The global growth in electricity consumption and the shortcomings of renewable electricity generation technologies are some of the reasons why it is still relevant to evaluate the performance of power conversion technologies that are used in fossil fuel power stations. The power conversion technology that is widely used in fossil fuel power stations is the Rankine cycle. The goal of this study was to determine if the efficiency of a typical Rankine cycle can be improved by adding a heat pump as a bottoming cycle. Three simulation models were developed to perform this evaluation. The first is a simulation model of a Rankine cycle. A quite detailed Rankine cycle configuration was evaluated. The simulation model was used to determine the heating requirements of the heat pump cycle as well as its operating temperature ranges. The efficiency of this Rankine cycle was calculated as 43.05 %. A basic vapour compression cycle configuration was selected as the heat pump of the combined cycle. A simulation model of the vapour compression cycle and the interfaces with the Rankine cycle was developed as the second simulation model. Working fluids that are typically used in vapour compression cycles cannot be used for this application, due to temperature limitations. The vapour compression cycle’s simulation model was therefore also used to calculate the coefficient of performance (COP) for various working fluids in order to select a suitable working fluid. The best cycle COP (3.015 heating) was obtained with ethanol as working fluid. These simulation models were combined to form the simulation model of the Rankine-heat pump combined cycle. This model was used to evaluate the performance of the combined cycle for two different compressor power sources. This study showed that the concept of using steam turbine or electrical power to drive a compressor driven vapour compression cycle in the configuration proposed here does not improve the overall efficiency of the cycle. The reasons for this were discovered and warrant future investigation. / Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013.

The global growth in electricity consumption and the shortcomings of renewable electricity generation technologies are some of the reasons why it is still relevant to evaluate the performance of power conversion technologies that are used in fossil fuel power stations. The power conversion technology that is widely used in fossil fuel power stations is the Rankine cycle. The goal of this study was to determine if the efficiency of a typical Rankine cycle can be improved by adding a heat pump as a bottoming cycle. Three simulation models were developed to perform this evaluation. The first is a simulation model of a Rankine cycle. A quite detailed Rankine cycle configuration was evaluated. The simulation model was used to determine the heating requirements of the heat pump cycle as well as its operating temperature ranges. The efficiency of this Rankine cycle was calculated as 43.05 %. A basic vapour compression cycle configuration was selected as the heat pump of the combined cycle. A simulation model of the vapour compression cycle and the interfaces with the Rankine cycle was developed as the second simulation model. Working fluids that are typically used in vapour compression cycles cannot be used for this application, due to temperature limitations. The vapour compression cycle’s simulation model was therefore also used to calculate the coefficient of performance (COP) for various working fluids in order to select a suitable working fluid. The best cycle COP (3.015 heating) was obtained with ethanol as working fluid. These simulation models were combined to form the simulation model of the Rankine-heat pump combined cycle. This model was used to evaluate the performance of the combined cycle for two different compressor power sources. This study showed that the concept of using steam turbine or electrical power to drive a compressor driven vapour compression cycle in the configuration proposed here does not improve the overall efficiency of the cycle. The reasons for this were discovered and warrant future investigation. / Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013.

Despite pharmacological advances, exercise remains a cost effective preventative for cardiovascular disease (CVD) by acutely and chronically lowering systolic blood pressure (SBP). Although numerous studies have investigated aerobic and resistance training’s role in eliciting an acute SBP response termed post-exercise hypotension (PEH), few researchers have investigated how performing both cardiovascular and weight training in a single session (concurrent training) or how different prescriptions for order of exercise modality will elicit this PEH response; no known studies have attempted altering the order of exercise types within each session. This study seeks to determine if the order of exercise type will affect a PEH response following concurrent exercise. Participants (n=13), considered low risk for cardiovascular disease participated in a control session, graded exercise test (GXT) and two concurrent sessions, with concurrent sessions counterbalanced for order of exercise mode. Recovery SBP was analyzed in the laboratory for sixty minutes and for twenty-four hours thereafter using an ambulatory blood pressure monitor. All exercise conditions elicited a depression in SBP; however, only the cardiovascular-weight training (CVWT) concurrent session elicited PEH (p = 0.05). However, there were no differences in SBP attenuation between conditions. There was no main effect for PEH between conditions during twenty-four hour assessment. With no statistically significant differences in the magnitude of PEH twenty-four hours after exercise, it may be determined that the order of exercise does not vi affect the preventative attributes of aerobic and resistance exercise in regards to acute SBP response. Furthermore, only exercise involving resistance training (CVWT) provoked PEH during the first 60 minutes; therefore it may be argued that individuals should pair cardiovascular exercise with weight training in order to elicit the greatest cardiovascular benefits. Future studies should consider evaluating the effect of time of day and PEH following concurrent exercise to determine if pairing exercise modalities will at different times will affect the blood pressure response.

