493 Works

DEHYDROGENATION OF A CRUMPLED GRAPHENE FLAKE: MOLECULAR DYNAMICS

N.G. Apkadirova, K.A. Krylova & R.R. Mulyukov
С помощью молекулярно-динамического моделирования рассмотрен процесс дегидрирования смятой чешуйки графена во время отжига при 77, 100, 150, 200, 250 и 300 К в течение 200 пс. Установлено, что отжиг при Т = 77 К в течение первых 50 пс не влияет на гравиметрическую плотность. Дальнейшая выдержка при этой температуре приводит к резкому снижению гравиметрической плотности до 7,6 вес.%. Установлено, что чем выше температура, тем быстрее идет процесс дегидрирования углеродной структуры. При температурах отжига выше 150...

The role of lead oxide in PbO-B2O3 glasses for solid state ionic devices

Gurinder Pal Singh, Joga Singh, Parvinder Kaur, Taminder Singh, Ravneet Kaur & D.P. Singh
Lead Borate Glasses (mole fraction of lead x=0.20-0.50 %) has been synthesized in laboratory with the help of conventional melt quenching technique. The confirmation of glassy state of prepared glasses is done by X-ray diffraction study. The physical properties, for instance, density and molar volume are determined to find the structural changes of glasses network. Density of these glass samples increases with enhancement in lead oxide content whereas molar volume shows an initial decrease and...

Optimization of powder metallurgy process parameters to recycle AZ91 magnesium alloy

N. Kumar & A. Bharti
A global increase in the demand for magnesium and its alloys has put increased pressure on magnesium's natural sources (magnesium ores) due to its high strength to weight ratio and environment-friendly nature. Therefore, it has become necessary to look for efficient recycling techniques for magnesium and its alloys. Powder metallurgy proved to be very efficient compared to conventional recycling techniques for the recycling of aluminum, copper, and other alloys. In the present work, an experimental...

IMPACTS OF COUPLE STRESS ON S-WAVES IN A PRE-STRESSED ANISOTROPIC SANDY MEDIUM

S. Selvi & L. Anitha
The effect of initial stress, dry sand with couple stress on shear wave propagation in an inhomogeneous, anisotropic, thinly layered laminated medium is studied. The shear wave velocity for the particular problem has been obtained. The derived velocity expression has been computed numerically for specific rigidity parameter, density parameter, initial stress parameter, anisotropic factor, sand parameter, couple stress parameter as well as wave number, and the outcomes are shown graphically.

RESULTS OF THE SURFACE MORPHOLOGY STUDY OF ELASTIC SELF-ADHESIVE RADIATION SHIELDING COATINGS BY ATOMIC FORCE MICROSCOPY

M.E. Buzoverya, Yu.P. Scherbak, V.D. Cherkasov, Yu.V. Yurkin, V.V. Avdonin, D.L. Suntsov & V.O. Pilshchikov
An algorithm for studying the structure of radiation shielding materials using the atomic force microscopy (AFM) method has been developed and described. Using the proposed method, the structure of tungsten-containing radiation shielding materials was studied and the difference in the microstructure of the samples and the nature of the distribution of the filler was revealed.

ASYMPTOTICAL REGIMES OF THE HYDROFRACTURING PLANAR 3D MODEL

E.V. Shel
In the proposed paper the Planar 3D model of hydraulic fracturing was investigated. All of the hydraulic fracturing equations were substituted into the mass conservation law and scaled. Nontrivial dimensionless parameters of the problem were found. Asymptotic regimes of the equation, the Radial or the Pseudo3D model, correspond to the infinitely small or the infinitely large dimensionless parameters. Thus, the limiting conditions of these models were found in the terms of the dimensionless parameters.

Ballistic response and induced damage of plain and reinforced concrete plates

Kamran Kamran & M.A. Iqbal
The present study shows the comparison of ballistic response and induced damages of plain and reinforced concrete plates subjected to the normal impact of ogive-nosed steel projectiles. The evaluation of damage has been described by the presence of cracking and measuring the size of the crater in terms of equivalent diameter, formed at front and rear concrete surfaces. The ballistic limits of plain and reinforced concrete have been obtained through the varied projectile velocities. The...

Evolution of the cylindrical nanopore morphology under diffusion processes

A.B. Vakaeva , G.M. Shuvalov & S.A. Kostyrko
In the present paper, we provide a theoretical approach to the analysis of nanopore morphological stability under diffusion taking into account surface elasticity. It is assumed that the pore shape may change during stress relaxation. The surface atomic flux is caused by the nonuniform distribution of chemical potential, which depends on bulk and surface stresses as well as pore surface curvature. The change in surface relief is described by the linearized evolution equation, which is...

Deformation instability in crystalline alloys: Luders bands

G.F. Sarafanov & Yu.G. Shondin
A mechanism of localization of plastic deformation at high temperatures is investigated in the framework of the autowave model. A model of the formation and propagation of Luders bands is proposed. It is established that a Luders band is a wavefront of the plastic deformation rate. From this article's point of view, the conditions for the formation of a Luders band are decisive for the interpretation of the fluidity serration. The critical value of the...

