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Article Citation - WoS: 39Citation - Scopus: 49Focus Variation Measurement and Prediction of Surface Texture Parameters Using Machine Learning in Laser Powder Bed Fusion(Asme, 2020) Ozel, Tugrul; Altay, Ayca; Kaftanoglu, Bilgin; Leach, Richard; Senin, Nicola; Donmez, AlkanThe powder bed fusion-based additive manufacturing process uses a laser to melt and fuse powder metal material together and creates parts with intricate surface topography that are often influenced by laser path, layer-to-layer scanning strategies, and energy density. Surface topography investigations of as-built, nickel alloy (625) surfaces were performed by obtaining areal height maps using focus variation microscopy for samples produced at various energy density settings and two different scan strategies. Surface areal height maps and measured surface texture parameters revealed the highly irregular nature of surface topography created by laser powder bed fusion (LPBF). Effects of process parameters and energy density on the areal surface texture have been identified. Machine learning methods were applied to measured data to establish input and output relationships between process parameters and measured surface texture parameters with predictive capabilities. The advantages of utilizing such predictive models for process planning purposes are highlighted.Article Citation - WoS: 9Citation - Scopus: 9Existence and Uniqueness of Best Proximity Points Under Rational Contractivity Conditions(Walter de Gruyter Gmbh, 2016) Karapinar, Erdal; Roldan-Lopez-de-Hierro, Antonio-Francisco; Sadarangani, KishinThe main aim of this paper is to present some theorems in order to guarantee existence and uniqueness of best proximity points under rational contractivity conditions using very general test functions. To illustrate the variety of possible test functions, we include some examples of pairs of functions which are included in innovative papers published in the last years. As a consequence, we prove that our results unify and extend some recent results in this field.Article Citation - WoS: 31Citation - Scopus: 40Variational Mode Decomposition-Based Radio Frequency Fingerprinting of Bluetooth Devices(Ieee-inst Electrical Electronics Engineers inc, 2019) Aghnaiya, Alghannai; Ali, Aysha M.; Kara, AliRadio frequency fingerprinting (RFF) is based on identification of unique features of RF transient signals emitted by radio devices. RF transient signals of radio devices are short in duration, non-stationary and nonlinear time series. This paper evaluates the performance of RF fingerprinting method based on variational mode decomposition (VMD). For this purpose, VMD is used to decompose Bluetooth (BT) transient signals into a series of band-limited modes, and then, the transient signal is reconstructed from the modes. Higher order statistical (HOS) features are extracted from the complex form of reconstructed transients. Then, Linear Support Vector Machine (LVM) classifier is used to identify BT devices. The method has been tested experimentally with BT devices of different brands, models and series. The classification performance shows that VMD based RF fingerprinting method achieves better performance (at least 8% higher) than time-frequency-energy (TFED) distribution based methods such as Hilbert-Huang Transform. This is demonstrated with the same dataset but with smaller number of features (nine features) and slightly lower (2-3 dB) SNR levels.Article Citation - WoS: 10Citation - Scopus: 18Evaluation Criteria for Object-Oriented Metrics(Budapest Tech, 2011) Misra, Sanjay; Computer EngineeringIn this paper an evaluation model for object-oriented (OO) metrics is proposed. We have evaluated the existing evaluation criteria for OO metrics, and based on the observations, a model is proposed which tries to cover most of the features for the evaluation of OO metrics. The model is validated by applying it to existing OO metrics. In contrast to the other existing criteria, the proposed model is simple in implementation and includes the practical and important aspects of evaluation; hence it suitable to evaluate and validate any OO complexity metric.Article Citation - WoS: 37Citation - Scopus: 45Study on the Cytocompatibility, Mechanical and Antimicrobial Properties of 3d Printed Composite Scaffolds Based on Pva/ Gold Nanoparticles (aunp)/ Ampicillin (amp) for Bone Tissue Engineering(Elsevier, 2021) Topsakal, Aysenur; Midha, Swati; Yuca, Esra; Tukay, Ari; Sasmazel, Hilal Turkoglu; Kalaskar, Deepak M.; Gunduz, OguzhanOver the years, gold nanoparticles (AuNP) have been widely used in several biomedical applications related to the diagnosis, drug