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Experimental study on the effects of artificial bed roughness on turbidity currents over abrupt bed slope change

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International Journal of Sediment Research 2020年第3期35卷 256-268页

作者： Sara Baghalian masoud Ghodsian Civil and Environmental Engineering Tarbiat Modares University Civil and Environmental Engineering and Water Engineering Research Institute Tarbiat Modares University

A series of experimental observations are presented in the current study to discuss the effects of artificial bed roughness on the turbidity current flowing in a rectangular channel with an abrupt change in bed *** this purpose,two different types of elements,sinusoidal and trapezoidal,with various heights and arrangements are considered as artificial bed roughness.A Vectrino velocity meter was used to measure the velocity and sediment concentration *** effects of inlet sediment concentration on front velocity,body velocity,unit discharge,sediment concentration,and suspended load transport rate also were *** equations were developed for estimation of the velocity of a turbidity current over smooth and rough *** unexpected experimental results showed that unlike the effect of roughness height,a change in the roughness arrangement has no significant influence on the velocity of a turbidity ***,the effect of bed roughness on the front velocity of a denser current is more significant.

关键词： Experimental analysis Turbidity current Bed roughness Slope break Velocity profile Concentration profile

Skill Assessment of Copernicus Climate Change Service Seasonal Ensemble Precipitation Forecasts over Iran

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Advances in Atmospheric Sciences 2021年第3期38卷 504-521页

作者： masoud NOBAKHT Bahram SAGHAFIAN Saleh AMINYAVARI Department of Civil Engineering Science and Research BranchIslamic Azad UniversityTehran ***Iran Department of Civil Engineering Chalous BranchIslamic Azad UniversityChalous 46615/397Iran

Medium to long-term precipitation forecasting plays a pivotal role in water resource management and development of warning ***,the Copernicus Climate Change Service(C3S)database has been releasing monthly forecasts for lead times of up to three months for public *** study evaluated the ensemble forecasts of three C3S models over the period 1993-2017 in Iran’s eight classified precipitation clusters for one-to three-month lead *** and non-probabilistic criteria were used for ***,the skill of selected models was analyzed in dry and wet periods in different precipitation *** results indicated that the models performed best in western precipitation clusters,while in the northern humid cluster the models had negative skill *** models were better at forecasting upper-tercile events in dry seasons and lower-tercile events in wet ***,with increasing lead time,the forecast skill of the models *** terms of forecasting in dry and wet years,the forecasts of the models were generally close to observations,albeit they underestimated several severe dry periods and overestimated a few wet ***,the multi-model forecasts generated via multivariate regression of the forecasts of the three models yielded better results compared with those of individual *** general,the ECMWF and UKMO models were found to be appropriate for one-month-ahead precipitation forecasting in most clusters of *** the clusters considered in Iran and for the long-range system versions considered,the Météo France model had lower skill than the other models.

关键词： ensemble forecasts Copernicus Climate Change Service long-term forecasting model evaluation Iran

Synthesis and spectral properties of Nd-doped glass-ceramics in SiO_2-CaO-MgO system prepared by sol-gel method

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Journal of Rare Earths 2013年第6期31卷 595-599页

作者： masoud Eslami Zohreh Hamnabard Ali Nemati Materials Science & Engineering Department Sharif University of Technology Materials Research School Ceramic Group

SiO2-CaO-MgO glass and glass-ceramic powder doped with Nd3＋ were synthesized with sol-gel method. Tetraethylorthosilicate （TEOS）, Ca（NO3）2？4H2O, Mg（NO3）2？6H2O, Nd（NO3）3？6H2O, ethanol, distilled water, and HNO3 were used as starting materials. The synthesized powder’s properties were examined with simultaneous thermal analysis （STA）, X-ray diffraction （XRD）, photoluminescence （PL） and scanning electron microscopy （SEM） analysis. The STA curves showed that the softening point and crystallization temperatures were shifted to higher temperatures with increasing dopant content. Regarding XRD patterns of glass samples, Nd was found to act as an intermediate oxide in glass matrix. The XRD patterns of glass-ceramic samples indicated that bredigite and akermanite crystallized in the glass matrix after heat treating at 900 oC. The fluorescence spectra showed that glass-ceramics emitted much stronger irradiation than glasses with the same dopant content. The SEM images illustrated uniform and homogeneous distribution of applied oxides in glass and glass-ceramic compositions.

