The diploma thesis deals with problems of drop forging. A detailed literary study is prepared in this work, in which there are data for working out the specified component – mudguard holder. There are options for cutting the semi-product, types of lubricants, construction of ideal preform or different kinds of forging machines for drop forging. The next part of this thesis is about technology of drop forging on crank forging presses. This section is aimed on technical drawing of the forging and its classification by the complexity of the shape. Furthermore, the thesis deals with the economic part, setting out the individual costs of the production from which the cost price of a forging is determined.

The thesis is focused on making the most efficient actuator shaft, using machinery company. Using Fanuc's control system on all machines with examples of their use in practice. Production and integration of a special holder for the drill stage.

The holder of outdoor air-conditioning units are made out of steel 11 321.21 with 2mm thickness. The production quantity is 2000 units / year. The holder is produced using CNC machine for cutting and bending on CNC press brake. The semi-finished product is a metal sheet (2 x 2000 x 1000 mm). Part of this diploma thesis is to design of the population with the punching tools, the layout of parts on the metal sheet and design of appropriate press brake punches and dies. The conclusion contains economic evaluation of the proposed solution.

This diploma thesis “Tubular Skid Holder of Skoda Fabia Super 2000 Rally Car” is aimed to engineering design of tubular skid holder of rally car Skoda Fabia Super 2000. There is used FEM software for analysis s evaluation of current variant and following variants of engineering design. The most relevant final variant design, which is consistent with asked stiffness and reduction of weight, was chosen based on findings.

This diploma work is engaged in the issue of the life assurance. It includes the proposal of the product from the life assurance branch for the start of the chosen business subjekt that the best corresponds with the dedicated requirements.

Thesis (M. A. Agricultural Science (Agricultural Economics)) -- University of Limpopo, 2021 / Maize seeds differ according to varieties. The traditional maize varieties(also referred to as (Landraces)are maize varieties that have been cultivated and subjected to selection by farmers for generations. They retain a distinct identity and lack formal crop improvement. Improved maize varieties, on the other hand, are bred with characteristics such as drought and disease tolerance. This research was conducted to determine the attributes preferred by farmers when making a maize varietal choice. To be specific, the study aimed to achieve the following objectives:(i) Identify and describe socio economic characteristics of smallholder maizefarmers’ in Mogalakwena Municipality;(ii) Analyse socioeconomic characteristics of smallholder maize farmers in Mogalakwena Municipality;(iii)Identify different maize varieties grown by smallholder farmers in Mogalakwena Municipality, and (iv) determine and analyse factors influencing farmers’ choice of a maize variety. Descriptive statistics and the Multinomial Logistic Regression Mode lwere used for data analysis. The results of the study revealed that 64% of the respondents had formal education. This meant that they have the capability to grasp more information, if provided witht rainings. It was found that 75% of the farmers did not have access to extension service which is supposed to play a significant role in agricultural information dissemination. The most grown maize variety was landrace varieties which constituted 59.5%. This percentage was said to be resultant from limited access to the seed market. Infact, 80% of the farmers had to travel an average o f42 kilomteres to access the market which also had a limited number of varieties. The Multinomial Logistic Regression Model revealed that only 5variables (Educational level, farm size, yield, extension contact and knowledge of maize varieties) were significant at 1%, 5%,1 %,1% and1%, respectively. The majority of farmers were old people with little access to extension service andaninad equate farming knowledge which lead to a high percentage of farmers continuing to grow landrace varieties. Based on thef indings, this study recommend further research on attributes that influence farmers varietal choice and Government intervention in provision for resources and development of existing and new infracstrcture to encourage extension service delivery Keywords: Landrace, improve maize variety, smallholder farmer

No description available.

