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considerations for effective ground support in evaporites

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International journal of Mining Science and Technology 2019年第1期29卷 113-118页

作者： j.R.Nopola c.A.Vining RESPEc

Evaporites, such as salt and potash, pose unique problems to ground-support designs that are not encountered in other rock types. Evaporites are subject to continual creep and no amount of ground support can successfully arrest this process. common ground-support techniques that are useful for most rock types may reduce the effective life of bolts in evaporite mines and create unseen hazards. A different approach to ground support must be applied to provide long-term support in areas where high creep rates are present. The goal of effective ground-support designs in these situations is not to contain and prevent the rock from moving; rather, the ground-support design must be able to move along with the rock and contain any fully detached slabs until additional remediation measures can be *** most appropriate ground-support designs will consider the expected movement of the rock and the duration that the area needs to remain accessible.

关键词： Ground support Ground control Rock mechanics And salt mechanics

P-type SnO thin films prepared by reactive sputtering at high deposition rates

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journal of Materials Science & Technology 2019年第8期35卷 1706-1711页

作者： c.Guillén j.Herrero Department of Energy CIEMATAvda. Complutense 40Edif. 42Madrid28040Spain

SnO is an ideally suitable p-type conductive material, with large hole mobility, and has attracted great interest in connection with next-generation electronic applications. In the present work, tin oxide(SnOx)thin films were deposited on unheated soda lime glass substrates by reactive Dc sputtering from a pure Sn target. The structural, optical and electrical properties of the films were analysed as a function of the oxygen partial pressure in the sputtering atmosphere and of the post-deposition annealing temperature in air. A structural analysis was carried out using Raman spectroscopy and X-ray diffraction. Optical and electrical characterizations were performed using photo-spectrometry and Hall effect measurements,respectively. The films grown at room temperature and low oxygen pressures reached high deposition rates of above 45 nm/min, showing poorly crystalline SnO and low transparency. Subsequent heating to 350℃ allowed to achieve a more crystalline tetragonal SnO with an average visible transmittance of 65%,a p-type conductivity of 0.8 S/cm, and a hole mobility of 3.5 cm^2/(V s).

关键词： Transparent conducting oxide (TcO) Nanocrystalline structure Optical absorption Hole mobility

Enhancement of Sinter Densification of SrO-BaO-Nb_2O_5-SiO_2 Tungsten-Bronze Glass-ceramics by Doping with P_2O_5

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journal of Materials Science & Technology 2013年第8期29卷 731-736页

作者： j.c.chen Y.Zhang Shenyang Research and Development centre for Advanced Materials Institute of Metal ResearchChinese Academy of Sciences State Key Laboratory of New ceramics and Fine Processing Institute of Nuclear and New Energy TechnologyTsinghua University

Densification behaviors of SrO-BaO-Nb2O5-SiO2 based glass-ceramics prepared by conventional sintering were investigated with an emphasis on the influence of P2O5 content. Although P2O5 dopant did not modify the surface crystallization mechanism, it resulted in a decrease of the glass transition temperature, which facilitates the viscous glass flow necessary for sintering. However, premature crystallization of （Sr, Ba）Nb2O6 induced by addition of excess amount of P2O5 essentially retarded sintering due to the formation of closed pores in the matrix. The SrO-BaO-Nb2O5-SiO2 glass with 1.0 mol% P2O5 （SBN-1P） showed the best sinter densification, which was accomplished at about 850 ℃.

关键词： Sintering densification DieLectric properties Glass-ceramic

Gamma Irradiation Effects in InBi_(0.8) Te_(0.2) crystals Grown by Horizontal Directional Freezing

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Acta Metallurgica Sinica(English Letters) 2015年第10期28卷 1205-1213页

作者： c.j.Ajayakumar A.G.Kunjomana Department of Physics Crystal Research CentreChrist University

