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Propagation of Ion Solitary Pulses in Dense Astrophysical Electron-Positron-Ion Magnetoplasmas

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Plasma Science and Technology 2015年第12期17卷 1000-1005页

作者： ata-ur-rahman S.A.KHAN A.QAMAR Department of Physics Theoretical Plasma Physics GroupIslamia College Peshawar(A Public Sector University) National Centre for Physics QAU Campus Department of Physics University of Peshawar

In this paper,we theoretically investigate the existence and propagation of low amplitude nonlinear ion waves in a dense plasma under the influence of a strong magnetic *** plasma consists of ultra-relativistic and degenerate electrons and positrons and non-degenerate cold ***,the appearance of two distinct linear modes and their evolution is studied by deriving a dispersion equation with the aid of Fourier ***,the dynamics of low amplitude ion solitary structures is investigated via a Korteweg-de Vries equation derived by employing a reductive perturbation *** effects of various plasma parameters like positron concentration,strength of magnetic field,obliqueness of field,etc.,are discussed in *** the end,analytical results are supplemented through numerical analysis by using typical representative parameters consistent with degenerate and ultra-relativistic magnetoplasmas of astrophysical regimes.

关键词： degenerate relativistic perturbation solitary representative Electron appearance dense collective normalized

Oxidative desulfurization of dibenzothiophene over Fe promoted Co–Mo/Al_2O_3 and Ni–Mo/Al_2O_3 catalysts using hydrogen peroxide and formic acid as oxidants

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Chinese Journal of Chemical Engineering 2018年第3期26卷 593-600页

作者： Yaseen Muhammad Ayesha Shoukat ata ur rahman Haroon ur Rashid Waqas Ahmad Institute of Chemical Sciences University ofPeshawar Khyber Pakhtunkhwa Pakistan School of Chemistry and Chemical Engineering Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology Guangxi University Guangxi 530004 China Department of Chemistry 5arhad University of Science and Information Technology Peshawar Pakistan

This work reports the enhancing effect of a highly cost effective and efficient metal, Fe, incorporation to Co or Ni based Mo/Al2O3 catalysts in the oxidative desulfurization （ODS） of dibenzothiophene （DBT） using H2O2 and formic acid as oxidants. The influence of operating parameters i.e. reaction time, catalyst dose, reaction temperature and oxidant amount on oxidation process was investigated. Results revealed that 99% DBT conversion was achieved at 60℃ and 150 min reaction time over Fe-Ni-Mo/Al2O3. Fe tremendously enhanced the ODS activity of Co or Ni based Mo/Al2O3 catalysts following the activity order：Fe-Ni-Mo/Al2O3 〉 Fe-Co-Mo/Al2O3 〉 Ni-Mo/Al2O3 〉 Co-Mo/Al2O3, while H2O2 exhibited higher oxidation activity than formic acid over all catalyst systems. Insight about the surface morphology and textural properties of fresh and spent catalysts were achieved using scanning electron microscopy （SEM）, X-ray diffraction （XRD）, energy dispersive X-ray （EDX） analysis, Atomic Absorption Spectroscopy （AAS） and BET surface area analysis, which helped in the interpretation of experimental data. The present study can be deemed as an effective approach on industrial level for ODS of fuel oils crediting to its high efficiency, low process/catalyst cost, safety and mild operating condition.

关键词： Oxidative desulfurization Fuel oil Dibenzothiophene Fe promoted (Co/Ni)-Mo/Al2O3 catalyst XRD

Nonplanar Electrostatic Solitary Waves in a Relativistic Degenerate Dense Plasma

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Communications in Theoretical Physics 2013年第4期59卷 479-483页

作者： ata-ur-rahman A. Mushtaq S. Ali A. Qamar Institute of Physics & Electronics University of Peshawar National Center for Physics Shahdrah Valley Road Department of Physics Abdul Wali Khan University

By employing the reductive perturbation technique, the propagation of cylindrical and spherical ion acoustic solitary waves is studied in an unmagnetized dense relativistic plasma, consisting of relativistically degenerate electrons and cold fluid ions. A modified Korteweg-de-Vries equation is derived and its numerical solutions have been analyzed to identify the basic features of electrostatic solitary structures that may form in such a degenerate Fermi plasma. Different degrees of relativistic electron degeneracy are discussed and compared. It is found that increasing number density leads to decrease the aznplitude the width of the ion acoustic solitary wave in both the cylindrical and spherical geometries. The relevance of the work to the compact astrophysical objects, particularly white dwarfs is pointed out.

