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Microstructure and Mechanical Properties of 45 vol.%SiC_p/7075Al Composite

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Journal of Materials Science & technology 2015年第9期31卷 930-934页

作者： Ziyang Xiu Wenshu Yang Ronghua Dong Murid Hussain Longtao Jiang YongXing Liu Gaohui Wu State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Department of Material Science and Engineering Harbin Institute of Technology Department of Chemical Engineering COMSATS Institute of Information Technology

Microstructure and mechanical behavior of high volume content SiCp/7xxxAl composites have not been explored yet. Therefore, in the present work, 45 vol.% SiCp/7075Al composite has been prepared by pres- sure infiltration method. High density dislocations were found around SiC/Al interface in SiCp/7075Al composite after water-quenching and aging treatment. Fine dispersed nano-η＇ phases were observed after the aging treatment. Adverse to other SiCp/Al composites prepared by the pressure infiltration method, an interface layer was observed between SiC particles and AI matrix. Furthermore, high-resolution trans- mission electron microscopy （HRTEM） observation indicated that this interface layer was coherent/semi- coherent with that of the SiC particles. 45 vol.% SiCp/7075Al composite demonstrated high tensile strength （630 MPa） and micro-ductility. Compared to aged SiCp/2024Al composite, the aged SiCp/7075Al com- posite showed an increase of about 200% in the tensile strain and 90% in the tensile strength, respectively. It is speculated that nano-η＇ phases in the Al matrix significantly contributed to the strengthening effect while the interface layer between SiC and AI matrix might be beneficial to the strength and plasticity of SiCp/7075Al composite.

关键词： Metal matrix composite7075Al InterfaceNano precipitationMechanical properties

Induced modifications in the properties of Sr doped BiFeO3 multiferroics

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Progress in Natural Science:Materials International 2013年第5期23卷 487-492页

作者： Tanvir Hussain Saadat A.Siddiqi Shahid Atiq M.S.Awan Centre of Excellence in Solid State Physics Quaid-e-Azam CampusUniversity of the Punjab Interdisciplinary Research Centre in Biomedical Materials (IRCBM) COMSATS Institute of Information Technology Department of Physics COMSATS Institute of Information Technology

Multiferroics exhibit unique combination of ferroic properties,*** instance,in BiFeO3,magnetic and electric properties *** this work,BiFeO3 and Sr-doped BiFeO3 samples with general formula,Bi1-x Srx FeO3(x=0.00,0.05,0.10,0.20,and 0.30) were synthesized by sol-gel auto-combustion technique,in order to investigate these ferroic *** samples were confrmed to have perovskite type rhombohedral structure,characteristic of BiFeO3.A dilute phase of Bi2Fe4O9was also found in all the Sr-doped *** micrographs of the palletized samples revealed that minutely doped Sr might not have any effect on the morphology of the *** dependent dielectric measurements were carried out at room temperature for all the samples from 100 Hz to 1 *** dielectric constant of un-doped sample at low frequency was 52 which decreased with increasing Sr *** enhancement of magnetic properties was observed with increasing the Sr *** BiFeO3 material was observed to have the least value of remanent *** the Sr2+ tions were doped in BiFeO3,its magnetization and remanence were increased to 0.867 emu/g and 0.175 emu/g,respectively,at x=0.30.

关键词： Bismuth ferrite Ferroelectricity Ferromagnetism Nanomaterials Magnetically ordered materials

Photodetachment of H^- near a hard wall with arbitrary laser polarization direction

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Chinese Physics B 2015年第8期24卷 286-290页

作者： Azmat Iqbal A.Afaq Department of Physics COMSATS Institute of Information Technology Centre of Excellence in Solid State Physics University of the Punjab New Campus

The photodetachment of H-near a hard wall is investigated with linear polarized laser light travelling in arbitrary direction θL with respect to the z axis. An analytical formula for the total cross section is derived using semi-classical closed orbit theory, which consists of two terms, i.e., the smooth background term and the oscillatory term with an extra factor 2(θL). This factor controls oscillations in the total photodetachment cross section. The amplitude of oscillation is maximum at θL = 0 when the laser polarization direction is perpendicular to the wall and it approaches zero at θL = π /2when the laser polarization direction is parallel to the wall. It is also observed that the total cross section depends on the source–wall distance and it reduces to a free space case when the wall is at infinite distance from the source.

