http://ir.haramaya.edu.et//hru/handle/123456789/3 2026-08-28T10:13:38Z http://ir.haramaya.edu.et//hru/handle/123456789/8700 The Central Field Approximation for Many Electron Atoms Assemahgn, Wondwosun The solution to the Schrodinger equation in case of Hydrogen atom (single particle) can be solved exactly. But if we consider many electron atoms the Schrodinger equation could not solved exactly due to the electron-electron term makes the solution inseparable in single-particle coordinates. However, we can estimate the solutions using different methods. so from those methods the Central Field Approximation provides an excellent starting point to deal with a many-electron system and even if further improvements on this are available and often employed, the Central Field Approximation scheme itself serves a very large number of applications. A set of Quantum defect were also performed and the results have been compared with that of the experimental values. the term quantum defect is a measure of the difference betwen an energy level and the corresponding one in hydrogen. That is the extent to which an outer (valence) electron of a given angular momentum penetrates the inner shell of the atom. While comparing the experimental and calculated values, we have stressed the role of centeral field approximation in Quantum defect theory, some suggestions for improvement of the results are also disscussed 62 2019-07-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/8693 Classification Of Jimma Coffee Beans Using Morphological and Color Features Lata, Teshale Image processing techniques have become increasingly useful in the vegetable industry, especially for applications in quality inspection and evaluation of food grains, fruits, vegetables, processed foods, and defect sorting. In this research work, we focused on the classification of Jimma coffee beans using morphological features (Limmu, Abba Buna, Yachi, and Buno wash), color, and morphological features extracted from 600 images. For each category, 150 images were captured. We used Artificial Neural Networks (ANN) to classify Jimma coffee beans based on the extracted features. Specifically, 15 color features and 8 morphological features, totaling 23 predominant features, were extracted from images of the four classes of coffee beans. We implemented a three-classification setup using color, morphology, and a combination of color and morphological datasets as inputs to the network. For the dataset considered, we allocated 70% (420 images) for training, 20% (120 images) for testing, and 10% (60 images) for validation. The accuracy of classification using color, morphology, and their combination were 74.8%, 75.0%, and 74.8%, respectively. The performance of the network was optimal for all classifications 67 2024-06-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/8682 MICROBIAL QUALITY AND HYGIENIC PRACTICES OF SELECTED FRESH FRUIT JUICES IN HARAR CITY, EASTERN ETHIOPIA Dejene Gurme; Zekeria Yusuf (PhD); Mulugeta Desta (PhD) Freshly prepared fruit juices are widely consumed in urban centers of Ethiopia due to their nutritional value, affordability, and accessibility. However, their microbiological safety remains a growing public health concern, particularly when juices are prepared under poor hygienic conditions. This study assessed the microbial quality and hygienic practices associated with mango (Mangifera indica) and avocado (Perseaamerican)juices vended in Harar city. A total of 20 juice samples (10 Mango and 10 Avocado) were collected from local juice houses such as Addot, Selam, Silase, TeshitaJuice, and Berger house between April and May 2022. Standard culture-based methods were employed to enumerate indicator organisms (total coliforms, fecal coliforms, Escherichia coli) and spoilage microbes (yeasts, molds, Staphylococcus species), and to detect selected pathogens (E. coli, Staphylococcus aureus, Salmonella, and Shigella). Additionally, a structured questionnaire was administered to 30 vendors and consumers to assess socio-demographic characteristics, awareness, and hygienic practices. Data was analyzed using descriptive statistics and chi-square tests. Results showed that both mango and avocado juices were contaminated with coliforms, E. colicounts ranging from 2.42 ± 0.05 to2.77 ± 0.08 log₁₀ cfu/mL. Staphylococcal counts were significantly higher in avocado juices (4.97 ± 0.15 log₁₀ cfu/mL) than in mango (4.30 ± 0.12 log₁₀ cfu/mL, p ≤ 0.05). Yeasts and molds exceeded Codex limits (≤3 log₁₀ cfu/mL) in all samples. Pathogen prevalence included E. coli (30% of samples), S. aureus (40–50%), Salmonella (10–20%), and Shigella (20% in avocado only). All juice samples failed to meet Codex microbiological standards, indicating potential health risks to consumers. Survey data revealed that most respondents were young (67% aged 21–23 years), lacked formal training in food hygiene (83%), and relied exclusively on untreated tap water during preparation.Hence, freshly prepared mango and avocado juices sold in Harar are unsafe for consumption due to high microbial loads and the presence of pathogens. So, it needs urgent interventions on food hygiene training for vendors, stricter regulatory monitoring, improved water quality, and consumer awareness campaigns to safeguard public health 48p. 2025-11-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/8676 MATHEMATICAL MODELLING OF CHIKUNGUNYA DISEASE DYNAMICS GETACHEW, FETENE In this thesis, we have adapted and modified the existing SEIR-SI Mathematical model by adjusting the vertical transmission in humans, where infected mothers pass the disease to newborns, and introducing insecticide spraying targeting the mosquito population to describe the transmission dynamics of Chikungunya disease. Mathematical analysis of the model yields the basic reproduction number, a key biological threshold parameter that determines disease persistence or elimination was calculated using the next-generation matrix method. The local stability of the disease free equilibrium and the endemic equilibrium was discussed using the Routh-Hurwitze criterion. Also, the global stability of both the disease free and the endemic equilibrium were performed using Lasselle’s invariance principle of Lyapunov functions. The results show that; if , then the disease free equilibrium is globally asymptotically stable, which leads to eradication of the disease and the current intervention (spraying) is effective. Conversely, if , then the endemic equilibrium becomes globally stable, which indicate that the persistence of the disease within the community and stronger intervention are required to bring below one. Sensitivity analysis highlights that the spraying insecticide rate has a significant negative impact on reproduction number, suggest that intensify vector control measures can effectively reduce disease transmission. Meanwhile, the vertical transmission rate has a moderate effect on increasing transmission. Numerical simulation was conducted using MATLAB software to confirm our analytic result 93 2025-11-01T00:00:00Z