Mustafa Atakan Akar

A Comparative Study of Estimation Methods for Parameters in Multiple Linear Regression Model

Abstract Cankaya, S., Kayaalp, G.T., Sangun, L., Tahtali, Y. and Akar, M. 2006. A comparative study of estimation methods for parameters in multiple linear regression model. J. Appl. Anim. Res., 29: 43–47. This paper investigated least squares method, non-parametric method and robust regression methods to predict the parameters of multiple regression models. To evaluate these methods, measurements of body weight, total length and fork length of fishes collected from Serranus cabrilla were used. In these regression models, body weight was dependent variable whereas total length and fork length were independent variables. The results show that non-parametric regression method, general additive model, has minimum R2 value and least median squares has maximum R2 value, 0.334 and 0.855, respectively.

Performance and emission characteristics of compression ignition engine operating with false flax biodiesel and butanol blends

In this study, fuel properties, engine performance, and emission characteristics of diesel fuel, false flax biodiesel, and their blends with butanol have been evaluated. Blend ratios used in this study were diesel–biodiesel–butanol (70% diesel–20% biodiesel–10% butanol and 60% diesel–20% biodiesel–20% butanol by volume) and biodiesel–diesel (20% biodiesel–80% diesel and 100% biodiesel by volume). Experiments showed that 10% alcohol addition to diesel and biodiesel fuels caused a decrease in torque value up to 8.57%. When butanol ratio raised to 20%, torque value decreased to an average of 12.7% and power values decreased to an average of 13.57%. Specific fuel consumption increased to an average of 10.63% and 12.80% with 10% and 20% butanol addition, respectively. Alcohol addiction into conventional diesel and biodiesel fuel slightly increased NOX emissions. Supplement of alcohol decreased CO and CO2 emissions when it was entrained to diesel and increased it when it was added to biodiesel. It means that addition of alcohol to diesel changed CO and CO2 emissions.

The Influence of Diesel Fuel-biodiesel-ethanol-butanol Blends on the Performance and Emission Characteristics of a Diesel Engine

In this study, performance and exhaust emissions of a diesel engine fueled with Fuel A (60% diesel–30% biodiesel–5% ethanol–5% butanol) and Fuel B (40% diesel–50% biodiesel–5% ethanol–5% butanol) were investigated. The biodiesel produced from trap grease was obtained with an oil separator. Fuel A and Fuel B were tested in a single cylinder, four-stroke diesel engine at full load conditions. Compared with diesel fuel, the performance characteristics of blend fuels slightly deteriorated while the emission characteristics improved significantly. CO and HC emissions decreased by 87.01 and 87.50%, respectively.

Effect of Spark Plug Alteration on Performance Using Hydrogen Enriched Gasoline in Si Engine Under Various Loads and Compression Ratios

In this study, change in brake power (BP) of a variable compression spark ignited engine was investigated with different spark plugs and hydrogen enrichment. The tests were carried out with a four stroke, single cylinder, naturally aspirated, variable compression ratio (VCR) engine. Two different compression ratios (CR) of 8.5:1 and 10:1 under %50 part throttle condition were implemented throughout the experiments. Moreover, engine loads of 8 Nm, 13 Nm and 17 Nm were applied to evaluate effects of different spark plugs and hydrogen usage at different engine loads. Copper, iridium and platinum spark plugs were tested for each experiment condition. In addition, hydrogen was added through the intake manifold with flow rates of 0, 2 and 4 lit/min to enhance combustion of VCR engine. According to test results, iridium and platinum spark plug usage, hydrogen addition and higher compression ratio improved BP significantly. This variance occurred more obvious with platinum spark plug usage comparing to iridium spark plug. In addition, effects of spark plug alteration, hydrogen addition and higher CR on enhancement of BP were comparatively lower at higher engine loads.