关键词： nonplanar ion acoustic solitary waves relativistic degenerate plasma modified KdV equation

Damped Kadomtsev–Petviashvili Equation for Weakly Dissipative Solitons in Dense Relativistic Degenerate Plasmas

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Communications in Theoretical Physics 2017年第12期67卷 783-790页

作者： S.Ahmad ata-ur-rahman S.A.Khan F.Hadi Department of Physics University of Kotli Azad Jammu and Kashmir Department of Physics Theoretical Plasma Physics Group Islami a College Peshawar (A Public Sector University) National Centre for Physics Quaid-i-Azam University Campus Department of Nuclear Engineering Kyoto University Department of Applied Physical and Material Sciences University of Swat

We have investigated the properties of three-dimensional electrostatic ion solitary structures in highly dense collisional plasma composed of ultra-relativistically degenerate electrons and non-relativistic degenerate ions. In the limit of low ion-neutral collision rate, we have derived a damped Kadomtsev–Petviashvili(KP) equation using perturbation analysis. Supplemented by vanishing boundary conditions, the time varying solution of damped KP equation leads to a weakly dissipative compressive soliton. The real frequency behavior and linear damping of solitary pulse due to ion-neutral collisions is discussed. In the presence of weak transverse perturbations, soliton evolution with damping parameter and plasma density is delineated pointing out the extent of propagation using typical parameters of dense plasma in the interior of white dwarfs.

关键词： dissipative solitons damped Kadomtsev–Petviashvili equation

Electron acoustic solitary waves in unmagnetized nonthermal plasmas

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Communications in Theoretical Physics 2021年第5期73卷 80-84页

作者： Muhammad Khalid Aqil Khan Mohsin Khan Daud Khan Sheraz Ahmad ata-ur-rahman Department of Physics Government Post Graduate College MardanMardan 23200Pakistan Theoretical Plasma Physics Group Department of PhysicsIslamia College Peshawar(Public Sector University)Peshawar 25120Pakistan Department of Physics Government Post Graduate College NowsheraNowshera 24100Pakistan

Electron acoustic(EA)solitary waves(SWs)are studied in an unmagnetized plasma consisting of hot electrons(following Cairns-Tsalli distribution),inertial cold electrons,and stationary *** employing a reductive perturbation technique(RPT),the nonlinear Korteweg–de Vries(KdV)equation is derived and its SW solution is ***,the effects of plasma parameters such as the nonextensivity parameter(q),the nonthermality of electrons(α),and the cold-to-hot electron density ratio(β)are investigated.

关键词： Electron acoustic solitons KdV equation Cairns-Tsalli distribution

Simultaneous operation of dibenzothiophene hydrodesulfurization and methanol reforming reactions over Pd promoted alumina based catalysts

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燃料化学学报 2012年第6期40卷 714-720页

作者： Muhammad Yaseen Muhammad Shakimllah Imtiaz Ahmad ata ur rahman Faiz ur rahman Muhammad Usman Rauf Razzaq Institute of Chemical Sciences University of Peshawar Khyberpukhtunkhwa Pakistan State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China

In the current study simultaneous reactions of hydrodesulfurization(HDS) of dibenzothiophene(DBT) and reforming of methanol in a micro-autoclave reactor were studied over bi-metallic(Co-Mo/Al2O3 and Ni-Mo/Al2O3) and tri-metallic(Pd-Co-Mo/Al2O3 and Pd-Ni-Mo/Al2O3) catalyst systems which were prepared by incipient impregnation *** situ hydrogen utilization and low Pd loadings were the major targets of this *** comparison purpose,catalytic activity was separately determined for both the methanol reforming and HDS of DBT reactions as *** based catalysts were confirmed with better activity than Co ones for both the reactions with Pd promoted ones ranking at the top ***-Ni-Mo/Al2O3 > Ni-Mo/Al2O3 > Pd-Co-Mo/Al2O3 > Co-Mo/Al2O3 where Pd-Ni-Mo/Al2O3 showed 91% DBT conversion at 380 ℃ and 12 h reaction *** of the selected organic additives on catalytic activity were tested for their effect toward HDS reaction which was unique with close relation to their chemical *** products were quantitatively and qualitatively analyzed via HPLC and GC-MS techniques respectively which helped in elucidating reaction mechanism.

