The impact of friends on newly immigrant children's emotional and behavioral adjustment

Immigration disrupts an individual's support network; however, the stresses of the immigration process increase the need for social support. The presence of social support becomes essential for immigrant children and adolescents to cope with these important transitional circumstances. Friends are both sources of social support and models for behavior. Furthermore, friendship networks are known to have a significant influence on youths' functioning. Literature suggests that peer relations become more important in adolescence and friend support is related to child and adolescent well-being. Thus, friend relationships may be particularly important for immigrant youths who experience disruption in their friendship networks during the process of migration to another country. In addition to friendship networks and support, friend characteristics also need to be taken into consideration as important factors for immigrant youth adjustment. My study involved analyses of the effects of friend support and friend problem behaviors on emotional and behavioral functioning for elementary, middle, and high school age newly immigrant children and adolescents. ^ Immigrant children and adolescents (N = 503) were interviewed at schools by interviewers fluent in participants' languages. Structural Equation Modeling (SEM) analyses revealed that friend support and friend problem behaviors were related to children's self-esteem and externalizing behaviors. In addition, friend problem behavior alone predicted children's psychological symptoms and depression scores. Furthermore, age/grade was found to be a moderator for the relation between friend problem behavior and immigrant youth behavioral adjustment such that compared to elementary and high school cohorts, middle school youths showed more externalizing behaviors when they had friends performing problem behaviors. ^ Results supported the idea that both friend support and friend behavior are related to newly immigrant youths' emotional and behavioral adjustment. This study informs further research and interventions concerning the development of programs to facilitate immigrant youths' adjustment by revealing friendship factors related to their adaptation.^

Numerical heat transfer analysis of carbon-based foams for use in thermal protection system

The applicability of carbon-based foams as an insulating or active cooling material in thermal protection systems (TPSs) of space vehicles is considered using a computer modeling. This study focuses on numerical investigation of the performance of carbon foams for use in TPSs of space vehicles. Two kinds of carbon foams are considered in this study. For active cooling, the carbon foam that has a thermal conductivity of 100 W/m-k is used and for the insulation, the carbon foam having a thermal conductivity of 0.225 W/m-k is used. A 3D geometry is employed to simulate coolant flow and heat transfer through carbon foam model. Gambit has been used to model the 3D geometry and the numerical simulation is carried out in FLUENT. Numerical results from this thesis suggests that the use of CFOAM and HTC carbon foams in TPS's may effectively protect the aluminum structure of the space shuttle during reentry of the space vehicle.

Computational fluid dynamics (CFD) based approach to consequence assessment of accidental release of hydrocarbon during storage and transportation

This thesis investigated the risk of accidental release of hydrocarbons during transportation and storage. Transportation of hydrocarbons from an offshore platform to processing units through subsea pipelines involves risk of release due to pipeline leakage resulting from corrosion, plastic deformation caused by seabed shakedown or damaged by contact with drifting iceberg. The environmental impacts of hydrocarbon dispersion can be severe. Overall safety and economic concerns of pipeline leakage at subsea environment are immense. A large leak can be detected by employing conventional technology such as, radar, intelligent pigging or chemical tracer but in a remote location like subsea or arctic, a small chronic leak may be undetected for a period of time. In case of storage, an accidental release of hydrocarbon from the storage tank could lead pool fire; further it could escalate to domino effects. This chain of accidents may lead to extremely severe consequences. Analyzing past accident scenarios it is observed that more than half of the industrial domino accidents involved fire as a primary event, and some other factors for instance, wind speed and direction, fuel type and engulfment of the compound. In this thesis, a computational fluid dynamics (CFD) approach is taken to model the subsea pipeline leak and the pool fire from a storage tank. A commercial software package ANSYS FLUENT Workbench 15 is used to model the subsea pipeline leakage. The CFD simulation results of four different types of fluids showed that the static pressure and pressure gradient along the axial length of the pipeline have a sharp signature variation near the leak orifice at steady state condition. Transient simulation is performed to obtain the acoustic signature of the pipe near leak orifice. The power spectral density (PSD) of acoustic signal is strong near the leak orifice and it dissipates as the distance and orientation from the leak orifice increase. The high-pressure fluid flow generates more noise than the low-pressure fluid flow. In order to model the pool fire from the storage tank, ANSYS CFX Workbench 14 is used. The CFD results show that the wind speed has significant contribution on the behavior of pool fire and its domino effects. The radiation contours are also obtained from CFD post processing, which can be applied for risk analysis. The outcome of this study will be helpful for better understanding of the domino effects of pool fire in complex geometrical settings of process industries. The attempt to reduce and prevent risks is discussed based on the results obtained from the numerical simulations of the numerical models.

