A Calculation Approach to Elastic Constants of Crystallines at High Pressure and Finite Temperature

Elastic constants of Na and Li metals are calculated successfully for temperatures up to 350K and pressures up to 30GPa using a scheme without involving any adjustable parameter.Elastic constants are assumed to depend only on an effective pair potential that is only determined by the average interatomic distance.Temperature has an effect on elastic constants by way of charging the equilibrium.The elastic constants can be obtained by fitting the relationship between total energy and strain tensor using the new set of lattice parameters obtained by calculating displacement of atoms at the finite temperature and at a fixed pressure.The relationship between the effective pair potential and the interatiomic distance is fitted by using a series of data of cohesive energy corresponding to lattice parameters.     

BEPC中电子云导致的束团横向尺寸增长研究

多束团正电子储存环中可能发生电子云不稳定性. 由于电子云导致的束团横向尺寸增长已经成为提高对撞机对撞亮度的主要限制因素之一. 介绍了在BEPC储存环中, 利用条纹相机直接测量由于电子云导致的束团横向尺寸增长结果, 并与模拟计算进行了比较.     

温度测量装置的控制方法

在现代工业生产中，温度测量装置的使用十分广泛。在许多场合如热处理、热加工、温度实验等都需要严格的控温条件，才能保证产品的质量。因此，对使用中的温度测量（或控制）装置必须进行控制，确保其可靠性。温度测量装置属于计量器具，应遵循我国《计量法》的规定定期周检，但是在实际工作中，情况往往比较复杂，需区别对待和处理。温度测量装置有许多种类，具体的控制方法大体有两类：1.送实验室周检；2.现场校准。周检法用于能运送到实验室的有适用检定规程的温度测量装置，如常用的XCT型动圈式温度指示调节仪（适用国家计量检定规程J…     

Growth of NaBi（WO4）2 Dendrite and Mechanism

The solid-liquid interface motion of NaBi（WO4）2 （NBWO） melt crystal growth is observed in an in situ system, in which the whole processes of interface transition from fiat interface and cellular to dendrite are visualized. The spacing of the dendrite under smaller temperature gradient turns out to be larger than that under larger temperature gradient, which is found to be sensitive to the temperature distribution. The mechanism of dendrite growth of NBWO is studied based on the model of the growth units of anion coordination polyhedra. The { 001} face has two apex links, so it shows higher stability and has high growth rate and forms the arm of dendrite, whereas the {010} face has only one apex link, and thus shows relative slower growth rate and firstly forms the branches.     

利用精密仪表放大器实现负压电流检测

监测正电源的电流时，通常使用高边检流放大器。然而，对于ISDN、电信电源，通常需要一个工作在负电源的检流放大器。本文介绍了一种采用MAX4460单电源仪表放大器设计负压检流放大器的方法。     

新品推荐——软件工具类

BPM Helix自动烧录系统，KIC Explorer热温度曲线系统，LeadTracer—RoHS XRF系统，SMT3000LD自动去助焊剂系统     

二元示数计算

(二)负数开平方法 原理:当某一根置大,就将出现估负根的计算。     

热处理条件对双粉工艺中Bi—2212粉末的相组成影响

实验研究了Bi-2212粉末在空气，8％O2和纯O2种处理的相组成特征，指出通过改变热处理温度和气氛可控制前驱粉中对2223成相影响较大的(Bi，Pb)-2212相，Ca2PbO4相，2201相和14：24AEC等相。