关键词： quantum interference photodetachment process hard wall closed orbit theory

EIAS:An Efficient Identity-Based Aggregate Signature Scheme for WSNs Against Coalition Attack

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Computers, Materials & Continua 2019年第6期59卷 903-924页

作者： Yong Xie Fang Xu Xiang Li Songsong Zhang Xiaodan Zhang Muhammad Israr Department of Computer technology and Application Qinghai UniversityXiningChina School of Computer and information Science Hubei Engineering UniversityXiaoganChina Department of Computer Sciences COMSATS UniversityAbbottabadPakistan

Wireless sensor networks(WSNs)are the major contributors to big data *** authenticity and integrity of the data are two most important basic requirements for various services based on big *** aggregation is a promising method to decrease operation cost for resource-constrained ***,the process of data acquisitions in WSNs are in open environments,data aggregation is vulnerable to more special security attacks with hiding feature and subjective fraudulence,such as coalition *** to provide data authenticity and integrity protection for WSNs,an efficient and secure identity-based aggregate signature scheme(EIAS)is proposed in this *** security proof shows that our proposed scheme can be secure against all kinds of *** performance comparisons shows EIAS has clear advantages in term of computation cost and communication cost when compared with similar data aggregation scheme for WSNs.

关键词： Wireless sensor networks(WSNs) big data signature aggregation efficiency coalition attack

Synthesis of Nano-sized Barium Titanate Powder by Solid-state Reaction between Barium Carbonate and Titania

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Journal of Materials Science & technology 2007年第5期23卷 655-658页

作者： U.Manzoor D.K.Kim Department of Physics COMSATS Institute of Information TechnologyIslamabadPakistan Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology(KAIST)DaejeonKorea

Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2.

关键词： Barium tltanate Mechanical milling Solid-state reaction Nano particles

A Review Featuring Fabrication, Properties and Applications of Carbon Nanotubes(CNTs) Reinforced Polymer and Epoxy Nanocomposites

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Chinese Journal of Polymer Science 2018年第4期36卷 445-461页

作者： Sobia Imtiaz Muhammad Siddiq Ayesha Kausar Sedra Tul Muntha Jaweria Ambreen Iram Bibi Department of Chemistry Quaid-i-Azam University Department of Physics Comsats Institute of Information Technology Department of Chemistry Hazara University

Carbon nanotubes（CNTs） have long been recognized as the stiffest and strongest man-made material known to date. In addition, their high electrical conductivity has roused interest in the areas of electrical appliances and communication related applications. However, due to their miniature size, the excellent properties of these nanostructures can only be exploited if they are homogeneously embedded into light-weight matrices as those offered by a whole series of engineering polymers. In order to enhance their chemical affinity to engineering polymer matrices, chemical modification of the graphitic sidewalls and tips is necessary. The mechanical and electrical properties to date of a whole range of nanocomposites of various carbon nanotube contents are also reviewed in this attempt to facilitate progress in this emerging area. Recently, carbonaceous nano-fillers such as graphene and carbon nanotubes（CNTs） play a promising role due to their better structural and functional properties and broad range of applications in every field. Since CNTs usually form stabilized bundles due to van der Waals interactions, they are extremely difficult to disperse and align in a polymer matrix. The biggest issues in the preparation of CNTs reinforced composites reside in efficient dispersion of CNTs into a polymer matrix, the assessment of the dispersion, and the alignment and control of the CNTs in the matrix. An overview of various CNT functionalization methods is given. In particular, CNT functionalization using click chemistry and the preparation of CNT composites employing hyperbranched polymers are stressed as potential techniques to achieve good CNT dispersion. In addition, discussions on mechanical, thermal, electrical, electrochemical and applications of polymer/CNT composites are also included.

