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Acta mechanica Sinica 2010年第4期26卷 541-550页

作者： A.mahmood C.Fetecau N.A.khan m.Jamil Department of mathematics COMSATS Institute of Information Technology Department of mathematics Technical University of Iasi Department of mathematics University of Karachi Abdus Salam School of mathematical Sciences GC University

The velocity field and the associated shear stress corresponding to the longitudinal oscillatory flow of a generalized second grade fluid, between two infinite coaxial circular cylinders, are determined by means of the Laplace and Hankel transforms. Initially, the fluid and cylinders are at rest and at t = 0＋ both cylinders suddenly begin to oscillate along their common axis with simple harmonic motions having angular frequencies Ω1 and Ω2. The solutions that have been obtained are presented under integral and series forms in terms of the generalized G and R functions and satisfy the governing differential equation and all imposed initial and boundary conditions. The respective solutions for the motion between the cylinders, when one of them is at rest, can be obtained from our general solutions. Furthermore, the corresponding solutions for the similar flow of ordinary second grade fluid and Newtonian fluid are also obtained as limiting cases of our general solutions. At the end, the effect of different parameters on the flow of ordinary second grade and generalized second grade fluid are investigated graphically by plotting velocity profiles.

关键词： Generalized second grade fluid Velocity field Shear stress Longitudinal oscillatory flow Laplace and Hankel transforms

Electrical, Thermal, Photocatalytic and Antibacterial Studies of metallic Oxide Nanocomposite Doped Polyaniline

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Journal of materials Science & Technology 2013年第9期29卷 795-800页

作者： Saima Sultana Rafuddin mohammad Zain khan Khalid Umar m.muneer membrane Research Laboratory Department of Chemistry Faculty of Science Aligarh Muslim University Department of Civil Environmental and Geomatic Engineering Chadwick Building University College London Environmental Research Laboratory Department of Chemistry Faculty of Science Aligarh Muslim University

ZnO-ZrO2 nanocomposite was prepared by sol-gel method and in-situ polymerization was used to synthesize ZnO-ZrO2 nanocomposite doped polyaniline （PANI）. The materials were characterized by X-ray diffraction （XRD）, Fourier transform infrared （FTIR） spectroscopy, transmission electron microscopy （TEm）, scanning electron microscopy （SEm） and energy dispersive X-ray spectroscopy （EDX） to ensure the crystallite size, functional groups, morphology and chemical composition of the polymer nanocomposite complex. The average particle size of the ZnO-Zr02 nanoparticles was found to be 20.5 nm. Thermal gravimetric analysis （TGA） was used to study the thermal stability of the complex, shows improved thermal stability of polymer nanocomposite as compared to the pure organic polymer. The material also possesses good electrical conductivity. Additionally, the photocatalytic activity of the materials was investigated by monitoring the decolorization of Acid Blue 29 dye in a UV photocatalytic reactor and PANI-ZnO-ZrO2 was found to possess higher photocatalytic activity than pure PANI. Finally, the antibacterial activity of the materials was examined and it was observed that PANI-ZnO-ZrO2 could be used as an excellent antibacterial agent. Hence, desired properties could be integrated by mixing appropriate phases of the materials for specific applications such as heterogeneous catalyst, antibacterial agents, antibiotics delivery and high temperature conducting polymers.

关键词： Nanocomposites Polyaniline Electrical conductivity Photocatalyst Antibacterial agents

Experimental investigation of evaporative cooling systems for agricultural storage and livestock air-conditioning in Pakistan

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Building Simulation 2021年第3期14卷 617-631页

作者： Hafiz m.U.Raza muhammad Sultan majid Bahrami Alamgir A.khan Department of Agricultural Engineering Bahauddin Zakariya UniversityBosan RoadMultan 60800Pakistan Laboratory for Alternative Energy Conversion(LAEC) School of Mechatronic Systems EngineeringSimon Fraser UniversitySurreyBCCanada Department of Agricultural Engineering Muhammad Nawaz Shareef University ofAgricultureMultan 60000Pakistan

