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101.
Sustainable water management is a global challenge for the 21st century. One key aspect remains protection against urban flooding. The main objective is to ensure or maintain an adequate level of service for all inhabitants. However, level of service is still difficult to assess and the high-risk locations difficult to identify. In this article, we propose a methodology, which (i) allows water managers to measure the service provided by the urban drainage system with regard to protection against urban flooding; and (ii) helps stakeholders to determine effective strategies for improving the service provided. One key aspect of this work is to use a database of sewer flood event records to assess flood risk. Our methodology helps urban water managers to assess the risk of sewer flooding; this approach does not seek to predict flooding but rather to inform decision makers on the current level of risk and on actions which need to be taken to reduce the risk. This work is based on a comprehensive definition of risk, including territorial vulnerability and perceptions of urban water stakeholders. This paper presents the results and the methodological contributions from implementing the methodology on two case studies: the cities of Lyon and Mulhouse. 相似文献
102.
Streamflow Simulation by SWAT Using Different Precipitation Sources in Large Arid Basins with Scarce Raingauges 总被引:2,自引:1,他引:1
Meiyan Yu Xi Chen Lanhai Li Anming Bao Mupenzi Jean de la Paix 《Water Resources Management》2011,25(11):2669-2681
Streamflow from the mountains is the main source of water for the lower plain in arid regions. Accurate simulation of streamflow
is of great importance to the arid ecosystem. However, many large arid drainage basins in northwestern China have low density
of precipitation stations, which makes the streamflow modeling and prediction very difficult. Based on raingauge data and
Tropical Rainfall Measuring Mission (TRMM) data combined with raingauge data, different approaches were explored for spatializing
precipitation in large area with scarce raingauges. Spatialized precipitation was then input into Soil and Water Assessment
Tool (SWAT), a semi-distributed hydrological model, to simulate streamflow. Results from a case study in the Manas river basin
showed that simulated hydrographs using both the approaches are able to reproduce the watershed hydrological behavior. Moreover,
statistical assessment indicated that hydrological model driven by the spatialized precipitation based on radar combined with
raingauge data performed better than that based on gauge data. Radar precipitation estimator can provide a practical data
source for hydrological modeling at a basin scale where the raingauge network is sparse. 相似文献
103.
Juan Manuel González Calleros Josefina Guerrero García Jean Vanderdonckt 《Universal Access in the Information Society》2013,12(4):387-401
The need for accessibility evaluation tools is motivated by several endogenous and exogenous reasons coming from the end user (the designer and the developer) and companies releasing information systems. Existing evaluation tools mainly concentrate on examining the code of Web pages: Web pages more and more frequently contain non-HTML parts that entirely escape from being treated by existing techniques. This is the case of the advanced human–machine interface (AHMI), a piece of software programmed in C/C++, used for controlling the advanced flight management system in the aircraft cockpit. Studying this new user interface (UI) requires a structured approach to evaluate and validate AHMI designs. The goal in this work is to develop an evaluation tool to automate the process of evaluating the AHMI. The method addresses: support of multiple bases of guidelines (accessibility or usability or both) on-demand (partial or total evaluation), with different levels of details (a presentation for developers and for those responsible for certifying accessibility). The method goes a step toward the automatic evaluation of UI containing non-HTML parts. 相似文献
104.
The Sanaga River is one of Sub‐Saharan Africa's largest and greatly regulated rivers. Available flow data for this hydrosystem largely cover the pre‐ and post‐regulation periods. From comparisons between unregulated (hypothetical) and observed scenarios, it has been possible to separate and to quantify hydro‐climatic (groundwater + rainfall) change effects from anthropogenic impacts (especially dam‐related alterations). To appreciate shifts in the river regime, discontinuity detection tests and the IHA model were applied to discharge data series reflecting average and extreme flow conditions, respectively. Results obtained principally from the Hubert segmentation method reveal that a major discontinuity occurred in 1970–1971 separating a surplus phase between 1945–1946 and 1969–1970, and a deficient and much contrasted one, from 1971/1972. This implies that the Sanaga catchment is dominantly affected by hydro‐climatic changes. However, wide land cover/land use changes experienced here since 1988 have resulted in an increase in surface runoff. Additional quickflows linked to these changes may have partly compensated for the substantial decline in the dry season rainfall and groundwater inputs observed from this date. Although at the monthly scale, dam‐related impacts on average flows increase with stage of regulation, the seasonal variability of the river regime remains generally unaffected. A comparison of the IHA statistics, calculated from unregulated and observed streamflow data, show that hydrologic shifts occurring in maximum and minimum discharges are mostly significant from 1971/1972 and are mainly due to the action of dams. Minimum flows appear, however, widely impacted, thus reflecting the prime objective assigned to the existing reservoirs, constructed to supplement flows for hydroelectricity production during the dry season. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
105.
