308 research outputs found
Can switching fuels save water? A life cycle quantification of freshwater consumption for Texas coal-and natural gas-fired electricity
Thermal electricity generation is a major consumer of freshwater for cooling, fuel extraction and air
emissions controls, but the life cycle water impacts of different fossil fuel cycles are not well understood.
Much of the existing literature relies on decades-old estimates for water intensity, particularly regarding
water consumed for fuel extraction. This work uses contemporary data from specific resource basins and
power plants in Texas to evaluate water intensity at three major stages of coal and natural gas fuel cycles:
fuel extraction, power plant cooling and power plant emissions controls. In particular, the water intensity
of fuel extraction is quantified for Texas lignite, conventional natural gas and 11 unconventional natural
gas basins in Texas, including major second-order impacts associated with multi-stage hydraulic
fracturing. Despite the rise of this water-intensive natural gas extraction method, natural gas extraction
appears to consume less freshwater than coal per unit of energy extracted in Texas because of the high
water intensity of Texas lignite extraction. This work uses new resource basin and power plant level
water intensity data to estimate the potential effects of coal to natural gas fuel switching in Texasâ power
sector, a shift under consideration due to potential environmental benefits and very low natural gas
prices. Replacing Texasâ coal-fired power plants with natural gas combined cycle plants (NGCCs) would
reduce annual freshwater consumption in the state by an estimated 53 billion gallons per year, or 60% of
Texas coal powerâs water footprint, largely due to the higher efficiency of NGCCs.Mechanical Engineerin
Interface Width and Bulk Stability: requirements for the simulation of Deeply Quenched Liquid-Gas Systems
Simulations of liquid-gas systems with extended interfaces are observed to
fail to give accurate results for two reasons: the interface can get ``stuck''
on the lattice or a density overshoot develops around the interface. In the
first case the bulk densities can take a range of values, dependent on the
initial conditions. In the second case inaccurate bulk densities are found. In
this communication we derive the minimum interface width required for the
accurate simulation of liquid gas systems with a diffuse interface. We
demonstrate this criterion for lattice Boltzmann simulations of a van der Waals
gas. When combining this criterion with predictions for the bulk stability we
can predict the parameter range that leads to stable and accurate simulation
results. This allows us to identify parameter ranges leading to high density
ratios of over 1000. This is despite the fact that lattice Boltzmann
simulations of liquid-gas systems were believed to be restricted to modest
density ratios of less than 20.Comment: 5 pages, 3 figure
Understanding environmental and fisheries factors causing fluctuations in mud crab and blue swimmer crab fisheries in Northern Australia to inform harvest strategies
The current project investigated relationships between environmental factors and harvests of crabs in the Gulf of Carpentaria (GoC), northern Australia. This was in response to industry and managerial concerns about consistent declines in harvests of GoC Giant Mud Crab (Scylla serrata). In the orthern Territory (NT), declines occurred between 2009 and 2016, whilst in Queensland (Qld), declines occurred between 2013 and 2016. The declines occurred despite different management arrangements (e.g. NT harvests females, whereas Qld does not), suggesting common environmental factors were involved
Understanding environmental and fisheries factors causing fluctuations in mud crab and blue swimmer crab fisheries in Northern Australia to inform harvest strategies
The current project investigated relationships between environmental factors and harvests of crabs in the Gulf of Carpentaria (GoC), northern Australia. This was in response to industry and managerial concerns about consistent declines in harvests of GoC Giant Mud Crab (Scylla serrata). In the orthern Territory (NT), declines occurred between 2009 and 2016, whilst in Queensland (Qld), declines occurred between 2013 and 2016. The declines occurred despite different management arrangements (e.g. NT harvests females, whereas Qld does not), suggesting common environmental factors were involved
Planar millimeter wave radar frontend for automotive applications
A fully integrated planar sensor for 77 GHz automotive applications is presented. The frontend consists of a transceiver multichip module and an electronically steerable microstrip patch array. The antenna feed network is based on a modified Rotman-lens and connected to the array in a multilayer approach offering higher integration. Furthermore, the frontend comprises a phase lock loop to allow proper frequency-modulated continuous wave (FMCW) radar operation. The latest experimental results verify the functionality of this advanced frontend design featuring automatic cruise control, precrash sensing and cut-in detection. These promising radar measurements give reason to a detailed theoretical investigation of system performance. Employing commercially available MMIC various circuit topologies are compared based on signal-tonoise considerations. Different scenarios for both sequential and parallel lobing hint to more advanced sensor designs and better performance. These