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CFD simulation and optimization of an industrial cement gas-solid air classifier

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Particuology 2024年第6期89卷 172-184页

作者： Mohamadreza Esmaeilpour Ali Mohebbi vahab Ghalandari Department of Chemical Engineering Faculty of EngineeringShahid Bahonar University of KermanKermanIran Kerman Momtazan Cement Company KermanIran

An air classifier is one of the main and effective devices in cement *** this study,a three-dimensional,steady and two-phase(solid-gas)computational fluid dynamics(CFD)simulation was performed to optimize the performance of this device in the Kerman Momtazan cement plant,*** the validation of CFD results,the air flow field and air path lines between fixed blades were checked carefully and the non-uniformity in velocity distribution and the formation of vortex flows between the blades close to particle inlets were *** study tried to improve the device efficiency by changing the method of entering particles into the device,resulting in a reduction in air classifier electrical energy consumption(from 41 to 35(kW h)/t)and an increase in production rate(from 203 to 214 t/h).Additionally,the study investigated the effects of other modifiable operating conditions like rotary cage rotation speed,pressure difference,and inlet air temperature on the particle size distribution and classifier *** results showed that increasing the cage rotation speed decreased the product rate and the product particles mean diameter while increasing pressure difference or increasing temperature increased the product rate and the product particles mean *** was concluded that these modifiable operating conditions can significantly affect the performance of the air classifier in the cement industry.

关键词： Cement air classifier Computational fluid dynamics Gas-solid two-phase flow Optimization Eulerian-Lagrangian method Efficiency

Study on failure mechanism of room and pillar with different shapes and configurations under uniaxial test and numerical simulation compression using experimental test and numerical simulation

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Underground Space 2023年第2期9卷 105-121页

作者： vahab Sarfarazi Nima Babanouri Shahin Fattahi Kaveh Asgari Department of Mining Engineering Hamedan University of TechnologyHamedanIran Department of Mining Engineering Shahid Bahonar University of KermanKermanIran

Experimental and discrete element methods were used to investigate the failure behavior of room and pillar with different configura-tions under uniaxial *** samples with dimension of 15 cm×15 cm×5 cm were *** the specimens,rooms and pillars with different configurations were *** room dimension was 1 cm×1 cm,and the pillar dimension was according to the room *** different configurations were chosen for rooms and *** axial load was applied to the model by rate of 0.05 mm/*** results show that the failure process was mostly governed by both the non-persistent joint angle and joint *** compressive strength of the specimens was related to the fracture pattern and failure mechanism of the *** was shown that the shear behaviour of pillars was related to the number of the induced tensile cracks,which increased by increasing the room *** compressive strength of samples increased with the increase of the room *** failure pattern and failure strength are similar in both methods,i.e.,the experimental testing and the numerical simulation.

关键词： PFC2D Physical test Rock pillar

Numerical solution of particle size distribution equation:Rapid expansion of supercritical solution(RESS)process

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Particuology 2021年第4期19卷 201-213页

作者： Hamidreza Bagheri Hassan Hashemipour vahab Ghalandari Sattar Ghader Department of Chemical Engineering Faculty of EngineeringShahid Bahonar University of KermanKermanIran Department of Chemical Engineering Faculty of EngineeringVali-E-Asr University of RafsanjanRafsanjanIran Momtazan Cement Company KermanIran

The present study aimed to numerically simulate the rapid expansion of the supercritical solution(RESS)process including particle generation,hydrodynamics,and solving the population balance equation(PBE)to predict the particle-size distribution(PSD)of solid-supercritical carbon dioxide binary ***,momentum,and mass equations,in addition to the extended generalized Bender equation of state(EoS),were applied to predict the hydrodynamic behavior of a supercritical solution under several operating conditions using a nozzle and expansion *** tetraphenylporphyrin(TBTPP)solubility in supercritical carbon dioxide was calculated using the Peng-Robinson EoS/Kwak-Mansoori as a mixing ***,TBTPP,aspirin,ibuprofen,and salicylic acid nucleation as well as the supersaturation rate were ***,we solved the time dependence of the parameters of the size distribution *** established models are compared over a wide parameter range using a reference model that refers to the method of moment log-normal size distribution functions through the RESS process to predict a solid *** results obtained are presented with and without coagulation *** average absolute percent deviation of solubility of TBTPP was 3.98,and the hydrodynamic behavior of supercritical carbon dioxide showed a similar trend as the results presented in the published research ***,a particle size distribution prediction using coagulation showed acceptable agreement with the experimental PSDs.

