Influence of Magnetic Field on the Rectification Process of Binary Heterogeneous Azeotrope

To improve separate effect of binary heterogeneous azeotrope in the magnetic field with different magnetic induction intensity, the influence of magnetic field on the rectification process of binary heterogeneous azeotrope was investigated with l-butanol-water system. The results show that the composition of liquid-liquid phase equilibrium of l-butanol-water system has definitely changed, the composition of l-butanol in light phase （l-butanol layer） increases by 1. 17%-1.63% and the composition of water in heavy phase （water layer） increases by 1.21%-1.58% under the influence of magnetic field. By separation of magnetization, the composition of l-butanol increases by 0.8%-1.2% and the recovery ratio of 1 -butanol increases by 1.6%-2.5%. Magnetic field has positive effect, however, the magnetized effect is not in proportion to magnetic induction intensity and has an optimum condition, in the range of 0.25 T-0. 3 T.     

Calculating magnetic shielding effectiveness for high-power dc comparator by magnetic circuit method

Magnetic shielding is very important in the design of a high-power dc comparator. This paper addressed the application of magnetic circuit method to calculate the magnetic shielding effectiveness of high-power dc comparators when an external radial magnetic field is added. The mathematical relationship between the magnetic shielding effectiveness and the parameters of the magnetic shielding body were obtained. To verify the validity of the calculation method, we developped a procedure to measure the magnetic shielding effectiveness of the magnetic body by measuring the induction voltage of the detection winding instead of the magnetic intensity at a point in the magnetic shielding body, making the manipulation much easier. The result calculated with the magnetic circuit method turns out to be closer to the measured one compared with that calculated with a conventional algorithm proposed by Ren, suggesting that the magnetic circuit method is an applicable tool for estimating the toroidal cavity magnetic shielding effectiveness of a heavy current comparator when a radial magnetic field is added.     

Research on electromagnetic relay＇s dynamic characteristics disturbed by uniform static magnetic field

Electromagnetic relay is a widely used apparatus which usually works in a magnetic disturbance environment. To evaluate its electromagnetic compatibility （EMC） in a static magnetic field, dynamic characteristics of a clapper relay in a uniform static magnetic field situation based on the finite element method （FEM） is studied. Influences of the magnetic field on dynamic parameters （delay time, pick-up time, end pressure, and final velocity） as well as a situation in which the relay cannot function normally are analyzed. Simulation reveals that the external magnetic field which weakens the relay＇s air-gap field has a greater influence on the relay＇s dynamic parameters than the one strengthening the field. The validity of the simulation is verified by measured results of coil current and armature displacement.     

Nonlinear identification of electro-magnetic force model

Conventional attractive magnetic force models （proportional to the coil current squared and inversely proportional to the gap squared） cannot simulate the nonlinear responses of magnetic bearings in the presence of electromagnetic losses,flux leakage or saturation of iron.In this paper,based on results from an experimental set-up designed to study magnetic force,a novel parametric model is presented in the form of a nonlinear polynomial with unknown coefficients.The parameters of the proposed model are identified using the weighted residual method.Validations of the model identified were performed by comparing the results in time and frequency domains.The results show a good correlation between experiments and numerical simulations.     

分层流体中弧立波的理论分析和符号运算研究

The study of solitary waves has been a subject highly popular and full of interest sinec Russell[1]first observed the solitary waves in a channel and the research on the internal solitary waves in stratified fluids is one of the branches of this subject.There are extensively internal solitary waves in the atmosphere,oceans.fjords and lakes.To study them is of academic and practical significance[2].Numerous investigators have made contributions since the theoretical work on internal solitary waves was initiated by Keulegan[3].Nevertheless,some problems remain still to be discussed,for example,the higher-order theories for one-dimensional internal solitary waves in stratified fluids of small depth,the two-dimensional internal solitary waves,the explanation of the experimental and the practical phenomena by means of theoretical analysis.In this thesis,we hope to gain an insight into the above three items by combining of theoretical analysis and symbolic computation.The following work has been completed.     

Study on the heat transfer of cross flow in vertical upward tubes

INTRODUCTION Cross flow and heat transfer were widely found in oil production and chemical facilities.A detailed study of the hydrodynamic characteristics and heat transfer of cross flow is necessary for optimal design of the system and the development of new measuring techniques.Studies on the heat transfer in sin-gle-phase liquid cross flow were carried out in the past decades.Air or water was often chosen as the working fluid,in these studies commonly focused on fluids flowing across r…     

旋转电机磁场计算的数值解析结合法

A numerical-analytical method is applied for the two-dimensional magnetic field computation in rotational electric machines in this paper. The analytical expressions for air gap magnetic field are derived. The pole pairs in the expressions are taken into account so that the solution region can be reduced within one periodic range. The numerical and analytical magnetic field equations are linked with equal vector magnetic potential boundary conditions. The magnetic field of a brushless permanent magnet machine is com-     

Sensors Array Technique for Monitoring Aluminum Alloy Spot Welding

In this paper,the sensors array technique is applied to the quality detection of aluminum alloy spot welding.The sensors array has three forms,i.e.,linear magnetic sensors array,annular magnetic sensors array and cross magnetic sensors array.An algorithm based on principal component analysis is proposed to extract the signal eigenvalues.The three types of magnetic sensors array are used in the experiment of monitoring the signal.After the eigenvalues are extracted,they are used to build a relationship with ...     

