Dissertations / Theses on the topic 'Adaptation energy'

Notre travail s'inscrit dans le cadre des recherches sur le Sleeping mode. Notre contribution est structurée principalement autour deux axes : l'étude et l'évaluation de la performance des processus de mise en veille/réveil des points d'accès et la sélection du nombre minimal des points d'accès dans un milieu urbain dense. Dans un premier temps, nous étudions les processus de mise en veille/réveil des points d'accès dans un scenario classique de réseau domestique. Ce scenario suppose que le point d'accès mis en veille doit détecter la présence d'un utilisateur potentiel dans sa zone de couverture et réagir par conséquence d'une façon autonome pour se mettre en état de fonctionnement normal. Nous avons choisi quatre processus de réveil du point d'accès, et nous avons ensuite étudié chacun de ces processus, et proposé un protocole de communication qui permette à un utilisateur d'envoyer l'ordre au point d'accès de s'éteindre. Lorsque cela était possible, nous avons utilisé le protocole COAP qui est prévu pour établir des sessions de commande pour l'Internet des Objets. Nous avons ensuite mesuré les performances du point de vue de l'économie d'énergie qu'il permet de réaliser et du délai entre le moment où un utilisateur potentiel est détecté et le moment où le point d'accès devient opérationnel. Nous avons aussi étudié un réseau dense dans un milieu urbain (le centre ville de Rennes) où la zone de couverture d'un point d'accès pouvait être partiellement ou totalement couverte par d'autres points d'accès. Pour évaluer la redondance dans le réseau, nous avons collecté des informations réelles sur les points d'accès en utilisant l'application Wi2Me. Le traitement de ces informations nous a permis d'identifier les points d'accès existants dans la zone étudiée et leurs zones de couverture respectives démontrant ainsi la superposition de ces zones de couverture et le potentiel d'élimination d'un certain nombre de points d'accès sans affecter la couverture globale. Nous avons alors proposé un système centralisé qui collecte les données de couverture des points d'accès observée par les utilisateur. Nous avons donc utilisé ce simple fait pour centraliser la vue du réseau de plusieurs utilisateurs, ce qui permet d'avoir une vue assez précise de la disponibilité des points d'accès dans une zone géographie. Nous avons alors proposé une représentation de ces données de couverture à travers des matrices qui traitent les différentes erreurs de capture (coordonnées GPS non précises, réutilisation des noms de réseaux, etc). Enfin, nous avons ensuite proposé deux algorithmes permettant de sélectionner l'ensemble minimal des points d'accès requis fournissant une couverture identique à celle d'origine
The main goal of the thesis is to design an Energy Proportional Network by taking intelligent decisions into the network such as switching on and off network components in order to adapt the energy consumption to the user needs. Our work mainly focuses on reducing the energy consumption by adapting the number of APs that are operating to the actual user need. In fact, traffic load varies a lot during the day. Traffic is high in urban areas and low in the suburb during day work hours, while it is the opposite at night. Often, peak loads during rush hours are lower than capacities of the networks. Thus they remain lightly utilized for long periods of time. Thus keeping all APs active all the time even when the traffic is low causes a huge waste of energy. Our goal is to benefit from low traffic periods by automatically switch off redundant cells, taking into consideration the actual number of users, their traffic and the bandwidth requested to serve them. Ideally we wish to do so while maintaining reliable service coverage for existing and new coming users. First we consider a home networking scenario. In this case only one AP covers a given area. So when this AP is switched off (when no users are present), there will be no other AP to fill the gap of coverage. Moreover, upon the arrival of new users, no controller or other mechanism exists to wake up the AP. Consequently, new arriving users would not be served and would remain out of coverage. The study of the state of the art allowed us to have a clear overview of the existing approaches in this context. As a result, we designed a platform to investigate different methods to wake up an AP using different technologies. We measure two metrics to evaluate the Switching ON/OFF process for the different methods. The first is the energy consumed by the AP during the three phases it goes through. The second is the delay of time for the AP to wake up and be operational to serve the new users. In the second case we consider a dense network such as the ones found in urban cities, where the coverage area of an AP is also covered by several other APs. In other words, the gap resulting from switching off one or several APs can be covered by other neighbouring ones. Thus the first thing to do was to evaluate the potential of switching off APs using real measurements taken in a dense urban area. Based on this collected information, we evaluate how many APs can be switched off while maintaining the same coverage. To this end, we propose two algorithms that select the minimum set of APs needed to provide full coverage. We compute several performance parameters, and evaluate the proposed algorithms in terms of the number of selected APs, and the coverage they provide

Context: Cloud computing is providing services and resources to customers based on pay-per-use. As the services increasing, Cloud computing using a vast number of data centers like thousands of data centers which consumes high energy. The power consumption for cooling the data centers is very high. So, recent research going on to implement the best model to reduce the energy consumption by the data centers. This process of minimizing the energy consumption can be done using dynamic Virtual Machine Consolidation (VM Consolidation) in which there will be a migration of VMs from one host to another host so that energy can be saved. 70% of energy consumption will be reduced/ saved when the host idle mode is switched to sleep mode, and this is done by migration of VM from one host to another host. There are many energy adaptive heuristics algorithms for the VM Consolidation. Host overload detection, host underload detection and VM selection using VM placement are the heuristics algorithms of VM Consolidation which results in less consumption of the energy in the data centers while meeting Quality of Service (QoS). In this thesis, we proposed new heuristic algorithms to reduce energy consumption. Objectives: The objective of this research is to provide an energy efficient model to reduce energy consumption. And proposing a new heuristics algorithms of VM Consolidationtechnique in such a way that it consumes less energy. Presenting the advantages and disadvantages of the proposed heuristics algorithms is also considered as objectives of our experiment. Methods: Literature review was performed to gain knowledge about the working and performances of existing algorithms using VM Consolidation technique. Later, we have proposed a new host overload detection, host underload detection, VM selection, and VM placement heuristic algorithms. In our work, we got 32 combinations from the host overload detection and VM selection, and two VM placement heuristic algorithms. We proposed dynamic host underload detection algorithm which is used for all the 32 combinations. The other research method chosen is experimentation, to analyze the performances of both proposed and existing algorithms using workload traces of PlanetLab. This simulation is done usingCloudSim. Results: To compare and get the results, the following parameters had been considered: Energy consumption, No. of migrations, Performance Degradation due to VM Migrations (PDM),Service Level Agreement violation Time per Active Host (SLATAH), SLA Violation (SLAV),i.e. from a combination of the PDM, SLATAH, Energy consumption and SLA Violation (ESV).We have conducted T-test and Cohen’s d effect size to measure the significant difference and effect size between algorithms respectively. For analyzing the performance, the results obtained from proposed algorithms and existing algorithm were compared. From the 32 combinations of the host overload detection and VM Selection heuristic algorithms, MADmedian_MaxR (Mean Absolute Deviation around median (MADmedian) and Maximum Requested RAM (MaxR))using Modified Worst Fit Decreasing (MWFD) VM Placement algorithm, andMADmean_MaxR (Mean Absolute Deviation around mean (MADmean), and MaximumRequested RAM (MaxR)) using Modified Second Worst Fit Decreasing (MSWFD) VM placement algorithm respectively gives the best results which consume less energy and with minimum SLA Violation. Conclusion: By analyzing the comparisons, it is concluded that proposed algorithms perform better than the existing algorithm. As our aim is to propose the better energy- efficient model using the VM Consolidation techniques to minimize the power consumption while meeting the SLAs. Hence, we proposed the energy- efficient algorithms for VM Consolidation technique and compared with the existing algorithm and proved that our proposed algorithm performs better than the other algorithm. We proposed 32 combinations of heuristics algorithms (host overload detection and VM selection) with two adaptive heuristic VM placement algorithms. We have proposed a dynamic host underload detection algorithm, and it is used for all 32 combinations. When the proposed algorithms are compared with the existing algorithm, we got 22 combinations of host overload detection and VM Selection heuristic algorithms with MWFD(Modified Worst Fit Decreasing) VM placement and 20 combinations of host overload detection and VM Selection heuristic algorithms with MSWFD (Modified Second Worst FitDecreasing) VM placement algorithm which shows the better performance than existing algorithm. Thus, our proposed heuristic algorithms give better results with minimum energy consumption with less SLA violation.

In view of the problem of uneven load distribution and energy consumption among nodes in a multi-hop wireless sensor network, this research constructs the routing schedule problem as a MOP (Multi-objective Optimization Problem), and proposed an energy-aware routing optimization scheme RDSEGA based on multi-objective optimization. In this scheme, in order to avoid the searching space explosion problem caused by the increase of nodes, KSP Yen's algorithm was applied to prune the searching space, and the candidate paths selected after pruning are recoded based on priority. Then adopted the improved strengthen elitist genetic algorithm to get the entire network routing optimization scheme with the best energy efficiency. At the same time, in view of the problem of routing discontinuity in the process of path crossover and mutation, new crossover and mutation method was proposed that based on the gene fragments connected by the adjacent node or the same node to maximize the effectiveness of the evolution result. The experimental results prove that the scheme reduced the energy consumption of nodes in the network, the load between nodes becomes more balanced, and the working time of the network has been prolonged nearly 40% after the optimization. This brings convenience to practical applications, especially for those that are inconvenient to replace nodes.

Wireless ad hoc networks have a number of advantages over traditional, infrastructure-based networks. Robustness and easy deployment are two of the main advantages. However, the distributed nature of such networks raises a number of design challenges, especially when energy-efficiency and QoS requirements are to be taken into consideration. These challenges can only be met by allowing closer cooperation and mutual adaptation between the protocol layers, referred to as a cross-layer design paradigm. In energy-constrained wireless ad hoc networks, each node can only transmit to a limited number of other nodes directly. Hence, in order to reach distant destinations, intermediate nodes must relay the traffic of their peer nodes, resulting in multihop routes. The total energy consumption associated with a end-to-end transmission over such a route can be significantly reduced if the nodes are correctly configured. A cross-layer, optimization scheme, based on adaptive modulation and power control, is proposed in this thesis. The optimization scheme assumes that an existing route has been found, and allows QoS requirements in terms of end-to-end bit error rate and delay. Both transmission and circuit energy consumption is taken into consideration. By jointly optimizing all nodes throughout the route, the total energy consumption can be reduced by more than 50%, compared to a fixed-rate system. The adaptive system also exhibits superior capabilities to meet stringent QoS requirements. Results for both continuous and discrete rate adaptation is produced, and it is found that discrete adaptation causes only a small performance degradation, compared to the optimal, continuous case. Simulations also show that the system is vulnerable to inaccurate link state information. Finally, the effects of maximum-rate limitation and ignoring the circuit power consumption is investigated.

