High-dynamic range tone-mapping algorithm for focal plane processors

This paper presents a Dynamic Range improvement technique which is specially well-suited to be implemented in Focal Plane Processors (FPP) due to its very limited computing requirements since only local memories, little digital control and a comparator are required at the pixel level. The presented algorithm employs measurements during exposure time to create a 4-bit non-linear image whose histogram determines the shape of the tone-mapping curve which is applied to create the final image. Simulations results over a highly bimodal 120dB image are presented showing that both the highly and poorly illuminated parts of the image keep a sufficient level of details.Ministerio de Ciencia e Innovación TEC2009-11812Junta de Andalucía 2006-TIC-235

Non-intrusive load monitoring techniques for activity of daily living recognition

Esta tesis nace con la motivación de afrontar dos grandes problemas de nuestra era: la falta de recursos energéticos y el envejecimiento de la población. Respecto al primer problema, nace en la primera década de este siglo el concepto de Smart Grids con el objetivo de alcanzar la eficiencia energética. Numerosos países comienzan a realizar despliegues masivos de contadores inteligentes ("Smart Meters"), lo que despierta el interés de investigadores que comienzan a desarrollar nuevas técnicas para predecir la demanda. Así, los sistemas NILM (Non-Intrusive Load Monitoring) tratan de predecir el consumo individual de los dispositivos conectados a partir de un único sensor: el contador inteligente. Por otra parte, los grandes avances en la medicina moderna han permitido que nuestra esperanza de vida aumente considerablemente. No obstante, esta longevidad, junto con la baja fertilidad en los países desarrollados, tiene un efecto secundario: el envejecimiento de la población. Unos de los grandes avances es la incorporación de la tecnología en la vida cotidiana, lo que ayuda a los más mayores a llevar una vida independiente. El despliegue de una red de sensores dentro de la vivienda permite su monitorización y asistencia en las tareas cotidianas. Sin embargo, son intrusivos, no escalables y, en algunas ocasiones, de alto coste, por lo que no están preparados para hacer frente al incremento de la demanda de esta comunidad. Esta tesis doctoral nace de la motivación de afrontar estos problemas y tiene dos objetivos principales: lograr un modelo de monitorización sostenible para personas mayores y, a su vez, dar un valor añadido a los sistemas NILM que despierte el interés del usuario final. Con este objetivo, se presentan nuevas técnicas de monitorización basadas en NILM, aunando lo mejor de ambos campos. Esto supone un ahorro considerable de recursos en la monitorización, ya que únicamente se necesita un sensor: el contador inteligente; lo cual da escalabilidad a estos sistemas. Las contribuciones de esta tesis se dividen en dos bloques principales. En el primero se proponen nuevas técnicas NILM optimizadas para la detección de la actividad humana. Así, se desarrolla una propuesta basada en detección de eventos (conexiones de dispositivos) en tiempo real y su clasificación a un dispositivo. Con el objetivo de que pueda integrarse en contadores inteligentes. Cabe destacar que el clasificador se basa en modelos generalizados de dispositivos y no necesita conocimiento específico de la vivienda. El segundo bloque presenta tres nuevas técnicas de monitorización de personas mayores basadas en NILM. El objetivo es proporcionar una monitorización básica pero eficiente y altamente escalable, ahorrando en recursos. Los procesos Cox, log Gaussian Cox Processes (LGCP), monitorizan un único dispositivo si la rutina está estrechamente ligada a este. Así, se propone un sistema de alarmas si se detectan cambios en el comportamiento. LGCP tiene la ventaja de poder modelar periodicidades e incertidumbres propias del comportamiento humano. Cuando la rutina no depende de un único dispositivo, se proponen dos técnicas: una basada en gaussianas mixtas, Gaussian Mixture Models (GMM); y la otra basada en la Teoría de la Evidencia de Dempster-Shafer (DST). Ambas monitorizan y detectan deterioros en la actividad, causados por enfermedades como la demencia y el alzhéimer. Únicamente DST usa incertidumbres que simulan mejor el comportamiento humano y, por tanto, permite alarmas en caso de un repentino desvío. Finalmente, todas las propuestas han sido validadas mediante la evaluación de métricas y la obtención de resultados experimentales. Para ello, se han usado medidas de escenarios reales que han sido recopiladas en bases de datos. Los resultados obtenidos han sido satisfactorios, demostrando que este tipo de monitorización es posible y muy beneficioso para nuestra sociedad. Además, se ha dado a lugar nuevas propuestas que serán desarrolladas en el futuro. Códigos UNESCO: 120320 - sistemas de control medico, 332201 – distribución de la energía, 120701 – análisis de actividades, 120304 – inteligencia artificial, 120807 – plausibilidad, 221402 – patrones

