Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-09-06T17:39:17Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DissertacaoDeMestrado-IrineuMoura-imlm2.pdf: 1240260 bytes, checksum: 4bbaf8839fa3d5be7fca586e1f290f68 (MD5) / Made available in DSpace on 2016-09-06T17:39:17Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DissertacaoDeMestrado-IrineuMoura-imlm2.pdf: 1240260 bytes, checksum: 4bbaf8839fa3d5be7fca586e1f290f68 (MD5) Previous issue date: 2015-08-24 / Energy consumption has been gaining traction as yet another major concern that mainstream software developers must be aware of. It used to be mainly the focus of hardware designers and low level software developers, e.g., device driver developers. Nowadays, however, mostly due to the ubiquity of battery-powered devices, any developer in the software stack must be prepared to deal with this concern. Thus, to be able to properly assist them and to provide guidance in future research it is crucial to understand how they have been handling this matter. This thesis aims to aid in this regard by exploring a set of software changes, i.e., commits, to obtain insights into actual solutions implemented by open source developers when dealing with energy consumption. We use as our main data source GITHUB, a source code hosting platform for collaborative development, and extract a sample of the available commits across several different projects. From this sample, we manually curate a set of energy-aware commits, that is, any commit that refers to a source code change where developers intentionally modify, or aim to modify, the energy consumption (or power dissipation) of a system or make it easier for other developers or end users to do so. We then apply a qualitative research method to extract recurring patterns of information and to group the commits that intend to save energy into categories. A small survey was also conducted to assess the quality of our analysis and to further expand our understanding of the changes. During our analysis we also cover different aspects of the commits. We observe that the majority of the changes (~47%) still target lower levels of the software stack, i.e., kernels, drivers and OS-related services, while application level changes encompass ~34% of them. We notice that developers may not always be certain of the energy consumption impact of their changes before actually performing them, among our dataset we identify several instances (~12%) of commits where developers show signs of uncertainty towards their change’s effectiveness. We also highlight the possible software quality attributes that may be favored over energy efficiency. Notably, we spot a few instances of commits where developers performed a change that would negatively impact the energy consumption of the system in order to fix a bug. It is also worth noting, we draw attention to a specific group of changes which we call "energy-aware interfaces". They add tuning knobs that can be used by developers or end users to control the energy consumption of an underlying component. / O controle do consumo de energia tem ganhado cada vez mais atenção como outro tipo de interesse ao qual desenvolvedores de software devem estar atentos. Antes esse tipo de preocupação era principalmente o foco de designers de hardware e desenvolvedores de baixonível, como por exemplo, desenvolvedores de drivers de dispositivos. Entretanto, devido à ubiquidade de dispositivos dependentes de bateria, qualquer desenvolvedor deve estar preparado para enfrentar essa questão. Logo, entender como eles estão lidando com o consumo de energia é crucial para estarmos aptos a auxiliá-los e para prover uma direção adequada para pesquisas futuras. Com o intuito de ajudar nesse sentido, essa tese explora um conjunto de mudanças de software, isto é, commits, para entender melhor sobre os tipos de soluções que são implementadas de fato por desenvolvedores de código aberto quando os mesmos devem lidar com o consumo de energia. Nós utilizamos o GITHUB como nossa principal fonte de dados, uma plataforma de hospedagem de código fonte para o desenvolvimento colaborativo de projetos de software, e extraímos uma amostra dos commits disponíveis entre vários projetos diferentes. Dessa amostra, nós manualmente selecionamos um conjunto de commits "energy-aware", isto é, qualquer commit que se refere a uma modificação de código onde o desenvolvedor propositalmente modifica, ou intenciona modificar, o consumo de energia (ou a dissipação de potência) de um sistema ou torna mais fácil para que outros desenvolvedores ou usuários finais possam fazê-lo. Nós então aplicamos sobre esses commits um método de análise qualitativa para extrair padrões recorrentes de informação e para agrupar os commits que intencionam reduzir