Modelling of thermo-acoustic refrigerators using general algebraic modelling system
- Authors: Tartibu, L.K.
- Date: 2016
- Subjects: Thermo-acoustic refrigerator , Optimisation , Modelling
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/217038 , uj:21591 , Citation: Tartibu, L.K. 2016. Modelling of thermo-acoustic refrigerators using general algebraic modelling system.
- Description: Abstract: While thermo-acoustic refrigeration is new among emerging technology, it shows strong potential towards the development of sustainable and renewable energy systems by utilising a sound wave to remove the heat. This work discusses a new mathematical programming approach that provides fast initial engineering estimates to initial design calculations, describing the optimal geometry of thermo-acoustic refrigerators. Three different criteria describing their performances were taken into account: maximum cooling, best coefficient of performance and acoustic power loss. As the stack has been identified as the heart of the device where heat transfer takes place, this new approach aims to optimise its geometrical parameters: namely, the stack position, the stack length, the blockage ratio and the stack pore sizes. Hence, the optimisation task is formulated as a three-criterion nonlinear programming problem with discontinuous derivatives. This approach was implemented in the General Algebraic Modelling Systems. The unique characteristic of this research is the computation of all efficient optimal solutions, allowing the decision maker to identify the most efficient solution. The proposed modelling approach was investigated experimentally to evaluate its ability to predict the best parameters describing the geometry of the stack. Similar trends were obtained to support the use of the proposed approach in the design of thermo-acoustic refrigerators.
- Full Text:
- Authors: Tartibu, L.K.
- Date: 2016
- Subjects: Thermo-acoustic refrigerator , Optimisation , Modelling
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/217038 , uj:21591 , Citation: Tartibu, L.K. 2016. Modelling of thermo-acoustic refrigerators using general algebraic modelling system.
- Description: Abstract: While thermo-acoustic refrigeration is new among emerging technology, it shows strong potential towards the development of sustainable and renewable energy systems by utilising a sound wave to remove the heat. This work discusses a new mathematical programming approach that provides fast initial engineering estimates to initial design calculations, describing the optimal geometry of thermo-acoustic refrigerators. Three different criteria describing their performances were taken into account: maximum cooling, best coefficient of performance and acoustic power loss. As the stack has been identified as the heart of the device where heat transfer takes place, this new approach aims to optimise its geometrical parameters: namely, the stack position, the stack length, the blockage ratio and the stack pore sizes. Hence, the optimisation task is formulated as a three-criterion nonlinear programming problem with discontinuous derivatives. This approach was implemented in the General Algebraic Modelling Systems. The unique characteristic of this research is the computation of all efficient optimal solutions, allowing the decision maker to identify the most efficient solution. The proposed modelling approach was investigated experimentally to evaluate its ability to predict the best parameters describing the geometry of the stack. Similar trends were obtained to support the use of the proposed approach in the design of thermo-acoustic refrigerators.
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Thermal losses considerations in thermo-acoustic engine design
- Authors: Tartibu, L.K.
- Date: 2016
- Subjects: Thermo-acoustic engine , Modelling , Multi-objective optimization
- Language: English
- Type: Conference proceedings
- Identifier: http://ujcontent.uj.ac.za8080/10210/385373 , http://hdl.handle.net/10210/217031 , uj:21588 , Citation: Tartibu, L.K. 2016. Thermal losses considerations in thermo-acoustic engine design.
- Description: Abstract: Thermo-acoustic cooling as an environmentally friendly refrigeration system is one of the research areas being pursued. Although not commercially available and simple to fabricate, the designing of thermo-acoustic coolers involves significant technical challenges. Many fundamental issues related to the thermo-acoustic effects and the associated heat transfer must be addressed. The most inhibiting characteristic of current thermo-acoustic cooling devices is the lack of efficiency. The stack has been identified as the heart of the device where the heat transfer takes place. Improving its performance will make thermo-acoustic technology more attractive. Most of the existing efforts have not taken thermal losses to the surroundings into account in the derivation of the models. Five different parameters describing the stack geometry and the angular frequency of the standing wave are considered. This work explores the use of a multi-objective optimization approach to model and to optimize the performance of a simple thermo-acoustic engine. The present study highlights the importance of thermal losses in the modelling of small-scale thermo-acoustic engines using a multi-objective approach. The unique characteristic of this research is the computing of all efficient optimal solutions describing the best geometrical configuration of thermo-acoustic engines.