Inom revisionsbranschen upptar tilläggstjänster en betydande del av tjänsteutbudet. Utöver revision erbjuder revisionsbyråerna även tjänster inom redovisning, skatt och rådgivning. Forskning visar att när tilläggstjänster och revision säljs till samma kund så uppstår en synergieffekt som inom forskningsvärlden benämns kunskapsöverföring. Denna synergieffekt har enligt forskarna en positiv inverkan på revisionen vilket i sin tur kan leda till en effektivare revision. Mot denna bakgrund har denna studie som mål att ta reda på vad som konkret bidrar till att kunskapsöverföring kan uppstå inom en revisionsbyrå.Ett delsyfte är att studien ska fungera som en kartläggning av vad kunskapsöverföring kan innebära för revisorers dagliga arbetsuppgifter i praktiken. Eftersom effekten kunskapsöverföring uppstår mellan olika tjänsteområden och avdelningar har studien även som delsyfte att undersöka vilken betydelse kommunikation har för effektens uppkomst.På grund av studiens explorativa karaktär och vår frågeställning valde vi att genomföra dubbla metoder vilket innebar både intervjuer och enkäter. För att utöka vår förståelse och skapa underlag för enkäten genomförde vi sex intervjuer med fem auktoriserade/godkända revisorer och en konsult. Dessa respondenter representerar fem olika revisionsbyråer, varav fyra var big-4 byråer. Efter intervjuerna genomfördes även en enkätundersökning baserad på intervjuernas resultat som vände sig till alla auktoriserade/godkända revisorer i Sverige.Den teoretiska referensramen utgår från den tidigare arkivforskning som gett indikationer på kunskapsöverföringens existens inom revisionsbranschen. Utöver detta behandlas även forskning kring revisorns oberoende samt revisionskvalitet. För att anknyta till studiens delsyfte kring kommunikation presenteras även teorier kring överföring av kunskap.Resultaten från intervjuerna och enkäten presenteras i empirin tillsammans inom gemensamma teman utifrån vilka bidragande effekter vi har hittat. Dessa teman är förberedande arbete och förvarningar, användande av andras arbete, kommunikation, informationsvärdering samt påverkan på revisionsprocess. Empirikapitlet avslutas med två egna förklaringsmodeller för fenomenet kunskapsöverföring.Studien visar att revisorerna i stor utsträckning anser att kunskapsöverföring existerar. Revisorer kan effektivisera revisionsprocessen genom användande av det arbete som andra konsulter gjort under året samt få förvarningar som bättre förbereder dem inför revisionen. Kommunikation är nödvändig för att dessa faktorer ska kunna uppstå och revisorerna värderar information från konsulter individuellt sett. De förklaringsmodeller vi konstruerade kan till 38 % respektive 55 % förklara vad som bidrar till att kunskapsöverföring uppstår mellan tilläggstjänster och revision. / Within the audit industry, non-audit services constitute a significant part of the services that is offered. In addition to auditing, the audit firms also offer services within accounting, tax and advisory. Research has shown that a synergy effect known as knowledge spillover occurs when audit and non-audit services are sold to the same customer. According to the researchers, this synergy effect has a positive influence on the audit service which in turn could lead to a more efficient audit process. With this in mind, this study aims to find out which factors that contributes to the occurrence of knowledge spillover within an audit firm.A subsidiary aim is that the study shall work as an investigation of what knowledge spillover can mean for the daily work tasks of auditors. Since the knowledge spillover effect occurs between different service areas and departments, the study also aims to discover how communication can affect the emergence of the effect.Because of our research question and the explorative character of the study, we choose to perform mixed methods i.e. both interviews and surveys. With the purpose of expanding our understanding and create a basis for our survey, six interviews were performed with five APCs and one advisory consultant. These respondents represented five different audit firms, of which four were big-4. After this, a survey based on the results of the interviews was distributed to all APCs in Sweden.The theoretical framework sets out from earlier archival research that has indicated that knowledge spillover exists within the audit industry. Apart from this, research within the area of auditor independence and audit quality will also be presented. To link with the study’s subsidiary aim regarding communication, theories within the area of knowledge transfer will also be discussed.The empirical findings from the interviews and the survey are presented together in themes based on the contributing effects we’ve found. These themes are preparatory work and warnings, using the work of others, communication, information, evaluation and impact on the audit process. The chapter is then ended with two of our own explanatory models for the phenomenon of knowledge spillover.The results show that auditors to a great extent find that knowledge spillover exists. Accountants can streamline the audit process by using the work of other consultants performed during the year and also by getting early warnings that better prepare them for the audit. Communication is necessary for these factors to occur and auditors’ values information they receive from consultants individually. The explanatory models constructed can explain what factors that contributes to knowledge spillover between audit and non-audit services to 38 % respectively 55 %

