压电换能器输出声功率的电测法

本文介绍压电换能器实用状态下声功率的脉冲、恒压、恒流等6种测量方法.阐述了各方法的测量原理、适用范围及对各种方法的比较和评价.     

A new satellite to satellite tracking algorithm from Doppler-shifted frequency measurements

A new satellite to satellite tracking (SST) algorithm from Doppler-shifted frequency measurements is proposed. The estimation principle is demonstrated and the mathematic model of SST is established. The state estimation methods for a user (the cooperative case) and target satellites (the non-cooperative case) are presented based on particle swarm optimization (PSO). The Cramer-Rao lower bounds (CRLB) are deduced as well. Performance of the new algorithm is validated through computer simulations, which proved that the proposed method is effective in terms of the estimation quality compared with CRLB and superior in accuracy to the Bearings-Only (BO) method in almost all simulation cases except for the case that an enough long tracking arc-length is obtained for a user satellite.     

一类状态时滞系统的最优预见控制器设计

研究了一类状态时滞系统的最优预见控制器设计问题. 首先通过差分将所研究的时滞系统转化为形式上不含时滞的一般系统,然后根据已有的无时滞系统的预见控制理论设计出系统的控制器,并且给出了所设计的控制器存在的充分条件.仿真实验说明了预见前馈补偿的有效性.     

介质颗粒在尘埃等离子体金属棘轮中的运动

通过实验研究了等离子体环境中金属棘轮对介质尘埃颗粒的整流过程.单分散聚苯乙烯颗粒悬浮在处于等离子体环境中的金属棘轮通道内,通过调节气压和放电功率实现了对颗粒的整流,颗粒在锯齿通道内做可控性定向运动.实验中只观察到颗粒的逆向运动.由于金属棘轮电势低,其表面较厚的鞘层对颗粒形成较强的约束,颗粒受到的非平衡切向离子拖曳合力更大,这将引起颗粒更快的定向运动.实验结果为建立尘埃等离子体棘轮模型奠定基础.     

大气折射对高程约束下时差定位误差的影响及修正

电波在不均匀大气中传播会发生折射现象,传播路径和速度都会发生改变,若不考虑其影响,将导致利用测量多站到达时间差进行辐射源定位产生较大误差。本文分析了已知先验高程约束条件下大气折射对多站时差定位误差的影响,论证了迭代修正法在高程约束条件下(约束条件为冗余条件)无法达到最优,提出了大气折射条件下基于迭代然后再进行改进粒子群优化的时差定位误差修正算法,通过仿真分析验证了该修正算法的有效性。     

Research of united model of knowledge discovery state space and its application

1.INTRODUCTION Atpresent,complextypedatamining,suchasmulti media,audio,video,image,Webpage,spatial tem poraldataetc.,isreceivingmoreandmoreattention frombothresearchandbusinesscommunity.Howto exploittheexistingminingtechniquesofstructured datatocomplextypesofdata?Canweproposeacom montheoreticalframeworkforminingbothstructured dataandcomplextypesofdata?Wethinkitisurgent forustotrytoanswertheabovequestions.Fromdifferentperspectives,suchasevidencetheo ry,roughsetetc.,someresearchershaveprop…     

教师队伍结构优化目标的动态管理系统

根据目标年的教师队伍结构的规划,运用数学模型,建立了教师队伍的管理系统.根据每一年的变化,找出了下一年教师队伍结构的量化控制方法,并给出了相应的对策,使得整体结构逐步达到目标要求.     

多重采样离散时间系统的最优预见伺服控制器设计

研究了具有多重采样特点的离散时间控制系统,对这类系统给出了一种最优预见控制器的设计方法.首先利用离散时间系统提升技术,把多重采样离散时间系统转化成单一采样的扩大系统.然后利用构造扩大误差系统的方法引入积分器.再对扩大误差系统应用通常的线性二次型最优预见伺服系统设计方法设计控制器,从而得到原系统的多重采样最优预见控制器.     

Stratigraphy and age of the Daohugou Bed in Ningcheng, Inner Mongolia

Recent fieldwork has extended the distribution of the Daohugou Bed deposits from the Daohugou Village to its several neighboring areas. The fossil-bearing Daohugou deposits uncomformably overlie complex bedrocks, and comprise three major parts. The red shales in the lower part were misidentified as belonging to the Tuchengzi Formation. Field excavation has indicated that the shales of upper part of the bed are the major fossil-bearing horizon. Due to strong tectonic activities, sediments were often folded with the sequences inverted in the region. Some newly recognized contacts between the Daohugou Bed and the volcanic rocks showed that the ignimbrite of the Tiaojishan Formation （159-164 Ma） underlies the Daohugou deposits, rather than overlying the latter as previously proposed. Thus, the age of the Daohugou deposits should be younger than the age of the ignimbrite, and thus it was incorrect to correlate the Daohugou Bed with the Middle Jurassic Jiulongshan Formation. Although biostratigraphic studies based on conchostracans and insects support a Middle Jurassic-early Late Jurassic age for the Daohugou deposits, vertebrate fossils such as Liaoxitriton, Jeholopterus and feathered maniraptorans show much resemblance to those of the Yixian Formation. In other words, despite the absence of Lycoptera, a typical fish of the Jehol Biota, the Daohugou vertebrate assemblage is closer to that of the Early Cretaceous Jehol Biota than to any other biota. We propose that the Daohugou fossil assemblage probably represents the earliest evolutionary stage of the Jehol Biota based on both vertebrate biostratigraphy and the sedimentological and volcanic features which suggest the Daohugou deposit belongs to the same cycle of volcanism and sedimentation as the Yixian Formation of the Jehol Group.     

RE－B—Ti共渗及其耐磨性和耐蚀性的研究

研究了固体粉末法ＲＥ－Ｂ－Ｔｉ共渗工艺，渗层的耐磨性和耐蚀性．结果表明选用合适的渗剂对Ｔ１０钢进行共渗处理，渗层的耐磨性及耐蚀性均优于单一渗硼层和渗钛层；稀土元素具有催渗作用，其最佳浓度约为５％，此时渗层最厚，且其耐磨性及耐蚀性亦最好．