Hardware and software platforms to deploy and evaluate non-intrusive load monitoring systems

The work in this PhD thesis addresses the practical implications of deploying and testing Non-Intrusive Load Monitoring (NILM) and eco-feedback solutions in real-world scenarios. The contributions to this topic are centered around the design and development of NILM frameworks that have been deployed in the wild, supporting long-term research in ecofeedback and also serving the purpose of producing real-world datasets and furthering the state of the art regarding the performance metrics used to evaluate NILM algorithms. This thesis consists of three main parts: i) the development of tools and datasets for NILM and eco-feedback research, ii) the design, implementation and deployment of NILM and eco-feedback technologies in real world scenarios, and iii) an experimental comparison of performance metrics for event detection and event classification algorithms. In the first part we describe the Energy Monitoring and Disaggregation Data Format (EMD-DF) and the SustData and SustDataED public datasets. In second part we discuss the development and deployment of two hardware and software platforms in real households, to support eco-feedback research. We then report on more than five years of experience in deploying and maintaining such platforms. Our findings suggest that the main practical issues can be divided in two categories, technological (e.g., system installation) and social (e.g., maintaining a steady sample throughout the whole study). In the final part of this thesis we analyze experimentally the behavior of a number of performance metrics for event detection and event classification, identifying clusters and relationships between the different measures. Our results evidence some considerable differences in the behavior of the performance metrics when applied to the different problems.O trabalho desenvolvido nesta tese de doutoramento aborda as implicações praticas da instalação e avaliação de soluções de monitorização não intrusiva de cargas elétricas (NILM) e eco-feedback em cenários reais. As contribuições para este tópico estão centradas em torno da concepção e desenvolvimento de plataformas NILM que foram instaladas em ambientes não controlados, suportando a pesquisa de longo termo em eco-feedback e servindo também o propósito de produzir conjuntos de dados científicos, bem como promover o avanço do estado da arte acerca das métricas de desempenho utilizadas para avaliar algoritmos NILM. Esta tese é constituída por três partes principais: i) o desenvolvimento de ferramentas e conjuntos de dados científicos para investigação em NILM e eco-feedback, ii) a concepção, desenho e instalação de tecnologias NILM e eco-feedback em cenários reais, e iii) uma comparação experimental de métricas de desempenho para algoritmos de detecção e de classificação de eventos. Na primeira parte descrevemos o Energy Monitoring and Disaggregation Data Format (EMD-DF) e os conjuntos de dados científicos SustData e SustDataED. Na segunda parte discutimos o desenvolvimento e instalação de duas plataformas de hardware e software em residências atuais com a finalidade de suportar a investigação em eco-feedback. Aqui, reportamos sobre mais de cinco anos de experiência na instalação e manutenção destes sistemas. Os nossos resultados sugerem que as principais implicações práticas podem ser divididas em duas categorias, físicas (e.g., instalação do sistema) e sociais (e.g., manter uma amostra constante ao longo de todo o estudo). Na terceira parte analisamos experimentalmente o comportamento de uma série de métricas de desempenho quando estas são utilizadas para avaliar algoritmos de detecção e de classificação de eventos. Calculamos as correlações lineares e não lineares entre os vários pares de métricas, e com base nesses valores procuramos agrupar as métricas que evidenciam um comportamento semelhante. Os nossos resultados sugerem a existência de diferenças evidentes no comportamento das métricas quando aplicadas a ambos dos problemas.Fundação para a Ciência e a Tecnologi

