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Rainfall-induced wind erosion in soils stabilized with alkali-activated waste materials

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Journal of Rock Mechanics and Geotechnical Engineering 2025年第1期17卷 465-480页

作者： Alireza Komaei Abbas Soroush seyed mohammad Fattahi Hesam Ghanbari Department of Civil and Environmental Engineering Amirkabir University of TechnologyTehran159163431Iran

This study evaluates the efficacy of sustainable erosion control using slag-based alkali-activated cement crusts under varying rainfall and wind conditions. The rainfall intensities ranged from 30 mm/h to 120 mm/h, with durations ranging from 15 min to 90 min, and crust slopes of ∼2° (gentle) and 30° (steep). Wind tunnel experiments were conducted at wind velocities of 14 m/s, 21 m/s, and 28 m/s to investigate post-rainfall wind erodibility, along with changes in crust strength and microstructure analysis. The findings show the development of hydrated cementitious phases in alkali-activated material, which form around and between the particles during the alkaline activation process. Alkali-activated cement crusts significantly reduced erosion caused by rainfall and subsequent wind by several orders of magnitude. At the highest rainfall intensity of 120 mm/h, rainfall erosion was measured to be 1654.81 kg/m2 for untreated samples and 0.89 kg/m2 for treated samples, demonstrating a substantial 99.95% reduction in erosion due to the treatment. Similarly, at the highest wind speed tested, wind erosion was 122.75 kg/m2 for untreated samples and 0.095 kg/m2 for treated samples, indicating a significant 99.92% reduction in erosion due to the formation of an alkali-activated cement crust on the soil surface. However, exposure of the samples to 120 mm/h rainfall for 90 min resulted in a 5.2-fold increase in wind erosion compared to pre-rainfall conditions. Similarly, penetrometer results indicated a 37%–54% reduction in post-rainfall surface strength.

关键词： Rainfall erosion Alkali-activated material Wind erosion Crust formation

A novel technology for control of variable speed pumped storage power plant

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Journal of Central South University 2016年第8期23卷 2008-2023页

作者： seyed mohammad Hassan Hosseini mohammad Reza Semsar Department of Electrical Engineering Islamic Azad University

Variable speed pumped storage machines are used extensively in wind power plant and pumped storage power plant. This paper presents direct torque and flux control(DTFC) of a variable speed pumped storage power plant(VSPSP). By this method both torque and flux have been applied to control the VSPSP. The comparison between VSPSP's control strategies is studied. At the first, a wind turbine with the capacity 2.2 k W and DTFC control strategies simulated then a 250 MW VSPSP is simulated with all of its parts(including electrical, mechanical, hydraulic and its control system) by MATLAB software. In all of simulations, both converters including two-level voltage source converter(2LVSC) and three-level voltage source converter(3LVSC) are applied. The results of applying 2LVSC and 3LVSC are the rapid dynamic responses with better efficiency, reducing the total harmonic distortion(THD) and ripple of rotor torque and flux.

关键词： direct torque and flux control(DTFC) two-level & three-level voltage source converter(2LVSC&3LVSC) variable speed pumped storage power plant(VSPSP)

A comparative study of physicochemical and photocatalytic properties of visible light responsive Fe,Gd and P single and tri-doped TiO_2 nanomaterials

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Journal of Rare Earths 2018年第1期36卷 72-85页

作者： seyed mohsen adyani mohammad ghorbani department of materials science and engineering sharif university of technologyPO．Box 11155-9466Tehran，lran institute for nanoscience and nanotechnology(inst) sharif university of technologyP0．Box 11155-8639，Tehran1ran

High performance Fe-Gd-P tri-doped TiO2 nanoparticles （1 at% for each dopant） were successfully synthesized by a modified sol-gel method. Various analytical and spectroscopic techniques were carried out to determine the physicochemical properties of the prepared samples, including XRD, EDX, FESEM, BET, FFIR, XPS, PL, EIS and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of prepared samples were evaluated by photo degradation of methyl orange （MO） and 4-chlorophenol （4- CP） as model pollutants under visible light irradiation. Effects of each dopant on different properties of TiO2 nanoparticles were investigated. Results show that Gd and P doping enhances Ti02 surface textural properties by forming Ti O Gd and Ti-O-P bonds. It is found that Gd plays a superior role in increasing oxygen vacancies and organic species on TiO2 surface. Gd doping also facilitates transferring of the photo-induced charge carriers to the surface adsorbed species. The enhanced electronic band structure and visible light response, as well as high electron lifetime of Fe-Gd-P tri-doped sample is mainly attributed to Fe and Gd doping. The tri-doped TiO2 with rate constant ofkapp - 1.28 ~ 10-2 min-1 for MO and kapp ~ 0.94 ~ 10-2 min-1 for 4-CP, shows the highest photodegradation rate among all samples including undoped and single doped samples. The improved photocatalytic performance of Fe-Gd-P tri- doped Ti02 is due to the synergistic effect of enhanced surface chemistry and textural properties, increased number of surface adsorbed hydroxyl groups and organic species, improved visible light ab- sorption, increased lifetime of the photo-induced electron/hole pairs and boosted interfacial charge transfer.

