Numerical Simulation of Wind and Temperature Fields over Beijing Area in Summer   总被引：4，自引：0，他引：4  

HU Xiaoming  LIU Shuhu  WANG Yingchun  LI Ju 《Acta Meteorologica Sinica》2005,19(1):120-127

1. IntroductionThe basic role of urban-rural boundary layer re-search is to study all kinds of physical process changesin the atmosphere boundary layer over urban and itssurrounding areas. Urban heat island (UHI) is a well-known feature of urban-rural climate. Attempts toincrease the understanding of the causes of the UHIand other urban-rural boundary layer phenomena haveused observational, theoretical and modelling methodssince long before. Seaman (1989) used a hydrostaticmodel, with real …  相似文献   

A precise monitoring of snow surface height in the region of Lambert Glacier basin-Amery Ice Shelf,East Antarctica   总被引：2，自引：0，他引：2  

I.Allison 《中国科学D辑(英文版)》2005,48(1):100-111

The net surface snow accumulation on the Antarctic ice sheet is determined by a combination of precipitation, sublimation and wind redistribution. We present a one-year record of hourly snow-height measurements at LGB69 (70°50'S, 77°04'E, 1850 m a.s.l.). east side of Lambert Glacier basin (LGB), and 4 year record at G3 (70°53'S, 69°52'E, 84 m a.s.l.), Amery Ice Shelf (AIS). The measurements were made with ultrasonic sensors mounted on automatic weather stations installed at two sites. The snow accumulation at LGB69 is approximately 70 cm. Throughout the winter, between April and September, there was little change in surface snow height (SSH) at the two sites. The negative SSH change is due to densification at LGB69, and is due to both ablation and densification at G3. The strongest accumulation at two sites occurred during the period between October and March (accounting for 101.6% at LGB69), with four episodic increasing events occurring during 2002 for LGB69, and eight events during 1999-2002 for G  相似文献   

Studies on wind environment around high buildings in urban areas     

LIU Huizhi  JIANG Yujun  LIANG Bin  ZHU Fengrong  ZHANG Boyin  SANG Jianguo 《中国科学D辑(英文版)》2005,48(Z2)

High buildings or architectural complex in urban areas remarkably distort the urban surface wind fields. As the air flow approaches,local strong wind may appear around the buildings. The strong wind makes the pedestrians on sidewalks, entrances and terrace very uncomfortable and causes the pedestrian level wind environment problem. In this studies, hot-wire wind measurement, wind scouring in wind tunnel and numerical computation were carried out to evaluate the wind environment of tall buildings in the prevailing flow conditions in Beijing areas. The results obtained by three techniques were compared and mutually verified. The conclusions drawn from three approaches agree with each other. Also the advantages and limitations of each method were analyzed. It is suggested that the combination of different techniques may produce better assessment of wind environment around high buildings.  相似文献   

Late Glacial to Holocene coastal changes of SE Rügen Island (Baltic Sea, NE Germany)     

Gösta Hoffmann  Jens Barnasch 《Aquatic Sciences - Research Across Boundaries》2005,67(2):132-141

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浙江江山石鼓水库除险加固工程技术措施          下载免费PDF全文

龚新晖  郐开富  刘席军 《探矿工程》2005,32(4):31-34

根据浙江江山石鼓水库大坝的结构构造特点、水库地质条件以及水库病险原因与状况，制定出一套科学完善的病险水库除险加固工程技术措施和施工操作规程，对病险水库进行了全面彻底治理，并取得良好效果。详细介绍了工程病险状况，除险加固方案设计，施工工艺及操作规程，加固效果检测及评价等。  相似文献   

Sustainability schizophrenia or “actually existing sustainabilities?” toward a broader understanding of the politics and promise of local sustainability in the US     

Rob Krueger  Julian Agyeman 《Geoforum》2005,36(4):410-417

As an approach to development, many see capitalism as reaching across an enormous range of scholarly domains and political interests. For some time geographers and others have begun to conceptualize capitalism as less of a system of intrinsic economic logic and more a collection of social and discursive relationships. By bringing capitalism into the “discursive world” these commentators and others have provided the theoretical ground for an exploration of alternative economic forms, especially those that are more socially and ecologically just. This paper makes an argument for putting sustainable development through the same theoretical scrutiny. Drawing on examples from the US we recruit the concept of “actually existing sustainabilities” from Altvater’s concept “actually existing socialisms” as an entry point to this conversation. Our purpose is to show that the potential for sustainability in the US exists in current local policies and practices if we rethink how we frame it.  相似文献   

