MISSTEV : model for information security shared tacit espoused values
- Authors: Thomson, Kerry-Lynn
- Date: 2007
- Subjects: Computer security -- Management , Management information systems -- Security measures , Data protection
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9787 , http://hdl.handle.net/10948/717 , Computer security -- Management , Management information systems -- Security measures , Data protection
- Description: One of the most critical assets in most organisations is information. It is often described as the lifeblood of an organisation. For this reason, it is vital that this asset is protected through sound information security practices. However, the incorrect and indifferent behaviour of employees often leads to information assets becoming vulnerable. Incorrect employee behaviour could have an extremely negative impact on the protection of information. An information security solution should be a fundamental component in most organisations. It is, however, possible for an organisation to have the most comprehensive physical and technical information security controls in place, but the operational controls, and associated employee behaviour, have not received much consideration. Therefore, the issue of employee behaviour must be addressed in an organisation to assist in ensuring the protection of information assets. The corporate culture of an organisation is largely responsible for the actions and behaviour of employees. Therefore, to address operational information security controls, the corporate culture of an organisation should be considered. To ensure the integration of information security into the corporate culture of an organisation, the protection of information should become part of the way the employees conduct their everyday tasks – from senior management, right throughout the entire organisation. Therefore, information security should become an integral component of the corporate culture of the organisation. To address the integration of information security into the corporate culture of an organisation, a model was developed which depicted the learning stages and modes of knowledge creation necessary to transform the corporate culture into one that is information security aware.
- Full Text:
- Date Issued: 2007
- Authors: Thomson, Kerry-Lynn
- Date: 2007
- Subjects: Computer security -- Management , Management information systems -- Security measures , Data protection
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9787 , http://hdl.handle.net/10948/717 , Computer security -- Management , Management information systems -- Security measures , Data protection
- Description: One of the most critical assets in most organisations is information. It is often described as the lifeblood of an organisation. For this reason, it is vital that this asset is protected through sound information security practices. However, the incorrect and indifferent behaviour of employees often leads to information assets becoming vulnerable. Incorrect employee behaviour could have an extremely negative impact on the protection of information. An information security solution should be a fundamental component in most organisations. It is, however, possible for an organisation to have the most comprehensive physical and technical information security controls in place, but the operational controls, and associated employee behaviour, have not received much consideration. Therefore, the issue of employee behaviour must be addressed in an organisation to assist in ensuring the protection of information assets. The corporate culture of an organisation is largely responsible for the actions and behaviour of employees. Therefore, to address operational information security controls, the corporate culture of an organisation should be considered. To ensure the integration of information security into the corporate culture of an organisation, the protection of information should become part of the way the employees conduct their everyday tasks – from senior management, right throughout the entire organisation. Therefore, information security should become an integral component of the corporate culture of the organisation. To address the integration of information security into the corporate culture of an organisation, a model was developed which depicted the learning stages and modes of knowledge creation necessary to transform the corporate culture into one that is information security aware.
- Full Text:
- Date Issued: 2007
Monitoring and intelligent control for complex curvature friction stir welding
- Hua, Tao
- Authors: Hua, Tao
- Date: 2006
- Subjects: Friction welding , Fuzzy systems
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9612 , http://hdl.handle.net/10948/420 , Friction welding , Fuzzy systems
- Description: A multi-input multi-output system to implement on-line process monitoring and intelligent control of complex curvature friction stir welding was proposed. An extra rotation axis was added to the existing three translation axes to perform friction stir welding of complex curvature other than straight welding line. A clamping system was designed for locating and holding the workpieces to bear the large force involved in the process between the welding tool and workpieces. Process parameters (feed rate, spindle speed, tilt angle and plunge depth), and process conditions (parent material and curvature), were used as factors for the orthogonal array experiments to collect sensor data of force, torque and tool temperature using multiple sensors and telemetry system. Using statistic analysis of the experimental data, sensitive signal features were selected to train the feed-forward neural networks, which were used for mapping the relationships between process parameters, process conditions and sensor data. A fuzzy controller with initial input/output membership functions and fuzzy rules generated on-line from the trained neural network was applied to perceive process condition changes and make adjustment of process parameters to maintain tool/workpiece contact and energy input. Input/output scaling factors of the fuzzy controller were tuned on-line to improve output response to the amount and trend of control variable deviation from the reference value. Simulation results showed that the presented neuro-fuzzy control scheme has adaptability to process conditions such as parent material and curvature changes, and that the control variables were well regulated. The presented neuro-fuzzy control scheme can be also expected to be applied in other multi-input multi-output machining processes.
- Full Text:
- Date Issued: 2006
- Authors: Hua, Tao
- Date: 2006
- Subjects: Friction welding , Fuzzy systems
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9612 , http://hdl.handle.net/10948/420 , Friction welding , Fuzzy systems
- Description: A multi-input multi-output system to implement on-line process monitoring and intelligent control of complex curvature friction stir welding was proposed. An extra rotation axis was added to the existing three translation axes to perform friction stir welding of complex curvature other than straight welding line. A clamping system was designed for locating and holding the workpieces to bear the large force involved in the process between the welding tool and workpieces. Process parameters (feed rate, spindle speed, tilt angle and plunge depth), and process conditions (parent material and curvature), were used as factors for the orthogonal array experiments to collect sensor data of force, torque and tool temperature using multiple sensors and telemetry system. Using statistic analysis of the experimental data, sensitive signal features were selected to train the feed-forward neural networks, which were used for mapping the relationships between process parameters, process conditions and sensor data. A fuzzy controller with initial input/output membership functions and fuzzy rules generated on-line from the trained neural network was applied to perceive process condition changes and make adjustment of process parameters to maintain tool/workpiece contact and energy input. Input/output scaling factors of the fuzzy controller were tuned on-line to improve output response to the amount and trend of control variable deviation from the reference value. Simulation results showed that the presented neuro-fuzzy control scheme has adaptability to process conditions such as parent material and curvature changes, and that the control variables were well regulated. The presented neuro-fuzzy control scheme can be also expected to be applied in other multi-input multi-output machining processes.
- Full Text:
- Date Issued: 2006
Practical and scalable synthesis of N-Alkyl-N,N'Diacylhydrazines
- Authors: Gouws, Melissa Claire
- Date: 2008
- Subjects: Chemistry, Organic , Acylation , Insecticides
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10406 , http://hdl.handle.net/10948/696 , Chemistry, Organic , Acylation , Insecticides
- Description: The work presented in this thesis is concerned with the evaluation of potential synthetic routes for the diacylhydrazine group of compounds, and particularly, unsymmetrical diacylhydrazines. Diacylhydrazines form the basis for a relatively new group of insecticides that have molt accelerating properties, and which are considered to offer substantial advantages over other insecticides used for the control of certain insects. The overall objective for this study is to evaluate different potential synthetic routes for a model diacylhydrazine with the view to define potentially scaleable routes. The compound selected for this study was the unsymmetrical diacylhydrazine, N-[N-(tertbutyl) phenylcarbonylamino](4-methylphenyl)-carboxamide since it offers the same range of challenges that would be expected for the synthesis of other similar unsymmetrical diacylhydrazines. Thus, the synthesis of unsymmetrical diacylhydrazines require two reaction steps: The first step is the synthesis of the intermediate mono-acylhydrazine, while the second step is the synthesis of the desired diacylhydrazine from the intermediate mono-acylhydrazine. The most important factor in the two-step reaction sequence is to obtain a high degree of selectivity for the desired mono-acylhydrazine isomer. Acylation of t-butylhydrazine using 4-methylbenzoyl chloride can produce the desired product N-[(tert-butyl)amino](4-methylphenyl)carboxamide in yields above 90 percent, but this reaction produces a variety of by-products, including the “wrong” isomer (N-amino-N- (tert-butyl)(4-methylphenyl)carboximide). Unexpected byproducts for this particular acylation reaction, not previously reported in the literature have also been identified during this investigation. This includes a de-butylated diacylhydrazine, (4-methylphenyl)- N-[(4-methylphenyl)carbonylamino] carboxamide. Although the reaction between tert-butylhydrazine and 4-methylbenzaldehyde is very selective giving near quantitative yields of the desired hydrazone, the subsequent conversion of the hydrazone into the desired mono-acylhydrazine is problematic. The most promising route appears via bromination to form the hydrazidic bromide, followed by hydrolysis of the hydrazidic bromide. Yields for the bromination reaction during this investigation were somewhat higher than that reported previously in literature. Hydrolysis of the hydrazidic bromide, apparently also results in the hydrolysis of the reaction product to give an ester of the free acid (when an ester solvent is used). The synthesis of N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide was only briefly considered to evaluate essentially two approaches, namely: · The conversion of the monoacylhydrazine, N-[(tert-butyl)amino](4- methylphenyl)carboxamide, by acylating with either benzoyl chloride or methylbenzoate (gave 86 percent N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide when benzoyl chloride was used as acylating agent); and · The one-pot conversion of the hydrazone, [(1E)-2-(4-methylphenyl)-1- azavinyl](tert-butyl)]amine, by bromination/hydrolysis and acylation. In this case, benzoyl chloride (2 percent N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide), benzoic acid (80.67 percent N-[N-(tertbutyl) phenylcarbonylamino](4-methylphenyl)carboxamide) were evaluated as potential acylating agents.
- Full Text:
- Date Issued: 2008
- Authors: Gouws, Melissa Claire
- Date: 2008
- Subjects: Chemistry, Organic , Acylation , Insecticides
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10406 , http://hdl.handle.net/10948/696 , Chemistry, Organic , Acylation , Insecticides
- Description: The work presented in this thesis is concerned with the evaluation of potential synthetic routes for the diacylhydrazine group of compounds, and particularly, unsymmetrical diacylhydrazines. Diacylhydrazines form the basis for a relatively new group of insecticides that have molt accelerating properties, and which are considered to offer substantial advantages over other insecticides used for the control of certain insects. The overall objective for this study is to evaluate different potential synthetic routes for a model diacylhydrazine with the view to define potentially scaleable routes. The compound selected for this study was the unsymmetrical diacylhydrazine, N-[N-(tertbutyl) phenylcarbonylamino](4-methylphenyl)-carboxamide since it offers the same range of challenges that would be expected for the synthesis of other similar unsymmetrical diacylhydrazines. Thus, the synthesis of unsymmetrical diacylhydrazines require two reaction steps: The first step is the synthesis of the intermediate mono-acylhydrazine, while the second step is the synthesis of the desired diacylhydrazine from the intermediate mono-acylhydrazine. The most important factor in the two-step reaction sequence is to obtain a high degree of selectivity for the desired mono-acylhydrazine isomer. Acylation of t-butylhydrazine using 4-methylbenzoyl chloride can produce the desired product N-[(tert-butyl)amino](4-methylphenyl)carboxamide in yields above 90 percent, but this reaction produces a variety of by-products, including the “wrong” isomer (N-amino-N- (tert-butyl)(4-methylphenyl)carboximide). Unexpected byproducts for this particular acylation reaction, not previously reported in the literature have also been identified during this investigation. This includes a de-butylated diacylhydrazine, (4-methylphenyl)- N-[(4-methylphenyl)carbonylamino] carboxamide. Although the reaction between tert-butylhydrazine and 4-methylbenzaldehyde is very selective giving near quantitative yields of the desired hydrazone, the subsequent conversion of the hydrazone into the desired mono-acylhydrazine is problematic. The most promising route appears via bromination to form the hydrazidic bromide, followed by hydrolysis of the hydrazidic bromide. Yields for the bromination reaction during this investigation were somewhat higher than that reported previously in literature. Hydrolysis of the hydrazidic bromide, apparently also results in the hydrolysis of the reaction product to give an ester of the free acid (when an ester solvent is used). The synthesis of N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide was only briefly considered to evaluate essentially two approaches, namely: · The conversion of the monoacylhydrazine, N-[(tert-butyl)amino](4- methylphenyl)carboxamide, by acylating with either benzoyl chloride or methylbenzoate (gave 86 percent N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide when benzoyl chloride was used as acylating agent); and · The one-pot conversion of the hydrazone, [(1E)-2-(4-methylphenyl)-1- azavinyl](tert-butyl)]amine, by bromination/hydrolysis and acylation. In this case, benzoyl chloride (2 percent N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide), benzoic acid (80.67 percent N-[N-(tertbutyl) phenylcarbonylamino](4-methylphenyl)carboxamide) were evaluated as potential acylating agents.
