A Voyage Planning Tool for Arctic Transit of Cargo Ships

The paper presents a decision-support tool for maritime operations in Arctic seas. This tool targets at improving the safety and fuel efficiency of existing and future cargo vessels that are designed to operate in Arctic and in open water conditions. It is achieved by smart voyage planning using meteorological, oceanographic and ice forecasting. A single-objective optimization for minimizing the fuel consumption in various scenarios of Arctic transits is established, with the transit time and the safety as the two major constraints. The tool is implemented in an in-house Matlab code, which is based on Dijkstra’s algorithm, a grid-based approach that aims at finding the most cost-efficient path connecting any chosen nodes in a given grid. Results from case studies along the Northern Sea Route indicate that the tool generates appropriate routes in ice-infested Arctic waters. The fuel consumption accounting for ice-induced extra resistance is optimized and the risk of collision with icebergs has been considered.

Magnesium Corrosion in Different Solutions

The corrosion mechanism of Mg alloys in Hank’s solution was elucidated by comparing the corrosion of typical Mg alloys (AZ91, ZE41 and Mg2Zn0.2Mn) and high purity Mg in Hank’s solution at room temperature and in 3% NaCl saturated with Mg(OH)2. Corrosion was characterised by the evolved hydrogen and the surfaces after the immersion tests. Corrosion in Hank’s solution was weakly influenced by microstructure in contrast to corrosion in the 3% NaCl solution, where second phases cause strong micro-galvanic acceleration. This is attributed to the formation of a more protective surface film in Hank’s solution, causing extra resistance between the alpha-Mg matrix and the second phase. The incubation period in Hank’s solution was alloy dependent.

An experimental study on the effect of spacer on concentration polarization in a long channel reverse osmosis membrane cell

This study was to experimentally investigate the performance and organic fouling behaviour in a 1-m long RO membrane channel with or without spacer for desalting. It was found that local permeate flux distributed heterogeneously along the long membrane channel without a spacer inserted due to exponential growth of concentration polarization, which also resulted in decreasing salt rejection and increasing organic fouling along the membrane channel in the downstream direction. This heterogeneity could be lessened by inserting a spacer into the channel, which mitigated concentration polarization due to the enhanced turbulence caused by a spacer, especially at the downstream portion of the channel. However, in the upstream of the channel, inserting a spacer exerted an additional vertical resistance which might counteract the effect of concentration polarization mitigation by a spacer and caused a lower permeate flux. This suggests that it is necessary to consider the integral effect of spacer for designing an RO membrane module and an overall RO system in order to prevent extra resistance, reduce concentration polarization and membrane fouling.

TLS D5

TLS D5 is an air-hardening high-carbon high-chromium die steel. The addition of approximately 3% Co gives this steel extra resistance to galling and pickup and also provides additional red hardness, which is useful on semihot work applications. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on wear resistance as well as heat treating and machining. Filing Code: TS-647. Producer or source: Timken Latrobe Steel.

Dynamic Splinting Following Flexor Tendon Repair

Electromyographic investigation of subjects wearing dynamic flexor tendon repair (Kleinert) splints shows a wide variability in the amount of contraction in the flexor digitorum profundus muscle during extension of the finger. We suggest there is no advantage in giving extra resistance to the extensor muscles, and that the strength of the rubber bands needs to be only just sufficient to flex the finger passively back to its resting position.

An electromyographic study of elbow motion during postexercise muscle soreness

Postexercise muscle soreness was induced in the elbow flexors of human volunteer subjects through the use of a regimen of eccentric contractions. Physical examination before and 48 h after the exercise included measurements of range of elbow motion at the elbow and of arm diameter. Electromyographic (EMG) observations, utilizing fine wire electrodes introduced into each of the elbow flexors, were carried out before and 48 h after the exercise. These observations included resting EMG levels, EMG activity under various isometric loads, and activity during active and passive extensions. The soreness induced was accompanied by a reduction in resting elbow angle while the subjects stood with arms relaxed at their sides, decreased range of both flexion and extension of the elbow, and swelling of the arm. EMG measurements showed no increase in EMG activity as the sore arms were extended passively at the elbow, indicating that the extra resistance to extension associated with the soreness was not a result of stretch receptor-induced activity in the flexors. The results rule out the possibility that neuromuscular activity is responsible for the restriction of motion and are consistent with the idea that edematous changes within the perimuscular connective tissue alter the elastic behavior of the muscles and cause restriction of motion.

