Ege University Institutional Repository
Not a member yet
116239 research outputs found
Sort by
Edge Co-Even Domination
No full textDomination is one of those important parameters in graph theory which has a very wide range of applications. There are various types of domination depending on the structure of dominating sets. In this study, a new domination parameter called edge co-even domination number is introduced and denoted by ?_coe^' (G). Some basic graphs such as path, cycle, complete, complete bipartite, star, regular, wheel and their complement graphs are examined of this definition. In addition, some results of this parameter are found under graph operations, such as corona and cartesian product
ASO Visual Abstract: Outcomes for Patients with Obesity Undergoing Adrenalectomy for Pheochromocytoma-An International Multicenter Analysis
No full text[Abstract Not Acaileble
Investigation of indoor radon levels in schools in the Bornova district of İzmir province
No full textConsidering modern life, people spend around 75% of our day indoors, where exposure to natural and man-made risks is common. One such risk is radon gas, the second leading cause of lung cancer. This study focused on indoor radon levels in three elementary schools in Bornova, Izmir, to assess annual radiation doses for students, teachers, and staff. The mean indoor radon was found to be 225.4 +/- 16.66% Bq m-3. The resulting doses ranged from 0.08 +/- 0.06 to 5.41 +/- 0.12 mSv y-1, all below the ICRP's recommended limit (3-10 mSv y-1), and were compared with international benchmarks for safety assessment.Trkiye Bilimsel ve Teknolojik Arascedil;timath;rma Kurumu [2209A]; TUBITAK; Directorate of National Education of Bornova DistrictThis study is supported by TUBITAK 2209A University Student Research Projects Support Program. We would like to thank the Directorate of National Education of Bornova District and the School Principals for their support. We sincerely thank the anonymous reviewers for their thoughtful suggestions that resulted in the final form of our manuscript, which is greatly improved by their suggestions
Comparison of direct model predictive control methods for permanent magnet synchronous motor control
No full textPermanent magnet synchronous motors are widely preferred in many areas due to the advantages they offer. On the other hand, the rapid development of direct model predictive control methods in controlling power converters and electric motor drives has reinforced the success of these control methods in these areas. This study compares four different direct model predictive control methods in the context of permanent magnet synchronous motor control. The main motivation of this study is the absence of research in the literature comparing these four methods and the fact that existing studies focus only on control performance. Unlike the existing comparisons, this study evaluates the selected methods not only in terms of control performance but also in terms of design complexity and computational burden. The comparisons are based on simulation studies, considering various operating conditions of electric drive systems, such as four-quadrant operation, speed variations under load, and load variations at constant speed. The results obtained demonstrate that all these direct model predictive control systems provide sufficient control performance under different operating conditions. However, performance metrics reveal differences among the methods
Characterization of the ash samples before and after thermal processing aiming phosphorus extraction and residues valorization
