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Ingeniero Civil / En la región altiplánica de la Cordillera de los Andes existen lagunas someras de algunos centímetros de profundidad denominadas salares; grandes extensiones de agua salada acotadas por una cáscara de sal en sus extremos como resultado de las altas tasas de evaporación. Diversas investigaciones han demostrado que la temperatura del agua puede variar en 20-30 °C en el día y que los sedimentos cumplen la función de reservorios, reteniendo calor durante el día y liberándolo en la noche, reduciendo de esta manera la oscilación termal diaria. La situación es determinada por procesos ocurrentes a ambos lados de la interfaz agua-sedimento (IAS), perspectiva que debe usarse al proponer modelos conceptuales. Sin embargo, raramente se considera en estudios y, de hacerlo, el calentamiento de los sedimentos por absorción de radiación solar no se analiza. La presente memoria toma como base Flow Solve , un modelo numérico del académico Kraig Winters (U. de California, San Diego) que utiliza el método espectral. El modelo se aplica a un sistema agua sedimento en que la capa superior de los sedimentos es calentada de manera periódica. Además, se estudia el orden de discretización espacial y temporal, así como la relación entre los números de Nusselt y Rayleigh. A partir de los resultados se concluye que existe una relación empírica exponencial entre el calor absorbido en la capa superior de los sedimentos (𝐻�����𝑠�����), la altura del cuerpo de agua (ℎ𝑤�����) y la frecuencia asociada a los periodos de evaluación (𝜔�����) y el número adimensional Π1 (que cuantifica el rol de los sedimentos en el balance de calor). La amplitud térmica es directamente proporcional al calor absorbido en los sedimentos elevado a un coeficiente de orden 0,6 , es decir, Δ𝑇�����𝑤����� crece sin cota a medida que aumenta el calor absorbido. En el caso de la curva Δ𝑇�����𝑤����� como función del periodo, la pendiente disminuye a medida que aumenta la duración de los ciclos, hasta estabilizarse. No se puede estimar la amplitud térmica para periodos superiores a los simulados. Para el caso de la altura de agua se aprecia una curva con pendiente decreciente. A medida que aumenta la altura del cuerpo de agua, la amplitud térmica tiende a 0°C, mientras que al disminuir ℎ𝑤�����, Δ𝑇�����𝑤����� crece sin cota. A partir de los 50 cm, Δ𝑇�����𝑤����� toma valores inferiores a 0,1 °C. La escala de longitud de Kolmogorov entrega resultados que permiten estimar satisfactoriamente la distancia vertical a definir entre puntos de la grilla. Sin embargo, en el caso del paso temporal, el usar un Δt del orden de la escala de tiempo de Kolmogorov puede asegurar que se consideren todas las escalas físicas del proceso, pero no implica que se cumplan las condiciones matemáticas necesarias para que el programa funcione correctamente. De este modo, el requisito dominante en el caso del tiempo viene dado por una expresión empírica. La relación entre los números de Nusselt y Rayleigh revela que el fenómeno de intercambio de calor en la IAS queda descrito por convección natural en una placa horizontal caliente a temperatura uniforme en régimen turbulento. / Este trabajo ha sido parcialmente financiado por Fondecyt 1140821

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Este trabalho trata do comportamento de jovens estudantes de uma escola da rede estadual paulista no que concerne as estratégias e heurísticas observáveis que praticam diante de determinados problemas lógico-matemáticos. Identifica algumas das heurísticas e estratégias clássicas que os educandos praticam e não praticam. A investigação se dá por meio de apresentação de problemas contextualizados que prescindem de conhecimentos matemáticos elaborados, a estudantes do último ano do ensino médio e análise dos processos de resolução deflagrados pelos estudantes na tentativa de resolver os problemas. Também é apresentado subsídio teórico e problemas adequados à reprodução parcial dessa investigação que podem interessar ao professor de matemática da educação básica ou ao pesquisador em resolução de problemas. Por fim, são problematizadas as informações observadas sobre o comportamento intelectual dos educandos no sentido de estabelecer hipóteses sobre as conquistas ou não dos educandos quanto à competência em resolução de problemas. / Este trabalho trata do comportamento de jovens estudantes de uma escola da rede estadual paulista no que concerne as estratégias e heurísticas observáveis que praticam diante de determinados problemas lógico-matemáticos. Identifica algumas das heurísticas e estratégias clássicas que os educandos praticam e não praticam. A investigação se dá por meio de apresentação de problemas contextualizados que prescindem de conhecimentos matemáticos elaborados, a estudantes do último ano do ensino médio e análise dos processos de resolução deflagrados pelos estudantes na tentativa de resolver os problemas. Também é apresentado subsídio teórico e problemas adequados à reprodução parcial dessa investigação que podem interessar ao professor de matemática da educação básica ou ao pesquisador em resolução de problemas. Por fim, são problematizadas as informações observadas sobre o comportamento intelectual dos educandos no sentido de estabelecer hipóteses sobre as conquistas ou não dos educandos quanto à competência em resolução de problemas.