o consumo energético em categorias. Uma pequena pesquisa também foi realizada com os autores dos commits para avaliar a qualidade da nossa análise e para expandir nosso entendimento sobre as modificações. Nós também consideramos diferentes aspectos dos commits durante a análise. Observamos que a maioria das modificações (~47%) ainda se aplicam às mais baixas camadas de software, isto é, kernels e drivers, enquanto que mudanças a nível de aplicação compreendem ~34% do nosso conjunto de dados. Nós notamos que os desenvolvedores nem sempre estão seguros do impacto de suas modificações no consumo de energia antes de realizá-las, em nosso conjunto de dados identificamos várias instâncias de modificações (~12%) em que os desenvolvedores demonstram sinais de incerteza em relação à eficácia de suas mudanças. Também apontamos alguns dos possíveis atributos de qualidade de software que são favorecidos em detrimento do consumo de energia. Entre essas, destacamos alguns commits onde os desenvolvedores realizaram uma modificação que impactaria negativamente no consumo de energia com o intuito de consertar algum problema existente no software. Também achamos interessante ressaltar um grupo específico de modificações que chamamos de “interfaces energy-aware”. Elas adicionam controles no software em questão que possibilitam outros desenvolvedores ou usuários finais a ajustar o consumo de energia de algum componente subjacente.

This research is related to the control of energy consumption and efficiency in building Heating Ventilation and Air Conditioning (HVAC) systems and is primarily concerned with controlling the function of heating. The main goal of this thesis is to develop a control system that can achieve the following two main control functions: a) detection of unexpected indoor conditions that may result in unnecessary power consumption and b) energy efficiency control regarding optimal balancing of two parameters: the required energy consumption for heating, versus thermal comfort of the occupants. Methods of both orientations were developed in a multi-zone space composed of nine zones where each zone is equipped with a wireless node consisting of temperature and occupancy sensors while all the scattered nodes together form a wireless sensor network (WSN). The main methods of both control functions utilize the potential of the deterministic subspace identification (SID) predictive model which provides the predicted temperature of the zones. In the main method for detecting unexpected situations that can directly affect the thermal condition of the indoor space and cause energy consumption (abnormal situations), the predictive temperature from the SID model is compared with the real temperature and thus possible temperature deviations that indicate unexpected situations are detected. The method successfully detects two situations: the high infiltration gain due to unexpected cold air intake from the external surroundings through potential unforeseen openings (windows, exterior doors, opened ceilings etc) as well as the high heat gain due to onset of fire. With the support of the statistical algorithm for abrupt change detection, Cumulative Sum (CUSUM), the detection of temperature deviations is accomplished with accuracy in a very short time. The CUSUM algorithm is first evaluated at an initial approach to detect power diversions due to the above situations caused by the aforementioned exogenous factors. The predicted temperature of the zone from the SID model utilized appropriately also by the main method of the second control function for energy efficiency control. The time needed for the temperature of a zone to reach the thermal comfort zone threshold from a low initial value is measured by the predicted temperature evolution, and this measurement bases the logic of a control criterion for applying proactive heating to the unoccupied zones or not. Additional key points for the control criterion of the method is the occupation time of the zones as well as the remaining time of the occupants in the occupied zones. Two scenarios are examined: the first scenario with two adjacent zones where the one is occupied and the other is not, and the second scenario with a multi-zone space where the occupants are moving through the zones in a cascade mode. Gama and Pareto probability distributions modeled the occupation times of the two-zone scenario while exponential distribution modeled the cascade scenario as the least favorable case. The mobility of the occupants modeled with a semi-Markov process and the method provides satisfactory and reasonable results. At an initial approach the proactive heating of the zones is evaluated with specific algorithms that handle appropriately the occupation time into the zones.

