Mueller-matrix Ellipsometry on Electroformed Rough Surfaces

Abstract

Automated Mueller-matrix ellipsometry was used to investigate the optical properties of electroformed standard rough surfaces as a function of r.m.s. surface roughness heights and angle of incidence. The r.m.s. roughness of the specimens examined varied from 50 to 12 500 nm. Six different surface finishes and 22 different specimens were examined and Mueller matrices were obtained at angles of incidence that varied from 30 to 80°. Measurements were conducted at a wavelength of 633 nm with the use of a division-of-amplitude photopolarimeter capable of simultaneously measuring all four Stokes parameters of arbitrarily polarized light. Values of ψ and Δ, the ellipsometric parameters, were derived from the measured Mueller matrices. The results demonstrate firstly the monotonic variations in the derived values of Δ with surface roughness for fixed angles of incidence, which include a ‘resonance’ effect for specimens with r.m.s. roughness heights close to the wavelength of light, secondly a systematic variation of ψ with the angle of incidence for different specimen roughness values and a reversal in these trends beyond the pseudo-Brewster angle, thirdly a monotonic variation in Δ values with the angle of incidence for different roughness values, fourthly relatively large variations in ψ values for roughness values close to the wavelength of light and fifthly relatively little change in ψ and Δ values for roughness values that greatly exceeded the wavelength of light.     

Parameter Estimation in Water Distribution Networks

Estimation of pipe roughness coefficients is an important task to be carried out before any water distribution network model is used for online applications such as monitoring and control. In this study, a combined state and parameter estimation model for water distribution networks is presented. Typically, estimation of roughness coefficient for each individual pipe is not possible due to non-availability of sufficient number of measurements. In order to address this problem, a formal procedure based on K-means clustering algorithm is proposed for grouping the pipes which are likely to have the same roughness characteristics. Also, graph-theoretic concepts are used to reduce the dimensionality of the problem and thereby achieve significant computational efficiency. The performance of the proposed model is demonstrated on a realistic urban water distribution network.     

CSCC for the mean and standard deviation of non-normally distributed life test data

In this paper Cumulative Sum Control Charts (CSCC) have been constructed for the mean and standard deviation of non-normally distributed life test data. The parameters of the V-mask have been determined and finally the expression for the Average Run Length is derived.     

Room-temperature metal stamping by microfluidics

We show the possibility to fabricate highly controlled metal micropatterns on a variety of substrates, such as semiconducting or metallic materials, exploiting a combination of spontaneous galvanic displacement reactions with microfluidics. The process is reliable and quite versatile and allows the fabrication of complex patterns of different metals on a number of substrates in few minutes on a conventional laboratory bench.     

The Contribution of Vessel Volume Change and Blood Resistivity Change to the Electrical Impedance Pulse

An impedance pulse, recorded noninvasively, has contributions due to both the change in blood volume of the arteries and to the change in the blood resistivity. Other researchers have tried to quantify the relative contributions and have either underestimated or overestimated the contributions since they did not simulate the physiological conditions. We have used an in vitro flow circulation system to more closely simulate the physiological conditions and quantify the two contributions. We find that the blood resistivity change contribution is strong enough (21.5 percent of the arterial volume change contribution) to change the morphology of the impedance pulse. There is, however, a phase difference between the two contributions. As a result of this, the blood resistivity change contribution to the height of the impedance pulse will be less than 5.5 percent.     

Corrosion of type 316L stainless steel in molten LiCl–KCl salt

Pyrochemical reprocessing in molten chloride salt medium has been considered as one of the best options for the reprocessing of spent metallic fuels. The AISI 316L stainless steel (SS) is envisaged as a candidate material for the fabrication of components for various unit operations like salt preparation vessel, electro‐refiner and cathode processor, on which ceramic coatings with metallic bond coat will be applied by the thermal plasma spraying. The unit operation like electro‐refining is carried out in the molten lithium chloride–potassium chloride (LiCl–KCl) eutectic salt at 773 K in argon atmosphere. The corrosion behaviour of the container vessel in molten chloride salts is therefore important, hence corrosion tests were carried out in a molten salt test assembly under argon gas atmosphere. The present paper discusses the corrosion behaviour of 316L SS in the molten LiCl–KCl eutectic salt at 873 K. The 316L SS samples were immersed in the molten LiCl–KCl eutectic for 25, 100 and 250 h, while 316L SS with yttria stabilized zirconia coating was exposed for 1000 h. The exposed samples were examined by optical and scanning electron microscope for corrosion attack. The X‐ray mappings of the cross‐section of the degraded layer onto the 316L SS indicated that the mechanism of corrosion corresponds to the selective diffusion of Cr to the surface with the formation of voids below, and the formation of chromium compounds at the surface. The results of the present study indicated that the yttria stabilized zirconia coating onto the 316L SS exhibits a better corrosion resistance in molten chloride salt than with uncoated 316L SS.     