关键词： Fe-Gd-P tri-doped TiO2Sol-gel synthesisPhotodegradationVisible light responseSynergistic effectRare earths

Nonlinear finite time attitude control of flexible spacecraft based on a novel output redefinition method

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Chinese Journal of Aeronautics 2023年第11期36卷 373-385页

作者： seyed Majid ESMAEILZADEH mohammad Sadegh ZEYGHAMI Department of Electrical Engineering Iran University of Science and TechnologyNarmakTehran 16846-13114Iran

A finite time attitude controller is designed for a flexible spacecraft based on a novel output redefinition method, in this paper. To make the flexible appendages vibration suppression effective, the appendage tip-point is selected as the output. First, a novel output redefinition method is proposed to overcome the non-minimum phase property of the dynamic model. The proposed method not only makes the system model minimum phase but also improves the attitude control system performance. Consequently, the precise attitude pointing and stabilization are ***, a nonlinear finite time H∞controller is designed based on the backstepping approach. For the situation where the modal variables measurements are not available, a modal observer is also designed. The simulation results show the effectiveness of the proposed method in the presence of the model uncertainties and environmental disturbances.

关键词： Finite time Output redefinition H1 control Attitude control Flexible spacecraft Backstepping Robust

A novel hybrid algorithm based on a harmony search and artificial bee colony for solving a portfolio optimization problem using a mean-semi variance approach

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Journal of Central South University 2016年第1期23卷 181-188页

作者： seyed mohammad seyedhosseini mohammad Javad Esfahani Mehdi Ghaffari Department of Industrial Engineering Iran University of Science and Technology Young Researchers and Elite Club Naragh BranchIslamic Azad University Department of Industrial Engineering Naragh BranchIslamic Azad University

Portfolio selection is one of the major capital allocation and budgeting issues in financial management, and a variety of models have been presented for optimal selection. Semi-variance is usually considered as a risk factor in drawing up an efficient frontier and the optimal portfolio. Since semi-variance offers a better estimation of the actual risk portfolio, it was used as a measure to approximate the risk of investment in this work. The optimal portfolio selection is one of the non-deterministic polynomial(NP)-hard problems that have not been presented in an exact algorithm, which can solve this problem in a polynomial time. Meta-heuristic algorithms are usually used to solve such problems. A novel hybrid harmony search and artificial bee colony algorithm and its application were introduced in order to draw efficient frontier portfolios. Computational results show that this algorithm is more successful than the harmony search method and genetic algorithm. In addition, it is more accurate in finding optimal solutions at all levels of risk and return.

关键词： portfolio optimizations mean-variance model mean semi-variance model harmony search and artificial bee colony efficient frontier

Application of computational fluid dynamics in design of viscous dampers-CFD modeling and full-scale dynamic testing

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Earthquake Engineering and Engineering Vibration 2023年第4期22卷 1065-1080页

作者： Hassan Lak seyed Mehdi Zahrai seyed mohammad Mirhosseini Ehsanollah Zeighami Department of Civil Engineering Collage of EngineeringArak BranchIslamic Azad UniversityArak ***Iran School of Civil Engineering College of EngineeringUniversity of TehranTehran ***Iran

Computational fluid dynamics(CFD)provides a powerful tool for investigating complicated fluid *** paper aims to study the applicability of CFD in the preliminary design of linear and nonlinear fluid viscous *** fluid viscous dampers were designed based on CFD *** first device was a linear viscous damper with straight *** second was a nonlinear viscous damper containing a one-way pressure-responsive valve inside its *** dampers were detailed based on CFD simulations,and their internal fluid flows were ***-scale specimens of both dampers were manufactured and tested under dynamic *** to the tests results,both dampers demonstrate stable cyclic behaviors,and as expected,the nonlinear damper generally tends to dissipate more energy compared to its linear *** compatibility was achieved between the experimentally measured damper force-velocity curves and those estimated from CFD *** a thermography camera,a rise in temperature of the dampers was measured during the *** was found that output force of the manufactured devices was virtually independent of temperature even during long duration ***,temperature dependence can be ignored in CFD models,because a reliable temperature compensator mechanism was used(or intended to be used)by the damper manufacturer.

