Since the dawn of the space race, satellites have grown rapidly in complexity and shrunk equally rapidly in size. Most of them contain an Attitude Determination and Control System (ADCS) on board for pointing and detumbling manoeuvres. These intricate systems are designed for an outer space environment, hence, phenomenon otherwise abscent in space, such as gravity and aerodynamic drag present a challenge in validating these systems on Earth. The gimbal suspension testbed aims to provide a 3 Degree of Freedom (DoF) suspension where the mounted satellite under test can rotate about either axis. The suspension induces disturbance torques that must be modeled in order for the testbed to be characterized. This is accomplished by formulating the necessary gimbal dynamics, bearing friction, aerodynamic and Center of Mass (CoM) displacement torque model. This yields a relationship from which all torques present in the system can be expressed in terms of the angles, angular velocities and angular accelerations of the gimbal frames. By measuring the angles and obtaining the velocities and accelerations through numerical differentiation, the torques that correspond to a certain motion can be calculated. Furthermore, the thesis covers the iterative design of the gimbal suspension and all of its constituents, the angular measurement method and a Finite Element Method (FEM) simulation to estimate deformations. The result is presented in terms of a simulation that validates the models by predicting its behaviour for certain movement. The final result is a series of characterization plots that tells the user of the gimbal testbed how much torque must be produced by the CubeSat ADCS in order to operate it. / Sedan begynnelsen av rymdkapplöpningen har satelliter snabbt ökat i komplexitet och lika snabbt minskat i storlek. De flesta satelliter har ett attitydsbestänings- och kontrollsystem (ADCS) ombord för att kunna utföra vissa manövrar. Dessa system är designade för rymdmiljön, därför kan fenomen som annars är frånvarande i rymden, så som gravitation och luftmotstånd, innebära en utmaning då man önskar att validera systemet på jorden. Gimbalupphängningen förmedlar rotation med tre frihetsgrader där satelliten under test kan rotera kring alla tre axlar. Upphängningen inducerar störmoment som måste modelleras för att den ska bli ordentligt karaktäriserad. Detta åstadkoms genom att formulera gimbalens dynamiska förhållanden, kullagerfriktion, luftmotstånd och masscenterförflyttning. Dessa samband kopplar samman alla moment som är närvarande i systemet som funktion av gimbalramarnas vinklar, vinkelhastigheter och vinkelaccelerationer. Genom att mäta vinklarna och erhålla vinkelhastigheter och vinkelacceleration genom numerisk derivering kan momenten som motsvarar den uppmätta rörelsen beräknas. Dessutom presenteras den iterativa designen av gimbalupphängningen och alla dess beståndsdelar, vinkelmätningsmetoden och en finita elementmetodssimulering för att uppskaffa deformationer. Resultatet presenteras i form av simuleringar som validerar modellen genom att förutspå dess beteende för viss rörelse. Det slutgiltiga resultatet är en serie av karaktäriseringsgrafer som förmedlar till användaren just hur mycket moment dess CubeSats ADCS måste producera för att kunna använda gimbalupphängingen.

Syftet med uppsatsen är att kartlägga behovet av en testbädd för telemedicinska produkter och att analysera krav som medicintekniska företag ställer på en testbäddsmiljö för samverkan med sjukvården. Målet har varit att konkretisera resultatet i en kommersialiseringsplan för Karolinska Testbädd för Telemedicin och eHälsa, vid Medicinsk Teknik på Karolinska Universitetssjukhuset. Vid genomförandet av undersökningen har totalt 19 intervjuer och ytterligare 6 telefonintervjuer genomförts med dels representanter från medicintekniska företag och sjukvården och dels med samarbetsstrukturer för medicinsk teknik och möjliga finansiärer. En enkätundersökning har genomförts för att kvantifiera resultatet från intervjuerna. Webbutskick har gjorts till 279 företag med verksamhet inom områdena medicinsk teknik, IT och telekom. Uppsatsen beskriver hur den kliniska forskningen inom området medicinsk teknik har förändrats de senaste decennierna och hur situationen ser ut idag. Utmaningar som den svenska hälso- och sjukvården står inför presenteras, som demografiska förändringar, ökade sjukvårdskostnader, dyrare behandlingsmetoder och färre kommersialiserade innovationer inom medicinsk teknik.  Omständigheter som påverkar produktutveckling för hälso- och sjukvården belyses, dels genom den regulatoriska gränsdragningen mellan IT-produkter och medicintekniska produkter och dels utifrån en genomgång av forskning inom produkt- och tjänsteutveckling och utifrån de frågor kring hur företag bedriver produktutveckling som ställts i intervjuerna och i webbenkäten. Resultatet visar att företagen i högsta grad är beroende av samarbete med sjukvården i olika faser av sin produktutvecklingsprocess och att flera företag uttrycker ett behov av en testbäddsstruktur. Företagen samarbetar med vården framförallt för att det möjliggör att utveckla mer vårdanpassade produkter. Samarbete med vården ger kortare utvecklingstider och därmed minskade utvecklingskostnader. Det förenklar även arbetet med validering av produkters