A simple method for rapid calibration of faraday and ion‐counting detectors on movable multicollector mass spectrometers

Methods are presented for rapid determination of relative efficiencies of Faraday cups in a multicollector array with movable cups and of Daly or electron multiplier detector dead time and gain values. The Faraday calibration approach is based on measuring the same isotopic ratio in two sequences with different collector configurations having one collector in common. Changes in thermal fractionation during the two measurement sequences are monitored using the same two collectors. Since the relative efficiencies are determined by measuring the same ratio in different cups corrected for time‐dependent changes in fractionation, it is unnecessary to use a standard of known composition and calculations are simple, not requiring the solution of multiple equations. Determination of dead time and gain values for a Daly detector are shown based on multidynamic measurements of masses 207, 206, and 208 from Pb standard SRM982 in two sequences consisting of L1‐Daly‐H1 and Daly‐H1‐H2. This provides two equations that can be solved for Daly dead time and gain. This method uses static measurements and is therefore insensitive to signal instability. It also does not require use of a standard of known isotopic composition. The potential of using known cup efficiencies to help determine absolute isotopic abundances is discussed.     

MC2环

证明了关于左MC2环的几个结果：1)R是左MC2环当且仅当S1∩J＝S1∩Z1；2)R是左MC2环当且仅当全矩阵环Mn(R)是左MC2环；3)左MC2环是morita不变的；4)设R是有限群G—分次环，|G|^-1∈R，则R是左MC2环当且仅当R#G^*是左MC2环。     

基于Motorola 68VZ328开发系统的研究

该开发系统是一种硬件处理能力相当于386的MC68VZ328嵌入式CPU和嵌入式Linux操作系统相结合的完全的片上系统,包括一片8MB的SDRAM外部存储器芯片,一片2MB的Flash可进行在线读写;LCD液晶显示接口,可外接640×512、320×240、240×160点阵液晶;两个串口与外部相连,可与通用串口相接;由十几个键组成的键盘和一个自由编程发音的蜂鸣器;一个具有红外传输功能的接口。在某种意义上说,这是一个计算机系统的微缩,它通过板上的串口与PC机相连,在计算机上运行SDS编译仿真软件,实现该系统的在线调试。     

电话机免提通话集成电路的特点及常见故障的分析

在比较电话机免提通话集成电路特点的同时,分析了MC34018集成电路的内部工作原理及其常见故障,并优化了与集成块TEA1062共同组成的免提电路的工作流程.     

Dielectric relaxation studies of methyl cellulose with phenol derivatives in non-polar solvents using time domain reflectometry

Dielectric relaxation measurements of methyl cellulose with substituted phenols p-cresol, m-cresol and o-cresol mixture in different non-polar solvents CCl₄, benzene and 1,4-dioxan for different concentrations over the frequency range of 10 MHz–20 GHz at 303 K have been carried out using Time Domain Reflectometry (TDR). Dielectric parameters such as static permittivity (ε₀) and relaxation time (τ) were determined and discussed to yield information on the molecular structure and dynamics of the mixture. The dielectric constant and relaxation time were found to be high for methyl cellulose with p-cresol in CCl₄ compared with the other mixtures.     

Explicit proton transfer in classical molecular dynamics simulations

We present Hydrogen Dynamics (HYDYN), a method that allows explicit proton transfer in classical force field molecular dynamics simulations at thermodynamic equilibrium. HYDYN reproduces the characteristic properties of the excess proton in water, from the special pair dance, to the continuous fluctuation between the limiting Eigen and Zundel complexes, and the water reorientation beyond the first solvation layer. Advantages of HYDYN with respect to existing methods are computational efficiency, microscopic reversibility, and easy parameterization for any force field. © 2014 Wiley Periodicals, Inc.     

MC1496P 集成电路的应用研究

系统的介绍了ＭＣ１４９６Ｐ的模拟乘法器原理及特性，在实现混频方面进行了较细致的研究，并通过实验提出了有关工作参数。     

圆插补加工大型机壳大孔的研究

介绍了一种以铣代镗,利用圆插补功能加工大型机壳较大内孔的方法.     

基于MC13213的无线网络音频设计

介绍了基于MC13213和AMBE2000芯片设计一套语音压缩编码系统,并对系统设计中遇到的问题进行了探讨。