基于三点估计法的直流配电中心概率潮流计算

分布式电源呈间歇性/波动性,负荷呈随机性,利用概率统计理论研究基于不确定性量的电力系统规划、运行与控制已成为当前的研究热点.针对近年来不断增加的以风电、光伏为代表的分布式电源接入柔性直流配电网的现象,开展了概率潮流研究.以Nataf变换方法结合Cholesky分解进行不确定变量的相关性处理,提出了一种计及输入变量相关性...     

远红外频率选择表面的传输特性分析

设计了十字单元的远红外带通型频率选择表面(FSS),并采用模匹配法对其传输特性进行了研究,其中单元中的场分布用有限元法求出。根据此方法研究了不同极化方式的电磁波在斜入射条件下,对不同布阵方式的远红外FSS传输特性的影响。结果发现,无论单元是按正方形布阵还是按正三角形布阵,在电磁波斜入射时中心频率都随入射角的增大而向低频漂移,带宽都相应减小。但无论入射波是什么极化方式,所设计单元按正三角形布阵时的传输特性都比正方形布阵方式稳定。     

申报世界遗产保护和永续利用人类瑰宝

目前中国的世界遗产地的发展存在重申报、轻管理,在全国范围内缺乏有效、统一的协调和管理,过度开发利用与被动保护管理等问题.中国应强化国家对世界遗产地工作的协调、领导和管理,注重对遗产资源的严格管理和科学利用,加强世界遗产地间的沟通交流与遗产资源保护的宣传等.     

沈庭景胜 --2006年沈阳世界园艺博览会沈阳园设计

在沈阳园的设计中,设计师充分利用北方大环境的特征及基地中细微的高差、观视角度等元素突出沈阳地域特性.为了能将园林功能融入园林设计之中,设计师大量运用了欲扬先抑等手法.     

复合补偿在印制板尺寸变形修正中的应用

印制板生产过程中,基材不可避免会出现平面上的尺寸涨缩变形,业内一般对此种变形进行经验性或基于试制的结果进行反向预补偿,此种预补偿有一定概率达不到预期效果.文章提出通过分区抓取PCB板件的几何中心,并在模拟平面二维线性形变的基础上对PCB成品尺寸变形进行复合补偿,可以有效解决上述问题.     

短消息图书自动查询系统的设计与实现

在分析了目前传统查书方式的缺点和短信查询优势的基础上提出了利用短信实现客户服务的系统模型,详细分析其实现方案.并讨论了关键技术和解决方法.该系统现已投入使用,具有接入简单,处理迅速,可扩展性好等特点.     

Oil Demand and Stocks

Current data of world oil demand. This includes international bunkers and refinery fuel. Updated on a monthly basis. Current data of oil demand from counties such as Canada, the United States of America, Japan, OECD Europe, Belgium, France, Germany, Italy, Netherlands, Spain, Sweden, the United Kingdom, Australia, Mexico, Republic of Korea, and Turkey. Updated on a monthly basis. Current data for crude oil and refined product stocks in Canada, Chile, Mexico, the United States (Western Hemisphere), France, Germany, Italy, Netherlands, Spain, the United Kingdom and Other Europe (Europe), Japan, Republic of Korea, Other Pacific (Asia-Pacific), and Total OECD (Table 12.1) Current data for refined product stocks in the OECD Western Hemisphere, OECD Europe, OECD Asia-Pacific and Total OECD. Products include gasoline, diesel and gasoil, and heavy fuel oil. Updated on a monthly basis (Table 12.2).     

Enhanced electrical conductivity of alumina/nano-carbon ceramic composite via iodine impregnation of gel-casted alumina body and reductive sintering

In this work, we present the fabrication of alumina/nano-carbon ceramic composite displaying enhanced electrical conductivity through facile iodine impregnation of gel-casted alumina body. Following the previously developed novel fabrication process of alumina/nano-carbon composite having a highly uniform nano-carbon network and superior semi-conductive properties via reductive sintering of gel-casted alumina body under inert atmosphere, we extended the process through the facile impregnation of gel-casted body in iodine solution resulting in enhancement of the amount of nano-carbon, graphitization degree, electrical conductivity and carrier density. The effect of iodine concentration on the properties of alumina/nano-carbon as well as the mechanism for enhanced electrical performance are also systematically investigated.     

Production of porous SiC by liquid phase sintering using graphite as sacrificial phase: Influence of SiO2 and graphite on the sintering mechanisms

Porous silicon carbide (SiC) is a promising ceramic for high-temperature applications due to its unique combination of properties. In the present work, a fabrication route for porous SiC is presented using graphite spherical powder as sacrificial phase to introduce porosity. By varying the initial amount of sacrificial phase, high-performance SiC materials with porosities in the range 30–50% were manufactured and characterized in terms of microstructure, density, thermal conductivity and flexural strength. The materials were fabricated by liquid phase sintering in presence of 2.5 wt.% Al₂O₃ and Y₂O₃ as sintering additives. The results indicate that the SiO₂ present in the starting SiC powders interacts with the sintering additives forming liquid phases that promote densification and weight loss. Besides, an Al-Si liquid phase is formed at higher sintering temperatures, whose contribution to densification is inhibited in presence of graphite due to the formation of Al-rich carbides.     

基于大冬会和世界杯分析哈尔滨啤酒体育营销策略

哈尔滨啤酒是中国最早的啤酒品牌,连续获得"中国名牌产品"。在百威英博啤酒集团的领导下,品牌战略逐渐得到完善,并建立了全方位的营销网络,借助世界杯赛事迅速抢占国内市场,形成专业的商业营销模式,让企业得到了高度发展,其品牌渗透力更是超越"雪花""青岛""燕京"等国内啤酒大商。哈尔滨啤酒不仅仅以全国市场为目标,更是以远销国外为目标,在国家的舞台上演绎属于东方传奇。哈尔滨啤酒作为一个百年品牌,其纯正清爽的口味得到了越来越多消费者的喜爱。先后成为"大冬会""世界杯"等体育赛事的赞助商,让哈尔滨啤酒走向了全世界。因此,本文以"大冬会"和"世界杯"为例,分析哈尔滨啤酒体育营销策略计划。通过介绍哈尔滨啤酒的品牌故事及酿造工艺,展开对哈尔滨啤酒在体育赛事以及全国市场的营销战略推广。