Abstract
A vertical annular configuration with differently heated cylindrical surfaces and horizontal adiabatic boundaries is systematically studied in view to their industrial applications. In this ...paper, we investigate the effects of conjugate buoyant heat transport in water based nanofluids with different nanoparticles such as alumina, titania or copper, and is filled in the enclosed annular gap. The annulus space is formed by a thick inner cylinder having a uniform high temperature, an exterior cylindrical tube with a constant lower temperature, and thermally insulated upper and lower surfaces. By investigating heat transport for broad spectrum of Rayleigh number, solid wall thickness, thermal conductivity ratio and nanoparticle volume fraction, we found that the influence of wall thickness on thermal dissipation rate along wall and interface greatly depends on conductivity ratio and vice-versa. In particular, we uncover that the choice of nanoparticle in a nanofluid and its concentration are key factors in enhancing the thermal transport along the interface. Specially, copper based nanofluids produces higher heat transport among other nanoparticles, and for the range of nanoparticle concentration chosen in this analysis, enhanced thermal dissipation along the interface has been detected as nanoparticle volume fraction is increased. Our results are applicable to choose nanofluids along with other critical parameters for the desired heat transport.
Photovoltaic properties of SnS based solar cells Ramakrishna Reddy, K.T.; Koteswara Reddy, N.; Miles, R.W.
Solar energy materials and solar cells,
11/2006, Letnik:
90, Številka:
18
Journal Article, Conference Proceeding
Recenzirano
Polycrystalline thin films of tin sulphide have been synthesised using spray pyrolysis. The layers grown at a temperature of 350
°C had the orthorhombic crystal structure with a strong (1
1
1) ...preferred orientation. The films had resistivities ∼30
Ω
cm with an optical energy band gap (
E
g) of 1.32
eV. Heterojunction solar cells were fabricated using sprayed SnS as the absorber layer and indium doped cadmium sulphide as the window layer and the devices were characterised to evaluate the junction properties as well as the solar cell performance. The current transport across the junction has been modelled as a combination of tunnelling and recombination. The best devices had solar conversion efficiencies of 1.3% with a quantum efficiency of 70%.
The classical and shear deformation beam and plate theories are reformulated using the nonlocal differential constitutive relations of Eringen and the von Kármán nonlinear strains. The equations of ...equilibrium of the nonlocal beam theories are derived, and virtual work statements in terms of the generalized displacements are presented for use with the finite element model development. The governing equilibrium equations of the classical and first-order shear deformation theories of plates with the von Kármán nonlinearity are also formulated. The theoretical development presented herein should serve to obtain the finite element results and determine the effect of the geometric nonlinearity and nonlocal constitutive relations on bending response.
The third-order shear deformation plate theory of Reddy A simple higher-order theory for laminated composite plates,
J. Appl. Mech. 51 (1984) 745–752 is reformulated using the nonlocal linear ...elasticity theory of Eringen. This theory has ability to capture the both small scale effects and quadratic variation of shear strain and consequently shear stress through the plate thickness. Analytical solutions of bending and free vibration of a simply supported rectangular plate are presented using this theory to illustrate the effect of nonlocal theory on deflection and natural frequency of the plates. Finally, the relations between nonlocal third-order, first-order and classical theories are discussed by numerical results.
Here we report on Bi2O3 clusters immobilized on anatase TiO2 nanostructures for an enhanced rate of photocatalytic H2 evolution. Structural, morphological, and optical properties of the Bi2O3@TiO2 ...nanocomposite (BT) were characterized by a series of techniques including X-ray diffraction, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy and electrochemical impedance spectroscopy. The catalytic H2 evolution experiments were carried out under different light sources: natural solar light, LED UV (365 ± 5 nm) and LED visible (420 ± 5 nm) light source. Under the solar light a pristine anatase TiO2 nanostructured (TNS) catalyst generated 4.20 mmol h−1 g−1, whereas in the presence of Bi2O3@TNS showed much higher H2 production 26.02 mmol h−1 g−1. The photocatalytic activity of the BT and its reproducible performance for five recycles is ascribed to an efficient separation of photogenerated charge carriers. A plausible reaction mechanism for the H2 generation is proposed.
•Anatase TiO2 nanostructures were prepared by using hydrothermal and thermal treatment methods.•Bi2O3 clusters@TiO2 nanostructures facilitated enhanced rate of photocatalytic H2 evolution.•Bi2O3@TiO2 produced 6 folds higher rate of H2 production under solar light irradiation.
