虚拟社会仿真中的人际关系网络模型研究

人际关系网络具有复杂网络中典型的小世界、无标度特性,同时其本身又具有强的"地域性".在分析人际关系网络三种特性的基础上,借鉴构建小世界、无标度网络的思想,提出了在危机条件下,某地区民众就当前发生的危机事件因交流而形成的人际关系网络模型,实现了原型系统,并进行了仿真实验分析.结果表明,构建的人际关系网络模型是可行的,可用于虚拟社会系统建模仿真.     

国家关键基础设施模型总体设计与实现

对国家关键基础设施的建模仿真越来越受到各国重视.为应对危机影响下国家关键基础设施仿真的需求,寻求国家关键基础设施这一复杂系统的模型建立方法,界定了国家关键基础设施的基本概念、组成,分析了用建模与仿真方法研究该问题的必要性,根据"按需服务"的设计思想,设计了国家关键基础设施模型的总体结构,并对各子模型的实现和模型综合集成方法进行了深入研究和思考.该模型及设计思路为复杂社会系统的建模与仿真提供了有益的借鉴和参考.     

面向社会计算的集成建模方法与应用系统

复杂社会系统建模是社会计算面临的首要问题.面向社会计算领域的建模流程与需求,提出了一种模型深度集成架构,称为POV框架.该框架由物理层、覆盖层和虚拟层3部分组成,提供了模型的组织、表达和集成方法.基于该方法搭建了面向社会计算数据模型交互共享集成平台,为研究者们提供包括数据资源、分析工具和建模仿真计算环境的社会计算实验平...     

计算机组成原理虚拟实验环境的设计及实现

根据实验教学的需要,结合计算机组成原理的特点,对计算机组成原理虚拟实验环境进行了研究.该实验环境基于清华大学计算机厂设计研制的Tec-xp实验箱,开发软件平台采用Microsoft Visual C++6.0语言和SQLServer2003数据库技术.该实验环境的搭建从系统的需求分析出发,采用面向对象的仿真方法进行建模,同时结合计算机系统的功能特性和计算机组成原理教学的特点,应用了离散事件系统仿真的基本理论和方法,使得虚拟环境的操作如同在真实的设备上一样.该虚拟实验环境的实施,给学生提供一个具有自主性的实验环境,具有良好的开放性、通用性和实用价值.     

基于UML方法的空间交会GNC仿真系统设计

为提高建模的快速性、可靠性、可维护性和可扩展性,采用面向对象技术对空间交会GNC仿真系统进行分析与设计.该仿真系统采用统一建模语言进行设计,从用户角度对 GNC仿真系统需要实现的功能进行了概念建模,从方案实现角度对交会系统核心对象、类及其相互关系进行了功能建模,另外采用序列图、状态图及协作图对关键的事件、流程及其活动进行了行为建模.仿真系统已得到初步实现,可以支持不同仿真背景,不同建模粒度下的仿真要求,应用结果验证了建模的特点,说明本设计方法具有一定的应用价值.     

基于Modelica的虚拟远程实验室

为了弥补传统实验教学模式的不足,介绍一种使用新型的、面向对象的多领域统一建模语言Modelica进行建模及仿真的电工电子虚拟远程实验室,并详述了其架构及远程实验的操作流程。构建两个子系统——模电实验系统及吹摆控制实验系统。通过调用Modelica标准模型库,实现了模电实验系统的建模;根据模块化建模的思想,对吹摆控制实验系统进行系统分解,利用Modelica编写每个模块的仿真模型,建立了可扩展的系统模型库,并基于该模型库实现了吹摆系统的构建。将两个子系统放在虚拟实验平台上仿真,仿真结果符合理论推算。     

装备虚拟操作训练的过程建模方法研究

针对装备虚拟操作训练系统中对过程建模的研究仅停留在针对具体仿真任务的应用技术层面,缺乏深入的建模理论研究的现象;首先分析了虚拟操作训练仿真目的和装备操作的特点,叙述了过程模型在虚拟操作训练中的重要性;然后提出了一种面向操作训练的过程建模方法及其实现方法,为虚拟操作训练系统过程建模提供了理论支撑;基于此过程建模方法开发的“某型防空高炮虚拟操作训练系统”验证了建模方法的可行性.     

