Thèses : « Edge energy »

1

Johansson, Jennifer. « Cooling storage for 5G EDGE data center ». Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79126.

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Data centers requires a lot of energy due to that data centers count as the buildings also contains servers, cooling equipment, IT-equipment and power equipment. As the cooling solution for many data centers around the world right now, the compressor-based cooling solution counts for around 40% of the total energy consumption. A non-compressor-based solution that is used in some data centers, but also is in a research phase is the free cooling application. Free cooling means that the outside air is utilized to cool down the data center and there are two main technologies that contains within free cooling: airside free cooling and waterside free cooling. The purpose of this master thesis is to analyze two types of coils; one corrugated and the other one smooth, providing from Bensby Rostfria, to investigate if it is possible to use free cooling in 5G EDGE data center in Luleå, with one of these coils. The investigation will be done during the warmest day in summer. This because, according to weather data, Luleå is one candidate where this type of cooling system could be of use. The project was done through RISE ICE Datacenter where two identical systems was built next to each other with two corrugated hoses of different diameter and two smooth tubes with different diameter. The variables that was measured was the ambient temperature within the data hall, the water temperature in both water tanks, the temperature out from the system, the temperature in to the system and the mass flow of the air that was going to go through the system. The first thing that was done was to do fan curves to easier choose which input voltages for the fans that was of interest to do further analysis on. After that was done, three point was taken where the fan curve was of most increase. The tests were done by letting the corrugated hoses and smooth tubes to be in each of the water tanks and fill it with cold water. It was thereafter the coils that should warm the water from 4,75 °C – 9,75 °C, because of that the temperature in the data center was around 15 °C. The rising in particularly these temperatures was chosen because it is seen that to use free cooling the temperature differences must be at least 5 °C. The tests were done three times to get a more reliable result. All the data was further taken in to Zabbix and to further analysis in Grafana. When one test was done the files was saved from Grafana to Excel for compilation, and thereafter to Matlab for further analysis. The first thing that was analyzed was if the three different tests with the same input voltages gave similar results in the water temperature in the tank and the temperature out from the system. Thereafter, trendlines was built to investigate the temperature differences in and out of the system, the temperature differences in and the water temperature in the tank, the mass flow and the cooling power. That trendline was further in comparison to each other, which was 2D-plots between the cooling power and the temperature differences between the inlet and the water. Thereafter the both coils could compare to each other to see which of them that gave the largest cooling power and was most efficient to install in a future 5G data center module. The conclusion for this master thesis is that the corrugated hose will give a higher cooling power with higher temperature differences outside, but during the warmest summer day it was distinctly the smooth tube that gave the largest cooling power and therefore the best result. The smooth tube also got, through hand calculations, the larger amount of pipe that was necessary to cool down the 5G module, but the smallest water tank. It was also shown that for the warmest summer day, a temperature in the water tank of 24 °C is the best, compared to 20 °C and 18 °C. The amount of coil that is needed to cool down the data center with a temperature in the water tank at 24 °C and how large the water tank differs between the two types of coils. For the corrugated hose a length of 1.8 km and a water tank of 9.4 m3. As for the smooth tube a length of 1.7 km and a water tank volume of 12 m3. As can be seen throughout this project is that this type of cooling equipment is not the most efficient for the warmest summer day but could easily be used for other seasons.

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Madhvesh, Ashok. « Crucial edge detection in sensor system under energy constraints ». Thesis, Wichita State University, 2009. http://hdl.handle.net/10057/2507.

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Wireless sensor nodes are usually deployed in remote locations for various applications that require monitoring of certain interesting events. Due to this remote operational feature the longevity of the sensor node's lifetime has been a primary concern. Although the sensor nodes available today may be equipped with rechargeable batteries, the minimal energy capacity of such batteries and low recharge rates degrade the sensor's lifetime and achievable performance. Hence, operational algorithms are needed to guarantee high performance with efficient utilization of energy available. In this thesis, considering temporally correlated event phenomena, the important question answered is: "How long should the sensor sleep, and for how long should the sensor stay active?". To achieve this, a sensor activation/deactivation algorithm has been developed that achieves high performance with efficient energy utilization. A sensor loses energy predominantly because of redundant transmissions of sensed data. To avoid this, a sensor was modeled to transmit only the changes sensed in the event-occurrence process, referred to as Crucial Edges or Transitions. In addition, the system model allows the transmission of transitions that are detected late. Several intuitive decision-making policies were compared and the results compared in order to determine the best policy for this problem. This policy was later analyzed usingMarkov chain analysis techniques to derive upper and lower bounds on the achievable performance. The proposed policy achieves high performance under energy balancing constraints, and is deterministic, simple and easy to implement on a sensor node.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science

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3

Liu, Wei-Hsin. « Investigation of edge effects in thermoacoustic couple measurements ». Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA246393.

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Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, December 1990.
Thesis Advisor(s): Atchley, Anthony A. ; Hofler, Thomas J. "December 1990." Description based on title screen as viewed on March 31, 2010. DTIC Descriptor(s): Heat Transfer, Coupling (Interaction), Peak Values, Ratios, Temperature, Thermodynamics, Edges, Isolation, Sensitivity, Regions, Short Range (Time), Profiles, Plates, Internal, Acoustic Arrays, Pressure, Drives, Leading Edges, Mean, Amplitude, Sound Pressure, Stacking, Thermopiles. DTIC Identifier(s): Heat Pumps, Energy Conversion, Energy Storage, Heat Transfer, Thermoacoustic Couples, Theses Author(s) subject terms: Acoustics, Thermoacoustics, Thermoacoustic Heat Transport. Includes bibliographical references (p. 34). Also available in print.

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Chang, Xiaomin. « Sustainable Edge Computing Platform for Energy Management in Smart Homes ». Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/20245.

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There is a growing trend for engaging edge computing to help smart homes to improve the comfort of living for residents. The rapidly rising interest in such deployments, however, does not usually correspond with energy management schemes. In this thesis, we will propose a unified system framework for enabling a sustainable edge computing, while meeting the needs of data processing for smart home applications. Besides, we also designed an edge-based energy management framework for powering smart appliances at home, which aims to enable the use of renewable energy to greatly reduce energy costs for households. To make better use of renewable energy, a modified forecasting approach will be applied in both frameworks, to constantly forecast renewable energy generation. Furthermore, two optimal energy scheduling algorithms for edge devices and one job scheduling algorithm for appliance jobs are also proposed in this thesis. By employing advanced energy disaggregation technique in the edge-based energy management framework, usage pattern and users preference on each appliance can be derived, and thus, each appliance job can be rescheduled based on this information. To evaluate the performance of two edge computing paradigms, two prototype systems have been implemented by using low-cost and easy-to-get hardware. The experiment results demonstrate that renewable energy is completely capable of supporting the reliable running of edge computing devices and smart appliances, and the utilisation of renewable energy increased significantly when our proposed frameworks were employed, compared with when they were not.

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Bozorgchenani, Arash <1989&gt. « Energy and Delay Efficient Computation Offloading Solutions for Edge Computing ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amsdottorato.unibo.it/9356/1/PhD%20Thesis_Arash%20Bozorgchenani.pdf.

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This thesis collects a selective set of outcomes of a PhD course in Electronics, Telecommunications, and Information Technologies Engineering and it is focused on designing techniques to optimize computational resources in different wireless communication environments. Mobile Edge Computing (MEC) is a novel and distributed computational paradigm that has emerged to address the high users demand in 5G. In MEC, edge devices can share their resources to collaborate in terms of storage and computation. One of the computational sharing techniques is computation offloading, which brings a lot of advantages to the network edge, from lower communication, to lower energy consumption for computation. However, the communication among the devices should be managed such that the resources are exploited efficiently. To this aim, in this dissertation, computation offloading in different wireless environments with different number of users, network traffic, resource availability and devices' location are analyzed in order to optimize the resource allocation at the network edge. To better organize the dissertation, the studies are classified in four main sections. In the first section, an introduction on computational sharing technologies is given. Later, the problem of computation offloading is defined, and the challenges are introduced. In the second section, two partial offloading techniques are proposed. While in the first one, centralized and distributed architectures are proposed, in the second work, an Evolutionary Algorithm for task offloading is proposed. In the third section, the offloading problem is seen from a different perspective where the end users can harvest energy from either renewable sources of energy or through Wireless Power Transfer. In the fourth section, the MEC in vehicular environments is studied. In one work a heuristic is introduced in order to perform the computation offloading in Internet of Vehicles and in the other a learning-based approach based on bandit theory is proposed.

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Xia, Chunqiu. « Energy Demand Response Management in Smart Home Environments ». Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/20182.

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ENABLING DEMAND RESPONSE ON ENERGY MANAGEMENT IN SMART HOME With the penetration of the Internet of Things (IoT) paradigm into the household scenario, an increasing number of smart appliances have been deployed to improve the comfort of living in the household. At present, most smart home devices are adopting the Cloud-based paradigm. The increasing electricity overhead from these smart appliances, however, has caused issues, as existing home energy management systems are unable to reduce electricity consumption effectively. To address this issue, we propose the use of an Edge-based computing platform with lightweight computing devices. In our experiments, this Edge-based platform has proven to be more energy efficient when compared to the traditional Cloud-based platform. To further reduce energy tariffs for households, we propose an energy management framework, namely Edge-based energy management System (EEMS), to be used with the Edge-based system that was designed in the first stage of our research. The EEMS is a low infrastructure investment system. A small-scale solar energy harvesting system has also been integrated into this system. The non-intrusive load monitoring (NILM) algorithm has been implemented in appliances monitoring. Regarding to energy management function, the scheduling strategy can also conform to user preference. We have conducted a realistic experiment with several smart appliances and Raspberry Pi. The experiment resulted in the electricity tariff being reduced by 82.3%. The last part of research addresses demand response (DR) technology. With the development of DR, energy management systems such as EEMS are better able to be implemented. We propose the use of an electricity business trading model, integrated with user-side demand response resources. The business trading model can be adopted to manage risks, increase profit and improve user satisfaction. Users will also benefit from tariffs reduction with the use of this model.

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Raffa, Viviana. « Edge/cloud virtualization techniques and resources allocation algorithms for IoT-based smart energy applications ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22864/.

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Nowadays, the installation of residential battery energy storage (BES) has increased as a consequence of the decrease in the cost of batteries. The coupling of small-scale energy generation (residential PV) and residential BES promotes the integration of microgrids (MG), i.e., clusters of local energy sources, energy storages, and customers which are represented as a single controllable entity. The operations between multiple grid-connected MGs and the distribution network can be coordinated by controlling the power exchange; however, in order to achieve this level of coordination, a control and communication MG interface should be developed as an add-on DMS (Distribution Management System) functionality to integrate the MG energy scheduling with the network optimal power flow. This thesis proposes an edge-cloud architecture that is able to integrate the microgrid energy scheduling method with the grid constrained power flow, as well as providing tools for controlling and monitoring edge devices. As a specific case study, we consider the problem of determining the energy scheduling (amount extracted/stored from/in batteries) for each prosumer in a microgrid with a certain global objective (e.g. to make a few energy exchanges as possible with the main grid). The results show that, in order to have better optimization of the BES scheduling, it is necessary to evaluate the composition of a microgrid in such a way as to have balanced deficits and surpluses, which can be performed with Machine Learning (ML) techniques based on past production and consumption data for each prosumer.

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Singh, Navjot. « Planning of Mobile Edge Computing Resources in 5G Based on Uplink Energy Efficiency ». Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38444.

