THE EFFECT OF EXHAUST BACKPRESSURE ON PERFORMANCE OF A DIESEL ENGINE: A NEURAL NETWORK BASED SENSITIVITY ANALYSIS

Yiğit Gülmez,Güner Özmen 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.1

Various types of emission-reducing systems or waste heat recovery systems installed on exhaust pipes of internal combustion engines are a source of high exhaust gas backpressure. Increased backpressure can cause negative impacts on the performance of internal combustion engines. This study aims to explore the relationship between exhaust gas backpressure and diesel engine performance indication parameters such as volumetric efficiency and brake specific fuel consumption. A neural network model was generated to identify the relation between the input variables (engine backpressure, engine speed, torque and exhaust temperature) and performance indicators (volumetric efficiency and brake specific fuel consumption). A single cylinder, naturally aspirated, 13 kW diesel engine was used for experiments and the results of the experiments were used to develop the neural network model. Then, a sensitivity analysis was performed to identify the influence of any input parameter including exhaust gas backpressure on volumetric efficiency and brake specific fuel consumption. The results of the study showed that engine backpressure is a critical parameter for both volumetric efficiency and fuel consumption. Besides, the study demonstrated that neural network modelling is a suitable method to explore the relationship between inputs and outputs of an internal combustion engine system.

Successful surgical intervention in traumatic carotid artery thrombosis after a motor vehicle accident: a case report

Yiğit Görkem 대한외상학회 2023 大韓外傷學會誌 Vol.36 No.1

Blunt carotid artery injury can lead to impaired brain perfusion due to ischemic stroke and thromboembolic events. To reduce the risk of potential neurological complications, it is critical to determine the diagnosis and management protocol as quickly as possible after a detailed clinical examination. This report presents successful surgical treatment of a young male patient who developed a traumatic left common carotid artery thrombosis after a motor vehicle accident.

The effects of cement thickness and cement shade on the final color of lithium disilicate crowns

Yiğit Yamalı,Merve Bankoğlu Güngör,Seçil Karakoca Nemli,Bilge Turhan Bal 대한치과보철학회 2023 The Journal of Advanced Prosthodontics Vol.15 No.2

Purpose. The aim of this study is to evaluate the effect of resin cement color, cement thickness, and thermocycling on the final color of monolithic lithium disilicate crowns. Materials and methods. A total of ninety prepared central incisors of typodont teeth were restored with lithium disilicate crowns which have different cement thicknesses (40 µm, 80 µm, and 120 µm) and cement shades (clear, yellow, and white). Color parameters of restorations were measured with a spectrophotometer in three different steps 1) before cementing 2) after cementing and 3) after thermocycling with 10000 cycles. Color differences (∆E00) were calculated with the CIEDE2000 formula and evaluated according to perceptibility (0.8) and acceptability (1.8) thresholds. The ∆E00 data were analyzed by using two-way ANOVA before and after thermocycling (α = .05). Results. There was no interaction between the cement shade and the cement thickness factors. After cementation, the mean ∆E00 was under the perceptibility threshold in the group of 40 µm cement thickness and clear cement while it was between the perceptibility and acceptability thresholds (0.8 < ∆E00 < 1.8) for all other groups. After thermocycling, the ∆E00 values were between the perceptibility and acceptability thresholds for all experimental groups. Although there were no significant differences among the groups, thermocycling increased the color difference values. Conclusion. The cementation of restorations with clear, yellow, and white resin cements resulted in color differences with uncemented restorations except for the group cemented with clear cement in 40 µm cement thickness. All study groups revealed perceptible color change after thermocycling. [J Adv Prosthodont 2023;15:93-100]

The electrical properties of ZnO/Si heterojunction diode depending on thin film thickness

Akın Ümmühan,Houimi Amina,Gezgin Bahri,Gündoğdu Yasemin,Kılıç Sümeyye,Mercimek Bedrettin,Berber Adnan,Gezgin Serap Yiğit 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.2