funktionalitet. Flera företag har utarbetade samarbeten direkt in på vårdavdelningar, medan andra i dagsläget saknar nödvändiga samarbetsstrukturer. Studien har identifierat ett flertal företag som visat intresse för ett samarbete med Testbädden och ytterligare ett antal som har önskat att få mer information om vad Testbädden kan erbjuda. I kommersialiseringsplanen föreslås Karolinska Testbädd för Telemedicin och eHälsa fokusera på sin nisch samt vidareutveckla den kompetens som företagen saknar. Testbädden bör arbeta vidare med att utveckla både externa kontakter och den interna samverkansorganisationen på Karolinska för att möjliggöra effektiva, smidiga och kvalitativa samarbeten mellan företag och sjukhusets avdelningar. / The purpose is to study the demand for a testbed for telemedicine and to analyze the medical device-developing companies’ requirements on the testbed’s facilities when collaborating with the healthcare sector in their product development. The study’s aim is to result in a commercialization plan for Karolinska Testbed for telemedicine and eHealth, at the department of Biomedical Engineering at Karolinska University Hospital. During the study, 19 interviews and 6 telephone-interviews has been held with people from the medical device industry, hospitals, potential funders and collaboration structures which foster medical device development. A web-survey has been sent to 279 companies within the fields of medical technologies, IT and telecom, to quantify the results from the interviews. The study describes how the clinical research on medical technologies has changed over the last decades and what the situation is like today. Present and forthcoming challenges to the Swedish health care system is presented, like demographic changes, increasing healthcare-costs, expensive treatments and the scarcity of medical device innovations being commercialized. Obstacles affecting the medical device development are studied, including the regulatory differences between IT and medical devices. An analysis of the research on product and service development is also looked at from the perspectives on how the medical device companies develop their products, which is derived from both interviews and the web-survey. The result shows that medical device companies rely upon the ability to collaborate with the hospitals in different phases of their product development process and that there is an extensive need for a testbed structure amongst companies. The companies that collaborate with hospitals do it primarily because it makes their products more adaptive to functioning in the settings of healthcare, time to market and development costs can be decreased and it facilitates the process when validating the functionality of their products. Several companies have their ways of collaborating with hospital wards whilst others explicitly lack indispensable collaboration structures. The study has identified some companies which have shown interest in collaborating with Testbed Karolinska for telemedicine and eHealth and other ones whom wish to receive more information on what the testbed can offer them. In the commercialization plan it is suggested that Karolinska Testbed for telemedicine and eHealth shall focus on their niche and elaborate the competency which the companies doesn’t have. It is also suggested that the Testbed continues the work with developing the internal organization within Karolinska to enable efficient, flexible and qualitative collaboration between companies and the clinics at Karolinska University Hospital.

Τα ασύρματα δίκτυα μικροαισθητήρων είναι μια πρόσφατη κατηγορία αδόμητων υπολογιστικών δικτύων, τα οποία αποτελούνται από κόμβους με μικρό μέγεθος και περιορισμένους υπολογιστικούς και ενεργειακούς πόρους. Τέτοιοι κόμβοι έχουν δυνατότητες μέτρησης φυσικών μεγεθών (όπως πχ. θερμοκρασία, υγρασία, κ.α.), ασύρματης επικοινωνίας μεταξύ τους, και σε κάποιες περιπτώσεις αλληλεπίδρασης με το περιβάλλον τους (μέσω κατάλληλων ηλεκτρομηχανικών μερών). Καθώς τα δίκτυα αυτά έχουν αρχίσει να γίνονται πιο προσιτά (από άποψη κόστους και διαθεσιμότητας hardware), το πεδίο εφαρμογής και η φιλοσοφία χρήσης τους συνεχώς εξελίσσεται και διευρύνεται. Έτσι, έχουμε παραδείγματα εφαρμογών από παρακολούθηση της βιοποικιλότητας μιας περιοχής έως την παρακολούθηση στατικότητας κατασκευών, και δίκτυα με πλήθος κόμβων από δεκάδες έως και εκατοντάδες ή και χιλιάδες κόμβων. Κατά την εκπόνηση της διδακτορικής διατριβής ασχοληθήκαμε με τις εξής βασικές ερευνητικές κατευθύνσεις που αφορούν στα συγκεκριμένα δίκτυα: α) την εξομοίωσή τους, β) την ανάπτυξη πρωτοκόλλων διάδοσης πληροφορίας κατάλληλων για αυτά τα δίκτυα και τη μελέτη της απόδοσής τους μέσω εξομοίωσης, γ) τη μοντελοποίηση εχθρικών συνθηκών («εμποδίων») σε ένα τέτοιο δίκτυο και την εφαρμογή τους στο επίπεδο της εξομοίωσης, δ) την ανάπτυξη εφαρμογών για τη διαχείρισή τους. Στο σκέλος της εξομοίωσης, δόθηκε αρχικά έμφαση στην αποδοτική εξομοίωση τέτοιου τύπου δικτύων με μέγεθος αρκετών χιλιάδων κόμβων, και στα πλαίσια της έρευνας μας αναπτύχθηκε ένα περιβάλλον εξομοίωσης (simDust), με δυνατότητα προσθήκης νέων πρωτοκόλλων καθώς και οπτικοποίησης. Το περιβάλλον αυτό χρησιμοποιήθηκε ακολούθως για την επέκταση και πειραματική αξιολόγηση ορισμένων χαρακτηριστικών υπαρχόντων πρωτοκόλλων διάδοσης πληροφορίας σε ασύρματα δίκτυα