Dielectric and pyroelectric characteristics of the infrared sensitive (Pb1?xSrx)TiO3 ceramics

PST ferroelectric ceramics were fabricated successfully by a two-step method, i e first, PbTiO₃ and SrTiO₃ were sintered respectively, then mixed and sintered together. The process and characteristics of PST ferroelectric ceramics were introduced and researched. Their dielectric and pyroelectric characteristics are as follows dielectric constant 10⁴ order, low dielectric loss (lower than 3.0% in the working frequency range of 1–1 000 kHz), saturation polarization intensity 10⁻¹ C/m² order, and pyroelectric coefficient 10⁻³ C/m²·K order.     

卡塞格林式星敏感器杂散光分析

卡塞格林系统是新型星敏感器的光学系统,具有口径大、体积小的优点,但外界杂散光对卡塞格林系统的影响很大。介绍了一种焦距为425mm,口径为102mm的卡塞格林系统,考虑轴外渐晕的影响,给出星敏感器主遮光罩以及主、次遮光罩的设计方法。这种设计方法相比于其他方法更加便捷和精准。并用Tracepro对系统进行杂散光分析。计算得到点源垂直照度透射比（Point Source Transmittance,PST）曲线。分析结果表明,当杂散光入射角大于临界角30°时,PST值小于10-8量级,满足系统使用要求。证明设计方法是可行的。     

Ti－48at％Al合金PST晶体的高温压缩性能

采用磁悬浮区域熔炼的方法制备了ＴｉＡｌ合金ＰＳＴ晶体，然后在８００℃下对其压缩性能和变形组织分别进行了测试和观察。结果表明，在８００℃时的屈服强度取决于片层界面与压缩轴的夹角φ在φ＝９０°时屈服强度最高，而φ＝４５°时最低。８００℃时屈服强度较室温下的有较大程度下降，这与α２相中锥面滑移系｛１１２１｝＜１１２６＞的临界分切应力的降低有关．     

TiAl合金PST晶体断裂过程原位TEM观察

利用ＴＥＭ原位应变观察技术研究了ＴｉＡｌ合金ＰＳＴ晶体中裂纹扩展过程。发现界面与裂纹的交互作用与界面类型有关，不对称的伪孪晶界面（γ／γＰ）对裂纹扩展的阻碍最强烈。片层界面以及二次裂纹导致的裂纹分叉是层状组织韧化ＴｉＡｌ合金的重要原因。当裂纹与片层界面的夹角不同时，γ相所表现的两种截然不同的断裂方式表明在ＴｉＡｌ合金的脆性本质中包含有位错动力学的因素。     

超短型内嵌式遮光罩设计

为了在不影响杂散光抑制效果的同时减少空间遥感器的结构尺寸,方便其姿态控制,提出了一种超短型内嵌式遮光罩。介绍了超短型内嵌式遮光罩的基本结构形式及其优化设计方法。重新设计了遮光罩的形状,采用超短型多层遮光筒结构代替了传统设计中过长的外遮光罩。改变了遮光罩与主体结构的安装方式,将遮光罩嵌入式安装于空间遥感器的主体结构,最大限度地压缩了结构尺寸。以某航空相机光学载荷为例,分析了该种遮光罩的可行性和消杂散光效果。采用Light-tools软件优化设计了双层同心圆柱筒结构的遮光罩,并对该遮光罩的杂散光抑制效果进行了评估。模拟计算结果表明,外遮光罩采用超短型内嵌式结构后,遮光罩总长度和重量均减小为传统设计结果的1/3。系统的点源透过率(PST)曲线显示其整体呈下降趋势,且在离轴角大于25°后,光学系统的PST降低到10~(-7)以下。另外,设计的遮光罩能够有效抑制视场外杂散光,其杂散光抑制能力与其他离轴、同轴系统大体相当,满足使用需求。     

猪用生长激素(PST)脂质体包封率测定方法的比较

试验对测定包封率的两种方法即凝胶柱分离法和鱼精蛋白凝聚法进行了比较，测得PST脂质体的包封率分别为75．26％、84．58％，PST回收率分别为90．4％和98．22％。因此确定了鱼精蛋白法为试验产品包封率的测定方法。     

THE ALGORITHMS AND APPLICATIONS FOR DETERMINING PERMEABILITY COEFFICIENTS BY PULSE SPECTRUM TECHNIQUE

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｆｏｌｌｏｗｉｎｇｅｑｕａｔｉｏｎｉｓｗｉｄｅｌｙｕｓｅｄｉｎｇｒｏｕｎｄｗａｔｅｒｄｙｎａｍｉｃｓ,ｅｌｅｃｔｒｉｃｉｔｙａｎｄｍｅｄｉｃａｌｓｃｉｅｎｃｅ: ｘ ｋｘ(ｘ ,ｙ) Ｈ ｘ ｙ ｋｙ(ｘ ,ｙ) Ｈ ｙ =ｆ(ｘ ,ｙ,     

Application of linearized power system model to selection of PST controller input signal

This paper presents a selection method for phase shift transformer PST controller input signal. Simple conditions of input signal selection are obtained using frequency response analysis. The proposed method requires a suitable modeling of power system including PST device. The two types of power system models described in this paper are the nonlinear equations system model and the linearized model. The linearized model is represented as a block diagram transfer function model and as a state space representation model. The block diagram model presented in this paper has been used for the PST feedback input signal selection. Five locally available measurements at the switching node of the PST are considered. The results of frequency domain tests have confirmed that the block diagram transfer function model is a useful tool for power system analysis. The LQR method is used to achieve the final verification and the choice of input control signal.     

Coupled finite particle method with a modified particle shifting technology

The conventional SPH method has been frustrated with the low accuracy originated from the particle inconsistency. The finite particle method (FPM) is an improved SPH method with a higher‐order accuracy. However, the numerical accuracy and stability of FPM depend on the uniformity of particles. Facing the disorder particles, the conventional FPM may suffer from an ill‐conditioned corrective matrix and is difficult to conduct longtime simulations. A popular and robust particle regularization scheme is the so‐called particle shifting technology (PST), which can effectively enhance the accuracy and stability of particle methods. In the context of FPM, PST is analyzed and discussed, and a modified PST (MPST) is proposed. Modified PST saves great amount of computational cost with respect to the conventional PST and acquires better features of accuracy and stability. Finally, the coupled FPM method by combining MPST and δ‐SPH is developed to simulate a series of viscous flows. The numerical results indicate that MPST is effective in improving accuracy, stability, and efficiency of PST, and the coupled FPM is shown to be robust for simulating viscous flows and has a higher accuracy and stability.     

18脉冲双桥整流器的研究

为了降低电源电流中的谐波成分,减少电网污染,提出一种采用相移变压器的双桥18脉冲整流器拓朴结构,介绍了其工作原理,并且分析了相移变压器的功能以及消谐原理,最后对这种拓扑结构进行了仿真和实验研究.结果表明,这种整流器系统具有优良的工作性能,具有实际应用价值.