检索结果-南通市图书馆

Journal of Rock Mechanics and Geotechnical Engineering 2017年第6期9卷 1112-1122页

作者： Rohola Hasanpour Jürgen Schmitt yilmaz ozcelik Jamal Rostami Institute for Tunneling and Construction Management Ruhr-University Bochum Department of Civil Engineering Darmstadt University of Applied Science Department of Mining Engineering Hacettepe University Department of Mining Engineering Colorado School of Mines

Severe shield jamming events have been reported during excavation of Uluabat tunnel through adverse geological conditions, which resulted in several stoppages at advancing a single shielded tunnel boring machine(TBM). To study the jamming mechanism, three-dimensional(3D) simulation of the machine and surrounding ground was implemented using the finite difference code FLAC3D. Numerical analyses were performed for three sections along the tunnel with a higher risk for entrapment due to the combination of overburden and geological conditions. The computational results including longitudinal displacement contours and ground pressure profiles around the shield allow a better understanding of ground behavior within the excavation. Furthermore, they allow realistically assessing the impact of adverse geological conditions on shield jamming. The calculated thrust forces, which are required to move the machine forward, are in good agreement with field observations and measurements. It also proves that the numerical analysis can effectively be used for evaluating the effect of adverse geological environment on TBM entrapments and can be applied to prediction of loads on the shield and preestimating of the required thrust force during excavation through adverse ground conditions.

关键词： Single shielded tunnel boring machine(TBM) Numerical modeling Shield jamming Squeezing ground Uluabat tunnel

Prediction of TBM jamming risk in squeezing grounds using Bayesian and artificial neural networks

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2020年第1期12卷 21-31页

作者： Rohola Hasanpour Jamal Rostami Jürgen Schmitt yilmaz ozcelik Babak Sohrabian Institute for Tunneling and Construction Management Ruhr-University BochumBochumGermany Department of Mining Engineering Colorado School of MinesGoldenUSA Department of Civil Engineering Darmstadt University of Applied ScienceDarmstadtGermany Department of Mining Engineering Hacettepe UniversityAnkaraTurkey Faculty of Mining and Metallurgical Engineering Urmia University of TechnologyUrmiaIran

This study presents an application of artificial neural network(ANN)and Bayesian network(BN)for evaluation of jamming risk of the shielded tunnel boring machines(TBMs)in adverse ground conditions such as squeezing *** analysis is based on database of tunneling cases by numerical modeling to evaluate the ground convergence and possibility of machine *** results of initial numerical analysis were verified in comparison with some case studies.A dataset was established by performing additional numerical modeling of various scenarios based on variation of the most critical parameters affecting shield *** includes compressive strength and deformation modulus of rock mass,tunnel radius,shield length,shield thickness,in situ stresses,depth of over-excavation,and skin friction between shield and *** the dataset,an ANN was trained to predict the contact pressures from a series of ground properties and machine ***,the continuous and discretized BNs were used to analyze the risk of shield *** results of these two different BN methods are compared to the field observations and summarized in this *** developed risk models can estimate the required thrust force in both *** BN models can also be used in the cases with incomplete geological and geomechanical properties.

关键词： Bayesian network(BN) Artificial neural network(ANN) Shielded tunnel boring machine(TBM) Jamming risk Numerical simulation Squeezing ground

圆锥角膜患者使用Rose K2软性角膜接触镜的临床表现（英文）

在线全文

学校读者我要写书评

暂无评论

国际眼科杂志 2017年第8期17卷 1415-1418页

作者： Ihsan yilmaz Ferah ozcelik Gokhan Demir Gonul Durusoy Basak Saracoglu Muhittin Taskapili 贝约格鲁眼科医疗与研究医院土耳其伊斯坦布尔34420

目的:评价圆锥角膜患者使用Rose K2软性角膜接触镜的舒适度及视觉表现。方法:横断面研究。50例患者(50眼)接受全面的眼科检查,包括屈光度、裸眼视力(UCVA)、最佳矫正视力(BCVA)、裂隙灯显微镜及眼底检查、泪膜破裂时间(BUT)、角膜地形... 详细信息

目的:评价圆锥角膜患者使用Rose K2软性角膜接触镜的舒适度及视觉表现。方法:横断面研究。50例患者(50眼)接受全面的眼科检查,包括屈光度、裸眼视力(UCVA)、最佳矫正视力(BCVA)、裂隙灯显微镜及眼底检查、泪膜破裂时间(BUT)、角膜地形图和对比敏感度。戴镜后,测量最佳戴镜矫正视力(BCLCVA)、对比敏感度及舒适度通过平均视觉模拟量(VAS)呈现。结果:患者平均年龄为26.2±6.0(16~39)y。使用Rose K2软性角膜接触镜UCVA,BCVA,和BCLCVA的平均logMAR值依次为0.61±0.37(0.15~1.3),0.42±0.32(0~1.3)和0.18±0.20(0~1.3)。使用接触镜后视敏度显著提高(P<0.05),在明视和暗视条件下,对比敏感度数值明显增加(P<0.05)。Rose K2软性角膜接触镜的视觉模拟量(VAS)值为8.02±1.64(5~10)。结论:圆锥角膜患者使用Rose K2软性角膜接触镜能够改善视力,对比敏感度以及舒适度。

