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Mathematical modelling to assess the carrying capacity for multi-species culture within coastal waters

Duarte, Pedro; Meneses, Rute; Hawkins, A.J.S.; Zhu, M.; Fang, J.; Grant, J.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2003 ENG
Relevância na Pesquisa
36.09%
In the context of aquaculture, carrying capacity is generally understood as the standing stock of a particular species at which production is maximised without negatively affecting growth rates. The estimation of carrying capacity for aquaculture is a complex issue. That complexity stems from the many interactions between and among cultivated and non-cultivated species, as well as between those species and their physical and chemical environments. Mathematical models may help to resolve these interactions, by analysing them in a dynamic manner. Previous carrying capacity models have considered the biogeochemical processes that influence growth of cultivated species in great detail. However, physical processes tend to have been addressed very simplistically. Further, most modelling has been for monocultures, despite the increasing importance of multi-species (=polyculture) systems. We present here a two-dimensional coupled physical–biogeochemical model implemented for Sungo Bay, Shandong Province, People’s Republic of China. Sungo Bay is used for extensive polyculture, where bivalve shellfish and kelp are the most important cultivated species. Data collected over 13 years (1983–2000)was available for modelling. Our main objectives were to implement the model...

Thermal and environmental simulation of buildings

Ramos, João António Esteves; Pitarma, Rui A.; Carvalho, Maria da Graça
Fonte: Instituto Politécnico de Leiria Publicador: Instituto Politécnico de Leiria
Tipo: Conferência ou Objeto de Conferência
Publicado em //2002 ENG
Relevância na Pesquisa
46%
The purpose of most buildings is to provide a comfortable and healthy indoor environment for the occupants. As a result of increasing energy prices in the last decades, much effort has been done to reduce the cost arising from mechanical and natural ventilation of buildings. This often involves lowering the outdoor air intake. At the same time, many new pollution sources have been introduced in the buildings. These issues are important if we take into consideration that today the majority of the people spends more than 90% of their time indoors. In this work will be presented a physical and mathematical models to study the three-dimensional turbulent air flow patterns with thermal buoyant effects, the heat transfer, including radiation between walls, the gas contaminant trasnport and the most air transport into mechanical or natural ventilated spaces. the calculations made use of a numerical procedure, which solves the three-dimensional equations for the conservation of mass, momentum, thermal energy and air contaminant transport. The turbulence is modelled by the k-e model and thermal radiation by the discrete transfer method. To validate the mathematical model, the predictions results were compared with experimental data for two different scales - full scale office room and 1/4 laboratory scale model. A physical modelling technique...

Mean sea-level rise impacts on Santos Bay, Southeastern Brazil - physical modelling study

Alfredini, Paolo; Alfredini, Emilia Arasaki; Amaral, Rogerio Fernando do
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
55.96%
The greenhouse effect and resulting increase in the Earth`s temperature may accelerate the mean sea-level rise. The natural response of bays and estuaries to this rise, such as this case study of Santos Bay (Brazil), will include change in shoreline position, land flooding and wetlands impacts. The main impacts of this scenario were studied in a physical model built in the Coastal and Harbour Division of Hydraulic Laboratory, University of Sao Paulo, and the main conclusions are presented in this paper. The model reproduces near 1,000 km(2) of the study area, including Santos, Sao Vicente, Praia Grande, Cubatao, Guaruja and Bertioga cities.; Brazilian Environment Ministry (MMA); World Bank/GEF-Global Environment Facility; CNPq - Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (National Council for Scientific and Technological Development)[381068/2004-8]

Gas-solid two-phase flow in the riser of circulating fluidized beds: mathematical modelling and numerical simulation

Cabezas Gómez,Luben; Milioli,Fernando Eduardo
Fonte: The Brazilian Society of Mechanical Sciences Publicador: The Brazilian Society of Mechanical Sciences
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2001 EN
Relevância na Pesquisa
45.9%
A mathematical model is developed for gas-solids flows in circulating fluidized beds. An Eulerian formulation is followed based on the two-fluids model approach where both the fluid and the particulate phases are treated as a continuum. The physical modelling is discussed, including the formulation of boundary conditions and the description of the numerical methodology. Results of numerical simulation are presented and discussed. The model is validated through comparison to experiment, and simulation is performed to investigate the effects on the flow hydrodynamics of the solids viscosity.

Physical modelling in biomechanics.