- Full Text:
- Authors: Tartibu, L.K.
- Date: 2016
- Subjects: Thermo-acoustic engine , Modelling , Multi-objective optimization
- Language: English
- Type: Conference proceedings
- Identifier: http://ujcontent.uj.ac.za8080/10210/385373 , http://hdl.handle.net/10210/217031 , uj:21588 , Citation: Tartibu, L.K. 2016. Thermal losses considerations in thermo-acoustic engine design.
- Description: Abstract: Thermo-acoustic cooling as an environmentally friendly refrigeration system is one of the research areas being pursued. Although not commercially available and simple to fabricate, the designing of thermo-acoustic coolers involves significant technical challenges. Many fundamental issues related to the thermo-acoustic effects and the associated heat transfer must be addressed. The most inhibiting characteristic of current thermo-acoustic cooling devices is the lack of efficiency. The stack has been identified as the heart of the device where the heat transfer takes place. Improving its performance will make thermo-acoustic technology more attractive. Most of the existing efforts have not taken thermal losses to the surroundings into account in the derivation of the models. Five different parameters describing the stack geometry and the angular frequency of the standing wave are considered. This work explores the use of a multi-objective optimization approach to model and to optimize the performance of a simple thermo-acoustic engine. The present study highlights the importance of thermal losses in the modelling of small-scale thermo-acoustic engines using a multi-objective approach. The unique characteristic of this research is the computing of all efficient optimal solutions describing the best geometrical configuration of thermo-acoustic engines.
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Optimal design study of thermoacoustic regenerator with lexicographic optimization method
- Tartibu, L.K., Sun, B., Kaunda, M.A.E.
- Authors: Tartibu, L.K. , Sun, B. , Kaunda, M.A.E.
- Date: 2015
- Subjects: Design , Implementing , Managing and practicing innovation , Optimization algorithms , Mechanical design , Modelling , Multi-objective/attribute decision-making , Design strategies
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/17471 , uj:15887 , ISSN: 1726-0531 , Citation: Tartibu, L.K. Sun, B. & Kaunda, M.A.E. 2015. Optimal design study of thermoacoustic regenerator with lexicographic optimization method. Journal of Engineering, Design and Technology, 13(3): 499 – 519. , DOI: 10.1108/JEDT-09-2012-0039.
- Description: Abstract: Purpose – This paper aims to illustrate the use of the augmented epsilon-constraint method implemented in general algebraic modelling system (GAMS), aimed at optimizing the geometry of a thermoacoustic regenerator. Thermoacoustic heat engines provide a practical solution to the problem of heat management where heat can be pumped or spot cooling can be produced. However, the most inhibiting characteristic of thermoacoustic cooling is their current lack of efficiencies. Design/methodology/approach – Lexicographic optimization is presented as an alternative optimization technique to the common used weighting methods. This approach establishes a hierarchical order among all the optimization objectives instead of giving them a specific (and most of the time, arbitrary) weight. Findings – A practical example is given, in a hypothetical scenario, showing how the proposed optimization technique may help thermoacoustic regenerator designers to identify Pareto optimal solutions when dealing with geometric parameters. This study highlights the fact that the geometrical parameters are interdependent, which support the use of a multi-objective approach for optimization in thermoacoustic. Originality/value – The research output from this paper can be a valuable resource to support designers in building efficient thermoacoustic device. The research illustrates the use of a lexicographic optimization to provide more meaningful results describing the geometry of thermoacoustic regenerator. It applies the epsilon-constraint method (AUGMENCON) to solve a five-criteria mixed integer non-linear problem implemented in GAMS (GAM software).
