A comparative analysis on the total cost of ownership between thin-clients and fat-clients in an outsourced desktop environment.

Thesis (MBA)-University of KwaZulu-Natal, 2006.More than ever, business leaders are focused on growing revenues, containing costs and providing a higher level of customer support, whilst reducing the cost of business support activities, such as information technology costs. One method of achieving these apparently contradictory goals is through the use of thin-client computing. There has certainly been a contradicting view held by many industry pundits such as Gartner and International Data Corporation on whether this is indeed the case. This dissertation is a case study that focuses on what thin-client technology's impact is on the Total Cost of Ownership in the desktop computing environment relative to the traditional use of laptops and PCs, now commonly referred to as fat-clients. The factors and elements that contribute to a Total Cost of Ownership (TCO) for desktop computing will be explored. This study endeavors to douse the contradictory philosophies that claim for and against a lower Total Cost of Ownership (TCO) in deploying thin-clients. The literature review presented outlines the contradictions in philosophies. Research will be undertaken on National Ship Chandlers, which is in the largest ship chandler in Africa. National Ship Chandlers was migrated from a fat-client to a thin-client environment in 2002. National Ship Chandlers management seeks to understand whether they have realised a lower Total Cost of Ownership as a result of the migration. In this context, this study seeks to clarify which of the computing environments, thin-clients or fat-clients yield a lower Total Cost of Ownership within an outsourced desktop environment. In so doing it may assist in bringing clarity to the ongoing feud on the contradicting philosophies and technology claims. There has been no significant academic research undertaken on the Total Cost of Ownership of thin-clients in relation to fat-clients in an outsourced desktop environment. Both qualitative and quantitative research techniques are employed. The conclusions from this will be evaluated and presented. Based on these findings recommendations will be made to National Ship Chandlers management on a strategic direction for their desktop computing environment. This study reveals that for an outsourced desktop computing environment using thin-clients, National Ship Chandlers could realise an approximate 23% saving over a fat-client implementation. This excludes the benefits that can be realised from aspects of information security, ease of the operational platform and greater system availability. Thin-client technology has provides CEOs and CIOs compelling reasons to deploy as a desktop computing architecture and will continue to grow its' market-share into the future

Multistage compression and transient flow in CO₂ pipelines with line packing

The main purpose of this thesis is to develop rigorous analytical and CFD models followed by their applications to real case studies in order to: i) identify the optimum multistage compression strategies for minimising the compression and intercooler power requirements for real CO2 feed streams containing various types and amounts of impurities associated with the various types of CO2 capture technologies; and ii) investigate the buffering efficacy of realistic CO2 transmission pipelines as a line packing strategy for smoothing out temporal fluctuations in feed loading and maintaining the desired dense-phase flow for both pure CO2 and its various realistic mixtures representative of the most common types of capture technologies. An analytical model based on thermodynamics principles is developed employing Plato Silverfrost FTN95 software and applied to determine the power requirements for various compression strategies and inter-stage cooling duties for typical pre-combustion (98.07 % v/v of CO2) and oxy-fuel CO2 mixtures of 85 and 96.7 % v/v CO2 purity compressed from a gaseous state at 15 bar and 38 oC to the dense-phase fluid at 151 bar. Compression options examined include conventional multistage integrally geared centrifugal compressors, advanced supersonic shockwave compressors and multistage compression combined with subcritical and supercritical liquefaction and pumping. In each case, the compression power requirement is calculated numerically using a 15-point Gauss-Kronrod quadrature rule in QUADPACK library, and employing the Peng-Robinson Equation of State (PR EOS) implemented in REFPROP v.9.1 to predict the pertinent thermodynamic properties of the CO2 and its mixtures. In the case of determining the power demand for inter-stage cooling and liquefaction, a thermodynamic model based on Carnot refrigeration cycle is applied. The study shows that a decrease in the impurity content from 15 to 1.9 % v/v in the CO2 streams reduces the total compression power requirement by ca. 1.5 % to as much as 30 %, while for all cases, inter-stage cooling duty is predicted to be significantly higher than the compression power demand. It is found that multistage compression combined with subcritical liquefaction using utility streams and subsequent pumping can offer a higher efficiency than conventional integrally geared centrifugal compression for high purity (> 96.7 % v/v) CO2 streams. In the case of a raw/dehumidified oxy-fuel mixture, that carries a relatively large amount of impurities (85 % v/v CO2), subcritical liquefaction at 62.53 bar is shown to increase the cooling duty by as much 50 % as compared to that for pure CO2. The second part of this study focuses on the development and testing of a numerical CFD model employing Plato Silverfrost FTN95 software for simulating the transient fluid flow behaviour in CO2 pipelines with line packing. The model is based on the numerical solution of the conservation equations using the Method of Characteristics, incorporating PR EOS to deal with CO2 and its various mixtures. Following its verification, the numerical model is employed to conduct a systematic study on the impact of operational flexibility involving a temporal reduction in the upstream CO2 feed flow rate on the transient flow behaviour in the pipe over a period of 8 hours. A particular focus of attention is determining the optimum pipeline design and operating line packing conditions required in order to maximise the delay in the transition from dense phase flow to the highly undesirable two-phase flow following the ramping down of the CO2 feed flow rate. The investigations were conducted for both pure CO2 and its various realistic mixtures. For the case studies examined, the results show that the efficacy of line packing can be increased by increasing the pipeline length from 50 to 150 km for the same pipe inner diameter of 437 mm. However, as the pipelines length increased to 150 km, the increase in the pipe inner diameter beyond 486 mm was found to have no further impact on the line drafting time. While, in the case of inlet feed temperature, the line drafting time increases following an increase in the inlet feed temperature of transported fluid from 283.15 K up to 303.15 K. Beyond the operating inlet feed temperature of 311.15 K, the line drafting time only marginally increased. It is also shown that the presence of impurities reduces the transition time to two-phase flow following the ramping down of the feed flow rate

