Modeling for Predicting Flow Stress of Al-14Cu-7Ce Alloy at Elevated Temperature

在应变速率0.001~1 s-1、温度573~823 K的条件下,采用Gleeble 3500热模拟试验机对Al-14Cu-7Ce合金进行等温热压缩实验,并根据真应力-真应变的计算数值,建立了Al-14Cu-7Ce合金高温流变应力本构方程。结果表明,流变应力符合速率方程€=ADLGb/kT(sinhaLG)n;其中,应变的影响通过多项式拟合方式耦合进入材料常数A,αL和n。所建立的本构方程能够准确预测Al-14Cu-7Ce合金高温流变应力,实验条件下控制合金热变形的主要机制是位错攀移。     

A study of job shop standard setup time quota

For the multi-item and small lot size production mode and single machine job shop scheduling sequence independent setup time, many setup times are difficult to estimate accurately, which influences the ability to achieve accurate production cycles and costs of products. The survey shows that the length of the setup time depends on the level of employee’s knowledge. Therefore, a method for determining the standard setup time quota based on the level of employees’ knowledge is proposed. First, an evaluation index system for the level of employee’s knowledge is built; the level of employee’s knowledge is estimated by the masses and experts fuzzy comprehension evaluation and entropy method. Second, the range and definition of the level of employees’ knowledge index are developed. Third, the relational model of the employee’s knowledge level and the level of employees’ knowledge index is constructed through the least squares method. Finally, an example application is presented to verify the feasibility and effectiveness of the proposed model.     

广州一中大坦沙校区规划设计

介绍在广州市第一中学规划建筑设计方案构思过程中,对人文精神、校园特色、历史记忆等理念的理解和贯彻。探讨针对高中新建校区对老校区校园文化的归属感和认同感营造的设计语言的运用。     

利用Visual C++开发Pro/ENGINEER三维标准库

从提高产品设计效率和质量出发,探讨了参数化设计功能和Pro/ENGINEER Wildfire环境下三维模型参数化设计的实现策略和途径,分析了基于Pro/TOOLKIT二次开发的三维标准件库参数化设计的过程,并给出了应用实例。     

钨合金球的制备与研究进展

基于不同领域对钨合金球性能指标的要求,总结并综述了制备钨合金球的材料体系、制备方法及性能检测方法等,对钨合金球的应用领域及今后研究发展方向进行了简单概述,以期为钨合金球的制备研究提供参考.     

基于故障树的计算机安全性分析模型

提出了通过分析计算机系统的资源实体、访问者权限、安全需求和弱点等安全属性,按照不同的安全需求构造出安全故障树来直观地反映攻击者可能选取的攻击手段的安全状况评价方法;分析安全故障树,使用潜在攻击路径和系统安全失效概率从定性和定量两个方面表达计算机系统的安全状况,为系统的安全改进提供指导和建议。     

Reynolds-Averaged Navier-Stokes Equations Describing Turbulent Flow and Heat Transfer Behavior for Supercritical Fluid

Supercritical fluid has been widely applied in many industrial applications.The traditional Reynolds-averaged Navier-Stokes(RANS)equations are directly applied for turbulent flow and heat transfer of the supercritical fluid,ignoring turbulent effect of the thermal physical properties due to the intense nonlinearity.This paper deduces a set of Reynolds-averaged Navier-Stokes equations for supercritical fluid(SCF-RANS equations)to depict turbulent flow and heat transfer of the supercritical fluid taking all the physical parameters as variables.The SCF-RANS equations include many new correlation terms due to fluctuation of the thermal physical properties.Model methods for the new correlation term have been discussed for closing the SCF-RANS equations.Some of them have relatively mature models,while others are completely new and need profound physical theoretical analysis for proposing reasonable models.This paper provides referable information for these new correlations as far as authors know.The SCF-RANS equations not only provide the formulation special for flow and heat transfer of the supercritical fluid,but also represent the most sophisticate form of the RANS equations,for every involved physical property has been considered as variable without any simplification.     

Plasmon-enhanced nanosoldering of silver nanoparticles for high-conductive nanowires electrodes

The silver nanowires (Ag NWs) electrodes, which consist of incompact Ag nanoparticles (NPs) formed by multi-photon photoreduction, usually have poor conductivit...