COBALT CHROME

COBALT CHROME is an air-hardening,high-carbon, high-chromium die steel. The addition of approximately 3% to this steel gives it extra resistance to galling and pick-up and additional red hardness which is useful on semi-hot-work applications. It also is recommended when it is desirable to nitride specialized tools. Its many uses include dies, gages, punches, rolls and slitter knives. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, heat treating, and machining. Filing Code: TS-427. Producer or source: Latrobe Steel Corporation.

Resistance of superconducting-normal interfaces

The work of Pippard, Shepherd & Tindall (P. S. T.) on the resistance of copper foil sandwiched between superconducting lead electrodes has been extended (1) to study the influence of alloying the lead with bismuth, (2) to investigate other pairs of metals, Pb-Re, Pb-Mo, Pb-Al, Pb-Sn, Sn-Al. In addition, different techniques for depositing lead electrodes on copper foil have been investigated; evaporation in vacuo after cleaning the copper surface by sputtering has been found to give the most consistent results and minimal oxide contamination at the metallic interface. Thin oxide layers give rise to a characteristic rise in the resistance of the sandwich as the temperature is lowered well below the superconducting transition. The behaviour is fairly consistent with a simple model in which regions of metallic contact carry current in parallel with tunnel junctions; the conductivity of the latter is much higher than for oxide layers used for experiments on superconducting tunnelling, and it is conjectured that they are monomolecular. The rise of resistance towards the transition temperature of lead, as observed by P. S. T., becomes more marked when bismuth is added to the lead, but reaches a limiting behaviour with 5 % Bi which is maintained up to 20 % Bi, at which point the behaviour becomes less reproducible, as might be expected with a two phase superconducting electrode. The resistance of the sandwich at the lowest temperatures is also somewhat increased by the addition of bismuth to the lead. A theory of the observations has been developed by extension of the argument of P. S. T. which attributes the extra resistance to the penetration of excitations from the normal metal into the superconductor, provided they have an energy above the gap. With the addition of bismuth these excitations are more frequently scattered before finally being assimilated into the equilibrium superconducting state, and the extra scattering reveals itself as extra resistance. At the lowest temperatures no excitations can enter the superconductor from the normal metal, and if the superconductor were pure and metallic contact perfect the total reflexion of excitations with reversal of character, as analysed by Andreev, would lead to no extra resistance. The reflected excitations, however, penetrate to something like the coherence length into the superconductor in the form of an evanescent mode. It is the scattering of the evanescent mode by impurities which is responsible for partial reflexion without change of character, and hence for the extra resistance at low temperatures. The scattering process for evanescent modes is analysed in some detail and the problem of developing a full theory in the three dimensional case is discussed but without a final conclusion. The one dimensional model is nevertheless capable of fairly complete solution, though reasons are given for not trusting its predictions in the real situation. Although fully quantitative explanation of the experimental results is not possible either at low temperatures or near the transition temperature (in the latter case because of effects due to short lifetime of excitations in lead), the qualitative agreement between models and experiment is not unsatisfactory. The results on sandwiches in which the centre part becomes superconducting at a lower temperature than the flanking electrodes confirm other observations in showing how the resistance begins to drop as the temperature falls towards the lower transition temperature. The Pb-Mo samples behave as might have been expected if the molybdenum had a transition temperature of about 1K although these samples, possibly due to iron content, had a transition temperature below 0.4 K.