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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

How does lightning initiate and what controls lightning frequency? /

Schroeder, Vicki. January 2000 (has links)
Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 104-111).
192

Cloud computing technology framework and reducing risks / Cloud computing technology framework and reducing risks

Akrir, Khaled Ali Ahmed January 2015 (has links)
The thesis investigates, in a qualitative way, the vectors that contribute to cloud computing risks in the areas of security, business, and compliance. The focus of this research is on the identification of risk vectors that affect cloud computing and the creation of a framework that can help IT managers in their cloud adoption process. Economic pressures on businesses are creating a demand for an alternative delivery of the model that can provide flexible payments, dramatic cuts in capital investment, and reductions in operational cost. Cloud computing is positioned to take advantage of these economic pressures with low cost IT services and a flexible payment model, but at what risk to the business? Security concerns about cloud computing are heightened and fueled by misconceptions related to security and compliance risks. Unfortunately, these security concerns are seldom, expressed quantifiably. To bring clarity to cloud computing security, compliance, and business risks, this research focuses on a qualitative analysis of risk vectors drawn from one-on-one interviews with top IT experts selected. The qualitative aspect of this research separates facts from unfounded suspicions, and creates a framework that can help align perceived risks of cloud computing with actual risks. The qualitative research was done through interviews with experts and through the survey to measure risk perceptions about cloud computing using a Likert scale. The decision-making model and the framework created by this research help to rationalize the risk vectors on cloud environments and recommend reducing strategies to bring the IT industry one step closer to a clearer understanding of the risks-tradeoffs implications of cloud computing environments.
193

Dynamic Voltage and Frequency Scaling Enhanced Task Scheduling Technologies Toward Greener Cloud Computing

Aldhahri, Eiman Ali 01 May 2014 (has links)
The skyrocketing amount of electricity consumed by many data centers around the globe has become a serious issue for the cloud computing and entire IT industry. The demand for data centers is rapidly increasing due to widespread usage of cloud services. It also leads to huge carbon emissions contributing to the global greenhouse effect. The US Environmental Protection Agency has declared that data centers represent a substantial portion of the energy consumption in the US and the whole world. Some of this energy consumption is caused by idle servers or servers running at higher-than-necessary frequencies. Due to the Dynamic Voltage and Frequency Scaling (DVFS) technology enabled in many CPUs, strategically reducing CPU frequency without affecting the Quality of Service (QoS) is desired. Our goal in this paper is to calculate and tune to the best CPU frequency for each running task combined with two commonly-used scheduling approaches, namely round robin and first fit algorithms, given the CPU configuration and the execution deadline. The effectiveness of our algorithms is evaluated under a CloudSim/CloudReport simulation environment as well as real hypervisor computer system with power gauge. The open source CloudReport, based on the CloudSim simulator, has been used to integrate our DVFS algorithm with the two scheduling algorithms to illustrate the efficiency of power saving in different scenarios. Furthermore, electricity consumption is measured and compared using power gauge of Watts Up meter.
194

Utilization of Cloud Computing Applications in Commercial Companies

Jindra, Martin January 2012 (has links)
No description available.
195

Data intensive ATLAS workflows in the Cloud

Rzehorz, Gerhard Ferdinand 09 May 2018 (has links)
No description available.
196

Avaliação de desempenho de mecanismos de segurança em ambientes PACS (Picture Archiving and Communication System) baseados em computação em nuvem / Performance evaluation of security mechanisms in PACS environments (Picture Archiving and Communication System) based on cloud computing

