Browsing by Author "Hailemariam, Getachew"

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    Analytical Selection of Material for Lifan 520 model vehicle Brake Disc
    (AAU, 2018-06) Hailemariam, Getachew; Daniel, Tilahun (PhD)
    In automotive engineering sector, the safety aspect is a major consideration in development of a new vehicle. Each single system has been studied and developed in order to meet safety requirements. Widely Disc Type Brake used for this safety requirements and manufactured for first time in 1902 G.C in United Kingdom. In Braking time, the Kinetic energy of a Vehicle changed to heat energy. This high temperature leads to reduce the rotors performance and failures will occur. The existing material of Brake Disc has suitable properties to facilitate this reduction in performance of Brake Disc. The objective of this research is analytically, Selecting alternative material for Lifan 520 model vehicle Disc Brake Rotor. the weighting of material is done among Cast Iron, Stainless Steel, carbon-ceramic, Aluminum Metal Matrix composite and Titanium alloys. From those Candidate Materials, Digital Logic Methods (DLM) is a method used to Select suitable material for Brake Rotor. Density, wear rate, coefficient of friction, compressive strength, Specific heat and Cost are a property of Candidate materials that considered in selection of suitable material for brake disc by Digital Logic method. The result of this analysis shows that, Aluminum Metal Matrix composite (AMMC) is the material that higher value of figure of merit (FOM) from all above five Candidate materials. Therefore, this material is best material for Disc Brake than Gray Cast Iron (GCI). Lifan 520 model vehicle is selected for this purpose. Some variables such as: Deceleration of a vehicle, Stopping Distance, mass of Disc, deformation and Von-misses Stress on Brake Disc is calculated in order to see the visible differences between Disc Brake made from new(AMMC) and old(GCI) materials. A 3D Modeling of Disc Brake is done by SOLIDWORK 2018® modeling software and FEA ANSYS 18.2® is used to calculate mass of Disc, deformation and Von-misses Stress. Result obtained from Numerical and FEA showed that; Disc Brake made from AMMC reduce the mass by 62.4 %, increase Deceleration by 33.16%, Reduce Stopping Distance by 31.7%. Generally, it increases over all performance of Brake Disc by 8.7%. Therefore, based on Shown result, it can be concluding that Aluminum Metal Matrix composite (AMMC) material is the Suitable material for Lifan 520 brake disc.
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    Prototype Community Health Information Retrieval System for Jimma Zone: A Case Study of Jimma Institute of Health Sciences.
    (Addis Ababa University, 1998-06) Hailemariam, Getachew; Tadesse, Taye (PhD)
    For the enhancement of the economic development of a country, healthy and productive human resources are extremely needed. People should get adequate health care services to enable them to lead productive and meaningful life. In a third world country like Ethiopia, although many of the prevailing health problems are potentially preventable through the provision of appropriate primary health care services, the deteriorating health care service has made it difficult to control the existing health problems. One of the factors that is responsible for the deteriorating health care service is the absence of accurate, relevant and timely health information. In Ethiopia, the health information flows from regions to the center. At the regional level, the source of health information is the health facilities-based recording system. This form of information has failed to show the true picture of the health status of the people of the country. The other sources of health information such as community-based health information system and special studies have not been strengthened. Currently, Jimma Institute of Health Sciences has shown an endeavor to establish community-based health information system through its community-oriented/based educational program. This educational program is conducted in the actual or simi lar communities where students will serve after graduation. In this educational program, among other things, students gather health and health related data from both rural and urban communities in Jimma zone. The main objective of collecting such data is to integrate training, research, and health care services. However, this information has not been effectively used for the stated objective beyond the immediate academic exercises that students undertake. Piles of data collecting forms containing continuity health data collected for the past fourteen years are found in the data processing unit of the community-based educational program coordinating office. Although some efforts have recently been witnessed to enter the data into a computer, the conversion process had been undertaken before proper investigation was carried out. The main purpose of this study is to analyze the existing system and propose the design and development of appropriate computer-based information system. To this end, an effort has been made to understand what is being carried out by the current information system and identify the requirements of the improved system using different fact finding instruments. Specifically, facts were gathered through questionnaire, interview, discussions, document analysis and through critically observing the activities of the existing data processing unit. The findings of the survey reveals that the overall usage of the community health information is so minimal. Only 35.6% of the total respondents have used the data. • users are less satisfied with existing system.73.3% of the total respondents recommended change in the existing information system. • duplicate and redundant files were identified in the existing system. • the absence of standardized data collection formats have seriously affected the data storage, processing, and output generation. • Poorly organized community health information system is currently in place. The analysis of the facts collected has fac ilitated the identification of users requirements and databases to be designed and implemented. Based on the response of users, among the identified databases, detailed analysis and design of the socio- demographic database have been carried out. Conceptual data modeling techniques such as Entity Relationship Modeling and Relational Data Analys is have been employed to identify entities and to undertake analysis. Furthermore, to test the conceptual design and demonstrate how the improved system can be implemented, prototype databases and user interfaces are physically designed using Microsoft Access. Finally, recommendations are made for implementing the improved system and further studies to be carried out.