Improvement of exhaust gas pressure’s utilization for compressing the intake air in diesel engine’s cylinders

In order to improve the economical and environmental performances of the Diesel engines, the present paper aims to bring to the forefront solutions to increase the efficiency of the supercharging process carried out by the aggregates with Comprex type pressure waves. One solution to this is to drive the Comprex, not by the supercharged engine as it currently happens, but by a DC motor. The speed of the electric motor is modified, by means of an electronic management system, depending on the speed and load of the Diesel engine. The paper presents the experimental results obtained during the investigation of a supercharged Diesel engine by the Comprex driven type according to the proposed solution.     

Maritime interests in the EU policy-making: Structures,practices, and governability of collective action

Throughout Europe, a number of maritime interests have re-targeted their lobbying structures and strategies aiming to influence the development of the maritime related European Union (EU) policies. The paper examines these maritime interests’ mobilisation in the making of the Common EU Maritime Transport Policy (CMTP). First, it provides a review of the role of these interest groups and the implications of the observed collective interests’ representation. Then, with the contribution a data-set of replies to a questionnaire distributed to all the interest groups that are involved in EU maritime affairs, the paper analyses the variety of interest groups representing the maritime sector in EU affairs. The focus is on the structures (i.e. membership numbers and types, location, internal structures, budget) and the lobbying practices of the 37 identified EU level maritime related organisations. The paper also presents an evaluation of the most positive and most negative parameters of the ‘EU environment’ and the ‘economic environment’ that assist, or undermine, the governability cohesiveness of this collective action. This study provides information on whether and under what conditions maritime interests are able to form comprehensive EU-level organisations capable of representing their members and their interests in the EU policy making process     

An interpretation of inter-container port relationships from the demand perspective

Container ports serve as important conduits to facilitate the efficient flow of containerized cargo. As part of value-driven chain systems that intersect between hinterlands, efficiency gains that are generated within the container port will have a direct impact on the competitive advantage of its users and affect the economic potential of both the origin and destination hinterlands. As such, the paper proposes the usage of indifference analysis propounded in microeconomic theory as a useful means to examine inter-container port competition and complementarity. The framework presented can also be combined with Porter's 'Diamond' model in order for inter-container port demand relationships to be quantified, measured and analysed in an holistic manner. Apart from analysing inter-port relationships from the standpoint of container ports, the framework can also be used to analyse inter-port relationships from the perspective of other key players in the value-driven chain system and modified accordingly to incorporate various indicators that are deemed to be relevant to these parties.     

垂直及斜出水流场的二维及三维TR-PIV试验

本文对钝头回转体垂直及斜出水流场采用TR-(Time-Resolved)PIV技术进行测量,并对斜出水流场进行3D-Stereo PIV(三维体视 PIV)测量.文中介绍了测试技术及测量结果,揭示了出水过程中流动结构及其演变,展示了TR-PIV技术对具有瞬态历程特征的出水流场研究的适应性.     

Long-term changes of inorganic nutrients in the Lagoon of Venice (Italy)

The paper aims at investigating the trends of the concentrations of dissolved inorganic nitrogen (DIN) and phosphorous in the Lagoon of Venice, Italy, in the last 35 years. The trend analysis of ammonia nitrogen, nitrate nitrogen and reactive phosphorus (RP) yielded rather different results. The decrease in ammonia nitrogen concentration, in particular, in the basin influenced by severe industrial discharges, is accurately described by a negative exponential model. The nitrate concentration did not show significant interannual trends, while wide seasonal variations have been detected. Reactive phosphorus concentration increased until the end of the 1970s at the stations close to the industrial area as well as in those influenced by river discharges and by sewages of the city of Venice. The sudden decrease that followed was most likely related with environmental policies, namely the improvement of wastewater purification treatments and the regulation of phosphorus use in detergents.     

An approach to estimating the hull girder response of a ship due to springing

This article describes an estimation method for the hull girder response of a ship due to springing. The linear and nonlinear springing effects on the hull girder are evaluated. Previous studies on the springing response focused mainly on the symmetric response, or vertical response. In this article, however, the springing analysis is extended to asymmetric responses, or horizontal and torsional responses. The Timoshenko beam model was used to calculate the hull girder response and the quadratic strip method was employed to calculate hydrodynamic forces and moments on the hull. To remove irregular frequencies, a rigid lid was adopted on the hull free surface level and hydrodynamic coefficients were interpolated for asymptotic values. Applications to two ships for the symmetric and asymmetric responses were carried out and the effect of springing responses is also discussed.     

Dynamic analysis of a pantograph-catenary system using absolute nodal coordinates

The dynamic interaction between the catenary and the pantographs of high-speed trains is a very important factor that affects the stable electric power supply. In order to design a reliable current collection system, a multibody simulation model can provide an efficient and economical method to analyze the dynamic behavior of the catenary and pantograph. In this article, a dynamic analysis method for a pantograph-catenary system for a high-speed train is presented, employing absolute nodal coordinates and rigid body reference coordinates. The highly flexible catenary is modeled using a nonlinear continuous beam element, which is based on an absolute nodal coordinate formulation. The pantograph is modeled as a rigid multibody system. The analysis results are compared with experimental data obtained from a running high-speed train. In addition, using a derived system equation of motion, the calculation method for the dynamic stress in the catenary conductor is presented. This study may have significance in providing an example that a structural and multibody dynamics model can be unified into one numerical system.     

US Navy Studies on Alternative Fuel Sources and Power and Propulsion Methods for Surface Combatants and Amphibious Warfare Ships

The US Navy has been studying the technical and cost impacts associated with the availability and cost of fossil fuel contrasted with nuclear energy alternatives for surface combatants and amphibious warfare ships. Over the past 2 years these efforts have grown in maturity to examine the tactical and strategic implications of our Navy's dependence on fossil fuels from technical, economic, and military perspectives. This paper will present three major topics:

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  Background research on alternative energy sources.
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  A survey discussion of current and future power and propulsion system technologies.
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  An overview of principal Naval Sea Systems Command studies on the integration of alternative power and propulsion system technologies into notional surface combatants, submarines, and amphibious warfare ships.

Given the US Navy's dependence on fossil fuels and the expected increase in cost and reduced availability of fossil fuel, propulsion system investment decisions made today will have a profound impact on the future tactical and strategic roles of the US Navy surface fleet. This paper lays the foundation for providing robust and flexible technology decision opportunities for the Navy's future.     

Stabilization Control for Rider-Motorcycle Model in Hamiltonian Form

This study deals with dynamics and control of a rider-motorcycle system model in Hamiltonian form. The model is established to account for not only the motorcycle dynamics but also changes in rider's postures. Tyre forces are treated as external forces and rider's control actions contain three actuation torques. The Hamiltonian system is subject to dissipation effects due to tyre forces and rider's control torques. In addition to the total Hamiltonian, a generalized free energy is employed in formulation. Lyapunov's second method provides sufficient conditions for stability. Variable structure system (VSS) control is used to account for stabilization control exerted by the rider. Simulation results validate the proposed method.