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Cosmic acceleration with bulk viscosity in an anisotropic f(R, Lm) background

Communications in Theoretical Physics 2023年第7期75卷 103-112页

作者： raja Solanki Bina Patel Lakhan V Jaybhaye P K Sahoo Department of mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India Department of mathematical Sciences P.D.Patel Institute of Applied SciencesCharotar University of Science and Technology(CHARUSAT)ChangaAnand 388421GujaratIndia

In this article,we investigate the observed cosmic acceleration in the framework of a cosmological f(R,Lm)model dominated by bulk viscous matter in an anisotropic *** consider the locally rotationally symmetric Bianchi type I metric and derive the Friedmann equations that drive the gravitational interactions in f((R,Lm)***,we assume the functional form f(R,Lm)=R/2+Lαm,where a is a free model parameter,and then find the exact solutions of field equations corresponding to our viscous matter dominated *** incorporate the updated H(z)data and the Pantheon data to acquire the best-fit values of parameters of our model by utilizing theχ2 minimization technique along with the markov Chain monte Carlo random sampling ***,we present the behavior of physical parameters that describe the Universe’s evolution phase,such as density,effective pressure and EoS parameters,skewness parameter,and the statefinder diagnostic *** find that the energy density indicates expected positive behavior,whereas the negative behavior of bulk viscous pressure contributes to the Universe’s *** effective EoS parameter favors the accelerating phase of the Universe’s ***,the skewness parameter shows the anisotropic nature of spacetime during the entire evolution phase of the ***,from the statefinder diagnostic test,we found that our cosmological f(R,Lm)model lies in the quintessence region,and it behaves like a de-Sitter universe in the far *** analyze different energy conditions in order to test the consistency of the obtained *** find that all energy conditions except strong energy condition(SEC)show positive behavior,while the violation of SEC favors the recently observed acceleration with the transition from decelerated to an accelerated epoch of the Universe’s expansion in the recent past.

关键词： LRS Bianchi type I metric f(R Lm)gravity bulk viscosity skewness parameter equation of state parameter statefinder parameter

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Surface Characterisation of Silicon Based mEmS

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Chemical Research in Chinese Universities 2004年第4期20卷 407-410页

作者： LI J. CUI z m. A. Baker The Surface Analysis Laboratory School of Engineering University of SurreyRutherford Appleton LaboratoryThe Surface Analysis Laboratory School of Engineering University of Surrey Guildford GU2 7XH UKChilton Didcot UKGuildford GU2 7XH UK

Polysilicon microelectromechanical systems(mEmS) are the subject of intensive researches. Surface chemistry and topography of a mEmS test structure fabricated at Sandia National Laboratory, USA, were studied by means of scanning electron microscopy(SEm), X-ray photoelectron spectroscopy(XPS) and atomic force microscopy(AFm). XPS C_ 1sand Si_ 2pspectra from the polysilicon components, silicon nitride substrate and a reference silicon wafer were compared. The results confirm the presence of a self-assembled monolayer(SAm) on the mEmS surface. An island-like morphology was found on both polysilicon and silicon nitride surfaces of the mEmS. The islands take the form of caps, being up to 0.5 μm in diameter and 20 nm in height. It is concluded that the co-existence of columnar growth and equiaxed growth during the low pressure chemical vapor deposition(LPCVD) of these layers leads to the observed morphology and the islands are caps to the columnar structures.

关键词： microelectromechanical systems XPS Atomic force microscopy

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One-Dimensional Anyon Lattice and slq（2） Algebra Realization

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Chinese Physics Letters 2005年第5期22卷 1207-1209页

作者： z.Bentalha m.Tahiri B.Liani TheoreticalPhysicsLaboratory TlemcenUniversityTlemcenAlgeria LaboratoiredePhysiqueThéorique Universitéd'Essenia31100OranAlgeria

We discuss the connection between anyons (Particles with fractionalstatistics) living on a one-dimensional lattice and sl(q)(2) algebra. We assign to each site-anyonfield, then we demand the anyonic fields to be noncommuting objects in agreement with theChern-Sinions picture of anyons. We show how the anyonic algebra can emerge from these noncommutingobjects. Starting from the emerged algebra we build the Sl(q)(2) algebra at q roots of unity.

