肉牛饲料添加剂中铅含量的测定

利用火焰原子吸收光谱法(FAAS),测定了硫酸铜、硫酸锌、膨润土、米糠、氧化锌、菜渣、盐等7种肉牛饲料添加剂中铅(Pb)元素的含量.各添加剂的加标回收率在98%-108%之间,相对标准偏差(RSD)小于1.3%,具有良好的准确度和精确度.结果表明,试验中所测的硫酸铜、硫酸锌、氧化锌添加剂中铅含量严重超出国家标准.     

大型射电望远镜多馈源切换机构的设计

针对大型射电望远镜配备的馈源频段多、定位精度高和切换时间短的特点,结合工程实践,介绍了一种通过馈源旋转方式来实现多组馈源相互切换并用锁定销来精确定位的设计,通过该设计使每个馈源的相心均能准确到达天线的第二焦点位置并锁定。对整个机构的结构形式、功能进行了阐述,并对馈源的定位误差加以分析。同时,通过采用可倾覆使用的绕线机构,解决了天线在不同仰角条件下换馈机构旋转时带来的电缆缠绕问题。     

Integration of equipment planning and project scheduling

It is common to schedule project activities first, then the utilization of equipment and its operating crew is planned based on such schedule. Real world experiences indicate that activity scheduling can be heavily impacted by the resources needed. In particular, if a project requires highly specialized and expensive equipment type, then one needs to take into account the schedule and cost of such resources in developing the project schedule.     

Forward, backward, and symmetric solutions of discrete ARMA representations

The main objective of this paper is to determine a closed formula for the forward, backward, and symmetric solution of a general discrete-time Autoregressive Moving Average representation. The importance of this formula is that it is easily implemented in a computer algorithm and gives rise to the solution of analysis, synthesis, and design problems.     

洋浦电厂#11-13联合循环机组高压给水系统的变频改造

着重论述了海南洋浦电厂#11-13联合循环机组锅炉高压给水系统变频改造的原由，改造方法和运行对策，供兄弟单位参考和借鉴。     

移动多媒体一体化解决方案--FLO技术探讨

对美国高通公司推出的MeidaFLO进行了介绍.特别就其FLO空中接口技术与另一种主流技术DVB-H进行了比较.作为一种全新的无线多媒体传输技术,FLO创新的一体化解决方案、优化编码方式、分层调制与手机高度集成等特性使得其在实现多媒体传输方面拥有其它技术无法比拟的优越性.     

The asymptotic behaviour of weak solutions to the forward problem of electrical impedance tomography on unbounded three‐dimensional domains

The forward problem of electrical impedance tomography on unbounded domains can be studied by introducing appropriate function spaces for this setting. In this paper we derive the point‐wise asymptotic behaviour of weak solutions to this problem in the three‐dimensional case. Copyright © 2008 John Wiley & Sons, Ltd.     

Porosity, mechanical properties, residual stresses of supersonic plasma-sprayed Ni-based alloy coatings prepared at different powder feed rates

The aim of this paper was to investigate the effect of powder feed rate (PFR) on the microstructure and mechanical properties of the supersonic plasma-sprayed Ni-Cr-B-Si-C coatings. The microstructure, porosity and mechanical properties of the coatings and the residual stresses at the coating surfaces were experimentally determined. Results showed that the variations of porosity, elastic moduli and micro-hardness of the coatings followed Weibull distribution. From the statistical trend, the porosity of the coating increased with increasing PFR. However, the elastic modulus and the micro-hardness of the coating decreased and reached local minima and then increased with increasing PFR. Elastic modulus could be generally considered to be an increasing function of micro-hardness. The mean value of the elastic modulus of the coating calculated from Weibull plot was almost proportional to the square root of the mean value of the micro-hardness of the coating. Moreover, with increasing PFR, the residual stress at the coating surface, which was mainly governed by the elastic modulus of the coating, decreased to a local minimum and then increased.     

A 64 kbit/s Videophone codec with forward analysis and control

A new combination of coding methods for a 64 kbit/s transmission system for typical videophone situations is investigated. The codec structure is based on a standard hybrid discrete cosine transform (DCT) codec with temporal prediction. The picture is divided blockwise into changed and unchanged areas. One motion vector with subpel accuracy is computed and transmitted for each block of the changed area. For the forward analysis, the prediction error is calculated in the whole picture. Only the blocks with the highest prediction errors are updated by a DCT with a perception adaptive quantization. The number of DCT update blocks depends on the remaining bits after the transmission of the overhead information. The codec is controlled by a forward analysis of the prediction error and is not based on a buffer control. The spatial resolution of the source signal is reduced in two steps to prevent a codec overload caused by too much activity between two frames.     

正激式开关电源输出滤波特性的分析与仿真

文中对正激式开关电源的输出LCR组合滤波特性进行了深入分析,在比较分析以往一些相关研究的基础上,从时域和频域计算仿真了LCR组合滤波器的功能性能以及关键零点频率,以指导变换器环路补偿设计。