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571.
Management of coastal eutrophication: Integration of field data, ecosystem-scale simulations and screening models 总被引:5,自引:0,他引:5
A.M. Nobre J.G. Ferreira A. Newton T. Simas J.D. Icely R. Neves 《Journal of Marine Systems》2005,56(3-4):375-390
A hybrid approach for eutrophication assessment in estuarine and coastal ecosystems is presented. The ASSETS screening model (http://www.eutro.org) classifies eutrophication status into five classes: High (better), Good, Moderate, Poor and Bad (worse). This model was applied to a dataset from a shallow coastal barrier island system in southwest Europe (Ria Formosa), with a resulting score of Good. A detailed dynamic model was developed for this ecosystem, and the outputs were used to drive the screening model. Four scenarios were run on the research model: pristine, standard (simulates present loading), half and double the current nutrient loading. The Ria Formosa has a short water residence time and eutrophication symptoms are not apparent in the water column. However, benthic symptoms are expressed as excessive macroalgal growth and strong dissolved oxygen fluctuations in the tide pools. The standard simulation results showed an ASSETS grade identical to the field data application. The application of the screening model to the other scenario outputs showed the responsiveness of ASSETS to changes in pressure, state and response, scoring a grade of High under pristine conditions, Good for half the standard scenario and Moderate for double the present loadings. The use of this hybrid approach allows managers to test the outcome of measures against a set of well-defined metrics for the evaluation of state. It additionally provides a way of testing and improving the pressure component of ASSETS. Sensitivity analysis revealed that sub-sampling the output of the research model at a monthly scale, typical for the acquisition of field data, may significantly affect the outcome of the screening model, by overlooking extreme events such as occasional night-time anoxia in tide pools. 相似文献
572.
A game-theoretic analysis of competition among container port hubs: the case of Busan and Shanghai 1
Christopher M. Anderson Yong-An Park Young-Tae Chang Chang-Ho Yang Tae-Woo Lee Meifeng Luo 《Maritime Policy and Management》2008,35(1):5-26
Countries throughout the world, and especially within Asia, are investing heavily in container port infrastructure in the hopes of capturing a larger share of global shipping activity for their economies. Many existing ports are emphasizing developing the capacity to serve as a hub port, building deepwater berths with large terminals to facilitate transfer of containers from feeder ships to mother ships for intercontinental transport. We develop a game-theoretic best response framework for understanding how competitor ports will respond to development at a focus port, and whether the focus port will be able to capture or defend market share by building additional capacity. We apply this model to investment and competition currently occurring between the ports of Busan and Shanghai. 相似文献
573.
J. R. Serrano F. J. Arnau V. Dolz A. Tiseira M. Lejeune N. Auffret 《International Journal of Automotive Technology》2008,9(3):277-288
This article presents a two-stage turbocharged heavy-duty diesel (HDD) engine designed to fulfil the US2007 anti-pollution
directive. This directive imposes very restrictive limits on the NOx and particle emissions of HDD engines. In this work,
the possibility of combining particle traps in the exhaust line to reduce soot emissions with very high EGR rates to reduce
NOx emissions is considered. This new generation engine implements two-stage turbocharging in order to improve the bsfc when
the engine is working on steady conditions as well as to optimize the engine transient response. After carrying out the tests,
the results were analyzed and the engine settings were adjusted to maximise its behaviour and minimise pollutant emissions.
NOx and soot emission peaks were also analyzed at engine transient conditions in order to keep them under certain levels,
and thus maintain the overall pollutant emissions to a level that is as low as possible. In summary, a double-stage turbocharging
configuration can greatly improve engine driveability (between 23% and 36% depending on engine speed), while reducing NOx
emissions during transient evolution without increasing opacity peaks beyond the stated limits. 相似文献
574.
M. Antoni 《Recherche - Transports - Sécurité》2012,28(2):101-118
In this article, we discuss on how to solve the following problems: the checks and tests before putting the safety facilities into service, and the results of these tests which are essential, time consuming and may show great variations among each other. Economic constraints and the increasing complexity associated with the development of computerized tools tend to limit the capacity of the classic approval process. In practice, a reduction of the test cover rate is observed. The method presented in this article makes it possible to formally validate the new computerized mechanisms of the existing French interlocking systems with real-time functional interpreted Petri nets. The aim of our project was to provide SNCF with an operating method for the formal validation of interlocking systems. A formal proof method by assertion, applicable to our interlocking system, which covers equally the specification and its real software implementation, is presented in this article. With the proposed method and its associated tools, we completely verify that the system follows all safety procedures at all times and does not show superfluous conditions. This replaces all plateform tests checks. It is included in the existing testing procedures. The advantages of using this method are the following: a significant reduction of testing time and of the related costs, an increase of the test coverage rate (determinisitic safety vs. probabilistic safety), and an answer to the new demand of railway infrastructure maintenance engineering to modify and validate computerized interlocking systems. The mastery of formal methods by infrastructure engineers is surely a key to prove that additional safety is not expensive. 相似文献
575.
This paper describes the hydrographic conditions observed during six surveys carried out during 2003 and 2004, in the framework of the “IDEA Project” (acronym for “Influence of oceanographic structure and dynamics on demersal populations in waters of the Balearic Islands”). The surveys were developed on the shelf and slope of Mallorca Island, in particular in two fishing grounds at the north and south of the Mallorca channel. Periodic movements of the fishing fleet between these two areas have been regularly reported, suggesting a seasonal variability of the resources which could be in turn associated with the hydrodynamic variability. With this motivation, water masses affecting these grounds have been identified and their seasonal variability has been studied. Different oceanographic and environmental conditions have been found between the two fishing grounds. These differences are related to the presence of mesoscale structures, associated with the Western Mediterranean Intermediate Water (WIW) at the north of the Ibiza channel and big gyres detached from the Algerian Current. The former has been shown to have influence on the regional oceanic circulation and the latter could affect the progress of fresh Atlantic Water (AW) towards the channels and make possible the presence of high salinity values at intermediate waters at the south of Mallorca Island. Historical data from other oceanographic cruises carried out in the region are finally used to discuss the interannual variability of these mesoscale structures. 相似文献
576.
577.
用有限元法对各种载荷工况下的转向架构架进行了疲劳分析,利用人工神经网络和遗传算法最大程度地减轻了转向架构架的质量. 相似文献
578.
青藏高原铁路客车电气系统设计 总被引:2,自引:0,他引:2
文章从安全性和可靠性的角度出发,指出了青藏高原铁路客车电气系统需要解决的难题,介绍了电气系统及设备所采取的针对性措施以及系统控制与防护措施。 相似文献
579.
580.
以太网技术在列车通信网络中的应用探讨 总被引:1,自引:0,他引:1
基于现有列车通信网络(TCN)不能完全满足信息传输的情况,提出了工业以太网和CAN总线共存的方案,介绍了基于高性能数字信号处理器TMS320F206的工业Ethernet的硬件接口电路、CAN/Ethernet网关模型等。 相似文献