关键词： Algebra

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Stress Intensity Factor for the Interaction between a Straight Crack and a Curved Crack in Plane Elasticity

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Acta mechanica Solida Sinica 2016年第4期29卷 407-415页

作者： m.R.Aridi N.m.A.Nik Long z.K.Eshkuvatov Institute for mathematical Research Universiti Putra Malaysia College of Foundation and General Studies Universiti Tenaga Nasional mathematics Department Faculty of Science Universiti Putra Malaysia

Formulation in terms of hypersingular integral equations for the interaction between straight and curved cracks in plane elasticity is obtained using the complex variable functions method. The curved length coordinate method and a suitable numerical scheme are used to solve such integrals numerically for the unknown function, which are later used to find the stress intensity factor, SIF.

关键词： hypersingular integral equation complex variable function method curved length coordinate method stress intensity factor

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Parallel propagating modes and anomalous spatial damping in the ultra-relativistic electron plasma with arbitrary degeneracy

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Chinese Physics B 2017年第11期26卷 76-82页

作者： H Farooq m Sarfraz z Iqbal G Abbas H A Shah Department of Physics Government College University Government College University

The dispersion relations of parallel propagating modes（Langmuir mode, right and left handed circular polarized waves） in the weak magnetic field limit ｜ω-k·v｜〉〉？ are considered for ultra-relativistic arbitrary degenerate electron plasma. The results are presented in terms of moments of Fermi-Dirac distribution. The increase in the electron equilibrium number density from negative large（weakly degenerate） to positive large（highly degenerate） values of μ/Te is observed（where μ is the electron chemical potential and Te is the electron thermal energy）. As a result, shifting of the cutoff points in all the real dispersion branches towards the higher values and increasing in the band gap between unmagnetized longitudinal and transverse modes in k-space are examined. Also, the suppression of the weak magnetic field effects in weakly magnetized right handed and left handed circular polarized waves and a decrease in the longitudinal and transverse screening effects are observed in the graphical patterns due to an increase in the equilibrium number density.

关键词： degenerate Fermi gases relativistic plasmas electromagnetic waves

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Correlation between Porosity and Fracture mechanism in High Pressure Die Casting of Am60B Alloy

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Journal of materials Science & Technology 2016年第1期32卷 54-61页

作者： X.Li S.m.Xiong z.Guo School of materials Science and Engineering Tsinghua University State Key Laboratory of Automobile Safety and Energy Tsinghua University

X-ray tomography was used to characterize the porosity in high pressure die casting of Am60B alloy. In situ tensile deformation was performed to observe the change of porosities and their influences on crack initiation, propagation and subsequent fracture of specimen. Results showed that four types of porosi- ties, including gas-shrinkage pore, gas pore, net-shrinkage and island-shrinkage, could be identified according to the formation mechanism and morphology characterization. During tensile deformation, it was shown that the gas-shrinkage pore and net-shrinkage, rather than gas pore or island-shrinkage, were the main sources for crack initiation. In addition, the crack propagated by interconnecting the po- rosities at the cross section with minimum efficient force bearing area. At these locations where externally solidified crystals （ESCs） were present, the crack would propagate along the ESC boundaries in an inter- granular mode, while at these locations without ESCs, the crack would propagate roughly along the direction perpendicular to the tensile stress in a combination of trans-granular and inter-granular modes.

关键词： High pressures die casting Am60B alloy Fracture mechanism Porosity

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Benzene selective hydrogenation over supported Ni(nano-) particles catalysts: Catalytic and kinetics studies

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Chinese Journal of Chemical Engineering 2018年第3期26卷 521-528页

作者： m.H.Peyrovi N.Parsafard z.mohammadian Faculty of Chemistry Science and Petroleum Department of Physical Chemistry University of Shahid Beheshti Kosar University of Bojnord Department of Applied Chemistry

This report aims to reduce the benzene in a mixture of benzene and toluene as a model reaction using catalytic hydrogenation. In this research, we developed a series of catalysts with different supports such as Ni/HmS, Ni/HzSm-5, Ni/HzSm5-HmS, Ni/Al2O3 and Ni/SiO2. Kinetic of this reaction was investigated under various hydrogen and benzene pressures. For more study, two kinetic models have also been selected and tested to describe the kinetics for this reaction. Both used models, the power law and Langmuir-Hinshelwood, provided a good fit toward the experimental data and allowed to determine the kinetic parameters. Among these catalysts, Ni/Al2O3 showed the maximum benzene conversion （99.19%） at 130℃ for benzene hydrogenation. The lowest toluene conversion was observed for Ni/SiO2. Furthermore, this catalyst presented high selectivity to benzene （75.26%） at 130℃. The catalytic performance （activity, selectivity and stability） and kinetics evaluations were shown that the Ni/SiO2 is an effective catalyst to hydrogenate benzene. It seems that the surface properties particularly pore size are effective parameter compared to other factors such as acidity and metal dispersion in this process.