- Full Text:
- Date Issued: 2008
Product development as part of a positioning strategy for the hunting industry in the Eastern Cape
- Van Niekerk, Pieter du Preez
- Authors: Van Niekerk, Pieter du Preez
- Date: 2002
- Subjects: New products -- Marketing , Hunting -- South Africa -- Eastern Cape , Game farms -- South Africa -- Eastern Cape , Venison -- Marketing , Meat industry and trade -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10894 , http://hdl.handle.net/10948/111 , New products -- Marketing , Hunting -- South Africa -- Eastern Cape , Game farms -- South Africa -- Eastern Cape , Venison -- Marketing , Meat industry and trade -- South Africa -- Eastern Cape
- Description: In this study on product development and positioning in the hunting industry in the Eastern Cape, two conceptual frameworks were developed, based on a literature study. These positioning and product development concepts were tested against primary and secondary information gathered about the hunting industry. The game and hunting industries were in a strong growth phase at the time of this study. These industries are playing an increasingly important role in the economy of the Eastern Cape, and more and more agricultural land is utilised for game ranching. From the perspective of obtaining a competitive advantage in an increasingly competitive environment, it is therefore important for hunting providers to develop suitable products, and to position these products correctly. It is also important to investigate the characteristics of the game and hunting industries in the Eastern Cape and to get information about the characteristics of the market in which product development and positioning take place. Hunting is the most important form of game utilisation in the Eastern Cape, followed by cropping of game and live game sales. At the time of this study, the total value of the game utilised annually in the Eastern Cape was in excess of R168 million. Game utilisation seemed to be taking place on a sustainable basis, as the number of animals utilised annually was less than the annual production. Kudu and springbok provide the biggest total income, and, together with mountain reedbuck, are the most abundant species in the Eastern Cape. The main game-producing areas in the Eastern Cape coincide with the areas where extensive beef, sheep and goat farming are practised. The hunting products on offer from hunting providers, differ in certain ways. Aspects like price, type of hunting provided, game species available for hunting, terrain where hunting takes place, and various other aspects in connection with the hunt, differ from hunting provider to hunting provider. Characteristics of the hunting experience that hunters desire may be divided into core and variable elements. The core elements include: · the conditions pertaining to the hunt being spelt out clearly; · the maintenance of safety standards; · reasonable day fees; · the presence of game in sufficient numbers; and · other aspects generally desired by hunters. In the study it was found that the needs of hunters also differ regarding certain aspects of the hunting experience. These variable elements include price levels, type and availability of accommodation, and the role of the hunting provider. The core aspects that hunters desire are as a rule part of the product offering. From a product development perspective, the variable elements provide an opportunity to customise products to hunter needs. The inclusion or exclusion of variable elements from the product offering give rise to certain unique product features, and therefore provide the opportunity for product differentiation. After development, products are positioned firstly by selecting a market segment to focus on. Secondly, the needs of hunters in the target segment should be clearly identified, followed by the development of suitable products based on hunter needs, and taking into account the features of competitive offerings. Decisions should also be taken about the features to be included in the product offering to achieve product differentiation. After development of a suitable product, an image or brand should be chosen for the product, and this image should be effectively communicated to the market. A number of possible positioning options were identified for hunting providers. It was found that factors like the physical features of the ranch, available infrastructure, the market segment chosen, desires of the hunting providers, and the perception of the needs of hunters, eventually influence decisions about product development and positioning. The final decisions on positioning should take the core competencies of the hunting provider into account and should ensure that the hunting provider has the ability to fill the chosen position in the market.
- Full Text:
- Date Issued: 2002
- Authors: Van Niekerk, Pieter du Preez
- Date: 2002
- Subjects: New products -- Marketing , Hunting -- South Africa -- Eastern Cape , Game farms -- South Africa -- Eastern Cape , Venison -- Marketing , Meat industry and trade -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10894 , http://hdl.handle.net/10948/111 , New products -- Marketing , Hunting -- South Africa -- Eastern Cape , Game farms -- South Africa -- Eastern Cape , Venison -- Marketing , Meat industry and trade -- South Africa -- Eastern Cape
- Description: In this study on product development and positioning in the hunting industry in the Eastern Cape, two conceptual frameworks were developed, based on a literature study. These positioning and product development concepts were tested against primary and secondary information gathered about the hunting industry. The game and hunting industries were in a strong growth phase at the time of this study. These industries are playing an increasingly important role in the economy of the Eastern Cape, and more and more agricultural land is utilised for game ranching. From the perspective of obtaining a competitive advantage in an increasingly competitive environment, it is therefore important for hunting providers to develop suitable products, and to position these products correctly. It is also important to investigate the characteristics of the game and hunting industries in the Eastern Cape and to get information about the characteristics of the market in which product development and positioning take place. Hunting is the most important form of game utilisation in the Eastern Cape, followed by cropping of game and live game sales. At the time of this study, the total value of the game utilised annually in the Eastern Cape was in excess of R168 million. Game utilisation seemed to be taking place on a sustainable basis, as the number of animals utilised annually was less than the annual production. Kudu and springbok provide the biggest total income, and, together with mountain reedbuck, are the most abundant species in the Eastern Cape. The main game-producing areas in the Eastern Cape coincide with the areas where extensive beef, sheep and goat farming are practised. The hunting products on offer from hunting providers, differ in certain ways. Aspects like price, type of hunting provided, game species available for hunting, terrain where hunting takes place, and various other aspects in connection with the hunt, differ from hunting provider to hunting provider. Characteristics of the hunting experience that hunters desire may be divided into core and variable elements. The core elements include: · the conditions pertaining to the hunt being spelt out clearly; · the maintenance of safety standards; · reasonable day fees; · the presence of game in sufficient numbers; and · other aspects generally desired by hunters. In the study it was found that the needs of hunters also differ regarding certain aspects of the hunting experience. These variable elements include price levels, type and availability of accommodation, and the role of the hunting provider. The core aspects that hunters desire are as a rule part of the product offering. From a product development perspective, the variable elements provide an opportunity to customise products to hunter needs. The inclusion or exclusion of variable elements from the product offering give rise to certain unique product features, and therefore provide the opportunity for product differentiation. After development, products are positioned firstly by selecting a market segment to focus on. Secondly, the needs of hunters in the target segment should be clearly identified, followed by the development of suitable products based on hunter needs, and taking into account the features of competitive offerings. Decisions should also be taken about the features to be included in the product offering to achieve product differentiation. After development of a suitable product, an image or brand should be chosen for the product, and this image should be effectively communicated to the market. A number of possible positioning options were identified for hunting providers. It was found that factors like the physical features of the ranch, available infrastructure, the market segment chosen, desires of the hunting providers, and the perception of the needs of hunters, eventually influence decisions about product development and positioning. The final decisions on positioning should take the core competencies of the hunting provider into account and should ensure that the hunting provider has the ability to fill the chosen position in the market.
- Full Text:
- Date Issued: 2002
Restoring trust by verifying information integrity through continuous auditing
- Authors: Flowerday, Stephen
- Date: 2006
- Subjects: Auditing, Internal , Corporate governance
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9796 , http://hdl.handle.net/10948/504 , http://hdl.handle.net/10948/d1011920 , Auditing, Internal , Corporate governance
- Description: Corporate scandals such as Enron, WorldCom and Parmalat, have focused recent governance efforts in the domain of financial reporting due to fraudulent and/or erroneous accounting practices. In addition, the ineffectiveness of the current system of controls has been highlighted, including that some directors have been weak and ineffective monitors of managers. This board of director ‘weakness’ has called for additional mechanisms for monitoring and controlling of management, focusing on financial reporting. This problem intensifies in that today companies function in real-time, and decisions are based on available realtime financial information. However, the assurances provided by traditional auditing take place months after the transactions have occurred and therefore, a trust problem arises because information is not verified in real-time. Consequently, the errors and fraud concealed within the financial information is not discovered until months later. To address this trust problem a conceptual causal model is proposed in this study based on the principles of systems theory. The emergent property of the causal model is increased trust and control. This study establishes that mutual assurances assist in building trust and that information security assists in safeguarding trust. Subsequently, in order to have a positive relationship between the company directors and various stakeholders, uncertainty needs to be contained, and the level of trust needs to surpass the perceived risks. The study concludes that assurances need to be provided in real-time to restore stakeholder confidence and trust in the domain of financial reporting. In order to provide assurances in real-time, continuous auditing is required to verify the integrity of financial information when it becomes available, and not months later. A continuous auditing process has its foundations grounded in information technology and attends to the challenges in real-time by addressing the standardisation of data to enable effective analysis, the validation of the accuracy of the data and the reliability of the system.
- Full Text:
- Date Issued: 2006
- Authors: Flowerday, Stephen
- Date: 2006
- Subjects: Auditing, Internal , Corporate governance
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9796 , http://hdl.handle.net/10948/504 , http://hdl.handle.net/10948/d1011920 , Auditing, Internal , Corporate governance
- Description: Corporate scandals such as Enron, WorldCom and Parmalat, have focused recent governance efforts in the domain of financial reporting due to fraudulent and/or erroneous accounting practices. In addition, the ineffectiveness of the current system of controls has been highlighted, including that some directors have been weak and ineffective monitors of managers. This board of director ‘weakness’ has called for additional mechanisms for monitoring and controlling of management, focusing on financial reporting. This problem intensifies in that today companies function in real-time, and decisions are based on available realtime financial information. However, the assurances provided by traditional auditing take place months after the transactions have occurred and therefore, a trust problem arises because information is not verified in real-time. Consequently, the errors and fraud concealed within the financial information is not discovered until months later. To address this trust problem a conceptual causal model is proposed in this study based on the principles of systems theory. The emergent property of the causal model is increased trust and control. This study establishes that mutual assurances assist in building trust and that information security assists in safeguarding trust. Subsequently, in order to have a positive relationship between the company directors and various stakeholders, uncertainty needs to be contained, and the level of trust needs to surpass the perceived risks. The study concludes that assurances need to be provided in real-time to restore stakeholder confidence and trust in the domain of financial reporting. In order to provide assurances in real-time, continuous auditing is required to verify the integrity of financial information when it becomes available, and not months later. A continuous auditing process has its foundations grounded in information technology and attends to the challenges in real-time by addressing the standardisation of data to enable effective analysis, the validation of the accuracy of the data and the reliability of the system.
