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This paper aims to improve the previous fuel scrubbing model and find out the relationship between bubble diameter and scrubbing efficiency (ƞ).

A fuel tank scrubbing test bench was established to verify the accuracy of this model. Ullage and dissolved oxygen concentration were measured, and images of bubble size and distribution were collected and analyzed using image analysis software.

The bubble diameter has a great influence on ullage and dissolved oxygen concentration during the fuel scrubbing process. The scrubbing efficiency (ƞ) has an exponential relationship with bubble diameter and decreases rapidly as the bubble diameter increases.

The variation of the ullage and dissolved oxygen concentration predicted by this model is more accurate than that of the previous model. In addition, the study of bubble size can provide a guidance for the design of fuel scrubber.

This study not only improves the previous fuel scrubbing model but also develops a method to calculate scrubbing efficiency (ƞ) based on bubble diameter. In addition, a series of tests and analyses were conducted, including numerical calculation, experiment and image analysis.

The dissimilar welds between AISI 304L and Fe-15.6Cr-8.5Mn were investigated on oxidation at 700°C with the effects of dissolved nitrogen in the welds. This paper aims to clarify the oxidation behaviors to expand the range of application for Fe-Cr-Mn stainless steel.

Dissimilar welds between AISI 304L and Fe-15.6Cr-8.5Mn were fabricated using gas tungsten arc welding to investigate the oxidation behavior of the welds at 700°C. Pure Ar and Ar-4%N₂ shielding gases were used to evaluate the effects of nitrogen gas. The welds were introduced to the cyclic oxidation test. In each cycle, the furnace was heated up to 700°C, and the temperature was kept at 700°C for 8 h, then the mass gain because of oxidation was examined. The scales after oxidation test were investigated by using scanning electron microscopy with EDX and X-ray diffraction analysis.

Addition of 4 per cent nitrogen to Ar shielding gas reduced delta-ferrite content in the weld. Ar-4%N₂ shielding gas resulted in dissolved nitrogen which helped increase the diffusivities of chromium or oxygen vacancies in the oxide to facilitate the chromia formation at the inner part near the steel substrate. This protective layer can help reduce the Fe outward diffusion, thus reducing mass gain because of iron oxide formation.

The oxidation behavior of dissimilar welds between AISI 304L and Fe-15.6Cr-8.5Mn were investigated at 700°C. The evaluation is beneficial for expanding the range of application of Fe-Cr-Mn stainless steel at high temperature.

The kinetics of nitriding in titanium bearing austenitic stainless steels in cylindrical coordination has been investigated. Nitriding at nitrogen partial pressure of 0.5 atm and temperature from 980°C up to 1160oC resulted in the formation of titanium and chromium nitride and above the Cr2N solvus temperature (1100°C), no chromium nitride was formed. The nitrided case may consist of up to three zones: nitrogen in solid solution, precipitation of TiN and finally mixed TiN+Cr2N precipitation. These are in consistent with the affinity of titanium and chromium towards nitrogen which has been thermodynamically justified. To assess the kinetics of nitriding, a mathematical model for nitrogen diffusion in cylindrical system has been developed via solving Fick’s equation for cylindrical coordinate by numerical method. For this purpose the use has been made of the austenite stabilizing effect of nitrogen to correlate the movement of the boundary of the nitrogen stabilized austenite and plastic deformation induced martensite. Since the crystal structure of the material used in this study is of fcc type and it is nitrided in a fully annealed and unstrained state, therefore the effect of excess nitrogen on the kinetics of nitride fronts growth has been assumed as negligible. The results are in good agreement with the previous investigations. Unlike previous works, the present model takes into account the change of nitrogen diffusion coefficient due to nitrogen concentration profile and

Corrosion research chemists of Argonne National Laboratory in the United States, have recently conducted far‐reaching studies into the corrosion problems related to liquid sodium, i.e., carbon migration in sodium‐steel systems, in order to assure long uninterrupted service for sodium‐cooled atomic reactors

Finer sediment particles (silt and clay) transported by rivers carry the major part of nutrient loads by absorption; thus, sediment settling can remove nutrients from the water column. The purpose of this paper is to analyze the relation between reservoir sedimentation and water quality by assessing the reservoir sedimentation process and the sediments’ characteristics.

Bathymetric surveys from 2004 to 2014 were analyzed to assess the sedimentation process. Core samples provided information on a layer-by-layer basis of the sediment deposits, and water samples near the surface and near the bottom provided information on sediment concentration, and adsorbed and dissolved nutrients.

The upstream region of a reservoir is already silted. From 2004 to 2014, the delta evoluted approximately 500 m downstream and the deposits were mainly composed of clay. An area of approximately 1,000 m between the delta and the dam should still be able to continue allowing sediment deposition in the coming years. Most of the nutrients were absorbed into the sediment particles, except for the nitrogen measured in the dry season.

