在通风条件下密闭空间漏气的对流扩散仿真

建立了密闭空间内的气体在通风条件下的泄漏对流扩散数学模型,介绍了其有限元模型,详细描述了该仿真系统的结构框架图,具体给出了密闭空间内的气体在通风条件下的泄漏对流扩散时的节点浓度曲线图和两个截面的浓度色图。仿真结果对于建立该密闭空间内的气体浓度安全监控系统具有重要的指导作用。     

一种改进的放射性气体扩散高斯预估模型算法*

通过对放射性气体扩散的特征描述,针对高斯预估模型存在的缺点,引入了动态变化的泄漏强度,并通过夹角系数的方式将风速和放射性气体自身的扩散速度合成,得到对气体扩散起到关键作用的合成扩散速度,进而更好地模拟了放射性气体扩散过程中在不同时段、不同区域、不同气流状态下的气体浓度。最后通过实验仿真模拟,表明该算法在一定条件下能够有效地计算出放射性气体泄漏后的不同时间点和不同气流状态下的扩散浓度空间分布,能够较好地模拟放射性气体扩散的动态变换过程,对放射性气体泄漏事故现场的预测和评估具有很好的辅助决策作用。     

潜艇舱段氧气泄漏扩散的三维仿真

在研究潜艇AIP舱段的氧气泄漏扩模型基础上,研制了封闭空间中的易燃、易爆气体的漏扩散三维仿真软件（SD-LO系统）。SDLO综合利用了有限元前处理软件的网络剖分功能和MATLAB软件的二维及三维图形显示功能,模拟了AIP舱室内的氧漏扩散过程,最后给出了氧气泄漏扩散的效果图以及浓度变化曲线图,该文研究对潜艇安全监控预警系统的建立有一定的参考价值和指导意义。     

氚扩散虚拟仿真系统原型研发及其应用

为了研究氚泄漏时的动态扩散机制与事故风险,本文基于三维图形引擎研发了氚扩散虚拟仿真系统.采用预先危险性分析方法进行了氚系统安全分析,通过粒子系统方法模拟了事故中氚扩散的动态过程,基于虚拟漫游与仿真技术实现了人机交互仿真功能.以国际热核聚变实验堆（ITER）的氚提取系统仿真为案例,模拟了氢同位素分离柱与管道发生泄漏时氚的动态扩散过程和浓度变化情况,仿真结果为氚泄漏的安全防护提供了依据.     

基于数据驱动的氚粒子扩散三维仿真系统

为了对氚安全包容系统中氚扩散数据的变化进行直观分析,实现氚扩散的计算数据在空间中的三维可视化,本文基于Unity3D引擎研发了氚安全包容三维虚拟仿真系统.本系统基于计算数据驱动粒子系统对氚的输运及泄漏扩散过程进行三维仿真,以中国聚变工程实验堆CFETR的排灰处理系统(TEP)作为案例,模拟了排灰处理系统中氚的输运及渗透...     

基于MapX的泄漏事故救援决策系统

详细介绍了以地理信息系统(GIS)为基础的危险化学品泄漏事故的仿真及救援决策支持系统的设计结构与应用。本系统以MapX为开发工具,VB．NET为开发平台,实现了不同环境条件下的危险化学品泄漏扩散事故的仿真及其后果预测。该系统同时还具有计算不同应急救援部门的最短救援路径和查询应急资源信息的功能,为事故状态下的救援决策和应急管理提供了有力的支持。     

气体管道泄漏次声源仿真模拟及试验研究

管道泄漏次声波声源特性的研究是次声波法适应性及定位精确性的重要保障，首先对气体管道泄漏声源进行了理论分析，然后通过建立管道泄漏内外流场及声学模型对泄漏声源进行仿真模拟，最后通过试验验证。结果表明：1、气体管道泄漏次声波声源主要成分是四极子声源。2、气体管道泄漏次声信号能量主要集中在0-5 Hz的频段内。3、泄漏次声信号声压值随着管道泄漏孔径的增大而增大，随管道初始压力的增大而增大。     

