等级化信息安全保障体系设计思想

一、前言等级化信息安全是我国信息安全的一项基本策略,实施等级化信息安全保护是实现“重点资产重点保护”,同时又“适度安全”的有效手段,其最终目的是实现安全和成本的综合平衡,达到提高信息安全建设质量,提高安全的综合性价比这一根本目的。正如任何一种新方法的提出必然面临如何有效实施的问题一样,自从2003年中办发27号文件以来,尽管国家相关部门已经陆续出台了等级化信息安全保障的相关文件、意见和实施指南,等级化在信息安全界的实施却比较困难。这是由于在实践中发现,目前出台的相关指南对于复杂的应用系统和网络系统在其操作性上…     

A high-efficiency CMOS +22-dBm linear power amplifier

Modern wireless communication systems require power amplifiers with high efficiency and high linearity. CMOS is the technology of choice for complete systems on a chip due to its lower costs and high integration levels. However, it has always been difficult to integrate high-efficiency power amplifiers in CMOS. In this paper, we present a new class of operation (parallel A&B) for power amplifiers that improves both their dynamic range and power efficiency. A prototype design of the new amplifier was fabricated in a 0.18-/spl mu/m CMOS technology. Measurement results show a PAE that is over 44% and the measured output power is +22 dBm. In comparison to a normal class A amplifier, this new design increases the 1-dB compression point (P1dB) by over 3 dB and reduces dc power consumption by over 50% within the linear operating range.     

一种转移脉冲宽度可调的CCD驱动电路

本文以TCD132D线阵CCD为例,介绍了一种用循环计数器和拨码开关共同作用改变CCD转移脉冲的CCD驱动电路。该电路结构简单,工作可靠,调整方便。     

BC—1型白平衡仪的原理与实践

ＢＣ－１型白平衡仪是一种光电积分式测色仪器，它通过颜色传感器获取屏幕的红，绿，蓝三条色信号，与预先存储在仪器中的标准信号值相比较通过ＬＥＤ条形显示器显示两者之偏差，用以直接指导彩电生产线的白平衡调整，仪器采用Ｉｎｔｅｌ１８０９８单片微机为系统核心，内藏信号发生器，仪器可任选红，绿，蓝作为基准色，具有基色亮度自动调整功能，该仪器的定标方法简单，快捷，可方便地存储８套基准白场标准数据，该仪器已可靠在应     

Finite-element analysis of hyperelastic thin shells with large strains

The objective of this contribution is the development of theoretical and numerical models applicable to large strain analysis of hyperelastic shells confining particular attention to incompressible materials. The theoretical model is developed on the basis of a quadratic displacement approximation in thickness coordinate by neglecting transverse shear strains. In the case of incompressible materials this leads to a three-parametric theory governed solely by mid-surface displacements. The material incompressiblity is expressed by two equivalent equation sets considered at the element level as subsidiary conditions. For the simulation of nonlinear material behaviour the Mooney-Rivlin model is adopted including neo-Hookean materials as a special case. After transformation of nonlinear relations into incremental formulation doubly curved triangular and quadrilateral elements are developed via the displacement method. Finally, examples are given to demonstrate the ability of these models in dealing with large strain as well as finite rotation shell problems.The present study is supported by a research grant of the German National Science Foundation (DFG) under Ba 969/3-1.dedicated to Prof. Dr. Dr. Erwin Stein for his 65th birthday anniversary     

(+)-CC-1065 as a structural probe of Mu transposase-induced bending of DNA: overcoming limitations of hydroxyl-radical footprinting

Phage Mu transposase (A-protein) is primarily responsible for transposition of the Mu genome. The protein binds to six att sites, three at each end of Mu DNA. At most att sites interaction of a protein monomer with DNA is seen to occur over three minor and two consecutive major grooves and to result in bending up to about 90 degrees. To probe the directionality and locus of these A-protein-induced bends, we have used the antitumor antibiotic (+)-CC-1065 as a structural probe. As a consequence of binding within the minor groove, (+)-CC-1065 is able to alkylate N3 of adenine in a sequence selective manner. This selectivity is partially determined by conformational flexibility of the DNA sequence, and the covalent adduct has a bent DNA structure in which narrowing of the minor groove has occurred. Using this drug in experiments in which either gel retardation or DNA strand breakage are used to monitor the stability of the A-protein--DNA complex or the (+)-CC-1065 alkylation sites on DNA (att site L3), we have demonstrated that of the three minor grooves implicated in the interaction with A-protein, the peripheral two are 'open' or accessible to drug bonding following protein binding. These drug-bonding sites very likely represent binding at at least two A-protein-induced bending sites. Significantly, the locus of bending at these sites is spaced approximately two helical turns apart, and the bending is proposed to occur by narrowing of the minor groove of DNA. The intervening minor groove between these two peripheral sites is protected from (+)-CC-1065 alkylation. The results are discussed in reference to a proposed model for overall DNA bending in the A-protein att L3 site complex. This study illustrates the utility of (+)-CC-1065 as a probe for protein-induced bending of DNA, as well as for interactions of minor groove DNA bending proteins with DNA which may be masked in hydroxyl radical footprinting experiments.     

PbO－Bi_2O_3－B_2O_3－SiO_2系重金属氧化物玻璃的结构与光学性

通过密度、可见光光谱、红外吸收光谱、Ｃｏ－６０辐照损伤试验及荧光光谱的测试，研究了ＰｂＯ－Ｂｉ２Ｏ３－Ｂ２Ｏ３－ＳｉＯ２玻璃系的光学性能与结构．密度最高可达８．４６４ｇ／ｃｍ３其紫外吸收达截止波长随Ｐｂ２＋及Ｂｉ３＋含量升高而红移．玻璃熔化温度低达８５０℃．在ＰｂＯ－Ｂｉ２Ｏ３－Ｂ２Ｏ３系玻璃中加人ＳｉＯ２可使玻璃结构更致密．室温下该系统玻璃在３６０ｎｍ有一个宽的激发峰，能产生４１８ｕｍ及４３８ｕｍ两个弱的发射峰．该系统玻璃的结构是由［ＳｉＯ４］４－、［ＢＯ３］３－、［ＢＯ４］５－、［ＰｂＯ４］６－及［ＢｉＯ６］９－构成．其中部分Ｐｂ２＋及Ｂｉ３＋以网络外体进入玻璃．     

Experimental studies of new ductile coupling beams and multi-storey shear walls

The span-depth ratios of coupling beams to interconnect shear walls are generally small, so that brittle shear failure may occur and lead to reduced ductility. In order to improve the ductility of coupling beams for earthquake loading, a new type of ductile coupling beam is proposed in this paper. Along the middle depth of this beam, a slit through the entire thickness (a narrow hole) near each end and two lateral keyways along the remaining middle part of the span are made. The reductions of the stiffness under service load and the ultimate carrying capacity of the beam due to the weakening mentioned above are small and the ductility is greatly increased. Tests of 4-storey walls interconnected by coupling beams in three different constructions (monolithic beams, beams with a through-slit and new-type beams) indicated that shear walls with the new coupling beams possess the best aseismic behaviours under cyclic loading. The proposed new coupling beam has been used in a high-rise building.