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Electrical and dielectric properties of Al/p-Si and Al/perylene/p-Si type diodes in a wide frequency range

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Chinese Physics B 2014年第1期23卷 519-524页

作者： ahmet Kaya akaya@turgutozal.edu.tr Physics Department Faculty of Sciences Gazi University Ankara 06500 Turkey

The perylene （C20H12） layer effect on the electrical and dielectric properties of Al/p-Si （MS） and Al/perylene/p-Si （MPS） diodes have been investigated and compared in the frequency range of 0.7 kHz-2 MHz. Experimental results show that C-V characteristics give an anomalous peak for two structures at low frequencies due to interface states （Nss） and series resistance （Rs）. The increases in C and G/o3 at low frequencies confirm that the charges at interface can easily follow an ac signal and yield excess capacitance and conductance. The frequency-dependent dielectric constant （er） and dielectric loss （e＇） are subtracted using C and G/co data at 1.5 V. The eI and e＂ values are found to be strongly dependent on frequency and voltage, and their large values at low frequencies can be attributed to the excess polarization coming from charges at traps. Plots of ln（o＇ac）-ln（w） for two structures have two linear regions, with slopes of 0.369 and 1.166 for MS, and of 0.077 and 1.061 for MPS, respectively. From the C 2-V characteristics, the doping acceptor atom concentration （NA） and barrier height （,~） for Schottky barrier diodes （SBDs） 1.303 ~ 1015 cm-3, and 1.10 and I. 13 eV, respectively. of MS and MPS types are also obtained to be 1.484 ~ 1015

关键词： organic-inorganic based Schottky diodes perylene (C20H12) interfacial layer electrical and di-electric properties frequency and voltage dependence

Effect of imperfect bonding on the dynamic response of a pre-stressed sandwich plate-strip with elastic layers and a piezoelectric core

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Acta Mechanica Solida Sinica 2017年第6期30卷 658-667页

作者： ahmet Dasdemir Department of Mathematics Kastamonu University Kuzeykent Campus 37150 Kastamonu Turkey

In this paper,we consider the dynamic response of a pre-stressed sandwich plate-strip with a piezoelectric core and elastic layers under the action of a time-harmonic force resting on a rigid *** investigation is carried out within the framework of the piecewise homogeneous body model by utilizing the exact equations of motion and relations of the linear theory of *** is assumed that there is a shear-spring-type imperfect contact between the layers,but a complete contact between the plate-strip and the rigid foundation.A mathematical model of the problem is constructed,and the governing equations of motion are solved by employing the finite element method（FEM）.Numerical results illustrating the influence of a change in the value of the shear-spring parameter on the dynamic response of the plate-strip are then presented.

关键词： Sandwich plate-strip Shear-spring-type imperfection Piezoelectric materials Initial stress Frequency response

New Apsidal Motion in Four Eccentric Eclipsing Binaries:V610 Car,V944 Cep,V2815 Ori and V1260 Tau

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Research in Astronomy and Astrophysics 2022年第11期22卷 69-77页

作者： ahmet Bulut Department of Physics Faculty of Arts and SciencesCanakkale Onsekiz Mart UniversityTerzioglu CampusTR-17020CanakkaleTurkiye Astrophysics Research Centre and Observatory Canakkale Onsekiz Mart UniversityTerzioglu CampusTR-17020CanakkaleTurkiye

This paper presents an apsidal motion *** apsidal motion analysis of the eccentric eclipsing binaries V610 Car(P=4.84 days),V944 Cep(P=6.56 days),V2815 Ori(P=2.13 days),and V1260 Tau(P=5.43 days)was performed using minima times from the O-C Gateway database,ASAS-3,ASAS-SN,and TESS,following Lacy’s *** rates of change of periastron longitude were found to be 0.0253±0.0041,0.0347±0.0015,0.0288±0.0010 and0.0294±0°.0079 cycle^(-1),*** the light curve study,the first photometric mass ratio of V944 Cep was found to be q=1.4994±0.0012.A new light curve of V944 Cep was obtained using TESS *** first absolute dimensions of V944 Cep were M_(1)=1.10±0.01 M_(⊙),M_(2)=1.64±0.02 M_(⊙),R_(1)=2.04±0.37 R_(⊙),R_(2)=3.77±0.67 R_(⊙)for the hotter primary component(T_(1)=4925 K),and M_(1)=1.04±0.01 M_(⊙),M_(2)=1.57±0.02 M_(⊙),R_(1)=2.26±0.36 R_(⊙),R_(2)=3.74±0.59 R_(⊙)for the cooler primary component(T_(1)=4475 K).For V610 Car,V944 Cep,V2815 Ori and V1260 Tau,the apsidal motion periods were found to be 188±26 yr,186±8 yr,73±3 yr and 182±38 yr,*** V944 Cep,the internal structural constants of the component stars log_(k2,obs)=-2.05±0.01 and log_(k2,theo)=-1.83 for hotter primary component and log_(k2,obs)=-1.97±0.01 and log_(k2,theo)=-1.89 for cooler primary component were calculated.