Context: In recent years, Cloud computing has gained a wide range of attention in both industry and academics as Cloud services offer pay-per-use model, due to increase in need of factors like reliability and computing results with immense growth in Cloud-based companies along with a continuous expansion of their scale. However, the rise in Cloud computing users can cause a negative impact on energy consumption in the Cloud data centers as they consume huge amount of overall energy. In order to minimize the energy consumption in virtual datacenters, researchers proposed various energy efficient resources management strategies. Virtual Machine dynamic Consolidation is one of the prominent technique and an active research area in recent time, used to improve resource utilization and minimize the electric power consumption of a data center. This technique monitors the data centers utilization, identify overloaded, and underloaded hosts then migrate few/all Virtual Machines (VMs) to other suitable hosts using Virtual Machine selection and Virtual Machine placement, and switch underloaded hosts to sleep mode.   Objectives: Objective of this study is to define and implement new energy-aware heuristic algorithms to save energy consumption in Cloud data centers and show the best-resulted algorithm then compare performances of proposed heuristic algorithms with old heuristics.   Methods: Initially, a literature review is conducted to identify and obtain knowledge about the adaptive heuristic algorithms proposed previously for energy-aware VM Consolidation, and find the metrics to measure the performance of heuristic algorithms. Based on this knowledge, for our thesis we have proposed 32 combinations of novel adaptive heuristics for host overload detection (8) and VM selection algorithms (4), one host underload detection and two adaptive heuristic for VM placement algorithms which helps in minimizing both energy consumption and reducing overall Service Level Agreement (SLA) violation of Cloud data center. Further, an experiment is conducted to measure the performances of all proposed heuristic algorithms. We have used the CloudSim simulation toolkit for the modeling, simulation, and implementation of proposed heuristics. We have evaluated the proposed algorithms using PlanetLab VMs real workload traces.   Results: The results were measured using metrics energy consumption of data center (power model), Performance Degradation due to Migration (PDM), Service Level Agreement violation Time per Active Host (SLATAH), Service Level Agreement Violation (SLAV = PDM . SLATAH) and, Energy consumption and Service level agreement Violation (ESV).  Here for all four categories of VM Consolidation, we have compared the performances of proposed heuristics with each other and presented the best heuristic algorithm proposed in each category. We have also compared the performances of proposed heuristic algorithms with existing heuristics which are identified in the literature and presented the number of newly proposed algorithms work efficiently than existing algorithms. This comparative analysis is done using T-test and Cohen's d effect size.   From the comparison results of all proposed algorithms, we have concluded that Mean absolute Deviation around median (MADmedain) host overload detection algorithm equipped with Maximum requested RAM VM selection (MaxR) using Modified First Fit Decreasing VM placement (MFFD), and Standard Deviation (STD) host overload detection algorithm equipped with Maximum requested RAM VM selection (MaxR) using Modified Last Fit decreasing VM placement (MLFD) respectively performed better than other 31 combinations of proposed overload detection and VM selection heuristic algorithms, with regards to Energy consumption and Service level agreement Violation (ESV). However, from the comparative study between existing and proposed algorithms, 23 and 21 combinations of proposed host overload detection and VM selection algorithms using MFFD and MLFD VM placements respectively performed efficiently compared to existing (baseline) heuristic algorithms considered for this study.   Conclusions: This thesis presents novel proposed heuristic algorithms that are useful for minimization of both energy consumption and Service Level Agreement Violation in virtual datacenters. It presents new 23 combinations of proposed host overloading detection and VM selection algorithms using MFFD VM placement and 21 combinations of proposed host overloading detection and VM selection algorithms using MLFD VM placement, which consumes the minimum amount of energy with minimal SLA violation compared to the existing algorithms. It gives scope for future researchers related to improving resource utilization and minimizing the electric power consumption of a data center. This study can be extended in further by implementing the work on other Cloud software platforms and developing much more efficient algorithms for all four categories of VM consolidation.

The most recent analysis of energy usage in the country reveled that nearly 50% of the power generation is used for air conditioning and mechanical ventilation most of which is used by commercial organizations. The grid generation mix that contains a high percentage of fossil fuel makes such energy usage environment unfriendly. Although absorption refrigeration is an old technique its economical application is limited to applications where cheap or waste heat energy is available despite decades of R&D, due to low COP, high initial cost and larger size. Heat input at Moderately high (over 120ᵒC) temperature and need to release large amount of heat to the environment through liquid or air cooling makes absorption chiller less conducive in cooling. Yet, being a tropical country, Sri Lanka has a better potential in adopting solar driven absorption refrigeration, if the chillers are operated at low temperature heat input that also promotes efficiency in storage that is mandatory due to fluctuation of energy source, subject to economic feasibility. The project aims designing and modeling of a solar power driven absorption chiller system that is adoptable to a selected medium size commercial organization. The proposed system uses heat energy around 100ᵒC and reusing fraction of energy expelled to the environment by suitably modifying operating parameter and thereby increasing efficiency of the system. Reduction of such heat losses and reducing heat input is achieved with the use of secondary heat exchange (brine) system that optimizes the energy usage. This arrangement will make efficient usage of solar heat storage, even in the considerable absence of solar power. System modeling and simulation of both basic double effect chiller and its modified versions were carried out and compared to evaluate improvement. The simulation of the modified system was used to obtain working parameters of the chiller so that a suitable solar collector, chilled water and heat rejection systems can be designed. Operational conditions of the cooling system are measured by the state sensors that feed inputs to the control system to achieve the optimum efficiency and their technical details are also included in the report.

Wave ocean energy is a source of renewable energy which is gaining interest in the modern world. In contrast to other well-researched renewable energy sources such as wind energy, wave ocean energy is under the development phase. Governments around the world are encouraging the research of harnessing wave energy. As of now, there are different concepts to harness energy from waves. Tribological components are one of the main aspects that need attention in these wave energy converters. The moving components such as bearings can be the life-determining component of the entire device. This thesis provides conceptual solutions to adapt an existing start-stop bearing test rig to the conditions of wave energy converters. The test rig can test different bearing sused in the wave energy converters. The new design intends to provide scaled wave energy conditions. These conditions are mainly influenced by the oscillating movement of the bearings, the complex load condition and the salty environment. Since the testing of bearings in wave energy converters is in the initial stage, modular designs are implemented to test different types of bearings.
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Modéliser des phénomènes électromagnétiques par des méthodes déterministes requiert une division du volume étudié en éléments discrets dont la taille est de l'ordre du dixième de la longueur d'onde. La demande en ressource informatique augmente donc avec la fréquence. De plus, compte tenu de la complexité des problèmes et des incertitudes sur les données d'entrées, il devient illusoire de réaliser un calcul déterministe pour chaque variable analysée. De nouvelles méthodes, dites énergétiques, sont développées pour étudier les systèmes grands devant la longueur d'onde. Elles permettent d'estimer statistiquement la valeur du champ à l'intérieur d'un système. Une de ces techniques, la Statistical Energy Analysis (SEA), développée en acoustique, est transposée ici en électromagnétisme. La SEA permet de décrire les échanges d'énergies entre les différents systèmes composant une structure. L'énergie de chaque système dépend des notions de mode de résonance, de perte et de couplage. Les paramètres liés à ces notions sont évalués analytiquement et numériquement. Une méthode de sous structuration automatique est également présentée Les résultats obtenus semblent confirmer l'intérêt de cette méthode
Modeling electromagnetic phenomena by deterministic methods requires a subdivision of the volume under study into a number of discrete elements with sizes of the order of tenth of the wavelength. So, the demand for computer resources significantly grows with increasing frequencies. Moreover, taking into account the complexity of the problems and the uncertainties on the input data, it becomes illusory to make a deterministic calculation for each studied variable. New methods, called energetic methods, were developed to study systems large in front of the wavelength. They allow to estimate statistically the value of the field inside a system One of these methods, the Statistical Energy Analysis (SEA), developed in acoustic, is transposed here in electromagnetism. The SEA allows to describe the exchanges of energy between the different systems of a structure. The energy of each system depends on the concepts of mode of resonance, loss and coupling. The parameters linked with these concepts are assessed by analytical formulae and numerical simulations. An automatic sub structuring method is also presented. The results obtained seem to confirm the interest of this method

Resilience and solar energy are separately growing in popularity for urban planners and similar professionals. This project links the two discrete terms together and examines the extent to which solar energy can improve local government resilience efforts. It includes a detailed literature review of both topics, as well as the methodology and findings related to a survey and interviews of local government officials and key stakeholders across the country related to hazard mitigation and energy assurance planning. This research finds that integrating the use of solar energy can improve local government resilience efforts related to mitigation, preparedness, response and recovery activities in the following ways: by being incorporated into hazard mitigation strategies as a means to maintain critical operations, thereby reducing loss of life and property; by being utilized in comprehensive planning efforts to increase capacity and decrease reliance and stress upon the grid, thereby reducing the likelihood of blackout events; by being used in tandem with backup storage systems as an integral part of energy assurance planning, which can help ensure critical functions continue in times of grid outage; by being used to provide power for response activities such as water purification, medicine storage and device charging; and by being used as an integral part of rebuilding communities in a more environmentally-conscious manner. The result of the research is a document entitled Solar Energy & Resilience Planning: a practical guide for local governments, a guidebook for local government officials wishing to have more information about incorporating solar energy into current resilience initiatives; it is included at the end of the report as Appendix C.

There is evidence that hotels are the highest energy use buildings of the tertiary sector in Europe and internationally because of their operational characteristics and the large number of users. Therefore, there is potential for significant energy savings. This study investigated the energy performance of the hotel sector in Greece and proposes a methodology for their energy classification and climate change mitigation strategies for an optimum building envelope design for a typical hotel building operated all year or seasonally. This was achieved by collecting operational energy data for 90 Greek hotels and analyzing them using the k-means algorithm. Then a typical hotel building was modelled using TRNSYS and climate change weather files to assess the impact on its energy demand and to propose climate change mitigation strategies. The assessment was performed via hourly simulations with real climatic data for the past and generated future data for the years 2020, 2050 and 2080. The analysis of the energy data (based on utilities supply) of 90 hotels shows average consumption approx 290 kWh/m2/year for hotels with annual operation and 200 kWh/m2/year for hotels with seasonal operation. Furthermore, the hotels were classified in well separated clusters in terms of their electricity and oil consumption. The classification showed that each cluster has high average energy consumption compared to other buildings in Greece. Cooling energy demand of the typical building increased by 33% and heating energy demand decreased by 22% in 2010 compared to 1970. Cooling load is expected to rise by 15% in year 2020, 34% in year 2050 and 63% in year 2080 compared to year 1970. Heating load is expected to decrease by 14% in year 2020, 29% in year 2050 and 46% in year 2080. It was found that different strategies can be applied to all year and seasonally operated buildings for the most energy efficient performance. These include: a. For all year operated buildings: insulation, double low e glazing, intelligently controlled night and day ventilation, ceiling fans and shading. The building of year 2050 would need more shading and the building of year 2080 would need additional shading and cool materials. b. For seasonally operated buildings: Intelligently controlled night and day ventilation, cool materials, ceiling fans, shading and double low e glazing. Only the building of year 2080 would need insulation. This study makes a contribution to understanding the impact of the climate change on the energy demand of hotel buildings and proposes mitigation strategies that focus on the building envelope in different periods and climatic zones of Greece.

Ukraine chose the way of European integration, finally confirming the intentions, when signed an Agreement about Association between European Union and Ukraine on June,27,2014. To meet the obligations Ukraine should implement the adaptation of national legislation including energy efficiency and renewable energy to the European Union.

Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 7, 2008) Includes bibliographical references.

In September 2020, Northeast China suffered three unprecedented typhoons in half a month, and there was freezing rain in early November, all of which led to the large-scale urban power failure. The occurrence of these phenomena makes people directly see climate change and its impact on the living environment of human beings. Many studies have shown that the cause of climate change is the increase of artificial greenhouse gas emissions since industrialization. In addition to the increase of extreme weather disasters, the most direct manifestations of climate change are the rising temperature, droughts, and rising sea levels. The building sector accounts for 39% of global greenhouse gas emissions and 36% of energy consumption. To ensure the long-term integrity and normal operation of buildings, we need to understand the impact of climate on buildings, and how to deal with it. This paper reviews the literature on climate change and building energy by searching search engines and literature databases. For extreme weather, most literature talks about the impact of power failure, the main strategy is to improve reliability, resilience, sustainability, and robustness, it can help reduce losses and recover as soon as possible. On the other hand, the methods of adaptation to and mitigation of non-disaster weather are reviewed from the perspective of sustainability. This paper mainly reviews the methods of passive technology and strategy for exemplary buildings, building envelope, passive ventilation, lighting/shading, solar energy, bioenergy, dehumidification, passive cooling, and design strategy. According to the local climate, the geographical characteristics of the building, to develop comprehensive passive technology and strategy, can meet or close to meet their energy saving, emission reduction, comfort needs. This paper can provide a technical and strategic reference for the building sector to deal with climate change.

Via online ZOOM meeting Presentation

Scenario Planning as a tool for planning for the future has widespread use in the industry today and enjoys an envious status as the primary tool of futures thinking. However, the development in this field has been mired with confusion on its application and purpose. Since popularized by Shell in its use to anticipate the oil crisis in the 70s, scenario thinking has grown in use to aid public policy making, corporate strategic planning and even in the natural sciences. This paper attempts to study the scenario planning process design from a corporate perspective by studying its use in energy companies in Sweden. Energy companies present an ideal industry for this study as it is embroiled with obvious uncertainties in future power and carbon prices but also with subjective uncertainties tied to the political interest in the industry and the industry being in the centre of the climate change debate. Furthermore, the extremely long term nature of investment projects in this industry further exacerbates the need for deep insights into the future. This paper studies the nature of the scenario planning process based on two past papers; that have identified the key characteristics of scenarios. Firm specific internal factors are used to explain the differences in the process designs found in empirical data. Finally a framework to design a scenario planning process is proposed. This framework takes into account these internal factors to enable companies to leverage their internal resources and make full use of scenario planning as a tool.