Droplet Dynamics Under Extreme Ambient Conditions

This open access book presents the main results of the Collaborative Research Center SFB-TRR 75, which spanned the period from 2010 to 2022. Scientists from a variety of disciplines, ranging from thermodynamics, fluid mechanics, and electrical engineering to chemistry, mathematics, computer science, and visualization, worked together toward the overarching goal of SFB-TRR 75, to gain a deep physical understanding of fundamental droplet processes, especially those that occur under extreme ambient conditions. These are, for example, near critical thermodynamic conditions, processes at very low temperatures, under the influence of strong electric fields, or in situations with extreme gradients of boundary conditions. The fundamental understanding is a prerequisite for the prediction and optimisation of engineering systems with droplets and sprays, as well as for the prediction of droplet-related phenomena in nature. The book includes results from experimental investigations as well as new analytical and numerical descriptions on different spatial and temporal scales. The contents of the book have been organised according to methodological fundamentals, phenomena associated with free single drops, drop clusters and sprays, and drop and spray phenomena involving wall interactions

Droplet Dynamics Under Extreme Ambient Conditions

This open access book presents the main results of the Collaborative Research Center SFB-TRR 75, which spanned the period from 2010 to 2022. Scientists from a variety of disciplines, ranging from thermodynamics, fluid mechanics, and electrical engineering to chemistry, mathematics, computer science, and visualization, worked together toward the overarching goal of SFB-TRR 75, to gain a deep physical understanding of fundamental droplet processes, especially those that occur under extreme ambient conditions. These are, for example, near critical thermodynamic conditions, processes at very low temperatures, under the influence of strong electric fields, or in situations with extreme gradients of boundary conditions. The fundamental understanding is a prerequisite for the prediction and optimisation of engineering systems with droplets and sprays, as well as for the prediction of droplet-related phenomena in nature. The book includes results from experimental investigations as well as new analytical and numerical descriptions on different spatial and temporal scales. The contents of the book have been organised according to methodological fundamentals, phenomena associated with free single drops, drop clusters and sprays, and drop and spray phenomena involving wall interactions

Applications of fluorocarbons for supercritical extraction in the petroleum industry.

Doctor of Philosophy in Chemical Engineering. University of KwaZulu-Natal, Howard College 2016The majority of supercritical processes utilise carbon dioxide (CO2) as the principal solvent, because CO2 has many attributes that make it an ideal supercritical fluid (SCF) solvent. This study investigates the possibility of replacing CO2 with trifluoromethane or hexafluoroethane, because of the poor performance of CO2 in cases where more polar and heavier molecular weight solutes must be extracted. Several applications in the petroleum industry, such as oil sludge treatment and the treatment of contaminated soils, are discussed. Due to the large number hydrocarbons present in such applications, a selection of solutes that could be used to simulate a simplified stream were chosen for these investigations. These selected solutes were n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, 1-hexene, 3-methylpentane, methylcyclohexane, toluene and water. High-pressure vapour-liquid equilibria and vapour-liquidliquid equilibria for binary systems containing either trifluoromethane or hexafluoroethane, with these solutes were measured using a static-analytic apparatus at temperatures of between (272.9 and 313.2) K. For several systems, the phase equilibria data were verified using bubble-point pressures measured with a static-synthetic, variable-volume cell. Parameters for thermodynamic models were obtained by regression of the experimental data for the binary systems. The models provide a good representation of the majority of the systems investigated, and were therefore also used to estimate portions of the critical locus curves. These critical locus curves were compared to the critical loci that were extrapolated from the sub-critical coexistence data as well as critical loci that were measured with a critical point determination apparatus. There is satisfactory agreement between the calculated, the extrapolated and the measured critical loci. The thermodynamic models were used to simulate the separation of several hydrocarbon-water emulsions using either CO2, trifluoromethane, hexafluoroethane or mixtures thereof. The simulations confirmed that trifluoromethane, hexafluoroethane as well as mixtures thereof, provide improved performances (recoveries and yields) when used as alternative solvents in the SCF extraction of these systems. An economic analysis of a SCF extraction process was performed to investigate the performance of the solvents, and if such SCF extraction processes, using a mixture of trifluoromethane and hexafluoroethane, would provide an economically competitive treatment process for hydrocarbon-water emulsions

Enabling PreOS Desktop Management

Abstract: Desktop management is probably the most resource-consuming task for the typical operations and support team, regardless of being frequently overlooked as not as complex or specialized as core network operations and management. Nowadays this scenario is even worst, since the increasing number and complexity of desktop systems was not matched by satisfactory management solutions -despite the relative success of products such as Intel's Landesk or Microsoft's SMS. In order to address this problem, we are exploring a different approach to desktop management, through the design and implementation of the OpenDMS management framework. This open source framework differs from available products in several points, such as earlier remote management mechanisms (prior to operating system load), incorporation of existing open standards, a network-centric architecture, operating system neutrality and tighter integration between traditional PCs, Thin Clients and Network PCs. In this paper we discuss the current status of desktop management solutions and we present an overview of the OpenDMS approach, including its most relevant technical foundations and an application scenario