An Efficient Solid-State Synthesis of N-Aryl-2-phenyldiazenecarboxamides

The subject of organic solid-state synthesis is a fascinating one. It has many advantages such as high efficiency and selectivity, easy separation and purification, mild reaction conditions, and environmental acceptability1. In recent years, this method has been widely used in a variety of organic reactions including substitution2, condensation3, oxidation-reduction4, rearrangement5 and elimination6. However, the solid state reaction using K3Fe(CN)6/KOH to oxidize substituted semicarbazides…     

Effects of Cr doping on the electrochemical performance of Li3V2(PO4)3 cathode material for lithium ion batteries

A series of Cr-doped Li₃V_2 − x Cr _x (PO₄)₃ (x = 0, 0.1, 0.25, and 0.5) samples are prepared by a sol–gel method. The effects of Cr doping on the physical and chemical characteristics of Li₃V₂(PO₄)₃ are investigated. Compared with the XRD pattern of the undoped sample, the XRD patterns of the Cr-doped samples have no extra reflections, which indicates that Cr enters the structure of Li₃V₂(PO₄)₃. As indicated by the charge–discharge measurements, the Cr-doped Li₃V_2 − x Cr _x (PO₄)₃ (x = 0.1, 0.25, and 0.5) samples exhibit lower initial capacities than the undoped sample at the 0.2 C rate. However, both the discharge capacity and cycling performance at high rates (e.g., 1 and 2 C) are enhanced with proper amount of Cr doping (x = 0.1). The highest discharge capacity and capacity retention at the rates of 1 and 2 C are obtained for Li₃V_1.9Cr_0.1(PO₄)₃. The improvement of the electrochemical performance can be attributed to the higher crystal stability and smaller particle size induced by Cr doping.

     

Early cure behavior of a liquid dicyanate ester resin

The early cure behavior of 4,4‐dicyanato 1,1‐diphenolethane resin with and without incorporating Cr(acac)₃, Co(acac)₃, and Cu(acac)₂, respectively, as catalysts was investigated by gel permeation chromatography. The curing intermediates were separated by the column elution method and characterized by Fourier transform infrared, ¹H, and ³C NMR spectroscopies. The results indicated that the formed dimer in the early cure stage is a straight chain containing a primary amino group. The formed triazine ring in the trimer has a strong catalytic effect on the remaining cyanate groups so that the reactivity of the trimers was significantly increased. The reactivities of the curing intermediates decreased with molecular size until 7‐mer was reached. The initial monomer consumption is described by second‐order‐rate kinetics. In the presence of metal acetylacetonates, the curing reactions may be accelerated, but they did not change the reaction path and preceding sequence of reactivities. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3085–3092, 2001     

STATE VERIFICATION FOR SYNCHRONOUS CIRCUITS

This paper presents the techniques of implicit traversing and state verification for sequential finite state machines(FSMs) based of on the state collapsing of state transition graph(STG). The problems of state designing are described. In order to achieve high state enumeration coverage, heuristic knowledge is proposed.     

Design of Modified Short Backfire Antennas for Millimeter-Waves Wireless LAN Applications

A set of novel modified short backfire antennas are proposed and designed for the application of millimeter-wave wireless LAN systems, by using the FDTD method. By changing the geometrical parameters and feeding structure, the short backfire antennas can generate different kinds of radiation patterns, including narrow pattern, fan-like pattern and conical patterns. Antenna parameters such as reflection bandwidth, input impedance, and far field radiation pattern are presented for each kind of antennas. The proposed different kinds of antennas are suitable for various purposes of wireless LAN applications.     

1.55μm多量子阱行波光放大器

介绍了1.55μm波段的多量子阱(MQW)行波式半导体激光放大器的制备及其特性的测量.其测量结果.在注入脉冲电流条件下.内增益为20dB.饱和输出峰值功率为40mW.     

Generalized multiplication-free arithmetic codes

Arithmetic coding is a highly efficient lossless source coding technique. Multiplication-free arithmetic coding algorithms provide an excellent tradeoff between operation complexity and coding performance. A whole family of multiplication-free arithmetic codes, which achieve the best coding efficiency and can be used for arbitrary size of alphabets, is derived. The complete tradeoff between the complexity of operations and compression performance of all the algorithms is presented     

生物组织电导率CMIT平面螺旋激励线圈的分析

计算了平面矩形螺旋线圈的电感值,结果与近似公式计算得出的电感值吻合。另外,通过理论计算发现,矩形平面螺旋线圈产生的磁场具有聚焦的特性,并计算和讨论了分层生物组织的电导率对电感的影响,认为用矩形平面螺旋线圈来做生物组织非接触的电导率成像的激励线圈是可行的。     

微型计算机在瞬态电波波形测试中的应用

介绍了微型计算机在对瞬态电波波形进行自动采集，存贮，处理及显示中的应用，且提出了一种典型的测试系统的总体方案及其硬，软件设计，该系统具有良好的人机界面，操作方便灵活，测试的准确度，可靠性较高。     

用于网络单元时钟的压控石英振荡器

介绍了１５５．５２Ｍｂｉｔ／ｓ、６２２．０８Ｍｂｉｔ／ｓ、２４８８．３２Ｍｂｉｔ／ｓ、１０Ｇｂｉｔ／ｓＳＤＨ系统上的时钟频率源的基本原理，针对ＳＤ我同步对网络单元时钟要求的３８．８８ＭＨｚ压控振荡顺频率源进行了设计，当环境温度在０℃到７０℃范围内变化时，压控振荡器的频率漂移优于±１×１０＾－６，瞬时频率稳定定优于１．２５×１０＾－９。