Evaporative cooling(EC)is an ancient technique that is usually suitable for hot and dry climatic conditions due to the potential of water vapor *** this study,three kinds of evaporative cooling systems such as direct EC(DEC),indirect EC(IEC),and maisotsenko cycle EC(mEC)were locally developed at *** performance of the systems was evaluated and compared for agricultural storage and livestock air-conditioning application in *** experiments were performed for climatic conditions of multan city(Pakistan)and the data were collected for hourly and daily *** to the results,it was observed that the DEC system has the ability to reduce the temperature of ambient air to an average of 8.5℃.Whilst IEC and mEC systems were able to drop the temperature of ambient air to an average of 6.8℃and 8.9℃,*** per the results,the DEC system remained behind to provide desired conditions for livestock and agricultural product storage applications due to excessive *** the other hand,the IEC and mEC systems can achieve the desired conditions for livestock application,but could not provide feasible conditions for various fruits and vegetable *** study concludes that hybrid EC systems can be developed to provide desired conditions for a wide range of applications under varying climatic conditions.

关键词： evaporative cooling air-conditioning dew-point wet-bulb storage livestock

Non-axisymmetric Homann stagnation-point flow of Walter’s B nanofluid over a cylindrical disk

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Applied mathematics and mechanics(English Edition) 2020年第5期41卷 725-740页

作者： m.khan m.SARFRAZ J.AHmED L.AHmAD C.FETECAU Department of mathematics Quaid-i-Azam UniversityTaxila 47050Pakistan Department of Basic Sciences University of Engineering and TechnologySheringal Upper Dir 18000Pakistan Department of mathematics Shaheed Benazir Bhutto UniversitySheringal Upper Dir 18000Pakistan Academy of Romanian Scientists Bucuresti 050094Romania

The study of non-axisymmetric Homann stagnation-point flow of Walter’s B nanofluid along with magnetohydrodynamic(mHD) and non-linear Rosseland thermal radiation over a cylindrical disk in the existence of the time-independent free stream is considered. moreover, the notable impacts of thermophoresis and Brownian motion are analyzed by Buongiorno’s model. The momentum, energy, and concentration equations are converted into the dimensionless coupled ordinary differential equations via similarity transformations, which are later numerically solved by altering the values of the pertinent parameters. The numerical and asymptotic solutions for the large shear-to-strain rate ratio γ =a/bfor the parameters of the displacement thicknesses and the wall-shear stress are computed by perturbative expansion and analyzed. Furthermore, the technique bvp4c in mATLAB is deployed as an efficient method to analyze the calculations for the non-dimensional velocities, temperature, displacement thickness, and concentration profiles. It is observed that the two-dimensional displacement thickness parameters α andβ are reduced due to the viscoelasticity and magnetic field effects. moreover, when the shear-to-strain rate ratio approaches infinity, α is closer to its asymptotic value, while βand the three-dimensional displacement thickness parameter δ1 show the opposite *** outcomes of the viscoelasticity and the magnetic field on the skin friction are also determined. It is concluded that ■ reaches its asymptotic behavior when the shearto-strain rate ratio approaches infinity. meanwhile, ■ shows different results.

关键词： Walter’s B fluid cylindrical disk nanofluid magnetic field non-linear thermal radiation stagnation-point flow

Structural and opto-electrical properties of pyrolized ZnO-CdO crystalline thin films

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Journal of Semiconductors 2015年第5期36卷 1-7页

作者： A.m.m.Tanveer Karim m.K.R.khan m.mozibur Rahman Department of Physics Rajshahi University of Engineering & Technology Department of Physics University of Rajshahi

A series of ZnO-CdO thin films of different molar ratios of Zn and Cd have been deposited on glass sub- strate at substrate temperature -360℃ by the spray pyrolysis technique at an ambient atmosphere. X-ray diffraction （XRD） studies confirmed the polycrystalline nature of the film and modulated crystal structures ofwurtzite （ZnO） and cubic （CdO） are formed. The evaluated lattice parameters, and crystallite size are consistent with literature. Dislocation density and strain increased in the film as the grain sizes of ZnO and CdO are decreased. The band gap energy varies from 3.20 to 2.21 eV depending on the Zn/Cd ratios in the film. An incident photon intensity dependent I-V study confirmed that the films are highly photosensitive. Current increased with the increase of the intensity of the light beam. The optical conductivity and the optical constants, such as extinction coefficient, refractive index and complex dielectric constants are evaluated from transmittance and reflectance spectra of the films and these parameters are found to be sensitive to photon energy and displayed intermediate optical properties between ZnO and CdO, making it preferable for applications as the buffer and window layers in solar cells.