Tin (II) sulphide (SnS), a direct band gap semiconductor compound, has recently received great attention due to its unique properties. Because of low cost, absence of toxicity, and good abundance in ...nature, it is becoming a candidate for future multifunctional devices particularly for light conversion applications. Although the current efficiencies are low, the cost-per-Watt is becoming competitive. At room temperature, SnS exhibits stable low-symmetric, double-layered orthorhombic crystal structure, having a = 0.4329, b = 1.1192, and c = 0.3984 nm as lattice parameters. These layer-structured materials are of interest in various device applications due to the arrangement of structural lattice with cations and anions. The layers of cations are separated only by van der Waals forces that provide intrinsically chemically inert surface without dangling bonds and surface density of states. As a result, there is no Fermi level pinning at the surface of the semiconductor. This fact leads to considerably high chemical and environmental stability. Further, the electrical and optical properties of SnS can be easily tailored by modifying the growth conditions or doping with suitable dopants without disturbing its crystal structure.
In the last few decades, SnS has been synthesized and studied in the form of single-crystals and thin-films. Most of the SnS single-crystals have been synthesized by Bridgeman technique, whereas thin films have been developed using different physical as well as chemical deposition techniques. The synthesis or development of SnS structures in different forms including single-crystals and thin films, and their unique properties are reviewed here. The observed physical and chemical properties of SnS emphasize that this material could has novel applications in optoelectronics including solar cell devices, sensors, batteries, and also in biomedical sciences. These aspects are also discussed.
This work investigated the performance of overlapped gate-on-drain of a gate all around-tunnel field-effect transistor (GAA-TFET) biosensors by considering the dielectric modulated technique by ...immobilizing the targeted biomolecules in the cavity region curved under the overlapped gate-on-drain. The nanowire GAA-TFET device shows excellent controllability over the channel and reduces leakage current to a greater extent. Here, we tried to make the ambipolar nature of the TFET, an advantage for the biosensor by detecting the biomolecule using variation of ambipolar current of TFET. Due to structural arrangement, the nanocavity under the overlapped gate region suppresses the ambipolar drain current by increasing the dielectric constant of the targeted biomolecules. The device can show a variation of 10
2
and 10
3
amount of sensitivity for the variation of dielectric constant from 1 to 5 and, compared with the other TFET structure, the proposed overlapped gate-on-drain GAA-TFET biosensor shows higher sensitivity and low leakage with a highly controlled channel.
Electrocardiogram (ECG) watermarking provides secure communication of patient information lies in a 1D- ECG signal. The primary challenge in ECG watermarking is the deterioration of an ECG signal ...which causes the loss and impotence to extract patient information. This paper proposes a wavelet method based watermarking scheme for patient information hiding in the ECG as a QR image. Here, we first convert the 1D-ECG signal to 2D-ECG image using the Pan–Tompkins algorithm. We use a wavelet transform to decompose 2D-ECG image. Wavelet analysis can capture the subtle underlying information of the ECG. Then we further decompose the detail coefficient of wavelet and the QR image using QR decomposition for embedding data. The embedding factor value calculation is adaptive by harnessing the entropy value of the signal. The hidden data is easily extractable with no distortion at the extractor side. The ECG data we use in this paper is from the MIT-BIH database. The results on this dataset suggest that our proposed approach is useful in patient information data hiding scheme in ECG. The proposed method outperforms the state-of-the-art.
The highly efficient single‐junction bulk‐heterojunction (BHJ) PM6:Y6 system can achieve high open‐circuit voltages (VOC) while maintaining exceptional fill‐factor (FF) and short‐circuit current ...(JSC) values. With a low energetic offset, the blend system is found to exhibit radiative and non‐radiative recombination losses that are among the lower reported values in the literature. Recombination and extraction dynamic studies reveal that the device shows moderate non‐geminate recombination coupled with exceptional extraction throughout the relevant operating conditions. Several surface and bulk characterization techniques are employed to understand the phase separation, long‐range ordering, as well as donor:acceptor (D:A) inter‐ and intramolecular interactions at an atomic‐level resolution. This is achieved using photo‐conductive atomic force microscopy, grazing‐incidence wide‐angle X‐ray scattering, and solid‐state 19F magic‐angle‐spinning NMR spectroscopy. The synergy of multifaceted characterization and device physics is used to uncover key insights, for the first time, on the structure–property relationships of this high‐performing BHJ blend. Detailed information about atomically resolved D:A interactions and packing reveals that the high performance of over 15% efficiency in this blend can be correlated to a beneficial morphology that allows high JSC and FF to be retained despite the low energetic offset.
The high‐performing single‐junction organic solar cell blend, PM6:Y6, is examined to obtain an in‐depth understanding of the voltage losses, and charge recombination and extraction dynamics. The devices exhibit remarkable extraction coupled with moderate recombination losses. This behavior can most likely be credited to a beneficial morphology as evidenced by atomically resolved 19F magic‐angle‐spinning solid‐state NMR analysis.
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