基于FLUENT的天然气扩散模拟软件研发

FLUENT程序能精确模拟天然气的泄漏扩散,但由于此类计算软件对使用者要求高且参数设置复杂,因此应用并不普遍.对FLUENT进行二次开发,通过Scheme界面编程实现了FLUENT和高级程序语言VB的通信,并整合地形地貌、环境条件及气体组成等多种信息,建立相关扩散模型和数据库,开发出一套天然气扩散模拟软件.软件实现了在交互界面进行参数设置后,调用FLUENT程序在后台模拟天然气的扩散,并把模拟结果输出显现到用户界面.该应用软件结合工程实际,界面友好简单实用,可节省一般工程技术人员的时间,增强数值模拟软件在气体泄漏扩散中的通用性和快捷性.     

气体泄漏传热模型及其有限元分析

对气体发生泄漏时漏孔处的流动与传热耦合特性进行研究。分析泄漏流动状态并考虑摩擦力影响,推导气体泄漏描述方程,利用焦耳-汤姆逊系数计算泄漏节流温差并采用压缩因子进行修正。基于有限元方法建立传热模型,对泄漏稳态流与热传导的耦合场进行仿真分析,进而通过红外热成像方式实现泄漏点定位。仿真与实验结果表明,该传热模型较好地表征了泄漏发生时漏孔处的热特性,为利用红外成像技术的泄漏定位方法奠定了基础。     

基于超声波虚拟相控阵列的气体泄漏成像方法

提出了一种基于虚拟相控阵列的气体泄漏成像方法,能够实现气体泄漏源的可视化定位。该方法首先利用扫描传感器分时采集泄漏源产生的声波信号,然后采用互功率谱和虚拟阵列信号处理技术对泄漏源进行定位。通过仿真讨论了各种因素对定位成像精度的影响,其中包括传感器的数量和阵元间距。在实验平台上进行气体泄漏源的检测和成像实验,验证了该方法的可行性和精确性。结果表明,该方法能够准确可靠地对气体泄漏源进行可视化成像。     

Strategy models for enabling offshore outsourcing: Russian short-cycle-time software development

Economic factors are driving software development projects onto globally dispersed models, as offshore outsourcing becomes more common. Software development companies in developing economies compete for lucrative, job-creating offshore contracts on the basis of industry maturity, labor skills, technology infrastructure, and government support. Diffusion of technology is a key aspect of each of these determinants of competitiveness. This paper analyzes the development of strategies for the diffusion of short-cycle-time software development into and within Russia. Short-cycle-time development is sometimes called agile development or Internet-speed development and uses a number of techniques to move software quickly into production. These techniques are spreading rapidly among software developers worldwide. The benefits of these techniques are well known and provide a credible explanation for why this rapid diffusion is occurring. This paper explains how these techniques are spreading in a borderless fashion. Using the Kline model of innovation diffusion and the Greiner model of evolution and growth of organizations, we analyze the enablers and barriers to diffusion of short-cycle-time software development techniques in Russia. This analysis reveals a complex interaction of political, economic, and technical elements enabling and inhibiting the development of knowledge that supports the innovation diffusion necessary for companies to compete for offshore contracts. © 2005 Wiley Periodicals, Inc.     

The effect of transaction costs on the decision to replace 'off-the-shelf' software: the role of software diffusion and infusion

This study examines the extent to which software diffusion and infusion affect the decision to replace ‘off‐the‐shelf’ software, using the example of spreadsheet software. Transaction cost economics motivates the propositions that higher levels of software diffusion and higher levels of software infusion act as disincentives on the firm’s decision to upgrade or change off‐the‐shelf software. Our focus on software diffusion and infusion extends previous research that only examined hardware infusion and diffusion. Results from the study, using a survey, newsgroups and interviews, generally support the propositions and show that the more software is diffused and infused into a firm, the less likely it is to be changed or upgraded. More specifically, the results also show that, while software infusion acts directly to reduce the likelihood of software replacement, software diffusion only affects it indirectly through its effect on infusion.     

