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A GENERIC ASSESSMENT OF WASTE DISPOSAL AT DOUALA CITY PRACTICES, PRINCIPLES AND UNCERTAINTIESAtangana, Abdon 18 July 2013 (has links)
One reason why groundwater, so often constitutes the main source of drinking water in
many cities and towns around the world, is because it is frequently present in sufficient
quantities at the point of demand. However, this seemingly advantage may sometimes be its
greatest disadvantage, especially in situations where the groundwater occurs at shallow
depths and the area overlying the aquifer is populated densely. This problem is particularly
relevant in the present technological age with its vast quantities of waste that is often
disposed in an uncontrolled manner. Such a situation occurs at Douala the economic capital
of Cameroon in central Africa. The city not only host more than 80% of industries in the
country, but also has the largest urban population of approximately 3 000 000 with a
population density of approximately 350 persons per square kilometre, which continue to
increase at a rate of approximately 120 000 migrants per year from the rural areas, while
the groundwater level is very shallow and may sometimes rise above the soil surface,
especially during floods, which occur not too infrequently.
Although the pollution problem is not restricted to groundwater as such, it is aggravated
here, because of the ancient belief that wastes are safely disposed of, if buried below the
earthâs surface. It took disasters like Love Canal and the Price Landfill to discover the
detrimental effects that this practice may have on the population living on or near polluted
aquifers. Extreme care therefore should be exercised to prevent the pollution of any aquifer
that may pose problems to living organisms or to try and restore a polluted aquifer
threatening the natural environment. Groundwater pollution should therefore receive
urgent attention when discovered.
This thesis describes an attempt to develop a set of guidelines for the restoration of the
groundwater resources at Douala, based on the relatively new technique of permeable
reactive barriers for groundwater remediationâa technique that is also increasingly
applied in the restoration of the Superfund sites in the United States of America.
Modern attempts to clean up contaminated aquifers, relies heavily on the use of suitable
computational numerical models. Such models have in the past always been based on the
classical hydrodynamic dispersion equation. However, an analysis of the equation in this
thesis has shown that the equation cannot account for the longâtail contamination plumes
characteristic of fractured rock aquifers. Fortunately, it is not too difficult to develop a more
suitable equation. For, as shown in the thesis, all that one has to do is to replace the ordinary derivatives in the classical equation with fractional derivatives.
Mechanistic modeling of physical systems is often complicated by the presence of
uncertainties, which was in the past usually neglected in the models used in the restoration
of aquifers.While these uncertainties have regularly been neglected in the past, it is
nowadays imperative that any groundwater model be accompanied by estimates of
uncertainties associated with the model. Although a large number of approaches are
available for this purpose, they often require exorbitant computing resources. The present
investigation was consequently limited to the application of the Latin Hypercube Sampling
method applied to an analytical solution of the hydrodynamic dispersion equation.
It has been known for years that the hydrodynamic dispersion equation discussed in
Chapter 5, is not able to account for the longâtail plumes often observed in studies of
contaminated fracturedârock aquifers. An approach frequently used to account for this is to
replace the ordinary spatial and temporal derivatives in the hydrodynamic equation with
fractional derivativesâa procedure confirmed in this thesis.