Fábio Sousa de Sant\'Ana 07 November 2016 (has links)
Introdução: A adoção de um Sistema de Arquivamento e Distribuição de Imagens (PACS, do inglês Picture Archiving and Communication System) é condição fundamental para a estruturação de um ambiente radiológico sem filme. Um PACS é composto basicamente por equipamentos e sistemas informatizados interconectados em rede, direcionados à aquisição, armazenamento (ou arquivamento), recuperação e apresentação de imagens médicas aos especialistas responsáveis por avaliá-las e laudá-las. A computação em nuvem vem ao encontro dos PACS e surge como uma maneira de simplificar o compartilhamento de imagens entre organizações de saúde e promover a virtualização de espaços físicos e para garantir o seu funcionamento ininterrupto.Objetivo: Este estudo teve como objetivo implementar um PACS simplificado em ambiente cloud computing privado, com foco nas funcionalidades de arquivamento e disponibilização de imagens médicas e avaliar questões de segurança e performance. Metodologia: As imagens que compuseram o PACS do ambiente cloud foram obtidas através do PACS físico atualmente em uso no Centro de Ciência das Imagens e Física Médica do Hospital das Clinicas da Faculdade de Medicina de Ribeirão Preto - CCIFM/HCFMRP. Para os procedimentos da avaliação de segurança foram construídos cenários que possibilitavam a: 1) anominização de dados de identificação dos pacientes através de criptografia computacional em base de dados utilizando o algoritmo de criptografia Advanced Encryption Standard - AES, 2) transferência de imagens médicas seguras através de conexão com a Internet utilizando Virtual Network Private - VPN sobre o protocolo Internet Protocol Security - IPSec (VPN/IPSec) e 3) envio seguro através de tunelamento baseado em Secure Shell - SSH. Resultados: Foi identificada uma queda de performance no envio de informações para a nuvem quando submetidos aos níveis de segurança propostos, sugerindo a relação entre aumento de segurança e perda de performance, apontando para a necessidade de estudos de desempenho quando da condução de projetos envolvam a adoção em ambientes clínicos de solução PACS baseada em cloud computing. / Introduction: the adoption of a PCAS (Picture Archiving and Communication System) is fundamental for the structuring of a radiological environment without film. A PACS comprises, essentially, hardware and information systems interconnected in a network, oriented towards acquisition, storage (or archiving), retrieving and presentation of medical images to specialists entrusted with analyzing and assessing them. Cloud computing comes to support of PCAS, simplifying medical imaging sharing between health care organizations and promoting the virtualization of physical infrastructure to assure uninterrupted availability of the PCAS. Goal: This study aimed to implement a simplified PCAS in a private cloud computing environment, and subsequently to evaluate its security and performance. Methodology: The images that formed the new PCAS were obtained from the exiting PCAS of Centro de Ciência das Imagens e Física Médica of Hospital das Clinicas da Faculdade de Medicina de Ribeirão Preto - CCIFM/HCFMRP. To evaluate its security, scenarios were built within the following framework: 1) patient identification data anonymization through computational database cryptography, using the AES (Advanced Encription Standards) algorithm ; 2) transfer of encrypted medical images on the Internet using VPN (Virtual Private Network) over IPSec (Internet Protocol Security); and 3) safe traffic through Secure Shell (SSH) tunneling. Results: There was a performance drop on traffic of information to the cloud under the proposed security levels that suggests a relationship between increase in security and loss of performance, pointing to the need for performance studies when the project involving driving adoption in clinical environments PACS solution based on cloud computing.
197

Vad finns det för fördelar och nackdelar medmolnet? : Hur upplever IT-företag dessa?

Andersson, Johan, Pettersson, Johan January 2014 (has links)
Att inom företag och organisationer använda sig av molntjänster är den senaste heta trenden inom IT-världen. Men vad finns det egentligen för fördelar och nackdelar med att använda sig av molntjänster? I denna uppsats beskriver vi först fenomenet molnetoch molnjänster, även känt som cloud computing. Efter det har vi gjort en litteraturstudie för att ta reda på vad det finns för för och nackdelar med användandetav molntjänster. Vi har till slut utfört en kvalitativ enkätundersökning för att ta reda påvad IT-företag som använder sig av molntjänster upplever för för och nackdelar meddem. Den genomförda litteraturstudien resulterade i ett visst antal för och nackdeler.Dessa för och nackdelar har vi delat in i åtta stycken kategorier med övergripande teman. Vi har därefter utformat enkätfrågorna utifrån dessa kategorier.
198