关键词：加氢脱硫二苯并噻吩催化剂高效液相色谱法

Effect of Zn doping on electronic structure and optical properties zincblende GaN(A DFT+U insight)

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Communications in Theoretical Physics 2021年第3期73卷 139-147页

作者： Muhammad Junaid Iqbal Khan Zarfishan Kanwal Masood Yousaf Hamid Ullah Javed Ahmad Abid Latif Yong-Han Shin ata ur rahman Khalid Laboratory of Theoretical and Experimental Physics Department of PhysicsBahauddin Zakariya UniversityMultan(60800)Pakistan Department of Civil Engineering Faculty of Engineering and TechnologyBahauddin Zakariya UniversityMultan60800Pakistan Department of Physics Division of Science and TechnologyUniversity of EducationTownshipLahore54770Pakistan Multiscale Materials Modelling Laboratory Department of PhysicsUniversity of UlsanUlsan44610Republic of Korea

The development of new materials,having exceptional properties in comparison to existing materials is highly required for bringing advancement in electronic and optoelectronic *** this fact,we investigated structural,electronic,and optical properties of zincblende GaN doped with selected Zn concentrations(6.25%,12.50%,and 18.70%),using the first-principle calculations based on density functional theory with GGA+*** conducted the entire study using the WIEN2K *** this study,we calculated various significant parametric quantities such as cohesive energies,formation energies,bulk moduli,and lattice constants along with the study of optical and electronic properties by substituting Ga atoms with Zn atoms in 1×2×2 *** structural stability is confirmed by studying the phonon dispersion curves which suggest that Zn:GaN material is stable against the 6.25%and 18.70%Zn concentrations while for 12.50%,it shows *** Hubbard values U=0,2,4,6 eV were added to GGA and the electronic properties were improved with the U=6 *** absorption was blue shifted while the refractive index and dielectric constant were increased with increasing the Zn *** properties are enhanced due to the prime contribution of cations(Zn)3ri *** optical and electronic properties are further discussed in detail in the entire study.

关键词： density functional theory(DFT) optoelectronics Ⅲ-Ⅴsemiconductors optical properties electronic properties structural properties

Tunable beam deflection based on plasmonic resonators mounted freestanding thermoresponsive hydrogel

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Chinese Optics Letters 2020年第6期18卷 67-70页

作者： ata ur rahman Khalid Juan Liu Naeem Ullah Shiqi Jia Beijing Engineering Research Center for Mixed Reality and Advanced Display School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China

We propose and numerically demonstrate a dynamic beam deflector based on plasmonic resonator loaded thermoresponsive freestanding hydrogel that swells and collapses in water by *** this purpose,we utilize four-step phase gradients mounted on freestanding hydrated *** normal incidence,linearly orthogonal light deflects to 19.44°in the collapsed state and 14.40°in the swollen state of ***,the light deflects at a third angle of 12.29°when the solvent changes from water to *** is expected that our metadesign will provide a platform for dynamic holography,active lensing,data storage,and anticounterfeiting.

关键词： tuning beam deflector hydrogel

Exploitation of geometric and propagation phases for spin-dependent rational-multiple complete phase modulation using dielectric metasurfaces

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Photonics Research 2022年第4期10卷 877-885页

作者： ata ur rahman Khalid Fu FENG Naeem Ullah Xiaocong Yuan Michael Geoffrey Somekh Nanophotonics Research Center Shenzhen Key Laboratory of Micro-Scale Optical Information Technology&Institute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060China Beijing Engineering Research Center for Mixed Reality and Advanced Display School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Faculty of Engineering University of NottinghamNottingham NG72RDUK

Metasurfaces have drawn considerable attention in manipulation of electromagnetic waves due to their exotic subwavelength footprints. Regardless of immense progress of polarization-dependent flat optics, the realization of on-device switchable complete phase multiplication is still missing from design multifunctional devices. Here,by combining geometric and propagation phases, a generalized design principle is proposed that can achieve switchable integer or fractional multiple complete phase modulation in transmitted circularly cross-polarized light by switching the handedness of incident polarization. As a proof of concept, two types of spin-dependent bifunctional wavefront manipulating devices, including switchable beam splitter/beam deflector and spinto-orbital angular momentum converter designs are numerically realized. It is believed that the proposed single-cell spin-switchable rational-multiple complete-phase-modulation design principle based on combined propagation and geometric phases has great potential to underpin the development of meta-optics-based multifunctional operations in the field of integrated optics, imaging, and optical communication.

关键词： polarization phase rational