Comment on 'Surface thermodynamics, surface stress, equations at surfaces and triple lines for deformable bodies'

Energy Technology Data Exchange (ETDEWEB)

Gutman, E M, E-mail: gutman@bgu.ac.i [Department of Materials Engineering, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 84105 (Israel)

2010-10-27

In a recent publication by Olives (2010 J. Phys.: Condens. Matter 22 085005) he studied 'the thermodynamics and mechanics of the surface of a deformable body, following and refining the general approach of Gibbs' and believed that 'a new definition of the surface stress is given'. However, using the usual way of deriving the equations of Gibbs-Duhem type the author, nevertheless, has fallen into a mathematical discrepancy because he has tried to unite in one equation different thermodynamic systems and 'a new definition of the surface stress' has appeared known in the usual theory of elasticity. (comment)

Truncatable bootstrap equations in algebraic form and critical surface exponents

Energy Technology Data Exchange (ETDEWEB)

Gliozzi, Ferdinando [Dipartimento di Fisica, Università di Torino andIstituto Nazionale di Fisica Nucleare - sezione di Torino,Via P. Giuria 1, Torino, I-10125 (Italy)

2016-10-10

We describe examples of drastic truncations of conformal bootstrap equations encoding much more information than that obtained by a direct numerical approach. A three-term truncation of the four point function of a free scalar in any space dimensions provides algebraic identities among conformal block derivatives which generate the exact spectrum of the infinitely many primary operators contributing to it. In boundary conformal field theories, we point out that the appearance of free parameters in the solutions of bootstrap equations is not an artifact of truncations, rather it reflects a physical property of permeable conformal interfaces which are described by the same equations. Surface transitions correspond to isolated points in the parameter space. We are able to locate them in the case of 3d Ising model, thanks to a useful algebraic form of 3d boundary bootstrap equations. It turns out that the low-lying spectra of the surface operators in the ordinary and the special transitions of 3d Ising model form two different solutions of the same polynomial equation. Their interplay yields an estimate of the surface renormalization group exponents, y{sub h}=0.72558(18) for the ordinary universality class and y{sub h}=1.646(2) for the special universality class, which compare well with the most recent Monte Carlo calculations. Estimates of other surface exponents as well as OPE coefficients are also obtained.

Calculations of stationary solutions for the non linear viscous resistive MHD equations in slab geometry

International Nuclear Information System (INIS)

Edery, D.

1983-11-01

The reduced system of the non linear resistive MHD equations is used in the 2-D one helicity approximation in the numerical computations of stationary tearing modes. The critical magnetic Raynolds number S (S=tausub(r)/tausub(H) where tausub(R) and tausub(H) are respectively the characteristic resistive and hydro magnetic times) and the corresponding linear solution are computed as a starting approximation for the full non linear equations. These equations are then treated numerically by an iterative procedure which is shown to be rapidly convergent. A numerical application is given in the last part of this paper

Self-dual Yang-Mills equation and deformation of surfaces

International Nuclear Information System (INIS)

Serikbaev, N.S.; Myrzakul, K.; Sajymbetova, S.K.; Koshkinbaev, A.D.; Myrzakulov, R.

2003-01-01

We show that many integrable systems and integrable spin systems in 2+1 dimensions can be obtained from the (2+1)- dimensional Gauss-Mainardi-Codazzi and Gauss-Weingarten equations, respectively. We also show that the (2+1)-dimensional Gauss-Mainardi-Codazzi equation which describes the deformation (motion) of surfaces is the exact reduction of the Yang-Mills-Higgs-Bogomolny and self-dual Yang-Mills equations. On the basis of this observation, we suggest that the (2+1)-dimensional Gauss-Mainardi-Codazzi equation is a candidate to be integrable, and the associated linear problem (Lax representation) with the spectral parameter is presented. (author)

Soliton surfaces via a zero-curvature representation of differential equations

International Nuclear Information System (INIS)

Grundland, A M; Post, S

2012-01-01

The main aim of this paper is to introduce a new version of the Fokas–Gel’fand formula for immersion of soliton surfaces in Lie algebras. The paper contains a detailed exposition of the technique for obtaining exact forms of 2D surfaces associated with any solution of a given nonlinear ordinary differential equation which can be written in the zero-curvature form. That is, for any generalized symmetry of the zero-curvature condition of the associated integrable model, it is possible to construct soliton surfaces whose Gauss–Mainardi–Codazzi equations are equivalent to infinitesimal deformations of the zero-curvature representation of the considered model. Conversely, it is shown (proposition 1) that for a given immersion function of a 2D soliton surface in a Lie algebra, it is possible to derive the associated generalized vector field in the evolutionary form which characterizes all symmetries of the zero-curvature condition. The theoretical considerations are illustrated via surfaces associated with the Painlevé equations P1, P2 and P3, including transcendental functions, the special cases of the rational and Airy solutions of P2 and the classical solutions of P3. (paper)

Neoclassical MHD equations for tokamaks

International Nuclear Information System (INIS)

Callen, J.D.; Shaing, K.C.

1986-03-01

The moment equation approach to neoclassical-type processes is used to derive the flows, currents and resistive MHD-like equations for studying equilibria and instabilities in axisymmetric tokamak plasmas operating in the banana-plateau collisionality regime (ν* approx. 1). The resultant ''neoclassical MHD'' equations differ from the usual reduced equations of resistive MHD primarily by the addition of the important viscous relaxation effects within a magnetic flux surface. The primary effects of the parallel (poloidal) viscous relaxation are: (1) Rapid (approx. ν/sub i/) damping of the poloidal ion flow so the residual flow is only toroidal; (2) addition of the bootstrap current contribution to Ohm's laws; and (3) an enhanced (by B 2 /B/sub theta/ 2 ) polarization drift type term and consequent enhancement of the perpendicular dielectric constant due to parallel flow inertia, which causes the equations to depend only on the poloidal magnetic field B/sub theta/. Gyroviscosity (or diamagnetic vfiscosity) effects are included to properly treat the diamagnetic flow effects. The nonlinear form of the neoclassical MHD equations is derived and shown to satisfy an energy conservation equation with dissipation arising from Joule and poloidal viscous heating, and transport due to classical and neoclassical diffusion

Wave-equation Qs Inversion of Skeletonized Surface Waves

KAUST Repository

Li, Jing

2017-02-08

We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals. The optimal Qs model is the one that minimizes the difference in the peak frequencies of the predicted and observed Rayleigh wave arrivals using a gradient-based wave-equation optimization method. Solutions to the viscoelastic wave-equation are used to compute the predicted Rayleigh-wave arrivals and the misfit gradient at every iteration. This procedure, denoted as wave-equation Qs inversion (WQs), does not require the assumption of a layered model and tends to have fast and robust convergence compared to full waveform inversion (FWI). Numerical examples with synthetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation to the subsurface Qs distribution as long as the Vs model is known with sufficient accuracy.

Skeletonized wave-equation Qs tomography using surface waves

KAUST Repository

Li, Jing

2017-08-17

We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals. The optimal Qs model is then found that minimizes the difference in the peak frequencies of the predicted and observed Rayleigh wave arrivals using a gradient-based wave-equation optimization method. Solutions to the viscoelastic wave-equation are used to compute the predicted Rayleigh-wave arrivals and the misfit gradient at every iteration. This procedure, denoted as wave-equation Qs tomography (WQs), does not require the assumption of a layered model and tends to have fast and robust convergence compared to Q full waveform inversion (Q-FWI). Numerical examples with synthetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation to the subsur-face Qs distribution as long as the Vs model is known with sufficient accuracy.

Wave-equation Qs Inversion of Skeletonized Surface Waves

KAUST Repository

Li, Jing; Dutta, Gaurav; Schuster, Gerard T.

2017-01-01

We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals. The optimal Qs model is the one that minimizes the difference in the peak frequencies of the predicted and observed Rayleigh wave arrivals using a gradient-based wave-equation optimization method. Solutions to the viscoelastic wave-equation are used to compute the predicted Rayleigh-wave arrivals and the misfit gradient at every iteration. This procedure, denoted as wave-equation Qs inversion (WQs), does not require the assumption of a layered model and tends to have fast and robust convergence compared to full waveform inversion (FWI). Numerical examples with synthetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation to the subsurface Qs distribution as long as the Vs model is known with sufficient accuracy.

Erosion resistance comparison of alternative surface treatments

Science.gov (United States)

Česánek, Z.; Schubert, J.; Houdková, Š.

2017-05-01

Erosion is a process characterized by the particle separation and the damage of component functional surfaces. Thermal spraying technology HP/HVOF (High Pressure / High Velocity Oxygen Fuel) is commonly used for protection of component surfaces against erosive wear. Alloy as well as cermet based coatings meet the requirements for high erosion resistance. Wear resistance is in many cases the determining property of required component functioning. The application suitability of coating materials is particularly influenced by different hardness. This paper therefore presents an erosion resistance comparison of alloy and cermet based coatings. The coatings were applied on steel substrates and were subjected to the erosive test using the device for evaluation of material erosion resistance working on the principle of centrifugal erodent flow. Abrasive sand Al2O3 with grain size 212-250 μm was selected as an erosive material. For this purpose, the specimens were prepared by thermal spraying technology HP/HVOF using commercially available powders Stellite 6, NiCrBSi, Cr3C2-25%NiCr, Cr3C2-25%CoNiCrAlY, Hastelloy C-276 and experimental coating TiMoCN-29% Ni. Erosion resistance of evaluated coatings was compared with erosive resistance of 1.4923 high alloyed steel without nitridation and in nitrided state and further with surface treatment using technology PVD. According to the evaluation, the resulting erosive resistance depends not only on the selected erodent and surface protection, but also on the erodent impact angle.

Aspheric surface testing by irradiance transport equation

Science.gov (United States)

Shomali, Ramin; Darudi, Ahmad; Nasiri, Sadollah; Asgharsharghi Bonab, Armir

2010-10-01

In this paper a method for aspheric surface testing is presented. The method is based on solving the Irradiance Transport Equation (ITE).The accuracy of ITE normally depends on the amount of the pick to valley of the phase distribution. This subject is investigated by a simulation procedure.

Effect of surfaces similarity on contact resistance of fractal rough surfaces under cyclic loading

Science.gov (United States)

Gao, Yuanwen; Liu, Limei; Ta, Wurui; Song, Jihua

2018-03-01

Although numerous studies have shown that contact resistance depends significantly on roughness and fractal dimension, it remains elusive how they affect contact resistance between rough surfaces. The interface similarity index is first proposed to describe the similarity of the contact surfaces, which gives a good indication of the actual contact area between surfaces. We reveal that the surfaces' similarity be an origin of contact resistance variation. The cyclic loading can increase the contact stiffness, and the contact stiffness increases with the increase of the interface similarity index. These findings explain the mechanism of surface roughness and fractal dimension on contact resistance, and also provide reference for the reliability design of the electrical connection.

Skeletonized wave equation of surface wave dispersion inversion

KAUST Repository

Li, Jing

2016-09-06

We present the theory for wave equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. Similar to wave-equation travel-time inversion, the complicated surface-wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the (kx,ω) domain. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2D or 3D velocity models. This procedure, denoted as wave equation dispersion inversion (WD), does not require the assumption of a layered model and is less prone to the cycle skipping problems of full waveform inversion (FWI). The synthetic and field data examples demonstrate that WD can accurately reconstruct the S-wave velocity distribution in laterally heterogeneous media.

Numerical solution of the resistive magnetohydrodynamic boundary-layer equations

International Nuclear Information System (INIS)

Glasser, A.H.; Jardin, S.C.; Tesauro, G.

1983-10-01

Three different techniques are presented for numerical solution of the equations governing the boundary layer of resistive magnetohydrodynamic tearing and interchange instabilities in toroidal geometry. Excellent agreement among these methods and with analytical results provides confidence in the correctness of the results. Solutions obtained in regimes where analytical medthods fail indicate a new scaling for the tearing mode as well as the existence of a new regime of stability

[Corrosion resistant properties of different anodized microtopographies on titanium surfaces].

Science.gov (United States)

Fangjun, Huo; Li, Xie; Xingye, Tong; Yueting, Wang; Weihua, Guo; Weidong, Tian

2015-12-01

To investigate the corrosion resistant properties of titanium samples prepared by anodic oxidation with different surface morphologies. Pure titanium substrates were treated by anodic oxidation to obtain porous titanium films in micron, submicron, and micron-submicron scales. The surface morphologies, coating cross-sectional morphologies, crystalline structures, and surface roughness of these samples were characterized. Electrochemical technique was used to measure the corrosion potential (Ecorr), current density of corrosion (Icorr), and polarization resistance (Rp) of these samples in a simulated body fluid. Pure titanium could be modified to exhibit different surface morphologies by the anodic oxidation technique. The Tafel curve results showed that the technique can improve the corrosion resistance of pure titanium. Furthermore, the corrosion resistance varied with different surface morphologies. The submicron porous surface sample demonstrated the best corrosion resistance, with maximal Ecorr and Rp and minimal Icorr. Anodic oxidation technology can improve the corrosion resistance of pure titanium in a simulated body fluid. The submicron porous surface sample exhibited the best corrosion resistance because of its small surface area and thick barrier layer.

The Closest Point Method and Multigrid Solvers for Elliptic Equations on Surfaces

KAUST Repository

Chen, Yujia

2015-01-01

© 2015 Society for Industrial and Applied Mathematics. Elliptic partial differential equations are important from both application and analysis points of view. In this paper we apply the closest point method to solve elliptic equations on general curved surfaces. Based on the closest point representation of the underlying surface, we formulate an embedding equation for the surface elliptic problem, then discretize it using standard finite differences and interpolation schemes on banded but uniform Cartesian grids. We prove the convergence of the difference scheme for the Poisson\\'s equation on a smooth closed curve. In order to solve the resulting large sparse linear systems, we propose a specific geometric multigrid method in the setting of the closest point method. Convergence studies in both the accuracy of the difference scheme and the speed of the multigrid algorithm show that our approaches are effective.

Surface resistance of superconductors - examples from Nb - O systems

International Nuclear Information System (INIS)

Palmer, F.

1988-01-01

The observed surface resistance of most superconductors can be written as the sum of two terms. R/sub obs/ = R/sub BCS/ + R/sub res/. This paper is divided into three sections. The first section describes the BCS theory of surface resistance in terms of a simplified two-fluid model. The second section describes several possible causes of residual resistance including normal conducting materials, tunneling across cracks in the surface, and direct generation of phonons by the RF electric field. The last section describes recent experiments having to do with the effects of oxide layers on surface resistance. Layers grown in pure oxygen at room temperature were found to have little or no effect, but if these layers are heated to temperatures near 300 0 C, they can alter both the BCS resistance and the residual resistance. Heated oxide layers also increased the dependence of the residual resistance on ambient magnetic field. 31 references, 13 figures, 3 tables

Explicit frequency equations of free vibration of a nonlocal Timoshenko beam with surface effects

Science.gov (United States)

Zhao, Hai-Sheng; Zhang, Yao; Lie, Seng-Tjhen

2018-02-01

Considerations of nonlocal elasticity and surface effects in micro- and nanoscale beams are both important for the accurate prediction of natural frequency. In this study, the governing equation of a nonlocal Timoshenko beam with surface effects is established by taking into account three types of boundary conditions: hinged-hinged, clamped-clamped and clamped-hinged ends. For a hinged-hinged beam, an exact and explicit natural frequency equation is obtained. However, for clamped-clamped and clamped-hinged beams, the solutions of corresponding frequency equations must be determined numerically due to their transcendental nature. Hence, the Fredholm integral equation approach coupled with a curve fitting method is employed to derive the approximate fundamental frequency equations, which can predict the frequency values with high accuracy. In short, explicit frequency equations of the Timoshenko beam for three types of boundary conditions are proposed to exhibit directly the dependence of the natural frequency on the nonlocal elasticity, surface elasticity, residual surface stress, shear deformation and rotatory inertia, avoiding the complicated numerical computation.

Surface electrical resistivity of insulators

International Nuclear Information System (INIS)

Senn, B. C.; Liesegang, J.

1996-01-01

A method is presented here for measuring surface charge decay, and theory has been developed so as to produce determinations of resistivity in the surface region of insulator films or wafers. This method incorporates the use of a coaxial cylindrical capacitor arrangement and an electrometer interfaced to a PC. The charge transport theory given here is based on Mott-Gurney diffusion, and allows easy interpretation of the experimental data, especially for the initial phase of surface charge decay. Resistivity measurements are presented for glass, mica, perspex and polyethylene, covering a range of 10 9 to 10 18 Ωm, as an illustration of the useful range of the instrument for static and antistatic materials, particularly in film or sheet form. Values for the surface charge diffusion constants of the materials are also presented. The charge transport theory has also been extended to allow the experimental and computational theoretical comparison of surface charge decay not only over the initial phase of charge decay, but also over longer times. The theoretical predictions show excellent agreement with experiment using the values for the diffusion constants referred to above

Solution of the Helmholtz-Poincare Wave Equation using the coupled boundary integral equations and optimal surface eigenfunctions

International Nuclear Information System (INIS)

Werby, M.F.; Broadhead, M.K.; Strayer, M.R.; Bottcher, C.

1992-01-01

The Helmholtz-Poincarf Wave Equation (H-PWE) arises in many areas of classical wave scattering theory. In particular it can be found for the cases of acoustical scattering from submerged bounded objects and electromagnetic scattering from objects. The extended boundary integral equations (EBIE) method is derived from considering both the exterior and interior solutions of the H-PWECs. This coupled set of expressions has the advantage of not only offering a prescription for obtaining a solution for the exterior scattering problem, but it also obviates the problem of irregular values corresponding to fictitious interior eigenvalues. Once the coupled equations are derived, they can be obtained in matrix form by expanding all relevant terms in partial wave expansions, including a bi-orthogonal expansion of the Green's function. However some freedom in the choice of the surface expansion is available since the unknown surface quantities may be expanded in a variety of ways so long as closure is obtained. Out of many possible choices, we develop an optimal method to obtain such expansions which is based on the optimum eigenfunctions related to the surface of the object. In effect, we convert part of the problem (that associated with the Fredholms integral equation of the first kind) an eigenvalue problem of a related Hermitian operator. The methodology will be explained in detail and examples will be presented

Surface morphology modelling for the resistivity analysis of low temperature sputtered indium tin oxide thin films on polymer substrates

International Nuclear Information System (INIS)

Yin Xuesong; Tang Wu; Weng Xiaolong; Deng Longjiang

2009-01-01

Amorphous or weakly crystalline indium tin oxide (ITO) thin film samples have been prepared on polymethylmethacrylate and polyethylene terephthalate substrates by RF-magnetron sputtering at a low substrate temperature. The surface morphological and electrical properties of the ITO layers were measured by atomic force microscopy (AFM) and a standard four-point probe measurement. The effect of surface morphology on the resistivity of ITO thin films was studied, which presented some different variations from crystalline films. Then, a simplified film system model, including the substrate, continuous ITO layer and ITO surface grain, was proposed to deal with these correlations. Based on this thin film model and the AFM images, a quadratic potential was introduced to simulate the characteristics of the ITO surface morphology, and the classical Kronig-Penney model, the semiconductor electrical theory and the modified Neugebauer-Webb model were used to expound the detailed experimental results. The modelling equation was highly in accord with the experimental variations of the resistivity on the characteristics of the surface morphology.

Linearised collective Schroedinger equation for nuclear quadrupole surface vibrations

International Nuclear Information System (INIS)

Greiner, M.; Heumann, D.; Scheid, W.

1990-11-01

The linearisation of the Schroedinger equation for nuclear quadrupole surface vibrations yields a new spin degree of freedom, which is called collective spin and has a value of 3/2. With the introduction of collective spin dependent potentials, this linearised Schroedinger equation is then used for the description of low energy spectra and electromagnetic transition probabilities of some even-odd Xe, Ir and Au nuclei which have a spin 3/2 in their groundstate. (orig.)

Navier-Stokes Computations With One-Equation Turbulence Model for Flows Along Concave Wall Surfaces

Science.gov (United States)

Wang, Chi R.

2005-01-01

This report presents the use of a time-marching three-dimensional compressible Navier-Stokes equation numerical solver with a one-equation turbulence model to simulate the flow fields developed along concave wall surfaces without and with a downstream extension flat wall surface. The 3-D Navier- Stokes numerical solver came from the NASA Glenn-HT code. The one-equation turbulence model was derived from the Spalart and Allmaras model. The computational approach was first calibrated with the computations of the velocity and Reynolds shear stress profiles of a steady flat plate boundary layer flow. The computational approach was then used to simulate developing boundary layer flows along concave wall surfaces without and with a downstream extension wall. The author investigated the computational results of surface friction factors, near surface velocity components, near wall temperatures, and a turbulent shear stress component in terms of turbulence modeling, computational mesh configurations, inlet turbulence level, and time iteration step. The computational results were compared with existing measurements of skin friction factors, velocity components, and shear stresses of the developing boundary layer flows. With a fine computational mesh and a one-equation model, the computational approach could predict accurately the skin friction factors, near surface velocity and temperature, and shear stress within the flows. The computed velocity components and shear stresses also showed the vortices effect on the velocity variations over a concave wall. The computed eddy viscosities at the near wall locations were also compared with the results from a two equation turbulence modeling technique. The inlet turbulence length scale was found to have little effect on the eddy viscosities at locations near the concave wall surface. The eddy viscosities, from the one-equation and two-equation modeling, were comparable at most stream-wise stations. The present one-equation

In vivo measurement of vocal fold surface resistance.

Science.gov (United States)

Mizuta, Masanobu; Kurita, Takashi; Dillon, Neal P; Kimball, Emily E; Garrett, C Gaelyn; Sivasankar, M Preeti; Webster, Robert J; Rousseau, Bernard

2017-10-01

A custom-designed probe was developed to measure vocal fold surface resistance in vivo. The purpose of this study was to demonstrate proof of concept of using vocal fold surface resistance as a proxy of functional tissue integrity after acute phonotrauma using an animal model. Prospective animal study. New Zealand White breeder rabbits received 120 minutes of airflow without vocal fold approximation (control) or 120 minutes of raised intensity phonation (experimental). The probe was inserted via laryngoscope and placed on the left vocal fold under endoscopic visualization. Vocal fold surface resistance of the middle one-third of the vocal fold was measured after 0 (baseline), 60, and 120 minutes of phonation. After the phonation procedure, the larynx was harvested and prepared for transmission electron microscopy. In the control group, vocal fold surface resistance values remained stable across time points. In the experimental group, surface resistance (X% ± Y% relative to baseline) was significantly decreased after 120 minutes of raised intensity phonation. This was associated with structural changes using transmission electron microscopy, which revealed damage to the vocal fold epithelium after phonotrauma, including disruption of the epithelium and basement membrane, dilated paracellular spaces, and alterations to epithelial microprojections. In contrast, control vocal fold specimens showed well-preserved stratified squamous epithelia. These data demonstrate the feasibility of measuring vocal fold surface resistance in vivo as a means of evaluating functional vocal fold epithelial barrier integrity. Device prototypes are in development for additional testing, validation, and for clinical applications in laryngology. NA Laryngoscope, 127:E364-E370, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

Tokamak m = 1 magnetohydrodynamic calculations in toroidal geometry using a full set of nonlinear resistive magnetohydrodynamic equations

International Nuclear Information System (INIS)

Charlton, L.A.; Carreras, B.A.; Holmes, J.A.; Lynch, V.E.

