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Numerical Analysis of Deteriorated Sub-sea Pipelines under Environmental Loads

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Chinese Journal of Mechanical engineering 2015年第6期28卷 1163-1170页

作者： GüCüYEN engin Department of Civil engineering Faculty of Engineering Celal Bayar University

The significant point is the bidirectional interaction technique in FSI analysis while investigating subsea corrosion effect. By this way, pipe environment is accurately modelled and fluid effects are also considered. The effect of external corrosion defects on structural behaviour of a pipeline is studied by creating a nonlinear numerical model based on the finite element method according to ABAQUS analysis program. Corrosion losses of sections are obtained from experimental results and applied to the model. Numerical model is formed by a span of sub-sea pipeline that is subjected to environmental loads. Seismic and wind-generated irregular wave loads are considered as environmental loads. Irregular wave is represented with equivalent eight regular waves via FFT. The pipe is modelled according to two different types which are non-corroded（intact） and corroded（deteriorated） to demonstrate corrosion effects on it. The visible type of corrosion in marine environment is named ‘pitting＇ corrosion, in which the material loss is locally interpenetrated over the surface. By considering this situation, the corroded and non-corroded pipes are modelled as 3D solid elements. The main point is revealing how the subsea corrosion affects the structural behaviour of pipelines on the basis of implementation of experimental results to a model structure due to changes of stresses and displacement.

关键词： offshore pipelines environmental loads corrosion numerical analysis

Placement Effect on the Stability of Tetrapod Armor Unit on Breakwaters in Irregular Waves

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China Ocean engineering 2017年第6期31卷 747-753页

作者： Yesim CELIKOGLU Demet engin Yildiz Technical University Department of Civil Engineering Hydraulics and Coastal Engineering Laboratory Davutpasa 34210 Esenler-Istanbul Turkey

Tetrapod, one of the well-known artificial concrete units, is frequently used as an armor unit on breakwaters. Two layers of tetrapod units are normmaly placed on the breakwaters with different placement methods. In this study, the stability of tetrapod units with two different regularly placement methods are investigated experimentally in irregular waves. Stability coefficients of tetrapod units for both placement methods are obtained. The important characteristic wave parameters of irregular waves causing the same damage ratio as those of the regular waves are also determined. It reveals that the average of one-tenth highest wave heights within the wave train （H1/lo） causes the similar damage as regular waves.

关键词： breakwaters tetrapod unit stability placement methods irregular waves

Comparative evaluation of different statistical tools for the prediction of uniaxial compressive strength of rocks

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International Journal of Mining Science and Technology 2020年第6期30卷 785-797页

作者： Ahmet Teymen engin Cemal Mengüç Department of Mining engineering Nigde Ömer Halisdemir University51240 NigdeTurkey Department of Electrical and Electronics engineering Nigde Ömer Halisdemir University51240 NigdeTurkey

In this study,uniaxial compressive strength(UCS),unit weight(UW),Brazilian tensile strength(BTS),Schmidt hardness(SHH),Shore hardness(SSH),point load index(Is50)and P-wave velocity(Vp)properties were *** predict the UCS,simple regression(SRA),multiple regression(MRA),artificial neural network(ANN),adaptive neuro-fuzzy inference system(ANFIS)and genetic expression programming(GEP)have been *** obtained UCS values were compared with the actual UCS values with the help of various *** were modeled using different methods and compared with each *** the study where the performance indice PIat was used to determine the best performing method,MRA method is the most successful method with a small *** is concluded that the mean PIat equal to 2.46 for testing dataset suggests the superiority of the MRA,while these values are 2.44,2.33,and 2.22 for GEP,ANFIS,and ANN techniques,*** results pointed out that the MRA can be used for predicting UCS of rocks with higher capacity in comparison with *** to the performance index assessment,the weakest model among the nine model is P7,while the most successful models are P2,P9,and P8,respectively.