No full textThis paper presents the prospect of phosphorus (P) - rich poultry litter manure ash (PLA) used to recover P through microwave heating methods, aiming for residual slag recycling in constructions. The results show the complex composition of the ashes characterized by X-ray fluorescence (XRF), reflected light optical microscopy, X-ray microanalysis (SEM/EDS) and X-ray diffraction (XRD), which explains the differences between the ash types and the operation temperature in the combustion chamber. At the same time, the results present a novel approach of using microwave heating by reducing energy consumption to extract/enrich P from PLA and forming a by-product/residual slag used as a supplementary cementing material. Samples of fly ash (FA) and bottom ash (BA) were collected from two fluidized bed incinerators (G & uuml;res and Beypi in T & uuml;rkiye) operating at 750 degrees C and 850 degrees C within the PHIGO project funded by the 3rd ERA-MIN Program of the European Union Commission.ERA-MIN3 Joint Call (2021) [310/01.03.2022, 19848/02.08.2022]; Vinnova-Sweden [2022-00072]; TUBITAK-Turkey [122N038]; Polish National Centre for Research and Development (NCBR) [ERA-MIN3/1/9/PHIGO/2022]; FCT-Portugal [UIDB/04683, UIDP/04683]; UNIBS - Italy thanks RHIGUS; MUR: PRIN 2022; Vinnova [2022-00072] Funding Source: VinnovaThe authors acknowledge the ERA-MIN3 Joint Call (2021) for funding the PHIGO project Thermal Processing of P -rich ashes aiming for HIGH-GRADE PHOSPHORUS Products through UEFISCDI-Romania (ref. 310/01.03.2022 and contract UNSTPB-UCB no. 19848/02.08.2022) , Vinnova-Sweden (ref. 2022-00072) , TUBITAK-Turkey (ref. 122N038) and Polish National Centre for Research and Development (NCBR) (ERA-MIN3/1/9/PHIGO/2022) . B.V. thanks FCT-Portugal (UIDB/04683; UIDP/04683) . UNIBS - Italy thanks RHIGUS ( (Low energy technologies for recovery of high-grade phosphorus) financed by MUR: PRIN 2022) . The authors acknowledge the anonymous reviewers for their contribution brought in improving the manuscript
Parametrik ve parametrik olmayan yöntemler kullanarak otobüs durakta bekleme süresini etkileyen faktörlerin modellenmesi
No full textBu tez, otobüs durakta bekleme süresini etkileyen temel operasyonel ve yolcuya ait faktörleri modellemeyi amaçlamaktadır. Çalışma, manuel olarak toplanan durak düzeyindeki veriler kullanılarak İzmir kentinde gerçekleştirilmiştir. Analiz kapsamında toplam binen yolcu sayısı, otobüs içi kalabalıklık düzeyi, açılan kapı sayısı ve yolcu çeşitliliği oranı olmak üzere dört temel değişken ele alınmıştır. Veri seti 443 gözlemden oluşmakta olup, eksik veriler çıkartılmıştır. Modelleme sürecinde, parametrik yöntemler olan Çoklu Doğrusal Regresyon, Elastik Net ve Polinom Regresyon yöntemlerine ek olarak parametrik olmayan K-En Yakın Komşu, Rastgele Orman ve XGBoost yöntemleri uygulanmıştır. Modeller; R², Ayarlanmış R², OKH, Ortalama Mutlak Hata ve Kök Ortalama Kare Hata gibi ölçütlerle karşılaştırılmıştır. Elastik Net modeli %72’lik, XGBoost ve Rastgele Orman modelleri ise %77’nin üzerinde ayarlanmış R² değerleri ile en başarılı sonuçları vermiştir. K-En Yakın Komşu modeli nispeten düşük performans göstermiştir. Tüm modellerde en etkili değişkenin binen yolcu sayısı olduğu tespit edilmiştir. Bu çalışma, Türkiye bağlamında otobüs durakta bekleme süresini tahmin etmeye yönelik çok yönlü bir modelleme yaklaşımı sunarak literatüre katkı sağlamaktadır.This thesis aims to model the key operational and passenger-related factors affecting bus dwell time. The study was conducted using stop-level data collected manually, focusing on İzmir as a case study. Four main variables were analyzed: total number of boarding passengers, interior crowdedness level, number of doors opened, and the complexity ratio (i.e., the proportion of elderly, disabled, or stroller users among boarding passengers). The dataset consists of 443 observations, with missing values cleaned prior to analysis. Parametric Multiple Linear Regression, Elastic Net, Polynomial Regression, and non-parametric K-Nearest Neighbors, Random Forest, and XGBoost modeling approaches were implemented. Models were evaluated using statistical metrics such as R², adjusted R², Mean Squared Error, Mean Absolute Error, and Root Mean Squared Error. The Elastic Net model achieved an adjusted R² of 72%, while XGBoost and Random Forest yielded the best performance, with Adjusted R² values exceeding 77%. The KNN (K-Nearest Neighbors) model showed relatively lower performance. Across all models, the number of boarding passengers emerged as the most influential factor affecting dwell time. This study contributes to the literature by offering a multifaceted modeling approach for predicting bus dwell times in Türkiye