Fossil fuels continue to deplete with use as they are irreplaceable. In addition, the environmental impact with the continuous use of these conventional fuels has generated global concern due to the production of harmful emission gases. An alternative source of energy has become inevitable. Technological advancements in the area of biomass use for both aviation and power generation are at different levels of development. There is however the need for an integrated approach to assess gas turbine engine behaviour in terms of performance, emission and economics when they are running on biofuels. The current research work is concerned with finding alternative fuel resources for use on stationary gas turbine engines for power generation with the necessary identification of suitable biofuels using a multidisciplinary approach. A techno-economic, environmental and risk assessment (TERA) model comprising the performance, emissions, economics and risk modules has been developed. There had been several simulations of two gas turbine engines (GTEs) to ascertain the effects of both ambient and operating conditions and the effect of fuel types on the engines. These simulations were done with the use of an in-house code-the Turbomatch and a code developed for the steam cycle which is employed for the combined cycle simulation. Cont/d.

Alcohol is among the most common substance to be co-administered with a variety of other drugs. It is frequently used simultaneously (i.e., on the same occasion) with cocaine. The objective of this qualitative investigation was to explore the patterns, contexts, functions, harmful consequences, risk-taking behaviors, and gender differences associated with the simultaneous use of cocaine and alcohol. In-depth semi-structured interviews with simultaneous alcohol and cocaine users were conducted at a residential treatment centre in Ontario, Canada (n=10). Two independent coders conducted a content analysis of the transcripts. Results revealed that method of cocaine use was an important variable when describing a simultaneous use occasion. There was a wide variety of reported contexts, functions, and harms associated with simultaneous alcohol and cocaine use. This research contributes to a better understanding of the patterns, functions, and contexts of simultaneous use, along with the corresponding risk taking behaviors and harms in treatment clients.

This thesis presents experimental and simulated data gathered specifically to assess air-cooled proton exchange membrane (PEM) fuel cells as a heat and electrical power source for residential combined heat and power (CHP). The experiments and simulations focused on the air-cooled Ballard Nexa fuel cell. The experimental characterization provided data to assess the CHP potential of the Nexa and validate the model used for the simulations. The model was designed to be applicable to any air-cooled PEM fuel cell. Based on hourly load data, four Nexa fuel cells would be required to meet the peak electrical load of a typical coastal British Columbia residence. For a year of operation with the four fuel cells meeting 100% of the electrical load, simultaneous heat generation would meet approximately 96% of the space heating requirements and overall fuel cell efficiency would be 70%. However, the temperature of the coolant expelled from the Nexa varies with load and is typically too low to provide for occupant comfort based on typical ventilation system requirements. For a year of operation, the coolant mean temperature rise is only 8.3 +/- 3.4 K above ambient temperature. To improve performance as a CHP heat engine, the Nexa and other air-cooled PEM fuel cells need to expel coolant at temperatures above 325 K. To determine if PEM fuel cells are capable of achieving this coolant temperature, a model was developed that simulates cooling system heat transfer. The model is specifically designed to determine coolant and stack temperature based on cooling system and stack design (i.e. geometry). Simulations using the model suggest that coolant mass flow through the Nexa can be reduced so that the desired coolant temperatures can be achieved without the Nexa stack exceeding 345 K during normal operation. Several observations are made from the presented research: 1) PEM fuel cell coolant air can be maintained at 325 K for residential space heating while maintaining the stack at a temperature below the 353 K Nafion design limits chosen for the simulations; 2) The pressure drop through PEM cooling systems needs to be considered for all stack and cooling system design geometries because blower power to overcome the pressure drop can become very large for designs specifically chosen to minimize stack temperature or for stacks with long cooling channels; 3) For the air-cooled Nexa fuel cell stack, heat transfer occurring within the fuel cell cooling channels is better approximated using a constant heat flux mean Nusselt correlation than a constant channel temperature Nusselt correlation. This is particularly true at higher output currents where stack temperature differences can exceed 8 K.