Influence of Zeotropic Mixtures＇ Performance of Heat Transfer in Temperature Gliding on the Condenser or Evaporator

Many zeotropic refrigerant mixtures are proposed as alternatives to some chlorofluorocarbons（CFCs） and hydrochlorofluorocarbons （ HCFCs ）. An advantage of zeotropic mixtures is the possibility of reduction in entropy generation by matching the temperature glidings of refrigerant and heat-transfer fluid in both condenser and evaporator. Zeotropic mixtures are compared with pure refrigerants to evaluate their exergetic losses. On the other hand, the special phenomena which result from temperature gliding are proved by experiments. A simple equation is obtained, to evaluate different zeotropic mixtures＇ exergetic losses. The maximum flow rate of heat-transfer fluids is found in order that refrigerants phase change can be completed. Lastly, some examples of zeotropic mixtures （R407C, R405A and R414B） are given, and their exergetic losses and maximum flow rate of heat-transfer fluids in condenser are forecasted.     

A tunable dual-broad-band branch-line coupler utilizing composite right／left-handed transmission lines

INTRODUCTION Veselago (1968) theoretically analyzed the wave propagation in a left-handed (LH) material which has simultaneously a negative magnetic permeability and a negative electric permittivity. The electric field, the magnetic field, and the wave vector of an electro-magnetic wave propagating in such a material obey the left-hand rule (instead of the right-hand rule for usual materials). Such an LH material was first real-ized in 2001 in microwave region with an array of metallic …     

铁磁液体所受磁力的几种数学模型及应用

探讨了铁磁流体的性质，推导出了铁磁液体所受磁力的几种数学模型，最后研究了由于磁力的作用，铁磁流体表面内和表面外的压强值不同。     

不锈钢铝合金半固态连接工艺参数研究

By using semisolid joining technique,the bonding of stainless steel and semisolid aluminum alloy is successfully realized.The relationships between interracial shear strength and solid fraction of aluminum alloy,bonding pressure and time of keeping pressure were studied by the method of orthogonal experiment.The interfacial structure and the fracture structure of the bonding plate are studied by means of optical microscope (OM) and scanning electron microscope (SEM).The results show that there is the best solid fraction between the solid phase line and the liquid phase line of the semisolid aluminum alloy,with the increase of bonding pressure and pressure time,the interfacial shear strength increases rapidly,and then with further increase of bonding pressure and pressure time,the shear strength rises little.Along the interface,solid phase and liquid phase bond with stainless steel by turns because of the different diffusion ability.So,a new type of non-equilibrium diffusion interfacial structure is constructed at the interface of stainless steel and aluminum alloy,compound mechanism of plastic and brittle fracture interface was formed at the shear fracture interface.     

镝钕改性铁氧磁流体的制备与表征

为了研制工艺简单且饱和磁化强度高的磁流体,本文采用化学共沉淀法通过对铁氧体磁流体改性制备了水基镝钕复合铁氧体磁流体,实验讨论了温度、镝与钕的配比及用量、表面活性剂的用量、pH值对磁流体稳定性,改变工艺流程的影响,其结果表明:(1)在n(Fe):[n(Nd3+)+n(Dy3+)]=14:1,n(Fe3+):n(Fe2+)=1.70~1.75,镝与钕的用量比为n(Nd3+):n(Dy3+)=1:1,25%NH3.H2O作为沉淀剂和pH值的调节剂,反应体系温度控制在35℃左右,调pH值至9~11;(2)以明胶作为表面活性剂,其最佳用量是每60 mL载液0.005 0 g,包裹温度在55℃左右,包裹最佳pH=4。该条件下制得黑亮的水基镝钕铁氧磁流体,其磁性能比普通水基铁氧体高。在可见光的照射和磁场的共同作用下,可以看到明亮的磁光环产生。同时,还对产品的黏度、磁化强度、表面包覆情况、稳定性等进行了相应的表征。     

