•CFD-based hydrodynamic analysis of octagonal RAS tank with Cornell-type dual drain was performed.•Effect of flow-split between two outlets was analysed using large-scale and small-scale turbulent ...structures in the domain.•Effect of flow-split on flow velocity, uniformity, vorticity and swirl characteristics for s ∊ 0, 1.
Large culture tanks of several hundred or thousand m3 size are generally encouraged for economic advantages in Recirculating Aquaculture Systems (RAS). Out of numerous possibilities in designing the inlet and outlet configurations in octagonal culture tanks, the inlet pipes near the corner walls and the outlets at the tank’s center and/or on side wall are some of the widely-used configurations. The use of wall drain to achieve a controlled flow pattern in the tank, however, influences distinct flow features such as pressure, velocity, uniformity and turbulence in the tank, which are of theoretical interest as well as practical importance. A finite volume description of the flow in an octagonal culture tank at full-scale was therefore developed using Realizable turbulence model with second order accuracy in space and time. The tank was equipped with an inlet pipe near the corner wall and dual-drain outlet system of Cornell-type. The base case had a flow configuration of 45% of flow through central bottom drain, and the rest through the wall drain. Model verification was performed using grid convergence tests, and validation was conducted using Acoustic Doppler velocimetry (ADV) based velocity measurements. The effect of wall drain on the large-scale and small-scale turbulent structures was studied using the distribution of turbulent kinetic energy and vorticity respectively. The parametric study on the flow-split between the two outlets was analyzed using different flowfield indicators, such as flow velocity, uniformity, vorticity strength, maximum absolute vorticity and swirl number. Such an inclusive analysis not only explores the hydrodynamics in the commercial culture tanks with Cornell-type dual-drain but also recommends the farmers with the suitable flow-split between such outlet systems.
The aim of this study was to determine what the fast food restaurants in the Gauteng region are doing to combat obesity. Obesity is a global epidemic, with figures rising at an alarming rate every ...year. The food service industry has contributed significantly to the rise in obesity rates worldwide. Purposive sampling technique was utilised. From the target population selected, one manager per establishment was chosen to participate in the survey (one manager x 5 fast food outlets x 6 branches = 30 managers in total). The study used a quantitative research approach, utilising self-administered surveys which were distributed by the researchers. Summarily, the study observed that there was a statistically significant difference (p<0.05) among the managers regarding knowledge of healthy meals. Managers of two of the fast foods had better knowledge of healthy meals than managers of the other three fast foods. A lot still needs to be done across all sectors of the food industry. The South African government, specifically the Departments of Health and Tourism, should collaborate to develop regulations regarding inclusion of nutritional information on menus. Increasing fast food restaurant employees' awareness of the obesity epidemic can have a long-term impact because they will be able to easily promote healthier eating if they are better informed. The findings revealed that the managers agreed that more regulations were needed to help reduce obesity.
During the last few decades, several sectors in Antarctica have transitioned from glacial mass balance equilibrium to mass loss. In order to determine if recent trends exceed the scale of natural ...variability, long-term observations are vital. Here we explore the earliest, large-scale, aerial image archive of Antarctica to provide a unique record of 21 outlet glaciers along the coastline of East Antarctica since the 1930s. In Lützow-Holm Bay, our results reveal constant ice surface elevations since the 1930s, and indications of a weakening of local land-fast sea-ice conditions. Along the coastline of Kemp and Mac Robertson, and Ingrid Christensen Coast, we observe a long-term moderate thickening of the glaciers since 1937 and 1960 with periodic thinning and decadal variability. In all regions, the long-term changes in ice thickness correspond with the trends in snowfall since 1940. Our results demonstrate that the stability and growth in ice elevations observed in terrestrial basins over the past few decades are part of a trend spanning at least a century, and highlight the importance of understanding long-term changes when interpreting current dynamics.
With the rapid increasing heat fluxes released from micro electronic devices, thermal management of electric components faces huge challenge. High working temperature generated by the chip will ...directly affect its performance. It is essential to develop advanced model to enhance heat transfer. In this study, a new microchannel heat sinks with impinging jets and dimples (MHSIJD) model with side outlets was proposed. Computational fluid dynamics simulation methodology with RNG
k
–
ε
turbulence model was used to investigate the performance of MHSIJD with side outlets. Valuation indices including thermal capability, pump consumption and overall performance were analyzed. Three models were compared with basic model (MHSIJD without side outlets): the cross section of the side outlet was set as 0.2 × 0.2 mm (Case 1), 0.4 × 0.4 mm (Case 2), and 0.6 × 0.6 mm (Case 3). The results showed that: (1) the MHSIJD with side outlets performs better heat transfer characteristic due to the alleviation of drift phenomenon. The heat transfer capacity can be increased by up to 17.51%; (2) the MHSIJD with side outlets exhibits a lower pressure drop, which can be reduced up to 22.39%; and (3) the overall performance of MHSIJD with side outlets is better due to its higher cooling efficiency and lower pump consumption.
In this study the flow rate in a quasi-2D hopper with two symmetric outlets was investigated numerically. When two outlets merge into one, the flow rate is obviously bigger than that with a large ...enough distance between them. To explain the influence of the interaction between these two outlets, it was found that the velocity field above one outlet will be affected by the neighboring outlet by reducing the stagnant zone. With increasing distance, this interaction becomes weaker. Finally the formula of flow rate considering various outlet sizes and distances is fitted to the simulation data.
•The flow rate in a quasi-2D hopper with two outlets is investigated.•The formula of flow rate is fitted.•The flow field in the hopper is plotted.