Komputerowe gry edukacyjne dla dzieci z trudnościami w czytaniu – doświadczenia polskie i irlandzkie.

W latach 2011-13 przeprowadziliśmy projekt badawczy, którego celem była ocena skuteczności komputerowych gier edukacyjnych jako narzędzia do treningu tempa czytania w pracy z dziećmi wolno czytającymi. W projekcie napotkaliśmy szereg nieprzewidzianych trudności; niniejszy artykuł stanowi refleksję nad nimi z perspektywy praktycznych możliwości i ograniczeń korzystania z komputerowych gier edukacyjnych w terapii pedagogicznej. Powolne czytanie rozumiemy jako trudność w automatyzacji procesu dekodowania. Zakładamy, że natura treningu komputerowego może służyć zaprojektowaniu skutecznego narzędzia do poprawy automatyzacji dekodowania. W tekście opisujemy przebieg trzykrotnej próby wdrożenia treningu tempa czytania dla dzieci z klas 3-6 na podstawie edukacyjnej gry komputerowej GraphoGame-Fluent. Okazało się, że zebrane w rezultacie dane były niewystarczające do odpowiedzi na postawione przez nas pytania dotyczące efektywności treningu i jego poszczególnych parametrów (tj. rodzaj trenowanego materiału – sylaba / wyraz, frekwencja w języku pisanym). W związku z powyższym, przedstawiamy krytyczne uwagi na temat trudności stojących przed badaczem (a także terapeutą) chcącym stosować edukacyjne gry komputerowe w terapii. Trudności mogą dotyczyć etapu wyboru gry (czy jest odpowiednia do problemu ucznia, skuteczna i motywująca), technicznych trudności ze sprzętem (dostępność komputerów i akcesoriów) oraz organizacji treningu (ograniczenia wynikające ze sztywnego stosowania systemu klasowo-lekcyjnego). Opis trudności w prowadzeniu badań w polskich szkołach zestawiamy z opisem takiego samego badania prowadzonego przez nas w szkołach w Irlandii.

Przygotowanie i podział na sylaby korpusu tekstów dla dzieci.

Artykuł dotyczy korpusu tekstów dla dzieci, który został utworzony na potrzeby projektu Graphogame-Fluent*, poświęconego ocenie skuteczności komputerowych gier edukacyjnych w terapii trudności w czytaniu (Szczerbiński et al. 2012). W artykule poruszono zagadnienia związane z przygotowaniem korpusu, przy czym najwięcej uwagi poświęcono podziałowi korpusu na sylaby (Śledziński 2010). W publikacji przedstawiono kilka istotnych pojęć lingwistycznych – definicje: sylaby, sonorności i skali sonorności. Na podstawie dostępnych definicji nie da się przeprowadzić jednoznacznego podziału na sylaby. Problem ten w szczególności dotyczy języka polskiego – ze względu na występujące licznie wieloelementowe grupy spółgłoskowe o strukturze niespotykanej w innych językach. Na potrzeby praktyczne można jednak zastosować określone procedury i rozwiązania umowne. W artykule zaproponowano dwuetapową procedurę sylabizacji. Pierwszy etap obejmuje wyznaczenie kategorii zbitek spółgłoskowych oraz ustalenie dla tych kategorii wstępnego podziału opartego na zasadzie sonorności (jeżeli jest to możliwe). Etap drugi związany jest z ustaleniem umownych szczegółowych reguł podziału dla konkretnych zbitek spółgłoskowych przy uwzględnieniu wskazówek, które również zostały omówione w artykule.

