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Search Results: 1 - 10 of 553506 matches for " A.B. Fourie "
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J. Sevitz,A.C. Brent,A.B. Fourie
South African Journal of Industrial Engineering , 2012,
Abstract: ENGLISH ABSTRACT: The conventional consumer carrier bags have recently received considerable attention in South Africa. The choice of material for these bags, based on environmental preferences in the South African context, could significantly influence the local manufacturing industry. Life Cycle Assessment (LCA), an environmental management tool, has been applied to objectively evaluate and compare the overall environmental impacts of the complete life cycles (from raw material extraction to final disposal) of consumer plastic and paper carrier bags in South Africa. Paper bags have a higher carrying capacity compared to plastic bags and different use ratios were subsequently evaluated. Plastic bags have a lower environmental impact for use ratios of up to 2.5 plastic bags to one paper bag. Above this ratio the conclusions are not reliable. Paper bags would need to increase its recycled content significantly to be competitive in terms of environmental impacts. The re-use of thicker plastic, as proposed by the new plastic bag legislation, has the potential to significantly lower the impact of plastic bags. AFRIKAANSE OPSOMMING: Die konvensionele gebruikersdrasakke het onlangs aansienlike aandag in Suid Afrika ontvang. Die keuse van materiaal vir hierdie sakke, wat gebaseer is op omgewingsvoorkeure in die Suid-Afrikaanse konteks, kan 'n wesenlike invloed uitoefen op die plaaslike vervaardigingsindustrie. Lewenssiklusanalise (LCA), 'n omgewingsbestuurgereedskap, is aangewend vir 'n objektiewe evaluasie en vergelyking van die algehele omgewingsimpakte van die totale lewenssiklus (vanaf grondstofekstraksie tot finale wegdoening) van gebruikersplastiek- en papierdrasakke in Suid-Afrika. Aangesien papiersakke 'n ho r drakapasiteit het in vergelyking met plastieksakke, is verskillende gebruiksverhoudings evalueer. Plastieksakke het 'n laer omgewingsimpak vir gebruiksverhoudings tot en met 2.5 plastieksakke vir elke papiersak. Die gevolgtrekkings van die studie is nie betroubaar vir ho r verhoudings nie. Die persentasie hergesirkuleerde materiaal in papiersakke moet verhoog word om mededingend te wees in terme van omgewingsimpak. Die hergebruik van dikker plastiek, soos voorgestel deur die nuwe plastieksakwetgewing, het die potensiaal om die algehele impak van plastieksakke wesenlik te verlaag.
Employee`s Perception of Women Leaders in Nigeria Private and Public Organisation
A.B. Owolabi
The Social Sciences , 2013,
Abstract: Despite the constraints and the negative worldview about women, the world today is witnessing an upsurge of feminine power, influence and productivity. Significant changes have therefore occurred in gender-role and gender based division of labour. This paper examined employees` perception of women leaders in Nigeria private and public organizations. A total of two hundred and fifty participants were used for the study (125 workers from public and 125 workers from private sector). An attitude towards women leader scale was administered into them and scores were analysed using the independent t-test and 2 2 Analysis of variance. Results show that there are negative attitude towards women leaders but there are no significant difference in the attitude of private and public employees towards women leaders. Sex and marital status also predict employees` attitude towards female leaders, with males and married people having a favourable attitude towards women leaders. Findings were discussed in the light of previous findings in the literature
High trypanosome infections in Glossina palpalis palpalis Robineau-Desvoidy 1830 in southern Kaduna state, Nigeria
A.B Ahmed
Science World Journal , 2007,
Abstract: A survey was undertaken to determine the prevalence of trypanosome infection in Glossina species in Kaura Local Government Area (LGA) of Kaduna State, Southern Guinea Savanna, Nigeria, aimed at identifying areas to be prioritized for area-wide tsetse eradication. The flies were trapped from a relic forest and also from 22 locations spread within the LGA and dissected to determine infection rates and infection types. Glossina palpalis palpalis Robineau-Desvoidy 1830 was the only tsetse species encountered both within the relic forest and the 22 locations sampled; its distribution was strictly riverine. Out of the 409 non-teneral flies dissected in the relic forest, 18.1 ± 0.02%, were infected with trypanosomes, with infections of the vivax-group dominating (76.92%) over the congolensegroup (23.01%). Of the 690 flies caught from 22 locations, 9.9 ± 1.0% were infected, 69.12% with vivax-group and 30.88% with congolense-group. Infections of the brucei-group were not encountered throughout the investigation period. The high prevalent figure of 12.64% recorded in the flies from both the relic forest and other locations portray the area as highly risky, with Bondong, Manchok and Kadarko districts being highly endemic, followed by a region of medium prevalence at Kukum district and a region of low endemicity within the mountain ranges of Zankan district. A well articulated vector eradication programme that will target G. p. palpalis and the various species of other biting dipterans is recommended as the solution to the recurring nagana problem in the area.
