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Particle size distribution in a multi-zone circulating fluidized bed polymerization reactor

Particuology 2024年第10期93卷 291-299页

作者： Mohammadhossein Hadadiyan Navid Mostoufi reza marandi Process Design and Simulation Research Centre School of Chemical EngineeringCollege of EngineeringUniversity of TehranP.O.Box 11155-4563TehranIran Polymer Research Group Petrochemical Research and Technology CompanyNational Petrochemical CompanyP.O.Box 14358/84711TehranIran

This research focuses on modeling a multi-zone circulating reactor(MZCR)in the polypropylene production *** these reactors,designed for polyolefin production,small catalyst particles(20–300μm)initiate polymerization in the presence of monomer *** reactor consists of two main regions:the riser and the *** riser operates in the fast fluidization and the downer is in the moving bed *** the two-fluid model with the Eulerian-Eulerian approach,the dynamics of both solid and gas phases were modeled by applying Newton's laws of motion and assuming spherical *** population balance of particles within the reactor was also coupled with the equations of *** simultaneous solution of these equations provides valuable insights into particle and fluid behavior,revealing trends such as the growth of polymer ***,the impact of various operating conditions was *** study also examined the effects of design parameters(gas inlet velocity,average inlet diameter,and temperature)on the system *** instance,it was shown that in the case where the solid circulation flux is 30 kg/(m^(2) s)the velocity of particles in the bed increases from 0.4 at the inlet to 1.1 m/s in the fully developed zone,when it is 43 kg/(m^(2) s)the velocity of particles increases from 0.3 to 1.4 m/s,and when it is 55 kg/(m^(2) s),it is increased from 0.22 to 1.5 m/***,trends in particle size distribution based on temperature adjustments were *** study showed that higher temperatures accelerate the polymerization reaction rate,promoting faster growth kinetics and the formation of larger particles.

关键词： Fluidization Polymerization Gas-solid flow Multi-zone circulating reactor(MZCR) CFD-PBM Two-fluidmodel

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Syntheses, Crystal Structures, and Properties of a New Lead(Ⅱ) Complex Involving Holo-and Hemidirected Coordination Spheres with 3,5,6-Tris(2-pyridyl)-1,2,4-triazine Ligand

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Chinese Journal of Structural Chemistry 2014年第8期33卷 1184-1190页

作者： Farzin marandi Department of Chemistry Payame Noor University

[Pb（TPT）（μ-I）2PbI2（μ-I）2Pb（TPT）] 1 （TPT is the abbreviation of 3,5,6-tris（2- pyridyl）-1,2,4-triazine ligand） has been synthesized and characterized by elemental analysis, IR, J H- NMR spectroscopy and studied by thermal and electrochemical properties as well as X-ray crystallography. The single-crystal X-ray data show two different kinds of Pb2＋ ions in 1 with coordination numbers of six, Pbl = PbI6, and five, Pb2 = PbN312, with holodirected and hemidirected coordination spheres, respectively. The supramolecular features in 1 are negotiated through the weak but directional Pb...I, C-H...N and C-H...I interactions and aromatic π-π stacking interactions.

关键词： lead(Ⅱ) crystal structure holodirected hemidirected 1,2,4-triazine

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Performance improvement of a crumb rubber modified bitumen using recycled glass powder

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第11期14卷 805-814页

作者： Mojtaba GHASEMI Seyed Morteza marandi Department of Civil Engineering Shahid Bahonar UniversityKerman 761691 4111 Iran

In this study, the efficiency of bitumen and asphalt mixtures modified with crumb rubber(CR) and recycled glass powder(RGP) is evaluated. From an environmental point of view, the application of RGP in asphalt mixtures is considered beneficial since it prevents accumulation of waste glass in the natural environment. Rheological and mechanical properties of modified bitumen samples were investigated by laboratory methods such as bitumen conventional tests and dynamic shear rheometer(DSR), and also by asphalt mixture performance tests including Marshall stability, indirect tensile strength(ITS),compressive strength, and indirect tensile stiffness modulus. The results showed that the application of RGP in place of CR has no negative impact on the efficiency of bitumen and asphalt mixtures and even improves their engineering properties except for the toughness index(TI). Moreover, a modification with 5% CR and 5% RGP in asphalt mixtures results in the best overall performance.

