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Generalized Bleustein-Gulyaev type waves in layered porous piezoceramic structure

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Applied Mathematics and Mechanics(English Edition) 2015年第9期36卷 1223-1242页

作者： A.k.vASHISHTH A.DAHIYA v.GUPTA Department of Mathematics Kurukshetra University

The propagation of a Bleustein-Gulyaev （B-G） type wave in a structure consisting of multiple layers and a half-space of porous piezoelectric materials is theoreti- cally studied. The solutions of the problem in terms of the mechanical displacements and electric potential functions are obtained for each layer and the half-space. The dispersion equation is obtained for electrically open and shorted boundary conditions by use of the transfer matrix method. A peculiar kind of B-G waves is investigated, which can propagate only in the layer over the half-space. The relationship between the piezoelectric constants and the dielectric constants is found for the existence of a peculiar kind of propagation modes. The numerical results in terms of the phase velocity and the electromechanical coupling factor with different thicknesses of the layer stack are presented.

关键词： Bleustein-Gulyaev (B-G) type wave electro-mechanical coupling porouspiezoceramic transfer matrix

Influence of preparation route and slip casting conditions on titania and barium titanate ceramics

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Particuology 2012年第3期10卷 371-383页

作者： Arvind k. Nikumbh Parag v. Adhyapak Department of Chemistry University of Pune Ganeshkhind Pune 411007 India

Titania （TiO2） and barium titanate （BaTiO3） were synthesized using three different dicarboxylates, which included oxalate, malate and tartarate. These powders were characterized by X-ray powder diffraction, scanning electron micrographs, BET specific surface area and particle size distribution. Their properties depended to a great extent on the nature of the precursor. The titania and barium titanate powders obtained from the tartarate precursor were found to be good for slip casting. Slips of these oxides with different solids contents were prepared at different pH values using both distilled water and ethanol as the dispersing agent and also with and without deflocculant. The theological behaviors of the suspensions were then determined, and the slip, green and sedimentation bulk densities were measured. The minimum viscosities were observed at pH 8.2 for the TiO2-water and pH 10.2 for the BaTiO3-water system.

关键词： Ceramics TiO2 BaTiO3 Chemical synthesis Thermogravimetric analysis (TGA)X-ray diffraction

Performance of inclined pillars with a major discontinuity

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International Journal of Mining Science and Technology 2019年第3期29卷 437-443页

作者： k.v.Jessu A.J.S.Spearing Western Australia School of Mines kalgoorlie Curtin University

Discontinuities are an inherent part of the rock mass and majorly affect the stability of the excavation skin and *** dip of the discontinuities and their properties also have a significant effect on the strength of the *** approaches are commonly used to determine the pillar strength but can overestimate the strength and don’t consider the inclination of the pillars and the strength reduction caused by *** modeling is a powerful tool and if calibrated can be used to evaluate the strength of the pillars with discontinuities having a range of *** effect of a discontinuity on inclined pillars was conducted which has been seldom considered in evaluating the pillar ***-dimensional vertical pillars were simulated,and the pillar strength was calibrated to accepted theoretical results and then the discontinuities were introduced in different pillar inclinations with distinct width to height ratios to gain an insight into the effective pillar strength *** upon the results,it was found that the discontinuities have a significant effect with the increase in the inclination of the pillars even at a higher width to height ratios.

关键词： Numerical modelling Pillar Discontinuities Inclination Width to height ratios

Influence of ligand architecture on the structure of coordination centre in dimeric europium carboxylates with 1,10-phenanthroline

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Journal of Rare Earths 2009年第4期27卷 539-543页

作者： v.Tsaryuk k.Lyssenko k.Zhuravlev v.Zolin v.kudryashova I.Pekareva Z.klemenkova Laboratory of Molecular Electronics V.A.Kotelnikov Institute of Radioengineering and Electronics Russian Academy of Sciences 1 Vvedenskii sq. Fryazino Moscow Reg. 141190 Russia A.N.Nesmeyanov Institute of Organoelement Compounds Russian Academy of Sciences 28 Vavilov st. Moscow 119991 Russia

Methods of optical spectroscopy and X-ray crystallography data were used to examine the effect of architecture of carboxylate anions on structure of the Eu3＋ coordination centre in europium earboxylates with 1,10-phenanthroline Eu（RCOO）3·Phen. Luminescence spectra of europium acetate, nitropropionate, benzoate, naphthylcarboxylates, phenylacetates, phenoxyacetate, triphenylpropionate were investigated. A few of europium carboxylates with 2,2＇-bipyridine Eu（RCOO）3·Bpy and europium salts Eu（RCOO）3·nH2O were also studied. vibrational IR and Raman spectra of phenylacetate family were analyzed. The crystal structure of nitropropionate Eu（NO2C2H4COO）3·Phen was solved by X-my diffraction method. The predominant influence of steric hindrances on Eu^3＋ coordination centre was observed at increase of the size of aromatic flagment of carboxylate anions. It was demonstrated, that introduction of the methylene bridges between the carboxylic group and aromatic rings of ligand weakens the effect of steric factor.

