Tecniche per il controllo dinamico del consumo di potenza per piattaforme system-on-chip

Providing support for multimedia applications on low-power mobile devices remains a significant research challenge. This is primarily due to two reasons: • Portable mobile devices have modest sizes and weights, and therefore inadequate resources, low CPU processing power, reduced display capabilities, limited memory and battery lifetimes as compared to desktop and laptop systems. • On the other hand, multimedia applications tend to have distinctive QoS and processing requirementswhichmake themextremely resource-demanding. This innate conflict introduces key research challenges in the design of multimedia applications and device-level power optimization. Energy efficiency in this kind of platforms can be achieved only via a synergistic hardware and software approach. In fact, while System-on-Chips are more and more programmable thus providing functional flexibility, hardwareonly power reduction techniques cannot maintain consumption under acceptable bounds. It is well understood both in research and industry that system configuration andmanagement cannot be controlled efficiently only relying on low-level firmware and hardware drivers. In fact, at this level there is lack of information about user application activity and consequently about the impact of power management decision on QoS. Even though operating system support and integration is a requirement for effective performance and energy management, more effective and QoSsensitive power management is possible if power awareness and hardware configuration control strategies are tightly integratedwith domain-specificmiddleware services. The main objective of this PhD research has been the exploration and the integration of amiddleware-centric energymanagement with applications and operating-system. We choose to focus on the CPU-memory and the video subsystems, since they are the most power-hungry components of an embedded system. A second main objective has been the definition and implementation of software facilities (like toolkits, API, and run-time engines) in order to improve programmability and performance efficiency of such platforms. Enhancing energy efficiency and programmability ofmodernMulti-Processor System-on-Chips (MPSoCs) Consumer applications are characterized by tight time-to-market constraints and extreme cost sensitivity. The software that runs on modern embedded systems must be high performance, real time, and even more important low power. Although much progress has been made on these problems, much remains to be done. Multi-processor System-on-Chip (MPSoC) are increasingly popular platforms for high performance embedded applications. This leads to interesting challenges in software development since efficient software development is a major issue for MPSoc designers. An important step in deploying applications on multiprocessors is to allocate and schedule concurrent tasks to the processing and communication resources of the platform. The problem of allocating and scheduling precedenceconstrained tasks on processors in a distributed real-time system is NP-hard. There is a clear need for deployment technology that addresses thesemulti processing issues. This problem can be tackled by means of specific middleware which takes care of allocating and scheduling tasks on the different processing elements and which tries also to optimize the power consumption of the entire multiprocessor platform. This dissertation is an attempt to develop insight into efficient, flexible and optimalmethods for allocating and scheduling concurrent applications tomultiprocessor architectures. It is a well-known problem in literature: this kind of optimization problems are very complex even in much simplified variants, therefore most authors propose simplified models and heuristic approaches to solve it in reasonable time. Model simplification is often achieved by abstracting away platform implementation ”details”. As a result, optimization problems become more tractable, even reaching polynomial time complexity. Unfortunately, this approach creates an abstraction gap between the optimization model and the real HW-SW platform. The main issue with heuristic or, more in general, with incomplete search is that they introduce an optimality gap of unknown size. They provide very limited or no information on the distance between the best computed solution and the optimal