一种基于码本聚类的低复杂度用户选择算法

现有块对角化(BD)预编码系统用户选择算法较少考虑利用已选用户与剩余用户之间的关系来排除不可选用户.针对这点不足,给出了一种采用码本聚类的低复杂度用户选择算法( CodeGreedy算法).该算法采用弦距离刻画用户信道的相关性,以此为依据将用户划分到不同码本空间中,聚集在同一码本空间的用户信道具有较强的相关性,形成互斥...     

网络时代知识产权犯罪问题研究及其对策

侵犯知识产权是互联网上一股来势凶猛的暗流!使传统的刑事法律受到挑战,迫切需要相关各界作出及时回应,从意识、法律和技术上加以遏制,以保护知识产权人的权利,进而维护全社会的科学技术和文学艺术的进步.     

动画动态定位在网页上的方法

网页上经常会显示一些动画,如重要信息或广告等。本文用JavaScript实现了使动画固定在网页画面的相对位置上,不会被移出画面。     

Polycrystalline diamond MESFETs by Au-mask technology for RF applications

Metal-semiconductor field effect transistors (MESFETs) were fabricated on H-terminated polycrystalline diamond.The DC characteristics of the p-channel MESFET showed a maximum drain current density of 204 mA/mm at a gate-source voltage of 6 V,and a maximum transconductance of 20 mS/mm at a gate-source voltage of 1.5 V.The small signal S-parameters of MESFET with 2 100 m gate width and 2 m gate length were measured.An extrinsic cut-off frequency (fT) of 1.7 GHz and the maximum oscillation frequency (fmax) of 2.5 GHz were obtained,which was the first report on diamond MESFETs with RF characteristics in China.     

The oxidation state of sulfur detected in Na2O-CaO-SiO2 float glass by X-ray absorption near edge structure spectra

The oxidation state of sulfur is detected in Na2O-CaO-SiO2 float glass by synchrotron radiation X-ray absorption near edge structure (XANES) spectra at the sulfur K edge. The measured spectra show the only presence of S6+ in the Na2O-CaO-SiO2 float glass and the oxidation state of sulfur do not change with the increase of glass depth. It is also found that, after the melt has gone through the molten tin bath, the S6+ is the dominant species, but S2- is also present on both surfaces. It is not certain whether cation bonds to S2- or not, because there are many cations dissolved in the melted tin which makes the spectrum complicated.     

Model study of IPMC beam electroactive response based on root deformation

Ionic polymer-metal composite (IPMC) is a type of electroactive polymer (EAP). In this paper, based on Nemat-Nasser model, an improved model is developed to explain the initial nonlinear response of electric actuation on the fixed end deformation. Three IPMC strip samples with different surface resistance are chosen for analysis. Further, from simulation and experiment results, it is found that the root deformation made the tip movement of the IPMC strip with little surface resistance, but this effect was less and less when the surface resistance reduced. The calculation results of this model for the fixed end show a more accurate simulation for the actual deformation of IPMC strips.     

科技期刊编辑职业健康危害及其对策

对科技期刊编辑人员职业危害度及职业倦怠的成因进行分析,提出预防措施和对策,呼吁科技期刊编辑人员关注自己的职业健康。科技期刊理论学应把科技期刊编辑职业健康及其影响因素的研究纳入研究的范畴。     

C*-代数中Moore-Penrose逆及Bott-Duffin逆的扰动分析

设A为C*-代数,a,-a=a δa∈A并且a 存在,‖a ‖‖δa‖<1。定义-a是a的稳定扰动,当且仅当-aA∩(1-aa )A={0}。此时-a 存在,并且‖-a ‖的上界被给出。对于B-D广义逆a p,在给出一般表达式的前提下,对于一类具有“p-零”性质的B-D广义逆,得到了‖-a p‖的一个上界。     

ZF12-145(L)气体绝缘金属封闭开关设备断路器

介绍了ZF12-145（L）三相共箱式气体绝缘金属封闭开关设备断路器的技术参数、性能、灭弧室的计算分析和主要特点.     

SiO2(am)在FoCa粘土和MX-80粘土中扩散实验的模拟

不定形二氧化硅[Amorphous Silica，简称SiO2（am）]是高放废物玻璃固化体在处置后，发生降解的主要产物。对SiO2（am）在FbCa粘土和MX-80粘土柱中的扩散迁移进行了实验研究，结果显示：在粘土柱中有大量的SiO2（am）沉淀产生；土柱中总Si增加量与时间的关系基本为线性正相关关系。采用CRUNCH程序对上述扩散迁移实验进行了模拟，模拟内容包括：溶液和岩相中Si浓度变化、总的筋增加量与时间的关系以及实验期间孔隙率的变化；同时分析了有效扩散系数对结果的影响。结果说明，使用CRUNCH程序进行反应迁移模拟是可行的；但是实验中pH值测量时机不适当；另外由于土样本身Si含量较高，易对土柱总Si的分析结果产生影响，这些因素需进一步实验时改进。