关键词： (stars:)binaries:eclipsing stars:fundamental parameters techniques:photometric

New testing methodology for the quantification of rock crushability:Compressive crushing value(CCV)

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International Journal of Minerals,Metallurgy and Materials 2018年第11期25卷 1227-1236页

作者： Ekin Koken ahmet Ozarslan Department of Mining Engineering Zonguldak Bülent Ecevit University67100ZonguldakTurkey

Crushing is a size reduction process that plays a key role in both mineral processing and crushing–screening plant design. Investigations on rock crushability have become an important issue in mining operations and the manufacture of industrial crusher equipment. The main objective of this research is to quantify the crushability of hard rocks based on their mineralogical and mechanical properties. For this purpose, the mineralogical, physical, and mechanical properties of various hard rocks were determined. A new compressive crushing value(CCV) testing methodology was proposed. The results obtained from CCV tests were compared with those from mineralogical inspections, rock strength as well as mechanical aggregate tests. Strong correlations were found between CCV and several rock and aggregate properties such as uniaxial compressive strength(UCS), the brittleness index(S_(20)), and aggregate impact value(AIV). Furthermore, the relationship between the mineralogical properties of the rocks and their CCVs were established. It is concluded that the proposed testing methodology is simple and highly repeatable and could be utilized as a pre-design tool in the design stage of the crushing process for rock quarries.

关键词： crushability jaw crusher hard rocks aggregate rock strength crushed stone

Finite Element Analysis of the Contact Mechanics of Ceramic-on-Ceramic Hip Resurfacing Prostheses

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Journal of Bionic Engineering 2010年第3期7卷 244-253页

作者： ahmet C.Cilingir Department of Mechanical Engineering Sakarya University

Ceramics are good alternative to metal as bearing couple materials because of their better wear resistance. A Finite Element(FE) study was performed to investigate the contact mechanics and stress distribution of Ceramic-on-Ceramic (COC) hip resurfacingprostheses. It was focused in particular on a parametric study to examine the effects of radial clearance, loading,alumina coating on the implants, bone quality, and fixation of cup-bone interface. It was found that a reduction in the radialclearance had the most significant effect on the predicted contact pressure distribution among all of the parameters considered inthis study. It was determined that there was a significant influence of non-metallic materials, such as the bone underneath thebearing components, on the predicted contact mechanics. Stress shielding within the bone tissue was found to be a major concernwhen regarding the use of ceramic as an alternative to metallic resurfacing prostheses. Therefore, using alumina implantswith a metal backing was found to be the best design for ceramic resurfacing prostheses in this study. The loading, bone quality,and acetabular cup fixation conditions were found to have only minor effects on the predicted contact pressure distribution alongthe bearing surfaces.

关键词： contact mechanics hip resurfacing ceramic finite element analysis

Bright and dark soliton solutions for some nonlinear fractional differential equations

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Chinese Physics B 2016年第3期25卷 52-59页

作者： Ozkan Guner ahmet Bekir Cankiri Karatekin University Faculty of Economics and Administrative Sciences Department of International Trade CankiriTurkey Eskisehir Osmangazi University Art-Science Faculty Department of Mathematics-Computer Eskisehir Turkey

In this work, we propose a new approach, namely ansatz method, for solving fractional differential equations based on a fractional complex transform and apply it to the nonlinear partial space-time fractional modified Benjamin-Bona- Mahoney （mBBM） equation, the time fractional mKdV equation and the nonlinear fractional Zoomeron equation which gives rise to some new exact solutions. The physical parameters in the soliton solutions： amplitude, inverse width, free parameters and velocity are obtained as functions of the dependent model coefficients. This method is suitable and more powerful for solving other kinds of nonlinear fractional PDEs arising in mathematical physics. Since the fractional deriva- tives are described in the modified Riemann-Liouville sense.