μικροαισθητήρων. Παράλληλα, αναπτύξαμε ένα νέο πρωτόκολλο και κάναμε μια σύγκριση της απόδοσής του με άλλα αντίστοιχα πρωτόκολλα. Η πειραματική μας αξιολόγηση έδειξε ότι το νέο πρωτόκολλο, το οποίο βασίζεται σε δυναμικές αλλαγές της ακτίνας μετάδοσης των κόμβων του δικτύου, συμπεριφέρεται αποδοτικότερα από άλλα πρωτόκολλα της υπάρχουσας βιβλιογραφίας, και συγκεκριμένα σε δίκτυα με εμπόδια και ανομοιογενή ανάπτυξη των αισθητήρων. Στη συνέχεια, δόθηκε έμφαση στην προσθήκη «ρεαλιστικών» συνθηκών κατά τη διάρκεια της εξομοίωσης τέτοιων πρωτοκόλλων, οι οποίες να λειτουργούν ανταγωνιστικά ως προς τα πρωτόκολλα αυτά. Σκοπός μας ήταν να προταθεί ένα μοντέλο, το οποίο να μπορεί να περιγράψει συνθήκες που περιορίζουν την αποτελεσματικότητά τους. Συγκεκριμένα, προτείναμε και υλοποιήσαμε ένα ολοκληρωμένο μοντέλο ``εμποδίων'', το οποίο εισάγει μικρή πρόσθετη υπολογιστική πολυπλοκότητα σε έναν εξομοιωτή, ενώ παράλληλα για να εξετάσουμε την επίδρασή του εστιάσαμε σε πρωτόκολλα τα οποία χρησιμοποιούν γεωγραφική γνώση (απόλυτη ή σχετική) για να δρομολογήσουν την πληροφορία μέσα σε ένα δίκτυο ασύρματων μικροαισθητήρων. Τέτοια πρωτόκολλα είναι σχετικά ευαίσθητα σε δυναμικές αλλαγές της τοπολογίας και των συνθηκών του δικτύου. Μέσω πειραματικής αξιολόγησης δείξαμε την σημαντική επίδραση που μπορούν να έχουν συγκεκριμένες αντίξοες συνθήκες μέσα στο δίκτυο στην απόδοση αυτών των πρωτοκόλλων. Στο σκέλος των εφαρμογών, προτείναμε αρχικά μια αρχιτεκτονική (WebDust/ShareSense) για ένα σύστημα διαχείρισης τέτοιων δικτύων, το οποίο να παρέχει βασικές δυνατότητες δημιουργίας εφαρμογών για τέτοια δίκτυα σε συνδυασμό με επεκτασιμότητα. Χαρακτηριστικά που ξεχωρίζουν είναι η δυνατότητα διαχείρισης πολλαπλών ετερογενών ασύρματων δικτύων μικροαισθητήρων, η ανοικτότητα, η χρήση peer-to-peer αρχιτεκτονικής για τη διασύνδεση πολλών διαφορετικών δικτύων. Υλοποιήθηκε μέρος του προτεινόμενου συστήματος, ενώ στη συνέχεια το σύστημα αναθεωρήθηκε σε ότι αφορά την αρχιτεκτονική του και εμπλουτίστηκε με πρόσθετες δυνατότητες παρουσίασης. / Wireless sensor networks are a recently introduced category of ad hoc computer networks, which are comprised by nodes of small size and limited computing and energy resources. Such nodes are able of measuring physical properties such as temperature, humidity, etc., wireless communication between each other and in some cases interaction with their surrounding environments (through the use of electromechanical parts). As these networks have begun to be widely available (in terms of cost and commercial hardware availability), their field of application and philosophy of use is constantly evolving. We have numerous examples of their applications, ranging from monitoring the biodiversity of a specific outdoor area to structural health monitoring of bridges, and also networks ranging from few tens of nodes to even thousands of nodes. In this PhD thesis we investigated the following basic research lines related to wireless sensor networks: a) their simulation, b) the development of data propagation protocols suited to such networks and their evaluation through simulation, c) the modelling of ``hostile'' circumstances (obstacles) during their operation and evaluation of their impact through simulation, d) the development of a sensor network management application. Regarding simulation, we initially placed an emphasis to issues such as the effective simulation of networks of several thousands of nodes, and in that respect we developed a network simulator (simDust), which is extendable through the addition of new data propagation protocols and visualization capabilities. This simulator was used to evaluate the performance of a number of characteristic data propagation protocols for wireless sensor networks. Furthermore, we developed a new protocol (VRTP) and evaluated its performance against other similar protocols. Our studies show that the new protocol, that uses dynamic changes of the transmission range of the network nodes, performs better in certain cases than other related protocols, especially in networks containing obstacles and in the case of non-homogeneous placement of nodes. Moreover, we emphasized on the addition of ``realistic'' conditions to the simulation of such protocols, that have an adversarial effect on their operation. Our goal was to introduce a model for obstacles that adds little computational overhead to a simulator, and also study the effect of the inclusion of such a model on data propagation protocols that use geographic information (absolute or relative). Such protocols are relatively sensitive to dynamic topology changes and network conditions. Through our experiments, we show that the inclusion of obstacles during simulation can have a significant effect on these protocols. Finally, regarding applications, we initially proposed an architecture (WebDust/ShareSense), for the management of such networks, that would provide basic capabilities of managing such networks and developing applications above it. Features that set it apart are the capability of managing multiple heterogeneous sensor networks, openess, the use of a peer-to-peer architecture for the interconnection of multiple sensor network. A large part of the proposed architecture was implemented, while the overall architecture was extended to also include additional visualization capabilities.

