Influence of shock absorber wearing on vehicle brake performance

In order to safely maintain a vehicle, it is necessary to verify the most important systems that affect safety during Periodic Motor Vehicle Inspections (PMVIs). In a previous paper, a test method and validation criteria were suggested by the authors to verify shock absorber status during PMVIs, as they are a fundamental component that may wear out during a vehicle’s life. In this paper, variations of the performance of the vehicle’s brakes resulting from shock absorber wearing have been analyzed, in order to confirm whether the suggested criteria is valid for taking into account longitudinal forces and pitch movement on the vehicle. A simulation-based study was conducted with several configurations of a worn damper on a vehicle driving on two virtual roads: smooth and undulating. The results confirmed that the damping coefficient established as an acceptable value to verify the shock absorber status in PMVIs is also valid considering the forces involved in a braking maneuver.     

Communicating and learning maritime safety culture—development and evaluation of a didactic design based on an interactive module

To be able to disseminate knowledge about maritime safety culture and safety management to different actors in the Swedish maritime sector, a didactic design was developed and evaluated. The didactic design includes an interactive scenario-based module and a teacher’s guide and is based on a model for experience-based learning that connects theory and practice by a cyclic approach. Students at upper-secondary maritime schools were chosen as a user group and the didactic design was adapted for them. The didactic design was tested in a classroom setting including interaction with the students and a follow-up 1 week later. The didactic design was successful in immediately creating a relevant discussion about safety culture, and the student group could, on the whole, remember and describe all scenarios a week after the presentation of the material. The results were overall positive regarding usability and user experience with a potential for further development and implementations. The participating teacher at the school was also very positive and felt he would be able to apply the didactic design with support of the teacher’s guide.     

The method of imbedded Lagrangian element to estimate wave power absorption by some submerged devices

A simple approach is described to estimate the wave power absorption potential of submerged devices known to cause wave focusing and flow enhancement. In particular, the presence of a flow-through power take-off （PTO） system, such as low-head turbines, can be accounted for. The wave radiation characteristics of an appropriately selected Lagrangian element （LE） in the fluid domain are first determined. In the limit of a vanishing mass, the LE reduces to a patch of distributed normal dipoles. The hydrodynamic coefficients of this virtual object are then input in a standard equation of motion where the effect of the PTO can be represented, for example, as a dashpot damping term. The process is illustrated for a class of devices recently proposed by Carter and Ertekin （2011）, although in a simplified form. Favorable wave power absorption is shown for large ratios of the LE wave radiation coefficient over the LE added mass coefficient. Under optimal conditions, the relative flow reduction from the PTO theoretically lies between 0.50 and 1 2 ≈ 0.71, with lower values corresponding to better configurations. Wave power capture widths, the sensitivity of results to PTO damping and sample spectral calculations at a typical site in Hawaiian waters are proposed to further illustrate the versatility of the method.     

Incentives to reduce port inefficiency: a theoretical approach

Over the last decades, the European Union (EU) has devoted a large amount of effort and money to projects aimed at boosting some of its maritime corridors as a modal alternative to road or rail freight transport. However, the overall design of most of these programmes has ex post revealed as very ineffective. This paper suggests that promoting port efficiency might be a more suitable target to increase the modal split of Short Sea Shipping (SSS) than subsidizing firms to transfer cargo from road to sea. But defining ‘port efficiency’ is a complex task and, therefore, granting money directly to port authorities could also generate perverse moral hazard effects, particularly when the improvements are difficult to monitor and many investments are non-refundable. The European Court of Auditors points out that millions of EU public port finance was wasted on empty terminal and other unused infrastructure. The objective of this paper is to design a proper subsidy to promote SSS by encouraging port improvements through a proper system of incentives. As a policy recommendation, in this paper we propose the development of a subsidy per inefficiency-reduction unit.     

TransMilenio BRT system in Bogota,high performance and positive impact – Main results of an ex-post evaluation

The paper presents the main characteristics, costs and impacts of TransMilenio, the bus based mass transit system of Bogotá, using BRT corridors and feeder services. An ex-post cost-benefit analysis is done, including monetary valuation of direct impacts on travel time and travel cost and externalities, such as improved road safety and air quality. Impacts on crime, land values, employment and tax revenue are also presented. The results are positive and robust; nevertheless, it is important to recognize that user perception has declined and there is urgent need to introduce service improvements. The paper also includes an ex-ante evaluation of the projected expansion using current costs, which indicates the need to limit construction capital costs. The results are an indication of the potential of BRT, and the evaluation methodology is applicable to other transit projects.     