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Increasing number of devices demand for low latency and high-speed data transmission require that the computation resources to be closer to users. The emerging Mobile Edge Computing (MEC) technology aims to bring the advantages of cloud computing which are computation, storage and networking capabilities in close proximity of user. MEC servers are also integrated with cloud servers which give them flexibility of reaching vast computational power whenever needed. In this thesis, leveraging the idea of Mobile Edge Computing, we propose algorithms for cost-efficient and energy-efficient the placement of Mobile Edge nodes. We focus on uplink energy-efficiency which is essential for certain applications including augmented reality and connected vehicles, as well as extending battery life of user equipment that is favorable for all applications. The experimental results show that our proposed schemes significantly reduce the uplink energy of devices and minimizes the number of edge nodes required in the network.

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Chang, Zhongwen, Pär Olsson, Nils Sandberg et Dmitry Terentyev. « Interaction Energy Calculations of Edge Dislocation with Point Defects in FCC Cu ». KTH, Reaktorfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122396.

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In order to improve the dislocation bias (DB) model of swelling under irradiation, a large scale of atomistic simulation of the interaction in face centered cubic (FCC) Cu model lattice between an edge dislocation (ED) and point defects such as a vacancy, a self-interstital atom (SIA) have been performed for various configurations. It is found dislocation core splits into partial cores after energy relaxation. Interactions with any SIA conficurations is one order of magnitute larger than with a vacancy. The reason that SIA creats a larger dilatation volumn than the vacancy is directly observed from calculation. Furthurmore, within the interaction range, an octahedron position rather than dumbbell in <100> direction is observed in the stable state after relaxation in interactions between a edge dislocation and a dumbbell SIA. Comparision of interaction energy in analytical and atomistic calculation shows that analytical one has a stronger interaction in vacancy-ED systems, suggesting that the bias factor (BF) from analytical calculation is larger than from atomistic calculation.

QC 20130530

Generation IV reactor research and development (GENIUS)

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Pitts, R. A. « Ion energy, sheath potential and secondary electron emission in the tokamak edge ». Thesis, Royal Holloway, University of London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508346.

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Stern, Stephanie (Stephanie B. ). « Making energy efficiency desirable : lessons from a cutting-edge program in Minneapolis ». Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67242.

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Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 42-45).
For the last 30 years, experts have claimed that energy efficiency upgrades in existing buildings can lead to significant reductions in energy use, yet efficiency programs, particularly those geared towards households, have failed to meet expectations. Through interviews with participants of the Community Energy Services program in Minneapolis, Minnesota, I identify the barriers to investing in energy efficiency facing homeowners, even with a cutting-edge program that combines technical and financial assistance and seeks to create neighborhood norms around addressing energy efficiency. I argue that it is important to distinguish between financial and logistical barriers and emotional or psychological barriers. Both are important to convince a homeowner to take action, yet Community Energy Services, like many other programs, focuses too much on the former, while failing to make a compelling emotional argument for the majority of their participants. The Community Energy Services program improves on previous energy efficiency programs by simplifying the process and supporting the homeowner. It provides a promising model that, once strengthened with a more convincing emotional argument for upgrades, could be a breakthrough to significant reductions in energy use.
by Stephanie Stern.
M.C.P.

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Bernal, Mera José Luis. « Cosmology on the Edge of Lambda-Cold Dark Matter ». Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/667707.

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Cosmology is the science that studies the Universe as whole, aiming to understand its origin, composition and evolution. During the last decades, cosmology has transitioned from a “data staved” to a “data driven” science, inaugurating what is known as precision cosmology. This huge observational effort has confirmed and fostered theoretical research, and established the standard model of cosmology: Lambda-Cold Dark Matter (LCDM). This model successfully reproduces most of the observations. However, there are some persistent tensions between experiments that might be smoking guns of new physics beyond this model. Anyways, there is a difference between modeling and understanding, and LCDM is a phenomenological model that, for instance, does not describe the nature of the dark matter or dark energy. This thesis collects part of my research focused on pushing the limits of the standard cosmological model and its assumptions, regarding also existing tensions between experiments. New strategies to optimize the performance of future experiments are also proposed and discussed. The largest existing tension is between the direct measurements of the Hubble constant using the distance ladder in the local Universe and the inferred value obtained from observations of the Cosmic Microwave Background when LCDM is assumed. A model independent reconstruction of the late-time expansion history of the Universe is carried out, which allows us to identify possible sources and solutions of the tension. We also introduce the concept of the low redshift standard ruler, and measure it in a model independent way. Finally, we introduce a statistical methodology to analyze several data sets in a conservative way, no matter the level of discrepancy between them, accounting for the potential presence of systematic errors. The role of primordial black holes as candidates for dark matter is addressed in this thesis, too. Concretely, the impact of an abundant population of primordial black holes in the rest of cosmological parameters is discussed, considering also populations with extended mass distributions. In addition, massive primordial black holes might be the seeds that are needed to explain the origin of the supermassive black holes located in the center of the galaxies. We predict the contribution of a population of massive primordial black holes to the 21 cm radiation from the dark ages. This way, observations of the 21 cm intensity mapping observations of the dark ages could be used to ascertain if the seeds of the supermassive black holes are primordial. Finally, we estimate the potential of radio-continuum galaxy surveys to constrain LCDM. These kind of experiments can survey the sky quicker than spectroscopic and optical photometric surveys and cover much larger volumes. Therefore, they will be specially powerful to constrain physics which has impact on the largest observable scales, such as primordial non Gaussianity. On the other hand, intensity mapping experiments can reach higher redshifts than galaxy surveys, but the cosmological information of this signal is coupled with astrophysics. We propose a methodology to disentangle astrophysics and optimally extract cosmological information from the intensity mapping spectrum. Thanks to this methodology, intensity mapping will constrain the expansion history of the Universe up to reionization, as shown in this thesis.
El modelo estándar de cosmología, LCDM, se apoya en una cantidad ingente de observaciones extremadamente precisas, que es capaz de reproducir con gran exactitud. Sin embargo, este es un modelo fenomenológico que no es capaz de responder algunas de las preguntas fundamentales sobre el Universo, como la naturaleza de la materia oscura o la energía oscura. Además, cuando este modelo se utiliza para interpretar las observaciones, aparecen tensiones entre experimentos independientes. Estas tensiones, en el caso de no estar producidas por errores sistemáticos no tenidos en cuenta, necesitarían un modelo cosmológico diferente para ser resueltas. Esta tesis recoge trabajos publicados en revistas científicas investigando estos problemas de LCDM. Concretamente, se cubren tres temas principales: la tensión en la constante de Hubble entre las medidas directas usando la escalera de distancias y los valores inferidos a partir de las observaciones de la colaboración Planck asumiendo LCDM; el rol de los agujeros negros primordiales como semillas de los agujeros negros supermasivos, o como candidato para conformar una parte significativa de la materia oscura; y el potencial y las estrategias óptimas a aplicar en experimentos que mapean la estructura a gran escala del Universo para examinar LCDM y medir posibles desviaciones del modelo. De este modo, el trabajo aquí recogido tiene como objetivo investigar las tensiones presentes en LCDM, así como las preguntas que deja sin responder de una manera crítica y desde un punto de vista agnóstico. Además, pretende sentar las bases para futuras investigaciones en estas líneas, cuando estén disponibles nuevas y mejores observaciones, e indicar el camino para poder poner a prueba el modelo estándar de cosmología en los años venideros en regímenes en los que aún no se ha hecho ninguna medida.

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Docherty, Frances Therese. « ELNES investigations of spinels ». Thesis, University of Glasgow, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341951.

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Fawaz, Ibrahim. « Offloading strategies for mobile terminals with energy harvesting capabilities ». Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLT040.

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Aujourd’hui, les communications mobiles sans fil sont en pleine croissance, en raison du grand nombre d’appareils connectés, ce qui augmente considérablement la demande de gros volumes de données, nécessitant des calculs intensifs et entraînant une forte consommation d’énergie. Toutefois, cette expansion des services sans fil est encore entravée par les limitations des terminaux mobiles, en termes de capacité de traitement, de stockage et d’énergie. Récemment, le Mobile Edge Computing (MEC) et la récupération d’énergie (EH) ont été proposés comme des technologies prometteuses pour prolonger la durée de vie des batteries des appareils mobiles et améliorer leurs capacités de traitement. D’une part, le MEC permet de décharger les tâches de calcul des appareils mobiles vers une station de base voisine avec plus d’énergie et de ressources de traitement. D’autre part, l’EH exploite des sources d’énergie alternatives et renouvelables pour alimenter les appareils mobiles. Cependant, la nature stochastique des énergies renouvelables peut entraîner des pénuries d’énergie. Dans ce cas, les performances du système peuvent être dégradées en raison de la perte de paquets ou d’une latence intolérable. Afin de garantir la durabilité du système, des politiques de transmission efficaces sous les contraintes de l’EH sont nécessaires. Dans cette thèse, nous étudions la planification conjointe des ressources et le déchargement des calculs dans un système MEC monoutilisateur fonctionnant avec des dispositifs basés sur l’EH. La contribution principale de ce travail est l’introduction de la contrainte de délai stricte au lieu de la contrainte de délai moyenne pour satisfaire les besoins futurs des communications à faible latence et des applications critiques. Nous étudions trois configurations différentes. Dans la première configuration, nous considérons que le canal est parfaitement connu au niveau de l’émetteur (CSI parfait) et nous visons à minimiser la perte de paquets due à la violation du délai et au débordement de la mémoire tampon du dispositif. Le problème d’optimisation associé est modélisé comme un processus de décision de Markov et la politique optimale est donnée par des techniques de programmation dynamique. Nous montrons que la politique optimale est plus performante que les autres politiques en adaptant le nombre de paquets traités aux états du système. Dans la seconde configuration, nous considérons un scénario plus réaliste, où le canal n’est pas parfaitement connu à l’émetteur et il est acquis après une phase d’estimation. En fait, cette estimation peut être erronée entraînant une dégradation supplémentaire du taux de perte de paquets. Par conséquent, nous évaluons la politique optimale obtenue précédemment lorsque le CSI est imparfait et nous montrons qu’elle reste robuste par rapport à d’autres politiques. Enfin, nous examinons la configuration sans CSI au niveau de l’émetteur. Nous supposons donc qu’un CSI obsolète est seulement disponible et nous montrons que la politique optimale proposée peut encore atteindre de bonnes performances par rapport à d’autres politiques
Nowadays, the wireless mobile communications are witnessing unprecedented growth fueled by the huge number of connected devices increasing importantly the demands for high-volume data traffic, requiring thus intensive computation and leading to high energy consumption. However, this expansion of wireless services is still restrained by mobile terminals limitations, in terms of processing capacity, storage and energy. Mobile Edge Computing (MEC) and Energy Harvesting (EH) schemes have been recently proposed as promising technologies to extend the battery lives of mobile devices and improve their computing capabilities. On one hand, MEC enables offloading computation tasks from mobile devices to nearby Base Station with more energy and computations resources. On the other hand, EH exploits alternative renewable energy sources to power mobile devices. However, the stochastic nature of renewable energy may lead to energy outage. In such cases, the system’s performance can be degraded due to packet loss or intolerable latency. In order to sensure the system sustainability, efficient transmission policies under EH constraints are needed. In this thesis, we investigate the joint resource scheduling and computation offloading in a single user MEC system operating with EH based devices. The main contribution of this work is the introduction of the strict delay constraint instead of the average delay constraint to satisfy future requirements of lowlatency communications and critical applications. We study three different setups. In the first setup, we consider a perfect Channel State Information (CSI) at the transmitting device and we aim to minimize the packet loss due to delay violation and buffer overflow at the device’s data buffer. The associated optimization problem is modeled as Markov Decision Process and the optimal policy is exhibited through Dynamic Programming techniques. We show that the optimal policy outperforms other policies by adapting the number of processed packets to the system states. In the second setup, we consider a more realistic scenario, where the channel is not perfectly known at the transmitter and it is acquired after an estimation phase. In fact, this estimation can be erroneous degrading thus further the packet loss rate. Hence, we evaluate the previously obtained optimal policy under imperfect CSI conditions and we show that it remains robust with respect to other policies. Finally, we address the setup with no CSI at the transmitter. We therefore assume that an outdated CSI is only available and we show that the proposed optimal policy can still achieve good performance compared to other policies

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Mount, Kristopher Patrick. « Finite Element Analysis of Probe Induced Delamination of a Thin Film at an Edge Interface ». Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/31014.