Experimental and RANS-CFD Study of Nacelle Drag

The drag on a nacelle model was investigated experimentally and computationally to provide guidance and insight into the capabilities of RANS-based CFD. The research goal was to determine whether industry constrained CFD could participate in the aerodynamic design of nacelle bodies. Grid refinement level, turbulence model and near wall treatment settings, to predict drag to the highest accuracy, were key deliverables. Cold flow low-speed wind tunnel experiments were conducted at a Reynolds number of 6∙〖10〗^5, 293 K and a Mach number of 0.1. Total drag force was measured by a six-component force balance. Detailed wake analysis, using a seven-hole pressure probe traverse, allowed for drag decomposition via the far-field method. Drag decomposition was performed through a range of angles of attack between 0o and 45o. Both methods agreed on total drag within their respective uncertainties. Reversed flow at the measurement plane and saturation of the load cell caused discrepancies at high angles of attack. A parallel CFD study was conducted using commercial software, ICEM 15.0 and FLUENT 15.0. Simulating a similar nacelle geometry operating under inlet boundary conditions obtained through wind tunnel characterization allowed for direct comparisons with experiment. It was determined that the Realizable k-ϵ was best suited for drag prediction of this geometry. This model predicted the axial momentum loss and secondary flow in the wake, as well as the integrated surface forces, within experimental error up to 20o angle of attack. SST k-ω required additional surface grid resolution on the nacelle suction side, resulting in 15% more elements, due to separation point prediction sensitivity. It was further recommended to apply enhanced wall treatment to more accurately capture the viscous drag and separated flow structures. Overall, total drag was predicted within 5% at 0o angle of attack and 10% at 20o, each within experimental uncertainty. What is more, the form and induced drag predicted by CFD and measured by the wake traverse shared good agreement. Which indicated CFD captured the key flow features accurately despite simplification of the nacelle interior geometry.

Heat Transfer in an Airfoil Shaped Strut

The heat transfer from a hot primary flow stream passing over the outside of an airfoil shaped strut to a cool secondary flow stream passing through the inside of that strut was studied experimentally and numerically. The results showed that the heat transfer on the inside of the strut could be reliably modeled as a developing flow and described using a power law model. The heat transfer on the outside of the strut was complicated by flow separation and stall on the suction side of the strut at high angles of attack. This separation was quite sensitive to the condition of the turbulence in the flow passing over the strut, with the size of the separated wake changing significantly as the mean magnitude and levels of anisotropy were varied. The point of first stall moved by as much as 15% of the chord, while average heat transfer levels changed by 2-5% as the inlet condition was varied. This dependence on inlet conditions meant that comparisons between experiment and steady RANS based CFD were quite poor. Differences between the CFD and experiment were attributed to anisotropic and unsteady effects. The coupling between the two flows was shown to be quite low - that is to say, heat transfer coefficients on both the inner and outer surfaces of the strut were relatively unaffected by the temperature of the strut, and it was possible to predict the temperature on the strut surface quite reliably using heat transfer data from decoupled tests, especially for CFD simulations.

Formal and informal translation and interpretation for immigrants and asylum seekers

As of 2011 there were over 50,000 migrants, who speak a language other than English or Irish at home, residing in Northern Ireland. Many of these individuals do not possess adequate levels of English language proficiency in order to access services. Research funded by the Northern Ireland Inclusion and Diversity Service was conducted to determine the home-school connections of culturally and linguistically diverse families in Northern Ireland. It revealed that there are a wide variety of ways that translation and interpretation services are offered for families not fluent in English within the school settings. Drawing upon the findings from the research in Northern Ireland, this presentation provides an overview of the types of translation and interpretation taking place in Northern Ireland; the advantages and disadvantages of each; and recommendations for agencies utilizing both formal and informal translation and interpretation. The presentation also includes references to work in this area in other contexts, as well as specific guidelines for agencies using both formal and informal translation and interpretation. These guidelines help ensure that the translations are conducted in a professional manner for all agencies providing services.