Thesis (Ph.D. (Geography)) -- University of Limpopo, 2020 / Agriculture in South Africa, particularly in the summer rainfall areas, faces the challenge of optimal crop production in the face of climate change. Climate change scenarios for South Africa have been predicted to have a negative impact on agriculture particularly in the summer rainfall areas because of its dependence on climate variables. Within the context of the South African agricultural sector, it has become important to identify who and what is most vulnerable to impacts of climate change, so that support for adaptation can be targeted appropriately. The aim of this study was to assess the hazard of climate change in relation to the production of selected dryland crops, namely: sunflower, soybean, and groundnut in the summer rainfall areas and to model their vulnerability and response to climate change as well as to develop coping and adaptation strategies. A survey of 800 farmers was carried out in three agro-ecological zones of Limpopo and Free State. The population was purposively selected and were present for focus group discussions and questionnaire administration. Questions on agronomic practices, cost of production, climate change impact on productivity, coping and adaptation methods used in the face of climate change were asked. The response showed that farm production was not at the optimum, not only because of the influence of climate but as a result of the poor agronomic practices by the farmers. Following a factor analysis, 70% of the decline in crop yield was attributed to poor farming decisions. A further look at climatic factors affecting farmers indicated that frost with a 0.989 loading was the most climate extreme affecting most of the farmers. In order to buffer the effects of climate change, the farmers undertook various changes in their farm management and also received some support from the various governmental and non-governmental institutions. It was however, found that though there were policies in place for farmer support, such supports were not administered in a timely fashion and some support types were not adequate for the farmers. A correlation between the number of supports received and yields showed an increase in yield for farmers who received more than one type of support and with such variations evident across the agroecological zones. Physical modelling was conducted to model crop suitability based on downscaled data from the Special Report on Emissions Scenarios A2, (SRES A2) for the time periods centred on 2020, 2050 and 2080. The results showed areas which were not suitable for either soybean, sunflower or groundnut production in the future over time with some areas gaining and losing under different farm input regimes. To establish the effects of climate change on yield, a field experiment was carried out for two consecutive seasons and the results obtained were used to feed the AquaCrop crop simulation model to model the effects of climate change on yield under different management conditions.The results obtained from the survey, field experiments and climate indices guided the development of vulnerability indicators in a spatial manner. Using the socioeconomic and biophysical results, the vulnerability of the summer rainfall area was calculated. The results showed that areas in Limpopo, North West, Eastern Cape, and Northern Cape were the most vulnerable. Based on the types of adaptation options employed by farmers which included a change in planting dates, employing support from institutions, other sources of income, farming practices and recommendations for future adaptation, various scenarios were run in a crop simulation model to determine the cropping regimes suitable for the study area. Options included technology, on-farm management, out of farm management, human and social factors. The results indicated that coping and adaptation measures are place specific and the effects of a climate extreme are felt differently by different farming communities and farmers in the same community. It is hence recommended that the government in its policies towards alleviating the risk of farmers to climate change should look at site-specific options and not a one model fits all. Farmers should also play a role in enhancing their adaptive capacity as well. It is only when barriers are bridged and a proper network of communication established alongside resource provision, will there be a change in farmer’s attitude toward implementing suggested adaptation options. / University of Limpopo VLIR-IUC

The central aim of this thesis is to give further insights into the structural properties of the calcite(104) surface and especially to unravel its surface reconstruction by clarifying the contradicting reports of the (2 × 1) and row-pairing reconstruction. Within this thesis, the pristine as well as the CO and H2O-covered calcite(104) surface is investigated for the first time with non-contact atomic force microscopy (NC-AFM) operated at 5 K. CO terminated tips are used in the measurements to benefit from the improved contrast capabilities and detailed understanding of contrast formation with these tips.

