8,788 research outputs found
Phase transition of a two dimensional binary spreading model
We investigated the phase transition behavior of a binary spreading process
in two dimensions for different particle diffusion strengths (). We found
that cluster mean-field approximations must be considered to get
consistent singular behavior. The approximations result in a continuous
phase transition belonging to a single universality class along the phase transition line. Large scale simulations of the particle density
confirmed mean-field scaling behavior with logarithmic corrections. This is
interpreted as numerical evidence supporting that the upper critical dimension
in this model is .The pair density scales in a similar way but with an
additional logarithmic factor to the order parameter. At the D=0 endpoint of
the transition line we found DP criticality.Comment: 8 pages, 10 figure
How does economic crisis impact on family vacations?
PURPOSE: This study aims at improving the understanding of the behavior of Portuguese consumers regarding vacations in a severe recessionary context, as well as providing knowledge contributing to the consumer behavior field of research as far as the hospitality industry is concerned. DESIGN: Having that purpose in mind, a quantitative study was conducted using data gathered by questionnaire involving a sample of 450 respondents. Results of the quantitative analysis were further complemented with the information previously collected using Netnography. FINDINGS: The overall analysis suggests that the impact of the crisis on the household financial situation throughout the last couple of years influences decisions towards family vacations. When referring to attitudes toward money and expenses, the perception consumers have of how much their purchase and consumption behavior was affected by the crisis has a clear impact to the maximum amount spent on holidays, travel and tourism by the household. Indeed, nowadays customers better ponder every purchase they make, and they often imagine what they would do if they had more money – and, specifically, regarding tourism products. PRACTICAL IMPLICATIONS: There is evidence of a significant relationship between the change in holiday plans and how much the household was affected by the crisis. Also, it is important to note that the main sources of information chosen by customers to base their decisions regarding changing holiday’s plans reflects their change in behavior, since the cheapest strategies to communicate and gather information are the ones most used: e-word of mouth and digital platforms.info:eu-repo/semantics/acceptedVersio
Heat Recovery Opportunities from Electrical Substation Transformers
The transformation of voltages in electrical substations leads to energy losses in the form of waste heat; the quantity of which depends on transformer size and electrical loading. This paper investigates how a novel waste heat source, namely transformer waste heat could be harvested and distributed via district heating networks. Firstly, the investigation considered nameplate heat loss factors to quantify the theoretical waste heat potential from electrical substation transformers in England, Wales and Northern Ireland, which varied from 3.0 to 5.4 TWh.a-1, equivalent to between 0.7 and 1.25% of annual heat demand for these countries, depending on loading assumptions. A number of heat recovery approaches which could be integrated with existing transformer cooling systems were then proposed. A spreadsheet model was then developed to simulate heat recovery from a transformer, together with the upgrade of the recovered heat using a heat pump prior to delivery via district heating. The model was used to evaluate the merits of capturing transformer waste heat losses, estimated using industry supplied electrical loading data, to meet different heat network demands based on an existing network, compared to conventional heating technologies. Findings suggest that the system proposed can achieve levelised costs that are up to 17% lower than the running costs of air-source heat pumps, whilst reducing emissions by almost 80% when displacing gas boilers. The methodology hereby described can also be used to evaluate the feasibility of recovering transformer waste heat in other countries
A Case Study of the Integration of Mine water into Smart Cooling and Heating Network systems
Minewater presents a significant opportunity as an energy source and store in the UK and elsewhere. This research investigates the feasibility and factors necessary to successfully integrate minewater into smart cooling and heating network systems that can support acceleration towards the UK’s net zero target. Heat recovery from minewater offers a lowcarbon source of energy for either heating or cooling and can provide thermal storage, potentially valuable for inter-seasonal demand. The work builds on a feasibility study in Barnsley, Yorkshire, which explored the design of a heat network that integrates heat, power, and mobility and uses waste heat from a glass factory. This work focusses on analyzing the subsurface factors including flowrate, yield, mine void volume, and interconnectivity, which affect the flow and consequently thermal behavior of the available minewater. A 3D model using Petrel and Groundhog have been created combining data from the available boreholes and Coal Authority maps to characterise the subsurface conditions
