Validation Study Of The Integral-Differential Scheme For Multi-Block Grids

This MS Thesis seeks to validate the accuracy of the Integral-Differential Scheme (IDS). In the attempts to accomplish this task, research efforts were focused on the scheme’s ability to capture the physics of known flow fields, as well as the scheme’s ability to predict the features of flow field quantities that may be derived from experimental measurements. The IDS was developed with the goal of being computationally efficient, from a programming perspective, as well as being numerically accurate, stable, and robust, from a mathematical perspective. The IDS is designed to solve the full Navier-Stokes equations in their integral forms. Unlike traditional control volume schemes, the IDS is built upon two sets of cells: spatial and temporal cells. For 2-D flows, the IDS considers an elementary control volume as a collection of four spatial cells and a single temporal cell. Similar to other explicit CFD schemes, the IDS relies on the use of the Taylor series expansion and other traditional CFD criteria. It is of interest to note that there are previous IDS validation studies which were conducted at North Carolina A&T State University. These past studies mainly focused on the qualitative aspects of the flow field physics. Furthermore, in all cases, they focused on flow field problems that can be represented by single-block grids. In this analysis, the validation studies are focused on multi-block grids in which the physics of the flow field is made complicated due to the presence of shock waves and flow separation zones. Of interest to this MS Thesis are two supersonic flow field problems that are supported by experimental data; namely, the supersonic flow over a rearward-facing step problem and the supersonic flow over a cavity problem. The validation studies conducted herein demonstrated that the IDS was able to predict the experimental data in both cases

The Influence of Weather on Mortality in Rural Tanzania: A Time-Series Analysis 1999�-2010

Weather and climate changes are associated with a number of immediate and long-term impacts on human health that occur directly or indirectly, through mediating variables. Few studies to date have established the empirical relationship between monthly weather and mortality in sub-Saharan Africa. The objectives of this study were to assess the association between monthly weather (temperature and rainfall) on all-cause mortality by age in Rufiji, Tanzania, and to determine the differential susceptibility by age groups. We used mortality data from Rufiji Health and Demographic Surveillance System (RHDSS) for\ud the period 1999 to 2010. Time-series Poisson regression models were used to estimate the association between monthly weather and mortality adjusted for long-term trends. We used a distributed lag model to estimate the delayed association of monthly weather on mortality. We stratified the analyses per age group to assess susceptibility. In general, rainfall was found to have a stronger association in the age group 0_4 years (RR_1.001, 95% CI_0.961_1.041) in both short and long lag times, with an overall increase of 1.4% in mortality risk for a 10 mm rise in rainfall. On the other hand, monthly average temperature had a stronger association with death in all ages while mortality increased with falling monthly temperature. The association per age group was estimated as: age group 0_4 (RR_0.934, 95% CI_0.894_0.974), age group 5_59 (RR_0.956, 95% CI_ 0.928_0.985) and age group over 60 (RR_0.946, 95% CI_0.912_0.979). The age group 5_59 experienced more delayed lag associations. This suggests that children and older adults are most sensitive to weather related mortality. These results suggest that an early alert system based on monthly weather information may be useful for disease control management, to reduce and prevent fatal effects related to weather and monthly weather.\u

Assessment of Strength Compliance with Standards for Tanzania Eucalyptus Wood Poles Treated with Copper-Chromium-Arsenic Compounds

Samples of copper-chromium arsenic compounds (CCA) treated Eucalyptus poles for power transmission were sampled from a lot following Military Standard MIL-STD 105D, Single sampling, Tightened Inspection, Acceptable Quality Level (AQL) of 4 as provided for in the South African Standard SABS 754:1994 from lots containing 151-500 poles. Samples were randomly selected from a lot. Maximum fiber stresses were evaluated taking into account the actual taper in each pole. The cantilever loading test was performed on the samples following SABS 754:1994. It was found out that the average taper for the poles was smaller than that assumed in the standard due to the different pole growth characteristics and environment in Tanzania and that the average modulus of elasticity obtained for the poles was lower than the average assumed in SABS 754:1994. The poles also showed excessive deflections at working loads. It is recommended to the Tanzania Bureau of Standards that although SABS 754:1994 is meant to be used for eucalyptus poles grown in Southern Africa south of the Sahara that are treated with creosote or CCA there is a need to review it to take into account the actual characteristics of the poles grown in Tanzania where they are normally grown in highland areas with higher rainfall and colder climates

Properties of Boards Made from Rice Husk and Portland cement As Binders and Reinforced with Sisal Fibres

