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Optimization of A Real Time Multi Mixed Make-To-Order Assembly Line to Reduce Positive Drift
Get PDFThesisAssembly lines are critical for the realization of product manufacture. In recent times, there has been a shift from the make-to-stock (mass production) approach to a make-to-order (mass customization) approach and this has brought on a strong emphasis on product variety. Although variety can be included to a product at various phases of production, literature shows that by providing each functional module of the product with several variants, assembly lines provide the most cost-effective approach to achieve high product variety. However, there are certain challenges associated with using assembly lines to achieve product variety. One of these challenges is assembly line balancing. Assembly line balancing is the search for an optimum assignment of tasks, such that given precedence constraints according to pre-defined single or multi objective goal are met. These objectives include reducing the number of stations for a given cycle time or minimizing the cycle time for a given number of stations. Cycle time refers to the amount of time allotted to accomplish a certain process in an assembly process. This deviation from the optimal cycle time is technically referred to as drift. Drift can be negative or positive. Negative drift represents the time span during which an assembly line is idle, due to work being finished ahead of prescribed cycle time. Positive drift, meanwhile, represents time span in which an assembly line exceeds the prescribed cycle time. The problems caused by drift, especially positive drift, is so vast that there is a research niche are dedicated to this study called Assembly Line Balancing Problems. Various authors have proposed numerous solutions for solving assembly line balancing problems created by positive drift. However, there is very little information on optimizing multi model make-to order systems with real time inputs so as to reduce the effects of positive drift. This study looks at how such a system can be optimized by using the case study of a water bottling plant. This is done by initially looking at the literature in the field of assembly line balancing to isolate the research gap this study aims to fill. Secondly, the water bottling plant, described as the case study, is modelled using MATLAB/Simulink. Thirdly, the different optimization methodologies are discussed and applied to the created model. Finally, the optimized model is tested and the results are analysed. The results of this study show that positive drift, which can be a major challenge in a real time multi mixed assembly line, can be reduced by the optimization of assembly lines. The results of this study can also be seen as an addition to the knowledge base of the broader research on mixed model assembly line balancing
Evaluation Of Municipal Waste Services In Matjhabeng Local Municipality, Free State Province
Get PDFDissertationThe study evaluated the degree of effectiveness, efficiency, safety and sustainable solid waste management service delivery in the Matjhabeng Local Municipality and to recommend possible measures to improve the services delivered.
Six towns in the Matjhabeng Local Municipality were included in the study and English questionnaires were completed by 50 respondents in each town.
Results of the study indicated that no plastic bags or bins were provided for storage and sorting of waste generated by the residents. There was a lack of routine collection of waste and no communication with the residents with regards to solid waste occurred. It was observed that the majority of residents dumped their waste in open spaces and very few residents recycle and compost their waste and a need exists to educate the residents regarding the importance of recycling and composting waste.
The study indicated that the current solid waste management system in Matjhabeng Local Municipal area is not sustainable and it should be improved. It is recommended that adequate transport and collection of waste, improved communication with residents (meetings), promotion of reduction, reuse and recycling of waste be emphasized. Community based composting as well as municipal assistance being provided by the local municipalities with segregation and collection of waste, will lead to a more sustainable solid waste management system
Comparative Analysis Of Cytochrome P450 Monooxygenases Between The Genera Streptomyces And Mycobacterium
Get PDFThesisCytochrome P450 monooxygenases (CYPs/P450s) are found in all domains of life and are known for their catalytic versatility and stereo- and regio-specific activity. While the impact of lifestyle on P450 evolution has been reported in many eukaryotes, this remains to be addressed in bacteria. In this report, Streptomyces and Mycobacterium, belonging to the phylum Actinobacteria, were studied owing to their contrasting lifestyles and impact on human beings. Genome-wide data mining and annotation of P450s in 48 Streptomyces species revealed the presence of 1 625 P450s in their genomes. Of these 1 625 P450s, all had characteristic glutamic acid and cysteine at the EXXR and CXG motifs, respectively; however, 34 P450s lacked one or both P450 characteristic motifs, EXXR and CXG, owing to their short amino acid sequences and were thus regarded as fragment/pseudo-P450s. Comparison of P450s revealed that species belonging to the genera Streptomyces and Mycobacterium had almost the same patterns in terms of the average number of P450s in their genomes. All 1 625 P450 identified in 48 