TbDyFe超磁致伸缩材料机电耦合特性实验研究

主要讨论了ＴｂＤｙＦｅ超磁致伸缩材料电磁与机械耦合特性实验的若干问题，建立了电磁与机械耦合系统的物理模型并应用阻抗分析方法得到了相应的等效电路，设计制作了实验装置，测定了在电磁场与应力场共同作用下Ｔｂ，Ｄｙ１－ｘ，Ｆｅ２－ｘ三元稀土合金超磁致伸缩棒的机电耦合系数与电磁与机械耦合系统振动频率等，所得结果为进一步研制稀土超致伸缩换能器提供了重要的实验依据。     

稀土超磁致伸缩材料致动器的动力学特性分析

研究了超磁致伸缩微位移致动器的非线性动力学特性， 以应用于精密机械加工的微进给系统的稀土超磁致伸缩微位移致动器设计及实验数据为基础分析了碟．簧非线性刚度对微位移致动器动力学特性的影响。     

稀土功能材料的研究热点——超磁致伸缩材料

稀土超磁致伸缩材料的开发是目前稀土功能材料研究的热点。由于这种材料磁致伸缩值极大、机械响应快、功能密度高,可广泛用于声纳换能器、执行器和制动器等多方面,对潜艇、精密控制系统和机器人等高技术的发展具有重要意义。今年10月7日～8日中国稀土学会稀土固体科学与新材料专业委员会在上海组织了第一届超磁致伸缩学术会议。会上宣读的     

稀土基本知识（十一）：稀土超磁致伸缩材料及其应用

稀土超磁致伸缩材料是继稀土永磁、稀土发光、稀土高温超导材料之后兴起的又一种新型稀土功能材料，其应用领域非常广泛。从有源减振、燃料喷射系统、液体和阀门控制、微定位器到致动器、振子和声纳，对潜艇、精密控制系统和机器人等高技术的发展都具有重要意义。近年来，稀土超磁致伸缩材料正在成为世界各国的一个重要研究领域，许多发达国家投入了大量的人力、物力开展超磁致伸缩材料与器件的研究和开发。     

稀土超磁致伸缩材料发展概况

讨论了磁致伸缩效应的来源,介绍了稀土超磁致伸缩材料的特性和应用及目前的研究现状,重点评述了稀土超磁致伸缩材料的各种制备工艺和技术关键,介绍了"一步法"新工艺的特点,指出了今后的研究方向和工作重点。     

超磁致伸缩材料的制备技术研究进展

指出超磁致伸缩材料的制备工艺、性能优化,磁 机耦合过程的理论分析与实验研究,是超磁致伸缩材料研究的两大主题.定向凝固技术是目前国内外广泛采用的超磁致伸缩材料的制备方法.较全面地评述了各种传统的定向凝固技术和新型定向凝固技术的原理和工艺技术特点及存在的问题,提出了一种新的改进型定向凝固技术.     

Terfenol-D材料变负载时的磁致伸缩特性分析

关于稀土超磁致伸缩材料Terfenol-D的磁致伸缩特性国内外已有大量报道,但大多数都是基于载荷(预紧力)在磁致伸缩过程中保持不变条件下的磁致伸缩特性研究。本文在这些研究的基础上分析了Terfenol-D材料在变负载时的磁致伸缩特性,介绍了变负载动态特性曲线的求解方法并讨论了恒载与变载时特性曲线的特点与差异。     

稀土磁致伸缩材料

磁致伸缩——磁场强度从零变化到饱和时引起物体长度相对变化。据研究所知,磁致伸缩具有明显的方向依赖性。一、稀土磁致伸缩材料的概况超磁致伸缩材料出现于60年代。由于解决了材料的工业化工艺,近年来才正     

