The design of bus route systems — An interactive location-allocation approach

An interactive modelling approach is developed to solve the practical problem of bus route network design. Possible bus routes are identified with facilities which can be located. Zones or pairs of zones in the urban area are identified with customers who will be allocated to the established facilities. It is shown that the classical Set Covering Problem is useful under the assumption of fixed demand; the Simple Plant Location Problem is effective under the assumption of demand which is sensitive to the level of bus service provided.     

Hub location with flow economies of scale

A characteristic feature of hub and spoke networks is the bundling of flows on the interhub links. This agglomeration of flows leads to reduced travel costs across the interhub links. Current models of hub location do not adequately model the scale economies of flow that accrue due to the agglomeration of flows. This paper shows that current hub location models, by assuming flow-independent costs, not only miscalculate total network cost, but may also erroneously select optimal hub locations and allocations. The model presented in this paper more explicitly models the scale economies that are generated on the interhub links and in doing so provides a more reliable model representation of the reality of hub and spoke networks.     

浅析连续箱梁设计中的几个问题

结合工程实际,对连续箱梁设计计算中常遇到的几个棘手问题进行定量分析,并给出工程中实际可用的计算方法。     

Marginal cost pricing of ferry transportation: a practical application ∗

In this paper, in which the author attempts to redress the lack of attention by economists to ferry operation, a simple pricing model, based on marginal cost pricing, is developed.     

Initiatives in Philippine Coastal Management: An Overview

Standardized and free-format questionnaires on the state of coastal management were fielded to coastal management practitioners during three workshops and a national feedback and recommendation workshop. The most commonly cited responses were identified for each of 13 political regions and overall trends were identified. Management frameworks frequently included research, community organizing, education, livelihood, resource enhancement, resource protection, regulation, and networking components. Gender issues, documentation, and infrastructure investment were rare. The most commonly perceived environmental problem was illegal/ destructive fishing and its associated overfishing and low fish catch. The most commonly cited socioeconomic problem was the inadequacy of law enforcement. The best monitored variables were usually those related to environmental management: status and change of habitats, resources, and degree of enforcement/patrolling activities. The most common nonregulatory enhancement, aside from environmental education (which is the most popular), was mangrove reforestation. In terms of regulations, the majority of the respondents have reportedly formulated an integrated coastal management plan. In practice, regulating destructive and illegal fishing practices and then the establishment of fish sanctuaries are the next most implemented. The most popular quality-of-life enhancement strategies focused on the improvement of sustainable fishing as a livelihood and on a variety of supplementary livelihoods. The most usual institutional intervention being implemented was the setting up of local community people's organizations. Major factors which may influence success or failure of coastal management and recommendations on research, community organizing and livelihood, legislation and policies, implementation and coordination, and networking are also summarized.     

地铁制动试验台测控系统简介

介绍了地铁制动试验台的测试对象和其测控系统的组成与原理。     

Dynamics of inorganic nutrient species in the Bohai seawaters

Within the frame of a Sino-German Joint Research Program, two cruises of “R/V Dong Fang Hong 2” were carried out in September–October 1998 and April–May 1999, respectively, to understand the dynamics of nutrients in the Bohai. Nutrient species (NO₃⁻, NO₂⁻, NH₄⁺, PO₄³⁻ and SiO₃²⁻) are determined colorimetrically on board for five anchor and 30 grid stations. In situ incubation experiments are performed to determine planktonic nutrient uptake and benthic exchange flux. Nutrient concentrations display short-term variability and seasonal change in the Bohai, with higher levels in shallow coastal waters than in the Central Bohai. The influence of riverine discharge on nutrient levels can be seen from salinity isopleths, nutrient distribution and species ratios. Near-bottom (nb) waters have similar nutrient concentrations as to the surface waters in the Central Bohai, whereas stratification takes place in the Bohai Strait and North Yellow Sea. In situ incubation experiments provide evidence that the uptake ratio (i.e. N, P) by phytoplankton is proportional to the ratios among nutrient species in ambient waters. Based on the data of this study and previously publications, a preliminary estimate of nutrient budgets via riverine input and atmospheric deposition is established. The results indicate that atmospheric deposition gains importance over rivers in delivering nutrients into the Bohai and sustain the new production, following recent decrease in riverine inflow caused by drought periods in North China and damming practices. A historical review of nutrient data indicates that concentrations of nitrogen increase and phosphorus and silica decrease in the Central Bohai over last 40 years. This potentially has an important influence on the health of ecosystem in Bohai (e.g. food web and community structure), though further study is needed to examine the scenario in more detail.