Mine water utilization as a secondary heat source and heat storage in a smart local heating and cooling distribution system
Mine water has been gaining increasing attention in recent years as a potential source for heat recovery and storage. This is due to its unique properties that make it an ideal medium for capturing and storing large amounts of thermal energy. Mine water is naturally heated by the earth's geothermal energy and typically has a constant temperature throughout the year, making it an excellent source
of renewable energy. Additionally, the water's high thermal conductivity and large volumes provide an effective means for storing and transferring heat. With the increasing demand for sustainable energy sources and the need to reduce greenhouse gas emissions, the utilization of mine water for heat recovery and storage has become an attractive option for many industries and communities. In this project, we will explore the benefits of using mine water for heat recovery and storage, as well as some of the risks and challenges that need to be overcome to fully realize its potential as a renewable energy source
Poliomielite associada à vacina: descrição de caso por transmissão domiciliar
Poliomyelitis associated with live strain vaccine is defined as the paralytic form of the acute anterior poliomyelitis related to the vaccine strain. Since these strains behave similarly to the wild-type virus, we can differentiate, epidemiologically, two types of vaccine-associated poliomyelitis: cases in which the patient was vaccinated and cases in which the patient had had contact with vaccinated individuals. We herein present the case of an unvaccinated child, with a clinical picture of an acute anterior poliomyelitis associated with the live strain vaccine, whose brother received the Sabin vaccine 20 days before the onset of the symptoms. Vaccine strain of the type 3 poliovirus was isolated in fecal culture and a presented mutation in nucleotide 472 (C;®;U) in the 5' non-coding region, which is strongly related to the higher strain virulence.A poliomielite associada à vacina oral é definida como a forma paralÃtica da poliomielite anterior aguda decorrente da cepa vacinal. Uma vez que o comportamento da cepa vacinal é semelhante ao do vÃrus selvagem, epidemiologicamente podemos distinguir dois tipos de poliomielite associada à vacina, os casos em que o paciente foi vacinado e os casos em que o paciente teve contato com pessoas que receberam a vacina. Apresentamos o caso de um lactente não vacinado, que apresentou quadro de poliomielite anterior aguda associada à vacina oral, cujo irmão havia recebido a vacina Sabin 20 dias antes do inÃcio do quadro clÃnico. Na cultura de fezes do paciente foi isolado o poliovÃrus tipo 3, cepa vacinal, que apresentava mutação do nucleotÃdeo 472 (C;®;U) na região 5' não codificadora, a qual está significativamente relacionada com a maior virulência da cepa
The Richardson's Law in Large-Eddy Simulations of Boundary Layer flows
Relative dispersion in a neutrally stratified planetary boundary layer (PBL)
is investigated by means of Large-Eddy Simulations (LES). Despite the small
extension of the inertial range of scales in the simulated PBL, our Lagrangian
statistics turns out to be compatible with the Richardson law for the
average of square particle separation. This emerges from the application of
nonstandard methods of analysis through which a precise measure of the
Richardson constant was also possible. Its values is estimated as
in close agreement with recent experiments and three-dimensional direct
numerical simulations.Comment: 15 LaTex pages, 4 PS figure
On the violation of a local form of the Lieb-Oxford bound
In the framework of density-functional theory, several popular density
functionals for exchange and correlation have been constructed to satisfy a
local form of the Lieb-Oxford bound. In its original global expression, the
bound represents a rigorous lower limit for the indirect Coulomb interaction
energy. Here we employ exact-exchange calculations for the G2 test set to show
that the local form of the bound is violated in an extensive range of both the
dimensionless gradient and the average electron density. Hence, the results
demonstrate the severity in the usage of the local form of the bound in
functional development. On the other hand, our results suggest alternative ways
to construct accurate density functionals for the exchange energy.Comment: (Submitted on 27 April 2012
Transport, Industrial and Commercial Refrigeration – A research project
The Climate Change Act commits the UK to reach net zero emissions by 2050, tackling hard to abate areas. A significant energy end use, often overlooked in policy, is refrigeration and there is a gap in our understanding of transport, industrial and commercial refrigeration (TICR) emissions. Essential for multiple applications across the cold chain, this paper assesses the size of TICR emissions, and opportunities for research and innovation. Our initial results suggest that 6% of industrial electricity use is for refrigeration, with large uncertainty in this figure. To address this knowledge gap, we reviewed available data sources to estimate the UK’s carbon emissions and produce a breakdown per application sector. In an industry dominated by SMEs with low-risk appetite and innovations with low readiness levels, we explore ways, which TICR could decarbonise in order to reach the UK’s Net Zero ambitions, through innovation and better data
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