Estimation of soil clay and calcium carbonate using laboratory, field and airborne hyperspectral measurements 总被引:2,自引:0,他引:2
Philippe Lagacherie Frédéric Baret José Madeira Netto Jean Marc Robbez-Masson 《Remote sensing of environment》2008,112(3):825-835
This paper examines how reflectance spectrometry used in the laboratory to estimate clay and calcium carbonate (CaCO3) soil contents can be applied to field and airborne measurements for soil property mapping. A continuum removal (CR) technique quantifying specific absorption features of clay (2206 nm) and CaCO3 (2341 nm) was applied to laboratory, field and airborne HYMAP reflectance measurements collected in 2003 (33 sites) and 2005 (19 sites) over bare soil sites of a few meters within the La Peyne Valley area, southern France. Nine intermediate stages from the laboratory up to HYMAP sensor measurements were considered for separately evaluating the possible degradation of estimation performances when going across scales and sensors, e.g. radiometric calibration, spectral resolution, spatial variability, illumination conditions, and surface status including roughness, soil moisture and presence and nature of pebbles.Significant relationships were observed between clay and CaCO3 contents and CR values computed respectively at 2206 nm and 2341 nm from reflectance measurements at the laboratory level with an ASD spectrophotometer up to the HYMAP spectro-imaging sensor. Performances of clay and CaCO3 estimations decreased from the laboratory to airborne scales. The main factors inducing uncertainties in the estimates were radiometric and wavelength calibration uncertainties of the HYMAP sensor as well as possible residual atmospheric effects. 相似文献
106.
Recent progress in modelling, animation and rendering means that rich, high fidelity virtual worlds are found in many interactive graphics applications. However, the viewer's experience of a 3D world is dependent on the nature of the virtual cinematography, in particular, the camera position, orientation and motion in relation to the elements of the scene and the action. Camera control encompasses viewpoint computation, motion planning and editing. We present a range of computer graphics applications and draw on insights from cinematographic practice in identifying their different requirements with regard to camera control. The nature of the camera control problem varies depending on these requirements, which range from augmented manual control (semi‐automatic) in interactive applications, to fully automated approaches. We review the full range of solution techniques from constraint‐based to optimization‐based approaches, and conclude with an examination of occlusion management and expressiveness in the context of declarative approaches to camera control. 相似文献
107.
Marcelo Siqueira Longin Jan Latecki Nicholas Tustison Jean Gallier James Gee 《Journal of Mathematical Imaging and Vision》2008,30(3):249-274
We present here a new randomized algorithm for repairing the topology of objects represented by 3D binary digital images.
By “repairing the topology”, we mean a systematic way of modifying a given binary image in order to produce a similar binary
image which is guaranteed to be well-composed. A 3D binary digital image is said to be well-composed if, and only if, the square faces shared by background and foreground
voxels form a 2D manifold. Well-composed images enjoy some special properties which can make such images very desirable in
practical applications. For instance, well-known algorithms for extracting surfaces from and thinning binary images can be
simplified and optimized for speed if the input image is assumed to be well-composed. Furthermore, some algorithms for computing
surface curvature and extracting adaptive triangulated surfaces, directly from the binary data, can only be applied to well-composed
images. Finally, we introduce an extension of the aforementioned algorithm to repairing 3D digital multivalued images. Such
an algorithm finds application in repairing segmented images resulting from multi-object segmentations of other 3D digital
multivalued images.
相似文献
James GeeEmail: |
108.
It has been argued that blogs, as an extension of 1960s 'New Journalism,' have become an important form of alternative media. At their idealized best, blogs can report news without the constraints of censure or the pressures of advertising. This argument suggests that blogs can therefore offer a deeper analysis, based upon a diverse range of sources and contributing citizen commentators, which is not possible through modern corporate, mainstream outlets. This exploratory study uses both critical discourse and content analysis to examine 344 posts, 1,712 hyperlinks, and 10,401 comments from 4 political/current events blogs within a 7-day period. This research argues that previous conceptualizations of alternative media, at least in relation to the political/current events blogosphere, might need reconsideration. 相似文献
109.
This paper addresses the optimal disturbance attenuation problem by output feedback for multivariable linear systems with delayed inputs. The attenuation is optimal in the sense that the controller minimizes the maximal amplitude of the plant output in response to such a disturbance. The controller is a general feedback, involving an observer, a state predictor, and a predicted state feedback. The optimal disturbance attenuation problem is formulated in terms of an equivalent system without delay. The optimal bound of the disturbance attenuation is then characterized, and it is shown that the optimal controller tends to have high gains. A necessary and sufficient condition to guarantee the existence of an optimal solution is provided using the geometric approach. 相似文献
110.
When European laboratories decided to develop a digital sound broadcasting system (DSB), they specified three main conditions to fulfil:
- quality improvement up to the level of ‘CD’ sound, even in difficult reception conditions (mobile vehicles, etc)
- additional significant digital data transmissions in order to transform sound broadcasting into a really new service
- the possibility of a common system for satellite and terrestrial transmissions.