关键词： Coagulation Growth Method of moment Particle size distribution Supercritical solution

Evaluation of plow system performance in long-wall mining method using particle flow code

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International Journal of Coal Science & Technology 2019年第4期6卷 518-535页

作者： Mohammadreza Ajamzadeh vahab Sarfarazi Hesam Dehghani Hamedan University of Technology HamedanIran

The underground or open-pit methods are used for the extraction of mineral resources,each of which is divided into different *** is one of the mineral resources,which is exploited either by the surface or the underground *** long-wall mining is one of the methods for the underground coal *** this method,which is a mechanized one,some machines such as the shearer or plow are used for the *** coal mine in Parvadeh,Tabas is a mechanized mine that is extracted by the long-wall *** modeling with particle flow code software was used in this mine for the evaluation of plow performance using the coal *** this regard,the sample was first calibrated by sampling from the Parvadeh coal mine and performing the uniaxial and Brazilian tests on the ***,the modeling was done by constructing the model and using the variables such as the clearance angle and the linear velocity of the *** making 28 models for the plow,the best model of the plow was selected based on the maximum force applied to the machine in the X ***,the results of this study showed that the best plow performance is for a model with the clearance angle of zero and the linear velocity of 9 mm/min,and the maximum force applied to this model is equal to 39,000 kN in the X direction.

关键词： Plow Long-wall mining Particle flow code Numerical modeling

Effects of weathering depth and thickness on rock failure:Experimental approach and particle flow code simulation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第11期16卷 4638-4653页

作者： vahab Sarfarazi Mehdi Torabi-Kaveh Arsham Moayedi Far Mining Engineering Department Hamedan University of TechnologyHamedan57965155Iran Department of Geology Yazd UniversityYazd***Iran Montanuniversitat Leoben Franz Josef Straße 18Leoben8700Austria

This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical *** first configuration involved conducting artificial weathering on limestone using the freezing and thawing(F-T)for 40 *** mechanical parameters of the samples were measured at the end of the 40th *** the second configuration,a series of specimens underwent salt crystallization(S-C)tests for 20 *** results were validated using discrete element method(DEM).Next,the weathered limestone model with dimensions of 108 mm54 mm were *** weathering layers were tested at four different thicknesses(i.e.2.5 mm,5 mm,7.5 mm,and 10 mm)and three different positions(at the surface,5 mm under the rock surface,and 10 mm under the rock surface).According to the results,weathering depth and thickness have a considerable effect on the failure *** results also showed a correlation between the values of compressive strength and failure mechanisms associated with the weathering *** numerical results revealed that the tension crack was the dominant ***,with increasing weathering thickness,Young's modulus,crack initiation stress,and final strength decreased in constant weathering *** results also demonstrated that the failure progress of the numerical models was similar to that observed in the laboratory.

关键词： Limestone Weathering depth Weathering thickness Failure pattern Particle flow code in two dimensions(PFC2D)

Experimental and Numerical Study of Shear Fracture in Brittle Materials with Interference of Initial Double Cracks

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Acta Mechanica Solida Sinica 2016年第5期29卷 555-566页

作者： Hadi Haeri vahab Sarfarazi Mohammad Fatehi Marji Ahmadreza Hedayat Zheming Zhu Young Researchers and Elite Club Bafgh BranchIslamic Azad UniversityBafghIran Department of Mining Engineering Hamedan University of TechnologytiamedanIran Associate Prof. Head of Mine Exploitation Engineering DepartmentFaculty of Mining and MetallurgyInstitution of EngineeringYazd UniversityYazdIvan Department of Civil and Environmental Engineering Colorado School of MinesGoldenColorado 80401USA College of Architecture and Environment Sichuan UniversityChengdu 610065China