A saturation based self-tuned robust control design for Euler Lagrange systems
No full textControl of the family of systems that can be represented in the Euler Lagrange (EL) form is both challenging from a theoretical perspective and applicable to abroad spectrum of real systems. For this type of control problem, given that any parameter estimation error and disturbances are not directly addressed, the system performance deteriorates, and stability cannot be deduced in advance. Considering these issues, this work presents the design and the corresponding analysis of a saturation function based, model-free, continuous robust controller for mechanical systems represented in the EL form. In order to avoid chattering in controller input, which is a common problem in most robust and high-gain control designs, the proposed method makes use of continuously differentiable terms. The stability of the closed-loop system is ensured via rigorous Lyapunov-based arguments. To ease the tuning of the controller gain, an adaptive gain-tuning algorithm is proposed to be applied as an add-on. The effectiveness of the controller is demonstrated by a simulation study on a twin rotor multi-input-multi-output system (TRMS) model Furthermore, the feasibility of the proposed method is then tested on an in-house built, inherently unstable, and therefore extremely sensitive mobile robotic platform. In the experimental study, satisfactory performances are attained for both the controller and the gain-tuning algorithm where less than 0.5 degrees error is obtained in roll and pitch angles and less than 1 degrees error is achieved in the yaw direction.Scientific and Technological Research Council of Turkey (TUBITAK) [121E296]; TUBITAKThis study was supported by Scientific and Technological Research Council of Turkey (TUBITAK) under the Grant Number 121E296. The authors thank to TUBITAK for their supports
Bitki Gelişimini Teşvik Eden Bazı Bakterilerin White Dynasty Lale (Tulipa sp. L.) Çeşidinin Gelişimine Etkisi
No full textBu çalışmada White dynasty lale çeşidine, özgün ve yararlı bakteri ırklarının gelişim ve çiçeklenme üzerine etkileri araştırılmıştır. Ege Üniversitesi, Ziraat Fakültesi, Bitki Koruma Bölümü, Bakteriyoloji Laboratuvarı kültür koleksiyonuna ait endofitik karakterli olan 117 adet aday yararlı bakteri izolatı in vitro olarak siderofor aktivitesi, IAA üretimi, ACC deamilaz aktivitesi ve Fosfataz Aktivitesi testleri yapılmıştır. In vitro PGPR testlerinin sonucuna üzerinden yapılan tartılı derecelendirme metodu ile en başarılı dört yararlı bakteri bitkiler üzerinde uygulanmak üzere seçilmiştir. Bakterilerin OD 600 = 0.1 (~1×10? cfu/ml) yoğunluğundaki süspansiyonları 5 ml olarak içirme şeklinde bitki köklerine uygulanmıştır. Çalışma, tesadüf parselleri deneme desenine göre 3 tekerrürlü ve her tekerrürde 3 adet bitki olacak şekilde laboratuvar koşullarında kurulmuştur. Lalelerin yaprak sayısı, yaprak uzunluğu, yaprak genişliği, bitki boyu, çiçek boyu, çiçek genişliği ve sap kalınlığı incelenmiştir. Çalışmanın sonucunda en yüksek yaprak sayısı, en uzun bitki boyu, en yüksek yaprak uzunluğu, en fazla yaprak genişliği 213 numaralı bakteri uygulamasından; en yüksek çiçek boyunun ve en geniş çiçek çapı kontrol uygulamasından elde edilmiştir. Yürütülen çalışmada lale yetiştiriciliği için incelenen parametreler bakımından 213 no.lu özgün izolatına ait bakteri uygulamasının diğer uygulamalara nazaran daha fazla olumlu etki oluşturduğu gözlemlenmiştir
Synthesis, characterization, crystal structure, electrochemical and photoluminescence properties, DFT and molecular docking studies, and antimicrobial activities of two mononuclear nickel (II) complexes with Pyrazole-derived ligands