真空预压法加固软基的流固耦合数值分析

利用数值分析方法建立了软土地基模型,采用比奥固结理论,计算分析了真空预压下的软土地基流固耦合作用;并进一步分析了真空度损耗率、密封墙、塑料排水板打设深度等因素对软基加固效果的影响。分析结果表明:在抽真空早期,地表沉降增长很快,达到一定天数后,沉降值逐渐趋于稳定;真空负压沿深度、水平方向上损耗,在加固软土外围形成一个零孔隙水压力面;真空度损耗率、塑料排水板打设深度对真空预压加固软土的效果影响很大;侧向密封墙对加固区内土体影响不大,但其限制了真空负压的侧向传递,使影响区的地基沉降大幅减小。     

带有端面辅助密封作用的刀口机械密封结构

从密封结构改进的角度,提出了带有端面辅助密封作用的刀口机械密封结构及设计的基本思想。该密封结构具有密封比压高、周向分布均匀、摩擦副磨损补偿能力强、磨损消耗功率小、密封稳定性好、工作可靠等特点。由于介质端动静环密封处的特殊结构处理,本结构适用于密封介质压力和粘度较大、转速较高的场合。另外,还对密封结构的主要零件的设计和选择提出了建议。     

Fe／Mo（110）的电磁性质：第一性原理研究

应用自旋极化的第一性原理对在Mo（110）衬底上生长Fe薄膜进行系统研究．计算结果表明：紧邻界面的Mo原子层向外驰豫,而Fe原子层则表现向内驰豫．Fe／Mo（110）系统的键合表现为各向异性,在平行于Mo（110）表面方向,各个原子之间都表现为金属键,而在垂至于Mo（110）表面方向,Fe原子之间、Fe原子和Mo原子之间却表现为金属键．Fe／Mo薄膜中,Fe原子的磁矩大于体材料Fe原子的磁矩,以铁磁方式排列,并且在紧邻界面的Mo原子诱导出少量的磁矩,这些磁矩与Fe原子以反铁磁的方式排列．     

筋带-砂-粘土层状体系直剪试验研究

为了研究粘土与加筋材料接触面之间的力学特性,及砂对粘土与筋带接触面力学特性的改善情况,采用直剪试验方法对粘土与聚丙烯土工带polypropylene在粘土不同含水量条件下进行了不同法向荷载作用的直剪试验,讨论了法向应力、含水量对高液限粘土与筋带之间剪切特性的影响;设计了筋带砂粘土层状布置体系的加筋土结构模型,并根据设计的模型进行直剪试验.试验结果表明:粘土与筋带接触面之间的剪切强度随着法向应力的增加呈非线性增长;接触面的摩擦系数随着含水量的增加而减小,接触面的粘聚力随含水量的增加先增大后减小,粘土与接触面之间存在一个最佳的含水量,这个值要比粘土压实的最佳含水量低2%左右;筋带砂粘土层状布置体系表明砂对粘土与筋带的剪切特性起到明显的改善作用.     

润滑油抗乳化性能研究创新型实验设计

根据目前润滑油抗乳化性研究最新进展与国家标准,设计了创新研究型的润滑油抗乳化性能研究实验。该实验模拟实际工况条件,改变油水比,设计单次乳化以及多次连续乳化实验,除采用传统的分水率、分水速度、油水外观和界面齐整度以及乳化层厚度等抗乳化性评价指标外,还利用紫外分光光度法测定了水相含油量,利用微量水分全自动测定仪测定了油相含水量,从而对润滑油抗乳化性能进行了综合评价。此外,还可将实验内容进行拓展,通过测试油水的界面张力、界面膜强度以及乳液粒径分布和光谱稳定性来分析润滑油抗乳化性能的微观作用机制。     

Study on Interfacial Bonding State of Ag-Cu in Cold Pressure Welding

Thetechnologyofcoldpressureweldingiswidelyusedtoachievethejoiningofthesameordifferentmetalswithdif ferentthermal physicspropertiesandotherconditions ,foritsparesenergysources ,simplifiestheweldingequipment,anditdoesnotneedtobeheatedanddoesnotcausethemeltingandtheheateffectzone ,brittlecompounds .Accordinglythetechnologymaybesatisfyingwithdemandforcomprehensivepropertiesinindustry ,andwillsettletheconflictbetweentheincreasingdeficienciesandgrowingdemands .Onthesideofmetallurgicability[1] ,thewe…     

纳米磁性液体材料的研究进展

综述了国内外纳米磁性液体材料的发展现状。磁性液体材料是一种特殊的新型材料,是由磁性纳米微粒(一般要求小于10nm)均匀弥散于某种液体基液中所构成的稳定体系。同时具有磁性和流动性,因此具有许多独特的磁学,流动力学,光学和声学特性。系统介绍了目前纳米磁性液体材料根据纳米磁性液体材料中的铁磁性固体颗粒的不同的分类及纳米磁性液体材料的基本性质。最后综述介绍了纳米磁性液体依据其独有的特殊性能和其在化工环保、印刷制造、医疗卫生、仪器仪表、航天航空中典型应用。同时比较了国内外纳米磁性液体材料的发展状况。