我国直径最大的稀土超磁致伸缩材料研制成功

北京有色金属研究总院稀土材料国家工程研究中心近日采用自行开发的“一步法”生产工艺 ,制成我国直径最大的稀土超磁致伸缩材料。其直径为 70ｍｍ、长 2 50ｍｍ ,主要技术经济指标均达到国际先进水平。“一步法”工艺即将熔炼—定向凝固—热处理等程序 ,在一台设备上连续完成 ,可用来制备大直径、高性能、低成本的稀土超磁致伸缩材料 ,且易于批量化生产。用这种工艺研制的稀土超磁致伸缩材料 ,成本不及国际售价的 1 8% ,可为我国军用、民用大功率换能器提供材料保障 ,具有重要的战略意义。据了解 ,目前我国研制的稀土超磁致伸缩材料直径一…     

酚醛粘结TbDyFe稀土磁致伸缩材料研究

采用取向织构合金粉开展了粘结稀土超磁致伸缩粘结工艺与性能研究。实验结果表明,对材料磁致伸缩影响显著的因素为粉末粒径和成形压力,在400 MPa压力下成形,粒径为250～420μm的粉末压制的样品拥有最大的磁致伸缩,无预应力时饱和磁致伸缩系数λs最大值为870×10~(-6)。16～20 KHz的磁场中,对材料损耗影响最大的因素为压制压力,压制压力高于400 MPa后材料的损耗降低至较低水平。     

Experiment on Nonlinear Properties Coupling Electromagnetism with Mechanics of Giant Rare Earth Magnetostrictive Materials

The electromagnetic and mechanical coupling properties of giant rare earth giant magnetostriction material TbxDy1 -xFe2 -z (0. 27 ≤x ≤ 0.3, 0 ≤ z ≤ 0.1 ) alloys were investigated by means of self-fabricated test apparatus. The effect of coupling mechanical with electromagnetic on magnetostrictive strain coefficient was discussed. The physical model of the coupling system was established. Based on the equivalent circuit of the coupling system, the magnetomechanical coupling coefficient was derived by means of impedance resistance analysis method.     

高效变频调速系统在太钢二钢连铸冷水系统中的应用

介绍了通用变频器在水泵上应用的节能原理,及其在连铸水处理二冷水系统的应用及功效。重点叙述了恒液位系统和恒压刀系统的构成及控制原理,以及本系统的应用和取得的经济效益。     

西门子S120卸料块伺服控制系统的改造

Φ159 mm生产线冷床上料卸料块是在线设备,卸料块原控制系统采用2台丹佛斯FC302变频器通过主从控制方式来控制2台丹佛斯伺服电机。原控制系统比较复杂,维护难度较大,备件订购周期长,因此制定了应用西门子S120主从控制替代原控制系统的方案。改造后效果明显,既满足了生产需要又便于维护,并且实现了现场设备的备件统一。     

Cyclic Filtration Apparatus for Testing Subballast under Rail Track

An apparatus capable of testing subballast-subgrade filtration behavior under cyclic loading is presented. The apparatus can be used to accurately monitor the pressure fluctuations, permeability of the filtration system, and turbidity variations of the effluent with time. The test results show that the frequency of cyclic loading has an influence on the filtration behavior of subballast material used in railway tracks. Further, the effect of cyclic load on the design and selection of subballast materials over a wet subgrade must be considered to avoid filter malfunctioning.     

Coupling among Pitch Motion, Axial Vibration, and Orbital Motion of Large Space Structures

The parameter dependency of large space structures on the coupling among attitude motion, structural vibration, and orbital motion has been investigated, particularly for structures such as tethered satellite systems. Tethered satellites are noticed for their possible applications. From space solar power systems to deorbit system, the applications of tethered satellites spread out over various fields. In this paper, we investigate planar motion of a satellite model, which consists of two tip particles and a massless spring. For such a space structure, the characteristics of the planar motion are shown to be determined by the mass ratio of tip particles, the natural frequency ratio of axial vibration to orbital motion, and the axial length ratio of the spring to the orbital radius. Among these three parameters, the natural frequency ratio has the greatest influence on the coupling phenomenon. Furthermore, the parameter range over which the coupling phenomenon occurs is specified.     