delivery, bio-imaging, photo-thermal therapy and regenerative medicine, owing to their unique features such as surface plasmon resonance, fluorescence and easy surface functionality. Recent studies showed that gold nanoparticles display positive effect on osteogenic differentiation. In line with this effect, 3-Dimesional (3D) scaffolds that can be used in bone tissue were produced by exploiting the properties of gold nanoparticles that increase biocompatibility and support bone tissue development. In addition, ampicillin was added to the scaffolds containing gold nanoparticles as a model drug to improve its antimicrobial properties. The scaffolds were produced as composites of polyvinyl alcohol (PVA) main matrix as PVA, PVA/AuNP, PVA/Ampicillin (AMP) and PVA/AuNP/AMP. Scanning Electron Microscopy (SEM) Fourier Transform Infrared Spectroscopy (FTIR), tensile measurement tests, and in vitro applications of 3D scaffolds were performed. As depicted by SEM, scaffolds were produced at pore sizes appropriate for bone tissue regeneration. According to FTIR results, there was no modification observed in the AMP, PVA and gold nanoparticles due to mixing in the resultant scaffolds. In vitro results show that 3D printed composite scaffold based on PVA/AuNP/AMP are biocompatible, osteo-inductive and exhibit antimicrobial properties, compared to PVA scaffolds. This study has implications for addressing infections during orthopedic surgeries. The PVA-based gold nanoparticle 3D tissue scaffold study containing ampicillin covers a new study compared to other articles based on gold nanoparticles.Article Citation - WoS: 113Citation - Scopus: 147Experiments and Finite Element Simulations on Micro-Milling of Ti-6al Alloy With Uncoated and Cbn Coated Micro-Tools(Elsevier, 2011) Oezel, T.; Thepsonthi, T.; Ulutan, D.; Kaftanoglu, B.; Ozel, T.; Kaftanolu, B.This paper presents experimental investigations and finite element simulations on micro-milling of Ti-6Al-4V alloy with fine grain uncoated and cBN coated micro-end mills. Micro-milling of Ti-6Al-4V using uncoated and cBN coated tungsten carbide micro-end mills are conducted; surface roughness, burr formation and tool wear are measured. Effects of machining parameters on surface roughness, burr formation, and tool wear for uncoated and cBN coated micro-tools are investigated. Finite element modelling is utilized to predict forces, temperatures, and wear rate for uncoated and cBN coated micro-tools. Predicted temperature and tool wear contours for uncoated and cBN coated micro-tool edges reveal advantages of cBN coatings. Optimization studies on the experimental results are also conducted to identify the optimum process parameters which minimize both surface roughness and burr formation concurrently. (C) 2011 CIRP.Review Citation - WoS: 75Citation - Scopus: 120Hybrid Blockchain Platforms for the Internet of Things (iot): a Systematic Literature Review(Mdpi, 2022) Alkhateeb, Ahmed; Catal, Cagatay; Kar, Gorkem; Mishra, AlokIn recent years, research into blockchain technology and the Internet of Things (IoT) has grown rapidly due to an increase in media coverage. Many different blockchain applications and platforms have been developed for different purposes, such as food safety monitoring, cryptocurrency exchange, and secure medical data sharing. However, blockchain platforms cannot store all the generated data. Therefore, they are supported with data warehouses, which in turn is called a hybrid blockchain platform. While several systems have been developed based on this idea, a current state-of-the-art systematic overview on the use of hybrid blockchain platforms is lacking. Therefore, a systematic literature review (SLR) study has been carried out by us to investigate the motivations for adopting them, the domains at which they were used, the adopted technologies that made this integration effective, and, finally, the challenges and possible solutions. This study shows that security, transparency, and efficiency are the top three motivations for adopting these platforms. The energy, agriculture, health, construction, manufacturing, and supply chain domains are the top domains. The most adopted technologies are cloud computing, fog computing, telecommunications, and edge computing. While there are several benefits of using hybrid blockchains, there are also several challenges reported in this study.Article Citation - WoS: 10Citation - Scopus: 8Beyond expectations: disease duration and psychological burden in psoriatic arthritis(Springer Heidelberg, 2023) Kilic, Gamze; Kilic, Erkan; Tekeoglu, Ibrahim; Sargin, Betul; Cengiz, Gizem; Balta, Nihan Cuzdan; Nas, KemalThis study aims to investigate the relationship between disease duration and psychological