Concentrated and gastight sampling technique of deepsea microplankton

A new sampling method of deepsea microplankton with function of in-situ concentrated sampling and gastight sampling was proposed. In-situ concentrated sampling technique was realized as follows: a microplankton membrane was used as filtration membrane, and a deepsea pump was used to pump seawater; the microplankton was captured and the density of microplankton was increased when seawater flow through the filtration membrane. Gastight sampling technique was realized as follows: a precharged accumulator was used as pressure compensator. During the process of lifting the sampler, the accumulator compensated the pressure drop continuously. The laboratory experimental results show that with in-situ concentrated sampling technique, in-situ concentrated sampling can be realized and the maximum concentration ratio reaches up to 500. With pressure compensation technique based on accumulator, gastight sampling can be realized. When sampling at 6 km and the precharge pressure of accumulator is 18 MPa, pressure drop of the sample is less than 2% compared with its original pressure. Deepsea experiment (at 1.9 km) results show that the sampler can realize in-situ concentrated sampling and gastight sampling.     

三相反应式步进电动机建模及常用控制方法仿真

以三相反应式步进电动机结构及其电磁回路特点为基础建立了完整的仿真模型;在已建立模型的基础上对步进电动机常用控制方法进行了仿真研究。其结果对于反应式步进电动机的控制及设计有一定的参考价值。     

丙烯腈／酯酸乙烯酯单体的室温引发浓乳液聚合

研究了丙烯腈 /醋酸乙烯酯单体的室温引发自加热的浓乳液聚合方法。探讨了聚合过程中主要参数对转化率和分子量的影响。最终得出 ,浓乳液聚合方法是实现室温引发、自加热聚合的首选方法。     

The Hu–Washizu variational principle for the identification of imperfections in beams

This paper presents a procedure for the identification of imperfections of structural parameters based on displacement measurements by static tests. The proposed procedure is based on the well‐known Hu–Washizu variational principle, suitably modified to account for the response measurements, which is able to provide closed‐form solutions to some inverse problems for the identification of structural parameter imperfections in beams. Copyright © 2008 John Wiley & Sons, Ltd.     

An estimate of the limit state of power transformers and autotransformers

The main indicators of the limit technical state of transformers and autotransformers, for which their further use is impermissible or inadvisable, are considered. The main elements of a power transformer which determine its limit state are the windings and the cores. Important indicators for estimating the technical state of the windings is the wear of the coil insulation, the degree of mechanical fastening of the windings and, in particular, the absence of dangerous deformations. Wear of the coil insulation is estimated from the degree of polymerization and the short-circuit resistance. The cores of the transformer become damaged fairly rapidly during operation. Normalized values of the above indicators are given as well as experience in using them in the Russian Federation and the Ukraine to estimate the limit state of transformers and autotransformers. The amount of inspection in order to reach conclusions on the technical state of a transformer and temporary measures until they are replaced are indicated. __________ Translated from élektricheskie Stantsii, No. 1, pp. 44–49, 2008.     

Application of AZ4903 to production of stator windings

To satisfy the needs of the high deep-width ratio and thickness of a planar micromotor’s stator windings, a process method to produce an electromagnetic planar micromotor with AZ4903 is proposed. Optimum relationships, such as the desired rotation speed vs. thickness of the coating process, and the temperature vs. time of pre-baking, are obtained. The appropriate time of lithography and development are also achieved. The thickness of the produced windings is 40 μm with ideal perpendicularity. Finally, stators and rotors are fabricated. The rotation speed and pull-out torque of the micromotor are tested. The experiment proved that the micromotor worked with a steady speed and a low ripple of pull-out torque. __________ Translated from J Tsinghua Univ (Sci & Tech) 2005, 45(8): 1062–1065 [译自: 清华大学学报(自然科学版)]     

含集中参数弹性梁振动特性解析与实验识别

基于Laplace变换推导出含集中质量与集中刚度弹性梁的振型函数和典型边界条件对应的频率方程,针对有一个集中质量与一个集中刚度的悬臂梁,求解出其固有特性,并利用基于自然激励技术(natural excitation technique,简称NExT)的特征系统实现算法(eigensystem realization algorithm,简称ERA),即NExT-ERA法对相应结构系统进行了模态识别。通过对比解析结果和实验结果,分别讨论了集中质量与集中刚度大小变化和位置变化时对梁振动特性的影响,得出了集中质量和集中刚度在悬臂梁上位置和大小变化时,悬臂梁固有频率的相应变化规律,为工程中具有集中质量和集中刚度等直弹性梁的振动分析方法和集中参数布置设计提供了参考。     

浓磷酸沉降与澄清技术的进展

介绍了云天化云峰分公司产能为28万t/a磷酸装置,针对磷矿品位的不断下降,杂质含量的不断升高,造成酸品质差,波动较大,从而影响到下游磷复肥产品的问题,采用了浓磷酸沉降与澄清技术,并改变絮凝剂加入方式。结果表明,2013年1~7月浓酸含固量平均为0.917%,为生产合格的18-46-0的DAP创造了条件。     

湿法磷酸生产浓磷酸淤渣分离设备的选型

针对湿法磷酸生产中浓磷酸淤渣难以利用的问题,提出浓磷酸淤渣分离方法,并对分离设备进行了选型试验,给出了试验的过程及参数。结果表明,卧式螺旋卸料沉降离心机适用于浓磷酸淤渣分离,分离后清液w(固)为1.64%,滤渣w(H2O)为47.81%。     

浅埋房式采空区集中煤柱下综采动载控制研究

石圪台煤矿31201综采工作面过上方房式采空区集中煤柱后,上煤层顶板运动造成下煤层综采面大量支架压死。通过建立过煤柱阶段覆岩结构模型,推导出工作面在出煤柱时的结构必然失稳是动载力源,辅以数值模拟揭示了动载矿压大于支架工作阻力的压架机理,由此提出预先爆破煤柱、释放岩层能量的治理方案。同步进行地面钻孔位移监测、从地面和井下钻孔布置传感器进行微震监测,掌握矿压显现特征,预警了动压危险。地表钻孔窥视说明了过煤柱动载显然要大于进入煤柱期间的动载,多点位移观测和微震观测说明预警爆破措施可有效防治动载矿压。