Lift and the leading-edge vortex

Flapping wings often feature a leading-edge vortex (LEV) that is thought to enhance the lift generated by the wing. Here the lift on a wing featuring a leading-edge vortex is considered by performing experiments on a translating flat-plate aerofoil that is accelerated from rest in a water towing tank at a fixed angle of attack of 15°. The unsteady flow is investigated with dye flow visualization, particle image velocimetry (PIV) and force measurements. Leading-and trailing-edge vortex circulation and position are calculated directly from the velocity vectors obtained using PIV. In order to determine the most appropriate value of bound circulation, a two-dimensional potential flow model is employed and flow fields are calculated for a range of values of bound circulation. In this way, the value of bound circulation is selected to give the best fit between the experimental velocity field and the potential flow field. Early in the trajectory, the value of bound circulation calculated using this potential flow method is in accordance with Kelvin's circulation theorem, but differs from the values predicted by Wagner's growth of bound circulation and the Kutta condition. Later the Kutta condition is established but the bound circulation remains small; most of the circulation is contained instead in the LEVs. The growth of wake circulation can be approximated by Wagner's circulation curve. Superimposing the non-circulatory lift, approximated from the potential flow model, and Wagner's lift curve gives a first-order approximation of the measured lift. Lift is generated by inertial effects and the slow buildup of circulation, which is contained in shed vortices rather than bound circulation. © 2013 Cambridge University Press.

Experimental studies of an accelerating, pitching, flat plate at low Reynolds number

The understanding of low Reynolds number aerodynamics is becoming increasingly prevalent with the recent surge in interest in advanced Micro-Air Vehicle (MAV) technology. Research in this area has been primarily stimulated by a military need for smaller, more versatile, autonomous, surveillance aircraft. The mechanism for providing the high lift coefficient required forMAV applications is thought to be largely influenced by the formation of a Leading Edge Vortex (LEV). This paper analyses experimentally, the influence of the LEV effect for a flat plate wing (AR = 4) under fast and slow pitch-up motions at Re =10,000 using a combination of dye flow visualisation and PIV measurements. It is found that a fast pitch over 1c shows a flow topology dominant LEV, while for a slow pitch case over 6c, the flow is largely separated. The development of the suction surface flow and the LEV was strongly correlated with the kinematics of the leading edge, suggesting that the effective local angle of incidence at the Leading Edge (LE) is of considerable significance in unsteady pitching motions. © 2013 by P.R.R.J Stevens.

Integration of silicon plasmonic schottky photodetector for on chip signal tapping at telecom wavelengths

We experimentally demonstrate the use of an on-chip integrated Schottky plasmonic detector for testing, monitoring and tapping signals in plasmonic and photonic devices. Theoretical model and measurement of external and integrated devices will be presented. © OSA 2013.

Consumo de tabaco, álcool e drogas ilícitas nos jovens

Dissertação de Mestrado apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Psicologia da Educação e Intervenção Comunitária.

A atitude dos consumidores face aos produtos alimentares de marca do distribuidor

Dissertação de Mestrado apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências da Comunicação, especialização em Marketing e Publicidade.

A imagem de um destino turístico cultural

Dissertação de Mestrado apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Empresariais.

Restauração directa de classes II em pré-molares com compósitos

Tese de Doutoramento apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Doutor em em Biotecnologia e Saúde, Epidemiologia e Saúde Pública.

A cultural study on communication and technology with specific reference to media in China

This dissertation examines the role of communications technology in social change. It examines secondary data on contemporary China arguing that many interpretations of events in China are unsuitable at best and at worst conceptually damages our understanding of social change in China. This is especially the case in media studies under the ‘democratic framework’. It proposes that there is an alternative framework in studying the media and social change. This alternative conceptual framework is termed a zone of interpretative development offering a means by which to discuss events that take place in a mediated environment. Taking a theoretical foundation using the philosophy of Mikhail Bakhtin this dissertation develops a platform with which to understand communication technology from an anthropological perspective. Three media events from contemporary China are examined. The first examines the Democracy Wall event and the implications of using a public sphere framework. The second case examines the phenomenon of the Grass Mud Horse, a symbol that has gained popular purchase as a humorous expression of political dissatisfaction and develops the problems seen in the first case but with some solutions. Using a modification of Lev Vygotskiĭ’s zone of proximal development this symbol is understood as an expression of the collective recognition of a shared experience. In the second example from the popular TV talent show contests in China further expressions of collective experience are introduced. With the evidence from these media events in contemporary China this dissertation proposes that we can understand certain modes of communication as occurring in a zone of interpretative development. This proposed anthropological feature of social change via communication and technology can fruitfully describe meaning-formation in society via the expression and recognition of shared experiences.