burden in PsA and to identify the risk factors associated with psychological distress. Patients with PsA who met CASPAR classification criteria enrolled by Turkish League Against Rheumatism (TLAR)-Network. Patients were categorized into three groups based on disease duration: early stage (< 5 years), middle stage (& GE; 5, < 10 years), and late stage (& GE; 10 years). All patients underwent clinical and laboratory assessment using standardized protocol and case report forms. The associations between psychological variables and clinical parameters were assessed by a multivariate analysis. Of the 1113 patients with PsA (63.9% female), 564 (%50.7) had high risk for depression and 263 (%23.6) for anxiety. The risk of psychological burden was similar across all PsA groups, and patients with a higher risk of depression and anxiety also experienced greater disease activity, poorer quality of life, and physical disability. Multivariate logistic regression revealed that female gender (OR = 1.52), PsAQoL (OR = 1.13), HAQ (OR = 1.99), FiRST score (OR = 1.14), unemployment/retired (OR = 1.48) and PASI head score (OR = 1.41) were factors that influenced the risk of depression, whereas the current or past enthesitis (OR = 1.45), PsAQoL (OR = 1.19), and FiRST score (OR = 1.26) were factors that influenced the risk of anxiety. PsA patients can experience a comparable level of psychological burden throughout the course of their disease. Several socio-demographic and disease-related factors may contribute to mental disorders in PsA. In the present era of personalized treatment for PsA, evaluating psychiatric distress can guide tailored interventions that improve overall well-being and reduce disease burden.Article Citation - WoS: 2Citation - Scopus: 3Electrical Characterization of Zninse2 Thin-Film Heterojunction(Springer, 2019) Gullu, H. H.; Parlak, M.ZnInSe2/Cu0.5Ag0.5InSe2 diode structures have been fabricated by thermal evaporation of stacked layers on indium tin oxide-coated glass substrates. Temperature-dependent dark current-voltage measurements were carried out to extract the diode parameters and to determine the dominant conduction mechanisms in the forward- and reverse-bias regions. The heterostructure showed three order of magnitude rectifying behavior with a barrier height of 0.72 eV and ideality factor of 2.16 at room temperature. In the high forward-bias region, the series and shunt resistances were calculated with the help of parasitic resistance relations, yielding room-temperature values of 9.54 x 10(2) Omega cm(2) and 1.23 x 10(3) Omega cm(2), respectively. According to the analysis of the current flow in the forward-bias region, abnormal thermionic emission due to the variation of the ideality factor with temperature and space-charge-limited current processes were determined to be the dominant conduction mechanisms in this heterostructure. In the reverse-bias region, the tunneling mechanism was found to be effective in the leakage current flow with trap density of 10(6) cm(-3). Spectral photocurrent measurements were carried out to investigate the spectral working range of the device structure. The main photocurrent peaks observed in the spectrum corresponded to the band-edge values of the active thin-film layers.Article Citation - WoS: 11Citation - Scopus: 12Structural and Temperature-Tuned Bandgap Characteristics of Thermally Evaporated β-in2< Thin Films(Springer, 2021) Surucu, O.; Isik, M.; Terlemezoglu, M.; Gasanly, N. M.; Parlak, M.In2S3 is one of the attractive compounds taking remarkable interest in optoelectronic device applications. The present study reports the structural and optical characteristics of thermally evaporated beta-In2S3 thin films. The crystalline structure of the thin films was found as cubic taking into account the observed diffraction peaks in the X-ray diffraction pattern. The atomic compositional ratio of constituent elements was obtained as consistent with chemical formula of In2S3. Three peaks around 275, 309 and 369 cm(-1) were observed in the Raman spectrum. Temperature-tuned bandgap energy characteristics of the In2S3 thin films were revealed from the investigation of transmittance spectra obtained at various temperatures between 10 and 300 K. The analyses of the transmittance spectra indicated that direct bandgap energy of the In2S3 thin films decreases from 2.40 eV (at 10 K) to 2.37 eV (at 300 K) with the increase of measurement temperature. The bandgap energy vs. temperature relation was investigated by means of Varshni optical model. The fitting of the experimental data under the light of theoretical expression revealed the absolute zero bandgap energy, the rate of change of bandgap energy and Debye temperature.