离散事件系统规范DEVS研究

离散事件系统是一类常见的系统，如何对这类系统进行描述与建模是离散事件系统仿真研究的核心内容。离散事件系统规范DEVS是一种离散事件系统形式化描述方法，它具有层次化和模块化的特点，利用该方法可对复杂的离散事件系统进行建模、设计、分析和仿真。该文详细介绍了DEVS基本模型和耦合模型，给出了DEVS在耦合运算下的封闭性构造证明，并提出了一种具有嵌套层次结构的DEVS耦合模型实现算法，该算法对基于DEVS描述的离散事件系统的仿真实现具有一定参考价值。     

基于混杂系统理论的制造系统仿真

根据制造系统连续事件与离散事件并存的特点,提出一种制造系统半实物仿真方法,设计连续事件和离散事件并存时仿真系统的时间推进机制。在Arena环境中实现对离散事件系统的建模,在Labview环境中实现特定连续变量事件的半实物仿真。设计并实现离散事件系统与连续事件的接口连接。仿真实验结果表明,该系统能较好地反映出整个制造系统的混杂特性,为混杂制造系统的仿真提供一种新的思路。     

基于虚拟DCS的电厂烟气脱硫协同仿真系统

介绍新型的电厂烟气脱硫仿真系统,提出采用基于CFD模型及过程模型的协同仿真方法进行建模,硬件系统采用虚拟DCS仿真方式.采用CFD方法建立详尽描述吸收塔特性的CFD模型,同时采用集中参数法对FGD其它设备进行建模,协同仿真方法能充分发挥两种建模方法的优点,更精确地描述FGD系统的特性.采用基于虚拟DCS的激励式仿真方法建立仿真系统,结合了全模拟模式和全激励模式的优点,使用虚拟DCS复现实际DCS的全部功能,具有极高的软件逼真度,同时以软件代替部分硬件,可极大地降低实现成本.基于虚拟DCS的电厂烟气脱硫协同仿真系统对于电厂脱硫系统人员培训、运行分析及系统优化研究具有重要作用.     

Using Bayesian networks and virtual coverage to hit hard-to-reach events

Reaching hard-to-reach coverage events is a difficult task that requires both time and expertise. Data-driven coverage directed generation (CDG) can assist in the task when the coverage events are part of a structured coverage model, but is a priori less useful when the target events are singular and not part of a model. We present a data-driven CDG technique based on Bayesian networks that can improve the coverage of cross-product coverage models. To improve the capability of the system, we also present virtual coverage models as a means for enabling data-driven CDG to reach singular events. A virtual coverage model is a structured coverage model (e.g., cross-product coverage) defined around the target event, such that the target event is a point in the structured model. The CDG system can exploit this structure to learn how to reach the target event from covered points in the structured model. A case study using CDG and virtual coverage to reach a hard-to-reach event in a multi-processor system demonstrates the usefulness of the proposed method.     

Training and learning for crisis management using a virtual simulation/gaming environment

Recent advances in computers, networking, and telecommunications offer new opportunities for using simulation and gaming as methodological tools for improving crisis management. It has become easy to develop virtual environments to support games, to have players at distributed workstations interacting with each other, to have automated controllers supply exogenous events to the players, to enable players to query online data files during the game, and to prepare presentation graphics for use during the game and for post-game debriefings. Videos can be used to present scenario updates to players in “newscast” format and to present pre-taped briefings by experts to players. Organizations responsible for crisis management are already using such technologies in constructing crisis management systems (CMSs) to coordinate response to a crisis, provide decision support during a crisis, and support activities prior to the crisis and after the crisis. If designed with gaming in mind, those same CMSs could be easily used in a simulation mode to play a crisis management game. Such a use of the system would also provide personnel with opportunities to rehearse for real crises using the same tools they would have available to them in a real crisis. In this paper, we provide some background for the use of simulation and gaming in crisis management training, describe an architecture for simulation and gaming, and present a case study to illustrate how virtual environments can be used for crisis management training.     

A simulation framework for crisis management: Design and use

A perennial simulation framework is proposed within the domain of crisis management simulation. Motivated by a need for establishing information superiority through decision-support analysis, the framework is designed to use symbiotic simulation and is also suitable for the hindsight and foresight studies that drive crisis-related preparedness exercises. The framework provides a novel feature of incorporating Human in the Loop simulations using virtual reality as a part of the symbiotic simulation. We coin the term perennial simulation to refer to our framework being enduring (the simulation working symbiotically with the real system), and recurring (performing “what-if?” simulations and continually providing feedback to the real system).Three case studies examine the application of the framework to crisis-related scenarios. The framework is shown to be useful and capable of dealing with crisis situations and adding value to existing expert advice, forming a symbiotic feedback loop that aids crisis management.     

An Exploratory Model for Evaluating Crisis Events and Managers' Concerns in Non‐Profit Organisations

Few organisations avoid the experience of crisis management. Some time during their life they are confronted with some type of crisis that may strain their resources and distract them from their central mission of serving its clients. Crisis management seeks to minimise the impact of these events. Although the crisis management literature is plentiful regarding larger organisations, little has been written on this subject as it relates to non‐profit organisations. This study examines the perceptions and experiences of crisis events among non‐profit organisation managers located in the north‐eastern part of the U.S. The results reveal that only a little more than a quarter of the respondents indicated that a formal crisis management team or any plans to implement it were operating in their non‐profit organisation.     

