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- MakaleAçık Erişim2025Scopus SJRQ2The role of NiO in isotype heterojunction photodiodes
Sevgili, Ömer; Orak, İkram; Özel, Sultan Süleyman; Özel, Faruk
This study presents a structural analysis of NiO and the fabrication of Al/NiO/p-Si isotype heterojunction photodiode (PD) as well as an investigation of the photo-response and photovoltaic (PV) properties of the PD in the various illumination intensities. The series resistance (RS) value of the Al/NiO/p-Si was calculated to be 0.11 kΩ using Ohm’s Law at 2 V. This result corroborates the assertion that RS is the pivotal parameter for attaining optimal performance in a PD. The NiO has made a notable improvement to the electrical parameters such as ideality factor, barrier height, and series resistance. The spectral responsivity R value of the PD was calculated as 1.59 A W−1 at −2 V. The Al/NiO/p-Si exhibited a short-circuit current density (JSC) of 60.38 mA·cm−2, an open-circuit voltage (VOC) of 149.0 mV, a fill factor (FF) of 27.67%, and a power conversion efficiency (PCE) of 2.49%. In view of the experimental results, it can be concluded that NiO represents a promising material for the optimization of heterojunction photodiode applications.
- MakaleYalnız künye2025Scopus SJRQ2Theoretical and experimental studies on a novel potential barrier control for a vehicle model and piezoelectric smart structure
Uyar, M.
A novel control methodology, inspired by the quantum mechanical phenomenon of particle-wave duality, wherein particles and waves utilize their energy to traverse potential barriers, has been proposed. This control strategy is investigated both numerically and experimentally to mitigate undesirable vibrations in a three-degree-of-freedom vehicle system and a smart beam structure. The mathematical framework for the vehicle system is derived using Lagrange’s equations, while the experimental setup is designed for the smart beam. Disturbance inputs in the form of step and sinusoidal road profiles are introduced into the vehicle model to simulate real-world conditions. For the smart beam, endpoint vibrations are induced as an initial value problem by releasing the beam’s endpoint from a predefined initial displacement. In order to achieve vibration suppression, control signals, parameterized based on system-specific frequency and period characteristics, are applied to both systems. The optimal control parameters are determined by evaluating the vibration damping performance. The findings of this study demonstrate that the proposed control strategy is not only effectively applicable to the experimental validation of the piezoelectric smart structure but also holds significant potential for numerical integration into mechanical systems, such as vehicle dynamics models.
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İncele - MakaleAçık Erişim2024Scopus SJRQ1AC transport loss analysis of HTS stack busbars for all-electric aircraft with harmonics and DC offset considerations
Abdioglu, Murat; Gautam, Gaurav; Zhang, Min; Yuan, Weijia
This paper presents a study of the current carrying capacity and AC loss of high-temperature superconducting (HTS) stacks to be used in busbar applications for all-electric aircraft. A 2D model was developed using COMSOL Multiphysics with a T-A formulation for detailed analysis. The study began by applying a stable 20 kA DC offset current to the HTS stacks to simulate practical operating conditions. Firstly, the behaviour of the critical current was studied under self-field conditions for stacks with different numbers of HTS tapes and spacing. Secondly, AC ripple currents were introduced with DC offsets, and the effects of 3rd and 5th harmonic distortions (HD) were studied. The results show that configurations with 40 tapes and gaps of more than 2 mm are considered suitable for safe current transport under DC conditions. On the other hand, increasing the tape spacing leads to an increase in the safe transport current ripple due to the reduced magnetic field interaction within the stack. In addition, the transport loss decreases as the air gap increases due to the reduction in the self-field, whereas it increases as the number of strips increases. The influence of the 3rd HD on the transport loss is minimal at a ripple current of 1% and slightly noticeable at 2%. However, it becomes more obvious as the ripple current approaches the critical value. Remarkably, even cases with equivalent total HD show significantly higher transport losses when characterised by higher 5th HD than their counterparts with 3rd HD. This comprehensive analysis provides valuable information on the performance characteristics of HTS stacks in all-electric aircraft busbar applications and offers important insights for the development and optimisation of these systems in practical aerospace applications.
