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stability analysis and modeling for the three-dimensional Darcy-Forchheimer stagnation point nanofluid flow towards a moving surface

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Applied Mathematics and Mechanics(English Edition) 2021年第3期42卷 357-370页

作者： Yuming CHU M.I.KHAN M.I.U.REHMAN s.KADRY s.qayyum M.WAQAs Department of Mathematics Huzhou UniversityHuzhou 313000Zhejiang ProvinceChina Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering Changsha University of Science&TechnologyChangsha 410114China Department of Mathematics Riphah International UniversityFaisalabad CampusFaisalabad 38000Pakistan Department of Mathematics Quaid-i-Azam UniversityIslamabad 44000Pakistan Department of Mathematics and Computer science Beirut Arab UniversityBeirut 11072809Lebanon NUTECH school of Applied sciences and Humanities National University of TechnologyIslamabad 44000Pakistan

In this research,the three-dimensional(3D)steady and incompressible laminar Homann stagnation point nanofluid flow over a porous moving surface is *** disturbance in the porous medium has been characterized by the Darcy-Forchheimer *** slip for viscous fluid is *** energy equation is organized in view of radiative heat flux which plays an important role in the heat transfer *** governing flow expressions are first altered into first-order ordinary ones and then solved numerically by the shooting *** solutions are obtained for the velocity,skin friction coefficient,temperature,and Nusselt number subject to sundry flow parameters,magnetic parameter,Darcy-Forchheimer number,thermal radiation parameter,suction parameter,and dimensionless slip *** this research,the main consideration is given to the engineering interest like skin friction coefficient(velocity gradient or surface drag force)and Nusselt number(temperature gradient or heat transfer rate)and discussed numerically through *** conclusion,it is noticed from the stability results that the upper branch solution(UBs)is more reliable and physically stable than the lower branch solution(LBs).

关键词： viscous slip Darcy-Forchheimer relation thermal radiation stagnation point flow dual solution heat generation/absorption stability result

Polarization multiplexing based duplex radio-over-fiber link for millimeter wave signal transmission to a ring of multiple radio access units

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Frontiers of Information Technology & Electronic Engineering 2019年第2期20卷 300-306页

作者： Tayyab MEHMOOD Hina qayyum salman GHAFOOR school of Electrical Engineering and Computer science National University of Sciences and Technology

A radio-over-fiber(RoF) distributed antenna system(DAs) architecture is proposed, where millimeter wave(mm-wave) signals are transmitted to four different radio access units(RAUs) arranged in a ring *** proposed architecture transmits duplex data of 128 Mb/s to each RAU in both downlink(DL) and uplink(UL)directions. The radio frequency(RF) signals are transmitted by polarization multiplexing a multi-wavelength ***-wave signals at a frequency of 25 GHz are generated at each RAU using remote heterodyne *** proposed architecture provides increased coverage while maintaining good bit error rate(BER) results.

关键词： Radio over fiber Millimeter wave Radio access units

Ion-induced kinetic electron emission from ~6LiF,~7LiF and MgF_2 thin films

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Chinese Physics B 2010年第8期19卷 344-349页

作者： s.Ullah A.H.Dogar M.Ashraf A.qayyum Pakistan Institute of Engineering and Applied sciences NiloreIslamabadPakistan Physics Division Pakistan Institute of Nuclear Science and TechnologyP.O.NiloreIslamabadPakistan Optics Laboratories P.O.Box 1021IslamabadPakistan

secondary electron yields for Ar^＋ impact on 6LiF, 7LiF and MgF2 thin films grown on aluminum substrates are measured each as a function of target temperature and projectile energy. Remarkably different behaviours of the electron yields for LiF and MgF2 films are observed in a temperature range from 25 ℃ to 300 ℃. The electron yield of LiF is found to sharply increase with target temperature and to be saturated at about 175 ℃. But the target temperature has no effect on the electron yield of MgF2. It is also found that for the ion energies greater than 4 keV, the electron yield of 6LiF is consistently high as compared with that of 7LiF that may be due to the enhanced contribution of recoiling 6Li atoms to the secondary electron generation. A comparison between the electron yields of MgF2 and LiF reveales that above a certain ion energy the electron yield of MgF2 is considerably low as compared with that of LiF. We suggest that the short inelastic mean free path of electrons in MgF2 can be one of the reasons for its low electron yield.

