船船水动力相互作用的CFD分析研究（英文）

A numerical study of ship-to-ship interaction forces is performed using a commercial CFD code, and the results are compared with experimental data and with the results of a panel method analysis. Two ship models have been used in the interaction forces analysis: a tug and a tanker, advancing parallel to each other with different lateral distances and two different values of the fluid depth. Computations are carried out with four different flow models: inviscid and viscous flow with the free surface modeled as a rigid wall and inviscid and viscous flow with the deformable free surface. A fair agreement was obtained with available experimental data and results obtained by panel method. The influence of viscosity in the computations is found to be comparatively weak, while the wavemaking effects may be important, at small magnitude of the horizontal clearance.     

Empowering Stakeholders to Manage Stinging Jellyfish: A Perspective

A global challenge is dealing with the risk of envenomation by the stinging jellyfish. Those who are affected include: the people stung, tourist providers; diving and adventure operations, beach and park authorities, life guards, commercial marine operators as well as local and centralized government; we focus on tourism. There is a diversity of jellyfish that pose a risk and they vary greatly in their ecology. Here, we propose five eco-groups of jellyfish to assist in prioritizing estimates of the risks to a broad clientele. Eco-groups are: (1) “Pulse species” that impact on beaches for short well-defined periods; (2) “Shelf-wide species;” (3) “Nearshore species;” (4) “Drifter species” and (5) “Deep sea species.” Great spatial variation and strong seasonality in the occurrence and abundance of jellyfish is the rule, rather than the exception, and this indicates that local knowledge and preventative action is the key to reducing the risk of envenomation. Managers can take control by getting involved in: predicting risk, detecting the presence of jellyfish and advising on/or providing barriers and protection, first responses and treatment of sting victims. Good communication and record keeping is critical within the stakeholder chain.     

科考船水下辐射噪声控制分析

介绍新造科考船可能参考的水下噪声标准以确保科考船进行合理的水下噪声控制,分析不同噪声源水下噪声的辐射机理及相应的噪声控制技术,并简要论述水下噪声验证测量的相关方法及可能的挑战。     

Global Fish Trade,Prices, and Food Security in an African Coral Reef Fishery

This study evaluated the potential impact of global fish trade on local food prices by analyzing a 16-year locally collected time series of disaggregated coral reef fish products and prices that differed in their market chain linkages—ranging from local to international markets. We were primarily interested in evaluating how local and global markets interacted with the local prices of beef, fish, and maize. There was no cointegration between the prices of exported octopus and that of maize and beef over this study period. Further, the three types of fish and associated markets responded in different ways to various price changes. For internationally traded octopus, we found a positive association between price and catch rates but no evidence that the global trade in octopus markets created local inflation, particularly the prices of the fish eaten by the poor. In general, there was no evidence for price transmission from export to nonexport fish products even though fishers appeared to focus on octopus when prices were high. Consequently, fishers' behaviors and trade policies that promote adjusting fishing effort to internationally traded fish did not appear to promote poverty or food insecurity in this fishery.     

Incompleteness and clarity in bus contracts: Identifying the nature of the ex ante and ex post perceptual divide

In the transport sector, many types of contracts exist. Some are very precise, and strive for completeness; others are very ‘light-weight’ and are incomplete. Bus and coach contracts, won through competitive tendering or negotiation, are typically incomplete in the sense of an inability to verify all the relevant obligations, as articulated through a set of deliverables. This paper draws on recent experiences in contract negotiation, and subsequent commitment in the bus sector, to identify what elements of the contracting regime have exposed ambiguity and significant gaps in what the principal expected, and what the agent believed they were obliged to deliver. We develop a series of regression models to investigate the extent of discrepancy between the principal and the agents perceived ‘understanding’ of contract obligations. The empirical evidence, from a sample of bus operators, is used to identify the extent of perceived incompleteness and clarity across a sample of bus contracts. A noteworthy finding is the important role that a trusting partnership plays in reducing the barriers to establishing greater clarity of contract specification and obligations, and in recognition of the degree of contract completeness.     