Cloud Computing : Lärplattform i molnet

Andersson, Mattias, Ludvigsson, Christopher January 2011 (has links)
Cloud computings framväxt har möjliggjort tillhandhållande av datorresurser online och erbjuder två väsentliga egenskaper, dels upplevda oändliga resurser och dels betalning per resursförbrukning. Lärplattformar används idag i stor utsträckning av de svenska universiteten och högskolorna som studieverktyg. Detta medför bättre möjligheter för distanskurser och e-inlärning. Att kombinera cloud computing med en lärplattform är idag möjligt och bör därför ge skolorna fördelar. Om lärplattformen driftas som molntjänst av extern leverantör bör också kraven se annorlunda ut. Syftet med uppsatsen är att utreda om det finns några incitament för att hyra en lärplattform som molntjänst och även att utreda om kraven ser annorlunda ut på en hyrd molntjänst. En fallstudie genomfördes på Uppsala universitet och Högskolan Dalarna, detta för att jämföra en lärplattform installerad på egen server med en lärplattform som hyrd molntjänst. Resultatet av studien bevisar att det finns fördelar med att hyra en lärplattform som molntjänst. Vad gäller kraven är det inte mycket som skiljer, ett viktigt krav när driften ligger hos en leverantör är att det finns en bra dialog och att organisationen litar på leverantören. / The growth of cloud computing has enabled the provision of computer resources online and offers two essential characteristics, illusion of infinite supply and pay-per-use. Learning management systems are currently used extensively by the Swedish universities as learning tools. This brings better opportunities for distance courses and e-learning. To combine cloud computing with a learning management system is now possible and should therefore give the schools benefits. If the Learning management system is hosted as a cloud service by an external provider, so should the requirements be different. The purpose of this paper is to investigate whether there are any incentives for rent a learning management system as a cloud service and also investigate if the requirements are different in a rented cloud service. A case study was conducted at Uppsala University and Dalarnas University, in order to compare a learning management system installed on their own server with a learning management system rented as a cloud service.  The result of the study proves that there are advantages to rent a learning management system as a cloud services. In terms to the requirements, there are no great differences. An important requirement when the learning management system is hosted by a supplier is that there is a good dialogue and that the organization relies on the supplier.
199

The validation of two box models predicting dense gas dispersion with experimental data

Sherrell, S. J. January 1988 (has links)
No description available.
200

The Cloud Marketplace : A Capability-Based Framework for Cloud Ecosystem Governance

Falk, Sebastian, Shyshka, Andriy January 2014 (has links)
Within the last five years, the market of cloud computing has shown rapid growth. However, despite the increasing popularity, researchers highlight numerous concerns regarding limited interoperability of systems hosted by different cloud providers as well as restricted customization of cloud solutions. In order to counter aforemen-tioned challenges, this study investigates the idea of introducing a marketplace for cloud services that leverage the service-oriented architecture (SOA) paradigm and of-fers software solutions, computing capabilities from cloud providers, components developed by third parties, as well as access to integration and audit services. The goal of the study lies in conceptualizing the idea and the evaluation of demand it may raise from the key cloud actors. In this regard, existing frameworks of cloud compu-ting and SOA contributed to the development of an initial model that was further improved through the interviewing process. The results of this study include a capa-bility-based framework for the cloud marketplace which not only clarifies the role and activities of the different actors but also contains the necessary features of the marketplace that are needed to ensure the proper workflow. In addition to that, the actors’ incentives and concerns regarding the marketplace were analyzed by applying SWOT-analysis. While the analysis revealed both positive interest and present de-mand among the actors, the identified weaknesses and threats highlight the need for further investigations in order to put the idea into practice.

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