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排序方式: 共有55条查询结果,搜索用时 15 毫秒
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The paper is concerned with the dispersion of a solute in a Bingham plastic fluid flowing in a pipe or a parallel plate channel. For pipe flow, the dispersion coefficient K2 first increases with ξ0 (the dimensionless radius of the plug flow region), reaches a maximum and then decreases. But in a channel flow, K2 decreases monotonically with increasing ξ0. Further K2 for channel flow is found to be larger than that for pipe flow for all values of ξ0 except 0.8≤ξ0≤1. 相似文献
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Rawat Jyoti Singh Annapurna Bhadauria H. S. Virmani Jitendra Devgun J. S. 《Multimedia Tools and Applications》2017,76(18):19057-19085
Multimedia Tools and Applications - In current consequence of haematology, blood cancer i.e. acute lymphoblastic leukemia is very frequently founded in medical practice, which is characterized by... 相似文献
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This short paper reports both the photoluminescence and the lifetime measurements of a prominent emission transition (5D0→7F2) of Eu3+ both in the presence and absence of the codopant rare earth ion (Dy3+) in an optical glass of the composition (79−x)TeO2+6AlF3+15LiF+xLn2O3 as a function of temperature down to 10 K. 相似文献
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Kaushik Biswas Sathravada Balaji Debarati Ghosh Annapurna Kalyandurg 《International Journal of Applied Glass Science》2017,8(2):204-215
In this work, effect of glass composition as well as ceramization on visible and near-infrared (NIR) luminescence properties along with their decay dynamics of Er3+ ions has been compared considering two different oxyfluoride glasses yielding BaF2 and BaGdF5 nanocrystals. Both the glass systems have exhibited an intense normal and upconversion green emission under ultraviolet (378 nm) and NIR (978 nm) excitations, respectively. A remarkable enhancement of these emission intensities is observed for gadolinium-(Gd) containing glasses. Interestingly, NIR fluorescence intensity from Er3+ ions at 1540 nm has showed marginal decrease in gadolinium-containing glass which is attributed to occurrence of strong excited-state absorption (ESA) due to higher fluorine content ensuing an augmentation of upconversion green emission with a concomitant decrease in NIR emission. The quadratic dependence of upconversion green emission intensity on its pump power for all the samples revealed biphotonic absorption process from ground-state 4I15/2 to the excited-state 4I11/2 followed by ESA of second photon to the 4F7/2 level. The intense green upconversion emission as well as enhanced NIR fluorescence lifetimes indicate the suitability of these glass/glass ceramics for upconversion lasers and amplification in the third telecom window. 相似文献
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Mid‐IR transparent TeO2‐TiO2‐La2O3 glass and its crystallization behavior for photonic applications 下载免费PDF全文
Gaurav Gupta Sathravada Balaji Kaushik Biswas Annapurna Kalyandurg 《Journal of the American Ceramic Society》2018,101(9):3900-3916
In this report, effect of enhanced rare earth (La2O3) concentration on substitution of TeO2 within ternary TeO2‐TiO2‐La2O3 (TTL) glass system has been studied with respect to its thermal, structural, mechanical, optical, and crystallization properties with an aim to achieve glass and glass‐ceramics having rare‐earth‐rich crystalline phase for nonlinear optical and infrared photonic applications. DSC analysis (10°C/min) demonstrates a progressive increase in glass‐transition temperature (Tg) from 359 to 452°C with the increase in La2O3 content. Continuous glass network modification with transformation of [TeO4] to [TeO3/TeO3+1] units is evidenced from Raman spectra which is corroborated with XPS studies. While mechanical properties demonstrate enhancement of cross‐linking density in the network. These glasses exhibit optical transmission window extended from 0.4 to 6 μm with calculated zero dispersion wavelength (λZDW) varying from 2.41 to 2.28 μm depending upon La2O3 content. Crystallization kinetics of TTL10 (80TeO2‐10TiO2‐10La2O3 in mol%) glass has been studied via established models. Activation energy (Ea) has been evaluated and dimensionality of crystal growth (m) suggests formation of surface crystals. Glass‐ceramic with crystalline phase of La2Te6O15 has been realized in heat‐treated TTL10 glass samples (at 450°C). As predicted from DSC analysis, FESEM study unveils the formation of surface crystallized glass‐ceramics. 相似文献
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Frequency and temperature dependence of dielectric constant (εr), dielectric loss (tanδ), ac conductivity (σac) and complex impedance spectroscopy studies on cured polyester matrix and sisal fibre-reinforced polyester composites (SFRPC)
have been investigated in the frequency range from 180 Hz to 1 MHz and temperature range from room temperature to 200 °C.
The experimental results showed that with the incorporation of sisal fibre, the values of εr, tanδ and σac are increased. It is also found that the values of εr and tanδ for both cured polyester matrix and SFRPC are decreased with increasing frequency, which indicates that the major
contribution to the polarization may come from orientation polarization and interfacial polarization. The increasing value
of εr with increasing temperature at a particular frequency is due to free motion of the dipole molecular chains within the cured
polyester matrix and SFRPC at higher temperature. 相似文献
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With a high-refractive-index mixed-oxide dielectric material of ZrTiO(4) and ZrO(2) [Substance H2 (Sub2) from E. Merck, Darmstadt, Germany], in combination with magnesium flouride (MgF(2)), design optimization and experimental production of low-loss antireflection (AR) coatings are carried out. Design-optimization studies that make use of these materials as constituents of a seven-layer coating system demonstrate that when the useful bandwidth of an AR coating is extended to cover a wider spectral range, the designs are in general found to have increased integrated reflection loss, higher ripple, and increased spectral instability. The experimental studies on Sub2 material show that the films have excellent optical performance over a wider process window, the advantage of which is demonstrated in the production of different AR coatings on a variety of glasses with refractive indices that range from 1.45 to 1.784 and different mechanical, thermal, and chemical properties. The manufacturing process of AR coatings shows a consistency better than 99% with respect to optical properties and durability. 相似文献