From Disaster to Crisis: The Failed Turnaround of Pan American Airlines

The academic and corporate analysis of crisis management achieved considerable impetus during the latter part of the 1980s with the occurrence of a number of major incidents which captured media attention. The terrorist bombing of Pan Am Flight 103 in December 1988 was one of the largest loss-of-life transport incidents of the decade and had serious implications for the integrity of the corporation. The bombing, whilst a discrete crisis event in itself, was part of a longer history of crisis through which the company had passed. The purpose of this paper is to explore the managerial response to crisis events within Pan Am and offer an assessment of the factors that ultimately led to the collapse of the corporation in 1991. Throughout the paper, attempts will also be made to set the events within the context of current thinking in crisis management and, in particular, to examine the demise of Pan Am within the context of a number of models of turnaround management developed within the literature.     

Crisis Politics in Authoritarian Regimes: How Crises Catalyse Changes under the State–Society Interactive Framework

Most studies and research on crisis management and government crises focus on nations that are advanced and democratic. Through the institutionalized mechanism of voting, the public can respond to a government's handling of a crisis without destabilizing the democratic system of government. However, the consequences of crises, particularly governance crises, in authoritarian regimes have not been adequately addressed. Drawing upon different frameworks in the field, this paper proposes a heuristic crisis development ladder and a state–society interactive framework more relevant for studying crisis management in authoritarian nations such as China. By focusing on the catalytic effect of crisis that accelerates reforms and changes, this paper argues that critical crises are politically powerful and decisive in authoritarian systems, especially in the context of an increasingly proactive civil society. This paper illustrates the crisis provoking politics that influences decision‐making under non‐democratic rule.     

浅析社会化媒体中个人虚拟形象的设计

今天,社会化媒体日益深入网络用户的生活,在这个虚拟社会中,视觉化的个人虚拟形象使网友的形象更加有血有肉,得到了众多用户的喜爱,同时也成为了网络虚拟财产的重要组成部分。作为一个新的视觉语言形式,个人虚拟形象设计理应得到更多的重视,设计师们也应该进一步地探索其创新性的设计理念,设计出个性化和多样化的个人虚拟形象来。     

异步DVE系统中生命周期约束下的因果一致性控制方法研究

分布式虚拟环境是模拟现实世界的虚拟空间,对因果一致性控制具有实时性要求,必须在事件生命周期结束前得到维护.然而,在大规模网络条件下,网络传输高延迟和动态性会导致部分事件不能及时到达,使已传到事件间因果关系无法在生命周期限制内有效传递.在现有方法中,部分方法基于所有事件一定能及时传到的假设,没有考虑生命周期对因果关系的制约;而另一部分方法虽然考虑了生命周期的约束,但其因果关系传递要求仿真时钟精确同步,且因果控制效率随系统规模的扩大而快速降低,限制了虚拟环境的普适性和实时性.提出了生命周期约束下的因果一致性控制方法LCO,突破了异步时钟间的时间值比较、多路径因果控制信息选择的终止条件、网络状况敏感的因果控制信息动态调节等关键技术,能够在事件无法及时传到时,仍可以根据已传到的事件计算出因果传递关系.实验证明,LCO既能维护生命周期内的因果一致性,又使因果控制信息量与系统规模无关,降低网络传输和计算开销.     

Opportunistic sharing scheme for spectrum allocation in wireless virtualization

The past few decades have witnessed an increasing growth in mobile and wireless network, leading to a corresponding fast growth in mobile demands. However, the proliferating mobile demands compel wireless network to face several challenges, such as the conflict between spectrum crisis and low resource utilization ratio, and the poor quality of service and quality of experience. Wireless virtualization, enabling multiple concurrent virtual networks running on shared wireless substrate resource, has been proposed as a promising way to overcome the plights of the current mobile and wireless network. How to efficiently allocate the resource, especially the spectrum resource, of physical network to multiple virtual networks is one fundamental and important challenge in wireless virtualization. This paper rethinks the characteristics of virtual networks’ requirements, and then divides the requirement into a baseline part and a fluctuant part. Based on it, this paper introduces an opportunistic spectrum sharing approach, through which we formulate the spectrum resource allocation problem as an NP-Hard problem. Then, we propose our opportunistic spectrum resource allocation scheme for the wireless virtualization. Simulations validate the performance advantages of our approach and show that opportunistic spectrum sharing significantly improves the revenue, resource utilization and acceptance ratio of physical wireless network while decreasing the payments of virtual networks.