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Energy release rates are extracted from non-linear finite element analyses of a thin film bonded to a rigid substrate that is shaft-loaded at its free edge. This geometry is of interest because it simulates a probe test that has proven to be useful in characterizing the adhesion of thin, microelectronic coatings bonded to silicon wafers. Preliminary experimental results indicate that out-of-plane rather than in-plane loading dominates failure in the system. This work therefore focuses on out-of-plane film loading. To validate finite element and energy release rate methodologies, energy release rates from finite element analyses of pressurized and shaft-loaded blister tests are first correlated to theoretical limit cases. Upon validation, mode I, mode II, and mode III energy release rates are extracted from three-dimensional continuum finite element models of the edge-loaded thin film by a three-dimensional modified crack closure method. Having assumed a circular debond as observed experimentally, energy release rates are determined by a step-wise approach around the circumference. The progression of debond is simulated in multiple analyses by altering the boundary conditions associated with increasing the debond radius. Mechanical loading is supplemented with thermal loading, introducing residual stresses in the non-linear analyses. A sensitivity analysis of energy release rates to residual stress is performed. The results indicate that inclusion of residual stress has an important role in both the magnitude and mode-mixity of energy release rates in the thin film. Increasing the length of debond effectively transitions the film from a shearing mode to a bending mode, thereby significantly impacting each mode of energy release rate differently.
Master of Science

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Zhang, Dingkang. « Neutral Particle Transport in Plasma Edge Using Transmission/Escape Probability (TEP) Method ». Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6916.

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Neutral particles play an important role on the performance of tokamak plasmas. In this dissertation, the original TEP methodology has been extended to take into account linearly (DP_1) and quadratically (DP_2) anisotropic distributions of angular fluxes for calculations of transmission probabilities. Three approaches, subdivision of optically thick regions, expansion of collision sources and the diffusion approximation, have been developed and implemented to correct effects of the preferential probability of collided neutrals escaping back across the incident surface. Solving the diffusion equation via the finite element method has been shown to be the most computationally efficient and accurate for a broader range of D/l by comparisons with Monte Carlo simulations. The average neutral energy (ANE) approximation has been developed and implemented into the GTNEUT code. The average neutral energy approximation has been demonstrated to be more accurate than the original local ion temperature (LIT) approximation for optically thin regions. The simulations of the upgraded GTNEUT code excellently agree with the DEGAS predictions in DIII-D L-mode and H-mode discharges, and the results of both the codes are in a good agreement with the experimental measurements.

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Helmy, Ahmed. « Energy-Efficient Bandwidth Allocation for Integrating Fog with Optical Access Networks ». Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39912.

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Access networks have been going through many reformations to make them adapt to arising traffic trends and become better suited for many new demanding applications. To that end, incorporating fog and edge computing has become a necessity for supporting many emerging applications as well as alleviating network congestions. At the same time, energy-efficiency has become a strong imperative for access networks to reduce both their operating costs and carbon footprint. In this dissertation, we address these two challenges in long-reach optical access networks. We first study the integration of fog and edge computing with optical access networks, which is believed to form a highly capable access network by combining the huge fiber capacity with closer-to-the-edge computing and storage resources. In our study, we examine the offloading performance under different cloudlet placements when the underlying bandwidth allocation is either centralized or decentralized. We combine between analytical modeling and simulation results in order to identify the different factors that affect the offloading performance within each paradigm. To address the energy efficiency requirement, we introduce novel enhancements and modifications to both allocation paradigms that aim to enhance their network performance while conserving energy. We consider this work to be one of the first to explore the integration of fog and edge computing with optical access networks from both bandwidth allocation and energy efficiency perspectives in order to identify which allocation paradigm would be able to meet the requirements of next-generation access networks.

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Dowds, Eleanor Jane, et Fatme El-Saghir. « Utilising waste heat from Edge-computing Micro Data Centres : Financial and Environmental synergies, Opportunities, and Business Models ». Thesis, KTH, Industriell ekonomi och organisation (Inst.), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298245.

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In recent times, there has been an explosion in the need for high-density computing and data processing. As a result the Internet and Communication Technology (ICT) demand on global energy resources has tripled in the last five years. Edge computing - bringing computing power close to the user, is set to be the cornerstone of future communication and information transport, satisfying the demand for instant response times and zero latency needed for applications such as 5G, self-driving vehicles, face recognition, and much more. The Micro Data Centre (micro DC) is key hardware in the shift to edge computing. Being self-contained, with in-rack liquid cooling systems, these micro data centres can be placed anywhere they are needed the most - often in areas not thought of as locations for datacentres, such as offices and housing blocks. This presents an opportunity to make the ICT industry greener and contribute to lowering total global energy demand, while fulfilling both the need for data processing and heating requirements. If a solution can be found to capture and utilise waste heat from the growing number of micro data centres, it would have a massive impact on overall energy consumption. This project will explore this potential synergy through investigating two different ways of utilising waste heat. The first being supplying waste heat to the District Heating network (Case 1), and the second using the micro DC as a ’data furnace’ supplying heat to the near vicinity (Case 2 and 3). Two scenarios of differing costs and incomes will be exploredin each case, and a sensitivity analysis will be performed to determine how sensitive each scenario is to changing internal and external factors. Results achieved were extremely promising. Capturing waste heat from micro data centres, and both supplying the local district heating network as well as providing the central heating of the near vicinity, is proving to be both economically and physically viable. The three different business models (’Cases’) created not only show good financial promise, but they demonstrate a way of creating value in a greener way of computing and heat supply. The amount of waste heat able to be captured is sufficient to heat many apartments in residential blocks and office buildings, and the temperatures achieved have proven to be sufficient to meet the heating requirements of these facilities, meaning no extra energy is required for the priming of waste heat. It is the hope that the investigations and analyses performed in this thesis will further the discussion around the utilisation of waste heat from lower energy sources, such as micro DCs, so that one day, potential can become reality.
På senare har tid har det skett en explosion i behovet av databehandling och databehandling med hög densitet. Som ett resultat har Internet- och kommunikationstekniksektorns (ICT) efterfråga på globala energiresurser tredubblats under de senaste fem åren. Edgecomputing för datorkraften närmre användaren och är hörnstenen i framtida kommunikation och informationsflöde. Omedelbar svarstid och noll latens som behövs för applikationersom 5G, självkörande fordon, ansiktsigenkänning och mycket mer tillfredställs av att datorkraften förs närme användaren. Micro Data Center är nycklen i övergången till edge computing. Eftersom att MicroData Center är fristående med inbyggda kylsystem kan de placeras där de behövs mest -ofta i områden som inte betraktas som platser för datacenter som exemeplvis kontor och bostadshus. Detta möjliggör för ICT-branschen att bli grönare och bidra till att sänka det totala globala energibehovet, samtidigt som behovet av databehandling kan tillgodoses. Om enlösning kan hittas för att fånga upp och använda spillvärme som genereras från växande antalet Micro Data Center, skulle det ha en enorm inverkan på den totala energiförbrukningen. Detta projekt kommer att undersöka potentiella synergier genom att undersöka två olikasätt att utnyttja spillvärme. Den första är att leverera spillvärme till fjärrvärmenätet (Case 1), och det andra att använda Micro Data Center som en "Data Furnace" som levererar värme till närområdet (Case 2 och 3). Två scenarier med olika kostnader och intäkter kommer att undersökas i varje Case och en känslighetsanalys kommer att utföras för att avgöra hur känsligt varje scenario är för ändrade interna och externa faktorer. Resultaten som uppnåtts är extremt lovande. Att fånga upp spillvärme från Micro Data Center och leverera till antingen det lokala fjärrvärmenätet eller nyttja spillvärmen lokalt har visat sig vara både ekonomiskt och fysiskt genomförbart. De tre olika affärsmodellerna (’Cases’) som skapats visar inte bara positivt ekonomiskt utfall, utan också ett sätt att skapa värde genom att på ett grönare sätt processa och lagra data och samtidigt värma städer. Mängden spillvärme som kan fångas upp är tillräcklig för att värma upp många lägenheter i bostadshus och kontorsbyggnader. Temperaturen på spillvärmen har visat sig vara tillräcklig för att uppfylla uppvärmningskraven i dessa anläggningar, vilket innebär att ingen extra energi krävs för att höja temperturen av spillvärme. Förhoppningen är att de undersökningar och analyser som utförs i denna rapport kommer att främja diskussionen kring utnyttjande av spillvärme från lägre energikällor, såsom Micro Data Center.

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Cuadrado-Cordero, Ismael. « Microclouds : an approach for a network-aware energy-efficient decentralised cloud ». Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S003/document.

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L'architecture actuelle du cloud, reposant sur des datacenters centralisés, limite la qualité des services offerts par le cloud du fait de l'éloignement de ces datacenters par rapport aux utilisateurs. En effet, cette architecture est peu adaptée à la tendance actuelle promouvant l'ubiquité du cloud computing. De plus, la consommation énergétique actuelle des data centers, ainsi que du cœur de réseau, représente 3% de la production totale d'énergie, tandis que selon les dernières estimations, seulement 42,3% de la population serait connectée. Dans cette thèse, nous nous intéressons à deux inconvénients majeurs des clouds centralisés: la consommation d'énergie ainsi que la faible qualité de service offerte. D'une part, du fait de son architecture centralisée, le cœur de réseau consomme plus d'énergie afin de connecter les utilisateurs aux datacenters. D'autre part, la distance entre les utilisateurs et les datacenters entraîne une utilisation accrue du réseau mondial à large bande, menant à des expériences utilisateurs de faible qualité, particulièrement pour les applications interactives. Une approche semi-centralisée peut offrir une meilleur qualité d'expérience aux utilisateurs urbains dans des réseaux clouds mobiles. Pour ce faire, cette approche confine le traffic local au plus proche de l'utilisateur, tout en maintenant les caractéristiques centralisées s’exécutant sur les équipements réseaux et utilisateurs. Dans cette thèse, nous proposons une nouvelle architecture de cloud distribué, basée sur des "microclouds". Des "microclouds" sont créés de manière dynamique, afin que les ressources utilisateurs provenant de leurs ordinateurs, téléphones ou équipements réseaux puissent être mises à disposition dans le cloud. De ce fait, les microclouds offrent un système dynamique, passant à l'échelle, tout en évitant d’investir dans de nouvelles infrastructures. Nous proposons également un exemple d'utilisation des microclouds sur un cas typique réel. Par simulation, nous montrons que notre approche permet une économie d'énergie pouvant atteindre 75%, comparée à une approche centralisée standard. En outre, nos résultats indiquent que cette architecture passe à l'échelle en terme du nombre d'utilisateurs mobiles, tout en offrant une bien plus faible latence qu'une architecture centralisée. Pour finir, nous analysons comment inciter les utilisateurs à partager leur ressources dans les clouds mobiles et proposons un nouveau mécanisme d'enchère adapté à l'hétérogénéité et la forte dynamicité de ces systèmes. Nous comparons notre solution aux autres mécanismes d’enchère existants dans des cas d'utilisations typiques au sein des clouds mobiles, et montrons la pertinence de notre solution
The current datacenter-centralized architecture limits the cloud to the location of the datacenters, generally far from the user. This architecture collides with the latest trend of ubiquity of Cloud computing. Also, current estimated energy usage of data centers and core networks adds up to 3% of the global energy production, while according to latest estimations only 42,3% of the population is connected. In the current work, we focused on two drawbacks of datacenter-centralized Clouds: Energy consumption and poor quality of service. On the one hand, due to its centralized nature, energy consumption in networks is affected by the centralized vision of the Cloud. That is, backbone networks increase their energy consumption in order to connect the clients to the datacenters. On the other hand, distance leads to increased utilization of the broadband Wide Area Network and poor user experience, especially for interactive applications. A distributed approach can provide a better Quality of Experience (QoE) in large urban populations in mobile cloud networks. To do so, the cloud should confine local traffic close to the user, running on the users and network devices. In this work, we propose a novel distributed cloud architecture based on microclouds. Microclouds are dynamically created and allow users to contribute resources from their computers, mobile and network devices to the cloud. This way, they provide a dynamic and scalable system without the need of an extra investment in infrastructure. We also provide a description of a realistic mobile cloud use case, and the adaptation of microclouds on it. Through simulations, we show an overall saving up to 75% of energy consumed in standard centralized clouds with our approach. Also, our results indicate that this architecture is scalable with the number of mobile devices and provide a significantly lower latency than regular datacenter-centralized approaches. Finally, we analyze the use of incentives for Mobile Clouds, and propose a new auction system adapted to the high dynamism and heterogeneity of these systems. We compare our solution to other existing auctions systems in a Mobile Cloud use case, and show the suitability of our solution