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- Authors: Tartibu, L.K. , Sun, B. , Kaunda, M.A.E.
- Date: 2015
- Subjects: Design , Implementing , Managing and practicing innovation , Optimization algorithms , Mechanical design , Modelling , Multi-objective/attribute decision-making , Design strategies
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/17471 , uj:15887 , ISSN: 1726-0531 , Citation: Tartibu, L.K. Sun, B. & Kaunda, M.A.E. 2015. Optimal design study of thermoacoustic regenerator with lexicographic optimization method. Journal of Engineering, Design and Technology, 13(3): 499 – 519. , DOI: 10.1108/JEDT-09-2012-0039.
- Description: Abstract: Purpose – This paper aims to illustrate the use of the augmented epsilon-constraint method implemented in general algebraic modelling system (GAMS), aimed at optimizing the geometry of a thermoacoustic regenerator. Thermoacoustic heat engines provide a practical solution to the problem of heat management where heat can be pumped or spot cooling can be produced. However, the most inhibiting characteristic of thermoacoustic cooling is their current lack of efficiencies. Design/methodology/approach – Lexicographic optimization is presented as an alternative optimization technique to the common used weighting methods. This approach establishes a hierarchical order among all the optimization objectives instead of giving them a specific (and most of the time, arbitrary) weight. Findings – A practical example is given, in a hypothetical scenario, showing how the proposed optimization technique may help thermoacoustic regenerator designers to identify Pareto optimal solutions when dealing with geometric parameters. This study highlights the fact that the geometrical parameters are interdependent, which support the use of a multi-objective approach for optimization in thermoacoustic. Originality/value – The research output from this paper can be a valuable resource to support designers in building efficient thermoacoustic device. The research illustrates the use of a lexicographic optimization to provide more meaningful results describing the geometry of thermoacoustic regenerator. It applies the epsilon-constraint method (AUGMENCON) to solve a five-criteria mixed integer non-linear problem implemented in GAMS (GAM software).
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Modelling, simulation and optimization of the materials flow of a multi-product assembling plant
- Nyemba, Wilson R., Mbohwa, Charles
- Authors: Nyemba, Wilson R. , Mbohwa, Charles
- Date: 2017
- Subjects: Arena® , Materials flow , Modelling
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/225005 , uj:22715 , Citation: Nyemba, W.R. & Mbohwa, C. 2017. Modelling, simulation and optimization of the materials flow of a multi-product assembling plant. 14th Global Conference on Sustainable Manufacturing, GCSM 3-5 October 2016, Stellenbosch, South Africa. DOI: 10.1016/j.promfg.2017.02.007. , ISSN: 2351-9789
- Description: Abstract: Various dynamic factors impact the movement of materials within a manufacturing environment, increasingly becoming complex for multi-product assembling plants owing to the multiplicity and interconnectedness of these factors. Analyzing these factors can be equally complex, requiring modelling and simulation tools. This paper looks at the modelling and simulation of the materials flow of a multi-product furniture assembling plant to develop an efficient system that accomplishes timely product deliveries at minimal cost. Generic simulation models based on 2 products were developed and constructed using Arena® Simulation Software. Following the simulation experiments and implementation of the results, the average hourly throughput was significantly increased and additional space to store materials prior to processing at workstations was created. The generic models were compatible with the company's other products and hence useful for the company’s production planning and scheduling.
