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Reliability and variance-based sensitivity analysis of arch dams during construction and reservoir impoundment

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Frontiers of Structural and Civil Engineering 2019年第3期13卷 526-541页

作者： m.Houshmand KHAnEGHAHI m.ALEmBAGHERI n.SOLTAnI Department of Civil Engineering Shahid Beheshti UniversityTehranIran Department of Civil and Environmental Engineering Tarbiat Modares UniversityTehranIran

The static performance of arch dams during construction and reservoir impoundment is assessed taking into account the effects of uncertainties presented in the model properties as well as the loading *** arch dam is chosen as the case study;it is modeled along with its rock foundation using the finite element method considering the stage *** previous studies concentrated on simplified models and approaches,comprehensive study of the arch dam model along with efficient and state-of-the-art uncertainty methods are incorporated in this *** reliability method is performed to assess the safety level and the sensitivity analyses for identifying critical input factors and their interaction effects on the response of the *** sensitivity analysis based on improved Latin hypercube sampling is employed in this study to indicate the influence of each random variable and their interaction on variance of the *** levels of model advancement are considered for the dam foundation system:1)monolithic dam without any joint founded on the homogeneous rock foundation,2)monolithic dam founded on the inhomogeneous foundation including soft rock layers,3)jointed dam including the peripheral and contraction joints founded on the homogeneous foundation,and 4)jointed dam founded on the inhomogeneous *** each model,proper performance indices are defined through limit-state *** this manner,the effects of input parameters in each performance level of the dam are *** outcome of this study is defining the importance of input factors in each stage and model based on the variance of the dam ***,the results of sampling are computed in order to assess the safety level of the dam in miscellaneous loading and modeling conditions.

关键词： concrete arch dams reliability randomness improved Latin hypercube sampling variance-based sensitivity analysis exceedance probability Sobol index

Supersonic Shock Wave with Landau Quantization in a Relativistic Degenerate Plasma

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Chinese Physics Letters 2020年第1期37卷 34-38页

作者： m.Kr.Deka A.n.Dev Department of Applied Sciences Gauhati UniversityGuwahati-781014AssamIndia Center for Applied mathematics and Computing Siksha O Anusandhan(Deemed to be University)Bh u baneswar-751030OdishaIndia

A three-dimensional(3D)BurgersJ equation adopting perturbative methodology is derived to study the evolution of a shock wave with Landau quantized magnetic field in relativistic quantum *** characteristics of a shock wave in such a plasma under the influence of magnetic quantization,relativistic parameter and degenerate electron density are studied with assistance of steady state *** magnetic field has a noteworthy control,especially on the shock wave's amplitude in the lower range of the electron density,whereas the amplitude in the higher range of the electron density reduces *** rate of increase of shock wave potential is much higher(lower)with a magnetic Held in the lower(higher)range of electron *** the relativistic factor,the shock wave's amplitude increases significantly and the rate of increase is higher(lower)for lower(higher)electron *** combined effect of the increase of relativistic factor and the magnetic field on the strength of the shock wave,results in the highest value of the wave potential in the lower range of the degenerate electron density.

关键词： density. solution. relativistic

Low temperature thermoluminescence behaviour of Y_2O_3 nanoparticles

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Journal of Rare Earths 2019年第1期37卷 19-23,M0002页

作者： S.Delice m.Isik n.m.Gasanly Department of Physics Hitit University Department of Electrical and Electronics Engineering Atilim University Department of Physics Middle East Technical University Virtual International Scientific Research Centre Baku State University

Y_2O_3 nanoparticles were investigated using low temperature thermoluminescence (TL) experiments. TL glow curve recorded at constant heating rate of 0.4 K/s exhibits seven peaks around 19, 62, 91,115,162,196 and 215 K. Activation energies and characteristics of traps responsible for observed curves were revealed under the light of results of initial rise analyses and T_(max)-T_(stop) experimental methods. Analyses of TL curves obtained at different stopping temperatures resulted in presence of one quasi-continuously distributed trap with activation energies increasing from 18 to 24 meV and six single trapping centers at49, 117, 315, 409, 651 and 740 meV. Activation energies of all revealed centers were reported in the present paper. Structural characterization of Y_2O_3 nanoparticles was accomplished using X-ray diffraction and scanning electron microscopy measurements.

