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Öğe Discernment of Static Eccentricity and Electrical Load Unbalance Currents through Space Vector Stray Flux in Permanent Magnet Synchronous Generator based Wind Turbines(Institute of Electrical and Electronics Engineers Inc., 2023) Aladag I.; Goktas T.; Arkan M.The usage of permanent magnet synchronous generators (PMSGs) in wind turbines are getting increase due to their high efficacy and power densities. However, the electrical and mechanical asymmetries such as eccentricity and electrical load unbalanced currents can affect the dynamic operation condition in PMSGs. This paper proposes to detect and discriminate electrical load unbalance current faults and static eccentricity through space vector stray flux in surface mounted PMSGs based wind turbines. The 2D-finite element results shows that it is not possible to discern the static eccentricity and load unbalance current fault since both faults exhibits same pattern in current and stray flux spectra in PMSGs. The harmonic at +5fs in positive sequence stray flux can be used to discriminate static eccentricity and electrical load unbalance faults in PMSGs. The proposed method yields more precise and certain results compared to classical phase current and single point stray flux analysis. © 2023 IEEE.Öğe Dural bone defects and encephalocele associated with chronic otitis media or its surgery(2002) Kizilay A.; Aladag I.; Cokkeser Y.; Ozturan O.OBJECTIVES: We investigated the incidence of dural bone defects and encephalocele following radical mastoidectomy or open cavity tympanoplasty. PATIENTS AND METHODS: We retrospectively evaluated 190 operations of 182 patients (97 males, 85 females; mean age 30.6 years; range 9 to 70 years) who underwent radical mastoidectomy (n=89) or open cavity tympanoplasty (n=101). Follow-up examinations included otomicroscopy. Patients with documented dural bone defects on examination or operation records were further evaluated by axial and coronal computed tomography scans of the temporal bone. Those with suspected encephalocele were studied by magnetic resonance imaging. RESULTS: Dural bone defects were detected in 17 patients perioperatively. Of these, 14 defects were associated with chronic otitis media. Three iatrogenic bone defects were induced during obliteration of lateral sinus thrombosis. The mastoid tegmen was the most common site of defects (41%) and the most common etiologic factor was cholesteatoma (84%). Encephalocele was detected in one patient in whom radical mastoidectomy with lateral sinus obliteration was performed due to lateral sinus thrombophlebitis. Encephalomalasia was found nearby the defect area in two patients. CONCLUSION: Dural bone defects associated with chronic otitis media are not rare, the most common cause being cholesteatoma. Repair of dural lacerations requires watertight closure to prevent the occurrence of encephalocele.Öğe Successful use of botulinum toxin injection in the treatment of salivary fistula following parotidectomy(2003) Kizilay A.; Aladag I.; Ozturan O.A twenty-year-old woman underwent right superficial parotidectomy for pleomorphic adenoma. On the 10th postoperative day she presented with a salivary fistula, for which repeated aspirations with pressure dressings were applied for a month. Despite decreases in the salivary fluid volume, reaccumulation persisted. Following aspiration of the salivary fluid, 40 units of botulinum toxin was injected into the pouch. On the second day of injection, the discharge ceased and the pouch disappeared. No side effects were observed and the patient remained symptom-free during four-month follow-up.