Breeding of the Hooded Vulture Necrosyrtes monachus in the Kruger National Park
A.B Daneel
Koedoe : African Protected Area Conservation and Science , 1984, DOI: 10.4102/koedoe.v27i1.558
Abstract: Mundy (1982, The comparative biology of southern African Vultures, Vulture Study Group, Johannesburg.) states that records exist for only 22 nests of the Hooded Vulture Necrosyrtes monachus in Rhodesia, of which he visited 15, while in only three nests were the eggs measured. He makes no specific mention of egg measurements from nests south of the Limpopo River, although the average of 10 "Southern African" eggs is given as 74,72 (Range 68,7 - 78,1) by 55,89 (Range 54,0 - 57,8) mm. Nevertheless, five South African breeding records exist, all from the Kruger.
Effect of Delayed Bleeding on Carcass and Eating Qualities of Rabbit Meat
A.B. Omojola
Pakistan Journal of Nutrition , 2007,
Abstract: A total of forty eight matured New Zealand rabbits with an average weight of 2.06±0.45 kg were used to evaluate the effect of delayed bleeding on carcass and organoleptic characteristics of rabbit meat. The rabbits were fed concentrate diet containing 19.11% Crude Protein (CP) and 2514.3 Kcal/kg Metabolizable Energy (ME) for a period of thirty five days. The rabbits were randomly assigned to four treatment groups in a completely randomized design. Each treatment was replicated thrice with each replicate consisting of four rabbits. Treatment one served as control where the 12 rabbits were bled immediately after stunning while treatments 2, 3 and 4 comprised of rabbits that were bled 5, 10 15 minutes after stunning. After proper bleeding, the rabbits were skinned, washed and eviscerated and cut into primal cuts. Samples for sensory evaluations were taken from the thigh muscle and the remaining carcasses were aged at 4°C for 24 and 72 hours. The result showed that the dressing percentage, chilled carcass weight and the pH were not affected (p>0.05) by delayed bleeding while the volume of blood drained decreased (p<0.05) as the period between stunning and bleeding increased. The drip loss and cooking loss increased as the time between stunning and bleeding increased while the Water Holding Capacity (WHC) decreased. The effect of delayed bleeding on shear force, WHC, drip loss and cooking loss became more pronounced with ageing. Apart from the colour and juiciness rating that significantly (p<0.05) decreased, the other eating qualities were not affected (p>0.05) by delayed bleedin
The role of karst in the genesis of sulphur deposits, Pre-Carpathian region, Ukraine
Speleogenesis and Evolution of Karst Aquifers , 2005,
Abstract: Most of exogenous epigenetic sulphur deposits are clearly associated with intensely karstified carbonate and sulphate rocks. This paper demonstrates, using the Pre-Carpathian region as an example, that karstification is one of the most important processes guiding the formation of sulphur deposits. This is determined by a coincidence of some major prerequisites of these two processes. In the Podol'sky and Bukovinsky regions the Miocene aquifer system is well drained by erosion valleys; the giant network caves known here in gypsum formed under past artesian conditions. In the region of sulphur deposits, associated with the same karstified gypsum strata, true artesian conditions still prevail. Hydrogeologic data show that abundant cavities detected in the vicinity of sulphur deposits can be interpreted as having the same origin as the relict caves of the Podol'sky and Bukovinsky regions. The widespread belief that the gypsum/anhydrite bed in the region is an aquifuge separating the Miocene aquifers is inadequate. This belief caused much controversy with regard to the genetic interpretations of sulphur deposits in the region. Cave systems formed by the upward water flow through the gypsum/anhydrite bed govern the water exchange between the aquifers within the aquifer system. A new karst model for the formation of sulphur deposits is suggested. It agrees well with the hydrogeological features of the Miocene sequence and with biogeochemical mechanisms of sulphur origin in low-temperature diagenetic environments.
Conceptualisation of speleogenesis in multi-storey artesian systems: a model of transverse speleogenesis
Klimchouk, A.B.