No full textTwo octahedral nickel complexes; [Ni(fdtp)2(DMF)2] (1) and [Ni(dcdtp)2(DMF)2] (2), based on 4-((3-fluorophenyl)diazenyl)-3-(trifluoromethyl)-1H-pyrazol-5-ol (fdtp) and 4-((2,4-dichlorophenyl)diazenyl)-3-(trifluoromethyl)-1H-pyrazol-5-ol (dcdtp) were synthesized. The complexes were characterized spectroscopically (FTIR, UV-Vis, Photoluminescence), Mass spectrometry, elemental analyses, electrochemically, thermally, and through Single-crystal X-ray investigations. The formation of the complexes was confirmed by the existence of Ni-O and Ni-N vibrations at bonds were observed as weak bands at 526-497 and 470-438 cm-1. According to the thermogravimetric analyses, the complexes were thermally stable and had relatively high activation energies (585.81 and 730.07 kJ mol-1 for 1, and 2, respectively). Cyclic voltammograms showed that the anodic potential region of 1 and 2 exhibited two irreversible oxidation peaks at 1.34 V &1.55 V and 1.41 V & 1.63 V, respectively, attributed to metal-localized oxidation. The complexes showed enhanced antibacterial activities compared to free ligands and comparable to the standard. The inhibition zones exhibited via 1 were about 21.7, 19.3, and 26.7 mm versus Escherichia coli (E. coli), Staphylococcus aureus (S. Aureus), and Bacillus Subtits (B. Subtits), respectively. Docking studies supported the antibacterial investigations; the binding energies of the complexes were -8.81 and -9.69 kcal/mol for 1 and 2 respectively, against E. coli (PDB ID: 6F86).Scientific and Technological Research Application and Research Center, Sinop University, Turkiye; Turkish Republic Department of Strategy and Budget [2016K12-2841]The authors acknowledge the Scientific and Technological Research Application and Research Center, Sinop University, Turkiye, for using the Bruker D8 QUEST diffractometer. The authors also acknowledge the presidency of the Turkish Republic Department of Strategy and Budget (Project Grant Nr: 2016K12-2841) for the financial support to conduct the photoluminescence measurements and electrochemical analysis. The authors would also like to dedicate the current article to the late Professor Hussein F. Zohdi, Professor of Organic Chemistry, Faculty of Science, Cairo University, Egypt, who passed away multiple years ago before starting the current work
Monitoring of marine pollution and stress responses: Radionuclides concentration and antioxidant molecules in macroalgae and seagrass
No full textThe biological effects of marine radionuclides on the macroalgae Cystoseira crinita and Halopteris scoparia, as well as the seagrass Cymodocea nodosa, were investigated in I(center dot)zmir Bay. Concentrations of radionuclides 210Pb, 226Ra, 232Th, and 40K were measured in samples of C. crinita and H. scoparia, whereas only 210Pb and 40K concentrations were determined in C. nodosa. In this study, 210Pb concentrations ranged from 11.38 to 31.72 Bq/kg in C. crinita, 19.7-98.02 Bq/kg in H. scoparia, and 26.09-81.27 Bq/kg in C. nodosa. Elevated 210Pb levels in H. scoparia and C. nodosa were observed predominantly during autumn and winter. The 210Po/210Pb activity ratios were found to range between 1.45 and 2.25 in C. crinita, 0.15-1.30 in H. scoparia, and 0.70-1.47 in C. nodosa. The antioxidant defense mechanisms in response to radiation-induced stress were examined in both macroalgae and seagrass samples, focusing on key biomarkers such as ascorbate peroxidase (APX), catalase (CAT), and proline. Correlation analyses were conducted between radionuclide concentrations and antioxidant activity. C. crinita exhibited a defense response to 210Pb exposure similar to that of 210Po, primarily through increased CAT enzyme activity. In C. nodosa, elevated 40K levels were associated with enhanced proline and APX responses, while the accumulation of 210Pb was met with a significant increase in proline-mediated antioxidant defense.Ege University Scientific Research Projects Committee, Trkiye [FDK-2018-20143]This work was partially funded by the Ege University Scientific Research Projects Committee, Turkiye (Project No: FDK-2018-20143)