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Glenn, Timothy Scott 1971. « Velocity measurement of laser energy induced Rayleigh surface waves on bulk substrates employing the optical beam deflection (knife-edge detection) method ». Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/49947.

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Sutrisno, Harry. « Techno-Economic Study on The Alternative Power and Cooling Systems Design for Cost & ; Energy-Efficient Edge Cloud Data Center(s) ». Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302990.

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The 5G technology has enabled performance-sensitive applications with low latency and high bandwidth requirements, which has put more low latency requirements on computing services. To answer this need, a small-scale data center called edge cloud is predicted to grow fast in the future. Due to its nature of being close to the end-users, the growth of edge clouds in the populated area may cause a problem with the existing power system. Besides this power system challenge, the edge cloud also requires a higher resource cost than the hyper-scale data center because of the economies of scale. In this thesis, four viable alternative power and cooling technologies are introduced to address those challenges. These four technologies are solar PV, Vertical Axis Wind Turbine (VAWT), Rear Door Heat Exchanger (RDHx), and immersion cooling. Detailed data of edge cloud are required to understand the contribution of these four technologies. However, due to the infancy state of edge cloud, those data are unavailable, and assumptions regarding data are made. Besides that, a cost model for an edge cloud is also required to show how significant the contribution of those alternative technologies is if compared to the total cost of ownership. In this thesis, the cost model for the edge cloud is extended for the alternative power and cooling system scenarios. Along with the assumed data of an edge cloud, sensitivity analysis is performed to determine whether the alternative power and cooling technologies can bring down the cost of edge cloud resources or not. Through the cost modeling, it was found out that VAWT and immersion cooling is not feasible for the particular assumed data center. On the other hand, solar PV can save 4.55% of data center electricity consumption (equal to 0.21% reduction of the total expense when calculated using the current electricity price). Furthermore, RDHx performed better with 22.73% of data center electricity expenses (equivalent to 8.35% of saving from total cost when calculated using the current electricity price).
5G-tekniken har möjliggjort prestandakänsliga applikationer med låg latens och höga bandbreddskrav, vilket har ställt högre krav på låg latens för datatjänster. För att möta detta behov förutspås ett småskaligt datacenter - edge cloud – växa i framtiden. På grund av dess användarnära natur kan tillväxten av edge clouds i tätområden orsaka problem med det befintliga kraftsystemet. Förutom denna kraftsystemutmaning kräver edge cloud också en högre resurskostnad än storskaliga datacenter på grund av skalfördelarna. I denna avhandling introduceras fyra alternativa energi- och kyltekniker för att hantera dessa utmaningar. Dessa fyra tekniker är solpanel, vertikalaxel vindturbin (VAWT), bakdörrvärmeväxlare (RDHx), och nedsänkningskylning. Detaljerad information om edge cloud erfordras för att förstå bidraget från dessa fyra tekniker. På grund av edge clouds tidiga stadium är all nödvändig data dock inte tillgänglig, vaför antaganden om görs. Förutom det krävs också en kostnadsmodell för edge cloud för att visa hur betydande bidraget från den alternativa tekniken är om den jämförs med den totala ägandekostnaden. I denna avhandling utökas kostnadsmodellen för edge cloud för de alternativa energi- och kylsystemscenarierna. Med antagen data för ett edge cloud genomförs en känslighetsanalys för att avgöra om alternativa energi- och kyltekniker kan sänka kostnaden för edge cloud-resurser eller inte. Kostnadsmodelleringen visar att VAWT och nedsänkningskylning inte är möjlig för det specifika antagna datacentret. Å andra sidan kan solpanel spara 4,55% av datacentrets elförbrukning (motsvarande 0,21% minskning av den totala kostnaden när den beräknas med det aktuella elpriset). Dessutom presterade RDHx bättre med 22,73% av datacenters elutgifter (motsvarande 8,35% av besparingen från totalkostnaden när den beräknas med det aktuella elpriset).

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Tena, Frezewd Lemma. « Energy-Efficient Key/Value Store ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-228586.

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Energy conservation is a major concern in todays data centers, which are the 21st century data processing factories, and where large and complex software systems such as distributed data management stores run and serve billions of users. The two main drivers of this major concern are the pollution impact data centers have on the environment due to their waste heat, and the expensive cost data centers incur due to their enormous energy demand. Among the many subsystems of data centers, the storage system is one of the main sources of energy consumption. Among the many types of storage systems, key/value stores happen to be the widely used in the data centers. In this work, I investigate energy saving techniques that enable a consistent hash based key/value store save energy during low activity times, and whenever there is an opportunity to reuse the waste heat of data centers.

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Yildirim, Ismail. « Surface Free Energy Characterization of Powders ». Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/27525.

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Microcalorimetric measurements and contact angle measurements were conducted to study the surface chemistry of powdered minerals. The contact angle measurements were conducted on both flat and powdered talc samples, and the results were used to determine the surface free energy components using Van Oss-Chaudhury-Good (OCG) equation. It was found that the surface hydrophobicity of talc increases with decreasing particle size. At the same time, both the Lifshitz-van der Waals (gSLW) and the Lewis acid-base (gSAB) components (and, hence, the total surface free energy (gS)) decrease with decreasing particle size. The increase in the surface hydrophobicity and the decrease in surface free energy (gS) can be attributed to preferential breakage of the mineral along the basal plane, resulting in the exposure of more basal plane surfaces to the aqueous phase. Heats of immersion measurements were conducted using a flow microcalorimeter on a number of powdered talc samples. The results were then used to calculate the contact angles using a rigorous thermodynamic relation. The measured heat of immersion values in water and calculated contact angles showed that the surface hydrophobicity of talc samples increase with decreasing particle size, which agrees with the direct contact angle measurements. A relationship between advancing water contact angle qa, and the heat of immersion (-DHi) and surface free energies was established. It was found that the value of -DHi decrease as qa increases. The microcalorimetric and direct contact angle measurements showed that acid-base interactions play a crucial role in the interaction between talc and liquid. Using the Van Oss-Chaudhury-Goodâ s surface free energy components model, various talc powders were characterized in terms of their acidic and basic properties. It was found that the magnitude of the Lewis electron donor, gS-, and the Lewis electron acceptor, gS+, components of surface free energy is directly related to the particle size. The gS- of talc surface increased with decreasing particle size, while the gS+ slightly decreased. It was also found that the Lewis electron-donor component on talc surface is much higher than the Lewis electron-acceptor component, suggesting that the basal surface of talc is basic. The heats of adsorption of butanol on various talc samples from n-heptane solution were also determined using a flow microcalorimeter. The heats of adsorption values were used to estimate % hydrophilicity and hydrophobicity and the areal ratios of the various talc samples. In addition, contact angle and heat of butanol adsorption measurements were conducted on a run-of-mine talc sample that has been ground to two different particle size fractions, i.e., d50=12.5 mm and d50=3.0 mm, respectively. The results were used to estimate the surface free energy components at the basal and edge surfaces of talc. It was found that the total surface free energy (gS) at the basal plane surface of talc is much lower than the total surface free energy at the edge surface. The results suggest also that the basal surface of talc is monopolar basic, while the edge surface is monopolar acidic. The results explain why the basicity of talc surface increases with decreasing particle size as shown in the contact angle and microcalorimetric measurements. Furthermore, the effects of the surface free energies of solids during separation from each other by flotation and selective flocculation were studied. In the present work, a kaolin clay sample from east Georgia was used for the beneficiation tests. First, the crude kaolin was subjected to flotation and selective flocculation experiments to remove discoloring impurities (i.e., anatase (TiO2) and iron oxides) and produce high-brightness clay with GE brightness higher than 90%. The results showed that a clay product with +90% brightness could be obtained with recoveries (or yields) higher than 80% using selective flocculation technique. It was also found that a proper control of surface hydrophobicity of anatase is crucially important for a successful flotation and selective flocculation process. Heats of immersion, heats of adsorption and contact angle measurements were conducted on pure anatase surface to determine the changes in the surface free energies as a function of the surfactant dosage (e.g. hydroxamate) used for the surface treatment. The results showed that the magnitude of the contact angle and, hence, the surface free energy and its components on anatase surface varies significantly with the amount of surfactant used for the surface treatment.
Ph. D.

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Harmassi, Mariem. « Thing-to-thing context-awareness at the edge ». Thesis, La Rochelle, 2019. http://www.theses.fr/2019LAROS037.

