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Stress analysis of thermally affected rotating nanoshafts with varying material properties

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Acta Mechanica Sinica 2016年第5期32卷 813-827页

作者： Keivan kiani Department of Civil Engineering K.N. Toosi University of Technology

Based on the surface elasticity theory of GurtinMurdoch, thermo-elastic fields within rotating nanoshafts with varying material properties subjected to a thermal field are explicitly examined. Accounting for the surface energy effect, the nonclassical boundary conditions are enforced in the cases of fixed-free and free-free conditions. The effects of variation of material properties, temperature of the environment, angular velocity, and radius of the outer radius on the radial displacement, hoop and radial stresses are investigated. In all performed studies, the role of the surface effect on the thermo-elastic field of the nanostructure is methodically discussed.

关键词： Rotating nanoshaft Thermo-elastic field Surface energy effect Non-classical boundary conditions Analytical modeling

Water Consumption of a Six-Year-Old River Red Gum Plantation in the Southern Zagros Mountains,Iran

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Journal of Mountain Science 2007年第2期4卷 136-145页

作者： Masoud EDRAKI Sayyed Ahang kowsar Department of Primary Industries Sunraysia Horticultural Centre PO Box 905Mildura Victoria Australia Fats Research Center for Agriculture and Natural Resources P.O. Box 71365-458 Shiraz LR. Iran

Water is the most important limiting factor in the development of arid environments; therefore, optimization of water use is a necessity in desert reclamation projects. Evapotranspiration of a 6-year-old river red gum （Eucalyptus camaldulensis Dehnh.） plantation, located in a sedimentation basin of an artificial recharge of the Gareh Bygone Plain groundwater system in Iran＇s southern Zagros Mountains, was studied during a 7-month period. A neutron moisture probe was used to monitor soil water changes in the root zone. Soil water depletion following rapid drainage for blocks receiving relatively high, medium and low volumes of foodwater were 809.6, 312.4, and 203.1 mm, respectively, for a 150-day period. Soil water potential during most of the study period was below -1.5 MPa. This study proves that river red gum in not a suitable species for desertification control where water conservation is of vital importance. Flood irrigation of trees on 8 Aug. 1991 provided the opportunity to throw doubt upon the claim of summer dormancy of river red gum.

关键词： Water consumption Eucalyptus camaldulensis desertification control Iran

On the limitations of linear beams for the problems of moving mass-beam interaction using a meshfree method

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Acta Mechanica Sinica 2012年第1期28卷 164-179页

作者： Keivan kiani Ali Nikkhoo Department of Civil Engineering Islamic Azad University Department of Civil Engineering University of Science and Culture

This paper deals with the capabilities of linear and nonlinear beam theories in predicting the dynamic response of an elastically supported thin beam traversed by a moving mass. To this end, the discrete equations of motion are developed based on Lagrange＇s equations via reproducing kernel particle method （RKPM）. For a particular case of a simply supported beam, Galerkin method is also employed to verify the results obtained by RKPM, and a reasonably good agreement is achieved. Variations of the maximum dynamic deflection and bending moment associated with the linear and nonlinear beam theories are investigated in terms of moving mass weight and velocity for various beam boundary conditions. It is demonstrated that for majority of the moving mass velocities, the differences between the results of linear and nonlinear analyses become remarkable as the moving mass weight increases, particularly for high levels of moving mass velocity. Except for the cantilever beam, the nonlinear beam theory predicts higher possibility of moving mass separation from the base beam compared to the linear one. Furthermore, the accuracy levels of the linear beam theory are determined for thin beams under large deflections and small rotations as a function of moving mass weight and velocity in various boundary conditions.

