This research investigates analytical models that might serve to support decisions in the early stages of designing high volume small parts order picking systems. Because the development of analytical closed-forms is challenging, a common approach is to use simulation models for detailed design performance assessment. However, simulation is not suitable for early stage design purposes; because simulation models are time-consuming (thus expensive) to construct and execute, especially when the number of alternatives to evaluate is large. If available, analytical models are computationally cheaper. They provide faster and more flexible solutions and though usually less detailed, may be adequate to support early stages of design. The challenge is to develop generic analytic models providing useful results for a class of problems. This research focuses on a class of problems in high volume small parts order picking systems with pick-to-buffer technology. This is a new technology, and not yet in widespread use. The novelty in the modeling approach is the distinct separation of item-picking and order assembly operations which permits the development of performance models for both throughput and service level. Essentially the system is modeled as a tandem queue, and the two detailed models for the picking and assembly subsystems are developed based on detailed description of the operations. Solving the model provides estimates for performance measures, such as order cycle time and system throughput, which are essential in design. The approximation method requires estimating the squared coefficient of interdeparture times from the classical GX/G/1 queuing model, and a suitable approximation is derived in this thesis. Computational tests show the model to provide reasonably accurate estimates of system performance, with minimal computational overhead. To support the proposed queuing model, new models are developed for estimating mean and squared coefficient of variation for pick and assembly operation times. These models include the variability of order contents and the picking process, along with the physical layout. Results of the estimation compare very well with that of simulation.

In order to understand the effects of structurally induced line of sight (SILOS) jitter (vibration) and to predict its effects on optical system performance, a simple and practical vibratory model and software are developed by using discrete and finite element modeling techniques. For an existing simple optical system, discrete and FE dynamic models are constructed and they are validated by modal tests for the frequency range of interest. In order to find material properties of adhesive, which is used in optical system, a simple test is constructed and these properties are found by using a single degree of freedom model. The effects of vibration on the system performance are investigated under random vibration load conditions by using the software developed. It is concluded that the analytical model suggested can successfully be used in preliminary design stage of a simple optical system when the optical housing and lens behave rigidly in the frequency range of interest. The optical performance prediction software combines the optical element tolerances and displacements in order to determine the optical performance.

<p>The main questions concerning energy technologies today are their economical and environmental impacts. These entities are (at the present) assessed on the basis that operations proceed as newly installed/designed systems, during an assumed working life period. While this is the common way of perceiving energy systems, performance-over-time will change as an effect of (e.g. material) degradation and not solely of different operation scenarios. How and to what extent, is the question that needs assessing in order to evaluate if these changes will jeopardise the intended system performance requirement. In turn, this pro-active assessment and analysis is in line with today’s performance based directives, laws, regulations and concepts; of which the working life is an essential part.</p><p>The main context of the thesis, is a contribution to the Research and Development (R&D) topic on life performance of energy technologies, with papers on a literature review and case study on two system parts: <i>solar collector and ground heat exchanger (borehole)</i>; within the energy technology area of combined solar energy technologies/systems utilised in buildings. The thesis specifically presents a general description of requirements on constructed works and their material, components and systems. It also gives an insight to the energy technology R&D and engineering sector, regarding durability and service life assessment methodologies; and also to the durability of constructed works sector, regarding the needs for assessing material degradation in relation to system performance. The case studies presented in the thesis, show how durability of energy technologies may be sought-after, as well as specific knowledge and useful tools, methodologies and test setups for assessing long-term performance of combined solar energy technologies (in this case a solar-assisted heat pump system utilising a building integrated Unglazed Solar Collector and energy storage).</p><p>The utilisation of solar collectors and heat pumps (primarily for space and domestic tap water heating) has rapidly increased in Sweden during the last decades. Sweden has today the largest heat pump market in Europe. During recent years, there has also been an increased interest in heating systems that combine heat pumps with solar collectors (glazed and unglazed) and energy storages; with the aim of attaining a system that provides higher energy and greater economical performances than individual solar collector or heat pump systems. If these systems are to be successful they must be economically feasible; placing emphasis on the cost, durability and performance of the system.</p><p>The main issue on life performance of energy technologies is how and to what extent, performance reduction in individual materials and components influences the overall system performance; as the essence of energy system sustainability is system performance.</p>