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, Technology and Policy Program, 2018
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 82-85).
Water and Energy systems that were once considered disparate, are coupled in many ways. Generation, transmission and distribution of each system relies on the other system. The interaction becomes significantly stronger in economies dependent on desalination for their water resources. One such country is the United Arab Emirates. The water-energy nexus faces serious challenges under climate change as cooling needs and outdoor water demands rise. This thesis models the impact of climate change on the water-energy nexus in the UAE. It explores a set of climate change adaptation policy scenarios and quantifies their respective economic, water and energy savings. Hence, it provides an analytical assessment of the nexus that can inform data-driven policy making. This thesis views the nexus through a qualitative lens and a quantitative lens. The qualitative piece presents the organizational mapping and structuring of the UAE institutions across the water-energy-climate nexus.
It highlights gaps in cross-sectoral interactions that need to be overcome for a sustainable future. The second piece presented in this thesis is analytical in nature. It uses two specialized water and energy softwares called the Water Evaluation and Planning System (WEAP) and the Long-range Energy Alternatives Planning System (LEAP) and couples them together to model the nexus. The water-energy nexus model is tested for different individual and aggregate adaptation policy scenarios to assess a wide range of effects on the nexus. These scenarios are also run for six sub-regions within the UAE (Abu Dhabi, Al Ain, Western region, Dubai, Eastern region and Fujairah) to understand the underlying demand sectors driving the water-energy nexus in these sub-regions. The results of this extensive scenario analysis have informed policy recommendations for long-term planning of the water-energy nexus in the UAE.
Important findings from this study include the huge savings potential from indoor consumption reduction (up to 1200 million cubic meters of water and 60 million gigajoules of electricity per year by 2060) and the need for irrigated land regulation (saves up to 700 million cubic meters of water and 5 million gigajoules of electricity per year by 2060) in the UAE. The sub-regional analysis highlights the need for sub-regionalized policy goals that govern regions based on their demand differences.
by Iqra Nadeem.
S.M. in Technology and Policy
S.M.inTechnologyandPolicy Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, Technology and Policy Program

The clothing industry is one of the most affected branches of the economy in crisis conditions such as the global Covid-19. If the production of textiles took place in the existing conditions, many companies would stop because the labor costs are high. From the processing of raw materials, through the production of textiles, all the way to the production of clothing, the greatest chance to return to real trends is the energy transition, technological transfer and adjustment of workers. The aim of this paper is to point out the possibilities that would keep the textile industry in line with global trends in the use of renewable energy sources.

In the modern day lifestyle, two factors have been primarily associated with the rising prevalence of obesity, the increasing consumption of energy dense food and the decline in physical activity (Varo et al. 2003). With an estimated 500 million adults thought to be obese worldwide (WHO 2013), it is clear we need to stem this epidemic. Much emphasis on research has already been placed on developing strategies to manipulate these two factors and reduce the incidence of obesity but at present an effective and sustainable solution seems elusive. One thing that is clear, with the increase in the cases of obesity, there has also been a concomitant rise in our intake of high refined carbohydrates and sugars. Moreover, the consumption of sugar-sweetened beverages (SSB) has increased over the past four decades (ERS 2004) and consequently, their association with obesity has been well documented (Nissinen et al. 2009, Olsen, Heitmann 2009, Hu, Malik 2010). To undo the damage of diets high in refined carbohydrates and sugars, exercise has been thought to be the answer by many but as yet this has not yielded convincing success in promoting weight loss and repairing the alterations to metabolism associated with chronic hyperglycaemia and obesity. In the first experimental chapter, an in vivo and in vitro approach was used to investigate the effects of high glucose availability on skeletal muscle metabolism. In our in vivo study the effects of 4 weeks sugar-sweetened beverage (SSB) supplementation was investigated on lean, healthy, lightly active individuals with very little or no previous consumption of SSB. Muscle biopsies were taken from each participant pre and post 4 week intervention and through western blotting and real time reverse-transcriptase polymerase chain reaction (RT-PCR), protein and gene expression of several metabolic markers and glucose regulating factors was measured. In the in vitro study, primary human muscle cell cultures were exposed to chronic hyperglycaemia and compared to cultures with normal glucose concentrations for 7 days. Analyses revealed both the in vivo and in vitro studies demonstrated a shift towards increased glycolytic activity and reduced oxidative activity, similar to that found in type 2 diabetes mellitus patients. Furthermore, in both studies an increase in MondoA expression was observed and in the in vitro cell cultures TXNIP expression was also increased. The fact that the findings from in vivo study are comparable to those in the in vitro study, demonstrates the potency of high glucose availability on skeletal muscle. The results are even more alarming as the participants were young healthy individuals, not overweight or obese and with very little previous history of SSB consumption, highlighting just how damaging the effects of SSBs can be and the significant role they play in the development of obesity. In chapter 3 and 4, long term exercise interventions were used to investigate the effects of chronic exercise on metabolism, body composition and energy balance of lean and overweight or obese (Ov/Ob) sedentary women. The aim of these studies was to investigate the compensatory mechanisms in Ov/Ob individuals preventing adaptations to exercise. A novel approach to long term exercise with ad libitum energy intake was used in both of these studies, where participants were not recruited with a desire to lose weight and they were also naïve to the true aims of the study. In chapter 3 a 4 week exercise training intervention was used and in chapter 4 an 8 week training intervention was used. Both studies utilized a group based circuit training format 3 days per week, the 4 week intervention was at a moderate intensity and the 8 week intervention had both a high and low intensity exercise group. Dual-energy xray absorptiometry (DXA) and indirect calorimetry, at rest and during exercise, were used to give and overview of participants’ anthropometric and metabolic profiles, before and after inventions. Blood samples were collected for analysis of several key hormones regulating metabolic adaptations and energy homeostasis in response to exercise. Diet records were also collected from participants to measure any alterations in energy and macronutrient intake. Neither the 4 week nor the 8 week exercise intervention demonstrated significant weight loss of either the lean or Ov/Ob individuals. However, in both the interventions lean participants displayed losses in percentage body fat, even though no weight loss was seen overall. These findings reaffirm those reported in previous literature that during an increase in exercise induced energy expenditure, Ov/Ob individuals with respond with a concomitant increase in energy intake, negating any possible weight or fat loss and possibly even promote weight gain. On the contrary lean individuals do not display the same over-compensation to the increased energy expenditure and there energy intake is unchanged. It is hypothesized that the lean participants were able to display a reduction in body fat through the ability to exercise at a higher absolute intensity. Based on analysis of blood samples, it was possible to further investigate possible regulators that may control a homeostatic mechanism, preventing weight/fat loss in obese individuals. In the 8 week study a significant drop in amylin concentrations was observed in the Ov/Ob participants, compared to no change in the lean subjects. It was proposed that Ov/Ob individuals, who also displayed heightened insulin resistance and hyperleptinemia, have developed an overreliance on amylin for satiety signalling. Moreover, in conjunction with the inability to achieve an absolute intensity high enough to induce adaptive responses to exercise, Ov/Ob individuals with reduced amylin secretion, increase energy intake after exercise and prevent any possible weight or fat loss. Additionally, adaptive responses to exercise were seen in both the 4 week and 8 week exercise studies, Ov/Ob participants displayed a positive movement away from a preference to rely on anaerobic metabolism at a low exercise intensity preintervention, towards more anaerobic metabolism post-intervention. In addition, following the 8 week exercise intervention, the inter-individual variability in response to exercise was investigated. Participants were separated based on their heart rate response, into responders and non-responders and it was revealed that those who clearly demonstrated adaptations, also tended to lose more weight, maintain a negative energy balance, and avoid the maladaptive decrease in amylin concentrations. Suggesting these individuals do not develop the hypothesized leptin resistance, and overreliance on amylin signal, meaning they do not overcompensate for increased exercise induced energy expenditure and can lose weight. In conclusion, it is clear that an exercise only or a one size fits all approach is not the answer in the treatment of obesity. A more multi-dimensional approach is necessary and in order to reduce many of the associated lifestyle disease markers, both diet and levels of physical activity must be addressed in the obese. Recommendations for future intervention studies must address this and combine a diet low in refined carbohydrates and sugars, with high intensity interval training and resistance exercise.

Investir dans l'utilisation et la production d'énergie est une nécessité pour lutter contre le changement climatique, mais aussi un défi pour l'adaptation climatique. La première partie de cette thèse est consacrée à l'amélioration de l'efficacité énergétique des appareils électroménagers. Le Chapitre 1 analyse si les consommateurs prennent en compte les économies d'énergie des réfrigérateurs au moment de les acheter à partir de données de vente anglaises. Le Chapitre 2 présente l'étiquette énergie européenne, ses effets sur l'efficacité énergétique ainsi que les facteurs clés de succès de cette politique de grande envergure. La deuxième partie de cette thèse étend son champ d'étude aux impacts que le changement climatique aura sur les comportements d'investissement. Le chapitre 3 s'intéresse à la sensibilité du secteur électrique au climat et propose des pistes de réflexion sur la prise en compte du changement climatique dans les décisions d'investissement. Le chapitre 4 est constitué d'une étude longitudinale de l'évolution du parc immobilier américain (1985-2011) et sa sensibilité au climat, dans le but d'établir des prédictions de long terme de l'impact du changement climatique sur la demande résidentielle de gaz et d'électricité
Energy investments are a requirement to mitigate climate change, but also a challenge for adaptation. The first part of this PhD dissertation focuses on improving the energy efficiency of domestic appliances. Chapter 1 analyses if consumers take into account energy costs when they purchase refrigerators with UK market data. Chapter 2 presents the EU Energy Label, its expected effects on energy efficiency and the key factors of success of such a large scale information-based policy. The second part of this PhD dissertation broadens the scope of analysis to the impacts of climate change on energy investment behaviour. Chapter 3 reviews the climate sensitiveness of the electricity sector and provides elements of discussion on how investments decisions could better take into account climate change in the future. Chapter 4 provides a longitudinal analysis of the evolution of US housing (1985-2011) and its sensitivity to climate, with the objective of forecasting the long-run impact of climate change on both residential gas and electricity consumptions

