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An air source heat pump (ASHP) water heater is a renewable and energy efficient hot water heating technology. ASHP water heaters are fast gaining maturity in the South African market and in Africa at large due to their low energy consumption (about 67 percent lower than conventional geysers), relatively low installation and operation cost, their environmental friendly nature and possibly the ease to retrofit with the old inefficient technologies. Furthermore, ASHP water heaters make use of some of the most recent advancement in refrigeration technologies enhancing their performance through a wide range of weather conditions. However, residential ASHP water heaters which come at the tail of a series of highly sophisticated models still harbour primitive control designs. One of such control system is the intermittent (on/off) control whereby the ASHP unit responds to a temperature differential threshold rather than instantaneous temperature fluctuations. Unfortunately, this control method contributes to a rapid deterioration of the compressor and other actuators due to high starting current during transient states and partial loading. Capacity control is a better alterative as it offers a more reliable system’s performance as well as a better protection for the system components. However, the drawbacks of implementing such a technology on residential ASHP water heaters is the initial purchasing cost. We use a systematic approach in this research to circumvent the purchasing cost and complete redesign hysteresis. The first step was centered around a hypothetical analysis of the performance of the heat exchangers in a bid to uncover the weakness during the operation of a residential ASHP water heater. It was observed that at ambient temperatures above 22°C notably during summer and winter afternoons, water only harnesses about 75 percent of the total heat rejected. Furthermore, the actuators keep doing work for about 15-20 minutes even after the heat transfer process has ceased completely. Following these observations, a sequential flow algorithm was developed aimed at matching the consumption point to weather variables like ambient temperature and secondly to most efficiently synchronize actuator components for a better energy management. This novel control method can save up to 58 percent of energy compared to the conventional on/off method during summer afternoons and averagely 20 percent during the rest of the day. It also has the merit to be cost effective as it barely requires no component retrofitting.

South Africa contributes approximately 0.5 percent to the total world milk demand and is the third largest producer of fresh cow milk in Africa after Sudan and Kenya. In comparison to any other enterprise, the cost of milk production is influenced by numerous factors, that in turn affect the profitability of the farm enterprise; however one of such factors is high electricity cost. In this regard, there is need for efficient operation of the milk processing plant at all stages and at the same time maximising on product quality and minimising on the cost of production including energy. At the dairy farm, milk handling mainly commences as the milk leaves the cow udder at 35°C–37°C and must be cooled rapidly to a storage temperature of 4°C in a bid to stop microbial activity. The cooling of the milk can be done directly by the bulk milk cooler (BMC) from 37°C to the required storage temperature of 4°C or it can be done successively through pre-cooling. The process of pre-cooling involves the use of a heat exchanger where in most instances the plate heat exchanger (PHE) is used as the pre-cooler (PC) thereby leading to energy savings in a dairy facility. Cooling of milk involves significant amount of energy and it could account for about 20 percent of the total energy consumed on a farm. The aim of the research was to develop mathematical models that could be used to predict the electrical energy performance and capture the cooling saving of an on-farm direct expansion bulk milk cooler (DXBMC) during the milk cooling process. Accordingly, data acquisition system (DAS) was designed and built to accurately measure the power consumption of the BMC, temperature of raw milk, room temperature, temperature of cold water, relative humidity and ambient temperature. The volume of milk produced per day was extracted from the daily records on the farm. In addition, the temperature sensors were connected to a four channel HOBO data loggers which were configured to log at every five-minutes interval. The results were analysed and the mathematical models were developed using MATLAB. The statistical Toolbox in MATLAB was used to rank the predictors according to their weight of importance using the ReliefF Algorithm test. The results showed that on average, the daily electrical energy consumed by the BMC at the two milking times was higher during the peak period (127.82 kWh and 93.86 kWh) than the off-peak period (48.31 kWh and 43.23 kWh). On average, the electricity used for cooling of milk on the dairy farm was 17.06 kWh/m3 of milk. The average monthly electricity used per cow on the farm was 8.03 kWh/cow which translated to an average of 0.26 kWh/cow/day The average specific energy consumption of the cooling system per litre of milk cooled was 0.02 kWh/L and was almost constant throughout the whole period of monitoring. Furthermore, the BMC was able to cool 57.33 L/kWh during the off-peak period which increased by 7.7 percent to 62.13 L/kWh during the peak period. Furthermore, mathematical models represented as multiple linear regression (MLR) models were built and developed using the experimental data. The developed mathematical models had good agreement with the experimental data as evidenced by the correlation coefficients of 0.922 and 0.8995 along with 0.935 and 0.930. The ReliefF Algorithm test revealed that the volume of milk was the principal contributor to the energy consumption of the BMC for both the morning (AM) and afternoon (PM) milking period. The Relative Prediction Error (RPE) was used to evaluate the suitability of the developed models. In this light, the AM off-peak model had RPE of 18.54 percent while the PM off-peak model had 14.42 percent. In addition, the AM peak and PM peak models had RPE of 19.23 percent and 18.95 percent respectively. This suggested that the MLR models for the off-peak and peak milking periods (both AM and PM) had acceptable prediction accuracy since the RPE values were between 10 percent and 20 percent. The findings from the experimental study showed that the coefficient of performance (COP) of the AM milking period was higher (2.20) than that of the PM milking period of the BMC (1.93). Increase in the milk volume led to an increase in the COP such that the peak period with higher milk volumes recorded a high COP increase of 12.61 percent and 19.81 percent for the AM and PM milking periods respectively.