Orientador: Euripedes Guilherme de Oliveira Nobrega / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-06T09:41:01Z (GMT). No. of bitstreams: 1 Amorim_MauricioJose_M.pdf: 2137966 bytes, checksum: bc8b0e13365a14be8d6bd6c336785b31 (MD5) Previous issue date: 2006 / Resumo: Este trabalho apresenta uma bancada didática destinada ao ensino nos cursos de engenharia de aplicações em projetos de controle, processamento digital de sinais e programação em tempo real. Bancadas didáticas são ferramentas indispensáveis ao ensino, considerando que os conceitos vistos apenas em sala de aula são muitas vezes abstratos. A bancada em questão foi desenvolvida partindo de projeto mecânico já existente, tendo sido colocados na estrutura sensores extensométricos para obter a resposta do sistema como deformação e projetado o circuito condicionador do sinal para essa resposta. Para a prirneira fase, envolvendo identificação, controle da estrutura e análise dos resultados, foram projetados dois acionadores para os motores que aplicam o distúrbio e o esforço de controle sobre a planta. Após terem sido satisfeitas as etapas da primeira fase, o próximo passo foi transferir o sistema de controle para uma configuração embarcada utilizando um microcontrolador. Para tanto, algumas adaptações e novos projetos emergiram diante da mudança do ambiente de processamento. A necessidade de adaptar os sinais para a nova placa de aquisição exigiu mudança em alguns circuitos. o acionador de motor para uma saída de controle modulada em largura de pulso foi desenvolvido utilizando componentes discretos. Além disso, é detalhadamente abordada a programação em tempo real do sistema de controle em questão / Abstract: This work presents the design of a didactic tesbed intended to teaching control system design, digital processing of signals and real-time programming. Didactic tesbeds are very vaIuabIe tools when applying concepts developed inside the classroom. The testbed developed here is built upon a previous mechanical design. Strain gages were used as measuring devices using a conditioning circuit. FirstIy, system identification, structural control and analysis of the results were proceeded, two motor drives were designed to operate motors performing both disturbance and control inputs. Afterwards, the control system was redesigned to operate using a micracontraller unit in a embedded architeture. Some adaptations on the circuits were needed and are covered here. A DC motor circuit driver using PWM signal was developed using discrete components. Besides, real-time programming of the control system is covered in detail / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Ämnet för uppsatsen grundar sig i en ökad efterfrågan av att kunna införa teknik och informationsteknik (IT), som är testad och anpassad för en verksamhet redan innan införandet. Vidare finns det ett behov av att, genom nya innovationer, uppnå långsiktiga strategiska mål inom vård och omsorg. Därför har Sveriges innovationsmyndighet Vinnova startat en satsning på testbäddar inom vård och omsorg. En testbädd kan liknas vid en innovations- och testmiljö där samarbete mellan vårdpersonal, företag och forskning kan ske för att ta fram produkter, processer och tjänster som är anpassade till den miljö där dessa sedan ska tillämpas. Denna studie berör hur utveckling och organisering av en innovations- och testmiljö kan gå till och vilka utmaningar som finns. Vidare tar vi upp intressenters roller och behov i utvecklingen samt hur innovation kan stimuleras i en organisation. Detta har genomförts med hjälp av en fallstudie kring utvecklingen av en testbädd i Landstinget i Östergötland (LIÖ). Teorier inom områdena intressenter, utveckling och innovation används för att stödja analysen och skapa förståelse för vissa begrepp. Den empiriska undersökningen utförs genom semistrukturerade intervjuer med representanter från olika intressentgrupper till testbädd LIÖ. Analysen genomförs även med hjälp av dokumentstudier som en del i den empiriska undersökningen. Det empiriska materialet diskuteras i relation till den teoretiska referensramen för att uppnå ett kunskapsbidrag i form av en slutsats. Denna berör hur en innovations- och testmiljö kan utvecklas och organiseras, intressenternas roll och behov i utvecklingen samt hur innovationer kan genereras och utvecklas i organisationer. Med fallets hjälp kan praktiken ge ny kunskap om dessa områden inför kommande utvecklingsprojekt av liknande karaktär. / The topic of this paper is based on an increased demand for the introduction of technology and information technology (IT), which is better tested and adapted for a business before the implementation. Furthermore, there is a need that through new innovations, achieve long-term strategic objectives in the care sector. Therefore, the Swedish innovation agency Vinnova started a venture in test beds in healthcare. A test bed can be likened to an innovation and testing environment. In these, collaboration between healthcare professionals, businesses and research is done to develop products, processes and services that are adapted to the environment in which they are then applied. This study concerns the development and organization of an innovation- and testing environment and what the challenges are. It also concerns the roles and the needs of the stakeholders in the development and how innovation can be achieved in an organization. This has been studied by a case concerning the development of the testbed LIÖ in Östergötland County Council. Theories in the fields of stakeholders, development and innovation are used to support the analysis around these parts, and to create an understanding of some concepts. The empirical study is carried out through semi-structured interviews with representatives from various stakeholder groups to testbed LIÖ. The analysis is also carried out with the help of document studies as part of the empirical investigation. The empirical data are discussed in relation to the theoretical framework for achieving a knowledge contribution in the form of a conclusion. This affects how an innovation and test environment can be developed and organized, stakeholder roles and needs of the development and how innovations can be generated and developed in organizations. The study of the case can provide new knowledge in these areas for future development projects of similar nature.

