Computation of pressure drop for dilute gas-solid suspension across thin and thick orifices

The present work deals with the computation of the gas-solid two-phase flow pressure drop across thin and thick orifices for a vertically downward flow configuration at the higher limits of a dilute phase flow situation(0.01≤αs,in≤0.10).The Eulerian-Eulerian(two-fluid)model has been used in conjunction with the kinetic theory of granular flow with a four-way coupling approach.The validation of the solution process has been performed by comparing the computational result with the existing experimental data.It is observed that the two-phase flow pressure drop across the orifice increases with an increase in the thickness of the orifice,and the effect is more prominent at higher solid loading.The pressure drop is found to increase with an increase in the solid volume fraction.An increase in the Reynolds number or the area ratio increases the pressure drop.An increase in the size of the particles reduces the pressure drop across the orifice at both small and relatively large solid volume fractions.Finally,a two-phase multiplier has been proposed in terms of the relevant parameters,which can be useful to evaluate the gas-solid two-phase flow pressure drop across the orifice and can subsequently help to improve the system performance.     

Degradation process in organic thin film devices fabricated using P3HT

The stability of regioregular poly(3-hexylthiophene 2,5-diyl) (P3HT) thin films sandwiched between indium tin oxide (ITO) and aluminium (Al) electrodes have been investigated under normal environmental conditions (25°C and RH∼45–50%). Electrical and optical properties of ITO/P3HT/Al devices have been studied over a period of 30 days. Mobility μ of the order of 10⁻⁴ cm²/V-s has been obtained from the V ² law in the as-deposited P3HT films. Scanning electron microscopy (SEM) investigations show blistering of Al contacts in devices with a poly(3,4-ethylenedioxythiophene) (PEDOT) interlayer on application of voltage whereas no blistering is seen in devices without PEDOT. The results have been explained in terms of trap generation and propagation and the moisture-absorbing nature of PEDOT.      

Comparative study of different Schlieren diffracting elements

This paper presents an analysis of diffraction effects taking place at different Schlieren diffracting elements. Two types of diffraction effects are prominent in the Schlieren schemes. One is diffraction of direct light (source image) at the Schlieren element, which limits the sensitivity and resolution of Schlieren systems. The second type is the diffraction of light deflected from the test object at the Schlieren-diffracting element. This second type of diffraction degrades the quality of Schlieren results. Experimental results showing the effect of diffraction of light deflected from the test object at a phase knife-edge, corner of a square phase aperture and an optical fiber tip as Schlieren diffracting elements have been presented and discussed.      

Stable edge dislocations in finite crystals

Dislocations have been considered as mechanically unstable defects in bulk crystals, ignoring the Peierls oscillations. Eshelby [J. Appl. Phys. 24 (1953) p.176] had showed that a screw dislocation can be stable in a thin cylinder. In the current work, considering Eshelby's example of an edge dislocation in a single crystalline plate, we show that an edge dislocation can be stable in a finite crystal. Using specific examples, we also show that the position of stability of an edge dislocation can be off-centre. This shift in the stability from the centre marks the transition from a stable dislocation to an unstable one. The above-mentioned tasks are achieved by simulating edge dislocations using the finite element method.     

Analyses of Lattice Traffic Flow Model on a Gradient Highway

The optimal current difference lattice hydrodynamic model is extended to investigate the traffic flow dynamics on a unidirectional single lane gradient highway. The effect of slope on uphill/downhill highway is examined through linear stability analysis and shown that the slope significantly affects the stability region on the phase diagram.Using nonlinear stability analysis, the Burgers, Korteweg-deVries(KdV) and modified Korteweg-deVries(mKdV) equations are derived in stable, metastable and unstable region, respectively. The effect of reaction coefficient is examined and concluded that it plays an important role in suppressing the traffic jams on a gradient highway. The theoretical findings have been verified through numerical simulation which confirm that the slope on a gradient highway significantly influence the traffic dynamics and traffic jam can be suppressed efficiently by considering the optimal current difference effect in the new lattice model.     

