Spatial fisheries ecology: Recent progress and future prospects

We review recent progresses made in the study of fish distribution and survival over space — i.e., fisheries spatial ecology. This is achieved by first surveying the most common statistical approaches and relative challenges associated with the analysis of fisheries spatial data, loosely grouped in geostatistical and regression approaches. Then we review a selected number of case-studies implementing the discussed techniques. We conclude by proposing new areas of statistical and ecological research to further our understanding of how fish distribute and survive in space. This review serves a dual purpose by emphasizing the scientific importance of studying spatial interactions to better understand the temporal dynamics of fish abundance, and by promoting the development of new analytical and ecological approaches for the analysis of spatial data. Through our survey we cover different statistical techniques, marine ecosystems and life stages. This analytical, geographic and ontogenetic variety is also purposely selected to highlight the importance of comparative and multidisciplinary studies across diverging ecological disciplines, ecosystems and life stages. Besides having a general ecological relevance this review also bears a more applied significance, owing to the increasing need for protecting renewable marine resources along with their primary habitat.     

American and European transportation responses to the 1973–74 oil embargo

A survey of U.S. and European responses to the energy crises engendered by the Arab boycott of October 1973–April 1974 is presented. U.S. Government policy actions with respect to allocation, rationing, price, and conservation measures are reviewed and contrasted with those of affected European governments. The results of those policies and their effects on transportation energy supply and demand behavior with respect to both commodity and passenger movement are described.Based on short- and long-term impact assessments of the policies considered, the authors identify significant research requirements.The authors were heavily engaged in U.S. responses to the energy emergency, and were asked to undertake study missions to those European nations significantly affected by the crisis to seek out avenues for mutual aid, and joint research, in resolving common energy problems. This paper is one product of those study missions.     

Devising business strategy for railways

This paper presents a case study which tackles a general problem for railway management, namely the formulation of a strategy to improve business financial performance. This is prefaced, in Section 2, by discussion of general principles - concerning the type of information system required, investigations to be conducted and associated measurement needs. The case study, of Section 3, concerns our investigations of VicRail's total business and its constituents. The task of financial improvement is revealed from an assessment of sectors' current cost-recovery positions and the identification of system joint costs. For freight sectors, future traffic prospects, pricing possibilities and the scope for more efficient operations are then considered, and the implications traced for overall deficit reduction and the development of business strategy. The concluding section draws some general lessons for railway managements.A fuller discussion by the authors of the theoretical framework employed, and particularly of the case study application, is contained in a complimentary publication: Improving Railway Financial Performance, published by Gower in January 1985.Transmark is a subsidiary of the British Railways Board, acting as its international consultancy. The authors, who were respectively study director and manager, wish to thank Bernard Warner (an independent consultant), Richard Eccles (of Transmark) and Adrian Balkyn-Rackowe (of British Rail) for their valuable contributions. The study report, titled Rail Cost — Pricing Options, was released by the Minister in April 1981.     

6502站继电器采集故障原因分析

本文通过对6502站继电器采集故障原因进行分析，提出用增加复示继电器、缩短电缆长度或采集电缆单独敷设的方法，减少采集故障发生，确保列控中心识别进路信息采集的正确性。     

The Alternative Motor Fuels Act, alternative-fuel vehicles, and greenhouse gas emissions

The corporate average fuel economy (CAFE) standard is the major policy tool to improve the fleet average miles per gallon of automobile manufacturers in the US. The Alternative Motor Fuels Act (AMFA) provides special treatment in calculating the fuel economy of alternative-fuel vehicles to give manufacturers CAFE incentives to produce more alternative-fuel vehicles. AMFA has as its goals an increase in the production of alternative-fuel vehicles and a decrease in gasoline consumption and greenhouse gas emissions. This paper examines theoretically the effects of the program set up under AMFA. It finds that, under some conditions, this program may actually increase the production of fuel-inefficient gasoline vehicles, gasoline consumption and greenhouse gas emissions.     