关键词： Crumb rubber (CR) Recycled glass powder (PGP) Rheological properties Performance testing Stone matrixasohalt (SMA)

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Polyacrylamide hydrogel application in sand control with compressive strength testing

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Petroleum Science 2019年第1期16卷 94-104页

作者： Mahsa Baghban Salehi Asefe Mousavi Moghadam Samira Zargari marandi Department of Petroleum Engineering Chemistry and Chemical Engineering Research Center of Iran Faculty of Chemical Engineering Tarbiat Modares University

Sand production is one of the major problems in sandstone reservoirs. Different mechanical and chemical methods have been proposed to control sand production. In this paper, we propose a chemical method based on using polyacrylamide/chromium triacetate hydrogel to investigate sand production in a synthetic sandpack system. To this end, a series of bulk experiments including the bottle test and rheological analysis along with compression tests were conducted. Experimental results indicated that the compressive strength of the sandpack was increased as much as 30 times by injecting 0.5 pore volume of hydrogel. Also, it was found that the increases in cross-linker and polymer concentrations exhibited a positive impact on the compressive strength of the sandpack, mostly by cross-linker concentration(48 psi). Hydrogel with a higher value of cross-linker could retain its viscoelastic properties against the strain which was a maximum of 122% for 0.5 weight ratio of cross-linker/polymer. The presence of salts, in particular divalent cations, has a detrimental effect on the hydrogel stability. The maximum strain value applied on hydrogel in the presence of CaCl_2 was only about 201% as compared to 1010% in the presence of distilled water. Finally, thermogravimetric analysis and its derivative showed that the hydrogel could retain its structure up to 300 °C. The results of this study revealed the potential application of the hydrogel to control sand production.

关键词： Sand control - Rheology Hydrogel strength Compressive strength Sandpack

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Synthesis,Spectra,X-ray Diffraction and Thermal Studies of New Zn(Ⅱ) Compounds Based on Dibenzoylmethane

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Chinese Journal of Structural Chemistry 2016年第10期35卷 1582-1592页

作者： FARZIN marandi NASTARAN Shahinpour QUAH CHING Kheng HOONG KUN Fun Department of Chemistry Payame Noor University X-ray Crystallography Unit School of PhysicsUniversity Sains Malaysia

Two new zinc（Ⅱ） compounds with dibenzoylmethane and N-donor ancillary ligands,[Zn（μ-pyz）（dbm）_2]_n（1） and [Zn（dbm）_2（μ-bpe）Zn（dbm）_2]（2）（Hdbm = dibenzoylmethane,pyz = pyrazine and bpe = 1,2-bis（4-pyridyl）ethane）,have been prepared and characterized using elemental analysis,IR,~1H NMR and 13 C NMR spectroscopy,and studied by thermal gravimetric analysis as well as single-crystal X-ray diffraction. The crystal and molecular structures of 1 and 2 have been solved by X-ray diffraction and they turned out to be a one-dimensional coordination polymer with linear dispositions of metal atoms and binuclear compound,respectively. These one-dimensional polymers are further connected to form a 3D supramolecular network by C–H···O（only in 2） and π-π interactions.

