This study assesses automobile seat comfort by using a subjective evaluation system with road trials and by measuring seat pressure. The focus of this study is to demonstrate how drivers are affected by seat comfort under actual road conditions. All experiments were carried out with 55 participants driving for at least 2.5 h. Before the participants drove, the interface pressure was measured at 9 areas in the automobile. During the road trials, a comfort assessment was performed at 4 intervals: 0 min, 15 min, 75 min and 150 min. Participants were required to complete a questionnaire of 24 questions for each section. In total, 33 parameters were evaluated using related statistical techniques with SPSS. The participants felt discomfort after 75 minutes, and seat comfort was directly affected by thermal comfort parameters. However, overweight participants found the seat to be more comfortable than subjects with a normal BMI. Evaluating during road trials is difficult, but real traffic conditions affect comfort level. In future studies, real traffic situations should not be omitted when assessing comfort. This study will help to close the information gap in this area because comfort was evaluated on the road for at least 2.5 hours with subjective evaluation system.

In this study the aerodynamic characteristics of 1/32 scale truck and trailer model were examined in a wind tunnel. The acting drag force to model truck and trailer combination is calculated and aerodynamic drag coefficient is determined. The wind tunnel tests were carried out in the range of 160 000 - 449 000 Reynolds numbers. In order to improve the aerodynamics structure of truck- trailer, one spoiler, one passive air channel and three different redirector is produced in three dimensional printer. These aerodynamic parts respectively added to base truck-trailer model and obtaining aerodynamic improvement rates compared. According to wind tunnel test results, the aerodynamic improvement rates are respectively 15,62 %, 18,80 %, 23,58 % and 21,54 %. The lowest drag coefficient was determined as 0,588 on model-3 of truck-trailer model.

The major energy sources of the world depend on coal, natural gasses and petroleum which are exhaustible and environmentally unfriendly. Biodiesel is a mono alkyl organic compound of long chain of fatty acids made of oil from plant oils and animal fats that make use of a catalyst and an alcohol, which may be utilized in traditional diesel engines to function as an option for petro-diesel or blended with petro-diesel to diminish emissions. Kebericho seed oil which is endemic to Ethiopia was studied with the objective of investigating as a possible raw material for biodiesel production in this work. The kebericho seed that was extracted at 40 °C exploiting n-hexane as solvent yielded 26.7 %w/w oil. The Crude kebericho seed oil was transesterified at 60 °C for 90 minutes using oil/methanol ratio of 1:6 and 1% weight of KOH as a catalyst, to supply its resultant methyl ester compound. The resultant Kebericho oil methyl ester yield was found 92%. The fatty acid profile determination was carried out using gas chromatographic analysis and Kebericho oil methyl ester showed that it had been largely composed of palmitic, stearic, linoleic, oleic and linolenic esters that are comparable to the profile of sunflower, safflower and soybean oil. The fuel properties of Kebericho oil methyl ester were determined using the international standard for pure biodiesel using ASTM standard and each of the measured Kebericho oil methyl ester fuel properties were satisfied the ASTM D6751 biodiesel standards. Results from this study have clearly suggested the capability of kebericho seed oil as a biodiesel feedstock. Besides, as kebericho is thought to be invasive in Ethiopia, such conceivable outcomes of creating biodiesel from such species could be considered as one future management option with potential noteworthy economic returns and environmental advantages.