The high-energy gamma-ray irradiation treatment using co-60 isotope offers the possibility of engineering mechanical and optoelectronic properties of In Bi0.8Te0.2crystals. Tellurium-doped indium bismuthide（In Bi） crystals were prepared by horizontal directional freezing technique. Dose-dependent modifications in structure, composition and surface topographical features have been analyzed by X-ray powder diffraction, X-ray energy-dispersive analysis, transmission electron and atomic force microscopy, respectively. Dielectric constant and dielectric loss were found to increase with the cumulative dose of radiation, and a shift in the ferroelectric transition temperature（Tc） from 405 to 410 K was observed for25 k Gy. Upon irradiation, there is an enhancement in microhardness（HV）, yield stress（ry） and stiffness constant（c11）.The optical transmittance was decreased by 12.45%, resulting in a reduction in the optical band gap from 0.210 e V to0.198 e V. These results indicate the suitability of In Bi0.8Sb0.2crystals for low-wavelength infrared applications.

关键词： crystal growth Dielectric properties Optical properties Hardness Irradiation

Influence of Te doping on the dielectric and optical properties of InBi crystals grown by directional freezing

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International journal of Minerals,Metallurgy and Materials 2014年第5期21卷 503-509页

作者： c.j. Ajayakumar A.G. Kunjomana crystal Research centre Department of PhysicsChrist University

Stoichiometric pure and tellurium （Te） doped indium bismuthide （InBi） were grown using the directional freezing technique in a fabricated furnace. The X-ray diffraction profiles identified the crystallinity and phase composition. The surface topographical features were observed by scanning electron microscopy and atomic force microscopy. The energy dispersive analysis by X-rays was performed to identify the atomic proportion of elements. Studies on the temperature dependence of dielectric constant （e）, loss tangent （tan6）, and Ac conductivity （cry） reveal the existence of a ferroelectric phase transition in the doped material at 403 K. When InBi is doped with tellurium （4.04 at%）, a band gap of 0.20 eV can be achieved, and this is confirmed using Fourier transform infrared studies. The results thus show the conversion of semimetallic InBi to a semiconductor with the optical properties suitable for use in infrared detectors.

关键词： crystals indium bismuthide tellurium doping optical properties dielectric properties phase transitions

Flow characteristics in a parallel-plate porous channel under convective boundary conditions and triple diffusion for the non-Darcy porous matrix

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Propulsion and Power Research 2021年第4期10卷 396-411页

作者： j.c.Umavathi Department of Mathematics Gulbarga UniversityGulbarga585106KarnatakaIndia

This article inspects the effect of triple diffusion in a vertical conduit encapsulated with porous matrix and subjected to third kind boundary *** kind boundary condition is a combination of Dirichlet and Neumann boundary conditions which specifies a linear combination of function and its derivative values on the *** chemical reaction along with viscous and Darcy dissipation effects are *** the Boussinesq approximation,the soultal buoyancy effects due to concentration gradients of the dispersed components are taken into *** suitable transformations,the conservation equations are reduced into dimensionless form and the dimensionless parameters evolved are thermal Grashof number (0≤Λ_(1)≤20),solutal Grashof number(for species 1 and 2,0≤Λ_(2);Λ_(3)≤20),porous (2≤σ≤8) and inertial parameters (0≤Ι≤6),Biot numbers(at the left and right walls,1≤Bi_(1);Bi_(2)≤10),Brinkman number (0≤Br≤1),Schmidt numbers (0≤Sc_(1);Sc_(2)≤6),Soret numbers (Sr_(1) =Sr_(2) =1) and temperature difference ratio (R_(T) = 1).Adopting perturbation technique,the analytical solutions which are applicable only when the Brinkman number is less than one is *** for any values of the Brinkman number,Runge-Kutta shooting method is *** impact of selected parameters on the momentum,heat and dual species concentration fields are presented in the form of *** solutions computed by numerical method are justified by comparing with the analytical *** numerical and analytical solutions are equal in the absence of Darcy and viscous dissipations and the discrepancy advances as the Brinkman number *** the solutions obtained are also justified by comparing the results with Zanchini[1]in the absence of chemical reaction for clear *** thermal field is augmented with the Brinkman number for symmetric and asymmetric Biot *** the profiles are highly distinct at the cold plate for unequal Biot numbers

关键词： Mixed convection Robin boundary conditions Darcy-Forchheimer-Brinkman model Soret number Runge-Kutta shooting method