1988-01-01

The linear stability and nonlinear evolution of the resistive m = 1 mode in tokamaks is studied using a full set of resistive magnetohydrodynamic (MHD) equations in toroidal geometry. The modification of the linear and nonlinear properties of the mode by a combination of strong toroidal effects and low resistivity is the focus of this work. Linearly there is a transition from resistive kink to resistive tearing behavior as the aspect ratio and resistivity are reduced, and there is a corresponding modification of the nonlinear behavior, including a slowing of the island growth and development of a Rutherford regime, as the tearing regime is approached. In order to study the sensitivity of the stability and evolution to assumptions concerning the equation of state, two sets of full nonlinear resistive MHD equations (a pressure convection set and an incompressible set) are used. Both sets give more stable nonlinear behavior as the aspect ratio is reduced. The pressure convection set shows a transition from a Kadomtsev reconnection at large aspect ratio to a saturation at small aspect ratio. The incompressible set yields Kadomtsev reconnection for all aspect ratios, but with a significant lengthening of the reconnection time and development of a Rutherford regime at an aspect ratio approaching the transition from a resistive kink mode to a tearing mode. The pressure convection set gives an incomplete reconnection similar to that sometimes seen experimentally. The pressure convection set is, however, strictly justified only at high beta

Surface Corrosion Resistance in Turning of Titanium Alloy

Directory of Open Access Journals (Sweden)

Rui Zhang

2015-01-01

Full Text Available This work addresses the issues associated with implant surface modification. We propose a method to form the oxide film on implant surfaces by dry turning to generate heat and injecting oxygen-rich gas at the turning-tool flank. The morphology, roughness, composition, and thickness of the oxide films in an oxygen-rich atmosphere were characterized using scanning electron microscopy, optical profiling, and Auger electron spectroscopy. Electrochemical methods were used to study the corrosion resistance of the modified surfaces. The corrosion resistance trends, analyzed relative to the oxide film thickness, indicate that the oxide film thickness is the major factor affecting the corrosion resistance of titanium alloys in a simulated body fluid (SBF. Turning in an oxygen-rich atmosphere can form a thick oxide film on the implant surface. The thickness of surface oxide films processed at an oxygen concentration of 80% was improved to 4.6 times that of films processed at an oxygen concentration of 21%; the free corrosion potential shifted positively by 0.357 V, which significantly improved the corrosion resistance of titanium alloys in the SBF. Therefore, the proposed method may (partially replace the subsequent surface oxidation. This method is significant for biomedical development because it shortens the process flow, improves the efficiency, and lowers the cost.

Investigation of Floor Surface Finishes for Optimal Slip Resistance Performance

Directory of Open Access Journals (Sweden)

In-Ju Kim

2018-03-01

Full Text Available Background: Increasing the slip resistance of floor surfaces would be desirable, but there is a lack of evidence on whether traction properties are linearly correlated with the topographic features of the floor surfaces or what scales of surface roughness are required to effectively control the slipperiness of floors. Objective: This study expands on earlier findings on the effects of floor surface finishes against slip resistance performance and determines the operative ranges of floor surface roughness for optimal slip resistance controls under different risk levels of walking environments. Methods: Dynamic friction tests were conducted among three shoes and nine floor specimens under wet and oily environments and compared with a soapy environment. Results: The test results showed the significant effects of floor surface roughness on slip resistance performance against all the lubricated environments. Compared with the floor-type effect, the shoe-type effect on slip resistance performance was insignificant against the highly polluted environments. The study outcomes also indicated that the oily environment required rougher surface finishes than the wet and soapy ones in their lower boundary ranges of floor surface roughness. Conclusion: The results of this study with previous findings confirm that floor surface finishes require different levels of surface coarseness for different types of environmental conditions to effectively manage slippery walking environments. Collected data on operative ranges of floor surface roughness seem to be a valuable tool to develop practical design information and standards for floor surface finishes to efficiently prevent pedestrian fall incidents. Keywords: floor surface finishes, operational levels of floor surface roughness, slip resistance, wet, soapy and oily environments

A Relation Between the Eikonal Equation Associated to a Potential Energy Surface and a Hyperbolic Wave Equation.

Science.gov (United States)

Bofill, Josep Maria; Quapp, Wolfgang; Caballero, Marc

2012-12-11

The potential energy surface (PES) of a molecule can be decomposed into equipotential hypersurfaces. We show in this article that the hypersurfaces are the wave fronts of a certain hyperbolic partial differential equation, a wave equation. It is connected with the gradient lines, or the steepest descent, or the steepest ascent lines of the PES. The energy seen as a reaction coordinate plays the central role in this treatment.

Theoretical study of the surface resistivity of (111) surfaces of NixPt1-x(111) alloys

International Nuclear Information System (INIS)

Rous, P. J.

2001-01-01

A layer-Korringa - Kohn - Rostoker calculation is used to study the compositional dependence of the surface resistivity of the (111) surface of Ni x Pt 1-x (111) alloys. The compositional disorder in the bulk and at the surface is described by the coherent potential approximation. If it is assumed that the atomic planes near the (111) surface Ni x Pt 1-x have the same composition as the bulk layers, then a weak Nordheim effect is observed in the compositional dependence of the surface resistivity. However, we show that surface segregation in Ni x Pt 1-x (111) causes an inverse Nordheim dependence in the actual surface resistivity as the bulk composition is varied. [copyright] 2001 American Institute of Physics

Impact of Volcanic Ash on Road and Airfield Surface Skid Resistance

Directory of Open Access Journals (Sweden)

Daniel M. Blake

2017-08-01

Full Text Available Volcanic ash deposited on paved surfaces during volcanic eruptions often compromises skid resistance, which is a major component of safety. We adopt the British pendulum test method in laboratory conditions to investigate the skid resistance of road asphalt and airfield concrete surfaces covered by volcanic ash sourced from various locations in New Zealand. Controlled variations in ash characteristics include type, depth, wetness, particle size and soluble components. We use Stone Mastic Asphalt (SMA for most road surface experiments but also test porous asphalt, line-painted road surfaces, and a roller screed concrete mix used for airfields. Due to their importance for skid resistance, SMA surface macrotexture and microtexture are analysed with semi-quantitative image analysis, microscopy and a standardised sand patch volumetric test, which enables determination of the relative effectiveness of different cleaning techniques. We find that SMA surfaces covered by thin deposits (~1 mm of ash result in skid resistance values slightly lower than those observed on wet uncontaminated surfaces. At these depths, a higher relative soluble content for low-crystalline ash and a coarser particle size results in lower skid resistance. Skid resistance results for relatively thicker deposits (3–5 mm of non-vesiculated basaltic ash are similar to those for thin deposits. There are similarities between road asphalt and airfield concrete, although there is little difference in skid resistance between bare airfield surfaces and airfield surfaces covered by 1 mm of ash. Based on our findings, we provide recommendations for maintaining road safety and effective cleaning techniques in volcanic ash environments.

Photochemical surface modification of PP for abrasion resistance

International Nuclear Information System (INIS)

Bahners, Thomas; Haessler, Ruediger; Gao Shanglin; Maeder, Edith; Wego, Andreas; Schollmeyer, Eckhard

2009-01-01

The potential of a photo-chemical approach to increase the surface hardness of polypropylene (PP) has been studied. Using a 222 nm excimer lamp, fibers and film were irradiated in the presence of multi-functional substances diallylphthalate (DAP), tetraallyloxyethane (TAE), and pentaerithritoltriacylate (PETA) and characterized with regard to the resulting effect on abrasion resistance. AFM-based methods were employed to analyze thermo-mechanical surface properties. Nanoindentation and microthermal analyses of the outermost surface layers of UV treated fibers gave clear indications of an effective cross-linking of reactive substances present during irradiation. One may assume that the reactive media polymerize on top of the surface of the PP substrate and form a thin-layer. The abrasion resistance of the PP fibers was tested by applying stress through a rotating and axially oscillating roller of defined roughness and measuring the mass loss as a function of time. The abrasion resistance was found to be remarkably improved compared to the untreated fiber. Best effects were achieved using PETA as reactive substance. The experiments clearly showed the influence of processing conditions, namely with regard to homogeneous coverage of the substrate surface with the reactive medium.

The Use of Nonlinear Constitutive Equations to Evaluate Draw Resistance and Filter Ventilation

Directory of Open Access Journals (Sweden)

Eitzinger B

2014-12-01

Full Text Available This study investigates by nonlinear constitutive equations the influence of tipping paper, cigarette paper, filter, and tobacco rod on the degree of filter ventilation and draw resistance. Starting from the laws of conservation, the path to the theory of fluid dynamics in porous media and Darcy's law is reviewed and, as an extension to Darcy's law, two different nonlinear pressure drop-flow relations are proposed. It is proven that these relations are valid constitutive equations and the partial differential equations for the stationary flow in an unlit cigarette covering anisotropic, inhomogeneous and nonlinear behaviour are derived. From these equations a system of ordinary differential equations for the one-dimensional flow in the cigarette is derived by averaging pressure and velocity over the cross section of the cigarette. By further integration, the concept of an electrical analog is reached and discussed in the light of nonlinear pressure drop-flow relations. By numerical calculations based on the system of ordinary differential equations, it is shown that the influence of nonlinearities cannot be neglected because variations in the degree of filter ventilation can reach up to 20% of its nominal value.

Alternating-direction implicit numerical solution of the time-dependent, three-dimensional, single fluid, resistive magnetohydrodynamic equations

Energy Technology Data Exchange (ETDEWEB)

Finan, C.H. III

1980-12-01

Resistive magnetohydrodynamics (MHD) is described by a set of eight coupled, nonlinear, three-dimensional, time-dependent, partial differential equations. A computer code, IMP (Implicit MHD Program), has been developed to solve these equations numerically by the method of finite differences on an Eulerian mesh. In this model, the equations are expressed in orthogonal curvilinear coordinates, making the code applicable to a variety of coordinate systems. The Douglas-Gunn algorithm for Alternating-Direction Implicit (ADI) temporal advancement is used to avoid the limitations in timestep size imposed by explicit methods. The equations are solved simultaneously to avoid syncronization errors.

Global solvability, non-resistive limit and magnetic boundary layer of the compressible heat-conductive MHD equations

OpenAIRE

Zhang, Jianwen; Zhao, Xiaokui

2015-01-01

In general, the resistivity is inversely proportional to the electrical conductivity, and is usually taken to be zero when the conducting fluid is of extremely high conductivity (e.g., ideal conductors). In this paper, we first establish the global well-posedness of strong solution to an initial-boundary value problem of the one-dimensional compressible, viscous, heat-conductive, non-resistive MHD equations with general heat-conductivity coefficient and large data. Then, the non-resistive lim...

Inductive Eigenmodes of a resistive toroidal surface in vacuum

International Nuclear Information System (INIS)

Lo Surdo, C.

1999-01-01

In this paper it has been studied the Electro-Magnetic (EM) Eigenmodes, sufficiently slow as to legitimate the pre-Maxwell approximation of Maxwell's system (or inductive Eigenmodes), of a given smooth, toroidal-unknotted, electrically resistive surface Τ with given smooth (surface) resistivity 0 d egree 3 . Within the above limitations (to be made more precise), the geometry of Τ is arbitrary. With the eigenvalue associated with the generic Eigenmode being defined as the opposite of its logarithmic time-derivative, one expects that the resulting spectrum be discrete and strictly positive. It shall be interested into the degenerate case where Τ be cut (i.e. electrically broken) along one or more of its irreducible cycles. This case will be analyzed autonomously, rather than as a limit (for ρ d egree → ∞ along the cuts) of the regular case. Without cuts, the Eigenproblem under consideration is nothing but the two-dimensional (2-dim) generalization of the classical case of a smooth, unknotted, electrically conductive, simple coil in infinite vacuum. Its analysis hinges on the classical potential theory, and turns out to be a special application of the linear, integrodifferential (elliptic) equation theory on a compact, multiply connected, 2-dim manifold. The attention and approach will be confined to strong (or classical) solutions, both in Τ and C Τ = R 3 / Τ. This study is divided in two parts: a General Part (Sects 1 divided 4) is devoted to the case of generic Τ and ρ d egree (within the convenient smoothness requirements), whereas a Special Part (Sects 5 divided 7) deals with the (more or less formal) discussion of a couple of particular cases (Τ ≡ a canonical torus), both of which with uniform ρ d egree. Some propaedeutical/supplementary information is provided in a number of Appendices [it

A new capacitive/resistive probe method for studying magnetic surfaces

International Nuclear Information System (INIS)

Kitajima, Sumio; Takayama, Masakazu; Zama, Tatsuya; Takaya, Kazuhiro; Takeuchi, Nobunao; Watanabe, Hiroshige

1991-01-01

A new capacitive/resistive probe method for mapping the magnetic surfaces from resistance or capacitance between a magnetic surface and a vacuum vessel was developed and tested. Those resistances and capacitances can be regarded as components of a simple electrical bridge circuit. This method exploits electrical transient response of the bridge circuit for a square pulse. From equiresistance or equicapacitance points, the magnetic surface structure can be deduced. Measurements on the Tohoku University Heliac, which is a small-size standard heliac, show good agreement with numerical calculations. This method is particularly useful for pulse-operated machines. (author)

An open circuit voltage equation enabling separation of cathode and anode polarization resistances of ceria electrolyte based solid oxide fuel cells

Science.gov (United States)

Zhang, Yanxiang; Chen, Yu; Yan, Mufu

2017-07-01

The open circuit voltage (OCV) of solid oxide fuel cells is generally overestimated by the Nernst equation and the Wagner equation, due to the polarization losses at electrodes. Considering both the electronic conduction of electrolyte and the electrode polarization losses, we express the OCV as an implicit function of the characteristic oxygen pressure of electrolyte (p* [atm], at which the electronic and ionic conductivities are the same), and the relative polarization resistance of electrodes (rc = Rc/Ri and ra = Ra/Ri, where Ri/c/a [Ωcm2] denotes the ionic resistance of electrolyte, and the polarization resistances of cathode and anode, respectively). This equation approaches to the Wagner equation when the electrodes are highly active (rc and ra → 0), and approaches to the Nernst equation when the electrolyte is a purely ionic conductor (p* → 0). For the fuel cells whose OCV is well below the prediction of the Wagner equation, for example with thin doped ceria electrolyte, it is demonstrated that the combination of OCV and impedance spectroscopy measurements allows the determination of p*, Rc and Ra. This equation can serve as a simple yet powerful tool to study the internal losses in the cell under open circuit condition.

Estimation of monthly solar exposure on horizontal surface by Angstrom-type regression equation

International Nuclear Information System (INIS)

Ravanshid, S.H.

1981-01-01

To obtain solar flux intensity, solar radiation measuring instruments are the best. In the absence of instrumental data there are other meteorological measurements which are related to solar energy and also it is possible to use empirical relationships to estimate solar flux intensit. One of these empirical relationships to estimate monthly averages of total solar radiation on a horizontal surface is the modified angstrom-type regression equation which has been employed in this report in order to estimate the solar flux intensity on a horizontal surface for Tehran. By comparing the results of this equation with four years measured valued by Tehran's meteorological weather station the values of meteorological constants (a,b) in the equation were obtained for Tehran. (author)

On the initial condition problem of the time domain PMCHWT surface integral equation

KAUST Repository

Uysal, Ismail Enes

2017-05-13

Non-physical, linearly increasing and constant current components are induced in marching on-in-time solution of time domain surface integral equations when initial conditions on time derivatives of (unknown) equivalent currents are not enforced properly. This problem can be remedied by solving the time integral of the surface integral for auxiliary currents that are defined to be the time derivatives of the equivalent currents. Then the equivalent currents are obtained by numerically differentiating the auxiliary ones. In this work, this approach is applied to the marching on-in-time solution of the time domain Poggio-Miller-Chan-Harrington-Wu-Tsai surface integral equation enforced on dispersive/plasmonic scatterers. Accuracy of the proposed method is demonstrated by a numerical example.

Surface Resistance Measurements of LHC Dipole Beam Screen Samples

CERN Document Server

Caspers, Friedhelm; Ruggiero, F; Tan, J; Tsutsui, H

2000-01-01

An estimate of the resistive losses in the LHC dipole beam screen is given from cold surface resistance measurements using the shielded pair technique. Several beam screen samples have been evaluated, with different copper coating methods, including a sample with ribbed surface envisaged to reduce electron cloud losses thanks to its low reflectivity. Experimental data, derived by a proper analysis of the measured Q-factors and including error estimates are compared with theoretical predictions of the anomalous skin effect.

Mapping the Qademah Fault with Traveltime, Surface-wave, and Resistivity Tomograms

KAUST Repository

Hanafy, Sherif M.

2015-08-19

Traveltime, surface-wave, and resistivity tomograms are used to track the buried Qademah fault located near King Abdullah Economic City (KAEC), Saudi Arabia. The fault location is confirmed by the 1) resistivity tomogram obtained from an electrical resistivity experiment, 2) the refraction traveltime tomogram, 3) the reflection image computed from 2D seismic data set recorded at the northern part of the fault, and 4) the surface-wave tomogram.

Mapping the Qademah Fault with Traveltime, Surface-wave, and Resistivity Tomograms

KAUST Repository

Hanafy, Sherif M.

2015-01-01

Traveltime, surface-wave, and resistivity tomograms are used to track the buried Qademah fault located near King Abdullah Economic City (KAEC), Saudi Arabia. The fault location is confirmed by the 1) resistivity tomogram obtained from an electrical resistivity experiment, 2) the refraction traveltime tomogram, 3) the reflection image computed from 2D seismic data set recorded at the northern part of the fault, and 4) the surface-wave tomogram.

Aging of residual surface resistance of superconducting lead cavities

DEFF Research Database (Denmark)

Danielsen, M.

1972-01-01

Measurements of the residual surface resistance of superconducting lead cavities as a function of time during a period of a month showed an oscillating variation. An explanation of the ageing curves is proposed. ©1972 The American Institute of Physics......Measurements of the residual surface resistance of superconducting lead cavities as a function of time during a period of a month showed an oscillating variation. An explanation of the ageing curves is proposed. ©1972 The American Institute of Physics...

Analytical approximate equations for the resistivity and its temperature coefficient in thin polycrystalline metallic films

International Nuclear Information System (INIS)

Tellier, C.R.; Tosser, A.J.

1977-01-01

In the usual thickness range of sputtered metallic films, analytical linearized approximate expressions of polycrystalline film resistivity and its t.c.r. are deduced from the Mayadas-Shatzkes theoretical equations. A good experimental fit is observed for Al rf sputtered metal films. (orig.) [de

Laser Surface Alloying of Aluminum for Improving Acid Corrosion Resistance

Science.gov (United States)

Jiru, Woldetinsay Gutu; Sankar, Mamilla Ravi; Dixit, Uday Shanker

2018-04-01

In the present study, laser surface alloying of aluminum with magnesium, manganese, titanium and zinc, respectively, was carried out to improve acid corrosion resistance. Laser surface alloying was conducted using 1600 and 1800 W power source using CO2 laser. Acid corrosion resistance was tested by dipping the samples in a solution of 2.5% H2SO4 for 200 h. The weight loss due to acid corrosion was reduced by 55% for AlTi, 41% for AlMg alloy, 36% for AlZn and 22% for AlMn alloy. Laser surface alloyed samples offered greater corrosion resistance than the aluminum substrate. It was observed that localized pitting corrosion was the major factor to damage the surface when exposed for a long time. The hardness after laser surface alloying was increased by a factor of 8.7, 3.4, 2.7 and 2 by alloying with Mn, Mg, Ti and Zn, respectively. After corrosion test, hardness was reduced by 51% for AlTi sample, 40% for AlMg sample, 41.4% for AlMn sample and 33% for AlZn sample.

Tailoring surface properties of ArF resists thin films with functionally graded materials (FGM)

Science.gov (United States)

Takemoto, Ichiki; Ando, Nobuo; Edamatsu, Kunishige; Fuji, Yusuke; Kuwana, Koji; Hashimoto, Kazuhiko; Funase, Junji; Yokoyama, Hiroyuki

2007-03-01

Our recent research effort has been focused on new top coating-free 193nm immersion resists with regard to leaching of the resist components and lithographic performance. We have examined methacrylate-based resins that control the surface properties of ArF resists thin films by surface segregation behavior. For a better understanding of the surface properties of thin films, we prepared the six resins (Resin 1-6) that have three types fluorine containing monomers, a new monomer (Monomer A), Monomer B and Monomer C, respectively. We blended the base polymer (Resin 0) with Resin (1-6), respectively. We evaluated contact angles, surface properties and lithographic performances of the polymer blend resists. The static and receding contact angles of the resist that contains Resin (1-6) are greater than that of the base polymer (Resin 0) resist. The chemical composition of the surface of blend polymers was investigated with X-ray photoelectron spectroscopy (XPS). It was shown that there was significant segregation of the fluorine containing resins to the surface of the blend films. We analyzed Quantitative Structure-Property Relationships (QSPR) between the surface properties and the chemical composition of the surface of polymer blend resists. The addition of 10 wt% of the polymer (Resin 1-6) to the base polymer (Resin 0) did not influence the lithographic performance. Consequently, the surface properties of resist thin films can be tailored by the appropriate choice of fluorine containing polymer blends.

Rate equation analysis of hydrogen uptake on Si (100) surfaces

International Nuclear Information System (INIS)

Inanaga, S.; Rahman, F.; Khanom, F.; Namiki, A.

2005-01-01

We have studied the uptake process of H on Si (100) surfaces by means of rate equation analysis. Flowers' quasiequilibrium model for adsorption and desorption of H [M. C. Flowers, N. B. H. Jonathan, A. Morris, and S. Wright, Surf. Sci. 396, 227 (1998)] is extended so that in addition to the H abstraction (ABS) and β 2 -channel thermal desorption (TD) the proposed rate equation further includes the adsorption-induced desorption (AID) and β 1 -TD. The validity of the model is tested by the experiments of ABS and AID rates in the reaction system H+D/Si (100). Consequently, we find it can well reproduce the experimental results, validating the proposed model. We find the AID rate curve as a function of surface temperature T s exhibits a clear anti-correlation with the bulk dangling bond density versus T s curve reported in the plasma-enhanced chemical vapor deposition (CVD) for amorphous Si films. The significance of the H chemistry in plasma-enhanced CVD is discussed

Trapped surfaces in monopole-like Cauchy data of Einstein-Yang-Mills-Higgs equations

International Nuclear Information System (INIS)

Malec, E.; Koc, P.

1989-08-01

We choose the nonabelian monopole solution of Bogomolny, Prasad and Sommerfield as a part of Cauchy data for the evolution of Einstein-Yang-Mills-Higgs equations. Momentarily static spherically symmetric data for gravitational fields are obtained numerically via the Lichnerowicz equation. In the case of generic scaling of fields we have found initial data with trapped surfaces. (author). 13 refs

Interpretation of hole-to-surface resistivity measurements at Yucca Mountain, Nevada Test Site

International Nuclear Information System (INIS)

Daniels, J.J.; Scott, J.H.

1981-01-01

Hole-to-surface resistivity measurements at Yucca Mountain indicate the presence of many near-surface geologic inhomogeneities, with no definite indication of deep structural features. A resistive anomaly near drill hole UE25a-6 is interpreted as a thin, vertical, resistive body that nearly intersects the surface, and may be caused by a silicified, or calcified, fracture zone. A resistive anomaly near hole UE25a-7 is probably caused by a near surface, horizontal, lens-shaped body that may represent a devitrified zone in the Tiva Canyon Member. Many conductive anomalies were detected to the southwest of hole UE25a-4. However, these anomalies are interpreted to be caused by variations in the thickness of the surface alluvium

Bacterial resistance of self-assembled surfaces using PPOm-b-PSBMAn zwitterionic copolymer - concomitant effects of surface topography and surface chemistry on attachment of live bacteria.

