基于2030可持续发展目标的珠三角土地消耗率与人口增长率协调关系评价

量化联合国可持续发展目标SDG 11.3.1“土地消耗率与人口增长率的比率（LCRPGR）”有助于了解城市扩张与人口增长之间的关系,为城市国土空间规划和人口城镇化调控提供数据支撑,并且对指导决策者制定城市增长计划至关重要。基于土地利用产品、夜间灯光数据和人口普查数据,提取了城市建成区,利用地理加权回归模型测算了珠三角地区1 km×1 km格网尺度人口密度。依据SDG 11.3.1指标元数据中定义和公式,对珠三角地区可持续发展进行了可靠评价。结果显示：①1990~2010年珠三角建成区面积扩张4.6倍,城区人口增长3.7倍;②1990~2010年珠三角的LCRPGR值由0.71增长到2.01;城市扩张速度与人口增长速度并非是成比例协调增长关系;③建成区的扩张主要是由耕地和农村居民用地转换而来。综上,自2000年后珠三角地区土地消耗率已经超过人口增长率,城市扩张速度与人口增长速度并非是成比例协调增长关系,二者的差异在增大,应当引起一定注意。     

海绵城市建设的径流控制指标探析

城市化引起的诸多水生态、水环境及洪灾问题均与天然水文条件的破坏紧密相关;水文控制指标是海绵城市建设中的关键控制指标。在调研国际城市雨洪管理的演变及目前城市水文控制指标发展趋势的基础上,提出海绵城市建设所必需的水文控制指标体系概念。该体系包括维持河湖湿地基流与地下水补给的入渗控制指标,减少雨洪面源污染的水质控制指标,防止河道侵蚀的水土侵蚀控制指标,以及避免小量级洪涝和减轻极端洪涝灾害的洪水控制指标。在此基础上,分析了我国在海绵城市建设中缺乏完整水文控制指标体系的现状,并提出了我国目前在建立城市雨洪管理水文控制指标工作中亟待开展的工作,为海绵城市建设中合理确定适合各地具体条件的水文控制指标体系提供研究思路与参考。     

基于Landsat 8影像和能量平衡的西安市热场格局研究!

基于2014年8月15日的Landsat 8影像,通过劈窗算法反演西安中心城区地表温度,定量测算热岛中心范围。估算多种地表能量分量,分析热环境格局与地表能量分量的关系。结果表明:(1)西安中心城区城市热岛集中分布在人口、居住、商业密集区、经济技术开发区以及植被覆盖较差的区域;(2)感热、波文比与地表温度呈正相关,人为热与温度呈不显著正相关,净辐射、潜热与地表温度呈显著负相关;(3)城市热岛的地表能量结构中感热与潜热差异是构成城市热岛差异的主要原因。     

Urban Social Media Demographics: An Exploration of Twitter Use in Major American Cities

This article explores intersections between place, race/ethnicity, and gender amongst American Twitter users and makes an argument that studying the intensity of tweets provides insights into how and why particular groups tweet. Given recent events in American political life such as the shooting in Ferguson, Missouri and the reactions by young, urban African Americans on Twitter, understanding the role of race, place, gender, and age is important. We observed the time between tweets of urban American Twitter users and explored whether the medium may be providing traditionally marginalized groups, such as young Black men, with potential avenues for mobilizing communication and access to resources.     

城市集中供热中计算机监控技术的有效应用

本文主要介绍了在远程操作当中,计算机监控技术所发挥的作用,丹佛斯变频器主要对循环水泵和补水泵进行控制,采用摄像机监控主要设备以及周边环境的安全,再利用光纤将视频信号传输到监控管理中心。采用这种系统组装,大大降低了供暖的成本,创造了很大的经济整益,有非常大的实用价值。     

Detailed Real-Time Urban 3D Reconstruction from Video

The paper presents a system for automatic, geo-registered, real-time 3D reconstruction from video of urban scenes. The system collects video streams, as well as GPS and inertia measurements in order to place the reconstructed models in geo-registered coordinates. It is designed using current state of the art real-time modules for all processing steps. It employs commodity graphics hardware and standard CPU’s to achieve real-time performance. We present the main considerations in designing the system and the steps of the processing pipeline. Our system extends existing algorithms to meet the robustness and variability necessary to operate out of the lab. To account for the large dynamic range of outdoor videos the processing pipeline estimates global camera gain changes in the feature tracking stage and efficiently compensates for these in stereo estimation without impacting the real-time performance. The required accuracy for many applications is achieved with a two-step stereo reconstruction process exploiting the redundancy across frames. We show results on real video sequences comprising hundreds of thousands of frames.     