The development of a Magneto-hydrodynamics (MHD) numerical tool to study high density thermal plasmas in plasma acceleration devices is presented. The MHD governing equations represent eight conservation equations for the evolution of density, momentum, energy and induced magnetic fields in a plasma. A matrix-free implicit method is developed to solve these conservation equations within the framework of an unstructured grid finite volume formulation. The analytic form of the convective flux Jacobian is derived for general unstructured grids. A Lower Upper Symmetric Gauss Seidel (LU-SGS) technique is developed as part of the implicit scheme. A coloring based algorithm for parallelization of this technique is also presented and its computational efficiency is compared with a global matrix solve technique that uses the GMRES (Generalized Minimum Residual) algorithm available in the PETSc (Portable Extensible Toolkit for Scientific computation) libraries. The verification cases used for this study are the MHD shock tube problem in one, two and three dimensions, the oblique shock and the Hartmann flow problem. It is seen that the matrix free method is comparatively faster and shows excellent scaling on multiple cores compared to the global matrix solve technique. The numerical model was thus verified against the above mentioned standard test cases and two application problems were studied. These include the simulation of plasma deflagration phenomenon in a coaxial plasma accelerator and a novel high speed flow control device called the Rail Plasma Actuator (RailPAc). Experimental studies on coaxial plasma accelerators have revealed two different modes of operation based on the delay between gas loading and discharge ignition. Longer delays lead to the detonation or the snowplow mode while shorter delays lead to the relatively efficient stationary or deflagration mode. One of the theories that explain the two different modes is based on plasma resistivity. A numerical modeling study is presented here in the context of a coaxial plasma accelerator and the effect of plasma resistivity is dealt with in detail. The simulated results pertaining to axial distribution of radial currents are compared with experimental measurements which show good agreement with each other. The simulations show that magnetic field diffusion is dominant at lower conductivities which tend to form a stationary region of high current density close to the inlet end of the device. Higher conductivities led to the formation of propagating current sheet like features due to greater convection of magnetic field. This study also validates the theory behind the two modes of operation based on plasma resistivity. The RailPAc (Rail Plasma Actuator) is a novel flow control device that uses the magnetic Lorentz forces for fluid flow actuation at atmospheric pressures. Experimental studies reveal actuation ~ 10-100 m/s can be achieved with this device which is much larger than conventional electro-hydrodynamic (EHD) force based plasma actuators. A magneto-hydrodynamics simulation study of this device is presented. The model is further developed to incorporate applied electric and magnetic fields seen in this device. The snowplow model which is typically used for studying pulsed plasma thrusters is used to predict the arc velocities which agrees well with experimental measurements. Two dimensional simulations were performed to study the effect of Lorentz forcing and heating effects on fluid flow actuation. Actuation on the order of 100 m/s is attained at the head of the current sheet due to the effect of Lorentz forcing alone. The inclusion of heating effects led to isotropic blast wave like actuation which is detrimental to the performance of RailPAc. This study also revealed the deficiencies of a single fluid model and a more accurate multi-fluid approach is proposed for future work. / text

Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-08-29T18:05:26Z No. of bitstreams: 1 ERICK JOHN FIDELIS COSTA – DISSERTAÇÃO (PPGCC) 2017.pdf: 3969742 bytes, checksum: 640b82ab0868dc91523e02df93ab3a6e (MD5) / Made available in DSpace on 2018-08-29T18:05:26Z (GMT). No. of bitstreams: 1 ERICK JOHN FIDELIS COSTA – DISSERTAÇÃO (PPGCC) 2017.pdf: 3969742 bytes, checksum: 640b82ab0868dc91523e02df93ab3a6e (MD5) Previous issue date: 2017-03-05 / O desenvolvimento da capacidade de resolução de problemas deve ser estimulado desde as séries iniciais. Diante dessa necessidade, o ensino de Computação passou a ser considerado com o objetivo de estimular e aprimorar competências essências para resolução de problemas. Desenvolvendo nos estudantes uma maneira de interagir com a Ciência da Computação por meio de um pensamento interdisciplinar, o Pensamento Computacional. O Pensamento Computacional se baseia nas competências adquiridas através da Ciência da Computação, não apenas como ferramenta, mas como uma forma de pensar de maneira organizada e capaz