The current approach to performance measurement in British Columbia is to select and match performance measures with strategic goals and objectives so that health administrators and decision makers can evaluate the performance of different care sectors (e.g. primary, community and acute care) within the provincial health system. Although this approach offers basic understanding of system performance, it is static and considers the performance of organizational components in isolation from their interrelationships and external influences. The purpose of this research is to enhance the current performance measurement approach in BC by linking health system variables through causal relationships and feedback loops that can impact and lead to health system sustainability. The qualitative system dynamics method was applied to develop a conceptual performance measurement model. Fifteen interviews with stakeholders were conducted at the BC Ministry of Health to validate and improve the pre-validation model. A post-validation model was then created based on the feedback and comments from the 15 interview participants. As a product of this research, the post-validation model, Web of Measures 2.0, will explain how the identified cause and feedback mechanisms both internal and external to the BC health system may help determine policy levers for designing and developing quality improvement initiatives. Although quantitative analysis is out of scope for this research, potential benefits of inputting BC data into the proposed model are discussed at the end of this thesis. / Graduate / 0769 / 0790 / qi.william.yang@gmail.com

BACKGROUND Integrated healthcare systems are believed to be enabled by the electronic exchange of clinical information. Canada and other national health systems are making substantial investments in information technology, in order to liberate and share clinical information between providers, improve the quality and safety of care, and reduce costs, yet we currently have no way of measuring these information flows, nor of understanding whether they contribute to the integration of care delivery. METHODS A literature review and consensus development process (nominal group) were used to provide guidance on system integration measures which are enabled by electronic information exchange. In order to conceptualize the components of electronic information exchange, establish a reference vocabulary for terminology, and guide the development of a questionnaire to gather field data, a formal ontology was developed. Validation of a sub-group of the survey data quality was achieved using the ontology and an unrelated database, demonstrating how ontologies may be used to adapt performance measurement methodologies to systems where constraints such as time-compression, lack of resources or access to needed information are prevalent. RESULTS The survey tool gathered cross-sectoral data from a regional health system which populated a summary measure of inter-provider electronic health information exchange (the eHIE), and measured perceptions of system integration from a single health region. The eHIE indicated that 7 -12% of clinical information that could be shared, was being shared electronically in the health region. ANOVA confirmed a significant correlation between the amount of information being exchanged electronically in this system and respondent perceptions of system integration suggesting that the eHIE may be used as a leading indicator for healthcare system integration. CONCLUSIONS It is possible to conceptualize and quantify inter-provider electronic health information exchange. As complex adaptive systems, healthcare systems are dynamic and open to correction; the use of a leading or proximal indicator such as the eHIE may inform effective policy-making and resource allocation in our pursuit of the goal of seamlessly integrated care.

Migrating from a wired to a wireless implementation for communication system used in industrial applications is a logical move to avoid the many shortcomings associated with wires. When operated under harsh environments, those wires can break and could cause not only damage to the system but also endanger human lives. However, it is not well documented how well a wireless protocol can work under such harsh industrial environments. This thesis attempts to answer this research question in the point of view of gauging the performance of a wireless protocol under the influence of electromagnetic noise. More specifically, the type of noise signal that is the focus of this investigation is the random, pulsed type (e.g., discharges caused by sparking) that creates a hyperbolic broadband disturbance in the frequency domain. Consequently, a fractal noise model is used to study noise of this nature. The steps toward achieving this goal include: requirements gathering, wireless technology selection; noise modelling and synthesis; real noise capture and analysis to validate the chosen noise model; high-frequency fractal noise emulation in hardware; the use of a novel noise injection method for empirical work; and the conducting of a controlled synthetic noise-to-wireless node performance evaluation to obtain performance measure in the form of packet error rate (PER). Performance data in terms of PER versus signal-to-noise ratio (SNR) for various nodes separation have been collected. There were three significant findings: the obtained performance curves follow the standard 'S' trend; for a specific desired reliability (denoted by a certain PER), the SNR at the transmitter needs to be boosted as the correlation of the noise being present increases; and the maximum distance between nodes separation for a certain reliability to be achieved depends exponentially with the transmitter‟s SNR. The relationship in the third finding assists in placement of wireless nodes, which in turn can determine the minimum amount of wireless nodes required for an industrial system to reach the desired system reliability, thus boasting network cost saving.