Are we doing it wrong or do we expect too much? Forces that push authorities to become public transport designers

This paper presents a number of reasons that are responsible for the disappointment of authorities in their operators’ efforts to develop public transport (PT) to the advantage of their travellers. The lessons drawn in this paper are based upon the competitive tendering experience of the authors and upon the results of meetings organised with parties involved in competitive tendering and aimed at exchanging lessons. There appears to be three main causes: (1) there is freedom for the operator, but the contract is bad; (2) there is freedom for the operator, there is a good contract, but there is no market; and (3) there is freedom for the operator, but the operator is not able to use it. The paper concludes with a few perspectives for improvement.     

Contracting regimes for bus services: What have we learnt after 20 years?

This paper reviews a number of themes that have played a crucial role in the debate on alternative contracting regimes for the provision of urban bus services. We have selected four crucial issues to reflect on: (i) contractual regimes (in particular competitive tendering as compared to negotiated performance-based contracts, as means to award the rights to provide service); (ii) contract completeness (focussing on ex ante and ex post elements); (iii) building trust through partnership; and (iv) tactical or system level planning for bus services. Experience in these areas suggests that competitive tendering has frequently not lived up to expectations and that negotiation is likely in many circumstances to deliver better value for money.     

Seaports and the structural implications of the economic crisis

The 2008 credit crunch and the subsequent economic crisis ended a period that lasted over two decades wherein international seaports around the globe experienced double-digit volume increases. This chapter provides an analysis of the structural effects that the crisis has on seaports, focusing mostly on developments in Europe. It does so via an examination of (a) the crisis implication for each of the four major types of transport flows that account for the vast majority of port throughput worldwide; (b) the prospects for future capacity organisation and development, given the realignment of the involvement strategies that the various stakeholders (i.e., governments, port authorities, service providers, users, investors) endorse in reaction to the financial tsunami; and (c) the adjustment opportunities, that the trade downturn unintentionally provides, allowing for correction of existing misallocations in the sector via the deployment of relevant adjustment strategies by the related actors. Recapping the identified structural consequences, the final section concludes on the changing role and responsibilities of port authorities and the ‘new issues’ that will require further investigation in the post-financial tsunami era.     

Toward the betterment of risk allocation: Investigating risk perceptions of Australian stakeholder groups to public-private-partnership tollroad projects

This paper presents a qualitative assessment of the risk perceptions held by key Australian stakeholder groups in the context of tollroads operated under the public-private-partnership model. The findings confirm that experience accumulated in recent years has contributed toward the betterment of risk-sharing optimisation amongst the contracting parties. The knowledge acquired through in-depth interviews supports the common view that equitable risk sharing is the vital ingredient of value for money. The proposition that the private sector is better equipped to manage commercial risks involving economic decision making whilst risks that have embedded unquantifiable social and public values and those in the domain of public governance are best left with government alone, appears to be replete with refutable implications. Public perception is a malleable concept and should be managed by both sectors.     

An activity-based approach for scheduling multimodal transit services

This paper proposes a new activity-based transit assignment model for investigating the scheduling (or timetabling) problem of transit services in multi-modal transit networks. The proposed model can be used to generate the short-term and long-term timetables of multimodal transit lines for transit operations and service planning purposes. The interaction between transit timetables and passenger activity-travel scheduling behaviors is captured by the proposed model, as the activity and travel choices of transit passengers are considered explicitly in terms of departure time choice, activity/trip chain choices, activity duration choice, transit line and mode choices. A heuristic solution algorithm which combines the Hooke–Jeeves method and an iterative supply–demand equilibrium approach is developed to solve the proposed model. Two numerical examples are presented to illustrate the differences between the activity-based approach and the traditional trip-based method, together with comparison on the effects of optimal timetables with even and uneven headways. It is shown that the passenger travel scheduling pattern derived from the activity-based approach is significantly different from that obtained by the trip-based method, and that a demand-sensitive (with uneven headway) timetable is more efficient than an even-headway timetable.