The roll-out of the fifth-generation (5G) wireless networks alongside existing generations and characterized by a dense deployment of base stations (BSs) to serve an ever-increasing number of users and services leads to a drastic increase in the overall network energy consumption (EC). It can lead to an unprecedented rise in operational expenditure (OPEX) for the network operators and an increased global carbon footprint. The present-day networks are dimensioned according to the peak traffic demands, and hence are under-utilized due to the daily traffic variations. Therefore, to save energy, BSs can be put into sleep with different levels following the daily load variations. Selection of the right sleep level at the right instant is important to adapt the availability of the resources to the traffic load to maximize the energy savings without degrading the performance of the network. Previous studies focused on the selection of sleep modes (SMs) to maximize energy saving or the sleep duration given configuration and network resources. However, adaptive BS configuration together with SMs have not been investigated. In this thesis, the goal is to consider the design of the wireless network resources to cover an area with a given traffic demand in combination with sleep mode management. To achieve this, a novel EC model is proposed to capture the activity time of a 5G BS in a multi-cell environment. The activity factor of a BS is defined as the fraction of time the BS is transmitting over a fixed period and is dependent on the amount of BS resources. The new model captures the variation in power consumption by configuring three BS resources: 1) the active array size, 2) the bandwidth, and 3) the spatial multiplexing factor. We then implement a Q-learning algorithm to adapt these resources following the traffic demand and also the selection of sleep levels. Our results show that the difference in the average daily EC of BSs considered can be as high as 60% depending on the deployment area. Furthermore, the EC of a BS can be reduced by 57% during the low traffic hours by having deeper sleep levels as compared to the baseline scenario with no sleep modes. Implementing the resource adaptation algorithm further reduces the average EC of the BS by up to 20% as compared to the case without resource adaptation. However, the EE gain obtained by the algorithm depends on its convergence, which varies with the distribution of the users in the cell, the peak traffic demand, and the BS resources available. Our results show that by combining resource adaptation with deep sleep levels, one can obtain significant energy savings under variable traffic load. However, to ensure the reliability of the results obtained, we emphasize the need to guarantee the convergence of the algorithm before its use for resource adaptation.
Under de senaste åren har intresset för energieffektivitet (EE) av mobila kommunikationssystem ökat på grund av den ökande energiförbrukningen (EF). Med femte generationens mobilsystem, vilket kännetecknas av mer komplexa och kraftfulla basstationer (BS) för att betjäna ett ständigt ökande antal användare och tjänster, riskerar nätverkets totala EF att öka ytterligare. Detta kan leda till en markant ökning av operativa utgifter (OPEX) för nätoperatörerna och ett ökat globalt koldioxidavtryck. Många studier har visat att dagens nätverk ofta är överdimensionerade och att radioresurserna är underutnyttjade på grund av variationerna i det dagliga trafikbehovet. Genom att anpassa BS radioresurser efter trafikbehovet kan man säkerställa att man uppfyller användarkraven samtidigt som man minskar den totala EF. I denna studie föreslås en aktivitetsbaserad metod för att utvärdera EF för en BS. Aktivitetsfaktorn för en BS definieras som den bråkdel av tiden som BS är aktiv (sänder data) under en fast period och är beroende av mängden radioresurser. För att kvantifiera EF för en BS föreslås en ny modell som beräknar in effekt till BS som funktion av utstrålad effekt från BS. Den nya modellen fångar variationen i energiförbrukning med tre huvudsakliga radioresurser som är: 1) antal sändarantenner 2) bandbredd och 3) den spatiella multiplexingfaktorn (antal användare som schemaläggs samtidigt). Därefter implementeras en Q- inlärningsalgoritm för att anpassa dessa resurser efter det upplevda trafikbehovet och vilolägen som BS kan växla till när den är inaktiv. Ett viloläge innebär att viss hårdvara i BS stängs av. Resultatet visar att man genom att identifiera rätt typ av BS utifrån lokala trafikförhållanden kan få energibesparingar så höga som 60%. Vidare kan EF för en BS reduceras med 57% under den tid av dygnet då trafiken är som lägst genom att ha djupare vilolägen jämfört med basscenariot utan vilolägen. Genom att implementera Q-inlärningsalgoritmen som anpassar tillgängliga radioresurser till trafikbehovet minskar den genomsnittliga EF för BS ytterligare med upp till 20%. Vinsten i EE som erhålls av algoritmen beror dock till stor del på dess konvergens, som varierar med fördelningen av användarna i cellen, topptrafikbehovet och BS tillgängliga radioresurser. Resultatet visar att genom att kombinera resursanpassning med vilolägen kan man få betydande energibesparingar under varierande trafikbelastning. För att säkerställa tillförlitligheten av de erhållna resultaten betonas emellertid behovet av att garantera konvergensen av algoritmen innan den används för resursanpassning.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.
The recent climate change has forced people to live in extreme conditions, either excessive heat or cold, implying that they must adapt to survive in these situations. However, there are people who, because of their geographical condition and lack of resources, lack the means and tools to combat these climate changes. The context of this study is provided in a rural town located in the Arequipa region (Peru), whose inhabitants have to fight against frosts of up to −20 °C in an area without electricity. A viable solution to this problem is found through the design and implementation of a heating system using geothermal and photovoltaic energy, which are resources found in the area, according to a report of the Ministry of Energy and Mines. This study analyzes and researches the geographical and meteorological conditions of the region, for validating, through theory and simulations, whether the proposed system can supply the thermal energy required to maintain the indoor temperature at a minimum of 15 °C under extreme conditions. The system is designed after analyzing the best technological options and techniques currently available in the context studied for its ultimate financing and establishing guidelines and indicators for monitoring results.

Climate change is warming terrestrial ecosystems across the Earth’s surface. Along with increases in mean daily temperatures, heat waves are predicted to become more frequent, higher intensity and longer duration across the globe in future decades. Under these scenarios, it is vital to understand spatial and temporal variations in the thermal responses of metabolic processes across wide climatic gradients. Understanding the relative contributions of plasticity and evolutionary adaptation in thermal regulation of both photosynthesis and respiration in leaves is critical if we are to better predict future carbon fluxes and vegetation dynamics. This thesis research applied two widely used physiological measurements: temperature responses of leaf dark respiration (R-T) and temperature responses of dark-adapted minimal fluorescence (Fo-T). For R-T curves, R25 (leaf respiration at 25°C) and Tmax (i.e. high temperature at which rates of respiration are maximal were quantified, with the latter providing an estimate of respiratory heat tolerance (RHT). Fo-T curves were used to quantify the temperature (Tcrit) at which Fo rises rapidly as leaves are heated; this was used as a measure of photosynthetic heat tolerance (PHT). This thesis first investigated the components of thermal acclimation (plasticity) and inherent differences (evolutionary adaptation) in respiration and photosynthesis by combing field surveys and controlled environment studies. The thesis also explored mechanisms underlying variation in heat response of PHT. The above traits were quantified at six field sites representing five thermally contrasting biomes across Australia, and in temperature-controlled glasshouses using species sourced from four thermally contrasting origins. For the field study, measurements were made in summer and winter. The first major finding was that thermal acclimation of R25 was evident in the glasshouse study but not when comparing summer and winter values in the field. Second, both Tmax and Tcrit showed consistent acclimation both in the field and glasshouse, with both parameters increased as growth temperature increased. Tcrit differed inherently among species origins, whereas Tmax did not; ca. 40% of the variation in Tcrit could Abstract III be explained by variations in fatty acid composition of cellular membranes. These results imply both acclimation and inherent differences contribute to the contemporary patterns of PHT while only acclimation contributed to the patterns of RHT. The third major finding was that the dynamic responses of Tcrit to heat stress in a tropical tree species were closely related to dynamic changes in heat shock proteins (HSPs) abundance and membrane fatty acid composition, indicating HSPs and membranes are playing significant roles in the adjustments of PHT. Collectively, this thesis enhances our understanding on the ecological patterns of plant metabolic temperature responses. It also provides insights into the biochemical linkages underlying thermal responses of both respiration and photosynthesis. The findings point to more future studies in the plant field in linking ecological, physiological, biochemical and molecular perspectives of heat tolerance response.

This study provides a long-term understanding of the impact of climate varia-bility and land use on seasonal water balance conditions for sustainable agricul-ture development, hydropower generation and ecosystem stability in the Lower Rufiji Basin. The severity of soil drought, extreme flooding and salinity intru-sion in the lower Rufiji floodplains are currently increasing smallholder poverty and enhance the sensitivity on the natural wetlands for shifting farming and livestock pastures. The CoupModel and SWAT hydrological model were ap-plied to assess and compare the impact of climate variability on the water bal-ance. The monthly river discharge was used for calibrating and validating the runoff at the Stiegler's Gorge. The simulated results for water balance compo-nents at Stiegler's Gorge showed 55% of accumulated precipitation is lost through evapotranspiration and 42 % is river runoffs for downstream agricul-ture and ecosystem services. The evaluation of the models simulation perfor-mance and posterior distribution of parameter behavioral value indicates the (GLUE) calibration method in the CoupModel agreed satisfactory with the Bayesian calibration (BC). The minimal variance in the Bayesian Calibration posterior parameter distribution was observed in the parameter for regulating water uptake from (CritThresholDry) and soil moisture availability for soil evaporation(PsiRs_ip). The SWAT simulation showed that south of the central floodplains has high risk of soil drought. The overall assessment implies that drought and river runoff dynamics in the LRB is affected by upstream land use activities. The strategies for building smallholder resilience towards climate change and land use impact requires collective and coordinated water manage-ment actions powered by individual, institutional, financial and technological adaptation.