Science.gov (United States)

Hsiao, Sheng-Wen; Venault, Antoine; Yang, Hui-Shan; Chang, Yung

2014-06-01

Three well-defined diblock copolymers made of poly(sulfobetaine methacrylate) (poly(SBMA)) and poly(propylene oxide) (PPO) groups were synthesized by atom transfer radical polymerization (ATRP) method. They were physically adsorbed onto three types of surfaces having different topography, including smooth flat surface, convex surface, and indented surface. Chemical state of surfaces was characterized by XPS while the various topographies were examined by SEM and AFM. Hydrophilicity of surfaces was dependent on both the surface chemistry and the surface topography, suggesting that orientation of copolymer brushes can be tuned in the design of surfaces aimed at resisting bacterial attachment. Escherichia coli, Staphylococcus epidermidis, Streptococcus mutans and Escherichia coli with green fluorescent protein (E. coli GFP) were used in bacterial tests to assess the resistance to bacterial attachment of poly(SBMA)-covered surfaces. Results highlighted a drastic improvement of resistance to bacterial adhesion with the increasing of poly(SBMA) to PPO ratio, as well as an important effect of surface topography. The chemical effect was directly related to the length of the hydrophilic moieties. When longer, more water could be entrapped, leading to improved anti-bacterial properties. The physical effect impacted on the orientation of the copolymer brushes, as well as on the surface contact area available. Convex surfaces as well as indented surfaces wafer presented the best resistance to bacterial adhesion. Indeed, bacterial attachment was more importantly reduced on these surfaces compared with smooth surfaces. It was explained by the non-orthogonal orientation of copolymer brushes, resulting in a more efficient surface coverage of zwitterionic molecules. This work suggests that not only the control of surface chemistry is essential in the preparation of surfaces resisting bacterial attachment, but also the control of surface topography and orientation of antifouling

Estimation of subsurface hydrological parameters around Akwuke, Enugu, Nigeria using surface resistivity measurements

International Nuclear Information System (INIS)

Utom, Ahamefula U; Odoh, Benard I; Egboka, Boniface C E; Egboka, Nkechi E; Okeke, Harold C

2013-01-01

As few boreholes may be available and carrying out pumping tests can be expensive and time consuming, relationships between aquifer characteristics and the electrical parameters of different geoelectric layers exist. Data from 19 vertical electrical soundings (VESs; 13 of these selected for evaluation) was recorded with a Schlumberger electrode configuration in the area around Akwuke, Enugu, Nigeria. The data was interpreted by computer iterative modelling with curve matching for calibration purposes. Geoelectric cross-sections along a number of lines were prepared to ascertain the overall distribution of the resistivity responses of the subsurface lithology. Identified probable shallow aquifer resistivity, thickness and depth values are in the range of 28–527 Ωm, 2.1–22.5 m and 3.1–28.3 m respectively. As our aquifer system consists of fine-grained, clay–silty sand materials, a modification of the Archie equations (Waxman–Smits model) was adopted to determine the true formation factor using the relationship between the apparent formation factor and the pore water resistivity. This representation of the effects of a separate conducting path due to the presence of clay particles in the aquifer materials was used in making reliable estimations of aquifer properties. The average hydraulic conductivity of 8.96 × 10 −4 m s −1 transmissivity ranging between 1.88 × 10 −3 and 2.02 × 10 −3 m 2 s −1 estimated from surface resistivity measurements correlated well with the available field data. Results of the study also showed a direct relationship between aquifer transmissivity and modified transverse resistance (R 2 = 0.85). (paper)

Microwave surface resistance of bulk YBa2Cu3O6+x material

Science.gov (United States)

Fathy, A.; Kalokitis, D.; Belohoubek, E.; Sundar, H. G. K.; Safari, A.

1988-10-01

Superconducting Y-Ba-Cu-O samples were prepared by conventional solid-state reaction. The microwave surface resistance of 1:2:3 compound superconductor material was measured in a special disk resonator structure at 10 GHz. At liquid-nitrogen temperatures the microwave surface resistance is comparable to that of Au. At lower temperature (~10 K) the surface resistance is an order of magnitude lower than that of Au at the same temperature.

Non-rigid registration of breast surfaces using the laplace and diffusion equations

Directory of Open Access Journals (Sweden)

Ou Jao J

2010-02-01

Full Text Available Abstract A semi-automated, non-rigid breast surface registration method is presented that involves solving the Laplace or diffusion equations over undeformed and deformed breast surfaces. The resulting potential energy fields and isocontours are used to establish surface correspondence. This novel surface-based method, which does not require intensity images, anatomical landmarks, or fiducials, is compared to a gold standard of thin-plate spline (TPS interpolation. Realistic finite element simulations of breast compression and further testing against a tissue-mimicking phantom demonstrate that this method is capable of registering surfaces experiencing 6 - 36 mm compression to within a mean error of 0.5 - 5.7 mm.

A model expansion criterion for treating surface topography in ray path calculations using the eikonal equation

International Nuclear Information System (INIS)

Ma, Ting; Zhang, Zhongjie

2014-01-01

Irregular surface topography has revolutionized how seismic traveltime is calculated and the data are processed. There are two main schemes for dealing with an irregular surface in the seismic first-arrival traveltime calculation: (1) expanding the model and (2) flattening the surface irregularities. In the first scheme, a notional infill medium is added above the surface to expand the physical space into a regular space, as required by the eikonal equation solver. Here, we evaluate the chosen propagation velocity in the infill medium through ray path tracking with the eikonal equation-solved traveltime field, and observe that the ray paths will be physically unrealistic for some values of this propagation velocity. The choice of a suitable propagation velocity in the infill medium is crucial for seismic processing of irregular topography. Our model expansion criterion for dealing with surface topography in the calculation of traveltime and ray paths using the eikonal equation highlights the importance of both the propagation velocity of the infill physical medium and the topography gradient. (paper)

Averaged RMHD equations

International Nuclear Information System (INIS)

Ichiguchi, Katsuji

1998-01-01

A new reduced set of resistive MHD equations is derived by averaging the full MHD equations on specified flux coordinates, which is consistent with 3D equilibria. It is confirmed that the total energy is conserved and the linearized equations for ideal modes are self-adjoint. (author)

Estimating Daily Global Evapotranspiration Using Penman–Monteith Equation and Remotely Sensed Land Surface Temperature

Directory of Open Access Journals (Sweden)

Roozbeh Raoufi

2017-11-01

Full Text Available Daily evapotranspiration (ET is modeled globally for the period 2000–2013 based on the Penman–Monteith equation with radiation and vapor pressures derived using remotely sensed Land Surface Temperature (LST from the MODerate resolution Imaging Spectroradiometer (MODIS on the Aqua and Terra satellites. The ET for a given land area is based on four surface conditions: wet/dry and vegetated/non-vegetated. For each, the ET resistance terms are based on land cover, leaf area index (LAI and literature values. The vegetated/non-vegetated fractions of the land surface are estimated using land cover, LAI, a simplified version of the Beer–Lambert law for describing light transition through vegetation and newly derived light extension coefficients for each MODIS land cover type. The wet/dry fractions of the land surface are nonlinear functions of LST derived humidity calibrated using in-situ ET measurements. Results are compared to in-situ measurements (average of the root mean squared errors and mean absolute errors for 39 sites are 0.81 mm day−1 and 0.59 mm day−1, respectively and the MODIS ET product, MOD16, (mean bias during 2001–2013 is −0.2 mm day−1. Although the mean global difference between MOD16 and ET estimates is only 0.2 mm day−1, local temperature derived vapor pressures are the likely contributor to differences, especially in energy and water limited regions. The intended application for the presented model is simulating ET based on long-term climate forecasts (e.g., using only minimum, maximum and mean daily or monthly temperatures.

Recent developments on the Kardar-Parisi-Zhang surface-growth equation.

Science.gov (United States)

Wio, Horacio S; Escudero, Carlos; Revelli, Jorge A; Deza, Roberto R; de la Lama, Marta S

2011-01-28

The stochastic nonlinear partial differential equation known as the Kardar-Parisi-Zhang (KPZ) equation is a highly successful phenomenological mesoscopic model of surface and interface growth processes. Its suitability for analytical work, its explicit symmetries and its prediction of an exact dynamic scaling relation for a one-dimensional substratum led people to adopt it as a 'standard' model in the field during the last quarter of a century. At the same time, several conjectures deserving closer scrutiny were established as dogmas throughout the community. Among these, we find the beliefs that 'genuine' non-equilibrium processes are non-variational in essence, and that the exactness of the dynamic scaling relation owes its existence to a Galilean symmetry. Additionally, the equivalence among planar and radial interface profiles has been generally assumed in the literature throughout the years. Here--among other topics--we introduce a variational formulation of the KPZ equation, remark on the importance of consistency in discretization and challenge the mainstream view on the necessity for scaling of both Galilean symmetry and the one-dimensional fluctuation-dissipation theorem. We also derive the KPZ equation on a growing domain as a first approximation to radial growth, and outline the differences with respect to the classical case that arises in this new situation.

A new surface resistance measurement method with ultrahigh sensitivity

International Nuclear Information System (INIS)

Liang, Changnian.

1993-01-01

A superconducting niobium triaxial cavity has been designed and fabricated to study residual surface resistance of planar superconducting materials. The edge of a 25.4 mm or larger diameter sample in the triaxial cavity is located outside the strong field region. Therefore, the edge effects and possible losses between the thin film and the substrate have been minimized, ensuring that induced RF losses are intrinsic to the test material. The fundamental resonant frequency of the cavity is the same as the working frequency of CEBAF cavities. The cavity has a compact size compared to its TE 011 counterpart, which makes it more sensitive to the sample's loss. For even higher sensitivity, a calorimetry method has been used to measure the RF losses on the superconducting sample. At 2 K, a 2 μK temperature change can be resolved by using carbon resistor sensors. The temperature distribution caused by RF heating is measured by 16 carbon composition resistor sensors. A 0.05 μW heating power can be detected as such a resolution, which translates to a surface resistance of 0.02 nΩ at a surface magnetic field of 52 Oe. This is the most sensitive device for surface resistance measurements to date. In addition, losses due to the indium seal, coupling probes, field emission sites other than the sample, and all of the high field resonator surface, are excluded in the measurement. Surface resistance of both niobium and high-Tc superconducting thin films has been measured. A low R s of 35.2 μΩ was measured for a 25.4 mm diameter YBa 2 Cu 3 O 7 thin film at 1.5 GHz and at 2 K. The measurement result is the first result for a large area epitaxially grown thin film sample at such a low RF frequency. The abrupt disappearance of multipacting between two parallel plates has been observed and monitored with the 16 temperature mapping sensors. Field emission or some field dependent anomalous RF losses on the niobium plate have also been observed

A Modular Approach to Model Oscillating Control Surfaces Using Navier Stokes Equations

Science.gov (United States)

Guruswamy, Guru P.; Lee, Henry

2014-01-01

The use of active controls for rotorcraft is becoming more important for modern aerospace configurations. Efforts to reduce the vibrations of helicopter blades with use of active-controls are in progress. Modeling oscillating control surfaces using the linear aerodynamics theory is well established. However, higher-fidelity methods are needed to account for nonlinear effects, such as those that occur in transonic flow. The aeroelastic responses of a wing with an oscillating control surface, computed using the transonic small perturbation (TSP) theory, have been shown to cause important transonic flow effects such as a reversal of control surface effectiveness that occurs as the shock wave crosses the hinge line. In order to account for flow complexities such as blade-vortex interactions of rotor blades higher-fidelity methods based on the Navier-Stokes equations are used. Reference 6 presents a procedure that uses the Navier-Stokes equations with moving-sheared grids and demonstrates up to 8 degrees of control-surface amplitude, using a single grid. Later, this procedure was extended to accommodate larger amplitudes, based on sliding grid zones. The sheared grid method implemented in EulerlNavier-Stokes-based aeroelastic code ENS AERO was successfully applied to active control design by industry. Recently there are several papers that present results for oscillating control surface using Reynolds Averaged Navier-Stokes (RANS) equations. References 9 and 10 report 2-D cases by filling gaps with overset grids. Reference 9 compares integrated forces with the experiment at low oscillating frequencies whereas Ref. 10 reports parametric studies but with no validation. Reference II reports results for a 3D case by modeling the gap region with a deformed grid and compares force results with the experiment only at the mid-span of flap. In Ref. II grid is deformed to match the control surface deflections at the section where the measurements are made. However, there is no

Investigations of the surface resistance of superconducting materials

International Nuclear Information System (INIS)

Junginger, Tobias

2012-01-01

In particle accelerators superconducting RF cavities are widely used to achieve high accelerating gradients and low losses. Power consumption is proportional to the surface resistance R S which depends on a number of external parameters, including frequency, temperature, magnetic and electric field. Presently, there is no widely accepted model describing the increase of R S with applied field. In the frame of this project the 400 MHz Quadrupole Resonator has been extended to 800 and 1200 MHz to study surface resistance and intrinsic critical RF magnetic field of superconducting samples over a wide parameter range, establishing it as a world-wide unique test facility for superconducting materials. Different samples were studied and it was shown that R S is mainly caused by the RF electric field in the case of strongly oxidized surfaces. This can be explained by interface tunnel exchange of electrons between the superconductor and localized states in adjacent oxides. For well prepared surfaces, however, the majority of the dissipation is caused by the magnetic field and R S factorizes into field and temperature dependent parts. These different loss mechanisms were correlated to surface topography of the samples and distribution of oxides by using ultrasonic force microscopy and X-ray photon spectroscopy.

Corrosion resistance and biocompatibility of titanium surface coated with amorphous tantalum pentoxide

Energy Technology Data Exchange (ETDEWEB)

Sun, Ying-Sui [Department of Oral Biology, National Yang-Ming University, Taipei, Taiwan (China); Chang, Jean-Heng [Dental Department, Cheng Hsin General Hospital, Taipei, Taiwan (China); Huang, Her-Hsiung, E-mail: hhhuang@ym.edu.tw [Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Department of Dentistry, Taipei City Hospital, Taipei, Taiwan (China); Department of Stomatology, Taipei Veterans General Hospital, Taipei, Taiwan (China)

2013-01-01

Tantalum pentoxide (Ta{sub 2}O{sub 5}) possesses good corrosion resistance and biocompatibility. This study aimed to improve the corrosion resistance and biocompatibility of titanium (Ti) by coating it with an amorphous Ta{sub 2}O{sub 5} surface layer. An amorphous Ta{sub 2}O{sub 5} layer was prepared on the Ti surface using a simple hydrolysis–condensation process at room temperature. The surface characteristics of the test specimens were analyzed using X-ray photoelectron spectroscopy, glancing angle X-ray diffraction, field emission scanning electron microscopy, and contact angle measurements. The corrosion resistance of the test specimens was evaluated from the potentiodynamic polarization curves and ion release measurements in simulated blood plasma (SBP). The biocompatibility of the test specimens was evaluated in terms of the protein (albumin) adsorption, cell adhesion, and cell growth of human bone marrow mesenchymal stem cells (hBMSCs). The amorphous Ta{sub 2}O{sub 5} layer with a porous micro-/nano-scale topography, which was deposited on the Ti surface using a simple hydrolysis–condensation process, increased the corrosion resistance (i.e., increased the corrosion potential and decreased the anodic current and ion release) of the Ti in the SBP and improved the surface wettability, albumin adsorption, and cell adhesion. We conclude that the presence of an amorphous Ta{sub 2}O{sub 5} layer on the Ti surface increased the corrosion resistance and biocompatibility of Ti. - Highlights: ► Amorphous Ta{sub 2}O{sub 5} layer was coated on Ti using simple hydrolysis–condensation process. ► Ta{sub 2}O{sub 5} surface layer showed a micro-/nano-scale porous topography. ► Ta{sub 2}O{sub 5} layer enhanced wettability and corrosion resistance of Ti. ► Ta{sub 2}O{sub 5} layer enhanced protein adsorption, cell adhesion, and cell proliferation of Ti.

Surface Resistance Measurements and Estimate of the Beam-Induced Resistive Wall Heating of the LHC Dipole Beam Screen

CERN Document Server

Caspers, Friedhelm; Ruggiero, F; Tan, J

1999-01-01

An estimate of the resistive losses in the LHC beam screen is given from cold surface resistance measurements using the shielded pair technique, with particular emphasis on the effect of a high magnetic field. Two different copper coating methods, namely electro-deposition and co-lamination, have been evaluated. Experimental data are compared with theories including the anomalous skin effect and the magneto-resistance effect. It is shown whether the theory underestimates or not the losses depends strongly on the RRR value, on the magnetic field and on the surface characteristics. In the pessimistic case and for nominal machine parameters, the estimated beam-induced resistive wall heating can be as large as 260 mW/m for two circulating beams.

XPS and surface resistivity measurements of plasma - treated FEP co-polymer

International Nuclear Information System (INIS)

Pitrus, R.K.; Brack, N.; Liesegang, J.; Pigram, P.J.

2002-01-01

Full text: Fluorinated polymers such as fluorinated ethylene propylene (FEP) and poly(tetrafluoroethylene) (PTFE) play an important role in many applications due to their many desirable properties such as chemical resistivity, inertness, electrical stability and low dielectric constant; however, one disadvantage of fluorinated polymers is their extreme surface hydrophobicity. Previous studies show that plasma treatment will modify the surface by increasing the surface free energy and also offer a rapid and convenient method for pre-treating the polymers for many purposes. This paper, through resistivity and XPS (x-ray photoelectron spectroscopy) measurements, attempts to discover basic effects of such plasma treatment. Fluorinated ethylene propylene (FEP) co-polymer film of (0.05) mm thickness (obtained commercially) and with the following structure (CF 2 -CF 2 )-(CF(CF 3 )CF 2 )- was used. A suitable cleaning procedure was used to remove adventitious carbon from the surface. XPS has been used to study FEP film properties. The spectra of XPS were analyzed with the main focus on carbon and fluorine as they compose the elemental component of FEP film. A value of 2.05 was obtained for the F/C ratio, which is slightly higher than the theoretical F/C value estimated from the chemical structure of FEP (F/C 2). The clean film was then air plasma treated (pressure 10 -1 torr and power 30W) for various treatment times to produce a higher energy fluoropolymer surface. XPS studies investigated changes to the polymer surface and determined that oxidation occurs on the FEP surface. The oxidation reactions on the FEP surface form oxygen functional groups such as C-O and C=O groups. The results also show that the percentage of CF 2 and CF 3 in the co-polymer surface decreased with exposure time and the percentage of CF, C-C, C-O and C=O increased. There is a sharp decrease in F/C ratio and increase in O/C ratio. In addition to XPS, the resistivity of FEP-film was measured by a

Effect of interstitial impurities on the field dependent microwave surface resistance of niobium

Science.gov (United States)

Martinello, M.; Grassellino, A.; Checchin, M.; Romanenko, A.; Melnychuk, O.; Sergatskov, D. A.; Posen, S.; Zasadzinski, J. F.

2016-08-01

Previous work has demonstrated that the radio frequency surface resistance of niobium resonators is dramatically reduced when nitrogen impurities are dissolved as interstitial in the material. This effect is attributed to the lowering of the Mattis-Bardeen surface resistance with increasing accelerating field; however, the microscopic origin of this phenomenon is poorly understood. Meanwhile, an enhancement of the sensitivity to trapped magnetic field is typically observed for such cavities. In this paper, we conduct a systematic study on these different components contributing to the total surface resistance as a function of different levels of dissolved nitrogen, in comparison with standard surface treatments for niobium resonators. Adding these results together, we are able to show which is the optimum surface treatment that maximizes the Q-factor of superconducting niobium resonators as a function of expected trapped magnetic field in the cavity walls. These results also provide insights on the physics behind the change in the field dependence of the Mattis-Bardeen surface resistance, and of the trapped magnetic vortex induced losses in superconducting niobium resonators.

Corrosion resistance of the welded AISI 316L after various surface treatments

Directory of Open Access Journals (Sweden)

Tatiana Liptáková

2014-01-01

Full Text Available The main aim of this work is to monitor the surface treatment impact on the corrosion resistance of the welded stainless steel AISI 316L to local corrosion forms. The excellent corrosion resistance of austenitic stainless steel is caused by the existence of stable, thin and well adhering passive layer which quality is strongly influenced by welding. Therefore surface treatment of stainless steel is very important with regard to its local corrosion susceptibility Surfaces of welded stainless steel were treated by various mechanical methods (grinding, garnet blasting. Surface properties were studied by SEM, corrosion resistance was evaluated after exposition tests in chlorides environment using weight and metalographic analysis. The experimental outcomes confirmed that the mechanical finishing has a significant effect on the corrosion behavior of welded stainless steel AISI 316L.

Robust Imaging Methodology for Challenging Environments: Wave Equation Dispersion Inversion of Surface Waves

KAUST Repository

Li, Jing; Schuster, Gerard T.; Zeng, Zhaofa

2017-01-01

A robust imaging technology is reviewed that provide subsurface information in challenging environments: wave-equation dispersion inversion (WD) of surface waves for the shear velocity model. We demonstrate the benefits and liabilities of the method

On the initial condition problem of the time domain PMCHWT surface integral equation

KAUST Repository

Uysal, Ismail Enes; Bagci, Hakan; Ergin, A. Arif; Ulku, H. Arda

2017-01-01

Non-physical, linearly increasing and constant current components are induced in marching on-in-time solution of time domain surface integral equations when initial conditions on time derivatives of (unknown) equivalent currents are not enforced

Effect of the surface film electric resistance on eddy current detectability of surface cracks in Alloy 600 tubes

International Nuclear Information System (INIS)

Saario, T.; Paine, J.P.N.

1995-01-01

The most widely used technique for NDE of steam generator tubing is eddy current. This technique can reliably detect cracks grown in sodium hydroxide environment only at depths greater than 50% through wall. However, cracking caused by thiosulphate solutions have been detected and sized at shallower depths. The disparity has been proposed to be caused by the different electric resistance of the crack wall surface films and corrosion products in the cracks formed in different environments. This work was undertaken to clarify the role of surface film electric resistance on the disparity found in eddy current detectability of surface cracks in alloy 600 tubes. The proposed model explaining the above mentioned disparity is the following. The detectability of tightly closed cracks by the eddy current technique depends on the electric resistance of the surface films of the crack walls. The nature and resistance of the films which form on the crack walls during operation depends on the composition of the solution inside the crack and close to the crack location. During cooling down of the steam generator, because of contraction and loss of internal pressurization, the cracks are rather tightly closed so that exchange of electrolyte and thus changes in the film properties become difficult. As a result, the surface condition prevailing at high temperature is preserved. If the environment is such that the films formed on the crack walls under operating conditions have low electric resistance, eddy current technique will fail to indicate these cracks or will underestimate the size of these cracks. However, if the electric resistance of the films is high, a tightly closed crack will resemble an open crack and will be easily indicated and correctly sized by eddy current technique

Fermions on a Riemann surface and the Kadomtsev-Petviashvili equation

International Nuclear Information System (INIS)

Zabrodin, A.V.

1989-01-01

It is shown that the S matrix of free massless fermions on a Riemann surface of finite genus generates quasiperiodic solutions of the Kadomtsev-Petviashvili equation. An operator that changes the genus of a solution is constructed, and the law of composition of such operators is discussed. The construction is a generalization of the well-known operator approach in the case of soliton solutions to the general case of quasiperiodic τ functions

Ginzburg-Landau equations for a d-wave superconductor with applications to vortex structure and surface problems

International Nuclear Information System (INIS)

Xu, J.; Ren, Y.; Ting, C.S.

1995-01-01

The properties of a d x 2 -y 2 -wave superconductor in an external magnetic field are investigated on the basis of Gorkov's theory of weakly coupled superconductors. The Ginzburg-Landau (GL) equations, which govern the spatial variations of the order parameter and the supercurrent, are microscopically derived. The single vortex structure and surface problems in such a superconductor are studied using these equations. It is shown that the d-wave vortex structure is very different from the conventional s-wave vortex: the s-wave and d-wave components, with the opposite winding numbers, are found to coexist in the region near the vortex core. The supercurrent and local magnetic field around the vortex are calculated. Far away from the vortex core, both of them exhibit a fourfold symmetry, in contrast to an s-wave superconductor. The surface problem in a d-wave superconductor is also studied by solving the GL equations. The total order parameter near the surface is always a real combination of s- and d-wave components, which means that the proximity effect cannot induce a time-reversal symmetry-breaking state at the surface

Nonlinear behavior of multiple-helicity resistive interchange modes near marginally stable states

International Nuclear Information System (INIS)

Sugama, Hideo; Nakajima, Noriyoshi; Wakatani, Masahiro.

1991-05-01

Nonlinear behavior of resistive interchange modes near marginally stable states is theoretically studied under the multiple-helicity condition. Reduced fluid equations in the sheared slab configuration are used in order to treat a local transport problem. With the use of the invariance property of local reduced fluid model equations under a transformation between the modes with different rational surfaces, weakly nonlinear theories for single-helicity modes by Hamaguchi and Nakajima are extended to the multiple-helicity case and applied to the resistive interchange modes. We derive the nonlinear amplitude equations of the multiple-helicity modes, from which the convective transport in the saturated state is obtained. It is shown how the convective transport is enhanced by nonlinear interaction between modes with different rational surfaces compared with the single-helicity case. We confirm that theoretical results are in good agreement with direct numerical simulations. (author)

Protein resistance of surfaces modified with oligo(ethylene glycol) aryl diazonium derivatives.

