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Modelling nutrient fluxes from sub-arctic basins: Comparison of pristine vs. dammed rivers 总被引:1,自引:0,他引:1
Agata Sferratore Gilles Billen Josette Garnier Erik Smedberg Christoph Humborg Lars Rahm 《Journal of Marine Systems》2008,73(3-4):236
The deterministic Riverstrahler model of river functioning is applied for the first time to sub-arctic catchments. Seasonal nutrient (N, P, Si) deliveries to the coastal zone are simulated, and nutrient annual fluxes are established for the nearly pristine river Kalix (hereafter called Kalixälven) and the heavily dammed river Lule, (hereafter called Luleälven) both located in Northern Sweden and draining into the Bothnian Bay, Baltic Sea.For Kalixälven simulations are performed with a runoff calculated from precipitation, evapo-transpiration and temperature data for the period 1990–1999, using a hydrological model calibrated on observed monthly discharges at the river outlet. The same hydrological parameters are used to calculate specific runoff for the Luleälven basin in absence of dam regulation. Reservoir filling and emptying are simulated using a simplified representation of their management rules. Diffuse sources of nutrient are evaluated according to land cover of the catchment. The simulated seasonal trends are within the range of the observed data, in particular for discharge, dissolved silica, total phosphorus, inorganic nitrogen and total organic carbon. Specific runoff is 50% higher in the Luleälven than in the Kalixälven watershed due to higher altitudes and precipitations. Average silica, nitrate and phosphorus concentrations are much lower in Luleälven than in Kalixälven. Comparison of model results for the Luleälven with and without dams shows a reduction of respectively 25% and 30% in silica and phosphorus fluxes delivered at the outlet, while nitrogen delivery is increased by 10% in the dammed vs. undammed river system. The model allows assessing the respective role of reservoir trapping of nutrient in the reservoir through algal uptake and sedimentation, and of changes in the vegetation induced by flooding the valley formerly covered by forests and wetlands. 相似文献
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Motion Cueing in the Renault Driving Simulator 总被引:5,自引:0,他引:5
Gilles Reymond Andras Kemeny 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2000,34(4):249-259
Motion cueing in a driving simulator is necessary for advanced studies requiring drivers to accurately perceive and control the motion of their vehicle. The Renault Dynamic Simulator uses a 6-axes electro-mechanical mobile platform with an adequate motion control software. The physical and perceptual validity of the motion cueing is analyzed with respect to actual vehicle acceleration data and human self-motion per-ception criteria. Within the actuator displacement limits, it is capable of directly rendering transient vehicle accelerations whereas sustained linear acceleration cues are simulated by a coordinated platform tilt. Accel-eration transients are extracted by high-pass filtering, but a classical implementation based on linear filters may produce artifacts in some key driving situations. A non-linear motion cueing algorithm was developed to anticipate and reduce these false motion cues. 相似文献
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François MirabelMathias Reymond 《Transportation Research Part A: Policy and Practice》2011,45(1):18-30
The paper examines the question of the redistribution of toll revenue as seen in a bottleneck congestion model. Our objective is to analyse the impact of this redistribution on total cost and on modal split between railroad and road. Following Tabuchi’s two-mode model (Tabuchi, T., 1993. Bottleneck congestion and modal split. Journal of Urban Economics 34, 414-431.), we integrate a redistribution of toll revenue towards public transport into our study. In this context, we investigate two kinds of road toll regimes: a fine toll and a uniform toll. We will consider two types of railroad fare: when it is set equal to the marginal cost and when it is set equal to average cost. These models allow us to show that toll policy to be more efficient as long as toll revenue is directed towards public transport when the railroad fare is equal to average cost. 相似文献
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Role of steering wheel feedback on driver performance: driving simulator and modeling analysis 总被引:1,自引:0,他引:1
D. Toffin G. Reymond A. Kemeny J. Droulez 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2007,45(4):375-388
When driving in curves, how do drivers use the force appearing on the steering wheel? As it carries information related to lateral acceleration, this force could be necessary for drivers to tune their internal model of vehicle dynamics; alternatively, being opposed to the drivers' efforts, it could just help them stabilize the steering wheel position. To assess these two hypotheses, we designed an experiment on a motion-based driving simulator. The steering characteristics of the vehicle were modified in the course of driving, unknown to drivers. Results obtained with standard drivers showed a surprisingly wide range of adaptation, except for exaggerated modifications of the steering force feedback. A two-level driver model, combining a preview of vehicle dynamics and a neuromuscular steering control, reproduces these experimental results qualitatively and indicates that adaptation occurs at the haptic level rather than in the internal model of vehicle dynamics. This effect is related to other theories on the manual control of dynamics systems, wherein force feedback characteristics are abstracted at the position control level. This research also illustrates the use of driving simulation for the study of driver behavior and future intelligent steering assistance systems. 相似文献
5.
Benoit Crevier Jean-François Cordeau Gilles Savard 《Transportation Research Part B: Methodological》2012,46(1):100-119
In the rail industry, profit maximization relies heavily on the integration of logistics activities with an improved management of revenues. The operational policies chosen by the carrier have an important impact on the network yield and thus on global profitability. This paper bridges the gap between railroad operations planning and revenue management. We propose a new bilevel mathematical formulation which encompasses pricing decisions and network planning policies such as car blocking and routing as well as train make-up and scheduling. An exact solution approach based on a mixed integer formulation adapted to the problem structure is presented, and computational results are reported on randomly generated instances. 相似文献
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Leo Gilles 《汽车与配件》2011,(14):27-29
再生型电子控制性稳定系统(Electronic Stability Control-Regenerative,ESC-R)是一个模块化的制动系统,可用于各种结构的混合动力车。ESC-R通过电机回收制动能量,也可以与转向扭矩控制等电动转向系统集成,提高车辆的整体安全性。 相似文献
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