The dynamic relationships between paper petroleum refining and physical trade of crude oil into the United States

This article examines the relationship between refinery margins traded on paper using petroleum futures (the paper refinery) and the physical trade of crude oil into the US. Computations of a 3:2:1 crack spread were constructed using daily observations of second- and third-nearby unleaded gasoline and heating oil futures contracts traded on the New York Mercantile Exchange (NY MEX) and spot Brent crude oil prices. The crack spread represents the margin between the cost of crude oil feed stock today and the value of the products produced by a refinery in the future. Unit root tests on each of the time series found crack spreads to be stationary while crude oil imports were found to be non-stationary. A s the two series were found to be integrated of different order, cointegration analysis of the two series was not deemed appropriate. Instead, linear relationships between crack spreads and imports were examined using causality tests. It was found that the 2-month 3:2:1 crack spread Granger-causes crude oil imports and that this causality is unidirectional. The significance of these findings lies in the fact that other industries like tanker shipping derive their demand from the demand for, and trade in, petroleum. Crack spreads, therefore, can provide a leading indicator for short term developments in tanker demand. For a chartering manager who has ships on the spot market, crack spreads can help him/her anticipate demand developments and influence vessel deployment and chartering decisions.     

Some Thoughts on Flags of Convenience

The purpose of this article is to formulate the problem, to assess its magnitude, and at the same time to suggest the areas that must be investigated before any practical policy recommendations can be made.     

On the application of hydraulic theory to the deep-water flow through the Irbe Strait

A flow-dependent critical-point method for investigating topographically controlled flow in natural channels is applied to the bottom current through the Irbe Strait connecting the Baltic proper and the Gulf of Riga. This approach is based on the functional formalism due to Gill [Gill, A.E., 1977. The hydraulics of rotating-channel flow. J. Fluid Mech., 80, 641–671.], and here is used for the stratified flow structure observed during the IRBEX-95 field campaign. A critical section of the realizable flow regime was found to be located slightly downstream of the most pronounced horizontal constriction of the channel. The predicted baroclinic volume flux 7200 m³ s⁻¹ overestimates the observed mean bottom-water transport by around 30%, a discrepancy which most likely can be explained by the lack of sea level conditions and friction in the model.     

Route choice of cyclists in Zurich

This paper presents the first route choice model for bicyclists estimated from a large sample of GPS observations and overcomes the limitations inherent in the generally employed stated preference approach. It employs an improved mode detection algorithm for GPS post-processing to determine trips made by bicycle, which are map matched to an enriched street network. The alternatives are generated as a random sample from an exhaustive, but constrained search. Accounting for the similarity between the alternatives with the path-size factor the MNL estimates show that the elasticity with regards to trip length is nearly four times larger than that with respect to the share of bike paths. The elasticity with respect to the product of length and maximum gradient of the route is small. No other variable describing the routes had an impact. The heterogeneity of the cyclists is captured through interaction terms formulated on their average behaviour.     

Ballast Water Treatment systems: “Old” and “New” ones

This paper offers an overview of the currently available Ballast Water Treatment systems, their efficacy in reducing the number of organisms in relation with the IMO and other, future standards, and explores potentially new and promising technologies and current gaps.     

Location of bus garages

The location of bus garages is a complex issue that has received recent attention in the literature. Given a bus system, the number of bus garages and their locations depend on garage cost, deadheading cost and environmental impacts. An approximate analytical model is used to determine the number of bus garages that minimizes the above costs. The concept of a slowly varying density of bus-route origins (hence deadheads) per unit area is used to model deadheading costs. The increased deadheading caused by breakdowns and accidents is also considered. The garage cost is modeled as a function of the number of buses stored. A closed-form solution is obtained for the optimal density of garages, when the garage cost function is linear. The actual locations of garages and the allocations of buses to the garages are found using a discrete space location-allocation model formulated so as to consider the environmental impact associated with buses deadheading through populated neighborhoods.     

Towards comfort-optimal trajectory planning and control

ABSTRACT

This paper describes a method to analyse and evaluate different trajectory planning methods and controller types for usage in automated vehicles. Its application is shown by using a novel trajectory planning approach considering comfort aspects (based on Rapidly Exploring Random Tree (RRT)), two different controllers to follow the planned path (cascade controller and flatness based controller) and a simulation method to obtain resulting lateral vehicle accelerations. The method is used to plan and drive a trajectory through a roundabout. It can be seen that the lateral accelerations of the controller-driven vehicle are in the range of the values used for planning. However, the results of both controllers show differences in lateral deviation and in smoothness of lateral accelerations. The simulation results are then compared to real-world test drives in the same roundabout. The measured lateral accelerations are in the same range as well but show a smoother progression than the two controller models.