Influence of thermal treatments on the elastic parameters in iron rich metallic glasses

The change of magnetoelastic properties after thermal treatments has been investigated for two groups of metallic glasses. (Fe₇₉Co₂₁)_75+xSi_15−1.4xB_10+0.4x (x (at.%)=0, 2, 4, 6, 8, 10) has been studied both in the as-prepared state and after thermal annealing in an applied magnetic field, to achieve a particular domain structure, at temperatures well below the crystallization temperatures. Changes in the ΔE effect, magnetomechanical coupling (k) and internal friction coefficient (Q⁻¹) are reported, reaching values of about 60% of the saturation value E_S. Fe₆₄Ni₁₀Nb₃Cu₁Si₁₃B₉ alloys annealed in vacuum for 1 h in the temperature range 350–550 °C showed maximum values of the ΔE effect and k of 61% and 0.85, respectively, accompanied by a minimum value of Q of around 2 for the sample annealed at 460 °C. These variations are related to the progress of nanocrystalization. The properties achieved are among the best reported for magnetomechanical applications.     

厚膜永磁阵列微致动器的磁路研究

研究了厚膜永磁阵列微致动器中的磁场分布，并研究了永磁阵列单元几何尺寸对微致动器电磁力的影响。结果表明，厚膜永磁阵列单元高宽比和磁体单元间隔对微致动器电磁力影响较大磁徕单元高宽比为0．7是一个比较合适的尺寸。     

Mechanical spectroscopy in commercial Fe–6 wt.% Si alloys between 400 and 1000 K

Mechanical spectroscopy, neutron diffraction and differential scanning calorimetry (DSC) were performed on commercial Fe–6 wt.% Si alloy after quenching from high temperature. The damping spectrum shows a peak at around 800 K and an associated modulus defect. The modulus shows an increase during the second and subsequent heating runs. In addition, an anomaly in the modulus behavior has been found at around 400 K. Different thermal treatments allows to obtain two different recovery degrees of the quenched-in defects. The influence of the recovery degree on the 800 K internal friction peak and on the anelastic modulus has been evaluated and confirm the validity of the grain boundary mechanism associated to this peak. Experimental results are discussed on the basis of recovery and ordering processes.     

A suitable computational strategy for the parametric analysis of problems with multiple contact

The aim of the present work is to develop an application of the LArge Time INcrement (LATIN) approach for the parametric analysis of static problems with multiple contacts. The methodology adopted was originally introduced to solve viscoplastic and large‐transformation problems. Here, the applications concern elastic, quasi‐static structural assemblies with local non‐linearities such as unilateral contact with friction. Our approach is based on a decomposition of the assembly into substructures and interfaces. The interfaces play the vital role of enabling the local non‐linearities, such as contact and friction, to be modelled easily and accurately. The problem on each substructure is solved by the finite element method and an iterative scheme based on the LATIN method is used for the global resolution. More specifically, the objective is to calculate a large number of design configurations. Each design configuration corresponds to a set of values of all the variable parameters (friction coefficients, prestress) which are introduced into the mechanical analysis. A full computation is needed for each set of parameters. Here we propose, as an alternative to carrying out these full computations, to use the capability of the LATIN method to re‐use the solution to a given problem (for one set of parameters) in order to solve similar problems (for the other sets of parameters). Copyright © 2003 John Wiley & Sons, Ltd.     

镍铬合金在酸性CuCl2溶液中反应机理

对铜在酸性CuCl_2溶液中蚀刻反应机理论述,利用氧化-还原电动势原理,详细论述了Ni80Cr20合金在酸性CuCl_2溶液中化学蚀刻反应机理,以及影响蚀刻速度的因素,并对溶液中金属离子的存在形式作了验证。     

600 A IGBT开关电路及其散热系统设计

采用IGBT开关电路，对大功率电阻带进行直流脉宽调制控制，实现了内燃机车大功率直流发电机负载实验中的负载大小的连续调节。为了避免在实验过程中IGBT器件的温度过高，采用独特的双管IGBT结构和双向强迫风冷的散热系统。实验表明该电路运行稳定、可靠。     

锰铜基高阻尼合金中锌量的测定──硫氰酸盐萃取分离络合滴定法

基于甲基异丁基甲酮于稀盐酸介质中定量地萃取Ｚｎ￣（２＋）与ＣＮＳ￣－形成的络阴离子。从而达到与共存的锰、镍、铝、铬的完全分离。在有氟化物、硫脲存在时Ｆｅ￣（３＋）、Ｃｎ￣（２＋）和Ａｇ￣＋也不被萃取。有机相中的锌于ＰＨ５．５“六胺”缓冲介质中返萃取回水相，用ＥＤＴＡ滴定。在文中给定的条件下锌的一次被萃取率可达９９％以上，成功地解决了锰铜基高阻尼合金中共存离子对锌量测定的干扰问题。     

THE STATISTICAL DISTRIBUTION OF EXTREME VALUES OF WAVE-CURRENT FORCES ACTING ON SLENDER CIRCULAR CYLINDER IN IRREGULAR WAVES

Based on model test,the statistical distribution of extreme values of wave-current in-line forces acting on vertical circular cylinder is analyzed in this paper.It is shownthat the results calculated by the simplified method,proposed by authors,agree well with the testdata;Weibull distribution is also adoptable in the region of high KC number, and the shapeparameter a and scale parameter β are related well with KC number respectively.     

一个新的力觉临场感系统模型

本文提出了一个新的力觉临场感系统模型，讨论了它的二端口网络结构，推导了相应的网络特性参数，分析了参数的含仪和测量方法。此外，对理想系统的参数也进行了分析，本文的研究为临场感技术的发展提供了基础。     

电力变压器动稳定破坏的分析和对策

对大型电力变压器绕组在变压器发生外部短路时所受的辐向力和轴向力进行了分析和计算，比较了国内外不同的计算方法和得出的不同结果。