The future power grid will effectively utilize renewable energy resources and distributed generation to respond to energy demand while incorporating information technology and communication infrastructure for their optimum operation. This dissertation contributes to the development of real-time techniques, for wide-area monitoring and secure real-time control and operation of hybrid power systems. To handle the increased level of real-time data exchange, this dissertation develops a supervisory control and data acquisition (SCADA) system that is equipped with a state estimation scheme from the real-time data. This system is verified on a specially developed laboratory-based test bed facility, as a hardware and software platform, to emulate the actual scenarios of a real hybrid power system with the highest level of similarities and capabilities to practical utility systems. It includes phasor measurements at hundreds of measurement points on the system. These measurements were obtained from especially developed laboratory based Phasor Measurement Unit (PMU) that is utilized in addition to existing commercially based PMU’s. The developed PMU was used in conjunction with the interconnected system along with the commercial PMU’s. The tested studies included a new technique for detecting the partially islanded micro grids in addition to several real-time techniques for synchronization and parameter identifications of hybrid systems. Moreover, due to numerous integration of renewable energy resources through DC microgrids, this dissertation performs several practical cases for improvement of interoperability of such systems. Moreover, increased number of small and dispersed generating stations and their need to connect fast and properly into the AC grids, urged this work to explore the challenges that arise in synchronization of generators to the grid and through introduction of a Dynamic Brake system to improve the process of connecting distributed generators to the power grid. Real time operation and control requires data communication security. A research effort in this dissertation was developed based on Trusted Sensing Base (TSB) process for data communication security. The innovative TSB approach improves the security aspect of the power grid as a cyber-physical system. It is based on available GPS synchronization technology and provides protection against confidentiality attacks in critical power system infrastructures.

En los últimos años, el consumo de servicios multimedia ha aumentado y se prevé que esta tendencia continúe en un futuro próximo, convirtiendo el tema de la evaluación de la Calidad de la Experiencia (QoE) en un tema muy importante para valorar el servicio de los proveedores. En este sentido, la optimización de la QoE recibe cada vez más atención ya que las soluciones actuales no han tenido en cuenta, la adaptación, la viabilidad, la rentabi-lidad y la fiabilidad. La presente memoria se centra en la caracterización, diseño, desarrollo y evaluación de diferentes aplicaciones multimedia, con el fin de optimizar la QoE. Por tanto, este trabajo investiga la influencia que la infraestructura de redes, las características de los videos y los terminales de los usuarios, presentan en la QoE de los servicios multimedia actuales en Internet. Esta tesis se basa en la investigación exhaustiva de la evaluación subjetiva y objetiva de QoE en redes heterogéneas. Los desafíos y cuestiones relacionados con el estado de la técnica y se discuten en esta disertación. En la primera fase, diseñamos una metodología de prueba para evaluar la QoE en la transmisión de video en directo y a través de plataformas de video bajo demanda en redes Wi-Fi y celulares. A partir de esta fase inicial, propondremos los problemas a investigar y las preguntas para resolver a lo largo de esta disertación. Nuestra metodología hace uso de métricas subjetivas y objetivas para evaluar la QoE percibida por los usuarios finales. Se realiza un conjunto de experimentos en laboratorio donde nuestra metodología de pruebas es aplicada. Los resultados obtenidos se recopilan y analizan para extraer las relaciones entre la Calidad de servicio (QoS) y QoE. A partir de estos resultados, se propone un mapeo de QoS-QoE que permite predecir la QoE. En la siguiente fase de la investigación, desarrollamos los algoritmos de optimización de QoE basados en la administración del sistema de red para redes Wi-Fi y celulares. Los algoritmos usan los parámetros clave que se tuvieron en cuenta para la evaluación de QoE. El objetivo de estos algorit-mos es proporcionar un sistema de gestión flexible para las redes con el ob-jetivo de lograr un equilibrio controlado entre la maximización de QoE y la eficiencia del uso de los recursos. Por último, se diseña el banco de pruebas del sistema para evaluar el rendimiento de las aplicaciones de servicios multimedia genéricos en los diferentes entornos de prueba. El banco de pruebas del sistema se basa en el enfoque de virtualización; usa los recursos compartidos de un hardware fí-sico para virtualizar todos los componentes. El banco de pruebas virtualiza-do proporciona funciones de red virtualizadas para diferentes escenarios, como Internet (las redes de distribución de contenido - CDNs) y redes inalámbricas. Por lo tanto, se adoptan protocolos livianos y mecanismos ágiles en el sistema, para proporcionar un mejor servicio a los usuarios fina-les. Los resultados de QoE son proporcionados a los proveedores de servi-cios de acuerdo con los parámetros que se definen en el proceso de la eva-luación. Como resultado hemos obtenido un sistema que presenta un servi-cio rentable como una forma factible para la evaluación de la prueba. / In recent years, multimedia services consumption has increased and it is expected that this trend will continue in the near future, becoming the evaluation of