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Chinese Journal of Chemical Engineering 2020年第11期28卷 2733-2745页

作者： amir Heidari Process Simulation and Modeling Laboratory(PSMlab) Faculty of ChemicalPetroleum and Gas EngineeringSemnan UniversitySemnan ***Iran

Mixing efficiency in two-phase gas–liquid agitated vessel is one of the important challenges in the industrial *** fluid dynamics technique(CFD)was used to investigate the effect of four different pitched blade impellers,including 15°,30°,45°and 60°,on the mixing quality of gas–liquid agitated *** multiphase flow behavior was modeled by Eulerian–Eulerian multiphase approach,and RNG k-εwas used to model the *** CFD results showed that a strong global vortex plays the main role on the mixing quality of the gas phase in the *** on the standard deviation criterion,it was observed that the axial distribution of the gas phase in the 30°impeller is about 55%better than the *** addition,the results showed that the 30°impeller has a uniform radial distribution over the other impellers and the maximum gas phase holdup in the *** of the power consumption of the impellers showed that the 30°impeller has the highest power consumption among the other pitched blade ***,examine the effect of same power condition for pitched blade impellers showed that the 30°impeller has the best mixing quality in this condition.

关键词： Pitched blade impeller Mixing CFD Multiphase flow RNG k-εmodel

Phase-plane analysis of test particle orbits in regular black holes

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Communications in Theoretical Physics 2020年第1期72卷 111-117页

作者： Muhammed amir Astrophysics and Cosmology Research Unit School of MathematicsStatistics and Computer ScienceUniversity of KwaZulu-NatalPrivate Bag X54001Durban 4000South Africa

We investigate phase-plane analysis of general relativistic orbits in a gravitational field of the Reissner–Nordstr?m-type regular black hole *** employ phase-plane analysis to obtain different phase-plane diagrams of the test particle orbits by varying charge q and dimensionless parameterβ,whereβcontains angular momentum of the test *** compute numerical values of radii for the innermost stable orbits and corresponding values of energy required to place the test particle in *** on,we employ similar analysis on an Ayón–Beato–García(ABG)regular black hole and a comparison regarding key results is also included.

关键词： black holes modified gravity phase-plane diagrams

Computer-aided design of classical linear compensators with application to aerospace

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Journal of Systems Engineering and Electronics 2009年第6期20卷 1373-1377页

作者： amir Nassirharand School of Mechanical Manufacturing & Materials Engineering Univ.of Nottingham-Malaysia Campus Semenyih 43500 Malaysia

A new Matlab function based on a versatile compensator design approach is *** function allows design of lead-lag, PID, proportional plus rate feedback, proportional-integral plus rate feedback, and nth order linear *** primary inputs to this function are the plant transfer function and the desired closedloop behavior in terms of an nth order transfer *** output is the particular compensator *** unified design approach is primarily based on minimizing a mean-squared error type objective *** minimization gives the compensator parameters in terms of a set of linear simultaneous algebraic *** solution method requires the user to input such parameters as the lower and upper limits of frequency range of interest;such parameters are automatically determined by the use of numerical *** design method and the associated software are demonstrated by solving a flexible satellite problem, and the results are compared with those obtained by two other methods reported in the open literatures.

关键词： linear systems classical control numerical analysis optimization.

Multi-range controller design for highly nonlinear systems with application to unmanned aerial vehicles

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Journal of Systems Engineering and Electronics 2010年第3期21卷 491-495页

作者： amir Nassirharand School of Mechanical Manufacturing & Materials EngineeringUniversity of Nottingham-Malaysia Campus

A new procedure for a design of multi-range controllers for use with highly nonlinear systems is *** procedure involves obtaining the describing function models of the nonlinear plant by software followed by designing a controller at nominal ***,the controller parameters are optimized to yield a satisfactory closed-loop response at all operating ***,the performance and stability of the closed-loop system comprised of the designed controller and the nonlinear plant are *** procedure and the associated software are applied to a nonlinear control problem of the sort encountered in aerospace,and the results are compared with two other approaches.

关键词： control theory optimization describing functions Fourier analysis stabilization.

General Energy Decay of Solutions for a Weakly Dissipative Kirchhoff Equation with Nonlinear Boundary Damping

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Acta Mathematicae Applicatae Sinica 2017年第2期33卷 401-408页

作者： amir Peyravi Department of Mathematics College of Sciences Shiraz University Shiraz 71467-13565 Iran

In this article, we study the weak dissipative Kirchhoff equation under nonlinear damping on the boundary We prove a general energy decay property for solutions in terms of coefficient of the frictional boundary damping. Our result extends and improves some results in the literature such as the work by Zhang and Miao （2010） in which only exponential energy decay is considered and the work by Zhang and Huang （2014） where the energy decay has been not considered.