Vehicular exhaust emission control and engine efficiency are the most important parameters in current engine design. The Euro V emission norms aredirecting the research towards developing new technologies for combating engine emissions. Natural gas has become a widely used alternative fuel due to its many advantages including its ready availability and its low emission levels. Addition of hydrogen in CNG improves the composition and properties of base fuel CNG. In the present work adiesel engine was converted to operate in dual fuel engine mode in which Hydrogen-compressed natural gas (HCNG) was injected into the intake manifoldusing a specially developed electronic control unit (ECU) while diesel/biodiesel was injected directly inside the combustion chamber during the compression stroke. Experimental investigations were then carried out on a single cylinder four stroke CI engine test rig operatedin dual fuel mode using Diesel, Honge methyl ester (HOME),Jatropha methyl ester (JOME)as injected pilot fuels and HCNG as injectedprimary fuel.ECU was used for varying the injectiontimings and injection durations for HCNG injection while the optimum injection timing for diesel/biodieselwas maintained at 27°bTDC.The pilot fuel injection pressure was maintained at 230 bar. Engine was operated with constantcompression ratio of 17.5 and HCNG flow rate was maintained at 0.5kg/h. The experimental results showedthat an injection timing of 5obTDC and injection duration of 40obTDCfor HCNG injection was found to be optimum based on the improved performance, combustion and emission characteristics. The brake thermal efficiency formanifold injected HCNGdual fuel operation with diesel, HOME and JOME at 80% load was found to be 28.1%, 27.2% and 26.2% respectively. The Smoke emissions, Carbon monoxide (CO), Carbon dioxide (CO2) emissions were found to be lesser with aninjection timing of 5obTDC and injection duration of 40o bTDCin HCNG injected dual fuel operation.The use of HCNG manifold injection in the dual fuel operatedCI engine improves the performance and reduces the exhaust emissions from the engine except for HC and NOX emissions.

Energy demand at a global level is increasing day by day and fossil fuel resources are on the verge of becoming extinct. The drastic increase of the oil prices in the global oil market and the increased pollution levels created an interest to find renewable, sustainable and alternative fuels. Natural gas (NG) is considered as a most prominent alternative fuel due to its many advantages including its ready availability and its low emission levels. A diesel engine was converted to operate in dual fuel engine mode in which Compressed Natural Gas (CNG) was injected using a specially developed electronic control unit (ECU) into the intake manifold while injected pilot biodiesel autoignites and it becomes a source of ignition for CNG. Experimental investigations were conducted over a single cylinder water cooled four stroke dual fuel CI engine test rig operated using Diesel, Honge methyl ester (HOME), Jatropha methyl ester (JOME) and their blends with 15% ethanol as injected pilot fuels and CNG as injected primary fuel. ECU was used for varying the injection timings and injection durations for CNG injection while the optimum injection timing for diesel/biodiesel was maintained at 27°bTDC. The pilot fuel injection pressure was maintained at 230 bars. Engine was operated with constant compression ratio of 17.5 and CNG flow rate was maintained at 0.5 kg/h. The experimental results showed that an injection timing of 5obTDC and injection duration of 60o CA for CNG injection was found to be optimum based on the improved performance, combustion and emission characteristics. The brake thermal efficiency for manifold injected CNG- diesel/biodiesel-ethanol blended dual fuel operation at 80% load was found to be 27.1%, 26.2% and 25.2% for diesel- ethanol blend, HOME-ethanol blend and JOME-ethanol blends respectively. The carbon exhaust emissions and smoke emissions were found to be lesser in CNG injected dual fuel operation compared to CNG inducted dual fuel operation.

The control of the biodiesel production plays an important role on achieving the production standard of the biodiesel. The quality of the produced biodiesel depends on the raw materials, alcohol and catalyst selections and process and storage conditions. The control of the biodiesel production not only enables to achieve high quality biodiesel but also maintains the continuity of the product quality. In this work, an automation system for a two stage biodiesel production is designed and realized. A PLC (Programing Logic Control) based system is used for this purpose. The designed and realized biodiesel production facility enables to produce biodiesel using either a single stage or a two stage process. The quality of the biodiesels separately produced using a single stage and a two stage process are analysed and compared. The analysis results show that a two stage biodiesel production process gives better results compared to the single stage in fuel density, viscosity and flash point.

Studies have shown that road accidents usually result in rollover. Therefore, rollover dynamics is the most significant vehicle dynamics issues. The main objective of this study is to increase the safety margin of the commercial vehicle based on controlling the steering wheel angle because there are few studies on the steering control. As linear quadratic regulator and pole placement control systems were used as the controller in this paper, uncontrolled system was compared with the results of the controllers.