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Large eddy simulation of flow in a street canyon with tree planting under various atmospheric instability conditions

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Science china(Technological Sciences) 2010年第7期53卷 1928-1937页

作者： GU ZhaoLin1, ZHANG YunWei2 & LEI KangBin3.1 school of human settlements and {3. engineering, xi’an jiaotong University, xi’an 710049, china 1 school of Energy and Power engineering, xi’an jiaotong University, xi’an 710049, china 3.RIKEN Institute, Wako, Saitama, 3.1-0198, Japan school of human settlements and {3. engineering Xi’an Jiaotong University Xi’an China school of Energy and Power engineering Xi’an Jiaotong University Xi’an China RIKEN Institute Wako Saitama Japan

In this work, a large eddy simulation (LES) model, which includes momentum and heat source (or sink) inside the tree planting layer, is proposed for the simulation of flow in a street canyon with tree planting. Vegetation canopy layer simulation shows that this model can be used to simulate the velocity distribution and temperature variation inside the canopy layer. Effects of atmospheric instability on flow and pollutant distribution in a street canyon with tree planting of an aspect ratio of 0.5 are studied. Results show that compared with the canyon with no tree planting (or the exposed street canyon), the canyon with tree planting shows a reduced wind circulation and pollutant exchange rate (PER) at the top layer of the street canyon, which induces the increase in the pollutant concentrations near road surface, leeward wall and windward wall. When street canyon atmosphere is under a strongly unstable condition, wind velocity decreases while pollutant concentration is increased in the areas near the street canyon top, road surface, leeward and windward walls, compared with the wind velocity in the street canyon with the neutral stratification. When street canyon atmosphere is under a weakly unstable condition, wind velocity weakens near the street canyon top and windward wall, but strengthens near the road surface and leeward wall, and pollutant concentration is decreased near the leeward and windward walls and is increased between the two rows of trees. When the street canyon atmosphere is under an unstable condition, PER is lower than that under the neutral stratification.

关键词： street canyon flow tree planting atmospheric instability large eddy simulation pollutant concentration distribution

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Nitrogen isotopic composition of plant-soil in the Loess Plateau and its responding to environmental change

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Chinese Science Bulletin 2009年第2期54卷 272-279页

作者： LIU WeiGuo1,2 & WANG Zheng1,3.1 State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, xi’an 710075, china 2 xi’an {3. University, school of human settlement and civil engineering, xi’an 710049, china 3.Graduate University of Chinese Academy of Sciences, Beijing 100049, china State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China school of human settlement and {3. engineering Xi’an Jiaotong University Xi’an China Graduate University of Chinese Academy of Sciences Beijing China

The nitrogen isotope of soil is of emerging significance as an indicator of climatic change and biogeochemical cycle of nitrogen in nature systems. In this paper, the nitrogen content and isotopic composition of modern ecosystems from arid and semiarid Loess Plateau in northwestern china, including plant roots and surface soil, were determined to investigate trends in δ15N variation of plant roots and soil along a precipitation and temperature gradient in northwestern china under the East Asian Monsoon climate condition. The δ15N values of surface soil from the study area vary from ?1.2‰ to 5.8‰, but from -5.1‰ to 1.9‰ in the plant roots. Our results indicate that (1) although the isotopic compositions of both plant roots and surface soil change with a similar trend along the climate gradient, the apparent nitrogen difference between plant roots and soil existed, with -δ15N values ranging from 0.3. to 7.2‰ with average of 4.1‰; and (2) mean annual precipitation (MAP) is the dominant factor for isotopic composition of plant-soil nitrogen in the Loess Plateau, and the δ15N values are less correlated with MAT; we suggest that nitrogen isotopic composition of soil is a potential tracer for environmental changes.

