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An experimental inter-comparison of radiotherapic dosimetric delivery to assess X-Ray linear accelerator output characteristics

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Journal of Measurement Science and Instrumentation 2014年第3期5卷 83-86页

作者： k masood T Zafar J Zafar H Zafar Institute of Nuclear Medicine & Oncology (INMOL) Department of Economics Government College University Faculty of Engineering Department of Electrical EngineeringGovernment College University Tissue Optics & Microcirculation Imaging Research Group National University of Ireland

The dosimetric inter-comparison studies carry pertinent significance to ensure uniform radiation dose delivery for clinical trials. This paper investigates the comparative performance analysis of an X-ray high power linear accelerator per- formed by the International Dosimetry Survey Mission and Institute of Nuclear Medicine ＆ Oncology （INMOL）, Lahore. The measurements were made using cylindrical ionization chambers based on the International Atomic Energy Agency （IAEA） TRS-398 protocol for absorbed dose-to-water dosimetric standards, and the percentage deviation was found to be between 0.5 % - 1%. The dosimetric analysis concerning linear X-ray accelerator output performed by INMOL, Lahore was found to be in good agreement with the results of IAEA Dosimtery Survey Mission.

关键词： X-ray linear accelerator dosimetric analysis absorbed chamber phantom

Stokes' First Problem for an MHD Burgers Fluid

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Communications in Theoretical Physics 2013年第1期59卷 99-104页

作者： masood khan Department of Mathematics Quaid-i-Azam University

This work is related to the flow of a magnetohydrodynamic Burgers *** flow of an incompressible conducting Burgers fluid in the presence of a uniform transverse magnetic field over a plate that is moved suddenly is *** the application of the Laplace and Fourier sine transforms techniques,the exact analytical expressions for the velocity field and associated shear stress are determined in simple *** are written as a sum of steady-state and transient *** graphical results are plotted for different values of indispensable parameters and some interesting results are *** corresponding solutions for the hydrodynamic Burgers fluid appear as the limiting cases of the obtained solutions.

关键词： Stokes' first problem Burgers fluid Laplace and Fourier sine transforms exact solutions

MHD Flow of an Oldroyd-B Fluid through a Porous Space Induced by Sawtooth Pulses

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Chinese Physics Letters 2011年第8期28卷 161-164页

作者： masood khan Zeeshan Department of Mathematics Quaid-i-Azam UniversityIslamabad 44000Pakistan

We investigate the unsteady magnetohydrodynamic(MHD)flow of an Oldroyd-B fluid through a porous space induced by sawtooth *** fluid is assumed to be electrically conducting in the presence of a transverse uniform magnetic *** porous space is taken into account using modified Darcy's law for the Oldroyd-B *** solutions of the governing problem are obtained by using the Laplace transform *** effects of the magnetic parameter,the permeability of the porous space and the elasticity parameter of the fluid are studied on the flow characteristics.

关键词： method field porous

Uncertainty of concrete strength in shear and flexural behavior of beams using lattice modeling

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Frontiers of Structural and Civil Engineering 2023年第2期17卷 306-325页

作者： Sahand kHALILZADEHTABRIZI Hamed SADAGHIAN masood FARZAM Department of Civil Engineering University of TabrizTabriz ***Iran

This paper numerically studied the effect of uncertainty and random distribution of concrete strength in beams failing in shear and flexure using lattice modeling,which is suitable for statistical *** independent variables of this study included the level of strength reduction and the number of members with reduced *** levels of material deficiency(i.e.,10%,20%,30%)were randomly introduced to 5%,10%,15%,and 20%of *** provide a database and reliable results,1000 analyses were carried out(a total of 24000 analyses)using the MATLAB software for each *** studies were conducted for both shear-and flexure-deficit beams under four-point loading and results were compared using finite element software where *** of lattice modeling was highlighted as an efficient tool to account for uncertainty in statistical *** showed that the number of deficient members had a more significant effect on beam capacity compared to the level of strength *** scatter of random load-capacities was higher in flexure(range:0.680-0.990)than that of shear(range:0.795-0.996).Finally,nonlinear regression relationships were established with coefficient of correlation values(R^(2))above 0.90,which captured the overall load-deflection response and level of load reduction.