- Full Text:
- Date Issued: 2006
Selective para-funtionalization of phenol
- Authors: Indurkar, Jayant R
- Date: 2008
- Subjects: Phenol
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10402 , http://hdl.handle.net/10948/710 , Phenol
- Description: In previous work done in our laboratories, a method was discovered to produce phenolic mono-ethers from 4-hydroxyacetophenone and other 4-hydroxyketones by treating with ammonium peroxy-disulfate in an alcohol as a reaction solvent and in the presence of concentrated sulphuric acid or other strong protonic acids. Since this method of producing 4-alkoxyphenol ethers provides a very convenient way to modify hydroquinone and substituted hydroquinones to produce a variety of phenol mono-ethers, it was of interest to study the general scope of this reaction, including a more detailed investigation of the reaction mechanism. In previous studies, it was suggested that interaction between the aromatic pi-system of hydroquinone and the cyclohexa-2,5-diene structure of benzoquinone plays a significant role during the reaction. It was therefore of interest to investigate whether other compounds that are also capable of forming the cyclohexa-2,5-diene structure, will interact in a manner analogous to the hydroquinone/benzoquinone couple. Two specific compounds were selected for this purpose, namely 4-nitrosophenol and 4- (diphenylmethylene)cyclohexa-2,5-dien-1-one . The scope of etherification reactions of hydroquinone-benzoquinone or hydroquinone/benzoquinone like substrates such as 4-nitrosophenol and 4- (diphenylmethylene)cyclohexa-2,5-dien-1-one in the presence of acid catalyst and alcohols was investigated. These studies showed that hydroquinone, 4- nitrosophenol and 4-(diphenylmethylene)cyclohexa-2,5-dien-1-one successfully affords the phenolic ethers in good to excellent yield. For example, quantitative yield of 4-methoxyphenol could be obtained from a 1:1 mixture of hydroquinone and benzoquinone at the reflux temperature of methanol. In order to study the reaction mechanism, the cross-over reaction between tertbutylhydroquinone and benzoquinone (or hydroquinone and tertbutylbenzoquinone) was studied in detail. The results of these cross-over reactions were used to propose a mechanistic pathway that could explain the requirement for pi-interaction between the hydroquinone and benzoquinone molecules, the role of the acid catalyst, as well as the relative rates of hydroquinone and benzoquinone consumption during these reactions. The mechanism was also capable of explaining all the reaction products observed during these reactions. The work was then extended to reactions of 4-nitrosophenol and 4- (diphenylmethylene)cyclohexa-2,5-dien-1-one with methanol in the presence of either hydroquinone or benzoquinone. The results of these investigations strongly suggest the presence of similar interactions between these molecules that also influence the outcome of the reactions. The exploitation of pi-interactions between two molecules of these types investigated during this work opens an interesting field of chemistry. Clearly, the level of understanding developed during this work is only beginning to address this interesting field of chemistry and much work will need to be done to gain a fuller understanding of the chemistry involved as well as the potential synthetic value of these interactions.
- Full Text:
- Date Issued: 2008
- Authors: Indurkar, Jayant R
- Date: 2008
- Subjects: Phenol
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10402 , http://hdl.handle.net/10948/710 , Phenol
- Description: In previous work done in our laboratories, a method was discovered to produce phenolic mono-ethers from 4-hydroxyacetophenone and other 4-hydroxyketones by treating with ammonium peroxy-disulfate in an alcohol as a reaction solvent and in the presence of concentrated sulphuric acid or other strong protonic acids. Since this method of producing 4-alkoxyphenol ethers provides a very convenient way to modify hydroquinone and substituted hydroquinones to produce a variety of phenol mono-ethers, it was of interest to study the general scope of this reaction, including a more detailed investigation of the reaction mechanism. In previous studies, it was suggested that interaction between the aromatic pi-system of hydroquinone and the cyclohexa-2,5-diene structure of benzoquinone plays a significant role during the reaction. It was therefore of interest to investigate whether other compounds that are also capable of forming the cyclohexa-2,5-diene structure, will interact in a manner analogous to the hydroquinone/benzoquinone couple. Two specific compounds were selected for this purpose, namely 4-nitrosophenol and 4- (diphenylmethylene)cyclohexa-2,5-dien-1-one . The scope of etherification reactions of hydroquinone-benzoquinone or hydroquinone/benzoquinone like substrates such as 4-nitrosophenol and 4- (diphenylmethylene)cyclohexa-2,5-dien-1-one in the presence of acid catalyst and alcohols was investigated. These studies showed that hydroquinone, 4- nitrosophenol and 4-(diphenylmethylene)cyclohexa-2,5-dien-1-one successfully affords the phenolic ethers in good to excellent yield. For example, quantitative yield of 4-methoxyphenol could be obtained from a 1:1 mixture of hydroquinone and benzoquinone at the reflux temperature of methanol. In order to study the reaction mechanism, the cross-over reaction between tertbutylhydroquinone and benzoquinone (or hydroquinone and tertbutylbenzoquinone) was studied in detail. The results of these cross-over reactions were used to propose a mechanistic pathway that could explain the requirement for pi-interaction between the hydroquinone and benzoquinone molecules, the role of the acid catalyst, as well as the relative rates of hydroquinone and benzoquinone consumption during these reactions. The mechanism was also capable of explaining all the reaction products observed during these reactions. The work was then extended to reactions of 4-nitrosophenol and 4- (diphenylmethylene)cyclohexa-2,5-dien-1-one with methanol in the presence of either hydroquinone or benzoquinone. The results of these investigations strongly suggest the presence of similar interactions between these molecules that also influence the outcome of the reactions. The exploitation of pi-interactions between two molecules of these types investigated during this work opens an interesting field of chemistry. Clearly, the level of understanding developed during this work is only beginning to address this interesting field of chemistry and much work will need to be done to gain a fuller understanding of the chemistry involved as well as the potential synthetic value of these interactions.
- Full Text:
- Date Issued: 2008
Tailoring a lean product development framework for the South African automotive industry
- Authors: Mund, Klaudia
- Date: 2011
- Subjects: Lean manufacturing , Automobile industry and trade -- South Africa , Production management -- South Africa , Globalization
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:8792 , http://hdl.handle.net/10948/d1015737
- Description: Globalization in the automotive industry exerts enormous pressure on automotive manufacturers and forces many global companies to expand into emerging markets, which results in adopting new ways to manage product design and development. Excellence in product design and development offers an opportunity to gain competitive advantage and can be achieved by implementing Toyota´s Lean Product Development System (LPDS). Although in the last three years Toyota has been severely challenged by the global economic crisis, by a series of recalls resulting in reputation damage and also by natural disasters such as the recent tsunamis - the world can still learn from Toyota´s successes embodied in the lean concept and practices, which are integral to Toyota´s ‘way of life’. The LPDS model (Morgan & Liker 2006) has captured the attention of academics worldwide (including this researcher) thanks to the following key characteristics: shorter development times, less engineering hours involved in development, lower manufacturing costs, higher customer satisfaction and fewer defects reported. In the academic world, lean product development (LPD) is a new field of exploration and thus relevant literature and numbers of studies available are limited. However, scientists are asking questions about successful adaptation and adoption of this model to other environments beyond Toyota. Similarly, the researcher aimed in this thesis to find answers to its main research question, namely: ‘What would be a suitable LPD model for the South African automotive industry?’ South Africa (SA) is a country with a strong manufacturing tradition and although the automotive sector is the third-largest segment in the South African economy and its vehicle market is the largest on the African continent in a global perspective SA´s contribution is relatively small as it produces only 0.61percent of the global motor vehicle volume (OICA 2011). While the country strives to secure sustainable development for the automotive industry and seeks to improve its global competitiveness, companies operating in SA are currently faced with several unique challenges and problems. Lean has been expanding slowly in SA and some companies in the local automotive industry have implemented the lean concept into production areas to improve their operational excellence and performance. However, it is a search for excellence in product development (PD) that could best contribute to improved sustainability for the automotive industry and also provide an important strategic spur towards global competitiveness. The primary intention of this research was to develop an integrated LPD framework tailored for SA´s automotive industry. Considering this, it was necessary to determine current PD capabilities at domestic and international companies operating in SA´s automotive industry so as to examine levels of adaptation of LPD practices. A questionnaire survey and personal interviews involving all seven locally operating Original Equipment Manufacturers (OEMs), including Toyota, as well as 36 local automotive suppliers provided an empirical base for this investigation. This study indicates that SA plays an important supportive role in the global PD context. In spite of a strong manufacturing focus and very limited PD capabilities, SA´s automotive companies have already achieved a high level of ‘leanness’ in product engineering processes. However, on the downside, it appears that industry leaders and senior managers are sceptical about current and future capabilities and opportunities for SA in the designing and developing of global products.
- Full Text:
- Date Issued: 2011
- Authors: Mund, Klaudia
- Date: 2011
- Subjects: Lean manufacturing , Automobile industry and trade -- South Africa , Production management -- South Africa , Globalization
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:8792 , http://hdl.handle.net/10948/d1015737
- Description: Globalization in the automotive industry exerts enormous pressure on automotive manufacturers and forces many global companies to expand into emerging markets, which results in adopting new ways to manage product design and development. Excellence in product design and development offers an opportunity to gain competitive advantage and can be achieved by implementing Toyota´s Lean Product Development System (LPDS). Although in the last three years Toyota has been severely challenged by the global economic crisis, by a series of recalls resulting in reputation damage and also by natural disasters such as the recent tsunamis - the world can still learn from Toyota´s successes embodied in the lean concept and practices, which are integral to Toyota´s ‘way of life’. The LPDS model (Morgan & Liker 2006) has captured the attention of academics worldwide (including this researcher) thanks to the following key characteristics: shorter development times, less engineering hours involved in development, lower manufacturing costs, higher customer satisfaction and fewer defects reported. In the academic world, lean product development (LPD) is a new field of exploration and thus relevant literature and numbers of studies available are limited. However, scientists are asking questions about successful adaptation and adoption of this model to other environments beyond Toyota. Similarly, the researcher aimed in this thesis to find answers to its main research question, namely: ‘What would be a suitable LPD model for the South African automotive industry?’ South Africa (SA) is a country with a strong manufacturing tradition and although the automotive sector is the third-largest segment in the South African economy and its vehicle market is the largest on the African continent in a global perspective SA´s contribution is relatively small as it produces only 0.61percent of the global motor vehicle volume (OICA 2011). While the country strives to secure sustainable development for the automotive industry and seeks to improve its global competitiveness, companies operating in SA are currently faced with several unique challenges and problems. Lean has been expanding slowly in SA and some companies in the local automotive industry have implemented the lean concept into production areas to improve their operational excellence and performance. However, it is a search for excellence in product development (PD) that could best contribute to improved sustainability for the automotive industry and also provide an important strategic spur towards global competitiveness. The primary intention of this research was to develop an integrated LPD framework tailored for SA´s automotive industry. Considering this, it was necessary to determine current PD capabilities at domestic and international companies operating in SA´s automotive industry so as to examine levels of adaptation of LPD practices. A questionnaire survey and personal interviews involving all seven locally operating Original Equipment Manufacturers (OEMs), including Toyota, as well as 36 local automotive suppliers provided an empirical base for this investigation. This study indicates that SA plays an important supportive role in the global PD context. In spite of a strong manufacturing focus and very limited PD capabilities, SA´s automotive companies have already achieved a high level of ‘leanness’ in product engineering processes. However, on the downside, it appears that industry leaders and senior managers are sceptical about current and future capabilities and opportunities for SA in the designing and developing of global products.
