念和算法的有效性。     

Implementation of a Remote Hierarchical Supervision System Using Petri Nets and Agent Technology

For remote control systems, certain human operations may violate desired requirements and result in catastrophic failure. For such human-in-the-loop systems, this paper implements a hierarchical supervision system to guarantee that remote human-issued commands meet required specifications. In the presented scheme, Petri nets are applied to model, design, and verify both the local controller and the remote supervisor. Then, the agent technology is adopted to implement the supervisor as an intelligent agent for an online supervision of the remote control system. Hence, undesired resource conflicts and deadlock states can be avoided. An application to a flexible manufacturing system controlled over the Internet is provided to illustrate the developed approach. Implementation results show that by applying the presented hierarchical scheme, the supervisor has a more compact model with fewer states. Moreover, fewer request/response transmissions are consumed so that the effects of time delays and packet losses across the Internet could be moderated     

基于Petri网的SET双重签名建模与分析

双重签名是安全电子交易协议的一个重要技术,它将摘要和数字签名结合起来,使得交易中的各方仅得到部分消息即可完成验证从而达成多方协议。论文利用Petri网对双重签名进行建模和形式化描述,并就安全性对此模型进行了分析。     

门户网自助系统的扩展有色Petri网建模与分析

文章探讨了一种基于扩展有色Petri网的门户网自动生成系统,详细论述了有色Petri网与面向对象技术的融合方式,给出了面向对象的扩展有色Petri网的映射规则和形式化定义,并构建了门户网自动生成系统的ECPN模型,最后利用状态空间法和系统在实际生产中的效率统计,证明了模型的可用性、高效性。     

扩展PN在弹炮结合武器系统防空作战过程建模的应用

研究建立弹炮结合武器系统防空作战过程的PN模型。首先引入CTPN概念,然后进行作战过程的组件结构建模,以此为基础,分别建立组件的CTPN模型,最后建立作战过程的TPN模型,并对时间约束进行分析。研究表明对于复杂的离散事件动态系统,CTPN是一种有效的建模工具。     

Application of Petri Nets and Lagrangian Relaxation to Scheduling Automatic Material-Handling Vehicles in 300-mm Semiconductor Manufacturing

This paper deals with vehicle-scheduling problem (VSP) in an automatic material-handling environment in 300-mm semiconductor wafer manufacturing. We adopt Petri nets (PNs) modeling techniques to model the complicated coupling dynamics among transport jobs and overhead hoist transport (OHT) vehicles in a 300-mm OHT loop. The congestion phenomenon among OHT vehicles is captured. With help of the PN models, we formulate the OHT VSP as an integer programming problem whose objective is to schedule OHT vehicles to transport jobs such that average job completion time is minimized. Instead of solving for the optimal solution, we develop a solution methodology to generate a feasible schedule efficiently. A Lagrangian relaxation step is first taken to decompose the PN-based, integer programming problem into individual job-scheduling subproblems. To reduce computation efforts in solving each subproblem optimally, we develop an approximation method to solve each job subproblem by utilizing a reduced PN model of the job. Lagrangian multipliers are then optimized by a surrogate subgradient method. A heuristic algorithm is developed to adjust the dual solution to a feasible schedule. Numerical results demonstrate that our solution methodology can generate good schedules within a reasonable amount of computation time for realistic problems. Compared to a popular vehicle-dispatching rule, our approach can achieve in average 32% improvements on the average delivery time in our realistic test cases.     

A Case Study for the Application of Deterministic and Stochastic Petri Nets in the SoC Communication Domain

This paper presents an approach utilizing deterministic and stochastic Petri nets (DSPN) to analyze on-chip communication. In order to demonstrate the suitability of this approach, the on-chip communication structure of two examples featuring typical system-on-chip (SoC) communication conflicts like competition for common communication resources have been studied. A state-of-the-art heterogeneous digital signal processor (DSP) and a design example with an on-chip bus have been examined. The results show that sufficient modeling accuracy can be achieved with low modeling effort in terms of computation and implementation time. Holger Blume received his Dipl.-Ing. degree in electrical engineering from the University of Dortmund, Germany in 1992. From 1993 to 1998 he worked as a research assistant with the Working group on Circuits and Systems for Information Processing of Prof. Dr. H. Schrŝder in Dortmund. There he finished his PhD on Nonlinear fault tolerant interpolation of intermediate images in 1997. In 1998 he joined the Chair of Electrical Engineering and Computer Systems of Prof. Dr. T. G. Noll at the University of Technology RWTH Aachen as a senior engineer. His main research interests are in the field of heterogeneous reconfigurable Systems on Chip for multimedia applications. Dr. Blume is chairman of the German chapter of the IEEE Solid State Circuits Society. Thorsten von Sydow received the Dipl.-Ing. degree from the University of Technology RWTH Aachen, Germany, in 2002. Since then he is working as a research assistant at the Chair of Electrical Engineering and Computer Systems (Prof. T. G. Noll), University of Technology RWTH Aachen. His current research interests include Design Space Exploration for on-Chip interconnects and fine grain arithmetic oriented eFPGA architectures. Tobias G. Noll received the Ing. (grad.) degree in Electrical Engineering from the Fachhochschule Koblenz, Germany in 1974, the Dipl-Ing. degree in Electrical Engineering from the Technical University of Munich in 1982, and the Dr.-Ing. degree from the Ruhr-University of Bochum in 1989. From 1974 to 1976, he was with the Max-Planck-Institute of Radio Astronomy, Bonn, Germany, beeing active in the development of microwave waveguide and antenna components. Since 1976 he was with the Corporate Research and Development Department of Siemens and since 1987 he headed a group of laboratories concerned with the design of algorithm specific integrated CMOS circuits for high-throughput digital signal processing. In 1992, he joined the Electrical Engineering Faculty of the University of Technology RWTH Aachen, Germany, where he is a Professor, holding the chair of Electrical Engineering and Computer Systems. In addition to teaching, he is involved in research activities on VLSI architectural strategies for high-throughput digital signal processing, circuits concepts, and design methodologies with a focus on low power CMOS and deep submicron issues, as well as on digital signal processing for medicine electronics.     