Many problems in nature can be represented as some kind of a satisfiability problem. Several SAT solvers and SMT solvers have been developed in the last decade with the goal of checking the satisfiability of different SAT problems. An all-solution satisfiability modulo theories on top of the Z3 SMT solver is presented that uses the clause blocking algorithm to find all the solution sets of a SAT problem. Then, an incremental All-SMT solver has been presented based on the all-SMT solver which is able to find the satisfiable answers of an incremental SMT problem based on the solution set of the original problem.

This report aims to investigate why proven methods for recycling concrete waste as road construction material are not practiced in Sweden. An additional objective is to investigate how concrete is handled as a waste product and whether it would be environmentally friendly and financially beneficial to clients and contractors. Information has been extracted via interviews conducted with experts from various positions within the civil engineering industry. Additional information was obtained through literature studies and questionnaires sent and received via email. Results which were frequently mentioned by engineering professionals included the extra expense of transporting and processing crushed concrete, parties involved in the design and construction processtend to follow traditional methods of using tried and tested virgin materials, the assumption of responsibility for structural failure due to alternative materials and general lack of knowledge surrounding crushed concrete as a construction material. Conclusions are that crushed concrete is suitable for construction of subbases in roads and base courses of cycle/pedestrian paths. Traditionally used virgin materials are generally less expensive than crushed concrete. Existing legislation makes the use of recycled construction material difficult. Awareness and education regarding recycled concrete, as a construction material, should be increased.

Made available in DSpace on 2014-06-12T15:57:41Z (GMT). No. of bitstreams: 2 arquivo3220_1.pdf: 1307302 bytes, checksum: 42435c33fd14be36778e3c202d24fd2d (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / A maioria das empresas utiliza a linguagem natural livre para documentar software, desde os seus requisitos, até os casos de uso e testes usados para verificar o produto final. Visto que as fases de análise, projeto, implementação e teste do sistema dependem essencialmente dessa documentação, é preciso assegurar inicialmente a qualidade desses textos. Contudo, textos escritos em linguagem natural nem sempre são precisos, devido ao fenômeno da ambigüidade (léxica e estrutural), podendo dar margem a diferentes interpretações. Uma alternativa para se minimizar esse problema é o uso de uma Linguagem Natural Controlada - um subconjunto de alguma língua natural, que usa um vocabulário restrito a um domínio particular, e regras gramaticais que guiam a construção de sentenças com redução de ambigüidade semântica visando padronização e precisão dos textos. Este trabalho, na área de Teste de Software, apresenta a ucsCNL (Use Case Specification CNL), uma Linguagem Natural Controlada para escrever especificações de casos de uso no domínio de dispositivos móveis. A ucsCNL foi integrada à TaRGeT (Test and Requirements Generation Tool), uma ferramenta para geração automática de casos de teste funcionais baseados em cenários de casos de uso escritos em Inglês. A ucsCNL provê um ambiente para geração de casos de teste mais claros, com ambigüidade reduzida, influindo diretamente na qualidade dos testes e na produtividade dos testadores. A ucsCNL já está em uso e tem alcançado resultados satisfatórios