关键词： Polymer nanocomposites CNTs Epoxy Conducting polymers RAMs

Quadratic convective flow of radiated nano-Jeffrey liquid subject to multiple convective conditions and Cattaneo-Christov double diffusion

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Applied Mathematics and Mechanics(English Edition) 2018年第9期39卷 1311-1326页

作者： P.B.SAMPATH KUMAR B.MAHANTHESH B.J.GIREESHA S.A.SHEHZAD Department of Studies and Research in Mathematics Kuvempu University Department of Mathematics Christ University Department of Mathematics COMSATS Institute of Information Technology

A nonlinear flow of Jeffrey liquid with Cattaneo-Christov heat flux is investigated in the presence of nanoparticles. The features of thermophoretic and Brownian movement are retained. The effects of nonlinear radiation, magnetohydrodynamic(MHD), and convective conditions are accounted. The conversion of governing equations into ordinary differential equations is prepared via stretching transformations. The consequent equations are solved using the Runge-Kutta-Fehlberg(RKF) method. Impacts of physical constraints on the liquid velocity, the temperature, and the nanoparticle volume fraction are analyzed through graphical illustrations. It is established that the velocity of the liquid and its associated boundary layer width increase with the mixed convection parameter and the Deborah number.

关键词： nonlinear convection Jeffrey liquid nanoliquid convective condition thermophoretic Brownian motion

Thermodynamics of Phantom Energy Accreting onto a Black Hole in Einstein–Power–Maxwell Gravity

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Chinese Physics Letters 2013年第10期30卷 34-37页

作者： G.Abbas R.M.Ramzan Department of Mathematics COMSATS Institute of Information TechnologySahiwal-67000Pakistan Department of Mathematics The Islamia University BahawalpurPakistan

We investigate the phantom energy accretion onto a 3D black hole formulated in the Einstein–Power–Maxwell theory,and present the conditions for critical accretion of phantom energy onto the black ***,we discuss the thermodynamics of phantom energy accreting onto the black hole and find that the first law of thermodynamics is easily satisfied while the second law and the generalized second law of thermodynamics remain invalid and conditionally valid,*** results for the Banados–Teitelboim–Zanelli black hole can be recovered by taking Maxwellian contribution equal to zero.

关键词： Maxwell black law Power

Seismic Hazard Assessment of District Mansehra,Khyber Pakhtoonkhawa,Pakistan

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Acta Geologica Sinica(English Edition) 2014年第4期88卷 1157-1168页

作者： MONA Lisa comsats institute of information technology(CIIT) Islamabad PakistanDepartment of Earth SciencesQuaid-i-Azam University

The site of Mansehra is located seismically in an active regime, known as the Crystalline Nappe Zone and Hazara-Kashmir Syntaxis in NW Himalayas, Pakistan. Seismic Hazard Assessment （SHA） for the site has been carried out by considering the earthquake source zones, selection of appropriate attenuation equations, near fault effects and maximum potential magnitude estimation. The Mansehra Thrust, Oghi Fault, Banna Thrust, Balakot Shear Zone, Main Boundary Thrust, Panjal Thrust, Jhelum Fault and Muzaffarabad Fault and, further to the south, the Sanghargali, Nathiagali, and Thandiani Thrusts are the most critical tectonic features within the 50 km radius of Mansehra. Using the available instrumental seismological data from 1904 to 2007, SHA has been carried out. Other reactivated critical tectonic features in the area have been investigated. Among them the Balakot-Bagh fault, with the fault length of 120 km from Balakot to Poonch, has been considered as the most critical tectonic feature on the basis of geological/structural/seismological data. The potential earthquake of maximum magnitude 7.8 has been assigned to the Balakot-Bagh fault using four regression relations. The peak ground acceleration value of 0.25 g （10% probability of exceedance for 50 years） and 0.5 g has been calculated with the help of the attenuation equation using probabilistic and deterministic approaches.

关键词： Seismic Hazard Assessment Mansehra District NW Himalayas Pakistan Probabilistic and Deterministic Approaches Balakot-Bagh Fault