瑞士联邦铁路客运车队的机车车辆

瑞士联邦铁路(SBB)现有客运车队的机车车辆类型极多,除了现代大功率机车、摆式列车、低地板车辆和客车外,还包括在这期间作了改进的旧系列机车车辆.今后的采购政策首先是购置新的区间列车.     

China' maritime developments

Development of ports and shipping in China are continuing at a phenomenal pace. They are now entering a second phase in these developments. With basic capacity to handle China's growing foreign trade established. China's ports and shipping are now being ratinalized in terms of inland infrastructure and intermodal networks, optimum trade flows, foreign alliances, and physical forms or consolidation of cargo. These developments are driven by the lack of a large, deep water ocean fleet on one hand and limited water depths at many major ports. Similarly, the extension of economic development to the inland ports of China has become a priority as has the effective integration of Hong Kong and gradual opening of direct shipping across the Taiwan Straits.     

The change in soil cover on the exposed bed of the Aral Sea

Desiccation of the Aral Sea has led to the formation of new soil cover on the exposed seabed. Investigation of the newly formed dry land is very important since it is a source of dust storms and salts transferred to long distances. A soil map of the exposed seabed for 2000 has been produced on the basis of the map for the year 1990 (Institute of Soil Science, Uzbekistan), satellite images, and selected field observations of groundwater table. During the period 1990–2000, the sea recessed 20–32 km, thus changing the soil cover characteristics. The maps of soil cover with the detailed information on soil textures, the characterization of soil types, the soil formation trends, and the changes in soil types during the sea recession process are available. Attention has been paid to erosion tendencies and susceptibility to dust and salt transfers. As a whole, the soil cover was formed as a result of the replacement of excessive wetlands (salt-marsh), located in the form of strip along the sea, by hydromorphic and semi-hydromorphic, semi-automorphic and automorphic soils. The drying seabed has complicated lithological and morphologic composition. The territory of the exposed seabed is characterized by different hydrological conditions. Groundwater depth varies from 0.5 to 10 m. With the shore's recession, the water storage groundwater is approaching the surface. With general tendency towards desertification, the initial soil cover changes. The soils that did not reach the complete genetic formation, under the influence of quickly changing hydrogeological conditions, are transformed into the other types and subtypes. Often, while becoming dry, they are self-destructed and change into sands. Currently, the following types of soils are observed on the exposed seabed: automorphic solonchaks, semi-automorphic solonchaks, semi-hydromorphic solonchaks, hydromorphic solonchaks, desert sandy soils, sands.     

Shipping freight derivatives: a survey of recent evidence

In an industry that is characterized by highly volatile prices, seasonality, strong business cycles, cyclicality and capital intensiveness, risk management is extremely important. Ship-owners and charterers face enormous risks, which emanate from fluctuations in freight rates, bunker prices, interest rates, foreign exchange rates and vessel values. These risks substantially affect the interplay between revenue and cost. Modern risk management techniques, involve the use of financial derivatives products, some of which have been developed exclusively for protecting (hedging) against the adverse price fluctuations of the aforementioned sources of risk in shipping. By using derivatives products, ship-owners and charterers can secure (stabilize) the level of their future income or costs and thus reduce uncertainty and unforeseen volatility of their cash-flow. To explore the importance of hedging freight rate risk in shipping operations, a survey of recent empirical evidence that has appeared in economic studies has been conducted. Developments over the past 20 years have been fast, with certain amount of research carried, which has helped to understand better the special features of these derivatives markets. They are all summarized in the current study, which can provide the stepping stone for further work in the area of shipping derivatives and risk management in shipping.     

Bigger vessels: How big is too big?

Growth in container liner traffic has been high for several decades and current growth rates are expected to continue, putting pressure on ports and liner companies to increase investment. Several factors are pushing up the capacity of new buildings, and bigger, rather than more, ships alleviate pressure on ports. But ship operating cost benefits will be eroded unless cargo handling performance can be upgraded. Because of physical inhibitions in existing facilities the recent pace at which lines have increased the size of the biggest ships operating seems likely to plateau in the next few years.     

Power Spectral Density of Road Profiles

The road profile is usually considered to be a random process x ( d ), where x is the road height and d is the distance along the road. As the vehicle travels along the road with velocity v , the random process x ( d ) is converted to a random process x ( t ) which is input to the vehicle suspension via the tyre. The random process x ( d ) is usually described in terms of its power spectral density as a function of frequency in either radians or cycles per unit distance. However, there are several different ways of defining power spectral density, and this makes it difficult to compare published data without knowing how the power spectral density has been defined. The proper calculation of RMS values of vehicle response for an assumed road power spectral density is explained by an example.     

Rail line length in a crosstown corridor with many-to-many demand

An analytical model that determines the optimal location and length of rail line along a crosstown transportation corridor with the objective of minimizing the total transportation cost is presented. A general, many-to-many passenger demand pattern is considered. The objective function, which includes the rail and bus riding costs, rail and bus operating costs, rail fleet costs and rail line costs, is minimized by using the classical optimization method with the aid of a computer program developed for the model. The model is applied to the Northwest-South transportation corridor in Calgary, Alberta, and the sensitivity of the optimal rail line location and length to the unit cost and demand parameters at their reasonable ranges is tested. It is found that although the total passenger demand, unit rail line cost, and unit bus operating cost have greater influence than the unit bus and rail riding costs, and unit rail fleet and operating costs, the optimal line length is generally insensitive to all these parameters. It is also found that the length of the existing LRT line in the corridor is comparable to the optimal line length obtained from the model, but the existing line should be extended further south in order to meet the heavier demand in that direction optimally.     

Examining the effect of life course events on modality type and the moderating influence of life stage

Transportation - Previous research has demonstrated the relevance of life events to explain changes in travel behavior. Less clear is the moderating role played by life stages on the relationship...     

Numerical Study of the Transition Between Reentrant Jet and Twin Vortex Flow Regimes in Ventilated Cavitation

Contrary to natural cavitation, ventilated cavitation is controllable and is not harmful. It is particularly used to reduce the drag of the hydraulic vehicles. The ventilated cavitation is characterized by various gas regimes. The mechanisms of ventilated cavitation are investigated in the present work with CFD based on a 2D solver. The attention is especially focused on the transition between the reentrant jet and twin vortex regimes. The results confirm that the product of ventilated cavitation number and Froude number is lower than 1 (σ_cFr?<?1) in the twin vortex regime, while it is higher than 1 (σ_cFr?>?1) in the reentrant jet regime, as reported in the literature. Further analysis shows that ventilated cavitation is significantly influenced by the natural cavitation number.