基于多类别支持向量机的城市交通网络模式分类研究

在网络层次上进行区域交通信号控制、交通分配和路径诱导是缓解交通堵塞的有效途径之一。为进一步提高城市交通网络分类检测的准确性,将支持向量机（Support Vector Machine）应用于交通事件的模式分类研究。通过提出一种基于多类别支持向量机的交通模式分类方法,设计了适合该检测系统的网络结构。仿真结果表明：相对于其他算法,城市交通网络的状态可分为数量有限且不同类型的模式,并且这些模式不断重复出现,当系统识别出网络处于某种模式时,就可参照事先确定的优化参数及策略进行交通控制和诱导,以缓解交通拥塞,提高交通系统的运行效率。该网络结构对于小样本数据具有检测率高、误报率低的优点,完全适用于城市交通的模式分类,同时也存在不足之处,指出了今后进一步研究的方向。     

An economic input-output analysis for urban stormwater quality planning

A new approach using input-output techniques is proposed for the analysis of urban stormwater pollution caused by urban land development. The input-output model provides projections of sectoral outputs within an urban region. By defining land as an input to production, these output projections may be translated into projections of commercial and industrial land development. Furthermore, the closed version of the input-output model is used to project residential land development as a function of projected wage income. The pollutant generation in urban stormwater is related to the quantity of each category of land development by a pollutant coefficient matrix. Thus, the model can be used to predict the impact of various economic growth scenarios on pollution loadings in runoff water. This will help planners in assessing the environmental costs of various scenarios, and in preparing for remedial actions. A numerical example is provided to illustrate the applications of the model.     

Effects of parallelogram-shaped pavement markings on vehicle speed and safety of pedestrian crosswalks on urban roads in China

The primary objective of this study was to evaluate the effects of parallelogram-shaped pavement markings on vehicle speed and crashes in the vicinity of urban pedestrian crosswalks. The research team measured speed data at twelve sites, and crash data at eleven sites. Observational cross-sectional studies were conducted to identify if the effects of parallelogram-shaped pavement markings on vehicle speeds and speed violations were statistically significant. The results showed that parallelogram-shaped pavement markings significantly reduced vehicle speeds and speed violations in the vicinity of pedestrian crosswalks. More specifically, the speed reduction effects varied from 1.89 km/h to 4.41 km/h with an average of 3.79 km/h. The reduction in the 85th percentile speed varied from 0.81 km/h to 5.34 km/h with an average of 4.19 km/h. Odds ratios (OR) showed that the parallelogram-shaped pavement markings had effects of a 7.1% reduction in the mean speed and a 6.9% reduction in the 85th percentile speed at the pedestrian crosswalks. The reduction of proportion of drivers exceeding the speed limit varied from 8.64% to 14.15% with an average of 11.03%. The results of the crash data analysis suggested that the use of parallelogram-shaped pavement markings reduced both the frequency and severity of crashes at pedestrian crosswalks. The parallelogram-shaped pavement markings had a significant effect on reducing the vehicle–pedestrian crashes. Two crash prediction models were developed for vehicle–pedestrian crashes and rear-end crashes. According to the crash models, the presence of parallelogram-shaped pavement markings reduced vehicle–pedestrian crashes at pedestrian crosswalks by 24.87% with a 95% confidence interval of [10.06–30.78%]. However, the model results also showed that the presence of parallelogram-shaped pavement markings increased rear-end crashes at pedestrian crosswalks by 5.4% with a 95% confidence interval of [0–11.2%].     

A hybrid approach based on SERVQUAL and fuzzy TOPSIS for evaluating transportation service quality

Managing service quality is vital to retain customer satisfaction and augment revenues for any business organization. Often it is difficult to assess service quality due to lack of quantifiable measures and limited data. In this paper, we present a hybrid approach based on SERVQUAL and fuzzy TOPSIS for evaluating service quality of urban transportation systems. The proposed approach consists of three steps. The first step involves development of a SERVQUAL based questionnaire to collect data for measuring transportation service quality. The participants provide linguistic assessments to rate the service quality criteria and the alternatives. In step 2, the linguistic ratings are combined through fuzzy TOPSIS to generate an overall performance score for each alternative. The alternative with the highest score is finally chosen. In step 3, sensitivity analysis is conducted to evaluate the influence of criteria weights on the decision making process.The strength of the proposed approach is its practical applicability and ability to provide solution under partial or lack of quantitative information. An application of the proposed approach for evaluation of service quality of metro in Montreal is provided.