检索结果-南通市图书馆

International Journal of Minerals,Metallurgy and Materials 2016年第4期23卷 434-441页

作者： Hamid Sazegaran Ali-Reza kiani-Rashid Jalil Vahdati Khaki Department of Materials Science and Metallurgical Engineering Engineering Faculty Ferdowsi University of Mashhad

Metallic hollow spheres are used as base materials in the manufacture of hollow sphere structures and metallic foams. In this study, steel hollow spheres were successfully manufactured using an advanced powder metallurgy technique. The spheres＇ shells were characterized by optical microscopy in conjunction with microstructural image analysis software, scanning electron microscopy（SEM）, energy-dispersive X-ray spectroscopy（EDX）, and X-ray diffraction（XRD）. The microscopic evaluations revealed that the shells consist of sintered iron powder, sintered copper powder, sodium silicate, and porosity regions. In addition, the effects of copper content on various parameters such as shell defects, microcracks, thickness, and porosities were investigated. The results indicated that increasing the copper content results in decreases in the surface fraction of shell porosities and the number of microcracks and an increase in shell thickness.

关键词： steel hollow spheres powder metallurgy copper content shell characteristics

Simultaneous approximation of a function and its derivatives by Sobolev polynomials: Applications in satellite geodesy and precise orbit determination for LEO CubeSats

在线全文

学校读者我要写书评

暂无评论

Geodesy and Geodynamics 2020年第5期11卷 376-390页

作者： M.kiani Graduated from Department of Geodesy School of Surveying and Geospatial Data EngineeringUniversity of TehranTehranIran

The objectives of this paper are twofold:(1) to present a new method of approximation such that the function and some of its derivatives are simultaneously approximated;and(2) to investigate the potential applications of this new method in the field of satellite geodesy by deriving a numerical solver of ordinary differential equations. To fulfill both the objectives, Sobolev polynomials are used. Explicit formulas for these polynomials are presented. A quadrature rule is derived based on the explicit forms of these polynomials. Solution of first order ordinary differential equations is presented based on the numerical integration method by the new quadrature rule. To present the applications of the results, three problems are investigated in the field of satellite geodesy. In the first application, orbit propagated by the numerical solution of orbital equations is compared with the Keplerian motion. It is shown that the new method for solving ordinary differential equations can be used alongside any other method, including the adaptive Runge-Kutta and Adams-Bashforth-Moulton integration methods. The comparison of this new method with the adaptive Runge-Kutta, Adams-Bashforth-Moulton, and the powerful and newly established adaptive Gaussian numerical integration methods reveals that it is at least 580, 666667, and72 times more accurate than the mentioned methods, respectively, in any given absolute tolerance and time increment. The method is fast, stable, consistent, and capable of handling high accuracy, even with large time increment and low absolute tolerance, which is shown in this application. In the second application, the Gravity Recovery and Climate Experiment(GRACE) satellites’ orbits are propagated using both the Ensemble Kalman Filter(EnKF) with stochastic updates and smoothing for the position and the Sobolev numerical integration. The orbits are then compared with the observed positions of the satellites. It is shown that the Sobolev polynomials work bet

关键词： numerical approximation ordinary

Improvements in mechanical, corrosion, and biocompatibility properties of Mg–Zr–Sr–Dy alloys via extrusion for biodegradable implant applications

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2023年第10期11卷 3840-3865页

作者： Faisal kiani Jixing Lin Khurram Munir Cuie Wen Yuncang Li School of Engineering RMIT UniversityMelbourneVictoria 3001Australia School and Hospital of Stomatology Wenzhou Medical UniversityWenzhou 325027China

