The need for wireless connectivity is ever increasing while conventional radio frequency (RF) communications are limited by the amount of available spectrum. Visible light communications (VLC) are emerging as a promising complementary to the RF wireless, thanks to the enormous available bandwidth in the visible spectrum. Moreover, VLC integrates into the ubiquitous illumination infrastructures to satisfy the need for wireless connectivity indoors. Commercially available light-emitting diodes (LEDs) are low-cost, simple, and have a small modulation bandwidth. For the small modulation bandwidth, VLC systems must enjoy high spectral efficiency to achieve high-rate transmission. Additionally, VLC systems must have high power efficiency to help preserve the critical advantage of LEDs for illumination applications. Furthermore, since LED luminaires are constrained by cost, deployed VLC systems must be low-complexity. Indoor VLC channels are dispersive due to multipath propagation indoors and due to the limited bandwidth of the optoelectronics. However, time-domain equalization on such channels can be prohibitively expensive for long serials. These challenges motivate extensive research on optical orthogonal frequency division multiplexing (OFDM). Given those problems and challenges, this thesis introduces novel spectrum- and power-efficient optical OFDM modulation schemes to implement with low complexity in VLC systems. Firstly, absolute value layered asymmetrically clipped optical OFDM (ALACO-OFDM) is presented to achieve high spectral efficiency and high power efficiency with fewer layers, thus requiring low complexity. Compared to its counterparts, ALACO-OFDM can achieve higher spectral efficiency and information rate even with fewer layers. Antisymmetry-constructed clipped optical OFDM (AC-OFDM) is then introduced as a novel low-complexity modulation scheme. To enhance the spectral efficiency and retain low-complexity, layered AC-OFDM (LAC-OFDM) is introduced, consisting of several layers of AC-OFDM signals. LAC-OFDM is shown to be less complex compared to its state-of-the-art counterparts. Concerning a practical VLC dispersive channel, low-complexity layered ACO-OFDM (L-LACO) is introduced with simple equalization. Mathematically, L-LACO generates identical signals to the existing layered asymmetrically-clipped optical OFDM (LACO-OFDM); however, it requires only half arithmetic operations at both the transmitter and the receiver. For a practical bandlimited VLC dispersive channel, the previous optical OFDM modulation schemes will be no longer non-negative after interpolation with sinc(t) pulse. This thesis presents Kramers-Kronig (KK) optical OFDM (KKO-OFDM) to enhance the spectral efficiency and power efficiency for such bandlimited VLC channels. The KKO-OFDM transmit signal is constructed to be real-valued, non-negative, and strictly bandlimited. Numerical results show that KKO-OFDM outperforms DCO-OFDM and LACO-OFDM in bandlimited VLC channels in terms of optical power efficiency. / Thesis / Doctor of Philosophy (PhD) / Visible light communications (VLC) integrate into the ubiquitous light-emitting diode (LED) luminaires, providing lighting and communication simultaneously. Commercially available LEDs are low-cost, simple, and have a limited modulation bandwidth. These LEDs demand that VLC orthogonal frequency division multiplexing (OFDM) modulation schemes be spectrum- and power-efficient with low complexity. Concerning these challenges, this thesis presents a novel spectrum- and power-efficient VLC OFDM scheme with low complexity. Firstly, absolute value layered asymmetrically clipped optical OFDM (ALACO-OFDM) is presented to achieve high spectral and power efficiency while requiring fewer layers. Then layered antisymmetry-constructed clipped optical OFDM (LAC-OFDM) is introduced, which requires low complexity as compared to existing layered asymmetrically-clipped optical OFDM (LACO-OFDM). Given a VLC dispersive channel, low-complexity LACO-OFDM (L-LACO) is furthermore introduced with simple equalization but generates an identical signal to the existing LACO-OFDM. Finally, for a bandlimited VLC channel, Kramers-Kronig optical OFDM (KKO-OFDM) is presented to achieve high spectral and power efficiency. The ALACO-OFDM and LAC-OFDM work in flat VLC line-of-sight links while L-LACO in VLC dispersive links and KKO-OFDM in bandlimited VLC dispersive links with simple equalizer.

