An inexpensive instrument for measuring benthic current velocity and direction at sea     

J. R. Craig  S. J. Kennelly 《Estuarine, Coastal and Shelf Science》1991,32(6)

An instrument which measures the velocity and direction of benthic water currents at depths of up to 80 m is described. Characteristics of this meter include: (i) readings are not affected by water flow during sinking or retrieval; (ii) it is portable; (iii) it operates unattended; (iv) it is inexpensive; and (v) it requires only simple maintenance. A timing circuit which operates two time periods in succession is used to activate and de-activate a revolution counter and a fluidfilled compass which are mounted on a special frame and vane system. In the field, the instrument accurately measured average current velocities of up to 6 m s⁻¹. Data are presented which illustrate the usefulness of this instrument in describing the velocity and direction of benthic currents along the east coast of Australia and demonstrate a positive correlation between benthic current velocity and catch rates of the commercially-exploited spanner crab Ranina ranina.  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   

基于倾斜摄影测量技术的高原地区三维城市建模研究     

陈兴芳  马明霞  张海欢  常慧  刘宇航 《测绘与空间地理信息》2016,(8):149-152

为建设"数字西宁"地理信息公共平台,本文利用AMC580多视角航空摄影仪的倾斜摄影技术和Smart3DCapture软件为数据处理平台,以高原城市西宁市实景真三维模型数据生产为例介绍了数据生产过程及其应用领域。结果表明,用倾斜摄影的方法能高效、高质量地实现实景真三维数据生产。倾斜摄影技术不仅从多个角度采集地面影像,从而克服了传统航空摄影技术只能从垂直角度进行拍摄的局限;倾斜摄影建立三维模型技术相对于传统的三维建模方法而言,凸显其建模速度快、成本低等优势;且所获取的真实、详细、丰富的地物信息,更符合人眼视觉习惯的真实且直观的世界。  相似文献   

降水现象仪观测应用评估   总被引：1，自引：0，他引：1  

杜传耀  尹佳莉  李林  伍永学  姜涛 《气象》2019,45(5):730-737

利用2017年9月至2018年8月北京20个站降水现象仪采集数据与人工平行观测数据,对降水现象仪进行了对比评估。结果表明:降水现象仪的缺测率为0.01%,空报率为0.6%,捕获率为93.5%,漏报率为27.9%,错报率为10.0%。从统计结果可知,降水现象仪的缺测率、空报率较低,捕获率较高,体现出设备性能良好的一面,漏报率和错报率偏高,表明设备漏识别和错误识别的情况较多,漏报主要发生在弱降水过程中,错报主要出现在毛毛雨的识别上。设备测量和人工观测降水开始时间一致性较好,终止时间一致性偏差;降水现象仪现存问题:在大雨强时易出现雨滴叠加误识别,在小雨强时识别率会降低,在无降水错误输出降水现象方面缺少质控。  相似文献   

A high-precision heuristic model to detect home and work locations from smart card data     

Nilufer Sari Aslam  Tao Cheng  James Cheshire 《地球空间信息科学学报》2019,22(1):1-11

Smart card-automated fare collection systems now routinely record large volumes of data comprising the origins and destinations of travelers. Processing and analyzing these data open new opportunities in urban modeling and travel behavior research. This study seeks to develop an accurate framework for the study of urban mobility from smart card data by developing a heuristic primary location model to identify the home and work locations. The model uses journey counts as an indicator of usage regularity, visit-frequency to identify activity locations for regular commuters, and stay-time for the classification of work and home locations and activities. London is taken as a case study, and the model results were validated against survey data from the London Travel Demand Survey and volunteer survey. Results demonstrate that the proposed model is able to detect meaningful home and work places with high precision. This study offers a new and cost-effective approach to travel behavior and demand research.  相似文献   

Calibration and use of continuous heat-type automated seepage meters for submarine groundwater discharge measurements     

B.M. Mwashote  W.C. Burnett  J. Chanton  I.R. Santos  N. Dimova  P.W. Swarzenski 《Estuarine, Coastal and Shelf Science》2010

Submarine groundwater discharge (SGD) assessments were conducted both in the laboratory and at a field site in the northeastern Gulf of Mexico, using a continuous heat-type automated seepage meter (seepmeter). The functioning of the seepmeter is based on measurements of a temperature gradient in the water between downstream and upstream positions in its flow pipe. The device has the potential of providing long-term, high-resolution measurements of SGD. Using a simple inexpensive laboratory set-up, we have shown that connecting an extension cable to the seepmeter has a negligible effect on its measuring capability. Similarly, the observed influence of very low temperature (≤3 °C) on seepmeter measurements can be accounted for by conducting calibrations at such temperatures prior to field deployments. Compared to manual volumetric measurements, calibration experiments showed that at higher water flow rates (>28 cm day⁻¹ or cm³ cm⁻² day⁻¹) an analog flowmeter overestimated flow rates by ≥7%. This was apparently due to flow resistance, turbulence and formation of air bubbles in the seepmeter water flow tubes. Salinity had no significant effect on the performance of the seepmeter. Calibration results from fresh water and sea water showed close agreement at a 95% confidence level significance between the data sets from the two media (R² = 0.98). Comparatively, the seepmeter SGD measurements provided data that are comparable to manually-operated seepage meters, the radon geochemical tracer approach, and an electromagnetic (EM) seepage meter.  相似文献   

