Performance evaluation of anti-radiation based on the gamma degradation process

In the environment of space radiation, the high-energy charged particles or high-energy photons acting on a spacecraft can cause either temporary device degradation or permanent failure. The traditional probability model is difficult to obtain reliable estimation of unit radiation resistance performance with small samples. Considering that different products will change differently after high-energy particle radiation, we construct a model based on the gamma degradation process. This model can efficiently describe the law of unit radiation resistance variation with the total radiation dose levels under the effect of the total dose and displacement damage. Finally, the proposed model is used to assess the anti-radiation performance of the N-channel power MOSFET device STRH60N20FSY3 produced by STM to obtain average unit radiation resistance, survival probability, survival function, etc.     

项目导向的计算机审计教学方法的创新与探索

针对目前计算机审计课程教学过程中存在课堂教学与计算机审计实践脱节问题,笔者根据自身教学经验,并结合参与国家审计署项目审计的经历,提出以项目为导向、整体模块化、模块多样化的计算机审计教学方法,实现教学理论与审计实践的较好结合,充分调动教学中两个主体的主观能动性,提高了教学质量。     

Numerical solutions of Duffing equations involving both integral and non-integral forcing terms

In this paper, an improved variational iteration method is presented for solving Duffing equations involving both integral and non-integral forcing terms. The main advantage of this modification over the standard variational iteration method (VIM) is that it can avoid unnecessary repeated computation in determining the unknown parameters in the initial solution. Numerical results reveal that the improved method is simple and efficient.     

图书馆读者网络问卷调查系统的设计与实现

本文为主要介绍,基于B／S结构,设计和开发网络版的读者问卷调查系统,此系统对调查问卷结果的分析和统计做出详细的描述,通过和图书馆其它系统的联合使用,形成特有的读者问卷调查反馈服务平台,本文参与“‘网络环境下高校用户信息行为实证研究”课题立项的研究。     

Machinability of Metal Matrix Composites Reinforced by 3-D Network Structure

Metal matrix composites reinforced by three-dimensional (3-D) continuous network structure reinforcement (3DCNRMMC) are difficult to machine due to serious tool wear and poor surface roughness caused by the brittle and hard reinforcement which interpenetrate into ductile matrix. In order to achieve the approach of low cost of 3DCNRMMC, the machinability of it needs to be understood. The influences of three cutting parameters and volume fraction of reinforcement on cutting force were analyzed in detail. The results indicate that: (1) Due to the brittle phase(s) introduced into ductile matrix of composites, there is a large fluctuation of cutting force causing deterioration of machinability. The fluctuation ranges of cutting forces, initially increase rapidly with the increase of volume fraction of reinforcement and then decrease finally, are largest at the range of the volume fraction of 55–65%; (2) The influence of cutting parameters on cutting force is obvious. With the increases of cutting speed, cutting force decreases gradually unless cutting speed exceeds the value of 209 m/min. Cutting forces increase with increasing feed rate and depth of cut; (3) Owing to the large fluctuation of cutting force, there were some cratered surfaces caused by Si₃N₄ reinforcement pulling-out and flaking-off. Some brittle phase protruding from the machined surface caused the deterioration of machined surface.     

激光技术在微细加工中的应用

本文介绍了用于微细加工的激光器的种类和特点，阐述了激光技术在微细加工中的应用、国外的研制情况及其发展前景。     

粉煤灰贮存库气化装置存在问题及对策

描述了大唐国际陡河发电厂粉煤灰贮存库运行过程中出现出灰口下灰慢及气管中堵灰现象,清理灰库后发现气化板损坏、气化槽箱体内全部充满灰、分支进气管弯头磨漏、气化槽箱体安装工艺缺陷及原设计等问题,并对上述问题进行了分析,提出了解决问题的对策。通过对策实施,灰库气化装置运行效果良好,装灰速度提高了4.3~5.7倍。     

金属铈改性对铁基柴油机尾气脱硝催化剂性能的影响

氧化铁具有良好的氧化还原性,CHA型骨架结构的SAPO-34分子筛具有优异的微孔结构和较大的比表面积,热稳定性高,因此Fe/SAPO-34材料被广泛研究用于尾气脱销,但其低温活性较差,活性窗口偏窄。利用金属铈改性能够有效上述缺点,通过现代表征技术详细阐述其中原因。