Koehl, M A R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 29/09/2003 EN
Relevância na Pesquisa
46.05%
Physical models, like mathematical models, are useful tools in biomechanical research. Physical models enable investigators to explore parameter space in a way that is not possible using a comparative approach with living organisms: parameters can be varied one at a time to measure the performance consequences of each, while values and combinations not found in nature can be tested. Experiments using physical models in the laboratory or field can circumvent problems posed by uncooperative or endangered organisms. Physical models also permit some aspects of the biomechanical performance of extinct organisms to be measured. Use of properly scaled physical models allows detailed physical measurements to be made for organisms that are too small or fast to be easily studied directly. The process of physical modelling and the advantages and limitations of this approach are illustrated using examples from our research on hydrodynamic forces on sessile organisms, mechanics of hydraulic skeletons, food capture by zooplankton and odour interception by olfactory antennules.

The physical modelling of a sitar

Ronan, David
Fonte: University of Limerick Publicador: University of Limerick
Tipo: info:eu-repo/semantics/masterThesis; ul_published_reviewed; ul_theses_dissertations
ENG
Relevância na Pesquisa
66.09%
non-peer-reviewed; Three files accompany the PDF of this thesis - Sitar.mid; Main.maxpat; poly.sitar.maxpat. Sitar.mid is available here. Main.maxpat and poly.sitar.maxpat can be made available to you upon request. Please contact ULIR administration: ir@ul.ie; There has been very little research done with regard to the physical modelling synthesis of the Indian classical instrument the Sitar. This dissertation intends on expanding on what little research has been done on the subject and attempts to model the instrument with modern modelling techniques such as bi-directional digital waveguides, fractional delay filtering and sympathetic vibrations. It also presents a new and unique implementation of a dynamically changing delay line for a non-linear system such as the sitar string that has not been attempted before. It does this by making use of the Karplus-Strong algorithm to control the dynamic delay line. The Karplus-Strong was chosen because of how naturally it represents the decay of a string. This dissertation also attempts to model the sympathetic strings and the resonator of the sitar.

3D geomechanical modelling for CO₂ geologic storage in the Dogger carbonates of the Paris Basin; 3D geomechanical modelling for CO2 geologic storage in the Dogger carbonates of the Paris Basin

Vidal-Gilbert, Sandrine; Nauroy, Jean-Francois; Brosse, Etienne
Fonte: Elsevier Ltd Publicador: Elsevier Ltd
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
36.02%
CO2 injection into a depleted hydrocarbon field or aquifer may give rise to a variety of coupled physical and chemical processes. During CO2 injection, the increase in pore pressure can induce reservoir expansion. As a result the in situ stress field may change in and around the reservoir. The geomechanical behaviour induced by oil production followed by CO2 injections into an oil field reservoir in the Paris Basin has been numerically modelled. This paper deals with an evaluation of the induced deformations and in situ stress changes, and their potential effects on faults, using a 3D geomechanical model. The geomechanical analysis of the reservoir–caprock system was carried out as a feasibility study using pressure information in a “one way” coupling, where pressures issued from reservoir simulations were integrated as input for a geomechanical model. The results show that under specific assumptions the mechanical effects of CO2 injection do not affect the mechanical stability of the reservoir–caprock system. The ground vertical movement at the surface ranges from −2 mm during oil production to +2.5 mm during CO2 injection. Furthermore, the changes in in situ stresses predicted under specific assumptions by geomechanical modelling are not significant enough to jeopardize the mechanical stability of the reservoir and caprock. The stress changes issued from the 3D geomechanical modelling are also combined with a Mohr–Coulomb analysis to determine the fault slip tendency. By integrating the stress changes issued from the geomechanical modelling into the fault stability analysis...

Practical approaches to modelling natural attenuation processes at LNAPL contaminated sites; Praktische Ansätze zur Modellierung natürlicher Abbauprozesse an LNAPL-kontaminierten Standorten

Miles, Benedict
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertação
EN
Relevância na Pesquisa
36.03%
Contamination of the subsurface by LNAPLs (Light Non-Aqueous Phase Liquids), particularly fuel hydrocarbons, is a widespread problem threatening groundwater quality at affected sites. Monitored natural attenuation (MNA) is increasingly used in site management strategies in such cases as an alternative to, or in conjunction with conventional remediation measures. For the implementation of MNA at a contaminated site, contaminant emission, transport and degradation processes need to be understood and quantified and a prognosis made for the likely future development of the contamination, especially with regard to the spatial and temporal stationarity of the contaminant plume. In this respect, mathematical models describing the relevant physical processes have come to play a central role in the investigation of contaminated sites. For the field-scale simulation of MNA-relevant processes, existing model codes offer manifold possibilities in terms of model complexity and process representation. The choice of modelling approach is site- and problem-specific, taking into consideration the site data available and the questions to be addressed (i.e. the processes of interest); there is no “one-size-fits-all” solution. Three kerosene contaminated sites...

