Optimizing the transportation of international container cargoes in Korea

This paper considers a multimodal transportation problem, which is the problem of determining the transportation flow, i.e. volume of container cargoes, and the transportation mode in each trade route, for the objective of minimizing the sum of shipping and inland transportation costs. The problem takes account of two restrictions: maximum cargo volumes capacitated at each seaport and maximum number of vehicles available at each transportation mode. To solve optimally the problem, this paper employs a mixed integer programming, which is an operations research technique. A case study is performed on the container cargo data in Korea and we draw several implications to improve efficiency in the transportation of international trade cargoes in Korea.     

Automatic FE modeler using stiffener-based mesh generation algorithm for ship structural analysis

Shipbuilding industries have started to employ 3D CAD systems to integrate all design and production processes by achieving seamless data transfer and data sharing. The emerging 3D CAD system brings a considerable change in FE analysis field. The availability of 3D geometry increased the recognition of the need for developing automatic FE modeling system consequently.

However, general automatic mesh algorithms developed by academic research field have a limitation. The difficulty in satisfying lots of line constraints and the absence of proper idealization of 3D geometry entities defined in CAD system hinders directly employing the general mesh algorithms.

In this research, an automatic FE modeling system has been developed for cargo hold FE modeling and whole ship FE modeling. The basic concept of the algorithm is to decompose surfaces using stiffener lines into subregions and generate mesh using a rule established based on FE modeling practice of ship structure. Since the decomposed subregions take simple polygon, they can be easily transformed into elements by decomposing the polygon according to the rule defined considering the shape of the polygon and mesh seed on its perimeter. The algorithm is also designed to treat appropriate geometry idealizations for bracket-type surface and stiffener connections. The idealization process is also completely customized based on FE modeling practice. The validity of the developed system is verified through illustrative examples.     

The effect of precession-induced changes in the Mediterranean freshwater budget on circulation at shallow and intermediate depth

The Neogene marine sedimentary record of the Mediterranean basin is characterised by the regular occurrence of organic-rich layers or sapropels. These sapropels are known to correlate with the precession cycle: their deposition coincides with precession minima. This correlation is thought to be caused to a large extent by a precession-induced increase in the amount of freshwater reaching the Mediterranean Sea. In the literature, various sources of this extra freshwater have been identified and different mechanisms as to how this freshwater flux leads to sapropels have been proposed. In this study we investigate the effects of precession-induced changes in the freshwater budget using a regional ocean general circulation model of the Mediterranean Sea. Emphasis is on the effects at the surface and at intermediate depth. The forcing of the ocean model is adjusted to precession minimum conditions on a parameter by parameter basis. Novel to our approach is that the value of the required adjustments is taken from a global coupled climate model with which experiments have been performed for the present day (close to precession maximum) and precession minimum. With the ocean model we focus on the extent to which extra runoff from either south (specifically: the river Nile) or north and changes in net precipitation over the sea itself lead to a more stable stratification; this we judge by the associated reduction of the sea surface salinity and mixed layer depth in the regions of intermediate and deep water formation. Our main finding is that the effects of (1) increased discharge of the rivers coming from the north, and (2) the increase in net precipitation over the sea itself, are of equal or greater importance than that of increase in Nile discharge.     

Intelligent Tools Used in the Design of Navy Ships

The first step in implementing an intelligent ship is designing the ship intelligently. Naval ship design is becoming an interactive process where designers on different sites can work collaboratively and simultaneously, connected through virtual design environments. In this paper we introduce two such design environments. The first is an immersive, virtual reality environment enabling rapid design of ship space arrangements, exploration of Human System Integration issues, and reduced cost of test and evaluation through the use of modeling and simulation. The second is a systems engineering application capable of evaluating the benefit of spiral technology insertions, identifying areas for research and development investment, and evaluating the performance, risk, and affordability of proposed technologies in current and future ship systems, by conducting trade space analysis and optimization. Applications of these tools will be discussed.     

An Alternative Method to Determine the Magic Tyre Model Parameters Using Genetic Algorithms

Summary Tyre behavior plays an important role in vehicle dynamics research. Knowledge of tyre properties is necessary to properly design vehicle components and advance control system. For that purpose mathematical models of the tyre are being used in vehicle simulation models. The Magic Formula Tyre Model is a semi-empirical tyre model which describes tyre behavior quite accurately. The Magic Formula Tyre Model needs a set of parameters to describe the tyre properties; the determination of these parameters is dealt with in this paper. A new method based on genetic techniques is used to determine these parameters. The main advantages of the method are its simplicity of implementation and its fast convergence to optimal solution, with no need of deep knowledge of the searching space. So to start the search, it is not necessary to know a set of starting values of the Magic Formula parameters. The comparison between analytical optimization methods and the method proposed is discussed in this paper.     

“2007线路机械”展览交易会介绍

例行的第13届国际交易展览会“2007线路机械”在卡卢加顺利结束。100多家俄罗斯企业和单位，以及20多家国外公司在展览会上展出了高生产率的线路机械和现代化的全套铁路养路机械设备。整个俄罗斯铁路系统工务部门的领导、线路机械制造企业的代表以及俄罗斯的邻国和其他国家的专家参与了展览会的工作。     

A 3D finite-element model of the Adriatic tides

A 3D finite-element numerical model is applied to the Adriatic Sea to simulate its tidal motions. This fully nonlinear model includes a free surface, very realistic topography, and an advanced turbulence closure. Comparison with available tidal elevations at coastal stations and with tidal ellipses at a few locations in the open sea demonstrates that the model simulations are highly accurate. The results are then used to determine the 3D distribution of the tidal residual currents.     

Improving the Performance of Loop-Sensor-Based Traffic-Information System by (M+PLL) Circuit

Conventionally a phase-shift detection method (PSDM) and a frequency-shift detection method (FSDM) have been used in loop detectors. The PSDM has a fast response time and is very effective in detecting vehicles traveling at normal speeds. However, it is well known that the detection results are erroneous for vehicles traveling at low speeds in heavy traffic conditions. On the other hand, the FSDM greatly improves the detector performance for heavy traffic conditions. However, this method is not effective in fast and normal traffic conditions. Thus, in order to collect accurate traffic data for all traffic conditions, this paper proposes combining two methods using the digital OR logic. In the developed circuit, a phase-locked loop (PLL) circuit is used for measuring the phase change. This paper also develops a new loop detector instrumentation method using the so-called M circuit for detecting frequency change. The developed method has been tested for various traffic conditions. Experimental results show that the new combined M and PLL detection method greatly improves the accuracy in all traffic conditions, reducing the error rate in measuring traffic flow by more than 83%, when compared to the PSDM.     

铁路噪声对沿线居民影响的研究

分析了铁路沿线居民对噪声的反应，并比较了铁路与交通运输噪声主观反应。结果表明，无论是高干扰率阈值的比较，或是从高干拢率与声级的回归方程比较，铁路和交通这两种运输噪声对人的主观反应干扰基本一样。     

Introduction of a friction coefficient dependent on the slip in the FastSim algorithm

One of the main limitations of algorithms relating forces and creepages at the wheel/rail contact is the use of a friction coefficient independent of the slip. This paper overcomes this limitation through a modification of the FastSim algorithm (based on the Simplified Theory of Kalker). A friction law based on the local value of the slip is established and the required formulation of the local slip elsewhere in the contact area is presented. Some difficulties of the method and the solutions adopted by the authors are also presented. Finally, the achieved improvements are shown through comparison of the results obtained both with the original and the modified FastSim algorithms.