Browsing by Author "Tesfaye Yohannes"

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    Assessment of Power Interruptions in Addis Ababa
    (Addis Ababa University, 2015-07) Tesfaye Yohannes; Seid Mohammed
    This research project is done for the primary purpose of assessing electric power interruptions in Addis Ababa. Power interruption becomes a serious problem in the city in everywhere. The number of outages is very high and it takes long time for service restoration. Due to this every aspects of business and non business activities and day to day lives of the city residents are negatively affected and highly complained with this problem. Moreover the power interruptions cause wastage of power or power losses significantly. The objective of this research project is identifying the root causes of power interruption and identifying and forwarding the appropriate remedies for the identified problems. For this end primary and secondary data are collected, a subsequent four year power nterruptions secondary data are collected from the service provider. A primary data is collected through open ended and close ended questionnaires, interviews and observations. Questioner is developed for electric power customers, for the service provider distribution and transmission operation staffs. Representative sample is determined based on random sampling method at 95% confidence level and at 5% margin of error. As per this 384 samples is determined out of 523,944 electric power customers and 184 sample employees from a total 362 employees. The analysis is done based on descriptive research analysis by using both qualitative and quantitative methods. Problems identifications are also done through SWOT analysis and root cause analysis. Root cause identifications are done through problem tree analysis. The research analysis find outs that power interruptions, power drops and poor customer services are major problems in electric power service. The root causes of the existing power interruptions are infrastructure capacity limitations, poor infrastructure & design, infrastructure management problem, poor planning & forecasting, exposure of infrastructures for theft & accidents, natural accident and water shortages. The company can minimize the power interruption problems by upgrading power supply infrastructure capacity, improving power infrastructure & design, improving infrastructure management practices, developing effective planning & forecasting practices: establishing preventive maintenance systems, applying power infrastructure rehabilitations works, supplying adequate and standard quality inputs, minimizing operational interruptions, developing infrastructure capacities, improving human resource management Practices and by making further studies. Electric power interruption is power outages and blackouts due to various reasons. Frequency of power interruption indicates the rate of occurrence or the number of repetition of the power interruptions in the grid systems. Whereas interruption duration indicates the length of time the power interruption continues or exists in the power grid systems.
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    Generalized Solution of Inhomogeneous Differential Equations
    (Addis Ababa University, 2010-06) Tesfaye Yohannes; Abdi Tadesse (PhD)
    We study the method to find a generalized solution to the linear inhomogeneous differential equations of different orders. Here first, second and fourth order linear inhomogenous differential equations are considered. We use generalized function for finding the generalized solutions of linear inhomogenous differential equations. Green’s function plays a great role for solving such differential equations