Streptomyces species were grouped into 144 P450 families and 377 P450 subfamilies. Among the families and subfamilies, 66 new P450 families and 144 new P450 subfamilies were identified in Streptomyces species. Analysis of P450 family conservation across 48 Streptomyces species revealed that among 144 P450 families identified, only two P450 families, the CYP107 and CYP157 P450 families, are conserved across all Streptomyces species. Comparative analysis of P450 family dynamics between the genera Streptomyces and Mycobacterium revealed the presence of the highest number of P450 families and P450 subfamilies in Streptomyces species. Streptomyces species have 144 P450 families and 377 P450 subfamilies, compared to 77 P450 families and 132 P450 subfamilies in mycobacterial species. Streptomyces species also have the highest number of new P450 families (66 families) and new P450 subfamilies (144 subfamilies) in their genomes compared to mycobacterial species. Interestingly, only two P450 families (CYP107 and CYP157) were conserved in Streptomyces compared to mycobacterial species where 10 P450 families, namely CYP51, CYP123, CYP125, CYP130, CYP135, CYP136, CYP138, CYP140, CYP144 and CYP1128, were conserved. Furthermore, P450 diversity percentage analysis between two genera revealed that Streptomyces species had almost double the P450 diversity percentage (0.18%) than mycobacterial species (0.07%). Comparative analysis of P450 profiles between the genera Streptomyces and Mycobacterium revealed that species belonging to these genera have different P450 profiles with few similarities. Despite both genera belonging to the same phylum, Actinobacteria, only 21 P450 families were found to be common and quite a large number of P450 families were found to be unique to Streptomyces (123 P450 families) and Mycobacterium (56 P450 families). In the 21 P450 families commonly found between the two genera, an interesting feature was observed in terms of the number of member P450s. A significant difference in the number of member P450s in the commonly shared P450 families was observed between Streptomyces and Mycobacterium. Differences were also observed in the number of dominant P450 families in the two genera. Only seven P450 families, namely CYP107, CYP105, CYP157, CYP154, CYP156, CYP147 and CYP183, contributed 62% of all P450s in Streptomyces species, whereas 15 P450 families, namely CYP125, CYP189, CYP150, CYP136, CYP135, CYP138, CYP140, CYP123, CYP143, CYP142, CYP144, CYP124, CYP108, CYP51 and CYP187, contributed 60% of all P450s in Mycobacterium. Furthermore, differences in P450 profiles between the two genera were observed in terms of type of dominant P450 families. A comparison of the dominant P450 families between the two genera revealed that none of the dominant P450 families was common between them. This strongly supports the concept that these Streptomyces P450s play a key role in the production of chemically diverse secondary metabolites, as a large number of P450 families were found in 48 Streptomyces species. P450 families, namely CYP105, CYP107, CYP161, and CYP183, which are highly populated in Streptomyces species compared to mycobacterial species, were found to be involved in secondary metabolite production. In contrast to the P450 families highly populated in Streptomyces species, P450 families that are highly populated in mycobacterial species, such as CYP125, CYP124, CYP108, CYP140 and CYP268, are involved in steroid (cholesterol) and hydrocarbon (lipids, alkenes, long chain acetate and ketone) hydroxylation, suggesting that these P450 families possibly help mycobacterial species to assimilate the host compounds.
It is clear that different lifestyles influenced the P450 profiles in Streptomyces and Mycobacterium, hence the differences observed between the two genera in terms of number of P450s, P450 family and subfamily diversity, dominant and unique P450 families types and differences in number of P450s in common P450 families. Furthermore, functional analysis of P450s suggests that in Streptomyces, P450s are destined for secondary metabolite production, whereas in Mycobacterium they are destined for utilisation of host lipids or synthesis of novel lipids. Based on the evidence presented in this study, the researcher hereby proposes that lifestyle or ecological niches play a key role in the evolution of P450 profiles in species belonging to the genera Streptomyces and Mycobacterium
Radiographic Image Recording Techniques When Using Computed Radiography Imaging Systems In The Eastern Cape Province
Get PDFIntroduction
Computed Radiography (CR) is currently the main leading digital radiography system
that was introduced to interchange from conventional film-screen radiography systems.
The key advantage of CR over film-screen radiography is the ability to perform postprocessing,
which allows image recording faults to be rectified. This, inevitably leads
one to inquire whether or not the required radiographic techniques are still being
employed prior to post-processing when CR systems are used.
Aim of the study
The aim of this study was to assess and possibly enhance image recording techniques
employed when using computed radiography imaging systems in private and
government hospitals in the Eastern Cape province, South Africa.
Methodology
A retrospective study design, using a self-designed checklist, was utilised to assess
the image recording techniques used by diagnostic radiographers when producing CR
images. The checklist consists of quantitative data with qualitative elements. Images
of the chest and abdomen were evaluated by the researcher and two other assessors.