固沙林庇护区内降尘特征的初步观测   总被引：2，自引：1，他引：2  

张华  何红  李锋瑞 《干旱区地理》2005,28(2):156-160

采用野外定位实测法,连续两年对科尔沁沙地24龄人工固沙杨树(Populussimonii)林庇护区内4～6月份及强沙尘暴事件中的降尘特征进行了观测研究。结果表明:(1)林地庇护区内4、5月份的降尘量较多,分别为273和437kg/hm2,6月份的降尘量较少,为171kg/hm2。(2)林地中央的滞尘效应在风蚀季节和强沙尘暴天气过程中十分显著。(3)林地庇护区内的降尘中粒径<0.02mm颗粒含量占60.7%,降尘中的全C、全N和速效P含量分别高达1.676%、0.163%和210.66mg/kg,这对风沙土表层土壤的细化和养分的积累具有重要的生态学意义。  相似文献   

Three dimensional numerical simulation of residential building on shrink–swell soils in response to climatic conditions          下载免费PDF全文

Xiong Zhang  Jean‐Louis Briaud 《国际地质力学数值与分析法杂志》2015,39(13):1369-1409

Shrink–swell soils can cause distresses in buildings, and every year, the economic loss associated with this problem is huge. This paper presents a comprehensive system for simulating the soil–foundation–building system and its response to daily weather conditions. Weather data include rainfall, solar radiation, air temperature, relative humidity, and wind speed, all of which are readily available from a local weather station or the Internet. These data are used to determine simulation flux boundary conditions. Different methods are proposed to simulate different boundary conditions: bare soil, trees, and vegetation. A coupled hydro‐mechanical stress analysis is used to simulate the volume change of shrink–swell soils due to both mechanical stress and water content variations. Coupled hydro‐mechanical stress‐jointed elements are used to simulate the interaction between the soil and the slab, and general shell elements are used to simulate structural behavior. All the models are combined into one finite element program to predict the entire system's behavior. This paper first described the theory for the simulations. A site in Arlington, Texas, is then selected to demonstrate the application of the proposed system. Simulation results are shown, and a comparison between measured and predicted movements for four footings in Arlington, Texas, over a 2‐year period is presented. Finally, a three‐dimensional simulation is made for a virtual residential building on shrink–swell soils to identify the influence of various factors. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

1980—2015年风蚀影响下中国北方土壤有机质与养分流失时空特征     

赵海鹏  宋宏权  刘鹏飞  李霄阳  王团徽 《地理研究》2019,38(11):2778-2789

中国北方干旱/半干旱区是全球主要的沙尘源区之一,风蚀造成的沙尘排放可导致大量的土壤有机质（SOM）与养分流失,并通过传输与沉降过程对其进行空间再分配,对空气质量、气候变化、植被生长及生物地球化学过程等具有重要影响。本文利用WRF/Chem（Weather Research Forecasting with Chemistry）v3.7.1大气化学传输模型,对1980—2015年间中国北方沙尘排放及其引起的SOM、全氮（TN）与全磷（TP）的时空变化过程进行了精细化模拟,探究了中国北方风蚀引起的SOM、TN与TP养分流失的时空变化特征。结果表明：① 1980—2015年来平均每年约有66.59 Tg的沙尘颗粒排放至大气;② 沙尘排放具有较大的时空差异,沙尘排放源区主要集中在新疆东部、内蒙古西部的巴丹吉林沙漠和腾格里沙漠等地区;③ 每年因沙尘排放引起的SOM、TN和TP流失量分别约为0.07 Tg、0.004 Tg和0.005 Tg;④ 1980—2015年间中国北方沙尘排放及其引起的SOM、TN与TP的流失量具有较强的年际波动,未呈现显著的趋势性变化特征。本研究对于认知风蚀在碳循环与养分循环过程中的作用,以及对深入了解中国北方的土地退化机理具有重要意义。  相似文献   

海上风机吸力式桶形基础承载特性研究综述     

毋晓妮  廖倩  李晔 《海洋技术学报》2020,39(1):91-106

风机基础作为海上风机整体结构的重要组成部分,承受着上部风机所受到的风浪流荷载,并且对风机的安全性及可靠性至关重要。吸力式桶形基础由于其安装简单和可重复利用等优点,在海洋平台基础中得到了广泛应用,并逐步应用于海上风机基础中。但由于海上风机与海洋平台在海洋环境中的荷载工况有一定的差别,仍需要通过对其承载特性研究现状进行全面认识,以实现吸力式桶形基础在海上风机基础中的可靠应用。文中通过总结和评价现有研究对桶形基础在不同土体条件以及荷载条件下进行试验及数值模拟分析得到的研究结果,综述了静荷载和循环荷载作用下砂土和黏土中的吸力式桶形基础的承载特性研究现状,以及海上风机吸力式桶形基础的相关研究。文章展望了目前应用于海上风机基础的桶形基础仍缺乏的研究,为海上风机吸力式桶形基础的可靠应用及后续研究提供重要参考。  相似文献