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Microsystems & Nanoengineering 2022年第1期8卷 161-174页

作者： ferhat bayram Durga Gajula Digangana Khan Goutam Koley Holcombe Department of Electrical and Computer Engineering Clemson UniversityClemsonSC 29634USA School of Electrical and Computer Engineering Georgia Institute of TechnologyAtlantaGA 30332USA

Nonlinear oscillations in micro-and nanoelectromechanical systems have emerged as an exciting research area in recent years due to their promise in realizing low-power,scalable,and reconfigurable mechanical memory and logic ***,we report ultralow-power mechanical memory operations utilizing the nonlinear oscillation regime of GaN microcantilevers with embedded piezotransistive AlGaN/GaN heterostructure field effect transistors as highly sensitive deflection *** between the high and low oscillatory states of the nonlinear oscillation regime was demonstrated using a novel phase-controlled opto-mechanical excitation setup,utilizing a piezo actuator and a pulsed laser as the primary and secondary excitation sources,***-based photoacoustic excitation was amplified through plasmonic absorption in Au nanoparticles deposited on a ***,the minimum switching energy required for reliable memory operations was reduced to less than a picojoule(pJ),which translates to one of the lowest ever reported,when normalized for mass.

关键词： excitation operations cantilever

Mechanical behaviour of adhesively single lap joint under buckling conditions

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Chinese Journal of Aeronautics 2021年第2期34卷 154-164页

作者： ferhat KADIOGLU Department of Aerospace Engineering Ankara Yildirim Bcvazit University06050 UlusAnkaraTurkey

Adhesive Single Lap Joints have been subjected to tensile and bending investigations by many researchers. However, the joint is also likely to experience buckling loading in some aerospace applications. The aim of this work is to investigate the joint behaviour under quasi-static buckling conditions. For this purpose, the joints with three different adherend thicknesses and 25 mm overlap length were tested using two different types of adherends and an adhesive film. They were modelled using a non-linear Finite Element Method via the ABAQUS Explicit package *** to failure and stress distributions in the joints were predicted and compared with the experimental results, which were found in a good agreement. The adhesive layer in the joint was assumed to experience shear stresses under the buckling mode, similar to that in tensile loading, yet, the stress concentrations at the ends of the overlap, the main cause of the failure, resulted in different effects on the joint performance;for the buckling mode the critical stresses were in compression but for the tensile case in peeling. Unlike the latter, the former was found to prevent failure of the layer depending on the adherend thickness, causing different failure mechanisms. There were two different failure modes of the joints;a complete failure in the adhesive layer and large plastic deformation of adherends which could be a good source for crashworthiness situations. Mechanical properties of the adherends were found to play important roles on the joint performance.

关键词： Adhesive joins Buckling mode Energy absorption Finite element method Single lap joint

Current and efficiency optimization under oscillating forces in entropic barriers

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Chinese Physics B 2016年第9期25卷 227-234页

作者： ferhat Nutku Ekrem Aydiner Theoretical Physics Research Group Department of PhysicsFaculty of ScienceIstanbul University

The transport of externally overdriven particles confined in entropic barriers is investigated under various types of oscillating and temporal ***,load,and amplitude dependence of the particle current and energy conversion efficiency are investigated in three *** oscillating forces,the optimized temperature–load,amplitude–temperature,and amplitude–load intervals are determined when fixing the amplitude,load,and temperature,*** using three-dimensional plots rather than two-dimensional ones,it is clearly shown that oscillating forces provide more efficiency compared with a temporal one in specified optimized parameter ***,the dependency of efficiency to the angle between the unbiased driving force and a constant force is investigated and an asymmetric angular dependence is found for all types of ***,it is shown that oscillating forces with a high amplitude and under a moderate load lead to higher efficiencies than a temporal force at both low and high temperatures for the entire range of contact angle.

关键词： entropic barrier Brownian motion Fick–Jacobs equation efficiency of Brownian motor

Current and efficiency of Brownian particles under oscillating forces in entropic barriers

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Chinese Physics B 2015年第4期24卷 82-89页

作者： ferhat Nutku Ekrem Aydιner Theoretical Physics Research Group Department of Physics Faculty of Sciencestanbul University

In this study, considering the temporarily unbiased force and different forms of oscillating forces, we investigate the current and efficiency of Brownian particles in an entropic tube structure and present the numerically obtained results. We show that different force forms give rise to different current and efficiency profiles in different optimized parameter intervals. We find that an unbiased oscillating force and an unbiased temporal force lead to the current and efficiency, which are dependent on these parameters. We also observe that the current and efficiency caused by temporal and different oscillating forces have maximum and minimum values in different parameter intervals. We conclude that the current or efficiency can be controlled dynamically by adjusting the parameters of entropic barriers and applied force.