Non-local simulation of the stable boundary layer with a third order moments closure model

A new higher order closure model for the stable boundary layer is presented and compared with Large Eddy Simulation data. The model includes numerical solutions for the mean values, second and third order moments equations. A satisfactory agreement is found between the calculated vertical profiles of the turbulent quantities with those provided by the LES. Furthermore the new model results are compared with profiles obtained with a lower order closure model in order to verify the effective importance of including third order dynamical equations in the model.     

城市桥梁改造中的桥头交叉口典型问题及对策

早期桥梁建设中往往对桥头接线缺乏重视,运行至今,存在较多的道路交通问题。文章以福建省将乐县三华大桥桥头交叉口为分析对象,对旧桥改造中面临的一系列道路交通问题进行分析,并结合大桥实际情况,提出了相应的改善措施,供相关工程技术人员参考。     

Net tax incidence for urban public transit subsidies in New Zealand

This paper examines the impact of policy changes in the funding of New Zealand public transit modes.These changes, introduced in 1983, are evaluated in terms of the net incidence of public transit subsidy assistance, taking into account its source of funding and the income class of those commuters benefiting from the subsidy. The general conclusion is that the net incidence of subsidy assistance remains progressive (i.e., a transfer from high to low income commuters) following the introduction of shared funding on the predominant public transit modes (rail and bus), sourced from income tax (central government) and property tax (regional/local government). However, because of the predominance of medium to high income commuters on rail vis-a-vis bus and the traditional source of funding on these modes in terms of income tax (a progressive tax source) and property tax (a regressive tax source), the degree of progressivity previously associated with public transit subsidies has now substantially reduced.The analysis and opinions expressed in this paper are the responsibility of the author alone and do not purport to represent the views of the Ministry of Transport.     

Off-set crack propagation analysis under mixed mode loadings

An assessment was carried out herein to study the eccentricity of cracks subjected to mixed-mode loadings. Several loading locations relative to a central line were selected to induce mixed-mode loadings, which were computed using a finite element method. An adaptive meshing technique was adopted during the simulation of crack propagation to ensure the singularity of stress at the tip of the crack. The stress intensity failure criterion was used and programmed, and the node splitting technique was used when the stress intensity factor reached the fracture toughness of the material to simulate crack propagations. It was found that large variations in the stress intensity factor were observed when off-set cracks were used, and that K _II decreased when loading distance increased, but increased when the off-set crack distance was increased. Both crack eccentricity and loading distance played important roles in producing mixed-mode loading, compared to the influence of central cracks. Correction factors were introduced to modify the calculation of stress intensity factors under mixed-mode loadings. Simulations of crack propagation were also conducted to study the effects of crack eccentricities and loading distances. It was found that the crack length, the loading distance relative to the central crack and the crack eccentricity dominated calculations of the integrity of cracked structures.     

Sampling of alternatives for route choice modeling

This paper presents a new paradigm for choice set generation in the context of route choice model estimation. We assume that the choice sets contain all paths connecting each origin–destination pair. Although this is behaviorally questionable, we make this assumption in order to avoid bias in the econometric model. These sets are in general impossible to generate explicitly. Therefore, we propose an importance sampling approach to generate subsets of paths suitable for model estimation. Using only a subset of alternatives requires the path utilities to be corrected according to the sampling protocol in order to obtain unbiased parameter estimates. We derive such a sampling correction for the proposed algorithm.Estimating models based on samples of alternatives is straightforward for some types of models, in particular the multinomial logit (MNL) model. In order to apply MNL for route choice, the utilities should also be corrected to account for the correlation using, for instance, a path size (PS) formulation. We argue that the PS attribute should be computed based on the full choice set. Again, this is not feasible in general, and we propose a new version of the PS attribute derived from the sampling protocol, called Expanded PS.Numerical results based on synthetic data show that models including a sampling correction are remarkably better than the ones that do not. Moreover, the Expanded PS shows good results and outperforms models with the original PS formulation.