NUMERICAL DRAG REDUCTION OF A GROUND VEHICLE BY NACA2415 AIRFOIL STRUCTURED VORTEX GENERATOR AND SPOILER

Bayindirli Cihan 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.5

Using of computational fluid dynamics (CFD) have big advanteges for design process components in the automotive industry. Flow structures around vehicle and drag forces can investigate in CFD without producing real size prototype vehicle. The drag force affect fuel efficiency and drivability too. In this study, the drag coefficient of 1/15 scale minibus model was minimizated by NACA 2415 airfoil structured vortex generator and front spoiler in Fluent®. Flow analyses were performed at the 5 different free stream velocities in the range of 2.8 × 105  6.6 × 105 Reynolds numbers, where the dynamic similarity condition was provided. The drag coefficient of base minibus model was 0.415. The CD coefficient of the model minibus was decreased 10.94 % with original designed NACA 2415 airfoil structured vortex generator in model 1. In total of 22.59 % drag reduction was obtained by designed front spoiler. The effect of this drag reduction on fuel consumption about 6 ~ 12 % at high vehicle speeds.

Investigation of combustion and emission characteristics of n-hexane and n-hexadecane additives in diesel fuel

Cihan Bayindirli,Mehmet Celik 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4

One of the most important basic requirements of diesel-powered vehicles that they have lower pollutant emissions and fuel consumption. In diesel engines, combustion and engine performance are influenced by the physical and chemical properties of the used fuel. Engine design studies are not enough to increase engine performance and reduce exhaust emissions alone. By adding fuel additives in diesel fuel, the physical and chemical properties of the fuel can be improved. Fuel additives affect engine performance, combustion and emissions positively by exerting catalyst effect during combustion. In this study, n-hexane and n-hexadecane were added in diesel fuel (D0) by volume of 4, 12 % and 20 %. With respect to D0 fuel, in DHD20 and DHX20 fuels engine torque increased by 1.60 % and 1.32 %, respectively, while the brake specific fuel consumption decreased by 3.12 % and 1.98 %, respectively. Maximum cylinder pressures and heat release rate values of the ingredient added fuels increased. It was seen that NO x emissions increased while HC, CO and soot emissions decreased with increasing contribution ratio.

Acute Dystonia after Using Single Dose Duloxetine: Case Report

Gorkem Karakas,Ugurlu,Sinay Onen,Deniz BayindirLi,Ali Caykoylu 대한신경정신의학회 2013 PSYCHIATRY INVESTIGATION Vol.10 No.1

Duloxetine is a balanced and potent serotonin and noradrenaline reuptake inhibitor which is known to be effective in depression and anxiety disorders. The common adverse effects include dry mouth, nausea, insomnia, somnolence, dizziness and constipation. Reported adverse effects of the extra pyramidal symptoms (EPS) are rare. In this case, a patient who suffered from acute dystonia, after only one dose of 30 mg duloxetine is presented.

Experimental investigation of impact of addition of bioethanol in different biodiesels, on performance, combustion and emission characteristics

Mehmet Çelik,İlker Örs,Cihan Bayindirli,Mehmet Demiralp 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.11

This study includes the experimental evaluation of performance, combustion and emission characteristics of cottonseed and grapeseed biodiesels and blends containing bioethanol in a diesel engine with different engine speeds at full load. Addition of bioethanol into the fuels (diesel and biodiesel) used by diesel engines is considered an effective solution. The study observed that the cetane number, viscosity, density and lower heating value of fuel were reduced after the addition of bioethanol in all engine speeds. While the brake power and torque values were reduced as the rate of bioethanol increased, additionally specific fuel consumption, maximum cylinder pressure, heat release and ignition delay also increased. Reviewing the emission results, carbon monoxide (CO) and total hydrocarbon (THC) emissions increased as bioethanol rate increased, nitrogen oxides (NO x ) and smoke emissions were reduced.

