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Structure Stability and Oxygen Permeability of Perovskite-type Oxides of Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.1)R_(0.1)O_ (3-δ)(R=Al,Mn,Fe,Ce,Cr,Ni,Co)

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Journal of Materials Science & Technology 2012年第2期28卷 177-183页

作者： Ensieh Ganji Babakhani Jafar Towfighi Laleh Shirazi Ali Nakhaeipour Akbar Zamaniyan Zahra Shafiei Gas department Research Institute of Petroleum Industry (RIPI) Chemical engineering department Engineering FacultyUniversity of Tarbiat Modares

Perovskite-type a0.5Sr0.5Co0.8Fe0.1R0.1O3-δ （R=Al, Mn, Fe, Ce, Cr, Ni, Co） oxide membranes were ex- ploited and synthesized. Oxygen behavior, order-disorder transition and phase stability of these composite oxides were investigated by combined analysis of X-ray diffraction （XRD）, temperature programmed desorp- tion （TPD）, thermogravimetric-differential thermal analysis （TG-DTA）. Oxygen permeation through these membranes was studied by the gas chromatography （GC） method using a high-temperature permeation cell in a wide temperature range from 700 to 950℃. High permeation fluxes were observed for these materials. The high permeation flux was about 3.19 ***-2 under air/He gradients at 950℃, which was achieved for a0.5Sr0.5Co0.8Fe0.1R0.1O3-δ（BSCFNiO） membrane. The results of analysis showed no phase transition for BSCFNiO oxide with increasing temperature and XRD pattern of this material after O2-TPD indicated to sustain a pure perovskite structure after oxygen permeation process.

关键词： Perovskite Ceramic membrane Oxygen separation Phase stability

Hot Extrusion Process Effect on mechanical Behavior of Stir Cast Al Based Composites Reinforced with mechanically Milled B_4C Nanoparticles

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Journal of Materials Science & Technology 2011年第12期27卷 1113-1119页

作者： A. Alizadeh E. Taheri-Nassaj M. Hajizamani department of Materials Science and engineering Tarbiat Modares University Faculty of Materials and Manufacturing Processes MUT University

In this study, aluminum alloy （Al-2 wt% Cu） matrix composites reinforced with I, 2 and 4 wt% boron carbide nanoparticles fabricated through mechanical milling with average size of 100 nm were fabricated via stir casting method at 850℃. Cast ingots of the matrix alloy and the composites were extruded at 500℃ at an extrusion ratio of 10：1 to investigate the effects of hot extrusion on the mechanical properties of the composites. The microstructures of the as-cast and the extruded composites were investigated by scanning electron microscopy （SEM）. Density measurement, hardness and tensile tests were carried out to identify the mechanical properties of the composites. The extruded samples revealed a more uniform distribution of B4C nanoparticles. Also, the extruded samples had strength and ductility values superior to those of the as-cast counterparts. In the as-cast and the extruded samples, with increasing amount of B4C nanoparticles, yield strength and tensile strength increased but e^ongation to fracture decreased.

关键词： Stir casting Hot extrusion Al matrix composite B4C nanoparticles mechanicalmilling

Application of different CFD multiphase models to investigate effects of baffles and nanoparticles on heat transfer enhancement

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Frontiers of Chemical Science and engineering 2014年第3期8卷 320-329页

作者： Ali SHAHMOHAMMADI Arezou JAFARI Chemical engineering department Tarbiat Modares University Tehran 114-14115 Iran

In this work, the effect of baffles in a pipe on heat transfer enhancement was studied using computa- tional fluid dynamics （CFD） in the presence of Al2O3 nanoparticles which are dispersed into water. Fluid flow through the horizontal tube with uniform heat flux was simulated numerically and three dimensional governing partial differential equations were solved. To find an accurate model for CFD simulations, the results obtained by the single phase were compared with those obtained by three different multiphase models including Eulerian, mixture and volume of fluid （VOF） at Reynolds numbers in range of 600 to 3000, and two different nanoparticle concentrations （1% and 1.6%）. It was found that multi- phase models could better predict the heat transfer in nanofluids. The effect of baffles on heat transfer of nanofluid flow was also investigated through a baffled geometry. The numerical results show that at Reynolds numbers in the range of 600 to 2100, the heat transfer of nanofluid flowing in the geometry without baffle is greater than that of water flowing through a tube with baffle, whereas the difference between these effects （nanofluid and baffle） decreases with increasing the Reynolds number. At higher Reynolds numbers （2100-3000） the baffle has a greater effect on heat transfer enhancement than the nanofluid.

