In recent years, the demand for data center computing has increased significantly due to the growing popularity of cloud applications and Internet-based services. Today's large data centers host hundreds of thousands of servers and the peak power rating of a single data center may even exceed 100MW. The combined electricity consumption of global data centers accounts for about 3% of worldwide production, raising serious concerns about their carbon footprint. The utility providers and governments are consistently pressuring data center operators to reduce their carbon footprint and energy consumption. While these operators (e.g., Apple, Facebook, and Google) have taken steps to reduce their carbon footprints (e.g., by installing on-site/off-site renewable energy facility), they are aggressively looking for new approaches that do not require expensive hardware installation or modification. This dissertation focuses on developing algorithms and systems to improve the sustainability in data centers without incurring significant additional operational or setup costs. In the first part, we propose a provably-efficient resource management solution for a self-managed data center to cap and reduce the carbon emission while maintaining satisfactory service performance. Our solution reduces the carbon emission of a self-managed data center to net-zero level and achieves carbon neutrality. In the second part, we consider minimizing the carbon emission in a hybrid data center infrastructure that includes geographically distributed self-managed and colocation data centers. This segment identifies and addresses the challenges of resource management in a hybrid data center infrastructure and proposes an efficient distributed solution to optimize the workload and resource allocation jointly in both self-managed and colocation data centers. In the final part, we explore sustainable resource management from cloud service users' point of view. A cloud service user purchases computing resources (e.g., virtual machines) from the service provider and does not have direct control over the carbon emission of the service provider's data center. Our proposed solution encourages a user to take part in sustainable (both economical and environmental) computing by limiting its spending on cloud resource purchase while satisfying its application performance requirements.

We address the problem of migration of local storage of desktop users to remote sites. Assuming a network connection is maintained between the source and destination after the migration makes it possible for us to transfer a fraction of storage state while trying to operate as close to disconnected mode as possible. We have designed an approach to determine the subset of storage state that is to be transferred based on past accesses. We show that it is feasible to use information about files accessed to determine clusters and hot-spots in the file system. Using the tree structure of the file system and by applying an appropriate similarity measure to user accesses, we can approximate the working sets of the data accessed by the applications running at the time. Our results indicate that our technique reduces the amount of data to be copied by two orders of magnitude, bringing it into the realm of the possible.

Global economic trends suggest that there is a need to generate sustainable renewable energy to meet growing global energy demands. Solar energy harnessed by concentrated photovoltaic (CPV) systems has a potential for strong contributions to future energy supplies. However, as a relatively new technology, there is still a need for considerable research into the relationship between the technology and the solar resource. Research into CPV systems was carried out at the University of Ottawa’s Solar Cells and Nanostructured Device Laboratory (SUNLAB), focusing on the acquisition and assessment of meteorological and local solar resource datasets as inputs to more complex system (cell) models for energy yield assessment. An algorithm aimed at estimating the spectral profile of direct normal irradiance (DNI) was created. The algorithm was designed to use easily sourced low resolution meteorological datasets, temporal band pass filter measurement and an atmospheric radiative transfer model to determine a location specific solar spectrum. Its core design involved the use of an optical depth parameterization algorithm based on a published objective regression algorithm. Initial results showed a spectral agreement that corresponds to 0.56% photo-current difference in a modeled CPV cell when compared to measured spectrum. The common procedures and datasets used for long term CPV energy yield assessment was investigated. The aim was to quantitatively de-convolute various factors, especially meteorological factors responsible for error bias in CPV energy yield evaluation. Over the time period from June 2011 to August 2012, the analysis found that neglecting spectral variations resulted in a ~2% overestimation of energy yields. It was shown that clouds have the dominant impact on CPV energy yields, at the 60% level.

Cloud computing is a relatively new form of computing which uses virtualized resources. It is dynamically scalable and is often provided as pay for use service over the Internet or Intranet or both. With increasing demand for data storage in the cloud, the study of data-intensive applications is becoming a primary focus. Data intensive applications are those which involve high CPU usage, processing large volumes of data typically in size of hundreds of gigabytes, terabytes or petabytes. The research in this thesis is focused on the Amazon’s Elastic Cloud Compute (EC2) and Amazon Elastic Map Reduce (EMR) using HiBench Hadoop Benchmark suite. HiBench is a Hadoop benchmark suite and is used for performing and evaluating Hadoop based data intensive computation on both these cloud platforms. Both quantitative and qualitative comparisons of Amazon EC2 and Amazon EMR are presented. Also presented are their pricing models and suggestions for future research.

