31 research outputs found
Setting intelligent city tiling strategies for urban shading simulations
Assessing accurately the solar potential of all building surfaces in cities, including shading and multiple reflections between buildings, is essential for urban energy modelling. However, since the number of surface interactions and radiation exchanges increase exponentially with the scale of the district, innovative computational strategies are needed, some of which will be introduced in the present work. They should hold the best compromise between result accuracy and computational efficiency, i.e. computational time and memory requirements.
In this study, different approaches that may be used for the computation of urban solar irradiance in large areas are presented. Two concrete urban case studies of different densities have been used to compare and evaluate three different methods: the Perez Sky model, the Simplified Radiosity Algorithm and a new scene tiling method implemented in our urban simulation platform SimStadt, used for feasible estimations on a large scale. To quantify the influence of shading, the new concept of Urban Shading Ratio has been introduced and used for this evaluation process. In high density urban areas, this index may reach 60% for facades and 25% for roofs. Tiles of 500 m width and 200 m overlap are a minimum requirement in this case to compute solar irradiance with an acceptable accuracy. In medium density areas, tiles of 300 m width and 100 m overlap meet perfectly the accuracy requirements. In addition, the solar potential for various solar energy thresholds as well as the monthly variation of the Urban Shading Ratio have been quantified for both case studies, distinguishing between roofs and facades of different orientations
DEVELOPMENT OF THE CITYGML APPLICATION DOMAIN EXTENSION ENERGY FOR URBAN ENERGY SIMULATION
ABSTRACT No widely applicable open information model standard exists until now for large-scale Urban Energy Modelling. Although different data models have been developed for different urban energy tools, they do not offer possibilities of interoperability and exchange between the stakeholders, tools and expert fields. To address this issue, an international group of urban energy simulation developers and users is developing since May 2014 an Application Domain Extension (ADE) Energy for the open urban information model CityGML. This paper introduces the Energy ADE developed and tested by this international urban energy group. Goals, requirements and the modular structure of the CityGML extension are described in detail
CAGIRE: a wide-field NIR imager for the COLIBRI 1.3 meter robotic telescope
The use of high energy transients such as Gamma Ray Bursts (GRBs) as probes
of the distant universe relies on the close collaboration between space and
ground facilities. In this context, the Sino-French mission SVOM has been
designed to combine a space and a ground segment and to make the most of their
synergy. On the ground, the 1.3 meter robotic telescope COLIBRI, jointly
developed by France and Mexico, will quickly point the sources detected by the
space hard X-ray imager ECLAIRs, in order to detect and localise their
visible/NIR counterpart and alert large telescopes in minutes. COLIBRI is
equipped with two visible cameras, called DDRAGO-blue and DDRAGO-red, and an
infrared camera, called CAGIRE, designed for the study of high redshift GRBs
candidates. Being a low-noise NIR camera mounted at the focus of an
alt-azimutal robotic telescope imposes specific requirements on CAGIRE. We
describe here the main characteristics of the camera: its optical, mechanical
and electronics architecture, the ALFA detector, and the operation of the
camera on the telescope. The instrument description is completed by three
sections presenting the calibration strategy, an image simulator incorporating
known detector effects, and the automatic reduction software for the ramps
acquired by the detector. This paper aims at providing an overview of the
instrument before its installation on the telescope.Comment: Accepted by Experimental Astronom
Carte Archéologique de la Gaule, Pré-inventaire archéologique sous la direction de Michel Provost, La Vienne
International audienc
Carte Archéologique de la Gaule, Pré-inventaire archéologique sous la direction de Michel Provost, La Vienne
International audienc