Physical modelling of water, fauna and flora: knowledge gaps, avenues for future research and infrastructural needs

THOMAS Robert E; JOHNSON Matthew; FROSTICK Lynne; PARSONS Daniel; BOUMA Tjeerd; DIJKSTRA Jasper T.; EIFF Olivier; GOBERT Sylvie; HENRY Pierre-Yves; KEMP Paul; MCLELLAND Stuart J.; MOULIN F.; MYRHAUG Daug; NEYTS A.; PAUL M.; PENNING Ellis; RICE S.p.; PUIJA
Fonte: TAYLOR & FRANCIS LTD Publicador: TAYLOR & FRANCIS LTD
Tipo: Articles in Journals Formato: Online
ENG
Relevância na Pesquisa
45.96%
Physical modelling is a key tool for generating understanding of the complex interactions between aquatic organisms and hydraulics, which is important for management of aquatic environments under environmental change and our ability to exploit ecosystem services. Many aspects of this field remain poorly understood and the use of physical models within eco-hydraulics requires advancement in methodological application and substantive understanding. This paper presents a review of the emergent themes from a workshop tasked with identifying the future infrastructure requirements of the next generation of eco-hydraulics researchers. The identified themes are: abiotic factors, adaptation, complexity and feedback, variation, and scale and scaling. The paper examines these themes and identifies how progress on each of them is key to existing and future efforts to progress our knowledge of eco-hydraulic interactions. Examples are drawn from studies on biofilms, plants, and sessile and mobile fauna in shallow water fluvial and marine environments. Examples of research gaps and directions for educational, infrastructural and technological advance are also presented.; JRC.H.7-Climate Risk Management

Physical modelling of Flowslide Mobility

Davoodi Bilesavar, ROYA
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 4752993 bytes; application/pdf
EN; EN
Relevância na Pesquisa
55.96%
Static liquefaction is a sudden decrease of soil shear strength due to the rapid development of pore pressures generated during the collapse of loose, saturated soil deposits. If this type of failure occurs in sloping soils, a flowslide can result. Viscous debris moving down a slope with high velocity could cover a vast area and cause significant loss of life and property. The primary objective of this study was to investigate the triggering factors of liquefaction in shallow slopes through the physical modeling technique of centrifuge testing. A flowslide simulator was developed to investigate the factors that lead to the liquefaction of soil slopes. This simulator was capable of replicating groundwater regimes and intense rainfalls with pore pressure transducers to monitor the pore pressure changes in the model slope and digital cameras to calculate the resultant slope deformation, velocity, and acceleration using the Particle Image Velocimetry method (PIV) of digital image correlation. In the course of this research, four centrifuge tests have been performed to evaluate the triggering mechanisms of fast landslides in shallow slopes. A seepage induced failure was simulated in the first test. The second and third tests were conducted applying different groundwater regimes in combination with intense rainfall to bring the slope to failure. The last test was a rainfall induced failure in the absence of a pre-existing groundwater table. The results from these experiments illustrate that the initial groundwater level has a considerable effect on the mobility of flowslides.; Thesis (Master...

Physical modelling of landslides in loose granular soils

Beddoe, Ryley
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
45.91%
The catastrophic consequences associated with landslides necessitate predictions of these hazards to be made with as much certainty as possible. However, the often complex nature of these events make predictions highly challenging. In this thesis, a number of hypotheses related to the triggering mechanisms and subsequent consequences of landslides in a loose-granular soil were investigated. The investigation was conducted using small-scale geotechnical centrifuge models, and a new flume facility developed to examine landslide behavior in a reduced-scale model. The first hypothesis explored in this research was that static liquefaction might preferentially occur in the saturated granular soil located at the base of the landslide rather than the well-drained inclined portion of the slope. Using a geotechnical centrifuge model, it was found that a small initial toe failure did act as a monotonic loading trigger to shear the loose contractile saturated sand at the base of the slope and caused liquefaction to occur. The second hypothesis investigated whether the consequences of a landslide triggered under elevated groundwater antecedent conditions are higher than scenarios under drier antecedent conditions. Results from five centrifuge models subjected to different antecedent groundwater conditions show that higher groundwater conditions can result in landslides with velocities about three times higher and travel distances eight times higher than low antecedent conditions. The third hypothesis investigated the influence of slope inclination on landslide consequences. Seven geotechnical centrifuge models were built and tested...