关键词： Catalytic hydrogenation Power law model Langmuir-Hinshelwood mode Selectivity Kinetics

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The dynamics of a nanosecond gas discharge development with an extended slot cathode in argon

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Plasma Science and Technology 2020年第12期22卷 78-88页

作者： N A ASHURBEKOV K O ImINOV G S SHAKHSINOV m z zAKARYAEVA K m RABADANOV Dagestan State University Faculty of PhysicsMakhachkala 367000Russia Institute of Physics DFRC of RASMakhachkala 367015Russia

The article presents the results of an experimental study and numerical modelling for the formation and development dynamics of a high-voltage transverse nanosecond discharge generated by a slot cathode in an argon medium at a pressure range of 1–10 Torr. Numerical modelling was carried out under similar experimental conditions for the processes of formation and propagation of ionisation waves, electron density distribution, excited atom and average electron energy in the discharge gap, including the cavity inside the cathode. At a pressure of p=1 Torr, a classical version of a high-voltage discharge is demonstrated to take place with no penetration of the plasma into the cathode cavity and no observed hollow cathode effect. An increase in gas pressure to 5 Torr leads to a penetration of plasma into the cathode cavity with the formation of a cathodic potential drop(CPD) region. Electrons emitted from the side surfaces of the cavity pass through the CPD region without collisions, oscillate inside the cathode cavity;the hollow cathode effect is fully manifested. At р=10 Torr, the modelling results qualitatively coincide with the results at р=5 Torr;in this case, however, hardly any accelerated electrons are observed in the gap between the electrodes, due to their energetic relaxation both inside the cathode cavity and when exiting from it. In both cases, the plasma structure formed at the exit of the cathode cavity involves a concentration of charged particles an order of magnitude higher than that in the rest of the gap, leading to a self-limiting discharge current effect. The results of the numerical modelling are in good agreement with experimental data.

关键词： nanosecond gas discharge numerical simulation argon excited atoms

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Fabrication and Characterization of a 2×2 microfiber Knot Resonator Coupler

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Chinese Physics Letters 2012年第8期29卷 96-98页

作者： A.A.Jasim A.z.zulkifli m.z.muhammad H.Ahmad S.W.Harun Department of Electrical Engineering University of Malaya 50603 Kuala LumpurMalaysia Photonics Research Center Department of PhysicsUniversity of Malaya50603 Kuala LumpurMalaysia

A 2×2 microfiber knot resonator(mKR)coupler is *** hybrid device is obtained by forming a knot within the coupling region of a microfiber coupler with a 50:50 splitting *** microfiber coupler is successfully fabricated by laterally fusing and tapering two optical fibers using a flame-brushing *** coupler has an overlapping length of 40 mm with a uniform waist of around 5μ*** an mKR structure,the coupler produces a resonant response at both output *** free spectral range of the output spectrum from both ports is obtained at 0.2 nm at a knot diameter of 260μ*** resonance extinction ratio of the device varies from 2 to 6 dB while the calculated Q factor and finesse are~25646 and 3.3,respectively,at both output ports.

关键词： technique fiber resonator

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Impact of coupling geometry on thermoelectric properties of oligophenyl-base transistor

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Chinese Physics B 2017年第2期26卷 420-427页

作者： S Ramezani Akbarabadi H Rahimpour Soleimanit m Bagheri Tagani z Golsanamlou Computational Nanophysics Laboratory （CNL） Department of Physics University of Guilan Rasbt P. O. Box 41335-1914Iran

Thermal and electron transport through organic molecules attached to three-dimensional gold electrodes in two different configurations, namely para and meta with thiol-terminated junctions is studied theoretically in the linear response regime using Green＇s function formalism. We used thiol-terminated（–SH bond） benzene units and found a positive thermopower because the highest occupied molecular orbital（HOmO） is near the Fermi energy level. We investigated the influence of molecular length and molecular junction geometry on the thermoelectric properties. Our results show that the thermoelectric properties are highly sensitive to the coupling geometry and the molecular length. In addition, we observed that the interference effects and increasing molecular length can increase the thermoelectric efficiency of device in a specific configuration.

关键词： coupling geometry figure of merit Green's function oligophenyl thermopower

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