关键词： ion-induced electron emission alkali halides electronic stopping electron mean free path

Newtonian heating effects in three-dimensional flow of viscoelastic fluid

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Chinese Physics B 2014年第5期23卷 373-379页

作者： A.qayyum T.Hayat M.s.Alhuthali H.M.Malaikah Department of Mathematics Quaid-i-Azam University 45320Islamabad 44000Pakistan Department of Mathematics Faculty of ScienceKing Abdulaziz University

A mathematical model is constructed to investigate the three-dimensional flow of a non-Newtonian fluid. An in-compressible viscoelastic fluid is used in mathematical formulation. The conjugate convective process （in which heat the transfer rate from the bounding surface with a finite capacity is proportional to the local surface temperature） in three-dimensional flow of a differential type of non-Newtonian fluid is analyzed for the first time. series solutions for the nonlinear differential system are computed. Plots are presented for the description of emerging parameters entering into the problem. It is observed that the conjugate heating phenomenon causes an appreciable increase in the temperature at the stretching wall.

关键词： viscoelastic fluid three-dimensional flow Newtonian heating

Glow Discharge Plasma Nitriding of AIsI 304 stainless steel

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Plasma science and Technology 2007年第4期9卷 463-468页

作者： A.qayyum M.A.NAVEED s.ZEB G.MURTAZA M.ZAKAULLAH National Tokamak Fusion Program IslamabadPakistan Department of Physics Quaid-i-Azam University45320 IslamabadPakistan salam Chair in Physics Government College University54000 LahorePakistan

Glow discharge plasma nitriding of AIsI 304 austenitic stainless steel has been carried out for different processing time under optimum discharge conditions established by spectroscopic analysis. The treated samples were analysed by X-ray diffraction （XRD） to explore the changes induced in the crystallographic structure. The XRD pattern confirmed the formation of an expanded austenite phase （TN） owing to incorporation of nitrogen as an interstitial solid solution in the iron lattice. A Vickers microhardness tester was used to evaluate the surface hardness as a function of indentation depth （μm）. The results showed clear evidence of surface changes with substantial increase in surface hardness.

关键词： optical diagnostics plasma nitriding austenitic stainless steel

Development of multi-physics numerical simulation model to investigate thermo-mechanical fatigue crack propagation in an autofrettaged gun barrel

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Defence Technology（防务技术） 2021年第5期17卷 1579-1591页

作者： Naveed Hussain Faisal qayyum Riffat Asim Pasha Masood shah Department of Mechanical Engineering University of Engineering and TechnologyTaxilaPakistan Institut für Metallformung Technische Universitat BeragakademieFreibergGermany

In this research,a detailed multi-physics study has been carried out by numerically simulating a solid fractured gun barrel for 20 thermo-mechanical *** numerical model is based on thermal effects,mechanical stress fields and fatigue crack ***-plastic material data of modified AIsI 4340 at temperatures ranging from 25 to 1200℃and at strain rates of 4,16,32 and 48 s^(-1) was acquired from high-temperature compression *** was used as material property data in the simulation *** boundary conditions applied are kept similar to the working gun barrel during continuous firing.A methodology has been provided to define thermo-mechanically active surface-to-surface type interface between the crack faces for a better approximation of stresses at the crack *** of results from non-autofrettaged and autofrettaged simulation models provide useful information about the evolution of strains and stresses in the barrel at different points under combined thermo-mechanical loading cycles in both *** effect of thermal fatigue under already induced compressive yield due to autofrettage and the progressive degradation of the accumulated stresses due to thermo-mechanical cyclic loads on the internal surface of the gun barrel(mimicking the continuous firing scenario)has been *** between energy release rate at tips of varying crack lengths due to cyclic thermo-mechanical loading in the non-autofrettaged and autofrettaged gun has been carried out.

关键词： steel Autofrettage Gun barrel Crack propagation Thermo-mechanical fatigue Numerical simulation Residual stress dissipation

Electrical and optical measurements in the early hydrogen discharge of GLAsT-Ⅲ

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Plasma science and Technology 2017年第8期19卷 66-75页

作者： s HUssAIN A qayyum Z AHMAD s AHMAD R KHAN M A NAVEED R ALI F DEEBA G M VOROBYOV GLAsT Team National Tokamak Fusion Program 3329 Islamabad Pakistan saint-Petersburg state University 198504 Saint-Petersburg Russia