Physical Modelling of the Mobility of Dry Granular Landslides

Bryant, SARAH
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
66.12%
In geotechnical engineering, granular flows are often studied as a means to further the understanding of the mechanisms that drive landslide motion. High quality experimental data is essential in providing evidence for the development and verification of new theoretical methods that link complex grain interactions to the extended mobility of some landslide events. At present, limited experimental data is available that captures the full range of landslide mobility. In an attempt to add to the present data sources, high quality experimental data was obtained through the use of high speed cameras and physical modelling using a geotechnical centrifuge and a large scale landslide flume. These modelling techniques allow for landslide motion, representative of field scale events, to be observed in a well-defined and controlled setting. A series of nine tests were performed in a geotechnical centrifuge under varying slope inclinations and Coriolis conditions. The effects of Coriolis on landslide mobility were evident when comparing final deposit shapes and total runout. The effects of Coriolis were more pronounced for higher velocity situations and when material was travelling on the horizontal base section opposed to the sloped section of the physical model. A series of thirty tests were performed using a large scale flume under varying source volumes and basal friction conditions...

Different modelling tools of aquatic ecosystems: A proposal for a unified approach

Pereira, A.; Duarte, Pedro; Norro, A.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2006 ENG
Relevância na Pesquisa
36.14%
Over the last few decades, several modelling tools have been developed for the simulation of hydrodynamic and biogeochemical processes in aquatic ecosystems. Until late 70's, coupling hydrodynamic models to biogeochemical models was not common and today, problems linked to the different scales of interest remain. The time scale of hydrodynamic phenomena in coastal zone (minutes to hours) is much lower than that of biogeochemistry (few days). Over the last years, there has been an increasing tendency to couple hydrodynamic and biogeochemical models in a clear recognition of the importance of incorporating in one model the feedbacks between physical, chemical and biological processes. However, different modelling teams tend to adopt different modelling tools, with the result that benchmarking exercises are sometimes difficult to achieve in projects involving several institutions. Therefore, the objectives of this paper are to provide a quick overview of available modelling approaches for hydrodynamic and biogeochemical modelling, to help people choose among the diversity of available models, as a function of their particular needs, and to propose a unified approach to allow modellers to share software code, based on the object oriented programming potentiality. This approach is based on having object dynamic link libraries that may be linked to different model shells. Each object represents different processes and respective variables...

Physical Modelling of the Zodiacal Dust Cloud

Ozernoy, Leonid M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/12/2000
Relevância na Pesquisa
46.08%
(abridged) This review is based on an extensive work done in collaboration with N. Gorkavyi, J. Mather, and T. Taidakova, which aimed at the physical modelling of the interplanetary dust (IPD) cloud in the Solar system, i.e., establishing a link between the observable characteristics of the zodiacal cloud and the dynamical and physical properties of the parent minor bodies. Our computational approach permits with modest computer resources to integrate the trajectories of hundreds of particles and to effectively store up to $10^{10-11}$ positions, which provides a high fidelity 3D distribution of the dust. Our numerical codes account for the major dynamical effects that govern the motion of IPD particles. We have demonstrated the efficacy of our codes by performing the following analyses: (i) simulation of the distribution of Centaurs (comets scattered in their journey from the Kuiper belt inward the Solar system) and revealing the effects of the outer planets in producing `cometary belts'; (ii) detailed inspection of a rich resonant structure found in these belts, which predicts the existence of gaps similar to the Kirkwood gaps in the main asteroid belt; (iii) a preliminary 3-D physical model of the IPD cloud, which includes three dust components -- asteroidal...