关键词： CFD simulation heat transfer nanofluid,baffle single phase model multiphase model

Cell-based allometry:an approach for evaluation of complexity in morphogenesis

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Quantitative Biology 2023年第2期11卷 183-203页

作者： Ali Tarihi Mojtaba Tarihi Taki Tiraihi department of Computer engineering Faculty of Computer Science and EngineeringShahid Behshti UniversityTehran 19839-69411Iran department of Computer engineering Sharif University of TechnologyTehran 11365-11155Iran department of Anatomical Sciences School of Medical SciencesTarbiat Modares UniversityTehran 14117-13116Iran

Background:Morphogenesis is a complex process in a developing animal at the organ,cellular and molecular *** this investigation,allometry at the cellular level was ***:Geometric information,including the time-lapse Cartesian coordinates of each cell's center,was used for calculating the allometric coefficients.A zero-centroaxial skew-symmetrical matrix(CSSM),was generated and used for constructing another square matrix(basic square matrix:BSM),then the determinant of BSM was calculated(d).The logarithms of absolute d(Lad)of cell group at different stages of development were plotted for all of the cells in a range of development stages;the slope of the regression line was estimated then used as the allometric ***,the lineage growth rate(LGR)was also calculated by plotting the Lad against the logarithm of the *** complexity index at each stage was *** method was tested on a developing Caenorhabditis elegans ***:We explored two out of the four first generated blastomeres in *** *** ABp and EMS lineages show that the allometric coefficient of ABp was higher than that of EMS,which was consistent with the complexityindexas well ***:The conclusion of this study is that the complexity of the differentiating cells in a developing embryo can be evaluated by allometric scaling based on the data derived from the Cartesian coordinates of the cells at different stages of development.

关键词： embryogenesis allometry complexity C.elegans bioinformatics skew matrix morphogenesis

Inhibiting soil loss and runoff from small plots induced by an individual freeze-thaw cycle using three rangeland species

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International Soil and Water Conservation Research 2020年第3期8卷 228-236页

作者： Milad Hatefi Seyed Hamidreza Sadeghi Reza Erfanzadeh Morteza Behzadfar department of Watershed Management engineering Faculty of Natural ResourcesTarbiat Modares UniversityIran department of Rangeland Management Faculty of Natural ResourcesTarbiat Modares UniversityNoorIran

This study investigated the role of three rangeland species *** trichophorum,Medicago sativa,and Lolium prenne on mitigating of effects of a freeze-thaw(FT)cycle on runoff generation and soil loss from small experimental *** plots(0.5×0.5m)were prepared in three replicates for control(i.e.,under a FT cycle only)and treatments(i.e.,individually planted with the study species and subject to a FT cycle).The treated plots were then placed at a slope of 20%and subjected to simulated rainfall with intensity of 70 mm h-1 and 30 min *** results of the study showed a significant effect(P<0.05)of the plants on controlling runoff and soil loss after a FT ***,the detrimental effects of the FT cycle due to performance of ice lenses and formation of an active melting layer in the soil surface were ameliorated by the presence of litter on the soil and root-binding effect of the *** to runoff increased by 54,111 and 10%,runoff volume decreased by 27,68 and 0.4%and soil loss changed by-34,-62,and+6.5%in the plots planted with ***,*** and ***,*** results of the current study indicated that *** had the maximum benefit on reducing runoff and soil loss from the plots undergoing a FT cycle.

关键词： Biological measures Frosted soil Plant binding effects Soil hydrology

Wettability alteration and oil recovery by spontaneous imbibition of smart water and surfactants into carbonates

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Petroleum Science 2020年第3期17卷 712-721页

作者： Saeb Ahmadi Mostafa Hosseini Ebrahim Tangestani Seyyed Ebrahim Mousavi Mohammad Niazi department of Chemical engineering Sanandaj Branch Islamic Azad UniversitySanandajIran department of Petroleum engineering Faculty of Chemical EngineeringTarbiat Modares UniversityTehranIran Faculty of Chemical engineering Tarbiat Modares UniversityTehranIran