Science.gov (United States)

Fairman, Callie; Ginges, Joshua Z; Lowe, Stuart B; Gooding, J Justin

2013-07-22

Anti-fouling surfaces are of great importance for reducing background interference in biosensor signals. Oligo(ethylene glycol) (OEG) moieties are commonly used to confer protein resistance on gold, silicon and carbon surfaces. Herein, we report the modification of surfaces using electrochemical deposition of OEG aryl diazonium salts. Using electrochemical and contact angle measurements, the ligand packing density is found to be loose, which supports the findings of the fluorescent protein labelling that aryl diazonium OEGs confer resistance to nonspecific adsorption of proteins albeit lower than alkane thiol-terminated OEGs. In addition to protein resistance, aryl diazonium attachment chemistry results in stable modification. In common with OEG species on gold electrodes, OEGs with distal hydroxyl moieties do confer superior protein resistance to those with a distal methoxy group. This is especially the case for longer derivatives where superior coiling of the OEG chains is possible. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Why Did the Bear Cross the Road? Comparing the Performance of Multiple Resistance Surfaces and Connectivity Modeling Methods

Directory of Open Access Journals (Sweden)

Samuel A. Cushman

2014-12-01

Full Text Available There have been few assessments of the performance of alternative resistance surfaces, and little is known about how connectivity modeling approaches differ in their ability to predict organism movements. In this paper, we evaluate the performance of four connectivity modeling approaches applied to two resistance surfaces in predicting the locations of highway crossings by American black bears in the northern Rocky Mountains, USA. We found that a resistance surface derived directly from movement data greatly outperformed a resistance surface produced from analysis of genetic differentiation, despite their heuristic similarities. Our analysis also suggested differences in the performance of different connectivity modeling approaches. Factorial least cost paths appeared to slightly outperform other methods on the movement-derived resistance surface, but had very poor performance on the resistance surface obtained from multi-model landscape genetic analysis. Cumulative resistant kernels appeared to offer the best combination of high predictive performance and sensitivity to differences in resistance surface parameterization. Our analysis highlights that even when two resistance surfaces include the same variables and have a high spatial correlation of resistance values, they may perform very differently in predicting animal movement and population connectivity.

Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3Ox bulk material

International Nuclear Information System (INIS)

Wosik, J.; Kranenburg, R.A.; Wolfe, J.C.; Selvamanickam, V.; Salama, K.

1991-01-01

We report measurements of the millimeter wave surface resistance of grain-aligned YBa 2 Cu 3 O x bulk material grown by a liquid phase process. The measurements were performed by replacing the endplate of a TE 011 cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. We show that, for the parallel configuration, the surface resistance at 77 K and 80 GHz is typically near 100 mΩ. For a very well-aligned sample with a very low density of Y 2 BaCuO y precipitates, measured in the perpendicular configuration, the transition width (10%--90%) is about 2 K and the surface resistance is less than 50 mΩ at 88 K. The effect of microstructure on surface resistance is discussed

Surface perturbations of a shallow viscous fluid heated from below and the (2+1)-dimensional Burgers equation

International Nuclear Information System (INIS)

Kraenkel, R.A.; Pereira, J.G.; Manna, M.A.

1991-01-01

The (2+1)-dimensional Burgers equation is obtained as the equation of motion governing the surface perturbations of a shallow viscous fluid heated from below, provided the Rayleigh number of the system satisfy the condition R ≠ 30. A solution to this equation is explicity exhibited and it is argued that it describes the nonlinear evolution of a nearly one-dimensional kink. (author)

The electrical resistivity method in cased boreholes

Energy Technology Data Exchange (ETDEWEB)

Schenkel, C.J.

1991-05-01

The use of downhole current sources in resistivity mapping can greatly enhance the detection and delineation of subsurface features. The purpose of this work is to examine the resistivity method for current sources in wells cased with steel. The resistivity method in cased boreholes with downhole current sources is investigated using the integral equation (IE) technique. The casing and other bodies are characterized as conductivity inhomogeneities in a half-space. For sources located along the casing axis, an axially symmetric Green's function is used to formulate the surface potential and electric field (E-field) volume integral equations. The situations involving off-axis current sources and three-dimensional (3-D) bodies is formulated using the surface potential IE method. The solution of the 3-D Green's function is presented in cylindrical and Cartesian coordinate systems. The methods of moments is used to solve the Fredholm integral equation of the second kind for the response due to the casing and other bodies. The numerical analysis revealed that the current in the casing can be approximated by its vertical component except near the source and the axial symmetric approximation of the casing is valid even for the 3-D problem. The E-field volume IE method is an effective and efficient technique to simulate the response of the casing in a half-space, whereas the surface potential approach is computationally better when multiple bodies are involved. Analyzing several configurations of the current source indicated that the casing response is influenced by four characteristic factors: conduction length, current source depth,casing depth, and casing length. 85 refs., 133 figs., 11 tabs.

Evaluation of Fine Aggregate Morphology by Image Method and Its Effect on Skid-Resistance of Micro-Surfacing.

Science.gov (United States)

Xiao, Yue; Wang, Feng; Cui, Peide; Lei, Lei; Lin, Juntao; Yi, Mingwei

2018-05-29

Micro-surfacing is a widely used pavement preventive maintenance technology used all over the world, due to its advantages of fast construction, low maintenance cost, good waterproofness, and skid-resistance performance. This study evaluated the fine aggregate morphology and surface texture of micro-surfacing by AIMS (aggregate image measurement system), and explored the effect of aggregate morphology on skid-resistance of single-grade micro-surfacing. Sand patch test and British pendulum test were also used to detect skid-resistance for comparison with the image-based method. Wet abrasion test was used to measure skid-resistance durability for feasibility verification of single-grade micro-surfacing. The results show that the effect of Form2D on the skid-resistance of micro-surfacing is much stronger than that of angularity. Combining the feasibility analysis of durability and skid-resistance, 1.18⁻2.36 grade micro-surfacing meets the requirements of durability and skid-resistance at the same time. This study also determined that, compared with British pendulum test, the texture result obtained by sand patch test fits better with results of image method.

Effect of Surface Modification on Corrosion Resistance of Uncoated and DLC Coated Stainless Steel Surface

Science.gov (United States)

Scendo, Mieczyslaw; Staszewska-Samson, Katarzyna

2017-08-01

Corrosion resistance of 4H13 stainless steel (EN-X46Cr13) surface uncoated and coated with an amorphous hydrogenated carbon (a-C:H) film [diamond-like carbon (DLC)] in acidic chloride solution was investigated. The DLC films were deposited on steel surface by a plasma deposition, direct current discharge (PDCD) method. The Fourier transform infrared (FTIR) was used to determine the chemical groups existing on DLC films. The surface of the specimens was observed by a scanning electron microscope (SEM). The tribological properties of the both materials were examined using a ball-on disk tribometer. The microhardness (HV) of diamond-like carbon film increased over five times in relation to the 4H13 stainless steel without of DLC coating. Oxidation kinetic parameters were determined by gravimetric and electrochemical methods. The high value of polarization resistance indicates that the DLC film on substrate was characterized by low electrical conductivity. The corrosion rate of 4H13 stainless steel with of DLC film decreased about eight times in relation to uncoated surface of 4H13 stainless steel.

Laser surface modification of stainless steels for cavitation erosion resistance

Science.gov (United States)

Kwok, Chi Tat

1999-12-01

Austenitic stainless steel UNS S31603 (Fe -17.6Cr -11.2Ni -2.5Mo -1.4Mn -0.4Si -0.03C) has higher pitting corrosion resistance but lower cavitation erosion resistance than that of UNS S30400. This is because of its lower tendency for strain induced martensitic transformation and higher stacking fault energy as compared with those of UNS S30400. In order to improve its cavitation erosion resistance, surface modification of S31603 was performed by laser surface melting and laser surface alloying using a 2-kW CW Nd-YAG laser and a 3-kW CW CO2 laser. For laser surface melting, austenitic stainless steel UNS S30400, super duplex stainless steel UNS S32760 and martensitic stainless steel UNS S42000 were also investigated for comparison purpose. For laser surface alloying, alloying materials including various elements (Co, Cr, Ni, Mo, Mn, Si & C), alloys (AlSiFe & NiCrSiB), ceramics (Si3N 4, SiC, Cr3C2, TiC, CrB & Cr2O 3) and alloys-ceramics (Co-WC, Ni-WC, Ni-Al2O3, Ni-Cr2C3) were used to modify the surface of S31603. The alloyed surface was achieved first by flame spraying or pre-placing of the alloy powder on the S31603 surface and then followed by laser surface remelting. The cavitation erosion characteristics of laser surface modified specimens in 3.5% NaCl solution at 23°C were studied by means of a 20-kHz ultrasonic vibrator at a peak-to-peak amplitude of 30 mum. In addition, their pitting corrosion behaviour was evaluated by electrochemical techniques. The microstructures, compositions, phase changes and damage mechanisms under cavitation erosion were investigated by optical microscopy, SEM, EDAX and X-ray diffractometry. Mechanical properties such as microhardness profile were also examined. The cavitation erosion resistance Re (reciprocal of the mean depth of penetration rate) of laser surface melted S31603 was found to be improved by 22% and was attributed to the existence of tensile residual stress. Improvement on the Re of S42000 was found to be 8.5 times

Temporal step fluctuations on a conductor surface: electromigration force, surface resistivity and low-frequency noise

International Nuclear Information System (INIS)

Williams, E D; Bondarchuk, O; Tao, C G; Yan, W; Cullen, W G; Rous, P J; Bole, T

2007-01-01

Scattering of charge carriers from surface structures will become an increasing factor in the resistivity as the structure decreases in size to the nanoscale. The effects of scattering at the most basic surface defect, a kink in a step edge, are here analyzed using the continuum step model. Using a Langevin analysis, it has been shown that the electromigration force on the atoms at the step edge causes changes in the temporal evolution of the step-edge. For an electromigration force acting perpendicular to the average step edge and mass-transport dominated by step-edge diffusion, significant deviations from the usual t 1/4 scaling of the displacement correlation function occur dependent on a critical time τ and the direction of the force relative to the step edge (i.e. uphill or downhill). Experimental observations of step fluctuations on Ag(111) show the predicted changes among step fluctuations without current, and with current in the up- and down-hill directions for a current density of order 10 5 A cm -2 . The results yield the magnitude of the electromigration force acting on kinked sites at the step-edge. This in turn yields the contribution of the fluctuating steps to the surface resistivity, which exceeds 1% of the bulk resistivity as wire diameters decrease below 10s of nanometres. The temporal fluctuations of kink density can thus also be related to resistivity noise. Relating the known fluctuation spectrum of the step displacements to fluctuations in their lengths, the corresponding resistivity noise is predicted to show spectral signatures of ∼f -1/2 for step fluctuations governed by random attachment/detachment, and ∼f -3/4 for step fluctuations governed by step-edge diffusion

Airflow resistivity instrument for in situ measurement on the earth's ground surface

Science.gov (United States)

Zuckerwar, A. J.

1983-01-01

An airflow resistivity instrument features a novel specimen holder, especially designed for in situ measurement on the earth's ground surface. This capability eliminates the disadvantages of prior intrusive instruments, which necessitate the removal of a test specimen from the ground. A prototype instrument can measure airflow resistivities in the range 10-5000 cgs rayl/cm, at specimen depths up to 15.24 cm (6 in.), and at differential pressures up to 2490.8 dyn sq cm (1 in. H2O) across the specimen. Because of the close relationship between flow resistivity and acoustic impedance, this instrument should prove useful in acoustical studies of the earth's ground surface. Results of airflow resistivity measurements on an uncultivated grass field for varying values of moisture content are presented.

Comparison of surface fractal dimensions of chromizing coating and P110 steel for corrosion resistance estimation

International Nuclear Information System (INIS)

Lin, Naiming; Guo, Junwen; Xie, Faqin; Zou, Jiaojuan; Tian, Wei; Yao, Xiaofei; Zhang, Hongyan; Tang, Bin

2014-01-01

Highlights: • Continuous chromizing coating was synthesized on P110 steel by pack cementation. • The chromizing coating showed better corrosion resistance. • Comparison of surface fractal dimensions can estimate corrosion resistance. - Abstract: In the field of corrosion research, mass gain/loss, electrochemical tests and comparing the surface elemental distributions, phase constitutions as well as surface morphologies before and after corrosion are extensively applied to investigate the corrosion behavior or estimate the corrosion resistance of materials that operated in various environments. Most of the above methods are problem oriented, complex and longer-period time-consuming. However from an object oriented point of view, the corroded surfaces of materials often have self-similar characterization: fractal property which can be employed to efficiently achieve damaged surface analysis. The present work describes a strategy of comparison of the surface fractal dimensions for corrosion resistance estimation: chromizing coating was synthesized on P110 steel surface to improve its performance via pack cementation. Scanning electron microscope (SEM) was used to investigate the surface morphologies of the original and corroded samples. Surface fractal dimensions of the detected samples were calculated by binary images related to SEM images of surface morphologies with box counting algorithm method. The results showed that both surface morphologies and surface fractal dimensions of P110 steel varied greatly before and after corrosion test, but the chromizing coating changed slightly. The chromizing coating indicated better corrosion resistance than P110 steel. Comparison of surface fractal dimensions of original and corroded samples can rapidly and exactly realize the estimation of corrosion resistance

Comparison of surface fractal dimensions of chromizing coating and P110 steel for corrosion resistance estimation

Energy Technology Data Exchange (ETDEWEB)

Lin, Naiming, E-mail: lnmlz33@163.com [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Guo, Junwen [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Xie, Faqin [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China); Zou, Jiaojuan; Tian, Wei [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Yao, Xiaofei [School of Materials and Chemical Engineering, Xi’an Technological University, Xi’an 710032 (China); Zhang, Hongyan; Tang, Bin [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

2014-08-30

Highlights: • Continuous chromizing coating was synthesized on P110 steel by pack cementation. • The chromizing coating showed better corrosion resistance. • Comparison of surface fractal dimensions can estimate corrosion resistance. - Abstract: In the field of corrosion research, mass gain/loss, electrochemical tests and comparing the surface elemental distributions, phase constitutions as well as surface morphologies before and after corrosion are extensively applied to investigate the corrosion behavior or estimate the corrosion resistance of materials that operated in various environments. Most of the above methods are problem oriented, complex and longer-period time-consuming. However from an object oriented point of view, the corroded surfaces of materials often have self-similar characterization: fractal property which can be employed to efficiently achieve damaged surface analysis. The present work describes a strategy of comparison of the surface fractal dimensions for corrosion resistance estimation: chromizing coating was synthesized on P110 steel surface to improve its performance via pack cementation. Scanning electron microscope (SEM) was used to investigate the surface morphologies of the original and corroded samples. Surface fractal dimensions of the detected samples were calculated by binary images related to SEM images of surface morphologies with box counting algorithm method. The results showed that both surface morphologies and surface fractal dimensions of P110 steel varied greatly before and after corrosion test, but the chromizing coating changed slightly. The chromizing coating indicated better corrosion resistance than P110 steel. Comparison of surface fractal dimensions of original and corroded samples can rapidly and exactly realize the estimation of corrosion resistance.

Ernst Equation and Riemann Surfaces: Analytical and Numerical Methods

International Nuclear Information System (INIS)

Ernst, Frederick J

2007-01-01

extending the techniques espoused by these authors to other physica lly interesting problems (e.g., when electromagnetic fields are involved) are discussed. In addition to these eight chapters, there are two appendices. The first concerns the theory of Riemann surfaces and the second describes the relationship between the Ernst equation and twistor theory. It should be mentioned that this book may be considered to be an homage to Olaf Richter, whose very promising research life ended prematurely in November 2003. Indeed, a substantial part of the book is based upon his habilitation thesis. It is the reviewer's opinion that the resulting book will be more useful as a resource for those who are already well versed in the subject of integrable systems than as an educational tool for novices who would like to enter this exciting branch of mathematical physics. (book review)

Time Domain Surface Integral Equation Solvers for Quantum Corrected Electromagnetic Analysis of Plasmonic Nanostructures

KAUST Repository

Uysal, Ismail Enes

2016-10-01

Plasmonic structures are utilized in many applications ranging from bio-medicine to solar energy generation and transfer. Numerical schemes capable of solving equations of classical electrodynamics have been the method of choice for characterizing scattering properties of such structures. However, as dimensions of these plasmonic structures reduce to nanometer scale, quantum mechanical effects start to appear. These effects cannot be accurately modeled by available classical numerical methods. One of these quantum effects is the tunneling, which is observed when two structures are located within a sub-nanometer distance of each other. At these small distances electrons “jump" from one structure to another and introduce a path for electric current to flow. Classical equations of electrodynamics and the schemes used for solving them do not account for this additional current path. This limitation can be lifted by introducing an auxiliary tunnel with material properties obtained using quantum models and applying a classical solver to the structures connected by this auxiliary tunnel. Early work on this topic focused on quantum models that are generated using a simple one-dimensional wave function to find the tunneling probability and assume a simple Drude model for the permittivity of the tunnel. These tunnel models are then used together with a classical frequency domain solver. In this thesis, a time domain surface integral equation solver for quantum corrected analysis of transient plasmonic interactions is proposed. This solver has several advantages: (i) As opposed to frequency domain solvers, it provides results at a broad band of frequencies with a single simulation. (ii) As opposed to differential equation solvers, it only discretizes surfaces (reducing number of unknowns), enforces the radiation condition implicitly (increasing the accuracy), and allows for time step selection independent of spatial discretization (increasing efficiency). The quantum model

Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material

International Nuclear Information System (INIS)

Wosik, J.; Kranenburg, R.A.; Wolfe, J.C.; Selvamanickam, V.; Salama, K.

1990-04-01

Measurements are reported of the millimeter-wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid-phase process. The measurements were performed by replacing the endplate of a TE(011) cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. For the parallel configuration, the surface resistance at 77 K and 80 GHz is given. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K and the surface resistance is derived at 88 K. The effect of microstructure on surface resistance is discussed. 19 refs

Study of the surface resistance of niobium sputter-coated copper cavities

CERN Document Server

Benvenuti, Cristoforo; Campisi, I E; Darriulat, Pierre; Peck, M A; Russo, R; Valente, A M

1999-01-01

A systematic study of the superconducting properties of niobium films deposited on the inner wall of copper radiofrequency cavities is presented. Films are grown by sputtering with different discharge gases (Xe, Kr, Ar and Ar/Ne mixtures) on substrates prepared under different conditions. The measured quantities include the surface resistance at 1.5 GHz, the critical temperature and the penetration depth. The surface resistance is analyzed in terms of its dependence on temperature, RF field and the density of trapped fluxons. Once allowance for electron scattering is made by means of a single mean free path parameter, good agreement with BCS theory is observed. The residual resistance is observed to be essentially noncorrelated with the superconducting properties, although influenced by specific coating conditions. On occasions, very low residual resistances, in the nano-ohm range, have been maintained over a broad range of RF field, indicating the absence of fundamental limitations specific to the film techn...

Evaluation of Fine Aggregate Morphology by Image Method and Its Effect on Skid-Resistance of Micro-Surfacing

Directory of Open Access Journals (Sweden)

Yue Xiao

2018-05-01

Full Text Available Micro-surfacing is a widely used pavement preventive maintenance technology used all over the world, due to its advantages of fast construction, low maintenance cost, good waterproofness, and skid-resistance performance. This study evaluated the fine aggregate morphology and surface texture of micro-surfacing by AIMS (aggregate image measurement system, and explored the effect of aggregate morphology on skid-resistance of single-grade micro-surfacing. Sand patch test and British pendulum test were also used to detect skid-resistance for comparison with the image-based method. Wet abrasion test was used to measure skid-resistance durability for feasibility verification of single-grade micro-surfacing. The results show that the effect of Form2D on the skid-resistance of micro-surfacing is much stronger than that of angularity. Combining the feasibility analysis of durability and skid-resistance, 1.18–2.36 grade micro-surfacing meets the requirements of durability and skid-resistance at the same time. This study also determined that, compared with British pendulum test, the texture result obtained by sand patch test fits better with results of image method.

A wavelet-based PWTD algorithm-accelerated time domain surface integral equation solver

KAUST Repository

Liu, Yang

2015-10-26

© 2015 IEEE. The multilevel plane-wave time-domain (PWTD) algorithm allows for fast and accurate analysis of transient scattering from, and radiation by, electrically large and complex structures. When used in tandem with marching-on-in-time (MOT)-based surface integral equation (SIE) solvers, it reduces the computational and memory costs of transient analysis from equation and equation to equation and equation, respectively, where Nt and Ns denote the number of temporal and spatial unknowns (Ergin et al., IEEE Trans. Antennas Mag., 41, 39-52, 1999). In the past, PWTD-accelerated MOT-SIE solvers have been applied to transient problems involving half million spatial unknowns (Shanker et al., IEEE Trans. Antennas Propag., 51, 628-641, 2003). Recently, a scalable parallel PWTD-accelerated MOT-SIE solver that leverages a hiearchical parallelization strategy has been developed and successfully applied to the transient problems involving ten million spatial unknowns (Liu et. al., in URSI Digest, 2013). We further enhanced the capabilities of this solver by implementing a compression scheme based on local cosine wavelet bases (LCBs) that exploits the sparsity in the temporal dimension (Liu et. al., in URSI Digest, 2014). Specifically, the LCB compression scheme was used to reduce the memory requirement of the PWTD ray data and computational cost of operations in the PWTD translation stage.

Comparison of multi-drug resistant environmental methicillin-resistant Staphylococcus aureus [MRSA] isolated from recreational beaches and high touch surfaces in built environments

Directory of Open Access Journals (Sweden)

Marilyn C Roberts

2013-04-01

Full Text Available Over the last decade community-acquired methicillin-resistant Staphylococcus aureus [MRSA] has emerged as a major cause of disease in the general population with no health care exposure or known classical risk factors for MRSA infections. The potential community reservoirs have not been well defined though certain strains such as ST398 and USA300 have been well studied in some settings. MRSA has been isolated from recreational beaches, high-touch surfaces in homes, universities and other community environmental surfaces. However, in most cases the strains were not characterized to determine if they are related to community-acquired or hospital-acquired clinical strains. We compared 55 environmental MRSA from 805 samples including sand, fresh and marine water samples from local marine and fresh water recreational beaches (n=296, high touch surfaces on the University of Washington campus (n=294, surfaces in UW undergraduate housing (n=85, and the local community (n=130. Eleven USA300, representing 20% of the isolates, were found on the UW campus surfaces, student housing surfaces and on the community surfaces but not in the recreational beach samples from the Northwest USA. Similarly, the predominant animal ST133 was found in the recreational beach samples but not in the high touch surface samples. All USA300 isolates were multi-drug resistant carrying 2-6 different antibiotic resistance genes coding for kanamycin, macrolides and/or macrolides-lincosamides-streptogramin B and tetracycline, with the majority [72%] carrying 4-6 different antibiotic resistance genes. A surprising 98% of the 55 MRSA isolates were resistant to other classes of antibiotics and most likely represent reservoirs for these genes in the environment.

Instanton calculus without equations of motion: semiclassics from monodromies of a Riemann surface

Science.gov (United States)

Gulden, Tobias; Janas, Michael; Kamenev, Alex

2015-02-01

Instanton calculations in semiclassical quantum mechanics rely on integration along trajectories which solve classical equations of motion. However in systems with higher dimensionality or complexified phase space these are rarely attainable. A prime example are spin-coherent states which are used e.g. to describe single molecule magnets (SMM). We use this example to develop instanton calculus which does not rely on explicit solutions of the classical equations of motion. Energy conservation restricts the complex phase space to a Riemann surface of complex dimension one, allowing to deform integration paths according to Cauchy’s integral theorem. As a result, the semiclassical actions can be evaluated without knowing actual classical paths. Furthermore we show that in many cases such actions may be solely derived from monodromy properties of the corresponding Riemann surface and residue values at its singular points. As an example, we consider quenching of tunneling processes in SMM by an applied magnetic field.

Measurements of the anomalous RF surface resistance of niobium using a dielectric resonator

International Nuclear Information System (INIS)

Moffat, D.; Bolore, M.; Bonin, B.; Jacques, E.; Safa, H.