On Time: Implications in Physical Modelling and Numerical Analysis

Vassiliadis, Vassilios S
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Tipo: Conferência ou Objeto de Conferência
EN
Relevância na Pesquisa
45.96%
Presentation at the weekly group meeting of the Process Systems Engineering (PSE) Research Group, at the Department of Chemical Engineering and Biotechnology, University of Cambridge.; This presentation examines the issue of 'time' from a multitude of points of consideration. These include (a) philosophy, (b) perception of time and neurology, (c) physics and engineering, (d) mathematics, (e) numerical analysis and computing. Perhaps the most important conclusion from this extensive analysis and presentation of material on the topic of what time really is, is described by the following. Definition of Time: Time is the human perception described by storage of a prior experienced state(s) through the senses (internal or external), its (their) replacement at discrete (almost, perhaps) instances by a new input and its comparison with what is stored in memory. We call duration the magnitude of the differences of the older stored state(s) in memory with the new, fresh input. The larger the difference the faster we perceive something to be ('of higher rate'), hence the shorter the perceived duration. Furthermore, the implications regarding the validity of the very foundations of mathematics and its use in physical modelling and in computing models of the real physical world are examined in detail.

Decarbonising the English residential sector: modelling policies, technologies and behaviour within a heterogeneous building stock; Modelling policies, technologies and human behaviour within a heterogeneous building stock; A new building stock model for the english residential sector; A systems approach to modelling energy and emissions from the residential sector

Kelly, Scott
Fonte: University of Cambridge; Department of Land Economy; Cambridge Centre for Climate Change Mitigation Research; Selwyn College Publicador: University of Cambridge; Department of Land Economy; Cambridge Centre for Climate Change Mitigation Research; Selwyn College
Tipo: Thesis; doctoral; PhD
EN
Relevância na Pesquisa
36.17%
It is now widely accepted that the residential sector offers significant potential for carbon mitigation. This is true for both the overall magnitude of emissions reductions and the cost per tonne of CO2(eq) mitigated. However, both the scope and scale of potential carbon mitigation pathways remain controversial. The pace of decarbonisation is also openly debated. Examples of some of these contentions include: centralised versus decentralised energy supply; energy efficiency versus low carbon generation; demolition versus renovation of the existing building stock and behaviour change versus technological solutions. Incontrovertibly, any one of these seemingly apparent tensions is not mutually exclusive, and the ultimate decarbonisation pathway will likely consist of most if not all of these proposed solutions being implemented to some varying degree. Despite the significant potential for carbon mitigation in the built environment, deep cuts have not yet materialised. It is argued that this lack of progress stems from a poor understanding of the highly complex socio-economic, socio-dynamic and technical physical systems that underpin energy use in dwellings.Modelling this requires requires novel methods capable of capturing the complexities that arise from government policies...

Modelling of friction stir spot welding

Reilly, Aidan
Fonte: University of Cambridge; Department of Engineering; Sidney Sussex College; Trinity Hall Publicador: University of Cambridge; Department of Engineering; Sidney Sussex College; Trinity Hall
Tipo: Thesis; doctoral; PhD
EN
Relevância na Pesquisa
36.03%
Friction stir spot welding (FSSW) is a solid-state welding process which is especially useful for joining precipitation-hardened aluminium alloys that undergo adverse property changes during fusion welding. It also has potential as an effective method for solid-state joining of dissimilar alloys. In FSSW, heat generation and plastic flow are strongly linked, and the scale of the process in time and space is such that it is difficult to separate and control the influence of all the relevant input parameters. The use of modelling is well-established in the field of welding research, and this thesis presents an analysis of the thermal and mechanical aspects of FSSW, principally using the finite element (FE) technique. Firstly, a thermal FE model is shown, which is subsequently validated by reference to experimental temperature data in both aluminium-to-aluminium and aluminium-to-steel welds. Correlations between high-quality welds and temperature fields are established, and predictions are made for peak temperatures reached under novel welding conditions. Deformation and heating are strongly linked in FSSW, but existing modelling tools are poorly suited to modelling flow processes in the conditions extant in FSSW. This thesis discusses the development and optimisation of two novel techniques to overcome the limitations of current approaches. The first of these uses greatly simplified constitutive behaviour to convert the problem into one defined purely by kinematics. In doing so...