This work presents the first electrical and optical measurements of the initial phase of hydrogen discharge in the upgraded spherical tokamak GLAsT-III, initiated with electron cyclotron heating（ECH）. Diagnostic measurements provide insights into expected and unexpected physics issues related to the initial phase of discharge. A triple Langmuir probe（TLP） has been developed to measure time series of the floating potential, plasma electron temperature and number density over the entire discharge, allowing monitoring of the two phases of the discharge： the ECH pre-ionization phase following by the plasma current formation phase. A TLP has the ability to give time-resolved measurements of the floating potential（V_（float））, electron temperature（T_e） and ion saturation current（I_（sat）∝n_e√kT_e）.sat e eThe evolution of the ECH-assisted pre-ionization and subsequent plasma current phases in one shot are well envisioned by the probe. Intense fluctuations in the plasma current phase advocate for efficient equilibrium and feedback control systems. Moreover, the emergence of some strong impurity lines in the emission spectrum, even after only a few shots, suggests a crucial need for improvements in the base vacuum level. A noticeable change in the shape of the temporal profiles of the floating potential, electron temperature, ion saturation current（I_（sat）） and light emission has been observed with changing hydrogen fill pressure and vertical magnetic field.

关键词： floating saturation subsequent spherical heating triple unexpected impurity noticeable advocate

Pulsed ion beam-assisted carburizing of titanium in methane discharge

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Chinese Physics B 2010年第1期19卷 247-256页

作者： M.shafiq M.Hassan K.shahzad A.qayyum s.Ahmad R.s.Rawat M.Zakaullah Department of Physics Quaid-i-Azam University Department of Physics GC University National Tokamak Fusion Program Natural sciences and science Education National Institute of EducationNanyang Technological University

The carburizing of titanium （Ti） is accomplished by utilizing energetic ion pulses of a 1.5 kJ Mather type dense plasma focus （DPF） device operated in methane discharge. X-ray diffraction （XRD） analysis confirms the deposition of polycrystalline titanium carbide （TIC）. The samples carburized at lower axial and angular positions show an improved texture for a typical （200）TIC plane. The Williamson-Hall method is employed to estimate average crystallite size and microstrains in the carburized Ti surface. Crystallite size is found to vary from - 50 to 100 nm, depending on the deposition parameters. Microstrains vary with the sample position and hence ion flux, and are converted from tensile to compressive by increasing the flux. The carburizing of Ti is confirmed by two major doublets extending from 300 to 390 cm^-1 and from 560 to 620 cm^-1 corresponding to acoustic and optical active modes in Raman spectra, respectively. Analyses by scanning electron microscopy/energy dispersive x-ray spectroscopy （sEM/EDs） have provided qualitative and quantitative profiles of the carburized surface. The Vickers microhardness of Ti is significantly improved after carburizing.

关键词： carbide plasma focus microstructure surface morphology

Hybrid Renewable Energy Resources Management for Optimal Energy Operation in Nano-Grid

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Computers, Materials & Continua 2022年第5期71卷 2091-2105页

作者： Faiza qayyum Faisal Jamil shabir Ahmad Do-Hyeun Kim Department of Computer Engineering Jeju National UniversityJeju-siJeju Special Self-Governing Province63243Korea Department of IT Convergence Engineering Gachon UniversitySujeong-GuSeongnam-SiGyeonggi-Do461-701Korea

Renewable energy resources are deemed a potential energy production source due to their cost efficiency and harmless reaction to the environment,unlike non-renewable energy ***,they often fail to meet energy requirements in unfavorable weather *** concept of Hybrid renewable energy resources addresses this issue by integrating both renewable and non-renewable energy resources to meet the required energy *** this paper,an intelligent cost optimization algorithm is proposed to maximize the use of renewable energy resources and minimum utilization of non-renewable energy resources to meet the energy requirement for a nanogrid *** actual data set comprising information about the load and demand of utility grids is used to evaluate the performance of the proposed nanogrid energy management *** objective function is formulated to manage the nanogrid operation and implemented using a variant of Particle swarm Optimization(PsO)named recurrent PsO(rPsO).Firstly,rPsO algorithm minimizes the installation cost for ***,the proposed NEMs ensures cost efficiency for the post-installation period by providing a daily operational plan and optimizing renewable ***-of-the-art optimization models,including Genetic Algorithm(GA),bat and different Mathematical Programming Language(AMPL)solvers,are used to evaluate the *** study’s outcomes suggest that the proposed work significantly reduces the use of diesel generators and fosters the use of renewable energy resources and beneficiates the eco-friendly environment.

关键词： smart grid nanogrid distributed generation(DG) renewable energy optimization machine learning