No description available.

Visible light communication (VLC) systems take advantage of ubiquitous light-emitting diodes (LED) and leverage existing illumination infrastructure to provide broadband optical communication links. Multiple-input multiple-output (MIMO) VLC systems are among the well studied topics in VLC research. However, most traditional MIMO VLC systems require accurate alignment and have to adjust to different magnifications at various link distances. Consequently, the alignment and calibration modules increase the complexity of the receiver structures. A pixelated MIMO VLC system is introduced in this thesis, which transmits a series of time-varying coded images that can be received and decoded by commercial digital cameras. Using a convex lens placed in front of the transmitter at its focal length, the system exploits the Bokeh effect to obtain fixed-scale images at all link distances. Compared with traditional pixelated MIMO VLC systems, which send information directly in space, this spatial-angular mapping system sends information in different angles instead. In contrast to the complex receiver structures in traditional setups, the proposed system can capture fixed-scale images with a simple receiver requiring no re-focusing as the camera moves. The channel model of the system is measured and modeled and a rateless code is applied to track the truncation of receive images for various link ranges and angular offsets. A proof-of-concept optical communication system is implemented with an LCD display and a high speed CMOS camera. Performance of the system is measured and analysed. The experimental system can achieve a throughput of approximately 10 bit per frame over 90 cm. This fixed-scale pixelated MIMO wireless optical communication system provides a less expensive option for short-range indoor broadcasting optical links and inter-vehicle communications due to its mobility, stability and simpler receiver structure compared to traditional designs in different working conditions. / Thesis / Master of Applied Science (MASc)

« Il n'y a pas d'image au théâtre. Il est l'invisible qui vient dans l'image et l'indicible qui vient dans la parole » Voilà comment Olivier Py, définit le théâtre, texte et représentation. L'étude de l'image dans le théâtre d'Olivier Py est une réflexion sur l'évolution du texte dramatique contemporain et sur le processus d'exercice du regard d'un spectateur qui se trouve au carrefour des différentes esthétiques traditionnelles et modernes. L'émigration de l'image du texte à la scène demeure la question qui bouleverse tout le processus de la création théâtrale, aussi bien sur le plan théorique que pratique.Le poème écrit n'est plus seulement une organisation cohérente d'actions accomplies mais, aussi, l'espace où l'écriture permet le transport du logos à l'opsis.La scène devient, ainsi, l'espace dialectique du partage du sensible entre acteur et spectateur, scène et salle, réel et virtuel, visible et invisible…Bref, le théâtre d'Olivier Py est l'univers des images qui se manifestent en présence réelle, « comme en état de grâce », mais qui, rapidement, deviennent fugaces, figures, simulacres, comme des spectres qui se dérobent. / "There is no image to the theater. it is the invisible which comes in the image and the unspeakable which comes in the world". Her is how Olivier Py, defines the theater, the text and the representation. The study of the image in the theater of Olivier Py is the reflection on the evolution of the contemporary dramatic text and on the process of exercise of the look of a spectator who is in the crossroads of the various traditional and modern esthetics. The migration of the image of the text in the podium raises the question which upsets all the process of the theatrical creation, as well on the theoretical plan that has a practice.The written poem is not any more only a coherent organization of accomplished actions but, also, the space where the writing allows the transport of the logos to the opsis. The scene becomes, hence, the dialectical space of the sharing of the sensitive between actor and spectator, stage and room, real and virtual, visible and invisible...Concisely, the theater of Olivier Py is the universe of the effigies which show themselves in real presence, "as in a state of grace", but which, speedly, become fleeting, figures, enactments, as spectres which get away.

