城市街道峡谷汽车尾气污染的数值模拟

建立了一个简单的三维街道峡谷空气污染模式,并用实测资料进行了验证。利用建立的模式设计了7种试验方案,对街道峡谷内的污染状况进行了模拟。以CO为模拟对象的数值试验结果表明,街道峡谷上空的风速风向条件是决定街道峡谷内的污染状况的重要因素。峡谷上空风向与街道轴线的夹角越大、风速越小,则街道地面CO浓度越高。以现有的兰州典型车流量和排放因子,兰州街道地面CO浓度容易超标;若不控制车流量,到2008年,即使兰州上路汽车排放达标,但街道地面CO浓度仍然容易超标。     

GPS/MEMS INS integrated system for navigation in urban areas

This paper evaluates the performance of a tightly coupled GPS/INS integrated system based on low cost MEMS IMUs in dense urban areas, and investigates two different methods to improve its performance. The first method used is to derive observations from two different constraint equations reflecting the behavior of a typical land vehicle. The first constraint equation is derived assuming that the vehicle does not slip and always remains in contact with the ground. If these assumptions are true the velocity of the vehicle in the plane perpendicular to the forward direction should be zero. The second constraint equation is derived from the fact that the height does not change much in a short time interval in a land vehicular environment. Thus, when a GPS outage occurs (partial/complete), the integrated system combines the INS and constraints-derived virtual measurements to keep the position and velocity errors bounded. This method is suitable for use in real-time applications. The second method is specifically suitable for a post-mission application and involves the use of Rauch-Tung-Striebel (RTS) smoother. The designed system performance is evaluated using two data sets collected in dense urban areas. The obtained results demonstrate the effectiveness of different algorithms considered, in controlling the INS error growth, and indicates the potential of MEMS IMUs for use in land vehicle navigation applications.     

路灯AM/FM/GIS建设研究

通过对AM/FM/GIS的研究 ,结合路灯行业实际情况 ,指出了路灯行业AM/FM/GIS建设的必要性。构建了路灯AM/FM/GIS系统的体系结构和路灯AM/FM/GIS功能框架 ,并提出路灯AM/FM/GIS系统建设的合理建议     

Spatial conjunctive analysis of (crime) case configurations: Using Monte Carlo methods for significance testing

While research has repeatedly demonstrated how spatial distributions of crime can be shaped by the presence of facilities such as bars and public transport hubs, the joint influence of different facility types has rarely been explored. Spatial conjunctive analysis of case configurations (also known as qualitative comparative analysis) offers a means to identify the combinations of facility types that are most commonly found around crime events, and has been used in a small number of studies focusing on street robbery. This study extends this limited evidence base by implementing a significance test based on the Monte Carlo method using street robbery data for Austin, Texas. The results show that some of the top-ranking facility type combinations had observed frequencies that were not significantly greater than chance expectations. The accurate identification of the highest-risk environments has important implications for crime prevention.     

基于GIS的社区居民避震疏散区划方法及应用研究

在快速城市化和地震灾害频发的背景下,灾前人群紧急疏散区划成为防灾减灾规划研究的重要课题。结合当前城市应急疏散设施布局现状,立足于社区夜间避震疏散需求,综合运用GIS空间分析技术,从应急疏散需求分布、疏散空间可达性、疏散优化归属3方面逐步构建居民避震疏散区划方法,并选择上海市内人群和建筑相对密集的陆家嘴街道为对象开展实证研究。从而为城市防震减灾规划的避难设施优化布局和应急疏散预案编制提供科学适用的技术手段。     

旅游开发影响下民族社区文化记忆的代际传承——以西安回民街历史文化街区为例

在旅游开发背景下,目的地社区文化记忆的代际延续与传承对居民的地方认同具有重要意义.本文借助文化记忆媒介的理论框架,依托23位本地居民的深度访谈,探究旅游影响下代际间记忆传承的时空媒介信息与延续性要素.研究发现:①在旅游开发影响下,虽然新一代与老一代居民在文化记忆空间的认知与表述上存在差异性,但记忆媒介在旅游发展中的保留...     

白云凹陷陆坡峡谷沉积与迁移特征及其对天然气水合物成藏的影响

利用高分辨率地震资料,研究了南海北部白云凹陷中新世以来的陆坡峡谷沉积和迁移特征及其对动态似海底反射（BSR）的影响。白云凹陷陆坡区浊流和底流共同作用形成了大型单向迁移峡谷沉积体系。峡谷的沉积过程包括侵蚀为主阶段、侵蚀-沉积共同作用阶段及沉积为主阶段。峡谷沉积相主要包括峡谷侵蚀基底、谷底沉积、谷内滑塌块体搬运沉积及侧向倾斜沉积层等4个单元。峡谷的迁移造成含天然气水合物脊部两侧不同的侵蚀-沉积环境,因此,脊部两侧BSR反射特征也不同。随着峡谷迁移的进行,在峡谷侵蚀侧翼处,沉积物被侵蚀,天然气水合物稳定带底界将发生下移,BSR反射特征为多轴较连续反射;而峡谷沉积侧翼处,沉积物增厚,天然气水合物稳定带将发生上移,BSR反射特征为单轴连续反射。     

Street profile analysis: A new method for mapping crime on major roadways

Street profile analysis is a new method for analyzing temporal and spatial crime patterns along major roadways in metropolitan areas. This crime mapping technique allows for the identification of crime patterns along these street segments. These are linear spaces where aggregate crime patterns merge with crime attractors/generators and human movement to demonstrate how directionality is embedded in city infrastructures. Visually presenting the interplay between these criminological concepts and land use can improve police crime management strategies. This research presents how this crime mapping technique can be applied to a major roadway in Burnaby, Canada. This technique is contrasted with other crime mapping methods to demonstrate the utility of this approach when analyzing the rate and velocity of crime patterns overtime and in space.     

基于倾斜摄影的实景三维单体化模型构建方法

倾斜摄影实景三维模型是由连续的三角网通过纹理贴图组成,模型上各地理要素具有\"一张皮\"的特点.针对无法管理与编辑模型上各地理对象的问题,本文提出了基于倾斜摄影实景模型进行单体化建模的技术方法.首先,利用倾斜航空摄影技术,探讨了基于Street Factory实景三维模型全自动构建方法;然后,以生成的实景三维模型为基础,利...     

沈阳市街道灰尘中重金属的环境影响与健康风险评价

采集中国沈阳市区主要交通干道街道灰尘样品,在对其重金属Cd、Cu、Pb和Zn环境影响分析的基础上,应用美国EPA人体暴露风险评估方法对街道灰尘重金属的健康风险进行评估。结果表明,手-口接触行为是人体(儿童和成人)摄入街道灰尘重金属的最主要途径,其次为皮肤吸收和呼吸吸入。重金属对人体的非致癌风险表现为：Pb大于Cd大于Cu大于Zn,均小于非致癌风险阈值1,对人体不会造成健康危害,且儿童的非致癌风险大于成人。重金属Cd目前尚未形成致癌风险,但其对儿童的潜在生态危害值得重视。