- Full Text:
- Authors: Nyemba, Wilson R. , Mbohwa, Charles
- Date: 2017
- Subjects: Arena® , Materials flow , Modelling
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/225005 , uj:22715 , Citation: Nyemba, W.R. & Mbohwa, C. 2017. Modelling, simulation and optimization of the materials flow of a multi-product assembling plant. 14th Global Conference on Sustainable Manufacturing, GCSM 3-5 October 2016, Stellenbosch, South Africa. DOI: 10.1016/j.promfg.2017.02.007. , ISSN: 2351-9789
- Description: Abstract: Various dynamic factors impact the movement of materials within a manufacturing environment, increasingly becoming complex for multi-product assembling plants owing to the multiplicity and interconnectedness of these factors. Analyzing these factors can be equally complex, requiring modelling and simulation tools. This paper looks at the modelling and simulation of the materials flow of a multi-product furniture assembling plant to develop an efficient system that accomplishes timely product deliveries at minimal cost. Generic simulation models based on 2 products were developed and constructed using Arena® Simulation Software. Following the simulation experiments and implementation of the results, the average hourly throughput was significantly increased and additional space to store materials prior to processing at workstations was created. The generic models were compatible with the company's other products and hence useful for the company’s production planning and scheduling.
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Process mapping, modelling and optimization of plant layouts and materials handling in manufacturing
- Nyemba, Wilson R., Mbohwa, Charles, Nyemba, L. E. N.
- Authors: Nyemba, Wilson R. , Mbohwa, Charles , Nyemba, L. E. N.
- Date: 2018
- Subjects: Manufacturing , Materials handling , Modelling
- Language: English
- Type: Book chapter
- Identifier: http://hdl.handle.net/10210/270495 , uj:28752 , Citation: Nyemba, W.R., Mbohwa, C. & Nyemba, L.E.N. 2018. Process mapping, modelling and optimization of plant layouts and materials handling in manufacturing. In Book: Transactions on Engineering Sciences.
- Description: Abstract: Documenting process flows in a manufacturing environment provides a guide to understanding how processes are interconnected and how materials are handled, thus forming the basis for modelling and optimization in order to simplify the otherwise complex systems particularly in multi-product manufacturing. Research was carried out at a furniture manufacturing company specializing in the production of a wide range of furniture from hardwood. Owing to the multiplicity of processes and the movement of materials in manufacturing environments, the factors affecting such setups increasingly become complex, equally requiring complex techniques to analyze and optimize them. A work study carried out at the company established inherent problems that affected production and were used as the basis for modelling and optimizing the processes, focusing on grouping of workstations depending on functions, predicting performance using simulation and machine distance matrices for a reorganized plant layout. Results obtained after modelling and optimizing the plant layout were useful for production planning and control as well as enhancing the company’s productivity and efficiency.
- Full Text:
Process mapping, modelling and optimization of plant layouts and materials handling in manufacturing
- Authors: Nyemba, Wilson R. , Mbohwa, Charles , Nyemba, L. E. N.
- Date: 2018
- Subjects: Manufacturing , Materials handling , Modelling
- Language: English
- Type: Book chapter
- Identifier: http://hdl.handle.net/10210/270495 , uj:28752 , Citation: Nyemba, W.R., Mbohwa, C. & Nyemba, L.E.N. 2018. Process mapping, modelling and optimization of plant layouts and materials handling in manufacturing. In Book: Transactions on Engineering Sciences.
- Description: Abstract: Documenting process flows in a manufacturing environment provides a guide to understanding how processes are interconnected and how materials are handled, thus forming the basis for modelling and optimization in order to simplify the otherwise complex systems particularly in multi-product manufacturing. Research was carried out at a furniture manufacturing company specializing in the production of a wide range of furniture from hardwood. Owing to the multiplicity of processes and the movement of materials in manufacturing environments, the factors affecting such setups increasingly become complex, equally requiring complex techniques to analyze and optimize them. A work study carried out at the company established inherent problems that affected production and were used as the basis for modelling and optimizing the processes, focusing on grouping of workstations depending on functions, predicting performance using simulation and machine distance matrices for a reorganized plant layout. Results obtained after modelling and optimizing the plant layout were useful for production planning and control as well as enhancing the company’s productivity and efficiency.