one. The goal of this work is to address both abstraction and optimality gaps, formulating accurate models which accounts for a number of ”non-idealities” in real-life hardware platforms, developing novel mapping algorithms that deterministically find optimal solutions, and implementing software infrastructures required by developers to deploy applications for the targetMPSoC platforms. Energy Efficient LCDBacklightAutoregulation on Real-LifeMultimediaAp- plication Processor Despite the ever increasing advances in Liquid Crystal Display’s (LCD) technology, their power consumption is still one of the major limitations to the battery life of mobile appliances such as smart phones, portable media players, gaming and navigation devices. There is a clear trend towards the increase of LCD size to exploit the multimedia capabilities of portable devices that can receive and render high definition video and pictures. Multimedia applications running on these devices require LCD screen sizes of 2.2 to 3.5 inches andmore to display video sequences and pictures with the required quality. LCD power consumption is dependent on the backlight and pixel matrix driving circuits and is typically proportional to the panel area. As a result, the contribution is also likely to be considerable in future mobile appliances. To address this issue, companies are proposing low power technologies suitable for mobile applications supporting low power states and image control techniques. On the research side, several power saving schemes and algorithms can be found in literature. Some of them exploit software-only techniques to change the image content to reduce the power associated with the crystal polarization, some others are aimed at decreasing the backlight level while compensating the luminance reduction by compensating the user perceived quality degradation using pixel-by-pixel image processing algorithms. The major limitation of these techniques is that they rely on the CPU to perform pixel-based manipulations and their impact on CPU utilization and power consumption has not been assessed. This PhDdissertation shows an alternative approach that exploits in a smart and efficient way the hardware image processing unit almost integrated in every current multimedia application processors to implement a hardware assisted image compensation that allows dynamic scaling of the backlight with a negligible impact on QoS. The proposed approach overcomes CPU-intensive techniques by saving system power without requiring either a dedicated display technology or hardware modification. Thesis Overview The remainder of the thesis is organized as follows. The first part is focused on enhancing energy efficiency and programmability of modern Multi-Processor System-on-Chips (MPSoCs). Chapter 2 gives an overview about architectural trends in embedded systems, illustrating the principal features of new technologies and the key challenges still open. Chapter 3 presents a QoS-driven methodology for optimal allocation and frequency selection for MPSoCs. The methodology is based on functional simulation and full system power estimation. Chapter 4 targets allocation and scheduling of pipelined stream-oriented applications on top of distributed memory architectures with messaging support. We tackled the complexity of the problem by means of decomposition and no-good generation, and prove the increased computational efficiency of this approach with respect to traditional ones. Chapter 5 presents a cooperative framework to solve the allocation, scheduling and voltage/frequency selection problem to optimality for energyefficient MPSoCs, while in Chapter 6 applications with conditional task graph are taken into account. Finally Chapter 7 proposes a complete framework, called Cellflow, to help programmers in efficient software implementation on a real architecture, the Cell Broadband Engine processor. The second part is focused on energy efficient software techniques for LCD displays. Chapter 8 gives an overview about portable device display technologies, illustrating the principal features of LCD video systems and the key challenges still open. Chapter 9 shows several energy efficient software techniques present in literature, while Chapter 10 illustrates in details our method for saving significant power in an LCD panel. Finally, conclusions are drawn, reporting the main research contributions that have been discussed throughout this dissertation.

