21 research outputs found
A bearing capacity approach to the design of low-volume traffic roads
No full textPavement design methods based on the elastic layer theory idealize the pavement structure as consisting of linear elastic layers and utilize the theory of elasticity to predict limiting stresses and strains. The assumption of elastic behavior may be valid for relatively stiff pavement materials. In unpaved roads, consisting of unbound granular bases overlying cohesive subgrades, the assumption of elastic behavior is unlikely to be valid. The behavior of such pavements under traffic stresses is markedly nonlinear. Pavement design methods based on the ultimate strength approach assume shear failure of the pavement structure at sufficiently high traffic stresses. Pavement material behavior is assumed to be plastic rather than elastic. The assumption of plastic response is more realistic for unpaved roads in which traffic stresses exceed the elastic range of the pavement materials. The determination of the ultimate wheel load that a pavement structure can sustain is the most important component of a design process based on bearing capacity theory. Existing solutions are restricted to a narrow range of material properties and are also deficient in the manner in which they determine ultimate wheel loads. General and accurate solutions for the determination of the bearing capacity of pavement structures are required. The incorporation of climatic factors in the pavement design process is another important component of design based on bearing capacity theory. Existing methods assume full saturation of the subgrade. Experience has shown that in many regions of the world full saturation rarely occurs and the assumption of full saturation leads to overdesign. There is a need to incorporate the influence of matric suction in the determination of ultimate wheel loads. A limit equilibrium solution, which can handle any combination of pavement material properties, is proposed for the determination of bearing capacity in a 2-layer pavement system. To enable the incorporation of climatic factors in the determination of ultimate wheel loads, limit equilibrium solutions are proposed for the determination of the effects of positive pore-water pressures and matric suction on bearing capacity. The solution developed for the influence of matric suction on bearing capacity is verified in the laboratory using model footing tests in homogeneous soils equilibrated under constant levels of matric suction. A simple method of testing compacted soils in the direct shear apparatus as well as a method of analyzing the test results in terms of the stress state variables is proposed. The method of testing and analysis is shown to give results which are comparable to the results of the modified direct shear test. The method is considered to be a simple and viable alternative for the characterization of shear strength of compacted unsaturated soils. Finally, a method based on bearing capacity theory is proposed for designing unpaved roads whose structure consists of a base layer overlying a subgrade. The method can handle any combination of shear strength parameters as well as constant levels of matric suction in the pavement layers
Bases for Integer Generalized Splines on Graphs, an Investigation
No full textv, 20 p.Let R be a ring and G a graph whose edges are labeled by ideals of R. A vertex labeling of G by elements of the ring is called a generalized spline if for each edge, the difference of the labels of the two connected vertices lies in the edge's ideal. The author examines the algebraic structure of the set of generalized splines -it is actually an R-module- and present results of Handschy, Melnick and Reinders concerning the existence of splines where the graph is a cycle and the ring is Z. The author also summarizes more general results of Gilbert, Polster and Tymoczcko regarding existence of nontrivial splines on arbitrary graphs. They show that when working over an integral domain, the set of all splines on a graph contains a free submodule whose rank is the number of vertices. The author gives examples of their construction working over the ring of integers
Method for determination of "Ob" for statically compacted soils
No full textAbstract in FrenchDue to copyright restrictions, this item cannot be share
An examination of constraints on fruit production by smallholder farmers in Vhembe District
No full textMRDVInstitute for Rural DevelopmentThe production of fruit commodity is crucial for livelihood, job creation and income generation. Smallholder fruit farming has become one of the key strategies to tackle the problems relating to health, lack of employment and poverty amongst rural people. The purpose of this study was to investigate fruit production levels by smallholder farmers in the Vhembe District of Limpopo Province, with special focus on mango, avocado, and macadamia nuts. The author investigated factors affecting smallholder fruit farmer's productivity and suggested policy recommendations that could lead to enhanced production. The author used both quantitative and qualitative methods of data collection by interviewing smallholder fruit farmers, and officials dealing with fruit production using structured and unstructured administered questionnaires in making observations of their farming practices. Out of a total population of 439 fruit producers, 224 were selected by employing the stratified random sampling procedures in Thulamela, Makhado and Mutale local municipalities in Vhembe District. The Statistical Package for Social Sciences (SPSS 2012, 20) was used to capture and analyse data. This was done to draw frequencies and cross tabulations. Content analysis, frequency distribution, and descriptive statistics were used to answer the objectives of the study. The study revealed shortage of water, low input use, lack of storage facilities, inadequate access to land, insecure tenure, insufficient pests, insects and diseases control, lack of access roads, labour, communication infrastructure and lack of practical management skills as major constrains contributing to low fruit production. It was envisaged that the results of the research would provide compelling scientific information that would help create a better platform for implementing improved farming strategies by government
An Analysis of Speech Acts in Margaret Ogola's the River and the Source and I Swear by Apollo