A new parallel algorithm for parsing arithmetic infix expressions

A new parallel algorithm for transforming an arithmetic infix expression into a par se tree is presented. The technique is based on a result due to Fischer (1980) which enables the construction of the parse tree, by appropriately scanning the vector of precedence values associated with the elements of the expression. The algorithm presented here is suitable for execution on a shared memory model of an SIMD machine with no read/write conflicts permitted. It uses O(n) processors and has a time complexity of O(log²n) where n is the expression length. Parallel algorithms for generating code for an SIMD machine are also presented.     

Nonlinear optical studies on new conjugated poly{2,2l‐(3,4‐ dialkoxythiophene‐2,5‐diyl) bis[5‐(2‐thienyl)‐1,3,4‐oxadiazole]}s

Three new donor–acceptor type poly{2,2^l‐(3,4‐ dialkoxythiophene‐2,5‐diyl)bis[5‐(2‐thienyl)‐1,3,4‐oxadiazole]}s ( P1, P2, and P3 ) were synthesized starting from thiodiglycolic acid and diethyl oxalate through multistep reactions. The polymerization was carried out using chemical polymerization technique. The optical and charge‐transporting properties of the polymers were investigated by UV‐visible, fluorescence emission spectroscopic and cyclic voltammetric studies. The polymers showed bluish‐green fluorescence in solutions. The electrochemical band gaps were determined to be 2.03, 2.09, and 2.17 eV for P1 , P2, and P3, respectively. The nonlinear optical properties of new polymers were investigated at 532 nm using single beam Z‐scan and degenerate four‐wave mixing (DFWM) techniques with nanosecond laser pulses. The polymers exhibited strong optical limiting behavior due to “effective” three‐photon absorption. Values of the effective three‐photon absorption ( 3PA ) coefficients, third‐order nonlinear susceptibilities (χ⁽³⁾), and figures (F) of merit were calculated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Superior Analog Performance due to Source-Gate Overlap in Vertical Line-Tunneling FETs and Their Circuits

Silicon - This paper presents a Vertical Line-Tunneling FET (VLTFET) optimized for superior performance in analog applications. The saturation mechanism, DC, and small-signal behaviors are...     

Quartic autocatalysis of homogeneous and heterogeneous reactions in the bioconvective flow of radiating micropolar nanofluid between parallel plates

This study deals with the quartic autocatalysis of homogeneous–heterogeneous chemical reaction that occurs in the bioconvective flow of micropolar nanofluid between two horizontally parallel plates. The quartic autocatalysis is found to be more effective than cubic autocatalysis since the concentration of the homogeneous species is substantially high. The upper plate is assumed to be in motion and the lower plate is kept stationary. Such a flow of micropolar fluid finds application in the pharmaceutical industry, microbial enhanced oil recovery, hydrodynamical machines, chemical processing, and so forth. The governing equations for this flow are in the form of the partial differential equation and their corresponding similarity transformation is obtained through Lie group analysis. The governing equations are further transformed to coupled nonlinear differential equations that are linearized through the Successive linearization method and are solved using the Chebyshev Collocation method. The effects of various parameters, such as micropolar coupling parameter, spin gradient parameter, reaction rates, and so forth, are analyzed. It is observed that the fluid flows with a greater velocity away from the channel walls, whereas near the channel walls the velocity decreases with an increase in the coupling parameter. Furthermore, the spin parameter increases the spin gradient viscosity that reduces the microrotation of particles that further decreases the microrotation profile.