Towards models of gravitational waveforms from generic binaries: II. Modelling precession effects with a single effective precession parameter

Schmidt, Patricia; Ohme, Frank; Hannam, Mark
Fonte: American Physical Society Publicador: American Physical Society
Tipo: Article; PeerReviewed Formato: application/pdf; application/pdf
Publicado em 29/01/2015
Relevância na Pesquisa
36.04%
Gravitational waves (GWs) emitted by generic black-hole binaries show a rich structure that directly reflects the complex dynamics introduced by the precession of the orbital plane, which poses a real challenge to the development of generic waveform models. Recent progress in modelling these signals relies on an approximate decoupling between the nonprecessing secular inspiral and a precession-induced rotation. However, the latter depends in general on all physical parameters of the binary which makes modelling efforts as well as understanding parameter-estimation prospects prohibitively complex. Here we show that the dominant precession effects can be captured by a reduced set of spin parameters. Specifically, we introduce a single effective precession spin parameter, χ_p, which is defined from the spin components that lie in the orbital plane at some (arbitrary) instant during the inspiral. We test the efficacy of this parameter by considering binary inspiral configurations specified by the physical parameters of a corresponding nonprecessing-binary configuration (total mass, mass ratio, and spin components (anti)parallel to the orbital angular momentum), plus the effective precession spin applied to the larger black hole. We show that for an overwhelming majority of random precessing configurations...

Um esforço de interpretação empírica da variação nos níveis de aptidão física a partir da modelação hierárquica: um estudo em crianças dos seis aos 10 anos de idade da região de Amarante - Portugal; Empirical interpretation of variation in physical fitness levels based on hierarchical modelling: a study in children from six to 10 years of age from the Amarante region - Portugal

Maia, José António Ribeiro; Carneiro, Maria; Silva, Rui Garganta da; Pereira, Simonete; Seabra, André; Bustamante, Alcibíades; Fermino, Rogério César
Fonte: Universidade de São Paulo. Escola de Educação Física e Esporte Publicador: Universidade de São Paulo. Escola de Educação Física e Esporte
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; Formato: application/pdf
Publicado em 01/03/2006 POR
Relevância na Pesquisa
36.08%
O objetivo deste estudo foi identificar e interpretar o significado da influência de determinantes que expliquem a heterogeneidade da aptidão física relacionada à saúde (AptFS) com base na abordagem da modelação hierárquica. Foram amostradas 1779 crianças dos seis aos 10 anos de idade da região de Amarante no norte de Portugal. Os determinantes considerados foram as condições ambientais de implantação das escolas, aspectos sócio-geográficos, recursos materiais e humanos. A AptFS foi avaliada com a bateria Fitnessgram e a atividade física (ActF) foi estimada com base no questionário de GODIN & SHEPHARD (1985). A análise dos dados foi feita com “software” HLM 6.02. Constatou-se a presença de uma hierarquia informacional atribuindo às escolas uma parte da explicação (0,05 < rho < 0,31). A maior variabilidade interindividual ocorreu na prova da milha sendo a idade, o sexo, os níveis de ActF e o índice de massa corporal (IMC) os maiores preditores. As condições ambientais do meio escolar e as estruturas humanas e escolares não foram incluídas nos modelos por ausência de significado estatístico. As conclusões remetem-nos: 1) para a necessidade do uso da modelação hierárquica no estudo da complexidade informacional da AptFS; 2) para a forte presença de variabilidade interindividual nos níveis de aptidão; 3) na forte influência da idade...

Physical and numerical modelling of a four-strand steelmaking tundish using flow analysis of different configurations

Cloete,J.H.; Akdogan,G.; Bradshaw,S.M.; Chibwe,D.K.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2015 EN
Relevância na Pesquisa
46.12%
Modern tundishes have evolved as vessels to serve as the final step in refining of molten steel by removing inclusions and promoting thermo-chemical homogeneity. In this study the flow behaviour in a four-strand tundish was investigated by means of a ½-scale water model as well as numerical modelling. The numerical and physical models were used to characterize residence time distribution and calculate properties pertaining to tundish flow regime. Three different tundish configurations were investigated: a bare tundish with no flow control devices, a tundish with a turbulence inhibitor, and a tundish with both a turbulence inhibitor and a dam. The physical and numerical models showed that a tundish without flow control devices is prone to significant short-circuiting. A tundish with a turbulence inhibitor was shown to be successful in preventing short-circuiting and provided surface-directed flow that might assist the removal of inclusions from the melt. However, it was also observed that the upward-directed flow caused the maximum turbulence kinetic energy near the surface to increase dramatically. The potential for slag entrainment should therefore be considered during the design and operation of tundishes with turbulence inhibitors.