Thesis (MScEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: In this study, commercially pure titanium foam was produced using space holder powder metallurgy techniques. Titanium foam is attractive as a scaffolding material for bone replacement and implants in the body. The porous morphology of the foam promotes osteogenesis, while the mechanical behaviour of the foam is closer to that of bone, which has an elastic moduli range of 5 - 40 GPa. Titanium foam was manufactured from powder mixtures of commercially pure titanium (CPTi) powder mixed with 41.4 wt% ammonium bicarbonate (ABC) powder and 1.45 wt% polyethyl glycol (PEG) powder. In this study, two CPTi powders with different particle size distributions, < 75 μm (-200 mesh, designated TiAA) and < 200 μm (-100 mesh, designated TiG), were mixed with the space holder ABC powder, that had been sieved into specified particle size ranges. The size ranges of space holder material studied were: 0 - 710, 250 - 425, 425 - 560, and 560 - 710 μm. This allowed foams with different large or macropore distributions to be produced from the different mixtures. The mixtures were uniaxially compacted at 100 MPa into transverse rupture bars. The ABC and PEG was then removed by thermal debinding in air for 5 hours at 100 °C and 1 hour at 330 °C each, consecutively. The debound samples are then sintered under high (10-6 mbar) vacuum on yttria-stabilised zirconia substrates, heating at 5 °C/min to 1200 °C, with a 2 hour hold at temperature. The microstructures of the different foams were evaluated by examining the polished samples using light optical microscopy. Three point bend tests were conducted on the sintered bars in order to determine the flexural strength and flexural modulus of the different foams. The produced foams had a relative density range between 37.5 - 62.5 % and average macro pore size range between 300 - 500 μm. The foams were found to have an elastic modulus similar to that of bone, 2 - 7 GPa. Finally, the mechanical properties of the foams were compared to known open foam mechanical models and other research projects. It was found that: (i) changes in either metal or space holder powder influences the sintering behaviour of metal foams, (ii) sintered titanium foams with similar densities but different macro/micropore size distributions have different mechanical responses to stress and (iii) the Ashby-Gibson model, based on foam density alone, gives a rough estimate of mechanical properties for the titanium foams studied, but does not capture variations due to pore size distribution. / AFRIKAANSE OPSOMMING: In hierdie studie is kommersiële suiwer titaanskuim geproduseer met behulp van ruimtehouer poeier metallurgie tegnieke. Titaanskuim is aantreklik as 'n raamwerkmateriaal vir beenvervanging en -inplantings in die liggaam. Die poreuse morfologie van die skuim bevorder osteogenese, terwyl die meganiese gedrag van die skuim naby aan dié van been is, met ‘n elasticiteitsmodulus tussen 5 - 40 GPa. Titaanskuim is vervaardig van ‘n poeier mengsel van kommersiële suiwer titaan (CPTi) poeier gemeng met 41,4 gew% ammonium bikarbonaat (ABC) poeier en 1.45 gew% poli-etileenglikol (PEG) poeier. In hierdie studie is twee tipes CPTi poeiers met verskillende deeltjiegrootteverspreiding, < 75 μm (-200 stofdigtheid, TiAA genoem) en <200 μm (-100 stofdigtheid, TiG genoem), met die ruimtehouer ABC-poeier, wat in bepaalde deeltjiegroottereekse gesif is, gemeng. Die wisselende groottes van ruimtehouer wat bestudeer is, was: 0 - 710, 250 - 425, 425 - 560, 560 - 710 μm. Dit het die vervaardiging van skuim met verskillende groot of macroporeuse vanaf die verskillende mengsels toegelaat. Die mengsel is teen 100 MPa in een rigting gekompakteer. Die ABC en PEG is dan verwyder word deur termiese ontbinding in lug vir 5 uur by 100 °C en 1 uur by 330 °C elk, onderskeidelik. Die ontbinde monsters is dan onder hoë (10-6 mbar) leemte op yttrium-gestabiliseer zirconia-substraat, met verwarming teen 5 °C/min tot 1200 °C met 'n verdere 2 uur by 1200 °C, gesinterd. Die mikrostrukture van die verskillende skuim is geëvalueer deur gepoleerde monsters met behulp van ‘n ligmikroskopie te ondersoek . Driepunt draaitoetse is op die gesinterd stawe uitgevoer om die buigsterkte en buigmodulus van die verskillende skuime te bepaal. Die vervaardigde skuime se relatiewe digtheid het tussen 37,5 - 62,5 % gewissel en die gemiddelde makroporiegrootte tussen 300 - 500 μm gewissel. Die skuim het 'n elastisiteitsmodulus soortgelyk aan dié van been getoon, 2 – 7 GPa. Ten slotte is die meganiese eienskappe van die skuim met bekende oop skuim meganiese modelle en ander navorsingsprojekte vergelyk. Daar is bevind dat: (i) veranderinge in óf metaal of ruimtehouer poeier beïnvloed die sinteringgedrag van metaalskuime, (ii) gesinterd titaniumskuim met soortgelyke digthede, maar verskillende makro / mikroporeuse verdelings, toon verskillende meganiese reaksies op stres en die Ashby-Gibson model, gebaseer op die skuimdigtheid alleen, (iii) wat 'n rowwe skatting van die meganiese eienskappe vir die bestudeerde titaniumskuime gee, maar nie die variasies ingrootteverspreiding van porieë ondervang nie.