1996-01-01

The surface resistance of high and low residual resistance ratio (RRR) niobium plates at 4.2 K and 1.8 K has been measured as a function of many processing and testing parameters. A dielectric resonator was used instead of a resonant cavity. This resonator offered the ability to make many, sensitive measurements with an efficient use of time and helium. It was found that the surface resistance, R s , of RRR = 190 niobium increased noticeably from the theoretical value if the cooling rate was slower than ∼ 10 K/min. (author)

Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material

Science.gov (United States)

Wosik, J.; Kranenburg, R. A.; Wolfe, J. C.; Selvamanickam, V.; Salama, K.

1991-01-01

Measurements of the millimeter wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid phase process are reported. The measurements were performed by replacing the endplate of a TE011 cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. It is shown that, for the parallel configuration, the surface resistance at 77 K and 80 GHz is typically near 100 milliohms. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K, and the surface resistance is less than 50 milliohms at 88 K. The effect of microstructure on surface resistance is discussed.

A simple approach to measure the surface resistivity of insulating materials

DEFF Research Database (Denmark)

Yang, Zhenyu; Wang, Qian

2011-01-01

A simple approach for measuring high surface resistivity of insulating materials using standard laboratory equipments is proposed. The developed system consists of a DC power transformer, a concentric ring probe assembly and a digital multi-meter. The DC power transformer can provide either 500V ...... for different materials, source voltages, and serially connected resistors. The testing results showed that the developed system and methods can provide a reasonably accurate measurement of surface resistivity of insulating materials in a robust and economic manner.......A simple approach for measuring high surface resistivity of insulating materials using standard laboratory equipments is proposed. The developed system consists of a DC power transformer, a concentric ring probe assembly and a digital multi-meter. The DC power transformer can provide either 500V...... or 250V DC signal. The probe assembly is constructed according to Danish Standard (DS/EN 1149-1:2006). The multi-meter (Agilent 3440 1A 6½) is used to measure the micro voltage over a known resistor which is serially connected with electrodes in the probe assembly. In order to obtain reliable...

Electrical resistivity study of insulators

International Nuclear Information System (INIS)

Liesegang, J.; Senn, B.C.; Holcombe, S.R.; Pigram, P.J.

1998-01-01

Full text: Conventional methods of electrical resistivity measurement of dielectric materials involve the application of electrodes to a sample whereby a potential is applied and a current through the material is measured. Although great care and ingenuity has often been applied to this technique, the recorded values of electrical resistivity (p), especially for insulator materials, show great disparity. In earlier work by the authors, a method for determining surface charge decay [Q(t)], using a coaxial cylindrical capacitor arrangement interfaced to a personal computer, was adapted to allow the relatively straightforward measurement of electrical resistivity in the surface region of charged insulator materials. This method was used to develop an ionic charge transport theory, based on Mott-Gurney diffusion to allow a greater understanding into charge transport behaviour. This theory was extended using numerical analysis to produce a two dimensional (2-D) computational model to allow the direct comparison between experimental and theoretical charge decay data. The work also provided a means for the accurate determination of the diffusion coefficient (D) and the layer of thickness of surface charge (Δz) on the sample. The work outlined here involves an extension of the theoretical approach previously taken, using a computational model based more closely on the 3-D experimental set-up, to reinforce the level of confidence in the results achieved for the simpler 2-D treatment. Initially, a 3-D rectangular box arrangement similar to the experimental set-up was modelled and a theoretical and experimental comparison of voltage decay results made. This model was then transferred into cylindrical coordinates to allow it to be almost identical to the experiment and again a comparison made. In addition, theoretical analysis of the coupled non-linear partial differential equations governing the charge dissipation process has led to a simplification involving directly, the

Investigation of surface resistance of copper in classical and anomalous skin-effect region

International Nuclear Information System (INIS)

Kutovoj, V.A.; Egorov, A.M.

2008-01-01

The surface resistance of copper in classical and anomalous skin-effect region has been investigated, and the surface resistance improvement factor equal to the ratio of the surface resistance of copper at room temperature to that of helium temperature, depending on the electromagnetic field frequency, has been determined. The improvement factor has been shown to have inverse power law dependence on frequency. The frequencies at which the improvement factor of copper equals 10 have been determined. It has been found that the quality factor of a resonance high-frequency system made of copper, operating at temperature T ≥ 4.2 K can be increased 10 times or more as against a quality factor of a resonance high-frequency system operating at room temperature

Electro-thermal analysis of contact resistance

Science.gov (United States)

Pandey, Nitin; Jain, Ishant; Reddy, Sudhakar; Gulhane, Nitin P.

2018-05-01

Electro-Mechanical characterization over copper samples are performed at the macroscopic level to understand the dependence of electrical contact resistance and temperature on surface roughness and contact pressure. For two different surface roughness levels of samples, six levels of load are selected and varied to capture the bulk temperature rise and electrical contact resistance. Accordingly, the copper samples are modelled and analysed using COMSOLTM as a simulation package and the results are validated by the experiments. The interface temperature during simulation is obtained using Mikic-Elastic correlation and by directly entering experimental contact resistance value. The load values are varied and then reversed in a similar fashion to capture the hysteresis losses. The governing equations & assumptions underlying these models and their significance are examined & possible justification for the observed variations are discussed. Equivalent Greenwood model is also predicted by mapping the results of the experiment.

A Calderón multiplicative preconditioner for coupled surface-volume electric field integral equations

KAUST Repository

Bagci, Hakan; Andriulli, Francesco P.; Cools, Kristof; Olyslager, Femke; Michielssen, Eric

2010-01-01

A well-conditioned coupled set of surface (S) and volume (V) electric field integral equations (S-EFIE and V-EFIE) for analyzing wave interactions with densely discretized composite structures is presented. Whereas the V-EFIE operator is well

Derivation of the Wenzel and Cassie Equations from a Phase Field Model for Two Phase Flow on Rough Surface

KAUST Repository

Xu, Xianmin; Wang, Xiaoping

2010-01-01

In this paper, the equilibrium behavior of an immiscible two phase fluid on a rough surface is studied from a phase field equation derived from minimizing the total free energy of the system. When the size of the roughness becomes small, we derive the effective boundary condition for the equation by the multiple scale expansion homogenization technique. The Wenzel and Cassie equations for the apparent contact angles on the rough surfaces are then derived from the effective boundary condition. The homogenization results are proved rigorously by the F-convergence theory. © 2010 Society for Industrial and Applied Mathematics.

Chemically resistant, biocompatible and microstructured surface protection

International Nuclear Information System (INIS)

Hoffmann, W.; Pham, M.T.; Hueller, J.

1984-01-01

Subject of the invention are chemicallly resistant, biocompatible, and microstructured surface protective coatings of electronic elements and sensors including chemical sensors. Such coatings consist of a radiation-modified organic substance made of a microlithographic material. Modification can be achieved by irradiation with ions, atoms or molecules having an energy between 1 KeV and 1 MeV and a flux between 10 13 and 10 18 particles per cm 2

Resistivity scaling due to electron surface scattering in thin metal layers

Science.gov (United States)

Zhou, Tianji; Gall, Daniel

2018-04-01

The effect of electron surface scattering on the thickness-dependent electrical resistivity ρ of thin metal layers is investigated using nonequilibrium Green's function density functional transport simulations. Cu(001) thin films with thickness d =1 -2 nm are used as a model system, employing a random one-monolayer-high surface roughness and frozen phonons to cause surface and bulk scattering, respectively. The zero-temperature resistivity increases from 9.7 ±1.0 μ Ω cm at d =1.99 nm to 18.7 ±2.6 μ Ω cm at d =0.9 0 nm, contradicting the asymptotic T =0 prediction from the classical Fuchs-Sondheimer model. At T =9 00 K, ρ =5.8 ±0.1 μ Ω cm for bulk Cu and ρ =13.4 ±1.1 and 22.5 ±2.4 μ Ω cm for layers with d =1.99 and 0.90 nm, respectively, indicating an approximately additive phonon contribution which, however, is smaller than for bulk Cu or atomically smooth layers. The overall data indicate that the resistivity contribution from surface scattering is temperature-independent and proportional to 1 /d , suggesting that it can be described using a surface-scattering mean-free path λs for 2D transport which is channel-independent and proportional to d . Data fitting indicates λs=4 ×d for the particular simulated Cu(001) surfaces with a one-monolayer-high surface roughness. The 1 /d dependence deviates considerably from previous 1 /d2 predictions from quantum models, indicating that the small-roughness approximation in these models is not applicable to very thin (<2 nm) layers, where the surface roughness is a considerable fraction of d .

Decoupling pipeline influences in soil resistivity measurements with finite element techniques

Science.gov (United States)

Deo, R. N.; Azoor, R. M.; Zhang, C.; Kodikara, J. K.

2018-03-01

Periodic inspection of pipeline conditions is an important asset management strategy conducted by water and sewer utilities for efficient and economical operations of their assets in field. The Level 1 pipeline condition assessment involving resistivity profiling along the pipeline right-of-way is a common technique for delineating pipe sections that might be installed in highly corrosive soil environment. However, the technique can suffer from significant perturbations arising from the buried pipe itself, resulting in errors in native soil characterisation. To address this problem, a finite element model was developed to investigate the degree to which pipes of different a) diameters, b) burial depths, and c) surface conditions (bare or coated) can influence in-situ soil resistivity measurements using Wenner methods. It was found that the greatest errors can arise when conducting measurements over a bare pipe with the array aligned parallel to the pipe. Depending upon the pipe surface conditions, in-situ resistivity measurements can either be underestimated or overestimated from true soil resistivities. Following results based on simulations and decoupling equations, a guiding framework for removing pipe influences in soil resistivity measurements were developed that can be easily used to perform corrections on measurements. The equations require simple a-prior information on the pipe diameter, burial depth, surface condition, and the array length and orientation used. Findings from this study have immediate application and is envisaged to be useful for critical civil infrastructure monitoring and assessment.

Microwave surface resistance of YBa2Cu3O/sub 6.9/ superconducting films

International Nuclear Information System (INIS)

Martens, J.S.; Beyer, J.B.; Ginley, D.S.

1988-01-01

The microwave surface resistance of an YBa 2 Cu 3 O/sub 6.9/ superconducting thick film was measured over the range 7.0--16.7 GHz at 77 K. This was done by placing a sample in a TE 01 /sub n/ wavemeter cavity and observing the change in selectivity of the cavity. The material's surface resistance is of the same order of magnitude as that of silver at 77 K from 8 to 12 GHz and improves about another order at 4.2 K. The power-law behavior of surface resistance with frequency is probably close to quadratic. This is similar to the behavior of low critical temperature superconductors

Transient analysis of electromagnetic wave interactions on plasmonic nanostructures using a surface integral equation solver

KAUST Repository

Uysal, Ismail Enes

2016-08-09

Transient electromagnetic interactions on plasmonic nanostructures are analyzed by solving the Poggio-Miller-Chan-Harrington-Wu-Tsai (PMCHWT) surface integral equation (SIE). Equivalent (unknown) electric and magnetic current densities, which are introduced on the surfaces of the nanostructures, are expanded using Rao-Wilton-Glisson and polynomial basis functions in space and time, respectively. Inserting this expansion into the PMCHWT-SIE and Galerkin testing the resulting equation at discrete times yield a system of equations that is solved for the current expansion coefficients by a marching on-in-time (MOT) scheme. The resulting MOT-PMCHWT-SIE solver calls for computation of additional convolutions between the temporal basis function and the plasmonic medium\\'s permittivity and Green function. This computation is carried out with almost no additional cost and without changing the computational complexity of the solver. Time-domain samples of the permittivity and the Green function required by these convolutions are obtained from their frequency-domain samples using a fast relaxed vector fitting algorithm. Numerical results demonstrate the accuracy and applicability of the proposed MOT-PMCHWT solver. © 2016 Optical Society of America.

Fluoride influences nickel-titanium orthodontic wires′ surface texture and friction resistance

Directory of Open Access Journals (Sweden)

Mona Aly Abbassy

2016-01-01

Full Text Available Objectives: The aim of this study was to investigate the effects exerted by the acidulated fluoride gel on stainless steel and nickel-titanium (Ni-Ti orthodontic wires. Materials and Methods: Sixty stainless steel and Ni-Ti orthodontic archwires were distributed into forty archwires used for in vitro study and twenty for in situ study. Fluoride was applied for 1 h in the in vitro experiment while it was applied for 5 min in the in situ experiment. The friction resistance of all wires with ceramic brackets before/after topical fluoride application was measured using a universal testing machine at 1 min intervals of moving wire. Moreover, surface properties of the tested wires before/after fluoride application and before/after friction test were examined by a scanning electron microscope (SEM. Dunnett′s t-test was used to compare frictional resistance of as-received stainless steel wires and Ni-Ti wires to the wires treated by fluoride in vitro and in situ (P < 0.05. Two-way ANOVA was used to compare the effect of fluoride application and type of wire on friction resistance in vitro and in situ (P < 0.05. Results: Ni-Ti wires recorded significantly high friction resistance after fluoride application when compared to stainless steel wires in vitro, P < 0.05. Fluoride application did not significantly affect the friction resistance of the tested wires in situ, P < 0.05. SEM observation revealed deterioration of the surface texture of the Ni-Ti wires after fluoride application in vitro and in situ. Conclusions: The in vitro fluoride application caused an increase in friction resistance of Ni-Ti wires when compared to stainless steel wires. In vitro and in situ fluoride application caused deterioration in surface properties of Ni-Ti wires.

Layer Dependence of Graphene for Oxidation Resistance of Cu Surface

Institute of Scientific and Technical Information of China (English)

Yu-qing Song; Xiao-ping Wang

2017-01-01

We studied the oxidation resistance of graphene-coated Cu surface and its layer dependence by directly growing monolayer graphene with different multilayer structures coexisted,diminishing the influence induced by residue and transfer technology.It is found that the Cu surface coated with the monolayer graphene demonstrate tremendous difference in oxidation pattern and oxidation rate,compared to that coated with the bilayer graphene,which is considered to be originated from the strain-induced linear oxidation channel in monolayer graphene and the intersection of easily-oxidized directions in each layer of bilayer graphene,respectively.We reveal that the defects on the graphene basal plane but not the boundaries are the main oxidation channel for Cu surface under graphene protection.Our finding indicates that compared to putting forth efforts to improve the quality of monolayer graphene by reducing defects,depositing multilayer graphene directly on metal is a simple and effective way to enhance the oxidation resistance of graphene-coated metals.

The characteristics of surface oxidation and corrosion resistance of nitrogen implanted zircaloy-4

International Nuclear Information System (INIS)

Tang, G.; Choi, B.H.; Kim, W.; Jung, K.S.; Kwon, H.S.; Lee, S.J.; Lee, J.H.; Song, T.Y.; Shon, D.H.; Han, J.G.

1997-01-01

This work is concerned with the development and application of ion implantation techniques for improving the corrosion resistance of zircaloy-4. The corrosion resistance in nitrogen implanted zircaloy-4 under a 120 keV nitrogen ion beam at an ion dose of 3 x 10 17 cm -2 depends on the implantation temperature. The characteristics of surface oxidation and corrosion resistance were analyzed with the change of implantation temperature. It is shown that as implantation temperature rises from 100 to 724 C, the colour of specimen surface changes from its original colour to light yellow at 100 C, golden at 175 C, pink at 300 C, blue at 440 C and dark blue at 550 C. As the implantation temperature goes above 640 C, the colour of surface changes to light black, and the surface becomes a little rough. The corrosion resistance of zircaloy-4 implanted with nitrogen is sensitive to the implantation temperature. The pitting potential of specimens increases from 176 to 900 mV (SCE) as the implantation temperature increases from 100 to 300 C, and decreases from 900 to 90 mV(SCE) as the implantation temperature increases from 300 to 640 C. The microstructure, the distribution of oxygen, nitrogen and carbon elements, the oxide grain size and the feature of the precipitation in the implanted surface were investigated by optical microscope, TEM, EDS, XRD and AES. The experimental results reveal that the ZrO 2 is distributed mainly on the outer surface. The ZrN is distributed under the ZrO 2 layer. The characteristics of the distribution of ZrO 2 and ZrN in the nitrogen-implanted zircaloy-4 is influenced by the implantation temperature of the sample, and in turn the corrosion resistance is influenced. (orig.)

The orthogonal gradients method: A radial basis functions method for solving partial differential equations on arbitrary surfaces

KAUST Repository

Piret, Cé cile

2012-01-01

Much work has been done on reconstructing arbitrary surfaces using the radial basis function (RBF) method, but one can hardly find any work done on the use of RBFs to solve partial differential equations (PDEs) on arbitrary surfaces. In this paper

Heat-resisting alloys for hard surfacing and sealing pad welding

Directory of Open Access Journals (Sweden)

R.O. Wielgosz

2010-07-01

Full Text Available The paper deals with heat-resisting alloys used to harden surfaces of elements operating in increased temperatures. It also deals with alloysused to seal cooperating surfaces of elements operating in the conditions of increased temperatures and aggressive utilities. Application methods and properties of thus obtained layers have been presented and adhesion of layers with matrix material has been assessed.

A surface-integral-equation approach to the propagation of waves in EBG-based devices

NARCIS (Netherlands)

Lancellotti, V.; Tijhuis, A.G.

2012-01-01

We combine surface integral equations with domain decomposition to formulate and (numerically) solve the problem of electromagnetic (EM) wave propagation inside finite-sized structures. The approach is of interest for (but not limited to) the analysis of devices based on the phenomenon of

Fracture Resistance, Surface Defects and Structural Strength of Glass

NARCIS (Netherlands)

Rodichev, Y.M.; Veer, F.A.

2010-01-01

This paper poses the theory that the fracture resistance of basic float glass is dependent on it physicochemical properties and the surface defects fonned under the float glass production, glass processing and handling at the service conditions compose the aggregate basis for structural glass

Intermodulation distortion and surface resistance in impurity-doped YBCO and MgB{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Agassi, Y.D. [Naval Surface Warfare Center, Carderock Division, Bethesda, MD 20817 (United States); Oates, D.E., E-mail: oates@ll.mit.edu [MIT-Lincoln Laboratory, Lexington, MA 02420 (United States)

2014-11-15

Highlights: • Calculations of impurity-doping effects on surface resistance and intermodulation distortion. • The calculations are compared with previously published measurements in YBCO and MgB{sub 2}. • Excellent agreement between calculations and experiments are shown. • The effects of the symmetry of the energy gap are presented and discussed. - Abstract: Calculations of the microwave intermodulation distortion (IMD) and surface resistance of impurity-doped YBCO, MgB{sub 2} and Nb are presented. These are qualitatively distinct superconductors due to their energy-gap symmetries, d-wave (ℓ = 2), i-wave (ℓ = 6) and s-wave (ℓ = 0), respectively. The calculations are compared with previously published IMD and surface-resistance measurements of impurity-doped YBCO and Nb. The agreement between the data and fitted calculations is excellent in all cases. In the absence of IMD and surface-resistance measurements for doped MgB{sub 2}, we present representative predictions. The calculations are based on a Green’s-function approach that yields analytical expressions for the penetration depth and the nonlinear kernel in the constitutive relation. This penetration-depth expression reproduces the measured T{sup 2} low-temperature variation for doped superconductors and the surface-resistance reduction over that of the pure material. Regarding the IMD in superconductors with a nodal energy gap, the effect of doping is to enhance its magnitude and suppress its low-temperature 1/T{sup 2} divergence predicted by the nonlinear Meissner effect.

Mathematical model to determine the surface stress acting on the tooth of gear

Directory of Open Access Journals (Sweden)

Hinojosa-Torres J.

2010-01-01

Full Text Available Surface stress on the surface contact of gear tooth calculated by the Buckingham equation constitutes the basis for The American Gear Manufacturers Association (AGMA pitting resistance formula, which is based on a normal stress that does not cause failure since the yielding in contact problems is caused by shear stresses. An alternative expression based on the maximum-shear-stress is proposed in this paper. The new expression is obtained by using the maximum-shear-stress distribution and the Tresca failure criteria in order to know the maximum-shear-stress value and its location beneath the contact surface. Remarkable differences between the results using the proposed equation and those when the AGMA equation is applied are found.

Effects of surface topography and vibrations on wetting: Superhydrophobicity, icephobicity and corrosion resistance

Science.gov (United States)

Ramachandran, Rahul

Concrete and metallic materials are widely used in construction and water industry. The interaction of both these materials with water and ice (or snow) produces undesirable results and is therefore of interest. Water that gets absorbed into the pores of dry concrete expands on freezing and can lead to crack formation. Also, the ice accretion on concrete surfaces such as roadways can have disastrous consequence. Metallic components used in the water industry undergo corrosion due to contact with aqueous corrosive solutions. Therefore, it is desirable to make concrete water/ice-repellent, and to make metallic surfaces corrosion-resistant. Recent advances in micro/nanotechnology have made it possible to design functional micro/nanostructured surfaces with micro/nanotopography providing low adhesion. Some examples of such surfaces are superhydrophobic surfaces, which are extremely water repellent, and icephobic surfaces, which have low ice adhesion, repel incoming water droplets before freezing, or delay ice nucleation. This dissertation investigates the effects of surface micro/nanotopography and small amplitude fast vibrations on the wetting and adhesion of concrete with the goal of producing hydrophobic and icephobic concrete, and on the wetting of metallic surfaces to prevent corrosion. The relationship between surface micro/nanotopography and small fast vibrations is established using the method of separation of motions. Both these small scale effects can be substituted by an effective force or energy. The structure-property relationships in materials and surfaces are established. Both vibrations as well as surface micro/nanopatterns can affect wetting properties such as contact angle and surface free energy. Hydrophobic engineered cementitious composite samples are produced by controlling their surface topography and surface free energy. The surface topography is controlled by varying the concrete mixture composition. The surface free energy of concrete is

Bridging the Knowledge Gaps between Richards' Equation and Budyko Equation

Science.gov (United States)

Wang, D.

2017-12-01

The empirical Budyko equation represents the partitioning of mean annual precipitation into evaporation and runoff. Richards' equation, based on Darcy's law, represents the movement of water in unsaturated soils. The linkage between Richards' equation and Budyko equation is presented by invoking the empirical Soil Conservation Service curve number (SCS-CN) model for computing surface runoff at the event-scale. The basis of the SCS-CN method is the proportionality relationship, i.e., the ratio of continuing abstraction to its potential is equal to the ratio of surface runoff to its potential value. The proportionality relationship can be derived from the Richards' equation for computing infiltration excess and saturation excess models at the catchment scale. Meanwhile, the generalized proportionality relationship is demonstrated as the common basis of SCS-CN method, monthly "abcd" model, and Budyko equation. Therefore, the linkage between Darcy's law and the emergent pattern of mean annual water balance at the catchment scale is presented through the proportionality relationship.

Local instant conservation equations

International Nuclear Information System (INIS)

Delaje, Dzh.

1984-01-01

Local instant conservation equations for two-phase flow are derived. Derivation of the equation starts from the recording of integral laws of conservation for a fixed reference volume, containing both phases. Transformation of the laws, using the Leibniz rule and Gauss theory permits to obtain the sum of two integrals as to the volume and integral as to the surface. Integrals as to the volume result in local instant differential equations, in particular derivatives for each phase, and integrals as to the surface reflect local instant conditions of a jump on interface surface

Automation for measuring the surface resistivity of RPC by Arduino motor shield

International Nuclear Information System (INIS)

Pandey, A.; Kumar, A.; Singh, M.K.; Marimuthu, N.; Singh, V.

2016-01-01

India Based Neutrino Observatory (INO) is planning to use ∼ 30,000 Resistive Plate Chamber (RPC) detectors of size 2m x 2m. Each resistive plate chamber is made up of glass or Bakelite whose resistance is of the order 10 12 Ω/cm 2 , and two pick-up panels. Both glass electrodes of the detector have one side (outer) painted with thin and uniform coating of graphite paint. This provides the resistivity of range 100 - 300 kΩ per square. This range of resistivity provides distribution of voltage over the surface of glass electrodes. Uniform coating will provide uniform electric field inside the glass plate chamber and high resistivity value will help in confining the induced charge on the surface. It is one of the necessary criteria for good RPC detector that the coating of graphite paint should be uniform. Therefore it is required to measure the resistivity for the verification of uniformity. Last few years we have been focusing our efforts in this direction. In this connection, we made sequential improvement from the previous work. The present system is cost effective, automatically recording measurement in the computer, fast and accurate. Earlier MOTOR BEE ver. 5.0 microcontroller was used which was an imported and costly material. After massive search in the local market Arduino microcontroller was discovered, which controls the movement of all motors and it also saves the value of resistivity in the computer automatically

Research surface resistance of copper normal and abnormal skin-effects depending on the frequency of electromagnetic field

International Nuclear Information System (INIS)

Kutovyi, V.A.; Komir, A.I.

