-statistic is the ratio between a normal (0,1) distributed variable and the square root of a centrally distributed chi-square variable divided by its expected value, i.e., its degree of freedom.

This paper evaluates empirically some very common theories of the freight rate generating process in the time charter markets. After a review of the most common assumptions made of the way time charter rates are set, the hypotheses are identified as follows: (a) the Zannetos Hypothesis, (b), the Lagged Zannetos Hypothesis, (c) the Koyck Lag Hypothesis, (d) the Rational Expectation Hypothesis, and (e) the Conventional Wisdom Hypothesis. These hypotheses are tested using statistical cointegration analysis that includes both an Augmented Dickey-Fuller (ADF), and a Johansen likelihood ratio test. Confronted with the data, hypotheses (a) and (b) are rejected outrightly. In the Koyck Lag case, the ADF statistic seem to confirm the hypothesis. A closer look at the numbers reveals that all of the impact on the time charter rates comes from the lagged dependent variable. Hence, the Koyck Lag Hypothesis is rejected. In the Rational Expectation case, the two tests conflicted. Based on the fact that the Rational Expectation Hypothesis includes the lagged dependent variable and that the Johansen test has been found to be a more robust test than the ADF test, the Rational Expectation Hypothesis is rejected. The fifth hypothesis is a reflection of the general bulk industry perception that the time charter rate is impacted by changes in the comparable spot rate and not much by the spot rate levels. In this case both the ADF and the Johansen test accepted the hypothesis for all markets. Thus, the paper concludes that the conventional market explanation of the time charter freight rate setting process is essentially correct-spot rate changes matter spot rate levels do not.     

Collision damage of jack-ups

North Sea collision accident records covering a period of ten years indicate that the risk of collisions involving jack-ups is not dissimilar to that for semi-submersibles or fixed jacket structures. However, jack-ups are much more flexible than jackets and have a much lower degree of redundancy. Their response to collisions and their ability to absorb impact energy is, therefore, expected to be considerably different in comparison to jackets. This paper examines available data and information regarding the capability of jack-ups to withstand collision impacts and investigates the level of local damage that can potentially be caused to jack-up legs due to accidental collisions.     

A 2D long term advection—dispersion model for the Channel and southern North Sea Part B: Transit time and transfer function from Cap de La Hague

A 2D advection-dispersion model, already described and validated, has been used to provide information about water trajectories, transit times, transfer factors and transfer functions in the Channel and North Sea, south of 57 ° N.It shows that a fast vein of water moves parallel to the coast and reaches the northern limit of the model in one year. Along the coast, a few dozen kilometers from this vein, transit times increase by 2–4 months.Tidal gyres in the Channel recirculate waters and dissolved elements for about 2 yr, and in all it generally takes 3 yr for a specific discharge made at La Hague to completely leave the area under study.The transfer factor was depicted and found to be of the order of 10⁻⁵ m.k.s.One utilization of the transfer function could be to predict the future evolution of water content in the months and years following a discharge in these coastal waters.     

Truck backhauling on two terminal networks

Truck backhauling reduces empty truck-miles by having drivers haul loads on trips back to their home terminal. This paper 1) examines the impact on backhauling opportunities of terminal locations and directional imbalances in the flow of freight from the terminals, and 2) develops a method for determining which truckloads should be backhauled. Backhauling is studied for two terminals sending full truckloads to many customers under steady-state conditions. This research develops two backhauling models. The first is a continuous model that makes simplifying assumptions about customer locations and travel distances. It results in formulae showing that 1) savings from backhauling increase at a decreasing rate as the directional flow of freight between two terminals becomes more balanced and 2) backhauling is an important, but often ignored, factor in terminal (e.g. trucking terminal, warehouse, or plant) location and supplier selection decisions. The second model is a more general discrete model that determines which loads should be backhauled to minimize empty truck-miles.     

FLUXMANCHE radiotracers measurements: A contribution to the dynamics of the English Channel and North Sea

From 1986 to 1992, ¹²⁵Sb released by the nuclear fuel reprocessing plant at La Hague has been used to study the transfer of waters from mid-Channel areas towards the Straits of Dover. Since 1940, these investigations have formed part of the MAST 53 FLUXMANCHE programme and have involved repeated measurements on a Straits of Dover transect. A discussion of the results is presented here which takes into account new information provided by a hydrodynamic model developed in the framework of FLUXMANCHE; it combines knowledge of the monthly fluxes of water trough the Straits of Dover and week-by-week simulation of the ¹²⁵Sb activities of waters flowing in this aera. It is proposed that soluble radionuclides introduced into the central Channel are transferred towards the Straits of Dover over a time which varies from four to seven months depending on the route taken.     

Flange Force Effects on the Motion of a Train Wheelset

The motion of a train wheelset is investigated using Hopf bifurcation theory. The method takes full account of the nonlinear effects of the flange-rail contact forces which are incorporated in the model; The numerical solution is obtained over a wide range of forward speeds by transforming the bifurcation problem into a regular nonlinear boundary value problem, which is solved by standard methods. This solution is shown to be orbitally, asymptotically stable. The algorithm supplies complete information on the lateral and yaw motions and on the period of oscillation, even for very high forward speeds.     

Geochemical impacts of waste disposal on the abyssal seafloor

The response of pore water oxygen, nitrate, sulfate, sulfide, ammonium and methane and particulate organic carbon distributions to the input of 8.5 million m³ (3.8×10¹² g) of organic-rich waste materials is simulated. The deposit is assumed to be conical with a maximum thickness of approximately 20 m. Remineralization reactions within the deposit rapidly deplete any initially available pore water oxidants such as oxygen, nitrate and sulfate, and are subsequently dominated by fermentation reactions. Diffusion downward of reduced metabolites, sulfide, ammonium and methane, depletes the available oxidants in the pore waters below the waste pile, increasing the thickness of the anoxic layer. While the impacted region is limited to essentially the deposition site, recovery of the pore waters is estimated to be >10⁴ years. The overall computational results are corroborated by the pore water distributions observed at turbidite boundaries. Numerous uncertainties in the parameterizations limit the overall accuracy of the calculations presented. The most significant of these are: (1) A quantitatively accurate assessment of the remineralization rate of the deposited organic matter including its rate of inoculation by abyssal microorganisms; (2) a detailed assessment of potential non-diffusive pore water transport processes including advection due to compaction and buoyancy-driven flows and enhanced exchange due to macrobenthic irrigation activities and (3) an assessment of the potential alteration of pore space and methane reactivity due to gas hydrate formation.