关键词：角膜接触镜圆锥角膜患者软性角膜接触镜

ELECTRORHEOLOGICAL PROPERTIES OF TALC POWDER/SILICONE OIL SUSPENSIONS UNDER DC FIELDS

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2007年第3期25卷 245-252页

作者： Hasim yilmaz Ummihan yilmaz Chemistry Department Sciences FacultyHarran University63190 OsmanbeySanliurfaTurkey Chemistry Department Sciences FacultyGazi University06500 TeknikokullarAnkaraTurkey

In this study, the electrorheological （ER） behavior of suspensions prepared from d50 = 2.4 lam talc powder, dispersed in insulating silicone oil （SO） medium was investigated. Sedimentation stabilities of suspensions （c = 5 wt%） prepared using these talc powder powders were determined to be 78 days. The ER activity of all the suspensions was observed to increase with increasing electric field strength, concentration and decreasing shear rate. The shear stress of talc powder suspensions increased linearly with increasing concentrations of the particles and with the applied electric field strength. Electric field viscosity of all the suspensions decreased sharply with increasing shear rate and showed a typical shear thinning non-Newtonian visco-elastic behavior. Effects of frequency on the ER activity of talc powder/SO system were also investigated.

关键词： Electrorheological fluids Talc powder/silicone oil suspensions Shear stress

Mechanistic Transformations Involving Radical and Cationic Polymerizations

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第3期38卷 205-212,I0004页

作者： Gorkem yilmaz Yusuf Yagci Istanbul Technical University Department of ChemistryMaslak34469 IstanbulTurkey Center of Excellence for Advanced Materials Research(CEAMR)and Department of Chemistry Faculty of ScienceKing Abdulaziz University21589 JeddahSaudi Arabia

Mechanistic transformation approach has been widely applied in polymer synthesis due to its unique feature combining structurally different polymers prepared by different polymerization *** methods for the formation of block and graft copolymers through mechanistic transformation involve almost all polymerizations ***,certain polymerization processes require extensive purification processes,which can be time-consuming and *** developments on controlled/living polymerizations involving radical and cationic mechanisms with the ability to control molecular weight and functionality led to new pathways for mechanistic *** this mini-review,we systematically discussed relevant advances in the field through three main titles namely(i)from radical to cationic mechanism,(ii)from cationic to radical mechanism,and(iii)application of specific catalyst systems for both radical and cationic polymerizations.

关键词： Transformation Radical polymerization Cationic polymerization Controlled/living polymerization Photopolymerization

ELECTRORHEOLOGICAL PROPERTIES OF DIATOMITE/SILICONE OIL SUSPENSIONS UNDER DC FIELDS

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2006年第5期24卷 463-471页

作者： Hasim yilmaz Chemistry Department Sciences FacultyHarran University63190 OsmanbeySanliurfaTurkey

In this study, electrorheological （ER） behavior of suspensions prepared from 3.0 and 9.0 μm diatomite particulate, dispersed in insulating silicone oil （SO） medium was investigated. Sedimentation stabilities of suspensions （c = 5 wt%） prepared using these diatomite powders were determined to be 32 days （d = 3 μm） and 24 days （d = 9 μm）, respectively. ER activity of all the suspensions was observed to increase with increasing electric field strength, concentration and decreasing shear rate. Shear stress of diatomite suspensions increased linearly with increasing concentrations of the particles and with the applied electric field strength. Electric field viscosity of all the suspensions decreased sharply with increasing shear rate and particle size, showing a typical shear thinning non-Newtonian visco-elastic behavior. Effects of high temperature and polar promoter onto ER activity ofdiatomite/SO system were also investigated.

关键词： Electrorheological fluids Diatomite/silicone oil suspensions Shear stress.

The geometric resistivity correction factor for several geometrical samples

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2015年第8期36卷 1-8页

作者： Serdar yilmaz Mersin University Science and Arts Faculty Physics Department Mersin University Advanced Technology Education Research and Application Center

This paper reviews the geometric resistivity correction factor of the 4-point probe DC electrical conduc- tivity measurement method using several geometrical samples. During the review of the literature, only the articles that include the effect of geometry on resistivity calculation were considered. Combinations of equations used for various geometries were also given. Mathematical equations were given in the text without details. Expressions for the most commonly used geometries were presented in a table for easy reference.

