On the implementation of a Laboratory of Digital Television according to the ISDB-Tb standard

Este artículo resume el proceso de implementación del Laboratorio de Televisión Digital (DTV) de la Universidad de Cuenca, que surge como un entorno confiable de experimentación e investigación que hace uso de las características asociadas al estándar ISDB-Tb adoptado por Ecuador en el año 2010 para la transmisión de señales de televisión abierta. El objetivo de este artículo es documentar los aspectos que se han considerado para simular un escenario real en el que un Transport Stream (TS) formado por contenido audiovisual y aplicaciones interactivas, primero se genera, para luego transmitirse a través del canal de comunicaciones, y finalmente ser recibido en una televisión con receptor ISDB-Tb. Así, se facilita el desarrollo y la experimentación de nuevos servicios aprovechando el nuevo formato de DTV.

Development of Physics-based Models and Design Optimization of Power Electronic Conversion Systems

The main objective for physics based modeling of the power converter components is to design the whole converter with respect to physical and operational constraints. Therefore, all the elements and components of the energy conversion system are modeled numerically and combined together to achieve the whole system behavioral model. Previously proposed high frequency (HF) models of power converters are based on circuit models that are only related to the parasitic inner parameters of the power devices and the connections between the components. This dissertation aims to obtain appropriate physics-based models for power conversion systems, which not only can represent the steady state behavior of the components, but also can predict their high frequency characteristics. The developed physics-based model would represent the physical device with a high level of accuracy in predicting its operating condition. The proposed physics-based model enables us to accurately develop components such as; effective EMI filters, switching algorithms and circuit topologies [7]. One of the applications of the developed modeling technique is design of new sets of topologies for high-frequency, high efficiency converters for variable speed drives. The main advantage of the modeling method, presented in this dissertation, is the practical design of an inverter for high power applications with the ability to overcome the blocking voltage limitations of available power semiconductor devices. Another advantage is selection of the best matching topology with inherent reduction of switching losses which can be utilized to improve the overall efficiency. The physics-based modeling approach, in this dissertation, makes it possible to design any power electronic conversion system to meet electromagnetic standards and design constraints. This includes physical characteristics such as; decreasing the size and weight of the package, optimized interactions with the neighboring components and higher power density. In addition, the electromagnetic behaviors and signatures can be evaluated including the study of conducted and radiated EMI interactions in addition to the design of attenuation measures and enclosures.

A crowd of pedestrian dynamics – the perspective of physics.

Walking is the most basic form of transportation. A good understanding of pedestrian’s dynamics is essential in meeting the mobility and accessibility needs of people by providing a safe and quick walking flow. Advances in the dynamics of pedestrians in crowds are of great theoretical and practical interest, as they lead to new insights regarding the planning of pedestrian facilities, crowd management, or evacuation analysis. As a physicist, I would like to put forward some additional theoretical and practical contributions that could be interesting to explore, regarding the perspective of physics on about human crowd dynamics (panic as a specific form of behavior excluded).

The “FRA wheel” as a teaching tool to elaborate on the identity aspects of physics and mathematics as disciplines in interdisciplinary contexts

This thesis project is framed in the research field of Physics Education and aims to contribute to the reflection on the importance of disciplinary identities in addressing interdisciplinarity through the lens of the Nature of Science (NOS). In particular, the study focuses on the module on the parabola and parabolic motion, which was designed within the EU project IDENTITIES. The project aims to design modules to innovate pre-service teacher education according to contemporary challenges, focusing on interdisciplinarity in curricular and STEM topics (especially between physics, mathematics and computer science). The modules are designed according to a model of disciplines and interdisciplinarity that the project IDENTITIES has been elaborating on two main theoretical frameworks: the Family Resemblance Approach (FRA), reconceptualized for the Nature of science (Erduran & Dagher, 2014), and the boundary crossing and boundary objects framework by Akkerman and Bakker (2011). The main aim of the thesis is to explore the impact of this interdisciplinary model in the specific case of the implementation of the parabola and parabolic motion module in a context of preservice teacher education. To reach this purpose, we have analyzed some data collected during the implementation in order to investigate, in particular, the role of the FRA as a learning tool to: a) elaborate on the concept of “discipline”, within the broader problem to define interdisciplinarity; b) compare the epistemic core of physics and mathematics; c) develop epistemic skills and interdisciplinary competences in student-teachers. The analysis of the data led us to recognize three different roles played by the FRA: FRA as epistemological activator, FRA as scaffolding for reasoning and navigating (inhabiting) the complexity, and FRA as lens to investigate the relationship between physics and mathematics in the historical case.