Design and development of a diagonal-airflow batch dryer for spatial drying homogeneity

Das Verfahren der Lebensmitteltrocknung wird häufig angewendet, um ein Produkt für längere Zeit haltbar zu machen. Obst und Gemüse sind aufgrund ihres hohen Wassergehalts leicht verderblich durch biochemische Vorgänge innerhalb des Produktes, nicht sachgemäße Lagerung und unzureichende Transportmöglichkeiten. Um solche Verluste zu vermeiden wird die direkte Trocknung eingesetzt, welche die älteste Methode zum langfristigen haltbarmachen ist. Diese Methode ist jedoch veraltet und kann den heutigen Herausforderungen nicht gerecht werden. In der vorliegenden Arbeit wurde ein neuer Chargentrockner, mit diagonalem Luftstömungskanal entlang der Länge des Trocknungsraumes und ohne Leitbleche entwickelt. Neben dem unbestreitbaren Nutzen der Verwendung von Leitblechen, erhöhen diese jedoch die Konstruktionskosten und führen auch zu einer Erhöhung des Druckverlustes. Dadurch wird im Trocknungsprozess mehr Energie verbraucht. Um eine räumlich gleichmäßige Trocknung ohne Leitbleche zu erreichen, wurden die Lebensmittelbehälter diagonal entlang der Länge des Trockners platziert. Das vorrangige Ziel des diagonalen Kanals war, die einströmende, warme Luft gleichmäßig auf das gesamte Produkt auszurichten. Die Simulation des Luftstroms wurde mit ANSYS-Fluent in der ANSYS Workbench Plattform durchgeführt. Zwei verschiedene Geometrien der Trocknungskammer, diagonal und nicht diagonal, wurden modelliert und die Ergebnisse für eine gleichmäßige Luftverteilung aus dem diagonalen Luftströmungsdesign erhalten. Es wurde eine Reihe von Experimenten durchgeführt, um das Design zu bewerten. Kartoffelscheiben dienten als Trocknungsgut. Die statistischen Ergebnisse zeigen einen guten Korrelationskoeffizienten für die Luftstromverteilung (87,09%) zwischen dem durchschnittlich vorhergesagten und der durchschnittlichen gemessenen Strömungsgeschwindigkeit. Um den Effekt der gleichmäßigen Luftverteilung auf die Veränderung der Qualität zu bewerten, wurde die Farbe des Produktes, entlang der gesamten Länge der Trocknungskammer kontaktfrei im on-line-Verfahren bestimmt. Zu diesem Zweck wurde eine Imaging-Box, bestehend aus Kamera und Beleuchtung entwickelt. Räumliche Unterschiede dieses Qualitätsparameters wurden als Kriterium gewählt, um die gleichmäßige Trocknungsqualität in der Trocknungskammer zu bewerten. Entscheidend beim Lebensmittel-Chargentrockner ist sein Energieverbrauch. Dafür wurden thermodynamische Analysen des Trockners durchgeführt. Die Energieeffizienz des Systems wurde unter den gewählten Trocknungsbedingungen mit 50,16% kalkuliert. Die durchschnittlich genutzten Energie in Form von Elektrizität zur Herstellung von 1kg getrockneter Kartoffeln wurde mit weniger als 16,24 MJ/kg und weniger als 4,78 MJ/kg Wasser zum verdampfen bei einer sehr hohen Temperatur von jeweils 65°C und Scheibendicken von 5mm kalkuliert. Die Energie- und Exergieanalysen für diagonale Chargentrockner wurden zudem mit denen anderer Chargentrockner verglichen. Die Auswahl von Trocknungstemperatur, Massenflussrate der Trocknungsluft, Trocknerkapazität und Heiztyp sind die wichtigen Parameter zur Bewertung der genutzten Energie von Chargentrocknern. Die Entwicklung des diagonalen Chargentrockners ist eine nützliche und effektive Möglichkeit um dei Trocknungshomogenität zu erhöhen. Das Design erlaubt es, das gesamte Produkt in der Trocknungskammer gleichmäßigen Luftverhältnissen auszusetzen, statt die Luft von einer Horde zur nächsten zu leiten.

