腹地经济发展对港口吞吐量影响的动态研究

腹地经济规模和经济结构的变化影响着港口的发展方向，但是一般的静态回归模型中解释变量参数是固定的，无法反应腹地各种影响因素变化对港口吞吐量产生的动态影响，而变参数状态空间模型克服了这一缺陷，解释变量的参数可以随时间改变，充分体现了解释变量对因变量影响关系的改变，因此能够更加准确反映考察期内腹地各种因素对港口吞吐量的动态影响。在介绍模型的基础上，就东北经济对大连港集装箱吞吐量影响进行了实证研究，得出了较为详尽的结论，这些结论是港口未来发展的重要决策依据。     

无缝设计与施工在某超长结构地下室中对砼裂缝控制应用

结合工程实践,通过对地下室砼开裂的原因进行了分析,对影响结构的耐久性和安全性的裂缝,提出处理措施。     

T_H1 AND T_H2 CELL ANTIGEN RECEPTORS IN EXPERIMENTAL LEISHMANIASIS

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Impact of information technology on public transport fares data

The work described was undertaken as part of the CASSIOPE project in the EC DRIVE programme. A range of fare collection procedures in public transport is described, and the importance of these for data collection by operators is stressed. It is suggested that such data management could be standardized and to this end four case studies were carried out in different European cities. Data models were built for each city, and these models are merged into a preliminary version of a generalized model. The need and uses for such a fare collection data model is explained.     

Should the user pay?

The paper puts the case that historical analysis helps to understand current discussions on user-pays principles and practice. In particular, (a) it is demonstrated that the nature of funding systems is dominated by political considerations, and (b) user-pays systems lead to inadequate funding of infrastructure when politically controlled, but provide funds for expansion when “market-driven” (in pursuit of profit maximisation). The case is illustrated by reference to the experience of interregional transport infrastructure in 19th century in England and 20th century Australia. Revenue deficiencies arising from government-controlled rates can lead to the demise of private transport infrastructure. The problem is considered in the context of the history of interregional roads and railways in England between the 15th and 19th century in England and in Australia in the 19th and 20th century. The current embrace by government of the user-pays system in transport services arises from fiscal deficiencies, as much from economic philosophy. User-pays policies are part of the global re-emergence of economic rationalism since the 1970s. The lesson for other nations from Australia's experience is twofold. First, in a federal system of government, despite the efficiency benefits of user-pays in interregional land transport, fiscal and political objectives will prevail. Second, in sparsely populated and/or developing countries, deregulation of long distance road transport will make funding a national highway system a critical concern.     

The market for second-hand ships: Further results on efficiency using cointegration analysis

This paper examines the dynamic behaviour of second-hand prices of tankers and dry-cargo vessels over various time periods, with a view to determining whether or not the markets for such assets are efficient. It extends and re-analyses the results of an earlier study by Hale and Vanags, published in this journal in 1992. Using a more modern method of testing for cointegration, it is shown that both the tanker and dry cargo markets appear to be cointegrated, a fact which would suggest that these markets are inefficient. It is suggested that the existence of cointegration does not necessarily imply market inefficiency, if the factors that create the common trends are themselves stochastic in nature. With this in mind, it is argued that the evidence put forward in this paper is still consistent with market efficiency in the long run.     

Mathematical Modelling of Vibrations and Loading of Railway Tanks Taking into Account the Liquid Cargo Mobility

Dynamics and loading of railway tank cars transporting liquid cargo are investigated. The approach based on the mechanical-pendulum analogy for the liquid cargo mobility simulation is proposed. Hydrodynamic parameters of the mechanical analogy are determined using the solution of the boundary-value problem for the liquid cargo vibrations in a cavity with the tank boiler shape. The fitting of the developed mathematical models is proved by comparison of calculated results and test data. Vibration characteristics and loading of tank-cars under their shunt collisions and motion along straight and curved track in trains are evaluated. It is shown that as a rule the liquid cargo mobility has an essential influence on tank dynamic properties.     

The dynamics of traffic assignment and traffic control: A theoretical study

The paper considers traffic assignment, with traffic controls, in an increasingly dynamic way. First, a natural way of introducing the responsive policy, P_o, into steady state traffic assignment is presented. Then it is shown that natural stability results follow within a dynamical version of this static equilibrium model (still with a constant demand). We are able to obtain similar stability results when queues are explicitly allowed for, provided demand is constant. Finally we allow demand to vary with time; we consider the dynamic assignment problem with signal-settings now fixed. Here we assume that vehicles are very short and that deterministic queueing theory applies, and show that the time-dependent queueing delay at the bottleneck at the end of a link is a monotone function of the time-dependent input profile to the bottleneck. We have been unable to obtain results when dynamic demand and responsive signal control are combined.     

A dynamic stochastic assignment model for the analysis of general networks

The paper adopts the framework employed by the existing dynamic assignment models, which analyse specific network forms, and develops a methodology for analysing general networks. Traffic conditions within a link are assumed to be homogeneous, and the time varying O-D travel times and traffic flow patterns are calculated using elementary relationships from traffic flow theory and link volume conservation equations. Each individual is assumed to select a departure time and a route by trading off the travel time and schedule delay associated with each alternative. A route is considered as reasonable if it includes only links which do not take the traveller back to the origin. The set of reasonable routes is not consistant but depends on the time that an individual decides to depart from his origin. Equilibrium distributions are derived from a Markovian model which describes the evolution of travel patterns from day to day. Numerical simulation experiments are conducted to analyse the impact of different work start time flexibilities on the time dependent travel patterns. The similarity between link flows and travel times obtained from static and dynamic stochastic assignment is investigated. It is shown that in congested networks the application of static assignment results in travel times which are lower than the ones predicted by dynamic assignment.