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vibration characteristics of piezoelectric functionally graded carbon nanotube-reinforced composite doubly-curved shells

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Applied mathematics and mechanics(English Edition) 2021年第6期42卷 819-840页

作者： v.v.THAm H.Q.TRANT T.m.TU National Univensity of Ciwil Engineering Giai Phong Road 55Hai Ba Trung DistrictHanoi 100000 Vietnam

This paper presents an analytical solution for the free vibration behavior of functionally graded carbon nanotube-reinforced composite(FG-CNTRC) doubly curved shallow shells with integrated piezoelectric layers. Here, the linear distribution of electric potential across the thickness of the piezoelectric layer and five different types of carbon nanotube(CNT) distributions through the thickness direction are considered. Based on the four-variable shear deformation refined shell theory, governing equations are obtained by applying Hamilton's principle. Navier's solution for the shell panels with the simply supported boundary condition at all four edges is derived. Several numerical examples validate the accuracy of the presented solution. New parametric studies regarding the effects of different material properties, shell geometric parameters, and electrical boundary conditions on the free vibration responses of the hybrid panels are investigated and discussed in detail.

关键词： free vibration four-variable shear deformation refined theory functionally graded carbon nanotube-reinforced composite(FG-CNTRC) piezoelectric material

Tuning the particle size,physical properties,and photocatalytic activity of Ag_(3)PO_(4)materials by changing the Ag^(+)/PO_(4)^(3-)ratio

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Chinese Physics B 2023年第3期32卷 561-568页

作者： Hung N m Oanh L T m Chung D P Thang D v mai v T Hang L T minh N v Center for Nano Science and Technology Hanoi National University of Education136 Xuan Thuy RoadCau Giay DistrictHanoi 100000Vietnam Department of Physics Hanoi National University of Education136 Xuan Thuy RoadCau Giay DistrictHanoi 100000Vietnam Hanoi University of mining and Geology Duc Thang WardNorth Tu Liem DistrictHanoi 100000Vietnam Institute of materials Science Vietnam Academy of Science and Technology18 Hoang Quoc VietHanoi 100000Vietnam Faculty of Basic Sciences Hanoi University of Natural Resources and Environment41 A Phu Dien RoadNorth Tu LiemHanoi 100000Vietnam

This study demonstrates the influence of the Ag^(+)/PO_(4)^(3-)ratio in precursor solution on the crystal structural formation,morphology,physical properties,and photocatalytic performance of a Ag_(3)PO_(4)photocatalyst that is fabricated,using a facile precipitation method,from AgNO_(3)and Na2HPO_(4)·12H_(2)*** material characterizations were carried out using x-ray diffraction(XRD),scanning electron microscopy(SEm),energy-dispersive x-ray spectroscopy(EDX),Brunauer–Emmett–Teller(BET)surface area,Fourier transform infrared(FTIR)absorption,Raman scattering,x-ray photoelectron spectroscopy(XPS),Uv-vis absorption,and photoluminescence(PL).The results show that Ag_(3)PO_(4)crystallizes better when the excess PO_(4)^(3-)content increases,and the lattice parameters decrease slightly,while the crystal diameter and the particle size *** change is also observed in the Raman scattering and FTIR spectra with the increase in the vibration frequency of the[PO_(4)]*** compression of the[PO_(4)]unit was also confirmed in the XPS spectra with the shift of P 2p peaks toward higher binding *** photocatalytic results showed that the samples synthesized from excess PO_(4)^(3-)solution exhibited higher photocatalytic performance compared to the sample with a Ag^(+)/PO_(4)^(3-)ratio of 3:1.A sample prepared from the precursor solution with a Ag^(+)/PO_(4)^(3-)ratio of 3:1.5 was optimal for RhB decomposition under both visible light and natural sunlight,completely decomposing 10 ppm RhB after 15 minutes of xenon lamp irradiation and after 60 minutes under solar light *** is attributed to the high crystallinity,small particle size and low electron–hole recombination rate of the sample.

关键词： morphology photocatalytic Ag^(+)/PO_(4)^(3-)ratio visible light

Ferrofluid nucleus phase transitions in an external uniform magnetic field

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Chinese Physics B 2015年第10期24卷 322-330页

作者： B.m.Tanygin S.I.Shulyma v.F.Kovalenko m.v.Petrychuk Faculty of Radiophysics Taras Shevchenko National University of Kyiv

The phase transition between a massive dense phase and a diluted superparamagnetic phase has been studied by means of a direct molecular dynamics simulation. The equilibrium structures of the ferrofluid aggregate nucleus are obtained for different values of a temperature and an external magnetic field magnitude. An approximate match of experiment and simulation has been shown for the ferrofluid phase diagram coordinates ＂field-temperature＂. The provided phase coexistence curve has an opposite trend comparing to some of known theoretical results. This contradiction has been discussed. For given experimental parameters, it has been concluded that the present results describe more precisely the transition from linear chains to a dense globes phase. The theoretical concepts which provide the opposite binodal curve dependency trend match other experimental conditions： a diluted ferrofluid, a high particle coating rate, a high temperature,and/or a less particles coupling constant value.