2013-01-01

The results of the frequency dependence of surface resistance of copper in diffuse and specular reflection of electrons from the conductive surface of the high-frequency resonance of the system depending on the frequency of the electromagnetic field in the normal and anomalous skin effect. Found, the surface resistance of copper is reduced by more than 10 times at the temperature of liquid helium, as compared with a surface resistivity at room temperature, at frequencies f ≤ 173 MHz, for diffuse reflection of conduction electrons from the surface of the conductive layer, and the specular reflection - at frequencies f ≤ 346 MHz

Fluxon induced surface resistance and field emission in niobium films at 1.5 GHz

CERN Document Server

Benvenuti, Cristoforo; Darriulat, Pierre; Peck, M A; Valente, A M; Van't Hof, C A

2001-01-01

The surface resistance of superconducting niobium films induced by the presence of trapped magnetic flux, presumably in the form of a pinned fluxon lattice, is shown to be modified by the presence of a field emitting impurity or defect. The modification takes the form of an additional surface resistance proportional to the density of the fluxon lattice and increasing linearly with the amplitude of the microwave above a threshold significantly lower than the field emission threshold. Such an effect, a precursor of electron emission, is observed for the first time in a study using radiofrequency cavities operating at their fundamental 1.5 GHz frequency. The measured properties of the additional surface resistance severely constrain possible explanations of the observed effect. (23 refs).

Cavitation erosion resistance of AISI 316L stainless steel laser surface-modified with NiTi

International Nuclear Information System (INIS)

Chiu, K.Y.; Cheng, F.T.; Man, H.C.

2005-01-01

The present study is part of a project on the surface modification of AISI 316 stainless steel using various forms of NiTi for enhancing cavitation erosion resistance. In this study, NiTi powder was preplaced on the AISI 316L substrate and melted with a high-power CW Nd:YAG laser. With appropriate laser processing parameters, an alloyed layer of a few hundred micrometers thick was formed and fusion bonded to the substrate without the formation of a brittle interface. EDS analysis showed that the layer contained Fe as the major constituent element while the XRD patterns of the surface showed an austenitic structure, similar to that of 316 stainless steel. The cavitation erosion resistance of the modified layer (316-NiTi-Laser) could reach about 29 times that of AISI 316L stainless steel. The improvement could be attributed to a much higher surface hardness and elasticity as revealed by instrumented nanoindentation tests. Among various types of samples, the cavitation erosion resistance was ranked in descending order as: NiTi plate > 316-NiTi-Laser > 316-NiTi-TIG > AISI 316L, where 316-NiTi-TIG stands for samples surfaced with the tungsten inert gas (TIG) process using NiTi wire. Though the laser-surfaced samples and the TIG-surfaced samples had similar indentation properties, the former exhibited a higher erosion resistance mainly because of a more homogeneous alloyed layer with much less defects. In both the laser-surfaced and TIG-surfaced samples, the superelastic behavior typical of austenitic NiTi was only partially retained and the superior cavitation erosion resistance was thus still not fully attained

Hierarchically ordered self-lubricating superhydrophobic anodized aluminum surfaces with enhanced corrosion resistance.

Science.gov (United States)

Vengatesh, Panneerselvam; Kulandainathan, Manickam Anbu

2015-01-28

Herein, we report a facile method for the fabrication of self-lubricating superhydrophobic hierarchical anodic aluminum oxide (AAO) surfaces with improved corrosion protection, which is greatly anticipated to have a high impact in catalysis, aerospace, and the shipping industries. This method involves chemical grafting of as-formed AAO using low surface free energy molecules like long chain saturated fatty acids, perfluorinated fatty acid (perfluorooctadecanoic acid, PFODA), and perfluorosulfonicacid-polytetrafluoroethylene copolymer. The pre and post treatment processes in the anodization of aluminum (Al) play a vital role in the grafting of fatty acids. Wettability and surface free energy were analyzed using a contact angle meter and achieved 161.5° for PFODA grafted anodized aluminum (PFODA-Al). This study was also aimed at evaluating the surface for corrosion resistance by Tafel polarization and self-lubricating properties by tribological studies using a pin-on-disc tribometer. The collective results showed that chemically grafted AAO nanostructures exhibit high corrosion resistance toward seawater and low frictional coefficient due to low surface energy and self-lubricating property of fatty acids covalently linked to anodized Al surfaces.

The Effect of Surface Patterning on Corrosion Resistance of Biomedical Devices

Science.gov (United States)

Guo, Mengnan; Toloei, Alisina; Rotermund, Harm H.

2016-10-01

In this study, two styles of surface topographies have been created on stainless steel wires to test their corrosion resistance as simulated implanted biomedical devices. Grade 316 LVM stainless steel wire was initially polished to G1500 surface finish before treatment to produce the two different topographies: 1. Unidirectional roughness was created using SiC papers and 2. Various patterns were created with specific hole diameter and inter-hole spacing using focused ion beam (FIB). In order to simulate the environment of implanted biomedical devices, a three-electrode electrochemical cell with 0.9% (by mass) NaCl solution has been used to test the corrosion resistance of the samples by potentiodynamic polarization test method. SEM and EDS analyzed the appearance and chemical composition of different elements including oxygen on the surface. The potential of stable pitting, time related to the initiation of the stable pitting, and the highest corrosion current associated with stable pitting have been compared for samples with the two styles of topography. It was found that surfaces with patterns have a relatively higher pitting potential and it takes longer time to initiate stable pitting than the surface without any patterns.

Exploring surface cleaning strategies in hospital to prevent contact transmission of methicillin-resistant Staphylococcus aureus.

Science.gov (United States)

Lei, Hao; Jones, Rachael M; Li, Yuguo

2017-01-18

Cleaning of environmental surfaces in hospitals is important for the control of methicillin-resistant Staphylococcus aureus (MRSA) and other hospital-acquired infections transmitted by the contact route. Guidance regarding the best approaches for cleaning, however, is limited. In this study, a mathematical model based on ordinary differential equations was constructed to study MRSA concentration dynamics on high-touch and low-touch surfaces, and on the hands and noses of two patients (in two hospitals rooms) and a health care worker in a hypothetical hospital environment. Two cleaning interventions - whole room cleaning and wipe cleaning of touched surfaces - were considered. The performance of the cleaning interventions was indicated by a reduction in MRSA on the nose of a susceptible patient, relative to no intervention. Whole room cleaning just before first patient care activities of the day was more effective than whole room cleaning at other times, but even with 100% efficiency, whole room cleaning only reduced the number of MRSA transmitted to the susceptible patient by 54%. Frequent wipe cleaning of touched surfaces was shown to be more effective that whole room cleaning because surfaces are rapidly re-contaminated with MRSA after cleaning. Wipe cleaning high-touch surfaces was more effective than wipe cleaning low-touch surfaces for the same frequency of cleaning. For low wipe cleaning frequency (≤3 times per hour), high-touch surfaces should be targeted, but for high wipe cleaning frequency (>3 times per hour), cleaning should target high- and low-touch surfaces in proportion to the surface touch frequency. This study reproduces the observations from a field study of room cleaning, which provides support for the validity of our findings. Daily whole room cleaning, even with 100% cleaning efficiency, provides limited reduction in the number of MRSA transmitted to susceptible patients via the contact route; and should be supplemented with frequent targeted

Improved surface corrosion resistance of WE43 magnesium alloy by dual titanium and oxygen ion implantation

Energy Technology Data Exchange (ETDEWEB)

Zhao, Ying [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wu, Guosong; Lu, Qiuyuan [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wu, Jun [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Xu, Ruizhen [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Yeung, Kelvin W.K., E-mail: wkkyeung@hku.hk [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2013-02-01

Magnesium alloys are potential biodegradable materials and have attracted much attention due to their outstanding biological performance and mechanical properties. However, their rapid degradation inside the human body cannot meet clinical needs. In order to improve the corrosion resistance, dual titanium and oxygen ion implantation is performed to modify the surface of the WE43 magnesium alloy. X-ray photoelectron spectroscopy is used to characterize the microstructures in the near surface layer and electrochemical impedance spectroscopy, potentiodynamic polarization, and immersion tests are employed to investigate the corrosion resistance of the implanted alloys in simulated body fluids. The results indicate that dual titanium and oxygen ion implantation produces a TiO{sub 2}-containing surface film which significantly enhances the corrosion resistance of WE43 magnesium alloy. Our data suggest a simple and practical means to improve the corrosion resistance of degradable magnesium alloys. - Highlights: ► Surface modification of WE43 magnesium alloy using dual ion implantation ► Dual Ti and O ion implantation produces a homogeneous TiO{sub 2}-containing surface film ► Significant improvement of the alloy corrosion resistance after the dual ion implantation.

Continuous surface force based lattice Boltzmann equation method for simulating thermocapillary flow

International Nuclear Information System (INIS)

Zheng, Lin; Zheng, Song; Zhai, Qinglan

2016-01-01

In this paper, we extend a lattice Boltzmann equation (LBE) with continuous surface force (CSF) to simulate thermocapillary flows. The model is designed on our previous CSF LBE for athermal two phase flow, in which the interfacial tension forces and the Marangoni stresses as the results of the interface interactions between different phases are described by a conception of CSF. In this model, the sharp interfaces between different phases are separated by a narrow transition layers, and the kinetics and morphology evolution of phase separation would be characterized by an order parameter via Cahn–Hilliard equation which is solved in the frame work of LBE. The scalar convection–diffusion equation for temperature field is resolved by thermal LBE. The models are validated by thermal two layered Poiseuille flow, and two superimposed planar fluids at negligibly small Reynolds and Marangoni numbers for the thermocapillary driven convection, which have analytical solutions for the velocity and temperature. Then thermocapillary migration of two/three dimensional deformable droplet are simulated. Numerical results show that the predictions of present LBE agreed with the analytical solution/other numerical results. - Highlights: • A CSF LBE to thermocapillary flows. • Thermal layered Poiseuille flows. • Thermocapillary migration.

Continuous surface force based lattice Boltzmann equation method for simulating thermocapillary flow

Energy Technology Data Exchange (ETDEWEB)

Zheng, Lin, E-mail: lz@njust.edu.cn [School of Energy and Power Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Zheng, Song [School of Mathematics and Statistics, Zhejiang University of Finance and Economics, Hangzhou 310018 (China); Zhai, Qinglan [School of Economics Management and Law, Chaohu University, Chaohu 238000 (China)

2016-02-05

In this paper, we extend a lattice Boltzmann equation (LBE) with continuous surface force (CSF) to simulate thermocapillary flows. The model is designed on our previous CSF LBE for athermal two phase flow, in which the interfacial tension forces and the Marangoni stresses as the results of the interface interactions between different phases are described by a conception of CSF. In this model, the sharp interfaces between different phases are separated by a narrow transition layers, and the kinetics and morphology evolution of phase separation would be characterized by an order parameter via Cahn–Hilliard equation which is solved in the frame work of LBE. The scalar convection–diffusion equation for temperature field is resolved by thermal LBE. The models are validated by thermal two layered Poiseuille flow, and two superimposed planar fluids at negligibly small Reynolds and Marangoni numbers for the thermocapillary driven convection, which have analytical solutions for the velocity and temperature. Then thermocapillary migration of two/three dimensional deformable droplet are simulated. Numerical results show that the predictions of present LBE agreed with the analytical solution/other numerical results. - Highlights: • A CSF LBE to thermocapillary flows. • Thermal layered Poiseuille flows. • Thermocapillary migration.

Downscaling Coarse Actual ET Data Using Land Surface Resistance

Science.gov (United States)

Shen, T.

2017-12-01

This study proposed a new approach of downscaling ETWATCH 1km actual evapotranspiration (ET) product to a spatial resolution of 30m using land surface resistance that simulated mainly from monthly Landsat8 data and Jarvis method, which combined the benefits of both high temporal resolution of ETWATCH product and fine spatial resolution of Landsat8. The driving factor, surface resistance (Rs), was chosen for the reason that could reflect the transfer ability of vapor flow over canopy. Combined resistance Rs both upon canopy conditions, atmospheric factors and available water content of soil, which remains stable inside one ETWATCH pixel (1km). In this research, we used ETWATCH 1km ten-day actual ET product from April to October in a total of twenty-one images and monthly 30 meters cloud-free NDVI of 2013 (two images from HJ as a substitute due to cloud contamination) combined meteorological indicators for downscaling. A good agreement and correlation were obtained between the downscaled data and three flux sites observation in the middle reach of Heihe basin. The downscaling results show good consistency with the original ETWATCH 1km data both temporal and spatial scale over different land cover types with R2 ranged from 0.8 to 0.98. Besides, downscaled result captured the progression of vegetation transpiration well. This study proved the practicability of new downscaling method in the water resource management.

High-order fractional partial differential equation transform for molecular surface construction.

Science.gov (United States)

Hu, Langhua; Chen, Duan; Wei, Guo-Wei

2013-01-01

Fractional derivative or fractional calculus plays a significant role in theoretical modeling of scientific and engineering problems. However, only relatively low order fractional derivatives are used at present. In general, it is not obvious what role a high fractional derivative can play and how to make use of arbitrarily high-order fractional derivatives. This work introduces arbitrarily high-order fractional partial differential equations (PDEs) to describe fractional hyperdiffusions. The fractional PDEs are constructed via fractional variational principle. A fast fractional Fourier transform (FFFT) is proposed to numerically integrate the high-order fractional PDEs so as to avoid stringent stability constraints in solving high-order evolution PDEs. The proposed high-order fractional PDEs are applied to the surface generation of proteins. We first validate the proposed method with a variety of test examples in two and three-dimensional settings. The impact of high-order fractional derivatives to surface analysis is examined. We also construct fractional PDE transform based on arbitrarily high-order fractional PDEs. We demonstrate that the use of arbitrarily high-order derivatives gives rise to time-frequency localization, the control of the spectral distribution, and the regulation of the spatial resolution in the fractional PDE transform. Consequently, the fractional PDE transform enables the mode decomposition of images, signals, and surfaces. The effect of the propagation time on the quality of resulting molecular surfaces is also studied. Computational efficiency of the present surface generation method is compared with the MSMS approach in Cartesian representation. We further validate the present method by examining some benchmark indicators of macromolecular surfaces, i.e., surface area, surface enclosed volume, surface electrostatic potential and solvation free energy. Extensive numerical experiments and comparison with an established surface model

Study of the effect of nano surface morphology on the stain-resistant property of ceramic tiles

International Nuclear Information System (INIS)

Pan, S P; Hung, J K; Liu, Y T

2014-01-01

In this study, six types of commercially available ceramic tiles, including nano-structured ceramic tiles and regular ceramic tiles, were selected to investigate the effect of surface morphology on their stain-resistant property. The stain-resistant efficiencies of various ceramic tiles with nano-size surface were measured in order to determine the appropriate method for testing ceramic tiles with nano-structure surface

Method of moving frames to solve time-dependent Maxwell's equations on anisotropic curved surfaces: Applications to invisible cloak and ELF propagation

Science.gov (United States)

Chun, Sehun

2017-07-01

Applying the method of moving frames to Maxwell's equations yields two important advancements for scientific computing. The first is the use of upwind flux for anisotropic materials in Maxwell's equations, especially in the context of discontinuous Galerkin (DG) methods. Upwind flux has been available only to isotropic material, because of the difficulty of satisfying the Rankine-Hugoniot conditions in anisotropic media. The second is to solve numerically Maxwell's equations on curved surfaces without the metric tensor and composite meshes. For numerical validation, spectral convergences are displayed for both two-dimensional anisotropic media and isotropic spheres. In the first application, invisible two-dimensional metamaterial cloaks are simulated with a relatively coarse mesh by both the lossless Drude model and the piecewisely-parametered layered model. In the second application, extremely low frequency propagation on various surfaces such as spheres, irregular surfaces, and non-convex surfaces is demonstrated.

MARG2D code. 1. Eigenvalue problem for two dimensional Newcomb equation

Energy Technology Data Exchange (ETDEWEB)

Tokuda, Shinji [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Watanabe, Tomoko

1997-10-01

A new method and a code MARG2D have been developed to solve the 2-dimensional Newcomb equation which plays an important role in the magnetohydrodynamic (MHD) stability analysis in an axisymmetric toroidal plasma such as a tokamak. In the present formulation, an eigenvalue problem is posed for the 2-D Newcomb equation, where the weight function (the kinetic energy integral) and the boundary conditions at rational surfaces are chosen so that an eigenfunction correctly behaves as the linear combination of the small solution and the analytical solutions around each of the rational surfaces. Thus, the difficulty on solving the 2-D Newcomb equation has been resolved. By using the MARG2D code, the ideal MHD marginally stable state can be identified for a 2-D toroidal plasma. The code is indispensable on computing the outer-region matching data necessary for the resistive MHD stability analysis. Benchmark with ERATOJ, an ideal MHD stability code, has been carried out and the MARG2D code demonstrates that it indeed identifies both stable and marginally stable states against ideal MHD motion. (author)

Modeling surface roughness scattering in metallic nanowires

Energy Technology Data Exchange (ETDEWEB)

Moors, Kristof, E-mail: kristof@itf.fys.kuleuven.be [KU Leuven, Institute for Theoretical Physics, Celestijnenlaan 200D, B-3001 Leuven (Belgium); IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Sorée, Bart [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); KU Leuven, Electrical Engineering (ESAT) Department, Kasteelpark Arenberg 10, B-3001 Leuven (Belgium); Magnus, Wim [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

2015-09-28

Ando's model provides a rigorous quantum-mechanical framework for electron-surface roughness scattering, based on the detailed roughness structure. We apply this method to metallic nanowires and improve the model introducing surface roughness distribution functions on a finite domain with analytical expressions for the average surface roughness matrix elements. This approach is valid for any roughness size and extends beyond the commonly used Prange-Nee approximation. The resistivity scaling is obtained from the self-consistent relaxation time solution of the Boltzmann transport equation and is compared to Prange-Nee's approach and other known methods. The results show that a substantial drop in resistivity can be obtained for certain diameters by achieving a large momentum gap between Fermi level states with positive and negative momentum in the transport direction.

Method For Creating Corrosion Resistant Surface On An Aluminum Copper Alloy

Science.gov (United States)

Mansfeld, Florian B.; Wang, You; Lin, Simon H.

1997-06-03

A method for treating the surface of aluminum alloys hang a relatively high copper content is provided which includes the steps of removing substantially all of the copper from the surface, contacting the surface with a first solution containing cerium, electrically charging the surface while contacting the surface in an aqueous molybdate solution, and contacting the surface with a second solution containing cerium. The copper is substantially removed from the surface in the first step either by (i) contacting the surface with an acidic chromate solution or by (ii) contacting the surface with an acidic nitrate solution while subjecting the surface to an electric potential. The corrosion-resistant surface resulting from the invention is excellent, consistent and uniform throughout the surface. Surfaces treated by the invention may often be certified for use in salt-water services.

Development of stress corrosion cracking resistant welds of 321 stainless steel by simple surface engineering

Science.gov (United States)

Mankari, Kamal; Acharyya, Swati Ghosh

2017-12-01

We hereby report a simple surface engineering technique to make AISI grade 321 stainless steel (SS) welds resistant to stress corrosion cracking (SCC) in chloride environment. Heat exchanger tubes of AISI 321 SS, welded either by (a) laser beam welding (LBW) or by (b) metal inert gas welding (MIG) were used for the study. The welds had high magnitude of tensile residual stresses and had undergone SCC in chloride environment while in service. The welds were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). Subsequently, the welded surfaces were subjected to buffing operation followed by determination of residual stress distribution and surface roughness by XRD and surface profilometer measurements respectively. The susceptibility of the welds to SCC was tested in buffed and un-buffed condition as per ASTM G-36 in boiling MgCl2 for 5 h and 10 h, followed by microstructural characterization by using optical microscope and FESEM. The results showed that the buffed surfaces (both welds and base material) were resistant to SCC even after 10 h of exposure to boiling MgCl2 whereas the un-buffed surfaces underwent severe SCC for the same exposure time. Buffing imparted high magnitude of compressive stresses on the surface of stainless steel together with reduction in its surface roughness and reduction in plastic strain on the surface which made the welded surface, resistant to chloride assisted SCC. Buffing being a very simple, portable and economic technique can be easily adapted by the designers as the last step of component fabrication to make 321 stainless steel welds resistant to chloride assisted SCC.

Reduced equations for finite beta tearing modes in tokamaks

International Nuclear Information System (INIS)

Izzo, R.; Monticello, D.A.; DeLucia, J.; Park, W.; Ryu, C.M.

1984-10-01

The equations of resistive magnetohydrodynamics (MHD) are recast in a form that is useful for studying the evolution of those toroidal systems where the fast magnetosonic wave plays no important role. The equations are exact and have nabla vector.B vector = O satisfied explicitly. From this set of equations it is a simple matter to derive the equations of reduced MHD to any order in the inverse aspect ratio epsilon of the torus, and for β approx. epsilon or smaller. We demonstrate this by deriving a reduced set of MHD equations that are correct to 5th order in epsilon. These equations contain the exact equilibrium relation and as such can be used to find 3-D stellarator equilibria. In addition, if a subsidiary ordering in eta, the resistivity, is made, the equations of Glasser, Greene, and Johnson are recovered. This set of reduced equations has been coded by extending the initial value code, HILO. Results obtained, for both ideal and resistive linear stability, from the reduced equations are compared with those obtained by solving the full set of MHD equations in a cylinder. The agreement is shown to be excellent for both zero and finite beta calculations. Comparisons are also made with analytic theory illuminating the present limitations of the latter

Influence of surface roughness of stainless steel on microbial adhesion and corrosion resistance

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel; Bagge-Ravn, Dorthe; Kold, John

2003-01-01

Abstract The aim of this study was to evaluate if hygienic characteristics of stainless steel used in the food industry could be improved by smoothing surface roughness from an Ra of 0.9 to 0.01 ƒÝm. The adherence of Pseudomonas sp., Listeria monocytogenes and Candida lipolytica to stainless steel...... was not affected by surface roughness (Ra) ranging from grit 4000 polished stainless steel (Ra steel (Ra 0.9). Neither adhesion of Ps. aeruginosa nor its removal by an alkaline commercial cleaner in a flow system was affected by surface roughness. Pitting corrosion resistance...... was evaluated in a commercial disinfectant and in 1 M NaCl. Electropolished and grit 4000 polished steel proved more corrosion resistant as opposed to grit 80 and 120 polished surfaces. In conclusion, the surface finish did not influence bacterial attachment, colonisation, or removal, but is an important...

Cell surface alteration in Epstein-Barr virus-transformed cells from patients with extreme insulin resistance

International Nuclear Information System (INIS)

Gorden, D.L.; Robert, A.; Moncada, V.Y.; Taylor, S.I.; Muehlhauser, J.C.; Carpentier, J.L.

1990-01-01

An abnormality was detected in the morphology of the cell surface of Epstein-Barr virus-transformed lymphocytes of patients with genetic forms of insulin resistance. In cells from two patients with leprechaunism and two patients with type A extreme insulin resistance, scanning electron microscopy demonstrated a decrease in the percentage of the cell surface occupied by microvilli in cells from the patients with leprechaunism and type A insulin resistance compared with control cells. When cells from a healthy control subject and one of the patients with leprechaunism (Lep/Ark-1) were incubated with 125 I-labeled insulin, there was a decrease in the percentage of 125 I-insulin associated with microvilli on the cell surface. Thus, the decreased localization of insulin receptors with the microvillous region of the cell surface was in proportion to the decrease in microvilli

Effect of implantoplasty on fracture resistance and surface roughness of standard diameter dental implants.