Diffusion of hydrocarbons in the reforming catalyst: molecular modelling

This is an analysis of the diffusion and adsorption of the model reagents involved in the reforming process (heptane, methylcyclohexane and toluene) in the support (gamma-Al2O3) and catalyst (Pt/gamma-Al2O3) made use of in this process. Since the properties of these catalytic systems are influenced by the interactions between the atoms of the catalyst structure (host) and the atoms of the reagents (guest), analysis was carried out at the molecular level, using advanced computer simulations (molecular dynamics and forced diffusion) implemented in the MSI Software. The virtual host-guest model constructed with this software enabled a simulation of the real reforming system (reforming catalyst-reagents) and analysis of the diffusion phenomenon in this system.The results show that the propensity of the reagents to adsorption and the host-guest interaction energy are correlated with the coefficients of diffusion. The diffusion coefficient values are lower in the catalyst than in the support, probably because of the increased adsorption at the active Pt centres. The decrease in pore diameter from 17 to 10A brings about a decrease in the diffusion coefficients not only due to steric hindrance, but also as a result of capillary condensation. The favourable influence of temperature is more distinct in models characterised by a larger pore size. This is so because molecular diffusion dominates over the mechanism of Knudsen diffusion, which increases the temperature-dependence of diffusion.     

输运方程的谱流线扩散耦合方法及其在中子测井中的应用

§１．引言 近年来,中子输运理论得到了很大的发展,对输运问题的数值研究已经取得了很大成绩．这些研究方法的主流是 Ｍｏｎｔｅ Ｃａｒｌｏ方法［１］,确定型方法的研究相对要晚一些．八十年代, Ｌａｒｓｏｎ［２］等人开始用离散坐标Ｓｎ方法数值求解测井问题中的输运方程．离散坐标Ｓｎ方法采用的是空间变量和方向变量的全离散求解方法,要得到一定的求解精度,空间的网格节点数目不能太少,再加上方向变量的离散,所需求解的未知数数目将非常巨大,所以这种方法一般只用于一维和二维空间中的问题．对于三维问题,直接使用这种方法时…     

Diffusion dynamics of open source software: An agent-based computational economics (ACE) approach

The rising popularity of open source software (OSS) calls for a better understanding of the drivers of its adoption and diffusion. In this research, we propose an integrated framework that simultaneously investigates a broad range of social and economic factors on the diffusion dynamics of OSS using an Agent Based Computational Economics (ACE) approach. We find that interoperability costs, variability of OSS support costs, and duration of PS upgrade cycle are major determinants of OSS diffusion. Furthermore, there are interaction effects between network topology, network density and interoperability costs, which strongly influence the diffusion dynamics of OSS. The proposed model can be used as a building block to further investigate complex competitive dynamics in software markets.     

LBlock结构的扩散层研究

最优扩散是分组密码扩散层优良的一个重要指标,Suzaki等人对GFS（广义Feistel结构）做了最优扩散的讨论,但对LBlock型结构的扩散层的最优扩散置换未见文献讨论。借助符号计算软件Mathematica 7.0,将LBlock的分块扩散路径用多项式表达出来,形式化分析此算法[P]层的扩散性。通过穷举所有可能的8元置换,证明了LBlock结构在8轮之前不能达到全扩散;不含移位操作的LBlock结构不能达到全扩散。并且验证了LBlock算法原有的置换[p[8]={2,0,3,1,6,4,7,5}]为最优扩散置换,最后得到了其他一些同样性质优良的置换。     

Characteristics and diffusion of a microcomputer geoprocessing system: The Urban Data Management Software (UDMS) package

This paper presents a microcomputer software package for spatial modeling and traces its diffusion throughout the world. We consider its diffusion as a study in infrastructure constrained diffusion. One of the major conclusions is that the spread of increasingly low-cost microcomputers provides a necessary, but insufficient, infrastructure for the development and diffusion of spatial modeling activities.     

以PLC为控制核心的氧化扩散系统设计思路

主要介绍以PLC为控制核心的氧化扩散系统的设计思路。包括工艺需求、硬件设计和软件设计。其中着重阐述了氧化扩散系统中硬件组成部分的设计和实现方法。