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Particle Size Distribution and Characterization of High Siliceous and microporous materials

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journal of materials Science & Technology 2005年第4期21卷 563-570页

作者： S.KDurrani j.Akhtar m.Ahmad m.j.moughal Nuclear materials Division Pakistan Institute of Nuclear Science and Technology P.O. Nilore Islamabad PakistanNuclear Materials Division Pakistan Institute of Nuclear Science and Technology P.O. Nilore Islamabad PakistanNuclear Physics Divisions Pakistan Institute of Nuclear Science and Technology P.O. Nilore Islamaad PakistanNuclear Materials Division Pakistan Institute of Nuclear Science and Technology P.O. Nilore. Islamabad. Pakistan

Particle size, textural and surface characteristics influence some major technological properties of high siliceous aluminosilicate zeolite and sillicoaluminophosphate （SAPO） microporous materials. A comparative study was furnished for measuring surface characteristics, particle size and particle size distribution using particle size analyzer （PSA） and scanning electron microscope （SEm）. The PSA is capable of measuring particle diameter in micron range. The results of these techniques for estimation of particle size were compared and correlated statistically. Student t-test and variance ratio test （F-test） methods were performed for the significance of results by the analysis of variance （ANONA） and multiple-range tests. Textural and surface characteristics were evaluated by Brunauer, Emmett ＆ Teller （BET） volumetric technique and v-αs plotting method. The textural results shows that the external surface area and micropore volume of microporous materials were higher than those of the high siliceous zeolites and its zeotype materials.

关键词： Synthesis High siliceous zeolites microporous materials Particle size distribution micropore volume SEm

Cross-focusing of two chirped Gaussian laser beams and THz wave generation in plasmas of multi-ion species under a weakly relativistic and ponderomotive regime

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Plasma Science and Technology 2022年第10期24卷 1-11页

作者： m R jAFARI mILANI S REZAEI m j jAFARI Photonics and Quantum Technologies Research School Nuclear Science and Technology Research InstituteTehran 14665-678Iran Plasma and Fusion Research School Nuclear Science and Technology Research InstituteTehran 14399-51113Iran

The generation of terahertz(THz)waves via the beating of two high-intensity chirped Gaussian lasers in a multi-ion-species plasma is numerically studied by taking into account the weak relativistic and ponderomotive regime of *** coupled differential equations for beamwidth parameters are extracted by introducing the dielectric function of such plasma and using WKB and paraxial ray *** amplitude of THz radiation at beat frequency resulting from the nonlinear current density induced by the beat ponderomotive force of the cross-focusing of beams was *** impacts of the chirp frequency parameter,initial laser intensity and initial ionic species density(specifically,the presence of singly and doubly charged ions)in the plasma on THz generation were *** numerical results reveal that THz radiation generation strongly depends on the chirp frequency parameter.A specific range of chirp frequencies exists for self-focusing as well as THz generation with a'turning point',where the THz emission reaches its maximum *** results show that the strength of self-focusing and consequently the generated THz radiation are reduced by increasing the density of doubly charged ionic species in the plasma due to the suppression of the nonlinear effects.

关键词： laser–plasma interaction THz generation chirped Gaussian laser beams

STABLE AND UNSTABLE STATIONARY TRAjECTORIES

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Applied mathematics and mechanics(English Edition) 2005年第1期26卷 52-57页

作者： j.m.Soriano Departamento de Anlisis matemtico Facultad de MatemticasUniversidad de Sevilla Aptdo.1160 Sevilla 41808 Spain

The stability of stationary trajectories of a particular autonomous system is *** proof of the result is based upon continuation methods.

关键词： autonomous system continuation method trajectory critical point zero point stationary trajectory stable solution asymptotically stable

Finding the Time-dependent Term in 2D Heat Equation from Nonlocal Integral Conditions

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Computer Systems Science & Engineering 2021年第12期39卷 415-429页

作者： m.j.Huntul Department of mathematics College of ScienceJazan UniversityJazanSaudi Arabia

The aim of this paper is to find the time-dependent term numerically in a two-dimensional heat equation using initial and Neumann boundary conditions and nonlocal integrals as over-determination *** is a very interesting and challenging nonlinear inverse coefficient problem with important applications in various fields ranging from radioactive decay,melting or cooling processes,electronic chips,acoustics and geophysics to *** solvability theo-rems of these inverse problems are ***,since the problems are still ill-posed(a small modification in the input data can lead to bigger impact on the ultimate result in the output solution)the solution needs to be ***,in order to obtain a stable solution,a regularized objective function is minimized in order to retrieve the unknown *** two-dimensional inverse problem is discretized using the forward time central space(FTCS)finite-difference method(FDm),which is conditionally stable and recast as a non-linear least-squares minimization of the Tikhonov regularization ***,this is effectively solved using the mATLAB subroutine *** exact and noisy data are *** results for a few benchmark test examples are presented,discussed and assessed with respect to the FTCS-FDm mesh size discretisation,the level of noise with which the input data is contaminated,and the choice of the regularization parameter is discussed based on the trial and error technique.

