Pressure drop and heat transfer of catalyzed diesel particulate filters due to changes in soot loading and flow rate

When soot particles are loaded in a diesel particulate filter, it causes increase in back pressure of the exhaust system. To minimize this pressure drop due to DPF, the filter needs to be regenerated after a certain amount of soot has been accumulated. It is crucial to estimate the correct amount of soot that has been accumulated by measuring the differential pressure. It is also important to understand changes in pressure drop due to flow rate variations of the exhaust gas, since the pressure drop would be influenced by the exhaust flow rate as well as the amount of soot. Furthermore, the heat transfer characteristics of the catalyzed diesel particulate filter (CDPF) are another major issue, as the filter is occasionally exposed to high temperature gas. This study presents the characteristics of pressure drop according to the variation of soot loading and the mass flow rate in CDPF. In addition, heat transfer characteristics in the filter was investigated when a high temperature gas flows into the CDPF. Tests were performed in several CDPF samples having varying amounts of catalyst coating. Experimental results indicate that rig-based experiments are useful in understanding the characteristics of pressure drop in the CDPF. In the cake filtration region, a pressure drop has a proportional relationship according to soot loading and mass flow rate. It was found that an increased catalyst coating may lead to enhanced convective heat transfer.     

Developing a Framework to Identify Local Business and Government Vulnerability to Sea-Level Rise: A Case Study of Coastal Virginia

In this article, we develop methods for identifying local business and government vulnerabilities to sea-level rise and the natural hazards associated with it. Unlike the fairly large literature on measuring social vulnerability to natural hazards, there are very few papers that discuss methods for measuring local business or local government vulnerability even though businesses and governments are also differentially affected natural hazards. Our goal is to create measures that are easily replicable using readily available data and that are easy to explain to local planners, policymakers, and citizens. We implement our measures of local business and government vulnerability for our study area, Coastal Virginia. We combine those measures with a physical vulnerability measure to identify the areas in Coastal Virginia where planners and policymakers need to more closely examine the potential impacts of sea-level rise on their local businesses and government. While our methods are tailored to Coastal Virginia, they could be easily applied in other areas threatened by sea-level rise.     

Why do you care what other people think? A qualitative investigation of social influence and telecommuting

The effect of social interactions on decision-making is a topic of current interest in the travel behavior literature. These interactions have been investigated primarily from an intra-household perspective, but increasingly too in other types of social settings. In the case of interactions within a workplace, it has been suggested that the decision to telecommute may have some important social components. Previous research has concentrated on social isolation, and the effect on job satisfaction of qualitatively different (i.e., telecommunications-mediated) relationships with managers and colleagues. A topic that remains unexplored is the way social norms, in effect the influence of other people’s behavior, may influence the decision to adopt telecommuting. In this paper we set to investigate, within a qualitative framework, the role of social contact in the process of acquiring information on, and making decisions about, telecommuting. The results indicate that social contact does play a subtle but non-trivial role in the adoption and continuation process, and offer some insights about the importance of the social dimension, institutional set-up, and how they interact to influence the decision to telecommute.     

Transport in developing and emerging nations

One perspective on the allocation of transport investments by public authorities is offered by the so‐called ‘pork barrel’ model, whereby politicians and political parties allocate public investment spatially in such a way as to gain electoral support from localities so benefited. The paper introduces this model and discusses its attractions and problems in the case of the transport sector. A review of the modest number of published examples of this approach is offered before a detailed case study considers the case of railway investment in Nelson, New Zealand.     

Development of Beach Analysis Tools for Caribbean Small Islands

Beach erosion presents a hazard to coastal tourism facilities, which provide the main economic thrust for most Caribbean small islands (CSIs). Ad hoc approaches to addressing this problem have given way to the integrated coastal zone management (ICZM) approach, which recommends data collection, analysis of coastal processes, and assessment of impacts. UNESCO's Coast and Beach Stability in the Caribbean (COSALC) project has provided most CSIs with an opportunity to monitor their beaches and collect over 10 years of data. Research has been directed at integrating these data with geographic information systems (GIS) and other information technologies to develop a prototype beach analysis and management system (BAMS) for CSIs. This article presents the results of phase I development of this effort, which includes the development of tools for integrating spatial and non-spatial coastal data, estimating long-term beach erosion/accretion and sand volume change trends at individual beaches, identifying erosion-sensitive beaches, and mapping beach erosion hazards. The Southeast Peninsula, St. Kitts, is used as a case study to develop these tools and demonstrate system functionality.     

