Hydrodynamic performance of multiple-row slotted breakwaters

This study examines the hydrodynamic performance of multiple-row vertical slotted breakwaters. We developed a mathematical model based on an eigenfunction expansion method and a least squares technique for Stokes second-order waves. The numerical results obtained for limiting cases of double-row and triple-row walls are in good agreement with results of previous studies and experimental results. Comparisons with experimental measurements of the reflection, transmission, and dissipation coefficients (C _R , C _T , and C _E ) for double-row walls show that the proposed mathematical model adequately reproduces most of the important features. We found that for double-row walls, the C _R increases with increasing wave number, kd, and with a decreasing permeable wall part, dm. The C _T follows the opposite trend. The C _E slowly increases with an increasing kd for lower kd values, reaches a maximum, and then decreases again. In addition, an increasing porosity of dm would significantly decrease the C _R , while increasing the C _T . At lower values of kd, a decreasing porosity increases the C _E , but for high values of kd, a decreasing porosity reduces the C _E . The numerical results indicate that, for triple-row walls, the effect of the arrangement of the chamber widths on hydrodynamic characteristics is not significant, except when kd<0.5. Double-row slotted breakwaters may exhibit a good wave-absorbing performance at kd>0.5, where by the horizontal wave force may be smaller than that of a single wall. On the other hand, the difference between double-row and triple-row vertical slotted breakwaters is marginal.     

Rules for aggregated satisfaction with work commutes

In general trips frequently entail several stages varying in mode, duration, and other factors. In some way travelers aggregate their satisfaction with the stages to satisfaction with the whole trip. In this paper we address the question of how this aggregation is made. We use data from a Swedish survey measuring satisfaction with commutes to and from work and with the stages of the commutes. We test several aggregation rules for their goodness of fit to the observations. Our results show that a normatively correct averaging rule that takes into account the relative durations of the stages out-perform heuristic aggregation rules such as the peak-end, summation, and equal-weight averaging rules. We note that this does not exclude that the heuristic aggregation rules apply to other trips than repetitive commute trips.     

The numerical friction line

This paper presents a study on the numerical calculation of the friction resistance coefficient of an infinitely thin plate as a function of the Reynolds number. Seven eddy-viscosity models have been selected: the one-equation turbulence models of Menter and Spalart–Allmaras; the k-ω two-equation model proposed by Wilcox and its TNT, BSL and SST variants and the two-equation model. The flow has been computed at 14 Reynolds numbers in sets of seven geometrically similar Cartesian grids to allow a reliable estimation of the numerical uncertainty. The effect of the computational domain size has been reduced to negligible levels (below the numerical uncertainty). And the same holds for the iterative and round-off errors. In the finest grids of each set, the numerical uncertainty of the friction resistance coefficient is always below 1%. Special attention has further been given to the solution behaviour in the laminar-to-turbulent transition region. Curve fits have been applied to the data obtained at the 14 Reynolds numbers and the numerical friction lines are compared with four proposals from the open literature: the 1957 ITTC line, the Schoenherr line and the lines suggested by Grigson and Katsui et al. The differences between the numerical friction lines obtained with the seven turbulence models are smaller than the differences between the four lines proposed in the open literature.     

摩擦楔块几何尺寸对货车转向架性能的影响

分析了俄罗斯18-100型三大件货车转向架摩擦楔块结构的特点,指出改变摩擦楔块形状可以改进转向架的性能.     

Distribution and diet of larval and juvenile Arctic cod (Boreogadus saida) in the shallow Canadian Beaufort Sea

The distribution and diet of larval and juvenile Arctic cod (Boreogadus saida) were studied during summer 2005 in the coastal Canadian Beaufort Sea. A total of 275 individuals were captured and the highest abundance was observed at station depths of 20–30 m. This corresponds well with the location of the frontal zone where the Mackenzie River plume water and open sea water meet. Diet examinations were performed on 220 Arctic cod, which were found undamaged from sampling. We observed a gradual decrease in prey number per fish and increase in prey size as larvae grew which corresponded to a shift from Rotifera and nauplii towards larger copepodid stages. However, at all sizes, the larvae remain generalists and feed on a broad range of organisms. Environmental changes due to climate warming could have a two-fold impact on fish larvae feeding in the studied region. First, the potential for increased primary production may lead to increased zooplankton production that may impact the feeding and nutrition positively. On the other hand, greater discharge of turbid water from the Mackenzie River may reduce light penetration in the water column that may negatively influence the ability of visual predators to successively forage.     

EFFECTS OF NITRIC OXIDE SYNTHESIS INHIBITION WITH OR WITHOUT NITRIC OXIDE IN

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NITRIC OXIDE SYNTHESIS INHIBITION ENHANCES BUPIVACAINE CARDIOTOXICITY

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THE EFFECT OF VITAMIN C INTAKE ON GLYCOHEMOGLOBIN MEASUREMENTS

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CD_4~( ) EFFECTOR CELLS DEFAULT TO THE TH2 PATHWAY IN INTERFERONγ-DEFICIENT

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