No full textNovels are characterized by narration. However, in some instances depending on the style of the author, some portions of the novel may consist of interactions between the characters. It is therefore through speech acts analysis that the reader can interrogate how the writer develops the plot, characterization and the major concerns in the novel through discourse situations where a character talks to another character. This study examined speech acts in Margaret Ogola's two novels' The River and the Source (1994) and I Swear by Apollo (2002).In this regard, the objectives of this study were, firstly, to interrogate the significance of speech acts in comprehending dialogue in the novels The River and the Source and I Swear by Apollo, secondly, to describe the types of speech acts used by the writer in the novels The River and the Source and I Swear by Apollo, and finally to evaluate the uses and significance of speech acts used in the novels The River and the Source and I Swear by Apollo. Austin's (1962) Speech Act Theory guided this study. The study employed an analytical research design. A mixed method approach was used to analyze the data. Qualitative method was used to present the data in form of description whereas quantitative was used to count the total number of the speech acts used by the main characters. The population in this study was all the four novels by Ogola. To achieve its objectives; the study purposively selected two of her four novels due to the extensive use of dialogue in these two novels. Library research and content analysis were used in collecting data. Data was obtained from reading and analysis of the primary texts supplemented by secondary texts. The data was in form of utterances from the characters' conversations containing speech acts. The study concluded that speech acts in pragmatics could be used in the analysis of characters' utterances in the novels in the same way as daily verbal interactions. Secondly, the findings indicated that every utterance used by a character performs three simultaneous acts, namely: a locutionary, an illocutionary and perlocutionary. Moreover, every utterance produced by a character in the novels could be categorized under one of the five major categories of speech acts proposed by Searle: representatives, expressives, directives, commissives or declarations. The study found that all these five major speech acts were used by the writer in the novels with the representative being the most dominant in both novels and the declarations the least. In addition, the successful performance of each speech act depends on satisfying the four linguistic and non linguistic conditions called felicity conditions which interlocutors use in production and interpretation of utterances. These are the propositional, preparatory, sincerity and essential conditions. The study also revealed that each major speech act contains a wide range of sub acts or illocutionary forces which are distinguished based on their felicity conditions. For this reason, the findings showed that the writer used thirty six sub acts in the novels with the act of asserting having the highest frequency. Finally, the study also found out that both direct and indirect speech acts are used in the novels with the direct speech acts having the highest frequency of use. This study recommends that a speech act analysis be adopted as an effective tool in the analysis of the characters' verbal interactions in novels. In addition, it recommends that further research be conducted on speech act analysis of novels by other writers
Water Flow Behavior and Storage Potential of the Semi-Arid Ephemeral River System in the Mara Basin of Kenya
No full textAlluvial corridors of ephemeral river systems provide viable opportunities for natural water storage in dry lands. Whilst alluvial corridors are widely recognized as water buffers, particularly for areas experiencing constant water scarcity, little research has been undertaken in Sub-Saharan Africa to explore their hydrological variability and water resource potential as alternative water sources for nearby communities. This study investigated the water flow behavior and storage potential of an ephemeral river system in the Mara Basin of Kenya for purposes of supporting water resources development and ecological sustainability. The water flow processes – including the recharge rates and water loss processes – from existing sand storage systems were established through monitoring of ground and surface water levels. Water samples along the alluvial corridor were collected and analyzed for major ions and isotopic signatures required to establish the water storage dynamics. The storage potential was estimated through Probing and Electrical Resistivity Tomography techniques, augmented with in-situ measurements of hydraulic conductivities and channel bed porosities. The mean annual storage volume in the alluvium of the study reach was estimated at 1.1 Mm3, potentially capable of providing for the annual domestic and livestock water demands of the area. Transmission losses into the alluvium beneath the ephemeral channel-bed were noted to attenuate the flood peak discharges, depending on the level of saturation of the alluvial bed. However, water storage in the alluvium was subject to losses through evapotranspiration and seepage through fractured bedrocks. The study demonstrated the potential of alluvial corridors as water storage buffers providing alternative water sources to communities within the dry land regions with water scarcity, thereby to supporting ecosystem sustainability.Water Resource
Fever and its treatment among the more and less poor in Sub-Saharan Africa
Get PDFThe author empirically explores the relationship between household poverty and the incidence and treatment of fever--as an indicator of malaria--among children in Sub-Saharan Africa. He uses household Demographic and Health Survey data collected in the 1990s from 22 countriesin which malaria is prevalent. The analysis reveals a positive, but weak, association between reported fever and poverty. The geographic association becomes insignificant, however, after controlling for the mother's education. There is some evidence that higher levels of wealth in other households in the cluster in which the household lives are associated with lower levels of reported fever in Eastern and Southern Africa. Poverty and the type of care sought for an episode of fever are significantly associated: wealthier households are substantially more likely to seek care in the modern health sector. In Central and Western Africa those from richer households are more likely to seek care from all types of sources: government hospitals, lower-level public facilities such as health clinics, as well as private sources. In Eastern and Southern Africa the rich are primarily more likely to seek care from private facilities. In both regions there is substantial use of private facilities--use that increases with wealth. Like the incidence of fever, treatment-seeking behavior is strongly associated with the level of wealth in the cluster in which the child lives.Disease Control&Prevention,Health Systems Development&Reform,Public Health Promotion,Health Monitoring&Evaluation,Early Child and Children's Health,Health Monitoring&Evaluation,Poverty Assessment,Communicable Diseases,Statistical&Mathematical Sciences,Health Indicators
Author Correction: Spatial analysis and risk mapping of Crimean-Congo hemorrhagic fever (CCHF) in Sub-Saharan Africa
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