The team assessed a total of 720 (PA/AP and LAT) chest and (erect and supine)
abdominal images individually, which were copied from the CR workstations for each
assessor.
The data were categorically captured by the researcher and analysed by the quality
assurance (QA) radiographer to ensure accuracy before sending the hard and soft
copies of the sample to the statistician. Thus, the data were also provided to the
statistician to verify the accuracy of the checklist results copied into an Excel
spreadsheet, through the use of a data theme analyses technique. The technique that
was used in the analysis was that of key-words-in-context. Descriptive data, namely
frequencies and percentages, were calculated for categorical data. Means and
standard deviations or medians and percentiles were calculated from the numerical
data obtained.
Results
Image recording techniques assessed with a consistently high level of accuracy were
‘part selection on CR workstations’, ‘gridline artefact’ exclusion and ‘CR scanner
malfunction’, which resulted in averages exceeding 95%. The results also indicated
that an unacceptably high number of chest and abdominal examinations that were
assessed had averages of non-optimal positioning: [chest (41%) and (abdomen 41%)],
non-anatomical markers: [chest (73%) and abdomen (59%)], and no collimation
applied: [chest (64%) and abdomen (72%)]. The most noticeable assessments relating
to artefacts were foreign objects on the patients manifesting in PA/AP chest (14%),
LAT chest (20%), erect abdominal (23%) and supine abdomen (13%) images. Radiographers measure their processed images through EI values, which were
assessed as either ‘over exposed’, ‘under exposed’ or ‘in range’. The EI results
indicated that the majority of PA/AP chest was ‘in range’ (43%), whereas LAT chest
was ‘under exposed’ (45%). Conversely, the abdominal images only showed
underexposure as an average of 15% (18% for erect and 11% for supine abdominal
images). It is striking to note that overexposure occurred in 52% of the abdominal
images compared to 15% overexposure in chest images. Observed with assessment,
histogram errors occurred in 7% LAT chest to 5% PA/AP chest, whereas erect and
supine abdominal images had equivalent average histogram errors of 3% (n=16) each.
Looking at the image quality assessment of all chest and abdominal images,
satisfactory results relating to distortion, noise level and the degree of sharpness
occurred. However, the study did identify that contrast and density technique image
quality falling below an acceptable ‘3’ qualifier value could be improved in both chest
and abdominal images assessed.
Conclusion and recommendations
All research questions and objectives of the study were addressed. This enabled the
researcher to conclude that the three key areas requiring attention were: (i)
radiographic practice, (ii) setting the exposure and (iii) avoiding artefacts through
practical techniques. Recommendations are made to address these findings. Four
sections, namely functional, technical, practical, and quality assurance
recommendations are proposed
Simultaneous Impact Of Juxtaposed Learning Theories On Learner Information Processing Ability For Cognitive Growth And Development
Get PDFThesisThe scientific knowledge base that undergirds and serves as a nexus to unravel the complexity of the ubiquitous but subtle factors to learn maximally is couched in the fields of educational psychology (specifically, cognitive psychology) and educational neuroscience. Within this ambit, the researcher sought to investigate the mental dynamics that are primary, draw, and necessitate attention prior to information becoming knowledge to learners in the classroom. Hence, the appropriate topic for the study as conceived by the researcher is, The simultaneous impact of juxtaposed learning theories on learner information processing ability for cognitive growth and development.
The dynamics of learning studied and explained in this study, align with the researcher’s inquisitiveness regarding “How best to teach learners, so that they can learn best.” Thus, the study appeals to teachers for the need to take recourse to the required considerations of juxtaposed learning theories in the classroom towards the enhancement of learners’ information processing abilities. The considerations are encapsulated in the qualitative behaviours of learner’s conscious awareness, cognitive engagement, and metacognitive engagement.
The study irradiated the research paradigm, research design, and the research survey method (sample, data collection, and data analysis) employed to answer the research questions and to statistically reject, or fail to accept, the stipulated hypotheses of the study. A questionnaire was designed as a research instrument to collect data. Furthermore, the validity and reliability tests, as well as tests for statistical assumptions were conducted. Inferential statistics were employed to test the Hierarchical Linear Model (HLM) hypotheses and the Structural Equation Model (SEM) hypotheses.