A simultaneous experimental and numerical study of shear fracture of concrete-like materials is carried out using Brazilian disc specimens with initial double edge cracks and fourpoint bending beam specimens with double *** interference effects of two cracks/notches are investigated through varied ligament angles and crack *** is shown that shear fracturing paths change remarkably with the initial ligament angles and crack *** cracked specimens are numerically simulated by an indirect boundary element method.A comparison between the numerical results and the experimental ones shows good agreement.

关键词： cracked Fracture overlapped fracturing ligament simultaneous discontinuity cracking specimen shrinkage

Expression of connexin 30 and connexin 32 in hippocampus of rat during epileptogenesis in a kindling model of epilepsy

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Neuroscience Bulletin 2012年第6期28卷 729-736页

作者： Bijan Akbarpour Mohammad Sayyah vahab Babapour Reza Mahdian Siamak Beheshti Ahmad Reza Kamyab Departments of Physiology and Pharmacology Pasteur Institute of Iran.Tehran 131694-3551Islamic Republic of Iran Department of Physiology Faculty of Veterinary MedicineIslamic Azad UniversityScience and Research BranchTehran 14778-93855Islamic Republic of Iran Departments of Physiology and Pharmacology Pasteur Institute of IranTehran 131694-3551Islamic Republic of Iran Department of Physiology Faculty of Veterinary MedicineTehran UniversityTehran 141996-31111Islamic-Republic of Iran Department of Molecular Medicine Biotechnology Research CenterPasteur Institute of Iran Department of Biology Faculty of Science University of IsfahanIsfahan 81746-73441Islamic Republic of Iran

Objective Understanding the molecular and cellular mechanisms underlying epileptogenesis yields new in- sights into potential therapies that may ultimately prevent epilepsy. Gap junctions （GJs） create direct intercellular conduits between adjacent cells and are formed by hexameric protein subunits called connexins （Cxs）. Changes in the expression of Cxs affect GJ communication and thereby could modulate the dissemination of electrical discharges. The hippocampus is one of the main regions involved in epileptogenesis and has a wide network of GJs between different cell types where Cx30 is expressed in astrocytes and Cx32 exists in neurons and oligodendrocytes. In the present study, we evaluated the changes of Cx30 and Cx32 expression in rat hippocampus during kindling epileptogenesis. Methods Rats were stereotaxically implanted with stimulating and recording electrodes in the basolateral amygdala, which was electrically stimulated once daily at afterdischarge threshold. Expression of Cx30 and Cx32, at both the mRNA and protein levels, was measured in the hippocampus at the beginning, in the middle （after acquisition of focal seizures）, and at the end （after establishment of generalized seizures） of the kindling process, by real-time PCR and Western blot. Results Cx30 mRNA expression was upregulated at the beginning of kindling and after acquisition of focal seizures. Then it was downregulated when the animals acquired generalized seizures. Overexpression of Cx30 mRNA at the start of kindling was consistent with the respective initial protein increase. Thereafter, no change was found in protein abundance during kindling. Regarding Cx32, mRNA expression decreased after acquisition of generalized seizures and no other significant change was detected in mRNA and protein abundance during kindling. Conclusion We speculate that Cx32 GJ communication in the hip- pocampus does not contribute to kindling epileptogenesis. The Cx30 astrocytic network localized to perivascular re

关键词： connexin 30 connexin 32 hippocampus kindling

Feasibility of micro-organisms in soil bioremediation and dust control

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Biogeotechnics

Biogeotechnics 2024年第3期2卷 50-55页

作者： Erfan Ahmadzadeh Sima Samadianfard Yang Xiao vahab Toufigh Department of Civil Engineering The Sharif University of TechnologyTehranIran School of Civil Engineering Chongqing UniversityChongqing 400045China