Podemos encontrar em métodos ágeis como no Extreme Programming [Beck, 1999, Beck e Andres, 2006], no Scrum [Schwaber, 2008], no Crystal Clear [Cockburn, 2005], e no Lean Software Development [Poppendieck e Poppendieck, 2007] referências relacionadas à manipulação e disponibilização de métricas e outras informações no ambiente de desenvolvimento. Neste trabalho, estas atividades são consideradas como tarefas de acompanhamento ágil. Observamos em métodos ágeis a importância de se realizar ações (práticas) baseadas em alguns princípios como guidelines [Poppendieck e Poppendieck, 2007]. Por isto, realizamos uma análise bibliográca na literatura disponível para compreender princípios ágeis que possam afetar na execução deste tipo de tarefa, além de escrever sobre métricas no contexto de métodos ágeis e engenharia de software. Apesar da bibliograa, não encontramos pesquisas experimentais com o objetivo de levantar e (ou) compreender aspectos relacionados ao sucesso na aplicação deste tipo de tarefa em ambientes de desenvolvimento. Para isto, realizamos neste trabalho uma pesquisa experimental com este objetivo, utilizando uma abordagem de métodos mistos sequenciais de pesquisa [Creswell, 2009]. Escolhemos aplicar esta pesquisa em um conjunto de quinze equipes de desenvolvimento ágil, reunidas em realizações da disciplina Laboratório de Programação Extrema do IME-USP nos anos de 2010 e 2011. Esta pesquisa foi realizada em quatro fases sequenciais. Na primeira fase, realizamos sugestões para as equipes de desenvolvimento vinculadas ao acompanhamento ágil a m de levantar aspectos valiosos em sua aplicação utilizando uma abordagem baseada em pesquisa-ação [Thiollent, 2004]. Baseado nestes resultados, agrupamos alguns destes aspectos como heurísticas para o acompanhamento ágil, modelo similar ao de Hartmann e Dymond [2006]. Na segunda fase, aplicamos um questionário para vericar a validade das heurísticas levantadas. Na terceira fase, realizamos entrevistas semi-estruturadas com alguns integrantes destas equipes para compreender o por quê da validade das heurísticas levantadas, sendo analisadas com técnicas de teoria fundamentada em dados (grounded theory)[Strauss e Corbin, 2008]. Na quarta fase, reaplicamos o questionário da fase 2 em outro ambiente para triangulação da validade das heurísticas. Como resultado nal da pesquisa, estabelecemos um conjunto de heurísticas para o acompanhamento ágil, além de avaliações quantitativas de seus aspectos em dois ambientes, juntamente a diversas considerações qualitativas sobre sua utilização. Realizamos um mapeamento tanto das heurísticas como de seus conceitos relacionados à literatura disponível, identicando aspectos já existentes porém expandidos pela realização da pesquisa, e aspectos ainda não discutidos que podem ser considerados como novos na área. / It is possible to find on the agile methods several references related to managing and displaying relevant information in a software development worplace. These references are available in agile methods such as Extreme Programming [Beck, 1999, Beck e Andres, 2006], Scrum [Schwaber, 2008], Crystal Clear [Cockburn, 2005], Lean Software Development [Poppendieck e Poppendieck, 2007],etc. In our work, we name this kind of activity as agile tracking, relating it to the tracker role defined by Beck [1999]. We noticed the importance of performing actions (practices) based on a set of principles as guidelines [Poppendieck e Poppendieck, 2007], which is deeply associated with agile methods. Taking this matter into account, we performed a literature review in order to discuss a few agile principles that could affect the execution of agile tracking related tasks. We also describe a few works directly related to metrics, both on the agile methods and on the software engineering area in general. Even with related references in the literature, we could not find empirical researches with the goal of raising/understanding aspects related to successfully performing this kind of task on agile environments, which could be helpful on managing informations and informative workspaces. In order to accomplish this goal, we performed a research using a sequential mixed research methods approach [Creswell, 2009]. We chose to apply our research on a set of fifteen agile teams gathered on the IME-USP\'s \"Laboratory of Extreme Programming\" course in 2010 and 2011. This research was performed in four sequential phases. In the first phase, we made several suggestions to the agile teams, regarding agile tracking, using and approach based on action research [Thiollent, 2004]. We used this initial approach in order to gather relevant aspects of their use of agile tracking. Based on these results, we clustered some aspects as \"heuristics for agile tracking\", the same model used by Hartmann e Dymond [2006]. In phase two, we applied a survey to evaluate the validity of the proposed heuristics. In phase three, we gathered data from a few semi-structured interviews performed on team members in order to understand the reasons behind the proposed heuristics, in which we used grounded theory [Strauss e Corbin, 2008] coding techniques for analysis. In phase four, we reapplied phase two survey on a different environment in order to triangulate the heuristics evaluation data gathered on phase 2. As the result of this empirical research, a set of heuristics were established with quantitative evaluation data and several related qualitative concepts. We also relate the set of heuristics and associated concepts with other works in agile methods, highlighting aspects expanded by this research and some others that we could not directly find in the literature, which could be considered as new in the area.