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L'Internet des objets (IdO) comprend aujourd'hui une riche offre d'objets connectés, qui permettent de collecter et de partager en continu des données hétérogènes se rapportant à leurs environnements. Ceci a permis l'émergence d'un nouveau type d'applications, qui sont basées sur ces données et permettent de faciliter la vie des citoyens. Ces applications de l'Internet des objets sont dites « sensibles au contexte ». Grâce aux données collectées sur le contexte de l'utilisateur, elles sont en mesure d'adapter leur comportement de manière autonome, sans intervention humaine. Dans cette thèse, nous proposons un nouveau paradigme autour des interactions objet-à-objet, nommé « Interactions objet-à-objet pour la sensibilité au contexte en bordure de réseaux ». Ce dernier, permet de tenir compte d'un nouveau type de contexte, paradoxalement à la notion conventionnelle de « sensibilité au contexte » qui se limite au contexte de l’utilisateur d’une application. Ainsi nous proposons de nous intéresser pour la première fois au contexte des objets en tant que composante même de l’application. Cette thèse vise à doter les objets connectés d’un certain degré d'intelligence, leur permettant de comprendre leur propre environnement et d’en tenir compte dans leurs interactions objet-à-objet. Les contributions majeures de cette thèse se focalisent sur deux modules principaux. Nous proposons, dans un premier temps, un module d’identification de contextes capable de capter les contextes des objets mobiles et de délivrer ce genre d’information de contexte de façon exacte et continue. Sur la base de cette information de contexte assurée par le premier module, nous proposons un deuxième module de collecte de données sensible aux contextes de déploiement des objets connectés. Afin que ceci soit possible, de nombreux verrous restent à lever. Concernant le premier module d’identification de contexte, le premier défi rencontré afin de permettre aux objets connectés de devenir sensibles au contexte est (i) Comment peut-on assurer une identification de contexte exacte pour des objets déployés dans des environnements incontrôlables ? Pour ce faire, nous proposons dans notre premier travail un raisonneur dédié à l'apprentissage et le raisonnement sur le contexte [1]. Le raisonneur proposé est fondé sur une stratégie coopérative entre les différents dispositifs IdO d'un même voisinage. Cette coopération vise à un échange mutuel des données parmi les ressources disponibles d'un même voisinage. La deuxième problématique rencontrée est (ii) Comment peut-on assurer une identification de contexte continue pour des nœuds mobiles appartenant à des réseaux opportunistes ? Nous devons tout d'abord leur permettre de découvrir un maximum de voisins afin d'établir un échange avec. Afin de répondre à cette deuxième problématique nous proposons WELCOME un protocole de découverte des voisinages éco énergétique et à faible latence [2] qui permettra de diminuer considérablement les collisions sur la base d’une découverte de voisinage à faible coût en termes de latence et d’énergie. La troisième problématique, se rapportant au module de collecte de données sensible au contexte, est (iii) Comment peut-on assurer une collecte efficace et précise sur la base du contexte physique de déploiement des capteurs. En effet, d’une part tenir compte de l’information de contexte des capteurs, permet d'éviter toutes transmissions inutiles ou redondante de données. D’autre part, la contextualisation des données implique un partage et donc des transmissions de messages. La question ici (iii) Comment peut-on contextualiser au mieux le plus grand nombre d'objets connectés tout en préservant au mieux leurs ressources énergétiques. Afin de répondre à cette question, nous proposons un Publish-Subscribe à la fois sensible au contexte et éco énergétique basé sur un jeu coalitionnel dynamique qui permet de résoudre ces conflits d’intérêts entre les sources dans un réseau
Internet of Things IoT (IoT) today comprises a plethora of different sensors and diverse connected objects, constantly collecting and sharing heterogeneous sensory data from their environment. This enables the emergence of new applications exploiting the collected data towards facilitating citizens lifestyle. These IoT applications are made context-aware thanks to data collected about user's context, to adapt their behavior autonomously without human intervention. In this Thesis, we propose a novel paradigm that concern Machine to Machine (M2M)/Thing To Thing (T2T) interactions to be aware of each other context named \T2T context-awareness at the edge", it brings conventional context-awareness from the application front end to the application back-end. More precisely, we propose to empower IoT devices with intelligence, allowing them to understand their environment and adapt their behaviors based on, and even act upon, the information captured by the neighboringdevices around, thus creating a collective intelligence. The first challenge we face in order to make IoT devices context-aware is (i) How can we extract such information without deploying any dedicated resources for this task? To do so we propose in our first work a context reasoner [1] based a cooperation among IoT devices located in the same surrounding. Such cooperation aims at mutually exchange data about each other context. To enable IoT devices to see, hear, and smell the physical world for themselves, we need firstly to make them connected to share their observations. For a mobile and energy- constrained device, the second challenge we face is (ii) How to discover as much neighbors as possible in its vicinity while preserving its energy resource? We propose Welcome [2] a Low latency and Energy efficient neighbor discovery scheme that is based on a single-delegate election method. Finally, a Publish-Subscribe that take into account the context at the edge of IoT devices, can greatly reduce the overhead and save the energy by avoiding unnecessary transmission of data that doesn't match application requirements. However, if not thought about properly building such T2T context-awareness could imply an overload of subscriptions to meet context-estimation needs. So our third contribution is (iii) How to make IoT devices context-aware while saving energy. To answer this, We propose an Energy efficient and context-aware Publish-Subscribe [3] that strike a balance between energy-consumption due to context estimation and energy-saving due to context-based filtering near to data sources

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Miccoli, Roberta. « Implementation of a complete sensor data collection and edge-cloud communication workflow within the WeLight project ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22563/.

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This thesis aims at developing the full workflow of data collection from a laser sensor connected to a mobile application, working as edge device, which subsequently transmits the data to a Cloud platform for analysing and processing. The project is part of the We Light (WErable LIGHTing for smart apparels) project, in collaboration with TTLab of the INFN (National Institute of Nuclear Physics). The goal of We Light is to create an intelligent sports shirt, equipped with sensors that take information from the external environment and send it to a mobile device. The latter then sends the data via an application to an open source Cloud platform in order to create a real IoT system. The smart T-shirt is capable of emitting different levels of light depending on the perceived external light, with the aim of ensuring greater safety for road sports people. The thesis objective is to employ a prototype board provided by the CNR-IMAMOTER to collect data and send it to the specially created application via Bluetooth Low Energy connection. Furthermore, the connection between the edge device and the Thingsboard IoT platform is performed via MQTT protocol. Several device authentication techniques are implemented on TB and a special dashboard is created to display data from the IoT device; the user is also able to view data in numerical and even graphical form directly in the application without necessarily having to access TB. The app created is useful and versatile and can be adapted to be used for other IoT purposes, not only within the We Light project.

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Sigwele, Tshiamo. « Energy Efficient Cloud Computing Based Radio Access Networks in 5G. Design and evaluation of an energy aware 5G cloud radio access networks framework using base station sleeping, cloud computing based workload consolidation and mobile edge computing ». Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/16062.

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Fifth Generation (5G) cellular networks will experience a thousand-fold increase in data traffic with over 100 billion connected devices by 2020. In order to support this skyrocketing traffic demand, smaller base stations (BSs) are deployed to increase capacity. However, more BSs increase energy consumption which contributes to operational expenditure (OPEX) and CO2 emissions. Also, an introduction of a plethora of 5G applications running in the mobile devices cause a significant amount of energy consumption in the mobile devices. This thesis presents a novel framework for energy efficiency in 5G cloud radio access networks (C-RAN) by leveraging cloud computing technology. Energy efficiency is achieved in three ways; (i) at the radio side of H-C-RAN (Heterogeneous C-RAN), a dynamic BS switching off algorithm is proposed to minimise energy consumption while maintaining Quality of Service (QoS), (ii) in the BS cloud, baseband workload consolidation schemes are proposed based on simulated annealing and genetic algorithms to minimise energy consumption in the cloud, where also advanced fuzzy based admission control with pre-emption is implemented to improve QoS and resource utilisation (iii) at the mobile device side, Mobile Edge Computing (MEC) is used where computer intensive tasks from the mobile device are executed in the MEC server in the cloud. The simulation results show that the proposed framework effectively reduced energy consumption by up to 48% within RAN and 57% in the mobile devices, and improved network energy efficiency by a factor of 10, network throughput by a factor of 2.7 and resource utilisation by 54% while maintaining QoS.

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Kheffache, Mansour. « Energy-Efficient Detection of Atrial Fibrillation in the Context of Resource-Restrained Devices ». Thesis, Luleå tekniska universitet, Datavetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76394.

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eHealth is a recently emerging practice at the intersection between the ICT and healthcare fields where computing and communication technology is used to improve the traditional healthcare processes or create new opportunities to provide better health services, and eHealth can be considered under the umbrella of the Internet of Things. A common practice in eHealth is the use of machine learning for a computer-aided diagnosis, where an algorithm would be fed some biomedical signal to provide a diagnosis, in the same way a trained radiologist would do. This work considers the task of Atrial Fibrillation detection and proposes a novel range of algorithms to achieve energy-efficiency. Based on our working hypothesis, that computationally simple operations and low-precision data types are key for energy-efficiency, we evaluate various algorithms in the context of resource-restrained health-monitoring wearable devices. Finally, we assess the sustainability dimension of the proposed solution.

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Speranza, Nicholas A. « Adaptive Two-Stage Edge-Centric Architecture for Deeply-Learned Embedded Real-Time Target Classification in Aerospace Sense-and-Avoidance Applications ». Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright1621886997260122.

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Saroka, Vasil. « Theory of optical and THz transitions in carbon nanotubes, graphene nanoribbons and flat nanoclusters ». Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/28863.

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This thesis is devoted to the optical properties of low-dimensional structures based on such two-dimensional materials as graphene, silicene and phosphorene. We investigate optical properties of a variety of quasi-one dimensional and quasi-zero-dimensional structures, which are promising for future optoelectronics. Primarily we focus on their low-energy optical properties and how these properties are influenced by the structures’ geometry, external fields, intrinsic strain and edge disorder. As a consequence of this endeavor, we find several interesting effects such as correlation between the optical properties of tubes and ribbons whose periodic and ‘hard wall’ boundary conditions are matched and a universal value of matrix element in narrow-gap tubes and ribbons characterizing probability of transitions across the band gap opened up by intrinsic strain originating from the tube’s surface curvature or ribbon’s edge relaxation. The analytical study of the gapped 2D Dirac materials such as silicene and germanene, which have some similarity to the aforementioned quasi-one-dimensional systems in terms of physical description, reveals a valley- and polarization-dependent selection rules. It was also found that absorption coefficient should change in gapped materials with increasing frequency and become a half of its value for gap edge transitions when the spectrum is linear. Our analysis of the electronic properties of flat clusters of silicene and phosphorene relates the emergence and the number of the peculiar edge states localized at zero energy, so-called zero-energy states, which are know to be of topological origin, to the cluster’s structural characteristics such as shape and size. This allows to predict the presence and the number of such states avoiding complicated topological arguments and provides a recipes for design of metallic and dielectric clusters. We show that zero-energy states are optically active and can be efficiently manipulated by external electric field. However, the edge disorder is important to take into account. We present a new fractal-based methodology to study the effects of the edge disorder which can be applied also to modeling of composite materials. These finding should be useful in design of optoelectronic devices such as tunable emitters and detectors in a wide region of electromagnetic spectrum ranging form the mid-infrared and THz to the optical frequencies.

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Spittel, Daniel, Jan Poppe, Christian Meerbach, Christoph Ziegler, Stephen G. Hickey et Alexander Eychmüller. « Absolute Energy Level Positions in CdSe Nanostructures from Potential-Modulated Absorption Spectroscopy (EMAS) ». American Chemical Society, 2017. https://tud.qucosa.de/id/qucosa%3A33353.

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Semiconductor nanostructures such as CdSe quantum dots and colloidal nanoplatelets exhibit remarkable optical properties, making them interesting for applications in optoelectronics and photocatalysis. For both areas of application a detailed understanding of the electronic structure is essential to achieve highly efficient devices. The electronic structure can be probed using the fact that optical properties of semiconductor nanoparticles are found to be extremely sensitive to the presence of excess charges that can for instance be generated by means of an electrochemical charge transfer via an electrode. Here we present the use of EMAS as a versatile spectroelectrochemical method to obtain absolute band edge positions of CdSe nanostructures versus a well-defined reference electrode under ambient conditions. In this, the spectral properties of the nanoparticles are monitored with respect to an applied electrochemical potential. We developed a bleaching model that yields the lowest electronic state in the conduction band of the nanostructures. A change in the band edge positions caused by quantum confinement is shown both for CdSe quantum dots and for colloidal nanoplatelets. In the case of CdSe quantum dots these findings are in good agreement with tight binding calculations. The method presented is not limited to CdSe nanostructures but can be used as a universal tool. Hence, this technique allows the determination of absolute band edge positions of a large variety of materials used in various applications

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Schumann, Matthew Thomas. « The effect of ion-orbit-loss on the distribution of ion, energy and momentum from the edge plasma into the scrape-off layer in tokamaks ». Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53519.

