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First-principles study of the structural,elastic,electronic,optical,and vibrational properties of intermetallic Pd_2Ga

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Chinese Physics B 2012年第3期21卷 341-348页

作者： Yildirim A koc H Deligoz E Department of Physics Siirt University Department of Physics Aksaray University

The structural, elastic, electronic, optical, and vibrational properties of the orthorhombic Pd2Ga compound are investigated using the norm-conserving pseudopotentials within the local density approximation in the frame of density functional theory. The calculated lattice parameters have been compared with the experimental values and found to be in good agreement with these results. The second-order elastic constants and the other relevant quantities, such as the Young＇s modulus, shear modulus, Poisson＇s ratio, anisotropy factor, sound velocity, and Debye temperature, have been calculated. It is shown that this compound is mechanically stable after analysing the calculated elastic constants. Furthermore, the real and imaginary parts of the dielectric function and the optical constants, such as the optical dielectric constant and the effective number of electrons per unit cell, are calculated and presented. The phonon dispersion curves are derived using the direct method. The present results demonstrate that this compound is dynamically stable.

关键词： Pd2Ga vibrational properties optical properties elastic constants

Bound states of the s-Wave Equation with Equal scalar and Vector standard Eckart Potential

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Chinese Physics Letters 2006年第3期23卷 539-541页

作者： Eser Olgar Ramazan koc Hayriye Tutunculer Department of Physics Faculty of Engineering University of Gaziantep 27310 Gaziantep Turkey

A supersymmetric technique for the bound-state solutions of the s-wave Klein-Gordon equation with equal scalar and vector standard Eckart-type potential is proposed. Its exact solutions are obtained. Possible generali... 详细信息

关键词： KLEIN-GORDON EQUATION

simulation of Turbulent Flows Using a Finite-Volume Based Lattice Boltzmann Flow solver

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Communications in Computational Physics 2015年第1期17卷 213-232页

作者： Goktan Guzel Ilteris koc AsELsAN Inc MGEO DivisionEtlik 06011AnkaraTURKEY

In this study,the Lattice Boltzmann Method(LBM)is implemented through a finite-volume approach to perform 2-D,incompressible,and turbulent fluid flow analyses on structured *** though the approach followed in this study necessitates more computational effort compared to the standard LBM(the so called stream and collide scheme),using the finite-volume method,the known limitations of the stream and collide scheme on lattice to be uniform and Courant-Friedrichs-Lewy(CFL)number to be one are ***,the curved boundaries in the computational domain are handled more accurately with less *** improvements pave the way for the possibility of solving fluid flow problems with the LBM using coarser grids that are refined only where it is necessary and the boundary layers might be resolved better.

关键词： Lattice Boltzmann Method finite-volume approach turbulent flows

Ab initio calculations of the elastic,electronic,optical,and vibrational properties of PdGa compound under pressure

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Chinese Physics B 2012年第9期21卷 422-429页

作者： H. koc A. Yildirim E. Deligoz Department of Physics Siirt University Department of Physics Aksaray University

The structural, elastic, electronic, optical, and vibrational properties of cubic PdGa compound are investigated using the norm-conserving pseudopotentials within the local density approximation （LDA） in the framework of the density functional theory. The calculated lattice constant has been compared with the experimental value and has been found to be in good agreement with experimental data. The obtained electronic band structures show that PdGa compound has no band gap. The second-order elastic constants have been calculated, and the other related quantities such as the Young＇s modulus, shear modulus, Poisson＇s ratio, anisotropy factor, sound velocities, and Debye temperature have also been estimated. Our calculated results of elastic constants show that this compound is mechanically stable. Furthermore, the real and imaginary parts of the dielectric function and the optical constants such as the electron energy-loss function, the optical dielectric constant and the effective number of electrons per unit cell are calculated and presented in the study. The phonon dispersion curves are also derived using the direct method.

关键词： PdGa vibrational properties optical properties elastic constants

Comparison of Densiron 68 and 1 000 cst silicone oil in the management of rhegmatogenous retinal detachment with inferior breaks

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International Journal of Ophthalmology(English edition) 2013年第1期6卷 81-84页

作者： Ibrahim kocak Haci koc Nisa Hastanesi Fatih cadCobancesme mah Ozel Kent Hastanesi

AIM:To compare success rates and complications of Densiron 68 and 1000cst silicone oil (sO) in the management of rhegmatogenous retinal detachment (RRD) with inferior breaks (IBs). METHODs:Totally 61 eyes of 61 consecutive patients with RRD with IBs were assigned to pars plana vitrectomy (PPV) with Densiron (n =31) or PPV with sO (n=30) in order of presentation. sO and Densiron removal was performed 3 months after initial surgery. Follow up visits were terminated 6 months after sO removal. ·REsULTs:With a single operation, the Densiron group showed 84% and sO 74% reattachment. With further surgery, both groups showed 90% reattachment. Complications such as cataract, raised intraocular pressure (IOP), inflammatory reaction, macular epiretinal membranes, and emulsification of sO were seen in both groups. CONCLUsION:Densiron and sO are found to have similar success rates and complications.

