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Comparison of temperature dependence of internal damping of selected magnesium alloys

Abstract

The research is focused on the study of the temperature dependence of the internal damping of selected magnesium alloys with different contents of aluminium - AZ31 and AZ61. These alloys are currently widely used in various types of industry, mainly in the automotive industry. It belongs to a group of materials called HIDAMETS because they have excellent damping properties. The internal damping of the samples was measured on a unique ultrasonic device constructed at Žilina University in Žilina. Specimens were measured at baseline in the temperature range from 25 °C to 400 °C. Changes in internal damping caused by varying aluminium contents in investigated alloys were noted. As the aluminium content increases, maximum internal damping is achieved due to the formation, growth and subsequent dissolution of the continuous precipitate in the microstructure.

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Accurate Model for Temperature Dependence of Solar Cell Performance According to Phonon Energy Correction

). Measurements and modelling of III-V solar cells at high temperatures up to 400°C. 2017 IEEE 44th Photovoltaic Specialist Conference (PVSC) , 1–14. 9. Singh, P., & Ravindra, N. (2012). Temperature dependence of solar cell performance-an analysis. Solar Energy Materials & Solar Cells , 101 , 36–45. 10. Tamrakar, V., Gupta, S., & Sawle, Y. (2015). Single-diode PV cell modeling and study of characteristics of single and two-diode equivalent circuit. Electrical and Electronics Engineering: An International Journal , 4 (3), 13–24. 11. Schubert, E. (2006

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Temperature dependence of the energy band gap of CuSi2P3 semiconductor using PSOPW method

Dependence of the Energy Gap for some III-V Semiconductors , Ph.D. Thesis, Dohuk University, Kurdistan Region, Iraq, 2004. [14] A bdullah T.G., Temperature Dependence of Direct and Indirect Gaps of CuGe 2 P 3 Semiconductor, Ph.D. Thesis, Salahaddin University-Erbil, Kurdistan Region, Iraq, 2008. [15] A bdullah T.G., Sol. Stat. Sci. Technol., 22 (2014), 55. [16] T say Y.F., G ong B., M itra S.S., V etelino J.F., Phys. Rev. B, 6 (1972), 2330. [17] O lguin D., C antarero A., C ardona M., Phys. Status Solidi B, 220 (2000), 33

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Study on some linear and nonlinear optical parameters of glycine hydrofluoride single crystals

Abstract

Single crystal of glycine hydroflruoride (GHF) was grown from aqueous solution by slow evaporation technique. The structure of the grown crystal was tested and analyzed through X-ray powder diffraction. The functional groups have been identified from the FT-IR spectra. Slabs cut normal to the b-axis from the grown crystal were subjected to incident radiation with a wavelength range of 200 nm to 800 nm to investigate the transmittance and reflectance spectra. Linear optical parameters such as extinction coefficient k, refractive index n and both the real and imaginary parts: ∊real and ∊im of the dielectric permittivity were calculated as functions of the incident photon energy. The dispersion of the refractive index was fitted in terms of Cauchy formula and Wemple-DiDomenico single oscillator model. GHF crystals exhibited indirect optical interband transition and the optical energy gap Eg was determined by using Tauc plot. The indirect band gaps at elevated temperatures were determined and their temperature dependence was estimated. Optical band gap Eg values were found to decrease with an increase in crystal temperature; however, the band tail width exhibited opposite behavior. The nonlinear optical potential was examined by the second harmonic generation (SHG) test.