关键词： ferrofluid aggregate phase diagram molecular dynamics

Secure Data Sharing with Confidentiality,Integrity and Access Control in Cloud Environment

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Computer Systems Science & Engineering 2022年第2期40卷 779-793页

作者： v.Rajkumar m.Prakash v.vennila Department of Computer Science and Engineering Krishnasamy College of Engineering and Technology(Affiliated to Anna UniversityChennai)Cuddalore607109India Department of Computer Science and Engineering School of ComputingSRM Institute of Science&TechnologyKattankulathur603203India Department of Computer Science and Engineering K.S.R.College of Engineering(Affiliated to Anna UniversityChennai)Tiruchengode637215India

Cloud storage is an incipient technology in today’s *** of security in cloud environment is one of the primary challenges faced these *** scenario poses new security issues and it forms the crux of the current *** current study proposes Secure Interactional Proof System(SIPS)to address this *** methodology has a few key essential components listed herewith to strengthen the security such as authentication,confidentiality,access control,integrity and the group of components such as AvK Scheme(Access List,verifier and Key Generator).It is challenging for every user to prove their identity to the verifier who maintains the access *** is conducted by following Gulliou-Quisquater protocol which determines the security level of the user in multi-step authentication ***,RSA algorithm performs the key generation process while the proposed methodology provides data integrity as well as confidentiality using asymmetric *** methodological operations such as time consumption have been used as performance evaluators in the proposed SIPS *** proposed solution provides a secure system for firm data sharing in cloud environment with confidentiality,authentication and access *** Timed Petri(STPN)Net evaluation tool was used to verify and prove the formal analysis of SIPS *** evidence established the effectiveness of the proposed methodology in secure data sharing in cloud environment.

关键词： Secure interactional proof system access control multi-step authentication Gulliou-Quisquater protocol

Stability of stratified shear flows in channels with variable cross sections

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Applied mathematics and mechanics(English Edition) 2015年第11期36卷 1459-1480页

作者： v.R.REDDY m.SUBBIAH Department of mathematics Pondicherry University

For the instability problem of density stratified shear flows in sea straits with variable cross sections, a new semielliptical instability region is found. Rurthermore, the instability of the bounded shear layer is studied in two cases：（i） the density which takes two different constant values in two layers and （ii） the density which takes three different constant values in three layers. In both cases, the dispersion relation is found to be a quartic equation in the complex phase velocity. It is found that there are two unstable modes in a range of the wave numbers in the first case, whereas there is only one unstable mode in the second case.

关键词： hydrodynamic stability shear flow variable density sea strait variablecross section

Formation and Characterization of Ceramic Nanocomposite Crystalline Coatings on Aluminium by Anodization

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Journal of materials Science & Technology 2013年第7期29卷 595-602页

作者： m.mubarak Ali v.Raj School of Chemical Engineering Yeungnam UniversityGyeongsanGyeongbuk 712-749South Korea Advanced materials Research Laboratory Department of ChemistryPeriyar UniversitySalem 636 011Tamil NaduIndia

Ceramic nanocomposite coatings have been synthesized on aluminium by using lithium sulphate electrolyte with zirconium silicate additive by anodization. The effects of current density （CD） on microhardness, structure, composition and surface topography of the oxide layer formed at various CDs （0.1-0.25 A/cm^2） have been studied. Crystalline coatings formed at 0.25 A/cm^2 have been （width 95 nm） observed with a relatively uniform distribution confirmed by scanning electron microscopy. Additionally, the average microhardness value of ceramic nanocomposite coatings fabricated from lithium sulphate-zirconium silicate bath is approximately 8.5 times higher than that of the as-received aluminium. The surface statistics of the coatings is discussed in detail to explain the roughness and related parameters for better understanding. These observations demonstrate the importance of surface statistics in controlling the morphology of the coatings and its properties. From the X-ray diffraction investigations, it can be concluded that the formed nanocomposite coatings are crystalline in nature and that the crystallinity of the coatings decreases with increasing applied current density.