神经网络与HMM构成的混合网络在语音识别中应用的研究

隐马尔可夫模型（ＨＭＭ）技术是语音识别中应用较为成功的算法，但它的缺点影响了其精度、速度、硬件实现和推广应用。神经网络（ＮＮ）具有并行性、强的分类能力和易于硬件实现等优点。将ＮＮ与ＨＭＭ相结合构成混合网络，能克服ＨＭＭ与ＮＮ的缺点，保留双方的优点。本文详细评述了目前在语音识别中应用的由ＨＭＭ和ＮＮ构成的四种混合网络。通过对其结构、识别性能和特点的分析，可以看出ＨＭＭ和ＮＮ构成的混合网的性能明显优于     

Large-Scale Dynamical Models and Estimation for Permeation in Biological Membrane Ion Channels

Biological ion channels are water-filled angstrom-unit (1 angstrom unit=10^-10 m)sized pores formed by proteins in the cell membrane. They are responsible for regulating the flow of ions into and out of a cell and hence they control all electrical activities in a cell. This paper deals with constructing large scale stochastic dynamical models for explaining ion permeation; that is, how individual ions interact with the protein atoms in an ion channel and travel through the channel. These permeation models capture the dynamics of the ions at a femto-second time scale and angstrom-unit spatial scale. We review large scale multiparticle simulation methods such as Brownian dynamics for modeling permeation. Then we present a novel multiparticle simulation methodology, which we call adaptive controlled Brownian dynamics, for estimating the force experienced by a permeating ion at each discrete position along the ion-conducting pathway. The profile of this force, commonly known as the potential of mean force, results from the electrostatic interactions between the ions in the conduit and all the charges carried by atoms forming the channel the protein, as well as the induced charges on the protein wall. We illustrate the use of adaptive controlled Brownian dynamics in gramicidin channels and shape estimation of sodium channels.     

Phosphorus Removal from Silicon by Vacuum Refining and Directional Solidification

Silicon is widely used as a raw material for production of solar cells. As a major impurity in silicon, phosphorus must be removed to 1 × 10^?5 wt.%. In the present study, based on the distribution of phosphorus in a silicon ingot obtained by vacuum refining and directional solidification, the mechanism for removal of phosphorus from silicon is investigated. The results show that the distribution is controlled not only by segregation at the solid–liquid interface but also by evaporation at the gas–liquid interface, showing some deviation from Scheil’s equation. A modified model which considers both segregation and evaporation is used to simulate the distribution, matching quite well with the experimental results. The temperature and solidification rate are two important parameters that affect the overall mass transfer coefficient and the effective segregation coefficient and thus the distribution of phosphorus. A high removal efficiency and a homogeneous distribution can be obtained by adjusting these two parameters.     

Refining image segmentation by integration of edge and region data

A basic requirement for understanding the dynamics of the Earth's major ecosystems is accurate quantitative information about the distribution and areal extent of the Earth's vegetation formations. Some of this required information can be obtained through the analysis of remotely sensed data. Image segmentation is often one of the first steps of this analysis. This paper focuses on two particular types of segmentation: region-based and edge-based segmentations. Each approach is affected differently by various factors, and both types of segmentations may be improved by taking advantage of their complementary nature. Included among region-based segmentation approaches are region growing methods, which produce hierarchical segmentations of images from finer to coarser resolution. In this hierarchy, an ideal segmentation (ideal for a given application) does not always correspond to one single iteration, but map correspond to several different iterations. This, among other factors, makes it somewhat difficult to choose a stopping criterion for region growing methods. To find the ideal segmentation, the authors develop a stopping criterion for their Iterative Parallel Region Growing (IPRG) algorithm using additional information from edge features, and the Hausdorff distance metric. They integrate information from regions and edges at the symbol level, taking advantage of the hierarchical structure of the region segmentation results. Also, to demonstrate the feasibility of this approach in processing the massive amount of data that will be generated by future Earth remote sensing missions, such as the Earth Observing System (EOS), all the different steps of this algorithm have been implemented on a massively parallel processor     

Remote supervisory control of the human-in-the-loop system by using Petri nets and Java

For Internet-based remote control systems, certain human operations may violate desired safety requirements and result in catastrophic failure. For such human-in-the-loop systems, this paper proposes a systematic approach to developing supervisory agents which guarantee that remote manual operations meet safety specifications. By applying the mutual exclusion concept, the Petri net approach is used to model, design, and verify a supervisory system which prevents human errors. Then, Java technology is adopted to implement the supervisor as an intelligent agent for online supervision of the remote control system. To demonstrate the feasibility and practicability of the developed supervisory approach, we apply it to a rapid thermal processor controlled over the Internet.     

通过"分离"与"整合"构建新BSS/OSS

介绍了系统“分离”与“整合”的主要内容，以及实现“整合”所采用的互联技术和其它的关键技术，并给出了“整合”方案。     

Integration of Computational Models Inspired by Economics and Genetics

Multi-agent software systems can be modelled as complex dynamic systems in which agent adaptation and interaction occur continuously and concurrently. A genetics-inspired view has interaction occurring via exchange of agent characteristics encoded as genes, plus measures of success. An economics-inspired view has agent adaptation driven by changes in prices, and supply and demand. This paper describes work towards a synergistic combination of these views.