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Process flow modelling and optimization of a foundry layout in Zimbabwe using simulation
- Nyemba, Wilson R., Mhlanga, Ruvimbo, Chinguwa, Simon, Mbohwa, Charles
- Authors: Nyemba, Wilson R. , Mhlanga, Ruvimbo , Chinguwa, Simon , Mbohwa, Charles
- Date: 2017
- Subjects: Foundry , Layout , Modelling
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/257770 , uj:27087 , Citation: Nyemba, W.R. et al. 2017. Process flow modelling and optimization of a foundry layout in Zimbabwe using simulation. Proceedings of the 2017 International Symposium on Industrial Engineering and Operations Management (IEOM) Bristol, UK, July 24-25, 2017.
- Description: Abstract: Foundry industry technologies have evolved over the years largely due to rapid changes in technology resulting in complexities that require careful planning and organization. Materials in the foundry industry pass through various stages and a number of factors, ranging from preparation of charges, materials handling and routing, furnace and production scheduling influence the process flows through these interconnected stages. Such a complex network of activities pose some challenges to companies that traditionally employ manual means of production planning. Research was carried out at one of Zimbabwe’s largest foundry companies, prompted by the company’s failure to produce affordable grinding media on time and in turn forcing their main customers to prefer cheaper imports. The work study revealed that the company’s key challenges were in materials handling and transportation distances through the various workstations. This research focused on modelling the process flows using simulation with the aim of optimizing and reorganizing the foundry layout to reduce production costs, improve productivity and enhance efficiency. The resulting model of the optimal layout and process flows has been adopted and the company is gradually regaining its competitiveness and market share.
- Full Text:
- Authors: Nyemba, Wilson R. , Mhlanga, Ruvimbo , Chinguwa, Simon , Mbohwa, Charles
- Date: 2017
- Subjects: Foundry , Layout , Modelling
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/257770 , uj:27087 , Citation: Nyemba, W.R. et al. 2017. Process flow modelling and optimization of a foundry layout in Zimbabwe using simulation. Proceedings of the 2017 International Symposium on Industrial Engineering and Operations Management (IEOM) Bristol, UK, July 24-25, 2017.
- Description: Abstract: Foundry industry technologies have evolved over the years largely due to rapid changes in technology resulting in complexities that require careful planning and organization. Materials in the foundry industry pass through various stages and a number of factors, ranging from preparation of charges, materials handling and routing, furnace and production scheduling influence the process flows through these interconnected stages. Such a complex network of activities pose some challenges to companies that traditionally employ manual means of production planning. Research was carried out at one of Zimbabwe’s largest foundry companies, prompted by the company’s failure to produce affordable grinding media on time and in turn forcing their main customers to prefer cheaper imports. The work study revealed that the company’s key challenges were in materials handling and transportation distances through the various workstations. This research focused on modelling the process flows using simulation with the aim of optimizing and reorganizing the foundry layout to reduce production costs, improve productivity and enhance efficiency. The resulting model of the optimal layout and process flows has been adopted and the company is gradually regaining its competitiveness and market share.
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Modelling, simulation and optimization of the comminution and flotation circuits of platinum for sustainable mineral processing
- Nyemba, Wilson R., Kapumha, Zvikomborero B., Mushiri, Tawanda, Mbohwa, Charles
- Authors: Nyemba, Wilson R. , Kapumha, Zvikomborero B. , Mushiri, Tawanda , Mbohwa, Charles
- Date: 2020
- Subjects: Comminution , Modelling , Flotation
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/438718 , uj:38142 , Citation: Nyemba, W.R. et al. 2020. Modelling, simulation and optimization of the comminution and flotation circuits of platinum for sustainable mineral processing.