Context-aware computing envisions a new generation of smart applications that have the ability to perpetually sense the user’s context and use these data to make adaptation decision in response to changes in the user’s context so as to provide timely and personalized services anytime and anywhere. Unlike the traditional distribution systems where the network topology is fixed and wired, context-aware computing systems are mostly based on wireless communication due to the mobility of the network nodes; hence the network topology is not fixed but changes dynamically in an unpredictable manner as nodes join and the leave network, in addition to the fact that wireless communication is unstable. These factors make the design and development of context-aware computing systems much more challenging, as the system requirements change depending on the context of use. The Unified Modelling Language (UML) is a graphical language commonly used to specify, visualize, construct, and document the artefacts of software-intensive systems. However, UML is an all-purpose modelling language and does not have notations to distinguish context-awareness requirements from other system requirements. This is critical for the specification, visualization, construction and documentation of context-aware computing systems because context-awareness requirements are highly important in these systems. This thesis proposes an extension of UML diagrams to cater for the specification, visualization, construction and documentation of context-aware computing systems where new notations are introduced to model context-awareness requirements distinctively from other system requirements. The contributions of this work can be summarized as follows: (i) A context-aware use case diagram is a new notion which merges into a single diagram the traditional use case diagram (that describes the functions of an application) and the use context diagram, which specifies the context information upon which the behaviours of these functions depend. (ii) A Novel notion known as a context-aware activity diagram is presented, which extends the traditional UML activity diagrams to enable the representation of context objects, context constraints and adaptation activities. Context constraints express conditions upon context object attributes that trigger adaptation activities; adaptation activities are activities that must be performed in response to specific changes in the system’s context. (iii) A novel notion known as the context-aware class diagram is presented, which extends the traditional UML class diagrams to enable the representation of context information that affect the behaviours of a class. A new relationship, called utilisation, between a UML class and a context class is used to model context objects; meaning that the behaviours of the UML class depend upon the context information represented by the context class. Hence a context-aware class diagram is a rich and expressive language that distinctively depicts both the structure of classes and that of the contexts upon which they depend. The pragmatics of the proposed approach are demonstrated using two real-world case studies.

Context. Gaze based interaction in video games is still a developing field, and is mostly used as an off-line evaluation tool or a replacement for traditional input methods. This thesis will look closer at the prospect of using eye tracking as an additional input to be used alongside the traditional methods of input to improve the immersion and performance of the player. Objectives. To implement a gaze based interaction method into arst person adventure in a way to improve player performance and immersion. Method. Using the Tobii REX eye tracker, 18 volunteers participated in an experiment. They played two versions of a game in an controlled environment. The versions had the same mechanics and game elements but only one of them had eye tracking implemented. After the experiment the participants answered nine questions about which prototype they preferred. Results. All participants' scores were in all cases but one, lower when using the eye tracking input method, compared to the traditional one.The time it took for the participants to complete the game was longer for everybody. 16 out of 18 players also felt more immersed in the game while using eye tracking compared to playing with the traditional input method. Conclusions. The results from the experiments provided evidence that the interaction method designed for this thesis did not improve player performance. The results also showed that the interaction method did improve immersion for most players.

We have simulated the effect of different parameters in location-aware information sharing policies for crowd-based information exchange systems. The purpose of this simulation was to find out which parameters improved the upload time, battery life and success rate for nodes trying to upload a large file under bad conditions. To test the effect of these parameters on a larger scale, we simulated an area where a large number of nodes were moving around. Our test results showed that nodes greatly improved their battery life and the upload time by limiting the number of nodes they send data to, rather than sharing data with all nodes within reach. However, sending the oldest collected data performed very bad in regards of battery life time and had a relatively high amount of nodes that did not manage to upload their file. We concluded that nodes should not share their data with all available nodes at all times, and be restrictive in the amount of data they share with other nodes to conserve battery.

