A macroscopic theory of two-lane rural roads

A macroscopic theory for predicting the operation on two-lane, two-way roads is proposed. In this theory, the interaction between fast and slow vehicles obeys Newell’s kinematic wave theory of moving bottlenecks. Calibration is not required as all parameters are fully observable. Closed-form expressions for the capacity, average speed, percent time spent following and overtaking rates are proposed and the biases of current practice are identified. Comparisons between the proposed theory and empirical data are also included.     

The place of the ISPS Code in the legal international regime

The adoption of the International Ship and Port Facility Security Code (ISPS Code) is the latest response of the international shipping community to the increasing threat posed by acts of terrorism at sea. The ACHILLE LAURO incident of 1985 showed that the traditional law against piracy was not adequate to deal with new types of unlawful acts against international shipping, especially those involving acts of terrorism. The 1988 Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation (SUA Convention) and the technical and administrative measures adopted by the Maritime Safety Committee of IMO in 1986 and 1996 attempted to develop a broader regime to deal with unlawful acts against international shipping.However, the events of September 11, 2001 showed that additional measures were still needed to prevent terrorist attacks against ships.     

Hydrographic cruises off northwest Africa: the Canary Current and the Cape Ghir region

We present hydrographic data for several sections located along the African coastline and off Cape Ghir, carried out at times of weak surface winds (October 1995 and September 1997). The main sections are near the continental slope, at mean distances between 100 and 150 km from the coastline. North of Cape Ghir (31°N) the geostrophic transport (referenced to 650 m) of North Atlantic Central Water through these sections is 3.7 and 2.0 Sv for 1995 and 1997, respectively. This confirms that a major fraction of the water transport by the Canary Current flows east, into the continental slope off northwest Africa, at latitudes above Cape Ghir. Most of this flow continues south past Cape Ghir, along the coast and probably through the eastern passages of the Canary Archipelago. A significant fraction, however, may escape through surface Ekman transport (0.3–0.5 Sv during the early fall season) and by offshore flow at Cape Ghir (1.1 Sv in September 1997, referenced to 650 m). Despite the weak winds the Cape Ghir filament was clearly visible, characterized by localized coastal upwelling associated to a cyclonic shallow structure and cold (and fresh) waters stretching offshore as a very shallow feature (50–100 m deep). The satellite images show that the surface temperature field is highly variable, in rapid response to the surface winds, always with a core region of relatively cold water and commonly with one or two associated eddies. Our results support the existence of two recirculation cells in the area: a horizontal one that connects the interior eastern boundary currents with the coastal region and a vertical one related to both wind-induced and filament upwelling. The data also show a salinity subsurface maximum at the root of the filament, linked to water inflow from northern latitudes, and a subsurface anticyclonic eddy over the Agadir canyon, likely related to the poleward slope undercurrent.     

The simple,compelling case for PRT

When compared with existing urban modes, Personal Rapid Transit (PRT) offers compelling advantages in every important respect. The desirable attributes of any urban mobility mode are well documented, such as minimal travel time, safety, comfort, low cost, and minimal impacts. These attributes are used to define a hypothetical, ideal urban mode. The ideal mode would possess characteristics such as no waiting, no stops, from anywhere to anywhere service, risk-free, non-polluting, and accessible to everyone at any time. Although not attainable in the real world, the ideal provides a model and benchmark for design much as the Carnot thermodynamic cycle guides the development of internal combustion engines, or ideal gases and perfect fluids are postulated in physics. A matrix format is used to present the characteristics of various modes against the desirable attributes of any mode. Modes presented are the ideal, walking, bicycles, motorcycles, automobiles, taxis, buses, rail transit, Automated Guideway Transit (AGT), and PRT. In all respects, PRT is shown to approach the ideal much more closely than competing modes.     

Use of a probabilistic particle tracking model to simulate the Prestige oil spill

A probabilistic particle tracking model is used to simulate the oil dispersion after the Prestige wreckage. This oil spill constitutes a suitable benchmark to analyze the capabilities of a probabilistic model, since the time elapsed from wreckage to oil landing (12 days) is much longer than the reliability time associated with forecast winds, usually on the order of 3–4 days. The particle model can be run in two different modes: real time mode (when existing reliable wind fields for the event under scope) and in probabilistic mode (in absence of reliable wind fields but with historical fields corresponding to a similar period). The validity of the particle model is first evaluated in a hindcast way, running the Prestige case with the wind fields corresponding to the period November 19 to November 30, 2002, which were not available at the moment of the wreckage. Calculations show the accuracy of the model to provide the right impact point and timing. The probabilistic model is then used to simulate the same event by means of historical data. The region where the oil landed is shown to be the area with the highest probability to be impacted.     

A practical assessment of stated preferences methods

Stated preferences data in the form of rankings, ratings and choices were collected in Santiago and discrete choice models estimated with them. The models were compared in terms of accuracy v/s the cost of obtaining the information and models. All methods produced reasonable but different models and fairly close subjective values of time. In terms of production costs the ranking method was a clear looser although the experimental design was slightly biased against it. Finally, the use of computerised interviews is highly recommended particularly for dealing with low income people.     

Using the revenues from congestion pricing

The economic theory behind congestion pricing relies on using the revenues to help compensate highway users. But can practical methods of using revenues come close to achieving this compensation, and still have salient appeal to important political groups? This paper investigates the possibilities for designing a package of revenue uses that can achieve these twin goals. The suggested approach returns two-thirds of the revenues to travelers through travel allowances and tax reductions, and uses the rest to improve transportation throughout the area, including affected business centers. By replacing regressive sales and fuel taxes, this approach offsets the tendency of the prices alone to have a regressive distributional impact. By lowering taxes, funding new highways, improving transit, and upgrading business centers, the package provides inducements for support from several key interest groups. The potential amounts of money involved are discussed using nationwide data, and in more detail using a case study of ubiquitous facility pricing throughout the Los Angeles region. Illustrative calculations of the effects on various individuals confirm that such a package can create net benefits for a wide spectrum of people and interest groups.     

内破裂的数值模拟与分析

应用气—波两相流理论，引入计算流体动力学方法中的SIMPLE（Semi—ImplictMethodforPressure－LinkedEquations）方程，并在此基础上进行改进，对压力筒内的内破裂现象进行了系统的研究。本文发展了一套不依赖于试验结果的预报方法，较之以前的理论研究结果有了长足的进展，所采用的模型与假设能用于多种内破裂状况的模拟与预报。本文对一典型的内破状态进行了数值模拟，结合物理现象对模拟结果进行了分析，并与试验作比较。分析结果以一组计算机所绘图形表示，输出结果可作为压力筒结构动力分析的基础，所研制的程序也可作为内破裂问题流—固耦合研究的一大模块。     

Simulation Approach to the Effect of the Ratio Changing Speed of a Metal V-Belt CVT on the Vehicle Response

In regard to the belt and pulley system of a metal V-belt CVT, the characteristics of the ratio changing speed is obtained by experiments. It is summarized in a practical and simple experimental equation. By using this equation a simulation model is developed to analyze the response of a vehicle with a metal V-belt CVT to a rapid pulley ratio change. The simulation results are in reasonable agreements with experimental results.