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Öğe ANALYSIS OF THE DISCONTINUOUS PWM CONTROLLED D-STATCOM FOR REACTIVE POWER COMPENSATION APPLICATIONS(Univ Osijek, Tech Fac, 2014) Ertay, Muhammed Mustafa; Zengin, AhmetThe scope of this paper covers the investigations of discontinuous PWM (DPWM) control of the Distribution Static Synchronous Compensator (D-STATCOM). Various DPWM methods have been widely used in motor drives for controlling the inverter and reducing power losses. With the rising demand for energy, energy efficiency has currently become an issue of vital importance. As a result, the use of the D-STATCOM in distribution systems is becoming increasingly common. In this study, DPWM methods were used for the D-STATCOM inner control. For the outer control, phase angle control was used and PWM methods were adapted to this control algorithm. In addition, conventional continuous PWM (CPWM) methods were applied to the D-STATCOM for comparison purposes. All simulations were performed in the MATLAB-Simulink software environment. Power losses have a significant impact on the D-STATCOM; therefore, a simulation model was developed to calculate the conduction and switching losses in order to investigate the effectiveness of DPWM methods in reducing the D-STATCOM power losses. Results showed that the utilization of different DPWM methods in the D-STATCOM was suitable for high modulation indexes. This clearly illustrates that, according to different DPWM methods, a reduction of from 14 % up to 50 % in D-STATCOM switching losses can be achieved. Furthermore, this study proposes the use of CPWM and DPWM methods in low and high modulation indexes, respectively, according to the requirements of the distribution system.Öğe Analysis of the discontinuous PWM controlled D-STATCOM for reactive power compensation applications [Analiza diskontinuiranog PWM kontroliranog D-STATCOM-a u primjenama kompenzacije reaktivne energije](Strojarski Facultet, 2014) Ertay, Muhammed Mustafa; Zengin, AhmetThe scope of this paper covers the investigations of discontinuous PWM (DPWM) control of the Distribution Static Synchronous Compensator (D-STATCOM). Various DPWM methods have been widely used in motor drives for controlling the inverter and reducing power losses. With the rising demand for energy, energy efficiency has currently become an issue of vital importance. As a result, the use of the D-STATCOM in distribution systems is becoming increasingly common. In this study, DPWM methods were used for the D-STATCOM inner control. For the outer control, phase angle control was used and PWM methods were adapted to this control algorithm. In addition, conventional continuous PWM (CPWM) methods were applied to the D-STATCOM for comparison purposes. All simulations were performed in the MATLAB-Simulink software environment. Power losses have a significant impact on the D-STATCOM; therefore, a simulation model was developed to calculate the conduction and switching losses in order to investigate the effectiveness of DPWM methods in reducing the D-STATCOM power losses. Results showed that the utilization of different DPWM methods in the D-STATCOM was suitable for high modulation indexes. This clearly illustrates that, according to different DPWM methods, a reduction of from 14 % up to 50 % in D-STATCOM switching losses can be achieved. Furthermore, this study proposes the use of CPWM and DPWM methods in low and high modulation indexes, respectively, according to the requirements of the distribution system.Öğe AN APPROACH FOR DESIGNING PASSIVE POWER FILTERS FOR INDUSTRIAL POWER SYSTEMS BY USING GRAVITATIONAL SEARCH ALGORITHM(Univ Osijek, Tech Fac, 2015) Tosun, Salih; Öztürk, Ali; Ertay, M. Mustafa; Yalçın, Mehmet Ali; Zengin, AhmetHarmonics are one of the important factors in determining the energy quality in power systems. Hence, eliminating or damping undesired harmonics is crucial in electrical power systems. Due to their low costs, Passive Power Filters (PPF) are widely used in industrial power systems to limit harmonics' undesired affects. In this study, a new approach to design a PPF for power systems using heuristic Gravitational Search Algorithms (GSA) is proposed. Traditional Try and Error (TAE) method is, first, utilized to eliminate harmonics in our model power system. Then, GSA is adopted to minimize the effective current value of Point of Common Coupling (PCC) in the same model system. Our results yield that our proposed method with GSA eliminates the harmonics effectively.Öğe Does L-carnitine increase serum TNF -? and IGF-1 during liver regeneration in the rat?