- Full Text:
- Date Issued: 2011
The development and evaluation of a new manufacturing process for β-sitosterol-D glucoside
- Mtyopo, Mthetheleli Bethwell
- Authors: Mtyopo, Mthetheleli Bethwell
- Date: 2016
- Subjects: Pharmaceutical chemistry Chemistry, Organic
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: http://hdl.handle.net/10948/45920 , vital:39320
- Description: The existing production sequence of β-sitosterol-D-glucoside, a glucoside used in an “over-the-counter” (OTC) preparation under the brand name of Moducare® comprises of three process steps with an overall yield of less than 20%. The low yield is partly due to the instability of intermediates at reaction temperatures > 0oC, and partly due to the thermodynamic equilibrium between two stereoisomers. An economically alternative process was developed, evaluated and scaled-up in a 2l reactor. The project was initiated with a specific limitation in terms of the starting material that comprised a mixture of plant sterols, which necessitated a study of the isolation and purification of the desired product from a rather complex reaction mixture. The use of silver as halide acceptor for the Koenigs-Knorr synthesis did not give statistically significant different results from the same approach but using cadmium as halide acceptor instead. However, using the direct O-glucosylation approach not only gave statistically significant higher results, but also resulted in a much more convenient procedure. Under optimum conditions, a yield of approximately 83% (isolated) of 2,3,4,6- tetra-О-acetyl-β-sitosterol-D-glucoside could be achieved, which was substantially higher than that achieved with the traditional Koenigs-Knorr methodology and above reported yields in the literature (60-80%) for direct glycosylation. Separation of 2,3,4,6-tetra-О-acetyl-β-sitosterol-D-glucoside (BSSGT) from a reaction mixture that contains 2,3,4,6-tetra-О-acetyl-campesterol-D-glucoside (CSGT), 2,3,4,6-tetra-О-acetyl campestanol-glucoside (CSSGT), and 2,3,4,6-tetra-О-acetyl-sitostanol-Dglucoside (SSGT) was investigated using column chromatography. When using silica gel particles, very good separation efficiency and product recovery could be achieved using hexane/ethyl hexane as eluent. The isolated 2,3,4,6-tetra-О-acetyl-β-sitosterol-Dglucoside was easily hydrolysed to β-sitosterol-D-glucoside in high yields (79%) using methanolic KOH. The process for the production of β-sitosterol-D-glucoside was scaled-up from the laboratory bench scale (250 cm3) to a laboratory scale of 2 l using the direct Oglycosylation method. The overall yields of the scaled reaction for β-sitosterol-D-glucoside was slightly above the literature reported values (59%, 8/92) for the KnoenigsKnorr synthesis and compares well above (62%, 0/100) the current production process (less than 20% yields). When using catalogue prices, the material costs (without recycling) for the direct Oglucosylation route is approximately 57% less for the synthesis of 1kg of β-sitosterol-Dglucoside compared to the Koenigs-Knorr route. Given further savings for recycling, the direct O-glucosylation route provides an attractive alternative route for the synthesis ofthe target compound.
- Full Text:
- Date Issued: 2016
- Authors: Mtyopo, Mthetheleli Bethwell
- Date: 2016
- Subjects: Pharmaceutical chemistry Chemistry, Organic
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: http://hdl.handle.net/10948/45920 , vital:39320
- Description: The existing production sequence of β-sitosterol-D-glucoside, a glucoside used in an “over-the-counter” (OTC) preparation under the brand name of Moducare® comprises of three process steps with an overall yield of less than 20%. The low yield is partly due to the instability of intermediates at reaction temperatures > 0oC, and partly due to the thermodynamic equilibrium between two stereoisomers. An economically alternative process was developed, evaluated and scaled-up in a 2l reactor. The project was initiated with a specific limitation in terms of the starting material that comprised a mixture of plant sterols, which necessitated a study of the isolation and purification of the desired product from a rather complex reaction mixture. The use of silver as halide acceptor for the Koenigs-Knorr synthesis did not give statistically significant different results from the same approach but using cadmium as halide acceptor instead. However, using the direct O-glucosylation approach not only gave statistically significant higher results, but also resulted in a much more convenient procedure. Under optimum conditions, a yield of approximately 83% (isolated) of 2,3,4,6- tetra-О-acetyl-β-sitosterol-D-glucoside could be achieved, which was substantially higher than that achieved with the traditional Koenigs-Knorr methodology and above reported yields in the literature (60-80%) for direct glycosylation. Separation of 2,3,4,6-tetra-О-acetyl-β-sitosterol-D-glucoside (BSSGT) from a reaction mixture that contains 2,3,4,6-tetra-О-acetyl-campesterol-D-glucoside (CSGT), 2,3,4,6-tetra-О-acetyl campestanol-glucoside (CSSGT), and 2,3,4,6-tetra-О-acetyl-sitostanol-Dglucoside (SSGT) was investigated using column chromatography. When using silica gel particles, very good separation efficiency and product recovery could be achieved using hexane/ethyl hexane as eluent. The isolated 2,3,4,6-tetra-О-acetyl-β-sitosterol-Dglucoside was easily hydrolysed to β-sitosterol-D-glucoside in high yields (79%) using methanolic KOH. The process for the production of β-sitosterol-D-glucoside was scaled-up from the laboratory bench scale (250 cm3) to a laboratory scale of 2 l using the direct Oglycosylation method. The overall yields of the scaled reaction for β-sitosterol-D-glucoside was slightly above the literature reported values (59%, 8/92) for the KnoenigsKnorr synthesis and compares well above (62%, 0/100) the current production process (less than 20% yields). When using catalogue prices, the material costs (without recycling) for the direct Oglucosylation route is approximately 57% less for the synthesis of 1kg of β-sitosterol-Dglucoside compared to the Koenigs-Knorr route. Given further savings for recycling, the direct O-glucosylation route provides an attractive alternative route for the synthesis ofthe target compound.
- Full Text:
- Date Issued: 2016
The development of a commercial production process for p-menthane-3,8-diol
- Authors: Rust, Nico
- Date: 2009
- Subjects: Insect pests -- Control , Repellents
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10427 , http://hdl.handle.net/10948/d1018273
- Description: The synthesis of p-menthane-3,8-diol via the acid-catalyzed cyclization of citronellal in a dilute aqueous sulphuric acid medium was investigated using conventional batch and continuous systems in order to develop a commercial production process for said p-menthane-3,8-diol (PMD). The batch studies conducted during the first part of this study showed that the formation of PMD from citronellal occurs via an intra-molecular Prins reaction that results in the formation of both the desired PMD product, as well as the partially hydrated isopulegol. It was shown that the formationof the by- product, PMD-acetal, results from the reaction between an intermediate, 5-methyl-2- isopropylcyclohexanol, and the citronellal starting material, and not from the reaction between PMD and citronellal as previously reported. Kinetic studies confirmed the existence of a complicated kinetic model. The formation of PMD from citronellal displayed typical pseudo first order kinetics up to conversions of 70 after which the kinetic model becomes complicated as the result of the establishment of quasi equilibrium reactions between PMD and isopulegol (dehydration of PMD and hydration of isopulegol) and between PMD the PMD-acetal, both systems being acid catalysed. The PMD-acetal formation reaction appears to be second order with respect to PMD. Scale-up studies of the batch process to 30L and 50L scales showed that it would be extremely difficult to limit the level of PMD-acetal formation below the desired level of 1 percent, even if citronellal conversions are restricted to about 50 percent. During studies conducted on a commercially availablemicro-structured organic synthesis plant (OSP) it was shown that it is possible to perform the PMD reaction as a continuous process. The results obtained showed that the use of a micro-mixer such as the caterpillar micro-mixer did not provide enough residence time in order for desirable conversions (- 40 percent) to be obtained. By combining themicro-mixer with delay-loops of different thicknesses and lengths, and using increasing reaction temperatures, it was shown that the conversion of citronellal could be improved to some extent, but compared poorly to the expected conversions for a well-stirred batch reactor. By packing selected delay loops with inert SiC particles, improved mass transfer was observed between the organic and aqueous phases as reflected in the increased conversion of citronellal. Using the observations that were made during the use of the OSP, a continuous-flow, tubular reactor system was designed and constructed. Advanced statistical techniques were used to investigate the effect of variables such as temperature, acid concentration, reactor length, flow rate and the organic to aqueous ratio on the rate and selectivity of the reaction. Mathematical models were derived for citronellal conversion, yield of PMD and yield of PMD- acetals, and used to predict the concentrations of citronellal, PMD and PMD-acetals at set experimental conditions. The results obtained showed that it was possible to obtain a product which approached desired specifications.Downstream processing of the PMD reaction mixture as it exits the reactor requires phase separation and neutralization of the acid catalyst solution, followed by further work-up to recover unreacted starting material and intermediates for recycle back to the synthesis reactor, followed by purification of crude PMD to the desired specification. The study showed that neutralization, prior or after phase separation, does not affect the selectivity of the PMD to such a great extent, but does influence the relative conversion due to extended contact of the catalyst with the organic phase after the reaction is terminated. Recovery of unreacted citronellal and isopulegol could be achieved by a simple vacuum evaporation step, which may either be carried out in a batch manner using traditional distillation equipment, or in a continuous process using wiped-film (short path) techniques. It was also shown that selective crystallization of PMD from the crude product mixture by addition of a solvent, such as heptanes or hexane proved to be the best way of achieving the desired product specification.