Video transmission over wireless channel

This work has been realized by the author in his PhD course in Electrical, Computer Science and Telecommunication at the University of Bologna, Faculty of Engineering, Italy. All the documentation here reported is a summary of years of work, under the supervision of Prof. Oreste Andrisano, coordinator of Wireless Communication Laboratory - WiLab, in Bologna. The subject of this thesis is the transmission of video in a context of heterogeneous network, and in particular, using a wireless channel. All the instrumentation that has been used for the characterization of the telecommunication systems belongs to CNR (National Research Council), CNIT (Italian Inter- University Center), and DEIS (Dept. of Electrical, Computer Science, and Systems). From November 2009 to July 2010, the author spent his time abroad, working in collaboration with DLR - German Aerospace Center in Munich, Germany, on channel coding area, developing a general purpose decoder machine to decode a huge family of iterative codes. A patent concerning Doubly Generalized-Low Density Parity Check codes has been produced by the author as well as some important scientic papers, published on IEEE journals and conferences.

Analysis of human body kinematics using a hybrid markerless video acquisition and processing

A main objective of the human movement analysis is the quantitative description of joint kinematics and kinetics. This information may have great possibility to address clinical problems both in orthopaedics and motor rehabilitation. Previous studies have shown that the assessment of kinematics and kinetics from stereophotogrammetric data necessitates a setup phase, special equipment and expertise to operate. Besides, this procedure may cause feeling of uneasiness on the subjects and may hinder with their walking. The general aim of this thesis is the implementation and evaluation of new 2D markerless techniques, in order to contribute to the development of an alternative technique to the traditional stereophotogrammetric techniques. At first, the focus of the study has been the estimation of the ankle-foot complex kinematics during stance phase of the gait. Two particular cases were considered: subjects barefoot and subjects wearing ankle socks. The use of socks was investigated in view of the development of the hybrid method proposed in this work. Different algorithms were analyzed, evaluated and implemented in order to have a 2D markerless solution to estimate the kinematics for both cases. The validation of the proposed technique was done with a traditional stereophotogrammetric system. The implementation of the technique leads towards an easy to configure (and more comfortable for the subject) alternative to the traditional stereophotogrammetric system. Then, the abovementioned technique has been improved so that the measurement of knee flexion/extension could be done with a 2D markerless technique. The main changes on the implementation were on occlusion handling and background segmentation. With the additional constraints, the proposed technique was applied to the estimation of knee flexion/extension and compared with a traditional stereophotogrammetric system. Results showed that the knee flexion/extension estimation from traditional stereophotogrammetric system and the proposed markerless system were highly comparable, making the latter a potential alternative for clinical use. A contribution has also been given in the estimation of lower limb kinematics of the children with cerebral palsy (CP). For this purpose, a hybrid technique, which uses high-cut underwear and ankle socks as “segmental markers” in combination with a markerless methodology, was proposed. The proposed hybrid technique is different than the abovementioned markerless technique in terms of the algorithm chosen. Results showed that the proposed hybrid technique can become a simple and low-cost alternative to the traditional stereophotogrammetric systems.

The influence of career histories on team perfomance in new product development: a study of the video game industry

The purpose of this research is to contribute to the literature on organizational demography and new product development by investigating how diverse individual career histories impact team performance. Moreover we highlighted the importance of considering also the institutional context and the specific labour market arrangements in which a team is embedded, in order to interpret correctly the effect of career-related diversity measures on performance. The empirical setting of the study is the videogame industry, and the teams in charge of the development of new game titles. Video games development teams are the ideal setting to investigate the influence of career histories on team performance, since the development of videogames is performed by multidisciplinary teams composed by specialists with a wide variety of technical and artistic backgrounds, who execute a significant amounts of creative thinking. We investigate our research question both with quantitative methods and with a case study on the Japanese videogame industry: one of the most innovative in this sector. Our results show how career histories in terms of occupational diversity, prior functional diversity and prior product diversity, usually have a positive influence on team performance. However, when the moderating effect of the institutional setting is taken in to account, career diversity has different or even opposite effect on team performance, according to the specific national context in which a team operates.

Resa diagnostica di anamnesi, EEG intercritico ed home-made video negli episodi parossistici notturni: confronto con la VEPSG

Poiché la diagnosi differenziale degli episodi parossistici notturni è affidata alla VEPSG, tenendo conto dei limiti di tale metodica, il progetto attuale ha lo scopo di definire la resa diagnostica di strumenti alternativi alla VEPSG: anamnesi, home-made video ed EEG intercritico. Sono stati reclutati consecutivamente 13 pazienti, afferiti al nostro Dipartimento per episodi parossistici notturni. Ciascun paziente è stato sottoposto ad un protocollo diagnostico standardizzato. A 5 Medici Esperti in Epilessia e Medicina del Sonno è stato chiesto di formulare un orientamento diagnostico sulla base di anamnesi, EEG intercritico, home-made video e VEPSG. Attraverso l’elaborazione degli orientamenti diagnostici è stata calcolata la resa diagnostica delle procedure esaminate, a confronto con la VEPSG, attraverso il concetto di “accuratezza diagnostica”. Per 6 pazienti è stato possibile porre una diagnosi di Epilessia Frontale Notturna, per 2 di parasonnia, in 5 la diagnosi è rimasta dubbia. L’accuratezza diagnostica di ciascuna procedura è risultata moderata, con lievi differenze tra le diverse procedure (61.5% anamnesi; 66% home-made video; 69,2 % EEG intercritico). E’ essenziale migliorare ulteriormente l’accuratezza diagnostica di anamnesi, EEG intercritico ed home-made video, che possono risultare cruciali nei casi in cui la diagnosi non è certa o quando la VEPSG non è disponibile.

Riabilitazione e valutazione di pazienti con deficit neurologici mediante l'utilizzo di realtà virtuale, feedback aumentati, sensori inerziali e tecnologie video a basso costo.

