Thin-disc piezoceramic ultrasonic motor. Part II: system construction and control

Design and performance evaluation of an ultrasonic motor was discussed in [Wen et al., Thin-disc piezoelectric ultrasonic motor. Part I: design and performance evaluation, Ultrasonics]. Higher precision position control of piezoceramic ultrasonic motor depends on mechanical design and servo control of a very precise and adequate metrology. This paper proposes the design of a driving circuit and controller to deal with non-linearities behavior in the model of piezoceramic-driving ultrasonic motor. The performance of the driver and the effectiveness of the proposed controller are demonstrated by command inputs of sinusoidal and step signals. For comparison purpose, the ultrasonic motor is controlled using two methods: i.e., proportional-integral-derivative (PID) and sliding-mode control (SMC). It was proven that SMC would compensate automatically for unmodeled behaviors such as piezoceramic non-linearities and mechanical stick-slip phenomena. Furthermore, SMC scheme has been successfully applied to position tracking to demonstrate the excellent robust performance in noise rejection.     

An application of Bochner's technique to the deformations of the complex structure of

We consider the deformation of the complex structure of . We show that a harmonic deformation on equipped with the Fubini-Study metric is trivial if its supernorm is appropriately small.

     

用于脉冲γ强度测量的Ф60,1000μmPIN探测器

采用电阻率为10000—20000Ω.cm的高阻单晶硅材料,研制成功灵敏区尺寸为60mm,耗尽层厚度~1000μm的大面积厚PIN半导体探测器.设计了该类探测器厚度测量专用的反冲质子测量系统,对探测器的时间响应、γ灵敏度、漏电流、γ/n分辨等物理参数进行了测量和分析,结果表明,这类探测器可满足低强度裂变n/γ混合场中脉冲γ强度测量的需要.     

芴2,7位取代的9,9’-二芳基螺芴类化合物的合成及性能

设计并合成了一系列以三苯胺为核,芴衍生物为外围基团的有机蓝光小分子,该合成通过Suzuki反应在9-芳基芴的2位和(或)7位引入相同或不同取代基作为模块,并利用Friedel-Crafts反应将4-甲基三苯胺与这一系列模块结合.用NMR,MS和元素分析进行结构表征.荧光测试结果表明该类化合物溶液的荧光发射波长范围在442～466 nm之间,属蓝光发射.电化学测试显示该类材料的HOMO能级位于-5.15～-5.19 eV之间.差示扫描量热仪与热重分析得出化合物的玻璃化转变温度在166℃以上,热分解温度高于398℃,表明该类材料具有良好的热稳定性.     

SEGAL ALGEBRA $\[{A_{1,p}}(G)\]$ AND ITS MULTIPLIERS

Let G be a locally compactb abelian group and $\[{A_p}(G)\]$ the p-Fourier algeba of Herz. This pepar studies the space $\[{A_{1,p}}(G) = {L_1}(G) \cap {A_p}(G)\]$ with convolution product. It is proved that $\[{A_{1,p}}(G)\]$ is a character Segal algebra. Moreover, for the multipliers of $\[{A_{1,p}}(G)\]$ the author proves that $\[M({A_{1,p}}(G),{L_1}(G)) = M(G)\]$ and $\[M({A_{1,p}}(G),{A_{1,p}}(G)) = M(G)\]$ provided G is noncompact. If G is discrete, then $\[M({A_{1,p}}(G),{L_1}(G)) = {A_{1,p}}(G)\$ and $\[M({A_{1,p}}(G),{A_{1,p}}(G)) = {A_{1,p}}(G)\]$     

Finite groups acting 2-transitively on their sylow subgroups

In this paper we have completely determined: (1) all almost simple groups which act 2-transitively on one of their sets of Sylow p-subgroups. (2) all non-abelian simple groups T whose automorphism group acts 2-transitively on one of the sets of Sylow p-subgroups of T. (3) all finite groups which are 2-transitive on all their sets of Sylow subgroups. The first author acknowledges the support of OPR Scholarship of Australia The second author is supported by the National Natural Science Foundation of China. Thanks are also due to the Department of Mathematics, the University of Western Australia, where he did his part of this work for its hospitality     

隐含风险中性分布在巨灾超额损失再保险定价中的应用

通过与标的风险相关的期权市场估计出隐含变换系数,然后以Esscher变换为工具,将巨灾损失统计分布风险中性化,从而对以该非交易风险为标的的巨灾超额损失再保险进行定价.同时,从期权定价的角度,结合Weibull极值分布和超额损失再保险的特点,给出了巨灾超额损失再保险定价的闭型表达式.     

含噻吩环大环Schiff碱及其镧、钍配合物的合成

合成了三种新型含噻吩环大环Ｓｃｈｉｆｆ碱及其中一种与镧，钍的配合物。它们的结构均经ＩＲ，ＨＮＭＲ和元素分析表征。