在线学习系统的数据库高可用性研究

文章通过Linux HA组件与DB2 HADR(High Availability and Disaster Recovery)组件相结合的方式实现在线教学系统的数据库高可用性方案。首先介绍了HADR实现DB2的双机热备,并分析了HADR自身存在的无法自动切换问题,然后提出了结合HA和HADR实现DB2数据库自动切换的解决方案,并对方案中出现的特别问题提出了解决办法。为提高在线学习系统的可用性提供了数据库保证。     

使用Hot Potatoes轻松制作英语交互式练习题

随着教学网络化的发展,基于Web交互式练习题的制作备受重视。本文以初中英语练习题为例,介绍如何使用Hot Potatoes软件制作交互式练习题。     

Oracle数据库备份策略研讨

备份技术是解决数据库安全问是重要的数据库备份技术.是数据库安全的重要保障.因此.数据库安全的核心是备份技术.     

对发展西南温泉休闲旅游的思考

西南温泉休闲旅游开发应注重将本地区特色资源——丰富的地热资源、自然生态的奇特性及民族文化资源的丰富性整合起来,由于各温泉地所处的行政位置关系,在开发中面临重复建设的问题,要采取温泉旅游区域管理委员会这样一种管理机构模式进行开发,该管委会应该有一定数量的群众代表,表决机制为一票否决制;同时要运用“前台、帷幕、后台”模式进行开发,“前台”作为温泉休闲旅游的综合开发空间,“后台”为奇特自然资源、民族文化资源,而“帷幕”是前台后台的过渡。     

A Review of Current Researches on Blast Load Effects on Building Structures in China

The damages of building structures subjected to multifarious explosions cause huge losses of lives and property. It is the reason why the blast resistance and explosion protection of building structures become an important research topic in the civil engineering field all over the world. This paper provides an overview of the research work in China on blast loads effect on building structures. It includes modeling blast shock wave propagation and their effects, the dynamic responses of various building structures under blast loads and the measures to strengthen the building structures against blast loads. The paper also discusses the achievements and further work that needs be done for a better understanding of the blast loads＇ effects on building structures, and for deriving effective and economic techniques to design new or to strengthen existing structures.     

Numerical Simulation, of Response of SRC Columns Subjected to Blast Loading

The dynamic characteristics and failure modes of steel reinforced concrete （SRC） columns subjected to blast loading are complicated because of the transient stress wave in the SRC columns and the interaction between steel and concrete. This paper presents a numerical simulation of the response of SRC columns subjected to blast loading using hydrocode LS-DYNA. In the numerical model, a sophisticate concrete material model（the Concrete Damage Model）is employed with consideration of the strain rate effect and the damage accumulation. An erosion technique is adopted to model the spalling process of concrete. The possible failure modes of SRC columns are evaluated. It is observed that the failure of SRC columns subjected to blast load can generally be classified into three modes, namely, a direct failure in concrete body due to the stress wave, a transverse shear failure near the support sections due to the high shear force, and a flexural failure pertaining to large local and global deformation of the reinforcing steel.     

自立式高炉大型冷却模块的安装

阐述了高炉冷却模块的制作和安装,对此类工程的施工时提供了一定的参考.     

高炉热风炉燃烧控制系统

高炉热风炉燃烧控制系统通过改造，对实现高炉燃烧过程的稳定性、经济性、合理性，起到了一定的效果。文中重点叙述了在线系统的硬件配置及软件编制思想，同时指出了系统仍然存在不足与今后改进的方向。     

Rate-sensitive numerical analysis of dynamic responses of arched blast doors subjected to blast loading

Current practice in analysis and design of blast doors subjected to blast loading considers only simple boundary conditions and material properties. The boundary conditions and material properties, in fact, have considerable influence on the response of blast doors subjected to blast loading. In this paper, the dynamic responses of a reinforced concrete arched blast door under blast loading were analyzed by the finite element program ABAQUS, combined with a previously developed elasto-viscoplastic rate-sensitive material model. And the effect of the surrounding rock mass and contact effect of the doorframe were also taken into account in the simulation. It is demonstrated that the strain-rate effect has considerable influence on the response of reinforced concrete blast door subjected to blast loading and must be taken into account in the analysis.     

Analysis of blast wave propagation inside tunnel

The explosion inside tunnel would generate blast wave which transmits through the longitudinal tunnel. Because of the close-in effects of the tunnel and the reflection by the confining tunnel structure, blast wave propagation inside tunnel is distinguished from that in air. When the explosion happens inside tunnel, the overpressure peak is higher than that of explosion happening in air. The continuance time of the blast wave also becomes longer. With the help of the numerical simulation finite element software LS-DYNA, a three-dimensional nonlinear dynamic simulation analysis for an explosion experiment inside tunnel was carried out. LS-DYNA is a fully integrated analysis program specifically designed for nonlinear dynamics and large strain problems. Compared with the experimental results, the simulation results have made the material parameters of numerical simulation model available. By using the model and the same material parameters, many results were adopted by calculating the model under different TNT explosion dynamites. Then the method of dimensional analysis was used for the simulation results. As overpressures of the explosion blast wave are the governing factor in the tunnel responses, a formula for the explosion blast wave over-pressure at a certain distance from the detonation center point inside the tunnel was derived by using the dimensional analysis theory. By comparing the results computed by the formula with experimental results which were obtained before, the formula was proved to be very applicable at some instance. The research may be helpful to estimate rapidly the effect of internal explosion of tunnel on the structure.