La neuroriabilitazione è un processo attraverso cui individui affetti da patologie neurologiche mirano al conseguimento di un recupero completo o alla realizzazione del loro potenziale ottimale benessere fisico, mentale e sociale. Elementi essenziali per una riabilitazione efficace sono: una valutazione clinica da parte di un team multidisciplinare, un programma riabilitativo mirato e la valutazione dei risultati conseguiti mediante misure scientifiche e clinicamente appropriate. Obiettivo principale di questa tesi è stato sviluppare metodi e strumenti quantitativi per il trattamento e la valutazione motoria di pazienti neurologici. I trattamenti riabilitativi convenzionali richiedono a pazienti neurologici l’esecuzione di esercizi ripetitivi, diminuendo la loro motivazione. La realtà virtuale e i feedback sono in grado di coinvolgerli nel trattamento, permettendo ripetibilità e standardizzazione dei protocolli. È stato sviluppato e valutato uno strumento basato su feedback aumentati per il controllo del tronco. Inoltre, la realtà virtuale permette l’individualizzare il trattamento in base alle esigenze del paziente. Un’applicazione virtuale per la riabilitazione del cammino è stata sviluppata e testata durante un training su pazienti di sclerosi multipla, valutandone fattibilità e accettazione e dimostrando l'efficacia del trattamento. La valutazione quantitativa delle capacità motorie dei pazienti viene effettuata utilizzando sistemi di motion capture. Essendo il loro uso nella pratica clinica limitato, una metodologia per valutare l’oscillazione delle braccia in soggetti parkinsoniani basata su sensori inerziali è stata proposta. Questi sono piccoli, accurati e flessibili ma accumulano errori durante lunghe misurazioni. È stato affrontato questo problema e i risultati suggeriscono che, se il sensore è sul piede e le accelerazioni sono integrate iniziando dalla fase di mid stance, l’errore e le sue conseguenze nella determinazione dei parametri spaziali sono contenuti. Infine, è stata presentata una validazione del Kinect per il tracking del cammino in ambiente virtuale. Risultati preliminari consentono di definire il campo di utilizzo del sensore in riabilitazione.

La fotografia, il film e il video nella Land art tra documentazione e sperimentazione

La tesi affronta il ruolo problematico della documentazione nella Land art, sia per quanto riguarda l’immagine diffusa dai magazine e dalle riviste d’arte, sia affrontando nello specifico il rapporto con i media nella poetica degli artisti, dedicando particolare attenzione a De Maria, Heizer, Oppenheim, Smithson, Holt, Dibbets, Long, Fulton e Christo e Jeanne-Claude.

Tecnica, stile e ideologia nella musica sinfonica in video: la Quinta Sinfonia di Beethoven

Oggetto di questo lavoro è un’analisi dettagliata di un campione ristretto di riprese televisive della Quinta Sinfonia di Beethoven, con l’obiettivo di far emergere il loro meccanismo costruttivo, in senso sia tecnico sia culturale. Premessa dell’indagine è che ciascuna ripresa sia frutto di un’autorialità specifica che si sovrappone alle due già presenti in ogni esecuzione della Quinta Sinfonia, quella del compositore e quella dell’interprete, definita perciò «terza autorialità» riassumendo nella nozione la somma di contributi specifici che portano alla produzione di una ripresa (consulente musicale, regista, operatori di ripresa). La ricerca esamina i rapporti che volta a volta si stabiliscono fra i tre diversi piani autoriali, ma non mira a una ricostruzione filologica: l’obiettivo non è ricostruire le intenzioni dell’autore materiale quanto di far emergere dall’esame della registrazione della ripresa, così com’è data a noi oggi (spesso in una versione già più volte rimediata, in genere sotto forma di dvd commercializzato), scelte tecniche, musicali e culturali che potevano anche essere inconsapevoli. L’analisi dettagliata delle riprese conferma l’ipotesi di partenza che ci sia una sorta di sistema convenzionale, quasi una «solita forma» o approccio standardizzato, che sottende la gran parte delle riprese; gli elementi che si possono definire convenzionali, sia per la presenza sia per la modalità di trattamento, sono diversi, ma sono soprattutto due gli aspetti che sembrano esserne costitutivi: il legame con il rito del concerto, che viene rispettato e reincarnato televisivamente, con la costruzione di una propria, specifica aura; e la presenza di un paradigma implicito e sostanzialmente ineludibile che pone la maggior parte delle riprese televisive entro l’alveo della concezione della musica classica come musica pura, astratta, che deve essere compresa nei suoi propri termini.