关键词： lattice modeling shear failure flexural failure uncertainty deficiency numerical simulation

Pyridine-Thiourea Based High Performance Polymers: Synthesis and Characterization

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Chinese Journal of Polymer Science 2015年第1期33卷 49-60页

作者： Ghulam Waris Humaira masood Siddiqi Department of Chemistry Quaid-i-Azam University Islamabad Pakistan Department of Chemistry University of SheffieldUK

A novel diamine monomer, pyridine-2, 6-bis（（4-aminophenyl）thioureido）carbonyl（PATC） was synthesized efficiently and polymerized with various aromatic dianhydrides. Consequently, poly（pyridine thiourea-imide）s（PPTIs） with good thermal properties and flame retardancy were fabricated. The structures of PATC and PPTIs were characterized by FTIR, 1H-NMR, 13C-NMR spectroscopy along with elemental analysis, crystallinity, organosolubility, inherent viscosity and gel permeation chromatographic measurements. PPTIs containing C=S, CONH and meta substituted pyridine moieties in the polymer backbone showed amorphous nature and were readily soluble in highly polar organic solvents and even in less polar solvents such as tetrahydrofuran（THF）. Polymers had inherent viscosities in the range of 0.91-1.16 d L/g and molecular weight was found between 68000-77000 g/mol. The electrical properties of the PPTIs were estimated in terms of dielectric constant over a range of frequencies. Their thermal stability was determined by 10% weight loss temperature found in the range of 519-563 °C under inert atmosphere. The glass transition temperature of the polyimides varied between 247 °C and 267 °C. The flame retardant properties of PPTIs were investigated in terms of limiting oxygen index（LOI） which was found in the range of 38.26-39.95. Introduction of thiourea in the polymer backbone is an effective way to improve the thermal stability and flame retardancy. Thus PATC can be considered as an excellent candidate for the synthesis of high performance polymers.

关键词： Poly(pyridine thiourea-imide)s Crystallinity Flame retardancy GPC measurements.

Determination of Two-Dimensional Plastic Zone Shape and SIF at Crack-Tip Using RkPM

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Journal of Iron and Steel Research International 2013年第12期20卷 103-114页

作者： masood Hajali Caesar Abishdid Department of Civil and Environmental Engineering Florida International University Department of Civil Engineering Lebanese American University

Reproducing kernel particle Method （RkPM） is a meshless technology which has proven very useful for solving problems of elastic plastic fracture mechanics. The mode I plastic zone shape at the crack-tip in a work-hard ening material is obtained using RkPM. Ramberg-Osgood stress-strain relation is assumed and the crack-tip stress intensity factor （SIF） before and after formation of the plastic zone are examined. To impose the essential boundary conditions, penalty method is used. To construct the shape functions in the vicinity of the crack and crack-tip, both the diffraction and visibility criteria are employed. A comparison between two conventional treatments, visibility and diffraction, to crack discontinuity is conducted. The effects of different dilation parameters on SIF under plane-stress and plane-strain conditions are ~tudied. Results including plastic zone shape are compared with finite element method （FEM） to show the accuracy of RkPM. The main objective is to study the effects of different dilation parameters on SIF under plane stress and plane strain conditions and to obtain the mode I plastic zone shape at the crack-tip in a work hardening material using RkPM.