关键词： exact solutions ansatz method space-time fractional modified Benjamin-Bona-Mahoney equa-tion time fractional mKdV equation

Effect of Rotational and Sliding Motions on Friction and Degeneration of Articular Cartilage under Dry and Wet Friction

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Journal of Bionic Engineering 2015年第3期12卷 464-472页

作者： ahmet C. Cilingir Department of Mechanical Engineering Sakarya University 54187 Sakatya Turkey

Understanding the tribological properties of articular cartilage allows scientists to evaluate degenerative joint diseases and develop new treatment techniques. The objectives of this study are to demonstrate the detrimental effect of rotational motion under both dry and wet friction and to evaluate the friction and wear behavior of bovine articular cartilage with sliding and rotational testing configurations that represent fluid film and boundary lubrication mechanisms, respectively. The articular cartilage pin and plate samples were harvested from healthy adult bovine and then tested on a self-made friction and wear simulator. Cartilage samples were subjected to sliding and rotational motions under constant load. Friction coefficients and wear factors were calculated under three conditions： using bovine serum, phosphate buffered saline and with no lubricant present. The friction coefficient and wear factor of the articular cartilage were significantly increased with rotational motion under both dry and wet friction. Using bovine serum as lubricant in the sliding testing configuration the friction coefficient and wear factor of articular cartilage were both decreased. A similar decrease in the tribological properties of cartilage was initially observed for the rotational testing configuration with bovine serum; however, the friction coefficient and wear factor were increased after 150,000 cycles. In the absence of lubricant, the articular cartilage was entirely worn on contact area in both sliding and rotational testing configurations. Bovine serum proved an effective fluid film lubricant for articular cartilage surfaces.

关键词： articular cartilage rotational motion sliding motion dry friction wet friction wear

Bound states resulting from interaction of the non-relativistic particles with the multiparameter potential

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Chinese Physics B 2017年第10期26卷 38-48页

作者： ahmet Tas Ali Havare Mersin University Department of Physics

In this study, we present the analytical solutions of bound states for the Schrodinger equation with the mulfiparameter potential containing the different types of physical potentials via the asymptotic iteration method by applying the Pekeristype approximation to the centrifugal potential. For any n and l （states） quantum numbers, we derive the relation that gives the energy eigenvalues for the bound states numerically and the corresponding normalized eigenfunctions. We also plot some graphics in order to investigate effects of the multiparameter potential parameters on the energy eigenvalues. Furthermore, we compare our results with the ones obtained in previous works and it is seen that our numerical results are in good agreement with the literature.

关键词： multiparameter potential Schrodinger equation bound states asymptotic iteration method

Adaptive Fault Detection Scheme Using an Optimized Self-healing Ensemble Machine Learning Algorithm

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CSEE Journal of Power and Energy Systems 2022年第4期8卷 1145-1156页

作者： Levent Yavuz ahmet Soran ahmetÖnen Xiangjun Li S.M.Muyeen Electrical and Computer Engineering Department in Abdullah Gül University Kayseri 38080Turkey Department of Electrical and Computer Engineering College of EngineeringSultan Qaboos UniversityAl-KhoudMuscat123Oman Department of Electrical Engineering Qatar UniversityDoha 2713Qatar State Key Laboratory of Control and Operation of Renewable Energy and Storage Systems China Electric Power Rescarch InstituteBeijing 100192China

This paper proposes a new cost-efficient,adaptive,and self-healing algorithm in real time that detects faults in a short period with high accuracy,even in the situations when it is difficult to *** than using traditional machine learning(ML)algorithms or hybrid signal processing techniques,a new framework based on an optimization enabled weighted ensemble method is developed that combines essential ML *** the proposed method,the system will select and compound appropriate ML algorithms based on Particle Swarm Optimization(PSO)*** this purpose,power system failures are simulated by using the PSCA D-Python *** of the salient features of this study is that the proposed solution works on real-time raw data without using any pre-computational techniques or pre-stored ***,the proposed technique will be able to work on different systems,topologies,or data *** proposed fault detection technique is validated by using PSCAD-Python co-simulation on a modified and standard IEEE-14 and standard IEEE-39 bus considering network faults which are difficult to detect.

关键词： Decision tree(DT) ensemble machine learning algorithm fault detection islanding operation k-Nearest Neighbor(kNN) linear discriminant analysis(LDA) logistic regression(LR) Naive Bayes(NB) self-healing algorithm