Migrating from a wired to a wireless implementation for communication system used in industrial applications is a logical move to avoid the many shortcomings associated with wires. When operated under harsh environments, those wires can break and could cause not only damage to the system but also endanger human lives. However, it is not well documented how well a wireless protocol can work under such harsh industrial environments. This thesis attempts to answer this research question in the point of view of gauging the performance of a wireless protocol under the influence of electromagnetic noise. More specifically, the type of noise signal that is the focus of this investigation is the random, pulsed type (e.g., discharges caused by sparking) that creates a hyperbolic broadband disturbance in the frequency domain. Consequently, a fractal noise model is used to study noise of this nature. The steps toward achieving this goal include: requirements gathering, wireless technology selection; noise modelling and synthesis; real noise capture and analysis to validate the chosen noise model; high-frequency fractal noise emulation in hardware; the use of a novel noise injection method for empirical work; and the conducting of a controlled synthetic noise-to-wireless node performance evaluation to obtain performance measure in the form of packet error rate (PER). Performance data in terms of PER versus signal-to-noise ratio (SNR) for various nodes separation have been collected. There were three significant findings: the obtained performance curves follow the standard 'S' trend; for a specific desired reliability (denoted by a certain PER), the SNR at the transmitter needs to be boosted as the correlation of the noise being present increases; and the maximum distance between nodes separation for a certain reliability to be achieved depends exponentially with the transmitter‟s SNR. The relationship in the third finding assists in placement of wireless nodes, which in turn can determine the minimum amount of wireless nodes required for an industrial system to reach the desired system reliability, thus boasting network cost saving.

Made available in DSpace on 2015-05-08T14:53:42Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 998986 bytes, checksum: 476810476b0e46e0e25edce3e83bfa77 (MD5) Previous issue date: 2005-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aims to identify the limitations of productivity measurement systems (SMP`s) existing production unit in the sub-sector of the brewing industry of beverages. Is adopted with an exploratory case study set in a business sub-sector brewing the beverage industry, based on the criteria of typicality and accessibility, and the management team as the universe. Correlated variables SMP, productivity measures and limitations of SMP's to specific goals, opting for conducting a semistructured interview with the occupants of positions in levels managerial and strategic and collects the data through semi- structured, systematic observation and document analysis. Effects to quantitative and qualitative analysis addressing the SMP's according to established theoretical and quantitative data were sorted by spreadsheet to check. We identified management practices of production that characterize the existence of limitations of SMP's: lack of a measuring area structured, redundancy and lack of specificity of the measures and measurement methods, lack of organization of measures and their variables, large spread of frequency measurements in key areas of processes, logistics, packaging and engineering, since the disintegration of the software used to collect and process data to obtain low background in reporting, lack of cost-benefit evaluation of indicators and measurement system. There is a need to structure the SMP Strategic investigated from the viewpoint of cost, reliability, quality, flexibility and agility in order to add value in the decisions. / O presente trabalho visa identificar as limitações dos sistemas de medição de produtividade (SMP s) vigentes numa unidade produtiva do sub-setor cervejeiro da Indústria de bebidas. Adota-se uma pesquisa exploratória com estudo de caso ambientado numa empresa do sub-setor cervejeiro da indústria de bebidas, baseando-se nos critérios de tipicidade e acessibilidade, tendo o corpo gerencial como universo. Correlaciona-se as variáveis SMP, medidas de produtividade e limitações dos SMP s aos objetivos específicos, optando-se pela realização de uma entrevista semi-estruturada com os ocupantes de cargos nos níveis gerencial e estratégico e coleta-se os dados através de entrevista semi-estruturada, observação sistemática e análise documental. Efetua-se a análise quantitativa e qualitativa abordando os SMP s consoante à fundamentação teórica estabelecida e os dados quantitativos foram ordenados através de planilha eletrônica para checagem. Foram identificadas práticas gerenciais de produção que caracterizam a existência de limitações dos SMP s: inexistência de uma área de medição estruturada; redundância e falta de especificidade das medidas e métodos de medição utilizados; falta de organização das medidas e de suas variáveis; grande difusão da periodicidade das medições nas áreas-chave de processos, logística, packaging e engenharia; desintegração dos softwares utilizados desde a coleta e tratamento de dados, possibilitando baixo background na geração de relatórios; inexistência de avaliação custo-benefício dos indicadores e sistema de medição. Emerge a necessidade de estruturar o SMP investigado sob a ótica estratégica de custos, de confiabilidade, qualidade, flexibilidade e agilidade, de modo a agregar valor nas decisões.