Snapshot Three-Dimensional Surface Imaging With Multispectral Fringe Projection Profilometry

Fringe Projection Profilometry (FPP) is a popular method for non-contact optical surface measurements, including motion tracking. The technique derives 3D surface maps from phase maps estimated from the distortions of fringe patterns projected onto the surface of an object. Estimation of phase maps is commonly performed with spatial phase retrieval algorithms that use a series of complex data processing stages. Researchers must have advanced data analysis skills to process FPP data due to a lack of availability of simple research-oriented software tools. Chapter 2 describes a comprehensive FPP software tool called PhaseWareTM that allows novice to experienced users to perform pre-processing of fringe patterns, phase retrieval, phase unwrapping, and finally post-processing. The sequential process of acquiring fringe patterns from an object is necessary to sample the surface densely enough to accurately estimate surface profiles. Sequential fringe acquisition performs poorly if the object is in motion between fringe projections. To overcome this limitation, we developed a novel method of FPP called multispectral fringe projection profilometry (MFPP), where multiple fringe patterns are composited into a multispectral illumination pattern and a single multispectral camera is used to capture the frame. Chapter 3 introduces this new technique and shows how it can be used to perform 3D profilometry at video frame rates. Although the first attempt at MFPP significantly improved acquisition speed, it did not fully satisfy the condition for temporal phase retrieval, which requires at least three phase-shifted fringe patterns to characterize a surface. To overcome this limitation, Chapter 4 introduces an enhanced version of MFPP that utilized a specially designed multispectral illuminator to simultaneously project four p/2 phase-shifted fringe patterns onto an object. Combined with spectrally matched multispectral imaging, the refined MFPP method resulted in complete data for temporal phase retrieval using only a single camera exposure, thereby maintaining the high sampling speed for profilometry of moving objects. In conclusion, MFPP overcomes the limitations of sequential sampling imposed by FPP with temporal phase extraction without sacrificing data quality or accuracy of the reconstructed surface profiles. Since MFPP utilizes no moving parts and is based on MEMS technology, it is applicable to miniaturization for use in mobile devices and may be useful for space-constrained applications such as robotic surgery. Fringe Projection Profilometry (FPP) is a popular method for non-contact optical surface measurements such as motion tracking. The technique derives 3D surface maps from phase maps estimated from the distortions of fringe patterns projected onto the surface of the object. To estimate surface profiles accurately, sequential acquisition of fringe patterns is required; however, sequential fringe projection and acquisition perform poorly if the object is in motion during the projection. To overcome this limitation, we developed a novel method of FPP maned multispectral fringe projection profilometry (MFPP). The proposed method provides multispectral illumination patterns using a multispectral filter array (MFA) to generate multiple fringe patterns from a single illumination and capture the composite pattern using a single multispectral camera. Therefore, a single camera acquisition can provide multiple fringe patterns, and this directly increases the speed of imaging by a factor equal to the number of fringe patterns included in the composite pattern. Chapter 3 introduces this new technique and shows how it can be used to perform 3D profilometry at video frame rates. The first attempt at MFPP significantly improved acquisition speed by a factor of eight by providing eight different fringe patterns in four different directions, which permits the system to detect more morphological details. However, the phase retrieval algorithm used in this method was based on the spatial phase stepping process that had a few limitations, including high sensitive to the quality of the fringe patterns and being a global process, as it spreads the effect of the noisy pixels across the entire result. To overcome this limitation, Chapter 4 introduces an enhanced version of MFPP that utilized a specially designed multispectral illuminator to simultaneously project four p/2 phase-shifted fringe patterns onto an object. Combined with a spectrally matched multispectral camera, the refined MFPP method provided the needed data for the temporal phase retrieval algorithm using only a single camera exposure. Thus, it delivers high accuracy and pixel-wise measurement (thanks to the temporal phase stepping algorithms) while maintaining a high sampling rate for profilometry of moving objects. In conclusion, MFPP overcomes the limitations of sequential sampling imposed by FPP with temporal phase extraction without sacrificing data quality or accuracy of the reconstructed surface profiles. Since MFPP utilizes no moving parts and is based on MEMS technology, it is applicable to miniaturization for use in mobile devices and may be useful for space-constrained applications such as robotic surgery

