The oxidation resistance mechanism of SiC-B4C-xAl2O3 ceramics at 1400 ℃ in air atmosphere

The oxidation property of SiC-B₄C-xAl₂O₃ (x ranges from 0 wt% to 30 wt%) ceramics was studied in air at 1400 ℃. Results show that the porous oxide layer becomes dense and smooth with addition of Al₂O₃. When the content of Al₂O₃ is proper, the DOP (degree of polymerization) of borosilicate network can be improved with increase of Al₂O₃ content, inhibiting the migration of atoms and molecular groups. With that, the crystallization of SiO₂ and volatilization of B₂O₃ can be restrained. When the content of Al₂O₃ is excessive, the DOP of borosilicate network will be decreased, deteriorating the oxide layer morphology. It is believed that the damage of borosilicate network by excess Al₂O₃ should be responsible for this phenomenon. In this research, the SiC-B₄C ceramic with optimal oxidation resistant can be obtained when the content of Al₂O₃ is 15 wt%.     

Effect of low content sintering aids addition on β-SiC sintered by spark plasma sintering

The influence of low content of sintering aids addition on the properties of β-SiC sintered by spark plasma sintering was studied based on X-ray diffraction and SEM observations. Three dopants, respectively Al₂O₃, Al₂O₃-Y₂O₃ and Al₂O₃-AlN were chosen, and the investigation was undertaken in the [0.5–5 wt%] content range. The analyses revealed the possibility to increase the density of sintered pellets close to 100% of theoretical density (T.D.), even with the addition of very low sintering aids contents, as low as 0.5 wt%, for each dopant. The combination with high sintering pressure allowed keeping a fine microstructure and a pristine cubic crystalline structure while avoiding the formation of secondary phases.     

我国高校专利市场化机制的完善策略

高校的专利市场化是其服务社会经济的主要体现,也是最直接、最有效的促进经济发展的形式。但是,从专利转变为现实生产力并不是自发进行的,而是通过人们从事专利成果市场化活动来实现的。完善的专利市场化机制有利于专利市场化活动的规范化、制度化与流程化,进而影响高校专利市场化的环境、效率和效益,是一个不容忽视的因素。本文研究,既是对高校专利市场化工作的一次理论提升,也是对高校专利市场化机制的一次理论探索。     

Power flow Petri Net modelling for building integrated multi-source power system with smart grid interaction

This paper presents an energy management modelling of a multi-source power system composed of photovoltaic (PV) array, storage and power grid connection, and taking into account messages from smart grid. The designed system can supply a tertiary building at the same time as PV may produce energy. The control strategy aims to manage the power flow through the load with respect to its power demand and public grid constraints. The proposed energy management modelling is based on interpreted Petri Nets formalism. The system is tested using a simulation Stateflow model and responds within certain limits. The results show that this approach is valid and can be a solution for the future smart grid communication between buildings and public grid and may contribute to a better balance between production and consumption and future energy management.     

The implementation methodology of the real effects in a NOI nanostructure,aided by simulation and modelling

The SOI transistors permanently offer new candidates as nanodevices. The nothing on insulator NOI transistor was recently derived from the nano SOI–MOSFET family. Their output characteristics were theoretical modelled with an exponential law, validated by simulations. The transfer characteristics presented sometimes increasing and others times decreasing monotony. This phenomenon was put directly into a relationship with the gate tunnelling breakdown. This paper has three final targets: the breakdown limitation through the back-gate terminal, the real effects including in the NOI transistor architecture – like interface charges or metal-semiconductor work function and quantum effects corrections in simulations, in order to produce a better correlation between simulations and a real behaviour. These simulations represent a milestone in the NOI nanotransistor manufacturing, establishing some parameters that link the device to the real work regime.     

开关磁阻电机驱动系统建模与控制研究

分析了开关磁阻电机(SRM)非线性动态模型和在电动和制动状态下的控制模式,并在Matlab/Simulink环境下对SRM驱动系统进行建模。仿真结果真实反映了SRM的实际工作情况,模型具有很好的通用性,为进一步研究对SRM的控制提供了基础。     

粒子群优化算法在电力系统中的应用综述

粒子群优化(PSO)算法是一种新兴的群体智能优化技术,其思想来源于人工生命和演化计算理论,PSO通过粒子追随自己找到的最优解和整个群的最优解来完成优化。该算法简单易实现,可调参数少,已得到广泛研究和应用。在大量参阅国内外相关文献的基础上,简要介绍了PSO算法的工作原理,较为全面地详述了粒子群优化方法在电力系统中的应用,如电网规划、检修计划、短期发电计划、机组组合、负荷频率控制、最优潮流、无功优化、谐波分析与电容器配置、参数辨识、状态估计、优化设计等方面,并对今后可能的应用指出了研究方向。     

预变量与时效温度对Fe—Mn—Si合金记忆效应的影响

研究了预变形量和时效温度对Fe-28Mn-5．7Si-5Cr-0．82Ni-0．045Nb合金形状记忆效应的影响。结果表明，合金形状回复率随预变量的增大而减小，在2％左右合金回复率可以达到80％。合金经1023K时效处理时形状记忆效应最好，比固溶态提高了90％，这主要是时效处理有效提高了奥氏体基体的强度，而奥氏体基体的强度的提高可以抑制塑性变形的产生。     

基于J2EE和Matlab的发电厂继电保护综合管理系统

基于J2EE平台和Web服务的综合集成方案,既能充分利用J2EE平台的成功优势,又能以互操作性更好的方式展现整合企业信息系统功能。面向服务层,将计算平台、图形化平台集成于统一的信息化管理平台之中。介绍了一种面向服务层的基于J2EE和Matlab的发电厂继电保护综合管理系统。分析其总体结构、主要功能模块和技术特点。系统采用分布式J2EE架构,与Matlab有机结合,实现了发电厂继电保护信息管理、故障分析、保护整定等功能。该系统具有较好的实用性和通用性。     

毫米波辐射计缩比测试研究

缩比测试是在较低高度下对满足缩比条件的小目标进行测试,以等效在真实高度下对大目标进行测试的情况。文中针对毫米波辐射计的探测研究,讨论了其缩比测试的原理及条件,并在两种高度下进行了实际的毫米波辐射计缩比测试及相应真实高度下的塔载测试,结果对比表明了缩比测试的可信性。该方法简单易行,可节省大量经费。