(2009) Pehlivan, Mevlüt; Coşkun, Abdurrahman; Zengin, Ahmet; Aslaner, Arif; Yavuz, TevfikAmaç: Rat deneysel parsiyel hepatektomi modelinde L-karnitin uygulamasının 72. saate kadar IGF- 1, TNF ? ve lipid peroksidasyonuna etkisini araştırmayı amaçladık. Yöntem ve gereç: Atmış rat kontrol, düşük (100 mg/kg) ve yüksek doz (200 mg/kg) L-karnitin olmak üzere 3 gruba ayrıldı. Her bir grup, parsiyel hepatektomiden sonra 24 ve 72. saat olmak üzere 2 alt gruba ayrıldı. Yedi gün intra-peritoneal L-karnitin uygulamasından sonra parsiyel (% 70) hepatektomi yapıldı. L-karnitin, parsiyel hepatektomiden sonra da ratlara verilmeye devam edildi. Tüm gruplarda cerrahi operasyondan önce, 24 ve 72 saat sonra serum IGF-1, TNF-? ve doku malondialdehid düzeyleri ölçüldü. Bulgular: Kontrol grubunda, serum TNF-? düzeyleri, rejenerasyon boyunca anlamlı derecede arttı. Düşük doz (100 mg/kg) L-karnitin, TNF-? düzeylerini azaltırken yüksek doz (200 mg/kg) artırdı. IGF-1 düzeyi, kontrol grubunda cerrahi operasyondan sonra ilk 24 saate azalırken daha sonra artmaya başladı. L-karnitin gruplarında IGF-1 düzeylerinde benzer değişimler gözlendi. Malondialdehid düzeyleri kontrol grubunda ilk 24 saatte artarken daha sonra azalmaya başladı. Benzer şekilde L-karnitin gruplarında malondialdehid düzeyleri ilk 24 saatte artarken daha sonra doza bağımlı olarak azaldı. Sonuç: Karaciğer rejenerasyonunda sitokinler, büyüme faktörleri ve metabolik yollar olmak üzere üç temel unsur bulunmaktadır. Enerji metabolizmasındaki etkilerine ilaveten, yüksek doz L-karnitinin, IGF-1, TNF-? düzeyini artırarak ve malondialdehid düzeyini de azaltarak karaciğer rejenerasyonunu hızlandırabileceğini düşünmekteyiz.Öğe Does L-carnitine increase serum TNF -alpha and IGF-1 during liver regeneration in the rat?(Tubitak Scientific & Technical Research Council Turkey, 2009) Pehlivan, Mevlüt; Coşkun, Abdurrahman; Zengin, Ahmet; Aslaner, Arif; Yavuz, TevfikAim: We sought to evaluate the effect of L-carnitine administration on the levels of IGF-1, TNF-alpha, and lipid peroxidation during hepatic regeneration for up to 72 h in an experimental partial hepatic resection rat model. Materials and methods: Sixty rats were divided into 3 groups: control and low-dose (100 mg/kg) and high-close (200 mg/kg) L-carnitine. Each group was divided into 2 sub groups (24 and 72 h after partial hepatectomy). Partial (70%) hepatectomy was performed after 7 days of intra-peritoneal administration of L-carnitine. After partial hepatectomy, L-carnitine was also administered to rats until sacrifice. Serum IGF-1, TNF-alpha, and tissue inalondialdehyde levels were determined in all groups before and at 24 and 72 h after surgery. Results: Serum TNF-alpha increased significantly in the control group during the regeneration period. The low close of L-carnitine (100 mg/kg) decreased the elevation of TNF-alpha whereas the high dose (200 mg/kg) increased it. In the control group, the IGF-1 level decreased in the first 24 h after surgery and then increased. The IGF-1 level behaved similarly in the L-carnitine groups. The inalondialdehyde level in the control group increased during the first 24 h and then decreased. Similarly in the L-carnitine groups, the malondialdehyde level increased during the first 24 h and then decreased significantly in a close-dependent manner. Conclusion: Three types of biochemical pathways are essential in liver regeneration: cytokine, growth factor, and metabolic pathways. We conclude that, in addition to its effects on energy metabolism, high-dose L-carnitine may promote liver regeneration by increasing IGF-1, TNF-alpha, and decreasing malondialdehyde.Öğe Emergency thoracic epidural anesthesia with ropivacaine for a cachectic geriatric patient with ileus(2006) Akbay, Buket Kocaman; Hayıt, Feray; Özaydın, İsmet; Zengin, Ahmet; Demiraran, YavuzObjective: Operations associated with increased risk of perioperative mortality and morbidity lead to consider regional anesthesia techniques for elderly patients. Epidural analgesia is used widely combined with general anesthesia. In this case, it is discussed whether solely thoracic epidural technique with ropivacaine provide appropriate anesthesia or not in emergency situations for elderly patients. Case Report: A 73-year-old cachectic male diagnosed with ileus was scheduled for an emergency laparotomy. He had congestive heart failure with hypertension, tachycardia and tachypnea with jugular venous distension. Thoracic epidural anesthesia were performed with ropivacaine 75 mg. Total colectomy and ileorectal anastomosis were performed. The patient discharged uneventful postoperatively. Conclusion: Epidural anesthesia with ropivacaine was provided fast and effective anesthesia without sedation in the elderly patient with ileus. This technique should be used safely especially with it's advantages for cardiovascular and pulmonary compromised elderly patients.