关键词： glass glass-ceramic synthesis sol-gel method spectral properties rare earths

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

Impact of pertinent parameters on foam behavior in the entrance region of porous media:mathematical modeling

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Petroleum Science 2020年第6期17卷 1669-1682页

作者： Fereshteh Samimi Zahra Sakhaei masoud Riazi Department of Chemical Engineering School of Chemical and Petroleum EngineeringShiraz UniversityShirazIran Enhanced Oil Recovery(EOR)Research Centre IOR/EOR Research InstituteShiraz UniversityShirazIran Petroleum Engineering Department School of Chemical and Petroleum EngineeringShiraz UniversityShirazIran

Foam injection is a promising solution for control of mobility in oil and gas field exploration and development,including enhanced oil recovery,matrix-acidization treatments,contaminated-aquifer remediation and gas leakage *** study presents a numerical investigation of foam behavior in a porous *** flow method is applied to describe steady-state foam displacement in the entrance *** this model,foam flow for the cases of excluding and including capillary pressure and for two types of gas,nitrogen(N2)and carbon dioxide(CO2)are *** of pertinent parameters are also *** indicate that the foam texture strongly governs foam flow in porous *** entrance region may be quite different for foam texture to accede local equilibrium,depending on the case and physical properties that are *** to the fact that the aim of foaming of injected gas is to reduce gas mobility,results show that CO2 is a more proper injecting gas than *** are also some ideas presented here on improvement in foam displacement *** study will provide an insight into future laboratory research and development of full-field foam flow in a porous medium.

关键词： Foam displacement Entrance region Fractional flow method Foam texture Water saturation Mathematical modeling

Vibration analysis of steel structures including the effect of panel zone flexibility based on the energy method

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Earthquake Engineering and Engineering Vibration 2013年第4期12卷 587-598页

作者： Hasan Ghasemzadeh Hamid Rahmani Samani masoud Mirtaheri Department of Civil Engineering K.N.Toosi University of Technology Department of Civil Engineering Islamic Azad University–Pardis Branch

New approximate formulas are proposed to determine the natural frequencies of structures considering the effects of panel zone flexibility and soil-structure interaction. Several structures with various earthquake resisting systems are idealized as prismatic cantilever flexural-shear beams. Floor masses are considered as lumped masses at each story level and masses of columns are evenly distributed along the cantilever beam. Soil-structure interaction is considered as axial and rotational springs, whose potential energy are formulated and incorporated into overall potential energy of the structure. Subsequently, natural frequency equations are derived on the basis of energy conservation principle. The effect of axial forces on natural frequency is also considered in the proposed formulas. Using the method presented in this study, natural frequencies are computed using a simplified method with no complex numerical modeling. The proposed formulas are verified via experimental and numerical methods. Close agreement between the results from these three approaches are observed. Furthermore, the effects of panel zone flexibility, continuity plates and doubler plates on the natural frequencies of buildings are investigated.

关键词： free vibration energy method panel zone soil-structure interaction flexural-shear beams

Application of Modified Couple Stress Theory and Homotopy Perturbation Method in Investigation of Electromechanical Behaviors of Carbon Nanotubes

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Advances in Applied Mathematics and Mechanics 2017年第1期9卷 23-42页

作者： Mir masoud Seyyed Fakhrabadi School ofMechanical Engineering College of EngineeringUniversity of TehranTehranIran

The paper presents the size-dependant behaviors of the carbon nanotubes under electrostatic actuation using the modified couple stress theory and homotopy perturbation *** to the less accuracy of the classical elasticity theorems,the modified couple stress theory is applied in order to capture the size-dependant properties of the carbon *** of the static and dynamic behaviors under static DC and step DC voltages are *** effects of various dimensions and boundary conditions on the deflection and pull-in voltages of the carbon nanotubes are to be investigated in detail via application of the homotopy perturbation method to solve the nonlinear governing equations semi-analytically.