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Water infiltration in an aquifer recharge basin affected by temperature and air entrapment

., 1995. A simple soil-plant-atmosphere transfer model (SiSPAT) development and field verification. J. Hydrol., 166, 213–250. Constantz, J., 1982. Temperature dependence of unsaturated hydraulic conductivity of two soils. Soil Sci. Soc. Am. J., 46, 466–470. Constantz, J., Thomas, C.L., Zellweger, G., 1994. Influence of diurnal variations in stream temperature on streamflow loss and groundwater recharge. Water Resour. Res., 30, 3253–3264. Di Prima, S., Lassabatere, L., Bagarello, V., Iovino, M., Angulo-Jaramillo, R., 2016. Testing a new automated single

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Percolation thresholds in temperature dependence of electric conductivity of collagen films

Percolation thresholds in temperature dependence of electric conductivity of collagen films

Temperature measurement of electrical conductivity s were carried out from 395 to 543 K. The obtained dependence indicates an increase in s. The temperature dependence of the electrical conductivity allowed to observe the release of the free water, bound water and structural water. Studies on electric conductivity of collagen indicate the occurrence of percolation threshold, which comprises free release of water and change its properties from semiconducting to dielectric one.

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Temperature dependence of stress in CVD diamond films studied by Raman spectroscopy

Abstract

Evolution of residual stress and its components with increasing temperature in chemical vapor deposited (CVD) diamond films has a crucial impact on their high temperature applications. In this work we investigated temperature dependence of stress in CVD diamond film deposited on Si(100) substrate in the temperature range of 30 °C to 480 °C by Raman mapping measurement. Raman shift of the characteristic diamond band peaked at 1332 cm-1 was studied to evaluate the residual stress distribution at the diamond surface. A new approach was applied to calculate thermal stress evolution with increasing tempera­ture by using two commonly known equations. Comparison of the residts obtained from the two methods was presented. The intrinsic stress component was calculated from the difference between average values of residual and thermal stress and then its temperature dependence was discussed.

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Temperature dependence of Bi4Ge3O12 photoluminescence spectra

Abstract

Bi4Ge3O12 single crystals were obtained using Czochralski growth method. Photoluminescence spectra were analyzed versus temperature from 12 to 295 K. Besides the previously observed emission bands at 610 and 820 nm, the new emission band at 475 nm was found by a careful temperature dependence measurement in the present study. The influence of basic and defect structure on the shape and position of the spectra versus temperature was discussed.

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The Glass Transition Temperature and Temperature Dependence of Activation Energy of Viscous Flow of Ovalbumin

albumin. Biophys. J. 57, 389-396. Monkos K. (1996). Viscosity of bovine serum albumin aqueous solutions as a function of temperature and concentration. Int. J. Biol. Macromol. 18, 61-68. Monkos K. (2000). Viscosity analysis of the temperature dependence of the solution conformation of ovalbumin. Biophys. Chem. 85, 7-16. Monkos K. (2007a). Temperature dependence of the activation energy of viscous flow for ovalbumin in aqueous solutions. Curr. Top. Biophys. 30, 29-33. Monkos K. (2007b). Studies of protein

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Frequency and temperature dependent transport properties of NiCuZn ceramic oxide

Abstract

A polycrystalline sample of ceramic oxide Ni0.27Cu0.10Zn0.63Fe2O4 was prepared by the solid state reaction method. The sintered sample was well polished to remove any oxide layer formed during sintering and the two surfaces of the pellet were coated with a silver paste as a contact material. Among dielectric properties, complex dielectric constant (ε* = εʹ - jεʺ), loss tangent (tanδ) and ac conductivity (σac) in the frequency range of 20 Hz to 2 MHz were analyzed in the temperature range of 303 to 498 K using a Wayne Kerr impedance analyzer (model No. 6500B). The experimental results indicate that ε, εʺ, tanδ and σac decrease with an increase in frequency and increase with increasing temperature. The transition temperature, as obtained from dispersion curve of εʹ, shifts towards higher temperature with an increase in frequency. The variation of dielectric properties with frequency and temperature shows the dispersion behavior which is explained in the light of Maxwell-Wagner type of interfacial polarization in accordance with the Koop’s phenomenological theory. The frequency dependent conductivity results satisfy the Jonscher’s power law, σT(ω) = σ(o)+Aωn, and the results show the occurrence of two types of conduction process at elevated temperature: (i) low frequency conductivity, due to long-range ordering (frequency independent, region I), (ii) mid frequency conductivity at the grain boundaries (region II, dispersion) and (iii) high frequency conductivity at the grain interior due to the short-range hopping mechanism (frequency independent plateau, region III).

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