In response to the drastic decline of the European eel (Anguilla anguilla (L.)) fisheries have been reduced and elvers are stocked in areas where natural abundances are low. Are these measures adequate? To answer different aspects of this question, we have analysed more than a century of eel tagging, using both traditional and more novel capture – recapture analyses. Based on these long-term data, we have evaluated the impact of the Swedish eel coastal fisheries using Survival analysis. Our analysis indicates that the fishing mortality just prior the 2009 fishing restrictions were in the order of 10%. More recent tagging programs have focused on issues related to the fate of stocked fish. If and how they migrate out of the Baltic Sea and further on towards the Atlantic Ocean. Both earlier and our new studies reveal that all eels recaptured on the Swedish East Coast, no matter of their origin, migrate at a reasonable speed and direction towards the outlets of the Baltic Sea. Even though it is sometimes difficult to determine their origin, our analyses indicate that stocked fish were scarce among the recaptures. In an experiment on the Swedish West Coast, we knew the individuals’ origin (stocked or wild) and they had similar migration patterns. In contrast, silver eel in Lake Mälaren – assumed to have been stocked as elvers or bootlace eels – seemed to have difficulties in finding the outlets. Instead they overwintered and lost weight. However, weight losses are also significant among non-stocked individuals in the Baltic Sea, both if they overwinter and if they appear to be on their way out from the area. It remains an open question whether eels from the Baltic region in general, and whether the overwintered fish in particular, manage to reach the spawning area in the Atlantic Ocean. Based on current knowledge, I advocate invoking the precautionary approach and to concentrate Swedish eel stockings to the West Coast and allow the young fish to spread out on their own. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.</p><p> </p>

Grades computacionais oportunistas utilizam recursos ociosos de máquinas compartilhadas para executar aplicações que necessitam de um alto poder computacional e/ou trabalham com grandes quantidades de dados. Mas a execução de aplicações paralelas computacionalmente intensivas em ambientes dinâmicos e heterogêneos, como grades computacionais oportunistas, é uma tarefa difícil. Máquinas podem falhar, ficar inacessíveis ou passar de ociosas para ocupadas inesperadamente, comprometendo a execução de aplicações. Um mecanismo de tolerância a falhas que dê suporte a arquiteturas heterogêneas é um importante requisito para estes sistemas. Neste trabalho, analisamos, implementamos e avaliamos um mecanismo de tolerância a falhas baseado em checkpointing para aplicações paralelas em grades computacionais oportunistas. Este mecanismo permite o monitoramento de execuções e a migração de aplicações entre nós heterogêneos da grade. Mas além da execução, é preciso gerenciar e armazenar os dados gerados e utilizados por estas aplicações. Desejamos uma infra-estrutura de armazenamento de dados de baixo custo e que utilize o espaço livre em disco de máquinas compartilhadas da grade. Devemos utilizar somente os ciclos ociosos destas máquinas para armazenar e recuperar dados, de modo que um sistema de armazenamento distribuído que as utilize deve ser redundante e tolerante a falhas. Para resolver o problema do armazenamento de dados em grades oportunistas, projetamos, implementamos e avaliamos o middleware OppStore. Este middleware provê armazenamento distribuído e confiável de dados, que podem ser acessados de qualquer máquina da grade. As máquinas são organizadas em aglomerados, que são conectados por uma rede peer-to-peer auto-organizável e tolerante a falhas. Dados são codificados em fragmentos redundantes antes de serem armazenados, de modo que arquivos podem ser reconstruídos utilizando apenas um subconjunto destes fragmentos. Finalmente, para lidar com a heterogeneidade dos recursos, desenvolvemos uma extensão ao protocolo de roteamento em redes peer-to-peer Pastry. Esta extensão adiciona balanceamento de carga e suporte à heterogeneidade de máquinas ao protocolo Pastry. / Opportunistic computational grids use idle resources from shared machines to execute applications that need large amounts of computational power and/or deal with large amounts of data. But executing computationally intensive parallel applications in dynamic and heterogeneous environments, such as opportunistic grids, is a daunting task. Machines may fail, become inaccessible, or change from idle to occupied unexpectedly, compromising the application execution. A fault tolerance mechanism that supports heterogeneous architectures is an important requisite for such systems. In this work, we analyze, implement and evaluate a checkpointing-based fault tolerance mechanism for parallel applications running on opportunistic grids. The mechanism monitors application execution and allows the migration of applications between heterogeneous nodes of the grid. But besides application execution, it is necessary to manage data generated and used by those applications. We want a low cost data storage infrastructure that utilizes the unused disk space of grid shared machines. The system should use the machines to store and recover data only during their idle periods, requiring the system to be redundant and fault-tolerant. To solve the data storage problem in opportunistic grids, we designed, implemented and evaluated the OppStore middleware. This middleware provides reliable distributed storage for application data, which can be accessed from any machine in the grid. The machines are organized in clusters, connected by a self-organizing and fault-tolerant peer-to-peer network. During storage, data is codified into redundant fragments, allowing the reconstruction of the original file using only a subset of those fragments. Finally, to deal with resource heterogeneity, we developed an extension to the Pastry peer-to-peer routing substrate, enabling heterogeneity-aware load-balancing message routing.

