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Structural,dielectric and electrical properties of bismuth magnesium tantalate electronic system

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Journal of Magnesium and Alloys 2019年第4期7卷 628-636页

作者： Sarbasri Halder Satyanarayan Bhuyan R.n.p.Choudhary Department of Electronics and Communication Engineering Siksha‘O’AnusandhanDeemed to be UniversityBhubaneswar 751030India Department of physics Siksha‘O’AnusandhanDeemed to be UniversityBhubaneswar 751030India

The lead-free dielectric compound Bi(Mg2/3Ta1/3)O3(BMT)has been synthesized at high temperature by a low-cost solid-state *** X-ray diffraction(XRD)technique reveals that the fabricated sample has an orthorhombic crystal *** scanning electron microscope(SEM)image displays the uniform distribution of grains on the surface of the *** dielectric parameters(permittivity(εr),and loss tangent(tanδ)are studied over a wide range of temperature(150-500℃)and frequency(1 kHz-1 MHz).The temperature dependent conductivity plot follows Universal Johnson’s power *** complex impedance and modulus spectrum illustrate the electrical behavior of the compound at various frequency and *** nyquist spectra show the presence of the effect of grain and grain boundary in the synthesized *** grain resistance value declines with the rise in temperature that shows the presence of a negative temperature coefficient(nTCR)behavior in the *** complex modulus spectra display the occurrence of the conduction mechanism in the *** reported compound has a relative dielectric constant and loss of 22×10^3 and 1.8 respectively at 1 kHz frequency and 500℃,thus becoming an efficient applicant for dielectric applications that can operate at higher temperatures.

关键词： XRD Impedance spectroscopy Conductivity Conduction

Calibration of the DEM sliding friction and rolling friction parameters of a cohesionless bulk material

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particuology 2024年第9期92卷 126-139页

作者： Jonatan Marín pérez Tugrul Comlekci Yevgen Gorash Donald MacKenzie University of Strathclyde 75 Montrose StreetG11XJGlasgowUnited Kingdom

The discrete element method(DEM)has become a valuable tool for understanding the mechanical behaviour of granular assemblies,however,the accuracy of the DEM simulations depends on several interaction parameters such as the sliding friction and rolling friction ***,these parameters are estimated using bulk calibration approach(BCA)where the draw down test has been suggested as an effective way to approach these *** test provides up to four bulk criteria,the angle of repose,shear angle,mass flow rate and the mass loss which are used to narrow down the possible ***,there is still more research needed around it to fully understand how this methodology *** experimental and numerical study was carried out using the draw down test to assess the influence of different mass flow rates and particle shapes on DEM parameters for a cohesionless bulk *** is concluded that use of multi-sphere particles and three aperture sizes in the draw down test to calibrate the sliding and rolling friction parameters of a cohesionless bulk material can converge to a small feasible region in which a single combination of the friction coefficients can be *** calibrated sliding and rolling friction coefficients were validated using multi-sphere particles,where the maximum deviation was 5.9%from the experimental values.

关键词： Discrete element method Calibration Draw down Sliding friction Rolling friction particle shape

Evaluation of effectiveness of polymer coatings in reducing blastinduced deformation of steel plates

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Defence Technology（防务技术） 2021年第6期17卷 1895-1904页

作者： Damith Mohotti p.L.n.Fernando Dakshitha Weerasinghe Alex Remennikov School of Engineering and Information Technology The University of New South WalesCanberraACT2600Australia Department of Civil Engineering Faculty of EngineeringGeneral Sir John Kotelawala Defence UniversityRatmalanaSri Lanka School of Civil Engineering Faculty of EngineeringThe University of SydneyDarlingtonNSW2006Australia Centre for Infrastructure protection and Mining Safety University of WollongongWollongongNSW2522Australia

Incorporating elastomers such as polymers in protective structures to withstand high energetic dynamic loads,has gained significant *** main objective of this study is to investigate the influence of a polyurea coating towards the blast-induced response in steel *** such,polyurea coated steel plates were tested under near-field blast loads,produced by the detonation of 1 kg of spherical nitromethane charges,at a standoff distance of 150 *** steel(XLERpLATE 350)and high-strength steel(BIS80)plates with thicknesses of 10 mm were polyurea coated with thicknesses of 6 mm and 12 mm on either the front(facing the charge)or the back *** deformation profiles were measured using 3D *** simulations were performed using the non-linear finite element code *** strain-dependent behaviour of the steel and polyurea were represented by Johnson-cook and Money-Rivlin constitutive models,*** numerical models were validated by comparing the plate deflection results obtained from the experiments and were then used in the subsequent parametric study to investigate the optimum thickness of the polyurea *** results indicate that back face coating contributes towards an approximately 20%reduction in the residual deformation as well as the absence of melting of the polyurea layer,while the front-face coating can be used a means of providing additional standoff distance to the steel plates.