STUDY OF STRUCTURAL AND OPTICAL PROPERTIES OF IRON, COBALT DOPED AND IRON-COBALT CO-DOPED TIN DIOXIDE SnO2

K. Chedala, A. Benhaoua, R. Gheriani, A. Hima & L. Ayachi
In this paper is studied undoped tin dioxide (SnO2), iron doped tin dioxide (FeTO), cobalt doped tin dioxide (CTO), and iron-cobalt co-doped tin dioxide (FeCTO) thin films using spray pyrolysis technique at a temperature of 480°C heated glass. The dopant concentration value was 12wt %. Whilst, The structural and optical characteristics of fabricated thin films were studied. XRD analyses avowed the formation of rutile thin films structure along (211) and (110) as preferred orientations. The...

MICROSTRUCTURE CHARACTERIZATION OF WELD CONSUAMBLE CONDITION ON RESIDUAL STRESS, FLEXURAL STRENGTH AND ROOM TEMPERATURE TENSILE TESTS of P92 STEEL

V.K. Pal & L.P. Singh
The present manuscript describes the flexural strength, lower critical stress, and tensile stress of P92 steel welds was determined with respect to different conditions. The residual stresses axial and transverse stress were also measured blind hole drilling methods for the different conditions of welding consumables. The peak value of residual stresses was measured at the centre of the fusion zone. The maximum value of transverse stress was measured to be 355 MPa for case IV...

MECHANICAL PROPERTIES OF MARBLE DUST REINFORCED ALUMINUM MATRIX STRUCTURAL COMPOSITES FABRICATED BY STIR CASTING PROCESS

Sandeep Kashyap, Velaphi Msomi & Naveen Kumar
The use of aluminium and its alloys in aerospace, transportation, automobile and power transmission is growing these days because it has good corrosion resistance, is lightweight, and has a high specific strength. But aluminium and its alloys have some drawbacks, such as low absolute strength at higher temperatures, low impact resistance, low hardness, etc. In this research, the aluminium metal matrix composite has been manufactured with the help of the stir casting technique to improve...

Stability analysis of nanoscale surface patterns in ultrathin film coating

Gleb Shuvalov & Sergey Kostyrko
This paper presents a theoretical approach to the analysis of ultrathin film morphological stability under surface diffusion. Based on the simplified Gurtin–Murdoch model the surface elasticity has been taking into account. Due to the lattices mismatch, the film structure is subjected to misfit stress. It is assumed that the free surface can change the shape via mass transfer in order to minimize the total energy. Surface diffusion is considered as the main mechanism leading to...

Laser-induced photoacoustic characterization on thermal diffusivity of chitosan and sago starch biocomposite blend films

Junjie Chen
The photoacoustic(PA) technique has been testified to be versatile and also reliable for measuring the thermal properties of most materials. For example, it has been utilized to verify the thermal diffusivity of semiconductors, polymers, superconductor, metal and glass. In this study, the thermal diffusivity of the sago starch and chitosan polymer blend films was characterized using the laser-induced photoacoustic technique. It is based upon the theoretical analysis on the measured photoacoustic signal as a function...

Ab initio calculations of electronic band structure of ideal and defective CdMnS

Matanat Mehrabova, Natig Panahov & Niyazi Hasanov
The purpose of this work was to calculate the electronic band structure of ideal and defective Cd1-xMnxS. Ab initio, calculations are performed in the Atomistix Toolkit program within the Density Functional Theory and Local Spin Density Approximation on Double Zeta Double Polarized basis. We have used Hubbard U potential UMn = 3.59 eV for 3d states for Mn atoms. Supercells of 8 and 64 atoms were constructed. After the construction of Cd1-xMnxS (x = 6.25%;...

A study on mechanical and dielectric properties of B4C and Al dispersed single-layered epoxy-based polymer composites fabricated through molding and curing route

Vignesh Sreekandan Nair, Winowlin Jappes J T, S. Nagaveena, K. Sankaranarayanan, R. Krishna Sharma & N.C. Brintha
The work aims in developing epoxy composites with different compositions of boron carbide (5, 10, 15, and 20 wt.%) added with aluminium (10 wt %) for studying the mechanical and dielectric behavior. It was found that the tensile strength of the samples initially increased with an increase in reinforcements and then decreased with an increase in B4C content beyond 10 wt. %. Flexural strength, on the other hand, increased with the addition of B4C particles....

Comparison of mechanical strain measurement accuracy of fiber-optic sensor and smart-layer

Глеб Шипунов, Максим Баранов, Александр Никифоров & F.R. Khabibrakhmanova
Due to its fragility, fiber optic sensor (FOS) embedded into constructions made of carbon fiber reinforced polymer, can be broken both while it is manufacturing at the point of embedding into construction, and during its operation. This can lead to the inability to further monitoring of the construction strains. Usage of a specific thin Smart-layer for protection of FOS is proposed by the authors. For the Smart-layer manufacturing, 3D printing technology was used. The spectra...

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