Modeling and Verification of a Sentiment Analysis System Using Aspect-Oriented Petri Nets

An increasing number of social media and networking platforms have been widely used. People usually post the online comments to share their own opinions on the networking platforms with social media. Business companies are increasingly seeking effective ways to mine what people think and feel regarding their products and services. How to correctly understand the online customers’ reviews becomes an important issue. This study aims to propose a method with the aspect-oriented Petri nets (AOPN) to improve the examination correctness without changing any process and program. We collect those comments from the online reviews with Scrapy tools, perform sentiment analysis using SnowNLP, and examine the analysis results to improve the correctness. In this paper, we apply our method for a case of the online movie comments. The experimental results have shown that AOPN is helpful for the sentiment analysis and verifying its correctness.     

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。     

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。     

Modeling and Performance Analysis of Cognitive Radio Networks Using Stochastic Timed Colored Petri Nets

Cognitive radio (CR) is currently one of the most promising information transmission technologies to deal with the problem of spectrum scarcity and spectrum underutilization in wireless communications. CR networks aim to enhance spectrum efficiency to meet the ever-increasing demands of end users. The principle is to provide the opportunity for unlicensed users (secondary users, SUs) to temporarily and dynamically access the unused or sparsely used bandwidth while ensuring that it never interferes or degrades the performance of the incumbent license holders, commonly called primary users (PUs). This raises several challenges to be addressed in CR networks and performance of secondary users is one of the critical issues tackled in this paper. That is, we propose to devise CR networks as a retrial queueing system where PUs have preemptive priority over SUs. To calculate performance measures of the devised model under quite general assumptions about the model parameters, analytical methods are known to require hard calculations and the obtained results are generally not exploitable. For this reason, simulation modeling becomes the last resort to assess the dependability indicators. To this extend, we build the simulation model of the queueing system using Timed Stochastic Colored Petri Nets. Various useful results will be hence drawn while varying network conditions. Both exponential and Erlang distributions are considered for modeling service time of SUs. The obtained results with restrictive assumptions fit the analytical outcomes experienced for quite similar queuing models, which demonstrate the effectiveness of the proposed STCPN simulation model.

     

Modeling and Performance Evaluation of Inventory Systems Using Batch Deterministic and Stochastic Petri Nets

This paper presents our work on modeling and performance analysis of inventory systems using batch deterministic and stochastic Petri nets (BDSPNs). It addresses issues frequently raised by industrial companies, but did not receive enough attention by the Petri nets (PNs) community in spite of its important role in the study of discrete event systems. The BDSPN is a new class of PNs capable of describing the synchronization of discrete and batch token flows in discrete batch processes. Such processes appear in inventory systems or more general supply chains where materials are purchased in finite discrete quantities (batches of different sizes), and many operations such as inventory replenishment and customer order fulfillment are usually performed in a batch way because of the batch nature of customer orders and/or in order to take advantages of the economies of scale. In this paper, the BDSPN model is formally introduced, and its conflict resolutions of transitions and batch firing indexes are addressed. The model is then applied to the modeling and performance evaluation of various inventory systems. Analytic performance evaluation techniques are developed for the model with illustrative applications to the inventory systems. Our study shows that the model is powerful for both modeling and performance evaluation of the systems.     

一种随机Petri网性能等价化简与分析方法

随机Petri网模型是系统性能评价的有力工具,但其状态空间随模型规模的增长而指数性增长的问题限制了其对复杂和大规模系统模型的性能数量分析能力.因此,在对模型进行分析之前,先对其进行适当的性能等价化简,是一种更为可行的分析方法.本文首先讨论了一类随机Petri网-基本随机Petri网(ESPN)的性能等价分析方法,这类随机Petri网由顺序、并行、选择和循环等四种基本结构及其组合构成.作者推导出这四种基本结构的性能等价公式,并运用自底向上逐步综合替代的分层分析方法,给出这类随机Petri网模型的性能等价化简分析方法,该方法的复杂性随模型增长而线性增长,有效解决了其性能数量分析问题.然后,讨论了两种非基本结构到基本结构的转换规则,使得复杂的随机Petri网模型也可能转换为ESPN模型,从而使性能等价算法可应用于一般随机Petri网.     

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.     

Correction to "How to model reliability-growth when times of designmodifications are known"

A typographical error in the log-likelihood in the paper by N. Ebrahimi (see ibid., vol.45, p.54-8, 1996) is corrected     

长电缆对PWM变频器输出的过电压分析与对策

本文介绍了PWM变频器通过长电缆传输时对电机侧电压的影响,并设计了一种R、L、C滤波器,有效降低电压峰值与差模dv／dt。     

Yearning to be the center of everything,when we are the center of nothing: The parallels and reversals in chaco,hubble, and facebook

Humans have long sought to map their place in the cosmos and then situate their selves at the center of the universe. These patterns are displayed at three radically different sites — the Sun Dagger in Chaco Canyon, the Hubble Space Telescope, and social media and Facebook. Drawing from Marshall McLuhan, this article will theorize the parallels and reversals in these sites, where cosmological discoveries of the expanding universe have been countered by technological innovations involving electronic screens, such that social media counters space telescopes, cyberspace counters outer space, and Facebook counters Hubble. Perhaps the “revolution” of social media merely parallels other cultural reversals, all of which seek to return humans to the center of the universe, when we are the center of nothing. And this desire and delusion to be at the center of everything lies at the heart of contemporary issues facing the global civilization.