Fundamentals of discrete multimodal choice modelling

Abstract

In this paper an overview is given of the most relevant issues relating to the application of multimodal choice models, with particular emphasis on disaggregate modal split models. The paper considers questions of data, such as type of data, alternative sampling strategies and problems of measurement; and modelling issues, such as model specification and estimation, including a good presentation of the statistical techniques'available. The paper also addresses the aggregation problem, which lies at the heart of one of today's most hotly contested debates: whether to use aggregate or disaggregate models for policy analysis, and in which circumstances.     

The maximum shipping capacity of the Suez Canal

This paper considers the determination of the maximum shipping capacity of the Suez canal. Initially, some assumptions are made in order to calculate the ‘theoretical’ maximum capacity in terms of ‘standard ships’. This last term defines ships which transit the Canal at a given speed and at a given time interval from the vessel ahead and astern.

Data has been collected from the Canal Zone, the analysis of which provides the necessary information regarding speeds of vessels at different sections of the Canal, time gaps between different classes of ship at different nodes of the Canal, and relationships between time widths of convoys and numbers of ships in those convoys at different points of the Canal.

This data has then been used to calculate the maximum capacity of the Canal in terms of ‘real ships’. For that purpose four schemes have been devised, each taking a different mix of categories of ships. A sensitivity analysis has been undertaken in order to investigate the effect of each class of ship on the real maximum shipping capacity of the Canal. The last two schemes take into consideration the effect of the future introduction of supertankers.     

Road pricing—some of the more neglected theoretical and policy implications

The intention of this paper has been to raise some doubts about the extent to which the control of congestion is understood, not as an engineering problem, but as a socio‐economic one concerned with making the most appropriate use of scarce resources.

Despite some doubts, it seems that the basic theory, as applied to a highly simplified situation, is technically correct. What is much less clear, however, is the extent to which the acceptance of this analysis as a basis for policy making in the real world is justified. Even if, qualitatively, its implications are correct, there are significant quantitative uncertainties. Given that governments, local and national, are still pouring considerable sums of money, both through subsidies and investment, into the relief of congestion, it is desirable to change this state of affairs. There seems to be ample scope for the transport economist, the transport planner and the transport engineer to contribute to a debate which has a long and, in places, distinguished pedigree, but where the outcome is as yet considerably outstripped by the importance and complexity of the problems which must be solved.

     

The new economic order and African shipping policies

This paper approaches the problem of port labour training in Africa. It examines various aspects of immediate training, apprenticeship training and career training with the implementation of a pedagogic method of training, fully adapted to the specific needs of a port.     

Is Somali piracy a random phenomenon?

This paper investigates whether Somali piracy is a random phenomenon. The investigation takes place in two distinct parts. Its statistical analysis spans over a period of 11 years, from 2000 until 2011 for the first part (flags), and 5 years, from 2007 until 2011 for the second one (crews). The reason is that although prior to 2007 there have been a substantial number of attacks (parameter used in the first part of the research), very few ships were practically pirated (parameter used in the second part) within the same period. Firstly, it is widely believed that Somali pirates select their targets at random and the decision on attacking a vessel registered under a particular flag is unrelated to the participation of the flag state in any of the naval forces operating around the Horn of Africa. The enquiry attempts to assess whether these two common beliefs are supported by historical data and to what extent. Secondly, this paper asks whether there are certain nationalities of crews which are for ethnic and/or cultural reasons more (or less) vulnerable to fall victims of pirates off Somalia. Such groups (if there are any) would in effect indirectly ‘support’ Somali piracy, and for this reason, they could be considered as ‘passively supportive crews’. The analysis focuses on the crew composition of the attacked vessels with special interest cast upon those ships (meaning the crews) which eventually succumbed to Somali pirates and were in the end seajacked.