Quality of Experience (QoE) as a very important issue for assessing the quality of providers' services. In this sense, the optimization of the QoE is progressively receiving much attention considering that current solutions are not based on the adaptation, feasibility, cost-effectiveness, and reliability. The present dissertation is focused on the characterization, design, development and evaluation of different multimedia applications aimed to optimize the QoE. Therefore, this work investigates the influence that the networks infrastructure, the videos' characteristics and the users' terminals present on QoE of the current Internet multimedia services. The work is based on a comprehensive research of subjective and objective assessments in heterogeneous networks. Challenges and research questions related to the state of the art are discussed in this dissertation. In the first phase of this dissertation, we design a test methodology for assessing QoE of live video streaming and video on demand platforms to be transmitted over Wi-Fi and cellular networks. From this initial step, we will propound the related research issues and questions to solve this dissertation. Our methodology considers the use of subjective and objective metrics to evaluate the QoE perceived by end-users. A set of laboratory experiments is conducted where our proposed methodology is applied. The obtained results are gathered and analyzed to extract the relations between Quality of Service (QoS) and QoE. From the results, we propose a QoS-QoE mapping which allows predicting QoE. In the next phase of the research, we develop QoE-optimization algorithms based on network system management for Wi-Fi and cellular networks. The algorithms use the key parameters that were taken into account for QoE assessment. The goal of these algorithms is to provide a flexible management system for the networks in order to achieve the desirable trade-off between QoE maximization and resource usage efficiency. Lastly, the system testbed is designed in order to evaluate the performance of generic multimedia services applications for the different environments under test. The system testbed is based on virtualization approach; it uses the shared resources of a physical hardware to virtualize all components. The virtualized testbed provides virtualized network functions for the different scenarios such as the Internet (Content Delivery Networks - CDNs) and wireless networks. Therefore, lightweight protocols and agile mechanisms are adopted in the system to provide enhanced service to end-users. The QoE results are reported to the service providers according to the parameters defined in the evaluation process. As a result, we have obtained a cost-effective system, which is considered as a feasible way for test evaluation. / En els últims anys, el consum de serveis multimèdia ha augmentat i es preveu que aquesta tendència continue en un futur pròxim, convertitnt el tema de l'avaluació de la Qualitat d'Experiència (QoE) una tasca molt im-portant per a valorar el servei dels proveïdors. En aquest sentit, l'optimització de la QoE rep cada vegada més atenció degut a que les solucions actuals no tenen en compte, l'adaptació, la viabilitat, el rendiment i la fiabilitat. La present memòria se centra en la caracterització, disseny, desenvolupament i avaluació de diferents aplicacions multimèdia, amb la finalitat d'optimitzar la QoE. Per tant, aquest treball investiga la influència que la infraestructura de les xarxes, les característiques dels videos i els terminals dels usuaris tenen sobre la QoE dels serveis multimèdia actuals d'Iinternet. Aquesta tesi es basa en una recerca exhaustiva de l'avaluació subjectiva i objectiva de QoE en xarxes heterogènies. Els desafiaments i preguntes relacionats amb l'estat de la tècnica es discuteixen en aquesta dissertació. En la primera fase, dissenyem la metodologia de prova per a avaluar la QoE de transmissió de video en directe i de plataformes de video baix demanda en xarxes Wi-Fi i cel·lulars. A partir d'aquest primer pas, proposem els problemes de recerca relacionats i les preguntes a resoldre a través d'a-questa tesi. La nostra metodologia fa ús de mètriques subjectives i objecti-ves per a avaluar la QoE dels usuaris finals. Es realitzen un conjunt d'expe-riments en laboratori on s'aplica la nostra metodología. Els resultats obtin-guts es recopilen i analitzen per a extraure les relacions entre la QoS i la QoE. A partir d'aquests resultats, esproposa un mapatge de QoS-QoE que ens permetrà predir la QoE. En la següent fase de la recerca, desenvolupem els algoritmes d'optimi-tzació de la QoE per a l'administració de xarxes Wi-Fi i cel·lulars. Els algo-ritmes utilitzen els paràmetres clau que es van tenir en compte per a l'ava-luació de QoE. L'objectiu d'aquests algoritmes és proporcionar un sistema de gestió flexible per ales xarxes que permetrá aconseguir un equilibri con-trolat entre la maximització de la QoE i l'us eficient dels recursos. Finalment, el banc de proves del sistema està dissenyat per a avaluar el rendiment de les aplicacions de serveis multimèdia genèrics en els diferents entorns de prova. El banc de proves del sistema es basa en l'enfocament de virtualització; usa els recursos compartits d'un equip físic que virtualitza tots els components. El banc de proves virtualitzat proporciona les funcions de xarxa virtualitzades per a diferents escenaris, com Internet (les xarxes de distribució de continguts - CDNs) i xarxes sense fils. Per tant, s'adopten protocols lleugers i mecanismes àgils en el sistema per a proporcionar un millor servei als usuaris finals. Els resultats de QoE son proporcionats als proveïdors de serveis d'acord amb els paràmetres que es defineixen en el procés de l'avaluació. Com a resultat, hem obtés un sistema que presenta un servei rendible i com a viable per a l'avaluació de la prova. / Abdullah, MT. (2018). Smart Client-Server Protocol and Architecture for Adaptive Multimedia Streaming [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/103324 / TESIS