Musicalidades Quotidianas da Personalidade: estudo sobre o impacto da música na personalidade, comportamentos, emoções e quotidiano de jovens e adultos de língua portuguesa

Objetivos: A música, incomum pela sua ubiquidade e antiguidade, constitui uma das atividades humanas que ocupa um lugar significativo nas diversas culturas e vida diária. Geralmente agradável para grande parte das pessoas, produz numerosos e desmedidos efeitos, na sua maioria positivos para o ser humano. Esta investigação teve como objetivo principal estudar a relação entre alguns dos diferentes géneros musicais e os de traços de personalidade de jovens e de adultos com idades compreendidas entre os 18 e os 38 anos, fluentes em português. A investigação pretendeu descrever as preferências musicais em função da idade, género, estado civil e habilitações literárias; identificar os contextos, os períodos e as atividades mais comuns durante a escuta de música; reconhecer se a música é uma das atividades de lazer mais importantes para o grupo estudado; conhecer quais as razões mais frequentes apontadas pelos sujeitos para ouvir música; estudar a perceção que as pessoas têm sobre a influência da música na violência e no consumo de substâncias; verificar se os sujeitos consideram as preferências musicais como um fator importante e revelador de informações sobre a personalidade; avaliar o impacto e relação das preferências musicais com a personalidade e verificar quais os pares de emoções mais comuns, sentidos durante a escuta musical, e respetiva intensidade. Metodologia: A amostra foi constituída por 320 indivíduos com idades compreendidas entre os 18 e os 38 anos sendo a faixa etária mais comum a que se situa entre os 24 a 29 anos, maioritariamente do sexo feminino, solteiros, de nacionalidade portuguesa, detentores ou a frequentar um curso superior, nas áreas das ciências sociais/serviços ou exatas e tecnológicas. Os participantes aceitaram responder voluntariamente a uma bateria de testes (QCS, EPI, QMQEC e STOMP-PT). Para a caracterização da amostra, determinaram-se frequências absolutas e relativas ou valores médios e desvios-padrão. A normalidade da distribuição das pontuações médias dos instrumentos foi validada com o teste de Kolmogorov-Smirnov com correção de Lilliefors. A consistência interna estudou-se através do Alpha de Cronbach e da fórmula de Kuder Richarson. As diferenças entre grupos foram avaliadas recorrendo a uma ANOVA, a intensidade e magnitude das relações entre variáveis determinou-se através do coeficiente Eta quadrado (e 2) e com o coeficiente de correlação de Pearson avaliou-se a associação entre as variáveis em estudo. Resultados: Observou-se que a música energética é a mais típica dos escalões etários mais jovens, sendo que a rebelde trespassa todas as gerações, revelando os mais velhos também uma forte preferência pela música reflexiva. As escolhas musicais parecem não ser influenciadas pelo sexo e estado civil. Os indivíduos menos escolarizados parecem preferir músicas do tipo energético, excluindo as convencionais enquanto os detentores de maiores habilitações preferem os estilos reflexivos e rebeldes. É em casa, no quarto, ao fim de semana e quando estão sozinhos que os participantes mais ouvem música, constituindo esta a mais frequente atividade de lazer, por ser uma atividade essencial para a existência, não apelando à violência e ao consumo de substâncias e revelando as preferências musicais aspetos da personalidade. Encontraram-se diferenças estatisticamente significativas entre as dimensões da preferência musical e os traços de personalidade, sendo a música energética a que mais se destaca na extroversão e a rebelde no neuroticismo. Não se obtiveram resultados estatisticamente significativos entre os tipos de música