Results 21 to 30 of about 9,868 (174)
ABSTRACT Background Hazardous levels of contaminants produced by anthropogenic activities are increasingly pervading residential environs and urban areas. Hazardous contamination can pose significant health risks for citizens dwelling in exposure pathways.
Rosina Johnson +3 more
wiley +1 more source
Optimum sizing of PV/Wind hybrid system (I) CAD method [PDF]
2003-2004 > Academic research: refereed > Publication in refereed journalVersion of ...
Ai, B, Liao, X, Shen, H, Yang, HX
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Abstract Identifying refugia from emerging threats is vital to ensure the persistence of rare and threatened species, but modeling habitat distribution for these species is challenging and the role of people in refuge management is rarely considered. Myrtle rust is an emerging infectious disease that represents a grave threat to the rare wetland tree ...
Sarah M. Herbert +7 more
wiley +1 more source
Wind Turbine Modeling and Control Study based on LPV Model [PDF]
风能是一种清洁可再生能源,其开发和利用越来越受人们的重视。风力发电机是利用风能发电的设备,近年来,风力发电机逐渐向高效率、高可靠性和大型化发展,使风力发电机的动态模型变得更加复杂。为了使风力发电机平稳可靠运行,提高发电效益,对风力发电机进行建模和控制很有必要。本文针对风力发电机的动态非线性特性,基于LPV模型辨识方法对风力发电机建模,后用辨识所得LPV模型设计MPC控制器,对风力发电机进行变桨距控制。论文的主要工作有: (1)讨论风力发电机的原理模型,分别分析各分块原理模型和一些常用的计算机仿真工具。 (
曹力仁
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Assessing the Corn Belt as an anthropogenic barrier to migrating landbirds in the United States
Abstract Migrating landbirds adjust their flight and stopover behaviors to efficiently cross inhospitable geographies, such as the Gulf of Mexico and the Sahara Desert. In addition to these natural barriers, birds may increasingly encounter anthropogenic barriers created by large‐scale changes in land use. One such barrier could be the Corn Belt in the
Fengyi Guo +7 more
wiley +1 more source
Remote Sensing Retrieval Algorithms and Spatial-temporal Characteristics of POC in the South China Sea [PDF]
颗粒有机碳(ParticulateOrganicCarbon,POC)是海洋生物地球化学过程的重要组成部分,随着光学技术和遥感手段的进步,在不同时空尺度下监测POC取得很大突破。本文以2011年国家自然科学基金委南海共享航次现场光学数据为基础,探索适用于南海POC反演的海色卫星遥感算法,将算法应用到卫SeaWifs遥感反射比Rrs(λ)数据,得到南海月平均POC,并分析其在季节和年际时间尺度上的时空变化特征。 首先,依据现场观测遥感反射比Rrs(λ)和POC,用多种方法来估算南海表层POC浓度 ...
张鹏
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登塔是输电线路施工、巡视和检修的重要技术手段,而特高压输电线路截面大且为高耸的塔线耦合的弱阻尼系统,其风致振动特性及其对登塔作业人员的影响对确保作业和人员安全具有重要意义。针对±800 kV直流输电线路建立了输电线路塔线耦合体系有限元模型,基于风速随高度变化的Kaimal谱和谐波叠加法生成了2 m高风速分别为6、8、10 m/s的风速时程,应用模拟的风荷载对三塔两线体系在A、B两种地形下的风振响应进行了时域分析,并讨论了铁塔振动对登塔作业人员的影响。结果表明:在2 m高风速为6 m/s时,A ...
吴田 +4 more
doaj
On the normative roles of biodiversity and naturalness in conservation
Abstract Nature is an opaque concept. Consequently, the term biodiversity conservation has replaced nature conservation in most conservation contexts. We review the conceptual indeterminacies that plague the terms nature and natural but then show that comparable difficulties plague biodiversity.
David Saltz, Shlomo Cohen
wiley +1 more source
通过风洞实验,在5个风速下对6种不同结构的垄作及平作对照地的土壤风蚀速率、O~20cm风沙流结构进行了模拟观测研究。结果表明:垄作下平均土壤风蚀速率较平作下降低20%~60%。垄作和平作下土壤风蚀速率均随风速的增大呈幂函数递增,但平作下递增较快。风速为15m/s是早作农田土壤风蚀加剧的转折点,当风速大于15m/s时垄作下风蚀速率较平作下明显降低。0~20cm内,平作和垄作下输沙率与高度分别呈负指数和负线性关系。垄作下0~4cm输沙量和输沙量百分比(Q0~4/Q0~20)均低于平作 ...
刘目兴 王静爱 产平 刘连友 李小雁
doaj
Triboelectric Nanogenerator Structure Designs and Mechanical Energy Harvesting Applications [PDF]
随着环境污染、能源危机等社会问题的加剧,发展新型、高效且能够直接从环境中收集能量的新能源技术成为当今科学技术发展的一个重要课题。在各式各样的能量来源中,机械能由于其广泛存在于日常生活环境中,已经成为最受人们关注的能源之一。基于上述背景,纳米发电机——一种利用纳米材料和纳米结构收集机械能并转化成电能的新技术——于2006年被美国佐治亚理工学院王中林院士课题组首次提出,并快速发展成为一种高效且具有广泛实际应用前景的新能源技术。近年来,随着纳米发电机技术的发展,该领域的一个重要分支 ...
谢燕楠
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