关键词： Uniaxial compressive strength Adaptive neuro-fuzzy inference system Multiple regression Artificial neural network Genetic expression programming

Physical properties of ternary thallium chalcogenes Tl2MQ3（M = Zr, Hf; Q = S, Se, Te） via ab-initio calculations

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Chinese Physics B 2019年第10期28卷 462-472页

作者： engin Ateser Oguzhan Okvuran Yasemin Oztekin Ciftci Haci Ozisik engin Deligoz Aksaray University Department of Physics68100AksarayTurkey Gazi University Science FacultyPhysics Department06500AnkaraTurkey

We have reported a first principles study of structural, mechanical, electronic, and thermoelectric properties of the monoclinic ternary thallium chalcogenes Tl2MQ3(M = Zr, Hf;Q = S, Se, Te). The electronic band structure calculations confirm that all compounds exhibit semiconductor character. Especially, Tl2ZrTe3 and Tl2HfTe3 can be good candidates for thermoelectric materials, having narrow band gaps of 0.169 eV and 0.21 eV, respectively. All of the compounds are soft and brittle according to the second-order elastic constant calculations. Low Debye temperatures also support the softness. We have obtained the transport properties of the compounds by using rigid band and constant relaxation time approximations in the context of Boltzmann transport theory. The results show that the compounds could be considered for room temperature thermoelectric applications(ZT ~ 0.9).

关键词： electronic band structure thermoelectric properties figure of merit ternary thallium chalcogens

Deep tissue near-infrared imaging for vascular network analysis

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Journal of Innovative Optical Health Sciences 2017年第3期10卷 12-23页

作者： Kübra Seker Mehmet engin Department of Electrical&Electronics engineering Faculty of engineering Ege University Bornova IzmirTurkey35100

Subcutaneous vein network plays important roles to maintain microcirculation that is related to some diagnostic *** developments of optical imaging technologies,still the difficulties about deep skin vascular imaging have been *** the other hand,since hemoglobin con-centration of human blood has key role in the veins imaging by optical manner,the used wavelength in vascular imaging,must be chosen considering absorption of *** this research,we constructed a near infrared(NIR)light source because of lower absorption of hemoglobin in this optical *** obtain vascular image,reflectance geometry was ***,from recorded images,vascular network analysis,such as calculation of width of vascular of interest and complexity of selected region were *** comparing with other modalities,we observed that proposed imaging system has great advantages including nonionized radiation,moderate penetration depth of 0.5-3 mm and diameter of 1 mm,cost-effective and algorit hmic simplicity for analysis.

关键词： Vascular NIR imaging manufacturing liquid and solid phantoms difuse optical imaging image processing and analysis optical imaging system design.

Helicobacter pylori and serum kynurenine-tryptophan ratio in patients with colorectal cancer

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World Journal of Gastroenterology 2015年第12期21卷 3636-3643页

作者： Ayse Basak engin Bensu Karahalil Ali Esat Karakaya Atilla engin Department of Toxicology Faculty of Pharmacy Gazi University Department of General Surgery Faculty of Medicine Gazi University

AIM: To evaluate how Helicobacter pylori(H. pylori) is able to evade the immune response and whether it enhances systemic immune tolerance against colorectal ***: This prospective randomized study involved 97 consecutive colorectal cancer patients and 108 cancer-free patients with extra-digestive diseases. Colorectal cancer and cancer-free patients were assigned into subgroups according to H. pylori Ig G seropositivity. Exposure to H. pylori was determined by Ig G seropositivity which was detected by enzyme linked immunoassay(ELISA). Serum neopterin levels were measured by ELISA. Serum tryptophan, kynurenine, and urinary biopterin concentrations were measured by high performance liquid chromatography. Serum nitrite levels were detected spectrophotometrically. Serum indoleamine 2,3-dioxygenase activity was estimated by the kynurenine to tryptophan ratio and by assessing the correlation between serum neopterin concentrations and the kynurenine to tryptophan ratio. The frequencies of increased serum kynurenine to tryptophan ratio of H. pylori seronegative and seropositive colorectal cancer subgroups were estimated by comparing them with the average kynurenine to tryptophan ratio of H. pylori seronegative tumor-free ***: Compared with respective controls, in both H. pylori seronegative and seropositive colorectal cancer patients, while serum tryptophan levels were decreased(controls vs patients; seronegative: 20.37 ± 0.89 μmol/L vs 15.71 ± 1.16 μmol/L, P < 0.05; seropositive: 20.71 ± 0.81 μmol/L vs 14.97 ± 0.79 μmol/L, P < 0.01) the kynurenine to tryptophan ratio was significantly increased(controls vs patients; seronegative: 52.85± 11.85 μmol/mmol vs 78.91 ± 8.68 μmol/mmol, P < 0.01, seropositive: 47.31 ± 5.93 μmol/mmol vs 109.65 ± 11.50 μmol/mmol, P < 0.01). Neopterin concentrations in cancer patients were significantly elevated compared with controls(P < 0.05). There was a significant correlation between serum neopterin levels and kynurenine/t