In this study,extrusion was performed on Mg-Zr-Sr-Dy alloys for improving their mechanical,corrosion,and biocompatibility *** of extrusion and alloying elements on the microstructural characteristics,tensile and compressive strengths,corrosion behavior,and biocompatibility were *** Mg-Zr-Sr-Dy alloys were composed of an α-Mg matrix containing {10■2} extension twins and secondary phases of intermetallic compounds Mg_(17)Sr_(2) and Mg_(2)*** of basal and rare earth(RE) textures was observed in the extruded alloys and an increase in Dy content to 2 wt.% resulted in texture randomization and strengthening of the RE component,mainly due to particle-stimulated nucleation and a change from discontinuous dynamic recrystallization to continuous dynamic recrystallization,which also led to an improved tension-compression yield asymmetry of *** of the alloys significantly enhanced their tensile and compressive properties due to improved distribution of alloying elements and formation of *** rates tested by hydrogen evolution testing,potentiodynamic polarization,and electrical impedance spectroscopy showed similar trends for each composition,and the lowest corrosion rate of 3.37 mmy^(-1) was observed for the Mg-1Zr-0.5Sr-1Dy in the potentiodynamic polarization ***_(2)O_(3) was observed in the inner layers of the Mg(OH)_(2) protective films,whose protective efficacy was confirmed by charge-transfer and film resistances.A comparison among the minimum CRs observed in this study and previously studied as-cast Mg-Zr-Sr-Dy and extruded Mg-Zr-Sr alloys,demonstrates that both the extrusion process and addition of Dy in Mg-Zr-Sr improved the ***,extruded Mg-Zr-Sr-Dy alloys showed improved cell viability and adhesion of human osteoblast-like SaOS2 cells due to increased corrosion resistance and enhanced Sr distribution within the Mg matrix.

关键词： Corrosion Microstructure mechanical properties Cytotoxicity Mg–Zr–Sr–Dy alloy

Evaluation of seed quality and oil parameters in native Iranian almond(Prunus ***.) species

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2015年第1期26卷 115-122页

作者： Soghra kiani Shakiba Rajabpoor Karim Sorkheh Sezai Ercisli Department of Agriculture Payame Noor University Department of Biology Payame Noor University Department of Agronomy and Plant Breeding Faculty of Agriculture Shahid Chamran University of Ahvaz Department of Horticulture Agricultural FacultyAtaturk University

We assessed chemical composition and variation in oil content and seed weight of 40 wild-growing almonds（Prunus L. spp.） accessions collected from different parts of Iran. There were significant differences in kernel weight and oil parameters. Accessions ranged from0.20 to 1.5 g in kernel weight, 0.2–3.0 mm in shell thickness, and 16–55 % in oil content. The predominant vegetable oil components of kernels were 4.6–9.5 % palmitic acid, 0.4–0.8 % palmitoleic acid, 1.0–3.4 % stearic acid,48.8–88.4 % oleic acid and 11.3–33.2 % linoleic *** acid was detected in 15 accessions. High heritability was recorded for all studied traits and was maximum for shell thickness（98.5 %） and minimum for oil content（97.1 %）. Maximum and minimum ‘Euclidean＇pair wise dissimilarities were 17.9 and 0.5, *** 40 accessions were grouped into two major clusters.

关键词： Genetic diversity Kernel quality Oil parameters Wild almond(Prunus L.spp.)

Changes induced by osmotic stress in the morphology, biochemistry, physiology, anatomy and stomatal parameters of almond species(Prunus L. spp.) grown in vitro

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2014年第3期25卷 523-534页

作者： Shakiba Rajabpoor Soghra kiani Karim Sorkheh Farahnaz Tavakoli Department of Biology Payam e Noor University Department of Agriculture Payam e Noor University Department of Agronomy and Plant Breeding Faculty of Agriculture Shahid Chamran University of Ahwaz Department of Plant Breeding and Biotechnology Faculty of Agriculture Shahrekord University

We investigated the influence of different levels of osmotic stress on growth and development in selected wild almond species （eight Prunus spp.） grown in vitro. The study, while endorsing the efficacy of in vitro screening of auxiliary buds of wild almond for osmotic stress tolerance, showed species variability in its response to osmotic stress. Osmotic stress reduced growth and development of all the species. How-ever, the putative tolerant Prunus spp. showed better performance than the putative susceptible genotypes. On average there was an 80% de-crease in shoot dry weight at -1.2 MPa. Reduction in shoot weight was more common in osmotic stress-susceptible species in the section labeled‘Euamygdalus’. The tolerant Prunus species produced smaller changes in biochemical responses than the sensitive cultivars for malondialdehyde content, catalase activity, relative permeability of protoplast membranes, and net photosynthetic rate. The tolerant species maintained cell integrity better than drought sensitive species. Wild almond species in the section labeled ‘Spartioides’ （Prunus arabica （Olivier） Neikle, Prunus glauca＆amp;nbsp;（Browicz） A.E. Murray, Prunus scoparia Spach） and ‘Lycioides’ （Pru-nus lycioides Spach, Prunus reuteri Bossi. et Bushe） were best adapted to osmotic stress. Increase in chlorophyll concentration and leaf thickness under high osmotic stress can be considered as preliminary selection parameters for osmotic stress tolerance in Prunus spp. The study con-firmed the efficacy of the in vitro method for screening of large number of genotypes for osmotic stress tolerance in wild almond species.