It is proper to conclude that from the researcher’s suggested model MEIPAC (Model to Engender Information Processing Ability in the Classroom), the variables germane to information processing by the learners, and the variables that undergird good and successful teachers in facilitating effective and efficient processing of information by learners, are paramount. The results, discussions, and recommendations of the study, therefore, attest to the latter, and the need for teachers to heed The simultaneous impact of juxtaposed learning theories on learner information processing ability for cognitive growth and development
Effects Of Defects On Mechanical Properties In Metal Additive Manufacturing: A Review Focusing On X-Ray Tomography Insights
Get PDFResearch ArticleX-ray tomography has emerged as a uniquely powerful and non-destructive tool to analyze defects in additive
manufacturing. Defects include unintended porosity, rough surfaces and deviations from design, which can
have different root causes and can vary significantly among samples. Powder material properties, non-uniform
delivery of the powder layer, deformation during manufacturing, deviations from optimal process-parameters
caused by changes in the laser beam, the optical components and the scanning system operation, may result in
lack of fusion pores, metallurgical pores, keyhole pores, etc. These different types of pores have different typical
sizes, shapes and 3D distributions. All types of defects have effects on the mechanical properties of a final part.
The use of X-ray tomography to visualize pores in parts (non-destructively) prior to mechanical testing has
allowed us to improve our understanding of the effect of this porosity on the mechanical properties of the part
(also referred to as “effect of defect”). This can provide the possibility to discriminate critical defects from harmless
ones, and thereby build confidence in additivemanufacturing processes. This paper reviews the current state
of knowledge with regard to the “effect of defect” in metal additivemanufacturing, and highlights some relevant
examples from our recent work
A Tourism Development Plan For The South African War Battlefields Route In The Central Karoo
Get PDFDissertationTourism development is an important imperative in the development of especially rural areas; hence the focus of the National Department of Tourism on developing areas with rich natural, cultural and historical resources. Considering the emphasis on the development of tourism in South Africa, it is important that tourism development plans be established for the different tourism sectors of South Africa.
Dark tourism, which involves travelling to places of war and destruction, is experiencing an increase in popularity worldwide. This also applies to South Africa. Battlefield tourism, as a component of dark tourism, offers tourists the opportunity to experience sites or destinations associated with war. The increased interest in the South African War (1899-1902), both nationally and internationally, provides numerous tourism development opportunity for local areas.
The most well-known battlefield route in South Africa is the KwaZulu-Natal Battlefields Route. Although there are numerous South African battlefield sites in the Karoo, no attempts have been made to develop a comprehensive battlefield route. Thus, the main objective of the investigation was to construct a tourism development plan for the South African War Battlefields Route in the central Karoo. The tourism development plan was informed by an empirical study conducted amongst various stakeholders on the proposed route. The main findings indicate a need for the development of the route and the establishment of a South African War Battlefields Route Destination Marketing Organisation (DMO)
Automated Soil Classification And Identification Using Machine Vision And Artificial Neural Networks
Get PDFDissertationIntroduction: In the construction industry, one of the major considerations when designing a superstructure is which foundation should be selected. Foundations provide support to superstructures by transferring the load of the structure evenly into the earth. An inappropriate foundation choice could result in damage to the superstructure, or even the collapse of such a structure. The clay content of soil is a major determining factor when selecting a foundation type. Soil containing clay, has the potential to shrink and swell as the water content changes. This heaving of the soil can cause damage to the superstructure built upon it. Determining the amount of clay in a soil sample, is one of the most important steps in the soil classification process. In South Africa, the Hydrometer method is commonly used to determine the clay content of soil samples. This method is a manual, time intensive soil classification method, with doubtful accuracy. This study was undertaken to develop an Automated Soil Classification System (ASCS) that will classify soil more accurately and more expeditiously, making it cost and time effective. This was achieved by applying a Machine Vision (MV) process to soil samples, to generate unique digital soil sample fingerprints for soil samples. This process was then combined with an Artificial Neural Network (ANN), to automatically classify the soil sample from the fingerprints.
Methods: Initially a Machine Vision Instrument (MVI) was constructed for the consistent capturing of high fidelity images during the sedimentation process of a soil sample. Software was then developed to process these captured images and generate unique Soil Sample (SS) fingerprints for different soil constitutions. Four investigations were preformed to validate the consistency of the SS fingerprints generated with the MVI. These investigations were: 1. Validation of the SS fingerprint generation process; 2. Validation of the soil sample preparation procedure; 3. Determination of the differentiation ability of the MVI; and 4. Validation of the MVI by generating SS fingerprints for coded (unknown) soil samples. The generated SS fingerprints were then used to train an ANN to recognise and classify soil samples from their respective SS fingerprints. After the training of the ANN, a fifth investigation was undertaken determine the accuracy of the trained ANN and a final, sixth investigation was undertaken to compare the performance of the ASCS to that of the Hydrometer method.