- Full Text:
- Date Issued: 2009
- Authors: Rust, Nico
- Date: 2009
- Subjects: Insect pests -- Control , Repellents
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10427 , http://hdl.handle.net/10948/d1018273
- Description: The synthesis of p-menthane-3,8-diol via the acid-catalyzed cyclization of citronellal in a dilute aqueous sulphuric acid medium was investigated using conventional batch and continuous systems in order to develop a commercial production process for said p-menthane-3,8-diol (PMD). The batch studies conducted during the first part of this study showed that the formation of PMD from citronellal occurs via an intra-molecular Prins reaction that results in the formation of both the desired PMD product, as well as the partially hydrated isopulegol. It was shown that the formationof the by- product, PMD-acetal, results from the reaction between an intermediate, 5-methyl-2- isopropylcyclohexanol, and the citronellal starting material, and not from the reaction between PMD and citronellal as previously reported. Kinetic studies confirmed the existence of a complicated kinetic model. The formation of PMD from citronellal displayed typical pseudo first order kinetics up to conversions of 70 after which the kinetic model becomes complicated as the result of the establishment of quasi equilibrium reactions between PMD and isopulegol (dehydration of PMD and hydration of isopulegol) and between PMD the PMD-acetal, both systems being acid catalysed. The PMD-acetal formation reaction appears to be second order with respect to PMD. Scale-up studies of the batch process to 30L and 50L scales showed that it would be extremely difficult to limit the level of PMD-acetal formation below the desired level of 1 percent, even if citronellal conversions are restricted to about 50 percent. During studies conducted on a commercially availablemicro-structured organic synthesis plant (OSP) it was shown that it is possible to perform the PMD reaction as a continuous process. The results obtained showed that the use of a micro-mixer such as the caterpillar micro-mixer did not provide enough residence time in order for desirable conversions (- 40 percent) to be obtained. By combining themicro-mixer with delay-loops of different thicknesses and lengths, and using increasing reaction temperatures, it was shown that the conversion of citronellal could be improved to some extent, but compared poorly to the expected conversions for a well-stirred batch reactor. By packing selected delay loops with inert SiC particles, improved mass transfer was observed between the organic and aqueous phases as reflected in the increased conversion of citronellal. Using the observations that were made during the use of the OSP, a continuous-flow, tubular reactor system was designed and constructed. Advanced statistical techniques were used to investigate the effect of variables such as temperature, acid concentration, reactor length, flow rate and the organic to aqueous ratio on the rate and selectivity of the reaction. Mathematical models were derived for citronellal conversion, yield of PMD and yield of PMD- acetals, and used to predict the concentrations of citronellal, PMD and PMD-acetals at set experimental conditions. The results obtained showed that it was possible to obtain a product which approached desired specifications.Downstream processing of the PMD reaction mixture as it exits the reactor requires phase separation and neutralization of the acid catalyst solution, followed by further work-up to recover unreacted starting material and intermediates for recycle back to the synthesis reactor, followed by purification of crude PMD to the desired specification. The study showed that neutralization, prior or after phase separation, does not affect the selectivity of the PMD to such a great extent, but does influence the relative conversion due to extended contact of the catalyst with the organic phase after the reaction is terminated. Recovery of unreacted citronellal and isopulegol could be achieved by a simple vacuum evaporation step, which may either be carried out in a batch manner using traditional distillation equipment, or in a continuous process using wiped-film (short path) techniques. It was also shown that selective crystallization of PMD from the crude product mixture by addition of a solvent, such as heptanes or hexane proved to be the best way of achieving the desired product specification.
- Full Text:
- Date Issued: 2009
The development of a framework to reduce water and energy consumption through the use of water and energy value stream mapping for the South African manufacturing industry
- Authors: Davies, Edward
- Date: 2015
- Subjects: Lean manufacturing -- South Africa , Stream mapping -- South Africa , Water consumption -- South Africa
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: http://hdl.handle.net/10948/4160 , vital:20564
- Description: The Republic of South Africa’s energy economy is under immense pressure and the main energy utility, Eskom, cannot reliably generate sufficient electrical energy to meet its customer demand. Water security in South Africa is also under threat as the country is currently amidst a water crisis. The South African manufacturing industry is the sector consuming the largest portion of the total energy consumption and second largest portion of the total water consumption (excluding urban use) nationally. Water and energy efficiency improvement is becoming imperative for organisational success as well as national economic sustainability. This is due to the significant increase in the cost of both electrical energy and water in recent years, and the drop in the reserve energy margin below the minimum level required for sustainable operation of energy utilities. The research objective therefore was to develop a Lean-based water and energy efficiency improvement framework for the manufacturing industry to encourage and realise a reduced demand for energy and water in it. A literature review was conducted on the water and energy landscape in South Africa, Lean manufacturing principles and their positive natural influence on water and energy efficiency, and the Value Stream Mapping tool. The survey of water and energy wastes in the manufacturing industry yielded the creation of standardised water and energy waste categories for use in conjunction with the conventional Lean wastes, tools and techniques. The literature survey indicated that the implementation of Lean manufacturing techniques naturally leads to the improvement of energy and water intensity. The researcher hypothesised that there is even greater potential for water and energy savings if a Lean-based tool is developed to specifically focus on the improvement of energy and water efficiency. A framework for this tool was developed through the literature survey. The tool is based on the Value Stream Mapping tool. A practical experiment was then conducted to establish the effectiveness of the tool in the South African manufacturing industry. The experiment design included an outline of the forecasting and statistical validation techniques to ensure the integrity of data utilised for approving or disproving the set hypotheses. The results of the practical experiment yielded positive results, confirming the hypothesis that the implementation of the developed framework will lead to improved energy and water efficiency in the manufacturing industry. After an explanation of the experimental results, the study concluded with recommendations and conclusions based on the findings.
- Full Text:
- Date Issued: 2015
- Authors: Davies, Edward
- Date: 2015
- Subjects: Lean manufacturing -- South Africa , Stream mapping -- South Africa , Water consumption -- South Africa
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: http://hdl.handle.net/10948/4160 , vital:20564
- Description: The Republic of South Africa’s energy economy is under immense pressure and the main energy utility, Eskom, cannot reliably generate sufficient electrical energy to meet its customer demand. Water security in South Africa is also under threat as the country is currently amidst a water crisis. The South African manufacturing industry is the sector consuming the largest portion of the total energy consumption and second largest portion of the total water consumption (excluding urban use) nationally. Water and energy efficiency improvement is becoming imperative for organisational success as well as national economic sustainability. This is due to the significant increase in the cost of both electrical energy and water in recent years, and the drop in the reserve energy margin below the minimum level required for sustainable operation of energy utilities. The research objective therefore was to develop a Lean-based water and energy efficiency improvement framework for the manufacturing industry to encourage and realise a reduced demand for energy and water in it. A literature review was conducted on the water and energy landscape in South Africa, Lean manufacturing principles and their positive natural influence on water and energy efficiency, and the Value Stream Mapping tool. The survey of water and energy wastes in the manufacturing industry yielded the creation of standardised water and energy waste categories for use in conjunction with the conventional Lean wastes, tools and techniques. The literature survey indicated that the implementation of Lean manufacturing techniques naturally leads to the improvement of energy and water intensity. The researcher hypothesised that there is even greater potential for water and energy savings if a Lean-based tool is developed to specifically focus on the improvement of energy and water efficiency. A framework for this tool was developed through the literature survey. The tool is based on the Value Stream Mapping tool. A practical experiment was then conducted to establish the effectiveness of the tool in the South African manufacturing industry. The experiment design included an outline of the forecasting and statistical validation techniques to ensure the integrity of data utilised for approving or disproving the set hypotheses. The results of the practical experiment yielded positive results, confirming the hypothesis that the implementation of the developed framework will lead to improved energy and water efficiency in the manufacturing industry. After an explanation of the experimental results, the study concluded with recommendations and conclusions based on the findings.
- Full Text:
- Date Issued: 2015
The development of a self-disintegrating core-body for use in an art bronze-casting foundry which employs the ceramic-shell investment technique
- Authors: Lomax, Lawrence Talbot
- Date: 2004
- Subjects: Sculpture -- Technique , Bronze founding , Precision casting , Shell molding (Founding)
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:8499 , http://hdl.handle.net/10948/219 , Sculpture -- Technique , Bronze founding , Precision casting , Shell molding (Founding)
- Description: The development of a disintegrating core-body for use in an art bronze foundry, which employs the ceramic shell investment process, begins with an investigation of four principal materials that will constitute the core formula. The specifications for the disintegration of the designed core-body formula fall within the parameters that are normally set and used in the ceramic shell art bronze casting process. The raison d’ être for the disintegrating formula is based on the premise that cement breaks down (spalling) after being subjected to heat above a certain temperature. It was shown that pure cement in the form of naked test bars 100 mm x 20 mm x 20 mm does indeed break down into separate pieces when fired to and above 9000C; where 9000C is the lowest recommended temperature required for sintering the ceramic shell investment mould. The addition of calcium carbonate to pure cement in the form of naked test bars, produced a more unified formula that did not break into separate pieces when fired to 9450C. However this combination of cement and calcium carbonate had a slow setting time of 12 hours and a shrinkage value of 2,3%, which were both above the parameters being sought for a quick-setting formula with a shrinkage value of below 1%. The combination of cement, plaster of paris and silica produced formulae that set within six hours and had shrinkage values of less than 1% but did not disintegrate within 72 hours. It was only after the addition of calcium carbonate to the these mixes that formulae resulted that set within six hours, had relatively low shrinkage values and showed signs of breaking up after 60 hours. It was further shown that by altering the ratios of cement, plaster of paris, calcium carbonate and silica, that the parameters for quick-setting formulae with shrinkage values of 1% and below, that also disintegrated within 55 hours, could be achieved. xvi It was also proved by subjecting these formulae to higher relative humidity conditions that the disintegrating times could be reduced and brought to below 48 hours. Selected formulae were then subjected to temperatures of between 9000C and 10000C. It was found that as the temperatures were increased so the disintegration times were reduced and were even further reduced under higher relative humidity conditions. It was found from the above experiments that the selected formula determined to be suitable in all respects as a disintegrating core-body was too difficult to remove from the hollow bronze cast when subjected to an actual bronze pour. Further experimentation using increased proportions of silica in the formula resulted in a final core-body that could be quickly and easily removed from its bronze cast as soon as the core-body had cooled to room temperature. The selected core-body formula (F21D) that was used in the final set of bronze casting procedures was found to function optimally when fired to a temperature of 9000C and could be quickly and easily removed from the bronze casts leaving a clean inner bronze surface, free from any remnants of the fired core. The document concludes by recording the delimitations and advantages of the final core-body formula F21D, as well as making recommendations based on these parameters for further study relating to disintegrating core-body formulations.
- Full Text:
- Date Issued: 2004
- Authors: Lomax, Lawrence Talbot
- Date: 2004
- Subjects: Sculpture -- Technique , Bronze founding , Precision casting , Shell molding (Founding)
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:8499 , http://hdl.handle.net/10948/219 , Sculpture -- Technique , Bronze founding , Precision casting , Shell molding (Founding)
- Description: The development of a disintegrating core-body for use in an art bronze foundry, which employs the ceramic shell investment process, begins with an investigation of four principal materials that will constitute the core formula. The specifications for the disintegration of the designed core-body formula fall within the parameters that are normally set and used in the ceramic shell art bronze casting process. The raison d’ être for the disintegrating formula is based on the premise that cement breaks down (spalling) after being subjected to heat above a certain temperature. It was shown that pure cement in the form of naked test bars 100 mm x 20 mm x 20 mm does indeed break down into separate pieces when fired to and above 9000C; where 9000C is the lowest recommended temperature required for sintering the ceramic shell investment mould. The addition of calcium carbonate to pure cement in the form of naked test bars, produced a more unified formula that did not break into separate pieces when fired to 9450C. However this combination of cement and calcium carbonate had a slow setting time of 12 hours and a shrinkage value of 2,3%, which were both above the parameters being sought for a quick-setting formula with a shrinkage value of below 1%. The combination of cement, plaster of paris and silica produced formulae that set within six hours and had shrinkage values of less than 1% but did not disintegrate within 72 hours. It was only after the addition of calcium carbonate to the these mixes that formulae resulted that set within six hours, had relatively low shrinkage values and showed signs of breaking up after 60 hours. It was further shown that by altering the ratios of cement, plaster of paris, calcium carbonate and silica, that the parameters for quick-setting formulae with shrinkage values of 1% and below, that also disintegrated within 55 hours, could be achieved. xvi It was also proved by subjecting these formulae to higher relative humidity conditions that the disintegrating times could be reduced and brought to below 48 hours. Selected formulae were then subjected to temperatures of between 9000C and 10000C. It was found that as the temperatures were increased so the disintegration times were reduced and were even further reduced under higher relative humidity conditions. It was found from the above experiments that the selected formula determined to be suitable in all respects as a disintegrating core-body was too difficult to remove from the hollow bronze cast when subjected to an actual bronze pour. Further experimentation using increased proportions of silica in the formula resulted in a final core-body that could be quickly and easily removed from its bronze cast as soon as the core-body had cooled to room temperature. The selected core-body formula (F21D) that was used in the final set of bronze casting procedures was found to function optimally when fired to a temperature of 9000C and could be quickly and easily removed from the bronze casts leaving a clean inner bronze surface, free from any remnants of the fired core. The document concludes by recording the delimitations and advantages of the final core-body formula F21D, as well as making recommendations based on these parameters for further study relating to disintegrating core-body formulations.