"eLibrary" is a book management software application that runs on Microsoft Windows platforms. The software incorporates a Windows Explorer like interface and XML/XSL to display book details. The purpose of this project is to build a full-featured, commerical-quality software package to help people manage their books (either printed or electronic). The goal is for eLibrary to be a complete solution for people who wish to build their own personal electronic library catalog.

Entertainics is a web-based software application used to gather information about DVD players from several web-sites on the internet. The purpose of this software is to help users search for DVD players in a faster and easier way, by avoiding the navigation on every web-site that contains this product.

Easy Fitness, es un proyecto que presentamos como idea de negocio, que consiste en brindar servicios de entrenamiendo físico de manera virtual. Buscamos satisfacer el deseo de las personas que quieren realizar actividad física para sentirse saludables, que cuentan con tiempo limitado para ir a un gimnasio convencional, pues somos la alternativa para realizar ejercicios desde la comodidad del hogar, oficina, parque o cualquier lugar donde las personas se sientas más cómodas. Proponemos utilizar tecnología y elaborar una plataforma digital que ayude a las personas que buscan ejercitarse a realizar ejercicios guiados por videos instructivos o por entrenadores en vivo. Para confirmar la viabilidad de nuestro proyecto se realizó una investigación, para identificar si existía un mercado con el problema que planteamos “realizar ejercicios sin necesidad de ir a un gimnasio convencional” y que acepten nuestra propuesta como una solución. Esta investigación se realizó a través de entrevistas personalizadas y elaboración de un producto mínimo viable, en base a dichos resultados concretamos la viabilidad del proyecto. Asimismo, elaboramos un plan de marketing que nos permitió identificar el mercado operativo y proyectar las ventas de los cinco primeros años. Para dar soporte al servicio exhibimos un plan de operaciones, un plan organizacional, un plan gestión humana y un plan económico financiero que confirma la viabilidad y rentabilidad del negocio. / Easy Fitness is a project that we present as a business idea, which consists of providing physical training services in a virtual way. We seek to satisfy the desire of people who want to do physical activity to feel healthy but have limited time to go to a conventional gym. We are the alternative to exercise from the comfort of home, office, park or any place where people can feel more comfortable. We propose to use technology and develop a digital platform that helps people seeking to exercise to perform exercises guided by instructional videos or live trainers. In order to confirm the viability of our project, an investigation was carried out to identify if there is a market with the problem we have identified which is "to perform exercises without going to a conventional gym" and that it accepts our proposal as a solution. This research was carried out through personalized interviews and the elaboration of a minimum viable product. Based on these results we specified the viability of the project. We also developed a marketing plan that allowed us to identify the operating market and project sales for the first five years. To support the service, we exhibit an operations plan, an organizational plan, a human management plan and a financial economic plan that confirms the viability and profitability of the business. / Trabajo de investigación