Different computation problem domains such as sorting, matrix multiplication, etc. usually require different data representations and algorithms variants implementations in order to be adapted and re-designed to context-aware composition (CAC). Context-aware composition is a technique for the design of applications that can adapt its behavior according to changes in the program. We considered two application domains: matrix multiplication and graph algorithms (DFS algorithm in particular). The main problem in the implementation of the representation mechanisms applied in these problem domains is time spent on the data representation conversion that in the end should not influence the application performance.        This thesis work presents a flexible aspect-based architecture that includes the data structure representation adaptation in order to reduce implementation efforts required for adaptation different application domains.      Although, manual approach has small overhead 4-10% for different problems compared to the AOP-based approach, experiments show that the manual adaptation to CAC requires on average three times more programming effort in terms of lines of code than AOP-based approach. Moreover, the AOP-based approach showed the average speed-up over baseline algorithms that use standard data structures of 2.1.

As more robots and sensors are deployed in work and home environments, there is a growing need for these devices to act with some degree of autonomy to fulfill their purpose. Automated planning can be used to synthesize plans of action that achieve this. The main challenge addressed in this thesis is to consider how the automated planning problem changes when considered in the context of environments that are populated by humans. Humans have their own plans, and automatically generated plans should not interfere with these. We refer to this as social acceptability. Opportunities for proactive behavior often arise during execution. The planner should be able to identify these opportunities and proactively plan accordingly. Both social acceptability and proactivity require the planner to identify relevant situations from available information. We refer to this capability as context-awareness, and it may require complex inferences based on observed human activities. Finally, planning may have to consider cooperation with humans to reach common goals or to enable robots and humans to support one another. This thesis analyzes the requirements that emerge from human-aware planning — what it takes to make automated planning socially acceptable, proactive, context aware, and to make it support cooperation with humans. We formally state the human-aware planning problem, and propose a planning and execution framework for human-aware planning that is based on constraint reasoning and flaw-resolution techniques, and which fulfills the identified requirements. This approach is modular and extendable: new types of constraints can be added and solvers can be exchanged and re-arranged. This allows us to address the identified requirements for humanaware planning. In particular, we introduce Interaction Constraints (ICs) for this purpose, and propose patterns of Ics for social acceptability, proactivity, and contextawareness. We also consider cooperative plans in which certain actions are assigned to humans and the implications that this has. We evaluate the proposed methods and patterns on a series of use cases, as well as a variety of domains including a real-world robotic system. We evaluate the proposed methods and patterns on a series of use cases, as well as a variety of domains including a real-world robotic system. introduce Interaction Constraints (ICs) for this purpose, and propose patterns of ICs for social acceptability, proactivity, and context-awareness. We also consider cooperative plans in which certain actions are assigned to humans and the implications that this has. We evaluate the proposed methods and patterns on a series of use cases, as well as a variety of domains including a real-world robotic system.