关键词： meshless reproducing kernel particle method (RkPM) crack-tip stress intensity factor (SIF) plastic zone shape

The peculiar velocity and temperature profile of galaxy clusters

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Research in Astronomy and Astrophysics 2014年第6期14卷 667-672页

作者： Tabasum masood Naseer Iqbal Department of Physics Kashmir University Inter University Centre for Astronomy and Astrophysics IUCAA

Dynamical parameters like average velocity dispersion and temperature profile of galaxy clusters are determined using the theory of quasi-equilibrium ther- modynamics. The calculated results of velocity dispersion show a good agreement between theory and simulations with the results of velocity dispersion from Abdullah et al. An adaptive mesh refinement grid-based hybrid code has been used to carry out the simulations. Our results indicate that the average velocity dispersion profile of 20 Abell galaxy clusters falls in the range of 500 - 1000 km s^-1 and their temperature profile is of the order of 10^7 to 10^8 k calculated on the basis of kinetic theory. The data in the plot show a significant contribution from gravitating particles clustering together in the vicinity of the cluster center and beyond a certain region this veloc- ity dies out and becomes dominated by the Hubble flow due to which all the galaxy clusters in an expanding universe participate in Hubble expansion.

关键词： galaxies: clusters -- gravitation -- simulations

Formation control of quad-rotor UAV via PIO

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Science China(Technological Sciences) 2022年第2期65卷 432-439页

作者： BAI TingTing WANG DaoBo masood Rana Javed College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China Department of Electrical Engineering Usman Institute of TechnologyKarachi 75850Pakistan

In this article, the formation control of quad-rotor unmanned aerial vehicle(UAV) via pigeon inspired optimization(PIO) is designed. The nonlinear mathematical model of the quad-rotor UAV is used by applying algebraic graph theory and matrix analysis. A high order consistent formation control algorithm with fixed control topology is designed by using a position deviation matrix to describe its formation. To control the attitude of quad-rotor UAVs, it is difficult to obtain a set of optimal solutions, and hence a PIO based algorithm with variable weight hybridization is proposed. The algorithm is mainly composed of two parts. First, according to the distance between the particles in the iterative process, the inertia weight is dynamically changed,and the coefficient is adjusted to control the degree of influence on its inertia weight. Second, the overall scenario is designed by using MATLAB based simulations which show that the formation control of the quad-rotor UAV is achieved with the help of PIO.

关键词： pigeon inspired optimization formation control unmanned aerial vehicle and quad-rotor UAV

Effects of Thermal Radiation and Slip Mechanism on Mixed Convection Flow of Williamson Nanofluid Over an Inclined Stretching Cylinder

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Communications in Theoretical Physics 2019年第12期71卷 1405-1415页

作者： masood khan Aamir Hamid Hashim Department of Mathematics Quaid-i-Azam UniversityIslamabad 44000Pakistan Department of Mathematics&Statistics Riphah International UniversityIslamabadPakistan

The current investigation highlights the mixed convection slip flow and radiative heat transport of uniformly electrically conducting Williamson nanofluid yield by an inclined circular cylinder in the presence of Brownian motion and thermophoresis parameter.A Lorentzian magnetic body force model is employed and magnetic induction effects are *** governing equations are reduced to a system of nonlinear ordinary differential equations with associated boundary conditions by applying scaling group *** reduced nonlinear ordinary differential equations are then solved numerically by Runge-kutta-Fehlberg fifth-order method with shooting *** effects of magnetic field,Prandtl number,mixed convection parameter,buoyancy ratio parameter,Brownian motion parameter,thermophoresis parameter,heat generation/absorption parameter,mass transfer parameter,radiation parameter and Schmidt number on the skin friction coefficient and local Nusselt are analyzed and *** is found that the velocity of the fluid decreases with decrease in curvature parameter,whereas it increases with mixed convection ***,the local Nusselt number decreases with an increase in the radiation *** numerical comparison is also presented with the existing published results and found that the present results are in excellent agreement which also confirms the validity of the present methodology.

关键词： MHD Williamson nanofluid velocity and thermal slip inclined stretching cylinder heat generation/absorption