State of the Art on Micromilling of Materials,a Review

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journal of Materials Science & Technology 2012年第8期28卷 673-685页

作者： M.A.cmara j.c. campos Rubio A.M. Abro j.P. Davim Department of Mechanical Engineering Universidade Federal de Minas GeraisAv.Ant onio Carlos6627-Pampulha Belo Horizonte MGCEP:31.270-901Brazil Department of Mechanical Engineering University of AveiroCampus Universitrio de Santiago3810-193AveiroPortugal

The trend towards miniaturization has increased dramatically over the last decade, especially within the fields concerned with bioengineering, microelectronics, and aerospace. Micromillin8 is among the principal manu- facturing processes which have allowed the development of components possessing micrometric dimensions, being used to the manufacture of both forming tools and the final product. The aim of this work is to present the principal aspects related to this technology, with emphasis on the work material requirements, tool ma- terials and geometry, cutting forces and temperature, quality of the finished product, process modelling and monitoring and machine tool requirements. It can be noticed that size effect possesses a relevant role with regard to the selection of both work material （grain size） and tooling （edge radius）. Low forces and temper- ature are recorded during micromillin8, however, the specific cutting force may reach high values because of the ploughing effect observed as the uncut chip thickness is reduced. Finally, burr formation is the principal concern with regard to the quality of the finished part.

关键词： Micro-milling Micromachining Size effect Miniaturization

Effect of Solute contents of Al-Ni-Sr Alloy on Glass Forming Ability and Thermal Stability

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journal of Rare Earths 2004年第z2期22卷 73-77页

作者： Taek Soo Kim j K Lee H j Kim j c Bae Advanced Materials R&D center Korea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea

Glass forming ability (GFA) and structural characterization of a new amorphous Al-Ni-Sr alloy melt spun were investigated on the theory of the factors for the glass formation. The GFA was varied with the ratio of Ni to Sr in detail and successful amorphous phase dispersed with 2 ～ 5 nm precipitates was prepared from Al-Ni5-Sr3. Thermal stability and crystallization behavior of the amorphous phase were determined by continuous and isothermal heating technique on DcS, resulting that the crystallization occurs by the growth of fcc Al nanocrystals on the preexistent nuclei.

关键词： glass formation crystallization Al base amorphous alloys rapid solidification

Non-polynomial Zig-Zag and ESL shear deformation theory to study advanced composites

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chinese journal of Aeronautics 2019年第4期32卷 906-920页

作者： j.L.MANTARI I.A.RAMOS j.c.MONGE Faculty of Mechanical Engineering Instituto de investigación en ingeniería naval(IDIIN)National University of Engineering(UNI)Lima 15333Peru Department of Mechanical Engineering University of New Mexico Faculty of Mechanical Engineering Universidad de Ingeniería y Tecnología(UTEC)

The mechanical behavior of advanced composites can be modeled mathematically through unknown variables and Shear Strain Thickness Functions(SSTFs). Such SSTFs can be of polynomial or non-polynomial nature and some parameters of non-polynomial SSTFs can be optimized to get optimal results. In this paper, these parameters are called ‘‘r" and ‘‘s" and they are the argument of the trigonometric SSTFs introduced within the carrera Unified Formulation(cUF). The Equivalent Single Layer(ESL) governing equations are obtained by employing the Principle of Virtual Displacement(PVD) and are solved using Navier method solution. Furthermore, trigonometric expansion with Murakami theory was implemented in order to reproduce the Zig-Zag effects which are important for multilayer structures. Several combinations of optimization parameters are evaluated and selected by different criteria of average error. Results of the present unified trigonometrical theory with cUF bases confirm that it is possible to improve the stress and displacement results through the thickness distribution of models with reduced unknown variables. Since the idea is to find a theory with reduced numbers of unknowns, the present method appears to be an appropriate technique to select a simple model. However these optimization parameters depend on the plate geometry and the order of expansion or unknown variables. So, the topic deserves further research.

关键词： Analytical solution composite materials cUF ESL Plate Trigonometric functions Zig-Zag effects