现场总线Profibus-DP主从站数据交换探讨

介绍了Profibus-DP网络的基本特性、结构、主从通信原理。然后结合奥地利贝加莱公司(B&R公司)现场总线模块对主从站Profibus-DP数据交换的实现方法作了详细地讨论。     

Growth and optical properties of Er,Yb:YAl3(BO3)4 crystal

Single crystal of erbium, ytterbium-codoped yttrium aluminum tetraborate Er,Yb:YAl₃(BO₃)₄(Er,Yb:YAB) has been grown by the flux method. The absorption spectrum in the visible and NIR regions of Er,Yb:YAl₃(BO₃)₄ crystal are measured at room temperature and fluorescence spectrum of Er,Yb:YAl₃(BO₃)₄ crystal are also measured at room temperature, excited by 976 nm laser. Not only the strong NIR emission peaks located at 1548 nm was observed, but also the visible up-conversion luminescence has been found. The specific heat of the Er/Yb:YAB crystal at room temperature is 0.81 J/g °C.     

Symmetry in electron diffractions from helical structures

In this work, we elucidate the regular rule of the symmetry in electron diffraction patterns from helical structures. It is affected by the value of the dominating Bessel function orders for the layer lines and relative orientation of the samples with respect to the electron beam. For Single-Walled Carbon nanotubes (SWCNTs), we use analytic analysis and computer simulations to demonstrate that the 2mm symmetry of the electron diffraction may break down not only from an achiral SWCNT, but also from a chiral SWCNT. Also, the simulation work for B-DNA is presented to corroborate the theoretical analysis.     

MC68HC908QY4单片机在炉温控制系统中的应用

本文介绍了MC68HC908QY4单片机控制的炉温控制系统，对系统的基本构成与工作原理进行了研究，并对数学模型与算法进行了分析，设计了软硬件．同时给出了部分硬件电路图与软件流程图。     

光谱分析的微机测试

介绍了一种用光电倍增管将光信号转换为电信号,再将此信号放大经模数转换后输入到微机、打印机等设备的一套光谱分析的微机处理方法,此种方法与传统的干板照像法进行比较,在进行光谱分析时省时、省力、误差小,实现了光谱分析的微机化。     

林区环境因素与CORS测量精度的相关性分析

在林区环境下的碎部测量中存在一定的障碍物对CORS信号进行干扰,影响CORS信号的站间传播。为研究林区环境因素与CORS测量精度之间的关系,通过获取林区优势树种的叶面积指数(LAI)和CORS测量精度等要素,利用SPSS软件分析其相关性。结果表明：不同优势树种的LAI值与CORS测量精度秩相关系数r_s>0.8,在p<0.01下呈强相关性,树冠投影面积与CORS测量精度的秩相关系数r_s>0.5,在p<0.01下呈现中等相关,而树冠高度和地形与CORS测量精度未得出相关性。     

Recovery of indium and lead from lead bullion

Lead and indium were recovered by electrolysis and nonequilibrium solvent extraction process from lead bullion.The effects of current density,electrolytic period and circle amnant of electrolyte on the electrochemical dissolution of lead and indium were investigated.The effects of extraction phase ratio and mixing time on solvent extraction of indium and striping phase ratio and stripping stage on the loaded organic phase stripping were also investigated.The experimental results indicate that under optimum conditions,the purity of lead deposited on cathode is 98.5% and the deposit rate of lead is 99.9%,the dissolution rate of indium is 94.28%,the extraction rate of indium is 98.69%,the stripping rate of indium is almost 100%,and the impurity elements,such as Zn,Fe and Sn can be removed.     

基于软件无线电通信平台的高效信道化MSK系统

为了解决软件无线电平台中的数字上下变频技术,包括频谱的搬移和抽样率的转换,克服现有专用器件在实现这些功能中的不是,在分析高效宽频带变频系统的基础上把变频部分与MSK调制方式灵活地结合在一起,有利于在实际中进一步推广到各类调制方式中,从而实现软件无线电的高效数字变频调制解调．