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2024Scopus SJRQ2Exploring alternative polymer materials for joint liners: a software-guided material selection
Yilmaz, Galip; Gerdan, Zeynep; Çolak, Murat
This study explores the alternative polymer materials and selection process for joint implant liners, focusing on applying CES Selector software to identify suitable polymer materials. CES Selector provides an easy-to-use interface. It offers multiple selection methods, including boundary values and property constraints. Seven materials were excluded from the analysis, resulting in 19 potential candidates, including unconventional options like EVOH, PCTA, PESU, PI, PPA, PPC, PPSU, and PSU. The materials underwent evaluation based on key criteria, including tensile strength, Young’s modulus, compressive strength, fatigue strength, and fracture toughness. Overall, TPU exhibited a remarkable combination of high mechanical strength and adaptable Young’s modulus, making it a top contender. However, in other evaluation criteria, PI surpassed TPU, solidifying its potential as a superior choice. This systematic approach provides valuable insights for engineers and designers seeking innovative materials for joint implant liners. The study results broaden the range of materials used in implant manufacturing, providing potential alternatives that offer better long-term durability and performance.
- MakaleYayıncıda açık erişim2024Scopus SJRQ2Nonlinear optical properties of KnCl (n = 2-7) superalkali clusters
Şentürk, Şükrü; Fardad, Fraidoon; Ekincioğlu, Yavuz
The lowest energy structures along with the low lying isomer, stabilities, electronic properties, optical properties and nonlinear optical responses of KnCl (n = 2-7) clusters were studied within the density functional theory. The second order energy difference, dissociation energy and GH-L (HOMO-LUMO gap) point out that KnCl (n = 3, 5, 7) clusters are more stable. The calculated adiabatic ionization energies (AIE) for the KnCl (n = 2-6) clusters are in agreement with the measured ionization energies. The optical properties, namely optical electronegativity and refractive index, depends on the GH-L energy values. The K atom capped planar rhombus geometry of the K4Cl causes the noticeable vibrational frequency shift compared to the rest of IR spectra of the clusters. The first static hyperpolarizability (β o) values are in the range of 2.33 × 103-2.87 × 104 au and the second static hyperpolarizability varies between 5.74 × 106 au and 38.9 × 106 au for the cluster. The nonlinear optical response is due to the superalkali nature of KnCl (n = 2-7) clusters. From computed β vec values, the hyperpolarizability has projection on the dipole moment vector for the superalkalis except the K2Cl and K5Cl. The absorption spectra point out that KnCl (n = 6-7) clusters can be suitable as a NLO material since they have transparency in the deep UV region (λ< 300 nm).
AtıfScopus2WoS2OpenAlex3İncele - MakaleYayıncıda açık erişim2023Scopus SJRQ3Solidification analysis for variable thickness aluminum castings: simulation and chill design insights
Yilmaz, Galip; Colak, Murat; Uslu, Emin
Manufacturing high-quality casting parts with complex geometries requires high engineering skill and precision. One essential quality concern is isolated hot spots within the castings, often in thick sections. Each hot spot must be consistently fed or mitigated through directional solidification techniques. The impact of various mold sands and the geometry of chill parts on solidification direction was investigated using specialized casting and general-purpose simulation programs. A parametric optimization method was employed to analyze directional solidification to adjust the geometry of the chill parts. The results indicate that employing diverse mold sands to enhance cooling in the thick sections was a viable strategy for achieving directional solidification in parts where the feeding pathway is obstructed due to changes in cross-section. Furthermore, the study revealed that intricate details in the chill part’s geometry are not critical; however, a minimum volume (or weight) was necessary for adequate directional solidification. Lastly, an easily applicable mathematical model has been developed to determine the required volume of chill parts to ensure successful directional solidification.
AtıfScopus1WoS1OpenAlex1İncele - DergiSuperconductor Science and Technology
- DergiEngineering Research Express
- DergiPhysica Scripta