Detrimental impacts of dust caused by mine tailings have yielded to several studies on the efficiency of different soil *** stabilization has been recognized as a reality within recent decades,where bacteria could get adhesion to the grains and stabilize the soil ***,these bacteria are prone to be destroyed while exposed to the normal environmental *** this study,the effects of microcapsules containing two types of bacterial freeze-dried spores(*** Natto LMG 19457 and ***)have been investigated on the mine tailing stability in terms of two *** first part of the study is dedicated to the fabrication of microcapsules within the two bacteria and identification of the characteristics of these microcapsules to set the time of microcapsules break and release in the *** urea-formaldehyde microcapsules containing tung oil were synthesized using microencapsulation method and at the following,the bacterial spores of *** Natto LMG 19457 and *** which had the high durability and the capability to grow in the silicon oil,were added to the *** microcapsules effect on MT specimens and the viability of encapsulated spores were *** characteristics of the capsules were analyzed by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR)and thermo-gravimetric thermal analysis(TGA).In the second part,wind tunnel tests were conducted to study the effects of microorganism stabilizers on mine *** results indicated that the dust erosion reduced from 16%-using water as a stabilizer-to the 0.2%while using microcapsules containing *** Natto LMG 19457 and 0.8%while using microcapsules containing *** results showed the high efficiency of microcapsules containing bacteria in stabilizing the *** phenomenon was proved by SEM imaging in which the voids were bounded significantly while using the bacteria.

关键词： Urea formaldehyde microencapsulation Dust control Stabilization of soil Mine tailings(MTs) Wind tunnel experiment

Protective effect of Amorphophallus campanulatus(Roxb.) *** against thioacetamide induced oxidative stress in rats

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Asian Pacific Journal of Tropical Medicine 2011年第11期4卷 870-877页

作者： Puthuparampil Nazarudeen Ansil Anand Nitha Santhibhavan Prabhakaran Prabha Pallara Janardhanan Wills vahab Jazaira Mukalel Sankunni Latha Biochemistry and Pharmacognosy Research Laboratory School of BiosciencesM.G.UniversityP.O.Hills.P.O.KottayamKerala-686560India

Objective:To identify the phytochemical constituents of Amorphopkallus campanulatus(A. campanulatus) tuber and to evaluate its antioxidant potential through in vitro and in vivo models. Methods:Phytochemical screening and in vitro antioxidant activities of *** tuber n-hexane extract(ACHE) and methanolic extract(ACME) were evaluated using DPPH,hydroxyl radical,reducing power and total antioxidant capacity *** total phenolic and flavonoid contents were also *** protective potential of two different doses of ACME(125 and 250 mg/kg) was also evaluated against thioaeetamide(TAA) induced oxidative stress in rats. Silymarin used as a standard drug *** was assessed by quantifying the serum levels of aspartate aminotransferase(AST),alanine aminotransferase(AIT),alkaline phosphatase (ALP) and lactate dehydrogenase(LDH).The antioxidant potential of ACME were also evaluated by the estimation of catalase(CAT),glutathione peroxidase(GPx),glutathione reductase (OR),glutathione-S-transferase(GST),reduced glutathione(GSH) and lipid peroxidation (Thiobarbituric acid reactive substances) in hepatic and renal *** changes of liver were also ***:In vitro studies revealed that ACME has higher antioxidant and radical scavenging activity than ACHE,which may be attributed to its higher phenolic and flavonoid *** significandy prevented the elevation of serum AST,***,LDH,and tissue malondialdehyde levels(P < 0.05).Hepatic and renal ***,GPx,and catalase levels were remarkably increased by the treatment with the *** of histopathological changes also supported the dose dependent protective effects of ***:The results do suggest that *** tuber could be considered as a potential source of natural antioxidant.

关键词： Amorphophallus campanulatus Thioacetamide DPPH Hepatotoxicity Hepatoprotective Antioxidant aclivily Silymarin