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Chinese Journal of Chemical Engineering 2006年第2期14卷 270-275页

作者： ahmet sari Kamil Kaygusuz Department of Chemistry Gaziosmanpasa University 60240 Tokat Turkey Department of Chemistry Karadeniz Technical University 61100 Trabzon Turkey

Stearic acid (67.83℃) and myristic acid (52.32℃) have high melting temperatures that can limit their use as phase change material (PCM) in low temperature solar heating applications such as solar space and greenhouse heating in regard to climatic requirements. However, their melting temperatures can be adjusted to a suitable value by preparing a eutectic mixture of the myristic acid (MA) and the stearic acid (SA). In the present study, the thermal analysis based on differential scanning calorimetry (DSC) technique shows that the mixture of myristic acid (MA) and stearic acid (SA) in the respective composition (by mass) of 64% and 36% forms a eutectic mixture having melting temperature of 44.13℃ and the latent heat of fusion of 182.4J·g-1. The thermal energy storage characteristics of the MA-SA eutectic mixture filled in the annulus of two concentric pipes were also experimentally established. The heat recovery rate and heat charging/discharging fractions were determined with respect to the change in the mass flow rate and the inlet temperature of heat transfer fluid. Based on the results obtained by DSC analysis and by the heat charg- ing/discharging processes of the PCM, it can be concluded that the MA-SA eutectic mixture is a potential material for low temperature thermal energy storage applications in terms of its thermo-physical and thermal characteristics.

关键词： eutectic mixture myristic and stearic acids phase change material thermal energy storage differential scanning calorimetry

An Experimental Study on Thermal Characteristics of Laurie Acid as a Latent Heat Storage Material during Melting Process

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Chinese Journal of Chemical Engineering 2003年第2期11卷 240-243页

作者： ahmet sari Department of Chemistry Gaziosmanpasa University

The objective of this study was to establish the thermal characteristics of the lauric acid (95% purity) as a latent heat storage material filled in the annulus of vertical concentric double pipe during its melting process,The temperature data were used to determine the thermal characteristics,including the temporal temperature variations and the effects of the mass flow rate and the inlet temperature of the heat transfer fluid on the heat transfer coefficient and the heat charging fraction during the melting process,The results indicated that the time to reach to heat charging fraction of 1.0 could be altered by changing the mass flow rate and the inlet temperature of the heat transfer fluid.

关键词： lauric acid phase change material thermal characteristics melting process

A Novel Layered Double Hydroxide and Dodecyl Alcohol Assisted PCM Composite with High Latent Heat Storage Capacity and Thermal Conductivity

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Journal of Thermal Science 2024年第2期33卷 537-547页

作者： AL-AHMED Amir sari ahmet KHAN Firoz AL-RASHEIDI Masoud Hekimoğlu Gökhan AFZAAL Mohammad A.ALSULAMI Ahmed DAFALLA Hatim SALHI Billel A.ALSULAIMAN Fahad Interdisciplinary Research Center for Renewable Energy and Power Systems(IRC-REPS) King Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia Department of Metallurgical and Material Engineering Karadeniz Technical UniversityTrabzon61080Turkey Maths and Natural Sciences Division Higher Colleges of TechnologyP.O.Box 7947SharjahUnited Arab Emirates Department of Mechanical Engineering King Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia Core Research Facilities King Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia Interdisciplinary Research Center for Membranes and Water Security King Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia

Dodecyl alcohol(DDA) is a promising solid-liquid phase change material(PCM) due to its favorable latent heat storage(LHS) ***,the leakage issue of PCM in a melted state during the heating period and low thermal conductivity restricts its utilization potential in thermal energy storage(TES) *** the same context,the present work aims to overcome the leakage issue and improve the thermal conductivity of the *** this in mind,a novel leak-proof layered double hydroxide(LDH)/DDA composite PCM is proposed through a solution-based impregnation *** leak-proof impregnation ratio of the DDA impregnated within the cavities of the synthesized Al/Fe-LDH was determined to be 60%.Detailed morphological,physicochemical,and thermal properties of the fabricated composite were studied by scanning electron microscopy(SEM),Fourier transforms infrared(FTIR) spectroscopy,X-ray diffraction(XRD)spectroscopy,differential scanning calorimetry(DSC),thermalgravimetric analysis(TGA),and thermal cycling *** results show that the LDH/DDA composite has a suitable phase change temperature(about 20℃) for passive solar thermal management of building *** composite PCM showed high LHS enthalpy(about136 J/g),good thermal stability,and cycling LHS *** also showed nearly 152% higher thermal conductivity compared to that of pure DDA,ultimately reducing the melting and solidification time of the pure DDA by 44.9% and 45.5%,respectively.

关键词： dodecyl alcohol layered double hydroxide composite PCM thermal conductivity thermal energy storage(TES)

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

A novel mutation of SGK-1 gene in central serous chorioretinopathy

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International Journal of Ophthalmology(English edition) 2015年第1期8卷 23-28页

作者： Mahmut Akyol Muhammet Kazιm Erol Ozdemir Ozdemir Deniz Turgut Coban ahmet Burak Bilgin Esin Sogutlu sari Elif Betul Turkoglu Department of Medical Biology and Genetics Akdeniz University Faculty of Medicine Department of Ophthalmology Antalya Education and Research Hospital Department of Ophthalmology Zekai Tahir Burak Women's Health Education and Research Hospital Department of Ophthalmology Akdeniz University Faculty of Medicine Department of Ophthalmology Balιkesir University Faculty of Medicine

AIM: To investigate the association of serum glucocorticoid kinase gene-1(SGK-1) DNA variants with chronic central serous chorioretinopathy(CSC).METHODS: We enrolled 32 eyes of 32 patients who were diagnosed with chronic CSC and composed 32 normal eyes as a control group. Peripheral blood was used for DNA extraction and polymerase chain reaction amplification. SGK1 gene was sequenced by using Big Dye Terminator v3.1 cycle sequencing Kit(Applied Biosystems, Foster City, CA, USA). The SGK-1 gene and its variants were investigated in CSC patient group and control ***: We identified a new polymorphism M32 V in two person in the patient group [Minor allele frequency(MAF) =0.009] on the region of 1-60 amino acids. The rs1057293 was located in the encoder region of the SGK- 1 gene but not associated with CSC(P =0.68). An intrinsic rs1743966 is also not associated(P =0.28).CONCLUSION: The new polymorphism M32 V is located on the region of 1-60 amino acids which is necessary for localization to the mitochondria in CSC patient. This mutation is probably important for the energy metabolism and plays an important role in the cellular response to hyperosmotic stress and other stress stimuli. Both rs1057293 and rs1743966 are not associated with CSC.

关键词： central serous chorioretinopathy mutation polymerase chain reaction serum glucocorticoid kinase gene-1

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