关键词： Nonlinear beam theory Moving mass-beam in- teraction Euler-Bernoulli beam theory - Reproducing kernel particle method (RKPM) Galerkin method (GM)

Modified consecutive modal pushover procedure for seismic investigation of one-way asymmetric-plan tall buildings

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Earthquake Engineering and Engineering Vibration 2012年第2期11卷 221-232页

作者： Faramarz Khoshnoudian Mahdi kiani Department of Civil Engineering Amirkabir University of TechnologyTehranIran

The effects of higher modes and torsion have a significant impact on the seismic responses of asymmetric-plan tall buildings. A consecutive modal pushover (CMP) procedure is one of the pushover methods that have been developed to consider these effects. The aim of this paper is to modify the (CMP) analysis procedure to estimate the seismic demands of one-way asymmetric-plan tall buildings with dual systems. An analysis of 10-, 15- and 20-story asymmetric-plan buildings is carried out, and the results from the modified consecutive modal pushover (MCMP) procedure are compared with those obtained from the modal pushover analysis (MPA) procedure and the nonlinear time history analysis (NLTHA). The MCMP estimates of the seismic demands of one-way asymmetric-plan buildings demonstrate a reasonable accuracy, compared to the results obtained from the NLTHA. Furthermore, the accuracy of the MCMP procedure in the prediction of plastic hinge rotations is better than the MPA procedure. The new pushover procedure is also more accurate than the FEMA load distribution and the MPA procedure.

关键词： modified consecutive modal pushover seismic demands nonlinear time history analysis asymmetric-plan tall buildings torsion

Evaluation of soil erodibility factor(k)for loess derived landforms of Kechik watershed in Golestan Province,North of Iran

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Journal of Mountain Science 2016年第11期13卷 2028-2035页

作者： Farshad kiani Aboutaleb GHEZELSEFLO Dept.of Soil Science Gorgan university of agricultural sciences and natural resourcesGorgan ***Iran Natural resources organization of Golestan province Gorgan ***Iran

The technique proposed by Wischmeier ＆ Smith for estimating the soil erodibility factor is among the most important methods in this regard. Given the high amounts of silt and lime content in loess soils of eastern parts of Golestan province in Iran, this study aims to evaluate the ability of Wischmeier ＆ Smith index to estimate the soil erodibility of this region. Soil erodibility was first obtained by Wischmeier nomograph and then was compared with the actual values obtained by selecting six plots and then performing physical and chemical tests on these samples. Using the nomograph, Wischmeier index was calculated to be about 0.05-0.092 Mg h MJ？1 mm？1. The results showed that Wischmeier index was 182, 4.11, 6 and 0.35 times than actual value in field with half-hour rainfall, Fournier index, SWAT value with half-hour rainfall and SWAT value with Fournier index, respectively. Obtained results showed that erodibility estimated by Wischmeier ＆ Smith index was higher than the actual measured value. Poor performance of this index in loess soils indicates the need for further research in this field.

关键词： Soil erodibility Loess Wischmeier nomograph Iran

Graphitization in CK 45 Steel

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Journal of Materials Science & Technology 2009年第2期25卷 164-168页

作者： A.R. kiani-Rashid Department of Materials Engineering Faculty of Engineering Ferdowsi University of Mashhad Mashhad Iran

The purpose of this study was to determine the influence of heat treatment cycle on graphite phase formation on CK 45 steel. The presence of well distributed graphite in the matrix is responsible for the good mechanical and thermal properties of this kind of alloy. Such properties include excellent wear resistance, higher resistance to thermal shock, and higher resistance to oxidation at high temperature. A number of specimens were made up of appropriate design to provide the experimental materials. The transformation phase to a free carbon microstructure during graphitization under different conditions was then examined for the most successful experimental steels. Austenitising temperature of 920℃ and the following isothermal heat treatment of 750℃ at different holding times were used. Microstructures were examined by OM （optical microscopy） and SEM （scanning electron microscopy）. Furthermore, it was found that isothermal transformation at 750℃ for different soaking times produced a typical microstructure. Also, the amount of graphite increased with increasing isothermal heat treatment time. Heat treatment leading to supersaturation of iron with carbon was described and some of the consequences of the supersaturation were presented. Finally, the formation of the thermodynamically stable state of the graphite taken from the supersaturated solid solution was discussed.