Evaluation of the Protective Effect of Beta Glucan on Amikacin Ototoxicity Using Distortion Product Otoacoustic Emission Measurements in Rats

Tuba Bayindir,Aliye Filiz,Mustafa Iraz,Serdar Kaya,Mehmet Tan,Mahmut Tayyar Kalcioglu 대한이비인후과학회 2013 Clinical and Experimental Otorhinolaryngology Vol.6 No.1

Objectives. This experimental study investigated the possible protective effect of beta glucans on amikacin ototoxicity. Methods. Thirty-eight rats with normal distortion product otoacoustic emissions (DPOAEs) were divided into four groups. Group K was the control group. Group A was injected intramuscularly (i.m.) with amikacin 600 mg/kg/day between days 1-15. Group AB was given beta glucan gavage 1 mg/kg/day on days 0-15 and given amikacin 600 mg/kg/day i.m. on days 1-15. Group B was administered only beta glucan gavage, 1 mg/kg/day, on days 0-15. The DPOAEs were elicited in different frequency regions between 2,003 and 9,515 Hz, as distortion product diagrams (DPgrams), before and after the medication was administered, in all groups, on days 1, 5, 10, and 15. Results. No significant changes in the DPgrams were observed in group K. In group A, significant deterioration was observed at the 8,003 and 9,515 Hz frequencies on day 10, and at the 3,991, 4,557, 5,660, 6,726, 8,003, and 9,515 Hz frequencies on day 15. For group AB, statistically significant deterioration was observed at the 2,824, 8,003, and 9,515 Hz frequencies on day 15. The results for group B showed a significant improvement of hearing at the 2,378, 2,824, 3,363, and 3,991 Hz frequencies on day 1, at the 3,363, 3,991, and 8,003 Hz frequencies on day 10, and at the 8,003 Hz frequency on day 15. Conclusion. This study suggests that amikacin-induced hearing loss in rats may be limited to some extent by concomitant use of beta glucan.

Hybrid Fuzzy PI-Control Scheme for Quasi Multi-Pulse Interline Power Flow Controllers Including the P-Q Decoupling Feature

Vural, Ahmet Mete,Bayindir, Kamil Cagatay The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.5

Real and reactive power flows on a transmission line interact inherently. This situation degrades power flow controller performance when independent real and reactive power flow regulation is required. In this study, a quasi multi-pulse interline power flow controller (IPFC), consisting of eight six-pulse voltage source converters (VSC) switched at the fundamental frequency is proposed to control real and reactive power flows dynamically on a transmission line in response to a sequence of set-point changes formed by unit-step reference values. It is shown that the proposed hybrid fuzzy-PI commanded IPFC shows better decoupling performance than the parameter optimized PI controllers with analytically calculated feed-forward gains for decoupling. Comparative simulation studies are carried out on a 4-machine 4-bus test power system through a number of case studies. While only the fuzzy inference of the proposed control scheme has been modeled in MATLAB, the power system, converter power circuit, control and calculation blocks have been simulated in PSCAD/EMTDC by interfacing these two packages on-line.

Hybrid Fuzzy PI-Control Scheme for Quasi Multi-Pulse Interline Power Flow ControllersIncluding the P-Q Decoupling Feature

Ahmet Mete Vural,Kamil Cagatay Bayindir 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.5

Real and reactive power flows on a transmission line interact inherently. This situation degrades power flow controller performance when independent real and reactive power flow regulation is required. In this study, a quasi multi-pulse interline power flow controller (IPFC), consisting of eight six-pulse voltage source converters (VSC) switched at the fundamental frequency is proposed to control real and reactive power flows dynamically on a transmission line in response to a sequence of set-point changes formed by unit-step reference values. It is shown that the proposed hybrid fuzzy-PI commanded IPFC shows better decoupling performance than the parameter optimized PI controllers with analytically calculated feed-forward gains for decoupling. Comparative simulation studies are carried out on a 4-machine 4-bus test power system through a number of case studies. While only the fuzzy inference of the proposed control scheme has been modeled in MATLAB, the power system, converter power circuit, control and calculation blocks have been simulated in PSCAD/EMTDC by interfacing these two packages on-line.