L’objet de cette thèse est le développement et l’étude de la photoréactivité de TiO2, absorbant dans le visible et ayant des propriétés autonettoyantes et de dépollution de l’eau et de l‘air. Dans ce contexte, des films d’épaisseur controlée et mésostructurés de TiO2 non dopés et dopés par différents métaux (platine, vanadium et tungstène) , ont été synthétisés par voie sol-gel combinée au procédé d'auto-assemblage induit par évaporation. Les propriétés structurales et optiques ainsi que la composition chimique de la surface des films ont été caractérisées par de nombreuses techniques de caractérisation telles que DRX, GISAXS, TEM, MEB ellipsoporosimétrie, DRUV et XPS. Une étude complète des propriétés photocatalytiques des films à base de TiO2 aux interfaces solide-solide, solide-liquide et solide-gaz a été réalisée en utilisant respectivement les tests avec de l’acide stéarique, du bleu de méthylène et de l’acétone. Durant cette étude, nous avons montré qu’un contrôle adapté de l’épaisseur des films, de la nature et de la quantité du dopant peut améliorer l’activité photocatalytique jusqu’à un facteur de 16 par rapport à des films non dopés. Des tests préliminaires de piégeage chimiques des radicaux OH• par l’acide téréphtalique sous irradiation UV ont montré qu’il existait une bonne corrélation entre la photoréactivité et la génération des radicaux OH•. / The aim of this thesis is the development and study of photocatalytic properties of visible light photoactive mesoporous TiO2-based films to act as self-cleaning, and purification systems applied to air and water. Pure and doped mesoporous titania films with different metals as Pt, V and W were prepared by sol-gel method combined with evaporation induced self-assembly process at different thicknesses. Structural, optical properties and chemical composition of these films were characterized by XRD, GISAXS, TEM, SEM, ellipsoporosimetry , DRUV and XPS. In order to better characterize and compare the efficiency of these films at solid-solid, liquid-solid and air-solid interfaces, several tests were used: mineralization of stearic acid, photobleaching of methylene blue and photooxidation of acetone. In this study, it is shown how a suitable control of the film thickness, the nature and amount of the dopant can improve the photocatalytic activity up to a factor of 16 relative to un-doped films. Preliminary results on the OH• radicals production using terephtalic acid as a chemical probe showed good correlation between photoreactivity and generation of these radicals.