关键词： Y2O3 Luminescence Thermoluminescence Defects Rare earths

Effect of non-uniform temperature gradient and magnetic field on onset of marangoni convection heated from below by a constant heat flux

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Applied mathematics and mechanics(English Edition) 2010年第7期31卷 797-804页

作者： S.P.m.ISA n.m.ARIFIn R.nAZAR m.n.SAAD Institute for mathematical Research Universiti Putra Malaysia School of mathematical Sciences Universiti Kebangsaan Malaysia

This paper investigates the effect of non-uniform temperature gradient and magnetic field on marangoni convection in a horizontal fluid layer heated from below and cooled from above with a constant heat flux. A linear stability analysis is performed. The influence of various parameters on the convection onset is analyzed. Six non-uniform basic temperature profiles are considered, and some general conclusions about their desta- bilizing effects are presented.

关键词： maxangoni convection non-uniform temperature magnetic field

Structural morphological and Optical Properties of SnSb_2S_4 Thin Films Grown by Vacuum Evaporation method

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Journal of materials Science & Technology 2014年第10期30卷 1006-1011页

作者： n.Khedmi m.Ben Rabeh m.Kanzari Laboratoire de Photovoltaques et matriaux de Semi-conducteurs-EnIT-Universit de Tunis el manar BP 37le belvedere1002 TunisTunisie Laboratoire de Photovoltaques et matriaux de Semi-conducteurs-EnIT-IPEITunis montfleury-Universit de Tunis Tunisie

SnSb2S4 thin films were prepared from powder by thermal evaporation under vacuum of 1.33 × 10^-4 Pa （ 10^-6 Torr） on unheated glass substrates. The effect of thickness on the structural, morphological and optical properties of SnSb2S4 thin films was investigated. Films thickness measured by interference fringes method varied from 50 to 700 nm. X-ray diffraction analysis revealed that all the SnSb2S4 films were polycrystalline in spite without heating the substrates and the crystallinity was improved with increasing film thickness. The microstructure parameters： crystallite size, strain and dislocation density were calculated. It was observed that the crystallite size increased and the crystal defects decreased with increasing film thickness. In addition, by increasing the film thickness, an enhancement in the surface roughness root-mean-square （RmS） increased from 2.0 to 6.6 nm. The fundamental optical parameters like band gap, absorption and extinction coefficient were calculated in the strong absorption region of transmittance and reflectance spectrum. The optical absorption measurements indicated that the band （Eg） gap of the thin films decreased from 2.10 to 1.65 eV with increasing film thickness. The refractive indexes were evaluated in transparent region in terms of envelope method, which was suggested by Swanepoul. It was observed that the refractive index increased with increasing film thickness.

关键词： Ternary system Thermal evaporation technique Thin films Thickness Atomic force microscopy (AFm)

Ion acoustic shock and periodic waves through Burgers equation in weakly and highly relativistic plasmas with nonextensivity

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Plasma Science and Technology 2017年第1期19卷 7-19页

作者： m G HAFEZ n C ROY m R TALUKDER m HOSSAIn ALI Department of of Applied mathematics University of Rajshahi Rajshahi-6205 Bangladesh Department of mathematics Chittagong University of Engineering and Technology Chittagong-4349Bangladesh Plasma Science and Technology Lab Department of Applied Physics and Electronic EngineeringUniversity of Rajshahi Rajshahi-6205 Bangladesh

A comparative study is carried out for the nonlinear propagation of ion acoustic shock waves both for the weakly and highly relativistic plasmas consisting of relativistic ions and qdistributed electrons and *** Burgers equation is derived to reveal the physical phenomena using the well known reductive perturbation *** integration of the Burgers equation is performed by the（G￠/G）-expansion *** effects of positron concentration,ion–electron temperature ratio,electron–positron temperature ratio,ion viscosity coefficient,relativistic streaming factor and the strength of the electron and positron nonextensivity on the nonlinear propagation of ion acoustic shock and periodic waves are presented graphically and the relevant physical explanations are provided.