improvements strongly depend on the availability of suitable MMIC and reliable packaging technologies. Within our present approach possible future MMIC developments are already considered and, thus, can be easily adapted by the flexible frontend design. Es wird ein integrierter planarer Sensor fĂŒr 77 GHz Radaranwendungen vorgestellt. Das Frontend besteht aus einem Sende- und Empfangs-Multi-Chip-Modul und einer elektronisch schwenkbaren Antenne. Das Speisenetzwerk der Antenne basiert auf einer modifizierten Rotman- Linse. FĂŒr eine kompakte Bauweise sind Antenne und Speisenetzwerk mehrlagig integriert. Weiterhin umfasst das Frontend eine Phasenregelschleife fĂŒr eine prĂ€zise Steuerung des frequenzmodulierten Dauerstrichradars. Die aktuellen Messergebnisse bestĂ€tigen die Funktionalitšat dieses neuartigen Frontend-Designs, das automatische Geschwindigkeitsregelung, Kollisionswarnung sowie NahbereichsĂŒberwachung ermöglicht. Die QualitĂ€t der Messergebnisse hat weiterfĂŒhrende theoretische Untersuchungen ĂŒber die potenzielle SystemleistungsfĂ€higkeit motiviert. Unter BerĂŒcksichtigung von kommerziell erhĂ€ltlichenMMICs werden verschiedene Schaltungstopologien auf der Grundlage des Signal-Rausch-VerhĂ€ltnisses verglichen. Sowohl fĂŒr sequenzielle als auch fĂŒr parallele Ansteuerung der Antennenkeulen wird eine deutliche Leistungssteigerung ermittelt. Diese Verbesserungen hĂ€ngen maĂgeblich von der VerfĂŒgbarkeit geeigneter MMICs und einer zuverlĂ€ssigen Aufbau- und Verbindungstechnik ab. Das vorliegende Frontend-Konzept kann auf Grund seiner FlexibilitĂ€t leicht an derlei zukĂŒnftige Entwicklungen angepasst werden
Changing the spatial location of electricity generation to increase water availability in areas with drought: a feasibility study and quantification of air quality impacts in Texas
The feasibility, cost, and air quality impacts of using electrical grids to shift water use from drought-stricken regions to areas with more water availability were examined. Power plant cooling represents a large portion of freshwater withdrawals in the United States, and shifting where electricity generation occurs can allow the grid to act as a virtual water pipeline, increasing water availability in regions with drought by reducing water consumption and withdrawals for power generation. During a 2006 drought, shifting electricity generation out of the most impacted areas of South Texas (~10% of base case generation) to other parts of the grid would have been feasible using transmission and power generation available at the time, and some areas would experience changes in air quality. Although expensive, drought-based electricity dispatch is a potential parallel strategy that can be faster to implement than other infrastructure changes, such as air cooling or water pipelines.National Science Foundation (U.S.). Office of Emerging Frontiers in Research and Innovation (Grant 0835414)United States. Dept. of Energ
Achene slime content in some taxa of Matricaria L. (Asteraceae)
The achenes of Matricaria aurea and two varieties of M. chamomilla (var. chamomilla and var. recutita) have slime cells on the surface and they are characterized by slime envelope formation during hydration. The slime in these taxa is composed of pectins and cellulose. The slime could play important role in the distribution and colonisation of new habitats in Matricaria taxa
A perspective on multinational enterpriseâs national identity dilemma
This conceptual paper identifies gaps and contributes to the literature on âidentityâ dilemmas faced by multinational enterprises operating in a globalised world. Various characteristics and business strategies of multinational enterprises are delineated and analysed through the lens of social identity theory and international business concepts such as market and institutional logic. Our analysis, based on multiple cases, and derived from a variety of industries and countries, associates the identity dilemma to informed business strategy. Our findings suggest that while multinational enterprises face identity dilemmas that they sometimes use to their advantage, it also poses several challenges. Through our conceptualisation, we derive five distinct propositions to shape future research directions
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Detection of regulator genes and eQTLs in gene networks
Genetic differences between individuals associated to quantitative phenotypic
traits, including disease states, are usually found in non-coding genomic
regions. These genetic variants are often also associated to differences in
expression levels of nearby genes (they are "expression quantitative trait
loci" or eQTLs for short) and presumably play a gene regulatory role, affecting
the status of molecular networks of interacting genes, proteins and
metabolites. Computational systems biology approaches to reconstruct causal
gene networks from large-scale omics data have therefore become essential to
understand the structure of networks controlled by eQTLs together with other
regulatory genes, and to generate detailed hypotheses about the molecular
mechanisms that lead from genotype to phenotype. Here we review the main
analytical methods and softwares to identify eQTLs and their associated genes,
to reconstruct co-expression networks and modules, to reconstruct causal
Bayesian gene and module networks, and to validate predicted networks in
silico.Comment: minor revision with typos corrected; review article; 24 pages, 2
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