Dank der hohen uniaxialen Kristallanisotropie der L10-geordneten Phase gelten nanopartikuläre FePt+C-Schichten als aussichtsreiche Kandidaten zukünftiger Datenspeichersysteme. Aus diesem Grund werden in der vorliegenden Arbeit in Kooperation mit HGST- A Western Digital Company Prototypen solcher Medien strukturell bis hin zu atomarer Auflösung charakterisiert. Anhand von lokalen Messungen der Gitterparameter der FePt-Partikel wird gezeigt, dass die Partikel dünne, zementitartige Verbindungen an ihrer Oberfläche aufweisen. Zusätzlich werden große Partikel mit kleinem Oberfläche-Volumen-Verhältnis von kontinuierlichen Kohlenstoffschichten umschlossen, was die Deposition weiteren Materials verhindert. Eine Folge davon ist die Entstehung einer zweiten Lage statistisch orientierter Partikel, die sich negativ auf das magnetische Verhalten der FePt-Schicht auswirkt. Weiterhin wird die besondere Bedeutung des eingesetzten Substrats sowie seiner Gitterfehlpassung zur L10-geordneten Einheitszelle nachgewiesen. So lässt sich das Auftreten fehlorientierter ebenso wie das L12-geordneter Kristallite im Fall großer Fehlpassung und einkristalliner Substrate unterdrücken, was andererseits jedoch zu einer stärkeren Verkippung der [001]-Achsen der individuellen FePt-Partikel führt. Abschließend wird mithilfe der Elektronenholographie nachgewiesen, dass die Magnetisierungsrichtungen der FePt-Partikel aufgrund von Anisotropieschwankungen von den [001]-Achsen abweichen können.:1 Einleitung 2 Grundlagen 2.1 Magnetische Datenspeicherung 2.1.1 Longitudinale magnetische Datenspeicherung (LMR) 2.1.2 Perpendikuläre Medien (PMR) 2.1.3 Thermisch-unterstützte Schreibprozesse (HAMR) 2.2 Das binäre Legierungssystem Eisen-Platin 2.2.1 Die L10-Ordnungsphase 2.2.2 Partikuläre FePt-Schichten 2.3 Strukturelle Besonderheiten nanoskopischer Systeme 2.3.1 Vorzugsorientierungen in polykristallinen Materialien 2.3.2 Einfluss der Substratoberfläche 2.4 Magnetische Eigenschaften 2.4.1 Magnetokristalline Anisotropie 2.4.2 Das Stoner-Wohlfarth-Modell der Eindomänenteilchen 2.4.3 Besonderheiten nanoskopischer FePt-Magnete 2.5 Prinzipien der hochauflösenden Transmissionselektronenmikroskopie 2.5.1 Bild- und Kontrastentstehung 2.5.2 Angewandte Bildgebungsverfahren 2.5.3 Elektronenholographie 3 Experimentelles 3.1 Probenherstellung mittels Kathodenzerstäubung 3.2 Präparation von TEM-Lamellen und VSM-Proben 3.3 Strukturelle Charakterisierung 3.3.1 Klassische und hochaufgelöste Transmissionselektronenmikroskopie 3.3.2 Elektronenenergieverlustspektroskopie (EELS) 3.3.3 Röntgendiffraktometrie (XRD) 3.3.4 Rasterkraftmikroskopie (AFM) 3.4 Vermessung der magnetischen Eigenschaften 3.4.1 Korrektur der Hysteresemessungen 3.4.2 Untersuchung des Wechselwirkungsverhaltens 3.4.3 Bestimmung der Anisotropiefelder 3.4.4 Ermittlung der magnetischen Phasenschiebung mittels Holographie 4 Legierungsbildung und Segregationsphänomene 4.1 Charakterisierung der Platinverteilung 4.2 Untersuchung der Kohlenstoffsegregation 4.3 Einfluss von Kupfer-Additiven 5 Untersuchung des Substrateinflusses 5.1 Einfluss der Gitterfehlpassung zu einkristallinen Substraten 5.2 Vergleich einkristalliner und polykristalliner Substrate 5.3 Einfluss von Substratkorngrenzen 5.4 Auswirkungen der Substratrauheit 6 Magnetische Charakterisierung einzelner FePt Inseln mittels Elektronenholographie 6.1 Experimentelle Bestimmung der magnetischen