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Öğe Comparation of PI and Neural Fuzzy Based Closed Loop Control Methods for Permanent Magnet Synchronous Motor Fed by Matrix Converter(Ieee, 2015) Yakut, Yurdagul Bentesen; Sunter, Sedat; Ozdemir, MehmetPermanent magnet synchronous machines are used in many industrial applications today. In particular, depending on the developments in magnetic materials, permanent magnet synchronous motors rapidly developing in recent years have found themselves a widespread coverage in applications because of their outstanding features. When the research in the literature is surveyed, it is observed that the vector control of electrical machines is done by means of various methods. One of the most common applications of artificial intelligence used in the analysis of electrical machines is Neuro-Fuzzy, a combination of Fuzzy Logic and Neural Network. In this paper, the vector control of PMSM fed by a matrix converter is modeled and simulated by using PI controllers and Neuro-Fuzzy, one of the intelligent methods. Waveforms derived from the simulation of the vector control of PMSM fed by a matrix converter were examined comparatively for PI and Neuro-fuzzy controllers.Öğe A CONTROL METHOD FOR DRIVING DUAL PERMANENT MAGNET SYNCHRONOUS MOTORS FED BY SINGLE MATRIX CONVERTER(Univ Osijek, Tech Fac, 2017) Yakut, Yurdagul Bentesen; Sunter, Sedat; Ozdemir, MehmetIn this study, a control method is created to drive two parallel-connected permanent magnet synchronous motors fed by a single converter. Matrix converter used in this work provides ac-ac conversion in one stage. The matrix converter model and d-q model of dual PMSMs are performed in Matlab/Simulink. In industrial applications containing dual motors fed from a single converter, volume and weight of the drive system decreases, power electronics switches and other components are reduced and the installation cost decreases. Because of these advantages, many methods are being developed by researchers to control the dual motor drives. In this study, the motor control has been performed by using the average speed method. Control of dual permanent magnet synchronous motors with a single converter is implemented with ANFIS-based neural fuzzy controllers. All parameters of the motors are taken equal since two identical permanent magnet synchronous motors are considered. Two various operation conditions are investigated in the simulation. In the first case, one of the identical motors is operated on no-load, while the other one is operated with the rated load. In the second case, each motor is operated with various load torques varying with the time. Corresponding simulation results have been presented to show the performance of the drive system.Öğe Effectiveness of reverse first dorsal metatarsal artery flap for reconstruction of distal foot in electrical injuries(Elsevier Sci Ltd, 2025) Ozdemir, Mehmet; Akkoc, Mehmet Fatih; Selcuk, Caferi Tayyar; Erbatur, SerkanIntroduction: The severity of electrical injuries depends on the voltage, the duration of exposure to current, and the trajectory of the current through the body. The reconstruction for defects caused by electric current is a difficult process. Objective: The purpose of this study is to investigate the effectiveness of the reverse first dorsal metatarsal artery (FDMA) flap in the reconstruction of distal foot injuries caused by electric currents. Method: This is an observational and descriptive study. Reverse FDMA flaps were used in 21 patients with defects in the distal of their feet as a consequence of electrical injuries, and their outcomes were observed. Descriptive statistical methods were used in the analyses of the data. Results: While 57.1 % of the patients were between 18 and 35 years old, 3 patients were children, and 81 % of the patients were male. The site of the defect was the right sole/dorsum in 33.4 % of the cases and the right great toe in 28.6 %. Twenty patients (95.6 %) were exposed to high-voltage electric current. The dimensions of the defects of 42.9 % of the patients were 5-8 cm x 2-4 cm. Wound dehiscence was seen in 1 diabetic patient, and superficial flap necrosis developed in a young male patient with no health problems other than his electrical injury. Angiography was not performed on any patient. Conclusion: The reverse FDMA flap is a safe and effective method for the reconstruction for electrical injuries developing in the distal foot in which one-stage surgery is sufficient. We recommend the usage of the reverse FDMA flap for the closure of soft tissue defects caused by electrical injury in the sole, dorsal region of the foot, and great toes.Öğe Examining the Plastic Surgery Treatments Applied to Upper Extremities of Kahramanmaraş Earthquake Victims with Crush Injury(Wolters Kluwer Medknow Publications, 2025) Akkoc, Mehmet Fatih; Ozdemir, Mehmet; Ozel, VolkanAim: This study aims to examine earthquake-related upper extremity orthopedic injuries, and in our clinic, the plastic, reconstructive, and esthetic treatment methods applied to them after the two biggest earthquakes in Kahramanmara & scedil;, Turkey. Materials and Methods: This is a descriptive cross-sectional study and was conducted with 38 earthquake victims who were treated at the plastic, reconstructive, and esthetic surgery unit of a medical school health and research hospital in the Southeast Anatolia region of Turkey. Patient data were obtained retrospectively from electronic medical records, and descriptive