关键词： retinal detachment silicone oil Densiron heavy silicone oil inferior break

Design of a Two-dimensional Recursive Filter Using the Bees Algorithm

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International Journal of Automation and computing 2010年第3期7卷 399-402页

作者： D.T.Pham Ebubekir koc Manufacturing Engineering Centre Cardiff University Cardiff CF24 3AA UK

This paper presents the first application of the bees algorithm to the optimisation of parameters of a two-dimensional （2D） recursive digital filter. The algorithm employs a search technique inspired by the foraging behaviour of honey bees. The results obtained show clear improvement compared to those produced by the widely adopted genetic algorithm （GA）.

关键词： Bees algorithm swarm intelligence optimisation two-dimensional digital filter design.

Unusual complication in patient with Gardner's syndrome: Coexistence of triple gastrointestinal perforation and lower gastrointestinal bleeding: A case report and review of literature

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World Journal of Clinical Cases 2018年第10期6卷 393-397页

作者： sami Akbulut Cemalettin koc Abuzer Dirican Department of surgery and Liver Transplant Institute Inonu University Faculty of Medicine

Gardner's syndrome(Gs) is a rare syndrome with autosomal dominant inheritance, which is characterized by multiple intestinal polyps, dental anomalies, desmoid tumors, and soft tissue tumors. All gastrointestinal symptoms seen in Gs are associated with the underlying familial adenomatosis polyposis and abdominal desmoid tumors, with the most common symptoms being anemia, lower gastrointestinal bleeding, abdominal pain, diarrhea, obstruction, and mucous defecation. To our best knowledge, no case of Gs that has presented with gastrointestinal perforation and bleeding has ever been reported in the English language medical literature. A 37-year-old male who had been diagnosed with Gs five years earlier was referred to our clinic for lower gastrointestinal bleeding. Despite the absence of a bleeding focus on conventional angiography, the patient was operated on with laparotomy, due to the persistence of both signs and symptoms of mild peritonitis. On the laparotomy, the patient was noted to have areas of perforation in the duodenum, splenic flexura, and midrectum. The third and fourth part of the duodenum, the proximal 15 cm segment of the jejunum, a 10 cm segment of the terminal ileum, the whole colon, and the upper and middle rectum were resected, and duodenojejunal side-to-side anastomosis and terminal ileostomy were performed. The histopathological analysis of the large mass measuring 30 cm × 20 cm was reported as a desmoid tumor. The pathological examination of the tumor foci detected in the colonic specimen revealed poorly differentiated adenosquamous carcinoma.

关键词： Gastrointestinal perforation Gastrointestinal bleeding Adenosquamous carcinoma Complications Gardner’s syndrome

MOTIONs OF CURVEs IN THE GALILEAN sPACE G_3

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Acta Mathematica scientia 2015年第5期35卷 1046-1054页

作者： Ufuk OZTURK suleyman CENGIZ Esra Betul koc OZTURK Department of Mathematics Faculty of Science ank?r? Karatekin University

In this article, we study the flows of curves in the Galilean 3-space and its equiform geometry without any constraints. We find that the Frenet equations and the intrinsic quantities of the inelastic flows of curves are independent of time. We show that the motion of curves in the Galilean 3-space and its equiform geometry are described by the inviscid and viscous Burgers＇ equations.

关键词： Galilean geometry equiform geometry motions of curves inextensible flows Burgers' equation Frenet frames

Optimization of CNC cutting parameters using design of experiment(DOE) and desirability function

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Journal of Forestry Research 2018年第5期29卷 1423-1434页

作者： Ender Hazir Emine seda Erdinler Kücük Hüseyin koc Department of Forest Industrial Engineering Faculty of ForestryIstanbul University

In this study,2~5 （five factors at two-level factorial design） design of experiment was applied to investigate a set of optimal machining parameters to achieve a minimum surface roughness value for Abies *** specimens were prepared using different values of spindle speed,feed rate,depth of cut,tool radius,and cutting *** surface roughness （R_z） values were applied using a *** objectives were to：（1）obtain the effective variables of wood surface roughness;（2） analyze which of these factors had an impact on variability in the CNC machining process;（3） evaluate the optimal cutting values within the range of different cutting levels of machining *** results indicate that the design of experiment（DOE） based on the desirability function approach determined the optimal machining parameters successfully,leading to minimum R_a compared to the observed *** surface roughness values of tangential and radial cutting directions were 3.58 and 3.21 μm,respectively.

关键词： Wood surface roughness Optimization CNC Desirability function Pareto analysis