Preparation and electrochemical performances of graphite oxide/polypyrrole composites

Graphite oxide/polypyrrole composites (GPys) were prepared by in situ polymerization and reduced by NaBH₄ to prepare reduced graphite oxide/polypyrrole composites (R-GPys). On the basis of the morphological and structural characterization of the composites by Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests, the electrochemical performances of the composites were investigated by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance techniques. The experimental results showed that the specific capacitances of the composites before and after reduction (197 and 180 F/g) were highly improved compared with that of pristine graphite oxide (11 F/g) and polypyrrole (112 F/g), respectively. The capacitance retention of about 73% for R-GPys compared with 12% for PPy and 47% for GPys after 1200 cycles indicated the high cycle stability of the R-GPys and its potential as an electrode material for supercapacitor applications.     

Schiff碱-双（呋喃甲醛）缩联苯胺的合成与光谱研究

Schiff碱在材料、催化剂和分析化学方面等的研究都有了很大进展,也越来越受到重视。文章以呋喃甲醛和联苯胺为起始原料,在无水甲醇的溶剂中合成了一种新的Schiff碱,收率为85.0%。反应的最佳条件是呋喃甲醛与联苯胺的比例为3∶1,反应时间为1h,反应温度为30℃。这种新的Schiff碱结构且通过了IR和UV光谱测定。     

Tests on inclined,tapered and STS concrete-filled steel tubular (CFST) stub columns

This paper is an attempt to study the behaviour of the inclined, tapered and straight-tapered-straight (STS) concrete-filled steel tubular (CFST) stub columns. A total of 34 specimens were tested. The main parameters were the column type (inclined, tapered and STS), inclined or tapered angle (from 0°to 9°) and the cross-sectional type (circular and square). Comparisons with predicted cross-sectional strengths were made using the existing codes: AIJ-2008, AISC-2005, BS5400-2005, DBJ-13-51-2003 and EC4-2004.     

一种基于思维进化算法的变压器故障诊断方法

本文提出了一种基于思维进化算法的变压器故障诊断方法。该方法以变压器油中特征气体的含量作为输入参数,根据趋同和异化的原理进行搜素,从而得到输入和输出变量之间的对应关系。实例分析计算表明,采用该方法对变压器进行故障诊断是有效的。     

基于TCP／IP的网关转串口通讯

以8051系列的单片机和RTL8019AS网络接口芯片等构建网络接入系统,在RTL8019AS芯片提供的应用基础上完成TCP／IP协议,经过8051单片机实现数据的RJ-45与串口通讯。该设计为传统串口设备通过标准TCP／IP协议接入Internet提供了一种低成本解决方案。     

Assessment of intestinal amino acid availability in cattle by use of the precision-fed cecectomized rooster assay

The digestibilities of amino acids in duodenal digesta of steers were measured using a precision-fed cecectomized rooster assay. Freeze-dried duodenal digesta from steers fed five different diets were utilized. Amino acids present in digesta of steers fed diets supplemented with corn gluten meal were more digestible than those from digesta of steers fed diets supplemented with soybean meal, blood meal, fish meal, or no true protein source. Measurements of amino acid digestibility in the cecectomized rooster were similar to those obtained previously when measured with reference to chromic oxide in steers fitted with duodenal and ileal cannulae, suggesting that the precision-fed cecectomized rooster assay is an appropriate technique for estimating small intestinal digestibility of amino acids in cattle.     

用于MEMS器件的高性能运算放大器的IC设计与测试

根据特定电容式微传感器后续处理电路的高性能要求。设计一个运算放大器芯片，设计中采用了美国MOSIS公司提供的n阱0.35μm cmos工艺的SPICEBSIM3mos管模型。手算估计芯片的参数，然后采用了两种能系统反映芯片特性的测量电路对设计进行了性能测量。并根据测试结果对设计微出相应调整，从最终测试结果来看。设计的运算放大器具有很好的静态和动态性能。     

基于SI4432的无线通信系统设计与实现

短距离无线通信的应用已经越来越广泛,如何在保证通信质量和安全的前提下,降低系统能耗,减少硬件成本成为制约其发展的关键问题。文中采用ISM频段SI4432射频芯片和ATmega16控制单片机设计了一种新的无线通信系统,完成了系统硬件的搭建,无线通信程序及上位机界面的设计。该系统可在休眠与唤醒两种模式下工作,降低了系统整体能耗,实现了低功耗、小体积、高灵敏度的无线数据传输,可应用于工业控制、智能建筑、远程监控等多个领域,具有广阔的应用前景。     

Surface Wettability of Nanostructured Zinc Oxide Films

Zinc oxide (ZnO) nanograin and nanorod films were prepared by magnetron sputter deposition and an aqueous solution growth method. Their surface wettability was studied in relation to their surface morphologies. While the surfaces of both films were hydrophobic, the nanorod films exhibited higher surface hydrophobicity. A superhydrophobic surface was obtained on a ZnO nanorod film with a water contact angle of 151 deg. Results have shown that their surface wettability was influenced by the morphology of ZnO nanostructures, including the grain size, the length, and density of nanorods. Both types of ZnO films showed switchable wettability under ultraviolet irradiation and dark storage.     

A Millimeter-Wave Quasi-Optical Circuit for Compact Triple-Band Receiving System

A novel receiver optical system designed for Korean VLBI Network (KVN) has been used for conducting simultaneous millimeter-wave very long baseline interferometry (VLBI) observations at frequencies of 22, 43, 86, and 129 GHz. This multi-frequency band receiver system has been effective in compensation of atmospheric phase fluctuation by unique phase referencing technique in mm-VLBI observations. However, because the original optics system incorporated individual cryogenic receivers in separate cryostats, a rather bulky optical bench of size about 2600 mm x 2300 mm x 60 mm was required. To circumvent difficulties in installation and beam alignment, an integrated quasi-optical circuit incorporating a more compact triple-band receiver in single cryostat is proposed in this paper. The recommended frequency bands of the improved triple-band receiver are K(18–26 GHz) band, Q(35–50 GHz) band, and W(85–115 GHz) band. A frequency-independent quasi-optical circuit for triple band is adopted to obtain constant aperture efficiency as a function of the observed frequencies. The simulation results show that total aperture efficiency of each recommended frequency band is maintained almost constant within 1%. We present the design details of the compact wideband quasi-optical circuit and the triple-band receiver optimized for simultaneous multi-frequency observations.