Arama Sonuçları

Listeleniyor 1 - 6 / 6
  • Öğe
    Temperature dependent electrical transport in Al/Poly(4-vinyl phenol)/ p -GaAs metal-oxide-semiconductor by sol-gel spin coating method
    (Hindawi, 2016-03-10) Özden, Şadan; Tozlu, Cem; Pakma, Osman
    Deposition of poly(4-vinyl phenol) insulator layer is carried out by applying the spin coating technique onto p-type GaAs substrate so as to create Al/poly(4-vinyl phenol)/p-GaAs metal-oxide-semiconductor (MOS) structure. Temperature was set to 80-320 K while the current-voltage (I-V) characteristics of the structure were examined in the study. Ideality factor (n) and barrier height (φ b) values found in the experiment ranged from 3.13 and 0.616 eV (320 K) to 11.56 and 0.147 eV (80 K). Comparing the thermionic field emission theory and thermionic emission theory, the temperature dependent ideality factor behavior displayed that thermionic field emission theory is more valid than the latter. The calculated tunneling energy was 96 meV.
  • Öğe
    First boundary value problem for cordes-type semilinear parabolic equation with discontinuous coefficients
    (Hindawi, 2020-06-19) Harman, Aziz; Harman, Ezgi
    For a class of semilinear parabolic equations with discontinuous coefficients, the strong solvability of the Dirichlet problem is studied in this paper. The problem ∑i,j=1naijt,xuxixj-ut+gt,x,u=ft,x,uΓQT=0, in QT=Ω×0,T is the subject of our study, where Ω is bounded C2 or a convex subdomain of En+1,ΓQT=∂QT\∖t=T. The function gx,u is assumed to be a Caratheodory function satisfying the growth condition gt,x,u≤b0uq, for b0>0,q∈0,n+1/n-1,n≥2, and leading coefficients satisfy Cordes condition b0>0,q∈0,n+1/n-1,n≥2.
  • Öğe
    Analysis of the effect of experimental adsorption uncertainty on CH 4 production and CO 2 sequestration in Dadas shale gas reservoir by numerical simulations
    (Elsevier, 2019) Merey, Şükrü
    The importance of unconventional gas reservoirs such as shale gas reservoirs has increased with the decline of conventional gas reservoirs and advancement in horizontal drilling and hydraulic fracturing in the world. Recently, there have been many exploration activities in Dadas shales, Turkey. Previously, the adsorption capacities of CH 4 and CO 2 on Dadas shale samples were measured by using volumetric adsorption experimental set-up. Although adsorption uncertainties of these experiments were calculated, their effects on CH 4 production or CO 2 sequestration in Dadas shales were not evaluated in field scale. In this study, the numerical simulations for CH 4 gas production via 500 m long horizontal well from Dadas shale gas reservoir with different adsorption cases due to experimental adsorption uncertainties were conducted by using TOUGH + RealGasBrine. It was observed that initial CH 4 adsorption capacity of Dadas shales varies from 2.1% to 20.9% because of experimental adsorption uncertainty and absorbed gas volume corrections. Numerical simulations showed initial adsorbed gas % and final adsorbed gas % vary significantly. Similarly, the injection of CO 2 into the depleted Dadas shale gas reservoir was analyzed by numerical simulations at different adsorption cases due to experimental adsorption uncertainty and adsorbed gas volume correction. Final adsorbed CO 2 % varies from 18.1% to 27.5%. Furthermore, there are important differences in the amount of CO 2 injected, final adsorbed CH 4 % and final adsorbed CO 2 % during CO 2 injection simulations. The main reasons of these differences are experimental adsorption uncertainty and adsorbed gas volume correction. This study showed that the volumetric adsorption experimental method is not reliable in low adsorption values as in Dadas shales. It only gives adsorption ranges. The implication of this study is that the effect of experimental adsorption uncertainty obtained with the volumetric adsorption method on CH 4 production or CO 2 sequestration in Dadas shale gas reservoir is significant in field scale.
  • Öğe
    Optimized preparation for bimodal porous carbon from lentil processing waste by microwave-assisted K 2 CO 3 activation: Spectroscopic characterization and dye decolorization activity
    (Elsevier, 2019) Sayğılı, Hasan; Akkaya Sayğılı, Gülbahar
    This paper describes lab-scale experiments for producing optimal activated carbon (LWAC)with bimodal porous (mixed micro-mesoporous)texture under optimized conditions from lentil processing waste (LW)by microwave-assisted K 2 CO 3 activation. The influences of various operating parameters were evaluated including impregnation ratio (IR), carbonization temperature (CT)and carbonization time (Ct). The BET surface area (S BET )and total pore volume (V T )were chosen as main criteria in optimization. The optimized parameters were IR ratio of 3:1, CT of 800 °C and Ct of 1 h. The physicochemical properties of LW and LWAC were identified with diverse analytical techniques. LWAC possessed high S BET of 1875 m 2 /g and large V T of 0.995 cm 3 /g. The LWAC was then tested for its feasibility as cationic (Methylene blue (MB))and anionic (Methyl orange (MO))dyes adsorbent. It was found that LWAC has an adsorption capacity of 625 mg/g for MB and 476 mg/g for MO at 30 °C
  • Öğe
    Multivariate padé approximation for solving nonlinear partial differential equations of fractional order
    (Hindawi, 2013-03-16) Turut, Veyis; Güzel, Nuran
    Two tecHniques were implemented, the Adomian decomposition method (ADM) and multivariate Pade approximation (MPA), for ´ solving nonlinear partial differential equations of fractional order. The fractional derivatives are described in Caputo sense. First, the fractional differential equation has been solved and converted to power series by Adomian decomposition method (ADM), then power series solution of fractional differential equation was put into multivariate Pade series. Finally, numerical results were ´ compared and presented in tables and figures
  • Öğe
    Fresh and hardened properties of self consolidating Portland limestone cement mortars: Effect of high volume limestone powder replaced by cement
    (Elsevier, 2018-11-21) Demirhan, Serhat; Türk, Kazım; Ulugerger, Kübra
    The main purpose of this experimental study is to elucidate the performance of self-compacting mortars (SCMs) composed of high volume limestone powder (LSP). In accordance with this purpose, four different SCMs at which limestone content varied as 0%, 15%, 25% and 35% were designed and later on fresh, hardened and durability properties of the mixtures were investigated for different curing ages depending on the testing method. Compressive strength, splitting tensile strength, rheological properties, mini-slump cone, carbonation, UPV and capillary water absorption were investigated in terms of fresh and hardened performance properties. In term of fresh properties, test results showed that there was a clear increase in the yield stress up to LSP content of 15% and beyond this level there was a tendency of reduction of the yield stress with the increase of limestone addition and also slumps values increased and pointed out a satisfactory fresh property in accordance with the increase in the replacement level of LSP. For mechanical properties, there was a steady decrease in the compressive strength values with the increase in LSP content while the addition of LSP in SCMs more than 15% did not improve splitting tensile strength of the mixtures for all curing ages. As a durability property, carbonation resistance of SCMs samples decreased with the increase in LSP replacement level for all of the mixtures and also UPV values were in an acceptable range of good (for 15%) and doubtful (for 35%) category intervals. Furthermore, the control mixture with the only PC had the lowest sorptivity coefficient as 2.73 cm/s1/2 followed by SCMs with 15%, 25% and 35% LSP as 5.11, 6.13 and 6.14 cm/s1/2, respectively.