نتایج جستجو برای: thermal properties

تعداد نتایج: 1049095  

ربانی, حسن, مردانی, محمد, کشاورز, مهوش,

In this paper, we study the phonon and thermal properties of a nanocrystal by using transfer matrix method in the harmonic approximation. The considered system is a mass-spring nanocrystal with a square cross section. At first, for the ideal case, we obtain the phonon spectrum with free boundary conditions. Then we calculate some phonon transport properties of this system, namely, the phonon de...

In this paper, the phononic and thermal properties of tungsten disulfide have been studied. The aim of this study was to investigate the phonon and thermal properties such as heat capacity and enthalpy. The calculations are performed within the framework of density functional theory by pseudo-potential methood and by Quantum Espresso computational package and their exchange-correlation function...

Journal: :Nanotechnology 2015
Guillaume Savelli Sergio Silveira Stein Guillaume Bernard-Granger Pascal Faucherand Laurent Montès Stefan Dilhaire Gilles Pernot

Ti-based silicide quantum dot superlattices (QDSLs) are grown by reduced-pressure chemical vapor deposition. They are made of titanium-based silicide nanodots scattered in an n-doped SiGe matrix. This is the first time that such nanostructured materials have been grown in both monocrystalline and polycrystalline QDSLs. We studied their crystallographic structures and chemical properties, as wel...

Abstract: Refractory materials containing cordierite (2MgO.2Al2O3.5SiO2) and mullite (3Al2O3.2SiO2) are used as support in furnaces, because of their low thermal expansion properties which confer them a very good ability to thermal shock resistance. Composed of two phases presenting very different CTE (1.5–3×10-6 for cordierite and 4–6×10-6 K-1 for mullite), these materials can develop damag...

تشه, محمدرشاد, داودی , جمال,

 The aim of this investigation was to calculate the thermal properties of silver crystal in the presence of linear imperfection. The simulations were performed by molecular dynamics simulation technique in NPT as well as NVT ensemble based on quantum Sutton-Chen many body potential. The thermal properties including cohesive energy, melting temperature, isobaric heat capacity and thermal expansi...

The thermo-optical properties of coated surface are important for spacecraft thermal control coatings which depend on the optical properties and structure of the coating material. These coatings control the temperature by their capability of outer energy absorption and its emission. The optical properties of pigment can be improved if the pigment contains a high fraction of voids in its structu...

B. Ezzati, F. Hamedi Rad, T Ghafari,

  Objective: Studies have demonstrates that physical properties of denture base affect patient satisfaction and acceptance. Thermal conductivity is among the most important properties of denture base influencing the sense of taste and gingival health. The conventionally used acrylic resin has a low coefficient of thermal conductivity. This study aimed to improve the thermal conductivity of acry...

Abstract. Cubic crystalline oxides such as Y2O3 and MgO is used to stabalized zirconia phases at high temperature. In this paper the Y2O3 powder was added to stabilized zirconia and preparing a mixture of MgAl2O4 Spinel by mixing 1mol of nano-MgO with 1 mol of nano-Al2O3 powders. The spinel was added to the Y2O3-ZrO2 by various weight percentage (5, 10, 15, 20 and 25 wt%), and after that the sp...

  In this study, a new method for joining aluminum tubes in subsurface structures using steel converting and aluminum welding are presented and reviewed. But near the weld area is under high thermal cycle and will cause residual stresses in heat affected zone. Therefore for assessment of proposed connection from the perspective of residual stress by using the finite element method welding of tu...

Journal: :iranian journal of oil & gas science and technology 2012
mostafa sedaghatzadeh abbasali khodadadi mohammad reza tahmasebi birgani

designing drilling fluids for drilling in deep gas reservoirs and geothermal wells is a majorchallenge. cooling drilling fluids and preparing stable mud with high thermal conductivity are ofgreat concern. drilling nanofluids, i.e. a low fraction of carbon nanotube (cnt) well dispersed inmud, may enhance the mixture thermal conductivity compared to the base fluids. thus, they arepotentially usef...

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