statistical methods, Chi-square test, and post hoc were used for data analysis. Results: Of the earthquake victims, 55% were between 18 and 35 years old, 68% were female, 63% underwent plastic, reconstructive, and esthetic surgery due to upper extremity injuries, 50% had skin grafting, and 15% had amputation. In addition, 18.4% of the earthquake victims underwent surgery 3 times, and 13% were operated on 7 times. Conclusion: Careful attention should be paid to the treatment of upper extremity injuries that occur during major earthquakes. Delayed or inadequate interventions can result in amputation, highlighting the importance of plastic, reconstructive, and esthetic surgeons in disaster response teams. If possible, conservative treatment should be preferred for fractures in disaster environments. Amputation should always be the last treatment option for crush injuries. In cases requiring surgery, time should not be wasted.Öğe Implementation of a flywheel energy storage system for space applications(Tubitak Scientific & Technological Research Council Turkey, 2017) Celikel, Resat; Ozdemir, Mehmet; Aydogmus, OmurA satellite power system requires solar panels to provide energy and orientation. There are two regions in the orbital path of the satellite: the dark and bright region. The energy is provided by solar panels in the bright region and by flywheel energy storage system (FESS) in the dark region. Brushless DC (BLDC) motors are widely used in the FESS due to their low weight, high power density, high efficiency, high reliability, and high speed. Some mechanical resonances may occur due to physical features of the mechanical parts. Therefore, the current of the BLDC is dramatically increased because of the mechanical resonance. In this work, a current reference method was used to protect the power systems of the satellite from the current spikes of the solar power system. The parameters of the PI controller were calculated by using genetic algorithms. A FESS was designed and experimentally performed for high speed operation at about 20 krpm in the vacuumed environment.Öğe Keller Funnel Efficacy in No Touch Breast Augmentation and Reconstruction: A Systematic Review(Lippincott Williams & Wilkins, 2022) Morkuzu, Suat; Ozdemir, Mehmet; Leach, Garrison A. A.; Kanapathy, Muholan; Mosahebi, Afshin; Reid, Chris M. M.Background:Breast augmentation is one of the most common aesthetic surgical procedures. Tissue expansion followed by permanent implants is the most frequent postmastectomy breast reconstruction method. Implant contamination remains a critical problem with these procedures, resulting in acute infection as well as capsular contracture. To reduce the risk of implant contamination, the no-touch technique utilizing the Keller funnel has been adopted by many surgeons. This systematic review aims to investigate the advantages of the Keller funnel method for breast augmentation-reconstruction. Methods:A systematic review of PubMed, Embase, the Cochrane database, and Google Scholar was performed between 2005 and 2021. All clinical-based, retrospective and prospective studies utilizing the Keller funnel method for breast implant insertion were selected. Results:Six studies were identified for evaluation: five were retrospective cohorts and one was a prospective trial. No randomized controlled trials were found. Outcomes reported included lower rates of capsular contracture (RR, 0.42; P = 0.0006; 95% CI, 0.25-0.69), shorter incision lengths (35.5 +/- 2.1 mm), less insertion time (mean = 6 seconds), and decreased complications, and one paper reported ultimately greater patient satisfaction with outcomes (BREAST-Q Score: 92%). Conclusions:This review suggests that the Keller funnel is a useful method for no-touch breast augmentation and reconstruction surgery. The Keller funnel reduces subsequent capsular contracture rate, surgical time, and incision length and allows for easier insertion. However, our findings support recommendation of a prospective randomized controlled clinical trial with larger population size and follow-up intervals.Öğe A Multicenter Evaluation of Blood Culture Practices, Contamination Rates, and the Distribution of Causative Bacteria(Briefland, 2016) Altindis, Mustafa; Koroglu, Mehmet; Demiray, Tayfur; Dal, Tuba; Ozdemir, Mehmet; Sengil, Ahmet Zeki; Atasoy, Ali RizaBackground: The prognostic value of blood culture testing in the diagnosis of bacteremia is limited by contamination. Objectives: In this multicenter study, the aim was to evaluate the contamination rates of blood cultures as well as the parameters that affect the culture results. Materials and Methods: Sample collection practices and culture data obtained from 16 university/research hospitals were retrospectively evaluated. A total of 214,340 blood samples from 43,254 patients admitted to the centers in 2013 were included in this study. The blood culture results were evaluated based on the three phases of laboratory testing: the pre-analytic, the analytic, and the post-analytic phase. Results: Blood samples were obtained from the patients through either the peripheral venous route (64%) or an intravascular catheter (36%). Povidone-iodine (60%) or alcohol (40%) was applied to disinfect the skin. Of the 16 centers, 62.5% have no dedicated phlebotomy team, 68.7% employed a blood culture system, 86.7% conducted additional studies with pediatric bottles, and 43.7% with anaerobic bottles. One center maintained a blood culture quality control study. The average