No description available.

In order to fulfil the goals set by EU and in the Swedish energy agreement an increased share of renewable electricity production, like wind and solar power, is necessary. Due to current legislations photovoltaic (PV) installations are usually limited to the 255 kWp energy taxation rule, or to fit the consumption profile of the building. There is also an uncertainty regarding subsidies from a long-term perspective. Three main questions are examined in this report: Firstly, whether or not a larger PV installation is more beneficial compared to a smaller one regarding LCOE, payback time and IRR. Secondly, if and how a larger PV installation can be optimized using virtual storage. Thirdly, how the virtual storage solution compares to a conventional storage method with a lithium-ion battery. Throughout the project, larger installations have proven more profitable by taking advantage of cost efficiencies. By increasing the size of the installation from 120 kWp to 314 kWp for the investigated pilot project, the LCOE is reduced from 0,938 to 0,767 SEK/kWh, payback time is reduced from 17 to 12 years, and IRR is increased from 8,1 to 10,8 %. To maintain the advantage of the largest installation in the current market, it is necessary to integrate and optimize the storage so that all produced electricity is self-consumed. Some buildings have the possibility to create a virtual storage through using existing possibilities within the facility. Virtual storage is still an unexplored area but has risen in interest since focus on energy efficiency has increased. The project includes a virtual storage solution where the refrigeration system in a grocery store is paired with a water tank to provide more storage capacity. To optimize the use of the virtual storage, it is necessary to maximize the use of the available capacity. Three main applications have been identified as optimization alternatives for the project and those are: 1) storing excess electrical energy from over-production, 2) load shifting from hours with high electricity prices, 3) providing demand response for the primary regulation market (FCR-N, FCR-D). By utilizing the storage capacity, the PV investment can improve with regards to the studied economic measures. When utilizing the most profitable options, 1) and 3), for a 314 kWp PV installation the payback time is reduced from 12 to 10 years and the IRR is increased from 10,8 % to 11,73 %. Compared with a conventional lithium-ion battery (Tesla Powerwall), the virtual storage solution is competitive with respect to initial cost and environmental impact. However, for electrical aspects the battery significantly outperforms the virtual storage with an efficiency of 90 % of the battery and 54 % of the virtual storage and an energy density of 0,108 kWh/kg for the battery and 0,0035 kWh/kg for the virtual storage.

No description available.

Thesis (M.S.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (leaves 69-71).

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (p. [137]-143).

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (p. [111]-120).

Thesis (Ph.D. (Computer Science)) - Rhodes University, 2009.

Thesis (MIng.)--Stellenbosch University, 1990. / ENGLISH ABSTRACT: The transputer virtual memory system provide, for the transputer without memory management primitives, a viable virtual memory system. This report evaluates the architecture and its parameters. The basic software is also implemented a.nd described. The disk subsystem with software and hard",,'are is also evaluated in a single disk environment. It is shown that the unique features of the TVM system has advantages and disadvantages when compared to conventional virtual memory systems. One of the advantages is that a conventional operating system with memory protection can now also be implemented on the transputer. The main conclusion is that this is a performance effective implementation of a virtual memory system with unique features that should be exploited further. / AFRIKAANSE OPSOMMING: Die transputer virtuele geheue verskaf, vir 'n verwerker sander virtuele geheue ondersteuning, 'n doeltreffende virtuele geheue stelsel. Die verslag evalueer die argitektuur en sy parameters. Die skyfsubstelsel met programmatuur en apparatuur word ook geevalueer in 'n enkel skyfkoppelvlak omgewing. Daar word bewys dat die upieke eienskappe van die TVG (transputer virtuele geheue) voor- en nadele besit wanneer dit vElrgelyk word met konvensionele virtuele geheue stelsels. Een van die voordele is dat 'n konvensionele bedryfstelsel met geheue beskerming nou op 'n transputer ge-implementeer kan word. Die hoofnadeel agv die spesifieke argitektuur gee slegs 'n 15% degradering in werkverrigting. Dit word egter slegs oar 'n sekere datagrootte ervaar en kom tipies nie ter sprake wanneer daar massiewe programme geloop word nie.

Recent years have seen a revival of interest in virtualisation research. Although this term has been used to refer to various systems, the focus of this research is on systems which partition a single physical server into multiple virtual servers. It is difficult for researchers and practitioners to get a clear picture of the state of the art in server virtualisation. This is due in part to the large number of systems available. Another reason is that information about virtualisation systems lacks structure, and is dispersed among multiple sources. Practitioners, such as data centre managers and systems administrators, may be familiar with virtualisation systems from a specific vendor, but generally lack a broader view of the field. This makes it difficult to make informed decisions when selecting these systems. Researchers and vendors who are developing virtualisation systems also lack a standard framework for identifying the strengths and weaknesses of their systems, compared to competing systems. It is also time-consuming for researchers who are new to the field to learn about current virtualisation systems. The purpose of this research was to develop a framework to solve these problems. The objectives of the research correspond to the applications of the framework. These include conducting comparative evaluations of server virtualisation systems, identifying strengths and weaknesses of particular virtualisation systems, specifying virtualisation system requirements to facilitate system selection, and gathering information about current virtualisation systems in a structured form. These four objectives were satisfied. The design of this framework was also guided by six framework design principles. These principles, or secondary objectives, were also met. The framework was developed based on an extensive literature study of data centres, virtualisation and current virtualisation systems. Criteria were selected through an inductive process. The feasibility of conducting evaluations using the framework was demonstrated by means of literature-based evaluations, and a practical case study. The use of the framework to facilitate virtualisation system selection was also demonstrated by means of a case study featuring the NMMU Telkom CoE data centre. This framework has a number of practical applications, ranging from the facilitation of decision-making to identifying areas for improvement in current virtualisation systems. The information resulting from evaluations using the framework is also a valuable resource for researchers who are new to the field. The literature study which forms the theoretical foundation of this work is particularly useful in this regard. A future extension to this work would be to develop a decision support system based on the framework. Another possibility is to make the framework, and evaluations, available on-line as a resource for data center managers, vendors and researchers. This would also enable other researchers to provide additional feedback, enabling the framework to be further refined

The Kendall Square Research Machine 1 (KSR1) is a virtual shared memory (VSM) machine. Memory on the KSR1 consists primarily of shared, physically distributed caches. Effective memory utilization of the KSR1 is studied within this thesis. Special emphasis is laid upon how best to optimize iterative Krylov subspace methods using domain decomposition preconditioning. The domain decomposition preconditioner used was developed by J. H. Bramble, J. E. Pasciak, and A. H. Schatz. The Krylov subspace method used was the conjugate gradient algorithm. The linear systems being solved are derived from finite difference discretization of elliptic boundary value problems. Most of the focus of this thesis is upon how data structures affect performance of the algorithm on the KSR1. Implications for other iterative methods and preconditioners are also drawn. / Master of Science