Fast method for simulation of radionuclide chain migration in dual porosity fracture rocks

In fractured rocks with a porous rock matrix such as granites, radionuclides will flow with the water in the fracture network. The nuclides will diffuse in and out the rock matrix where they can sorb and be considerably retarded compared to the water velocity. A water parcel entering the network will mix and split at the fracture intersections and parts of the original parcel will traverse a multitude of different fractures. The flowrates, velocities, sizes and apertures of the fractures can vary widely. Normally one must solve the transport equations for every fracture and use the effluent concentration as inlet condition to the next fracture and so on. It is shown that under some weakly simplified conditions it suffices to determine one single parameter group containing information on the flow wetted surface that a water parcel contacts along the entire path. It is also shown how this can be obtained. Then, solving the transport equations only once for time and location along the path gives the concentration and nuclide flux of every nuclide in the chain everywhere along a path. The same solution actually is valid for every path in the network. This dramatically reduces the computation effort. The same approach can be used for models based on streamtubes.     

Balance the Paradox between Limited Health Resources and Growing Demands for Medical Services

Health institutions in the People＇s Republic of China are under considerable challenge. Innovations in management systems may support the challenge to increase both efficiency and effectiveness. The balanced scorecard （BSC） is one such innovation. We have used a model to explore the factors that may impact the diffusion of the BSC in Chinese government hospitals. In particular, we concentrate on three factors - the outer context, the nature of the innovation and the communication and influence. The outer context and the nature of the innovation do provide an inducement to implement a BSC. The strength of the communication and influence may affect the level of take-up. However, we recognise that they may choose ＂the BSC not for any apparent technical excellence but for the legitimation that Western management practices may bring to local managers.     

基于HR/CFD技术的城市汽车尾气扩散规律研究

为研究城市空间结构对汽车尾气扩散规律,根据高分辨率遥感影像建立了某城市核心区域几何模型。以当地常年气象风向作为重要的边界条件之一,应用CFD多相流技术,模拟了十字交叉口车辆队列怠速等候35,45,55 s时的尾气扩散过程,并对45 s时4个监测点的体积分数进行了实测,最后,通过建筑高度优化,降低了该区域的尾气含量。以上研究结果表明:在空间狭小区域,近地空间CO体积分数达1.0×10-7,与研究域平均体积分数相差100倍以上,说明城市空间结构对尾气扩散影响较大,仿真所揭示的规律与实测吻合。建筑设计时应结合当地气象风向和风速,应设计一定的建筑高度梯度,可以促使污浊气体迅速扩散至远地空间。     

基于可视化理论的重气泄漏扩散研究

可视化技术是一个新的技术领域,应用可视化技术结合模拟实验平台开展了重质气体泄漏扩散实验。对泄漏源不同间距和泄漏区障碍物工况下多泄漏源同时泄漏时的泄漏扩散过程进行了可视化研究,得到了罐区重气泄漏扩散过程的可视化影像。结果表明:可视化研究较好地展现了罐区重质气体泄漏扩散的全过程;多源泄漏的间距越大,扩散越快,范围越广;泄漏源靠的越近,其中间区域越容易形成重气高浓度区,危害越大;重质气体泄漏扩散至障碍物时,扩散行为会发生变化,在障碍物前后会形成高浓度区,并沿着障碍物壁面慢慢上升直至稀释成中性气体,危险性减小。     

大气臭氧扩散采样方法的初步研究

用扩散采样法,吸收空气中的Ｏ３,该方法测得的Ｏ３浓度对臭氧发生系统产生的Ｏ３浓度的相关系数为０．９８９５。该方法测得的空气中Ｏ３浓度与自动连续监测结果符合很好。     

基于技术扩散的客流量预测

旅游客流预测是旅游开发的基础研究内容.由于旅游客流具有动态的变化性和影响因素的多样性等特征,使定量的描述和预测旅游客流量具有较大的难度.鉴于此,综合技术扩散理论和区位论等理论,根据技术扩散的思想,在区域选择分析的基础上建立了具有较强实用性的客流动态预测模型.     

基于GIS的毒气泄漏和扩散模拟及其影响评估

详细讨论了基于GIS(Arc View3．2)的毒气泄漏与扩散模拟的实现及扩散影响的评价。考虑到GIS二次开发语言的局限性,利用外部程序语言开发了毒气扩散浓度空间分布的计算程序,动态链接到GIS系统中来实现模拟。为减轻城市和大型企业在地震下有毒物质的泄漏与扩散灾害和应急反应提供了有效手段,也为平时有毒物质类重大危险源的管理提供了依据。     

鞍山市ADMS-城市空气扩散模型的建立与验证

利用ADMS-城市扩散模型和鞍山市2002年排放清单数据库，建立了鞍山市SO2（二氧化硫）空气扩散模型.同时利用2002年的气象和监测资料对模型进行了验证。结果表明：年和四季的SO2监测值和预测值的一致性较好。     

危险气体扩散实时仿真的关键技术──“反求源强”方法初探

阐述了计算机实时仿真在危险气体泄漏扩散预警系统中的应用。文中首次提出了通过求解气体扩散方程一类反问题来确定源强，即根据传感器实时检测的浓度值，代入反问题算法的仿真程序求得近似泄漏强度，再将实时采集的气象参数一并代入扩散方程，在显示屏上给出有害气体云团在区域电子地图上的扩散态势。     

ADVANCES IN THE BOUNDARY INTEGRAL EQUATION METHOD IN SUBSURFACE FLOW1

ABSTRACT: This paper explores some of the advances of the boundary element method, as applied to ground-water problems, during the last five years. Although the method is still somewhat limited compared to solution by finite elements, the range of solutions has increased considerably. Diffusion and advection-diffusion solutions are done efficiently. These include the incorporation of inhomogeneity, anisotropy, and nonlinear diffusion. The difficult problem of stream-aquifer interaction is an important application as it is much easier to follow a free surface with its multiple configurations. The application must be able to cycle between ground-water connection and disconnection with the stream and include seepage surfaces. Flow in fractured media is a natural application where the flow in fractures can usually be treated without a computational exception in spite of extremely high aspect ratios. The case of seawater intrusion forms a type of free surface problem and thus is a case for which the method has special advantages. For these and other applications the boundary element method provides an inexpensive technique for calculation where the data preparation and setup time is minimal. In most of these cases, programs can and have been written on microcomputers.