The work presented in this thesis is devoted to the study of mechanism of tyre force generation and its influence on handling dynamics of ground vehicles. The main part of the work involves the development of tyre models for use under steady-state and transient operating conditions. The general capability of these models is assessedin a full vehicle simulation environment. The interaction between tyre and vehicle dynamics is critically evaluated and the observed vehicle behaviour is related to the inherent characteristics of different tyre models. In the field of steady-state tyre modelling, two versions of a numerical tyre model are developed. The modelling procedure is carried out in accordance with the viscoelastic properties of rubber, which influence the mechanical properties of the tyre structure and play a significant role in the determination of friction in the tyre contact patch. Whilst the initial simple version of the tyre model assumes a parabolic pressure distribution along the contact, a later more elaborate model employs a numerical method for the calculation of the actual normal pressure distribution. The changes in the pressure distribution as a result of variations in the rolling velocity and normal load influence mainly the levels of self-aligning moment, whilst the force characteristics remain practically unaffected. The adoption of a velocity dependent friction law explains the force generating behaviour of tyres at high sliding velocities. The analysis is extended to the area of transient tyre behaviour with the development of a tyre model appropriate for the study of transient friction force generation within the contact patch. The model incorporates viscoelasticity and inertial contributions, and incorporates a numerical stick-slip law. These characteristics are combined together for the successful simulation of transient friction force generation. The methodologies developed for the modelling of transient friction and steady-state tyre force generation are combined and further extended in order to create a generic transient tyre model. This final model incorporates a discretised flexible viscoelastic belt with inertia and a separate fully-dynamic discretised tread, also with inertia and damping, for the simulation of actual prevailing conditions in the contact patch. The generic tyre model appears to be capable of performing under a variety of operating conditions, including periodic excitations and transient inputs which extend to the non-linear range of tyre behaviour. For the evaluation of the influence of the aforementioned tyre models on the handling responses of a vehicle, a comprehensive vehicle model is developed, appropriate for use in handling simulations. The two versions of the steady-state models and the generic transient model are interfaced with the vehicle model, and the response of the vehicle to a step-steer manoeuvre is compared with that obtained using the Magic Formula tyre model. The comparison between the responses is facilitated by the definition of a new measure, defined as the non-dimensional yaw impulse. It is found that the transience involved in tyre behaviour may largely affect the response of a vehicle to a prescribed input.

A computer program, called &ldquo / Cogeneration Design&quot / is developed using Visual Basic 6.0, for conceptually designing cogeneration power plants. Design is focused on power plants to be built in university campuses, where there is mainly heating, hot water, electricity and sometimes cooling demands. Middle East Technical University campus is considered as the primary working area. Before the conceptual design study, detailed information regarding description of the campus, infrastructure, annual electric, water and heat demand covering last 10 years, properties of existing heat plant including natural gas expenses and specifications of the steam distribution pipes and electricity grid are collected and examined in detail. Throughout the thesis, eight different natural gas fired cogeneration power plant designs are developed regarding different gas turbine and steam turbine configurations, for METU Campus, considering the Campus&#039 / properties described above, by using the &quot / Cogeneration Design&quot / program. Then, by means of a thermoeconomic optimization process, cost summary reports are prepared and the feasibility of the designed cogeneration power plants are discussed.

In this thesis, several configurations of combined cycle cogeneration systems proposed by the author and an existing system, the Bilkent Combined Cycle Cogeneration Plant, are investigated by energy, exergy and thermoeconomic analyses. In each of these configurations, varying steam demand is considered rather than fixed steam demand. Basic thermodynamic properties of the systems are determined by energy analysis utilizing main operation conditions. Exergy destructions within the system and exergy losses to environment are investigated to determine thermodynamic inefficiencies in the system and to assist in guiding future improvements in the plant. Among the different approaches for thermoeconomic analysis in literature, SPECO method is applied. Since the systems have more than one product (process steam and electrical power), systems are divided into several subsystems and cost balances are applied together with the auxiliary equations. Hence, cost of each product is calculated. Comparison of the configurations in terms of performance assessment parameters and costs per unit of exergy are also given in this thesis.