Decreasing trends in total suspended solids and cumulative effects of nonpoint source projects in the Cuyahoga River Watershed,OH

Using the US EPA’s Grants Reporting and Tracking System (GRTS), we test if completion of best management practices (BMPs) through the Clean Water Act Section (4)319 National Nonpoint Source Program was associated with a decreasing trend in total suspended solids (TSS) load (metric tons/year). The study area chosen had 21 completed projects in the Cuyahoga River watershed in northeastern Ohio from 2000 to 2018. The 4319 projects ranged from dam removal, floodplain/wetland restoration to stormwater projects. There was an overall decreasing trend in TSS loads. We identified three phases of project implementation and completion, where phase 1 had ongoing projects, but none completed (2000–2004). The steepest decrease in loads, identified as phase 2 (2005–2011), was associated with completion of low-head dam modification and removal projects on the mainstem of the Cuyahoga River. A likely decreasing trend was associated with projects completed in the tributaries, such as natural channel design restoration and stormwater green infrastructure (phase 3). Pairing sediment reduction estimates from projects with the river’s flow normalized TSS loading trend, we estimated that the 4319 effort may account for a small fraction of the TSS load reduction. Other stream restoration projects (non-4319) have also been done in the Cuyahoga watershed by other organizations. However, trying to compile these other projects is challenging in larger watersheds having multiple municipalities, agencies, and nonprofits doing restoration without better coordinated record keeping and monitoring. While a decreasing trend in a pollutant load is a desirable water quality outcome, determining what contributed to that trend remains difficult.     

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。     

生产性服务业集聚研究综述

生产性服务业作为直接服务于工业生产的现代服务业,对促进我国经济结构调整具有重要意义。发达国家的发展历程已经证明,生产性服务业集聚已成为地区经济增长的重要引擎。本文从生产性服务业集聚形成机理、集聚的测度及影响因素等方面,对国内外生产性服务业集聚的相关研究成果进行梳理和评论。     

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。     

普适计算环境下基于情境的提醒服务自协调策略研究

由于老年人生理机能减退,针对老年人的提醒服务应用十分广泛.该类服务应考虑到老人的活动特征和环境特征才能提高服务效果,减少不必要的干扰.情境感知技术的发展为提醒服务的改进提供了契机,将情境引入到提醒服务的设计中,采用OWL本体方法构建领域内情境与服务知识的语义模型,以提醒服务平台的方式集成领域内提醒相关的设备与服务,并结合本体模型采用SWRL规则设计提醒服务的自协调策略,从而提高平台上不同提醒服务的自适应能力.通过模拟若干情境,采用Protégé和Pellet推理机验证了本体模型的正确性和协调规则的有效性.     

一种新的数字图书馆云服务用户满意度模型

随着云计算技术的发展,数字图书馆云服务评价成为迫切需要解决的问题.基于层次分析法(AHP),设计一种新的用户满意度模型评估数字图书馆云服务;为了从评估者角度获得测评指标的相对重要程度,提出一种新的AHP算法判断矩阵构造方式.实例表明:1)用户满意度模型能准确定位评估人员迫切需要改进的数字图书馆云服务; 2)改进的AHP算法能够从评估人员角度获得测评指标的权重值,有助于提高用户满意度的准确性.     

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.