Despite the increasing prevalence of obesity and the array of treatment modalities available, maintenance of reduced-weight in the long-term is uncommon. The reason(s) why weightregain is so commonplace remains contentious. The primary purpose of this dissertation was to determine the extent to which weight-loss in obese adults, when the intervention included an optimal exercise prescription, resulted in adaptations that may be considered aberrant and reflect risk of weight-regain. Unique to this investigation was the multifactorial approach to addressing the issue of adaptation through consideration of metabolic, physiological, and psychosocial factors. Accurate body composition assessment is a fundamental requirement upon which evaluation of adaptation to weight-loss is based. An additional purpose of the dissertation was to evaluate multi-frequency bioelectrical impedance analysis (MFBIA) as a technique for use in assessing body composition change of obese adults during weight-loss. Further, optimal weight management requires an incorporation of effective exercise prescription. Therefore, a final aim of the dissertation was to determine the optimal exercise intensity for weight management. Together the goals of this thesis were addressed through a series of studies, the first three relate to use of bioelectrical impedance analysis; the fourth and fifth studies were associated with exercise prescription for obese adults; and the final study, incorporating three components, dealt with adaptation to weight-loss in the obese. In the first study, twenty-nine young healthy adults, 17 males and 12 females (mean± SEM; 21.8 ± 0. 7 yrs and 20.3 ± 0.3 yrs) were recruited to assess the technical reliability (i.e., interinstrument and inter-operator reliability) of three MFBIA monitors. Technical reliability was assessed for both errors of measurement and associated analyses. In addition, intra-operator and intra-instrument variability was evaluated for repeat measures over a 4-hour period. The measured impedance values from a range of resistance-capacitance circuits were accurate to within 3 percent of theoretical values over a range of 50- 800 ohms. Similarly, phase was measured over the range 1 degrees-19 degrees with a maximum deviation of 1.3 degrees from the theoretical value. The extrapolated impedance at zero frequency was equally well determined (+/-3 percent). However, the accuracy of the extrapolated value at infinite frequency was decreased, particularly at impedances below 50 ohms (approaching the lower limit of the measurement range of the instrument). The inter-instrument/operator variation for whole body measurements were recorded on human volunteers with biases of less than +/-1 percent for measured impedance values and less than 3 percent for phase. The variation in the extrapolated values of impedance at zero and infinite frequencies included variations due to operator choice of the analysis parameters but was still less than +/-0.5 percent. The second study investigated the effect of moving from standing to lying supine on blood and plasma volumes, serum electrolyte concentrations, and measurements of whole-body impedance using MFBIA over a 60 minute period in 12 subjects (8 males, 4 females) 26.7 ± 5.5 yrs, 172.3 ± 6.9 em, and 71.0 ± 7.7 kg. While no significant differences were found in serum sodium, chloride or potassium concentrations as a function of the posture change, estimates of both blood and plasma volumes increased during the 60 minutes spent supine. Blood volume increased by 10.5 (4.2 to 16.4)percent and plasma volume increased 10.5 (5.0 to 17.6)percent. Similarly, whole-body resistivity measured at 50 kHz increased significantly by 24.1 (6.3 to 36.5) Q in absolute values across the hour supine, with the measurement at 60 minutes reflecting a 4. 7 ( 1.3 to 6. 7)percent increase in resistivity from the baseline measure. Although the weight lost across the hour was only 0.11 (0.05 to 0.15) kg, the change in total body water estimated from resistivity measures is likely to be significantly larger. The results from this study reflect the need for implementation of a standardised preparatory rest time prior to taking BIA measurements, and demonstrate the limitations associated with a single frequency, whole-body approach for assessing body-fluid distribution. The purpose of the third study was to validate the use of MFBIA to determine change in body composition of obese adults during weight reduction by direct comparison with total body water as measured by stable-isotope dilution. Specifically, the study had three parts. Firstly, from the data obtained on the total sample at baseline, the aim was to develop a prediction equation for the estimation ofTBW from MFBIA. The second aim was to validate the prediction equation in a subsample during (wk-5) and after the completion of a 12-wk weight-loss intervention. The final aim of the study was to determine whether intervention type influenced the accuracy of TBW predicted by MFBIA. Multiple regression analysis revealed that the MFBIA-derived prediction equation prior to weight-loss was able to determine TBW with a SEE of 1.9L by combining the impedance index (Ht2/R10o), age, gender, and body weight. However, during weight-loss, the comparison of TBW predicted by MFBIA and measured with deuterium dilution had a much larger bias than after completion of the weight-loss intervention. It was further revealed that the magnitude of the bias was influenced by the intervention mode, with those individuals on a very-low-energy diet recording greater measurement bias. These results raise concern for the accuracy of MFBIA during periods of weight-loss in obese adults. In particular, weight-loss elicited through severe restriction in dietary intake appears most problematic. In contrast, the post-intervention TBW measures determined from the MFBIAequation derived at baseline had a mean difference of only 0.9L relative to the group mean derived by deuterium dilution. Further, using the impedance index alone post-intervention, the mean TBW measures were within 0.5L of the mean reference measure. In the fourth study the relative and absolute levels of exercise intensity corresponding with the lactate threshold (LT) and ventilatory threshold (Tvent) were determined in forty-two sedentary obese adults, 23 females and 19 males (42.9±1.8 yrs; 36.8±0.9 kg.m-2 ). Subjects were obese but otherwise healthy and taking no medication known to modifY heart rate. Subjects were required to attend a testing session each week for three weeks scheduled for the same time of day, and day of the week. The three sessions involved: (1) a treadmill test to assist in subject familiarisation. The test enabled researchers to gauge working capacity and enable subjects to become accustomed with the treadmill and gas analysis apparatus; (2) a discontinuous graded treadmill test to assess cardiorespiratory function; and (3) assessment of body composition and resting metabolic rate. On two separate occasions subjects undertook a discontinuous graded treadmill walking test consisting of 4-minute work stages separated by 2-minute rest periods. During the last 30 seconds of each work stage, subjects rated perceived exertion (RPE) using the Borg 6-20 scale. Immediately on completion of each work stage, duplicate blood samples were collected by finger prick, haemolysed in 1 OO)ll of chilled perchloric acid, and stored for later blood lactate analysis. Throughout both tests HR was recorded and respiratory gases were collected and analysed. Resting metabolic rate was assessed by indirect calorimetry using a ventilated hood system. The major finding of this study was that corresponding with LT and Tvent respectively, the relative intensities defined as percentV02R (63.4±1.4 percent; 63.8±1.8 percent), percent HRR (65.2±1.6 percent; 66.6±1.5 percent) and percent HRpeak (78.2±1.0 percent; 79.2±1.0 percent), and the absolute intensity defined by METs calculated physiologically would be categorised as "hard" by the current guidelines. In contrast, at L T and T vent the relative intensity defined by RPE (12.6±0 .2; 12.8±0.3), and absolute intensity defined by METs calculated from mechanical parameters (4.8±0.2; 5.0±0.2), fall into the "moderate" intensity category. Therefore, there is a need to redefine the descriptors of exercise intensity for the obese population. Further, linear regression analysis revealed a relatively strong negative relationship (r=-0.58, P<0.001) between HRLT and age , and the addition of gender to the regression analysis improved the strength of the prediction equation (HRLr = 145.6- 0.623* Age(yrs) + 9.824*Gender (M=l, F=2) r=-0.70, P<0.001). Importantly, the intensity thresholds tested were at a level well tolerated by the obese population, and considered to be of moderate intensity. The purpose of the fifth study was to identify optimal aerobic exercise intensity for obese adults and to compare this with the relative and absolute intensity categories outlined in current guidelines provided by the Surgeon General (U.S. Dept. HHS, 1996) and American College of Sports Medicine (ACSM, 1995; 1998). In particular, the equivalence between submaximal markers of exercise intensity, challenged recently in studies of trained and recreational athletes and chronic obstructive pulmonary disease sufferers, was evaluated for the first time in obese adults. Using a testing procedure outlined in Study 4, data was assessed from 32 obese adults (15 males and 17 females), 42.1 ± 1.7 yrs and 37.4 ± 1.0 kg.m-2. The study showed that in the obese [1] the percent HRpeak-percent V02peak relationship was significantly greater than ACSM recommendations; [2] the percent HRR was equivalent with percent V02R not percent V02peak; and [3] exercise prescription at fixed percentages of V02peak or HRpeak corresponded with wide ranges of exercise intensities in relation to LT. These results together with those from Study 4 demonstrated for the first time that current exercise prescription guidelines for the obese are too conservative, particularly where optimising the exercise-induced benefits for weight management are concerned. The final study was based upon the hypothesis that weight-regain is attributed more to behavioural adaptations than to compensatory metabolic processes. The purpose of this randomised-control intervention was to ascertain the extent to which metabolic, physiological, and psychosocial factors adapt in obese adults during a period of weight decrement. Additionally, it was hypothesised that metabolic adaptation is related to the rate of weight-loss, the mode facilitating the energy deficit responsible for the weight-loss, and the tissue composition of the weight that is lost. In particular the study goal was to determine what evidence there is that loss of body weight results in metabolic, physiological, or psychosocial adaptations that are aberrant. Forty-eight obese adults (22 males and 26 females) on average 42.9 ± 1.8 years, 107.2 ± 3.4 kg, and 36.8 ± 0.9 kg.m-2 were recruited. Subjects were matched for gender, age, and BMI before being randomly assigned to very-low-energy diet plus exercise (VLED+Ex), low-fat diet plus exercise (LF+Ex), or control (C) groups. In the first two weeks, subjects undertook two treadmill tests to determine cardiorespiratory capacity and the relationship between submaximal markers of exercise intensity at increasing workloads. In the third week, all subjects underwent testing of baseline measures of resting metabolic rate, body composition, thyroid hormone function, blood lipid profile, body satisfaction and self-reported health. After this period, subjects followed the VLED+Ex, LF+Ex or C program for the following 12 weeks. For VLED+Ex and LF+Ex body composition and metabolic measures were repeated after the 4th and 8th week of the intervention. All measurements were repeated in the week following completion of the intervention, week 16 of the study program. Forty-two subjects completed the 16-week study. Collectively, the results from the weight-loss intervention do not support the notion that weightloss in obese adults results in aberrant changes in metabolic, physiological or psychosocial variables that would in turn place the reduced-obese adult at risk of weight regain. In particular, perception of size for both males and females post-intervention was strongly related with body weight (r = 0.71 and r = 0.89 for males and females respectively), relative weight (r = 0.81, r = 0.86), and BMI (r = 0.81, r = 0.84). While positive correlations were found between the magnitudes of change in body size and body satisfaction, self-reported health improved and limitations to daily physical activity were reduced in both intervention groups when compared with the control group at the completion of the intervention period. Overall, there was no evidence with respect to psychosocial factors that the intervention and concomitant change in body size was perceived negatively, and in many respects the greater the change in body size the greater the perceived benefit. In terms of physiological adaptation, participation in 12 weeks of aerobic endurance and resistance weight training was positively reflected in improvements in cardiorespiratory fitness, with an average improvement in maximal aerobic capacity (L.min-1 ) of 17.7 percent and 13.1 percent in the VLED+Ex and LF+Ex groups respectively. The energy-cost of exercise at LT did not change significantly with weight-loss and thus exercise prescribed at LT for the reduced-obese adult would as effective for increasing energy expenditure through physical activity as was shown at baseline. Although not reaching statistical significance, the time required to expend the energy suggested as necessary for weight maintenance was reduced by an average of 9 percent and 8 percent in the VLED+Ex and LF+Ex groups respectively. In terms of metabolic adaptation, the findings were somewhat conflicting depending upon the manner of comparing energy expenditure in people before and after a change in body size. Data was analysed via four different statistical approaches cited in the literature. Analysis of covariance with FFM (the variable most strongly explaining the variance in RMR measures) as the covariate revealed no significant differences in RMR between groups at any time point during the study. Comparing the actual RMR-FFM regression lines for each group before and after the intervention revealed that the slopes and intercepts of the RMR-FFM relationships did not alter significantly after weight-loss. In contrast, the third and fourth series of analyses in which predicted and observed measures ofRMR were compared pre and post intervention, and the change in FFM related to change in resting oxygen consumption were compared, were conflicting. However, it was proposed that these somewhat conflicting results may be explained by the influence of the energetic contribution of organ tissue to total FFM energetics. As would be expected, during the intervention changes in RQ reflected the nature of the dietary intervention. However, unexpectedly at the completion of the intervention the group that lost weight most rapidly had an RQ that was not significantly different from the values at baseline. The findings do not support the notion purported by previous research that weight-loss, and in particular rapid weight-Joss, increases the reliance on carbohydrate oxidation in the reduced-obese state and thus increasing the risk of weight regain. It may be concluded from the RMR and RQ data that as a function of endurance exercise training the adverse consequences cited in studies where weight is lost through dietary restriction alone are ameliorated. Finally, the VLED+Ex group had significantly reduced concentrations offT4, T4, T3 and IT3 at the completion of the intervention relative to baseline. However, the change in hormone concentration was not related to the change in body weight or FFM for any of the hormones. Further, all subjects were euthyroid throughout the intervention. Therefore, while rapid weightloss results in statistically significant reductions in thyroid hormones, determining whether this reflects clinically significant and persistent down-regulation of endocrine function, and thus reduced metabolic potential, requires further investigation.

Doutoramento em Ciências e Engenharia do Ambiente
As cidades, áreas que albergam cerca de 70% da população europeia, enfrentam hoje um conjunto de desafios associados a alterações do metabolismo urbano, que num contexto de alteração climática (AC), afectam o microclima urbano e a qualidade do ar (QA). Compreender a interação entre as AC, qualidade do ar e fluxos urbanos de calor (FUC) é um tópico de investigação emergente, reconhecido como área de interesse para a definição e implementação de políticas locais. O principal objetivo do presente trabalho é promover uma avaliação integrada das interações entre medidas de resiliência urbana e as AC, e respectiva influência no microclima urbano, QA e FUC, tendo como caso de estudo a cidade do Porto (Portugal). Pretende-se ainda impulsionar o desempenho dos modelos numéricos para que estes representem realisticamente os fenómenos físicos que ocorrem nas áreas urbanas. Para atingir este objetivo, o sistema de modelos WRF-SUEWS foi aplicado para a área de estudo para avaliar a influência de diferentes níveis de área urbanizada nas trocas de calor entre a superficie e a atmosfera. O modelo foi validado mediante a comparação dos seus resultados com dados medidos obtidos em campanhas de monitorização de fluxos. A influência das variáveis meteorológicas nos FUC, e a forma como estas, por sua vez, são influenciadas pela superfície urbana foi também avaliada. Para tal, o sistema WRF-SUEWS foi aplicado para 1-ano representativo de um período de clima presente (1986-2005) e de clima futuro de médio prazo (2046-2065). O cenário climático futuro foi projetado tendo por base o cenário RCP8.5. Esta análise permitiu quantificar e mapear os efeitos das AC nos FUC na cidade do Porto. Face à necessidade corrente de aumentar a resiliência urbana a futuros eventos meteorológicos extremos (e.g. ondas de calor), o sistema WRF-SUEWS foi ainda aplicado (com uma resolução espacial de 200 m) para avaliar a influência de medidas de resiliência nos FUC. Conhecendo a importância da morfologia urbana para as características do seu próprio clima, um conjunto de parameterizações urbanas (LSM, SUEWS e UCM) foram analisados para área de estudo, por forma a obter uma representação realista das características urbanas no modelo WRF e, consequentemente, obter um melhor desempenho na modelação da QA à escala local. Os resultados revelaram que o modelo UCM é a parameterização urbana que melhor representa os fluxos turbulentos de calor, a temperatura e velocidade do vento à superfície. Como resultado, o modelo CFD VADIS, inicializado pelo modelo WRF-UCM, foi aplicado com uma elevada resolução espacial (3 m) a um bairro típico da cidade do Porto. As simulações realizadas permitiram caracterizar o estado atual da QA na área de estudo, bem como avaliar a influência de diferentes medidas de resiliência nos padrões de velocidade do vento e na concentração de poluentes atmosféricos (PM10, NOX, CO e CO2). Este trabalho constitui uma ferramenta científica inovadora no que diz respeito ao conhecimento dos processos físicos que ocorrem à escala urbana, proporcionando uma visão integradora entre AC, QA e FUC. Estes resultados são relevantes para o apoio à decisão política do que respeita à implementação de estratégias que permitam aumentar a resiliência urbana, nas suas diversas vertentes, a um clima em mudança
Cities, home of about 70% of the European population, are facing important challenges related to changes in urban structure and its metabolism, and to pressures induced by climate change (CC) effects, which are affecting urban microclimate and air quality. The better understanding of the interactions between CC, air quality and urban surface energy balance (USEB) is an emerging priority for research and policy. The main objective of the current study is to provide an integrated assessment of the interaction between resilience measures and CC effects, and its influence on the urban microclimate and air quality as well as on the USEB, having as case study the city of Porto (Portugal). The ultimate goal is to improve the accuracy of numerical modelling to better represent the physical processes occurring in urban areas. For this purpose, the relevant parameters to both USEB and air quality were analysed. The WRF-SUEWS modelling setup was applied to the study area to assess the influence of different levels of urbanization on the surface-atmosphere exchanges. To validate the modelling setup, the results were compared with measurements carried out on field campaigns. The way of how the meteorological variables affect the USEB and how, in turn, these variables are themselves affected by urban surface was also assessed. The modelling setup was applied for 1-year period statistically representative of a present (1986-2005) and medium-term future (2046-2065) climate. The climate projection was produced under the RCP8.5 scenario. This analysis gives insights of how the urban-surface exchanges will be affected by CC, allowing the mapping of the FUC over the study area. As result of the need of increase cities resilience to future extreme weather events (e.g. heat waves), the WRF-SUEWS model (with a spatial resolution of 200 m), was applied to Porto city to evaluate the influence of a set of resilience measures on the USEB. Knowing the importance of urban surfaces to its own microclimate, a set of urban parameterization schemes (LSM, SUEWS and UCM) were analysed for the study area, to achieve a more accurate representation of urban features in the WRF model and, in consequence, to improve the capability of air quality modelling at urban/local scale. The results point out that the UCM is the urban parameterization that provides a more realistic representation of the turbulent energy fluxes and the near-surface air temperatures and wind speed. As result, a CFD modelling (VADIS), forced by WRF-UCM, was used to provide a set of numerical simulations with a high spatial resolution (3 m) over a typical neighbourhood in the Porto city. These simulations allow the characterization of the current air quality status over the study area, as well as the assessment of the influence of different resilience measures in the wind flow and air pollutants dispersion (PM10, NOX, CO and CO2). Overall, this research work is a step forward in understanding the physics of urban environments, providing also a linkage between CC, air quality and USEB. These findings are highly advantageous to support policy makers and stakeholders helping them to choose the best strategies to mitigate extreme weather events and air pollution episodes and so increase cities resilience to a future climate.