关键词： entropic barrier Brownian motion Fick-Jacobs equation efficiency of Brownian motor stochastic processes

Investigation of Bose-Einstein Condensates in q-Deformed Potentials with First Order Perturbation Theory

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Communications in Theoretical Physics 2018年第2期69卷 154-158页

作者： ferhat Nutku Ekrem Ayd?ner Department of Physics Faculty of Science istanbul University Vezneciler istanbul 34134 Thrke

The Gross-Pitaevskii equation, which is the governor equation of Bose-Einstein condensates, is solved by first order perturbation expansion under various q-deformed potentials. Stationary probability distributions reveal one and two soliton behavior depending on the type of the q-deformed potential. Additionally a spatial shift of the probability distribution is found for the dark soliton solution, when the q parameter is changed.

关键词： Bose-Einstein condensates solitons q-deformed potential perturbation theory

SYNTHESIS AND CHARACTERIZATION OF AN ACRYLATE POLYMER CONTAINING CHLORINE-1,3-DIOXALANE GROUPS IN SIDE CHAINS

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Chinese Journal of Polymer Science 2012年第5期30卷 642-651页

作者： Zulfiye Ilter ferhat Alhanli Fatih Dogan Ismet Kaya Firat University Faculty of Science and ArtsDepartment of ChemistryElazigTurkey Canakkale Onsekiz Mart University Faculty of EducationSecondary Science and Mathematics Education 17100CanakkaleTurkey Canakkale Onsekiz Mart University Department of Chemistry17020CanakkaleTurkey

Poly[2-（4-chlorophenyl）-l,3-dioxolan-4-yl]methyl acrylate, poly（CPhDMA）, was synthesized with radical polymerization process using 2,2＇-azobisisobutyronitrile as radical initiator in 1,4-dioxane at 60℃. The structure of poly（CPhDMA） was confirmed by means of UV-Vis, FT-IR, 1H-NMR, and 13C-NMR spectral techniques. The molecular weight distribution values of the polymer were determined with gel permeation chromatography （GPC）. The number-average molecular weight （Mn）, weight-average molecular weight （Mw） and polydispersity index （PDI） values of poly（CPhDMA） were determined to be 10300, 21600 and 2.097, respectively. The thermal degradation kinetics of the polymer was investigated by using TG/DTG-DTA and DSC analyses at different heating rates in dynamic nitrogen atmosphere. The apparent activation energy values obtained by Flynn-Wall-Ozawa and Friedman methods were found to be 91.68 and 85.23 kJ mo1-1, respectively, for thermal decomposition of poly（CPhDMA）. Also, the thermal degradation activation energy value of poly（CPhDMA） was calculated by using the Kissinger method based on the DTG, DTA and DSC data. Then the mechanism function of it was determined by master plots method. Finally, electrical and optical properties of poly（CPhDMA） were determined by four-point probe and UV-Vis techniques, respectively.

关键词： Synthesis of acrylate polymer Thermal degradation Kinetic parameters.

Impacts of urban headwater disturbances on downstream sediment loading where streamside management zones for forest harvesting activities are present downstream

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International Journal of Sediment Research 2017年第4期32卷 555-563页

作者： Ilkim Cavus Latif Kalin ferhat Kara Ministry of Forestry and Water Affairs.General Directorate of Combating Desertification and Erosion Auburn University School of Forestry and Wildlife Sciences Kastamonu University Faculty of Forestry

Watershed disturbances caused by land use/land cover(LU/LC) change, intensive forestry practices, and other forms of watershed disturbance are known to negatively affect water quality, if best management practices(BMPs) are not present. Disturbances near or around headwaters where BMPs are absent or are inadequate may impact downstream water quality and stream ecology regardless of the presence of downstream BMPs. In this study, the recovery of two small forest-dominated watersheds(Ww and Ew) in Auburn, Alabama, USA, was monitored 6-years after a partial clearcut was done. The streamside management zone(SMZ) in Ww was also partially harvested shortly after the partial clearcut to improve its sediment trapping effectiveness over the long-term. The hydrology and sediment transport in these watersheds were expected to stabilize over this period, however, new disturbances in the headwaters of both watersheds changed the watershed dynamics. Streamflow and sediment load were examined over a15-month period from February 2014 to May 2015. The clearcut in Ww and Ew, and the partially harvested SMZ in Ww seemed to have recovered; however, substantial amount of sediment load were measured across all monitoring sites in both watersheds as a result of upstream disturbances. This study emphasizes the necessity of watershed management as a whole, and the importance of BMP applications within the entire watershed. It also highlights the fact that watershed management and BMP implementation is a dynamic process, thus, strategies and techniques need to be continuously adapted in response to environmental changes.

