Evaluation of the Double Snap-Through Mechanism on the Wave Energy Converter's Performance

Lower efficiencies induce higher energy costs and pose a barrier to wave energy devices' commercial applications. Therefore, the efficiency enhancement of wave ...     

UNCTAD activities in the field of ports and their future

UNCTAD's work in the field of ports started, soon after its establishment in 1964, as a result of a 'Common measure of understanding on shipping questions'. It resulted in a three pronged effort in research, training and technical assistance, carried by the secretariat in close collaboration with the industry. Technical publications were published and are widely used by practitioners throughout the world. Port managers and government officials responsible for ports in developing countries were the beneficiaries of large-scale training programmes. Technical assistance to improve port services was conducted in several developing countries. During the 1990s, new mandates were agreed in the field of transport in which ports are not explicitly mentioned. This paper argues that the stakes in ports are so vital for trading countries, notably those seeking accelerated economic development, that a broad interpretation of the current mandate is needed.     

KERFIX, a time-series station in the Southern Ocean: a presentation

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.     

A cooperative waiting strategy based on elliptical areas for the Dynamic Pickup and Delivery Problem with Time Windows

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.     

Probabilistic modelling of the ultimate strength of ship plates with non-uniform corrosion

This paper presents the results of a parametric study of probabilistic modelling of the ultimate strength of ship plates with non-uniform corrosion represented by random fields. The load-shortening behaviour of the plates with non-uniform reduction of thickness due to corrosion under longitudinal compression is obtained using a general-purpose nonlinear finite element analysis program. A nonlinear time-dependent corrosion model is used to define the probabilistic characteristics of the random fields based on corrosion data measured in plate elements at different locations of bulk carriers. Based on the probabilistic models derived by Monte Carlo simulation, equations to predict the mean and the 5 % characteristic value of the ultimate strength of plates with non-uniform corrosion are developed. Finally a regression equation is proposed to take into account the effect of non-uniform corrosion patterns in the predictions of the ultimate strength of plates with uniform corrosion.     

Demand analysis in Angola seaports

ABSTRACT

This 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.     

On the allocation of city space to multiple transport modes

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.     

Transportation of dangerous goods by road: the Brazilian case for selection of carriers based on a risk management methodology

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.     

The Measurement of Efficiency of UK Airports,Using a Stochastic Latent Class Frontier Model

Abstract

In this paper, the latent stochastic frontier model is used to estimate the technical efficiency of UK airports. These airports are ranked according to their technical efficiency for the period 2000–06 and the airports are disentangled and segmented by the cost frontier model, which leads us to advise the implementation of policies by segments. Economic implications arising from the study are also considered.