Experimentació a distància de la física per a enginyers (EDFE)

El laboratori de física és el lloc que permet apropar la Física i la seva realitat quotidiana, tant la tecnològica com la científica, a l'estudiantat mitjançant experiències i demostracions motivadores. En general, les pràctiques de laboratori se solen realitzar per parelles, encara que no necessàriament, propiciant un treball en equip. Ara bé, pensant en aquelles estudiantes i aquells estudiants que no poden seguir el calendari de sessions presencials establert, per raons justificables, s’ha generat un material docent innovador consistent en la filmació de vídeos d’algunes de les pràctiques que actualment s'estan duent a terme en el laboratori de Física de l'EPSEM. Les filmacions van acompanyades per uns tutorials que permeten introduir la pràctica i il·lustrar tots els conceptes teòrics que hi intervenen i algunes simulacions. A més, també hi ha disponible uns tests d'autoavaluació i d'avaluació que acreditin l'aprenentatge de l'estudiant. L’objectiu és procurar, a partir d’una experimentació virtual, minimitzar la manca d’adquisició d’algunes habilitats pròpies de l’experimentació real al laboratori. Els productes creats han estat inclosos en el web del Departament de Física Aplicada de la UPC a l'EPSEM, on es proporciona tot un conjunt d’eines i informacions pensades per facilitar una millor forma de treballar en un laboratori. En aquest web es poden trobar, les normes generals per a la realització de les pràctiques i per a l’elaboració dels informes preceptius, el guió i l’esquema del muntatge de cada experimentació, així com enllaços a webs relacionats amb la física, que poden resultar molt útils per a l’alumnat. El pas endavant que suposa el material desenvolupat, ampliable en un futur, és sens dubte una alternativa educativa complementaria per garantir una formació més integral de les nostres estudiantes i dels nostres estudiants, en correspondència amb l’esperit de fomentar l'autoaprenentatge que traspua el procés d'integració a l'EEES. Veure: http://www.epsem.upc.edu/~practiquesfisica/

Strong magnetic field pulse generator

High magnetic fields and extremely low temperatures are essential in the study of new semiconductor materials for example in the field of spintronics. Typical phenomenons that arise in such conditions are: Hall Effect, Anomalous Hall effect and Shubnikov de-Haas effect. In this thesis a device capable for such conditions was described. A strong magnetic field pulse generator situated in the laboratory of physics and the Lappeenranta University of Technology was studied. The device is introduced in three parts. First one is the pulsed field magnetic generator, which is responsible for generating the high magnetic field. Next one is the measurement systems, which are responsible for monitoring the sample and the system itself. The last part describes the cryostat system, which allows the extremely cold temperatures in the system.