关键词： Carbon nanotubes modified couple stress theory homotopy perturbation method electrostatic actuation

Effect of fin attachment on thermal stress reduction of exhaust manifold of an off road diesel engine

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Journal of Central South University 2017年第3期24卷 546-559页

作者： Ali Akbar Partoaa Morteza Abdolzadeh masoud Rezaeizadeh Department of Mechanical Engineering Graduate University of Advanced Technology Kerman Iran

The effect of fin attachment on the thermal stress reduction of exhaust manifold of an off road diesel engine(Komatsu HD325-6) was *** doing this,coupled thermo-fluid-solid analysis of exhaust manifold of the off road diesel engine was carried *** thermal analysis,including thermal flow,thermal stress,and the thermal deformation of the manifold was *** flow inside the manifold was simulated and then its properties including velocity,pressure,and temperature were *** flow properties were transferred to the solid model and then the thermal stresses and the thermal deformations of the manifold under different operating conditions were ***,based on the predicted thermal stresses and thermal deformations of the manifold body shell,two fin types as well as body shell thickness increase were applied in the critical induced thermal stress area of the manifold to reduce the thermal stress and thermal *** results of the above modifications show that the combined modifications,*** thickness increase and the fin attachment,decrease the thermal stresses by up to 28% and the contribution of the fin attachment in this reduction is much higher compared to the shell thickness increase.

关键词： manifold exhaust simulation modification thermal stress deformation diesel engine

Prioritizing woody species for the rehabilitation of arid lands in western Iran based on soil properties and carbon sequestration

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Journal of Arid Land 2020年第4期12卷 640-652页

作者： masoud BAZGIR Reza OMIDIPOUR Mehdi HEYDARI Nasim ZAINALI masoud HAMIDI Daniel C DEY Department of Water and Soil Engineering Faculty of AgricultureIlam UniversityIlam ***Iran Department of Range and Watershed Management Faculty of Natural Resource and Earth ScienceShahrekord UniversityShahrekord ***Iran Department of Forestry Faculty of AgricultureIlam UniversityIlam ***Iran US Forest Service Northern Research StationColumbiaOM 65211USA

Plants are an important component in many natural ecosystems. They influence soil properties, especially in arid ecosystems. The selection of plant species based on their adaptations to site conditions is essential for rehabilitation of degraded sites and other construction sites such as check-dams. Other factors to be considered in species selection include their effects on soil properties and their abilities to meet other management objectives. The purpose of this study was to assess the effects of native(Populus euphratica Oliv. and Tamarix ramosissima Ledeb.) and introduced(Eucalyptus camaldulensis Dehnh. and Prosopis juliflora(Swartz) DC.) woody species on soil properties and carbon sequestration(CS) in an arid region of Iran. Soil sampling was collected at three soil depths(0–10, 10–20 and 20–30 cm) at the sites located under each woody species canopy and in an open area in 2017. Soil physical-chemical property was analyzed in the laboratory. The presence of a woody species changed soil characteristics and soil CS, compared with the open area. For example, the presence of a woody species caused a decrease in soil bulk density, of which the lowest value was observed under E. camaldulensis(1.38 g/cm^3) compared with the open area(1.59 g/cm^3). Also, all woody species significantly increased the contents of soil organic matter and total nitrogen, and introduced species had more significant effect than native species. The results showed that CS significantly increased under the canopy of all woody species in a decreasing order of P. euphratica(9.08 t/hm^2)>E. camaldulensis(8.37 t/hm^2)>P. juliflora(5.20 t/hm^2)>T. ramosissima(2.93 t/hm^2)>open area(1.33 t/hm^2), thus demonstrating the positive effect of a woody species on CS. Although the plantation of non-native species had some positive effects on soil properties, we recommend increasing species diversity in plantations of native and introduced woody species to provide more diversity for the increased ecosystem

关键词： arid ecosystem carbon sequestration degraded soil restoration reforestation soil management