growth rate in the bottles of blood cultures during the defined period (1259 -26,400/year) was 32.3%. Of the growing microorganisms, 67% were causative agents, while 33% were contaminants. The contamination rates of the centers ranged from 1% to 17%. The average growth time for the causative bacteria was 21.4 hours, while it was 36.3 hours for the contaminant bacteria. The most commonly isolated pathogens were Escherichia coli (22.45%) and coagulase-negative staphylococci (CoNS) (20.11%). Further, the most frequently identified contaminant bacteria were CoNS (44.04%). Conclusions: The high contamination rates were remarkable in this study. We suggest that the hospitals' staff should be better trained in blood sample collection and processing. Sterile glove usage, alcohol usage for disinfection, the presence of a phlebotomy team, and quality control studies may all contribute to decreasing the contamination rates. Health policy makers should therefore provide the necessary financial support to obtain the required materials and equipment.Öğe A Progressed Case of Stewart-Treves Syndrome in a Patient with Chronic Idiopathic Lymphedema in the Lower Extremity(Wolters Kluwer Medknow Publications, 2019) Ozdemir, Mehmet; Sultany, Mohammed Suleiman; Celikkaleli, Ercan; Ozalp, BurhanAngiosarcomas are uncommon malignant tumors that arise from vascular endothelial cells with poor prognosis. Stewart-Treves syndrome (STS) is a type of cutaneous angiosarcoma that develops in chronic lymphedema. Although the majority of lymphangiosarcomas arise from areas of lymphedema as a consequence of lymph node dissection in radical mastectomy, it has also occurred in other causes of lymphedema. In the pathophysiology of lymphangiosarcoma, impairment of the local immune response and induced angiogenesis are emphasized. A 69-year-old male patient with a previous diagnosis of chronic lymphedema in his left lower limb presented with STS and widespread metastases. The patient refused the treatment for lymphedema and ignored the lesion due to its innocuous appearance. In addition, during the presentation, he had Stage 4 disease and, therefore, he was not a candidate for curative operative treatment. Early tumor resection or limb amputation has the best outcomes in the treatment.Öğe Reconstruction for Skin Defects Occurring due to Resection of Midface Malignancies with Cervicofacial Advancement-Rotational Flap(Springer India, 2024) Akkoc, Mehmet Fatih; Ozdemir, Mehmet; Bayram, Mehmet; Bulbuloglu, SemraObjectiveThis study aims to present surgical experience and clinical outcomes regarding the reconstruction for malignancy-induced midfacial skin defects using varying patterns of cervicofacial advancement-rotational flaps (CARFs).MethodsThis is a descriptive study, and 25 patients with midfacial skin defect participated in this study. Defect repair was performed using CARF and descriptive statistics were used in data analysis.ResultsThe CARF was designed over perforators arising from branches of the anterior-based external carotid artery in all patients. 48% of the patients developed midfacial skin defects due to basal cell carcinoma, and 40% due to squamous cell carcinoma. Two patients developed ectropion, one patient developed base positivity, and one patient developed necrosis distal to the flap.DiscussionThe CARF has a good pattern and minimal tension, thus closing midface skin defects without bunching. The reconstruction for midfacial skin defects with CARF decreases both functional and aesthetic morbidity and improves patient outcomes.Öğe Reducing Mechanical Resonance Time of A Flywheel Energy Storage System by Using A Current Control Algorithm for Satellites(Gazi Univ, 2017) Celikel, Resat; Ozdemir, Mehmet; Aydogmus, OmurThe orbital period of a satellite is completed with two regions as defined bright and dark. The energy must be stored in the bright region of the orbital path. The flywheel energy stored systems are used to provide energy in the dark region. However, the flywheel mechanical systems have mechanical resonance problems which decrease the system performance. The brushless dc motor operates as a motor with undesirable high-current when exposed the mechanical resonance. In this paper, a current reference method is proposed to decrease the current spike and reduce the time period of the mechanical resonance. The performance of the proposed method has been demonstrated by using simulation results and experimental results.Öğe Sensorless vector control of a permanent magnet synchronuous motor with fuzzy logic observer(Springer, 2006) Gumus, Bilal; Ozdemir, MehmetIn this paper, a new method for sensorless vector control of a permanent magnet synchronous motor (PMSM) using a fuzzy logic observer is developed. This method is based on determination of rotor position and thereby speeds by estimating back-emf components which result from fuzzy logic observers. The rotor position angle and rotating speed are estimated by evaluating the instantaneous values of stator voltages and currents. The estimators are two fuzzy logic observers. They have two inputs: the estimated stator currents and the difference between the measured and estimated stator currents. In addition, the outputs of the fuzzy logic observers are the back-emf components in an alpha-beta reference frame. The proposed method was implemented using a MATLAB/Simulink software package program. The obtained results are within acceptable error limits for a wide speed range, from 40 rad/s up to 500 rad/s.
