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31.
Jasna Prpić-Oršić Roberto Vettor Odd Magnus Faltinsen Carlos Guedes Soares 《Journal of Marine Science and Technology》2016,21(3):434-457
The influence of various parameters, such as ship initial speed (full ahead and lower engine loads), loading condition, heading angle and weather conditions on ship fuel consumption and CO2 emission is presented. A reliable methodology for estimating the attainable ship speed, fuel consumption and CO2 emission in different sea states is described. The speed loss is calculated by taking into account the engine and propeller performance in actual seas as well as the mass inertia of the ship. The attainable ship speed is obtained as time series. Correlation of speed loss with sea states allows predictions of propulsive performance in actual seas. If the computation is used for weather routing purposes, values for various ship initial speed, loading conditions and heading angles for each realistic sea‐state must be provided. The voluntary speed loss is taken into account. The influence of the ship speed loss on various parameters such as fuel consumption and CO2 emissions is presented. To illustrate the presented concept, the ship speed and CO2 emissions in various routes of the Atlantic Ocean are calculated using representative environmental design data for the track of the routes where the ship will sail. 相似文献
32.
Carlos Pestana Barros Peter U.C. Dieke 《Transportation Research Part D: Transport and Environment》2008,13(5):347-350
This Note looks at the choice valuation restrictions on traffic entering the city of Lisbon, based on individual preferences in relation to noise, pollution and congestion. The analysis employs a questionnaire distributed in 2007 to ascertain the significant characteristics of traveling to Lisbon, with the aim of curbing the number of cars that are associated with the probability of individuals supporting a charge on motor vehicles entering the city. The model also takes into account the uncontrolled heterogeneity of the data. 相似文献
33.
Abstract This paper looks at estimated valuations of some service‐quality attributes in an airline choice context using stated preferences methods. The analysis is based on information obtained in the most important route connecting the Canary Islands with the Iberian Peninsula: Gran Canaria–Madrid, and tries to contribute to the body of knowledge in this area, given the relatively few studies of the monetary valuations of air travel regarding level‐of‐service attributes. A feature of this analysis is the examination of variations in values according to different characteristics of the service, such as price, penalties for changes in the ticket, legroom, food, etc.; the currently experienced level of the attribute, and various socio‐economic factors that affect the characteristics of the trip and passengers. In addition, the important issue of added value regarding different attributes is addressed, obtaining the willingness‐to‐pay for different improvements of service quality. A further analysis is made about how taste heterogeneity (market segments) affects these values. Results from the stated preference experiment and the market value of some comparable service are also compared. Finally, the paper brings together evidence from other studies and compares them with the findings obtained herein. 相似文献
34.
We propose a dynamic linear model (DLM) for the estimation of day‐to‐day time‐varying origin–destination (OD) matrices from link counts. Mean OD flows are assumed to vary over time as a locally constant model. We take into account variability in OD flows, route flows, and link volumes. Given a time series of observed link volumes, sequential Bayesian inference is applied in order to estimate mean OD flows. The conditions under which mean OD flows may be estimated are established, and computational studies on two benchmark transportation networks from the literature are carried out. In both cases, the DLM converged to the unobserved mean OD flows when given sufficient observations of traffic link volumes despite assuming uninformative prior OD matrices. We discuss limitations and extensions of the proposed DLM. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
35.
Catherine Jeandel Diana Ruiz-Pino Elvis Gjata Alain Poisson Christian Brunet Edwige Charriaud Frank Dehairs Daniel Delille Michel Fiala Charles Fravalo Juan Carlos Miquel Young-Hyang Park Philippe Pondaven Bernard Quguiner Suzanne Razouls Bernard Shauer Paul Trguer 《Journal of Marine Systems》1998,17(1-4)
Between January 1990 and March 1995, the research project KERFIX undertook the first regular noncoastal multiyear acquisition of parameters related to the carbon cycle in the Southern Ocean at a time series station located at 50°40′ S–68°25′ E, 60 miles southwest of the Kerguelen Islands. The objectives of KERFIX are (1) to monitor the ocean/atmosphere CO2 and O2 exchanges and to understand which processes govern these exchanges (2) to observe and interpret the seasonal and interannual variability of the production, flux, decomposition and dissolution of carbon and associated elements at this location. In addition, micropaleontological studies describe the present and past flux dynamics in this oceanic area, to improve the knowledge of the transfer functions of some oceanographic proxies. This paper presents a survey of the KERFIX program: scientific objectives, organization of the field operations and some main results obtained since the beginning of KERFIX program, as well as the results of the temporal evolution of hydrological, chemical and biological parameters. 相似文献
36.