A research study demonstrated that rice husks can be used to manufacture boards whichcan be used in low cost housing if bound by Portland limestone cement (CEM II/A-L/32.5R) and reinforced with sisal fibers to cater for their brittle behavior and that suchboards can provide a substitute for wood panels. Boards made of rice husks and cement inthe ratios of 1/3.3, 1/ 3.6 and 1/4 and with sisal fiber reinforcement contents of 0%, 0.4%,0.5% and 0.8% were prepared and tested for their physical and mechanical properties. Theresults were compared with standard requirements for boards made with wood based fiberand particle panel materials according to DIN 1101 and ISO 2696 and BS EN 634-2.Results indicate that water absorption and thickness swelling decreased with an increase infiber content and that there is an optimum rice husk/ cement ratio and fiber content thatgives maximum flexural strength and that such boards could be used in low cost housingconstruction. The use of such boards could be seen as partially solving the problem ofglobal warming and the problem of pollution associated with the disposal of rice husks indeveloping countries

Integrated Striga management in Sorghum through resistance breeding and biocontrol in the semi-arid regions of Tanzania.

Doctor of Philosophy in Plant Breeding. University of KwaZulu-Natal, Pietermaritzburg, 2017.Abstract available in PDF file

Comparison of the Properties of Portland Cement and Portland-Limestone Cement

A study was made in a cement factory in Dar es Salaam, Tanzania, where Ordinary Portland Cement (CEM I 42.5N) and Portland-limestone cement (PLC) which has the brand name Twiga Cement Extra (CEM II/A-L/32.5R) are produced and conforming to the Tanzania Standard TZS 727 (Part1): 2002, which is equivalent to EN 197 published by the committee  or European normalization (CEN). A comparison was made between the two types of cements in terms of physical, chemical and mechanical properties. It was found out that they all complied with the standards, that there was no significant difference in their setting times and that the Portland cement had higher strengths than the PLC. It was also  bserved that there was a slightly lower water demand for the same consistency when compared to OPC and hence there is an improvement of the cohesiveness of a concrete  ix when PLC is used. It was concluded, however, that the two cements are different and that sing the two cements interchangeably as is done in Tanzania is wrong because they do not have equivalent strengths and therefore equivalent performance since the PLC is not  timized. Portland-limestone cement (PLC) is known to offer significant energy savings and green house gas (GHG) reduction (up to 10% GHG savings) over conventional Portland cement while at the same time providing comparable performance if optimized

Validation Study Of The Integral-Differential Scheme For Multi-Block Grids

This MS Thesis seeks to validate the accuracy of the Integral-Differential Scheme (IDS). In the attempts to accomplish this task, research efforts were focused on the scheme’s ability to capture the physics of known flow fields, as well as the scheme’s ability to predict the features of flow field quantities that may be derived from experimental measurements. The IDS was developed with the goal of being computationally efficient, from a programming perspective, as well as being numerically accurate, stable, and robust, from a mathematical perspective. The IDS is designed to solve the full Navier-Stokes equations in their integral forms. Unlike traditional control volume schemes, the IDS is built upon two sets of cells: spatial and temporal cells. For 2-D flows, the IDS considers an elementary control volume as a collection of four spatial cells and a single temporal cell. Similar to other explicit CFD schemes, the IDS relies on the use of the Taylor series expansion and other traditional CFD criteria. It is of interest to note that there are previous IDS validation studies which were conducted at North Carolina A&T State University. These past studies mainly focused on the qualitative aspects of the flow field physics. Furthermore, in all cases, they focused on flow field problems that can be represented by single-block grids. In this analysis, the validation studies are focused on multi-block grids in which the physics of the flow field is made complicated due to the presence of shock waves and flow separation zones. Of interest to this MS Thesis are two supersonic flow field problems that are supported by experimental data; namely, the supersonic flow over a rearward-facing step problem and the supersonic flow over a cavity problem. The validation studies conducted herein demonstrated that the IDS was able to predict the experimental data in both cases

The Theory and History of Ocean Boundary Making

Over the years, Douglas Johnston has written and edited a large body of literature on the subject of ocean boundary making. The functionalist approach to ocean boundary which he presents in this book is obviously the result of his careful accumulation of knowledge and experience over many years\u27 involvement with the topic as researcher and writer. While at Dalhousie University in Halifax he had significant and direct involvement with the Ocean Studies Program

2-Cyclotomic field extensions

This paper presents a thorough investigation of $2$-cyclotomic extensions, covering various aspects such as their degrees, intermediate subextensions, Galois \\ structures, and the minimal polynomials over an arbitrary base field. In our quest to provide explicit expressions for the coefficients of the minimal polynomials of these intermediate subextensions in the cyclotomic field, we discovered fascinating \\ characterizations, some of which are linked to the well-known Catalan numbers