The evolution of the Graphics Processing Units (GPUs) over the last decade, has reinforced general purpose computing while sustaining a steady performance growth in graphics intensive applications. However, the immense performance improvement is generally associated with a steep rise in GPU power consumption. Consequently, GPUs are already close to the abominable power wall. With a massive popularity of the mobile devices running general-purpose GPU (GPGPU) applications, it is of utmost importance to ensure a high energy efficiency, while meeting the strict performance requirements. In this work, we demonstrate that, customizing a Streaming Multiprocessor (SM) of a GPU, at a lower frequency, is significantly more energy efficient, compared to employing Dynamic Voltage and Frequency Scaling (DVFS) on an SM, designed for a high frequency operation. Using a system level Computer Aided Design (CAD) technique, we propose SSAGA - Streaming Multiprocessors Sculpted for Asymmetric GPGPU Applications, an energy efficient GPU design paradigm. SSAGA creates architecturally identical SM cores, customized for different voltage-frequency domains.

Ad hoc networks have gained significant importance and gathered huge momentum within the wireless network research community. We explore the novel idea of applying ad hoc networking for urban search and rescue operations. Several algorithms have been proposed and implemented for routing in ad hoc networks and their performance have been thoroughly analyzed. But none of the prior work deals specifically for search and rescue operations, which entail certain specific criteria such as prevention of node loss, maximizing the area of coverage and constant and instantaneous access to a main controller. In this thesis, we propose a centralized and adaptive algorithm tailored for efficient performance of mobile nodes assisting in search and rescue operations. The proposed algorithm assists in finding and maintaining stable links between the mobile nodes and base station, while optimizing the area of coverage and energy efficiency of the nodes. The algorithm is implemented using ns (network simulator), and its performance is compared with that of a widely used ad hoc routing protocol, Ad hoc On-demand Distance Vector (AODV) routing protocol. We use frequency of link breakages, network throughput and routing overhead as our performance metrics. This algorithm can also be extended to provide support for routing among mobile nodes.

In 5G systems, two radio air interfaces, evolved LTE and New Radio (NR), will coexist. By using millimeter waves, NR will provide high throughputs, but the higher frequencies will also lead to increased losses and a worse coverage. Multi-connectivity is therefore envisioned as a way to tackle these effects by connecting to multiple base stations simultaneously, allowing users to benefit from both air interfaces’ advantages. In this thesis, we investigate how multi-connectivity can be used efficiently in ultra-dense networks, a new paradigm in which the number of access nodes exceeds the number of users within the network. A framework for secondary cell association is presented and an energy efficiency’s condition is proposed. Upper and lower bounds of the network’s energy efficiency are analytically expressed. Algorithms for secondary cell selection are designed and evaluated through simulations. Multi-connectivity showed an improvement of up to 50% in reliability and and an increase of up to 20% in energy efficiency.

The cognitive radio (CR) concept is expected to be adopted along with many technologies to meet the requirements of the next generation of wireless and mobile systems, the 5G. Consequently, it is important to determine the performance of the CR systems with respect to these requirements. In this thesis, after briefly describing the 5G requirements, we present three main directions in which we aim to enhance the CR performance. The first direction is the reliability. We study the achievable rate of a multiple-input multiple-output (MIMO) relay-assisted CR under two scenarios; an unmanned aerial vehicle (UAV) one-way relaying (OWR) and a fixed two-way relaying (TWR). We propose special linear precoding schemes that enable the secondary user (SU) to take advantage of the primary-free channel eigenmodes. We study the SU rate sensitivity to the relay power, the relay gain, the UAV altitude, the number of antennas and the line of sight availability. The second direction is the scalability. We first study a multiple access channel (MAC) with multiple SUs scenario. We propose a particular linear precoding and SUs selection scheme maximizing their sum-rate. We show that the proposed scheme provides a significant sum-rate improvement as the number of SUs increases. Secondly, we expand our scalability study to cognitive cellular networks. We propose a low-complexity algorithm for base station activation/deactivation and dynamic spectrum management maximizing the profits of primary and secondary networks subject to green constraints. We show that our proposed algorithms achieve performance close to those obtained with the exhaustive search method. The third direction is the energy efficiency (EE). We present a novel power allocation scheme based on maximizing the EE of both single-input and single-output (SISO) and MIMO systems. We solve a non-convex problem and derive explicit expressions of the corresponding optimal power. When the instantaneous channel is not available, we present a simple sub-optimal power that achieves a near-optimal EE. The simulations show that the sub-optimal solution is very close to the optimal one. In the MIMO case, we show that adopting more antennas is more energy efficient.

