Anisotropy of the thermopower in higher silicide of transitions metals

A new technique for measuring the thermopower anisotropy using polycrystals on the basis of repeated measurements of an array of randomly oriented microcrystals and statistical analysis of the data obtained is proposed. The thermopower anisotropy of a series of higher silicides of transition metals (β-FeSi₂, doped MnSi_1.75, ReSi_1.75, and CrSi₂) is measured using polycrystals. It is found that, in β-FeSi₂ crystals, a very high thermopower anisotropy can be observed; in ReSi_1.75 crystals, the thermopower can have different signs; and, in CrSi₂, the absolute value of the thermopower depends heavily on the heat-treatment mode. The temperature dependences of the electrical conductivity and thermopower of CrSi₂ needles are measured. The thermopower anisotropy in CrSi₂ needles, as in bulk single crystals, is retained in a wide temperature range.     

The possibility of using acid-alkali solutions to precipitate rubidium in the form of its hexachlorotelluride

The possibility of isolating rubidium from acid-alcohol solutions in the form of its complex halogenide with tellurium is considered. The solubility of potassium, sodium, and rubidium in solutions of the mixture of hydrochloric acid and ethanol with their various volume ratios at t = 25°C is investigated. The possibility of increasing the degree of isolation of Rb in the form of its hexachlorotellurite (Rb₂TeCl₆) upon going from acidic to acid-alcohol solutions is shown.     

Calculation of Thermobimetallic Releases of Circuit Breakers with Indirect Heating for Currents from 63 to 250 A

Thermal releases based on thermobimetallic elements (TBEs) form the current-dependent part of the protective characteristic of a circuit breaker. The design of a mechanism of free releasing and the characteristics of a thermobimetallic element are analyzed. The operating condition for the thermal release is formulated, which is based on comparison of the mechanical characteristics of an actuator and thermomechanical characteristic of TBEs. Experimental studies of thermobimetallic releases, which are analogues of the breakers to be developed, were carried out. Taking into account the results of these experiments, a design procedure of thermobimetallic release was developed, which is applicable for all types of TBE heating (direct, indirect, combined). The procedure makes it possible to determine the geometrical dimensions of a TBE and the methods of its heating, as well as the operating temperature of release depending on the rated current of the breaker. It has been noted that, to provide the possibility of operating current adjusting, as well as for reliable operation of circuit breakers under vibration and shock conditions, it is necessary to provide for the free running of TBE during design. Comparison of design and experimental data showed the accuracy of procedure, which is acceptable for practical calculations.     

The technology and electrical characteristics of ceramics based on hydroxylapatite

In this paper, we have examined the synthesis and structure of hydroxylapatite and methods for obtaining a dense and porous hydroxylapatite, as well as methods for producing a dense and porous HA-based ceramics. The temperature dependence of conductivity and dielectric loss tangent of hydroxylapatite were investigated.     

Design of a Screw Powder Compactor

A method is suggested for optimizing the design and operating parameters of screw powder compactors.     

加速度地震检波器简谐振子有限元分析

介绍简谐振子的工作原理。利用ANSYS软件,采用有限元法创建了简谐振子质量块的实体模型,选择单晶硅作为简谐振子中质量块的材料;设置了模型的材料属性,采用智能分网的方式对模型划分网格,并对质量块模型施加沿x轴水平方向载荷,进行三维的静力分析和模态分析。静力分析得到实体模型的总位移是0.236×10-19μm;模态分析时只对前四阶模型进行了分析,根据其振型图及其总位移的应力云图,得到实体模型的二十阶振动模态的频率是78 001Hz,二十阶的总位移是0.122×10-6μm。     

双极型电压比较器的强电磁脉冲效应

基于大电流注入法(BCI),利用瞬态脉冲产生器模拟强电磁脉冲在双极型电压比较器中产生的耦合电流,观测到输出信号在注入瞬态大电流后的波形变化,包括占空比变化及脉冲衍生等。从基本电路原理方面分析了实验现象的产生机理,以及注入电流幅值、电路偏置等因素对双极型电压比较器强电磁脉冲效应的影响。