Öğe Inflammatory fibrosarcoma: A rare tumor involving retroperitoneum, ileum and colon(2007) Yaşar, Mehmet; Aslaner, Arif; Zengin, Ahmet; Turgut, TanerAn inflammatory fibrosarcoma is a rare tumor with a varied biological behavior, from benign to locally aggressive and occasionally malignant. It generally involves mesentery and retroperitoneal structures, but it rarely can involve the hollow viscera and commonly affects children and young adults. We report a case of inflammatory fibrosarcoma affecting an unusual age group, involving the ileum and descending colon (a rare site) causing subacute intestinal obstruction. We also discuss its surgical management, differential diagnosis and review of current literature.Öğe Leakage detection and localization on water transportation pipelines: a multi-label classification approach(Springer London Ltd, 2017) Kayaalp, Fatih; Zengin, Ahmet; Kara, Resul; Zavrak, SultanOne of the main problems of water transportation pipelines is leak which can cause water resources loss, possible human injuries, and damages to the environment. There are many studies in the literature focusing on detection and localization of leaks in the water pipeline systems. In this study, we have designed a wireless sensor network-based real-time monitoring system to detect and locate the leaks on multiple positions on water pipelines by using pressure data. At first, the pressure data are collected from wireless pressure sensor nodes. After that, unlike from the previous works in the literature, both the detection and localization of leakages are carried out by using multi-label learning methods. We have used three multi-label classification methods which are RAkELd, BRkNN, and BR with SVM. After the evaluation and comparison of the methods with each other, we observe that the RAkELd method performs best on almost all measures with the accuracy ratio of 98%. As a result, multi-label classification methods can be used on the detection and localization of the leaks in the pipeline systems successfully.Öğe Simulated annealing based passive power filter design for a medium voltage power system(Praise Worthy Prize S.r.l, 2013) Ertay, Muhammed Mustafa; Tosun, Salih; Zengin, AhmetPower quality problems on distribution systems are becoming an increasingly important issue because the increase of harmonic current sources not only caused poor supply quality but also can be damaged the system components. As is known passive power filters (PPFs) have been mostly used to restrict the harmonic currents in industrial distribution systems. Aim of this paper is PPF design according to IEEE standards by using simulated annealing (SA) which is one of the heuristic techniques. The main idea behind the PPF design is the minimization of rms current of distribution bus. First of all harmonic analysis of studied industrial power system has been done. After this analysis, PPF design for mitigation of current harmonics and also power factor correction is realized firstly by using the try and error (TAE) method taking into consideration IEEE 519-1992 standards. Similar to that PPF design is realized by using proposed SA method. Effectiveness and convenience of the designed single tuned PPFs in limitation of the harmonic distortions are analyzed via computer simulations. Also the effects of frequency deviation on PPFs are studied. Simulation studies are carried out in Matlab/Simulink environment. © 2013 Praise Worthy Prize S.r.l. - All rights reserved.Öğe Simulated annealing based passive power filter design for a medium voltage power system [conferenceObject](2012) Ertay, Muhammed Mustafa; Tosun, Salih; Zengin, AhmetPower quality problems on distribution systems are becoming an increasingly important issue because the increase of harmonic current sources not only caused poor supply quality but also can be damaged the system components. As is known passive power filters (PPFs) have been mostly used to restrict the harmonic currents in industrial distribution systems. Aim of this paper is PPF design according to IEEE standards by using simulated annealing (SA) which is one of the heuristic techniques. The main idea behind the PPF design is the minimization of rms current of distribution bus. First of all harmonic analysis of studied industrial power system has been done. After this analysis, PPF design for mitigation of current harmonics and also power factor correction is realized firstly by using the try and error (TAE) method taking into consideration IEEE 519-1992 standards. Similar to that PPF design is realized by using proposed SA method. Effectiveness and convenience of the designed single tuned PPFs in limitation of the harmonic distortions are analyzed via computer simulations. Simulation studies are carried out in Matlab/Simulink environment. © 2012 IEEE.