De nos jours, des efforts majeurs pour la conception de systèmes sur puces performants et efficaces énergétiquement sont en cours. Le déclin de la loi de Moore au début du XX e siècle a poussé les concepteurs à augmenter le nombre de cœurs par processeur pour continuer d’améliorer les performances. En conséquence, la surface de silicium occupée par les mémoires caches a augmentée. La finesse de gravure toujours plus petite a également fait augmenter le courant de fuite des transistors CMOS. Ainsi, la consommation énergétique des mémoires occupe une part de plus en plus importante dans la consommation globale des puces. Pour diminuer cette consommation, de nouvelles technologies de mémoires émergent depuis une dizaine d’années : les mémoires non volatiles (NVM). Ces mémoires ont la particularité d’avoir un courant de fuite très faible comparé aux technologies CMOS classiques. De fait, leur utilisation dans une architecture permettrait de diminuer la consommation globale de la hiérarchie de caches. Cependant, ces technologies souffrent de latences d’accès plus élevées que la SRAM, de coûts énergétiques d’accès plus importants et d’une durée de vie limitée. Leur intégration à des systèmes sur puces nécessite de continuer à rechercher des solutions. Cette thèse cherche à évaluer l’impact d’un changement de technologie dans la hiérarchie de caches.Plus spécifiquement, elle s’intéresse au cache de dernier niveau (LLC) et la technologie non volatile considérée est la STT-MRAM. Nos travaux adoptent un point de vue architectural dans lequel une modification de la technologie n’est pas retenue. Nous cherchons alors à intégrer les caractéristiques différentes de la STT-MRAM lors de la conception de la hiérarchie mémoire. Une première étude a permis de mettre en place un cadre d’exploration architectural pour des systèmes contenant des mémoires émergentes. Une seconde étude sur les optimisations architecturales au niveau du LLC a été menée pour identifier quelles sont les opportunités d’intégration de la STT-MRAM. Le but est d’améliorer l’efficacité énergétique tout en atténuant les pénalités d’accès dues aux fortes latences de cette technologie. / Today, intensive efforts to design energy-efficient and high-performance systems-on-chip (SoCs) are underway. Moore’s end in the early 20 th century pushed designers to increase the number of core per processor to continue to improve the performance. As a result, the silicon area occupied by cache memories has increased. The ever smaller technology node also increased the leakage current of CMOS transistors. Thus, the energy consumption of memories represents an increasingly important part in the overall consumption of chips.To reduce this energy consumption, new memory technologies have emerged overthe past decade : non-volatile memories (NVM). These memories have the particularity of having a very low leakage current compared to conventional CMOS technologies. In fact, their use in an architecture would reduce the overall consumption of the cache hierarchy. However, these technologies sufferfrom higher access latencies than SRAM, higher access energy costs and limitedlifetime. Their integration into SoCs requires a continuous research effort.This thesis work aims to evaluate the impact of a change in technology in the cache hierarchy. More specifically, we are interested in the Last-Level Cache(LLC) and we consider the STT-MRAM technology. Our work adopts an architectural point of view in which a modification of the technology is not retained. Then,we try to integrate the different characteristics of the STT-MRAM atarchitectural level when designing the memory hierarchy. A first study set upan architectural exploration framework for systems containing emerging memories. A second study on architectural optimizations at LLC was conducted toidentify opportunities for the integration of STT-MRAM. The goal is to improve energy efficiency while reducing access penalties due to the high latency ofthis technology.

The water supplies of some small inland communities may come in the form of river systems that offer brackish water. Not fit for immediate human consumption, the water can be further processed using reverse osmosis to be converted into drinking water.In very remote areas there are limited energy resources, and for those areas that lie beyond a municipal distribution grid, renewable energy sources may be used. A reverse osmosis system that operates from the limited power generated by a renewable energy system must do so with the utmost of efficiency. Three methods in improving the efficiency of small-scale reverse-osmosis system are investigated, namely high-pressure pump speed control, feed water heating and vacuum pump based energy recovery.