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Some of the outflowing ions in the plasma edge have sufficient energy to access orbits which allow them to free-stream out of the confined plasma region and be lost to the wall or divertor. The effects of this ion-orbit-loss (IOL) on the poloidal distribution of ion, energy and momentum fluxes from the plasma edge into the tokamak scrape-off layer (SOL) are analyzed for a representative DIII-D H-mode discharge. IOL yields large fluxes of particle, energy and momentum, distributed poloidally over the SOL, but predominantly into the outboard SOL, significantly changing the fluxes due to transport processes for confined ions within the edge plasma. An intrinsic co-current rotation in the edge of the plasma is produced by the preferential loss of counter-current ions

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Coppini, Gabriele. « Applicazioni dei fasci quasi-monocromatici in medicina ». Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10405/.

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I raggi X, a partire dalla loro scoperta, avvenuta nel 1895 ad opera di Wilhelm Conrad Röntgen, si sono rivelati un potentissimo mezzo per lo studio della materia. In particolare in campo medico hanno permesso la nascita della diagnostica per immagini che, parallelamente allo sviluppo delle tecnologie, è diventata un mezzo imprescindibile per lo studio delle patologie. Negli ultimi decenni molti studi sono stati compiuti in particolare sui vantaggi dell’utilizzo nell’imaging di raggi X monocromatici in sostituzione dell’usuale radiazione policromatica. Con il seguente elaborato si ha l’intento di fornire un quadro generale sulla fisica dei raggi X, sulla loro interazione con la materia e sugli attuali metodi di produzione di fasci monocromatici e quasi-monocromatici, con particolare attenzione all'utilizzo su vasta scala. Sono state infine trattate le principali applicazioni della radiazione monocromatica e quasi-monocromatica nelle tecniche di imaging medico.

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SCOPECE, DANIELE. « Surface and interface effects on the stability of SiGe nanoislands ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28452.

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Deposition of Ge upon Si substrates is the prototype of the mechanism called Stranski- Krastanov growth, i.e. the self-assembled formation of 3D islands, following the formation of a thin, 2D Wetting Layer. As is shown in Chapter 1, the nucleation of these islands is random and non-uniform when the deposition is performed upon the standard Si(001) substrate. Deposition of SiGe on different substrates of Si can lead, however, to a high degree of uniformity. Some examples are described in Chapters 3 and 4. The aim of this thesis is to supply a quantitative analysis for some peculiar phenomena concerning island nucleation that occurs on these non-standard substrates. This is performed through the evaluation of the internal energy of the island (including also effects on the substrate) as discussed at length in Chapter 2, where the elastic, surface and edge energy contributions are described, focusing particular attention to the second one, that turns out to be quite complicated. Particular attention is devoted to the island nucleation on stepped substrates of Si (Chapter 4). An in-depth analysis of the formation of faceting upon the substrate Si(1 1 10) is carried out in Chapter 5, whereas Chapter 6 deals with the transition from the faceting to three-dimensional islands on this peculiar system. Conclusions are drawn in Chapter 7. Appendices A and B contain some additional information regarding the elastic field and the description of surfaces. In Appendix C an analysis of the strained surface energy is carried out. In Appendix D some preliminary work performed during the PhD period on other impor- tant surfaces for the SiGe system is discussed. Finally at page 203 a Curriculum Vitae is reported.

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Lobato, Emilio Marcus de Castro. « Determination of Surface Free Energies and Aspect Ratio of Talc ». Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35743.

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Microcalorimetric measurements and contact angle measurements were conducted to assess the surface chemistry of the mineral talc. The contact angles were performed on both flat and powdered samples and the results were used to determine the surface free energy components and parameters (SFEC) using the acid-base theory for solids, according to the van Oss-Chaudhury-Good approach. It was found that the surface hydrophobicity of talc increases with decreasing particle size up to a limit after which hydrophilicity (polarity) increases. The increase in hydrophobicity was attributed to the increase of the delamination of the lamellar talc particles. Delamination is a comminution mechanism that preferentially exposes talc's hydrophobic basal planes, while fracture is another mechanism that breaks the lamellae, rupturing covalent bonds thus exposing more hydrophilic edge surfaces. The decrease in hydrophobicity, beyond a given particle size, could be related to the prevail of fracture over delamination during grinding which generated more hydrophilic edge surfaces.

The flow microcalorymetry combined with thin layer wicking allowed the separate estimation of the SFEC at the basal plane and edge surfaces of talc. The results suggested that the basal surface of talc is monopolar basic, while the edge surface is monopolar acidic, which are in agreement with the crystal structure of the mineral.

The combination of two particle size distribution techniques, which are based on different physical principles, permitted the quantitative determination of the aspect ratio of highly anisometric particles, such as talc. The same trend obtained using flow microcalorimetry was observed for the evolution of the aspect ratio as a function of particle fineness, i.e. the fracture prevails over delamination after achieving a maximum aspect ratio value of about 35. The agreement between two distinct methods was considered rather encouraging.

Master of Science

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Shirin, Abkenar Forough. « Towards Hyper-efficient IoT Networks Using Fog Paradigm ». Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/28951.

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Fog computing was emerged as a treasured paradigm to improve the efficiency of the typical cloud of things (CoT) architecture of the Internet of Things (IoT) networks. Contrasting to the CoT in which the resource-rich high-performance data centers (DCs) are located far from the energy-constrained terminal nodes (TNs), fog nodes (FNs) in fog-enabled architecture provide computing resources in the proximity of the TNs. Therefore, the TNs consume less energy to offload their generated tasks to the FNs rather than the cloud DCs. Moreover, shortening the distance between the TNs and the FNs results in alleviating the transmission latency for the delay-sensitive tasks generated by the TNs. This is more significant for specific applications, such as smart healthcare, search and rescue, and disaster management, wherein making a prompt decision is vital to save lives. However, Fog-IoT networks still suffer from challenges regarding energy efficiency and provisioning quality of service (QoS) requirements, especially in terms of delay and throughput. The motivation behind this thesis is to tackle the corresponding challenges and improve the performance of the Fog-IoT networks. To this end, novel optimization problems, models, methods, and algorithms are proposed that mainly focus on the energy efficiency improvement and QoS provisioning in Fog-IoT networks. Moreover, due to the importance of the mobility of FNs, the contributions of the thesis encompass improving the performance of Fog-IoT networks with respect to both fixed and mobile FNs.

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Dlamini, Thembelihle. « Core Network Management Procedures for Self-Organized and Sustainable 5G Cellular Networks ». Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3422837.

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This thesis investigates resource management procedures, within the Multi-access Edge Computi ng (MEC) paradigm, to obtain energy savings and guarantee Quality of Service(QoS) in Mobile Networks (MNs). Here, we enable energy savings within green-aware network apparatuses (i.e., communication and computing facilities) through the application of learning and control techniques, together with energy management procedures (BS sleep mode, VM soft-scaling, tuning of transmission drivers). In this study, we consider the MEC deployment scenarios suggested by ETSI and mobile operators for our system models. Firstly, we investigate energy-saving strategies within a remote site fully powered by only green/renewable energy (solar and wind). Here, we consider a single Base Station (BS) co-located with the MEC server, i.e., the BS is empowered with computing capabilities. To address the energy consumption problem within the remote site, we propose an online algorithm for edge network management. The algorithm make use of a Long Short-Term Memory (LSTM) neural network for estimating the short-term future traffic load and harvested energy, and control theory, specifically the Limited Lookahead Control (LLC) principles, for foresighted optimization. It also make use of energy management procedures, i.e., BS sleep modes and Virtual Machine (VM) soft-scaling (the reduction of computing resources per time instance). To obtain the energy savings and guarantee QoS, per time instance, the algorithm considers the future BS loads, onsite green energy available and then provisions edge network resources based on the learned information. Secondly, we study the energy consumption problem within an environment where BSs are densely-deployed, i.e., similar to an urban or semi-urban scenario. This work extend the energy consumption problem from a single BS case to multiple BSs. Here, each BS is powered by hybrid energy supplies (solar and power grid) and also empowered with computation capabilities (each BS is co-located with a MEC server). Towards edge system management, we propose a controller-based network architecture for managing energy harvesting (EH) BSs empowered with computation capabilities where on/off switching strategies allow BSs and VMs to be dynamically switched on/off, depending on the traffic load and the harvested energy forecast, over a given look-ahead prediction horizon. To solve the energy consumption minimization problem in a distributed manner, the controller partitions the BSs into clusters based on their location; then, for each cluster, it minimizes a cost function capturing the individual communication site energy consumption and the users’ QoS. To manage the communication sites, the controller performs online supervisory control by forecasting the traffic load and the harvested energy using a LSTM neural network, which is utilized within a LLC policy to obtain the system control actions that yield the desired trade-off between energy consumption and QoS. Finally, we investigate the energy consumption problem within a virtualized MEC server placed in proximity to a group of BSs. To address this challenge, we consider a computing-plus-communication energy model, within the MEC paradigm, where we focus on the communication-related energy cost in addition to the energy drained due to computing processes. Towards server management, an online algorithm based on traffic engineering and MEC Location Service is proposed. To obtain the energy savings and QoS guarantee, we jointly launch an optimal number of VMs for computing and transmission drivers coupled with the location-aware traffic routing for real-time data transfers. In order to efficiently provisioned edge system resources, we forecast the server workloads and harvested energy by using a LSTM neural network and the output is then used within the LLC-based algorithm. Our numerical results, obtained through trace-driven simulations, show that the proposed optimization strategies (algorithms) leads to a considerable reduction in the energy consumed by the edge computing and communication facilities, promoting energy self-sustainability within the MN through the use of green energy.

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Khaliq, Anzar. « Interface Chemistry and Energy Level Alignment of Silicon / Organic Semiconductor Heterostructures studied with Synchrotron Radiation X-ray Photoelectron Spectroscopy and Near Edge X-ray Absorption Fine Structure ». Paris 6, 2012. http://www.theses.fr/2012PA066224.

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To date the most widely used inorganic semiconductor is silicon (Si). There is no denial to its contribution in the current standing of micro-electronics but with time its limitations have been exposed, especially the absence of coupling with opto-electronics due to its indirect band gap. Devices which consist of a hybrid of both organic (e. G. Dyes) and Si are thought to be an interesting extension of the next generation Si-based devices. In this context, the modification of Si with organic molecules represents a promising approach for the incorporation of new functionalities into semiconductors (light harvesting, light emission). This has motivated the current research efforts on organic functionalization of the Si(001) surface, via a reaction of a functional group of the organic molecules with the dimers of the Si (001)– 2×1 surface. However, many interesting molecular objects grafted directly on semiconductor surface are multifunctional, which in most cases leads to competitive reactions with the surface silicon atoms and to multiple adsorption geometries. We have tackled this problem by passivating the silicon surface with cyclopentene (C5H8). The passivated layer has then been used as the substrate to grow molecular layers of TCNQ, (Tetracyanoquinodimethane) and PTCDA (3,4,9,10-perylene tetra carbonyl dianhydride). X-ray Photoelectron Spectroscopy (XPS) and Near Edge X-ray Absorption Fine Structure Spectroscopy (NEXAFS) have been used to determine the precise adsorption geometry of the buffer layer along with the molecular orientation of the adsorbate. Using the same techniques, the chemical environment of the organic / inorganic heterostructure interface has been studied in detail (PTCDA-cyclopentene / Si(001), TCNQ-cyclopentene / Si(001)) along with the molecular orientation (as function of film thickness) and the variations in band alignment. The latter studies may open new avenues in the development of these heterostructures in which modified silicon surfaces could be used as charge injecting / blocking electrodes.

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Memon, Saim. « Design, fabrication and performance analysis of vacuum glazing units fabricated with low and high temperature hermetic glass edge sealing materials ». Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/14562.