Reflexões e contribuições para o ensino de gravitação clássica no nível médio

The subject of Classic Gravitation is part of the actual curriculum for High School in Brazil, and it is taught in the first year of that education level. This master thesis presents a research regarding the subject Classic Gravitation in High School. This research was based in two complementary guidelines of research and action. The first guideline was the analysis of 21 didactic books of physics which are the more frequently used in High School, in the city of Natal/RN. The second guideline, worked after being verified the most common deficiencies presents in the didactic books, was the elaboration, followed by a practical application, of a course suggesting how to approach that subject in the classroom. The Parâmetros Curriculares Nacionais para o Ensino Médio (National Curricular Parameters for High School PCNEM) defend that Classic Gravitation is very important in the student s formation and that its study helps the comprehension of many nature s phenomena. Because of this vision of that subject by the PCNEM, the 21 analyzed books were separated in two groups: the first one, containing 10 books, was edited before the spreading of PCNEM, and the second, with 11 books, after that spreading. Whatever the group to which the didactic books belonged, the great majority of them let that subject in a second plan; two of them even suggesting, in the teacher s orientations, that the subject Gravitation can be suppressed in case of insufficient time . These analyses points that the PCNEM had produced no changes in the conception of the authors that wrote books regarding that subject. To analyze the didactic books, we elaborated a script which was used as an analysis tool, in which we put in evidence the relative importance of the historic and philosophic contextualization of the subject, the quotidian experience of the students and the interdisciplinary approach, among other aspects. It became evident that the didactic books give very little emphasis to historic aspects of the knowledge construction, to the relations with the day-by-day questions and to the interdisciplinary character of the subject Gravitation. It calls attention the non concordance among the authors opinions regarding the necessary previous knowledge or prerequisites the students should fulfill in order to begin to study Gravitation. The course we elaborated was given to a group of teachers as well as to students. In those courses we treated theoretical and practical aspects and emphasized historical questions and the ones which are related to people s daily life. The course for teachers was realized as an extra-mural activity of the UFRN and was given by the author of this thesis at the Escola Estadual Francisco Ivo Cavalcanti (a state public school in Natal/RN). There were 23 teachers present, from several public schools and several fields of knowledge. The thesis supervisor and the master degree s colleagues of the author acted as collaborators , reporting the participants opinions and speeches. The course to the students, on the other hand, had the participation of 300 regular students who belonged to 6 different 1st year classes of the High School Escola Marista de Natal (RN), in which the author acts as a physics teacher. The student s course was realized as part of the regular curriculum activities, in which three classes stood under the responsibility of the author and other three classes in charge of another Marista s teacher, who participated as a collaborator . The teacher s course as well as the students one were given in two stages, with five hours each. The first stage was divided in two moments, the first one focused on the survey of the spontaneous conceptions about gravitation, in which we worked basically with experiments of free throwing and pendulum, and the second one focused in theoretical presentations and quarrels about universe s models. In the second stage of the course we improved the study of Kepler s laws and the Newton s Universal Gravitation law, and we used as motivating tools some practices involving the construction of the solar system in scale. As instruments for evaluating both courses we used questionnaires and reported the speeches with participants opinions, beyond usual written evaluations in the course for the students. The teachers who participated in the course showed very good wills in realizing interdisciplinary practices; nevertheless, according their own speeches, they frequently came across the difficulty of how to do . From the experience we had in both courses, we conclude that the approach we propose hear to the teaching of the subject Classic Gravitation , supported on the tripod theory, practice and historical and philosophical aspects, is viable and effective. One hopes that this research may contribute in the formation of a opinion, among the teachers, concerning how to approach the subject of Classic Gravitation, and may offer suggestions in order those who want to apply that approach may develop classroom practices aiming to improve the teaching of that subject, which has a singular importance in the formation of High School students

Dimensión vertical de la región anterior de la mandíbula

We made some measurements from the region of the symphysis menti in 308 dried mandibles; 247 belong to the collection of the cranial museum of the discipline of Anatomy of the UNIFESP- Escola Paulista de Medicina- EPM and 61 belong to the didactic laboratory of the discipline of Anatomy from the Faculdade de Odontologia de Araraquara- UNESP, Brasil. On the dentate mandibles, the highest value founded was of 43,46 mm and the lowest of 22,67 mm. On the edentate mandibles, the highest value founded was of 37,24 mm and the lowest of 6,22mm. We hope that with the following discoveries we could contribute to a better knowledge of the symphysis menti region, not only to the professionals in Surgery and Implantology areas, but the industrials of related areas, to the confection of instruments used in these practices. © 2007 Sociedad Chilena de Anatom•br>.