关键词： Prunus spp. proline osmotic stress leaf character malon-dialdehyde protoplast membrane permeability

Estimating oak forest parameters in the western mountains of Iran using satellite-based vegetation indices

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2020年第2期31卷 541-552页

作者： Adel Nouri Bahman kiani Mohammad Hossein Hakimi Mohammad Hossein Mokhtari Department of Forest Sciences Faculty of Natural ResourcesYazd UniversityYazdIslamic Republic of Iran Department of Desert Management Faculty of Natural ResourcesYazd UniversityYazdIslamic Republic of Iran

Remote sensing is an important tool for studying and modeling forest *** indices obtained from Landsat-8 remotely sensed data were used to estimate the forest parameters in the western mountains of *** sample points were selected on the map of Bayangan County,Kermanshah province,*** each point,a cluster of five rectangular plots of 8100 m2 and 200 m apart was *** clusters were primarily sampled to determine the variance of the forest *** coefficient of variation was used as a criterion for sample *** density,canopy cover and basal area per hectare were calculated for each *** indices were extracted fromthe Landsat-8 images for each *** linear and nonlinear regressions were conducted to develop the *** models were validated using an independent data *** of model parameters was statistically *** results showed that Normalized difference vegetation index(NDVI)and Transformed normalized difference vegetation index(TNDVI)followed by Simple ratio vegetation index(SRVI)were the best predictors,explaining up to 91%of the variations with high *** NDVI,Soil adjusted vegetation index 2(SAVI2)and SRVI,the cubic model was more appropriate than the linear model for predicting the forest *** this model,the R-square value increased while NRMSE decreased *** Infrared percentage vegetation index(IPVI),the quadratic model was better,but,for other vegetation indices,nonlinear models were not superior to linear ***,it can be concluded that Landsat-8 imagery is suitable for predicting forest parameters in the oak forests of western *** course,large plots must be selected,and pre-classification is necessary to gain accurate and precise estimations.

关键词： Basal area Canopy cover Density Landsat-8 Modeling

Heat transfer and Helmholtz-Smoluchowski velocity in Bingham fluid flow

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2020年第8期41卷 1167-1178页

作者： A.SALEEM M.N.kiani S.NADEEM A.ISSAKHOV Mathematics and Its Applications in Life Sciences Research Group Ton Duc Thang UniversityHo Chi Minh 7000Vietnam Faculty of Mathematics and Statistics Ton Duc Thang UniversityHo Chi Minh 7000Vietnam Department of Mathematics Quaid-i-Azam UniversityIslamabad 44000Pakistan Faculty of Mechanics and Mathematics Al-Farabi Kazakh National UniversityAlmaty 0500Kazakhstan

A mathematical study is developed for the electro-osmotic flow of a nonNewtonian fluid in a wavy microchannel in which a Bingham viscoplastic fluid model is *** electric potential distributions,a Poisson-Boltzmann equation is employed in the presence of an electrical double layer(EDL).The analytical solutions of dimensionless boundary value problems are obtained with the Debye-Huckel theory,the lubrication theory,and the long wavelength *** effects of the Debyelength parameter,the plug flow width,the Helmholtz-Smoluchowski velocity,and the Joule heating on the normalized temperature,the velocity,the pressure gradient,the volumetric flow rate,and the Nusselt number for heat transfer are evaluated in detail using *** analysis provides important findings regarding heat transfer in electroosmotic flows through a wavy microchannel.

关键词： electro-osmosis Bingham viscoplastic fluid electric double layer(EDL) heat transfer Joule heating

Spatial Variability of Soil Organic Carbon in Different Hillslope Positions in Toshan Area, Golestan Province, Iran: Geostatistical Approaches

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2015年第6期12卷 1422-1433页

作者： Abolfazl BAMERI Farhad KHORMALI Farshad kiani Amir Ahmad DEHGHANI Dept. of Soil Science Gorgan University of Agricultural Sciences and Natural Resources Dept. of Water Engineering Gorgan University of Agricultural Sciences and Natural Resources