Indicators for Evaluating the Impact of Artificial Islands on the Barcelona Coast

Artificial islands have been constructed next to large cities due to the need for extra space in highly populated areas. These emerged structures have been used by many countries as platforms for developing infrastructure (airports, harbors, highways, etc.), rebuilding ecological areas, and creating new spaces for tourism or residential areas. In this study, two state-of-the-art numerical models for wave propagation and nearshore circulation are used to simulate the effects of an emerged artificial island on the Barcelona coast. Several sea indicators (wave height, intensity and direction of currents, and mean water level) are analyzed to assess the changes likely to be induced by an artificial island. Three different situations are studied and the indicators are compared across the different tests to obtain information that can be used in the planning process of these structures. In two-meter wave conditions, the tests show that wave height is generally reduced in the sheltered area, which leads to improved safety for beach users (bathing is prohibited when wave height exceeds the two-meter threshold). However, the numerical models also reveal that velocities in the sheltered area usually decrease, which must be controlled to prevent stagnation in the bathing area.     

Land use implications of sea level rise: A case study at myrtle beach,South Carolina

Abstract

the prospect of global warming and consequent sea level rise will have important implications for coastal communities. this article examines the land use implications of alternate sea level rise scenarios on the city of myrtle beach, south carolina. current trends as well as high and low sea level rise scenarios are superimposed on the city's beach profile and near shore contours to estimate the type and value of land development likely to be impacted.

It is found that losses associated with accelerated sea level rise would be particularly high in the city's hotel district and that overall property loss could range from 21 to 60% of the city's total property value. to lessen these potential losses, coastal communities such as myrtle beach must choose among one of three policy options including: (1) barricade the beach, (2) raise the land, and (3) implement a strategic retreat. specific alternatives within each of these options are explored in turn. the article concludes that successful development plans will incorporate ground rules sensitive to and consistent with dynamic coastal processes.     

Contributions to maritime economics—Zenon S. Zannetos,the theory of oil tankship rates

This paper discusses the importance of Zannetos’ 1966 book for the development of maritime economic thought. The main contributions of the book are recounted, and the empirical work in the book is reviewed.

The analysis of the present paper is a citation research on the maritime economics literature that refers to the book. Of the 42 papers in the set, about one-third refers to the book in general. A total of 35 papers refer to one or more elements of the book, with an equal number of references to: (1) the term structure of freight rates; (2) the empirical findings on the form of the supply curve; and (3) on the verification of his results.

The general conclusion of the citation analysis is that, apparently, a number of elements of his work are still very valid for current maritime economics thinking, while maritime economists have disregarded several other elements. The latter seems unjustified for some of the business structure observations that are made in the book, such as the notion that the ship is the firm, and the elasticity of expectations. The former observation is the basis for virtually all empirical work in maritime economics that is based on individual contract data (all freight rate analysis is of this nature), and the second is the basis for the analysis of investment behaviour in shipping, investigations of cyclicality and so on.

Zannetos can definitely be seen as the initiator of the important field of term structure analysis in maritime economics. In addition to this, there are several topics in the 1966 book that are as yet unexplored, and deserve empirical scrutiny.     

Hub dependence in constrained economies: the case of North Korea

While the geographical and economic factors concerning the development of hub ports are widely described by a variety of scholars and professionals, there is no recognized methodology measuring the hub dependence of a given port, region, or country. Based on a 20-year database of vessel movements, this paper proposes a methodology measuring hub dependence. North Korea offers a good case of a constrained economy facing dramatic internal and external pressures. Notably, the weight and geographical extent of its maritime connections are worth analysing because of its contrasted evolution from Soviet influence, geopolitical isolation, and growing trade due to economic reforms and increased foreign investments. The main results of this study show the spatial shift from long-distance calls to feeder calls: global foreland contraction, regionalization within Northeast Asia, and traffic concentration upon closest hubs of which South Korean ports. We conclude that hub dependence is a combination of local constraints and trade growth. The political implications of this phenomenon are explored, and a spatial model of hub dependence is proposed.     

Manoeuvring and hotelling external costs: enough for alternative energy sources?

Local air pollution is the most relevant externality of maritime transport, and its effects are more acute in urban areas as a result of manoeuvring, hotelling and load/unload activities at ports. This article is intended to assess ships’ local air pollution impact in generally densely populated harbour areas to decide whether alternative power supply measures are feasible. First, an optimized infrastructure investment model is developed to ease implementation and maximize the efficiency of alternative power supply projects. Once target harbours and traffic (ship types) within a national port network have been chosen, a vessel traffic analysis (ship type, tonnage, manoeuvring, and hotelling times) is carried out to quantify and evaluate annual polluting emissions (PM_2,5, SO₂, NOx, and VOCs) and their externalities. Finally, the assessment model is applied and results of the Spanish port network case study are discussed. The results obtained are significant and bring the possibility of further controlling the ship’s environmental performance at berth.