https://repository.sustech.edu/handle/123456789/16548 2026-04-09T00:52:24Z https://repository.sustech.edu/handle/123456789/16550 Sequence Stratigraphy and Sedimentary Facies of Fula Subbasin, Muglad Basin (Sudan) Hussien, Rashid Ahmed Mohammed Sedimentary analysis and Facies Associations may enhance accuracy of sequence stratigraphic correlation of Fula Subbasin, Muglad Basin, Sudan. According to core (very little) and log data, stratigraphic correlation was set. Abu Gabra Formation, Bentiu Formation, and Aradeiba Formation were subdivided into units. Essential depositional systems were recognized in the study area on the basis of the evolution of sedimentary facies. The origin of Fula Subbasin is related to the first rifting cycle (+ synrifting cycle?) that took place during the Early Cretaceous associated with an increase in tectonic activity and the opening of the Central African rift system (Late Jurassic- Middle Miocene). Synsedimentary tectonic activity and succeeding restructural regime of the subbasin were clearly reflected in the sedimentary records. Two sets of faulting in Fula oil field were detected. The first set was striking NW-SE, as in five zones the Fula 1 fault, Fula 2 fault, Fula 3 fault, eastern fault of well Fula 1 and the western fault of well Fula North 2, which dominate the evolution and sediments of the Fula structure. The second set was striking EW, as the north fault of well Fula 1, which controls the evolution of the trap. Three seismic horizons, i.e. the top of Aradeiba, the top of Bentiu and the top of Abu Gabra formations were chosen for interpretation according to their geological significance. Infill of that Early Cretaceous subbasin began with continental deposits that were alluvial and lacustrine in origin. article 2012-01-01T00:00:00Z https://repository.sustech.edu/handle/123456789/16552 Multiple Gross Errors Detection in Surveying Measurements Using Statistical Quality Control Elgazooli , Badria A. Gissmalla; Ibrahim , Ahmed M. Most of the surveying tasks involve the acquisition and analysis of measurements. Such measurements are subject to random, systematic and gross errors. In practice, redundant measurements are made to provide quality control and errors check. In qualitative analysis and statistical evaluation, it is generally assumed that the measurements contain only random errors and are regarded as random variables. In reality, the measurements may contain gross and/or systematic errors. The effects of such errors are distributed over the residuals, after an adjustment and lead to questionable results and interpretation. For high precision applications, gross and systematic errors need to be detected prior to the analysis. These errors should be tackled before the adjustment by means of screening. These few remaining gross errors in the measurements can be detected after the adjustment. These adjustment methods assume the presence of only one gross error. One of the most effective methods that can be used in detecting multiple gross errors is the statistical quality control method. Statistical quality control is a technique used to monitor a procedure with a goal of making it more efficient and ensures precise results. Statistical control charts are used to provide an operational definition of a special cause for a given set of data. It is possible to construct multiples of sigma control limits. When all the points on a control chart are within a multiple of sigma control limits and there are no gross errors in the data, the process of measurements is said to be in a state of statistical control. Otherwise, the data indicate the presence of non-random gross errors. In this research work, different methods of statistical quality control were used. Results showed that statistical quality article 2012-01-01T00:00:00Z https://repository.sustech.edu/handle/123456789/16549 Geometrically Nonlinear analysis using Plane Stress / strain Elements based on Alternative Strain Measures Akasha ,N. M.; Mohmed , Abdelrahman E. The description of deformation and the measure of strain are essential parts of nonlinear continuum mechanics. In this paper, a new formulation for geometric nonlinear plane stress/strain based on Logarithmic strains (GNLGS) is presented. This is coupled with a formulation based on the well known Greens strains and coupled with modifying a formulation based on geometric strains (conventional strains). A geometric nonlinear total lagrangian formulation applied on two-dimensional elasticity using 4-node plane finite elements is used. The formulations were implemented into the finite element program (NUSAP), which is developed for the analysis of plane stress/strain problems subjected to static loading. The solution of nonlinear equations was obtained by the Newton-Raphson method. The program was applied to obtain displacements for the different strain measures. The accuracy of the results was demonstrated by using two numerical examples and the results are in good agreement with other available published solutions and those obtained using commercial finite element solvers such as ANSYS. It could be concluded that the geometrically nonlinear formulations converge to the correct solution with coarse meshes and are computationally efficient. In addition, the resulting displacements clearly showed the effect of the nonlinearity in the deflected shape. It is also observed that all results were approximately identical when applying a small value of load and when a large value of a load was applied there was a difference between the results of the three strain measures. article 2012-01-01T00:00:00Z https://repository.sustech.edu/handle/123456789/16553 Optimally Tuned Proportional Integral Derivatives (PID) Controllers for Set-point Eltayeb, Eisa Bashier Mohamed; Salama , Omer Mohammed The proportional-integral-derivative (PID) controller is tuned to find its parameters values. Generally most of the tuning methods depend mainly on the experimental approach of open-loop unit step response. The controller parameters can be found if the system truly can be approximated by First Order Plus-Dead Time (FOPDT). The problem with such type of controllers is that: the performance of most of them deteriorates as the ratio ( ) of approximated equivalent delay L to the overall time constant T changes. The optimum tuning always checks this ratio and considers it in its formulae. The performances of different PID tuning techniques are simulated for different systems and analyzed based on the transient responses. MATLAB simulation results are presented and compared for different higher order systems. For the same characterization procedure, optimally tuned PID controller shows better performances over Ziegler-Nicholas (Z-N) and Cohn-Coon tuned. Superiority of the optimal PID tuning techniques sustained for variety of higher order systems. article 2012-01-01T00:00:00Z