Accessibility to organic carbon(OC) budget is required for sustainable agricultural development and ecosystem preservation and restoration. Using geostatistical models to describe and demonstrate the spatial variability of soil organic carbon(SOC) will lead to a greater understanding of this dynamics. The aim of this paper is to present the relationships between the spatial variability of SOC and the topographic features by using geostatistical methods on a loess mountain-slope in Toshan region, Golestan Province, northern Iran. Hence, 234 soil samples were collected in a regular grid that covered different parts of the slope. The results showed that such factors as silt, clay, saturated moisture content, mean weighted diameter(MWD) and bulk density were all correlated to the OC content in different slope positions, and the spatial variability of SOC more to slope positions and elevations. The coefficient of variation(CV) indicated that the variability of SOC was moderate in different slope positions and for the mountain-slope as a whole. However, the higher variability of SOC(CV = 45.6%) was shown in the back-slope positions. Also, the ordinary cokriging method for clay as covariant gave better results in evaluating SOC for the whole slope with the RMSE value 0.2552 in comparison with the kriging and the inverse distance weighted(IDW) methods. The interpolation map of OC for the slope under investigation showed lowering SOC concentrations versus increasing elevation and slope gradient. The spatial correlation ratio was different between various slope positions and related to the topographic texture.

关键词： Geostatistics Loess Soil organic carbon(SOC) Slope position Spatial heterogeneity Topography

Investigation of salinity impacts on germination and growth of two forest tree species at seedling stage

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2013年第4期24卷 703-708页

作者： Seyed Mohammad Hosseini Nasr Sekineh kiani Savadkoohi Elahe Ahmadi Department of Forestry Sari Agricultural Sciences and Natural Resources University

Soil salinity is becoming an increasingly serious constraint to plant growth in many parts of the world; this is particularly common in semi-arid and arid zones. This study was conducted to evaluate the effect of different concentrations of salt on seed germination and seedling growth of Acacia albida and A. salicina. Collected seeds were treated with H2SO4 98% for 35 min then left to germinate in a controlled growth chamber. Seeds were grown at salinity levels of 0.1, 0.2 and 0.3 mol.L1 of NaH2PO4.H20. Germination parameters and seedling growth indices were measured after 35 days. The mean of total length ofA. salicina in all salinity concentrations was more than that of ：4. albida. The fresh weight of stem and root of ：4, albida was more than that of ：4. salicina. Growth of control seedlings was higher than for other treatments and the fresh weight of stems of two species at salt concentrations of 0.2 and 0,3 *** decreased with increasing concentration of salt. Most Control seeds germinated at salinity of 0.1 *** and germination index, final germination and seeds stamina was greater at low levels of salinity.

关键词： soil salinity germination salt concentration Acacia albida,Acacia salicina.

Development and magnetic properties of loess-derived forest soils along a precipitation gradient in northern Iran

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2019年第8期16卷 1848-1868页

作者： Masoumeh POURMASOUMI Farhad KHORMALI Shamsollah AYOUBI Martin KEHL Farshad kiani Department of Soil Science Faculty of Water and Soil EngineeringGorgan University of Agricultural Sciences and Natural ResourcesGorganIran Department of Soil Science College of AgricultureIsfahan University of Technology84156-83111 IsfahanIran Institute of Geography University of CologneAlbertus-Magnus-PlatzD-50923 CologneGermany

In order to investigate the development of forest soils formed on loess, six representative modern soil pedons were selected along a precipitation gradient extending from eastern Golestan(mean annual precipitation, MAP = 500 mm)to eastern Mazandaran Provinces(MAP = 800 mm).Physiochemical, micromorphological and magnetic properties, as well as clay mineralogy of soils were studied using standard methods. Soils are mainly classified as Alfisols and Mollisols. Downward decalcification and the subsequent clay illuviation were the main criteria of soil development in all study areas. Pedogenic magnetic susceptibility of pedons studied varied systematically across the precipitation gradient in Northern Iran, increasing from 14.66 ×10-8 m3 kg-1 at the eastern part to 83.75 × 10-8 m3 kg-1 at the western margin of this transect. The frequencydependent magnetic susceptibility showed an increasing trend with rainfall as well. The micromorphological study of soils indicated that there is a positive relationship between climate gradient (increasing rainfall) and the micromorphological index of soil development(MISECA). The area and thickness of clay coatings showed an increasing trend with rainfall. Grain size analysis indicates that pedogenic processes are responsible for changing original grain size distribution of loess in our *** correlation achieved among modern soil properties and precipitation could be applied to the buried paleosols in the whole study area to refer degree of paleosol development and to reconstruct the paleoclimate.

关键词： Magnetic properties Soil formation Weathering Precipitation gradient Loess Iran