关键词：氮同位素物理性质化学性质环境论

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Experimental Investigation on Local Air Age and Air Distribution of Stratum Ventilation

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湖南大学学报（自然科学版） 2009年第S1期36卷 35-39页

作者： WANG Feng-hao,LI Yuan-bin,LIU xiao-dong,WANG xin-ke(school of {3. settlements and civil engineering,xi’an jiaotong University,xi’an,Shaanxi 710049,china) school of human settlements and {3. engineering Xi'an Jiaotong University Xi'an 710049 China

Because of the multiple problems on high energy consumption and unbalanced thermal comfort caused by the traditional ventilation system,a new concept of ventilation-stratum ventilation has been proposed,which sends the fresh air to the breathing zone *** this paper,the local air distributions of the displacement ventilation and the stratum ventilation in a model office were *** air ages in the breathing zone for the displacement ventilation and stratum ventilation were compared with the tracer gas concentration decay *** decay curves of tracer gas concentration for these two ventilation systems in the breathing zone were obtained,and the air ages were *** experimental results show that the stratum ventilation system can offer lower air age for four mechanically ventilated cases in the breathing zone,and it can also provide better thermal comfort,which renews the air of breathing zone more quickly and reduces the energy consumption in some *** experimental investigation provides a theoretical basis for the application of stratum ventilation system.

关键词： ventilation air quality air age distribution

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A method for support stiffness failure identification in a steel spring floating slab track of urban railway: a case study in china

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2024年第3期25卷 206-222页

作者： Junyuan ZHENG Caiyou ZHAO Duojia SHI Ping WANG Jian WANG Bolong JIANG xi SHENG Key Laboratoryof High-speed Railway engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 60031China school of civil engineering Southwest Jiaotong UniversityChengdu 610031China 01 DYNA(Qingdao)Test&Data Co. Ltd.Qingdao 266000China Rail Transit Digital Construction and Measurement Technology National engineering Research Center China Railway Design CorporationTianjin300308China Institute of Urban Smart Transportation&Safety Maintenance Shenzhen UniversityShenzhen 518060China

The extensive use of steel spring floating slab tracks has effectively addressed the challenge of alleviating the environmental vibrations induced by urban rail transit ***,under the combined action of train dynamic loads and complex environmental factors,problems,such as the fracture of steel spring vibration isolators and suspension vibrations induced by the uneven settlement of the base,often *** failure of isolator support stiffness is often hidden in its early stages and is challenging to identify by conventional detection *** the same time,it will aggravate the wheel-rail interaction,accelerate the deterioration of track structure,and even affect the driving *** study first establishes a detailed coupled train-floating slab track-foundation analytical *** the influence of the vibration isolator support stiffness failure on the dynamic indices of the floating slab track system response is analyzed.A set of defect identification methods that can detect the number of failed steel springs,severity of damage,and their location is ***,an intelligent monitoring system for support stiffness of floating slab track is built by combining the density-based spatial clustering of applications with noise algorithm and statistical data analysis and is applied to a rail line in southern *** a three-year monitoring campaign,a suspension failure and a fracture of a steel spring were each successfully detected and detailed failure information was *** investigation results were consistent with the damage identification *** repair,the track structure dynamic response returned to the average pre-damage level and further deterioration had been *** proposed damage identification methods and monitoring system provide an approach for intelligent identification of track structure support stiffness failures.

关键词： Floating slab track Support stiffness Detailed analytical model Failure identification Monitoring system

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Advances in numerical methods for the solution of population balance equations for disperse phase systems

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Science china Chemistry 2009年第8期52卷 1063-1079页

作者： SU JunWei1,GU ZhaoLin2,3.& XU X.Yun41 Department of Mechanical engineering and Automation,school of Mechanical engineering,{3.’an jiaotong University,{3.’an 710049,china 2 Key Laboratory of Mechanics on Disaster and Environment in Western china,Ministry of Education,Lanzhou 73.000,china 3.Department of Environmental Science and Technology,school of human settlements and {13. engineering,{3.’an jiaotong University,{3.’an 710049,china 4 Department of Chemical engineering,Imperial College London,London SW7 2AZ,UK Department of Mechanical engineering and Automation School of Mechanical Engineering Xi’an Jiaotong University Xi’an China Key Laboratory of Mechanics on Disaster and Environment in Western china Ministry of Education Lanzhou China Department of Environmental Science and Technology School of Human Settlements and Civil Engineering Xi’an Jiaotong University Xi’an China Department of Chemical engineering Imperial College London London UK