Although analyses of the full cycle of the nutrients were not carried out, the constant sediment trapping of finer sediments and the high rate of absorbed nutrients in the suspended sediment support the hypothesis that the reservoir has removed nutrients from aqueous media by adsorption into sediments.

In the studied case, reservoir sedimentation has led to better water quality downstream.

It is shown in this study that reservoir sedimentation may have positive effects on river water quality.

The elevated level of nitrate in groundwater is a serious problem in Texas aquifers. To control and manage groundwater quality, the characterization of groundwater contamination and identification of the factors affecting the nitrate concentration of groundwater are significant. The purpose of this paper is to determine factors which have significant impacts on the elevated groundwater nitrate concentrations of the Southern High-Plains and the Edwards-Trinity aquifers.

The characterization of groundwater nitrate contamination was undertaken by analyzing the hydrochemical data of groundwater within a statistical framework. The multivariate statistical analysis (ordinary least square) and geographically weighted regression (GWR) models were used to study the relationship between groundwater nitrate contamination and land use of the study areas.

Results show groundwater nitrate contamination is typically due to an overapplication of N fertilizers to cotton in the Southern High-Plains aquifer and to grassland in the Edwards-Trinity aquifer. Adjusted R² (0.45) explains variations of nitrate concentration by well-depth, cotton production, shrubland and grassland in the Edwards-Trinity aquifer. The results of an analysis of variations in N concentration with well depth for all 192 wells indicate that nitrate concentrations in water from wells in the Southern High-Plains and Edwards-Trinity aquifers tend to decrease with increasing well-depth.

In this study, the GWR model was built to identify nitrate concentration within a geographic framework to ensure sustainable use of groundwater, which is important for local management purposes. The analysis should include local spatial variations of elements such as hydrologic characteristics and the land use activities if groundwater nitrate contamination causes adverse effects on human and ecosystem health.

Research over the last 20 years has had a major focus on the ecology of east coast estuaries, including the interaction between coastal seawater and saltmarshes. It is not possible to separate intertidal coastal saltmarshes from the rest of the coastal marine environment as they are involved in a truly interactive system. The significance of this system is attracting increasing attention as the effect of elevated nutrient concentrations on the ecology of the coastal zone has become apparent. It is only when we understand how the various chemical and biological processes influence the flux of nutrients through the estuarine interface between land and sea that any sensible management strategy can be developed.

The purpose of this work is to investigate the performance of non‐contaminating metal cutting environments and investigate the associated tool chip interface conditions. The work benchmarks flood coolant characteristics and considers gaseous cutting environments as possible alternatives.

Cutting trials were undertaken for a range of cutting environments. Flood coolant was investigated as was dry cutting, compressed air, room temperature nitrogen and liquid nitrogen environments. A range of cutting variables was measured in order to document the effect of cutting environment.

The gaseous component of the liquid nitrogen environment limited the adhesion on the tool face to a region along the flank edge of the tool, shifting rake face conditions from seizure to that of sliding. Tighter chip curl, shorter contact lengths, reduced adhesion and lower feed forces are evidence that liquid nitrogen is acting as a “liquid inert barrier” beneath the chip within the tool/chip interface.

Only one tool work combination has been investigated. More tool work combinations will need to be investigated.

The work demonstrated that it is possible to use environmentally safe environments during metal cutting operations. This reduces the exposure of the environment and machine tool operatives to compounds which have been shown to have detrimental effects on the environment and human health.

The work has led to presenting a hypothesis that liquid nitrogen acts as a “liquid inert barrier” beneath the chip within the tool/chip interface.

The purpose of this paper is to develop a numerical model used for calculating the nonlinearities of large-scale hydro-pneumatic suspension (HPS) and investigating the effects of variations in flow path and operational parameter on suspension damping response.

To parameterization nonlinearities of the suspension, the author developed a two-phase flow model of a large-scale HPS based on computational fluid dynamics and volume of fluid method. Considerable effort was made to verify the nonlinearities by field measurements carried out on an off-highway mining dump truck. The investigation of effects of variations in flow path and operational parameter on damping characteristics highlights the necessity of the numerical simulation.

The two-phase flow model can represent the gas-oil interaction and simulate the suspension operational movement conveniently. Transient numerical simulation results can be used to model the nonlinearities of large-scale HPS accurately. A new phenomenon was discovered that the pressure in rebound chamber presents reduction trend during compression stroke in special cases. It has never been reported before.

Developed a two-phase flow model of a large-scale HPS, which can manage the gas-oil interaction and capture the complex flow field structure in it. The paper is the first study to model the nonlinearities of a large-scale HPS used in off-highway mining dump truck through transient numerical simulation. Compared with previous researches, such a research not only gives new insight and thorough understanding into the suspension internal fluid structure but also can give good guiding opinions to the optimal design of HPS.