Speleogenesis and Evolution of Karst Aquifers , 2007,
Abstract: Conceptual and respective quantitative models of speleogenesis/karstification developed for unconfined aquifers do not adequately represent speleogenesis in confined settings. A conceptual model for speleogenesis in confined settings is suggested, based on views about hydraulic continuity in artesian basins and close cross-formation communication between aquifers in multi-storey artesian systems. Soluble units sandwiched between insoluble porous/fissured formations (common aquifers) initially serve as low permeability beds separating aquifers in a confined system. Conduits evolve as result of vertical hydraulic communication between aquifers across the soluble bed ("transverse speleogenesis"). Recharge from the adjacent aquifer is dispersed and uniform, and flow paths across the soluble bed are rather short. There is a specific hydrogeologic mechanism inherent in artesian transverse speleogenesis (restricted input/output) that suppresses the positive flow-dissolution feedback and hence speleogenetic competition in fissure networks, and accounts for the development of more pervasive channelling in confined settings, of maze patterns where appropriate structural prerequisites exist. This is the fundamental cause for the distinctions between cave morphologies evolving in unconfined and confined aquifers and for eventual distinctions of karstic permeability, storage characteristics and flow system behaviour between the two types of aquifers. Passage network density (the ratio of the cave length to the area of the cave field, km/km2) and cave porosity (a fraction of the volume of a cave block, occupied by mapped cavities) are roughly one order of magnitude greater in confined settings than in unconfined. Average areal coverage (a fraction of the area of the cave field occupied by passages in a plan view) is about 5 times greater in confined settings. Conduit permeability in unconfined settings tends to be highly heterogeneous, whereas it is more homogeneous in confined settings. The storage characteristics of confined karstified aquifers are much greater. Recognition of the differences between origin, organisation and behaviour of karst systems evolved in unconfined and confined settings can improve efficiency of exploration and management of various resources in karst regions and adequacy of assessment of karst-related hazards.
Unconfined versus confined speleogenetic settings: variations of solution porosity
Klimchouk, A.B.
Speleogenesis and Evolution of Karst Aquifers , 2003,
Abstract: Speleogenesis in confined settings generates cave morphologies that differ much from those formed in unconfined settings. Caves developed in unconfined settings are characterised by broadly dendritic patterns of channels due to highly competing development. In contrast, caves originated under confined conditions tend to form two- or three-dimensional mazes with densely packed conduits. This paper illustrates variations of solution (channel) porosity resulted from speleogenesis in unconfined and confined settings by the analysis of morphometric parameters of typical cave patterns. Two samples of typical cave systems formed in the respective settings are compared. The sample that represents unconfined speleogenesis consists of solely limestone caves, whereas gypsum caves of this type tend to be less dendritic. The sample that represents confined speleogenesis consists of both limestone and gypsum maze caves. The comparison shows considerable differences in average values of some parameters between the settings. Passage network density (the ratio of the cave length to the area of the cave field, km/km2) is one order of magnitude greater in confined settings than in unconfined (average 167.3 km/km2 versus 16.6 km/km2). Similarly, an order of magnitude difference is observed in cave porosity (a fraction of the volume of a cave block, occupied by mapped cavities; 5.0 % versus 0.4 %). This illustrates that storage in maturely karstified confined aquifers is generally much greater than in unconfined. The average areal coverage (a fraction of the area of the cave field occupied by passages in a plan view) is about 5 times greater in confined settings than in unconfined (29.7 % versus 6.4 %). This indicates that conduit permeability in confined aquifers is appreciably easier to target with drilling than the widely spaced conduits in unconfined aquifers.
Towards defining, delimiting and classifying epikarst: Its origin, processes and variants of geomorphic evolution
Speleogenesis and Evolution of Karst Aquifers , 2004,
Abstract: Epikarst is the uppermost weathered zone of carbonate rocks with substantially enhanced and more homogeneously distributed porosity and permeability, as compared to the bulk rock mass below; a regulative subsystem that functions to store, split into several components and temporally distribute authogenic infiltration recharge to the vadose zone. Permeability organization in the epikarst dynamically develops to facilitate convergence of infiltrating water towards deeply penetrating collector structures such as prominent fissures that drain the epikarstic zone. This is manifested by epikarstic morphogenesis that tends to transform dispersed appearance of surface karst landforms into focused appearance adapted to the permeability structure at the base of epikarst. Epikarst is the result of combined action of several agencies including stress release, weathering and dissolution. It is a dynamic system which main characteristics are time-variant, changing in a regular way during the epikarst evolution. This paper examines the main characteristics of epikarst in the light of its origin and evolution.
Predicting Wave Velocity and Stress of Impact of Elastic slug and Viscoelastic Rod Using Viscoelastic Discontinuity Analysis (Standard Linear Solid Model)
A.B. Musa
Lecture Notes in Engineering and Computer Science , 2012,
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