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THE INFLUENCE OF ANTHROPOGENIC NITRATE ON GROUNDWATER QUALITY IN THE THABA NCHU AREAAkwensioge, Mbinze 23 July 2013 (has links)
Enrichment of nitrate in groundwater is a worldwide phenomenon, mostly resulting from anthropogenic activities in densely populated areas. The objective of this study was to analyse the groundwater quality in Thaba Nchu in the vicinity of contamination sites, where the nitrate contamination of groundwater has been increased along the last decades. This is important to control and manage groundwater quality of aquifer systems in the rural areas. A multi-approach methodology was followed. During this approach, the hydrogeochemistry of major constituents (both hydrodynamic and hydrochemical parameters), as well as the concentrations of environmental isotopes (18O, 2H) and nitrate isotopes (15N and 18O) were used to provide information on land use in order to trace sources of waters and solutes, and to study associated processes in shallow groundwater systems of the Thaba Nchu rural villages. According to the spatial distribution of nitrate contents, nitrate concentrations exhibit very high concentrations in BAL2, GL1, GL2, GL3, NP2, NP3 and SP. 65 % of the sampled wells exceeded the value of 6 mg/L as NO3-N. On-site sanitation in the study sites were the main cause of serious nitrate contamination given the superimposition of high nitrate concentrations with the distribution of on-ground nitrogen loadings. A connection of nitrate concentrations to rainfall conditions was found: High nitrate concentrations were recharged under drier conditions while lower nitrate concentrations appeared to be recharged under much wetter conditions. From the Piper diagram calcium chloride/nitrate water type showed significantly higher NO3-N concentrations (NO3-N > 100 mg/L) than the other water types. The Expanded Durov diagram showed a range of water types from fresh, clean water to mixtures from different sources. Nitrate has a less coherent distribution associated with high δ18O values, clearly suggesting either a non-conservative behaviour or more than one source. Different δ18O-NO3 trends suggested isotopically distinct, non-point source origins which varied spatially and temporally, due to different degrees of evaporation/recharge and number of on-ground nitrogen loadings. The plot of δ15N versus δ18O values indicated that animal and human wastes were the predominant NO3â sources, and a few boreholes from ammonium fertilisers and organic soil matter. KOM was the only borehole experiencing denitrification. A management strategy was developed consisting of a situation assessment, immediate actions, medium and longer-term actions. The management and reduction of groundwater nitrate levels depend on an understanding of the nitrogen sources and the pollution and nitrification mechanisms.
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CIVIC CULTURE AND LOCAL ECONOMIC DEVELOPMENT IN A SMALL TOWNvan Rooyen, Deidré 07 October 2013 (has links)
Although several cases of successful Local Economic Development (LED) programmes and
initiatives addressing poverty and inequity are present in South Africa, there are still a number of
challenges to overcome.
Firstly, the definition of LED varies, however the essence of LED is local partnerships for locality
planning â based on economic growth. Consequently, the analysis in this thesis uses the
âL-E-Pâ model, combining elements of âLocalityâ, âEconomicâ and âPartnershipsâ. This model
could be an answer for LED policy and practice to make use of all these elements.
Secondly, LED strategies need to go beyond merely compiling LED documents. Municipalities
need to engage with communities and the private sector in prioritising and designing appropriate
strategies that unlock local potential. However, in South Africa partnerships have not always
been central to LED planning. Furthermore, the soft factors of co-operation â trust and social
capital -, which are considered essential for effective collaboration between state and non-state
actors, should be constructed. Consequently, LED practitioners need to pay greater attention to
social relationships and networks, which fundamentally mould local economies.
Thirdly, academic research is only starting to incorporate social resources into economic
development practice. Furthermore, only a few authors have taken the concept of civic culture
into consideration when analysing LED. Local civic culture relates to how local problems are
defined, how solutions are found, how the local economic problems can be solved, who is
involved and how the decisions are made. International civic culture literature has been
contextualised to classify civic culture in South African terms. If an understanding of the civic
culture of an area is acknowledged, planning and development of this area can be simplified. Beaufort West is used as an example of a typical Karoo town to illustrate how the type of civic
culture a community has, can influence local economic growth.
Fourthly, there is a lack of research related to the establishment, growth and development of
mining towns. Although numerous international mining companies have identified the Karoo
surrounding Beaufort West for uranium extraction, planning documents of the Western Cape
Provincial Growth and Development Strategy (PGDS) and also in the Integrated Development
plans (IDPs) of the Central Karoo District Municipality and the Beaufort West Local Municipality
do not make any suggestions for the economic âroller-coasterâ ride ahead. The sustainability of
mining (non-renewable resource) towns is not as important as are the economic developments
of and the proactive planning (in partnerships) in these towns.
Fifthly, business confidence helps explain the sentiments that business owners or managers
have towards current and future business conditions. Several ways of measuring business
confidence are compared. Business confidence is mostly surveyed at national level. A
methodology for business confidence surveys at the local level is provided. This approach has
been piloted in the town of Beaufort West in the Karoo area of South Africa. There are plans for
a new uranium mine near Beaufort West, and the researcher speculates on its impact on the
broader local business confidence. The results of the 2007 and 2009 study in terms of the
opinions of business confidence in Beaufort West are compared.
There are very few comparative studies in terms of all the above-mentioned factors. Therefore,
the researcher proposes that these methodologies and models should be tested in other towns.