A Summary of Archaeological Excavations from 1983-1986 at the Green Family Print Shop, 18AP29, Annapolis, Maryland

18AP29, the Green Family Printshop, also known as the Jonas Green site, was excavated from 1983 to 1986 by Archaeology in Annapolis and Historic Annapolis Foundation. The site is not only the home of a significant figure in colonial Maryland but is also the location of one of the first colonial printing operations in Maryland. This site represents an important pre-industrial business in Annapolis. While this domestic site is complicated and rich, one of the most fascinating aspect of 18AP29 is the discovery of a large quantity of printers' type. Extensive analysis of the printers' type and documentary research on one of the print shop's products, the colonial newspaper, the Maryland Gazette, provides insights into the print culture which was developing during the 18th and 19th centuries. This report summarizes the stratigraphic analysis, minimum vessel counts, and faunal analysis. It provides some description of the printers' type.

Archaeological Excavations at 18AP44: 193 Main Street, Annapolis, Maryland, 1985-1987

193 Main Street (18AP44) is located between Main Street and Duke of Gloucester Street. The property was used ass a yard related to residential and commercial buildings during the 18th and 19th centuries. In the 1930's a movie theatre and parking lot were built on the property. That structure was torn down in the 1980's and a three-story commercial building was constructed. Archaeological excavations were conducted on the property from 1985-1987. A preliminary report was written in 1986 by Paul A. Shackel. This report is the final report on the archaeological investigations at 193 Main Street.

Análisis de las interacciones entre pares de alumnos en la resolución de problemas de matemáticas

La investigación que presentamos (Cobo, 1998) analiza las interacciones que se producen entre pares de alumnos en la resolución de problemas. Aunque no utilizamos la entrevista para recoger datos orales, la técnica que mostramos tiene elementos comunes a ella. La comparación de ambas puede abrir perspectivas de debate en cuanto a las semejanzas y diferencias respecto a la situación de observación, a los papeles comunicativos de los interlocutores, a la predeterminación del tema del diálogo, a las formas de analizar los datos obtenidos, etc. En las páginas siguientes hacemos una presentación general de la investigación, centrándonos, sobre todo, en la descripción de la técnica de recogida de datos orales que utilizamos, en el contexto en el que recogemos dichos datos y en el método de análisis que proponemos. En el Anexo mostramos, a modo de ejemplo, el resumen del microanálisis de uno de los episodios del proceso de resolución de un problema.

La construcción social de saberes matemáticos. El caso del tratamiento de la información

Este trabajo centra su atención en la construcción de saberes matemáticos en un ambiente de colaboración, en el que se privilegia la interacción entre los participantes, la confrontación y la negociación. Se hace una descripción de la problemática que se vive en el aprendizaje de las matemáticas y de la necesidad de innovar a través de situaciones donde el contenido matemático es relevante para el alumno y la sociedad. De igual modo se hace una descripción sucinta acerca de que esta manera de construir saberes incluye el desarrollo de competencias matemáticas, las consideradas en el plan de estudio de educación secundaria 2006. Esta descripción contiene actividades para un taller considerando el eje sobre el manejo de la información y una versión de principios para orientar su ejecución.

Teorías y Concepciones de la Matemática Educativa: una puesta en práctica en un curso de Cálculo Diferencial

La intención de este trabajo es presentar algunas teorías y concepciones de la Matemática Educativa y su implementación concreta en cursos de Cálculo Diferencial en una y varias variables. Se expondrán algunas ideas de la Resolución de Problemas, Investigación - Acción, Constructivismo Social (Teoría de Aprendizaje de Vigotsky) y algunos elementos de Ingeniería Didáctica. De todas estas teorias, se mencionan diversos ejemplos, implementados en los cursos de la Universidad de la República (Montevideo, Uruguay), entre los años 1995 y 2002. La exposición estará complementada con la presentación de resultados, y a partir de los mismos se obtendrán conclusiones y se formularán recomendaciones.

