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Evrard M. Claessens 《Maritime Policy and Management》1989,16(2):109-121
Port investments are generally analysed one project at a time, often within a set of relevant scenario alternatives. Sometimes the issue consists in assessing a combination of complementary projects at different locations, such as may be the case in addressing the feasibility of comprehensive jetty programmes in inter-island shipping. These alternatives can be evaluated by the so-called 'warehouse approach' of business logistics, as is exemplified in the present exercise. 相似文献
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Jane Bryan Max Munday David Pickernell Annette Roberts 《Maritime Policy and Management》2006,33(4):371-386
The paper seeks to improve the evidence base surrounding regional ports and their economic impact. The paper reveals that industries dependent on the port infrastructure are actually key regional players, often operating in relatively fast growth sectors, and contributing to the economic and social needs of the local economy. The focus in the case element of the paper is the operations of Associated British Ports (ABP) plc in industrial South Wales. In examining the direct and indirect consequences of the port activity the paper adopts an input-output framework of analysis. A better contextualization of the economic impact of ports is shown to be necessary in the devolved policy-making environment in the region. 相似文献
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This paper describes a model to synchronize the management and query of temporal and spatially referenced transportation data in geographic information systems (GIS). The model employs a method referred to as dynamic location, which facilitates spatial intersect queries from geographic shapes without the use of topological relationships. This is the inverse of how dynamic segmentation works in GIS. In contrast to dynamic segmentation, dynamic location stores geometry as an object within a single database field. This is an efficient, precise iconic model superseding the need for data decomposition into a complex set of tables. As an object model, the dynamic location process lends itself to high performance in an Internet, data-intensive, enterprise environment. Linear events are stored as {x, y} features, and not referenced to any route system. Route systems are built from {x, y, m} values (m for measure) and serve as number lines for mathematical operations. Any {x, y} object can then be referenced to either the Cartesian grid or any selected number line. This method offers the benefits of linear referencing, while making full use of a stable geodetic datum. Combinations of any {x, y} events may be placed over any {x, y, m} number line (route) and an intersect determined by looking through stacked {x, y, m} vertices of the coincident shapes. Since both geometry and shape reside in the same record, the use of “begin” and “end” dates facilitates full spatial and temporal version control. From a business process perspective, this creates a spatially enabled database, pulling GIS business functions back into the information technology mainstream. 相似文献
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AbstractCatch share programs are used in fisheries management to meet goals such as species recovery, overcapacity reduction, and economic efficiency. Anticipated impacts include fleet consolidation, infrastructure reduction, and social disruption within communities. The Pacific Coast Groundfish Fishery Social Study (PCGFSS) aims to understand social changes related to the recently implemented West Coast Groundfish Trawl Catch Share Program. In this article, we use a subset of PCGFSS data to explore the ways remaining fishery participants have thus far adapted to catch shares. While some vessels have left the fishery, we found that many participants are adapting to this catch shares program despite challenges. Quota leasing strategies, fishery diversification, gear innovation, and community quota funds are some of the tools participants are using to continue operating under the catch shares program. These early challenges and adaptations to the catch share program are worthy of continued tracking, as researchers, managers, and fishing communities, would benefit by considering first-hand perspectives of the on-the-ground realities of harvesting groundfish in the rationalized fishery. 相似文献
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Mengshi Lu Simin Huang Zuo-Jun Max Shen 《Transportation Research Part B: Methodological》2011,45(8):1251-1265
Product substitution can mitigate supply chain disruptions. However, it may not be very effective without multiple sourcing. In this paper, we consider a supply chain with two downward substitutable products. The products can be ordered from an unreliable supplier or a reliable but more expensive supplier. It is found that in an optimal sourcing policy the higher-grade product should be preferred over the lower-grade product. A sufficient condition is given for an optimal policy where only the higher-grade product is dual-sourced. The effect of substitution is contrasted with the non-substitution case. Numerical study shows the impact of demand variability and correlation on the effect of product substitution and the corresponding optimal sourcing policy. 相似文献
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刘俊田 《西安交通大学学报(英文版)》1998,(2)
Occlusivevasculardisorders,bothvenousandarterial,aresomeofthemostcommoncausesofmorbidityandmortalityindevelopedcountries.Theaimoftherapyinsuchconditionsis,firstly,torestoreandmaintainbloodflowtotheaffectedtissueororgan,andsecondly,torestorethesystemtothenormalhaemostaticstatewithoutovercompensatingandproducingcomplicationssuchashaemorrhage.Thrombolyticagents,suchasrecombinanttissueplasminogenactivator(rt-PA),arewidelyusedinthetreatmentofpatientswithacutemyocardialinfarction.However,successful… 相似文献
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Max Von Groll Steffen Mueller Tilo Meister Rudolf Tracht 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2006,44(4):327-338
Via a conventional steering system the driver perceives desired and disturbing effects such as road feedback and resonance effects, respectively. They appear with overlapping frequency spectra within the driver's steering torque. This paper introduces a control algorithm that is suppressing periodic disturbances without affecting useful steering road feedback attributes as well as regular power assistance characteristic. This is realised by an integrated torque actuator within the steering column in conjunction with a conventional Hydraulic-assisted Power Steering (HPS) system. 相似文献