On the optimum design of unitary cyclic group space-time codes

In this letter, based on the exact pairwise-error probability, we derive the union bound on the symbol-error probability (SEP) of the differential unitary space-time (DUST) modulation employing group codes. Instead of using the rank-and-determinant or Euclidean distance criteria, we optimize the cyclic group codes such that the union bound on the SEP is minimized for a predetermined scenario, taking into account the number of transmit and receive antennas and the operating signal-to-noise ratio (SNR). Our simulation results show that for a wide range of SNRs, the codes with the minimum union bound for a particular SNR outperform the codes designed based on rank-and-determinant or Euclidean distance criteria.     

润滑油添加剂的升级换代和需求预测

简要介绍了润滑油添加剂的供需现状和发展预测，分析了推动润滑油添加剂升级换代的动力，阐述了即将推出的GF—4发动机油规格对添加剂的新要求。     

“香山81号院”（半山枫林二期）外环境设计

1“居山”与”隐贵山居“ 回想一下人类的聚居行为颇为有趣，当年我们的祖先拼命从险山恶水的自然环境中挣脱出来，为的是得到更加安全和便利的聚居条件，但似乎从那一刻起本能式的回归意识便时刻魂牵梦绕，隐隐作响。其实无论是脱离自然还是回归自然，对于现实而言两者皆是虚幻和理想的。     

UCT测井技术在河南油田的应用

介绍了超声波固井质量检测仪(UCT)的原理、结构及测井方法，分析了UCT测井资料的应用情况。实践表明，UCT能准确地探测套管腐蚀，直观评价水泥与套管、水泥与地层一、二界面的胶结质量。     

女人一生的避孕攻略——不同时期的避孕法则

女性自初潮开始到绝经的过程中，有30多年的时间需要避孕。如何在这样漫长的时间里安全避孕。是每位女性维护自身健康必不可少的一项措施。有人说：“怀孕是生命力的表现，如果我们不用避孕了，那一定不是老了就是病了。”因此。避孕对于女性来说，是一件甜蜜而又麻烦的事。如果因意外怀孕而不得不采取人工流产。不仅会给女性带来心灵上无法抚平的伤害，还可能由此引发不孕、感染以及妇科肿瘤等不良后果。因此了解各种避孕节育方法的有效性、优缺点，将有助于女性在人生的不同阶段，选择那些有效、安全、适合自己的避孕节育方法，降低避孕失败的风险。[编者按]     

营造休闲空间

商店酒店．餐厅和酒吧是人们享受消费体验的场所．商业空间的设计需要抓住的是人们对这种体验过程的需求。营造不同的空间氛围可以吸引不同品位的类型的消费人群。在商店中商品不是顾客唯一寻求的东西．别致舒适的试衣间，通透明亮的镜子与室内环境的搭配甚至柜台提供的糖果都是购物者所需要的东西。同样餐厅的主角不一定是食物，精致的餐具同样可以吸引回头客的光顾．酒吧沙发上的靠垫：酒店大厅的天花板都可能是成为有价值的卖点：86期的《WALLPAPER》为我们挑选了来自世界流行消费场所．他们的卖点又在哪里呢？     

OpenType字体技术

OpenType字体技术是Type字体和TrueType字体“大战”的产物，也是响应Unicode字符编码标准的产物，更是Adobe与Microsoft公司合作的产物。单从时间概念上考虑，这种字体技术其实并不新，现在重提OpenType字体，是因为CS2套件对于OpenType字体的全面支持，以及OpenType字体具有许多最要的特征。     

En/Decoder for Spectral Phase-Coded OCDMA System Based on Amplitude Sampled FBG

A novel en/decoder for spectral phase-coded optical code-division multiple-access system based on amplitude sampled fiber Bragg grating (FBG) is proposed. Both equivalent chirp and equivalent phase shift are achieved by amplitude sampling. Compared with previous en/decoder based on step chirped FBG, it is easier to fabricate. The performance of the proposed en/decoder is verified by both numerical simulation and experimental demonstration.     

Study of trace elements in coal and mining wastes and its significance in China

In the world energy about 26% of all was dedved from coal combustion. Nearly 80% of the electricity produced in China is generated from coal. Coal will play the most important role in the coming 50 years as the past century in China. However one consequentially of the mining and combustion of coal is the mobilization of trace elements, especially trace metals, which have environmental and human health significance. Information on concentrations and distributions of potentially toxic elements in coal, and information On the modes of occurrence of these elements and the relations of the minerals in coal can help to predict the behavior of the potentially toxic trace metals dudng cleaning, combustion, weathering, and leaching.     

Epoxidation of high trans‐1,4‐polyisoprene and its properties

A new organic‐solvent‐free water‐phase suspension method was used to synthesize partially epoxidized high trans‐1,4‐polyisoprene (TPI) to improve its properties, including oil resistance and wet‐skid resistance. The epoxidation was conducted in an aqueous peracetic acid solution and on the TPI granules prepared by a bulk precipitation method with supported titanium catalyst. The effects of the synthesis conditions, including reaction temperature, reaction time, and pH value, on the epoxy content were investigated. Epoxidized trans‐1,4‐polyisoprene (ETPI) with epoxy contents between 10 and 80% were obtained within 4 h. Both the amorphous and crystalline regions of TPI were epoxidized. The crystallization properties decreased with increasing epoxy content. ETPIs possessed lower mechanical properties than TPI but could be enhanced by vulcanization. The oil resistance and wet‐skid resistance were significantly improved after epoxidation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008