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Characterization of mechanothermal-synthesized hydroxyapatite-magnesium titanate composite nanopowders

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Journal of Advanced Ceramics 2013年第1期2卷 63-70页

作者： abbas FAHAMI Bahman NASIRI-TABRIZI Materials Engineering Department Najafabad BranchIslamic Azad UniversityNajafabadIsfahanIran

Hydroxyapatite-magnesium titanate composite nanopowders have been developed using a mechanothermal *** treatment of the milled powders at 700℃resulted in the formation of HAp/MgTiO_(3)-MgO nanocomposite.X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and energy dispersive X-ray spectroscopy(EDX)techniques were utilized to characterize the synthesized *** results revealed that the dominant phases after mechanical activation were hydroxyapatite,anatase(TiO_(2))and periclase(MgO);while after thermal annealing process at 700℃,hydroxyapatite along with geikielite(MgTiO_(3))and periclase(MgO)were the major *** on the XRD analysis,the evaluation of structural features of the samples indicated that the average crystallite sizes of hydroxyapatite after 10 h of milling and subsequent thermal treatment at 700℃were about 21 nm and 34 nm,*** observations illustrated that the synthesized powders contained large agglomerates which consisted of significantly finer particles with spheroidal *** is concluded that the mechanothermal method can be used to produce hydroxyapatite-based nanocomposite with appropriate structural and morphological features.

关键词： HAp/MgTiO_(3)-MgO nanocomposite characterization methods mechanothermal

EXISTENCE AND ATTRACTIVITY OF k-ALMOST AUTOMORPHIC SEQUENCE SOLUTION OF A MODEL OF CELLULAR NEURAL NETWORKS WITH DELAY

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Acta Mathematica Scientia 2013年第1期33卷 290-302页

作者： Syed abbas 夏永辉 School of Basic Sciences Indian Institute of Technology MandiMandiH.P.-175001India Department of Mathematics Zhejiang Normal University

In this paper we discuss the existence and global attractivity of k-almost automorphic sequence solution of a model of cellular neural networks. We consider the corresponding difference equation analogue of the model system using suitable discretization method and obtain certain conditions for the existence of solution. Almost automorphic function is a good generalization of almost periodic function. This is the first paper considering such solutions of the neural networks.

关键词： almost automorphic sequence difference equations neural networks

Identifying porphyry-Cu geochemical footprints using local neighborhood statistics in Baft area, Iran

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Frontiers of Earth Science 2021年第1期15卷 106-120页

作者： Saeid GHASEMZADEH abbas MAGHSOUDI Mahyar YOUSEFI Department of Mining and Metallurgical Engineering Amirkabir University of TechnologyTehran 95799-79167Iran Faculty of Engineering Malayer UniversityMalayer 65719-95863Iran

Identifying geochemical anomalies related to ore deposition processes facilitates the practice of vectoring toward undiscovered mineral deposit *** districtscale exploration studies,analysis of dispersion patterns of ore-forming elements results in more-reliable ***,deriving significant geochemical footprints and mapping the ensuing geochemical anomalies are of important issues that lead exploration geologists toward anomaly sources,e.g.,*** paper aims to examine the effectiveness of local relative enrichment index and singularity mapping technique,as two methods of local neighborhood statistics,in the delineation of anomalous areas for further exploration.A data set of element contents obtained from stream sediment samples in Baft area,Iran,therefore was applied to illustrate the procedure *** close relationship between anomalous patterns recognized and known Cu-occurrences demonstrated that the procedures proposed can efficiently model complex dispersion patterns of geochemical anomalies in the study *** results showed that singularity mapping method is a better technique,compared to local relative enrichment index,to delineate targets for follow-up exploration in the *** made this comparison because,as pointed out by exploration geochemists,dispersion patterns of geochemical indicators in stream sediments vary in different areas even for the same deposit *** variety in the dispersion patterns is due to the operation of post-mineralization subsystems,which are affected by local factors such as landscape of the areas under ***,the effectiveness of the methods should be evaluated in every area for every targeted deposit.

关键词： local neighborhood statistics robust principal component analysis singularity mapping technique local relative enrichment index exploration targets

Phantom Energy Accretion by a Stringy Charged Black Hole

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Chinese Physics Letters 2012年第1期29卷 28-30页

作者： M.Sharif G.abbas Department of Mathematics University of the PunjabQuaid-e-Azam CampusLahore-54590Pakistan

We investigate the dynamical behavior of phantom energy near a stringy magnetically charged black *** this purpose,we derive equations of motion for steady-state spherically symmetric flow of phantom energy onto the stringy magnetically charged black *** is found that phantom energy accreting onto a black hole decreases its ***,the location of the critical points of accretion is explored,which yields a mass to charge *** ratio implies that accretion process cannot transform a black hole into an extremal black hole or a naked singularity,hence cosmic censorship hypothesis remains valid here.

关键词： singularity hence implies

Power Balance Consideration in the Design of Indirectly Driven Targets

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Plasma Science and Technology 2013年第6期15卷 506-510页

作者： Masoumi MAHBOOBEH Ghasemizad abbas Gholamzadeh LEILA Physics Department Faculty of ScienceGuilan University Physics Department Yazd University

A preliminary design for a heavy ion driver inertial fusion（HIDIF） target is presented. The effect of target material and dimensions on transfer efficiency and symmetrical irradiation in the hohlraum are *** analysis led to the evaluation of optimal target materials and dimensions to achieve a positive power balance of an ICF power *** results show that the best choice is a high Z material for cavity wall materials and a low Z material for the capsule *** is concluded that for achieving the highest transfer efficiency and best symmetrization we need an area ratio between 5≤A2/A1≤9.