As software applications are becoming increasingly distributed and mobile, their design and implementation are characterized by distributed software architectures, possibility of faults, and the need for energy awareness. Thus, software developers should be able to simultaneously reason about and handle the concerns of distribution, fault-tolerance, and energy-efficiency. Being closely intertwined, these concerns can introduce significant complexity into the design and implementation of modern software. In other words, to develop reliable and energy-efficient applications, software developers must understand how distribution, fault-tolerance, and energy-efficiency interplay with each other and how to implement these concerns while keeping the complexity in check. This dissertation addresses five technical issues that stand on the way of engineering reliable and energy-efficient software: (1) how can developers select and parameterize middleware to achieve the requisite levels of performance, reliability, and energy-efficiency? (2) how can one streamline the process of implementing and reusing fault tolerance functionality in distributed applications? (3) can automated techniques be developed to help transition centralized applications to using cloud-based services efficiently and reliably? (4) how can one leverage cloud-based resources to improve the energy-efficiency of mobile applications? (5) how can middleware be adapted to improve the energy-efficiency of distributed mobile applications operated over heterogeneous mobile networks? To address these issues, this research studies the concerns of distribution, fault-tolerance, and energy-efficiency as well as their interaction. It also develops novel approaches, techniques, and tools that effectively fuse and separate these concerns as required by particular software development scenarios. The specific innovations include (1) a systematic assessment of the performance, conciseness, complexity, reliability, and energy consumption of middleware mechanisms for accessing remote functionality, (2) a declarative approach to hardening distributed applications with resiliency against partial failure, (3) cloud refactoring, a set of automated program transformations for transitioning to using cloud-based services efficiently and reliably, (4) a cloud offloading approach that improves the energy-efficiency of mobile applications without compromising their reliability, (5) a middleware mechanism that optimizes energy consumption by adapting execution patterns dynamically in response to fluctuations in network conditions.
Ph. D.

The ability to swim and navigate the surrounding environment confers an advantage to motile bacteria, allowing the occupation of niches that are optimum for survival and growth. Bacteria are too small to sense their environment spatially, so they must sense the environment temporally by comparing the past and present environments and altering their motility accordingly. Chemotaxis systems coordinate flagellar motility responses with temporal sensing of the environment. Chemotaxis is proposed to be involved in plant root colonization by directing soil bacteria toward root exudates of various cereals, promoting growth. The nitrogen-fixing alpha-proteobacterium Azospirillum brasilense utilizes chemotaxis to navigate its environment by integrating various environmental signals into a chemotaxis signal transduction pathway. In chemotaxis, transducers receive environmental sensory information and transmit the signal to the histidine kinase CheA, which relays the signal to the response regulator CheY. A novel chemotaxis transducer, Tlp1, has been identified and characterized as an energy sensor by constructing a tlp1 mutant and performing behavioral and root colonization assays. In order to adapt to changing environmental conditions, chemotactic microorganisms must employ a molecular “memory” comparing present environmental conditions to ones previously experienced and resetting the chemotaxis transducer to a prestimulatory status. A recently identified chemotaxis operon revealed a methyltransferase CheR and methylesterase CheB, comprising an adaptation system, suggesting that A. brasilense undergoes methylation-dependent taxis responses, contrary to previous reports. Chemotaxis and methanol release assays suggest that adaptation by methylation in locomotor behavior involves the presence of other unknown methylation systems, and the contribution of CheR and CheB to chemotactic and aerotactic responses is complex. There is growing evidence that chemotaxis-like signal transduction pathways control a myriad of other cellular processes regulated in a temporal fashion. This would convey an advantage to cells by allowing modulation of cellular processes based on slight changes in environmental conditions and provide checkpoints for energetically consuming processes. Mutations in components of the chemotaxis-like signal transduction system revealed differences in cell size and exopolysaccharide production. This work shows that the signal transduction pathway of A. brasilense modulates cell length in response to changes in nutrient conditions, independently of growth rate.

Cette thèse s’intéresse aux stratégies comportementales et physiologiques permettant à un oiseau colonial, le manchot royal, de se reproduire sous de fortes contraintes énergétiques (jeûne prolongé) et sociales (forte densité de congénères) potentiellement stressantes. Utilisant la fréquence cardiaque (FC) comme indicateur de la dépense énergétique et de la réponse au stress, elle considère : 1) le coût énergétique des comportements majeurs (confort et agressivité) du manchot royal se reproduisant à terre, questionnant leur signifiance évolutive; 2) les changements physiologiques (FC, température corporelle, activité physique) associés au jeûne reproductif le plus long (1 mois), révélant que la FC de repos des animaux est fortement influencée par la densité coloniale et suggérant un coût énergétique de la vie en groupe; 3) L’influence de l’environnement social, indiquant que lors d'interactions agressives la réponse cardiaque des animaux est modulée par leur implication dans l'interaction et par le risque associé; 4) Les effets du statut nutritionnel et reproductif sur les réponses cardiaques, hormonales et métaboliques à différents stress anthropiques aigus, démontrant que ces réponses varient en fonction de la valeur relative de la reproduction (œuf vs. Poussin). L’atténuation de ces réponses, coûteuses en énergie et pouvant conduire à l'abandon de la progéniture, permettrait d’augmenter le succès reproducteur lorsque la valeur de la reproduction en cours est élevée. Des recherches futures permettront de déterminer les conséquences physiologiques (coût énergétique, stress oxydatif, vieillissement) du stress social chez des espèces vivant en groupe
This thesis investigates the behavioral and physiological strategies that allow a colonial breeder, the king penguin (Aptenodytes patagonicus), to breed while fasting in a crowded, possibly stressful, social environment. First, by monitoring penguin heart rate (HR) as a proxy to energy expenditure, it considers the energy cost of the most common behaviors (comfort and aggressive behavior) of penguins breeding ashore, and questions the adaptive significance of high and low, respectively, energy investment into these two behaviours. Second, it investigates the physiological changes that occur during the longest breeding fast (1 month) by continuously recording HR, body temperature and physical activity in incubating males. It reveals that changes in colony density (i. E. Crowding) may have a strong impact on the energy expended to fuel metabolism at rest, i. E. First evidence for an energy cost of group-living in birds. Third, it shows that penguins are highly sensitive to the social environment, as indicated by changes in HR responses to aggressive contexts of various relevance and associated risks. Fourth, it investigates the effects of breeding status on costly stress responses (hormonal, metabolic and cardiac). It shows that responses to acute stress decrease with increasing reproductive value of the offspring (egg vs. Chick), suggesting that stress responses may be adaptively attenuated to improve breeding success and fitness, when reproductive value of the current reproduction is high. Further research is needed to investigate the physiological consequences (energy expenditure, oxidative stress, aging) of social stress in group-living animals

The heat demand in Sweden has stagnated and district heating companies must take action to sustain in the market. Based on this background this study combines a PEST and SWOT analysis to produce a basis to suggest general strategies suitable for district heating companies in southern Sweden. The analysis found that both investments into activities outside of the heating market, as well as further development of current systems, are viable options. Increasing the awareness and knowledge about district heating companies was also identified as a factor that could entail several benefits.

L'énorme quantité de données dans les réseaux de capteurs vidéo sans fil (WVSN) pour les nœuds de capteurs de ressources limitées augmente les défis liés à la consommation d'énergie et à la consommation de bande passante. La gestion du réseau est l’un des défis de WMSN en raison de l’énorme quantité d’images envoyées simultanément par les capteurs au coordinateur. Dans cette thèse, pour surmonter ces problèmes, plusieurs contributions ont été apportées. Chaque contribution se concentre sur un ou deux défis, comme suit: Dans la première contribution, pour réduire la consommation d'énergie, une nouvelle approche pour l'agrégation des données dans WVSN basée sur des fonctions de similarité des plans est proposée. Il est déployé sur deux niveaux: le niveau du nœud du capteur vidéo et le niveau du coordinateur. Au niveau du nœud de capteur, nous proposons une technique d'adaptation du taux de trame et une fonction de similarité pour réduire le nombre de trames détectées par les nœuds de capteur et envoyées au coordinateur. Au niveau du coordinateur, après avoir reçu des plans de différents nœuds de capteurs voisins, la similarité entre ces plans est calculée pour éliminer les redondances. Dans la deuxième contribution, certains traitements et analyses sont ajoutés en fonction de la similarité entre les images au niveau du capteur-nœud pour n'envoyer que les cadres importants au coordinateur. Les fonctions cinématiques sont définies pour prévoir l'étape suivante de l'intrusion et pour planifier le système de surveillance en conséquence. Dans la troisième contribution, sur la phase de transmission, au niveau capteur-nœud, un nouvel algorithme d'extraction des différences entre deux images est proposé. Cette contribution prend également en compte le défi de sécurité en adaptant un algorithme de chiffrement efficace au niveau du nœud de capteur. Dans la dernière contribution, pour éviter une détection plus lente des intrusions conduisant à des réactions plus lentes du coordinateur, un protocole mac-layer basé sur le protocole S-MAC a été proposé pour contrôler le réseau. Cette solution consiste à ajouter un bit de priorité au protocole S-MAC pour donner la priorité aux données critiques
The huge amount of data in Wireless Video Sensor Networks (WVSNs) for tiny limited resources sensor nodes increases the energy and bandwidth consumption challenges. Controlling the network is one of the challenges in WMSN due to the huge amount of images sent at the same time from the sensors to the coordinator. In this thesis, to overcome these problems, several contributions have been made. Each contribution concentrates on one or two challenges as follows: In the first contribution, to reduce the energy consumption a new approach for data aggregation in WVSN based on shot similarity functions is proposed. It is deployed on two levels: the video-sensor node level and the coordinator level. At the sensor node level, we propose a frame rate adaptation technique and a similarity function to reduce the number of frames sensed by the sensor nodes and sent to the coordinator. At the coordinator level, after receiving shots from different neighboring sensor nodes, the similarity between these shots is computed to eliminate redundancies. In the second contribution, some processing and analysis are added based on the similarity between frames on the sensor-node level to send only the important frames to the coordinator. Kinematic functions are defined to predict the next step of the intrusion and to schedule the monitoring system accordingly. In the third contribution, on the transmission phase, on the sensor-node level, a new algorithm to extract the differences between two images is proposed. This contribution also takes into account the security challenge by adapting an efficient ciphering algorithm on the sensor node level. In the last contribution, to avoid slower detection of intrusions leading to slower reactions from the coordinator, a mac-layer protocol based on S-MAC protocol has been proposed to control the network. This solution consists in adding a priority bit to the S-MAC protocol to give priority to critical data

