离心铸造不锈钢空心管坯裂纹缺陷的探讨

介绍了离心铸造1Cr18Ni9Ti钢管坯产生的裂纹形态;从理论上探讨了裂纹产生机理并提出了预防和消除裂纹的措施及较佳的铸造工艺参数。     

消失模铸钢件表面渗碳的研究

从铸钢件表面渗碳的机理入手,研究EPS高温分解物与金属液的相互作用,EPS分解产生的大量高温游离碳,是铸钢件表面产生渗碳的根本原因.分析了模样材料密度、合金的化学成分、铸型的热状态、浇注工艺和铸件本身结构对铸钢件渗碳的影响,由此提出防止渗碳缺陷应该采取的几种措施:减少模样的发气量、增加透气性、改进浇注工艺、使用添加剂和真空密封技术等.     

Research on the mechanisms of laser forming for the metal plate

Laser forming is a complex thermal–mechanical process. To reveal the mechanisms dominating the forming process is essential to control accurately the deformation of metal plate. Numerous efforts had been made to understand the mechanisms of laser forming. Proposed mechanisms mainly included temperature gradient mechanism, buckling mechanism and upsetting mechanism. However, in the investigation of laser forming, it is found that the above three mechanisms cannot depict fully the process of deformation. Based on the study of thermal transfer and elastic–plastic deformation, the above three mechanisms are further explained. In addition, a new mechanism, coupling mechanism, is proposed. To verify the validity of the mechanisms proposed, numerical simulations are carried out, and simulation results are consistent with analyses of mechanisms. Further analyses of forming mechanisms provide a theoretical basis for the scanning path and heating conditions as well as high-precision forming.     

凝固过程中电流作用机制评述

综述了当前国内外有关电流在金属凝固过程中作用的研究状况,从理论上归纳和分析了电流对凝固过程产生作用的主要机制,对现有理论及计算公式进行推导,对相应公式进行进一步补充,对电流在凝固过程中的应用和进一步研究进行了展望.     

高层建筑消防机器人的机构研究与分析

结合高层建筑火灾现场的特殊条件,介绍了高层建筑消防救灾机器人的整体运作机理以及各主要功能部件的机构组成和工作原理.该机器人可以实现在保持姿态不变的条件下,携带一定数量的救生物品和灭火工具快速运动到壁面目标位置进行破障救生和火情探测,并将探测结果及时传递给处于安全地区的控制系统,便于救灾人员及时采取相应的措施.     

基于Pro/E的水压轴向柱塞泵三维造型设计及机构仿真

在分析水压轴向柱塞泵结构特点的基础上，详细说明了Pro／E在柱塞泵三维造型设计和机构仿真制作的全过程，从而为水压泵的设计提供了有力的工具。     

基于网络环境下对日志系统攻击的机理分析与研究

日志系统的安全对计算机安全来说至关重要,分析了日志系统受到攻击的位置和不同类型。并从日志系统的机密性、完整性和可用性三个方面对日志系统受到攻击的机理进行了详细的分析。最后,对日志系统如何防止受到各种攻击进行了总结。对在网络环境下计算机主机避免其日志系统受到攻击具有较强的指导意义。     

移动P2P文件共享系统中基于用户偏好的激励机制

提出一种基于用户偏好的激励机制,鼓励用户通过提供共享文件和转发操作为系统做出贡献。IMBPC结合了虚拟价格机制和预期文件传输延时,基于用户对价格和延时的偏好度来选择最合适的节点进行文件下载。通过设置模拟实同仅通过虚拟价格机制来激励用户做出贡献的策略进行比较,显示应用IMBPC策略的系统,节点的贡献积极性明显增加。     

基于WinPcap与Jpcap的校园局域网监控系统的设计与实现

利用基于Win32平台的抓包和网络分析开源库WinPcap,结合Java类库Jpcap,设计并实现一个校园局域网安全监控系统。该系统不但可以捕获、分析并存储数据包,还可使捕获的数据包以表格的形式展现,从而方便网络管理员的管理。给出其软件的设计和实现细节,实践证明该系统是有效的。     

Truth-Telling Reservations

We present a mechanism for reservations of bursty resources that is both truthful and robust. It consists of option contracts whose pricing structure induces users to reveal the true likelihoods that they will purchase a given resource. Users are also allowed to adjust their options as their likelihood changes. This scheme helps users save cost and the providers to plan ahead so as to reduce the risk of under-utilization and overbooking. The mechanism extracts revenue similar to that of a monopoly provider practicing temporal pricing discrimination with a user population whose preference distribution is known in advance.