关键词： Colorectal cancer Kynurenine/tryptophan Immune tol

Effects of wood species and retention levels on removal of copper,chromium,and arsenic from CCA-treated wood using sodium hypochlorite

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Journal of Forestry Research 2016年第2期27卷 433-442页

作者： engin Derya Gezer Paul A.Cooper Department of Forest Industry engineering Karadeniz Technical University61080 TrabzonTurkey Faculty of Forestry University of Toronto33 Willcocks St.TorontoON M5S 3B3Canada

Chemical extraction, bioremediation, and electrodialytic processes have been extensively studied for removal of copper, chromium, and arsenic from wood treated with chromated copper arsenate （CCA）. However, one problem has not been addressed： the effects of wood species and retention levels on remediation efficiency. The objectives of this study were to investigate the effects of wood species and retention levels on removal of copper, chromium, and arsenic from CCA-treated wood samples using sodium hypochlorite. Our results showed that sodium hypochlorite （NaOC1） was very effective for removal of copper, chromium, and arsenic from CCA-C treated milled wood samples for all three species used in this study. The Cu, Cr, and As extraction efficiencies for red pine were 95 % Cu, 97 % Cr and 94 % As, for maple were 95 % Cu, 97 % Cr, and 98 % As at 4.0 kg m-3 retention levels, and for aspen were 95 % Cu, 92% Cr, and 91% As at 9.6 kg m-3 retention level, respectively. However, the results showed that wood species and initial retention levels of CCA-treated wood products played very impor- tant roles in terms of removal of Cu, Cr, and As.

关键词： Chromated copper arsenate (CCA) Remediation Remediation efficiency Wood species Retention level

Structural and mechanical stability of rare-earth diborides

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Chinese Physics B 2013年第4期22卷 369-376页

作者： Haci Ozisik engin Deligoz Kemal Colakoglu Gokhan Surucu Department of Computer and Instructional Technologies Teaching Aksaray University Department of Physics Aksaray University 68100 Aksaray Turkey Department of Physics Gazi University Teknikokullar 06500 Ankara Turkey

Structural and mechanical properties of several rare-earth diborides were systematically investigated by first principles calculations. Specifically, we studied XB2 , where X=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Lu in the hexagonal AlB2 , ReB2 , and orthorhombic OsB2 -type structures. The lattice parameters, bulk modulus, bond distances, second order elastic constants, and related polycrystalline elastic moduli （e.g., shear modulus, Young’s modulus, Poisson’s ratio, Debye temperature, sound velocities） were calculated. Our results indicate that these compounds are mechanically stable in the considered structures, and according to ＂Chen’s method＂, the predicted Vickers hardness shows that they are hard materials in AlB2 - and OsB2 -type structures.

关键词： ab initio calculations elastic properties hardness rare-earth diborides

Degradation kinetics of bioactive compounds in dried mistletoe leaves during storage

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Food Bioscience 2023年第2期52卷 1175-1182页

作者： Julide Gamze Yazar engin Demiray Department of Food engineering Pamukkale UniversityTR-20070DenizliTurkey

This work evaluated the effect of air atmosphere packaging and modified atmosphere packaging on the quality and nutritional compounds of dried mistletoe leaves during 4 months of storage at 4 and 25℃ *** leaves packaged with modified atmosphere had improved nutritional qualities overall as compared to mistletoe leaves packaged with atmosphere *** the end of the storage period,water activity values of all samples increased by 0.72%-3.38%.Before storage,the dried mistletoe leaves’total phenolic content was determined to be 301.73±2.49 mg GAE/100 g dry *** total phenolic content of the samples decreased by 62.00%-71.96%after four months of *** was determined that the highest loss of total phenolic content was observed at room temperature(25℃)and in the samples packaged with normal atmospheric *** antioxidant activity values in MAP2 samples decreased by 23.82%after four months when kept at low temperatures,but the loss was calculated to be 34.48%in cases where they were kept at room *** acid content losses in AP,MAP1,and MAP2 samples kept at room temperature were 21.48%,15.90%,and 14.72%,*** the samples stored at low temperatures,these loss rates were calculated as 16.62%,13.05%,and 12.05%,*** single model was satisfactory for describing changes in ascorbic acid content,which could not be determined in the samples stored at both 4℃ and 25℃.The dried mistletoe leaves modified atmosphere packed and stored at low temperatures provided the highest bioactive compound retention.

关键词： Mistletoe Drying Storage Ascorbic acid Antioxidant activity Kinetics