Ultrawideband (UWB) is one of the promising technologies for future short-range high data rate communications (e.g. for wireless personal area networks) and longer range low data rate communications (e.g. wireless sensor networks).Despite its various advantages and potentials (e.g. low-cost circuitry, unlicensed reuse of licensed spectrum, precision ranging capability etc.), UWB also has its own challenges. The goal of this dissertation is to identify and address some of those challenges, and provide a framework for practical UWB transceiver design.In this dissertation, various modulation options for UWB systems are reviewed in terms of their bit error rate (BER) performances, spectral characteristics, modem and hardware complexities, and data rates. Time hopping (TH) code designs for both synchronous (introduced an adaptive code assignment technique) and asynchronous UWB impulse radio (IR) systems are studied. An adaptive assignment of two different multiple access parame ters (number of pulses per symbol and number of pulse positions per frame)is investigated again considering both synchronous and asynchronous scenarios, and a mathematical framework is developed using Gaussian approximations of interference statistics for different scenarios. Channel estimation algorithms for multiuser UWB communication systems using symbol-spaced (proposed a technique that decreases the training size), frame-spaced (proposed a pulse-discarding algorithm for enhanced estimationperformance), and chip-spaced (using least squares (LS) estimation) sampling are analyzed.A comprehensive review on multiple accessing andinterference avoidance/cancellation for IR-UWB systems is presented.BER performances of different UWB modulation schemes in the presence of timing jitter are evaluated and compared in static and multipath fading channels, and finger estimation error, effects of jitter distribution, and effects of pulse shape are investigated. A unified performance analysis app roach for different IR-UWB transceiver types (stored-reference, transmitted-reference, and energy detector) employing various modulation options and operating at sub-Nyquist sampling rates is presented. The time-of-arrival (TOA) estimation performance of different searchback schemesunder optimal and suboptimal threshold settings are analyzed both for additive white Gaussian noise (AWGN) and multipath channels.

Can rural renewable energy projects simultaneously meet the multiple goals of sustainable development, climate change mitigation and climate change adaptation? If so, under what conditions? Rural communities throughout Latin America have increasingly suffered the impacts of climate change and few policies exist to help them adapt to these impacts. The basic infrastructure and services that they frequently lack can be provided by low carbon technologies, potentially funded by international carbon finance flows that could enable the Millennium Development Goals of economic growth and poverty alleviation to be met while minimizing carbon emissions. This research will focus on this interrelationship among development, climate change mitigation and climate change adaptation policies and practices using political ecology to analyse community renewable energy projects in rural Central America. I assess fifteen community-owned renewable energy projects in Guatemala and Nicaragua to analyse whether current renewable energy projects are achieving these goals in an integrated way. The projects were established primarily as development, emissions reductions, climate change adaptation and disaster relief. The projects are evaluated on economic, development and climate change indicators that include sustainable development, poverty alleviation, emissions reductions, and climate vulnerability. I examine how the type of common property governance, local historical and environmental background and project implementation process influence the project success in meeting multiple objectives of climate adaptation, mitigation and development. Research methods include participatory poverty assessment techniques, semi-structured interviews, stakeholder analysis, and a combination of rapid and participatory methods. The analysis of sustainable development and vulnerability used the Sustainable Livelihoods Approach methodologies and emissions reductions were calculated using standard carbon reduction methodologies. The results show that, under certain conditions, renewable energy projects can simultaneously meet these three objectives, and thus that responses to climate change can be integrated with poverty alleviation and sustainable development. Small scale hydroelectric and solar systems can reduce emissions, enable adaptation and help local livelihoods although there are numerous problems that limit the success of projects including poor design, inequitable distribution of benefits, and poorly designed governance and maintenance structures.

Les défis énergétiques contemporains sont multidimensionnels, car ils sont à la fois économiques, sociaux et environnementaux. Ils sont également mondiaux, connexes et transversaux. Ils sont néanmoins saisis dans leur globalité par le droit international, même si celui-ci manifeste des insuffisances dans son approche. Celles-ci tiennent à l’appréhension imparfaite, d’une part, de la dimension stratégique des enjeux, intimement liés au principe de souveraineté, et, d’autre part, des risques environnementaux et humains. Pour autant, ces insuffisances n’enlèvent en rien la capacité du droit international à s’adapter à ces défis. Son adaptation est amorcée avec la prise en compte de leur caractère transversal et de la solidarité qui en découle. Elle est également consolidée par l’émergence d’une finalité nouvelle et inclusive, l’accès universel à l’énergie durable, et par la recherche d’une démocratie énergétique. Le droit international porte donc en lui tous les outils propres à lui permettre, non seulement d’accompagner la transition énergétique, mais aussi de la dynamiser
Current energy challenges are multidimentional in nature as they blend together the economic, social, and environmental fields. They are also global, interconnected and transversal. Energy challenges are apprehended globally by international law, despite some shortcomings. Those shortcomings stem from the strategic nature of energy challenges and their simultaneous dependance on sovereignty. They also come to light in the context of environmental risks and risks of harm to humans. Yet, those shortcomings do not deprive international law of its capacity to adapt to energy challenges. It shows adaptation by taking into account their transversal character and the correlated necessity for solidarity. The inclusive and new finality of pursuing universal access to sustainable energy and the efforts shown toward energy democracy yet reinforce this adaptability. Thus, international law exibits all the tools necessary to help, and also be an engine for the energy transition

Climate change effects are getting more evident year by year. Athens is specially affected by climate change related shocks, especially by poor air quality, flooding and heat waves. Every year climate shocks threatens and worsens the situation in the city. The municipality of Athens, together with the European Investment Bank and EQO-NIXUS (consulting company) have undertaken a project in order to increase the resilience and the mitigation and adaptation measures of the city, taking as case study 5 public buildings located in different areas of the centre of the city. This project is in line with the Athens Resilience Strategy drawn by the Municipality of Athens in order to integrate new ways to prepare and protect the city from future shocks and stresses. This study aims to investigate and propose mitigation and adaptation measures that could be potentially applied into the 5 selected public buildings in order to improve the energy efficiency and the resilience towards heat waves, flooding and pollution of the air. A literature review study has been performed in order to look for good practices worldwide in terms of energy efficiency and climate mitigation and adaptation in order to find the best measures that could be applied in the 5 selected buildings. Finally, a multi-criteria decision analysis has been executed to prioritise which measures result to be more relevant for each specific building. The study shows that, in overall, energy efficiency and raise of public awareness are the most relevant measures that can be potentially applied in the buildings in order to tackle the climate shocks that threatens Athens. Finally, if the measures are applied into the buildings and the resilience and energy efficiency measures are improved, this study could be replicated to other buildings of Athens in order to achieve the 2030 strategy plan set by the municipality of Athens.
Effekterna av klimatförändringen blir alltmer tydliga. Greklands huvudstad Aten påverkas exempelvis av försämrad luftkvalitet, översvämningar och värmeböljor och extrema klimatrelaterade händelser förvärrar situationen i staden. Atens kommun har tillsammans med Europeiska investeringsbanken och EQO-NIXUS (ett privat konsultföretag) genomfört ett projekt för att öka motståndskraften mot klimatförändringens effekter, genom anpassningsåtgärder, där fem offentliga byggnader i olika delar av Atens centrum studeras. Projektet är relaterat till Atens resiliensstrategi som handlar om hur staden ska integrera nya sätt förbereda och skydda staden och dess invånare från framtida extrema händelser och påfrestningar. Denna studie syftar till att undersöka och föreslå anpassningsåtgärder som potentiellt kan tillämpas i de fem olika offentliga byggnaderna för att förbättra energieffektiviteten och resiliensen mot värmeböljor, översvämningar och luftföroreningar. En litteraturstudie har genomförts för att identifiera globala, goda exempel när det gäller energieffektivitet och anpassning till ett förändrat klimat som potentiellt kan tillämpas i de fem byggnaderna. Slutligen har en multikriterieanalys med flera kriterier genomförts för att prioritera vilka åtgärder som är mest relevanta för varje specifik byggnad. Studien visar att energieffektivitet och ökning av allmänhetens medvetenhet totalt sett är de mest relevanta åtgärderna som potentiellt kan tillämpas i byggnaderna för att hantera klimatförändringar. Slutligen, om dessa åtgärder tillämpas och resiliensen och energieffektivitetsåtgärderna förbättras, skulle denna studie kunna vara relevant även för andra byggnader i Aten och därmed bidra till uppfyllelsen av stadens 2030-strategi.

Global warming induced by the emissions of greenhouse gases is one of the most important global environmental issues facing the world today. Using the building simulation techniques, this research investigates the interaction and relationship between global warming and built environment, particularly for the air-conditioned office buildings. The adaptation potential of various building designs is also evaluated. Based on the descriptive statistics method, the Pearson Product Moment Correlation and the regression analysis method, ten years of historical hourly climatic data for Australia are first analyzed. The distribution patterns of key weather parameters between a Test Reference Year (TRY) and multiple years (MYs), and between relatively cold and hot years are also compared. The possible cross-correlation between several different weather variables are then assessed and established. These findings form a useful basis and provide insights for the development of future weather models under "hot" global warming conditions and the explanation of building performance at different locations. Based on a review of the existing weather data generation models and findings from historic climatic data analysis, an effective method to generate approximate future hourly weather data suitable for the study of the impact of global warming is presented. This is achieved by imposing the future temperature projection from the global climate model on top of the historically observed weather data. Depending on the level of information available for the prediction of future weather conditions, this method allows either the method of retaining to current level, constant offset method or diurnal modelling method to be used. Therefore it represents a more comprehensive and holistic approach than previous one that have been used to convert the available weather data and climatic information to a format suitable for building simulation study. An example of the application of this method to the different global warming scenarios in Australia is also presented. The performance of a representative office building is then examined in details under the five weather scenarios (present, 2030 Low, 2030 High, 2070 Low and 2070 High) and over all eight capital cities in Australia. The sample building used for this study is an air conditioned, square shape, ten storey office tower with a basement carpark, which is recommended by the Australian Building Codes Board to represent the typical office building found in the central business district (CBD) of the capital cities or major regional centres in Australia. Through building computer simulations, the increased cooling loads imposed by potential global warming is quantified. The probable indoor temperature increases and overheating problems due to heat load exceeding the capacity of installed air-conditioning systems are also presented. It is shown that in terms of the whole building indoor thermal environment, existing buildings would generally be able to adapt to the increasing warming of the 2030 year Low and High scenarios projections and the 2070 year Low scenario projection. For the 2070 year High scenario, the study indicates that the existing office buildings in all capital cities will suffer from the overheating problem. To improve the building thermal comfort to an acceptable standard (ie, less than 5% of occupied hours having indoor temperature over 25°), a further increase of 4-10% of building cooling load is required. The sensitivity of different office building zoning (i.e. zone at different floors and/or with different window orientation) to the potential global warming is also investigated. It is shown that for most cities, the ground floor, and the South or Core zone would be most sensitive to the external temperature change and has the highest tendency to having the overheating problem. By linking building energy use to CO2 emissions, the possible increase of CO2 emissions due to increased building energy use is also estimated. The adaptation potential of different designs of building physical properties to global warming is then examined and compared. The parametric factors studied include the building insulation levels, window to wall ratio, window glass types, and internal load density. It is found that overall, an office building with a lower insulation level, smaller window to wall ratio and/or a glass type with lower shading coefficient, and lower internal load density will have the effect of lowering building cooling load and total energy use, and therefore have a better potential to adapt to the warming external climate. This phenomenon can be linked to the nature of internal-load dominated office-building characteristics. Based on these findings, a series of design and adaptation strategies have been proposed and evaluated.