de explorar as potencialidades provenientes das tecnologias da informação e comunicação. As principais abordagens para estimular o Pensamento Computacional, são: através de disciplinas específicas da Ciência da Computação (programação, algoritmos, etc) e, através da aplicação conjunta do Pensamento Computacional em paralelo ao ensino de disciplinas do ensino básico (matemática, ciência e leitura) sem a necessidade de disciplinas específicas da Ciência da Computação. Levando em consideração a segunda abordagem, é um problema realizar aplicações práticas pela falta de subsídio na literatura (poucos estudos práticos), inviabilizando sua aplicação. Pensando nisso, uma abordagem foi concebida para estimular as competências do Pensamento Computacional em conjunto à disciplina de matemática do ensino básico. Tal abordagem teve como objetivo estimular a capacidade de resolução de problemas nos alunos, por meio da própria disciplina de matemática, estimulando as competências essenciais através de atividades práticas utilizando questões em maior conformidade com o Pensamento Computacional. A abordagem proposta evidenciou fatores que possivelmente contribuíram para melhorar a capacidade de resolução de problemas nos alunos envolvidos. Isso foi identificado através da aplicação de um quasi-experimento onde foi possível identificar o impacto das atividades práticas propostas, no que diz respeito ao estímulo à capacidade de resolução de problemas nos alunos. / The development of the capacity to solve problems should be stimulated from the initial grades. Facing this necessity, the teaching of Computing began to be considered with the objective of stimulating and improving essential competences to solve problems. Aiming that students can develop a way of interacting with the Computer Science through an interdisciplinary thinking, the Computational Thinking. The Computational Thinking is based on the competences acquired through the Computer Science, not only as a tool, but as a way of thinking in an organized way and being able to explore the potentiality from information and communication technologies. The main approaches to stimulate Computational Thinking are: through specific Computer Science disciplines(programming, algorithms, etc.) and through the joint application of Computational Thinking in parallel with the teaching of subjects in the basic education(mathematics, science and reading) without the need of specific disciplines from the Computer Science. Considering the second approach, it is a problem to perform practical applications with the lack of subsidy in the literature (few practical studies), preventing its implementation. In this sense, an approach was designed to stimulate the competences of Computational Thinking together with the discipline of mathematics in the basic education. Such approach had the objective to stimulate students’ capacity to solve problems through the discipline of mathematics, stimulating the essential competences through practical activities using exercises in greater conformity with the Computational Thinking. The proposed approach evidenced factors that may have contributed to improve the capacity to solve problems in the students involved. This was identified through the application of a quasi-experiment where it was possible to identify the impact of the practical activities proposed, regarding the stimulation of the students’ capacity to solve problems.

The purpose of this qualitative case study was to explore the patterns of Saudi Arabian elementary female science teachers’ understanding and knowledge of critical thinking, as well as their perceptions towards critical thinking guidelines in the course of their lesson plans. The research questions that guided this study were: 1. How female elementary science teachers perceive the role of critical thinking in science education? 2. How do female science teachers perceive students’ abilities to use critical thinking skills in the classroom? 3. How do female science teachers incorporate and implement critical thinking as an essential objective in lesson planning? This research contains background information about student centered learning and developing critical thinking skills in the classroom. It is becoming increasingly apparent that critical thinking is an important aspect of intellectual development among students. Critical thinking is a crucial skill for students, especially in the STEM fields where problem solving is a large part of the discipline. The sample of this study was three Saudi Arabian elementary female science teachers. I conducted semi-structured interviews and used documents to collect data as well as answer the research questions. The findings revealed that all participants believed of the importance of using critical thinking skills in the classroom. However, the participants had a lack understanding and perception of incorporating students’ critical thinking in their lesson plans.