A digital signal processing system developed for the optimal use of high density magnetic storage media

High density data recording has traditionally been an essential factor in the development of communication and transmission systems. However, recently more sophisticated applications, including video recording, have necessitated refinements of this technology. This study concentrates on the signal processing techniques used to inhance the packing density of stored data. A comparison of the spectral mapping characteristics of different codes illustrates that the need for equalization can be eliminated and that significant bandwidth reduction can be achieved. Secondly, consideration is given to the deleterious effects of flutter, its associated effects on high density data recording, and the constraints imposed on the development of a time base corrector. An analysis is made of the bandlimiting effect which results when the incoming data is convolved with the head impulse response. The bandwidth of the channel, the size of the head gap, and the velocity of the media are seen from this analysis to be intrinsically related. These signal processing techniques are implemented, the channel capacity computed, and a significant channel efficiency achieved

A multimodal analysis of assessment sequences in Chilean Spanish interaction

This thesis presents a study of food assessments in Chilean Spanish interaction. The data consists of video recordings of six pairs of Chilean participants sampling British foods unknown to them. They tried each food at the same time and discussed their opinions. They were asked to do a joint ranking of these products to elicit sequences of agreement and disagreement. The data is analysed combining the methods of conversation analysis with those of interactional linguistics and the study of embodied interaction. There are three analytic chapters. The first one explores what constitutes a canonical assessment, i.e. aspects of the turn design of assessments in the particular context of the data and how they compare to the literature in English. The second analytic chapter is about the lead-up to an assessment. I explore how speakers initiate assessments (with particular attention to the role of eye gaze). The third analytic chapter deals with how non-lexical (and other) tokens and the co-occurring embodied aspects of their production (prosodic features, gestures, etc.) are designed and understood as projecting a stance towards the food. All things considered, this thesis contributes to filling a knowledge gap in relation to the study of assessments in the Spanish language. It also contributes the novelty of studying food assessments among non-experts. Finally, this thesis sheds light on how assessments arise in interaction and about the emergence of linguistic organisation through other non-verbal activities

Automatic Drum Transcription and Source Separation

While research has been carried out on automated polyphonic music transcription, to-date the problem of automated polyphonic percussion transcription has not received the same degree of attention. A related problem is that of sound source separation, which attempts to separate a mixture signal into its constituent sources. This thesis focuses on the task of polyphonic percussion transcription and sound source separation of a limited set of drum instruments, namely the drums found in the standard rock/pop drum kit. As there was little previous research on polyphonic percussion transcription a broad review of music information retrieval methods, including previous polyphonic percussion systems, was also carried out to determine if there were any methods which were of potential use in the area of polyphonic drum transcription. Following on from this a review was conducted of general source separation and redundancy reduction techniques, such as Independent Component Analysis and Independent Subspace Analysis, as these techniques have shown potential in separating mixtures of sources. Upon completion of the review it was decided that a combination of the blind separation approach, Independent Subspace Analysis (ISA), with the use of prior knowledge as used in music information retrieval methods, was the best approach to tackling the problem of polyphonic percussion transcription as well as that of sound source separation. A number of new algorithms which combine the use of prior knowledge with the source separation abilities of techniques such as ISA are presented. These include sub-band ISA, Prior Subspace Analysis (PSA), and an automatic modelling and grouping technique which is used in conjunction with PSA to perform polyphonic percussion transcription. These approaches are demonstrated to be effective in the task of polyphonic percussion transcription, and PSA is also demonstrated to be capable of transcribing drums in the presence of pitched instruments