关键词： Two-dimensional heat equation Neumann boundary conditions inverse identification problems Tikhonov regularization nonlinear optimization

Reconstructing the Time-Dependent Thermal Coefcient in 2D Free Boundary Problems

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Computers, materials & Continua 2021年第6期67卷 3681-3699页

作者： m.j.Huntul Department of mathematics College of ScienceJazan UniversityJazanSaudi Arabia

The inverse problem of reconstructing the time-dependent thermal conductivity and free boundary coefcients along with the temperature in a two-dimensional parabolic equation with initial and boundary conditions and additional measurements is,for the rst time,numerically *** inverse problem appears extensively in the modelling of various phenomena in engineering and *** instance,steel annealing,vacuum-arc welding,fusion welding,continuous casting,metallurgy,aircraft,oil and gas production during drilling and operation of *** literature we already know that this inverse problem has a unique ***,the problem is still ill-posed by being unstable to noise in the input *** the numerical realization,we apply the alternating direction explicit method along with the Tikhonov regularization to nd a stable and accurate numerical solution of nite *** root mean square error(rmse)values for various noise levels p for both smooth and non-smooth continuous time-dependent coef-cients Examples are *** resulting nonlinear minimization problem is solved numerically using the mATLAB subroutine *** exact and numerically simulated noisy input data are *** results presented for two examples show the efciency of the computational method and the accuracy and stability of the numerical solution even in the presence of noise in the input data.

关键词： Inverse identication problem two-dimensional parabolic equation free boundary Tikhonov regularization nonlinear optimization

The analysis of composite laminated beams using a 2D interpolating meshless technique

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Acta mechanica Sinica 2018年第1期34卷 99-116页

作者： S.H.m.Sadek j.Belinha m.P.L.Parente R.m.Natal jorge j.m.A.César de Sá A.j.m.Ferreira Department of mechanical Engineering Faculty of EngineeringUniversity of Porto Institute of mechanical Engineering and Industrial management University of Porto

Laminated composite materials are widely implemented in several engineering constructions. For its relative light weight, these materials are suitable for aerospace, military, marine, and automotive structural applications. To obtain safe and economical structures, the modelling analysis accuracy is highly relevant. Since meshless methods in the recent years achieved a remarkable progress in computational mechanics, the present work uses one of the most flexible and stable interpolation meshless technique available in the literature—the Radial Point Interpolation method(RPIm).Here, a 2 D approach is considered to numerically analyse composite laminated beams. Both the meshless formulation and the equilibrium equations ruling the studied physical phenomenon are presented with detail. Several benchmark beam examples are studied and the results are compared with exact solutions available in the literature and the results obtained from a commercial finite element software. The results show the efficiency and accuracy of the proposed numeric technique.

关键词： Radial point interpolators RPIm Laminated beam meshless method

Spin-correlation function of the fully frustrated Ising model and ±j Ising spin glass on a square lattice

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Chinese Physics B 2013年第6期22卷 549-552页

作者： m Y Ali j Poulter Department of mathematics Faculty of ScienceMahidol University

In this work we study the correlation function of the ground state of a two-dimensional fully frustrated Ising model as well as spin glass. The Pfaffian method is used to calculate free energy and entropy as well as the correlation function. We estimate the exponent of spin correlation function for the fully frustrated model and spin glass. In this paper an overview of the latest results on the spin correlation function is presented.

关键词： spin glass correlation function exponent square lattice

3D printing of patient-specific 316L–stainless–steel medical implants using fused filament fabrication technology: two veterinary case studies

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Bio-Design and manufacturing 2022年第4期5卷 808-815页

作者： j.m.Chacón P.j.Núñez m.A.Caminero E.García-Plaza j.Vallejo m.Blanco Escuela Técnica Superior de Ingeniería Industrial Universidad de Castilla-La ManchaAvdaCamilo JoséCela213071 Ciudad RealSpain Protresde Ingeniería y Soluciones C/Solana 60nave 313005 Ciudad RealSpain

Biomedical fracture fixation implants have complex sculptured geometries to adapt perfectly to fractured bones,making them difficult and expensive to manufacture with conventional machining methods. Fused filament fabrication(FFF) is a very popular Additive manufacturing technology that simplifies the manufacture of parts with complex geometries, making it ideal for the manufacture of customized medical implants.

关键词： steel fracture fused

magnetic, Dielectric and Complex Impedance Properties of xBa_(0.95)Sr_(0.05)TiO_3–(1-x)BiFe_(0.9)Gd_(0.1)O_3multiferroic Ceramics

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Acta metallurgica Sinica(English Letters) 2016年第6期29卷 505-517页

作者： m.j.miah A.K.m.Akther Hossain Department of Physics Bangladesh University of Engineering and Technology Department of Physics Comilla University

xBa_（0.95）Sr_（0.05）TiO_3–（1-x）BiFe_（0.9）Gd_（0.1）O_3[x BST–（1-x）BFGO]（x = 0.00, 0.10, 0.20 and 0.25） multiferroic ceramics were prepared by the standard solid-state reaction technique. Structural characterization was performed by X-ray diffraction. All the samples showed rhombohedral distorted perovskite structure. Surface morphology of the ceramics was studied by the field emission scanning electron microscope（FESEm）. From the FESEm observation, the grain size was observed to be decreased with increasing BST content. Enhanced magnetic properties were observed in BFGO with the increase in BST content because of large lattice distortion. The complex initial permeability increased with the increasing of BST content. The study of dielectric properties showed that the dielectric constant increased, whereas dielectric loss decreased with increasing of BST content due to the reduction of oxygen vacancies. An analysis of the electric impedance and modulus with frequency was performed at different temperatures. Non-Debye-type relaxation processes occur in the compound which was confirmed from the nature of the Cole–Cole plot. The DC conductivity was found to increase with the rise in temperature which indicates the semiconducting behavior of the compound with characteristics of the negative temperature coefficient of resistance. The activation energy, responsible for the relaxation determined from the modulus spectra（0.246 eV）, was found to be almost same as the value obtained from the impedance study（0.240 eV）, indicating that charge carriers overcome the same energy barrier during relaxation. The frequency response of imaginary parts of electric impedance and modulus suggested that the relaxation in xB ST–（1-x）BFGO ceramics follows the same mechanism at various temperatures.

关键词： magnetic properties Dielectric properties Impedance spectroscopy Activation energy