Paauglių mokymas/is spręsti jiems aktualias problemas, taikant Forumo teatro metodą, Lietuvoje yra netyrinėta mokslinėje literatūroje tema. Tyrimo tikslas - atskleisti, kokios vidinės (psichologinės) ir išorinės (socialinės) problemos jaudina 17-19 metų paauglius, ir kaip, taikant Forumo teatro metodą, susiformuoja gebėjimai jas iškelti ir konstruktyviai išspręsti. Darbe buvo siekiama išanalizuoti mokslinę, metodinę literatūrą, susijusią su Forumo teatro metodo taikymu; nustatyti Forumo teatro veikimo principus; apibūdinti paauglių požiūrį į Forumo teatro taikymo atitikimą jų poreikiams; išaiškinti, kaip, taikant Forumo teatro metodą, vyksta 17-19 metų paauglių gebėjimų spręsti problemas formavimosi procesas; nustatyti paauglių gebėjimus, įgytus mokymo/si spręsti jiems aktualias psichologines ir socialines problemas procese, taikant Forumo teatro metodą. Siekiant išsamiai ir detaliai išnagrinėti paauglių mokymo/si spręsti jiems aktualias problemas Forumo teatre procesą nuo 2007 m. lapkričio mėnesio iki 2008 m. gruodžio mėnesio 17-19 metų paaugliams buvo organizuoti Forumo teatro užsiėmimai ir atliekamas atvejų tyrimas. Tyrimo metu duomenys buvo renkami stebint atskirų individų ir individų grupių užduočių atlikimą, apklausiant ir fiksuojant (užrašant ir filmuojant) su tyrimo objektu susijusią informaciją. Tyrime dalyvavo 79 paaugliai. Forumo teatro taikymo procese paaugliai įgijo gebėjimų iškelti ir įvardinti jiems aktualias vidines (psichologines) ir išorines... [toliau žr. visą tekstą] / The topic of teenagers teaching and their learning how to solve their urgent problems through the method of Forum Theatre has not been investigated in Lithuanian scientific literature. The purpose of the investigation is to reveal what internal (psychological) and external (social) problems are important to 17-19-year-old teenagers and how the skills of revealing and solving these problems are formed using the method of Forum Theatre. This paper aims to analyze scientific, methodological literature connected with the Forum Theatre method application; establish Forum Theatre effect principles; describe the views of teenagers on how Forum Theatre application meets their needs; find out how, using the method of Forum Theatre, the process of building up teenagers skills of solving problems happens; reveal the abilities of the 17-19-year-olds which they developed through the process of learning-teaching how to cope with their psychological and social problems, using the method of Forum Theatre. Seeking to carry out a detailed investigation of the process of teenagers’ learning-teaching how to solve their urgent problems through Forum Theatre, from November 2007 till December 2008, Forum Theatre lessons were given to 17-19-year-old teenagers, after which the analysis of the cases was performed. During the investigation the data was collected monitoring how separate individuals and groups of individuals perform the tasks, interviewing and fixing (writing down and filming) the... [to full text]

This thesis describes the design of a new circuit for the production of superheated steam instead of the original heat exchanger, which showed frequent failure. In the introduction is disassambling the problems of the existing heat exchanger and the proposed method of solving the problem. Proposed is a new process circuit consisting of a heat exchanger to heat the steam, separator and heat exchanger for superheated stream. Gradually, the work both heat exchangers are designed thermal and strenght. In the thermal part is modeled all process circuit and calculated in the program ChemCad. The strength calculation is solved analytically according to EN 13 445, then all dimensions of heat exchangers are optimized. In the conclusion is verified by metod of finite element critical part of the exchanger. After successful completion of the design thermal and strength calculation was made relevant drawing documentation.