Techno-Economic Optimization of a Grid-Connected Hybrid Energy System Considering Voltage Fluctuation

Samia Saib,Ahmed Gherbi,Abdelhamid Kaabeche,Ramazan Bayindir 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.2

This paper proposes an optimization approach of a grid-connected photovoltaic and wind hybrid energy system including energy storage considering voltage fluctuation in the electricity grid. A techno-economic analysis is carried out in order to minimize the size of hybrid system by considering the benefit-cost. Lithium-ion battery type is used for both managing the electricity selling to the grid and reducing voltage fluctuation. A new technique is developed to limit the voltage perturbation caused by the solar irradiance and the wind speed through determining the state-of-charge of battery for every hour of a day. Improved particle swarm optimization (PSO) methods, referred to as FCVACPSO which combines Fast Convergence Particle Swarm Optimization (FCPSO) method and Variable Acceleration Coefficient Based Particle Swarm Optimization (VACPSO) method are used to solve the optimization problem. A comparative study has been performed between standard PSO method and PSO based methods to extract the best size with the benefit cost. A sensitivity analysis has been studied for different kinds and costs of batteries, by considering variable and constant state-ofcharge of battery. The simulations, performed under Matlab environment, yield good results using the FC-VACPSO method regarding the convergence and the benefit cost of the hybrid system.

Comparison of 3D accuracy of three different digital intraoral scanners in full-arch implant impressions

Ozcan Akkal,Ismail Hakki Korkmaz,Funda Bayindir 대한치과보철학회 2023 The Journal of Advanced Prosthodontics Vol.15 No.4

PURPOSE. This in vitro study aimed to evaluate the performance of digital intraoral scanners in a completely edentulous patient with angled and parallel implants. MATERIALS AND METHODS. A total of 6 implants were placed at angulations of 0°, 5°, 0°, 0°, 15°, and 0° in regions #36, #34, #32, #42, #44, and #46, respectively, in a completely edentulous mandibular polyurethane model. Then, the study model created by connecting a scan body on the implants was scanned using a model scanner, and a 3D reference model was obtained. Three different intraoral scanners were used for digital impressions (PS group, TR group, and CS group, n = 10 in each group). The distances and angles between the scan bodies in these measurement groups were measured. RESULTS. While the Primescan (PS) impression group had the highest accuracy with 38 μm, the values of 104 μm and 171 μm were obtained with Trios 4 IOSs (TR) and Carestream 3600 (CS), respectively (P = .001). The CS scanner constituted the impression group with the highest deviation in terms of accuracy. In terms of dimensional differences in the angle parameter, a statistically significant difference was revealed among the mean deviation angle values according to the scanners (P < .001). While the lowest angular deviation was obtained with the PS impression group with 0.185°, the values of 0.499° and 1.250° were obtained with TR and CS, respectively. No statistically significant difference was detected among the impression groups in terms of precision values (P > .05). CONCLUSION. A statistically significant difference was found among the three digital impression groups upon comparing the impression accuracy. Implant angulation affected the impression accuracy of the digital impression groups. The most accurate impressions in terms of both distance and angle deviation were obtained with the PS impression group.

Techno-Economic Optimization of a Grid-Connected Hybrid Energy System Considering Voltage Fluctuation

Saib, Samia,Gherbi, Ahmed,Kaabeche, Abdelhamid,Bayindir, Ramazan The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.2

This paper proposes an optimization approach of a grid-connected photovoltaic and wind hybrid energy system including energy storage considering voltage fluctuation in the electricity grid. A techno-economic analysis is carried out in order to minimize the size of hybrid system by considering the benefit-cost. Lithium-ion battery type is used for both managing the electricity selling to the grid and reducing voltage fluctuation. A new technique is developed to limit the voltage perturbation caused by the solar irradiance and the wind speed through determining the state-of-charge of battery for every hour of a day. Improved particle swarm optimization (PSO) methods, referred to as FC-VACPSO which combines Fast Convergence Particle Swarm Optimization (FCPSO) method and Variable Acceleration Coefficient Based Particle Swarm Optimization (VACPSO) method are used to solve the optimization problem. A comparative study has been performed between standard PSO method and PSO based methods to extract the best size with the benefit cost. A sensitivity analysis has been studied for different kinds and costs of batteries, by considering variable and constant state-ofcharge of battery. The simulations, performed under Matlab environment, yield good results using the FC-VACPSO method regarding the convergence and the benefit cost of the hybrid system.