Accurate prediction of the evolution of particle size distribution is critical to determining the dynamic flow structure of a disperse phase system.A population balance equation(PBE),a non-linear hyperbolic equation of the number density function,is usually employed to describe the micro-behavior(aggregation,breakage,growth,etc.) of a disperse phase and its effect on particle size *** solution is the only choice in most *** this paper,three different numerical methods(direct discretization methods,Monte Carlo methods,and moment methods) for the solution of a PBE are evaluated with regard to their ease of implementation,computational load and numerical *** attention is paid to the relatively new and superior moment methods including quadrature method of moments(QMOM),direct quadrature method of moments(DQMOM),modified quadrature method of moments(M-QMOM),adaptive direct quadrature method of moments(ADQMOM),fixed pivot quadrature method of moments(FPQMOM),moving particle ensemble method(MPEM) and local fixed pivot quadrature method of moments(LFPQMOM).The prospects of these methods are discussed in the final section,based on their individual merits and current state of development of the field.

关键词： population balance equation direct discretization method Monte Carlo method moment methods disperse phase system

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The application of geographic information technology to coastal geomorphology

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Acta Oceanologica Sinica 2009年第5期28卷 49-57页

作者： GUO Wei LI Shuheng ZHU Dakui school of human settlements and {3. engineering Xi＇an Jiaotong University Xi＇an 710049 China Department of Computer Sciences Xi＇an Jiaotong University Xi＇an 710049 China Department of Urban and Resources Sciences Northwest University Xi＇an 710032 China Faculty of Environmental Sciences University of Waterloo Waterloo N2L3G1 Canada Key Laboratory of Coast ＆ Island Development of Ministry of Education Nanjing University Nanjing 210093 China

With the development of modern oceanic observation technologies, coastal survey data have been experiencing a substantial growth. The integration management of the data from different disciplines, different sources and different formats has become a major research field in coastal geomorphology by using Geographic Information System （GIS）. This paper puts forward a new methodology framework of GIS techniques in coastal ocean geomorphology, including data acquisition, process, analysis, and representation. It focuses on some major GIS techniques to study the land-ocean interaction mechanism, such as spatial analysis, submarine topography model and three-dimension （3.） visualization, and apply its result to coastal urban planning, harbor site selection and geomorphology environment about coral reef and islands on the continental shelf. The case studies cover the whole coastal ocean to serve the social community, economical development and diplomatic rights for decision-making all round in the coastal zone. The research shows clearly that the application of coastal multi-source geospatial platform has changed the traditional coastal geomorphology science dramatically from its research scope, fields and methods, however, as made clear in this paper, extracting accurate information from remote sensing data and GIS databases for coastal geomorphological applications is a nontrivial challenge that requires the combined knowledge and skills of information scientists and geomorphologists.

关键词： coastal geomorphology geographic information system (GIS) spatial analysis threedimensional visualization

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RESEARCH ON THE BEST SLOPE GRADIENT OF SLOPE SOLAR INDUCED CONVECTIVE FLOWS POWER GENERATION SYSTEM

RESEARCH ON THE BEST SLOPE GRADIENT OF SLOPE SOLAR INDUCED C...

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2007世界太阳能大会：太阳能与人类居住

作者： Wei Jing Wang Fenghao school of human settlements and {3. xi’an jiaotong University xi ’an 710049 china Zhao Liang State Key Laboratory of Multiphase Flow in Power engineering xi’an jiaotong University xi ’an 710049 china

＜正＞Based On the monthly average solar radiation data from 1991 to 2000 year of china and the theory of the solar induced convective flows power generation,the feasibility of building slope solar induced convective flows power generation in west areas of china was analyzed and the gradient’s inflection on system power and efficiency was studied in this paper.A MATLAB code was compiled in this paper to get the best gradient of different *** the slope system was compared with horizontal system in performance under the same *** results show that the best gradient of the solar induced convective flows power generation is similar to the latitude;the slope collector can serve as a part of the chimney.