关键词： Headwater disturbances Best management practices Sediment load Southeast USA

Classification of pepper seeds using machine vision based on neural network

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International Journal of Agricultural and Biological Engineering 2016年第1期9卷 51-62页

作者： ferhat Kurtulmuş İlknur Alibaş Ismail Kavdir Department of Biosystems Engineering Faculty of AgricultureUludag University16059 BursaTurkey Department of Agricultural Machinery Faculty of AgricultureCanakkale Onsekiz Mart University17100 CanakkaleTurkey

Pepper is widely planted and used all over the world as fresh vegetable and *** and morphological information of pepper are stored through *** of seed variety is crucial for correctly identifying genetic *** varieties cannot be easily classified even by an expert eye due to the very small size of seeds and visual ***,more advanced technologies are required to determine the variety of a pepper seed.A classification method was proposed to discriminate pepper seed based on neural networks and computer *** acquisition was conducted using an office scanner at a resolution of 1200 *** features representing color,shape,and texture were extracted and used to classify pepper *** calculating features from different color components,a feature database was *** features were selected using sequential feature selection with different criterion *** a result of the feature selection procedure,the number of the features was significantly reduced from 257 to *** validation rules were applied to obtain a reliable classification model by preventing *** numbers of neurons in the hidden layer and various training algorithms were investigated to determine the best multilayer perceptron *** best classification performance was obtained using 30 neurons in the hidden layer of the *** this network,an accuracy rate of 84.94%was achieved using the sequential feature selection and the training algorithm of resilient back propagation in classifying eight pepper seed varieties.

关键词： pepper seed neural networks variety classification computer vision

Impact of the blockage ratio on the transport of sediment in the presence of a hydrokinetic turbine: Numerical modeling of the interaction sediment and turbine

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International Journal of Sediment Research 2021年第6期36卷 696-710页

作者： Fatima Khaled Sylvain Guillou Yann Méar ferhat Hadri University of Caen Normandy LISV University of Versailles Conservatoire National des Arts et Métiers University of Caen Normandy

Interactions between hydrokinetic turbines and near scale and far scale bed sediment particles are considered a critical area of assessment; however, a limited number of research studies have been published to address this issue. The current paper explores the influence of the blockage ratio on the morphology evolution downstream from a hydrokinetic turbine. A modeling framework is derived to predict the significant transport induced by a turbine installed on the erodible fluvial sandy bed surface,such as the Eulerian multi-phase model for the sediment and the Blade Element Momentum Theory(BEMT) for the turbine, using the open source platform OpenFOAM. Two configurations of different blockage ratios are considered. The configurations show differences in the bed morphology and the sediment transport. It has been shown for both configurations that the scour capabilities are enhanced below the turbine due to the acceleration of the flow and increasing local shear stress on the sediment.

关键词： Environmental impact Blockage effects Euler-Euler multiphase Hydrokinetic turbine Numerical simulations OpenFOAM

Bladder calculi concomitant with benign prostatic enlargement:is prostate surgery mandatory in patients who have never received medical therapy?

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Asian Journal of Andrology 2023年第5期25卷 604-607页

作者： Hakan Anil Umut Unal Kaan Karamik ferhat Ortoglu Hakan Ercil Department of Urology Adana City Training and Research HospitalAdana 01000Turkiye Department of Urology Korkuteli State HospitalAntalya 07000Turkiye

The historical dogma that bladder calculi comprise the main indication for prostatic surgery has recently been *** this study,we aimed to predict which patients should undergo simultaneous prostate and bladder calculi surgery or only bladder calculi removal by evaluating preoperative risk *** hundred and seventeen men with bladder stones and concomitant benign prostate enlargement(BPE)who had not received medical treatment before were included in the *** the first step,only the bladder calculi of patients were removed and medical treatment was given for *** patients who benefited from medical treatment during the follow-up were defined as Group 1 and the patients who required prostate surgery for any indication comprised Group *** factors for prostate surgery requirements were determined by comparing preoperative characteristics between the two groups with a cox regression *** the follow-up of 117 patients with bladder stones removed and medical treatment initiated,49(41.9%)patients had prostate surgery *** indication for 33(67.3%)of 49 patients was medical treatment *** presence of intravesical prostatic protrusion(IPP;hazard ratio:2.071,95%confidence interval[Cl]:1.05-4.05,P=0.034),and high postvoiding residual urine volume(hazard ratio:1.013,95%Cl:1.007-1.019,P<0.001)were found to be preoperative risk factors for needing future prostate *** patients who have not received medical treatment for BPE before,bladder calculi developing secondary to BPE do not always constitute an indication for prostate surgery.

关键词： benign prostate hyperplasia bladder calculi intravesical prostatic protrusion medical therapy prostate surgery