Abstract The development of mobile and ubiquitous computing has recently been rapid. One of the most promising research and development fields has been location-aware services. These services are challenging as they require a lot of resources for generating maps from spatial data and for visualizing temporary data gathered from the environment. Applying location-awareness and ubiquitous computing in the industry is currently under intensive research and development activities especially because of signs of promising new business opportunities. This thesis studies the development and evaluation of a location-aware system platform called Locawe designed for indoor and outdoor conditions. This decentralized middleware-based platform has been developed at CENTRIA Research and Development, Ylivieska. The main objectives of this research have been primarily to study and develop new ubiquitous features for the Locawe platform with various software and hardware combinations. In addition, during these studies gathered experiences have been used in order to design new versions of the Locawe architecture. These ubiquitous features, covering the use of GPS, RFID and WSAN technologies, have been tested in five field experiments, one laboratory experiment and several industrial pilots. In these evaluations, the author has considered what software and hardware alternatives are feasible and appropriate for improving the newly developed features in the Locawe platform. These features have been evaluated from usability, visualization and communication techniques perspective. As a result the author presents in this thesis main characteristics in location-aware system development from system layers, ubiquitous computing, mobility, and restrictions perspective. The author also suggests that the architeture presented in this thesis enables location-aware system development in indoor and outdoor conditions. With respect of state-of-the-art platforms, the Locawe platform is, at the moment, in some sense unique, although only as a research prototype. This platform combines two approaches, namely research on location platforms, and research on geosensor networks or smart environments. In addition, this platform gives one answer how RFID or WSAN technologies could be integrated under one framework together with mobile devices. Finally, the author also proposes that the research and development approach presented in this thesis can be applied successfully in research and development organizations specialized in applied research. / Tiivistelmä Mobiilin ja sulautetun tietotekniikan kehitys on ollut viime aikoina nopeaa. Yksi lupaavimmista tutkimus- ja kehityskohteista on ollut paikkatietoiset palvelut. Näiden palveluiden kehittäminen on varsin haasteellista, koska kehittämistyö vaatii runsaasti resursseja sekä karttojen generoimisessa paikkatietoaineistoista että ympäristöstä kerättävän väliaikaisen tiedon visualisoinnissa. Paikkatietoisten sovellusten ja sulautetun tietotekniikan soveltaminen teollisuudessa on aktiivisen tutkimus- ja kehittämistoiminnan keskiössä, koska näköpiirissä on selvästi uusia lupaavia liiketoimintamahdollisuuksia. Tässä väitöskirjassa keskitytään Locawe-nimisen paikkatietoisen ohjelmistoalustan kehittämisen ja arvioinnin raportointiin. Locawe-alusta on suunniteltu sekä sisä- että ulko-olosuhteisiin. Tämä hajautettu väliohjelmistopohjainen alusta on kehitetty CENTRIA Tutkimus ja kehityksen Ylivieskan yksikössä. Väitöskirjan tavoitteena on ollut ensisijaisesti tutkia ja kehittää uusia, sulautettua tietotekniikkaa hyödyntäviä ominaisuuksia Locawe-alustaan hyödyntäen erilaisia ohjelmisto- ja laitteistokombinaatioita. Väitöskirjaan liittyvän tutkimustyön aikana käyttäjiltä on useaan otteeseen kerätty käyttökokemuksia. Kokemuksia on hyödynnetty Locawe-arkkitehtuurin seuraavien versioiden suunnittelussa. Uusia, sulautettua tietotekniikkaa hyödyntäviä ominaisuuksia on testattu kaikkiaan viidessä kenttätestissä, yhdessä laboratoriotestissä sekä useissa teollisissa piloteissa. Ominaisuuksien toteuttamisessa käytettiin GPS-, RFID- ja WSAN-teknologioita. Testeissä kirjoittaja arvioi, minkälaiset ohjelmisto- ja laitteistovaihtoehdot ovat toteuttamiskelpoisimpia ja soveliaimpia uusien ominaisuuksien kehittämiseksi Locawe-alustaan. Ominaisuuksia on arvioitu käytettävyyden, visualisoinnin ja viestintätekniikoiden näkökulmista. Tutkimustyön tuloksena kirjoittaja esittelee väitöskirjassa paikkatietoisten järjestelmien kehittämiseen liittyviä ominaispiirteitä järjestelmätasojen, sulautetun tietotekniikan, mobiliteetin ja rajoitteiden näkökulmista. Lisäksi kirjoittaja esittää väitöskirjassa arkkitehtuurin, joka mahdollistaa paikkatietoisen järjestelmän kehittämisen soveltuen niin sisä- kuin ulko-olosuhteisiin. Huomioiden paikkatietoisten alustojen tason maailmanlaajuisesti väitöskirjassa kuvattu Locawe-alusta on tutkimusprototyyppinäkin tällä hetkellä tietyssä määrin ainutlaatuinen. Alustan tutkimisessa on nimittäin keskitytty sekä paikkatietoisten alustojen että geosensoriverkkojen ja älykkäiden ympäristöjen tutkimiseen. Lisäksi Locawe-alusta tarjoaa yhden ratkaisun RFID ja WSAN teknologioiden integrointiin yhdeksi kehykseksi yhdessä mobiililaitteiden kanssa. Lopuksi kirjoittaja esittää, että väitöskirjassa esitetty tutkimus- ja kehittämistoiminnan lähestymistapaa voidaan soveltaa vastaavissa tutkimusorganisaatioissa kuin CENTRIA.