关键词： polyurea coating near-field blast LS-DYnA plate deformation ALE

Species Diversity and population Status of Threatened plants in Different Landscape Elements of the Rohtang pass,Western Himalaya

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Journal of Mountain Science 2008年第1期5卷 73-83页

作者： K.n.Singh Gopichand Amit Kumar Brij Lal n.p.Todaria Biodiversity Division Institute of Himalayan Bioresource Technology (CSIR)PalampurHimachal Pradesh176 061India Forestry department HNB Garhwal UniversitySrinagarUttarakhandIndia

This paper highlights the quantitative estimates of plant species diversity and ecosystems of the Rohtang pass,which is one of the most preferred visiting spots by tourists in Himachal pradesh (H.p.),India. In spite of high pressure of anthropogenic activities,the Rohtang pass still harbours a variety of flowering plants with economic value,including various medicinal herbs. In order to observe species diversity in different landscape elements (LSEs),ground surveys were conducted in nine unique LSEs within the elevation range between 3624 m and 4332 m. plant community structure in each LSE was studied using stratified random sampling where a total 56 quadrats of 1 m2 in size for herbs and 7 quadrats of 25 m2 for shrubs were made. Of the total 50 plant species belonging to 15 families recorded in different random quadrats,24 species were found of medicinal value. Maximum species richness (18) and value of Shannon diversity (H'=2.2648) were observed on northeast-facing slope in picrorhiza kurrooa dominated LSE in moist area,followed by Rheum emodi LSE (species richness = 17 and H' = 2.4141) distributed on south-facing slope. Maximum values of species richness and Shannon diversity in Rheum emodi LSE were observed between 8 ～ 12 and 1.4797 ～ 2.1911,respectively. Rhododendron anthopogon dominated LSE on northwest-facing slope was found least diverse in terms of species richness where the Simpson index of dominance (D) was 0.4205. The species were equal in abundance in p. kurrooa LSE on east-facing slope and pleurospermum candollii LSE on north-facing slope,showing the maximum similarity in terms of species distribution between the two LSEs. Low turnover of species across common LSEs gives an idea regarding their limited distribution. Five species of threatened category according to the IUCn criteria were observed in seven LSEs. The largest population of threatened medicinal plants was recorded on northeast and northwest-facing slopes where population density of Bergenia

关键词： Species diversity threatened plant landscape Rohtang pass western Himalaya

Temperature and strain registration by fibre-optic strain sensor in the polymer composite materials manufacturing

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International Journal of Smart and nano Materials 2018年第2期9卷 99-110,I0003页

作者： V.p.Matveenko n.A.Kosheleva I.n.Shardakov A.A.Voronkov Department of complex problems of deformable solids mechanics Institute of Continuous Media Mechanics of the Ural Branch of RAS(ICMM UB RAS)PermRussian Federation Scientific&Educational Center for Aviation Composite Technologies Perm National Research Polytechnic University(PNRPU)PermRussian Federation

The presence of process-induced strains induced by various manufacturing and operational factors is one of the characteristics of polymer composite materials(pCM).Conventional methods of registration and evaluation of process-induced strains can be laborious,time-consuming and demanding in terms of technical *** employment of embedded fibre-optic strain sensors(FOSS)offers a real prospect of measuring residual *** paper demonstrates the potential for using embedded FOSS for recording technological strains in a pCM *** pCM plate is manufactured from prepreg,using the direct compression-moulding *** this method,the prepared reinforcing package is placed inside a mould,heated,and then exposed to compaction *** examined technology can be used for positioning FOSS between the layers of the composite ***-optic sensors,interacting with the material of the examined object,make it possible to register the evolution of the strain process during all stages of polymer-composite *** data were recorded with interrogator ASTRO X *** obtained data were processed using specially developed algorithms.

关键词： polymer composite materials fibre-optic strain sensors process-induced strains smart-materials

Context-Aware practice problem Recommendation Using Learners’ Skill Level navigation patterns

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Intelligent Automation & Soft Computing 2023年第3期35卷 3845-3860页

作者： p.n.Ramesh S.Kannimuthu Computer Science and Engineering Karpagam Institute of TechnologyCoimbatore641105India Information Technology Karpagam College of EngineeringCoimbatore641032India

The use of programming online judges(pOJs)has risen dramatically in recent years,owing to the fact that the auto-evaluation of codes during practice motivates students to learn *** pOJs have greater number of pro-gramming problems in their repository,learners experience information *** systems are a common solution to information *** recommender systems used in e-learning platforms are inadequate for pOJ since recommendations should consider learners’current context,like learning goals and current skill level(topic knowledge and difﬁculty level).To overcome the issue,we propose a context-aware practice problem recommender system based on learners’skill level navigation *** system initially performs skill level navigation pattern mining to discover frequent skill level navigations in the pOJ and toﬁnd learners’learning ***ﬁltering(CF)and con-tent-basedﬁltering approaches are employed to recommend problems in the cur-rent and next skill levels based on frequent skill level navigation *** sequence similarity measure is used toﬁnd the top k neighbors based on the sequence of problems solved by the *** experiment results based on the real-world pOJ dataset show that our approach considering the learners’cur-rent skill level and learning goals outperforms the other approaches in practice problem recommender systems.