超导纳米线单光子探测器件的制备

超导纳米线单光子探测器件(SNSPD)是超导单光子探测系统的核心器件。文中介绍了成功制备的基于5nm厚的NbN超导超薄薄膜的SNSPD器件。器件核心结构为150nm宽的纳米曲折线结构,纳米线条占空比为75%,面积为20μm×20μm。超导纳米线是利用电子束曝光(EBL)技术和反应离子刻蚀(RIE)等工艺技术制备的。所制备的SNSPD样品,在温度3.5K下的临界电流约12.9μA;在1310nm波长光波辐照,12.5μA的偏置电流下,探测效率约0.016%。     

An Interacting Gauge Field Theoretic Model for Hodge Theory: Basic Canonical Brackets

We derive the basic canonical brackets amongst the creation and annihilation operators for a two （1 ＋ 1）- dimensional （2D） gauge field theoretic model of an interacting Hodge theory where a U（1） gauge field （Aμ） is coupled with the fermionic Dirac fields （ψ and ψ）. In this derivation, we exploit the spin-statistics theorem, normal ordering and the strength of the underlying six infinitesimal continuous symmetries （and the concept of their generators） that are present in the theory. We do not use the definition of the canonical conjugate momenta （corresponding to the basic fields of the theory） anywhere in our whole discussion. Thus, we conjecture that our present approach provides an alternative to the canonical method of quantization for a class of gauge field theories that are physical examples of Hodge theory where the continuous symmetries （and corresponding generators） provide the physical realizations of the de Rham cohomological operators of differential geometry at the algebraic level.     

Calix[4]arene-based ditopic receptors for simultaneous recognition of fluoride and cobalt(II) ions

A series of calix[4]arene based ditopic receptors possessing bipyridyl and hydrazone units have been synthesized and evaluated for ionic recognition. It has been observed that the synthesized derivatives function as allosteric receptors for simultaneous recognition of Co²⁺and F^? ions through non-covalent interactions. Significant bathochromic shifts in the UV–visible spectrum with a profound colour change promise their use to engineer novel applications.     

A theoretical perspective on the accuracy of rotational resonance (R 2)-based distance measurements in solid-state NMR

The application of solid-state NMR methodology for bio-molecular structure determination requires the measurement of constraints in the form of ¹³C–¹³C and ¹³C–¹⁵N distances, torsion angles and, in some cases, correlation of the anisotropic interactions. Since the availability of structurally important constraints in the solid state is limited due to lack of sufficient spectral resolution, the accuracy of the measured constraints become vital in studies relating the three-dimensional structure of proteins to its biological functions. Consequently, the theoretical methods employed to quantify the experimental data become important. To accentuate this aspect, we re-examine analytical two-spin models currently employed in the estimation of ¹³C–¹³C distances based on the rotational resonance (R ²) phenomenon. Although the error bars for the estimated distances tend to be in the range 0.5–1.0 Å, R ² experiments are routinely employed in a variety of systems ranging from simple peptides to more complex amyloidogenic proteins. In this article we address this aspect by highlighting the systematic errors introduced by analytical models employing phenomenological damping terms to describe multi-spin effects. Specifically, the spin dynamics in R ² experiments is described using Floquet theory employing two different operator formalisms. The systematic errors introduced by the phenomenological damping terms and their limitations are elucidated in two analytical models and analysed by comparing the results with rigorous numerical simulations.     

Photoluminescence and atomic force microscopy studies on pre- and post-irradiated ruby with Fe3+ ion

Photoluminescence spectra measured for pristine ruby and its two irradiated samples with Fe³⁺ ion show R₁, R₂, N lines and a broad band. Decrease in intensities of these features is observed with irradiation of Fe³⁺ ion in ruby. Progressive structural changes and modifications on surface of irradiated rubies with Fe³⁺ ion have been observed by atomic force microscopy. Decrease in intensities is discussed in terms of pair formation.