- Full Text:
- Date Issued: 2004
The development of an integrated value chain cost reduction methodology
- Welman, Abraham Jacobus Frederik
- Authors: Welman, Abraham Jacobus Frederik
- Date: 2013
- Subjects: Corporations -- Finance -- Management , Manufacturing industries -- Cost control , Industrial procurement
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:8775 , http://hdl.handle.net/10948/d1012954
- Description: The reason for the existence of any company is to make a profit, which means increasing turnover and keeping costs as low as possible. Optimisation of the Value Chain and Procurement were identified as the two largest contributors when one needs to improve the bottom line of any company. The purpose of this research was to develop an integrated Value Chain and Procurement cost reduction methodology and system specifications for a software solution which captures, tracks and accurately reports the impact of the improvement initiatives. The main research question was structured as follows: What should the specifications of a software solution be that will integrate the cost reduction processes of the Value Chain and of Procurement, in a manner that will ensure maximum sustainable bottom-line savings for companies in the manufacturing or service industries? The objective was to define the key phases in the Value Chain and Procurement cost reduction process and to determine how and where they integrate. It is important to note that according the literature review and the survey, both the Value Chain and Procurement cost reduction processes consist of seven phases. The phases of the Value Chain cost reduction process were: Phase 1: Budget/ABC costing and data analysis; Phase 2: Generate ideas; Phase 3: Evaluate and approve ideas; Phase 4: Implementation planning and approval; Phase 5: Development of project (idea) specific KPI's; Phase 6: Implementation of ideas; Phase 7: Track and report savings. The phases of the Procurement (Strategic Sourcing) cost reduction process were: Phase 1: Team selection/data collection/spend analysis/work plan development Phase 2: Access requirements/internal and external analysis; Phase 3: Develop strategy/shape value proposition; Phase 4: Screen suppliers, issue RFI/P/Q, implementation planning; Phase 5: Conduct commercial event/negotiate/finalise contract; Phase 6: Implement contract; Phase 7: Contract management/track and reporting. The above two cost reduction processes integrate at each phase of the respective processes and should thus be implemented at the same time due to their interdependencies. Based on the findings of the research it was clear that an integrated Value Chain and Procurement cost reduction process alone is not going to solve the cost reduction problems of companies. It is essential for the successful implementation of the integrated cost reduction process to develop skills and knowledgeable resources to implement the integrated cost reduction process, improve collaboration between the Value Chain and Procurement, and to implement a system to track and report performance during implementation. Further research should include how to adapt the current company processes, structures, procedures and systems in order to gain maximum benefit from the implementation of an integrated cost reduction process. The integrated Value Chain and Procurement cost reduction process, supported by a software system, should improve the success of cost reduction projects in companies. It is, however, important to note that the application of the methodology will vary between industries and that service-related industries might put more emphasis on Procurement cost reduction, while the manufacturing industries might place a bigger emphasis on cost reduction in operations. In conclusion, irrespective of the industries, it is evident that this methodology will enhance the cost reduction results previously obtained from similar efforts.
- Full Text:
- Date Issued: 2013
- Authors: Welman, Abraham Jacobus Frederik
- Date: 2013
- Subjects: Corporations -- Finance -- Management , Manufacturing industries -- Cost control , Industrial procurement
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:8775 , http://hdl.handle.net/10948/d1012954
- Description: The reason for the existence of any company is to make a profit, which means increasing turnover and keeping costs as low as possible. Optimisation of the Value Chain and Procurement were identified as the two largest contributors when one needs to improve the bottom line of any company. The purpose of this research was to develop an integrated Value Chain and Procurement cost reduction methodology and system specifications for a software solution which captures, tracks and accurately reports the impact of the improvement initiatives. The main research question was structured as follows: What should the specifications of a software solution be that will integrate the cost reduction processes of the Value Chain and of Procurement, in a manner that will ensure maximum sustainable bottom-line savings for companies in the manufacturing or service industries? The objective was to define the key phases in the Value Chain and Procurement cost reduction process and to determine how and where they integrate. It is important to note that according the literature review and the survey, both the Value Chain and Procurement cost reduction processes consist of seven phases. The phases of the Value Chain cost reduction process were: Phase 1: Budget/ABC costing and data analysis; Phase 2: Generate ideas; Phase 3: Evaluate and approve ideas; Phase 4: Implementation planning and approval; Phase 5: Development of project (idea) specific KPI's; Phase 6: Implementation of ideas; Phase 7: Track and report savings. The phases of the Procurement (Strategic Sourcing) cost reduction process were: Phase 1: Team selection/data collection/spend analysis/work plan development Phase 2: Access requirements/internal and external analysis; Phase 3: Develop strategy/shape value proposition; Phase 4: Screen suppliers, issue RFI/P/Q, implementation planning; Phase 5: Conduct commercial event/negotiate/finalise contract; Phase 6: Implement contract; Phase 7: Contract management/track and reporting. The above two cost reduction processes integrate at each phase of the respective processes and should thus be implemented at the same time due to their interdependencies. Based on the findings of the research it was clear that an integrated Value Chain and Procurement cost reduction process alone is not going to solve the cost reduction problems of companies. It is essential for the successful implementation of the integrated cost reduction process to develop skills and knowledgeable resources to implement the integrated cost reduction process, improve collaboration between the Value Chain and Procurement, and to implement a system to track and report performance during implementation. Further research should include how to adapt the current company processes, structures, procedures and systems in order to gain maximum benefit from the implementation of an integrated cost reduction process. The integrated Value Chain and Procurement cost reduction process, supported by a software system, should improve the success of cost reduction projects in companies. It is, however, important to note that the application of the methodology will vary between industries and that service-related industries might put more emphasis on Procurement cost reduction, while the manufacturing industries might place a bigger emphasis on cost reduction in operations. In conclusion, irrespective of the industries, it is evident that this methodology will enhance the cost reduction results previously obtained from similar efforts.
- Full Text:
- Date Issued: 2013
The development of best practice guidelines for the contingency management of health-related absenteeism in the motor manufacturing industry
- Authors: Werner, Amanda
- Date: 2005
- Subjects: Sick leave , Absenteeism (Labor) , Contingency theory (Management) , Automobile industry and trade -- South Africa
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9379 , http://hdl.handle.net/10948/160 , Sick leave , Absenteeism (Labor) , Contingency theory (Management) , Automobile industry and trade -- South Africa
- Description: The research problem in this study was to identify best practices for the contingency management of health-related absenteeism. To achieve this goal, the following actions were taken: A literature study was conducted to identify the scope and impact of health-related absenteeism on organisations and the legal parameters within which health-related absenteeism should be managed. A literature study was also conducted to identify strategies to prevent and reduce health-related absenteeism and strategies to ensure the continuous provision of products and services in periods of high absenteeism. The theoretical study focused on the management of absenteeism, wellness, ill-health/mental problems and HIV/AIDS, as well as contingency strategies aimed at maintaining production and service provision. iii The findings from the literature study were integrated into a model of best practices for the contingency management of health-related absenteeism. This model was used as a basis for the development of a survey questionnaire to determine whether senior human resources practitioners, occupational health practitioners or line managers, who were responsible for the management of health-related absenteeism in organisations, agreed with the best practice guidelines developed in the study. The survey was conducted in the motor and motor component industry in the Nelson Mandela Metropolitan Municipality and Buffalo City Metropole. The empirical results from the study showed a strong concurrence with the best practices guidelines developed in the study, with the exception of the strategies aimed at maintaining undisrupted production and service provision during periods of high absenteeism. In particular, disagreement was shown with regard to alternative work arrangements such as flexible work-hours, a compressed workweek, telecommuting and job-sharing. Absenteeism, in general, is an issue that organisations are challenged with on a daily basis. The proliferation of various diseases, specifically HIV/AIDS, is contributing to this problem. An integrated and strategic approach is required to deal effectively and constructively with the immediate and expected future impact of health-related issues on absenteeism. Organisations could use the best practices guidelines, identified in this study, as a mechanism to benchmark how well they manage health-related absenteeism
- Full Text:
- Date Issued: 2005
- Authors: Werner, Amanda
- Date: 2005
- Subjects: Sick leave , Absenteeism (Labor) , Contingency theory (Management) , Automobile industry and trade -- South Africa
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9379 , http://hdl.handle.net/10948/160 , Sick leave , Absenteeism (Labor) , Contingency theory (Management) , Automobile industry and trade -- South Africa
- Description: The research problem in this study was to identify best practices for the contingency management of health-related absenteeism. To achieve this goal, the following actions were taken: A literature study was conducted to identify the scope and impact of health-related absenteeism on organisations and the legal parameters within which health-related absenteeism should be managed. A literature study was also conducted to identify strategies to prevent and reduce health-related absenteeism and strategies to ensure the continuous provision of products and services in periods of high absenteeism. The theoretical study focused on the management of absenteeism, wellness, ill-health/mental problems and HIV/AIDS, as well as contingency strategies aimed at maintaining production and service provision. iii The findings from the literature study were integrated into a model of best practices for the contingency management of health-related absenteeism. This model was used as a basis for the development of a survey questionnaire to determine whether senior human resources practitioners, occupational health practitioners or line managers, who were responsible for the management of health-related absenteeism in organisations, agreed with the best practice guidelines developed in the study. The survey was conducted in the motor and motor component industry in the Nelson Mandela Metropolitan Municipality and Buffalo City Metropole. The empirical results from the study showed a strong concurrence with the best practices guidelines developed in the study, with the exception of the strategies aimed at maintaining undisrupted production and service provision during periods of high absenteeism. In particular, disagreement was shown with regard to alternative work arrangements such as flexible work-hours, a compressed workweek, telecommuting and job-sharing. Absenteeism, in general, is an issue that organisations are challenged with on a daily basis. The proliferation of various diseases, specifically HIV/AIDS, is contributing to this problem. An integrated and strategic approach is required to deal effectively and constructively with the immediate and expected future impact of health-related issues on absenteeism. Organisations could use the best practices guidelines, identified in this study, as a mechanism to benchmark how well they manage health-related absenteeism
- Full Text:
- Date Issued: 2005
The development of motivational strategies for public sector workers in Kenya
- Authors: Chepkilot, Ronald Kiprop
- Date: 2005
- Subjects: Public administration -- Kenya , Employee motivation , Civil service -- Kenya -- Personnel management
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9380 , http://hdl.handle.net/10948/161 , Public administration -- Kenya , Employee motivation , Civil service -- Kenya -- Personnel management
- Description: The purpose of this study was to develop motivational strategies for motivating public sector workers in Kenya. To achieve this objective the following procedure was followed: • An examination of the public service was undertaken and the following factors were considered: The history of the public service; Past government reform programmes; The problem of corruption; Future government reform programmes; and The motivational climate in the service. iv • A literature survey was conducted on the approaches used by organisations in motivating employees. The findings were used to develop a motivational strategy model. On the basis of the strategies in the model, a questionnaire was developed for the empirical research study. • The empirical study was undertaken to examine the level of motivation in the public service and to identify the motivational strategies currently used in the public service in Kenya. The study also sought to determine the extent to which public sector managers agreed or disagreed that the motivational strategies developed by the study would be effective in motivating employees in their organisations. The results of the empirical study were incorporated into the integrated motivational strategy model presented in chapter six. The study established that the level of motivation among the public sector workers was extremely low. According to the research findings, 87 per cent of the respondents indicated that the level of motivation of employees in their organisation was low while 13 per cent indicated that it was high. It was also established that the climate in the public service was not conducive for motivating employees: the indicators were lack of job security; very low salaries; limited training and development opportunities; lack of career development programmes and lack of adequate working tools and equipment. It was further established that the government could no longer afford to make any substantial increases in salaries to the workers because the wage bill was extremely high at the level of 9.6 per cent of the GDP. It was observed that any further increases in salaries would v have a negative impact on the economy of the country. In view of the above, this study becomes extremely relevant as it suggests ways of enhancing the levels of motivation in the public service to improve service delivery in the public sector without allocation of vast financial resources. The study strongly recommends the application of the integrated motivational strategy model in its entirety; to enhance the level of employee’s motivation and work performance and achieve efficiency and effectiveness in service delivery. The study also recommends that further research be carried out to determine the effects of corruption on employee motivation and ways of eliminating the vice in the public service.
