n阶泛函微分方程振动性综述

本文的目的是介绍n阶泛函微分方程振动性的若干近期成果。全文共五分部。首先我们做了必要的准备工作。在第二节中,介绍了适合于常微分方程和泛函微分方程的振动判据的情况。在作三节中,介绍了由滞后引起的振动。在第四节中对非齐次方程的振动性的发展给予介绍。     

隔水管非线性振动的线性化分析

本文在规则波浪与海流联合作用下对海洋钻井隔水管进行了动力分析,对非线性拖曳力采用改进的线性化方法,推导了有限元线性振动方程。求解这些方程几乎象静力方程一样,只需要少数几次迭代就可求得响应最大值。同时给出一些规则波浪与海流联合作用下的算例,并对由本文方法和由非线性时间域动力分析方法分别求得的两种结果进行了比较。比较表明,两种计算结果吻合。本文的线性化方法及把动力方程变换为静力方程的方法,能节约计算机时。隔水管是海洋工程中较典型的构件,该分析方法便于实际应用。     

测量薄膜参数的新型精密仪器PW—Ⅱ型光波导测试仪

“PW—Ⅱ型光波导测试仪”是我国首次研制成功的测量厚膜参数的新型精密仪器。文章介绍了该仪器的测量原理和结构特点。对仪器的测量精度进行了理论分析和数学推导,并采取了相应的技术措施,给出了精确的实测计算结果:薄膜折射率测量精度的绝对值≤1×10~(-4);薄膜厚度测量精度的绝对值≤1×10~(-2)μm。该仪器还可以用来精确测量薄膜的损耗,并能用于各向异性薄膜特性参数的测试与研究。     

Simultaneous Multithreading Fau Tolerance Processor

Transient fault detection mechanism is added to simultaneous muhithreading architecture. By exploiting both ILP (Instruction l~evel Parallelism) and TLP (Thread Level Parallelism), Simultaneous Multithreading(SMT) Fault Tolerance Processor can be expected to achieve better tradeoff between performance and hardware cost than traditional Fault Tolerance Processors. Detailed simulations of 3 of SPEC95 benchmarks show that executing two redundant programs on the fault-tolerant microarchitecture takes only 40%-61% longer than running a single version of the program. The new instruction fetch algorithm enhances the performance by 0. 4%～1% to most of the benchmarks we choose randomly.     

Modulation of low-frequency oscillations in GaAs MESFETs’ channel current by sidegating bias

Low-frequency oscillations in channel current are usually observed when measuring the GaAs MESFET‘s output characteristics. This paper studies the oscillations by testing the MESFET‘s output characteristics under different sidegate bias conditions. It is shown that the low-frequency oscillations of channel current are directly related to the sidegate bias. In other words, the sidegate bias can modulate the oscillations. Whether the sidegate bias varies positively or negatively, there will inevitably be a threshold voltage after which the low-frequency oscillations disappear. The observation is strongly dependent upon the peculiarities of channel-substrate (C-S) junction and impact ionization of traps-EL2 under high field. This conclusion is of particular pertinence to the design of low-noise GaAs IC‘s.     

基于前馈补偿器的无轴承同步磁阻电机解耦控制

建立了无轴承同步磁阻电机径向悬浮力及转矩部分的数学模型,其电磁转矩和径向悬浮力之间以及径向悬浮力自身在两轴方向上存在相互耦合.针对无轴承同步磁阻电机的强耦合、非线性特性,采用磁场定向控制难以直接进行解耦控制,采用基于前馈补偿器的解耦控制策略,成功解除了上述变量间的耦合关系.采用前馈补偿解耦得到的控制系统结构简单,实现方便.仿真研究表明,该解耦方法可实现无轴承同步磁阻电机稳定悬浮运行,能实现上述变量间的完全动态解耦,同时电机具有较好的转矩和调速性能.     

研究简报(Nd_(1-x)Er_x)_3 Fe_(27.31)Ti_(1.69)化合物的磁晶各向异性

用振动样品磁强计并结合X射线衍射准确判定了Nd2.4Er0.6Fe27.31Ti1.69化合物的磁晶各向异性方式,研究结果发现,Nd2.4Er0.6Fe27.31Ti1.69化合物的磁晶各向异性从室温时的易面转变到低温时的易锥.     

Synthesis, characterization and properties of diamidodisilanes and azocyclosilane

Organosilicon compounds have been widely researched and have the maximum species besides hydrocarbons. In the progress of the research work, many scientists pay attention to the organic silicon compounds that have vari-ety reactive functional groups[1,2]. The difunctional disi-lanes are very active; they could react with not only the compounds containing reactive hydrogen atoms, but also the reactive polymers. Therefore, the disilanes with di-functional groups could be used as disilane substit…     

一类二维离散混沌系统在不同系统参数下的自适应混沌同步

基于参量自适应控制中的混沌同步．针对一类二维离散混沌系统，提出了混沌系统在不同系统参数下的混沌同步方法，并给出了理论证明和实际应用例子。其理论结果很容易扩展到高维系统。     

Comparative Analysis and Development Trend of Rock Drill

A large number of pneumatic rock drills are being extensively used in a majority of mines in China nowadays, with a high noise level up to 125 dB（A） and large vibration and oil-fog on working-site, which can seriously jeopardize manipulator＇ s body and mind. Aiming at improving drilling environment and labor safety condition, the production mechanism of noise of all sorts of rock drills including pneumatic hydraulic and water-powered rock drills and measures of reducing noise level of pneumatic rock drills in special were discussed and led to the conclusion of that the pneumatic rock drills should be eliminated step by step, the hydraulic rock drill should be developed at full speed and especially the water-powered rock drill should be studied and applied according to the situation of China. In addition, the reasons of why hydraulic rock drills have not yet been used extensively and spread wide areas in China were discussed. The main technical parameters of newly developed leg-supporting water-powered rock drill and the comparation of experimental data between pneumatic rock drill and hydraulic rock drill were listed. The experimental results show that water-powered rock drill possesses the same superior properties as hydraulic rock drill and its noise is less than 20 dB（A） than pneumatic rock drill and there is no oil-fog on the working-site and vibration is reduced largely~ but its drilling speed is raised largely , its structure is simpler, and maintenance is convenient. Therefore, popularizing applying of water-powered rock drill will be an effective way of improving mine working environment according to the current situation of China.