Phasenschiebung 6.2 Simulation der Phasenkontraste 7 Zusammenfassung / Highly textured L10-ordered FePt+C-films are foreseen to become the next generation of magnetic data storage media. Therefore prototypes of such media (provided by HGST- A Western Digital Company) are structurally investigated down to the atomic level by HR-TEM and the observed results are correlated to the magnetic performance of the film. In a first study the occurrence of a strongly disturbed surface layer with a lattice spacing that corresponds to cementite is observed. Furthermore the individual particles are surrounded by a thin carbon layer that suppresses the deposition of further material and leads, therefore, to the formation of a second layer of particles. Without a contact to the seed layer these particles are randomly oriented and degrade the magnetic performance of the media. A further study reveals, that a selection of single-crystalline substrates with appropriate lattice mismatch to the L10-ordered unit cell can be applied to avoid the formation of in-plane oriented and L12-ordered crystals. Unfortunately, the required large mismatch results in a broadening of the texture of the [001]-axes of the individual grains. As electron holography studies reveal, the orientation of the magnetization of the individual grains can differ from the structural [001]-axis due to local fluctuations of the uniaxial anisotropy.:1 Einleitung 2 Grundlagen 2.1 Magnetische Datenspeicherung 2.1.1 Longitudinale magnetische Datenspeicherung (LMR) 2.1.2 Perpendikuläre Medien (PMR) 2.1.3 Thermisch-unterstützte Schreibprozesse (HAMR) 2.2 Das binäre Legierungssystem Eisen-Platin 2.2.1 Die L10-Ordnungsphase 2.2.2 Partikuläre FePt-Schichten 2.3 Strukturelle Besonderheiten nanoskopischer Systeme 2.3.1 Vorzugsorientierungen in polykristallinen Materialien 2.3.2 Einfluss der Substratoberfläche 2.4 Magnetische Eigenschaften 2.4.1 Magnetokristalline Anisotropie 2.4.2 Das Stoner-Wohlfarth-Modell der Eindomänenteilchen 2.4.3 Besonderheiten nanoskopischer FePt-Magnete 2.5 Prinzipien der hochauflösenden Transmissionselektronenmikroskopie 2.5.1 Bild- und Kontrastentstehung 2.5.2 Angewandte Bildgebungsverfahren 2.5.3 Elektronenholographie 3 Experimentelles 3.1 Probenherstellung mittels Kathodenzerstäubung 3.2 Präparation von TEM-Lamellen und VSM-Proben 3.3 Strukturelle Charakterisierung 3.3.1 Klassische und hochaufgelöste Transmissionselektronenmikroskopie 3.3.2 Elektronenenergieverlustspektroskopie (EELS) 3.3.3 Röntgendiffraktometrie (XRD) 3.3.4 Rasterkraftmikroskopie (AFM) 3.4 Vermessung der magnetischen Eigenschaften 3.4.1 Korrektur der Hysteresemessungen 3.4.2 Untersuchung des Wechselwirkungsverhaltens 3.4.3 Bestimmung der Anisotropiefelder 3.4.4 Ermittlung der magnetischen Phasenschiebung mittels Holographie 4 Legierungsbildung und Segregationsphänomene 4.1 Charakterisierung der Platinverteilung 4.2 Untersuchung der Kohlenstoffsegregation 4.3 Einfluss von Kupfer-Additiven 5 Untersuchung des Substrateinflusses 5.1 Einfluss der Gitterfehlpassung zu einkristallinen Substraten 5.2 Vergleich einkristalliner und polykristalliner Substrate 5.3 Einfluss von Substratkorngrenzen 5.4 Auswirkungen der Substratrauheit 6 Magnetische Charakterisierung einzelner FePt Inseln mittels Elektronenholographie 6.1 Experimentelle Bestimmung der magnetischen Phasenschiebung 6.2 Simulation der Phasenkontraste 7 Zusammenfassung