- Full Text:
- Date Issued: 2005
- Authors: Chepkilot, Ronald Kiprop
- Date: 2005
- Subjects: Public administration -- Kenya , Employee motivation , Civil service -- Kenya -- Personnel management
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9380 , http://hdl.handle.net/10948/161 , Public administration -- Kenya , Employee motivation , Civil service -- Kenya -- Personnel management
- Description: The purpose of this study was to develop motivational strategies for motivating public sector workers in Kenya. To achieve this objective the following procedure was followed: • An examination of the public service was undertaken and the following factors were considered: The history of the public service; Past government reform programmes; The problem of corruption; Future government reform programmes; and The motivational climate in the service. iv • A literature survey was conducted on the approaches used by organisations in motivating employees. The findings were used to develop a motivational strategy model. On the basis of the strategies in the model, a questionnaire was developed for the empirical research study. • The empirical study was undertaken to examine the level of motivation in the public service and to identify the motivational strategies currently used in the public service in Kenya. The study also sought to determine the extent to which public sector managers agreed or disagreed that the motivational strategies developed by the study would be effective in motivating employees in their organisations. The results of the empirical study were incorporated into the integrated motivational strategy model presented in chapter six. The study established that the level of motivation among the public sector workers was extremely low. According to the research findings, 87 per cent of the respondents indicated that the level of motivation of employees in their organisation was low while 13 per cent indicated that it was high. It was also established that the climate in the public service was not conducive for motivating employees: the indicators were lack of job security; very low salaries; limited training and development opportunities; lack of career development programmes and lack of adequate working tools and equipment. It was further established that the government could no longer afford to make any substantial increases in salaries to the workers because the wage bill was extremely high at the level of 9.6 per cent of the GDP. It was observed that any further increases in salaries would v have a negative impact on the economy of the country. In view of the above, this study becomes extremely relevant as it suggests ways of enhancing the levels of motivation in the public service to improve service delivery in the public sector without allocation of vast financial resources. The study strongly recommends the application of the integrated motivational strategy model in its entirety; to enhance the level of employee’s motivation and work performance and achieve efficiency and effectiveness in service delivery. The study also recommends that further research be carried out to determine the effects of corruption on employee motivation and ways of eliminating the vice in the public service.
- Full Text:
- Date Issued: 2005
The oxidative coupling of phenols using stoichiometric metal oxidants
- Authors: Hoffmann, Eric
- Date: 2005
- Subjects: Phenols , Oxidation , Stoichiometry
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10977 , http://hdl.handle.net/10948/180 , Phenols , Oxidation , Stoichiometry
- Description: The oxidative coupling of 2,6-di-t-butylphenol under mild reaction conditions is well documented and the subject of many patents. However, the coupling of other monoand di- substituted phenols is not as well documented and thus there is scope for further investigation for providing a convenient, environmentally friendly and economically viable method for the oxidative coupling of these phenols. In this study, the oxidative coupling of a variety of alkylated phenolic substrates, 2-tbutylphenol, 2,6-di-t-butylphenol, 2,4 -di-t-butylphenol and ,4-dimethylphenol, using a range of different oxidizing agents, were investigated by means of experimental and/or theoretical means. The dibutylated aromatics provided the highest selectivities to their respective coupled products, with results obtained with the dimethyl analogue being only satisfactory, and that for 2 -t-butylphenol being totally inefficient. PM3 Molecular orbital (MO) calculations were used to predict the possible modes of coupling for the substrates 2,6 -di-t-butylphenol and 2,4-di-t-butylphenol, and these results were then compared with those obtained experimentally in the laboratory. Preliminarily, the coupling of unsubstituted phenolics was also assessed by means of MO calculations. Much emphasis was placed on Ce(IV) as the oxidant, and the reaction conditions under which it was used and the results that were obtained have not been reported before and are therefore novel. The oxidation of 2,4-di-t-butylphenol using Ce(IV) in the presence of methanesulphonic acid was optimized to afford high yields and selectivities to the desired ortho C-ortho C coupled product under mild reaction conditions. Various reaction parameters were also investigated in this case, such as varying the MeSO3H concentration, the solvent, the reaction temperature, the reaction time, the substrate loading, the rate of oxidant addition and the substrate to oxidant ratio. Ce(IV) also gave a high selectivity to the para C-para C coupled product when IX using 2,6-di-t-butylphenol as the substrate. However, it was not as effective with 2,4- dimethylphenol, and even less so with 2-t-butylphenol. The oxidation reactions of 2-t-butylphenol and 2,4-dimethylphenol with various coupling agents were also investigated with the intention of obtaining high selectivities to the respective desired coupled products. In these studies, 2-t-butylphenol afforded a large number of products, irrespective of the oxidant used. The dimethyl analogue was more selective, but results were not optimal. It was clear that the number of substituents on the phenol ring, their nature and their position with regards to the hydroxyl moiety was of great importance and made a significant impact on the preferred coupling mode of the substrate. It was observed that steric effects also played a major role in the outcome of these reactions: 2,6-di-t-butylphenol never afforded any C-O coupled products whereas 2-t-butylphenol, 2,4-di-t-butylphenol and 2,4-dimethylphenol all appeared to undergo some C-O coupling. Finally, reaction mechanisms were provided for both the K3Fe(CN)6 and Ce(IV) work, these reacting in basic and acidic media, respectively. It was proposed that both of these mechanisms operate through the initial formation of the phenoxyl radical.
- Full Text:
- Date Issued: 2005
- Authors: Hoffmann, Eric
- Date: 2005
- Subjects: Phenols , Oxidation , Stoichiometry
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10977 , http://hdl.handle.net/10948/180 , Phenols , Oxidation , Stoichiometry
- Description: The oxidative coupling of 2,6-di-t-butylphenol under mild reaction conditions is well documented and the subject of many patents. However, the coupling of other monoand di- substituted phenols is not as well documented and thus there is scope for further investigation for providing a convenient, environmentally friendly and economically viable method for the oxidative coupling of these phenols. In this study, the oxidative coupling of a variety of alkylated phenolic substrates, 2-tbutylphenol, 2,6-di-t-butylphenol, 2,4 -di-t-butylphenol and ,4-dimethylphenol, using a range of different oxidizing agents, were investigated by means of experimental and/or theoretical means. The dibutylated aromatics provided the highest selectivities to their respective coupled products, with results obtained with the dimethyl analogue being only satisfactory, and that for 2 -t-butylphenol being totally inefficient. PM3 Molecular orbital (MO) calculations were used to predict the possible modes of coupling for the substrates 2,6 -di-t-butylphenol and 2,4-di-t-butylphenol, and these results were then compared with those obtained experimentally in the laboratory. Preliminarily, the coupling of unsubstituted phenolics was also assessed by means of MO calculations. Much emphasis was placed on Ce(IV) as the oxidant, and the reaction conditions under which it was used and the results that were obtained have not been reported before and are therefore novel. The oxidation of 2,4-di-t-butylphenol using Ce(IV) in the presence of methanesulphonic acid was optimized to afford high yields and selectivities to the desired ortho C-ortho C coupled product under mild reaction conditions. Various reaction parameters were also investigated in this case, such as varying the MeSO3H concentration, the solvent, the reaction temperature, the reaction time, the substrate loading, the rate of oxidant addition and the substrate to oxidant ratio. Ce(IV) also gave a high selectivity to the para C-para C coupled product when IX using 2,6-di-t-butylphenol as the substrate. However, it was not as effective with 2,4- dimethylphenol, and even less so with 2-t-butylphenol. The oxidation reactions of 2-t-butylphenol and 2,4-dimethylphenol with various coupling agents were also investigated with the intention of obtaining high selectivities to the respective desired coupled products. In these studies, 2-t-butylphenol afforded a large number of products, irrespective of the oxidant used. The dimethyl analogue was more selective, but results were not optimal. It was clear that the number of substituents on the phenol ring, their nature and their position with regards to the hydroxyl moiety was of great importance and made a significant impact on the preferred coupling mode of the substrate. It was observed that steric effects also played a major role in the outcome of these reactions: 2,6-di-t-butylphenol never afforded any C-O coupled products whereas 2-t-butylphenol, 2,4-di-t-butylphenol and 2,4-dimethylphenol all appeared to undergo some C-O coupling. Finally, reaction mechanisms were provided for both the K3Fe(CN)6 and Ce(IV) work, these reacting in basic and acidic media, respectively. It was proposed that both of these mechanisms operate through the initial formation of the phenoxyl radical.