Naturally fractured carbonate reservoirs have very low oil recovery efficiency owing to their wettability and tightness of ***,smart water can enhance oil recovery by changing the wettability of the carbonate rock surface from oilwet to water-wet,and the addition of surfactants can also change surface *** the present study,the effects of a solution of modified seawater with some surfactants,namely C12 TAB,SDS,and TritonX-100(TX-100),on the wettability of carbonate rock were investigated through contact angle *** recovery was studied using spontaneous imbibition tests at 25,70,and 90°C,followed by thermal gravity analysis to measure the amount of adsorbed material on the carbonate *** results indicated that Ca2+,Mg2+,and SO42-.ions may alter the carbonate rock wettability from oil-wet to water-wet,with further water wettability obtained at higher concentrations of the ions in modified *** of NaCl from the imbibing fluid resulted in a reduced contact angle and significantly enhanced oil *** oil recoveries were obtained with modified seawater at 25 and 70°C,but once the temperature was increased to 90°C,the oil recovery in the spontaneous imbibition experiment increased *** of smart water with C12 TAB surfactant at 0.1 wt%changed the contact angle from 161°to 52°and enhanced oil recovery to 72%,while the presence of the anionic surfactant SDS at 0.1 wt%in the smart water increased oil recovery to 64.5%.The TGA analysis results indicated that the adsorbed materials on the carbonate surface were minimal for the solution containing seawater with C12 TAB at 0.1 wt%(SW+CTAB(0.1 wt%)).Based on the experimental results,a mechanism was proposed for wettability alteration of carbonate rocks using smart water with SDS and C12 TAB surfactants.

关键词： Smart water Surfactants Carbonate rock Wettability alteration

Methane hydrate stability in the presence of water-soluble hydroxyalkyl cellulose

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Journal of Natural Gas Chemistry 2012年第2期21卷 119-125页

作者： M. Mohammad-Taheri A. Zarringhalam Moghaddam K. Nazari N. Gholipour Zanjani Chemical engineering department Tarbiat Modares University Chemistry and Petrochemical Division Research Institute of Petroleum Industry

The effect of low-dosage water-soluble hydroxyethyl cellulose （approximate MW～90,000 and 250,000） as a member of hydroxyalkyl cellulosic polymer group on methane hydrate stability was investigated by monitoring hydrate dissociation at pressures greater than atmospheric pressure in a closed vessel. In particular, the influence of molecular weight and mass concentration of hydroxyethyl cellulose （HEC） was studied with respect to hydrate formation and dissociation. Methane hydrate formation was performed at 2℃ and at a pressure greater than 100 bar. Afterwards, hydrate dissociation was initiated by step heating from -10℃ at a mild pressure of 13 bar to 3℃, 0℃ and 2℃. With respect to the results obtained for methane hydrate formation/dissociation and the amount of gas uptake, we concluded that HEC 90,000 at 5000 ppm is suitable for long-term gas storage and transportation under a mild pressure of 13 bar and at temperatures below the freezing point.

关键词： hydrate stability dissociation kinetic low-dose polymer gas storage

Sediment contribution from different geologic formations and land uses in an Iranian small watershed,case study

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International Journal of Sediment Research 2017年第2期32卷 210-220页

作者： Seyed Hamidreza Sadeghi Saeed Najafi Alireza Riyahi Bakhtiari department of Watershed Management engineering Faculty of Natural ResourcesTarbiat Modares University department of Environmental Sciences Faculty of Natural ResourceTarbiat Modares University

Many intra and extra problems occurred due to unsustainable human use of natural resources leading to increasing sediment loads in the ***,few studies have been comprehensively conducted in progressing countries to prioritize sediment sources from different points of views,particularly in some countries like Iran where such valuable information is essential for proper watershed resources *** present study was therefore planned to assess the importance of potential sediment sources viz.,spatial sources(geologic units) and source types(land use units) in sediment yield in Idelo watershed as one of the important sub-watersheds of Sefidrood large Watershed in Zanjan Province,Iran,using composite *** addition,the results of the sediment fingerprinting approach were compared with those of field measurement data obtained from studying soil erosion types(viz.,sheet,rill and gully erosion).Toward this attempt,16 tracers were detected in different geologic units and land uses and the sediment yielded at the watershed *** results showed that the composite fingerprints of the different geologic units comprising As,N,Cu,Zn,OC and Co tracers could correctly distinguish 86% of the sediment source *** red gypsiferous marl contributed 85 percent in sediment *** regard to source types,the optimum composite fingerprint encompassed only N and Cu and provided a discriminatory efficiency of 90%.Besides that,the rangelands with 48.8% study area coverage had a significant contribution of 88% in sediment *** field measurements confirmed the reliability of results of fingerprinting approach in apportioning watershed scale sediment sources on the base of consistency of the two sets of *** was also understood from the results,besides successful applicability of composite fingerprinting in assessing the provenance of the sediment yielded at the watershed outlet that the geologic formations and land use types played differe

关键词： Composite fingerprinting Multivariate mixing model Soil erosion Spatial sources Source types

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