Globally, there are vast amounts of low-grade heat sources from industrial waste and renewables that can be converted into electricity through advanced thermodynamic power cycles and appropriate working fluids. In this thesis, experimental research was conducted to investigate the performance of a small-scale Organic Rankine Cycle (ORC) system under different operating conditions. The experimental setup consisted of typical ORC system components, such as a turboexpander with a high speed generator, a scroll expander, a finned-tube condenser, an ORC pump, a plate evaporator and a shell and tube evaporator. R245fa was selected as the working fluid, on account of its appropriate thermophysical properties for the ORC system and its low ozone depletion potential (ODP). The test rig was fully instrumented and extensive experiments carried out to examine the influences of several important parameters, including heat source temperature, ORC pump speed, heat sink flow velocity, different evaporators and with or without a recuperator on overall R245fa ORC performances. In addition, in terms of the working fluid’s environmental impact, temperature match of the cycle heat processes and system compactness, CO2 transcritical power cycles (T-CO2) were deemed more applicable for converting low-grade heat to power. However, the system thermal efficiency of T-CO2 requires further improvement. Subsequently, a test rig of a small-scale power generation system with T-CO2 power cycles was developed with essential components connected; these included a plate CO2 supercritical heater, a CO2 transcritical turbine, a plate recuperator, an air-cooled finned-tube CO2 condenser and a CO2 liquid pump. Various preliminary test results from the system measurements are demonstrated in this thesis. At the end, a theoretical study was conducted to investigate and compare the performance of T-CO2 and R245fa ORCs using low-grade thermal energy to produce useful shaft or electrical power. The thermodynamic models of both cycles were developed and applied to calculate and compare the cycle thermal and exergy efficiencies at different operating conditions and control strategies. In this thesis, the main results showed that the thermal efficiency of the tested ORC system could be improved with an increased heat source temperature in the system with or without recuperator. When the heat source temperature increased from 145 oC to 155 oC for the system without recuperator, the percentage increase rates of turbine power output and system thermal efficiency were 13.6% and 14% respectively while when the temperature increased from 154 oC to 166 oC for the system with recuperator, the percentage increase rates were 31.2% and 61.97% respectively. In addition, the ORC with recuperator required a relative higher heat source temperature, which is comparable to a system without recuperator. On the other hand, at constant heat source temperatures, the working fluid pump speed could be optimised to maximise system thermal efficiency for ORC both with and without recuperator. The pressure ratio is a key factor impacting the efficiencies and power generation of the turbine and scroll expander. Maximum electrical power outputs of 1556.24W and 750W of the scroll expander and turbine were observed at pressure ratio points of 3.3 and 2.57 respectively. For the T-CO2 system, the main results showing that the CO2 mass flow rate could be directly controlled by varying the CO2 liquid pump speeds. The CO2 pressures at the turbine inlet and outlet and turbine power generation all increased with higher CO2 mass flow rates. When CO2 mass flow rate increased from 0.2 kg/s to 0.26kg/s, the maximum percentage increase rates of measured turbine power generation was 116.9%. However, the heat source flow rate was found to have almost negligible impact on system performance. When the thermal oil flow rate increased from 0.364kg/s to 0.463kg/s, the maximum percentage increase rate of measured turbine power generation was only 14.8%. For the thermodynamic analysis, with the same operating conditions and heat transfer assumptions, the thermal and exergy efficiencies of R245fa ORCs are both slightly higher than those of T-CO2. However, the efficiencies of both cycles can be enhanced by installing a recuperator at under specific operating conditions. The experiment and simulation results can thus inform further design and operation optimisations of both the systems and their components.