关键词： heavy ion beam indirect drive transfer efficiency symmetrization

Physical Layer Authentication Using Ensemble Learning Technique in Wireless Communications

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Computers, Materials & Continua 2022年第12期73卷 4489-4499页

作者： Muhammad Waqas Shehr Bano Fatima Hassan Shanshan Tu Ghulam abbas Ziaul Haq abbas Engineering Research Center of Intelligent Perception and Autonomous Control Faculty of Information TechnologyBeijing University of TechnologyBeijing100124China Faculty of Computer Science and Engineering GIK Institute of Engineering Sciences and TechnologyTopi23460Pakistan School of Engineering Edith Cowan UniversityJoondalup Perth6027WA Australia Faculty of Electrical Engineering GIK Institute of Engineering Sciences and TechnologyTopi23460Pakistan

Cyber-physical wireless systems have surfaced as an important data communication and networking research *** is an emerging discipline that allows effective monitoring and efficient real-time communication between the cyber and physical worlds by embedding computer software and integrating communication and networking *** to their high reliability,sensitivity and connectivity,their security requirements are more comparable to the Internet as they are prone to various security threats such as eavesdropping,spoofing,botnets,man-in-the-middle attack,denial of service(DoS)and distributed denial of service(DDoS)and *** methods use physical layer authentication(PLA),themost promising solution to detect ***,the cyber-physical systems(CPS)have relatively large computational requirements and require more communication resources,thus making it impossible to achieve a low latency *** methods perform well but only in stationary *** have extracted the relevant features from the channel matrices using discrete wavelet transformation to improve the computational time required for data processing by considering mobile *** features are fed to ensemble learning algorithms,such as AdaBoost,LogitBoost and Gentle Boost,to classify *** authentication of the received signal is considered a binary classification *** transmitted data is labeled as legitimate information,and spoofing data is illegitimate ***,this paper proposes a threshold-free PLA approach that uses machine learning algorithms to protect critical data from spoofing *** detects the malicious data packets in stationary scenarios and detects them with high accuracy when receivers are *** proposed model achieves better performance than the existing approaches in terms of accuracy and computational time by decreasing the processing time.

关键词： Physical layer authentication machine learning cyber-physical systems security

CFD simulation of gas-solid flow patterns in a downscaled combustor-style FCC regenerator

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Particuology 2018年第4期16卷 96-108页

作者： abbas Azarnivand Yaghoub Behjat Ali Akbar Safekordi Department of Chemical and Petroleum Engineering SharifUniversity of Technology Tehran lran Process Development and Equipment Technology Division Research Institute of Petroleum Industry Tehran Iran

To investigate the gas-solid flow pattern of a combustor-style fluid catalytic cracking regenerator, a laboratory-scale regenerator was designed. In scaling down from an actual regenerator, large-diameter hydrodynamic effects were taken into consideration. These considerations are the novelties of the present study. Applying the Eulerian-Eulerian approach, a three-dimensional computational fluid dynamics （CFD） model of the regenerator was developed. Using this model, various aspects of the hydrodynamic behavior that are potentially effective in catalyst regeneration were investigated. The CFD simulation results show that at various sections the gas-solid flow patterns exhibit different behavior because of the asymmetric location of the catalyst inlets and the lift outlets. The ratio of the recirculated catalyst to spent catalyst determines the quality of the spent and recirculated catalyst mixing and distribution because the location and quality of vortices change in the lower part of the combustor. The simulation results show that recirculated catalyst considerably reduces the air bypass that disperses the catalyst particles widely over the cross section. Decreasing the velocity of superficial air produces a complex flow pattern whereas the variation in catalyst mass flux does not alter the flow pattern significantly as the flow is dilute.

关键词： Fluid catalytic cracking Combustor-style regeneratorLarge-diameter fluidized bed Hydrodynamics Gas-solid flow patternRecirculated catalyst

Singularities of noncompact charged objects

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Chinese Physics B 2013年第3期22卷 192-195页

作者： M.Sharif G.abbas Department of Mathematics University of the PunjabQuaid-e-Azam CampusLahore-54590Pakistan

We formulate a model for noncompact spherical charged objects in the framework of noncommutative field *** Einstein-Maxwell field equations are solved with charged anisotropic *** choose matter and charge densities as functions of the two parameters,instead of defining these quantities in terms of the Gaussian distribution *** is found that the corresponding densities and the Ricci scalar are singular in origin,whereas the metric is nonsingular,indicating a spacelike *** numerical solution of the horizon equation implies that there are two or one or no horizon（s）,depending on the *** also evaluate the Hawking temperature and find that a black hole with two horizons is evaporated to an extremal black hole with one horizon.

关键词： noncommutative geometry electromagnetic field spacetime singularity

Nano-Patterning of Diffraction Gratings on Human Hair for Cosmetic Purposes

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Journal of Cosmetics, Dermatological Sciences and Applications 2014年第3期4卷 173-178页

作者： khawar abbas Drew F. Goettler Bruce C. Lamartine Zayd C. Leseman Los Alamos National Laboratory Los Alamos USA Mechanical Engineering Department University of New Mexico Albuquerque USA

A method is presented for nano-patterning a diffraction grating on human hair with a focused ion beam. Strands of brown hair are patterned with hyperbolas and Archimedean spirals whose pitches range from 540 nm to 1040 nm. Exposure of the hair strands to white light at various incident angles demonstrates that light of varying wavelengths is diffracted by the diffraction gratings. The diffraction causes the brown strands of hair to reflect light from the entire range of visible light.

关键词： Diffraction Hair Nanopatterning Focused Ion Beam Milling