海洋重力传感器伺服回路分析与设计

海洋重力仪是改善舰船惯导系统精度的重要设备，其重力传感器的伺服回路决定着仪器的精度和动态性能。作在介绍零长弹簧海洋重力传感器结构原理的基础上，研究其伺服回路的结构组成和设计方法，分析了其主要环节参数对系统性能的影响，考察了其时域性能，对海洋重力仪的研制具有重要指导作用。     

梯度磁场中薄膜厚度梯度的形成机理

借助于基片下方放置的磁铁，在溅射的放电空间中引入了纵向的梯度磁场，辉光放电时，其外貌发生了显著的收缩，由此沉积的薄膜在平面内存在明显的厚度梯度，用磁场中带电粒子的运动理论解释了此种薄膜的形成机制。     

Biostimulation-enhanced Biodegradation of Nitrobenzene in Contaminated Groundwater

In this study, biostimulation technology was used for bioremediation of nitrobenzene-contaminated groundwater by adding a mixture of lactose and phosphate, peptone, and beef extract. During the process of biostimulation, the remediation effectiveness, microbial dehydrogenase activities and microbial densities were investigated; the varieties of microbial community structure and composition were analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE) technique and the relative abundances of nitrobenzene-degrading gene(nbzA) were determined by fluorescence quantitative real-time PCR(RT-PCR). Findings show that the removal rate of nitrobenzene in groundwater could reach about 60% by biostimulation with lactose and phosphate, 70% with peptone and 68% with beef extract. The microbial dehydrogenase activities and microbial densities were all improved obviously via biostimulation. The results of PCR-DGGE show that the microbial diversities were improved, and more than ten kinds of dominant microorganisms were detected after biostimulation. RT-PCR results show that the relative abundances of nbzA gene of microbes in groundwater were increased significantly, which indicated that biostimulation actually enhanced the growth of nitrobenzene-degrading bacteria. Therefore, biostimulation is a cost-effective and feasible bioremediation technique for nitrobenzene-contaminated groundwater.     

SINE TRANSFORM MATRIX FOR SOLVING TOEPLITZ MATRIX PROBLEMS

1. IntroductionStrang[1] first studied the use of circulallt matrices C for solving systems of linear eqllationsTi x = b witha symmetric positive definite Toeplitz matrix.Numerous authors such as T.Chan[2],R.Chan,etc.[3],[4],[5], Tyrtyshnikov[6], Huckle[7] and T.Ku and C.Kuo[8] proposed differentfamilies of circulallt / skew- circulant precondit ioners.Appling the preconditioned conjugate gradient algorithm(PCGA) to solve the systems Ti x -b, we must find a preconditioner P such that P…     

活塞圆筒装置压力盘样品组装的温度测定和热结构分析

活塞圆筒是目前使用最广泛的固体介质高温高压装置,样品组装方式和组装件的材料类型决定了高压腔体内部的热结构特征。在0.5、1.0、1.5 GPa压力下、800~1 400 ℃范围内,采用改进的双热电偶法、尖晶石反应测温法对QUICKpress型活塞圆筒的13 mm压力盘的样品组装进行了温度测定,通过获得的实验数据并结合傅里叶热传导模拟结果进行了热结构分析。实验结果表明：(1)热峰位置均位于有效石墨炉中心以下,即靠近钢塞一侧,20 ℃温差范围的热点区轴向分布区域大小介于2.8~5.2 mm,其热梯度为7.7~13.0 ℃/mm,而非热点区热梯度为42~83 ℃/mm;(2)随着温度或压力升高,热峰倾向于朝有效石墨炉中心靠拢,同时伴随着炉内热梯度增大和热点区变小,温度的影响更为显著。还对活塞圆筒压力组装的热结构的影响因素及相关问题进行了探讨。

     

多级感应线圈炮最优发射控制策略

基于电路理论,建立了多级感应线圈炮数学机电控制模型;分析了电枢受力的影响因素,结果表明,电枢受力决定于驱动线圈和电枢的电流大小和它们之间的互感梯度。总结了多级同步感应线圈炮设计原则,根据设计原则,提出了感应线圈炮的最优发射控制策略,并从理论上证明其可行性,最后以10级线圈炮为例,归纳了多级感应线圈炮的触发公式,并进行了实验验证,其结果表明,通过修正触发公式,仿真结果与测量值吻合较好。