- Description: Abstract: The quantum of minerals extracted from ore is critical for the success of mineral processing, hence the necessity to optimize the process flows in order to recover as much minerals as possible. The aim of this research was to identify bottlenecks and recovery-hampering factors within the comminution and flotation circuits of the concentrator plant at a platinum processing company in Zimbabwe. Modelling and simulation of the circuits were carried using Arena and Limn simulation software to optimize the process flows for improved throughput, maximum mineral recovery and enhanced efficiency and productivity. Alternative configurations of the layout of equipment were experimented on and compared with the original setup. The recommended reconfiguration of the circuits achieved increases of 2.97% in mineral recovery and 4 grams/ton in productivity resulting in a maximized output for the sustainable processing of platinum ore.
- Full Text:
- Authors: Nyemba, Wilson R. , Kapumha, Zvikomborero B. , Mushiri, Tawanda , Mbohwa, Charles
- Date: 2020
- Subjects: Comminution , Modelling , Flotation
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/438718 , uj:38142 , Citation: Nyemba, W.R. et al. 2020. Modelling, simulation and optimization of the comminution and flotation circuits of platinum for sustainable mineral processing.
- Description: Abstract: The quantum of minerals extracted from ore is critical for the success of mineral processing, hence the necessity to optimize the process flows in order to recover as much minerals as possible. The aim of this research was to identify bottlenecks and recovery-hampering factors within the comminution and flotation circuits of the concentrator plant at a platinum processing company in Zimbabwe. Modelling and simulation of the circuits were carried using Arena and Limn simulation software to optimize the process flows for improved throughput, maximum mineral recovery and enhanced efficiency and productivity. Alternative configurations of the layout of equipment were experimented on and compared with the original setup. The recommended reconfiguration of the circuits achieved increases of 2.97% in mineral recovery and 4 grams/ton in productivity resulting in a maximized output for the sustainable processing of platinum ore.
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A review on correction methods to solve limited representativeness in mineralogical analysis of measured liberation data
- Madiba, Mapilane S., Mulenga, François K., Hildebrandt, Diane
- Authors: Madiba, Mapilane S. , Mulenga, François K. , Hildebrandt, Diane
- Date: 2020
- Subjects: Mineral liberation , 2D imaging , Modelling
- Language: English
- Type: Conference Proceedings
- Identifier: http://hdl.handle.net/10210/465684 , uj:41652 , Citation: Madiba, M.S., Mulenga, F.K. & Hildebrandt, D. 2020. A review on correction methods to solve limited representativeness in mineralogical analysis of measured liberation data.
- Description: Abstract: Recent trends in the improvement of the mineral liberation measurements are briefly reviewed. Mineral liberation is the parameter used to suggest action to the flotation process which is intended to render better separation efficiency. The exposed grain surface area of 2D imaging of a polished section with stereological correction is proven to be the appropriate method to measure mineral liberation. Supplementary to 2D imaging, 3D micro CT scanner has also been used to determine the internal structure of the materials to analyze the volumetric grade of mineral of interest. There is a significant development that has been made in correcting measured liberation data acquired from 2 dimensional plane to 3 spatial dimensional. Although progress is being achieved, there are still challenges facing correction methods. Therefore, the advantages and disadvantages of specific issues, such as point spread function and excitation energies, facing the correction methods are discussed.
- Full Text:
- Authors: Madiba, Mapilane S. , Mulenga, François K. , Hildebrandt, Diane
- Date: 2020
- Subjects: Mineral liberation , 2D imaging , Modelling
- Language: English
- Type: Conference Proceedings
- Identifier: http://hdl.handle.net/10210/465684 , uj:41652 , Citation: Madiba, M.S., Mulenga, F.K. & Hildebrandt, D. 2020. A review on correction methods to solve limited representativeness in mineralogical analysis of measured liberation data.