Análise econômico-energética de utilização de resíduo industrial florestal para geração de energia térmica: um estudo de caso

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

A realidade das entidades científicas e a formação de professores de física: uma análise sociocultural

O objetivo da presente tese é realizar uma abordagem acerca da realidade das entidades científicas no contexto da formação de professores de física. A literatura em ensino de ciências destaca a importância do entendimento de aspectos da natureza da ciência por professores. Dentre esses aspectos, exploramos a questão da realidade das entidades inobserváveis descritas pelas teorias científicas, tratando sobretudo de critérios utilizados para a caracterização dessa realidade por licenciandos, bem como possíveis influências na constituição desses critérios. Consideramos que um professor de física, durante sua atuação profissional, precisará lidar com a questão da realidade de entidades não acessíveis aos sentidos, tendo talvez de explicar em que se baseia uma proposição sobre sua existência. No desenvolvimento do presente trabalho, trouxemos alguns elementos de uma discussão que se dá no âmbito filosófico a respeito do realismo científico e também abordamos formulações teóricas que tratam da questão da realidade em perspectivas que se referem ao campo cotidiano e ao senso comum. Como referencial mais geral, utilizamos uma abordagem sobre cultura, que aponta para a influência de diversas estruturas culturais nas formas de entendimento do mundo e permite conceber a ciência como uma dessas estruturas. Entre outras coisas, a aprendizagem da ciência envolveria a compreensão de suas formas específicas de atribuir realidade, em contraposição às formas de outras estruturas culturais. Foram desenvolvidos três estudos, com análises fundamentadas em metodologias qualitativas. No primeiro, investigamos critérios usados por licenciandos em física para definir a realidade de entidades da ciência e de entes relacionados a outros domínios; no segundo, analisamos formas pelas quais certas entidades científicas são caracterizadas e tomadas como reais em uma coleção de livros didáticos de física do ensino superior; e, por fim, o terceiro consistiu na construção e utilização de um heurístico, com o objetivo de proporcionar reflexões acerca de questões relacionadas ao conhecimento científico e a elementos de outras estruturas culturais e foram analisadas as entrevistas de quatro estudantes de licenciatura sobre o uso desse instrumento. Os resultados obtidos parecem mostrar que há influência de elementos vindos de fora da ciência nos critérios utilizados por estudantes para a definição da realidade das entidades. Além disso, mostram que esse tema não é comumente trazido à reflexão dos alunos, o que não contribui para a reelaboração dos critérios de realidade já trazidos por eles de outros campos que não o científico. O heurístico utilizado no terceiro estudo serviu para trazer à tona as bases do pensamento dos estudantes e lhes indicar certos elementos para reflexão; existiram diferenças nos tipos de reflexão suscitados pelo instrumento, o que consideramos ser uma espécie de \"contextualização cultural\" na maneira de compreender as questões trazidas por ele. O desenvolvimento dos três estudos nos permitiu compreender alguns aspectos relevantes sobre os modos de entendimento das entidades da ciência e pensar sobre suas formas de tratamento em um curso de física.

Measurement of the magnetic field of small magnets with a smartphone: a very economical laboratory practice for introductory physics courses

In this work, we propose an inexpensive laboratory practice for an introductory physics course laboratory for any grade of science and engineering study. This practice was very well received by our students, where a smartphone (iOS, Android, or Windows) is used together with mini magnets (similar to those used on refrigerator doors), a 20 cm long school rule, a paper, and a free application (app) that needs to be downloaded and installed that measures magnetic fields using the smartphone's magnetic field sensor or magnetometer. The apps we have used are: Magnetometer (iOS), Magnetometer Metal Detector, and Physics Toolbox Magnetometer (Android). Nothing else is needed. Cost of this practice: free. The main purpose of the practice is that students determine the dependence of the component x of the magnetic field produced by different magnets (including ring magnets and sphere magnets). We obtained that the dependency of the magnetic field with the distance is of the form x-3, in total agreement with the theoretical analysis. The secondary objective is to apply the technique of least squares fit to obtain this exponent and the magnetic moment of the magnets, with the corresponding absolute error.

Poster presentation as a report of a self-designed laboratory experiment : a case study

Julkaisumaa: 203 CZ CZE Tšekki

Physics 117 and 118; laboratory instructions and supplementary problems.

Mode of access: Internet.

Cognitive-didactic Model for Making Testing Items in Physics

Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, May, 2015