Doctor of Philosophy(PhD) / This thesis describes the exploration and the development of computational means to investigate the behaviour of design objects before they are available for investigation in the physical world. The motivation is to inform the design process about the design object’s performance in order to achieve better – more performance-oriented – design outcomes in the sense of energy efficiency and comfort performance than can be achieved by conventional design techniques. The research is structured into five successive parts. - Concept Development – A review of the objective domains comfort assessment and energy efficiency assessment is conducted and the design process, human design activity and the application of simulation in the architectural domain is discussed in order to identify requirements for the development of computational means for design analysis. Requirements regarding model content, model features and model integration are developed. The main requirements are that a highly integrated, three-dimensional and dynamic representation of physical processes is needed and that a universal and integrated representation is required. - Concept Formulation – Based on the identified requirements, the concept for a model is formulated. In order to achieve a universal and integrated representation of physical processes the concept uses the approach of a constructive language. Space is represented with autonomous spatial elements, called congeneric cells. Interaction between the cells is represented by near- and remote-conjunctions. Physical and geometric self-contained formulations of the model reduce the model input requirements, so that geometric information and simple property specification (material, activity) is sufficient to describe the design object in the model. - Model Development – The concept is formulated in mathematical physical terms based on well known physical laws and building physical models (first-principle approach). Heat and moisture conduction, diffusion of various components and a flow model is formulated as near-conjunction processes. Heat radiation, light and sound are modelled with a radiosity approach as remote-conjunctions. The simulation algorithm, which governs the interaction between the cells in order to represent the behaviour of space, is explained. - Computational Implementation – The concept and the model is tested by implementation of a prototype using C++ and OpenGL on a conventional Pentium 4 notebook. The prototype consists of three parts: user-interface, model translator and simulation engine. The user interface functions as model-input and result-output device. The implementation of the concept and of further model parts is described in detail. - Assessment and Testing – The developed concept and the model, as implemented in the prototype, are tested and assessed against the initially developed requirements. The physical model is assessed in regard to plausibility and accuracy of the representation of the physical phenomena. At the end of the thesis the project is summarized, the achievements of the project’s objectives are discussed critically and issues for future research are suggested. Possible applications of the developed model are listed, and the contributions to the application of computational simulation in the architectural domain, developed in this research, are named. At the current stage the required processing time and high memory requirements prevent implementation of a design assessment system, following the suggested concept, at a useful scale. Also the developed physical models require further refinement and testing. Although the general feasibility of the concept and the model was successfully demonstrated, its implementation in a fully applicable design assessment system based on the universal and integrated representation of physical processes was not achieved at this stage. While detailed description and analysis is given in the body of the thesis, detailed formulations of the work and the developed model are given in the appendix. The body and the appendix together provide a complete picture of the research presented.

<p>This paper presents the energy saving curtains, in order to make the</p><p>consumers be more aware of the energy efficiency of the energy saving</p><p>curtains, the paper gave related analysis and conclusions.</p><p>The work was performed by using the Parasol Program, developed by Lunds University, Sweden. The Program is used for quantifying the influence of window size, glass type, textile type, wall thermal insulation and sun shading on annual energy use and indoor thermal comfort. The results which are obtained from the calculations are applicable to similar climatic and environment conditions. Calculations were performed to investigate the potential for using sunshade devices to reduce annual energy demand for cooling and heating. Different materials and dimensions of the energy saving</p><p>curtain are used as variables in the analysis. The results indicated that for the current climatic conditions and other related factors, the total reduction rate of the annual energy consumption of office used buildings in Stockholm is estimated generally 20% -30% lower comparing to those buildings without energy saving curtain system. That means at least 20% of energy cost can be saved by the energy saving curtain system.</p>

<p>The impact of window area on the energy balance of a building was investigated by simulations in DEROB-LTH. The glazed area was varied in three types of buildings with different types of glazing and for several climates.</p><p>One low energy house was compared to a less insulated house but identical in size and layout. Three different types of glazing were used; uncoated double glazing, double glazing with one low-e coated pane and triple glazing with two low-e coated panes. Climates with variations in solar radiation, mean temperature, altitude and latitude were chosen.</p><p>The results show that if energy efficient window alternatives are chosen the flexibility of choosing the glazed area and orientation is higher. Choosing a larger area facing south resulted in a higher heating demand for uncoated double glazing in the standard house. An increased area also resulted in an increased peak load for heating for all the simulated cases. Choosing the energy efficient glazing type gave a decrease in heating demand for increased south facing glazed area in the standard house. In the low energy house the difference in heating demand between different areas was smaller than for the standard house. </p><p>An office module with two types of switchable glazing and one solar control glazing unit was used in three different climates; Stockholm, Brussels and Rome. Larger window areas increase the cooling demand but if glazing types with lower solar transmittance are used, the difference in cooling demand between different window areas decreases. An extremely large window area, however, increases the peak load both for cooling and for heating and should therefore be avoided. Energy can be saved by using switchable windows instead of solar control or in particular standard glazing.</p>

The United States Environmental Protection Agency has used environmental information provision as a policy tool to take advantage of consumer preferences for products that meet higher environmental standards. Such environmental programs include a variety of policies ranging from eco-labeling programs to voluntary environmental agreements between governments and manufacturers. This study analyzes the effects of two such programs - the ENERGY STAR program, an eco-labeling program, and the Climate Leaders program, a voluntary environmental agreement program - on consumer preferences for a household appliance. The study estimates consumer willingness to pay (WTP) for the two programs and examines factors that motivate WTP. A particular interest for the ENERGY STAR program is in determining how the offer of a mail-in rebate affects these preferences. Data used for this study was collected from an online survey conducted in the United States during March and April, 2009. Conditional and random parameter logit models, with product attributes only and with demographic and other individual characteristics as interaction terms, are used to analyze the data. Findings from this study imply that consumers are willing to pay a premium equivalent to a significant portion of the purchase prices for the products approved by either program. Also, it is found that consumers who are more concerned about environmental issues, such as global climate change, and who have confidence in the effects of collective action, are more likely to engage in the purchase of such environmentally friendly products. These results should help government agencies and manufacturers evaluate the effectiveness of environmental information provision programs.