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1.
2008年年底之前,10台Evolution系内燃机车中的第一台离开了位于宾夕法尼亚州伊利的GE交通运输集团组装工厂,前往哈萨克斯坦。这10台机车是为提高哈萨克斯坦Temir Zholy(KTZ)公司14205km铁路网牵引能力订购的大量机车的首批机车,该铁路网的电气化线路不足%。  相似文献   
2.
Since 1992, coastal researchers at the University of North Carolina at Wilmington have been documenting the impacts of human recreational use on Masonboro Island, a component of the North Carolina National Estuarine Research Reserve, and the subsequent natural processes that mitigate these impacts. Both short-term and long-term natural mitigational processes were identified. The effects of these processes were found to be much more rapid than similar impacts on typical terrestrial settings. However, careful examination of the data suggests that both physical location of the impact site and natural variability of weather patterns and events play a role. Management implications of these findings are proposed.  相似文献   
3.
Controllable dampers using electrorheological (ER) fluids have attracted considerable interest in recent years. They are proposed for use in semi-active suspensions for ground vehicles. The main advantages of ER fluid dampers are their fast response, ease of control, simple construction and low power requirements. This paper describes the development and testing of a high-voltage supply unit for modulating the damping force of an ER fluid damper. Experimental results on the vibration isolation characteristics of an ER fluid damper with different control strategies, obtained using a quarter-car model test rig, are also presented.  相似文献   
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Beach “nourishment” consists of placing sand on an eroding beach. The widened beach provides increased storm protection to adjacent structures and improved recreational benefits, but is most often transient, requiring on-going, repeated nourishment episodes. Numerical models of beach nourishment typically address such questions as how long a widened beach will last; economic models compare the benefits and costs of preserving a stretch of beach without regard to its geomorphic evolution. Neither have addressed the physical nor economic interactions between adjacent nourishing communities. Here, we couple a numerical model of coastline evolution and a cost-benefit model of beach nourishment, allowing adjacent communities to make dynamic nourishment decisions. Beach nourishment benefits adjacent communities both “updrift” and “downdrift.” The total amount of money spent on nourishment activities can decrease by as much as 25% when adjacent communities both conduct on-going nourishment projects, as opposed to the case where each community nourishes in isolation.  相似文献   
6.
介绍了法国宽体列车的设计理念,以及主要的结构特点和技术参数。  相似文献   
7.
The U.S. Army Corps of Engineers administers the only nationwide regulatory program that controls development activities in U.S. waters and wetlands. This article examines the statutory authorities, jurisdictional limitations, and evolution of the current Corps regulations, which express a strong policy to protect wetlands, estuaries, and tidal waters from unnecessary dredging, filling, or other alteration. The article explains the organization and procedures of the U.S. Army Corps of Engineers and examines in detail several precedential permit cases which have developed and implemented the Corps “wetlands policy.”; The article also evaluates current and potential policies underlying the regulatory efforts of the Corps of Engineers.  相似文献   
8.
Increasingly, natural resource managers see the marine protected areas that they are responsible for as linked social-ecological systems. This requires an equal focus on managing for both natural and human dimensions of the protected estate. Consequently, identification of indicators that represent the human dimensions of Large Scale Marine Protected Areas (LSMPAs) such as the Great Barrier Reef (GBR) is critical if these values are to be properly considered as part of standard management practice. Assessment and monitoring of the human dimensions of LSMPAs requires a replicable, collaborative process, rolled out at local scales but comparable across vast, socially and geographically diverse areas. This paper explores the application of a process for the development, assessment, and monitoring of the GBR's human dimensions. The process includes (a) development of a conceptual framework that links indicator sets to the desired state of the GBR's human dimensions; and (b) a collaborative approach including ten practical steps to implement assessment, monitoring, and benchmarking of the human dimensions of an LSMPA. We conclude with examination of challenges and opportunities for implementing this process in the GBR context, specifically with respect to the targets and objectives of the Reef 2050 Long-Term Sustainability Plan.  相似文献   
9.
欧洲锂电池行业贸易机构RECHARGE警告称,在2022年2月10日的投票之前,欧盟"电池和废电池报告草案"的部分内容可能会扼杀这一行业,令行业无法实现目标. 2月10日,欧洲议会的环境、公共卫生和食品安全委员会对这份报告进行了表决,报告更明确地定义了哪些电池可以进入市场,并对电池中的回收材料含量提出了最低要求.  相似文献   
10.
The Mackenzie River is the largest river on the North American side of the Arctic and its huge freshwater and sediment load impacts the Canadian Beaufort Shelf. Huge quantities of sediment and associated organic carbon are transported in the Mackenzie plume into the interior of the Arctic Ocean mainly during the freshet (May to September). Changing climate scenarios portend increased coastal erosion and resuspension that lead to altered river-shelf-slope particle budgets. We measured sedimentation rates, suspended particulate matter (SPM), particle size and settling rates during ice-free conditions in Kugmallit Bay (3–5 m depth). Additionally, measurements of erosion rate, critical shear stress, particle size distribution and resuspension threshold of bottom sediments were examined at four regionally contrasting sites (33–523 m depth) on the Canadian Beaufort Shelf using a new method for assessing sediment erosion. Wind induced resuspension was evidenced by a strong relationship between SPM and wind speed in Kugmallit Bay. Deployment of sediment traps showed decreasing sedimentation rates at sites along an inshore–offshore transect ranging from 5400 to 3700 g m− 2 day− 1. Particle settling rates and size distributions measured using a Perspex settling chamber showed strong relationships between equivalent spherical diameter (ESD) and particle settling rates (r= 0.91). Mean settling rates were 0.72 cm s− 1 with corresponding ESD values of 0.9 mm. Undisturbed sediment cores were exposed to shear stress in an attempt to compare differences in sediment stability across the shelf during September to October 2003. Shear was generated by vertically oscillating a perforated disc at controlled frequencies corresponding to calibrated shear velocity using a piston grid erosion device. Critical (Type I) erosion thresholds (u) varied between 1.1 and 1.3 cm s− 1 with no obvious differences in location. Sediments at the deepest site Amundsen Gulf displayed the highest erosion rates (22–54 g m− 2 min− 1) with resuspended particle sizes ranging from 100 to 930 µm for all sites. There was no indication of biotic influence on sediment stability, although our cores did not display a fluff layer of unconsolidated sediment. Concurrent studies in the delta and shelf region suggest the importance of a nepheloid layer which transports suspended particles to the slope. Continuous cycles of resuspension, deposition, and horizontal advection may intensify with reduction of sea ice in this region. Our measurements coupled with studies of circulation and cross-shelf exchange allow parameterization and modeling of particle dynamics and carbon fluxes under various climate change scenarios.  相似文献   
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