- Full Text:
- Date Issued: 2005
The selective dechlorination of poly-chlorophenols
- Authors: Thomas, Maxwell Paul
- Date: 2009
- Subjects: Sewage -- Purification -- Chlorination , Pesticides -- Toxicology , Chlorine -- Toxicology
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10391 , http://hdl.handle.net/10948/1124 , Sewage -- Purification -- Chlorination , Pesticides -- Toxicology , Chlorine -- Toxicology
- Description: Liquid phase catalytic hydrodechlorinations can provide a convenient and environmentally friendly method for treating organic chlorinated compounds in waste streams generated during the manufacturing of agrochemicals. During such treatment hydrochloric acid is generated as a by-product, which can be easily neutralized employing a base to yield an inorganic salt. This work describes the results obtained during the liquid phase hydrodechlorination of 2,6-dichlorophenol (2,6-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP). The hydrodechlorination of these chlorinated phenolic compounds in a mixture of methanol and water was investigated using supported and unsupported palladium catalysts to yield lower chlorinated phenols or phenol. Various parameters were investigated such as catalyst concentration, ammonium formate concentration, effect of base addition and effect of temperature. During this study two methods of hydrodechlorination were also investigated such as hydride-transfer hydrogenolysis, using ammonium formate, and hydrogenolysis, using dihydrogen. These methods offer a mild treatment in terms of the reaction temperature with temperatures used below 800C. A comparison of the palladium catalyst systems using these methods also showed that Pd/C produced the best results in terms of the hydrodechlorination rate and the selectivity towards phenol. When the ammonium formate method was used, complete hydrodechlorination of both substrates was achieved in 1h of reaction time at a selectivity of 100 percent towards phenol. A comparison of the method using dihydrogen and Pd/C showed that the reaction rate and the selectivity towards phenol during the hydrodechlorination of 2,6-DCP were 87.92 percent and 93.30 percent. Similarly, the reaction rate and selectivity during 2,4,6- TCP hydrodechlorination were 63.77 percent and 70.57 percent. These results were achieved in a reaction time of 3 hours. A high catalyst loading increases the reaction rate at the expense of selectivity, due to the formation of cyclohexanone, formed during further hydrogenation of phenol. The formation of cyclohexanone was limited at high temperatures (ca. 800C) with none detected during the hydrodechlorination of 2,6-DCP and 0.19 percent during the hydrodechlorination of 2,4,6-TCP. Evaluation of the hydrodechlorination parameters showed that the catalytic efficiency of the Pd/C catalysts was inhibited as the reaction proceeded due to the formation of HCl as by-product. A significant increase in the reaction rate was achieved when the reaction was performed in the presence of an inorganic base, which neutralized HCl.
- Full Text:
- Date Issued: 2009
- Authors: Thomas, Maxwell Paul
- Date: 2009
- Subjects: Sewage -- Purification -- Chlorination , Pesticides -- Toxicology , Chlorine -- Toxicology
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10391 , http://hdl.handle.net/10948/1124 , Sewage -- Purification -- Chlorination , Pesticides -- Toxicology , Chlorine -- Toxicology
- Description: Liquid phase catalytic hydrodechlorinations can provide a convenient and environmentally friendly method for treating organic chlorinated compounds in waste streams generated during the manufacturing of agrochemicals. During such treatment hydrochloric acid is generated as a by-product, which can be easily neutralized employing a base to yield an inorganic salt. This work describes the results obtained during the liquid phase hydrodechlorination of 2,6-dichlorophenol (2,6-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP). The hydrodechlorination of these chlorinated phenolic compounds in a mixture of methanol and water was investigated using supported and unsupported palladium catalysts to yield lower chlorinated phenols or phenol. Various parameters were investigated such as catalyst concentration, ammonium formate concentration, effect of base addition and effect of temperature. During this study two methods of hydrodechlorination were also investigated such as hydride-transfer hydrogenolysis, using ammonium formate, and hydrogenolysis, using dihydrogen. These methods offer a mild treatment in terms of the reaction temperature with temperatures used below 800C. A comparison of the palladium catalyst systems using these methods also showed that Pd/C produced the best results in terms of the hydrodechlorination rate and the selectivity towards phenol. When the ammonium formate method was used, complete hydrodechlorination of both substrates was achieved in 1h of reaction time at a selectivity of 100 percent towards phenol. A comparison of the method using dihydrogen and Pd/C showed that the reaction rate and the selectivity towards phenol during the hydrodechlorination of 2,6-DCP were 87.92 percent and 93.30 percent. Similarly, the reaction rate and selectivity during 2,4,6- TCP hydrodechlorination were 63.77 percent and 70.57 percent. These results were achieved in a reaction time of 3 hours. A high catalyst loading increases the reaction rate at the expense of selectivity, due to the formation of cyclohexanone, formed during further hydrogenation of phenol. The formation of cyclohexanone was limited at high temperatures (ca. 800C) with none detected during the hydrodechlorination of 2,6-DCP and 0.19 percent during the hydrodechlorination of 2,4,6-TCP. Evaluation of the hydrodechlorination parameters showed that the catalytic efficiency of the Pd/C catalysts was inhibited as the reaction proceeded due to the formation of HCl as by-product. A significant increase in the reaction rate was achieved when the reaction was performed in the presence of an inorganic base, which neutralized HCl.
- Full Text:
- Date Issued: 2009
Trust building strategies to enhance collective bargaining processes in organisations
- Authors: Ngalo, Osmond Tolo
- Date: 2011
- Subjects: Trust , Collective bargaining
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9398 , http://hdl.handle.net/10948/1312 , Trust , Collective bargaining
- Description: The main research problem in this study was to identify what trust-building strategies can be utilised by organisations to enhance collective bargaining processes. To achieve this objective a theoretical Institutional Arrangements-Based Model of trust-building was conceptualised, developed and presented in Chapter 5. The presentation of this model was the culmination of the research design phases outlined below: -The first phase consisted of a literature survey undertaken to discover the nature and dynamics of the concept "trust". -The second phase consisted of surveying the literature attempting to understand the nature of the collective bargaining process, its elements and types and the environmental factors that tend to impinge on it. -The final phase of the literature survey focused on various trust-building strategies, theories and models that can be utilised by organisations to ii enhance collective bargaining processes. Trust is generally acknowledged as a necessary requirement for effective and successful workplace relationships. Because of this factor it is crucial that South African employer-employee relationships are improved in a conscious and sustainable way in order for our businesses to remain competitive in the face of global competition. With this reality in mind there is still much in the South African labour relations environment that fosters conflict. One of the primary factors that impinge on trust in employer-employee relations in South Africa is the previous government‘s divisive and racist apartheid policies. These policies have resulted in serious structural imbalances in the economy, the skewed distribution of wealth and the general scarcity of resources to address these attendant challenges. Finnemore and van Rensburg (2002, p. 36) surveys the current labour relations scenario and comments about the extent to which it has been severely affected by apartheid. Some of its appalling outcomes are: racial divisions between skilled and unskilled workers, apartheid wage gaps, poorly educated workers, dictatorial management styles and a lack of protection for the most vulnerable workers. As revealed in this research study there are still widely divergent views at the workplace regarding the nature and levels of trust that are prevalent. The overwhelming view, however, is that there is, generally, a lack of trust between managerial and employee collective bargaining teams. This lack of trust which is evident between employer and employee parties will tend to result in collective bargaining processes being embarked upon in a climate imbued with the negative spirit of distrust. The recommended Institutional Arrangements-Based Model of trust-building advocates for a process of trust-building prior to any collective bargaining initiatives. This process, as depicted in the elements of the recommended model, needs to begin with phases which will focus on frame-alignment and the identification of all sources of distrust between the parties. These prescribed sessions seek to culminate in a common understanding, between the contesting parties, of their real divergent issues and concerns as well as their existing commonalities. The next phases of the recommended model entail the parties, jointly, developing proposals and policies that in the short and long term will aim at the resolution of the identified sources of distrust and thereby reduce the psychological distance between them. The final phase of the model entails the implementation of joint problem–solving resolutions and the development of appropriate policies i.e. institutional arrangements, to deal with all conflict-prone areas of the business operations. Simultaneously, there needs to be continuous evaluation and monitoring of organisational trust and the "agreed to" trust-building strategies to ensure that distrust is reduced or eliminated in the long term, allowing the organisation and the individual employees to perform at their optimum in order to achieve their common goals.
- Full Text:
- Date Issued: 2011
- Authors: Ngalo, Osmond Tolo
- Date: 2011
- Subjects: Trust , Collective bargaining
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9398 , http://hdl.handle.net/10948/1312 , Trust , Collective bargaining
- Description: The main research problem in this study was to identify what trust-building strategies can be utilised by organisations to enhance collective bargaining processes. To achieve this objective a theoretical Institutional Arrangements-Based Model of trust-building was conceptualised, developed and presented in Chapter 5. The presentation of this model was the culmination of the research design phases outlined below: -The first phase consisted of a literature survey undertaken to discover the nature and dynamics of the concept "trust". -The second phase consisted of surveying the literature attempting to understand the nature of the collective bargaining process, its elements and types and the environmental factors that tend to impinge on it. -The final phase of the literature survey focused on various trust-building strategies, theories and models that can be utilised by organisations to ii enhance collective bargaining processes. Trust is generally acknowledged as a necessary requirement for effective and successful workplace relationships. Because of this factor it is crucial that South African employer-employee relationships are improved in a conscious and sustainable way in order for our businesses to remain competitive in the face of global competition. With this reality in mind there is still much in the South African labour relations environment that fosters conflict. One of the primary factors that impinge on trust in employer-employee relations in South Africa is the previous government‘s divisive and racist apartheid policies. These policies have resulted in serious structural imbalances in the economy, the skewed distribution of wealth and the general scarcity of resources to address these attendant challenges. Finnemore and van Rensburg (2002, p. 36) surveys the current labour relations scenario and comments about the extent to which it has been severely affected by apartheid. Some of its appalling outcomes are: racial divisions between skilled and unskilled workers, apartheid wage gaps, poorly educated workers, dictatorial management styles and a lack of protection for the most vulnerable workers. As revealed in this research study there are still widely divergent views at the workplace regarding the nature and levels of trust that are prevalent. The overwhelming view, however, is that there is, generally, a lack of trust between managerial and employee collective bargaining teams. This lack of trust which is evident between employer and employee parties will tend to result in collective bargaining processes being embarked upon in a climate imbued with the negative spirit of distrust. The recommended Institutional Arrangements-Based Model of trust-building advocates for a process of trust-building prior to any collective bargaining initiatives. This process, as depicted in the elements of the recommended model, needs to begin with phases which will focus on frame-alignment and the identification of all sources of distrust between the parties. These prescribed sessions seek to culminate in a common understanding, between the contesting parties, of their real divergent issues and concerns as well as their existing commonalities. The next phases of the recommended model entail the parties, jointly, developing proposals and policies that in the short and long term will aim at the resolution of the identified sources of distrust and thereby reduce the psychological distance between them. The final phase of the model entails the implementation of joint problem–solving resolutions and the development of appropriate policies i.e. institutional arrangements, to deal with all conflict-prone areas of the business operations. Simultaneously, there needs to be continuous evaluation and monitoring of organisational trust and the "agreed to" trust-building strategies to ensure that distrust is reduced or eliminated in the long term, allowing the organisation and the individual employees to perform at their optimum in order to achieve their common goals.
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- Date Issued: 2011