沪市时变贝塔及财务影响因素分析

为了验证CAPM模型中贝塔系数的稳定性以及系统风险的影响因素,引入ENGLE提出的DCC—GARCH模型,利用上市公司普通股月度收益率数据得到随时间变化的贝塔值,证明了用来衡量资产风险的贝塔系数具有不稳定性。将时变贝塔与选取的财务指标进行多元线性回归,得出如下结论：对由时变贝塔表示的系统风险有显著正向影响的财务指标包括经营杠杆、资本积累率、企业规模,以及应收账款周转率;有显著负向影响的指标包括流动比率和现金流量比率;无显著影响的指标为财务杠杆和净资产收益率。与已有研究不同的是,时变贝塔的引入克服了研究结论只对行业研究具有一定参考意义而对个别公司的指导意义不大的缺点,可为利益相关者在公司层面衡量系统风险提供指导。     

Advanced impulsive‐driving technique for Super‐PVA panel

Abstract— Super‐PVA (S‐PVA) technology developed by Samsung has demonstrated excellent viewing‐angle performance. However, S‐PVA panels can place extra demands on charging time due to the time‐multiplexed driving scheme required to separately address two subpixels. Specifically, a 2G‐1D pixel structure theoretically requires subpixel charging in one‐half of the time available for a conventional panel. In this paper, a new LCD driving scheme, super impulsive technology (SIT), is proposed to improve motion‐blur reduction by driving an S‐PVA LCD panel at 120 Hz. The proposed scheme allows a 120‐Hz 2G‐1D panel to be driven with an adequate charging‐time margin while providing an impulsive driving effect for motion‐blur reduction. Considering that the cost of a 2G‐1D S‐PVA panel is comparable to that of a conventional 60‐Hz panel, this method achieves good performance at a reasonable price. The detailed algorithm and implementation method are explored and the performance improvements are verified.     

Copolymer of acrylonitrile/acrylic acid solid surface film dendrigrafted with citric acid

BACKGROUND: The aim of the present work was to improve the properties of acrylic polymer, which is a major fibre‐forming polymer. Acrylonitrile/acrylic acid copolymer, P(AN/AA), was chosen for this purpose and it was intended to study the condition for the formation of hydroxyl groups through the formation of hyperbranched polymers. RESULTS: The synthesis of a dendritic polymer of citric acid (CA) in the solid phase on a P(AN/AA) core is described. The product was analysed using the elemental analysis technique and ¹H NMR. Dendritic molecules were grown by a reaction between the carboxylic acid of acrylic acid and hydroxyl group of CA activated by dicyclohexylcarbodiimide. Products were analysed using Fourier transform infrared and NMR spectroscopy. CONCLUSION: The formation of CA dendrigraft on P(AN/AA) films in a heterogeneous system is possible. The percentage conversion of the copolymer reaction with CA was calculated based on the NMR results. The percentage conversion showed a gradual reduction with an increase in step numbers. The contact angle of water on the films was affected by the percentage conversion of the reactions. A calculation scheme is presented to show that the low degree of conversion leads to an increase in hydrophobic groups. Copyright © 2008 Society of Chemical Industry     

1—群的链条件

本文主要讨论1-群的各种凸1-子群的链条件,同时还讨论了满足链条件的各种凸1-子群的相互关系以及这些凸1-子群自身的特性.     

New era for TFT‐LCD size and viewing‐angle performance

Abstract— Samsung has announced the development of a full‐high‐definition (1920 × 1080) 82‐in. TFT‐LCD panel using Super‐PVA (S‐PVA) technology, the world's largest TFT‐LCD. In addition to the size breakthrough, this product achieves 600 nits of brightness, a contrast ratio of over 1200:1, an angle of view of 180°, a color gamut of 92%, and an 8‐msec response time. Several key enabling technologies were developed to achieve these specifications, including two‐transistor direct‐driven independently controlled S‐PVA subpixels, non‐even‐area‐ratio subpixels for optimal off‐axis gamma, gate overlap driving for larger driving margin, new CCFL technology for higher color gamut, and advanced fabrication techniques including the use of Samsung's new Gen 7 line. Many of these technologies will be applied to other products within Samsung's LCD‐TV product line. Samsung's broader development efforts toward the overall LCD‐TV market, including production status of the Gen 7 facility, will be updated.     

一种新型大电流分流器检测仪原理和特点

提出了一种新型直流大电流分流器检测仪的设计方案,通过电流比较仪和直流电位差计巧妙结合,设计出了一种测量范围宽,制造成本较低的分流器检测仪,该方案对提高检定分流器准确度和降低制造成本有重要的现实意义.     

天津电力通信网NEC网管系统优化方案

随着电力通信网日益庞大和复杂,实现一套高效可靠的网管系统尤显重要.文章结合天津电力通信网中的NEC设备网管情况,制定网管系统优化方案.利用综合业务数据网平台并使用MPLS VPN技术,将网络划分为不同的子网,减少路由表条目,解决了部分网元因路由表溢出而发生脱管的问题.通过对网络结构的调整,增加主调、备调网管间三层VPN通道,改进了备调网管的备用功能.目前已经验证方案的有效性,为其他网管系统的优化提供了新的思路.     

DCC缩合酯化法合成水杨酸低聚壳聚糖酯及抑菌性研究

在保留C2-NH2抗茵活性基团的基础上,以DCC为脱水剂制备了具有双抑菌活性中心的水杨酸低聚壳聚糖酯(SEC),并对其抑菌活性进行了研究.结果显示,SEC最佳合成反应条件为:n(低聚壳聚糖):n(水杨酸):n(DCC)=1:4:4,冰浴条件下酯化反应48 h,产物酯化度接近73%.该条件下制备的壳聚糖衍生物对各种常见菌...     

优化丙烯生成的催化裂解催化剂的特性及其性能评价

 针对由顺序和平行反应组成的催化裂解反应网络,在分子炼油水平上进行研究,优化丙烯生成的催化反应动力学（Optimized catalysis kinetics,简称 OCK）,为强化基质大孔的重油转化能力,提高活性中心可利用性和可接近性,深化裂解反应,优化催化剂成型效果,开发了 OCK 催化剂制备技术,研制出了新一代催化裂解（DCC）工艺专用催化剂 DMMC-1。与目前综合性能最好的 DCC 催化剂相比,DMMC-1具有大孔结构、高比表面积、高平衡活性等特点。实验室评价结果表明,采用 DMMC-1催化剂,使丙烯收率增加2.25百分点,丙烯选择性提高13.8%,汽油质量变好,重油裂化能力提高,焦炭选择性得到改善。     

Modifications of carbon for polymer composites and nanocomposites

The various forms of carbon used in composite preparation include mainly carbon-black, carbon nanotubes and nanofibers, graphite and fullerenes. This review presents a detailed literature survey on the various modifications of the carbon nanostructures for nanocomposite preparation focusing upon the works published in the last decade. The modifications of each form of carbon are considered, with a compilation of structure-property relationships of carbon-based polymer nanocomposites. Modifications in both bulk and surface modifications have been reviewed, with comparison of their mechanical, thermal, electrical and barrier properties. A synopsis of the applications of these advanced materials is presented, pointing out gaps to motivate potential research in this field.