In astronomy, interferometry by ground-based telescopes offers the greatest angular resolution. However, the Earth´s atmosphere distorts the incident wavefront from a celestial object, leading to blurring and signal loss. It also restricts the transmission of specific wavelengths within the electromagnetic spectrum. Space-based interferometers would mitigate atmospheric obstruction and potentially enable even higher angular resolutions. The main challenge of implementing space-based interferometry is the necessity of matching the light´s optical path differences at the telescopes within the coherence length of the light utilizing physical delay lines. This thesis explores the potential realization of digital delay lines via heterodyne interferometry. The technique generates a heterodyne beat note at the frequency difference between the incident stellar light and a reference laser in the radio regime, permitting digitization of the delay line while preserving the phase information for image reconstruction. The primary objective of the thesis is to advance the field of astronomy by constructing a testbed environment for investigating future space-based heterodyne interferometry in the NIR light range. It requires the achievement of two main tasks. Firstly, a laboratory starlight simulator is developed to simulate a distant star´s wavefront appearance as it reaches telescopes on or around Earth. The consequent starlight simulator contains an optical assembly that manifests a point source in NIR light, aligned with a mirror collimator’s focal point, transforming the wavefront from spherical to planar. Secondly, a fiber optical circuit with interference capability is constructed, consisting of a free-space optical delay line and a polarization-controlled custom-sized fiber. The delay line matches the optical paths within the light's coherence length, while the polarization controller optimizes interference visibility. The completion of the tasks establishes the foundation to investigate space-based heterodyne interferometry in the NIR light with the potential implementation of delay line digitization.

This thesis project has been conducted during a five-month research exchange visit to the Space Structure Dynamics and Control research group at University College Dublin. This report presents the design, development, and validation of a nanosatellite attitude control testbed. The testbed was designed to replicate the microgravity conditions of space by utilising an air bearing, enabling single-axis rotational motion for a 1U CubeSat-sized nanosatellite. The novel aspect of this research is the inclusion of two-degree-of-freedom, lumped-mass flexible appendages on either side of the nanosatellite, emulating a lightweight, flexible space structure. These flexible appendages were designed based on the stiffness characteristics of a deployable CubeSat solar array system found in existing literature, with exaggerated motion to amplify the measurable effects of various control approaches. The central focus of this project was the development of an avionics stack closely resembling CubeSat attitude control boards. The stack uses an STM32 microcontroller as the primary attitude control computer, and a suite of off the shelf breakout boards for sensors and wireless telemetry systems. Power, serial and I2C buses connect the attitude control board and the onboard computer board. A reaction wheel actuator controls the Euler heading attitude. The testbed was designed as an experimental platform for validating control algorithms developed through a model-based approach. Integration with the Simulink Embedded Coder toolbox allows for the compilation of Simulink models into C code, facilitating direct execution on the testbed. The testbed’s physical construction involves 3D printed ABS components, with the inclusion of load cells to measure disturbance torques from the excited flexible appendages. Results from validation experiments show that a simple PID controller causes significant excitation in the flexible appendages during a slew manoeuvre. However, the introduction of an input shaped attitude profile tailored to the natural frequency of the appendages successfully reduced the measured appendage excitation by 50%. Conversely, the force impedance wave based control approach did not show a reduction in appendage excitation, but shows promise for further developments in future work. In conclusion, the testbed has successfully achieved its predefined project objectives, albeit requiring further refinement, particularly in the telemetry down-link system. It is recommended that future work focuses on enhancement of the telemetry system, and validation of a model based approach to controller design. / Detta examensarbete har utförts under ett fem månaders forskningsutbyte vid forskningsgruppen Space Structure Dynamics and Control vid University College Dublin. Denna rapport presenterar design, utveckling och validering av en testbädd för attitydstyrning av en nanosatellit. Testbädden utformades för att efterlikna mikrogravitationsförhållandena i rymden genom att använda ett luftbärande lager, vilket möjliggör rotationsrörelse kring en axel för en nanosatellit av storleken 1U CubeSat. En unik aspekt av detta arbete är inkluderingen av två-frihet-graders, sammansatta flexibla påhängen på vardera sidan av nanosatelliten, vilket efterliknar en lätt, flexibel rymdstruktur. Dessa flexibla påhängen utformades med utgångspunkt från styvhetsegenskaperna hos ett utskjutbart CubeSat-solcellssystem som finns i befintlig litteratur, med överdriven rörelse för att förstärka de mätbara effekterna av olika styrmetoder. Det centrala