关键词： electron-positron-ion plasmas ion acoustic shock and periodic waves weakly and highly relativistic effects Burgers equation

Identification of Iron Oxides Qualitatively/Quantitatively Formed during the High Temperature Oxidation of Superalloys in Air and Steam Environments

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Journal of materials Science & Technology 2009年第4期25卷 479-482页

作者： m. Siddique n. Hussain m. Shafi Physics Division PINSTECH materials Division PINSTECH

mossbauer spectroscopy has been used to study the morphology of iron oxides formed during the oxidation of superalloys, such as SS-304L （1.4306S）, Incoloy-800H, Incoloy-825, UBHA-25L, Sanicro-28 and Inconel-690, at 1200℃ exposed in air and steam environments for 400 h. The basic aim was to identify and compare the iron oxides qualitatively and quantitatively, formed during the oxidation of these alloys in two environments. The behaviour of alloy UBHA-25L in high temperature oxidation in both environments indicates that it has good oxidation resistance especially in steam, whereas Sanicro-28 has excellent corrosion resistance in steam environment. In air oxidation of Inconel-690 no iron oxide, with established mossbauer parameters, was detected.

关键词： Superalloys mossbauer spectroscopy Oxidation Corrosion products

Predicting effects of tunnel throttling of annular freeway vehicular flow by a continuum model

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第4期11卷 733-746页

作者： Zhongmin Huang m.n.Smirnova n.n.Smirnov Zuojin Zhu Faculty of Engineering Science University of Science and Technology of ChinaHefei 230026China Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Faculty of mechanics and mathematics Lomonosov Moscow State UniversityMoscow 119992Russia

Fluid flow throttling is common in industrial and building services *** tunnel throttling of vehicular flow is caused by the abrupt number reduction of roadway lane,as the tunnel has a lower lane number than in the roadway normal *** predict the effects of tunnel throttling of annular freeway vehicular flow,a three-lane continuum model is ***Ⅲof the tunnel is completely blocked due to the need of tunnel rehabilitation,*** exists mandatory net lane-changing rate from laneⅢto laneⅡjust upstream of the tunnel entrance,which is described by a model of random number generated through a golden section *** net-changing rate between adjacent lanes is modeled using a lane-changing time expressed explicitly in algebraic *** paper assumes that the annular freeway has a total length of 100 km,a two-lane tunnel of length 2 km with a speed limit of 80 km/*** free flow speeds on lanesⅠ,ⅡandⅢare assumed to be 110,100 and 90 km/h *** on the three-lane continuum model,numerical simulations of vehicular flows on the annular freeway with such a tunnel are conducted with a reliable numerical method of 3rd-order *** results reveal that the vehicular flow has a smaller threshold of traffic jam formation in comparison with the case without tunnel *** fuel consumption can be estimated by interpolation with time averaged grid traffic speed and an assumed curve of vehicle *** vehicle fuel consumption is lane number dependent,distributes with initial density concavely,ranging from 5.56 to 8.00 *** throttling leads to an earlier traffic jam formation in comparison with the case without tunnel throttling.

关键词： Effects of tunnel throttling Vehicle fuel consumption Travel time Threshold of traffic jam formation Continuum model

Performance evaluation of minimum quantity lubrication by vege-table oil in terms of cutting force,cutting zone temperature,tool wear,job dimension and surface finish in turning AISI-1060 steel

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第11期7卷 1790-1799页

作者： KHAn m.m.A. DHAR n.R. Department of Industrial and Production Engineering Shahajalal University of Science and Technology Sylhet 3114 Bangladesh Department of Industrial and Production Engineering Bangladesh University of Engineering and Technology (BUET) Dhaka Bangladesh

In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (mQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of mQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by mQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.

关键词： minimum quantity lubrication (mQL) Cutting force Chip-tool interface temperature Tool wear Surface roughness Dimensional deviation