This will then determine whether the results differ in other Karoo towns and from the rest of
South Africa.
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THE RELATION BETWEEN SOUTH AFRICAN GEOLOGY AND GEOHYDROLOGYLourens, Paul Joël Havemann 03 December 2013 (has links)
Not available
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Family influence on physical activity : exploring the nature of reciprocal relationshipsZebedee, Janelle Ann. 10 April 2008 (has links)
The National Population Health Survey (CFLRI, 1998199) indicates an alarming
58% of Canadian youth are physically inactive. As well, 59% of Canadian women and
52% of Canadian men are also physically inactive (CFLRI, 1998199). Given the benefits
of physical activity to health, it is essential to learn more about the nature of family
influence on physical activity. This study was an exploration towards better
understanding the reciprocal relationship between parents and children's physical activity
behavior. Social Cognitive Theory provided a theoretical framework to investigate the
nature of the family socialization process. Qualitative methods examined the relationship
and influence between parents and children's choice to be physically active. Focus group
discussions were conducted with children and parents to understand influences on their
physical activity. Common themes were identified to gain insight into the social
interaction between children and parents. A better understanding of reciprocal family
influence on physical activity behavior will help foster interventions and new ideas to
promote physical activity, thereby enhancing the quality of life for children and their
parents.
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Credit risk analysis using artificial intelligence : evidence from a leading South African banking institutionMoonasar, Viresh January 2007 (has links)
Credit risk analysis is an important topic in financial risk management. Financial
institutions (e.g. commercial banks) that grant consumers credit need reliable models
that can accurately detect and predict defaults. This research investigates the ability
of artificial neural networks as a decision support system that can automatically
detect and predict “bad” credit risks based on customers demographic, biographic
and behavioural characteristics. The study focuses specifically on the learning vector
quantization neural network algorithm.
This thesis contains a short overview of credit scoring models, an introduction to
artificial neural networks and their applications and presents the performance
evaluation results of a credit risk detection model based on learning vector
quantization networks.
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The effect of slurry in the maintenance of the clover component in mixed grass/clover swardsChapman, Ross January 1988 (has links)
Low input grassland systems depend on cheap fertiliser sources, such as clover or animal manures, to maintain sward productivity. Clover is a poor competitor for phosphate (P2O5) and potash (K2O), a mixed sward will therefore require adequate inputs of these nutrients. Nitrogen (N) leads to the suppression of clover. Recycling of cattle slurry would be followed by small N and P2O5 but large K2O effects. The K2O and P2O5 would be expected to have a beneficial effect on the clover while the N would be detrimental. Two investigations into the balance between these aspects of cattle slurry on clover in a mixed sward were performed. Slurry N led to clover suppression, this effect was strongest following spring applications. K2O had a beneficial effect on the clover, the P2O5 supplied had a small positive effect but was insufficient to fully meet the clover's requirements. There was a suggestion that these beneficial effects were strongest following summer applications. In addition to these fertiliser effects, non nutritional secondary effects often followed slurry with a deleterious action on the clover. These effects were most common following higher rates of slurry and summer applications. A further investigation was performed to establish the effect of varying clover variety and companion grass species on the clover's susceptibility to cattle slurry N and secondary effects and the nature of these effects following pig slurry applications. This revealed that clover's susceptibility to slurry N was inversely related to leaf size. No difference in secondary effects susceptibility arose with different clover varieties or companion grass species. Pig slurry was not accompanied by secondary effects. Slurry applications to mixed swards may therefore have positive and negative nutritional effects on the clover component but non nutritional secondary effects may also act with a deleterious effect on the clover.