e as emoções. Conclusão: Os resultados devem ser vistos a título de ensaio e como introdutórios, seguindo no entanto os referidos na literatura quer ao nível das preferências por idade, sexo e habilitações literárias, quer ao nível do contexto onde é ouvida, quer ainda entre as dimensões de preferência musical e traços de personalidade. / Aims: Music, unusual for its ubiquity and age, is one of the human activities that occupies a significant place in different cultures and daily life. Generally pleasant to most people, produces many and huge positive effects in humans. This investigation aimed to study the relationship between some of the different music preferences and personality types of young and adults aged between 18 and 38 years, fluent in Portuguese. The research intended to describe the musical preferences based on age, gender, marital status and educational attainment; identify contexts, periods and the most common activities during music listening; recognize the music as one of the most important leisure activities for the group studied; know which are the most frequent reasons given by the subjects to listen to music; study the perception that people have about the influence of music on violence and substance use; check whether the subjects consider the musical preferences as a major factor that reveals information about personality; assess the impact and relationship of musical preferences with the personality and see which pairs of most common emotions are felt during music listening, and its respective intensity. Methods: The sample consisted of 320 individuals aged between 18 and 38 years being the most common age group of between 24 to 29 years, mostly female, single, Portuguese, holders or to attend a higher education in the areas of social / services or exact science. Participants voluntarily agreed to answer a battery of tests (QCS, EPI, QMQEC and STOMP-PT). To characterize the sample, they were determined absolute and relative frequencies and mean values and standard deviations. The normality of the average scores of the instruments has been validated with the Kolmogorov-Smirnov test with Lilliefors correction. Internal consistency was studied using Cronbach's alpha and Kuder Richardson formula. Differences between groups were assessed using an ANOVA, intensity and magnitude of the relationship between variables was determined by Eta squared coefficient and the Pearson correlation coefficient evaluated the association between the study variables. Results: It was observed that the energetic music is the most usual among the younger age groups, and the rebel pierces all generations, revealing the older ones a strong preference for reflective music. The musical choices do not seem to be influenced by sex and marital status. The less educated individuals seems to prefer the energetic type songs, excluding conventional, holders of higher qualifications prefer reflective and rebellious styles. It is at home, in the room, on the weekends and when they are alone that participants listen more music, making this the most common leisure activity, the essential for existence, not calling for violence and substance use and revealing aspects of personality. We found significant differences between the dimensions of music preferences and personality traits, with the energetic music standing out in extraversion and neuroticism on rebel. We did not get significant results among the types of music and emotions. Conclusions: The results should be viewed under test and has introductory , however following the reported in the literature both in terms of preferences by age, sex and education level , both in terms of the context in which it is heard, still follows music preference dimensions and personality traits .