Objective: This systematic review explored how “adjustment” is generally defined in adults with an acquired visible difference (AVD) and what positive psychological factors have been evidence to be associated with positive coping and processes of adjustment in AVD. Method: A systematic search for peer reviewed journal articles from 1980 to February 2016 was conducted using: PyschINFO, Medline, EMBASE and CINAHL. Studies were appraised according to eligibility criteria and evaluated against a quality criterion to assess risk of bias. Results: Fourteen studies were included and were in the areas of head and neck cancer, burns and amputation. Selected studies demonstrated inconsistent conceptualisations of adjustment ranging from: lack of psychopathology, resilience, post-traumatic growth and quality of life. Psychological factors identified were; social functioning (social support, social self-efficacy), coping strategies (emotion, problem-focused, active coping) and dispositional optimism. Studies were considered to be of moderate methodological quality with weaknesses including; a lack of control/comparison groups, lack of measure sensitive to the unique challenges of living with AVD and minimal account for confounding variables. Results are discussed in the context of future research implications. Objective: This study aimed to explore the relationship between two dimensions of attachment insecurity (avoidance and anxiety), body image dissatisfaction and perfectionism using theoretically driven multiple mediation models that included emotion dysregulation and interpersonal problems as hypothesised mediators. Method: Fifty female outpatients seeking cosmetic surgery on the National Health Service (NHS) and 26 females interested in seeking cosmetic surgery within the public domain participated in this cross-sectional study (N=76). Participants completed measures of attachment avoidance and anxiety, body image dissatisfaction, perfectionism, emotion dysregulation and interpersonal problems. Results: Attachment insecurity was significantly associated with body image dissatisfaction and perfectionism. Interpersonal problems and emotion dysregulation also significantly partially mediated the relationship between attachment insecurity and body image dissatisfaction, specifically satisfaction with discrete aspects of body parts. Emotion dysregulation was also found to significantly partially mediate the relationship between avoidant attachment and perfectionism, but not anxiety. The clinical implications of this research are discussed.

La quête du détecteur parfait, sans bruit, capable de détecter des photons uniques dans le visible et l’infrarouge, et ultimement de déterminer leur énergie est le graal de la détection. Pour arriver à ce but, de nombreux scientifiques ont développé des dispositifs depuis plusieurs dizaines d’années, et les astronomes ont toujours été à la pointe en ce domaine. En ce sens les imageurs à amplification semblent être la voie la plus rapide et la plus prometteuse pour atteindre ce but ultime. Ainsi après un bref historique de l’état de l’art sont exposés les systèmes à comptage de photons (IPCS) développés au LAM, qui ont été utilisés sur les télescopes ESO 3m60, OHP 1m93 ou encore WHT 4m20. Sont ensuite abordés les dispositifs imageurs intégrés à amplification comme les EMCCD (Electron multiplying charge coupled devices) dans le visible, avec quelques exemples de leur utilisation en astronomie. C’est la technologie qui, appliquée aux senseurs de front d’onde, aura permis conjointement à d’autres développements l’avènement des optiques adaptatives extrêmes comme celle de l’instrument VLT-SPHERE ou encore de SUBARU-SCExAO. Pour finir les e-APD (electron initiated avalanche photodiode) dans l’infrarouge seront abordés. Les e-APD ont cette propriété très intéressante d’être des amplificateurs quasi parfaits, et ont une capacité à détecter l’énergie des photons, des propriétés qui seront développées et analysées. Nous finirons par les perspectives et les progrès que nous sommes en droit d’attendre dans les prochaines années. / The quest for the perfect, noiseless detector, capable of detecting unique photons in the visible and infrared, and ultimately determining their energy is the grail of detection. To achieve this goal, many scientists have developed devices for several decades, and astronomers have always been at the forefront in this area. In this sense amplification imagers seem to be the fastest and most promising way to achieve this ultimate goal. Thus, after a brief history of the state of the art are exposed the photon counting systems (IPCS) developed at LAM, which were used on ESO telescopes 3m60, OHP 1m93 or WHT 4m20. Imaging integrated imaging devices such as Electron Multiplying Charge Coupled Devices (EMCCDs) are then discussed in the visible, with some examples of their use in astronomy. It is the technology that, applied to the wavefront sensors, has jointly enabled other developments the advent of extreme adaptive optics such as the VLT-SPHERE or SUBARU-SCExAO. To finish the e-APD (electron-induced avalanche photodiode) in the infrared will be discussed. E-APDs have this very interesting property of being almost perfect amplifiers, and have an ability to detect photon energy, properties that will be developed and analyzed. We will end up with the prospects and the progress that we are entitled to expect in the coming years.