Science.gov (United States)

Costa-Berenguer, Xavier; García-García, Marta; Sánchez-Torres, Alba; Sanz-Alonso, Mariano; Figueiredo, Rui; Valmaseda-Castellón, Eduard

2018-01-01

To assess the effect of implantoplasty on the fracture resistance, surface roughness, and macroscopic morphology of standard diameter (4.1 mm) external connection dental implants. An in vitro study was conducted in 20 screw-shaped titanium dental implants with an external connection. In 10 implants, the threads and surface were removed and polished with high-speed burs (implantoplasty), while the remaining 10 implants were used as controls. The final implant dimensions were recorded. The newly polished surface quality was assessed by scanning electron microscopy (SEM) and by 3D surface roughness analysis using a confocal laser microscope. Finally, all the implants were subjected to a mechanical pressure resistance test. A descriptive analysis of the data was made. Also, Student's t tests were employed to detect differences regarding the compression tests. Implantoplasty was carried out for a mean time of 10 min and 48 s (standard deviation (SD) of 1 min 22 s). Macroscopically, the resulting surface had a smooth appearance, although small titanium shavings and silicon debris were present. The final surface roughness (S a values 0.1 ± 0.02 μm) was significantly lower than that of the original (0.75 ± 0.08 μm S a ) (p = .005). There was minimal reduction in the implant's inner body diameter (0.19 ± 0.03 mm), and no statistically significant differences were found between the test and control implants regarding the maximum resistance force (896 vs 880 N, respectively). Implantoplasty, although technically demanding and time-consuming, does not seem to significantly alter fracture resistance of standard diameter external connection implants. A smooth surface with S a values below 0.1 μm can be obtained through the use of silicon polishers. A larger sample is required to confirm that implantoplasty does not significantly affect the maximum resistance force of standard diameter external connection implants. © 2017 John Wiley & Sons A/S. Published

Solution of volume-surface integral equations using higher-order hierarchical Legendre basis functions

DEFF Research Database (Denmark)

Kim, Oleksiy S.; Meincke, Peter; Breinbjerg, Olav

2007-01-01

The problem of electromagnetic scattering by composite metallic and dielectric objects is solved using the coupled volume-surface integral equation (VSIE). The method of moments (MoM) based on higher-order hierarchical Legendre basis functions and higher-order curvilinear geometrical elements...... with the analytical Mie series solution. Scattering by more complex metal-dielectric objects are also considered to compare the presented technique with other numerical methods....

Nonlinear differential equations for the wavefront surface at arbitrary Hartmann-plane distances.

Science.gov (United States)

Téllez-Quiñones, Alejandro; Malacara-Doblado, Daniel; Flores-Hernández, Ricardo; Gutiérrez-Hernández, David A; León-Rodríguez, Miguel

2016-03-20

In the Hartmann test, a wave aberration function W is estimated from the information of the spot diagram drawn in an observation plane. The distance from a reference plane to the observation plane, the Hartmann-plane distance, is typically chosen as z=f, where f is the radius of a reference sphere. The function W and the transversal aberrations {X,Y} calculated at the plane z=f are related by two well-known linear differential equations. Here, we propose two nonlinear differential equations to denote a more general relation between W and the transversal aberrations {U,V} calculated at any arbitrary Hartmann-plane distance z=r. We also show how to directly estimate the wavefront surface w from the information of {U,V}. The use of arbitrary r values could improve the reliability of the measurements of W, or w, when finding difficulties in adequate ray identification at z=f.

Polyamide desalination membrane characterization and surface modification to enhance fouling resistance.

Energy Technology Data Exchange (ETDEWEB)

Sharma, Mukul M. (Univeristy of Texas at Austin, Austin, TX); Freeman, Benny D. (Univeristy of Texas at Austin, Austin, TX); Van Wagner, Elizabeth M. (Univeristy of Texas at Austin, Austin, TX); Hickner, Michael A. (Pennsylvania State University, University Park, PA); Altman, Susan Jeanne

2010-08-01

The market for polyamide desalination membranes is expected to continue to grow during the coming decades. Purification of alternative water sources will also be necessary to meet growing water demands. Purification of produced water, a byproduct of oil and gas production, is of interest due to its dual potential to provide water for beneficial use as well as to reduce wastewater disposal costs. However, current polyamide membranes are prone to fouling, which decreases water flux and shortens membrane lifetime. This research explored surface modification using poly(ethylene glycol) diglycidyl ether (PEGDE) to improve the fouling resistance of commercial polyamide membranes. Characterization of commercial polyamide membrane performance was a necessary first step before undertaking surface modification studies. Membrane performance was found to be sensitive to crossflow testing conditions. Concentration polarization and feed pH strongly influenced NaCl rejection, and the use of continuous feed filtration led to higher water flux and lower NaCl rejection than was observed for similar tests performed using unfiltered feed. Two commercial polyamide membranes, including one reverse osmosis and one nanofiltration membrane, were modified by grafting PEGDE to their surfaces. Two different PEG molecular weights (200 and 1000) and treatment concentrations (1% (w/w) and 15% (w/w)) were studied. Water flux decreased and NaCl rejection increased with PEGDE graft density ({micro}g/cm{sup 2}), although the largest changes were observed for low PEGDE graft densities. Surface properties including hydrophilicity, roughness and charge were minimally affected by surface modification. The fouling resistance of modified and unmodified membranes was compared in crossflow filtration studies using model foulant solutions consisting of either a charged surfactant or an oil in water emulsion containing n-decane and a charged surfactant. Several PEGDE-modified membranes demonstrated improved

Simulation of variation of apparent resistivity in resistivity surveys using finite difference modelling with Monte Carlo analysis

Science.gov (United States)

Aguirre, E. E.; Karchewski, B.

2017-12-01

DC resistivity surveying is a geophysical method that quantifies the electrical properties of the subsurface of the earth by applying a source current between two electrodes and measuring potential differences between electrodes at known distances from the source. Analytical solutions for a homogeneous half-space and simple subsurface models are well known, as the former is used to define the concept of apparent resistivity. However, in situ properties are heterogeneous meaning that simple analytical models are only an approximation, and ignoring such heterogeneity can lead to misinterpretation of survey results costing time and money. The present study examines the extent to which random variations in electrical properties (i.e. electrical conductivity) affect potential difference readings and therefore apparent resistivities, relative to an assumed homogeneous subsurface model. We simulate the DC resistivity survey using a Finite Difference (FD) approximation of an appropriate simplification of Maxwell's equations implemented in Matlab. Electrical resistivity values at each node in the simulation were defined as random variables with a given mean and variance, and are assumed to follow a log-normal distribution. The Monte Carlo analysis for a given variance of electrical resistivity was performed until the mean and variance in potential difference measured at the surface converged. Finally, we used the simulation results to examine the relationship between variance in resistivity and variation in surface potential difference (or apparent resistivity) relative to a homogeneous half-space model. For relatively low values of standard deviation in the material properties (<10% of mean), we observed a linear correlation between variance of resistivity and variance in apparent resistivity.

Maxwell's equations in axisymmetrical geometry: coupling H(curl) finite element in volume and H(div) finite element in surface. The numerical code FuMel

International Nuclear Information System (INIS)

Cambon, S.; Lacoste, P.

2011-01-01

We propose a finite element method to solve the axisymmetric scattering problem posed on a regular bounded domain. Here we shall show how to reduce the initial 3D problem into a truncated sum of 2D independent problems posed into a meridian plane of the object. Each of these problem results in the coupling of a partial differential equation into the interior domain and an integral equation on the surface simulating the free space. Then variational volume and boundary integral formulations of Maxwell's equation on regular surfaces are derived. We introduce some general finite element adapted to cylindrical coordinates and constructed from nodal and mixed finite element both for the interior (volume) and for the integral equation (surface). (authors)

Improving wettability of photo-resistive film surface with plasma surface modification for coplanar copper pillar plating of IC substrates

International Nuclear Information System (INIS)

Xiang, Jing; Wang, Chong; Chen, Yuanming; Wang, Shouxu; Hong, Yan; Zhang, Huaiwu; Gong, Lijun; He, Wei

2017-01-01

Highlights: • Air atmosphere plasmacould generatehydrophilic groups of photo-resistive film. • Better wettability of photo-resistive filmled tohigher plating uniformity of copper pillars. • New flow isreduced cost, simplified process and elevated productivity. - Abstract: The wettability of the photo-resistive film (PF) surfaces undergoing different pretreatments including the O_2−CF_4 low-pressure plasma (OCLP) and air plasma (AP), is investigated by water contact angle measurement instrument (WCAMI) before the bottom-up copper pillar plating. Chemical groups analysis performed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectra (XPS) shows that after the OCLP and wash treatment, the wettability of PF surface is attenuated, because embedded fluorine and decreased oxygen content both enhance hydrophobicity. Compared with OCLP treatment, the PF surface treatment by non-toxic air plasma displays features of C−O, O−C=O, C=O and −NO_2 by AIR-FTIR and XPS, and a promoted wettability by WCAM. Under the identical electroplating condition, the surface with a better wettability allows electrolyte to spontaneously soak all the places of vias, resulting in improved copper pillar uniformity. Statistical analysis of metallographic data shows that more coplanar and flat copper pillars are achieved with the PF treatment of air plasma. Such modified copper-pillar-plating technology meets the requirement of accurate impedance, the high density interconnection for IC substrates.

Multidrug-Resistant and Extended Spectrum Beta-Lactamase-Producing Escherichia coli in Dutch Surface Water and Wastewater.

Directory of Open Access Journals (Sweden)

Hetty Blaak

Full Text Available The goal of the current study was to gain insight into the prevalence and concentrations of antimicrobial resistant (AMR Escherichia coli in Dutch surface water, and to explore the role of wastewater as AMR contamination source.The prevalence of AMR E. coli was determined in 113 surface water samples obtained from 30 different water bodies, and in 33 wastewater samples obtained at five health care institutions (HCIs, seven municipal wastewater treatment plants (mWWTPs, and an airport WWTP. Overall, 846 surface water and 313 wastewater E. coli isolates were analysed with respect to susceptibility to eight antimicrobials (representing seven different classes: ampicillin, cefotaxime, tetracycline, ciprofloxacin, streptomycin, sulfamethoxazole, trimethoprim, and chloramphenicol.Among surface water isolates, 26% were resistant to at least one class of antimicrobials, and 11% were multidrug-resistant (MDR. In wastewater, the proportions of AMR/MDR E. coli were 76%/62% at HCIs, 69%/19% at the airport WWTP, and 37%/27% and 31%/20% in mWWTP influents and effluents, respectively. Median concentrations of MDR E. coli were 2.2×10(2, 4.0×10(4, 1.8×10(7, and 4.1×10(7 cfu/l in surface water, WWTP effluents, WWTP influents and HCI wastewater, respectively. The different resistance types occurred with similar frequencies among E. coli from surface water and E. coli from municipal wastewater. By contrast, among E. coli from HCI wastewater, resistance to cefotaxime and resistance to ciprofloxacin were significantly overrepresented compared to E. coli from municipal wastewater and surface water. Most cefotaxime-resistant E. coliisolates produced ESBL. In two of the mWWTP, ESBL-producing variants were detected that were identical with respect to phylogenetic group, sequence type, AMR-profile, and ESBL-genotype to variants from HCI wastewater discharged onto the same sewer and sampled on the same day (A1/ST23/CTX-M-1, B23/ST131/CTX-M-15, D2/ST405/CTX-M-15.In

Reduced equations for finite beta tearing modes in tokamaks

International Nuclear Information System (INIS)

Izzo, R.; Monticello, D.A.; DeLucia, J.; Park, W.; Ryu, C.M.

1985-01-01

The equations of resistive magnetohydrodynamics (MHD) are recast in a form that is useful for studying the evolution of those toroidal systems where the fast magnetosonic wave plays no important role. The equations are exact and have del x B = 0 satisfied explicitly. From this set of equations it is a simple matter to derive the equations of reduced MHD to any order in the inverse aspect ratio epsilon of the torus and for βapprox.epsilon or smaller. This is demonstrated by deriving a reduced set of MHD equations that are correct to fifth order in epsilon. These equations contain the exact equilibrium relation and, as such, can be used to find three-dimensional stellarator equilibria. In addition, if a subsidiary ordering in eta, the resistivity, is made, the equations of Glasser, Greene, and Johnson [Phys. Fluids 8, 875 (1967); 19, 567 (1967)] are recovered. This set of reduced equations has been coded by extending the initial value code hIlo [Phys. Fluids 26, 3066 (1983)]. Results obtained for both ideal and resistive linear stability from the reduced equations are compared with those obtained by solving the full set of MHD equations in a cylinder. Good agreement is shown for both zero and finite-beta calculations. Comparisons are also made with analytic theory illuminating the present limitations of the latter

New surface layers with low rolling resistance tested in Denmark

DEFF Research Database (Denmark)

Pettinari, Matteo; Schmidt, Bjarne; Jensen, Bjarne Bo

2014-01-01

Rolling Resistance coefficient that could improve energy efficiency of the roads. In particular, two new types of Split Mastic Asphalt (SMA) were developed and compared to a reference one; both mixtures have a relatively small maximum grain-size, 6 mm and 8 mm, respectively. Surface measurements...

Influence of impurities and ion surface alloying on the corrosion resistance of E110 alloy

International Nuclear Information System (INIS)

Kalin, B. A.; Volkov, N. V.; Valikov, R. A.; Novikov, V. V.; Markelov, V. A.; Pimenov, Yu. V.

2013-01-01

The corrosion resistance of zirconium alloys depends on their structural-phase state, the type of core coolant and operating factors. The formation of a protective oxide film on the zirconium alloys is sensitive to the content of impurity atoms present in the charge base of alloys and accumulating in them in the manufacture of products. The impurity composition of the initial zirconium is determined by the method of its manufacture and generally remains unchanged in the products, deter-mining their properties, including their corrosion resistance. An increased content of impurities (C, N, Al, Mo, Fe) both individually and in their combination negatively affects the corrosion resistance of zirconium and its alloys. One of the potentially effective methods to increase the protective properties of oxide films on zirconium alloys is a surface alloying using the regime of mixing the atoms of a film, preliminarily coated on the surface, and the atoms of a target. This method makes it possible to form a given structural-phase state in the thin surface layer with unique physicochemical properties and thus to in-crease the corrosion resistance and wear resistance of fuel claddings. In this context, the object of investigation was samples of cladding tubes from alloy E110 with various content of impurity elements (nitrogen, aluminum, and carbon) with the aim to reduce the negative influence of impurities on the corrosion resistance by changing the structural-phase state of the surface layer of fuel claddings and fuel assembly components with alloying in the regime of ion mixing of atoms

Antibiotic resistance patterns of Escherichia coli strains isolated from surface water and groundwater samples in a pig production area

Directory of Open Access Journals (Sweden)

Roger Neto Schneider

2009-09-01

Full Text Available The use of antibiotics, so excessive and indiscriminate in intensive animal production, has triggered an increase in the number of resistant microorganisms which can be transported to aquatic environments. The aim of this study was to determine the profile of the antimicrobial resistance of samples of Escherichia coli isolated from groundwater and surface water in a region of pig breeding. Through the test of antimicrobial susceptibility, we analyzed 205 strains of E. coli. A high rate of resistance to cefaclor was observed, both in surface water (51.9% and groundwater (62.9%, while all samples were sensitive to amikacin. The percentages of multi-resistant samples were 25.96% and 26.73% in surface water and groundwater, respectively, while 19.23% and 13.86% were sensitive to all antibiotics tested. It was determined that the rate of multiple antibiotic resistance (MAR was 0.164 for surface water and 0.184 for groundwater. No significant differences were found in the profile of the antimicrobial resistance in strains of E. coli isolated in surface water and groundwater, but the index MAR calculated in certain points of groundwater may offer a potential risk of transmission of resistant genes.

Resistive MHD Stability Analysis in Near Real-time

Science.gov (United States)

Glasser, Alexander; Kolemen, Egemen

2017-10-01

We discuss the feasibility of a near real-time calculation of the tokamak Δ' matrix, which summarizes MHD stability to resistive modes, such as tearing and interchange modes. As the operational phase of ITER approaches, solutions for active feedback tokamak stability control are needed. It has been previously demonstrated that an ideal MHD stability analysis is achievable on a sub- O (1 s) timescale, as is required to control phenomena comparable with the MHD-evolution timescale of ITER. In the present work, we broaden this result to incorporate the effects of resistive MHD modes. Such modes satisfy ideal MHD equations in regions outside narrow resistive layers that form at singular surfaces. We demonstrate that the use of asymptotic expansions at the singular surfaces, as well as the application of state transition matrices, enable a fast, parallelized solution to the singular outer layer boundary value problem, and thereby rapidly compute Δ'. Sponsored by US DOE under DE-SC0015878 and DE-FC02-04ER54698.

Dynamics and fluctuation spectra of electrostatic resistive interchange turbulence

International Nuclear Information System (INIS)

Sydora, R.D.; Leboeuf, J.N.; An, Z.G.; Diamond, P.H.; Lee, G.S.; Hahm, T.S.

1985-11-01

The saturation mechanism for density and potential fluctuation spectra which evolve from linearly unstable electrostatic resistive interchange modes, are investigated using particle simulations. Detailed comparisons of the nonlinear evolution, saturation levels and resultant spectra between two- and three-dimensional sheared magnetic field configurations are made. Significant differences appear. The single rational surface, quasilinear-dominated evolution, fluctuation spectrum is adequately described using a density convection model. For the multiple rational surface case, the potential fluctuations are adequately represented by a balance between the nonlinearly modified source (curvature drive) and linear sink (parallel resistive field line diffusion). An accurate description of the density spectrum requires a mode coupling theory based on the two-point density correlation evolution equation. 24 refs., 15 figs

Comparison of Numerical Approaches to a Steady-State Landscape Equation

Science.gov (United States)

Bachman, S.; Peckham, S.

2008-12-01

A mathematical model of an idealized fluvial landscape has been developed, in which a land surface will evolve to preserve dendritic channel networks as the surface is lowered. The physical basis for this model stems from the equations for conservation of mass for water and sediment. These equations relate the divergence of the 2D vector fields showing the unit-width discharge of water and sediment to the excess rainrate and tectonic uplift on the land surface. The 2D flow direction is taken to be opposite to the water- surface gradient vector. These notions are combined with a generalized Manning-type flow resistance formula and a generalized sediment transport law to give a closed mathematical system that can, in principle, be solved for all variables of interest: discharge of water and sediment, land surface height, vertically- averaged flow velocity, water depth, and shear stress. The hydraulic geometry equations (Leopold et. al, 1964, 1995) are used to incorporate width, depth, velocity, and slope of river channels as powers of the mean-annual river discharge. Combined, they give the unit- width discharge of the stream as a power, γ, of the water surface slope. The simplified steady-state model takes into account three components among those listed above: conservation of mass for water, flow opposite the gradient, and a slope-discharge exponent γ = -1 to reflect mature drainage networks. The mathematical representation of this model appears as a second-order hyperbolic partial differential equation (PDE) where the diffusivity is inversely proportional to the square of the local surface slope. The highly nonlinear nature of this PDE has made it very difficult to solve both analytically and numerically. We present simplistic analytic solutions to this equation which are used to test the validity of the numerical algorithms. We also present three such numerical approaches which have been used in solving the differential equation. The first is based on a

The respiratory system in equations

CERN Document Server

Maury, Bertrand

2013-01-01

The book proposes an introduction to the mathematical modeling of the respiratory system. A detailed introduction on the physiological aspects makes it accessible to a large audience without any prior knowledge on the lung. Different levels of description are proposed, from the lumped models with a small number of parameters (Ordinary Differential Equations), up to infinite dimensional models based on Partial Differential Equations. Besides these two types of differential equations, two chapters are dedicated to resistive networks, and to the way they can be used to investigate the dependence of the resistance of the lung upon geometrical characteristics. The theoretical analysis of the various models is provided, together with state-of-the-art techniques to compute approximate solutions, allowing comparisons with experimental measurements. The book contains several exercises, most of which are accessible to advanced undergraduate students.

Skeletonized wave equation of surface wave dispersion inversion

KAUST Repository

Li, Jing; Schuster, Gerard T.

2016-01-01

We present the theory for wave equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. Similar to wave-equation travel

Theory of asymptotic matching for resistive magnetohydrodynamic stability in a negative magnetic shear configuration

International Nuclear Information System (INIS)

Tokuda, Shinji; Watanabe, Tomoko.

1996-11-01

A theory and a numerical method are presented for the asymptotic matching analysis of resistive magnetohydrodynamic stability in a negative magnetic shear configuration with two rational surfaces. The theory formulates the problem of solving both the Newcomb equations in the ideal MHD region and the inner-layer equations around rational surfaces as boundary value/eigenvalue problems to which the finite element method and the finite difference method can be applied. Hence, the problem of stability analysis is solved by a numerically stable method. The present numerical method has been applied to model equations having analytic solutions in a negative magnetic shear configuration. Comparison of the numerical solutions with the analytical ones verifies the validity of the numerical method proposed. (author)

HESS Opinions: Linking Darcy's equation to the linear reservoir

Science.gov (United States)

Savenije, Hubert H. G.

2018-03-01

In groundwater hydrology, two simple linear equations exist describing the relation between groundwater flow and the gradient driving it: Darcy's equation and the linear reservoir. Both equations are empirical and straightforward, but work at different scales: Darcy's equation at the laboratory scale and the linear reservoir at the watershed scale. Although at first sight they appear similar, it is not trivial to upscale Darcy's equation to the watershed scale without detailed knowledge of the structure or shape of the underlying aquifers. This paper shows that these two equations, combined by the water balance, are indeed identical provided there is equal resistance in space for water entering the subsurface network. This implies that groundwater systems make use of an efficient drainage network, a mostly invisible pattern that has evolved over geological timescales. This drainage network provides equally distributed resistance for water to access the system, connecting the active groundwater body to the stream, much like a leaf is organized to provide all stomata access to moisture at equal resistance. As a result, the timescale of the linear reservoir appears to be inversely proportional to Darcy's conductance, the proportionality being the product of the porosity and the resistance to entering the drainage network. The main question remaining is which physical law lies behind pattern formation in groundwater systems, evolving in a way that resistance to drainage is constant in space. But that is a fundamental question that is equally relevant for understanding the hydraulic properties of leaf veins in plants or of blood veins in animals.

Surface resistance of YBa2Cu3O7 films deposited on LaGaO3 substrates

International Nuclear Information System (INIS)

Cooke, D.W.; Gray, E.R.; Houlton, R.J.; Javadi, H.H.S.; Maez, M.A.; Bennett, B.L.; Rusnak, B.; Meyer, E.A.; Arendt, P.N.; Beery, J.G.; Brown, D.R.; Garzon, F.H.; Raistriek, I.D.; Bolmaro, B.; Elliott, N.E.; Rollett, A.D.; Klein, N.; Muller, G.; Orbach, S.; Piel, H.; Josefowicz, J.Y.; Rensch, O.B.; Drabeck, L.; Gruner, G.

1989-01-01

Superconducting films of YBa 2 Cu 3 O 7 deposited onto LaGaO 3 substrates were prepared by e-beam and magnetron sputtering techniques. Surface resistance measurements made at 22 GHz, 86 GHz, and 148 GHz show that these films are superior to those deposited by similar techniques onto SrTiO 3 . Typical surface resistance values measured at 22 GHz and 12 K are ∼2 m(cgom) with the lowest value being 0.2 m(cgom), which is only 2 to 4 times higher than Nb. The surface resistance is proportional to the square of the measuring frequency

Field dependent surface resistance of niobium on copper cavities

Directory of Open Access Journals (Sweden)

T. Junginger

2015-07-01

Full Text Available The surface resistance R_{S} of superconducting cavities prepared by sputter coating a niobium film on a copper substrate increases significantly stronger with the applied rf field compared to cavities of bulk material. A possible cause is that the thermal boundary resistance between the copper substrate and the niobium film induces heating of the inner cavity wall, resulting in a higher R_{S}. Introducing helium gas in the cavity, and measuring its pressure as a function of applied field allowed to conclude that the inner surface of the cavity is heated up by less than 120 mK when R_{S} increases with E_{acc} by 100  nΩ. This is more than one order of magnitude less than what one would expect from global heating. Additionally, the effects of cooldown speed and low temperature baking have been investigated in the framework of these experiments. It is shown that for the current state of the art niobium on copper cavities there is only a detrimental effect of low temperature baking. A fast cooldown results in a lowered R_{S}.