关键词： Eu^3+ luminescence spectra vibrational spectra X-ray crystal structure carboxylate 1,10-phenanthroline rare earths

Microstructure and phase elemental distribution in high-boron multicomponent cast irons

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International Journal of Minerals,Metallurgy and Materials 2022年第1期29卷 78-87页

作者： Yu.G.Chabak k.Shimizu v.G.Efremenko M.A.Golinskyi k.kusumoto v.I.Zurnadzhy A.v.Efremenko Physics Department Pryazovskyi State Technical UniversityMariupol87555Ukraine Mechanical Engineering Research Unit College of Design and Manufacturing TechnologyMuroran Institute of TechnologyMuroran-city050-8585Japan

The novel cast irons of chemical composition(wt%)0.7C-5W-5Mo-5v-10Cr-2.5Ti were invented with the additions of 1.6wt%B and 2.7wt%*** aim of this work was to study the effect of boron on the structural state of the alloys and phase elemental distribution with respect to the formation of wear-resistant structural *** was found that the alloy containing 1.6wt%B was composed of three eutectics:(a)“M_(2)(C,B)_(5)+ferrite”having a“Chinese Script”morphology(89.8vol%),(b)“M_(7)(C,B)_(3)+Austenite”having a“Rosette”morphology,and(c)“M_(3)C+Austenite”having a“Ledeburite”-shaped morphology(2.7vol%).With 2.7wt%of boron content,the bulk hardness increased from HRC 31 to HRC *** primary carboborides M_(2)(C,B)_(5) with average microhardness of Hv 2797 appeared in the structure with a volume fraction of 17.6vol%.The volume fraction of eutectics(a)and(b,c)decreased to 71.2vol%and 3.9vol%,*** matrix was“ferrite/austenite”for 1.6wt%B and“ferrite/pearlite”for 2.7wt%*** cast irons contained compact precipitates of carbide(Ti,M)C and carboboride(Ti,M)(C,В)with a volume fraction of 7.3%-7.5%.Based on the energy-dispersive X-ray spectroscopy,the elemental phase distributions and the appropriate phase formulas are presented in this work.

关键词： multi-component cast iron boron eutectic carbide carboboride

Densities and excess molar volumes of mixtures containing diesel,biodiesel and alkanols at temperatures from 288.15 to 313.15 k

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Chinese Journal of Chemical Engineering 2021年第6期34卷 198-207页

作者： Sunita Malik Poonam Jangra Darolia S.k.Garg v.k.Sharma Department of Chemistry Maharshi Dayanand UniversityRohtakHaryanaIndia J.C.Bose University of Science and Technology YMCAFaridabadHaryanaIndia

The present work is focusing on the synthesization and physico-chemical properties of Jatropha curcas biodiesel with diesel and *** densities of binary diesel(2)+1-alkanols(C_(3) or C_(4))(3)and ternary Jatropha curcas biodiesel(1)+diesel(2)+1-alkanols(C_(3)or C_(4))(3)blends have been reported over full range of composition at temperatures within range 288.15 to 313.15 *** densities of Jatropha curcas biodiesel(1)+diesel or 1-alkanols(C_(3) or C_(4))(2)blends have been measured at 313.15 *** molar volumes,v^E,v^E_(123)of binary and ternary blends were calculated from the measured data and the derived properties were correlated to composition using Redlich-kister equation.A reasonable agreement was found between the measured and estimated ***,densities and excess molar volumes data were reasoned to discuss molecular interactions taking into consideration effect of composition and temperature.