关键词： Recommender systems skill level navigation pattern programming online judge collaborativeﬁltering content-basedﬁltering

numerical solution of generalized DpL model using wavelet method during thermal therapy applications

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International Journal of Biomathematics 2019年第3期12卷 169-190页

作者： p.Kumar K.n.Rai Department of Mathematics H. R. College Amnour (A Constituent Unit of J. P. University) Saran-841401 India Department of Mathematical Sciences IIT (BHU) Varanasi India

In this paper, generalized dual-phase-lag (DpL) model has been studied for the numerical analysis of spatial variation of temperature within living biological tissues during thermal therapy applications. A new hybrid numerical scheme based on finite difference scheme and Chebyshev wavelet Galerkin method are used to solve the generalized DpL model with constant heat flux boundary condition. Multi-resolution and multi-scale computational property of Chebyshev wavelet in the present case localizes small scale variations of solution and fast switching of functional bases. Our study demonstrates that due to presence of coupling factor (convection–perfusion), generalized DpL model predicts lower temperature than classical DpL and pennes model at the tumor position. Higher values of phase lag times results in lower temperature at the tumor position. But, in case of variation of phase lag time due to temperature gradient, the nature of temperature profile also depends on the spatial coordinate. The effect of the blood temperature, porosity and interfacial convective heat transfer on temperature distribution has been investigated. It is found that larger values of porosity and interfacial convective heat transfer results in lower temperature at the tumor position. Also, both porosity and interfacial convective heat transfer are pronounced more at higher values. The whole analysis is presented in dimensionless form.

关键词： Chebyshev wavelet Galerkin method Generalized DpL model nonequilibrium bioheat transfer Thermal therapy

Kronecker product and bat algorithm-based coefficient generation for privacy protection on cloud

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International Journal of Modeling, Simulation, and Scientific Computing 2017年第3期8卷 61-77页

作者： nandkishor p.Karlekar n.Gomathi Vel-Tech Dr.RR&Dr.SR Technical University Chennai Tamil NaduIndia

Due to widespread growth of cloud technology,virtual server accomplished in cloud platform may collect useful data from a client and then jointly disclose the client’s sensitive data without ***,from the perspective of cloud clients,it is very important to take confident technical actions to defend their privacy at client ***,different privacy protection techniques have been presented in the literature for safeguarding the original *** paper presents a technique for privacy preservation of cloud data using Kronecker product and Bat algorithm-based coefficient ***,the proposed privacy preservation method is performed using two important *** the first step,pU coefficient is optimally found out using pUBAT algorithm with new objective *** the second step,input data and pU coefficient is then utilized for finding the privacy protected data for further data publishing in cloud *** the performance analysis,the experimentation is performed with three datasets namely,Cleveland,Switzerland and Hungarian and evaluation is performed using accuracy and *** the outcome,the proposed algorithm obtained the accuracy of 94.28%but the existing algorithm obtained only the 83.64%to prove the *** the other hand,the proposed algorithm obtained DBDR of 35.28%but the existing algorithm obtained only 12.89%to prove the privacy measure.

关键词： Cloud computing privacy preservation data publishing utility accuracy

An accurate modeling of piezoelectric smart beams with first-order shear deformation theory

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International Journal of Modeling, Simulation, and Scientific Computing 2015年第2期6卷 179-197页

作者： Litesh n.Sulbhewar p.Raveendranath Department of Aerospace Engineering Indian Institute of Space Science and Technology Thiruvananthapuram Kerala 695547India

A finite element model for piezoelectric smart beam in extension mode based on First-order Shear Deformation Theory(FSDT)with an appropriate through-thickness distribution of electric potential is *** of piezoelectric finite element formulations depends on the selection of assumed mechanical and electrical *** of the conventional FSDT-based piezoelectric beam formulations available in the literature use linear through-thickness distribution of electric potential which is actually ***,a novel quadratic profile of the through-thickness electric potential is proposed to include the nonlinear *** results obtained show that the accuracy of conventional formulations with linear through-thickness potential approximation is affected by the material configuration,especially when the piezoelectric material dominates the beam cross *** is shown that the present formulation gives the same level of accuracy for all regimes of material configurations in the beam cross ***,a modified form of the FSDT displacements is employed,which utilizes the shear angle as a degree of freedom instead of section *** a FSDT displacement field shows improved performance compared to the conventional *** present formulation is validated by comparing the results with AnSYS 2D *** comparison of results proves the improved efficiency and accuracy of the present formulation over the conventional formulations.

关键词： Actuator and sensor coupled field extension mode finite element piezoelectric smart beams variational formulation