Boundary Finite-Element Method Coupling Finite-Element Method for Steady-State Analyses of Dam-Reservoir Systems

The boundary finite-element method (BFEM) is extended for steady-state analyses of dam-reservoir system problems. In this study, the dam is assumed to be rigid and subjected to horizontal ground motions, and the liquid in the reservoir is assumed to be semiinfinite. The semiinfinite reservoir domain is partitioned into two subdomains: a near-field domain and a far-field domain. In it, the near-field domain is modeled by using the finite-element method (FEM), whereas the far-field domain is modeled by BFEM and is treated as a layered semiinfinite fluid domain. A BFEM/FEM coupling procedure is employed to solve the steady-state response of the reservoir. The coupling procedure is easy to implement and suitable for all frequencies, be it real or complex. The BFEM/FEM coupling procedure is validated in the frequency domain. Numerical results that are based on the present procedure are in good agreement with analytical and other available numerical solutions.     

Position and velocity coupling of postural sway to somatosensory drive

Light touch contact of a fingertip to a stationary surface provides orientation information that enhances control of upright stance. Slight changes in contact force at the fingertip lead to sensory cues about the direction of body sway, allowing attenuation of sway. In the present study, the coupling of postural sway to a moving contact surface was investigated in detail. Head, center of mass, and center of pressure displacement were measured as the contact surface moved rhythmically at 0.1, 0.2, 0.4, 0.6, and 0.8 Hz. Stimulus amplitude decreased with frequency to maintain peak velocity constant across frequency. Head and body sway were highly coherent with contact surface motion at all frequencies except 0.8 Hz, where a drop-off in coherence was observed. Mean frequency of head and body sway matched the driving frequency 相似文献   

板坯连铸内外复合冷却流场和温度场耦合数值模拟

 针对1 240 mm×200 mm板坯连铸提出了一种钢水内外复合冷却技术，即在结晶器内设置内冷却器 U形管，起到提高传热效率改善铸坯内部组织之目的。运用流体力学分析软件，就内外复合冷却结晶器内钢水在流场温度场耦合作用下的凝固状况进行数值模拟，发现内冷却器可以使钢水的流动状态均匀和加快连铸坯的凝固速度。     

增力式夹具的设计与应用

增力式夹具结构紧凑，夹紧迅速可靠。它可以用较少的原动力获得较大的夹紧力，其增力倍数据实际须要同设计者调整。而且，若按机构自锁条件设计，该夹具夹紧之后，实现自锁。本文对该夹具结构做了介绍，并通过理论分析，指出增力系数和夹具自锁的设计条件。     

Efficiency and frequency of translational coupling between the bacteriophage T4 clamp loader genes

The bacteriophage T4 DNA polymerase holoenzyme is composed of the core polymerase, gene product 43 (gp43), in association with the "sliding clamp" of the T4 system, gp45. Sliding clamps are the processivity factors of DNA replication systems. The T4 sliding clamp comes to encircle DNA via the "clamp loader" activity inherent in two other T4 proteins: 44 and 62. These proteins assemble into a pentameric complex with a precise 4:1 stoichiometry of proteins 44 and 62. Previous work established that T4 genes 44 and 62, which are directly adjacent on polycistronic mRNA molecules, are-to some degree-translationally coupled. In the present study, measurement of the levels (monomers/cell) of the clamp loader subunits during the course of various T4 infections in different host cell backgrounds was accomplished by quantitative immunoblotting. The efficiency of translational coupling was obtained by determining the in vivo levels of gp62 that were synthesized when its translation was either coupled to or uncoupled from the upstream translation of gene 44. Levels of gp44 were also measured to determine the relative stoichiometry of synthesis and the percentage of gp44 translation that was transmitted across the intercistronic junction (coupling frequency). The results indicated a coupling efficiency of approximately 85% and a coupling frequency of approximately 25% between the 44-62 gene pair during the course of infection. Thus, translational coupling is the major factor in maintaining the 4:1 stoichiometry of synthesis of the clamp loader subunits. However, coupling does not appear to be an absolute requirement for the synthesis of gp62.