Mikroyrityksen ja tilitoimiston välisten prosessien kehittäminen sähköistämisen avulla

Tämä tutkielma käsittelee mikroyrityksen ja tilitoimiston välistä yhteistyötä sekä sen edistämistä sähköistämisen keinoin. Aihetta käsitellään ulkoistamisen näkökulmasta, jolloin taloushallinnon prosessit käsittävät tilitoimiston ja yrityksen välisen tiedonvaihdon ja yhteistyön. Tutkielmassa käsitellään taloushallinnon roolia ja prosesseja sekä taloushallinnon ulkoistamisen teoreettisia lähtökohtia. Tämän jälkeen syvennytään taloushallinnon sähköistämiseen sekä sen etuihin ja haittoihin. Aiheita pyritään käsittelemään sekä yleisellä tasolla että mikroyritysten näkökulmasta. Tutkielman tavoitteena on teorian ja empiirisen tutkimuksen avulla selvittää, millaisia sähköisiä keinoja valitun kohdeyrityksen ja tilitoimiston yhteistyön kehittämiseen on tarjolla ja kuinka nämä keinot edistäisivät osapuolten välistä yhteistyötä. Työssä käytetty tutkimusmenetelmä on kvalitatiivinen ja tutkittavaa ilmiötä on tarkasteltu tapaustutkimuksen keinoin. Tutkimusaineisto kerättiin kohdeyrityksen omistajayrittäjältä keskusteluin sekä kohdeyrityksen käyttämälle tilitoimistolle sähköpostitse lähetetyllä kyselyllä. Tutkielmassa päädyttiin siihen, että sähköisistä menetelmistä on saatu apua esimerkiksi kuittikirjanpidossa. Käytössä olevien sähköisten palveluiden määrää sen sijaan voitaisiin vähentää ainakin poistamalla yksi laskujenhallintaohjelma käytöstä. Tämä edistäisi tositteiden kulkua yritykseltä kirjanpitäjälle ja samalla päästäisiin eroon myös yhdestä käyttöominaisuuksiltaan kehnosta laskujenhallintajärjestelmästä. Toisaalta todettiin, että ydinongelmat eivät loppujen lopuksi liity heikkoon teknologiaan vaan ihmisten välisiin suhteisiin eivätkä nämä ongelmat ole ratkaistavissa teknologian keinoin.

Mixing performance evaluation of additive manufactured milli-scale reactors

The mixing performance of three passive milli-scale reactors with different geometries was investigated at different Reynolds numbers. The effects of design and operating characteristics such as mixing channel shape and volume flow rate were investigated. The main objective of this work was to demonstrate a process design method that uses on Computational Fluid Dynamics (CFD) for modeling and Additive Manufacturing (AM) technology for manufacture. The reactors were designed and simulated using SolidWorks and Fluent 15.0 software, respectively. Manufacturing of the devices was performed with an EOS M-series AM system. Step response experiments with distilled Millipore water and sodium hydroxide solution provided time-dependent concentration profiles. Villermaux-Dushman reaction experiments were also conducted for additional verification of CFD results and for mixing efficiency evaluation of the different geometries. Time-dependent concentration data and reaction evaluation showed that the performance of the AM-manufactured reactors matched the CFD results reasonably well. The proposed design method allows the implementation of new and innovative solutions, especially in the process design phase, for industrial scale reactor technologies. In addition, rapid implementation is another advantage due to the virtual flow design and due to the fast manufacturing which uses the same geometric file formats.

Conversor de energia das ondas em energia elétrica com dispositivo de coluna de água oscilante: simulação numérica e estudo geométrico

Os oceanos representam um dos maiores recursos naturais, possuindo expressivo potencial energético, podendo suprir parte da demanda energética mundial. Nas últimas décadas, alguns dispositivos destinados à conversão da energia das ondas dos oceanos em energia elétrica têm sido estudados. No presente trabalho, o princípio de funcionamento do conversor do tipo Coluna de Água Oscilante, do inglês Oscillating Water Colum, (OWC) foi analisado numericamente. As ondas incidentes na câmara hidro-pneumática da OWC, causam um movimento alternado da coluna de água no interior da câmara, o qual produz um fluxo alternado de ar que passa pela chaminé. O ar passa e aciona uma turbina a qual transmite energia para um gerador elétrico. O objetivo do presente estudo foi investigar a influência de diferentes formas geométricas da câmara sobre o fluxo resultante de ar que passa pela turbina, que influencia no desempenho do dispositivo. Para isso, geometrias diferentes para o conversor foram analisadas empregando modelos computacionais 2D e 3D. Um modelo computacional desenvolvido nos softwares GAMBIT e FLUENT foi utilizado, em que o conversor OWC foi acoplado a um tanque de ondas. O método Volume of Fluid (VOF) e a teoria de 2ª ordem Stokes foram utilizados para gerar ondas regulares, permitindo uma interação mais realista entre o conversor, água, ar e OWC. O Método dos Volumes Finitos (MVF) foi utilizado para a discretização das equações governantes. Neste trabalho o Contructal Design (baseado na Teoria Constructal) foi aplicado pela primeira vez em estudos numéricos tridimensionais de OWC para fim de encontrar uma geometria que mais favorece o desempenho do dispositivo. A função objetivo foi a maximização da vazão mássica de ar que passa através da chaminé do dispositivo OWC, analisado através do método mínimos quadrados, do inglês Root Mean Square (RMS). Os resultados indicaram que a forma geométrica da câmara influencia na transformação da energia das ondas em energia elétrica. As geometrias das câmaras analisadas que apresentaram maior área da face de incidência das ondas (sendo altura constante), apresentaram também maior desempenho do conversor OWC. A melhor geometria, entre os casos desse estudo, ofereceu um ganho no desempenho do dispositivo em torno de 30% maior.

