International Journal of Engineering Research in Africa Vol. 49

Abstract: Drilling additives play a unique role during drilling operations, from aiding in the control of various drilling challenges to successfully enhancing downhole drilling efficiency. pH enhancers are amongst the plethora of additives imported into Nigeria at exorbitant prices to aid in drilling operations. These additives includes NaOH, Na₂CO₃, Ca (OH)₂ etc. These additives are used to improve the mud pH and mitigates drill string corrosion. The high cost of importation of these additives, has warranted the need for product substitution which should take advantage of the locally available resources. This paper evaluated the suitability of locally-sourced Trona, as a mud additive in drilling mud. Trona is known chemically as Sodium Sesquicarbonate or Sodium Hydrogen Carbonate. A distinguishing factor in this research work was the purification of Trona by extracting the compound of interest (Na₂CO₃) from it using the monohydrate process. The purification method involved crushing and screening of Trona as well as calcination, filtration and evaporation processes. The analysis of the Trona and the extracted product was performed using quantitative analysis and characterization tools such as FTIR and EDX. Further experimentation was carried out to evaluate the effects of the extracted sodium carbonate on the mud pH, rheology, and density of the water-based mud. The results were also compared to the results gotten from the addition of conventional Na₂CO to similar mud samples. The extracted Na₂CO was observed to increase the pH of the mud samples from 8.73 to 9.52 and the commercial Na₂CO increased it from 8.73 to 10 and this value is still in the range of API standard. The pH enhancers from both sources also had effect on the mud rheological properties. This indeed showed that the extracted Na₂CO from Trona acted as drilling fluid pH enhancer and hence possess the potential for usage in the industry.

Abstract: In this study a wastewater network model is developed using ArcGIS based automated tool that integrates with AutoCAD and SewerCAD. The developed model consists of three main phases. The AutoCAD phase where input data like served area, land survey, and network planning are prepared in DWG form. Then, the ArcGIS processes the DWG input data and generates output shapefiles required to build a SewerCAD network in the third phase. The shapefiles include all defined parameters required to start network analysis like pipelines layout, manholes’ locations, elevations, assigned populations and sanitary loads. Also, The model provides an unserved area option which allows the model user to eliminate a specific unsewered zone(s) from the predefined served area. The model helps network designers saving time and minimizing efforts since building wastewater networks in SewerCAD becomes a matter of minutes not hours. The model is applied on a wastewater network of an Egyptian village.

Abstract: Many companies are facing a constant need to develop coordination between operational functions to quickly respond to customer requests. Thus, many practitioners are resorting to an established and integrated business management methodology, the Sales and Operations Planning (S&OP). The impact of the S&OP on operational performance was significantly demonstrated in many studies. However, it turns out that the theoretical studies made differ from what is actually applied, in addition to several parameters that are considered in the calculations especially with regard to Japanese industries. So, how is S&OP operated in this industry? What are the different calculation parameters used? and how are the results obtained and analyzed?In this paper, we will first present a short literature review of S&OP and its role and benefits. Then, we present a model of S&OP used in a wire harnesses Japanese industry. The goal is to show first a concrete example, where we present the various parameters considered in the calculations, and then we will explain how the resulting graphs are analyzed by managers and what could be done as corrective actions in case of gap existing.

Abstract: This paper is concerned with stochastic optimization in continuous time and its application in reinsurance. It deals with a model of optimization reinsurance which makes it possible to maximize the technical benefit of an insurance company and to minimize the risk for a given period. Indeed, here we discuss a stochastic optimal control problem to determine the optimal risk management strategy, the purpose of which is to identify the appropriate level of transfer rate for "quota share" reinsurance contracts, which are most appropriate to the risk profile of an insurance company. In addition, we use a resolution approach based on dynamic programming and the HJB equation in order to reach the aforementioned aim, which is finding the optimal strategy for reinsurance to adapt better for insurance company.

Abstract: The good functioning of a discrete event system is related to how much the temporal constraints are respected. This paper gives a new approach, based on a statistical model and neural network, that allows the verification of temporal constraints in DES. We will perform an online temporal constraint checking which can detect in real time any abnormal functioning related to the violation of a temporal constraint. In the first phase, the construction of temporal constraints from statistical model is shown and after that neural networks are involved in dealing with the online temporal constraint checking.