In this work, ZnO thin flms have been produced on p-Si wafer depending on number of laser pulses applied using pulse laser deposition (PLD) technique at room temperature conditions. Three diferent thicknesses of ZnO thin flms (ZnO1, ZnO2 and ZnO3) have been produced by applying 18,000, 36,000 and 54,000 laser pulses and thicknesses of these produced three thin flms have been measured to be 41 nm, 70 nm, 197 nm, respectively. It is observed in this work that while thicknesses of ZnO thin flms increases, crystal structure of thin flms develops, their grain size increase while their band gaps decrease. Ag/ZnO/ Si/Au heterojunction diodes have been produced based on ZnO1, ZnO2 and ZnO3 thin flms. After that, efect of thickness of thin flm on electrical properties of diodes produced depending on number of laser pulses has been analyzed in detail. I–V characteristics of ZnO/Si heterojunction diodes produced have also been measured in darkness environment and under illumination conditions (AM 1.5 solar radiation of 80 mW/cm2 ) and results obtained have been interpreted and a conclusion has been made in this work. Furthermore, ideality factors, barrier heights and serial resistivities of these diodes have been calculated using conventional thermionic emission theory, Norde and Cheung-Cheung methods and then results obtained from analytical methods have been interpreted in detail in the present article. ZnO heterojunction diodes have exhibited photovoltaic properties under illumination conditions. It has been observed that as thickness of ZnO thin flm is increased, Jsc and η values of the hetero junction diodes are increased. ZnO-3A hetero junction diode has exhibited the most improved photovoltaic performance. We have also theoretically investigated photo-electric properties of ZnO-3A heterojunction diode using SCAPS-1D packed software. The resulted J–V characteristics have been found very similar to measured counterparts.

A study on (n, α) reaction cross sections using a new empirical systematic

Küçüksucu Sema,Yiğit Mustafa 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.11

In this article, we report a new empirical formula for quick calculation of cross sections of (n, α) reactions with 14–15 MeV neutrons. Cross sections are analysed in terms of the compound nucleus model. A systematic trend for 14–15 MeV neutrons is found in the variation of (n, α) reaction cross sections with the parameters (N Z + 1), (En + Q)0.5 and N/Z. The empirical relation between the cross sections and these parameters has been obtained, which give fairly good fits with the experimental data. We have also investigated the odd-even effects on (n, α) cross sections considering binding energy systematic of the shell model. The present formula is very useful in predicting of the (n, α) cross sections, where the measurements are not available as well as in testing new experimental data.

Subglottic Laryngeal Perforation After Redo Thyroidectomy: A Case Report

Muhammed Adi Syazni,Türk Yiğit,Özdemir Murat,Öztürk Kerem,Makay Özer 대한내분비외과학회 2023 The Koreran journal of Endocrine Surgery Vol.23 No.3

Inadvertent airway injury is a rare complication of thyroidectomy that can be life-threatening. Most studies report injuries occurring within the tracheal region. In this report, we present a case of subglottic laryngeal perforation following completion thyroidectomy. Based on our literature review, we believe that this is the first report of such a case. Through a multidisciplinary approach, the patient was treated successfully with surgery. This article aims to emphasise that more proximal airway injuries may occur with thyroidectomy and explore the possible factors and treatment options.

Isolated penetrating gluteal stab injury with uncontrolled bleeding in Türkiye: a case report

( Ali Metehan Celep ),( Görkem Yiğit ),( Ayla Ece Çelikten ),( Kudret Atakan Tekin ),( Ufuk Türkmen ) 대한외상학회 2023 大韓外傷學會誌 Vol.36 No.4

Arterial injuries in the gluteal region caused by a knife are rare but serious, with mortality rates of up to 25%. This case report presents the management of a young male patient admitted to the emergency department in hypovolemic shock, with uncontrollable bleeding from an isolated penetrating gluteal injury. Additionally, the details of the surgical approach employed are discussed.

Can tumor recurrence be reduced with plasma-kinetic vaporization of the area around the tumor in nonmuscle invasive bladder cancer?

Yüksel Yılmaz,Mehmet Cemal Kahya,Fatma Hüsniye Dilek,Osman Köse,Serkan Özcan,Ertan Can,Yiğit Akın,Batuhan Ergani,Ahmet Selçuk Dindar 대한비뇨의학회 2018 Investigative and Clinical Urology Vol.59 No.4

Purpose: To investigate the effect on recurrence of vaporization of the tumor surroundings and suspicious areas with a plasma-kinetic (PK) system after transurethral resection (TUR) of nonmuscle invasive bladder cancer. Materials and Methods: The study included 121 patients with a primary superficial bladder tumor who were randomized as those who underwent TUR with the PK system (Group 1, n=62) and those who underwent TUR with the monopolar system (Group 2, n=59). The vaporization procedure was performed by suppressing the cutting option of the PK system for a period, which would accumulate energy sufficient to make swelling-waves on the mucosa very close to the area of the loop to be vaporized. Results: A total of 121 patients who met the study criteria were included for evaluation. Recurrence was determined in 21 patients in Group 1 (33.87%) and in 29 patients in Group 2 (49.15%) (p=0.088). Recurrence was close to the old resection site in 6 of 21 patients in Group 1, and in 13 patients in Group 2 (p=0.028); the difference was statistically significant. No statistically significant difference was determined between the two groups with respect to age, gender, number of tumor foci, rate or range of additional treatments applied, cigarette smoking rate, repeat TUR rate and rate of tumor en- countered in repeat TUR, T-stage, and tumor grade. Conclusions: The effect of vaporization on recurrence by the PK system may seem similar to the effect of standard TUR, the recurrence- lowering effect surrounding nonmuscle invasive bladder cancers is better.