There are still many challenges in the field of VANETs that encouraged researchers to conduct further investigation in this field to meet these challenges. The issue pertaining to routing protocols such as delivering the warning messages to the vehicles facing Non-Line of Sight (NLOS) situations without causing the storm problem and channel contention, is regarded as a serious dilemma which is required to be tackled in VANET, especially in congested environments. This requires the designing of an efficient mechanism of routing protocol that can broadcast the warning messages from the emergency vehicles to the vehicles under NLOS, reducing the overhead and increasing the packet delivery ratio with a reduced time delay and channel utilisation. The main aim of this work is to develop the novel routing protocol for a high-density environment in VANET through utilisation of its high mobility features, aid of the sensors such as Global Positioning System (GPS) and Navigation System (NS). In this work, the cooperative approach has been used to develop the routing protocol called the Co-operative Volunteer Protocol (CVP), which uses volunteer vehicles to disseminate the warning message from the source to the target vehicle under NLOS issue; this also increases the packet delivery ratio, detection of NLOS and resolution of NLOS by delivering the warning message successfully to the vehicle under NLOS, thereby causing a direct impact on the reduction of collisions between vehicles in normal mode and emergency mode on the road near intersections or on highways. The cooperative approach adopted for warning message dissemination reduced the rebroadcast rate of messages, thereby decreasing significantly the storm issue and the channel contention. A novel architecture has been developed by utilising the concept of a Context-Aware System (CAS), which clarifies the OBU components and their interaction with each other in order to collect data and take the decisions based on the sensed circumstances. The proposed architecture has been divided into three main phases: sensing, processing and acting. The results obtained from the validation of the proposed CVP protocol using the simulator EstiNet under specific conditions and parameters showed that performance of the proposed protocol is better than that of the GRANT protocol with regard to several metrics such as packet delivery ratio, neighbourhood awareness, channel utilisation, overhead and latency. It is also successfully shown that the proposed CVP could detect the NLOS situation and solves it effectively and efficiently for both the intersection scenario in urban areas and the highway scenario.

Fueled by increasing human appetite for high computing performance, semiconductor technology has now marched into the deep sub-micron era. As transistor size keeps shrinking, more and more transistors are integrated into a single chip. This has increased tremendously the power consumption and heat generation of IC chips. The rapidly growing heat dissipation greatly increases the packaging/cooling costs, and adversely affects the performance and reliability of a computing system. In addition, it also reduces the processor's life span and may even crash the entire computing system. Therefore, dynamic thermal management (DTM) is becoming a critical problem in modern computer system design. Extensive theoretical research has been conducted to study the DTM problem. However, most of them are based on theoretically idealized assumptions or simplified models. While these models and assumptions help to greatly simplify a complex problem and make it theoretically manageable, practical computer systems and applications must deal with many practical factors and details beyond these models or assumptions. The goal of our research was to develop a test platform that can be used to validate theoretical results on DTM under well-controlled conditions, to identify the limitations of existing theoretical results, and also to develop new and practical DTM techniques. This dissertation details the background and our research efforts in this endeavor. Specifically, in our research, we first developed a customized test platform based on an Intel desktop. We then tested a number of related theoretical works and examined their limitations under the practical hardware environment. With these limitations in mind, we developed a new reactive thermal management algorithm for single-core computing systems to optimize the throughput under a peak temperature constraint. We further extended our research to a multicore platform and developed an effective proactive DTM technique for throughput maximization on multicore processor based on task migration and dynamic voltage frequency scaling technique. The significance of our research lies in the fact that our research complements the current extensive theoretical research in dealing with increasingly critical thermal problems and enabling the continuous evolution of high performance computing systems.