Results: The constructed MVI was able to acquire good quality greyscale images during the sedimentation process of soil samples in a consistent manner. Investigations 1 through 4 showed that correlation amongst SS fingerprints, generated from the same soil sample, was in the order of 97%, while the correlation amongst SS fingerprints, generated from multiple soils samples of the same constitution, was in the order of 95%. Investigation five showed that the training of the ANN was successful as the R values obtained after training were greater than 0,98. The sixth and final investigation showed that the accuracy of the ASCS was in the range of 95% and greatly outperformed the Hydrometer method, who’s accuracy varied from approximately 49 to 89%. The ASCS also delivered these results in 28 hours while the Hydrometer method took approximately seven days
Environmental Factors, Employee-Resourcing Strategies And Performance Of Small Restaurant Businesses In South Africa: A Structural Equation Modelling Approach
Get PDFSmall restaurant business sector is applauded for promoting economic growth and employment creation in developing economies. Despite the spirited efforts by developing nations to capacitate the sector to sustainably contribute to economic growth, it is often marred by a disturbing high failure rate, especially in South Africa. The failure rates have been attributed, among many other factors, to the inability of the small restaurant businesses to respond to the environmental uncertainty for increased performance. In addition, small restaurant businesses in developing economies have been found to share common characteristics with small businesses in other sectors, in terms of using ad hoc approaches to employee – resourcing. Yet, the adoption of proper employee-resourcing strategies such as doing workforce planning, formalising recruitment and staff retention are regarded as best human resource practices for optimum business performance. In addition, the contribution of environmental factors such as manager‘s expertise and experience, economic growth, and political stability in leveraging the adoption of effective employee-resourcing strategies and heightening business performance has been reported. There is however a dearth of research that explores the interplay of environmental influences, employee-resourcing strategies and performance of small businesses in a developing context. There is also a paucity of literature that explores whether a convivial relationship exists among environmental factors, employee-resourcing strategies and business performance among in South Africa. Furthermore, empirical evidence on the influence of employee-resourcing strategies on small business performance in the hospitality industry among emerging economies is disappointingly low.
It is against this background that this research used the Resource Based View (RBV), the Human Capital Theory, the Flexible Firm Model, Contingency theory and reviewed literature to gain an understanding on whether the internal and external environmental factors inform the adoption of employee-resourcing strategies, culminating in increased business performance. Using Structural Equation Modelling (SEM), the research proposes that the pathway to improved business performance demands small restaurant business owner-managers to adopt systemic and holistic approaches to employee-resourcing strategies that are attuned to the internal and external environmental factors to guarantee increased business performance.
The research was informed by the positivist paradigm and a quantitative research approach was adopted to test the proposed conceptual model. A structured questionnaire was administered to 221 owners/managers of small restaurant businesses in Free State Province, South Africa. Convenience sampling was employed to select the respondents. SEM was used to empirically test the hypothesised relationships in the conceptual model. The results showed that the structural model fitted the data satisfactorily and provided reasonable explanations on the nature of relationships among internal and external environmental factors, employee-resourcing strategies and small business performance in South African restaurants. The results established a positive and significant effect of the internal environmental factors on employee-resourcing strategies. Furthermore, the results also revealed a positive and significant effect of the external environment on employee-resourcing strategies. However, contrary to predictions, there were no relationships between internal and external environmental factors, employee-resourcing strategies and small restaurant performanc
Intelligent Single Worker Utilization For Component Retrieval For Multiple Stationary Assembly Lines
Get PDFSince the late 90s, the manufacturing industries have considerably evolved. Industries are more frequently making use of automated systems to improve their productivity, reduce the assembling time, and to be more competitive. This has led to an ever- increasing necessity for the implementation of automated manufacturing system capable of effectively handling all the required manufacturing processes.
This study aims to develop an automated manufacturing system that will be easy to manage, maintain, and capable of efficiently using the resources to complete the required manufacturing tasks. This experimental system consists of two assembly lines, an AGV, and a storeroom. These parts have been developed as autonomous system that collaborate with one another over a network link.
The assembly lines use a programmed algorithm that help them share information about each task performed, negotiate on the usage of the autonomous guided vehicle (AGV) and storeroom, and backup each other’s data. Each task performed by the assembly line is a time-based simulation of the assembling process of the four parts required from the storeroom. An AGV is used by the assembly line to collect parts from the storeroom. It follows a black line on a white surface connecting the storeroom to the assembly lines by using digital sensors. The storeroom uses an RFID system to store and retrieve parts according to the request placed by the assembly lines.
The final results obtained show that the project’s main objectives to create a resource sharing algorithm in a manufacturing system with autonomous assembly lines, AGV, and storeroom, capable of negotiating and sharing information were successfully achieved