Reparative, Neuroprotective and Anti-neurodegenerative Effects of Granulocyte Colony Stimulating Factor in Radiation-Induced Brain Injury Model

Gökhan Gürkan,Özüm Atasoy,Nilsu Çini,İbrahim Halil Sever,Bahattin Özkul,Gökhan Yaprak,Cansın Şirin,Yiğit Uyanıkgil,Ceren Kızmazoğlu,Mümin Alper Erdoğan,Oytun Erbaş 대한신경외과학회 2023 Journal of Korean neurosurgical society Vol.66 No.5

Objective : This animal model aimed to compare the rat group that received brain irradiation and did not receive additional treatment (only saline) and the rat group that underwent brain irradiation and received Granulocyte colony stimulating factor (G-CSF) treatment. In addition, the effects of G-CSF on brain functions were examined by magnetic resonance (MR) imaging and histopathologically. Methods : This study used 24 female Wistar albino rats. Drug administration (saline or G-CSF) was started at the beginning of the study and continued for 15 days after whole-brain radiotherapy (WBRT). WBRT was given on day 7 of the start of the study. At the end of 15 days, the behavioral tests, including the three-chamber sociability test, open field test, and passive avoidance learning test, were done. After the behavioral test, the animals performed the MR spectroscopy procedure. At the end of the study, cervical dislocation was applied to all animals. Results : G-CSF treatment positively affected the results of the three-chamber sociability test, open-space test and passive avoidance learning test, cornu Ammonis (CA) 1, CA3, and Purkinje neuron counts, and the brain levels of brain-derived neurotrophic factor and postsynaptic density protein-95. However, G-CSF treatment reduced the glial fibrillary acidic protein immunostaining index and brain levels of malondialdehyde, tumor necrosis factor-alpha, nuclear factor kappa-B, and lactate. In addition, on MR spectroscopy, G-CSF had a reversible effect on brain lactate levels. Conclusion : In this first designed brain irradiation animal model, which evaluated G-CSF effects, we observed that G-CSF had reparative, neuroprotective and anti-neurodegenerative effects and had increased neurotrophic factor expression, neuronal counts, and morphology changes. In addition, G-CSF had a proven lactate-lowering effect in MR spectroscopy and brain materials.

The Effect of High Dose Melatonin on Cardiac Ischemia- reperfusion Injury

Hakan Ceyran,Figen Narin,Nazmi Narin,Hülya Akgün,A. Bahar Ceyran,Figen Öztürk,Yiğit Akçah 연세대학교의과대학 2008 Yonsei medical journal Vol.49 No.5

Purpose: Melatonin, the most potent scavenger of toxic free radicals, has been found to be effective in protecting against pathological states due to the release of reactive oxygen species. This study was performed to establish the effect of high dose melatonin on protection against ischemia- reperfusion (I/R) injury in rat hearts. Materials and Methods: Forty male Sprague-Dawley rats were used in this study. They were separated into four groups of ten rats each. A left coronary artery occlusion was induced in the rats by ligating the artery for 20 minutes and then releasing the ligation (reperfusion) afterwards. The control group was Group A. Group B was subjected to myocardial ischemia-reperfusion without any treatment, while Group C underwent myocardial ischemia-reperfusion with a melatonin treatment before the ischemia. Group D was subjected to myocardial ischemia- reperfusion with a melatonin treatment before the reperfusion. After 20 minutes of reperfusion, blood samples were obtained from each group for biochemical studies, and the animals were sacrificed for histological and, immunohistochemical examinations of the myocardial tissue. Results: We found that the cardiac troponin T(cTn-T) levels were significantly increased in Group B when all groups were compared. In the Group C rats treated with melatonin, the cTn-T values were significantly lower than those in Groups B and D. In addition, malondialdehyde (MDA) and antioxidant enzymes including, superoxide dismutase (SOD) and myeloperoxidase (MPO) were lower than those in Group B in the melatonin treated groups. The differences were statistically significant (p<0.05). Histopathologic and immunohistopathologic studies also supported the effectiveness of melatonin. Conclusion: Our study suggests that high dose melatonin, appears to offer protection against cardiac ischemia-reperfusion injuries in rats by scavenging the free radicals and could have a potential clinical use in the management of myocardial ischemia.