关键词： dibenzoylmethane 1 2-bis(4-pyridyl)ethane pyrazine zinc(Ⅱ)

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Effects of Direction of Bridging of Thiocyanato on the Dimension of Coordination Polymers: Synthesis, Characterization and Single-crystal X-ray Structure Determination of [Cd(4,4'-dm-2,2'-bpy)(NCS)_2]_n and [Cd(4,4'-dmo-2,2'-bpy)(NCS)_2]_n Coordination Pol

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Chinese Journal of Structural Chemistry 2015年第7期34卷 1135-1144页

作者： HOSSEIN Shirdel FARZIN marandi ABBAS Jalilzadeh SEBASTIAN Huber ARNO Pfitzner Department of Food Industry Maku Branch Islamic Azad University Department of Chemistry Payame Noor University Institut für Anorganische Chemie Universitaet Regensburg 93040Regensburg Germany

Two new cadmium（II）-thiocyanato coordination polymers with 4,4＇-dimethyl-2,2＇-bipyridine（4,4＇-dm-2,2＇-bpy） and 4,4＇-dimethoxy-2,2＇-bipyridine（4,4＇-dmo-2,2＇-bpy） as chelating ligands were synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopy and X-ray crystallography. Thermal properties were also studied as well. These complexes have formed as [Cd（4,4＇-dm-2,2＇-bpy）（NCS）2]n（1） and [Cd（4,4＇-dmo-2,2＇-bpy）（NCS）2]n（2）. The coordination numbers of CdII in 1 and 2 are six（Cd N4S2）. Direction of bridging of thiocyanato anions in 1 and 2 created one- and two-dimensional coordination polymers, respectively. The supramolecular features in these complexes were guided and controlled by weak directional intermolecular interactions.

关键词： 2 2’-bipyridine cadmium(II) coordination polymer weak interactions

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Comparison the effect of ephedrine and phenylephrine in treatment of hypotension after spinal anesthesia during cesarean section

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Open Journal of Obstetrics and Gynecology 2012年第3期2卷 192-196页

作者： Atashkhoyi Simin Fardiazar Zahra Hatami marandi Pouya Torab reza AnesthesiologyAnesthesiology Alzahra Hospital Tabriz University of Medical Sciences Tabriz Iran Obstetrics & Gynecology Alzahra Hospital Tabriz University of Medical Sciences Tabriz Iran Tabriz University of Medical Sciences Alzahra Hospital Tabriz University of Medical Sciences Tabriz Iran

Background and Objective: The effectiveness of ephedrine and/or phenylephrine, in treatment of hypotension secondary to spinal anesthesia for cesarean section and their effects on fetal/neonatal outcome were studied. Methods and Materials: Sixty healthy parturients were randomly assigned to two groups;group E (n = 33) received boluses 5 mg/ml increments ephedrine and group P (n = 27) received a boluses of phnylephrine 100 μg/ml increments for treatment of hypotension after spinal block during cesarean section. Changes in maternal blood pressure and heart rate, and incidence of nausea-vomiting, neonatal Apgar score at 1 and 5 minutes of delivery, and umbilical arterial blood gas values were recorded. Results: There were no differences in treatment of hypotension following sympathectomy after spinal block with two drugs. Neonatal outcome was similar in two groups. There were not significant differences in umbilical arterial values in two groups. Conclusion: Ephedrine and phenylephrine are both effective vasopressores for treatment of hypotension associated to spinal block during cesarean section without adverse effects on infants/neonates.

关键词： Cesarean Section Spinal Anesthesia Hypotension Ephedrine Phenylephrine Fetal/Neonatal Outcome

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High-efficiency CdTe/CdS core/shell nanocrystals in water enabled by photo-induced colloidal hetero-epitaxy of CdS shelling at room temperature

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Nano Research 2015年第7期8卷 2317-2328页

作者： Hakimeh Zare Maziar marandi Somayeh Fardindoost Vijay Kumar Sharma Aydan Yeltik Omid Akhavan Hilmi Volkan Demir Nima Taghavinia Institute for Nanoscience and Nanotechnology Shafif University of Technology Tehran 14588 Iran Department of Physics Faculty of Sciences Arak University Arak 38156-8-8349 Iran Department of Physics Department of Electrical and Electronics Engineering and UNAM-Institute of Materials Science and Nanotechnology Bilkent University Ankara Turkey Luminous Center of Excellence for Semiconductor Lighting and Displays Microelectronics Division School of Electrical and Electronics Engineering and Physics and Applied Physics Division School of Physical and Mathematical Sciences Nanyang Technological University Singapore 639798 Singapore Physics Department ShafifUniversity of Technology Tehran 14588 Iran