关键词： ZnO-CdO buffer layers XRD spray pyrolysis

A broadband cross-polarization conversion anisotropic metasurface based on multiple plasmon resonances

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Chinese Physics B 2018年第1期27卷 357-364页

作者： m Ismail khan Farooq A Tahir Research Institute for microwave and millimeter-wave Studies (RImmS) National University of Sciences and Technology (NUST) Department of Electrical Engineering COMSATS Institute of Information Technology Attock Campus

A compact broadband cross-polarization conversion metasurface functioning in the microwave regime is realized and experimentally demonstrated. The metasurface consists of a two-dimensional periodic arrangement of anisotropic double- slit split-ring-resonator-based unit cells printed on top of a dielectric substrate, backed by metallic cladding. The proposed metasurface converts an x- or y-polarized wave into its orthogonal polarization over a fractional bandwidth of 100% from 5- 15 GHz, both for normal as well as oblique incidence. moreover, the sub-wavelength unit-cell size, thin dielectric substrate, and unique unit-cell design collectively make the response of the metasurface same for both polarizations and insensitive to the incidence angle. The designed structure is fabricated and tested. The measurement and simulation results are found to be consistent with each other.

关键词： cross-polarization conversion anisotropy metasurface plasmon resonances

Hemodynamic Response Detection Using Integrated EEG-fNIRS-VPA for BCI

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Computers, materials & Continua 2022年第1期70卷 535-555页

作者： Arshia Arif m.Jawad khan Kashif Javed Hasan Sajid Saddaf Rubab Noman Naseer Talha Irfan khan National University of Sciences and Technology(NUST) IslamabadPakistan Intelligent Robotics Lab National Center of Artificial IntelligenceNational University of Sciences and Technology(NUST)IslamabadPakistan Department of mechatronics Engineering Air UniversityIslamabadPakistan Institute of Space Technology IslamabadPakistan

For BCI systems,it is important to have an accurate and less complex architecture to control a device with enhanced *** this paper,a novel methodology for more accurate detection of the hemodynamic response has been developed using a multimodal brain-computer interface(BCI).An integrated classifier has been developed for achieving better classification accuracy using two *** integrated EEG-fNIRS-based vector-phase analysis(VPA)has been *** open-source dataset collected at the TechnischeUniversit鋞Berlin,including simultaneous electroencephalography(EEG)and functional near-infrared spectroscopy(fNIRS)signals of 26 healthy participants during n-back tests,has been used for this *** and physiological noise removal has been done using preprocessing techniques followed by individually detecting activity in both *** resting state threshold circle,VPA has been used to detect a hemodynamic response in fNIRS signals,whereas phase plots for EEG signals have been constructed using Hilbert Transform to detect the activity in each *** threshold circles are drawn in the vector plane,where each circle is drawn after task completion in each trial of EEG ***,both processes are integrated into one vector-phase plot to get combined detection of hemodynamic response for *** of this study illustrate that the combined EEG-fNIRS VPA yields considerably higher average classification accuracy,that is 91.35%,as compared to other classifiers such as support vector machine(SVm),convolutional neural networks(CNN),deep neural networks(DNN)and VPA(with dual-threshold circles)with classification accuracies 82%,89%,87%and 86%*** of this research demonstrate that improved classification performance can be feasibly achieved using multimodal VPA for EEG-fNIRS hybrid data.

