太阳能电池有机电子传输材料研究新进展

当今能源危机问题日益紧迫,以太阳能为代表的新能源开发成为研究热点。有机半导体材料具有成本低廉、可塑性强、性能优异等特点,因此在太阳能电池领域中具有极大的应用前景。研发性能优异、成本低、稳定性高的有机电子传输材料是太阳能电池研究领域的重要内容。总结了近年来有机电子传输材料的研究进展和发展方向,按照其分子结构分为富勒烯衍生物、大π共轭体系、非π体系、改性材料、碳纳米材料等5类体系,分别介绍了其结构特性,讨论了其在太阳能电池应用中存在的问题及解决方法,综述了该领域的最新研究成果,最后总结了开发新型高效的有机电子传输材料的研究方向。     

The effects of practice teaching sessions in second life on the change in pre-service teachers’ teaching efficacy

The purpose of this research was to investigate the effect of practice teaching in Second Life on the change of preservice teachers’ teaching efficacy, and the difference of changes between individual teaching practice and collaborative teaching practice in their teaching efficacy. Participants were placed into the individual teaching practice or collaborative teaching practice group as a part of a teaching methods and educational technology course. Both groups completed practice teaching sessions twice in Second Life and an instrument adopted for measuring of pre-service teachers’ teaching efficacy beliefs was administered after each of three stages. The researcher collected data from both groups before the first practice teaching, after the first practice teaching session, and after the second session. Results from a Repeated Measure ANOVA indicated that the practice sessions influenced changes in participants’ personal teaching efficacy but not teaching outcome expectancy. In addition, the results indicated significant difference between groups on their personal teaching efficacy after the second practice session, but not on teaching outcome expectancy. The difference between the two groups is attributed to the different methods in preparing for the practice session, practicing the teaching, and the reflection methods posed to each group of participants. This research suggests that pre-service teachers can gain valuable teaching practice in Second Life, and furthermore that collaborative practice teaching is more effective way than individual approaches to practicing teaching.     

Bifurcation control in a delayed two-neuron fractional network

The issue of bifurcation control for a delayed fractional network involving two neurons is concerned. Delay-dependent stability conditions and the bifurcation point are established by discussing the associated characteristic equation of the proposed network. Then, a delayed feedback controller is firstly designed to stabilize the Hopf bifurcation, and desirable dynamics is achieved. It is indicated that the designed controller is extremely effective which can postpone the onset of bifurcation by carefully selecting the feedback gain. Finally, simulation results are given to verify the efficiency of the theoretical results.     

Effects of hydrogen on mechanical properties of vanadium-niobium alloys

Mechanical properties of V-Nb alloys were investigated from 78 to about 300 K. The effects of alloying composition on the yield and flow stress are consistent with a hardening model due to the “misfit”" of one element in the matrix of the other. Additions of up to about 0.6 at. pct of hydrogen have a moderate strengthening effect on the yield stress of high vanadium alloys, but relatively little effect on the high niobium alloys. Little or no effect of adding hydrogen to any of the alloys was observed for the strain hardening coefficient. High Nb alloys were found to be much less embrittled by small additions of hydrogen than were high V alloys. In addition, the failure of severely embrittled alloys was found to be initiated intergranularly by impingement of mechanical twins on grain boundaries. It is speculated that the grain boundaries may be enriched hydrogen.     

装备综合预算编制研究

加强装备综合预算编制研究,对于提高装备经费使用效益具有重要的现实意义。阐述了编制装备综合预算的必要性,分析了影响装备综合预算编制的情形,提出了推进编制装备综合预算的措施,即坚持集中下达经费、坚持经费资产统一预算、坚持统一规范管理。     

基于光伏微网的PI-dP&O高性能MPPT控制器的设计

通过采用PI-dP&O模块、Buck-Boost电路与具有电流闭环控制的抑制积分饱和的PI控制器相结合的策略,设计出一种具有高性能的MPPT控制器。此控制器具有软件实现简单、适应性好、成本低廉等优点。在Matlab实验平台上将此高性能的MPPT控制器与传统的MPPT控制器进行对比,并应用到光伏微网中,充分显示其优越性和可行性。     

Numerical Analysis of Coaxial Double Gate Schottky Barrier Carbon Nanotube Field Effect Transistors

Carbon nanotube field-effect transistors (CNTFETs) have been studied in recent years as a potential alternative to CMOS devices, because of the capability of ballistic transport. The ambipolar behavior of Schottky barrier CNTFETs limits the performance of these devices. A double gate design is proposed to suppress this behavior. In this structure the first gate located near the source contact controls carrier injection and the second gate located near the drain contact suppresses parasitic carrier injection. To avoid the ambipolar behavior it is necessary that the voltage of the second gate is higher or at least equal to the drain voltage. The behavior of these devices has been studied by solving the coupled Schrödinger-Poisson equation system. We investigated the effect of the second gate voltage on the performance of the device and finally the advantages and disadvantages of these options are discussed.     

锡铁山铅锌矿原生电位调控浮选研究

运用原生电位调控浮选技术对锡铁山铅锌矿石进行了系统地浮选试验研究,在最佳矿浆电位和pH值条件下,工业试验指标较同期原流程生产指标提高铅精矿品位5·42%、铅回收率1·83%、锌回收率2·39%节约浮选药剂费用2·85元/t矿石,节省电耗4·57kW·h/t矿石。     

PWM变频器的能耗制动与再生制动

本文介绍了用于ＰＷＭ变频器的两种制动电路。此电路在实际应用中效果很好。