关键词： Anodization Nanocomposite Coatings Alumina Aluminium

Formation and Surface Structural Features of Crystalline Ceramic Nanocomposite Coatings on Aluminium Using Lithium Sulphate with Silicate Additive

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Acta metallurgica Sinica(English Letters) 2014年第2期27卷 185-197页

作者： m.mubarak Ali v.Raj Department of Chemistry Chikkaiah Naicker College Advanced materials Research Laboratory Department of ChemistryPeriyar University

We have synthesized a series of the ceramic coatings by anodization of aluminium using lithium sulphate and sodium silicate additive. Our experiments show that the present coatings are nanocomposites in nature, consisting of a mixture of nanocrystalline alumina, silica, aluminium silicate and mullite; the formation of alumina was similar to conventional anodizing technology, while the formation of mullite was attributed to an addition of sodium silicate. The microhardness of the coatings progressively increased with the increasing current density up to 0.2 A/cm2, which could mainly be attributed to the decrease of porosity in the interfacial region of the oxides up to the range. From the performance of the coatings against corrosion （Tafel/Nyquist plots）, it was inferred that the coatings fabricated by lithium sulphatesodium silicate bath have enhanced corrosion resistance （Rp = 3.12 kΩ）, as well as better microhardness value than that of the lithium sulphate bath alone （Rp = 660.96 Ω） which confirm the perception that the silica particles included in the anodized alumina matrices randomly. Presence of Al, Si and O indicated that the electrolyte components had been intensively incorporated into the coatings.

关键词： Anodization Nanocomposite Ceramic Lithium sulphate

Twofold hidden conformal symmetry of Kerr-Bolt black holes

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Chinese Physics B 2012年第2期21卷 117-122页

作者： m.R.Setare v.Kamali Department of Science Campus of BijarUniversity of Kurdistan BijarIran

Previously we have shown that a four-dimensional Kerr-Bolt black hole in non-extremal and also in extremal cases could be described by a holographic two-dimensional （2D） conformal field theory （CFT） [Ghezelbash A m, Kamali v and Setare m R 2010 Phys. Rev. D 82 124051; Setare m R and Kamali v 2010 JHEP 10 074]. motivated by recent work [Chen C m, Huang Y m, Sun J R, Wu m F and Zou S J 2010 Phys. Rev. D 82 066004], we show that there is another holographic description for these black holes. The first description is called the J-picture, whose construction is based on the black hole angular momentum. The new description is called the Q-picture, whose constructions originate from the nut charge of the black hole. Similar to the previous cases [Ghezelbash A m, Kamali v and Setare m R 2010 Phys. Rev. D 82 124051; Setare m R and Kamali v 2010 JHEP 10 0741, we show that this new picture for a low frequency limit of the wave equation of a massless charged scalar field in the background of a Kerr-Bolt black hole can be written as the Casimir of SL（2, R） symmetry. Our result shows that the entropy of the black hole is reproduced by the Cardy formula. In addition, the absorption cross section is consistent with the finite temperature absorption cross section for a two-dimensional CFT.

关键词： Kerr-Bolt back hole holographic descriptions hidden conformal symmetry Cardy formula

main Directions and Recent Test modeling Results of Lithium Capillary-Pore Systems as Plasma Facing Components

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Plasma Science and Technology 2004年第3期6卷 2291-2295页

作者： v.A.Evtikhin I.E.Lyublinski A.v.vertkov E.A.Azizov S.v.mirnov v.B.Lazarev S.m.Sotnikov v.m.Safronov A.S.Prokhorov v.m.Korzhavin FSUE "Red Star"-"Prana-Center" Co Moscow Russian FSUE TRINITI Troitsk Moscow region Russian Federation RF ministry for Atomic Energy Moscow

At present the most promising principal solution of the divertor problemappears to be the use of liquid metals and primarily of lithium Capillary-Pore Systems (CPS) as ofplasma facing materials. A solid CPS filled with liquid lithium will have a high resistance tosurface and volume damage because of neutron radiation effects, melting, splashing and thermalstress-induced cracking in steady state and during plasma transitions to provide the normaloperation of divertor target plates and first-wall protecting elements. These materials will not bethe sources of impurities inducing an increase of Z_(eff) and they will not be collected as dust inthe divertor area and in ducts. Experiments with lithium CPS under simulating conditions of plasmadisruption on a hydrogen plasma accelerator mK-200 [~ (10 - 15) mJ/m^2, ~ 50 μs] have beenperformed. The formation of a shielding layer of lithium plasma and the high stability of thesesystems have been shown. The new lithium limiter tests on an up-graded T-11m tokamak (plasma currentup to 100 kA, pulse length ~0.3 s) have been performed. Sorption and desorption of plasma-forminggas, lithium emission into discharge, lithium erosion, deposited power of the limiter areinvestigated in these experiments. The first results of experiments are presented.

关键词： lithium divertor plasma facing material