关键词： EEG-fNIRS hybrid BCI vector-phase analysis hemodynamic response detection

Novel Analytical Thermal Performance Rate Analysis in ZnO-SAE50 Nanolubricant: Nonlinear mathematical model

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Computers, materials & Continua 2021年第4期67卷 477-489页

作者： Adnan Abbasi Umar khan Naveed Ahmed Syed Tauseef mohyud-Din Ilyas khan El-Sayed m.Sherif Department of mathematics Mohi-ud-Din Islamic UniversityNerian SharifAJ&K12080Pakistan Department of mathematics and Statistics Hazara UniversityMansehra21120Pakistan Department of mathematics HITEC UniversityTaxilaCantt47070Pakistan University of multan Multan66000Pakistan Department of mathematics and Statistics Ton Duc Thang UniversityHo Chi Minh City72915Vietnam Department of mechanical Engineering College of EngineeringKing Saud UniversityAl-Riyadh11421Saudi Arabia Department of Physical Chemistry Electrochemistry and Corrosion LaboratoryNational Research CentreCairo12622Egypt

The investigation of local thermal transport rate in the nanolubricants is *** lubricants are broadly used in environmental pollution,mechanical engineering and in the paint industry due to high thermal performance ***,thermal transport in ZnO-SAE50 nanolubricant under the impacts of heat generation/absorption is *** colloidal suspension is flowing between parallel stretching disks in which the lower disk is positioned at z=0 and upper disk apart from distance *** problem is transformed in dimensionless version via described similarity *** the next stage,an analytical technique(VPm)is implemented for the solution *** graphical results against multiple flow parameters were furnished over the region of interest and explained *** is imperative to mention that the results are plotted for ZnO-SAE50 and conventional liquid as ***,rapid motion of the fluid is perceived against high Reynolds andγ*** wall shear stresses at the upper end rises for multiple Reynolds andγwhile;decrement is detected at the lower *** significant contribution of an internal heat source is noted for thermal performance rate at the upper ***,the local heat transport rate declines at the lower *** altering Reynolds number,prompt heat transfer rate is gained at the upper disk and increasing behavior of the local heat transport rate is slow at the lower *** the study,it is concluded that the nanolubricants have high thermal ***,such fluids are reliable to use in above stated areas.

关键词： Zno-SAE50 nanolubricant thermal performance local heat transport numerical algorithm skin friction

Development of Wheel-less Snake Robot with Two Distinct Gaits and Gait Transition Capability

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International Journal of Automation and computing 2013年第6期10卷 534-544页

作者： m.H.A.majid m.R.khan S.N.Sidek Department of mechatronics Engineering International Islamic University Malaysia

Snake robots are mostly designed based on single mode locomotion. However, single mode gait most likely could not work effectively when the robot is subject to an unstructured working environment with different measures of terrain complexity. As a solution, mixed mode locomotion is proposed in this paper by synchronizing two types of gaits known as serpentine and wriggler gaits used for non-constricted and narrow space environments, respectively, but for straight line locomotion only. A gait transition algorithm is developed to efficiently change the gait from one to another. This study includes the investigation on kinematics analysis followed by dynamics analysis while considering related structural constraints for both gaits. The approach utilizes the speed of the serpentine gait for open area locomotion and exploits the narrow space access capability of the wriggler gait. Hence, it can increase motion flexibility in view of the fact that the robot is able to change its mode of locomotion according to the working environment.

关键词： Bio-inspired robots robotics robot dynamics robot kinematics robotic mechanical systems.

Effect of Nonlinear Convection on Stratified Flow of Third Grade Fluid with Revised Fourier-Fick Relations

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Communications in Theoretical Physics 2018年第7期69卷 25-30页

作者： m.Waqas m.Ijaz khan T.Hayat A.Alsaedi Department of mathematics Quaid-I-Azam University Nonlinear Analysis and Applied mathematics (NAAm) Research Group Department of Mathematics Faculty of ScienceKing Abdulaziz University

Here thermal dependence conductivity and nonlinear convection features in third-grade liquid flow bounded by moving surface having varying thickness are formulated. Stagnation point flow is considered. Revised FourierFick relations and double stratification phenomena are utilized for modeling energy and concentration *** model of considered physical problem is achieved by implementing the idea of boundary layer theory. The acquired partial differential system is transformed into ordinary ones by employing relevant variables. The homotopic scheme yield convergent solutions of governing nonlinear expressions. Graphs are constructed for distinct values of physical constraints to elaborate the heat/mass transportation mechanisms.

关键词： nonlinear convection double stratification revised Fourier-Fick relations third grade liquid ther-mal dependence conductivity