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Selective hydrogenation catalysed by transition metal complexesNilchi, A. January 1988 (has links)
This work is an investigation of the mechanism by which norbornadiene, methyl oleate and methyl linoleate are hydrogenated in acetone at 30[sup]oC, 1 atmosphere or 3 atmospheres pressure, using rhodium complexes of the type [Rh(diene)L[sub]n][sup]+A[sup]-(where diene = norbornadiene , L = tertiary phosphine, phosphite, A = CIO[sup]-[sub]4 or PF[sup]-[sub]6). The results were interpreted assuming three active catalyst species, (Rh(diene)L[sub]2)[sup]+, (RhH[sub]2L[sub]2)[sup]+ and RhHL[sub]2. Also investigated were the effects of adding acid (HClO[sub]4) or base (Net[sub]3) and how this altered the equilibrium (RhH[sub]2L[sub]2)[sup]+<--> H[sup]+ + RhHL[sub]2. At atmospheric pressure, the rate of hydrogenation of norbornadiene and norbornene varies with ligand in the order PPh[sub]3 < PPh[sub]2Me < PPhMe[sub]2, suggesting that oxidative addition of hydrogen is an important first stage of the catalysis. The addition of acid, slowed the rate of hydrogenation for catalysts containing more electron donating ligands (relative to triphenyl phosphine), indicating that the monohydride was a more active specie than the dihydride. With triphenylphosphine or less electron donating ligands in the catalyst, the rate remains constant or increase slightly, indicating that an "unsaturate route" emanating from a diene complex is probably important. The catalyst containing cyclohexylphosphine ligands which are strongly electrondonating but sterically crowded is ineffective in hydrogenation, suggesting that steric crowding may cause an alternative route to operate. Higher pressure (3 atm.) causes faster hydrogenation and provided other mechanistic insights. For methyl oleate at atmospheric pressure, the rate of hydrogenation varies with ligand in the order PPh[sub]3 > PPh[sub]2Me > PPhMe[sub]2, but this order is reversed at 3 atm. pressure. The rate of isomerisation of methyl oleate varies with ligand in the order PPh[sub]3 < PPh[sub]2Me < PPhMe[sub]2, at both pressures. The rate of isomerisation of methyl oIeate and methyl linoleate is lowest, when there is no or a slight excess of acid present but is highest in presence of a base (especially for the catalyst containing diphenylmethylphosphine ligand). Mechanistic interpretations were made.
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Defining acceptable colour tolerances for identity branding in natural viewing conditionsBaah, Kwame F. M. January 2017 (has links)
Graphic arts provide the channel for the reproduction of most brand communications. The reproduction tolerances in the graphic arts industry are based on standards that aim to produce visually acceptable outcomes. To communicate with their target audience brands, use a set of visual cues that may include the definition of a single or combinations of them to represent themselves. The outcomes are often defined entirely by their colour specification without an associating it to target parameters or suitable colour thresholds. This paper researches into the feasibility of defining colour tolerances for brand graphical representations. The National Health Service branding was used as a test case borne out of a need to resolve differences between contracted suppliers of brand graphics. Psychophysical evaluation of colour coded navigation used to facilitate wayfinding in hospitals under the varying illuminances across the estate was found to have a maximum acceptable colour difference threshold of 5ΔE00. The simulation of defined illumination levels in hospitals, between 25-3000 lux, resulted in an acceptable colour tolerance estimation for colour coded navigation of 3.6ΔE00. Using ICC media relative correction an experiment was designed to test the extent to which substrate white points could be corrected for colour differences between brand proofs and reproductions. Branded stationery and publications substrate corrections to achieve visual matches had acceptable colour difference thresholds of 9.5ΔE*ab for solid colours but only 2.5ΔE*ab. Substrate white point corrections on displays were found to be approximately 12ΔE*ab for solids and 5ΔE*ab for tints. Where display media were concerned the use of non-medical grade to view medical images and branded content was determined to be inefficient, unless suitable greyscale functions were employed. A STRESS test was carried out, for TC 1-93 Greyscale Calculation for Self-Luminous Devices, to compare DICOM GSDF with Whittle’s log brightness. Whittle’s function was found to outperform DICOM GSDF. The colour difference formulas used in this research were tested, using near neutral samples 2 judged by observers using estimated magnitude differences. The CIEDE2000 formula was found to outperform CIELAB despite unexpected outcomes when tested using displays. CIELAB was outperformed in ΔL* by CIEDE2000 for displays. Overall it was found that identity branding colour reproduction was mostly suited to graphic arts tolerances however, to address specific communications, approved tolerances reflecting viewing environments would be the most efficient approach. The findings in this research highlights the need for brand visualisation to consider the adoption of a strategy that includes graphic arts approaches. This is the first time that the subject of defining how brands achieve tolerances for their targeted visual communications has been researched.
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The Generalized Cayley Map from an Algebraic Group to its Lie Algebramichor@esi.ac.at 11 September 2001 (has links)
No description available.
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