关键词： fluid viscous damper passive control dynamic testing energy dissipation device computational fluid dynamic thermography

New approach to solving master equations of density operator for the Jaynes Cummings model with cavity damping

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Chinese Physics B 2014年第9期23卷 65-70页

作者： seyed Mahmoud Ashrafi mohammad Reza Bazrafkan Physics Department Faculty of ScienceI.K.I.University

By introducing thermo-entangled state representation Ⅰη〉, which can map master equations of density operator in quantum statistics as state-vector evolution equations, and using ＂dissipative interaction picture＂ we solve the master equation of Jaynes-Cummings model with cavity damping. In addition we derive the Wigner function for density operator when the atom is initially in the up state Ⅰ↑〉 and the cavity mode is in coherent state.

关键词： Jaynes-Cummings model entangled state representation master equations

Characteristics of a multi-component MgO-based bioceramic coating synthesized in-situ by plasma electrolytic oxidation

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Journal of Magnesium and Alloys 2021年第5期9卷 1611-1625页

作者： Nasrinsadat Azarian seyed mohammad Mousavi Khoei Department of Mining and Metallurgical Engineering Amirkabir University of Technology(Tehran Polytechnic)P.O.Box 15875-4413TehranIran

Plasma electrolytic oxidation(PEO)has held great potential for the advancement of biodegradable implants,as it helps in developing porous bioceramic coatings on the surface of magnesium *** this research work,MgO-based bioceramic coatings containing the Si,P,Ca,Na,and F elements have been successfully fabricated on an AZ31 magnesium alloy plate utilizing the PEO *** characteristic current-voltage behavior of the samples during the process was surveyed in an electrolyte containing Ca(H_(2)PO_(4))_(2),Na_(2)SiO_(3)·9H_(2)O,Na_(3)PO_(4)·12H_(2)O,NaF,and KOH with a pH of 12.5 and electrical conductivity of 20 mS/cm^(-1).The results revealed that applying a voltage of 350-400 V(that is 50-100 V higher than the breakdown limit)could greatly facilitate the synthesis of a PEO ceramic coating with fewer defects and more uniform *** resulting coating was a compositionally graded bioceramic layer with a thickness in the range of 3.5±0.4 to 6.0±0.7µm,comprising the above-mentioned elements as promising bioactive *** synthesized ceramic features were investigated in terms of the elemental distribution of components through the thickness,which indicated a gradual rise in the Si and P contents and,conversely,a decline in the F content towards the outer *** growth mechanism of the PEO coating has been discussed accordingly.

关键词： Az31 magnesium alloy Plasma electrolytic oxidation Bioceramic Coating MgO-based ceramic

Computational analysis of neutronic effects of ThO_2 rods loaded in CANDU 6 fuel assemblies

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Nuclear Science and Techniques 2016年第4期27卷 14-20页

作者： seyed mohammad Mirvakili Zohreh Gholamzadeh seyed Amir Hossein Feghhi Reactor Research School Nuclear Science and Technology Research Institute Department of Radiation Application Shahid Beheshti UniversityG.C

Thorium as a suitable fertile with higher natural resources in comparison with uranium resources has been remarkably considered by different nuclear energy user countries in the last decades. Its prominent features such as suitable possibility for power flattening of a nuclear reactor, applicable breeder blanket to produce^(233)U fissile as well as neutron leakage prevention from a nuclear core has caused its application as power flatter, breeder material or other aimed utilizations be evaluated by the researches. In the present study, neutronics of a modeled CANDU 6loaded with Th O_2 and UO_2fuel rods have been computationally studied. The study aimed at reprocessing of burned Th O_2 seeds at CANDU 6 reactor to recover the total produced uranium, which is to be going under another compound fuel cycle. The obtained results showed all the core reactivity coefficients are sufficiently negative. The modeled core 949 GWd burn-up concluding in 99.99 %depletion of^(235)U initial loads. 18.38 kg of^(233) U was produced in the burnt Th O_2 fuel after 1-year burn-up time. In addition, 31.84 kg of^(239) Pu was produced in the UO_2 spent fuel rods after the burn-up time. After a proposed cooling time, about 50.01 kg of^(233)U will be available in the spent Th O_2 fuel.

关键词： CANDU堆中子泄漏燃料组件稳定杆计算核反应堆燃烧时间自然资源