Creative leadership & communities of practice

This Second Wave presentation focused on 'Creative Leadership and Communities of Practice', with particular reference to issues of trust affecting young people, unemployment and wider uncertainties in an economic recession when people were facing job cuts and in a social environment characterised by cynicism and a downturn in trust. Young people who join Second Wave are brought into a community of practice (CoP) (Lave and Wenger, 1991; Wenger, 1999) involving a dynamic, fluid process which is distinctive in its transformative power to change people's lives. The philosophy behind this involves Dewey's notion of the 'active self' (Dewey, 1916) and the theories of 'social constructivism' (Vygotsky, 1978). The process fosters trust, confidence and social learning (Bandura, 1977; Vygotsky, 1978) in which young people join in with a dialogue involving participation in the youth-centred creative space. The 'border zone' (Heath, 1994) in that creative space enables young people to connect with each other in the specialist field of youth arts. The youth-centred partnerships involved lead to greater confidence and development in a range of important artistic, social, cognitive and emotional skills and opportunities. Ultimately, the young person may become engaged in multi-agency working with Second Wave's external partners. Throughout all of these processes, young people are encouraged progressively to develop a more 'active self' to engage proactively with many different beneficial opportunities relating to the performing arts. In an era in which there has been a loss of trust in public life this is particularly important. If trust is defined in part as a belief in the honesty, competence and benevolence of others, it tends to act like 'social glue', cushioning difficult situations and enabling actions to take place easily that otherwise would not be permissible. The Edelman Trust Barometer for 2009 has recorded a marked diminution of trust in corporations, businesses and government, as a result of the credit crunch. While the US and parts of Europe were showing recovery from a generalised loss of trust by mid-year 2009, the UK had not. Social attitudes in Britain may be hardening - from being a nation of sceptics we may be becoming a nation of cynics: for example, only 13% of the population surveyed by Edelman trust politicians to tell the truth. In this situation, there is a need to promote positive measures to build trust. The presentation aims described key aspects of Second Wave's approach to identify and disseminate its model of good practice to make this more explicit and accessible to others. It is with awareness of the profoundly challenging circumstances facing young people, particularly but not exclusively in inner city urban areas such as Deptford, and the valuable contribution youth arts work can make to their well-being and development, that the presentation was carried out. In an era of generalised mistrust, the work done at Second Wave is crucial in empowering and supporting young people to find a positive and creative direction as part of the community.

"Practise what we preach": a social constructivist approach to blended learning

This presentation reports on the formal evaluation, through questionnaires, of a new Level 1 undergraduate course, for 130 student teachers, that uses blended learning. The course design seeks to radicalise the department’s approach to teaching, learning and assessment and use students as change agents. Its structure and content, model social constructivist approaches to learning. Building on the student’s experiences of and, reflections on, previous learning, promotes further learning through the support of “able others” (Vygotsky 1978), facilitating and nurturing a secure community of practice for students new to higher education. The course’s design incorporates individual, paired, small and large group activities and exploits online video, audio and text materials. Course units begin and end with face-to-face tutor-led activities. Online elements, including discussions and formative submissions, are tutor-mediated. Students work together face-to-face and online to read articles, write reflections, develop presentations, research and share experiences and resources. Summative joint assignments and peer assessments emphasise the value of collaboration and teamwork for academic, personal and professional development. Initial informal findings are positive, indicating that students have engaged readily with course content and structure, with few reporting difficulties accessing or using technology. Students have welcomed the opportunity to work together to tackle readings in a new genre, pilot presentation skills and receive and give constructive feedback to peers. Course tutors have indicated that depth and quality of study are evident, with regular online formative submissions enabling tutors to identify and engage directly with student’s needs, provide feedback and develop appropriately designed distance and face-to-face teaching materials. Pastoral tutors have indicated that students have reported non-engagement of peers, leading to the rapid application of academic or personal support. Outcomes of the formal evaluation will inform the development of Level 2 and 3 courses and influence the department’s use of blended learning.