Effect of WO<Subscript>3</Subscript> nanoparticle loading on the microstructural,mechanical and corrosion resistance of Zn matrix/TiO<Subscript>2</Subscript>-WO<Subscript>3</Subscript> nanocomposite coatings for marine application

In this study, for marine application purposes, we evaluated the effect of process parameter and particle loading on the microstructure, mechanical reinforcement and corrosion resistance properties of a Zn-TiO₂-WO₃ nanocomposite produced via electrodeposition. We characterized the morphological properties of the composite coatings with a Scanning Electron Microscope (SEM) equipped with an Energy Dispersive Spectrometer (EDS). We carried out mechanical examination using a Dura Scan hardness tester and a CERT UMT-2 multi-functional tribological tester. We evaluated the corrosion properties by linear polarization in 3.5% NaCl. The results show that the coatings exhibited good stability and the quantitative particle loading greatly enhanced the structural and morphological properties, hardness behavior and corrosion resistance of the coatings. We observed the precipitation of this alloy on steel is greatly influenced by the composite characteristics.     

Effect of injection angle on artificial cavitation using the design of experiment method

Using the supercavitation phenomenon is necessary to reach high velocities underwater. Supercavitation can be achieved in two ways: natural and artificial. In this article, the simulation of flows around a torpedo was studied naturally and artificially. The validity of simulation using theoretical and practical data in the natural and artificial phases was evaluated. Results showed that the simulations were consistent with the laboratory results. The results in different injection coefficient rates, injection angles, and cavitation numbers were studied. The obtained results showed the importance of cavitation number, injection rate coefficient, and injection angle in cavity shape. At the final level, determining the performance conditions using the Design of Experiment (DOE) method was emphasized, and the performance of cavitation number, injection rate coefficient, and injection angle in drag and lift coefficient was studied. The increase in injection angle in the low injection rate coefficient resulted in a diminished drag coefficient and that in the high injection rate coefficient resulted in an enhanced drag coefficient.     

Children’s travel to school: satisfaction,current mood,and cognitive performance

We investigate whether travel mode, travel time, and activities during travel influence children’s satisfaction with their travel to school, their current mood, and their cognitive performance after arriving at school. A sample of 344 children (165 girls) between the ages of 10 and 15 years were recruited at five public schools in Värmland County, Sweden. Directly after arriving at school, the children rated how they felt on two scales ranging from very sad to very happy and from very tired to very alert, filled out the Satisfaction with Travel Scale adapted for children (STS-C), reported details about their journeys, and took a word-fluency test. The results for STS-C showed that traveling by school bus and walking or cycling was experienced as having a higher quality than traveling by car. Children who engaged in conversation during their journeys reported a higher quality and more positive feelings than children who were engaged in solitary activities during their journeys. A shorter journey was experienced as having a higher quality and resulting in more positive feelings. Children traveling for longer durations performed better in the word-fluency test if using their smartphones or doing a combination of activities during their journeys.     

High-resolution surveys of the biogeochemistry of the New England shelfbreak front during Summer, 2002

We present the observations from a pair of field experiments at the New England shelfbreak front in June and August of 2002, each consisting of 14 cross-frontal surveys using the Lamont Pumping SeaSoar. Measurements of the front's physical, chemical, and bio-optical characteristics were made at high spatial and temporal resolution. The front, based on water-column hydrographic distributions, was found within a few km of the 200 m isobath during both cruises. We present here composite sections, based on averages of individual sections shifted in space to a common frontal location, of the cross-frontal distributions of these properties as a measure of the mean state of the front in both June and August. The observations show the familiar temperature, salinity, and density distributions of the summertime front, dominated by surface thermal heating. Nutrient and bio-optical distributions show the combined effects of water-mass exchange and biological processes. T, S, silicate, and phosphate distributions are suggestive of cross-frontal exchange of slope- and shelf waters, although transport mechanisms and pathways are not apparent. These properties, along with nitrate and optical measures of the suspended particle distributions, show vertical displacements of isopleths as the front is approached: property contours slope upwards toward the front from the shoreward side, and downwards toward the front from the seaward side. Again, actual water-movement pathways are not constrained by these suggestive patterns. Bio-optical distributions show elevated indicators of photosynthetic efficiency both seaward and shoreward of the front, but the front itself is a minimum in biomass. Accumulation of photosynthetic biomass appears to be controlled primarily by nitrate scarcity in waters within and above the pycnocline. At the base of the pycnocline, light limitation appears to be the controlling factor, although the base of the euphotic zone is deeper than the biomass maxima and the base of the pycnocline. Mechanisms explaining this phenomenon are unclear, but tenuous evidence suggests low stratification at the depth of the 1% light level may not allow phytoplankton to optimize for the low-light, high-nutrient conditions at depth. Cross-frontal differences in nutrient and bio-optical parameters, particularly in August, suggest distinct phytoplankton assemblages, and the presence of calcite-forming or nitrogen fixing groups to the community structure, especially in very shallow waters across the front and in pycnocline waters seaward of the front.     