The lighting retrofit method is adopted as one of the solutions to reduce lighting energy consumption and improve lighting quality in existing buildings. Lighting controls and energy-efficient light sources are used to achieve the goals of the lighting retrofit. Nowadays, Light-Emitting Diodes (LEDs) are replacing traditional lighting technology owing to their high efficiency and longevity. One of the advantages of LEDs is the controllability function, which allows users to set the light level according to their preferences. This saves more energy and satisfies users’ lighting needs. However, over time, the performance of lighting retrofit projects deteriorates subject to failure of the retrofitted lights. Therefore, to maintain the performance of lighting retrofit projects, maintenance must be planned and performed. The impacts of the users’ lighting level requirements on LEDs’ life characteristics and lighting system performance are investigated by using lighting controls. Light and occupancy sensors adjust artificial light to the light level required by users and detect the presence of users in the zones, respectively. Light sensors measure the average illuminance in the zones. The measured illuminance is compared to the users’ set illuminance; if the measured illuminance is higher than the users’ set illuminance, lamps are dimmed to meet users’ lighting preference, when the measured illuminance is less than the users’ set illuminance, lamps in the zone are replaced by new ones. The dimming level in each zone at each sampling interval is used to estimate the operating junction temperature, thereafter the degradation rate and luminous flux are calculated. Light levels at workspace are modelled using the lumen method. This model helps to quantify energy savings and predict when lamps will fail to deliver the required light levels. In existing studies, users’ lighting level requirements are neglected when investigating the lifetime of the lighting system; however, users’ profile and driving schemes affect the operating conditions of a lighting system. From the simulation results, it is noted that lumen output degradation increases when the user’s set illuminance is above the illuminance required under normal operating conditions and decreases when the user’s set illuminance is below the illuminance required under normal operating conditions. Increased lumen output degradation shortens the lifetime of LEDs and reduces energy savings, while decreased lumen output degradation extends the lifetime and increases energy savings. Generally, lighting retrofit projects contain a large lighting population; investigating when each lamp will fail can be time-consuming and costly. In this research, a mathematical model is formulated to model LEDs’ failure by analysing the statistical properties of the lumen degradation rates. Based on the statistical properties of the degradation rates, the cumulative probability of failure distribution and the survival function are modelled. The formulated survival function is incorporated into the lighting maintenance optimization problem to balance energy savings and maintenance costs. A case study carried out shows that, in 10 years, the optimal lighting maintenance plan would save up to 59% of lighting energy consumption with acceptable maintenance costs. It is found that the proposed maintenance plan is more cost-effective than full maintenance. It is concluded that lumen degradation failure should be considered when investigating the performance of lighting retrofit projects, as this may not only affect energy savings but also reduce the level of illumination, which can cause visual discomfort. The initial investment costs of LEDs are still a barrier to the implementation of LED lighting systems in residential buildings. Energy-efficiency projects often face hurdles to access capital investments because decision-makers and funders do not have enough information about operational savings the project can provide and specific financial requirements applied to efficiency investment. In this research, an optimization model is formulated to give decision-makers and funders detailed information about the performance and operational savings that a LED lighting retrofit project can offer and its economic viability. The lumen degradation failure model developed is used to monitor and estimate the energy savings, and the optimal maintenance plan is scheduled to replace failed lamps. In the existing studies, the economic analysis of the lighting retrofit projects is assessed based on lighting population decay due to burnout failure while in this research economic analysis is assessed by considering the lumen degradation failure. The case study results show that the substitution of halogen light bulbs with LED light bulbs could save up to 291.4 GWh of energy consumption, and reduce 273:92 103 tons of CO2 emissions over 10-year period. The optimization model formulated is effective to help the decision-makers and funders to quantify the savings and assess the economic viability of the LED lighting retroïnˇA˛t project. This optimization model can help the decision-makers and funders to make an informed decision. / Thesis (PhD (Electrical Engineering))--University of Pretoria, 2020. / Electrical, Electronic and Computer Engineering / PhD (Electrical Engineering) / Unrestricted