A cooperative waiting strategy based on elliptical areas for the Dynamic Pickup and Delivery Problem with Time Windows 下载免费PDF全文
The purpose of this paper to present a cooperative scheduling algorithm for solving the Dynamic Pickup and Delivery Problem with Time Windows (DPDPTW). The idea behind cooperative waiting strategies is to calculate simultaneously the waiting times for all nodes in the solution. Classical non‐cooperative scheduling algorithms perform the scheduling for each route independently of the scheduling of the other routes. We present the Cooperative Scheduling Problem (CSP) based on the elliptical areas generated by vehicles waiting at their nodes. The CSP is solved by means of a genetic algorithm and is evaluated by using a set of benchmarks based on real‐life data found in the literature. Initially, two waiting strategies are presented: Wait‐Early‐Time scheduling and Balanced‐Departure scheduling. Extensive empirical simulations have been carried out by analyzing the degree of dynamism and the average waiting time, a new concept defined to take into account the gap between the time windows of pickup and delivery nodes. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
37.
Juan Carlos Martín Augusto Voltes-Dorta 《Transportation Research Part B: Methodological》2011,45(1):112-127
The econometric estimation of cost functions has been proposed in the literature as a suitable approach in order to obtain estimations of marginal costs, efficiency levels and scale elasticities for transport industries. However, regarding the airport industry, no significant attention has been paid in developing an airport-specific estimation methodology rather than adapting the procedures applied to other industries. The lack of comparable airport data is one of the causes which could explain the scarcity of this literature in the past, as well as the use of very limited approaches to explain airport technology. This paper tries to overcome these limitations by developing an airport-specific methodology to estimate a multi-output long-run cost function using an unbalanced pooled database on 161 airports worldwide. The specification of hedonically-adjusted aircraft operations, domestic and international passengers, cargo and commercial revenues in the output vector, as well as the calculation of input prices are discussed. Both technical and allocative inefficiencies are specified in the model using a Stochastic Frontier method that has been estimated through Bayesian Inference and Markov Chain Monte Carlo methods. 相似文献
38.
Carlos Pestana Barros 《Maritime Policy and Management》2013,40(6):676-682
ABSTRACTThis paper presents a demand analysis of Angola seaports from 1996 to 2013 using the Berry, Levinsohn, and Pakes (BLP) demand model. The BLP is a random coefficient Logit demand model that takes into account the endogeneity of the price in the demand equation. The model reveals that seaports on Angola is explained by the average price, the price of maritime transport services, the price of substitute imports by airports, and by the income in the port region. The price is endogenous in demand equation and the endogeneity is taken into account in demand estimation. The price of air transportation is negative, and therefore it is a complementary good. The price of container handling is positive, and therefore it is a substitution good. Policy implication is also derived. 相似文献
39.
Eric J. Gonzales Nikolas Geroliminis Michael J. Cassidy Carlos F. Daganzo 《运输规划与技术》2013,36(8):643-656
Abstract This paper analyzes urban multimodal transportation systems in an aggregated way. To describe the aggregate behavior of traffic in cities, use is made of an idea that is now receiving some attention: the macroscopic fundamental diagram (MFD). We demonstrate through simulation how the MFD can be used to monitor and control a real network, in this case a portion of San Francisco, using readily available input data. We then show how different modes interact on the same network and discuss how these interactions might be incorporated into an MFD for multimodal networks. The work unveils two main results: first, it confirms recent results showing that restricting access to a city's congested areas can improve mobility for all travelers, including those who endure the restrictions; and second, that dedicating street space to collective transport modes can improve accessibility for all modes, even those from which space is taken away. 相似文献
40.
Marne Lieggio Junior Sérgio Ronaldo Granemann Osmar Ambrósio de Souza Carlos Henrique Rocha 《运输规划与技术》2013,36(7):677-696
Abstract This article applies a methodology for selecting carriers for the transportation of dangerous goods by road, with a special focus on risk management aspects. The methodology makes use of Stated Preference techniques and verifies the most critical risk-related variables influencing decision-making from the shippers' point of view. It embraces the planning and execution stages, an evaluation of the contracted company and a feedback process. The methodology was effectively applied to the case of liquid fuel shippers in the Brazilian middle-west region where it proved possible to identify which dangerous goods road transport company to contract in accordance with the risk management factors selected by the decision makers. 相似文献