- Description: Abstract: Recent trends in the improvement of the mineral liberation measurements are briefly reviewed. Mineral liberation is the parameter used to suggest action to the flotation process which is intended to render better separation efficiency. The exposed grain surface area of 2D imaging of a polished section with stereological correction is proven to be the appropriate method to measure mineral liberation. Supplementary to 2D imaging, 3D micro CT scanner has also been used to determine the internal structure of the materials to analyze the volumetric grade of mineral of interest. There is a significant development that has been made in correcting measured liberation data acquired from 2 dimensional plane to 3 spatial dimensional. Although progress is being achieved, there are still challenges facing correction methods. Therefore, the advantages and disadvantages of specific issues, such as point spread function and excitation energies, facing the correction methods are discussed.
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Enhancing productivity through simulation and layout planning : a case study of a manufacturing company in South Africa
- Lehlake, Stephen Katlego, Muyengwa, Goodwell, Mawane, Yvonie N.
- Authors: Lehlake, Stephen Katlego , Muyengwa, Goodwell , Mawane, Yvonie N.
- Date: 2018
- Subjects: Optimization , imulation , Modelling
- Language: English
- Type: Conference proceeding
- Identifier: http://hdl.handle.net/10210/290739 , uj:31567 , Citation:
- Description: Abstract: This paper aims to optimize a manufacturing process through creation of a simulation model that will be used to identify bottlenecks, restructure the layout and improve productivity. The paper also highlights the significance of process optimization in a manufacturing set up. Process optimizations strive to find the best solution for a process within the available constraints. Simulation is a collection of methodologies used to mimic the characteristics and behaviour of real system using computer software. Literature review was carried out to understand system dynamics and simulation. A case study was conducted at a manufacturing company. An Arena simulation model representing the process under study was developed and analysed. Various models were run and the results compared. The best model was developed that improved productivity through restructuring of the layout and minimization of the cycle times on the identified bottleneck stations. The simulation results showed that there was a vast difference on the amount of material input and the ATMs and Safes produced. The limitation of this study was that it only focused on the production of two products in the case studied company.
- Full Text:
- Authors: Lehlake, Stephen Katlego , Muyengwa, Goodwell , Mawane, Yvonie N.
- Date: 2018
- Subjects: Optimization , imulation , Modelling
- Language: English
- Type: Conference proceeding
- Identifier: http://hdl.handle.net/10210/290739 , uj:31567 , Citation:
- Description: Abstract: This paper aims to optimize a manufacturing process through creation of a simulation model that will be used to identify bottlenecks, restructure the layout and improve productivity. The paper also highlights the significance of process optimization in a manufacturing set up. Process optimizations strive to find the best solution for a process within the available constraints. Simulation is a collection of methodologies used to mimic the characteristics and behaviour of real system using computer software. Literature review was carried out to understand system dynamics and simulation. A case study was conducted at a manufacturing company. An Arena simulation model representing the process under study was developed and analysed. Various models were run and the results compared. The best model was developed that improved productivity through restructuring of the layout and minimization of the cycle times on the identified bottleneck stations. The simulation results showed that there was a vast difference on the amount of material input and the ATMs and Safes produced. The limitation of this study was that it only focused on the production of two products in the case studied company.
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Analysis of lightning surge effects on small-scale rooftop photovoltaic systems
- Holland, I., Doorsamy, W., Nixon, K.
- Authors: Holland, I. , Doorsamy, W. , Nixon, K.
- Date: 2018
- Subjects: Lightning protection , Modelling , Photovoltaic systems
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/274102 , uj:29227 , Citation: Holland, I., Doorsamy, W. & Nixon, K. 2018. Analysis of lightning surge effects on small-scale rooftop photovoltaic systems.
- Description: Abstract: Small-scale rooftop PV systems have become an attractive investment for small businesses and home owners. PV systems are inherently exposed to lightning phenomena and hence protection of the electrical system is required. In this paper, a simulation approach using MATLAB and Simulink is adopted to analyse the impacts of lightning induced effects on small-scale, rooftop, grid-connected PV systems. It is found that based on different coupling points, lightning surges could cause damage to the PV array, inverter as well as the connected load. The installation of surge protective devices could mitigate the potential damaging effects. In analysing the surge effects on the PV system, an understanding of the associated risk of damage to the PV system can be developed and hence the requirements for lightning protection of small-scale rooftop grid-connected PV systems can be comprehended.