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Vacuum glazing is a vital development in the move to more energy efficient buildings. In vacuum glazing, an evacuated cavity supresses gaseous conduction and convection to provide high thermal resistance. A high vacuum pressure (less than 0.1 Pa) is required and must be maintained by a hermetic seal around the periphery, currently formed with either indium (i.e. low temperature sealing method) or solder glass (i.e. high temperature sealing method). This thesis reports the results of an experimental and theoretical investigation into the development of new low temperature (less than 200°C) and novel high temperature (up to 450°C) glass edge seals. A new low temperature composite edge seal was developed in which double and triple vacuum glazings each of dimensions 300x300mm were fabricated with measured vacuum pressures of 4.6x10-2Pa and 4.8x10-2Pa achieved respectively. A three dimensional finite element model of the fabricated design of composite edge sealed triple vacuum glazing was developed.

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Dahlin, Linus, et Marcus Hedman. « Undersökning av värmeförluster genom kantbalk vid användning av golvvärme : En simuleringsundersökning i COMSOL Multiphysics ». Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-27163.

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I Sverige ställs allt högre krav på nya byggnader genom bestämmelser och lagar som påverkar energianvändningen. Byggnader kan värmas upp med hjälp av olika typer av distributionssystem såsom radiatorer och golvvärme. Värmebehovet hos byggnaden baseras på hur mycket värmeenergi som behövs för att uppnå termisk komfort. För att begränsa energianvändningen används isolering i syfte att minimera värmeförlusterna genom byggnadens klimatskärm. Denna undersökning syftar till att undersöka förluster som sker genom kantbalken vid användning av vattenburet golvvärmesystem och hur dessa förluster påverkas då grundkonstruktionen tilläggsisoleras på olika sätt. Kantbalken är den förstärkta del som finns under markplattan/platta på mark, tar upp krafter från bärande väggar och finns efter sidorna på byggnaden. Golvvärme är en uppvärmningsteknik där slingor placeras i grundkonstruktionen och förser byggnader med dess värmebehov. Golvvärmesystem installeras på olika sätt beroende på byggnaders förutsättningar och är ett energieffektivt uppvärmningssätt i kombination med värmepump. Undersökningen påbörjades genom att skapa en förenklad modell som behandlar en 2-dimensionell kantbalksutformning i COMSOL Multiphysics, som är ett program för modellering där statiska och dynamiska simuleringar genomförs i modeller med hjälp av finita-elementmetoden. Fyra modeller skapades med två olika CC-mått (centrumavstånd) och två olika golvmaterial. Därefter skapades tre fall med förbättrande åtgärder för att öka kantbalkens isolerförmåga. Dynamiska simuleringar genomfördes och hade tidsintervallet 365 dagar med varierande utetemperatur. När utetemperaturen varierade var effektbehovet hos golvvärmen olika vilket ledde till att golvvärmetemperaturen justerades efter utetemperaturen för att upprätthålla samma temperatur på golvytan. Resultaten visar att kantbalken står för cirka 50 % av markkonstruktionsförlusterna med installerat L-element. Vid komplettering av konstruktionen med två fall av tillläggsisolering framkom inga större förändringar i resultaten. Genom att byta ut L-elementet till ett U-element minskar dock värmeförlusterna genom kantbalken till ca 30 %. Markkonstruktionsförluster är de förluster som överförs från byggnaden till närliggande mark.
Through laws and regulations in Sweden, increasing demands regarding energy use are affecting new buildings. A building achieving thermal comfort is attaining its thermal needs and can be done so through several types of distribution systems such as radiators and underfloor heating. Insulation is used to limit the amount of energy lost through the building’s envelope whilst keeping up with the thermal needs. This study is meant to examine the thermal leakage around the edge beam installa-tion when using a waterborne underfloor heating system and different sets of insulation are installed in the ground-related construction. The edge beam is the reinforced part located around the perimeter of the building absorbing forces from supporting walls. The study started with creating and using a simplified model in COMSOL Multiphysics to look at a two-dimensional edge beam formation. COMSOL Multiphysics is a software used for modeling different static and dynamic simulations via the finite element method. Four models were created using two different CC-dimensions (center to center distance) and two different floor materials. After this, three cases were created with improved circumstances regarding the ability to isolate heat around the edge beam. Dynamic simulations were made and calculated a year’s worth of varying outdoor temperatures. When the outdoor temperature changes, the requirements of the underfloor heating output also change which leads to its temperature adapting due to the outdoor temperature. The results indicate the edge beam related heat losses make up of about 50 % of the ground-related construction losses in the model. When completing the design with two instances of additional insulation, no major changes were found in the results. However, replacing the L-shaped insulation around the edge beam with a U-shaped insulation reduces heat losses through the edge beam to about 30 %. Ground-related construction losses are the losses transferred from the building to adjacent ground.

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Thorsell, Thomas. « Advances in Thermal Insulation : Vacuum Insulation Panels and Thermal Efficiency to Reduce Energy Usage in Buildings ». Doctoral thesis, KTH, Byggnadsteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-90745.

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We are coming to realize that there is an urgent need to reduce energy usage in buildings and it has to be done in a sustainable way. This thesis focuses on the performance of the building envelope; more precisely thermal performance of walls and super insulation material in the form of vacuum insulation. However, the building envelope is just one part of the whole building system, and super insulators have one major flaw: they are easily adversely affected by other problems in the built environment. Vacuum Insulation Panels are one fresh addition to the arsenal of insulation materials available to the building industry. They are composite material with a core and an enclosure which, as a composite, can reach thermal conductivities as low as 0.004 W/(mK). However, the exceptional performance relies on the barrier material preventing gas permeation, maintaining a near vacuum into the core and a minimized thermal bridge effect from the wrapping of barrier material round the edge of a panel. A serpentine edge is proposed to decrease the heat loss at the edge. Modeling and testing shows a reduction of 60% if a reasonable serpentine edge is used. A diffusion model of permeation through multilayered barrier films with metallization coatings was developed to predict ultimate service life. The model combines numerical calculations with analytical field theory allowing for more precise determination than current models. The results using the proposed model indicate that it is possible to manufacture panels with lifetimes exceeding 50 years with existing manufacturing. Switching from the component scale to the building scale; an approach of integrated testing and modeling is proposed. Four wall types have been tested in a large range of environments with the aim to assess the hygrothermal nature and significance of thermal bridges and air leakages. The test procedure was also examined as a means for a more representative performance indicator than R-value (in USA). The procedure incorporates specific steps exposing the wall to different climate conditions, ranging from cold and dry to hot and humid, with and without a pressure gradient. This study showed that air infiltration alone might decrease the thermal resistance of a residential wall by 15%, more for industrial walls. Results from the research underpin a discussion concerning the importance of a holistic approach to building design if we are to meet the challenge of energy savings and sustainability. Thermal insulation efficiency is a main concept used throughout, and since it measures utilization it is a partial measure of sustainability. It is therefore proposed as a necessary design parameter in addition to a performance indicator when designing building envelopes. The thermal insulation efficiency ranges from below 50% for a wood stud wall poorly designed with incorporated VIP, while an optimized design with VIP placed in an uninterrupted external layer shows an efficiency of 99%, almost perfect. Thermal insulation efficiency reflects the measured wall performance full scale test, thus indicating efficiency under varied environmental loads: heat, moisture and pressure. The building design must be as a system, integrating all the subsystems together to function in concert. New design methodologies must be created along with new, more reliable and comprehensive measuring, testing and integrating procedures. New super insulators are capable of reducing energy usage below zero energy in buildings. It would be a shame to waste them by not taking care of the rest of the system. This thesis details the steps that went into this study and shows how this can be done.
QC 20120228

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Zou, Yu. « Strained Semiconductor Quantum Dots - Electronic Band Structure and Multilayer Correlation ». Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1248029992.

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Thesis (M.S.)--University of Akron, Dept. of Electrical and Computer Engineering, 2009.
"August, 2009." Title from electronic thesis title page (viewed 10/7/2009) Advisor, Ernie Pan; Co-Advisor, Nathan Ida; Committee members, Malik Elbuluk, Igor Tsukerman; Department Chair, Alex De Abreu Garcia; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

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Gumeniuk, Roman, Lev Akselrud, Kristina O. Kvashnina, Walter Schnelle, Alexander A. Tsirlin, Caroline Curfs, Helge Rosner et al. « Ca3Pt4+xGe13−y and Yb3Pt4Ge13 : new derivatives of the Pr3Rh4Sn13 structure type ». Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138956.

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The new phases Ca3Pt4+xGe13−y (x = 0.1; y = 0.4; space group I213; a = 18.0578(1) Å; RI = 0.063; RP = 0.083) and Yb3Pt4Ge13 (space group P42cm; a = 12.7479(1) Å; c = 9.0009(1) Å; RI = 0.061, RP = 0.117) are obtained by high-pressure, high-temperature synthesis and crystallize in new distortion variants of the Pr3Rh4Sn13 type. Yb3Pt4Ge13 features Yb in a temperature-independent non-magnetic 4f14 (Yb2+) configuration validated by X-ray absorption spectra and resonant inelastic X-ray scattering data. Ca3Pt4+xGe13−y is diamagnetic (χ0 = −5.05 × 10−6 emu mol−1). The Sommerfeld coefficient γ = 4.4 mJ mol−1 K−2 for Ca3Pt4+xGe13−y, indicates metallic properties with a low density of states at the Fermi level in good agreement with electronic structure calculation (N(EF) = 3.3 eV−1/f.u.)); the Debye temperature (θD) is 398 K
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

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Chen, Han. « Characterization and Optimization of Silicon-strip Detectors for Mammography and Computed Tomography ». Doctoral thesis, KTH, Medicinsk bildfysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-184092.

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The goal in medical x-ray imaging is to obtain the image quality requiredfor a given detection task, while ensuring that the patient dose is kept as lowas reasonably achievable. The two most common strategies for dose reductionare: optimizing incident x-ray beams and utilizing energy informationof transmitted beams with new detector techniques (spectral imaging). Inthis thesis, dose optimization schemes were investigated in two x-ray imagingsystems: digital mammography and computed tomography (CT). In digital mammography, the usefulness of anti-scatter grids was investigatedas a function of breast thickness with varying geometries and experimentalconditions. The general conclusion is that keeping the grid is optimalfor breasts thicker than 5 cm, whereas the dose can be reduced without a gridfor thinner breasts. A photon-counting silicon-strip detector developed for spectral mammographywas characterized using synchrotron radiation. Energy resolution, ΔE/Ein, was measured to vary between 0.11-0.23 in the energy range 15-40 keV, which is better than the energy resolution of 0.12-0.35 measured inthe state-of-the-art photon-counting mammography system. Pulse pileup hasshown little effect on energy resolution. In CT, the performance of a segmented silicon-strip detector developedfor spectral CT was evaluated and a theoretical comparison was made withthe state-of-the-art CT detector for some clinically relevant imaging tasks.The results indicate that the proposed photon-counting silicon CT detector issuperior to the state-of-the-art CT detector, especially for high-contrast andhigh-resolution imaging tasks. The beam quality was optimized for the proposed photon-counting spectralCT detector in two head imaging cases: non-enhanced imaging and Kedgeimaging. For non-enhanced imaging, a 120-kVp spectrum filtered by 2half value layer (HVL) copper (Z = 29) provides the best performance. Wheniodine is used in K-edge imaging, the optimal filter is 2 HVL iodine (Z = 53)and the optimal kVps are 60-75 kVp. In the case of gadolinium imaging, theradiation dose can be minimized at 120 kVp filtered by 2 HVL thulium (Z =69).

QC 20160401

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Saeedi, Navid. « Une approche très efficace pour l'analyse du délaminage des plaques stratifiées infiniment longues ». Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1160/document.