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For many companies, design related information mainly exists as rooms of paper-based archives, typically in the form of manufacturing drawings and technical specifications. This 'static' information cannot be easily reused. The work presented in this thesis proposes a methodology to ease this problem. It defines and implements a computer-based design tool that will enable existing design families to be transformed into 'dynamic' CAD-based models for the Conceptual, Embodiment and Detailed stages of the design process. Two novel concepts are proposed here, i) the use of a Function Means Tree to store Conceptual and Embodiment design and ii) a Variant Method to represent Detailed design. In this way a definite link between the more abstract conceptual and the concrete detailed design stages is realised by linking individual detailed designs to means in the Function Means Tree. The use of the Variant Method, incorporating 'state-of-the-art' developments in Solid Modelling, Feature-Based Design and Parametric Design, allows an entire family of designs to be represented by a single Master Model. Therefore, instances of this Master Model need only be stored as a set of design parameters. This enables current design families and new design cases to be more created more efficiently. Industrial Case Studies, including a Lathe Chuck family, a Drive-End casting and a family of Filtration Systems are given to prove the methodology.

Advances in materials technology, information and management systems have led to improvements in the engineering design, procurement, construction, installation and commissioning of process columns. The development of the front-end engineering design (FEED) process has led to the incorporation of best practices in the specification of equipment on projects during the design phase. The aim of the research is to investigate whether technical specifications have an impact on the life cycle costs of process columns. Adding to the initial capital cost of equipment, in the form of technical specification requirements, in an attempt to reduce life cycle costs, is always challenged during the project phase of a product life cycle. The principle of designing for the full product life cycle of process columns requires that consideration for both the project and operating life cycle be made at the stage of basic engineering. What is important to note is that the potential for life cycle cost savings at the beginning of a product life cycle is higher than during the operating life cycle. Figure S.1 illustrates this concept, and what is observed is that the potential for life cycle cost savings diminishes as the product life progresses over time. Process columns were chosen as the type of equipment to be investigated based on the nature, size and complexity of the equipment when compared to other equipment on a processing unit. Process columns are amongst the highest capital cost pieces of equipment in petrochemical units and usually have many auxiliary pieces of equipment associated with it in a system i.e. reboilers, condensers, pumps etc. / Dissertation (MEng)--University of Pretoria, 2009. / Graduate School of Technology Management (GSTM) / unrestricted

Post-editing machine translation has become more common in recent years due to the increase in materials requiring translation and the effectiveness of machine translation systems. This project presents a system for formalizing structured translation specifications that facilitates the assessment of the performance of a post-editor. This report provides details concerning two software applications: the Ruqual Specifications Writer, which aids in the authoring of post-editing project specifications, and the Ruqual Rubric Viewer which provides a graphical user interface for filling out a machine readable rubric file. The project as a whole relies on a definition of translation quality based on the specification approach. In order to test whether potential evaluators are able to reliably assess the quality of post-edited translations, a user study was conducted that utilized the Specifications Writer and Rubric Viewer. The specifications developed for the project were based on actual post-editing data provided by Ray Flournoy of Adobe. The study involved simulating the work of five post-editors, which consisted of developing texts and scenarios. 17 non-expert graders rated the work of the five fictional post-editors, and an Intraclass Correlation of the graders responses shows that they are reliable to a high degree. The groundwork laid by this project should help in the development of other applications that assist in the assessment of translation projects in terms of a specification approach to quality.