Although Canada is internationally known for its multicultural practices, the work life experiences of visible minority female school principals are unheard and absent from educational leadership research in Canada. In light of the fact that the student population in Canadian schools is increasingly diversifying, it is important to examine the experiences of visible minority female school principals from their own perspectives in order to gain a better understanding of their work life in the education system across Canada.<p> This research is a qualitative case study of the administrative work life experiences of five visible minority female school principals in five selected Western Canadian public schools. The purpose of the research was to examine and describe the administrative work life experiences of the selected visible minority female principals, with a particular focus on the path they took to become principals, the challenges they faced, and the strategies they used to foster inclusive schools. In-depth interviews were the main research method used in this study, supplemented by document and record analyses and the researchers reflective journal. Each of the five participants was interviewed three times in order to provide an in-depth analysis of their work experiences. The data were analyzed by using narrative and inductive analysis to let the participants tell their stories first and analyze the research questions inductively second. The results of this study revealed that the path to the principalship for visible minority female principals is influenced by multi-factors, personal abilities and strengths, challenges, supports, and preparatory and training programs. Each of the participants went through different processes to achieve their goal based on their own unique situations. This study also revealed the participants in their principal positions faced personal, professional, and organizational challenges related to gender, race, and accent. However, the participants regarded these challenges as opportunities for them to learn and to grow.<p> The strategies used to build inclusive schools by the five participants stemmed from the participants personal attributes, skills, support systems, and the contribution of their minority status. In their leadership positions, individuals set a clear mission, varied leadership styles, used reciprocal empowerment, demonstrated an ethic of care, acted as mentors, pursued networking, and mastered necessary positional knowledge.<p> This study provides recommendations for other visible minority female principals and visible minority female teachers who aspire to principal positions by identifying steps needed to prepare for the principalship; recommendations for Boards of Education on policy making and action as well as recommendations for professional development. Implications for future research are also set out. This study, while confirming the findings of the research done by other scholars, also has its own unique findings, and the five participants work life experiences provided five pictures of successful visible minority female school principals in Western Canadian public schools

Although Canada is internationally known for its multicultural practices, the work life experiences of visible minority female school principals are unheard and absent from educational leadership research in Canada. In light of the fact that the student population in Canadian schools is increasingly diversifying, it is important to examine the experiences of visible minority female school principals from their own perspectives in order to gain a better understanding of their work life in the education system across Canada.<p> This research is a qualitative case study of the administrative work life experiences of five visible minority female school principals in five selected Western Canadian public schools. The purpose of the research was to examine and describe the administrative work life experiences of the selected visible minority female principals, with a particular focus on the path they took to become principals, the challenges they faced, and the strategies they used to foster inclusive schools. In-depth interviews were the main research method used in this study, supplemented by document and record analyses and the researchers reflective journal. Each of the five participants was interviewed three times in order to provide an in-depth analysis of their work experiences. The data were analyzed by using narrative and inductive analysis to let the participants tell their stories first and analyze the research questions inductively second. The results of this study revealed that the path to the principalship for visible minority female principals is influenced by multi-factors, personal abilities and strengths, challenges, supports, and preparatory and training programs. Each of the participants went through different processes to achieve their goal based on their own unique situations. This study also revealed the participants in their principal positions faced personal, professional, and organizational challenges related to gender, race, and accent. However, the participants regarded these challenges as opportunities for them to learn and to grow.<p> The strategies used to build inclusive schools by the five participants stemmed from the participants personal attributes, skills, support systems, and the contribution of their minority status. In their leadership positions, individuals set a clear mission, varied leadership styles, used reciprocal empowerment, demonstrated an ethic of care, acted as mentors, pursued networking, and mastered necessary positional knowledge.<p> This study provides recommendations for other visible minority female principals and visible minority female teachers who aspire to principal positions by identifying steps needed to prepare for the principalship; recommendations for Boards of Education on policy making and action as well as recommendations for professional development. Implications for future research are also set out. This study, while confirming the findings of the research done by other scholars, also has its own unique findings, and the five participants work life experiences provided five pictures of successful visible minority female school principals in Western Canadian public schools