fokuset för detta projekt var utvecklingen av en avionikstack som nära liknar CubeSat-attitydregleringkort. Stacken använder en STM32-mikrokontroller som primär dator för attitydkontroll och ett urval färdiga breakout-kort för sensorer och trådlös telemetri. Strömförsörjning, serie- och I2C-bussar ansluter attitydregleringkortet och omborddatorn med en reaktionshjulsaktuator som styr Euler-attityd. Testbädden utformades som en experimentell plattform för att validera styralgoritmer som utvecklats med hjälp av en modellbaserad metod. Integration med Simulink Embedded Coder möjliggör kompilering av Simulink-modeller till C-kod, vilket underlättar direkt exekvering på testbädden. Testbäddens fysiska konstruktion innefattar 3D-utskrivna ABS-komponenter med inkludering av lastceller för att mäta störningsmoment från de exciterade flexibla påhängen. Resultaten från valideringsexperiment visar att en enkel PID-regulator orsakar betydande excitation i de flexibla påhängena under en vridningsmanöver. Dock lyckades en input-formad attitydprofil som anpassats till de flexibla påhängenas naturliga frekvens framgångsrikt minska den uppmätta excitationen med 50%. Omvänt visade den kraftimpedansvågbaserade styrmetoden inte någon minskning i excitation, men visar potential för vidare utvecklingar i framtida arbete. Sammanfattningsvis har testbädden framgångsrikt uppnått sina fördefinierade projektmål, om än med behov av ytterligare förfining, särskilt i telemetrisystemet. Det rekommenderas att framtida arbete fokuserar på förbättring av telemetrisystemet och validering av en modellbaserad ansats till styrdesign.

Benefiting from the constant and significant advancement of wireless communication technologies and networking protocols, Wireless Ad hoc NETwork (WANET) has played a more and more important role in modern communication networks without relying much on existing infrastructures. The past decades have seen numerous applications adopting ad hoc networks for service provisioning. For example, Wireless Sensor Network (WSN) can be widely deployed for environment monitoring and object tracking by utilizing low-cost, low-power and multi-function sensor nodes. To realize such applications, the design and evaluation of communication protocols are of significant importance. Meanwhile, the network performance analysis based on mathematical models is also in great need of development and improvement. This dissertation investigates the above topics from three important and fundamental aspects, including data collection protocol design, protocol modeling and analysis, and physical interference modeling and analysis. The contributions of this dissertation are four-fold. First, this dissertation investigates the synchronization issue in the duty-cycled, pipelined-scheduling data collection of a WSN, based on which a pipelined data collection protocol, called PDC, is proposed. PDC takes into account both the pipelined data collection and the underlying schedule synchronization over duty-cycled radios practically and comprehensively. It integrates all its components in a natural and seamless way to simplify the protocol implementation and to achieve a high energy efficiency and low packet delivery latency. Based on PDC, an Adaptive Data Collection (ADC) protocol is further proposed to achieve dynamic duty-cycling and free addressing, which can improve network heterogeneity, load adaptivity, and energy efficiency. Both PDC and ADC have been implemented in a pioneer open-source operating system for the Internet of Things, and evaluated through a testbed built based on two hardware platforms, as well as through emulations. Second, Linear Sensor Network (LSN) has attracted increasing attention due to the vast requirements on the monitoring and surveillance of a structure or area with a linear topology. Being aware that, for LSN, there is few work on the network modeling and analysis based on a duty-cycled MAC protocol, this dissertation proposes a framework for modeling and analyzing a class of duty-cycled, multi-hop data collection protocols for LSNs. With the model, the dissertation thoroughly investigates the PDC performance in an LSN, considering both saturated and unsaturated scenarios, with and without retransmission. Extensive OPNET simulations have been carried out to validate the accuracy of the model. Third, in the design and modeling of PDC above, the transmission and interference ranges are defined for successful communications between a pair of nodes. It does not consider the cumulative interference from the transmitters which are out of the contention range of a receiver. Since most performance metrics in wireless networks, such as outage probability, link capacity, etc., are nonlinear functions of the distances among communicating, relaying, and interfering nodes, a physical interference model based on distance is definitely needed in quantifying these metrics. Such quantifications eventually involve the Nodal Distance Distribution (NDD) intrinsically depending on network coverage and nodal spatial distribution. By extending a tool in integral geometry and using decomposition and recursion, this dissertation proposes a systematic and algorithmic approach to obtaining the NDD between two nodes which are uniformly distributed at random in an arbitrarily-shaped network. Fourth, with the proposed approach to NDDs, the dissertation presents a physical interference model framework to analyze the cumulative interference and link outage probability for an LSN running the PDC protocol. The framework is further applied to analyze 2D networks, i.e., ad hoc Device-to-Device (D2D) communications underlaying cellular networks, where the cumulative interference and link outage probabilities for both cellular and D2D communications are thoroughly investigated. / Graduate / 0984 / 0544 / tong1987fei@163.com