关键词： Jatropha curcas biodiesel Diesel Alcohols Blends Density Excess molar volumes

Characterization of mixing in an optimized designed T–T mixer with cylindrical elements

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Chinese Journal of Chemical Engineering 2019年第10期27卷 2337-2351页

作者： T.Manoj Dundi v.R.k.Raju v.P.Chandramohan Mechanical Engineering Department National Institute of TechnologyWarangalTelangana StateIndia

Passive micromixers are preferred over active mixers for many microfluidic applications due to their relative ease in integration into complex systems and operational *** also incur very low cost of ***,the degree of mixing is comparatively low in passive mixers than active mixers due to the absence of disturbance in the flow by external forces and the inherent laminar nature of microchannel *** designs of complex channel structures and three-dimensional geometries have been investigated in the past to obtain an efficient mixing in passive *** the studies on mixing enhancement with simple planar geometries of passive mixers have been few and *** present work aims to investigate the possibility of mixing enhancement by employing simple planar type designs,such as T-mixer and T–T mixer with cylindrical elements placed in the mixing *** mixing performance has been evaluated in the Reynolds number range of 6 *** results have shown that T–T mixer with cylindrical elements performed significantly well and obtained very good mixing quality over basic T-mixer for the entire range of Reynolds number(6 to 700).The device has also shown better mixing as compared to basic T–T mixer and T-mixer with cylindrical elements.A larger pair of vortices formed in the stagnation area due to the presence of a cylindrical element in the *** elements downstream caused significant enhancement in mixing due to splitting and recombining *** size of the cylindrical element in the T–T mixer has been optimized to obtain better mixing performance of the *** improvement in mixing quality by T–T mixer with cylindrical elements has been obtained at the expense of small rise in pressure drop as compared to other passive designs considered in this ***,the current design of T–T mixer with cylindrical elements can act as an effective and simple passive mixing device for various mi

关键词： CFD-simulation Cylindrical elements Micromixers Mixing quality Obstructions T–T-mixer

Ignition Process Evolution at High Supersonic velocities in Channel

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Journal of Thermal Science 2009年第2期18卷 166-172页

作者： M.A.Goldfeldl A.v.Starov k.Yu.Timofeev v.A.vinogradov Institute of Theoretical and Applied Mechanics Central Institute of Aviation Motors

The results of experimental research of multi-injector combustors in the regime of the attached pipe are *** a source of high-enthalpy working gas (air), hot shot wind tunnel IT-302M of ITAM, the Siberian Branch ofthe Russian Academy of Sciences was used. Tests have been carried out at Mach numbers 3,4 and 5, in a range ofchange of total temperature from 2000k up to 3000k and static pressure from 0.08MPa up to 0.23MPa. Injectorsection has been manufactured in two versions with a various relative height of wedge-shaped injectors with parallelfuel injection. Influence of conditions on the entrance of the combustion chamber on ignition and a stablecombustion of hydrogen was investigated. Intensive combustion of hydrogen has been received only at Machnumbers 3 and 4. Advantage of injector section with the greater relative height of injectors is revealed. Themechanism of fuel ignition in the combustion chamber of the given configuration was investigated: two-step ignitionprocess including 'kindling' and intensive combustion over all channel volume.

关键词： supersonic combustor ignition stable combustion.

Growth of 4＂ diameter polycrystailine diamond wafers with high thermal conductivity by 915 MHz microwave plasma chemical vapor deposition

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Plasma Science and Technology 2017年第3期19卷 93-97页

作者： A F POPOvICH v G RALCHENkO v k BALLA A k MALLIk A A kHOMICH A P BOLSHAkOv D N SOvYk E E ASHkINAZI v Yu YUROv Institute of Radio Engineering and Electronics of Russian Academy of Sciences Fryazino 141190 Russia General Physics Institute of Russian Academy of Sciences Moscow 119991 Russia Harbin Institute of Technology Harbin 150001 People's Republic of China National Research Nuclear University MEPhI Moscow 115409 Russia Central Glass and Ceramic Research Institute Kolkata 700 032 India

Polycrystalline diamond（PCD） films 100 mm in diameter are grown by 915 MHz microwave plasma chemical vapor deposition（MPCvD） at different process parameters,and their thermal conductivity（TC） is evaluated by a laser flash technique（LFT） in the temperature range of230-380 *** phase purity and quality of the films are assessed by micro-Raman spectroscopy based on the diamond Raman peak width and the amorphous carbon（a-C） presence in the *** and increasing dependencies for TC with temperature are found for high and low quality samples,***,as high as 1950 ± 230 W m-1 k-1 at room temperature,is measured for the most perfect material.A linear correlation between the TC at room temperature and the fraction of the diamond component in the Raman spectrum for the films is established.

关键词： thermal conductivity polycrystalline diamond microwave plasma chemical vapordeposition Raman spectroscopy