Biodiesel production from waste cooking oil is a potential feedstock to alternative fuel sources. Produced alternative fuel sources were to have a strong emphasis on energy efficiency to substitute the declining world supply of fossil fuels while also improving emission characteristics in diesel engine applications. The development of industrialization and mechanization causes increased fossil fuel consumption and its usage. This study aimed at an experimental investigation of biodiesel blended fuel combustion efficiency for single-cylinder diesel engines under varying engine loads at constant engine speed 1500 rpm. The transesterification process was used to produce biodiesel from waste cooking oil using NaOH as catalysts. Biodiesel reaction takes place with oil to methanol ratio of 6:1 at 60 °C reaction temperature for 90 min with 600 rpm stirring speed while 90% yield gained. Eight sample biodiesel blends were prepared with percentage value B5%, B10%, B15%, B20%, B25%, B30%, B35%, B40% v/v and B100% to investigate the effect of biodiesels on engine performances. The experimental result reveals that the mixed biodiesel blends have lower average value in terms of brake torque, brake power, and brake thermal efficiency than diesel fuels as a percentage of 16.79%, 4.08%, and 27.9% respectively. In addition, the average BSFC of biodiesel blends was increased by 4.8% than baseline diesel fuel. Related to exhaust gases emission test results were shows that the average CO and HC emissions decreased by 52.2% and 60% with increasing loads and blends and the increment of CO₂ and NOx by 28.1% and 45.4% respectively than baseline fuel with increasing blends and loads. Biodiesel derived from waste cooking oil was less costly and environmentally friendly and viable to substitute petro-diesel.

The production of these composites is prompted by the need for low-density materials for structural and automobile body parts that need to have excellent strength and wear resistance. This work aimed to fabricate an Al6061/SiC-reinforced material and assess its wear and friction qualities. The friction and wear properties of the Al6061/SiC composite materials with and without the addition of bagasse fly ash (BA) and aloe Vera ash (AA) were investigated by varying the weight percentage of reinforcements, and the results were presented and compared. 7.5, 10 wt. % SiC, 7.5,9, and 10 wt. % BA, and 6.5,9, and 11 wt. % AA used in this research. This hybrid composite was manufactured by stir casting and characterized by a pin-on-disc structure. The criteria employed to construct the composite were the weight, the ratio of powder mixing, the slurry being stirred at 600 rpm for 10 min, and the chemical composition of the reinforcements. The alloy Al6061 was melted at 710 °C. Al6061 10% SiC-10% bagasse ash and 11% aloe vera ash provided a low coefficient of friction and a value of 0.39. The results showed that the friction force and coefficient of friction were lower for the combination of 10% SiC-10% bagasse and 11% aloe vera ash. With a single addition of Al6061-10% SiC, a high weight loss of 0.1785 g was observed. A low average wear value (microns) was found for the combination of Al6061-10% SiC-10% bagasse ash and 11% aloe vera ash. It is concluded that adding bagasse and aloe vera ash greatly reduces the friction coefficient and enhances the wear properties. For this reason, auto manufacturers should take advantage of the information this study presents.

Contact stress arises in the wheel-rail because of the load imposed on the wheel. This stress on wheel leads to wear, distortion, and damage, increasing maintenance or replacement costs. This study primarily evaluates stresses in wheel-rail contact utilizing the FEM method to compare existing and newly developed wheel materials for their load-carrying capacity. A three-dimensional finite element analysis model of a wheel-rail system was created, and stress at a contact patch is calculated by applying a load. The study examines how the composition and hardness of materials affect stress distribution in wheel-rail contact. The composition of silicone, manganese, and carbon is increased to 0.5, 0.7 and 0.25% for the current wheel and to 0.8, 1.15 and 0.38% for the alloyed wheel. With a 0.82% increase in hardness for the alloyed wheel, the maximum equivalent (von-Mises) stress was found to be 0.26124 MPa for the existing wheel and 0.12907 MPa for the alloyed wheel. Finally, the result showed that the maximum deformation for the existing wheel was 0.0001225 mm, while for the alloyed wheel, it was 7.3088e-5 mm. Therefore, Addis Ababa Light Rail Transit and similar railway companies should consider the result of this study to improve their operations.

Particle shape is a significant factor influencing soil’s engineering behavior, affecting permeability, packing density, dilatancy, and shear strength. Angularity, a key element of particle morphology, provides insights into the transport history of sedimentary deposits. Current soil classification methods, such as those in the USCS and AASHTO systems, largely rely on sieve analysis, Atterberg limits, and hydrometer analysis. By neglecting particle shape, these methods can lead to inconsistencies in soil classification. Incorporating particle shape quantification, however, faces challenges, primarily the lack of accessible, cost-effective, and standardized measurement techniques. This study addresses this gap by quantifying the grain shape characteristics of granular soil samples collected from Addis Zemen town, Abay desert, and Lalibela town in Ethiopia. High-quality grain images were captured using microscopic imaging and analyzed using ImageJ software to determine roundness, circularity, and aspect ratio. The analysis revealed variations in roundness, with Abay sand exhibiting the highest value (0.78), followed by Addis Zemen sand (0.71) and Lalibela sand (0.69). This work contributes to a better understanding of soil properties in these regions and provides a basis for integrating particle shape into soil classification practices.