College of Natural and Computational Sciences

Comparisons of Influences of Mass Densities of Fuel Briquettes Produced from Eucalyptus, Olive Tree, Sorghum Stalk and Khat Waste Raw Materials On Burning Times

2026-05-20T08:05:13Z

Comparisons of Influences of Mass Densities of Fuel Briquettes Produced from Eucalyptus, Olive Tree, Sorghum Stalk and Khat Waste Raw Materials On Burning Times Amente (Prof), Gelana; Mengistu (PhD), Birhanu; KASSAHUN, WONDWOSEN Global energy demand is rising, causing overexploitation of fossil fuels and environmental challenges. Renewable sources, especially biomass briquettes from residues, offer sustainable alternatives. Ethiopia relies heavily on unsustainable biomass, leading to deforestation and degradation. The rising demand for household energy in Ethiopia has intensified reliance on fuelwood and charcoal, contributing to deforestation and environmental degradation. This study investigates the potential of four locally available biomass raw materials Eucalyptus, Olive tree, Sorghum stalk, and Khat waste—for briquette production. Raw materials (20 kg each) were chopped, air-dried, and carbonized under limited oxygen to produce char powder. The resulting char was mixed with 10% clay binder and water, molded into cylindrical briquettes, and oven-dried. Performance tests were conducted using the water boiling method, measuring density, burning temperature, and effective cooking times. Results revealed significant differences in density and effective cooking time among the briquette types. Khat and Olive tree briquettes exhibited higher densities (0.442 and 0.476 g/cm³) and sustained heating, maintaining water temperatures above 75°C for 101 and 73 minutes, respectively. Sorghum briquettes showed the highest peak temperature (96°C) but had short endurance (40 minutes), while Eucalyptus briquettes demonstrated the lowest density and inconsistent burning behavior, averaging only 31 minutes above 75°C. ANOVA confirmed significant differences (p < 0.05) among treatments, indicating that raw material type strongly influences briquette performance. The findings suggest that Khat waste and Olive tree residues are the most promising biomass feed stocks for producing efficient and sustainable fuel briquettes in Ethiopia, offering a renewable alternative to fuel wood and charcoal while addressing waste management and deforestation concerns. 42

A FLUID QUEUE DRIVEN BY SINGLE SERVER MARKOVIAN QUEUE WITH VARIANT WORKING VACATIONS

2026-05-20T07:41:53Z

A FLUID QUEUE DRIVEN BY SINGLE SERVER MARKOVIAN QUEUE WITH VARIANT WORKING VACATIONS LAMORE ADE, TSEGAYE; Demie (PhD), Seleshi; t Alemayehu (PhD), Getine In this thesis a fluid queue driven by single server Markovian queue with variant working vacation was investigated. Queuing theory is a mathematical approach that studies and models waiting lines. A fluid Queue is an input output system the customers are modeled as a continuous fluid that enters and leaves a storage device, called Buffer, Where the background process is governed by a single server Markovian queue. Fluid queues are powerfully applied across diverse fields to model systems where a continuous workload accumulates and depletes under rates controlled by a random environment, typically a Markov chain. In telecommunications, they model data buffers in routers and wireless networks with fluctuating traffic and channel capacity. In manufacturing, they represent continuous-flow production lines subject to machine breakdowns, while in finance, they analyze cash reserves in insurance and dam-based company models. The study focuses on formulating governing equations for background process model and fluid model, the closed-form solutions for steady state probabilities of the system were obtained by applying probability generating functions methods. Various performance measures of the system such as buffer content distribution, mean buffer content, server utilization were obtained. The model captures the dynamics of the system under working vacation polices, where the server operates at a reduced rate rather than being completely idle. Numerical computations were performed by MATLAB software to validate the theoretical results and analyze the system performance under various parameter settings. The findings provide insights into the behavior of fluid queues influenced by Markovian driven vacation polices, contributing to the broader understanding of queuing systems with server vacations. 47

THE EFFECT OF USING CONTEXT BASED-APPROACH ON THE CONCEPT OF GAS LAWS ON STUDENTS’ ACHIEVEMENT AND ATTITUDE

2026-05-20T07:11:28Z

THE EFFECT OF USING CONTEXT BASED-APPROACH ON THE CONCEPT OF GAS LAWS ON STUDENTS’ ACHIEVEMENT AND ATTITUDE Eliyas Burqa Usman; Ayalew Temesgen (PhD); Yiheyis Bogale (PhD) The study was aimed to evaluate the effect of using a Context-Based Approach (CBA) on the concept of gas laws on students' understanding and attitude. The study conducted at Ejersa Goro secondary school in Oromia region, Ethiopia. The research focused on the physical state of matter, specifically Boyle's, Charles', and Gay-Lussac's gas laws, which are fundamental concepts in secondary school chemistry with applications in various sciencerelated fields. The study employed quasi-experimental research approach, which contains experimental, control groups, and involved 72 grade 9 students selected by convenience sampling techniques. The experimental group received CBA instruction, while the control group received traditional instruction. The data were collected using pretests, posttests, retention tests, questionnaires, interviews, and observations. The study found that CBA significantly improved students' understanding and retention of gas law at each conceptual level (macro, micro, symbolic and graphical representation). The experimental group also showed a positive attitude toward CBA. The study concluded that CBA is a more effective instructional method than traditional teaching for enhancing students' understanding and retention of gas laws. The findings suggested that CBA is effective instructional approach and better if integrated into chemistry instructions to improve students' academic achievement and attitudes toward learning gas-law. 104p.

MODELING AND ANALYZING DIARRHEAL DISEASE DYNAMICS USING CONTROL MEASURES

2025-05-07T07:18:16Z

MODELING AND ANALYZING DIARRHEAL DISEASE DYNAMICS USING CONTROL MEASURES Bizuayehu Seyoum Zalale; (PhD) Getachew Teshome; (PhD) Melisew Tesfera In this study, a mathematical model to analyze the dynamics of a chronic water-borne disease known as diarrhea is developed. To achieve the objectives of this study work, secondary data on the population under five years of age from Bishoftu General Hospital between 2020 and March 2024 is collected. These populations were categorized as newborn, vaccinated, infected, and treated. Based on the epidemiological behavior of the diarrhea disease, a deterministic model is formulated by dividing the total population into seven classes. This model accounts for preventive interventions through vaccination and control measures through treatment. Since diarrhea is caused by pathogens that can survive and reproduce in water at specific temperatures and salinities, so we considered the pathogens as a compartment in the model. Our findings revealed that this water-borne disease can lead to serious infections. The qualitative behavior of the models, including the existence of equilibrium points, basic reproductive number of the model, and stability analysis of equilibrium points were analyzed. Using the collected data, some parameters value were estimated while value some others parameters were received from related publications, and based on the behavior of these disease the values left parameters where assumed. To determine the effect of parameters on the dynamics of the disease, a numerical simulation was performed and displayed the results in a graph using MATLAB 2019 computer software. The results show that increasing the rate of vaccination and treatment plays a crucial role in controlling the dynamics of diarrhea. Therefore, in order to eliminate diarrhea in the community, it is essential for stakeholders to consider these prevention strategies and control measures 62p.