关键词： semiconductor four point probe conductivity measurement resistivity correction factor

Comparisons of the suture zones along a geotraverse from the Scythian Platform to the Arabian Platform

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2014年第6期5卷 855-875页

作者： Ali yilmaz Shota Adamia Hüseyin yilmaz Cumhuriyet University Engineering FacultyDepartment of Environmental EngineeringKayseri StreetCU.CampusTR-58140 SivasTurkey Nodia Institute of Geophysics 1M.Alexidze Str.0195TbilisiGeorgia Cumhuriyet University Engineering FacultyDepartment of Geophysical EngineeringTR-58140 SivasTurkey

The area from the Greater Caucasus to the southeast Turkey is characteri：;.ed and shaped by several major continental blocks. These are Scythian Platform, Pontian-Transcaucasu.,; Continent-Arc System （PTCAS）, the Anatolian-lranian and the Arabian Platforms. The aim of this paper is to define these continental blocks and describe and also compare their boundary relationships along the suture zones. The Scythian Platform displays the evidence of the Hercynian and Alpine orogens. This platform is separated from the PTCAS by the Greater Caucasus Suture Zone. The incipient collision began along this suture zone before middle-late Carboniferous whereas the final collision occurred before Oligocene. The PTCAS can be divided into four structural units：（1） the Georgian Block - northern part of the Pontian-Transcaucasian island-arc, （2） the southern and eastern Black Sea Coast-Adjara-Trialeti Unit, （3） the Artvin-Bolnisi Unit, comprising the northern part of the southern Transcaucasus, and （4） the Imbricated Bayburt-Garabagh Unit. The PTCAS could be separated from the Anatolian Iranian Platform by the North Anatolian-Lesser Caucasus Suture （NALCS） zone. The initial collision was developed in this suture zone during Senonian-early Eocene and final collision before middle Eocene or Oligocene-Miocene. The Anatolian-lranian Platform （AIP） is made up of the Tauride Platform and its metamorphic equivalents together with Iranian Platform. It could be separated from the Arabian Platform by the Southeastern Anatolian Suture （SEAS） zone. The collision ended before late Miocene along this suture zone. The southernmost continental block of the geotraverse is the Arabian Platform, which constitutes the northern part of the Arabian-African Plate. This platform includes a sequence from the Precambrian felsic volcanic and clastic rocks to the Campanian-early Maastrichtian fiyschoidal clastics. All the suture zones include MORB and SSZ-types ophiolites in different ages. However, the ages of

关键词： Scythian Plattorm Arabian Platform Suture zones Ceotraverse

Supergravity-induced interactions on thick branes

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第4期23卷 135-146页

作者： Nejat T.yilmaz Department of Electrical and Electronics Engineering Yassar UniversitySelsuk Yassar Kampüsü niversite CaddesiNo:35-37 AgaliYol35100 Bornova zmir Turkey

The gravity coupling of the symmetric space sigma model is studied in the solvable Lie algebra parametrization. The corresponding Einstein equations are derived and the energy-momentum tensor is calculated. The results are used to derive the dynamical equations of the warped five-dimensional （5D） geometry for localized bulk scalar interactions in the framework of thick brane world models. The Einstein and scalar field equations are derived for flat brane geometry in the context of minimal and non-minimal gravity-bulk scalar couplings.

关键词： supergravity branes 5D warped geometry symmetric spaces

Seasonal Variation of Cumulative CO_2 Emission from a Vertisol Under Apricot Orchard in Semi-Arid Southeast Turkey

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2012年第3期22卷 322-332页

作者： G.yilmaz Department of Environmental Engineering Harran UniversityS anliurfa 63100 (Turkey)

Understanding the factors affecting the CO 2 emission from agricultural practices is crucial for global warming.A study was performed in an apricot orchard field in the experimental farm of the Harran University,Southeast Turkey,to i) quantify weekly and seasonal variations of the CO 2 emissions from a Vertisol under apricot orchard;ii) evaluate the difference in CO 2 emission between the area under trees and rows;and iii) assess the relationships between the amounts of CO 2 emissions and environmental parameters for better use and management of the soils from the view point of carbon balance and flux in a semi-arid environment under drip *** CO 2 emission measurements were performed during May 2008 and May 2010,from both under tree crowns (CO 2-UC) and between tree rows (CO 2-BR),on a weekly basis in southeast Turkey with a semi-arid *** 2 emissions were statistically correlated with weather and soil parameters such as air temperature,relative humidity,rainfall,soil water content,and soil temperature at various depths from 5 to 100 *** weekly emissions ranged from 82 to 1 110 kg CO 2 ha 1 week 1 and from 96 to 782 kg CO 2 ha 1 week 1 in CO 2-UC and CO 2-BR,*** in CO 2 emission in the second year was due to increases in mean air and soil *** weekly and monthly cumulative CO 2 emissions were positively correlated with the air and soil *** linear regression analysis explained 35% and 83% variations in average weekly and monthly CO 2 emissions,by using meteorological *** the interaction effects of meteorological parameters in regression equations nearly doubled the variance explained by the regression *** to stepwise regression analysis,soil and air temperatures were found to have the most significant impact on the temporal variability of the soil CO 2 emission.

关键词： global warming meteorological data plowing soil temperature stepwise regression