Optimal Forward-Scattering Angles of Atmospheric Aerosols in North China          下载免费PDF全文

JIA Sheng-Jie  Lü Da-Ren 《大气和海洋科学快报》2014,(3):236-242

The accurate understanding of atmospheric aerosol extinction coefficients is very important for at- mospheric science research. To achieve a fast and simple method for determining the parameters, the selection of optimal forward-scattering angles of atmospheric aerosols is required. In this paper, the authors introduce the detec- tion basis of forward-scattering of atmospheric aerosols, and the authors verify the sensitivity of the phase function to the real part of the complex refractive index. The au- thors use the Jaenicke urban aerosol model to determine that forward-scattering angles near 33° are suitable. However, the optimal forward-scattering angles in North China are between 37° and 40°. Numerical simulation shows that certain types of particle size distribution of newly generated particles and pollution have limited in- fluences on the selection of forward-scattering angles. But the ranges of these insensitive angles shift - 10 degrees for dust intrusion, and the relative deviations of the phase function are less than 5.0% within extra angles of 0° to 3°. This study can serve as a reference for the selection of optimal forward-scattering angles for visibility meters and Present Weather Identifiers （PWIs） in addition to the de- tection of forward-scattering optical properties.  相似文献   

地市级地理信息共享服务平台设计     

杜福光 《测绘工程》2014,23(11):51-55

随着社会经济与信息技术的不断发展,地市级智慧城市建设提上日程,如何建立一套规范统一而又具有通用性的地理信息共享服务平台是其关键.平台建设必须考虑三方面内容,即建设内容、运维机制与具体应用.在智慧唐山建设过程中,以面向服务为目标,顾及地市级地理信息共享服务平台的通用性,针对总体需求、总体架构、关键技术等方面进行设计,明确地理信息共享服务平台建设的内容、运维机制建设以及示范应用等内容,探讨适用于地市级智慧城市地理信息共享服务平台构建的解决方案.  相似文献   

感知校园服务平台的设计与实现     

黄露  谢忠  罗显刚 《测绘科学》2015,(9):69-73

为了进一步探索"感知校园"建设为师生带来的便利服务,该文以物联网、GIS、SOA、三维展示等技术为基础,以MapGIS K9为基础支撑平台,设计了一种感知校园服务平台。该平台面向广大师生,支持Web客户端和移动终端两大类终端设备,集虚拟校园服务、校园导航服务、校园视频监控、客流统计分析、校园活动等功能为一体,实现了学习、工作、管理和生活等信息的较全面感知,为师生的校园生活提供了一个便捷的信息感知、查询与交互的感知服务平台,为建设智慧校园提供参考。  相似文献   

Testing smarter control and feedback with users: Time,temperature and space in household heating preferences and practices in a Living Laboratory     

《Global Environmental Change》2020

Transitioning to more efficient and less carbon-intensive heating is a monumental policy challenge in the United Kingdom. However, very few households in the UK—and perhaps even elsewhere—have actual experience with state-of-the-art smart heating systems that may utilize enhanced control or feedback. Drawing from a unique sample of actual adopters of smart heating, this study closely examines the heating preferences, practices, and profiles of homes when they are given smarter heating systems. The study utilizes qualitative household data from the Energy System Catapult’s Living Laboratory of 100 smart homes in Birmingham (West Midlands), Bridgend (Wales), Manchester (Greater Manchester), and Newcastle (Northumberland). We examine the heating preferences and profiles of participants, with findings inductively organized around the themes of temperature, including tradeoffs between comfort, cost, and value; time, including the utility of heat scheduling; and space, including zonal heating controls. We also discuss patterns of learning, the emergence of environmental values, and issues of discomfort. We conclude by commenting on important distinctions between radiant and ambient heat, as well as between scheduled and on-demand heat. The main findings are 1) tradeoffs between comfort, value and cost occur when it comes to smart heating; 2) people want different numbers of warm hours in their homes at very different times; 3) households chose to heat different numbers of rooms; and 4) there are other non-monetary and non-functional aspects of smart heating that households value.  相似文献