Global warming induced by the emissions of greenhouse gases is one of the most important global environmental issues facing the world today. Using the building simulation techniques, this research investigates the interaction and relationship between global warming and built environment, particularly for the air-conditioned office buildings. The adaptation potential of various building designs is also evaluated. Based on the descriptive statistics method, the Pearson Product Moment Correlation and the regression analysis method, ten years of historical hourly climatic data for Australia are first analyzed. The distribution patterns of key weather parameters between a Test Reference Year (TRY) and multiple years (MYs), and between relatively cold and hot years are also compared. The possible cross-correlation between several different weather variables are then assessed and established. These findings form a useful basis and provide insights for the development of future weather models under "hot" global warming conditions and the explanation of building performance at different locations. Based on a review of the existing weather data generation models and findings from historic climatic data analysis, an effective method to generate approximate future hourly weather data suitable for the study of the impact of global warming is presented. This is achieved by imposing the future temperature projection from the global climate model on top of the historically observed weather data. Depending on the level of information available for the prediction of future weather conditions, this method allows either the method of retaining to current level, constant offset method or diurnal modelling method to be used. Therefore it represents a more comprehensive and holistic approach than previous one that have been used to convert the available weather data and climatic information to a format suitable for building simulation study. An example of the application of this method to the different global warming scenarios in Australia is also presented. The performance of a representative office building is then examined in details under the five weather scenarios (present, 2030 Low, 2030 High, 2070 Low and 2070 High) and over all eight capital cities in Australia. The sample building used for this study is an air conditioned, square shape, ten storey office tower with a basement carpark, which is recommended by the Australian Building Codes Board to represent the typical office building found in the central business district (CBD) of the capital cities or major regional centres in Australia. Through building computer simulations, the increased cooling loads imposed by potential global warming is quantified. The probable indoor temperature increases and overheating problems due to heat load exceeding the capacity of installed air-conditioning systems are also presented. It is shown that in terms of the whole building indoor thermal environment, existing buildings would generally be able to adapt to the increasing warming of the 2030 year Low and High scenarios projections and the 2070 year Low scenario projection. For the 2070 year High scenario, the study indicates that the existing office buildings in all capital cities will suffer from the overheating problem. To improve the building thermal comfort to an acceptable standard (ie, less than 5% of occupied hours having indoor temperature over 25°), a further increase of 4-10% of building cooling load is required. The sensitivity of different office building zoning (i.e. zone at different floors and/or with different window orientation) to the potential global warming is also investigated. It is shown that for most cities, the ground floor, and the South or Core zone would be most sensitive to the external temperature change and has the highest tendency to having the overheating problem. By linking building energy use to CO2 emissions, the possible increase of CO2 emissions due to increased building energy use is also estimated. The adaptation potential of different designs of building physical properties to global warming is then examined and compared. The parametric factors studied include the building insulation levels, window to wall ratio, window glass types, and internal load density. It is found that overall, an office building with a lower insulation level, smaller window to wall ratio and/or a glass type with lower shading coefficient, and lower internal load density will have the effect of lowering building cooling load and total energy use, and therefore have a better potential to adapt to the warming external climate. This phenomenon can be linked to the nature of internal-load dominated office-building characteristics. Based on these findings, a series of design and adaptation strategies have been proposed and evaluated.

Cette thèse s'intéresse à différents aspects relatifs à l'économie des énergies renouvelables (EnR) électriques. Celles-ci ont été choisies par de nombreux pays, désireux de réduire leur empreinte carbone, dans le cadre de la lutte contre le changement climatique.N'étant la plupart du temps pas compétitives face aux moyens de production conventionnels, les EnR nécessitent des subventions publiques, à la fois nationales et locales, pour être rentables. J'analyse l'efficacité de ces aides dans le cas du photovoltaïque chez les particuliers français, en tenant compte des phénomènes de communication, qui participent fortement à la diffusion. Je montre combien ces derniers peuvent être un levier supplémentaire dans le développement des EnR.Ensuite, j'étudie l'impact des schémas régionaux de raccordement au réseau des EnR, dans le cas de l'éolien terrestre en France. Ces schémas introduisent une différenciation spatiale des frais de raccordement. Cela permet de réorienter les investissements vers les régions dans lesquelles le réseau est moins contraint, ce que je quantifie.Les réseaux jouent également un rôle dans le développement des EnR via leur tarification. Celle-ci est essentielle dans le cas de l'autoconsommation, qui fait peser des risques sur l'équilibre budgétaire du gestionnaire de réseau. Ainsi, je détermine notamment les prix à l'optimum économique de second rang dans le cas d'un tarif binôme énergie-puissance.Enfin, j'analyse l'impact de la production renouvelable sur les prix de gros de l'électricité en Allemagne. Je montre que les EnR induisent une baisse des prix différenciée en fonction de l'équilibre offre-demande. Ceci pénalise les centrales de pointe nécessaires à la sécurité d'approvisionnement, ainsi que les EnR de demain, qui devront se passer de subventions
This thesis deals with several aspects of the economics of electric renewable energy sources (RES). These have been chosen by many countries, willing to reduce their carbon footprint, in order to fight climate change.As RES are usually not competitive against conventional power plants, they rely on national and local subsidies in order to be profitable. I analyse the efficiency of such support schemes in the case of solar photovoltaics for residential households in France. Communication phenomena also take a huge part in the diffusion process. My work shows in how far these are an additional driver of RES development.Then, I study the impact of regional network connection schemes for renewables in France, in the field of onshore wind energy. These schemes introduce a spatial differentiation of network connection charges. They enable to reallocate investments in regions in which the electricity network is less constrained, and I quantify this reallocation.Electricity networks also play a role in the development of RES through their tarification. The latter is fundamental in the case of self-consumption (or "prosumption"), that puts the budget balance of the network operator at risk. Thus, I derive second-best prices in the case of a two-part energy-capacity tariff.Finally, I analyse the impact of renewable generation on electricity wholesale prices in Germany. I show that RES induce a decrease in prices, which depends on the supply-demand equilibrium. This penalises peaking power plants that are necessary to the security of supply, as well as future renewables, which shall progressively become profitable without subsidies

This thesis analyses the elements and problems underpinning Brazil’s hydroelectric system and climate change legislation, at both national and international levels. As hydropower dams' operation is threatened by climate change, an adaptive legal framework to create energy security in Brazil in the context of climate change is needed. The study particularly investigates human rights issues and makes a comparative analysis with the American legislation. The study also provides a global model for other countries that rely on hydropower dams and face similar climate change issues.

Cette thèse s'interroge sur les conditions de réalisation d'une civilisation industrielle décarbonée et durable, en étudiant certains aspects de sa faisabilité physique et de son acceptabilité politique. Le Chapitre I étudie l'évolution du taux de retour énergétique dans différents scénarios prospectifs, et prédit que l'efficacité globale du secteur de l'électricité à fournir un surplus d'énergie serait réduite de moitié dans un scénario 100% renouvelable. Le Chapitre 2 souligne l'importance de la recyclabilité des métaux dans un modèle d'extraction optimale des métaux et des fossiles pour la production d'énergie. L'annexe au Chapitre 2 étend le théorème de Karush-Kuhn-Tucker au cas d'une série convexe sous un nombre fini de contraintes. Les Chapitres 3 et 4 se fondent sur une enquête auprès d'un échantillon représentatif de trois milles français, réalisée durant le mouvement des Gilets jaunes. Le Chapitre 3 étudie les croyances relatives à une taxe carbone avec dividende, mesure vantée pour lutter contre le changement climatique du fait de son efficacité et de sa progressivité. Si 70 % rejettent la taxe avec dividende. c'est en raison de perceptions pessimistes quant à ses propriétés : en contradiction avec les micro-simulations effectuées, la plupart pensent que leur ménage perdrait en pouvoir d'achat suite à la réforme, la perçoivent comme régressive et inefficace pour réduire la pollution et lutter contre le changement climatique. Le Chapitre 4 analyse les connaissances, les perceptions et les valeurs liées au changement climatique, examine les opinions relatives à la taxation du carbone et évalue le soutien à d'autres politiques climatiques
This thesis examines the conditions for the realization of a decarbonized and sustainable industrial civilization by studying certain aspects of its physical feasibility and political acceptability. Chapter 1 studies the evolution of the Energy Return On Investment in different prospective scenarios, and predicts that the overall efficiency of the electricity sector to supply a net energy surplus would be halved in a 100% renewable scenario. Chapter 2 highlights the importance of metal recyclability in a model of optimal extraction of metals and fossil fuels for energy production. The annex to Chapter 2 extends the Karush-Kuhn-Tucker theorem to the case of a convex series under a finite number of constraints. Chapters 3 and 4 are based on a survey of a representative sample of three thousand French people, carried out during the Yellow vests movement. Chapter 3 examines beliefs about a carbon "tax & dividend", a measure touted to combat climate change because of its effectiveness and progressivity. If 70% reject the tax & dividend, it is because of pessimistic perceptions about its properties: in contradiction with the micro-simulations, most believe that their household would lose purchasing power with the reform, perceive it as regressive, and inefficient to reduce pollution and fight climate change. Chapter 4 analyses knowledge, perceptions and values related to climate change, examines opinions on carbon taxation and assesses support for other climate policies

The impact on the built environment due to the forecasted climate change was presented by the authorities more than one decade ago, but the actions from the building industry to adapt buildings for a changed climate are still lacking. The purpose of this study is to identify a suitable cooling technique for a modern residential building in a future warmer climate in order to maintain thermal comfort but also energy efficiency. This thesis analyses and presents passive techniques and the behavior of active cooling with a slab cooling system under a future climate scenario so as to accomplish a sustainable system which will be functionable and viable in the future. To verify the different solutions the building performance simulation software IDA ICE has been used and a case study building with a simulated location in the city of Stockholm has been investigated. Results show promising outcomes as thermal comfort is achieved and energy efficiency is maintained depending on diversely selected energy sources.
Påverkan på den byggda miljön från klimatförändringar har upplysts av myndigheter under minst de senaste tio åren, men agerande från byggbranschen för att klimatanpassa är fortfarande låg. Syftet med denna studie är att identifiera en lämplig kylteknik för ett bostadshus i ett framtida varmare klimat för att bibehålla termisk komfort och samtidigt energieffektivitet. Denna examensrapport analyserar och presenterar prestanda hos dels olika passiva system, dels ett kombinerat värme- och kylsystem i bjälklag i ett framtida klimatscenario för att uppnå ett hållbart system som kommer att vara funktionellt och livskraftigt i framtiden. För att verifiera de olika kyllösningarna har simuleringsprogrammet för byggnadsprestanda IDA ICE använts och en fallstudiebyggnad med en simulerad placering i Stockholm har undersökts. Resultaten visar lovande resultat eftersom termisk komfort uppnås och energiprestanda kan bibehållas beroende på valda energikällor.

Today, it is not unusual that smartphone devices can’t survive even one day of regular use until the battery needs to be recharged. The batteries are drained while using power hungry applications made by developers who haven’t taken their application’s energy impact into consideration. In this thesis we study network transmissions as made by a mobile application, and the impact these have on the battery life. The application was developed with the local rescue and emergency service as a hypothetical target group. We test how the mobile network technologies 3G and WiFi together with the device’s current signal strength and battery level affect the energy usage of the battery when uploading data to a server. We develop an adaptation mechanism on application level which uses a mathematical model for calculating a suitable adaptation of scheduling of network interactions. The adaptation mechanism makes use of burst buffering of packets, and adjusts for 3G tail times as well as for different priorities of incoming requests. Custom packet scheduling profiles are made to make consistent measurements, and with this implementation we are able to reduce the amount of energy consumed using 3G and WiFi with 67 % and 39 % respectively during tests.