采用机械钻铣轻量化技术的轻型镜研制

以φ400mm轻型平面镜为例，介绍了采用机械减重法制造轻型镜的工艺技术。镜坯的轻量化采用了刚度虽不是最优，但工艺性最好的圆孔结构，并采用专门设计的钻头钻孔，再用氢氟酸消除微裂纹。加工结果表明，该镜的减重比达44．5％，但仍具有足够的刚度，且没有影响加工精度的变形。     

A simulation testbed based on lightweight processes

The Si lightweight-process based system for simulating process interactions is an enhancement to the C programming languge in the form of library primitives with sets of predefined data structures. The Si system encapsulates an existing lightweight-process library to provide a discrete-event simulation environment supporting the process view. It was developed as a research testbed for investigating methods which support simulations efficiently. Easy extensions and modifications to the Si system are a major design objective, accomplished through modularity and layering. This paper describes the system, our experiences with its implementation, and its applicability to simulation modeling. We report on performance measurements of different implementations of the simulation scheduler, and of different algorithms for simulating service disciplines.     

硬脂酸对轻质碳酸镁改性的研究

利用硬脂酸对轻质碳酸镁进行改性,研究了硬脂酸的用量、反应温度、反应时间对改性效果的影响,最终确定了最佳的改性条件。测定了改性轻质碳酸镁的沉降体积、吸油值和活化度并用红外光谱和热失重进行表征。实验结果表明轻质碳酸镁经改性后,亲水表面变为亲油表面;硬脂酸与轻质碳酸镁之间并不是简单的物理吸附,而是发生了化学反应,形成了新的化学键。     

Improving environmental sustainability of concrete products: Investigation on MWC thermal and mechanical properties

This research focuses on the possibility of constituting a more sustainable lightweight concrete, Mineralized Wood Concrete (MWC), substituting natural aggregates with wastes from woodworking activities. Exploiting this type of aggregates, a triple purpose has been achieved: preservation of natural raw materials, reuse of wastes and energy saving. Furthermore, the use of wood aggregates is a way to try to develop a sustainable concrete characterized by high thermal inertia, high thermal resistance and low weight.In this paper, effects of the addition of wood aggregates on mechanical and thermal properties of concrete are studied. Mechanical performances have been investigated with compressive strength tests, while a one-dimensional heat flow model has been used to predict the thermal conductivity of MWC.The use of MWC can be associated with the idea of a different typology of relatively heavy building envelope: this union could competitively answer to the demand of well-insulated building envelope and concurrently characterized by high thermal mass. From this union, a series of other values can be derived: low weight, environmentally friendly, easily industrialized and easy on-site casting. Consequently, applications of wood concrete in building constructions may be an interesting solution in order to improve sustainability and building energy efficiency.     

拓扑优化在发动机吊挂结构设计中的应用

研究了拓扑优化技术及其在航空发动机吊挂结构设计中的应用。建立了拓扑优化问题的数学模型,进行了灵敏度分析,采用CONLIN算法进行优化迭代求解,并介绍了消除数值不稳定现象棋盘格的方法。建立了基于通用有限元分析软件ANSYS和CONLIN优化算法的优化设计平台,采用FORTRAN语言编写了相应的有限元二进制数据读取、灵敏度求解、灵敏度过滤和流程控制等算法。将本方法用于发动机吊挂的结构设计中并得到合理的结果,证实了其有效性。     

Water absorption in internally cured mortar made with water-filled lightweight aggregate

The increased propensity for shrinkage cracking in low water-to-cement ratio (w/c) concrete has inspired the development of new technologies that can reduce the risk of early-age cracking. One of these is internal curing. Internal curing uses saturated lightweight aggregate to supply ‘curing water’ to low w/c paste as it hydrates. Significant research has been performed to determine the effects of internal curing on shrinkage and stress development; however, relatively little detailed information exists about the effects of internal curing on fluid transport properties such as water absorption or diffusivity. This study examines the absorption of water into mortar specimens made with saturated lightweight aggregates (SLWA). These results indicate that the inclusion of SLWA can reduce the water absorption of mortar specimens. This observation was reinforced with electrical conductivity measurements that exhibited similar reductions.     

On the polymer modified cement mortars with different lightweight aggregates in marine environment

Having a light weight is a design objective for offshore and coastal structures and in order to reach this aim, use of lightweight concrete consisting lightweight aggregates and polymers is a feasible solution. In this study, materials obtained from locally available crushed volcanic scoria as main aggregate and some additional lightweight aggregates with ceramic, perlite and andesite as well polymers were used in the mixtures with different proportions (totally 14 mixtures) to propose feasible alternatives for coastal structure designers. To evaluate the design performances of the mixtures, their properties such as density, cylinder compressive strength, capillarity, loss of mass under the effects of the agents in marine environment such as sodium sulphate and sodium chloride were obtained experimentally. It was found that mixtures with scoria aggregates showed more favourable results and additional aggregates gave flexibility to the designer to lower densities up to 40 % ‐ 60 % of normal‐weight mixtures. Polymer modification also improved the performance of the related materials.     

基于LDAP和SOAP的校园统一身份认证系统的研究与实现

随着校园网的逐步建设完善，基于校园网的应用得到迅速发展，迫切需要建立一个统一身份认证系统，对用户实行统一管理、统一认证和统一授权。提出了一个基于LDAP和SOAP的统一身份认证实现框架。     

轻量级开放式移动Agent系统：原理与实现

移动agent计算模式是一种灵活的基于Internet的分布式计算模式，但是“黑盒”式的设计和“单体”结构使得既有移动agent系统过于冗余，且不能随着用户需求和计算环境的变化动态修改系统的结构和行为。因此提出利用反射技术将移动agent系统“构件化”使其能够支持系统的“可定制”或“可裁剪”，并采用开放式的实现为移动agent系统的使用者提供扩展系统的能力。反射架构下的移动agent系统能够在运行时刻无需关闭系统动态加载或卸载特定模块；通过移动agent和底层平台的反射特性能自然地实现agent和agent平台的自适应。遵循这个途径开发了具有反射特性的Artemis-Mogent原型系统，并通过试验示范了新系统应用反射后的效果。     

PKI证书的撤销与验证

随着电子商务公司越来越多地使用数字证书 (由认证中心签发的电子身份证 )来保证在线交易的安全性 ,这一行为引发了对另一种安全性的需要 ,即对数字证书的有效性进行验证。因此 ,CA认证的一个重要操作就是验证用户的证书是否被撤销或者挂起。证书的撤销采用证书撤销列表 ,而用于验证证书状态的机制一般使用轻型目录存取协议或者在线证书状态协议。简要介绍了证书撤销列表以及基于轻型目录存取协议的目录服务机制 ,而重点讨论了基于在线证书状态协议的目录服务 ,并例举了一个在线证书状态协议的实际应用。