Sokna re-examined

International audience

Studies of turbulent flows in continuous casting of steel with and without magnetic field

This thesis develops and tests various transient and steady-state computational models such as direct numerical simulation (DNS), large eddy simulation (LES), filtered unsteady Reynolds-averaged Navier-Stokes (URANS) and steady Reynolds-averaged Navier-Stokes (RANS) with and without magnetic field to investigate turbulent flows in canonical as well as in the nozzle and mold geometries of the continuous casting process. The direct numerical simulations are first performed in channel, square and 2:1 aspect rectangular ducts to investigate the effect of magnetic field on turbulent flows. The rectangular duct is a more practical geometry for continuous casting nozzle and mold and has the option of applying magnetic field either perpendicular to broader side or shorter side. This work forms the part of a graphic processing unit (GPU) based CFD code (CU-FLOW) development for magnetohydrodynamic (MHD) turbulent flows. The DNS results revealed interesting effects of the magnetic field and its orientation on primary, secondary flows (instantaneous and mean), Reynolds stresses, turbulent kinetic energy (TKE) budgets, momentum budgets and frictional losses, besides providing DNS database for two-wall bounded square and rectangular duct MHD turbulent flows. Further, the low- and high-Reynolds number RANS models (k-ε and Reynolds stress models) are developed and tested with DNS databases for channel and square duct flows with and without magnetic field. The MHD sink terms in k- and ε-equations are implemented as proposed by Kenjereš and Hanjalić using a user defined function (UDF) in FLUENT. This work revealed varying accuracies of different RANS models at different levels. This work is useful for industry to understand the accuracies of these models, including continuous casting. After realizing the accuracy and computational cost of RANS models, the steady-state k-ε model is then combined with the particle image velocimetry (PIV) and impeller probe velocity measurements in a 1/3rd scale water model to study the flow quality coming out of the well- and mountain-bottom nozzles and the effect of stopper-rod misalignment on fluid flow. The mountain-bottom nozzle was found more prone to the longtime asymmetries and higher surface velocities. The left misalignment of stopper gave higher surface velocity on the right leading to significantly large number of vortices forming behind the nozzle on the left. Later, the transient and steady-state models such as LES, filtered URANS and steady RANS models are combined with ultrasonic Doppler velocimetry (UDV) measurements in a GaInSn model of typical continuous casting process. LES-CU-LOW is the fastest and the most accurate model owing to much finer mesh and a smaller timestep. This work provided a good understanding on the performance of these models. The behavior of instantaneous flows, Reynolds stresses and proper orthogonal decomposition (POD) analysis quantified the nozzle bottom swirl and its importance on the turbulent flow in the mold. Afterwards, the aforementioned work in GaInSn model is extended with electromagnetic braking (EMBr) to help optimize a ruler-type brake and its location for the continuous casting process. The magnetic field suppressed turbulence and promoted vortical structures with their axis aligned with the magnetic field suggesting tendency towards 2-d turbulence. The stronger magnetic field at the nozzle well and around the jet region created large scale and lower frequency flow behavior by suppressing nozzle bottom swirl and its front-back alternation. Based on this work, it is advised to avoid stronger magnetic field around jet and nozzle bottom to get more stable and less defect prone flow.