Browsing by Author "Belay, Abebe"

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    Designing A Stemmer For Ge’ez Text Using Rule Based Approach
    (Addis Ababa University, 2010-07) Belay, Abebe; Abebe, Ermias (PhD)
    In this study, a stemmer of Ge’ez text was developed. In designing processes, different concepts such as background for the thesis, literatures on conflation of the stemming algorithms, morphological nature of Ge’ez language, stemming techniques and other realted things were discussed in order to model and develop an automatic procedure for conflation. When inflectional and derivational morphologies of the language were discussed, affixations such as prefixing, infixing and suffixing are the main word formation processes in Ge’ez language. The language is morphologically complex. This is because different words can be formed due to the wide concatenations of affixes. For the experiment, two techniques were used: affix removal and morphological analysis techniques. To evaluate the stemmer, manually error counting technique was used. From the experiment, three types of errors are observed: over stemmed (6%), under stemmed (4.27%) and structural problems (7.31%). When the stemmer runs on the sample texts, it performed with an accuracy of 82.42%. The dictionary reductions of the stemmer were 29.9% to the stemmed words and 62.8% to root words. Lastly, the possible recommendations to future works and improvements of this work were reported.
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    Spectrophotometric investigation of Major bioactive compounds of coffee Beans
    (Addis Ababa University, 2011-10) Belay, Abebe; Gholap, A.V. (Professor)
    In this research the methods of measuring major bioactive compounds in coffee beans, their optical transition properties, self-association, hetero-association and thermodynamic properties were investigated by experimental and computational methods. The implemented methods for determination the contents of biocactive compounds in coffee beans are the extraction of caffeine from water solution or liquid-liquid extraction and fitting Gaussian function to the spectrum of the compound by non-linear curve fitting based on the Lavenberg-Marquardt algorithm to eliminate the possible interferences. The contents of caffeine and chlorogenic acids determined by these methods for green coffee beans are in the ranges of 0.90-1.27 %, 6.05-6.25 % respectively. The optical transition properties of caffeine, caffeic and 5-caffeoylquinic acids were determined in different solvents by integrating the absorption coefficients in the wave number regions. The calculated values of transition dipole moment of caffeine, caffeic and 5-caffeoylquinic acids in water in their wave number regions are 10.40×10−30, 19×10−30, 20×10−30Cm respectively. The corresponding oscillator strength are 0.19, 0.49 and 0.56. The concentration dependent selfassociation of caffeic, 5-caffeoylquinic acids and their hetero-association were analyzed by dimer model and Benesi-Hildebrand approaches. The thermodynamic parameters, enthalpy, Gibbs free energy and entropy of dimerzation reactions were calculated from Van’t Hoff equation. The calculated molar enthalpy change for caffeic and 5-caffeoylquinic acids of self-association are -63.20, -12.89 kJmol−1 respectively.In addition, the time dependent Schrodinger equations were solved by semi-classical approach to relate the theoretical expressions with the experimentally measurable quantities