关键词： Graphitization Carbon Microstructure Heat treatment Phase transformation

Novel Photoinitiated Synthesis, Characterization, Thermal Kinetics, and Mechanism of Complex of Potassium Hexacyanoferrate with Imidazole

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Chemical Research in Chinese Universities 2009年第2期25卷 138-142页

作者： MAJID kowsar AHMAD Siraj MALIK Mukhtar Ahmad Department of Chemistry National Institute of Technology

Photoinitiated substitution complex of [Fe（CN）6]^4- with imidazole has been synthesized and characterized. On the basis of elemental analysis, the empirical molecular formula of the complex is K4[Fe（CN）5（C3H4N2）]·4H2O. The substitution of aquo ligand produced as a result of photoexcitation by imidazole has been confirmed by various spectroscopic thechniques like UV-Vis, FTIR, NMR, and SEM techniques. The characteristic FTIR and NMR absorption peaks for different entities present support the assigned formula. The presence of cyanide and imidazole ligands is shown by FTIR absorption peaks at 2046 cm^-1 due to v（C≡N） and at 1447 and 1619 cm^-1 due to v（C=N） and v（C=C） stretching vibration of the aromatic ring of imidazole, hence, confirming the assigned formula and photoinitiated substitution process. ^1HNMR also shows the peaks for aromatic hydrogen confirming again the presence of imidazole in the complex, further supporting the successful photoinitiated process. The water outside the coordination sphere has been confirmed from FTIR peaks and thermal analysis. Thermal kinetics and mechanistic studies have also been carried out by TG and DSC, Thermodynamics parameters such as activation energy（Ea）, preexponential factor（A）, and entropy of activation（Aft） have been calculated for each step via different methods like Doyle＇s, Coats, and Redfern and Arrehenius.

关键词： Photochemistry Potassium he.xacyanoferrate Imidazole Photosubstitution FTIR

Zn(NO_3)_2·6H_2O/2,4,6-trichloro-1,3,5-triazine(TCT) a mild and selective system for nitration of phenols

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Chinese Chemical Letters 2010年第4期21卷 403-406页

作者： Firouzeh Nemati Hossein kiani Department of Chemistry Faculty of ScienceSemnan UniversitySemnanIran

Certain phenols and naphthols were nitrated regioselectively with Zn(NO)·6HO/TCT in acetonitrile as solvent at room temperature and short reaction time in good *** reaction condition was *** is a cheap and commercial... 详细信息

关键词： Nitration Phenols 2 4 6-Trichloro-l 3 5-triazine Regioselective

Assessing dynamic response of multispan viscoelastic thin beams under a moving mass via generalized moving least square method

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Acta Mechanica Sinica 2010年第5期26卷 721-733页

作者： Keivan kiani Ali Nikkhoo Bahman Mehri Department of Civil Engineering Sharif University of Technology Department of Mathematical Sciences Sharif University of Technology

Dynamic response of multispan viscoelastic thin beams subjected to a moving mass is studied by an efficient numerical method in some detail. To this end, the unknown parameters of the problem are discretized in spatial domain using generalized moving least square method （GMLSM） and then, discrete equations of motion based on Lagrange＇s equation are obtained. Maximum deflection and bending moments are considered as the important design parameters. The design parameter spectra in terms of mass weight and velocity of the moving mass are presented for multispan viscoelastic beams as well as various values of relaxation rate and beam span number. A reasonable good agreement is achieved between the results of the proposed solution and those obtained by other researchers. The results indicate that, although the load inertia effects in beams with higher span number would be intensified for higher levels of moving mass velocity, the maximum values of design parameters would increase either. Moreover, the possibility of mass separation is shown to be more critical as the span number of the beam increases. This fact also violates the linear relation between the mass weight of the moving load and the associated design parameters, especially for high moving mass velocities. However, as the relaxation rate of the beam material increases, the load inertia effects as well as the possibility of moving mass separation reduces.

关键词： Moving mass-beam interaction - Multispan viscoelastic beam Euler-Bernoulli beam Generalized moving least square method (GMLSM)