- Full Text:
- Authors: Holland, I. , Doorsamy, W. , Nixon, K.
- Date: 2018
- Subjects: Lightning protection , Modelling , Photovoltaic systems
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/274102 , uj:29227 , Citation: Holland, I., Doorsamy, W. & Nixon, K. 2018. Analysis of lightning surge effects on small-scale rooftop photovoltaic systems.
- Description: Abstract: Small-scale rooftop PV systems have become an attractive investment for small businesses and home owners. PV systems are inherently exposed to lightning phenomena and hence protection of the electrical system is required. In this paper, a simulation approach using MATLAB and Simulink is adopted to analyse the impacts of lightning induced effects on small-scale, rooftop, grid-connected PV systems. It is found that based on different coupling points, lightning surges could cause damage to the PV array, inverter as well as the connected load. The installation of surge protective devices could mitigate the potential damaging effects. In analysing the surge effects on the PV system, an understanding of the associated risk of damage to the PV system can be developed and hence the requirements for lightning protection of small-scale rooftop grid-connected PV systems can be comprehended.
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Modeling approach - Flowchart for an in-situ Acid Mine Drainage neutralization
- Basika, Batshiku, Huberts, Robert
- Authors: Basika, Batshiku , Huberts, Robert
- Date: 2013
- Subjects: Acid mine drainage , Flowchart , Modelling , Neutralization
- Language: English
- Type: Abstract: Mining disturbs geologic formations that took millions of years to form; once disruption has taken place, a variety of problems may arise, from physical hazards to pollution of water and soil. The main goal of this paper is to demonstrate the technical feasibility of ferric and ferrous ions in-situ removal from Acid Mine Drainage and to design suitable flowcharts that can be used to model in-situ neutralization. The principle is based on lime neutralization without agitation that consists of diffusion and neutralization of hydrogen ions within the solution, which will increase the pH and lead to diffusion and precipitation of ferric and ferrous ions. Experimental tests were conducted with raw Acid Mine Drainage solution from Randfontein Mine (Johannesburg, South Africa) and the method shows that it is possible to achieve about 90 - 98% efficiency for ferric and ferrous ions in-situ removal from Acid Mine Drainage. , Conference proceedings
- Identifier: http://hdl.handle.net/10210/16892 , uj:15819 , Basika, B. & Huberts, R. Modelling approach - flowchart for an in-situ Acid Mine Drainage neutralization. International Conference Proceedings of PSRC, Johannesburg, 15-16 April 2013.
- Full Text: false
- Authors: Basika, Batshiku , Huberts, Robert
- Date: 2013
- Subjects: Acid mine drainage , Flowchart , Modelling , Neutralization
- Language: English
- Type: Abstract: Mining disturbs geologic formations that took millions of years to form; once disruption has taken place, a variety of problems may arise, from physical hazards to pollution of water and soil. The main goal of this paper is to demonstrate the technical feasibility of ferric and ferrous ions in-situ removal from Acid Mine Drainage and to design suitable flowcharts that can be used to model in-situ neutralization. The principle is based on lime neutralization without agitation that consists of diffusion and neutralization of hydrogen ions within the solution, which will increase the pH and lead to diffusion and precipitation of ferric and ferrous ions. Experimental tests were conducted with raw Acid Mine Drainage solution from Randfontein Mine (Johannesburg, South Africa) and the method shows that it is possible to achieve about 90 - 98% efficiency for ferric and ferrous ions in-situ removal from Acid Mine Drainage. , Conference proceedings
- Identifier: http://hdl.handle.net/10210/16892 , uj:15819 , Basika, B. & Huberts, R. Modelling approach - flowchart for an in-situ Acid Mine Drainage neutralization. International Conference Proceedings of PSRC, Johannesburg, 15-16 April 2013.
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