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基于机器学习的流域尺度森林火灾灾害风险预测

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自然灾害学报 2024年第1期33卷 89-98页

作者：郗婕傅微北京建筑大学建筑与城市规划学院北京100044

森林是碳库,具有强大的固碳增汇功能,在应对气候变化中发挥着重要作用。然而,由于极端高温的影响,频繁发生可燃物自燃而引发森林火灾,除了影响区域水文大气循环过程以外,也给人类带来严重的人员伤亡和经济损失。现有森林火灾预测研究主... 详细信息

森林是碳库,具有强大的固碳增汇功能,在应对气候变化中发挥着重要作用。然而,由于极端高温的影响,频繁发生可燃物自燃而引发森林火灾,除了影响区域水文大气循环过程以外,也给人类带来严重的人员伤亡和经济损失。现有森林火灾预测研究主要侧重可燃物研究和火灾监测等方面,较少关注大尺度地形、气象和人类活动对森林火灾的影响,但这些也是除可燃物外导致森林火灾发生的主要因素。以嘉陵江流域重庆段为研究区,区域内山地受自然火灾影响严峻。基于地理信息系统叠加地理空间因子与火灾分布点获得数据集,构建4种机器学习模型,测试模型性能,评价最优模型进行森林火灾灾害风险制图。研究结果表明,模型评估指标受试者工作曲线下面积(area under the curve,AUC)平均值为95.0%,模型性能梯度提升决策树最优,AUC值为98.3.。利用梯度提升决策树(gradient boosting decision tree,GBDT)模型预测森林火灾风险对防范大尺度森林火灾具有一定的可行性,对山城避灾规划起到借鉴作用,规划引导降低森林火灾风险,从而维护生态平衡和生态系统碳汇能力。

关键词：森林火灾机器学习梯度提升决策树灾害风险制图山城避灾规划

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自然资源资产基本法律属性阐释——兼及“环境法典”编纂中自然资源之立法

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湖南师范大学社会科学学报 2024年第1期53卷 48-56页

作者：屈茂辉陈希湖南大学法学院湖南长沙410082

自然资源既是环境、生态的重要组成部分,也是人类赖以生存和发展的重要物质来源。健全自然资源资产产权制度是生态文明建设、全面依法治国、国家治理体系和治理能力现代化的重要任务,其逻辑起点是厘清自然资源资产的基本法律属性。自然... 详细信息

自然资源既是环境、生态的重要组成部分,也是人类赖以生存和发展的重要物质来源。健全自然资源资产产权制度是生态文明建设、全面依法治国、国家治理体系和治理能力现代化的重要任务,其逻辑起点是厘清自然资源资产的基本法律属性。自然资源资产即资产性自然资源,虽然不是自然资源的全部但却是自然资源的本原存在。基于人类生存和发展对于自然资源的依存关系,自然资源资产的基本法律属性体现为三个递进式层次:其一为财产,其二为物,其三为不动产。凡属自然资源资产均为天然生成,对人类而言具有价值性、可支配性和稀缺性;之于文明社会而言,从维持人类生存的基本材料向创造社会财富的生产原料的转化,基于其自身的土地附生性乃成为不动产的基本形态。包括《民法典》在内的现行法律仍缺乏对自然资源资产基本法律属性的明确规定,未来可考虑编纂“环境法典”时,以自然资源作为环境、生态及资产的基本法律属性为依据,对自然资源资产的基本法律属性予以规定,以期有利于形成科学的自然资源资产法规范体系。

关键词：自然资源资产法律属性环境法典

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非规则平面形状和非均匀布桩桩筏基础的计算分析

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天津大学学报（自然科学与工程技术版） 2003年第3期36卷 342-346页

作者：张建辉邓安福周锡礽河北大学机械与建筑工程学院保定071002 重庆大学土木工程学院重庆400045 天津大学建筑工程学院天津300072

采用桩筏基础分析方法,针对六边形平面形状和非均匀布桩的桩筏基础工程实例进行非线性分析,得到了基础沉降、桩轴力、摩阻力和筏与桩的荷载分担比随施工进度的变化规律,在一定程度上揭示了桩与土的共同作用机理.同时,将沉降计算结果与... 详细信息

采用桩筏基础分析方法,针对六边形平面形状和非均匀布桩的桩筏基础工程实例进行非线性分析,得到了基础沉降、桩轴力、摩阻力和筏与桩的荷载分担比随施工进度的变化规律,在一定程度上揭示了桩与土的共同作用机理.同时,将沉降计算结果与现场观测数据进行比较,显示了较好的一致性,表明该计算结果是合理可靠的.

关键词：桩筏基础非规则平面形状非均匀布桩非线性分析基础沉降桩轴力摩阻力荷载分担比

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