Previous literature has focused on luxury tourism or luxury shopping, revealing that luxury-driven attitudes comprised unveiled reasons such as materialism, a desire for social status and the need to ...conform with others. Different outlets play different roles in the enactment of shopping attitudes, but even this has been scarcely researched within the context of tourism. This research combines these three areas of research in order to assess how materialism, the desire for status or to conform with others enact tourists’ intentions of buying luxuries while on holiday, within different outlets. A sample of 314 tourists in Hong Kong was used to test eight hypotheses, by means of an ordered probit model. The study’s findings enlighten the social nature of luxury tourists’ shopping behaviours, a nature that depends not only on what they buy but also largely on where they buy.
In this study, we used high-throughput sequencing of 16S rRNA gene amplicons, to investigate the spatio-temporal variation in bacterial communities in surface-waters collected from eight major ...outlets of the Pearl River Estuary, South China. Betaproteobacteria were the most abundant class among the communities, followed by Gammaproteobacteria, Alphaproteobacteria, Actinobacteria, and Acidimicrobiia. Generally, alpha-diversity increased in winter communities and the taxonomic diversity of bacterial communities differed with seasonal and spatial differences. Temperature, conductivity, salinity, pH and nutrients were the crucial environmental factors associated with shifts in the bacterial community composition. Furthermore, inferred community functions that were associated with amino acid, carbohydrate and energy metabolisms were lower in winter, whereas the relative abundance of inferred functions associated with membrane transport, bacterial motility proteins, and xenobiotics biodegradation and metabolism, were enriched in winter. These results provide new insights into the dynamics of bacterial communities within estuarine ecosystems.
•Betaproteobacteria were the most abundant bacterial taxon among the communities.•Alpha-diversity generally increased in winter communities.•Temperature, conductivity and salinity were the vital environmental factors.•Amino acid metabolism predicted by PICRUSt was inhibited in winter.•The inferred function associated with membrane transport was enriched in winter.
•A topology optimization method for multiple inlet and outlet cold plates is proposed.•Examined the impact of the numbers and layout of inlets and outlets.•Inlet and outlet have a lower pressure drop ...along the short side layout.•The temperature distribution across the three inlets and outlets is more uniform.•The three inlets and outlets have more flow heat exchange capacity.
The trade-off between enhancing the thermal performance of battery liquid cooling plates and reducing their pumping power consumption remains an unresolved issue. In order to solve this problem, this study proposes a multi-inlet and multi-outlet liquid cooling plate design method based on topology optimization. Through topology optimization, 2D models with various numbers of inlets and outlets under different arrangements were obtained, and were extended into 3D numerical models. The study investigated the impact of inlet and outlet arrangement direction, quantity, channel depth, and total mass flow rate at the inlet on the performance of liquid cooling plates. The findings indicated that Topology-optimized liquid cooling plates exhibit superior flow and heat exchange performance compared to traditional straight-channel liquid cooling plates. Arranging the inlet and outlet along the width direction of the rectangular liquid cooling plate can reduce the pressure drop. As for the number of inlets and outlets along the width direction, employing three inlets and three outlets, as opposed to a single inlet and outlet, reduced pump power by 29.04 %, increased the heat transfer coefficient by 28.41 %, increased temperature uniformity by 39.13 %, and boosted the comprehensive evaluation factor by 80.7 %. Furthermore, the channel depth of 3 mm, with a total mass flow rate of 15 g/s at the inlet, was the ideal choice for achieving a balance between system heat dissipation and power consumption. Finally, the accuracy of the simulation was validated through experiments.
A low temperature, isothermal, gas-phase, recyclable process is described for the partial oxidation of methane to methanol over Cu-ZSM-5. Activation in NO at 150 °C followed by methane reaction and ...steam extraction (both at 150 °C) allowed direct observation of methanol at the reactor outlet.
•Data-driven analysis of micropollutants in 77 wet-weather discharge sites.•Top list of micropollutants with high occurrence and risk for surface waters.•Combined sewer overflows, stormwater outlets ...and all chemical classes show risk.•Minimum number of required events and sites predicted by concentration variability.•Discussion of learnings for future wet-weather flow monitoring.
Urban wet-weather discharges from combined sewer overflows (CSO) and stormwater outlets (SWO) are a potential pathway for micropollutants (trace contaminants) to surface waters, posing a threat to the environment and possible water reuse applications. Despite large efforts to monitor micropollutants in the last decade, the gained information is still limited and scattered. In a metastudy we performed a data-driven analysis of measurements collected at 77 sites (683 events, 297 detected micropollutants) over the last decade to investigate which micropollutants are most relevant in terms of 1) occurrence and 2) potential risk for the aquatic environment, 3) estimate the minimum number of data to be collected in monitoring studies to reliably obtain concentration estimates, and 4) provide recommendations for future monitoring campaigns. We highlight micropollutants to be prioritized due to their high occurrence and critical concentration levels compared to environmental quality standards. These top-listed micropollutants include contaminants from all chemical classes (pesticides, heavy metals, polycyclic aromatic hydrocarbons, personal care products, pharmaceuticals, and industrial and household chemicals). Analysis of over 30,000 event mean concentrations shows a large fraction of measurements (> 50%) were below the limit of quantification, stressing the need for reliable, standard monitoring procedures. High variability was observed among events and sites, with differences between micropollutant classes. The number of events required for a reliable estimate of site mean concentrations (error bandwidth of 1 around the “true" value) depends on the individual micropollutant. The median minimum number of events is 7 for CSO (2 to 31, 80%-interquantile) and 6 for SWO (1 to 25 events, 80%-interquantile). Our analysis indicates the minimum number of sites needed to assess global pollution levels and our data collection and analysis can be used to estimate the required number of sites for an urban catchment. Our data-driven analysis demonstrates how future wet-weather monitoring programs will be more effective if the consequences of high variability inherent in urban wet-weather discharges are considered.
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