Two-Vehicle Collision Reconstruction : A Rational, Computer-Aided Approach

Methods are presented for predicting either initial speeds or impact locations for two inelastic vehicles on a collision course. Forty system parameters are distinguished, of which up to 35 can be deduced with varying degrees of accuracy from post-collision data. The remaining parameters are calculated using the conservation laws of linear momentum, angular momentum, and energy. Essential ingredients of this analysis are the plastic impact deformation energies and the friction work along the post impact trajectories. Examples of central impact and computer-aided studies for oblique impact illustrate how vehicle speed predictions vary within the bounds of uncertain accident data.     

The costs and benefits of reducing SO2 emissions from ships in the US West Coastal waters

Potential costs and benefits of policy options for reducing offshore ship pollution are examined using a meta-analysis of studies synthesized regionally for the US West Coast. Net benefits of reducing SO₂ emissions from cargo ships in the US West Coast waters are found to range between $98 million and $284 million, annually; the benefit–cost ratio varies between 1.8 and 3.36, depending on the size of the control area and the sulfur content limit. The results show that about 21,000 tons of on-land equivalent SO₂ emissions or about 33% of SO₂ emissions from all mobile sources in California in 2005 can be reduced annually if the US West Coast exclusive economic zone is designated as an International Maritime Organization-compliant SO_x emission control area (SECA) with fuel-sulfur content not exceeding 1.5%. The analysis demonstrates that designating this area reduces more emissions than establishing a smaller zone at a lower but favorable benefit-cost ratio. Control measures that require 0.5% low-sulfur fuels reduce more SO₂ emissions, and also may have higher net benefits. Technological alternatives may achieve benefits of emissions reductions on the US West Coast across higher ranges of potential fuel prices. Combinations of fuel switching and control technology strategies provide the most cost-effective benefits from SECAs on the US West Coast and other world regions.     

Airport taxi service regulation: An analysis of an exclusive contract

Taxi service at a number of major airports is supplied by one taxi company under an exclusive contract with the airport operating authority. Conventional wisdom suggests that airport taxi service produced under exclusive contract is socially inefficient. This was found to be true at the Dallas/Fort Worth Airport. In this paper we analyze the exclusive airport taxi service at Honolulu International Airport as a case study. At Honolulu International Airport, the terms of the exclusive airport taxi service contract are far less restrictive than those at Dallas/Fort Worth. Our analysis indicates that exclusive airport service can provide high quality service, reasonable prices and revenues to finance airport service. We conclude that is not the exclusivity, but rather the terms of the contract and the circumstances specific to each market that determines which system is best for a particular place.     

顶部驱动技术向前推进

更强有力的顶部驱动和革新的下套管技术一包括液体冷却、永磁式同步电机一正在帮助钻井人员在印度海上执行任务     

Prediction of ship steering capabilities with a fully nonlinear ship motion model. Part 1: Maneuvering in calm water

This paper introduces a new method for the prediction of ship maneuvering capabilities. The new method is added to a nonlinear six-degrees-of-freedom ship motion model named the digital, self-consistent ship experimental laboratory (DiSSEL). Based on the first principles of physics, when the ship is steered, the additional surge and sway forces and the yaw moment from the deflected rudder are computed. The rudder forces and moments are computed using rudder parameters such as the rudder area and the local flow velocity at the rudder, which includes contributions from the ship velocity and the propeller slipstream. The rudder forces and moments are added to the forces and moments on the hull, which are used to predict the motion of the ship in DiSSEL. The resulting motions of the ship influence the inflow into the rudder and thereby influence the force and moment on the rudder at each time step. The roll moment and resulting heel angle on the ship as it maneuvers are also predicted. Calm water turning circle predictions are presented and correlated with model test data for NSWCCD model 5514, a pre-contract DDG-51 hull form. Good correlations are shown for both the turning circle track and the heel angle of the model during the turn. The prediction for a ship maneuvering in incident waves will be presented in Part 2. DiSSEL can be applied for any arbitrary hull geometry. No empirical parameterization is used, except for the influence of the propeller slipstream on the rudder, which is included using a flow acceleration factor.     

Measurements of Emissions to Air from a Marine Engine Fueled by Methanol

Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for ...     

Cost escalations in the front-end of projects – empirical evidence from Norwegian road projects

This paper investigates an issue largely ignored in the transport literature on cost overruns, namely, cost increases in the early project phase, long before the decision to build is made. This is the phase of project planning that is referred to as the front-end phase in the literature. The rationale of the study is that unless cost estimates during the front-end phase are relatively accurate, the wrong projects may be selected for further development. We first argue for why it is important to address cost escalation during the front-end phase of project planning. We then use Norwegian data to demonstrate the magnitude of cost escalations during the front-end phase of projects and in comparison to the implementation phase. We find that even in a sample of projects with relatively small cost overruns as in the case of Norway, there are substantial cost increases before the formal decision to build was made. This raises the issue of whether decisions and priorities taken at the early stages of project development are based on false information and whether this may lead to the wrong project concepts being selected.     

Using satellite observations of ocean color to categorize the dispersal patterns of river-borne substances in the Gaoping (Kaoping) River, Shelf and Canyon system

Mapping the water constituents from remotely sensed ocean color data enables a better understanding of the dispersal patterns of river-borne substances in the Gaoping (formerly spelled Kaoping) River, Shelf and Canyon (KPRSC) system. Based on twelve MODIS-Aqua images in the KPRSC region taken in 2005, we apply a newly developed GA-SA approach to derive maps of chlorophyll-a concentration (Chl-a), colored dissolved organic matter (CDOM) and non-algal particle/detritus/mineral (NAP). The results demonstrated that the different characteristics of Chl-a, CDOM and NAP make them ideal tracers for observing large-scale dispersal patterns. With ancillary information of averaged daily precipitation, the daily wind field obtained from QuikSCAT (Quick Scatterometer), and the 8-day composite of the temperature field obtained from MODIS-Aqua, we categorized the surface dispersal patterns as coastal, northwestward and frontal patterns. Also, for the first time, we observed a sudden increase of biomass on a large scale from a pair of ocean color images taken over only a 2-day interval. Another remarkable feature is the interaction between the southeastward flow and the intrusion of the Kuroshio Branch, resulting in complicated patterns with various scales of vortex structures and current fronts. The observed features could be used for model validation of the flow field of the KPRSC system.