Surface Gravity on the Horizon of η- ξ Spacetime

We investigate the two methods of defining the surface gravity ,κ on the horizon, which are the metric definition and the definition given by the spacetime conformal method. It is found that the latter is of greater generality. By this method, we find that ,κ of η- ξ spacetime is equal to the exponent factor α in the coordinate transformation, which confirms the argument that η- ξ spacetime can be considered as the background spacetime for finitetemperature field theories. The reasons why the metric definition of ,κ can not be applied in η- ξ spacetime are presented.     

基于特征的地平线遮挡剔除算法

可见性计算是计算机图形学的一个基本问题,高效的可见性计算可大量节省关于场景中不可见部分的计算。提出了一种新的基于地形特征的可见性判别算法。该算法首先提取场景的主要山脊线特征,然后构造地形的多分辨率层次细节模型,实现对四叉树结点的快速访问,最后应用增量地平线消隐技术及地形包围盒技术,实现了基于地形山脊线特征的快速遮挡剔除算法。实验结果证明了此算法的有效性。     

低空背景下红外目标提取跟踪算法研究

为解决低空复杂背景下红外目标的提取和跟踪,提出了地平线检测排除地物背景的方法,然后在地平线之上的区域,采用边缘检测、阈值分割、边界搜索算法并结合多帧图像的相关性以及目标形态和运动参数的连续性来提取目标。实验表明,本文的算法计算量小、实时性强,可以有效检测出地平线,排除低空背景和假目标的干扰,实现稳定的跟踪,并最终完成了DSP的硬件实现。     

接头盒的种类

此类支架型接头盒包括所有放在支架上的接头盒。支架接头盒的技术要求低于地下接头盒。它必须符合抗御3m深水浸的标准，因为这些接头盒的高度与地平线同高，而且支架也并不一定具有防水功能。Bellcore GR-771标准允许支架式接头盒透气或密封。因此，GR-771支架式接头盒额定指标显然不能满足防洪要求。由于这些接头盒是靠支架保护的，故对防撞击、防压和防腐蚀的要求不高。Bellcore不要求对支架型接头盒做防冻、解冻试验。     

Quantum Tunnelling and Hawking Radiation of Schwarzchild-Anti-de Sitter Black Hole with Topological Defect

We extend Parikh＇s recent work to Schwarzchild-anti-de Sitter black hole with topological defect whose Arnowitt-Deser-Misner （ADM） mass is no longer identical to its mass parameter. We view the Hawking radiation as a tunnelling process across the event horizon and the cosmological horizon. From the tunnelling probability, we find a leading correction to the semi-classical emission rate. The result employs an underlying unitary theory.     

Optimal policies for inventory systems with discretionary sales, random yield and lost sales

We determine replenishment and sales decisions jointly for an inventory system with random demand, lost sales and random yield. Demands in consecutive periods are independent random variables and their distributions are known. We incorporate discretionary sales, when inventory may be set aside to satisfy future demand even if some present demand may be lost. Our objective is to minimize the total discounted cost over the problem horizon by choosing an optimal replenishment and discretionary sales policy. We obtain the structure of the optimal replenishment and discretionary sales policy and show that the optimal policy for finite horizon problem converges to that of the infinite horizon problem. Moreover, we compare the optimal policy under random yield with that under certain yield, and show that the optimal order quantity （sales quantity） under random yield is more （less） than that under certain yield.     

Bekenstein-Hawking Cosmological Entropy and Correction Term Corresponding Cosmological Horizon of Rotating and Charged Black String

Utilizing the quantum statistical method and applying the new state density equation motivated by generalized uncertainty principle in quantum gravitaty, we avoid the difficulty in solving wave equation and directly calculate the partition function of bosonic and fermionic field on the background of rotating and charged black string. Then near the cosmological horizon, entropies of bosonic and fermionic field are calculated on the background of black string. When constant A introduced in generalized uncertainty principle takes a proper value, we derive Bekenstein- Hawking entropy and the correction value corresponding cosmologicaJ horizon on the background of rotating and charged black string. Because we use the new state density equation, in our calculation there are not divergent term and small mass approximation in the original brick-wall method. From the view of quantum statistic mechanics, the correction value to Bekenstein-Hawking entropy of the black string is derived. It makes people deeply understand the correction value to the entropy of the black string cosmological horizon in non-spherical coordinate spacetime.     

RELATIONSHIP BETWEEN HORIZONTAL EXTINCTION COEFFICIENT AND PM10 CONCENTRATION IN XI＇AN, CHINA, DURING 1980-2002

Based on daily visibility data obtained from 1980-2002 and air pollution index data from 2001-2004 in Xi＇an, long-term variations and relationships for daily horizontal extinction coefficient and mass concentration of PM10 have been evaluated. A decreasing trend was found in horizontal extinction coefficient during the past 23 years, with higher values observed in 1980s relative to 1990s, and the highest and lowest values in winter and summer, respectively. Significant correlation and similar seasonal variations existed between horizontal extinction coefficient and PM10 concentration, suggesting the high influence of PM10 to the visibility drop at a site in the Guanzhong Plain of central China during the past two decades.     

太阳何时落山?

夕阳的最后一缕光辉究竟是在哪一瞬间消失的？这个问题的答案并不像常识所认为的那么简单，这是因为在地平线附近大气折射的影响要比以前科学家们所认识的不规则得多．     

时尚如意红 三星UA46EH5080R液晶电视

时尚中国风三星UA46EH5080R液晶电视的设计灵感源自于中国传统红色元素,寓意喜庆、吉祥、幸福和如意等,时尚典雅的红色背板与金属质感的红色贝壳底座交相辉映,延伸至正面边框,露出一丝精巧的红边,宛如太阳升起在地平线。One Design窄边框设计,摒弃了传统外观的厚重边缘,在外观尺寸不变的情况