We report high-efficiency CdTe/CdS core/shell nanocrystals synthesized in water by epitaxially growing CdS shells on aqueous CdTe cores at room temperature, enabled by the controlled release of S species under low-intensity ultraviolet （UV） light illumination. The resulting photo-induced dissociation of S2O2- ions conveniently triggers the formation of critical two-dimensional CdS epitaxy on the CdTe surface at room temperature, as opposed to initiating the growth of individual CdS core-only nanocrystals. This controlled colloidal hetero-epitaxy leads to a substantial increase in the photoluminescence （PL） quantum yield （QY） of the shelled nanocrystals in water （reaching 64%）. With a systematic set of studies, the maximum PL QY is found to be almost independent of the illuminating UV intensity, while the shell formation kinetics required for reaching the maximum QY linearly depends on the illuminating UV intensity. A stability study of the QD films in air at various temperatures shows highly improved thermal stability of the shelled QDs （up to 120 ℃ in ambient air）. These results indicate that the proposed aqueous CdTe/CdS core/shell nanocrystals hold great promise for applications requiring efficiency and stability.

关键词： CdTe/CDs,core/shell nanocrystal thermal stability photochemical

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Aperture Field Estimation in Waveguide for Non-Sinusoidal Periodic Excitation

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Journal of Electromagnetic Analysis and Applications 2012年第3期4卷 129-134页

作者： Sushrut Das Kalidas marandi Department of Electronics Engineering Indian School of Mines Dhanbad India Department of Electronics Engineering Indian School of Mines Dhanbad India.

In this paper an attempt has been made to find the aperture field distribution in a rectangular waveguide for non-sinusoidal, periodic excitations using Multiple Cavity Modeling Technique. The excitation functions, considered, are square, trapezoidal and clipped sine wave in nature. In the present analysis these time domain excitation functions have been represented in terms of a truncated Fourier series consisting of the fundamental frequency and its higher harmonics. Within the waveguide the fundamental frequency will give rise to a dominant mode excitation whereas the higher order modes will excite dominant as higher order modes. If the higher harmonics are assumed suppressed then the waveguide is subjected only to a dominant mode excitation. Results for dominant mode reflection coefficient (magnitude), VSWR and complex transmission coefficient have been computed and compared with theoretical data. The excellent agreement between them validates the analysis.

关键词： Waveguides Aperture Distribution Non-Sinusoidal Periodic Excitation Moment Method

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Design of an Adaptive Neuro-Fuzzy Position Controller for a Pneumatic System

Design of an Adaptive Neuro-Fuzzy Position Controller for a ...

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2009中国控制与决策会议

作者： Mostafa marandi Sassan Azadi Department of Mechatronic Semnan UniversitySemnanIran

＜正＞Pneumatic actuators are recently used in many application for robotics and automation such as drilling, sawing,spraying,and *** utilization is due to high speed,low cost,and safety characteristics of these ***,the use of pneumatic systems in position control applications is somewhat restricted due to significant system nonlinearities,caused by air compressibility,friction effects and variations of process parameters with *** recent years,many researchers tried to solve these restrictions by applying adaptive control *** this work we used a hybrid structure of fuzzy control and neural networks for the control of a pneumatic *** the neural network used to adjust all of the output membership functions in the fuzzy logic controller and works as a neural adaption *** steepest descent learning procedure is implemented and the output from a conventional feedback controller is used as an error by neural network for tuning the parameters of the fuzzy ***,we compared our approach with the fuzzy adaption *** results obtained by simulation,show better performance of the proposed Adaptive Neuro-Fuzzy Control structure.

关键词： Adaptive Neuro-Fuzzy Controller Adaption Mechanism Pneumatic Actuator System Position Control

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