Phenomenology of a-axis and b-axis charge dynamics from microwave spectroscopy of highly ordered YBa2Cu3O6.50 and YBa2Cu3O6.993

Extensive measurements of the microwave conductivity of highly pure and oxygen-ordered \YBCO single crystals have been performed as a means of exploring the intrinsic charge dynamics of a d-wave superconductor. Broadband and fixed-frequency microwave apparatus together provide a very clear picture of the electrodynamics of the superconducting condensate and its thermally excited nodal quasiparticles. The measurements reveal the existence of very long-lived excitations deep in the superconducting state, as evidenced by sharp cusp-like conductivity spectra with widths that fall well within our experimental bandwidth. We present a phenomenological model of the microwave conductivity that captures the physics of energy-dependent quasiparticle dynamics in a d-wave superconductor which, in turn, allows us to examine the scattering rate and oscillator strength of the thermally excited quasiparticles as functions of temperature. Our results are in close agreement with the Ferrell-Glover-Tinkham sum rule, giving confidence in both our experiments and the phenomenological model. Separate experiments for currents along the $\hat a$ and $\hat b$ directions of detwinned crystals allow us to isolate the role of the CuO chain layers in \YBCO, and a model is presented that incorporates both one-dimensional conduction from the chain electrons and two-dimensional transport associated with the \cuplane plane layers.Comment: 17 pages, 13 figure

Convergence acceleration of an upwind least squares finite difference based meshless solver

One of the important trends in the present day CFD research is the development of new class of flow solvers called meshless solvers. All that this class of solvers require is a distribution of points in the computational domain. The development of upwind least squares finite difference method can be considered as a landmark event in the advances being made in the area of meshless solvers. In this paper, we propose an implicit time integration methodology for upwind least squares finite difference procedure. The idea of matrix-free implicit procedure in the framework of finite volume solver has been exploited in the present work to obtain a cheap and robust implicit time integration procedure. The present formulation shows excellent convergence acceleration over the explicit upwind least squares finite difference procedure

An upwind finite difference scheme for meshless solvers

In this paper, we present a new upwind finite difference scheme for meshless solvers. This new scheme, capable of working on any type of grid (structure, unstructured or even a random distribution of points) produces superior results. A means to construct schemes of specified order of accuracy is discussed. Numerical computations for different types of flow over a wide range of Mach numbers are presented. Also, these results were compared with those obtained using a cell vertex finite volume code on the same grids and with theoretical values wherever possible. The present framework has the flexibility to choose between various upwind flux formulas

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Not AvailableHistomorphological changes in neurosecretory cells of eyestalk (optic ganglia), brain and thoracic ganglia of Parapenaeopsis stylifera during different stages of ovarian maturation were recorded. There were five types of neurosecretory cells (NSCs) in eyestalk with size in range of 5-35 µm. They were distributed along medulla externa, medulla interna and medulla terminalis. Axonal terminals of these neurosecretory cells were found to terminate in sinus gland. Brain and thoracic ganglia possessed five types of neurosecretory cells such as giant neuron (80 µm), A (61-80 µm), B (41-60 µm), C (21-40 µm) and D (20 µm). They were arranged in several groups in different parts of brain - in anterior region B, C and D cells were observed, in posterior region giant neurons and Acells more in numberwhile A, B, C and D cells were found in lateral regions. Of the three regions in thoracic ganglia (anterior, middle and posterior), NSCs were distributed in anterior and posterior portions but were lacking in middle region. Aand B cells were noticed in anterior region followed by C and D cells. In posterior region, giant neurons and Acells were seen. Ovarian maturation in Parapenaeopsis stylifera seems to be under dual control of inhibitory action by the secretion of B and C cells of eyestalk and stimulatory influence by giant neuron (GN), Aand B cells of brain and thoracic ganglia as these NSCs of eyestalk were active in immature stage whereas cells of brain and thoracic ganglia were active in mature females. The active stage of secretion was characterized by hypertrophy, increase in number of nucleolus, staining intensity, granulation and migration of secretory material towards axon. Histochemical tests demonstrated that the neurosecretory cells of the shrimp were strongly positive to acid fuchsin, paraldehyde fuchsin but exhibited feeble reaction to Sudan black B and periodic acid-Schiff's reagent (PAS).Not Availabl

Fault Tree Analysis for Fungal Corrosion of Coated Aluminum

A fault tree methodology has been used to analyze the combinations of basic factors involved in fungal degradation and corrosion. The purpose was to demonstrate the identification of mitigation actions for reducing the risk of fungal corrosion of coated aluminum in aircraft. The interaction between fungal-induced degradation processes and coatings is described, and the methodology of the fault tree analysis (FTA) is presented. The interconnection of the basic factors through conventional AND and OR logic gates in the fault tree structure reveals vulnerabilities and potential failure pathways in the system. Mitigation actions can be directed at these basic factors to reduce or eliminate failure pathways, thereby reducing the overall risk of fungal-induced corrosion. Potential applications of FTA for corrosion mitigation, design and materials selection, and failure analysis are presented

Effect of CuPc and PEDOT:PSS as hole transport layers in planar heterojunction CdS/CdTe solar cell

This paper presents the fabrication and photovoltaic performance of new architecture based planar heterojunction CdS/CdTe thin film solar cells which were employed with two hole transport layers (PEDOT:PSS as HTL1 and CuPc as HTL2). The reported solar cells were fabricated through various deposition techniques such as sputtering, thermal evaporation, spin coating and characterized by FESEM, AFM, XPS, UPS and AM 1.5 solar simulator. The interfacial layer growth and chemical state identification of the deposited thin films were studied by cross-sectional FESEM and XPS techniques. The band bending occurs between absorbing and transporting layer helps to inject the excited charge carriers effectively into electrode that was explained using UPS analysis. The present work intends to explain the role of additional window layer (TiO2), buffer layer (CdS) and hole transporting layers (PEDOT:PSS and CuPc) in the novel device architecture. Further, these findings will offer new research directions to address the double hole transport (back contact) layers selection concept in CdS/CdTe heterojunction based solar cells

Adaptive denoising at Infrared wireless receivers

This paper proposes an innovative approach for noise cancellation at infrared (IR) wireless receivers. Ambient noise due to artificial lighting and the sun has been a major concern in infrared systems. The background induced shot noise typically has a power from 20 to 40 dB more than the signal induced shot noise and varies with time. Due to these changing conditions, infrared wireless receivers experience high level of non-stationary noise. The objective of the work mentioned in this paper is to develop digital signal processing algorithms at the infrared wireless system to combat high power non-stationary noise. The noisy signal is decomposed using a joint time and frequency representation such as wavelets and wavelet packets, into transform domain coefficients and the lower order coefficients are removed by applying a threshold. Denoised version is obtained by reconstructing the signal with the remaining coefficients. In this paper, we evaluate different wavelet methods for denoising at an infrared wireless receiver. Simulation results indicate that if the noise is uncorrelated with the signal and the channel model is unavailable the wavelet denoising method with different wavelet analyzing functions improves the signal to noise ratio (SNR) from 4 dB to 7.8 dB