Cross-shelf circulation and phytoplankton distribution at the summertime New England shelfbreak front

We investigate aspects of the secondary (cross-shelf) circulation at the Middle Atlantic Bight shelfbreak front using high-resolution data collected on the New England Shelf in August 2002. The alongshore shelfbreak jet coincides with the front at the seaward edge of the cold pool (remnant winter shelf water) and there is a suggestion of a cross-stream convergence centered at the jet core. Despite indications of convergence we found no evidence of a surface subduction on the seaward side of the front. At depth 70 m near the shelfbreak there was a patch of chlorophyll, located within a local temperature–salinity maximum which, though significantly below the euphotic zone, appeared to be photo-acclimated and viable. The chlorophyll feature could be the result of a local subduction by a larger scale eddy circulation seaward of the front.Dye tracer experiments directly observed the convergence at the foot of the shelfbreak front and subsequent upwelling of bottom boundary layer water along the shoreward side of the shelfbreak front. But, we found no evidence that this upwelling influenced productivity at the front. Further, since there was no cross-shelf maximum in subsurface chlorophyll at the front, we conclude that this productivity is in general, sustained by a broadly distributed local vertical nutrient flux from an underlying nutrient reservoir.     

An integrated water/sediment approach to study plankton (a case study in the southern Adriatic Sea)

In marine coastal areas many planktonic species produce resting stages (cysts) that sink to the bottom. Integrated sampling from both the water column (to collect active stages), and sediments (to collect cysts), could be useful to achieve more complete information about plankton composition.In the framework of the “INTERREG II Albania-Italy Project” an oceanographic survey was carried out aboard the r/v “Italica” from 20 to 31 October 2000. The survey interested the northern Albanian coast (Gulf of Drin) and the northern Apulian coast (Gulf of Manfredonia) on the opposite sides of the South Adriatic Sea. The plankton was collected from 14 stations. A total of 188 categories were recognized in plankton samples. Among those categories, 130 species were recognized (87 of phytoplankton, 43 of microzooplankton), and only 53 (40.8%) resulted common to both the Adriatic sides. A total of 69 cyst morphotypes were recognized in sediment samples; 38 of them were classified at the level of species. A statistical analysis of the micro-zooplankton species abundance showed a segregation of the two areas better than that obtained with the phytoplankton. Cyst distribution in the sediments showed a good gulf-segregation too. In addition, they allowed us to find complementary information, particularly for dinoflagellates. The most abundant species in the water column were not equally dominant as resting stages in the sediments. Sediment sampling allowed further information about the composition of the plankton communities, and suggested us to search for a new method to enhance the yield of less abundant cysts.     

Wave scattering by undulating bed topography in a two-layer ocean

The problem of wave scattering by undulating bed topography in a two-layer ocean is investigated on the basis of linear theory. In a two-layer fluid with the upper layer having a free surface, there exist two modes of waves propagating at both the free surface of the upper layer and the interface between the two layers. Due to a wave train of a particular mode incident on an obstacle which is bottom-standing on the lower layer, reflected and transmitted waves of both modes are created by the obstacle. For small undulations on the bottom of the lower layer, a perturbation method is employed to obtain first-order reflection and transmission coefficients of both modes for incident wave trains of again both modes in terms of integrals involving the bed-shape function. For sinusoidal undulations, numerical results are presented graphically to illustrate the energy transfer between the waves of different modes by the undulating bed. U. BASU was born in 1949. She is a professor in the Department Applied Mathematics, Calcutta University, India. Her current research interests include water wave problems, continuum mechanics, etc.     

欧洲绿色交通发展经验

首先探索了绿色交通涉及的因素,指出可持续交通层面下的政策目标。对实现这些目标可以采取的相关策略进行分析,包括新技术的应用以及交通政策的干预。基于欧洲经验,总结了交通政策的效果和作用,包括土地利用、基础设施、交通管理、运营措施、信息和宣传、费用等。最后,针对实施交通战略过程中存在的体制、可接受性、财政三方面的阻碍提出建议。     

3-（v，K4^（3）-e，λ）最小覆盖问题

考虑一种特殊类型的超图分解．证明了对任意的正整数v≥4和λ,存在具有[λv（v-1）（v-2）／18]个区组的MCλ（3,K4^（3）-e,v）,其边超越中至多含有两条边．     

Erosion-corrosion damages of water-pump impeller

A steel impeller placed in a water pump has been studied with the aim of understanding the surface erosion-corrosion phenomena responsible for reducing the pumping efficiency of water inside the cooling system. This experiment includes long-term (over about half a year) observations with a powered microscope and precise weight measurements. The experiments were carried out under different conditions of water using several mixtures of water and coolants with water contents of 25%, 50%, 75%, and 100% (i.e., pure tap water). The visual microscopy results reveal that most of the steel surface is pitted and clearly rusty, such that corrosion phenomena are noticeable as time passes. In addition, the amount of weight lost from the sample specimens submerged in static water increased linearly, whereas those placed in mixtures of water and coolant initially gained weight before reaching an almost constant weight. In order to see the dynamic effect of the impeller on the erosion-corrosion phenomena, surface observations of the steel impeller were also made at each time after suitable running conditions in water and water-coolant mixtures, namely around 3∼4 hours of operation per day under changing rotation speeds. The results show that the rate of weight loss was linear and 2∼3 times higher than the impeller in water under both static and dynamic conditions. However, when the impeller was submerged in the mixtures, the weight loss was initially insignificant due to the corrosion-proof ingredients of the coolant, but after around 2 months the weight loss substantially increased and gradually approached a linear curve.