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L'analyse des phénomènes locaux comme les effets de bord libre et le délaminage dans les structures multicouches nécessite des théories fines qui donnent une bonne description de la réponse locale. Étant donné que les approches tridimensionnelles sont, en général, très coûteuses en temps de calcul et en mémoire, des approches bidimensionnelles de type layerwise sont souvent utilisées. Dans ce travail de doctorat, un modèle layerwise en contrainte, appelé LS1, est appliqué au problème du multi-délaminage dans les plaques stratifiées invariantes dans le sens longitudinal. L'invariance dans la direction de la longueur nous permet d'aborder le problème analytiquement. Dans un premier temps, nous proposons une méthode analytique pour l'analyse des plaques multicouches multi-délaminées soumises à la traction uniaxiale. La singularité des contraintes interlaminaires aux bords libres et l'initiation du délaminage en mode III sont étudiées. Un modèle raffiné, nommé LS1 raffiné, est proposé pour améliorer les approximations dans les zones de singularités telles que les bords libres et les pointes de fissure. Les résultats du modèle raffiné sont validés en les comparant avec ceux obtenus par éléments finis tridimensionnels. Dans un deuxième temps, l'approche analytique proposée est étendue à la flexion cylindrique des plaques multicouches. La propagation du délaminage en modes I et II est étudiée et les approximations du modèle LS1 sont validées. À la fin, nous généralisons la méthode analytique proposée afin de prendre en considération tous les chargements invariants dans le sens longitudinal. L'approche finale permet d'analyser les plaques multicouches rectangulaires soumises à des charges invariantes sur les faces supérieure et inférieure, les forces ou les déplacements imposés sur les bords latéraux ainsi que quatre types de chargement sur les extrémités longitudinales: traction uniaxiale, flexion hors plan, torsion et flexion dans le plan. La solution analytique du modèle LS1 est obtenue pour une plaque stratifiée soumise à tous les chargements mentionnés ci-dessus. L'approche est validée en comparant avec la méthode des éléments finis tridimensionnels pour plusieurs types de chargement
The analysis of local phenomena such as free-edge effects and delamination in multilayered structures requires the accurate theories which can provide a good description of the local response. Since the three-dimensional approaches are generally very expensive in computational time and memory, the layerwise two-dimensional approaches are widely used. In this Ph.D. thesis, a stress layerwise model, called LS1, is applied to the multi-delamination problem in longitudinally invariant multilayered plates. The invariance in the longitudinal direction allows us to solve the problem analytically. At first, we propose an analytical method for the analysis of multi-delaminated multilayered plates subjected to the uniaxial traction. The free-edge interlaminaire stress singularities and the mode III delamination onset are investigated. A refined model, called Refined LS1, is proposed in order to improve the approximations in singularity zones such as free edges and crack tips. The results of the refined model are validated by comparing them with those obtained by a three-dimensional finite element model. Afterwards, the proposed analytical approach is extended to the cylindrical bending of the multilayered plates. The propagation of delamination in modes I and II is studied and the approximations of the LS1 model are validated. At last, we generalize the proposed analytical method to take into account all invariant loads in the longitudinal direction. The final approach allows us to analyze the rectangular multilayered plates subjected to invariant loads on the top and bottom surfaces, imposed displacements or forces at the lateral edges, and also four types of loading at the longitudinal ends: uniaxial traction, out-of-plane bending, torsion and in-plane bending. The analytical solution of the LS1 model is obtained for a laminated plate subjected to all the loads mentioned above. The approach is validated by comparison with the three-dimensional finite element method for various types of loading

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Svensson, Dennis, et Svärd Tobias Falk. « Mechanical dry grinding process of saw chain ». Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-39927.

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The cutting links on chainsaws needs to be sharpened regularly to retain its sharpness. The most effective way is to use a machine wheel grinder. However, due to high friction there is a high risk of tempering the steel and damaging the sustainability to wear, resulting in a dull cutting edge. In order to develop a grinding method that produces a good result every time, a series of parameters were tested in order to determine which combination of these generated the best grinding results. With all parameters established the results shows that the attributes of each grinding wheel are the main parameter controlling the grinding result. This project investigates the attributes of different grinding wheels and their impact on grinding results. By comparing the energy each grinding wheel uses to perform the same amount of work, each grinding wheels suitability is rated based on its performance. The calculations and the results from the analyses and tests show which of the grinding wheels performed the work with the lowest amount of increased energy.

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Gumeniuk, Roman, Lev Akselrud, Kristina O. Kvashnina, Walter Schnelle, Alexander A. Tsirlin, Caroline Curfs, Helge Rosner et al. « Ca3Pt4+xGe13−y and Yb3Pt4Ge13 : new derivatives of the Pr3Rh4Sn13 structure type ». Royal Society of Chemistry, 2012. https://tud.qucosa.de/id/qucosa%3A27796.

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The new phases Ca3Pt4+xGe13−y (x = 0.1; y = 0.4; space group I213; a = 18.0578(1) Å; RI = 0.063; RP = 0.083) and Yb3Pt4Ge13 (space group P42cm; a = 12.7479(1) Å; c = 9.0009(1) Å; RI = 0.061, RP = 0.117) are obtained by high-pressure, high-temperature synthesis and crystallize in new distortion variants of the Pr3Rh4Sn13 type. Yb3Pt4Ge13 features Yb in a temperature-independent non-magnetic 4f14 (Yb2+) configuration validated by X-ray absorption spectra and resonant inelastic X-ray scattering data. Ca3Pt4+xGe13−y is diamagnetic (χ0 = −5.05 × 10−6 emu mol−1). The Sommerfeld coefficient γ = 4.4 mJ mol−1 K−2 for Ca3Pt4+xGe13−y, indicates metallic properties with a low density of states at the Fermi level in good agreement with electronic structure calculation (N(EF) = 3.3 eV−1/f.u.)); the Debye temperature (θD) is 398 K.
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

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Rodrigues, Alessandro Roger. « Estudo da geometria de arestas de corte aplicadas em usinagem com altas velocidades de corte ». Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-03072005-134755/.

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Trata do estudo experimental da energia específica de corte e sua relação com parâmetros de usinagem, características geométricas e tribológicas das ferramentas, e material da peça usinada. Dentre as variáveis investigadas são destaques a profundidade de usinagem, velocidade de corte, raio de ponta, geometria de quebra-cavaco, tipo de revestimento das ferramentas, dureza, microestrutura e composição química do material da peça. Os seguintes materiais foram empregados nos ensaios: aços SAE 1213, 1020, 1045, ASTM H13 recozido e temperado, e liga de alumínio 2024. As medições de energia específica foram realizadas em uma máquina Charpy instrumentada por meio de um dinamômetro piezelétrico e um encoder ótico rotacional. Vários resultados puderam ser comparados aos obtidos em torno e centro de usinagem CNC devidamente instrumentados. Testes na condição HSM foram implementados nas máquinas-ferramentas. Todas as variáveis pesquisadas mostraram exercer influência sobre a energia específica. O aumento da profundidade de usinagem em 2,3 vezes causou diminuição da energia específica em 21%, na usinagem da liga de alumínio 2024. A elevação da velocidade de corte em torno de 70% conduziu a uma queda da energia específica de 24% para o aço SAE 1020. A geometria da ferramenta influiu mais decisivamente na energia específica sob velocidades de corte convencionais que na condição HSM. Pequenas variações na geometria do quebra-cavaco dos insertos causaram diminuição da energia específica de até 29%, para velocidade de corte convencional, e de 14% para HSM, na usinagem do aço H13 temperado. Diversos resultados de energia específica de corte medidos pelo ensaio Charpy proposto por este trabalho apresentaram boa concordância com os valores equivalentes fornecidos pela literatura científica
This thesis presents an experimental study about the specific cutting energy and its relation with cutting parameters, geometrical and tribological characteristics of tools, and workpiece material. Depth of cut, cutting speed, tool nose radius, chip-breaker geometry, tool coating, hardness, microstructure and chemical composition of the workpiece material are some investigated variables. The following workpiece materials were tested: SAE 1213, 1020, 1045, annealed and tempered ASTM H13 steels, and 2024 aluminum alloy. The specific cutting energy values were measured by using a Charpy machine instrumented through piezoelectric dynamometer and incremental optical encoder. Several results could be compared to ones from instrumented CNC lathe and machining center. Tests under HSM condition were carried out in machine-tools. All researched variables have influence over specific cutting energy. The depth of cut rise in 2.3x caused a decrease of specific cutting energy around 21% when machining 2024 aluminum alloy. The elevation of the cutting speed about 70% leaded to reduction of specific cutting energy around 24% when machining SAE 1020 steel. The tool geometry present more influence on specific cutting energy under conventional cutting speed than at high speed cutting. Small variations of tool chip-breaker geometries caused diminution of the specific cutting energy up to 29% for conventional cutting speed, and 14% on average for HSM condition when machining tempered ASTM H13 steel. Various specific cutting energy results obtained from the Charpy test proposed by this work presented a good concordance with equivalent ones provided by scientific literature

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Piškula, David. « Internet of Things ». Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2019. http://www.nusl.cz/ntk/nusl-399196.

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This thesis focuses on the Internet of Things and some of the most important problems it faces today. Among these are the overdependence on the Cloud and lack of autonomy, poor security and privacy, complicated initialization and power consumption. The work aims to implement a complex IoT solution that solves the discussed problems. The project is part of a collaboration with NXP Semicondutors and will be used to showcase the company's technologies.

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Yan, Tao. « Effects of the Edges of 2D Materials on Photoelectrochemical Solar Energy Conversion ». Digital WPI, 2020. https://digitalcommons.wpi.edu/etd-dissertations/597.

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Research on renewable energy must be hastened to solve the energy crisis we are now facing. Among all sustainable energy sources, solar energy and hydrogen gas fuel are two of the most clean and powerful. Photo-electrochemical (PEC) reactions use solar energy to electrochemically split water to produce hydrogen gas. Photoelectrocatalyst materials play an important role in increasing the e ciency of PEC reactions by absorbing solar energy and directing the energy towards the desired electrochemical reactions. Two-dimensional (2D) layered materials including MoS2, WS2, and SnS2 have drawn considerable attention as electrocatalysts and photo-electrocatalysts because of the catalytically-active nature of their edges and high charge mobility and transport e ciency within their layers. This work focuses on the synthesis, measurement, and simulation of PEC properties and behavior of WS2 nanotubes and SnS2 nano akes. The rst part of this work focuses on experimental synthesis and PEC measurement of edge-on oriented WS2 nanotubes and theoretical simulation of the atomic con guration and electronic structure of the edges by density functional theory (DFT) . WS2 nanotubes were synthesized by chemical vapor deposition (CVD) and sulfurization, but showed very poor photresponse. The DFT simulation shows the edges of the WS2 nanotubes are metallic, like those of 2H-MoS2. The metallic edges likely act as recombination sites for photogenerated charges, which explains the poor photoresponse of WS2. The second part of this work focuses on experimental synthesis and PEC measurement of edge-on oriented SnS2 nano akes and theoretical simulation by DFT. The edge-on oriented SnS2 nano akes exhibited high photoresponse and excellent PEC performance. The DFT simulation determined the atomic con gurations of SnS2 edges, and the stability of both bulk-like and monolayer SnS2 edges at various S potentials. In contrast to WS2 and MoS2, the DFT simulation also determined that the edges of SnS2 are semiconducting, not metallic. Therefore, the edges of SnS2 would not cause recombination of photoexcited charges, and would enable SnS2 to achieve a high photoresponse, as was experimentally observed. The DFT results also showed that the band gap energy of the SnS2 edges becomes smaller with increasing sulfur coverage, and allowed the in uence of chemical synthesis conditions on the electronic structure of the edges to be determined.

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Visotzky, Alexander M. « Double-Edged Sword : Russia’s Use of Energy as Leverage in the Near Abroad ». Oberlin College Honors Theses / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1241633377.

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Thèses sur le sujet « Edge energy »

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