关键词： Kirchhoff equation general decay boundary damping

Effect of synthesis solution pH of Co/γ-Al_2O_3 catalyst on its catalytic properties for methane conversion to syngas

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燃料化学学报 2018年第3期46卷 311-318页

作者： amir Mosayebi Reza Abedini Department of Chemical Engineering Tafresh University Faculty of Chemical Engineering Babol Noshirvani University of Technology

The cobalt nanoparticles over γ-Al_2O_3 support were prepared via chemical reduction of CoCl_2·6H_2O using NaBH_4 with various values of pH in the range of 11. 92-13. 80. Synthesized catalysts were studied through X-ray diffraction( XRD),N_2 adsorption/desorption( BET),H_2-temperature programmed reduction( H_2-TPR),H_2-chemisorption,O_2 pulse titration and temperature programmed oxidation( TPO) methods. Obtained results exhibited the synthesis solution pH showed a significant influence on the activity and selectivity in partial oxidation of methane reaction. The methane conversion,CO selectivity and H_2 yield were enhanced by increasing of the synthesis solution pH. Compared to other catalysts,the catalyst that synthesized at pH of 13.80,showed a superior ability in syngas production with a H_2/CO ratio of near 2 and also a proper stability against deactivation during the partial oxidation of methane.

关键词：部分氧化 Co/-Al 2 O 3 nanoparticles 选择 pH 价值

Combining Polarization-Division Multiplexing and Ferromagnetic Nonreciprocity to Achieve In-Band Ultra-High Isolation for Full-Duplex Wireless Systems

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Engineering 2024年第9期40卷 179-187页

作者： amir Afshani Ke Wu Poly-Grames Research Center Department of Electrical EngineeringÉcole Polytechnique de MontréalMontrealQC H3T 1J4Canada

The in-band full-duplex(IBFD)wireless system is a promising candidate for 6G and beyond,as it can double data throughput and enormously lower transmission latency by supporting simultaneous in-band transmission and reception of *** IBFD systems requires a substantial mitigation of a transmitter(Tx)’s strong self-interference(SI)signal into the receiver(Rx)***,current state-ofthe-art approaches to tackle this challenge are inefficient in terms of performance,cost,and complexity,hindering the commercialization of IBFD *** this work,we devise and demonstrate an innovative approach to realize IBFD systems that exhibit superior performance with a low-cost and lesscomplex architecture in an all-passive *** scheme is based on meticulously combining polarization-division multiplexing(PDM)with ferromagnetic nonreciprocity to achieve ultra-high isolation between Tx and Rx *** an unprecedented conception has become feasible thanks to a concurrent dual-mode circulator—a new component introduced for the first time—as a key feature of our module,and a dual-mode waveguide that transforms two orthogonally polarized waves into two orthogonal waveguide *** addition,we propose a unique passive tunable secondary SI cancellation(SIC)mechanism,which is embedded within the proposed module and boosts the isolation over a relatively broad *** report,solely in the analog domain,experimental isolation levels of 50,70,and 80 dB over 340,101,and 33 MHz bandwidth at the center frequency of interest,respectively,with excellent tuning ***,the module is tested in two real IBFD scenarios to assess its performance in connection with Tx-to-Rx leakage and modulation error in the presence of a Tx’s strong interference signal.

关键词： In-band full-duplex transceiver 6G Polarization-division multiplexing Dual-mode nonreciprocity

Studying the particle size ratio effect on granular mixing in a vertically vibrated bed of two particle types

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Particuology 2020年第6期18卷 100-111页

作者： amir Menbari Kamyar Hashemnia School of Mechanical Engineering Shiraz UniversityMolla Sadra St.ShirazIran

The uniform mixing of solids is important in many industries,such as the pharmaceutical,food,petrochemical and chemical *** numerically investigated the effect of particle size ratio on the mixing of bisized particles in a quasi-two-dimensional vibrationally fluidized *** granular bin ary mixtures comprised spherical particles with different size ***-dimensional discrete-element simulations agreed with previous experimental *** and diffusive mechanisms occurred Keywords:Discrete-element modeling Fluidization Granular media Mixing Particle size ratio Vibration within the vibrated *** particle size had no significant influence on convective mixing,whereas the diffusive mechanism strengthened for large size *** average particle velocity was larger in a mixture of large size *** stronger diffusive motion and larger average particle velocity caused the particles to mix faster for large size *** final mixing index decreased with size ratio because of the difference between the size and number of small and large particles.

关键词： Discrete-element modeling Fluidization Granular media Mixing Particle size ratio Vibration

Some Criteria for the Cohen-Macaulay Property and Local Cohomology

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Acta Mathematica Sinica,English Series 2009年第6期25卷 917-922页

作者： amir MAFI Department of Mathematics University of Kurdistan Institute for Studies in Theoretical Physics and Mathematics

Let a be an ideal of a commutative Noetherian ring R and M be a finitely generated R-module of dimension d. We characterize Cohen-Macaulay rings in term of a special homological dimension. Lastly, we prove that if R is a complete local ring, then the Matlis dual of top local cohomology module Ha^d（M） is a Cohen-Macaulay R-module provided that the R-module M satisfies some conditions.

关键词： Cohen-Macaulay Gorenstein flat module local cohomology module