Non-convex Quadratically Constrained Quadratic Programming: Hidden Convexity, Scalable Approximation and Applications

University of Minnesota Ph.D. dissertation. September 2017. Major: Electrical Engineering. Advisor: Nicholas Sidiropoulos. 1 computer file (PDF); viii, 85 pages.Quadratically Constrained Quadratic Programming (QCQP) constitutes a class of computationally hard optimization problems that have a broad spectrum of applications in wireless communications, networking, signal processing, power systems, and other areas. The QCQP problem is known to be NP–hard in its general form; only in certain special cases can it be solved to global optimality in polynomial-time. Such cases are said to be convex in a hidden way, and the task of identifying them remains an active area of research. Meanwhile, relatively few methods are known to be effective for general QCQP problems. The prevailing approach of Semidefinite Relaxation (SDR) is computationally expensive, and often fails to work for general non-convex QCQP problems. Other methods based on Successive Convex Approximation (SCA) require initialization from a feasible point, which is NP-hard to compute in general. This dissertation focuses on both of the above mentioned aspects of non-convex QCQP. In the first part of this work, we consider the special case of QCQP with Toeplitz-Hermitian quadratic forms and establish that it possesses hidden convexity, which makes it possible to obtain globally optimal solutions in polynomial-time. The second part of this dissertation introduces a framework for efficiently computing feasible solutions of general quadratic feasibility problems. While an approximation framework known as Feasible Point Pursuit-Successive Convex Approximation (FPP-SCA) was recently proposed for this task, with considerable empirical success, it remains unsuitable for application on large-scale problems. This work is primarily focused on speeding and scaling up these approximation schemes to enable dealing with large-scale problems. For this purpose, we reformulate the feasibility criteria employed by FPP-SCA for minimizing constraint violations in the form of non-smooth, non-convex penalty functions. We demonstrate that by employing judicious approximation of the penalty functions, we obtain problem formulations which are well suited for the application of first-order methods (FOMs). The appeal of using FOMs lies in the fact that they are capable of efficiently exploiting various forms of problem structure while being computationally lightweight. This endows our approximation algorithms the ability to scale well with problem dimension. Specific applications in wireless communications and power grid system optimization considered to illustrate the efficacy of our FOM based approximation schemes. Our experimental results reveal the surprising effectiveness of FOMs for this class of hard optimization problems

Literary Practices and the Curriculum Context: Exploring the Production of Assignments in a South African Vocational Higher Education Institution

This thesis explores curriculum construction and the production of assignments in two courses at a vocational higher education institution in South Africa, namely Film and Video Technology and Graphic Design. The influence of the vocational curriculum context on student and lecturer practices is examined through two analytical frameworks, literacy as social practice and Bernstein's concept of recontextualisation. An ethnographic methodology was used to investigate the broader curriculum context and literacy practices engaged in by students and lecturers. Fieldwork was carried out over a six-month period, while generating and collecting fieldnote, interview, documentary and photographic data. The analysis is presented as two separate case studies, one in each department. The study's interpretive approach is used to bring together the Bernstein focus on recontextualisation and curriculum with the Academic Literacies notion of literacy practice. The significant role of the curriculum context in the patterning of the literacy practices students engage in when producing their assignments is therefore recognised. The findings highlight the way the university of technology sectoral domain operates as a third aspect in the recontextualisation process alongside the professional and disciplinary domains, resulting in conflicting messages. Primacy is given to texts and literacy practices that resemble those in the professional domains. However, essayist literacies are also foregrounded and reflect generic and decontextualized understandings of writing that function as an important mechanism through which the sectoral domain asserts its position in the academy. The research demonstrates that the Academic Literacies and Bernsteinian frames can successfully be combined in empirical research, allowing the individual students' experiences to be located within broader institutional and sectoral structures in a way that challenges deficit views of the student. A further conclusion drawn is how an Academic Literacies lens can help to identify the workings of the sectoral domain thus broadening the analytical frame beyond individual institutional conditions