Effects of photovoltaic module soiling on glass surface resistance and potential-induced degradation

DEFF Research Database (Denmark)

Hacke, Peter; Burton, Patrick; Hendrickson, Alexander

2015-01-01

The sheet resistance of three soil types (Arizona road dust, soot, and sea salt) on glass were measured by the transmission line method as a function of relative humidity (RH) between 39% and 95% at 60°C. Sea salt yielded a 3.5 orders of magnitude decrease in resistance on the glass surface when ...

A model for investigating the influence of road surface texture and tyre tread pattern on rolling resistance

Science.gov (United States)

Hoever, Carsten; Kropp, Wolfgang

2015-09-01

The reduction of rolling resistance is essential for a more environmentally friendly road transportation sector. Both tyre and road design can be utilised to reduce rolling resistance. In both cases a reliable simulation tool is needed which is able to quantify the influence of design parameters on the rolling resistance of a tyre rolling on a specific road surface. In this work a previously developed tyre/road interaction model is extended to account for different tread patterns and for losses due to small-scale tread deformation. Calculated contact forces and tyre vibrations for tyre/road interaction under steady-state rolling are used to predict rolling losses in the tyre. Rolling resistance is calculated for a series of different tyre/road combinations. Results are compared with rolling resistance measurements. The agreement between simulations and measurements is generally very good. It is found that both the tyre structure and small-scale tread deformations contribute to the rolling losses. The small-scale contribution depends mainly on the road roughness profile. The mean profile depth of the road surface is identified to correlate very well with the rolling resistance. Additional calculations are performed for non-traditional rubberised road surfaces, however, with mixed results. This possibly indicates the existence of additional loss mechanisms for these surfaces.

Effects of rational surface density on resistive g turbulence

International Nuclear Information System (INIS)

Beklemishev, A.D.; Sugama, H.; Horton, W.

1993-01-01

The Beklemishev-Horton theory states that the anomalous transport coefficient is proportional to the density of rational surfaces provided that the interaction between the modes localized around different rational surfaces is weak compared with modes of the same helicity. The authors examine the effects of the density of states ρ using resistive g turbulence in 2D (single-helicity) and 3D (multi-helicity) simulations. They find that the modes with different helicities do not equipartition the available energy, but rather the coalescence or inverse cascade effect is strong so that a few low order mode rational surfaces receive most of the energy. The quasilinear flattening at the surfaces is a strong effect and they use bifurcation theory to derive that the effective diffusivity increases as χ eff = χ 0 ρ/(1 - Cρ) where C is a constant determined by interaction integrals. For a sufficiently high density of states Cρ ≤ 1, the higher order nonlinear interaction must be taken into account

Effects of different volume-equated resistance training loading strategies on muscular adaptations in well-trained men.

Science.gov (United States)

Schoenfeld, Brad J; Ratamess, Nicholas A; Peterson, Mark D; Contreras, Bret; Sonmez, G T; Alvar, Brent A

2014-10-01

Regimented resistance training has been shown to promote marked increases in skeletal muscle mass. Although muscle hypertrophy can be attained through a wide range of resistance training programs, the principle of specificity, which states that adaptations are specific to the nature of the applied stimulus, dictates that some programs will promote greater hypertrophy than others. Research is lacking, however, as to the best combination of variables required to maximize hypertophic gains. The purpose of this study was to investigate muscular adaptations to a volume-equated bodybuilding-type training program vs. a powerlifting-type routine in well-trained subjects. Seventeen young men were randomly assigned to either a hypertrophy-type resistance training group that performed 3 sets of 10 repetition maximum (RM) with 90 seconds rest or a strength-type resistance training (ST) group that performed 7 sets of 3RM with a 3-minute rest interval. After 8 weeks, no significant differences were noted in muscle thickness of the biceps brachii. Significant strength differences were found in favor of ST for the 1RM bench press, and a trend was found for greater increases in the 1RM squat. In conclusion, this study showed that both bodybuilding- and powerlifting-type training promote similar increases in muscular size, but powerlifting-type training is superior for enhancing maximal strength.

A liquid aluminum corrosion resistance surface on steel substrate

International Nuclear Information System (INIS)

Wang Deqing; Shi Ziyuan; Zou Longjiang

2003-01-01

The process of hot dipping pure aluminum on a steel substrate followed by oxidation was studied to form a surface layer of aluminum oxide resistant to the corrosion of aluminum melt. The thickness of the pure aluminum layer on the steel substrate is reduced with the increase in temperature and time in initial aluminizing, and the thickness of the aluminum layer does not increase with time at given temperature when identical temperature and complete wetting occur between liquid aluminum and the substrate surface. The thickness of the Fe-Al intermetallic layer on the steel base is increased with increasing bath temperature and time. Based on the experimental data and the mathematics model developed by the study, a maximum exists in the thickness of the Fe-Al intermetallic at certain dipping temperature. X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis reveals that the top portion of the steel substrate is composed of a thin layer of α-Al 2 O 3 , followed by a thinner layer of FeAl 3 , and then a much thicker one of Fe 2 Al 5 on the steel base side. In addition, there is a carbon enrichment zone in diffusion front. The aluminum oxide surface formed on the steel substrate is in perfect condition after corrosion test in liquid aluminum at 750 deg. C for 240 h, showing extremely good resistance to aluminum melt corrosion

Improving wettability of photo-resistive film surface with plasma surface modification for coplanar copper pillar plating of IC substrates

Energy Technology Data Exchange (ETDEWEB)

Xiang, Jing; Wang, Chong; Chen, Yuanming; Wang, Shouxu; Hong, Yan; Zhang, Huaiwu [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Gong, Lijun [Research and Development Department, Guangzhou Fastprint Circuit Tech Co., Ltd., Guangzhou 510663 (China); He, Wei, E-mail: heweiz@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research and Development Department, Guangdong Guanghua Sci-Tech Co., Ltd., Shantou 515000 (China)

2017-07-31

Highlights: • Air atmosphere plasmacould generatehydrophilic groups of photo-resistive film. • Better wettability of photo-resistive filmled tohigher plating uniformity of copper pillars. • New flow isreduced cost, simplified process and elevated productivity. - Abstract: The wettability of the photo-resistive film (PF) surfaces undergoing different pretreatments including the O{sub 2}−CF{sub 4} low-pressure plasma (OCLP) and air plasma (AP), is investigated by water contact angle measurement instrument (WCAMI) before the bottom-up copper pillar plating. Chemical groups analysis performed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectra (XPS) shows that after the OCLP and wash treatment, the wettability of PF surface is attenuated, because embedded fluorine and decreased oxygen content both enhance hydrophobicity. Compared with OCLP treatment, the PF surface treatment by non-toxic air plasma displays features of C−O, O−C=O, C=O and −NO{sub 2} by AIR-FTIR and XPS, and a promoted wettability by WCAM. Under the identical electroplating condition, the surface with a better wettability allows electrolyte to spontaneously soak all the places of vias, resulting in improved copper pillar uniformity. Statistical analysis of metallographic data shows that more coplanar and flat copper pillars are achieved with the PF treatment of air plasma. Such modified copper-pillar-plating technology meets the requirement of accurate impedance, the high density interconnection for IC substrates.

Staphylococcus cohnii--resident of hospital environment: cell-surface features and resistance to antibiotics.

Science.gov (United States)

Szewczyk, E M; Rózalska, M

2000-01-01

Staphylococcus cohnii strains dominated in the environment of investigated hospitals. We isolated 420 strains of the species mainly from hospitals environments, but also from infants--Intensive Care Units patients, its medical staff and non-hospital environments. S. cohnii subspecies cohnii was seen to dominate (361 strains). Seventy seven percent of these strains expressed cell-surface hydrofobicity, most of them were slime producers (61%) and this feature was correlated with their methicillin resistance. Among S. cohnii ssp. cohnii strains isolated from ICU environment 90% were resistant to methicillin, 43% expressed high-level resistance to mupirocin and high percentages were resistant to many other antibiotics. These strains may constitute a dangerous reservoir of resistance genes in a hospital.

Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

KAUST Repository

Almuhammadi, Khaled Hamdan

2016-12-29

Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a method includes preparing a pretreated target area on a CFRP composite surface using laser pulsed irradiation and bonding an electrode to exposed fibers in the pretreated target area. The surface preparation can allow the electrode to have a low contact resistance with the CFRP composite.

A boundary integral equation method using auxiliary interior surface approach for acoustic radiation and scattering in two dimensions.

Science.gov (United States)

Yang, S A

2002-10-01

This paper presents an effective solution method for predicting acoustic radiation and scattering fields in two dimensions. The difficulty of the fictitious characteristic frequency is overcome by incorporating an auxiliary interior surface that satisfies certain boundary condition into the body surface. This process gives rise to a set of uniquely solvable boundary integral equations. Distributing monopoles with unknown strengths over the body and interior surfaces yields the simple source formulation. The modified boundary integral equations are further transformed to ordinary ones that contain nonsingular kernels only. This implementation allows direct application of standard quadrature formulas over the entire integration domain; that is, the collocation points are exactly the positions at which the integration points are located. Selecting the interior surface is an easy task. Moreover, only a few corresponding interior nodal points are sufficient for the computation. Numerical calculations consist of the acoustic radiation and scattering by acoustically hard elliptic and rectangular cylinders. Comparisons with analytical solutions are made. Numerical results demonstrate the efficiency and accuracy of the current solution method.

Wave-equation dispersion inversion of surface waves recorded on irregular topography

KAUST Repository

Li, Jing; Schuster, Gerard T.; Lin, Fan-Chi; Alam, Amir

2017-01-01

Significant topographic variations will strongly influence the amplitudes and phases of propagating surface waves. Such effects should be taken into account, otherwise the S-velocity model inverted from the Rayleigh dispersion curves will contain significant inaccuracies. We now show that the recently developed wave-equation dispersion inversion (WD) method naturally takes into account the effects of topography to give accurate S-velocity tomograms. Application of topographic WD to demonstrates that WD can accurately invert dispersion curves from seismic data recorded over variable topography. We also apply this method to field data recorded on the crest of mountainous terrain and find with higher resolution than the standard WD tomogram.

Wave-equation dispersion inversion of surface waves recorded on irregular topography

KAUST Repository

Li, Jing

2017-08-17

Significant topographic variations will strongly influence the amplitudes and phases of propagating surface waves. Such effects should be taken into account, otherwise the S-velocity model inverted from the Rayleigh dispersion curves will contain significant inaccuracies. We now show that the recently developed wave-equation dispersion inversion (WD) method naturally takes into account the effects of topography to give accurate S-velocity tomograms. Application of topographic WD to demonstrates that WD can accurately invert dispersion curves from seismic data recorded over variable topography. We also apply this method to field data recorded on the crest of mountainous terrain and find with higher resolution than the standard WD tomogram.

Experiments on the rf surface resistance of the perovskite superconductors at 3 GHz

International Nuclear Information System (INIS)

Hein, M.; Klein, N.; Mueller, G.; Piel, H.; Roeth, R.W.

1988-01-01

Since the discovery of the perovskite superconductors many experiments to explore their physical properties have been performed and various potential applications have been considered. The high critical temperature of more than 90 K obtained with Y 1 Ba 2 Cu 3 O/sub 7-δ/ (Y may be substituted by other rare earth elements) makes these superconductors interesting for applications in microwave technology. This has focused the authors interest on the investigation of their rf properties. Due to the sensitivity of the rf surface resistance to surface impurities and remaining non superconducting phases rf measurements are a good means to provide useful information about the quality of sample preparation and about physical properties of the superconductor itself. This contribution reports on the experimental determination of the rf surface resistance of Y 1 Ba 2 Cu 3 O/sub 7-δ/ and Eu 1 Ba 2 Cu 3 O/sub 7-δ/ in the normal and superconducting state at 3 GHz. In the first chapter the preparation of the ceramic samples and initial dc experiments are described. The main part of the paper describes the rf measurements which are performed in a superconducting niobium host cavity. The obtained results for both the surface resistance and the high field performance are discussed with respect to the preparation of the samples and regarding possible applications. 7 references, 7 figures, 2 tables

LEAST SQUARE APPROACH FOR ESTIMATING OF LAND SURFACE TEMPERATURE FROM LANDSAT-8 SATELLITE DATA USING RADIATIVE TRANSFER EQUATION

Directory of Open Access Journals (Sweden)

Y. Jouybari-Moghaddam

2017-09-01

Full Text Available Land Surface Temperature (LST is one of the significant variables measured by remotely sensed data, and it is applied in many environmental and Geoscience studies. The main aim of this study is to develop an algorithm to retrieve the LST from Landsat-8 satellite data using Radiative Transfer Equation (RTE. However, LST can be retrieved from RTE, but, since the RTE has two unknown parameters including LST and surface emissivity, estimating LST from RTE is an under the determined problem. In this study, in order to solve this problem, an approach is proposed an equation set includes two RTE based on Landsat-8 thermal bands (i.e.: band 10 and 11 and two additional equations based on the relation between the Normalized Difference Vegetation Index (NDVI and emissivity of Landsat-8 thermal bands by using simulated data for Landsat-8 bands. The iterative least square approach was used for solving the equation set. The LST derived from proposed algorithm is evaluated by the simulated dataset, built up by MODTRAN. The result shows the Root Mean Squared Error (RMSE is less than 1.18°K. Therefore; the proposed algorithm can be a suitable and robust method to retrieve the LST from Landsat-8 satellite data.

Least Square Approach for Estimating of Land Surface Temperature from LANDSAT-8 Satellite Data Using Radiative Transfer Equation

Science.gov (United States)

Jouybari-Moghaddam, Y.; Saradjian, M. R.; Forati, A. M.

2017-09-01

Land Surface Temperature (LST) is one of the significant variables measured by remotely sensed data, and it is applied in many environmental and Geoscience studies. The main aim of this study is to develop an algorithm to retrieve the LST from Landsat-8 satellite data using Radiative Transfer Equation (RTE). However, LST can be retrieved from RTE, but, since the RTE has two unknown parameters including LST and surface emissivity, estimating LST from RTE is an under the determined problem. In this study, in order to solve this problem, an approach is proposed an equation set includes two RTE based on Landsat-8 thermal bands (i.e.: band 10 and 11) and two additional equations based on the relation between the Normalized Difference Vegetation Index (NDVI) and emissivity of Landsat-8 thermal bands by using simulated data for Landsat-8 bands. The iterative least square approach was used for solving the equation set. The LST derived from proposed algorithm is evaluated by the simulated dataset, built up by MODTRAN. The result shows the Root Mean Squared Error (RMSE) is less than 1.18°K. Therefore; the proposed algorithm can be a suitable and robust method to retrieve the LST from Landsat-8 satellite data.

Effects of PV Module Soiling on Glass Surface Resistance and Potential-Induced Degradation: Preprint

Energy Technology Data Exchange (ETDEWEB)

Hacke, Peter; Burton, Patrick; Hendrickson, Alex; Spartaru, Sergiu; Glick, Stephen; Terwilliger, Kent

2015-12-03

The sheet resistance of three soil types (Arizona road dust, soot, and sea salt) on glass were measured by the transmission line method as a function of relative humidity (RH) between 39% and 95% at 60 degrees C. Sea salt yielded a 3.5 order of magnitude decrease in resistance on the glass surface when the RH was increased over this RH range. Arizona road dust showed reduced sheet resistance at lower RH, but with less humidity sensitivity over the range tested. The soot sample did not show significant resistivity change compared to the unsoiled control. Photovoltaic modules with sea salt on their faces were step-stressed between 25% and 95% RH at 60 degrees C applying -1000 V bias to the active cell circuit. Leakage current from the cell circuit to ground ranged between two and ten times higher than that of the unsoiled controls. Degradation rate of modules with salt on the surface increased with increasing RH and time.

Investigation of series resistance and surface states in Au/n - GaP structures

International Nuclear Information System (INIS)

Kiymaz, A.; Onal, B.; Ozer, M.; Acar, S.

2009-01-01

The variation in series resistance and surface state density of Au/n - GaP Schottky diodes have been systematically investigated at room temperature by using capacitance-voltage C-V and conductance-voltage G/w-V measurements techniques. The C-V and G/w-V characteristics of these devices were investigated by considering series resistance effects in a wide frequency range. It is shown that the capacitance of the Au/n - GaP Schottky diode decreases with increasing frequency. It is assumed that the surface states were responsible for this behaviour. The distribution profile of Rs-V gives a peak in the depletion region at low frequencies and disappears with increasing frequencies

Gaussian-windowed frame based method of moments formulation of surface-integral-equation for extended apertures

Energy Technology Data Exchange (ETDEWEB)

Shlivinski, A., E-mail: amirshli@ee.bgu.ac.il [Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Lomakin, V., E-mail: vlomakin@eng.ucsd.edu [Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0407 (United States)

2016-03-01

Scattering or coupling of electromagnetic beam-field at a surface discontinuity separating two homogeneous or inhomogeneous media with different propagation characteristics is formulated using surface integral equation, which are solved by the Method of Moments with the aid of the Gabor-based Gaussian window frame set of basis and testing functions. The application of the Gaussian window frame provides (i) a mathematically exact and robust tool for spatial-spectral phase-space formulation and analysis of the problem; (ii) a system of linear equations in a transmission-line like form relating mode-like wave objects of one medium with mode-like wave objects of the second medium; (iii) furthermore, an appropriate setting of the frame parameters yields mode-like wave objects that blend plane wave properties (as if solving in the spectral domain) with Green's function properties (as if solving in the spatial domain); and (iv) a representation of the scattered field with Gaussian-beam propagators that may be used in many large (in terms of wavelengths) systems.

A new contact electric resistance technique for in-situ measurement of the electric resistance of surface films on metals in electrolytes at high temperatures and pressures

International Nuclear Information System (INIS)

Saario, T.; Marichev, V.A.

1993-01-01

Surface films play a major role in corrosion assisted cracking. A new Contact Electric Resistance (CER) method has been recently developed for in situ measurement of the electric resistance of surface films. The method has been upgraded for high temperature high pressure application. The technique can be used for any electrically conductive material in any environment including liquid, gas or vacuum. The technique has been used to determine in situ the electric resistance of films on metals during adsorption of water and anions, formation and destruction of oxides and hydrides, electroplating of metals and to study the electric resistance of films on semiconductors. The resolution of the CER technique is 10 -9 Ω, which corresponds to about 0.03 monolayers of deposited copper during electrochemical deposition Cu/Cu 2+ . Electric resistance data can be measured with a frequency of the order of one hertz, which enables one to follow in situ the kinetics of surface film related processes. The kinetics of these processes and their dependence on the environment, temperature, pH and electrochemical potential can be investigated

OPTIMIZATION OF SURFACE RESISTIVITY AND RELATIVE PERMITTIVITY OF SILICONE RUBBER FOR HIGH VOLTAGE APPLICATION USING RESPONSE SURFACE METHODOLOGY

Directory of Open Access Journals (Sweden)

N.N. Ali

2017-06-01

Full Text Available Silicone Rubber (SiR is considered as one of the most established insulator in High Voltage (HV industry. SiR possess a great function ability such as its lighter weight, great heat resistance and substantial electrical insulation properties. Dynamic research were performed all around the world in order to explore the unique insulating behavior of SiR but very little are done on the optimization of SiR in term of their processing parameters and formulation. In this work, four materials and processing factors were introduced; A: Alumina Trihydrate (ATH, B: Dicumyl-Peroxide (DCP, C: mixing speed and D: mixing time in order to analyze its contribution towards improving the surface resistivity and relative permittivity of SIR rubber. The factors range were set based on prior screening and are defined as; ATH (10 – 50 pphr, Dicumyl Peroxide (0.50 -1.50 pphr, speed of mixer (40 – 70 rpm and mixing period (5 – 10 mins which were then varied accordingly to produce an overall 19 samples of SiR blends. The testing results were analyzed using statistical Design of Experiment (DOE by applying two level full factorial from Design Expert Software (v10 to discover the inter-correlation between the factors studied and benefaction of each factor in improving both surface resistivity and relative permittivity responses of produced SiR blends. The model analysis on surface resistivity shows the coefficient of determination R2 value of 88.72% while the one for relative permittivity shows R2 value of 82.34 %. Combination of both dependent variables had yielded an optimization suggestion for SiR formulation and processing strategy of ATH: 50 pphr, DCP: 0.50 pphr, mixing speed: 70 rpm and mixing period: 10 mins with the desirability level of 0.835. The optimized formulation had resulted in the production of SiR blend with the characteristic of surface resistivity of 1.02039x10^14 Ω/sq and relative permittivity of 4.0231, respectively. In conclusion, it can be

Surface microstructures and corrosion resistance of Ni-Ti-Nb shape memory thin films

Energy Technology Data Exchange (ETDEWEB)

Li, Kun [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China); Faculty of Engineering and Environment, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China); Huang, Xu [Memry Corporation, Bethel, CT 06801 (United States); Gibson, Des [Institute of Thin Films, Sensors & Imaging, Scottish Universities Physics Alliance, University of the West of Scotland, Paisley PA1 2BE (United Kingdom); Zheng, Yang; Liu, Jiao; Sun, Lu [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China); Fu, Yong Qing, E-mail: richard.fu@northumbria.ac.uk [Faculty of Engineering and Environment, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom)

2017-08-31

Highlights: • The corrosion resistance of Ni-Ti-Nb shape memory thin films is investigated. • Modified surface oxide layers improve the corrosion resistance of Ni-Ti-Nb films. • Further Nb additions reduce the potential corrosion tendency of the films. - Abstract: Ni-Ti-Nb and Ni-Ti shape memory thin films were sputter-deposited onto silicon substrates and annealed at 600 °C for crystallization. X-ray diffraction (XRD) measurements indicated that all of the annealed Ni-Ti-Nb films were composed of crystalline Ni-Ti (Nb) and Nb-rich grains. X-ray photoelectron spectroscopy (XPS) tests showed that the surfaces of Ni-Ti-Nb films were covered with Ti oxides, NiO and Nb{sub 2}O{sub 5}. The corrosion resistance of the Ni-Ti-Nb films in 3.5 wt.% NaCl solution was investigated using electrochemical tests such as open-circuit potential (OCP) and potentio-dynamic polarization tests. Ni-Ti-Nb films showed higher OCPs, higher corrosion potentials (E{sub corr}) and lower corrosion current densities (i{sub corr}) than the binary Ni-Ti film, which indicated a better corrosion resistance. The reason may be that Nb additions modified the passive layer on the film surface. The OCPs of Ni-Ti-Nb films increased with further Nb additions, whereas no apparent difference of E{sub corr} and i{sub corr} was found among the Ni-Ti-Nb films.

Rapid identification of bacterial resistance to Ciprofloxacin using surface-enhanced Raman spectroscopy

Science.gov (United States)

Kastanos, Evdokia; Hadjigeorgiou, Katerina; Pitris, Costas

2014-02-01

Due to its effectiveness and broad coverage, Ciprofloxacin is the fifth most prescribed antibiotic in the US. As current methods of infection diagnosis and antibiotic sensitivity testing (i.e. an antibiogram) are very time consuming, physicians prescribe ciprofloxacin before obtaining antibiogram results. In order to avoid increasing resistance to the antibiotic, a method was developed to provide both a rapid diagnosis and the sensitivity to the antibiotic. Using Surface Enhanced Raman Spectroscopy, an antibiogram was obtained after exposing the bacteria to Ciprofloxacin for just two hours. Spectral analysis revealed clear separation between sensitive and resistant bacteria and could also offer some inside into the mechanisms of resistance.

Unsteady free surface flow in porous media: One-dimensional model equations including vertical effects and seepage face

Science.gov (United States)

Di Nucci, Carmine

2018-05-01

This note examines the two-dimensional unsteady isothermal free surface flow of an incompressible fluid in a non-deformable, homogeneous, isotropic, and saturated porous medium (with zero recharge and neglecting capillary effects). Coupling a Boussinesq-type model for nonlinear water waves with Darcy's law, the two-dimensional flow problem is solved using one-dimensional model equations including vertical effects and seepage face. In order to take into account the seepage face development, the system equations (given by the continuity and momentum equations) are completed by an integral relation (deduced from the Cauchy theorem). After testing the model against data sets available in the literature, some numerical simulations, concerning the unsteady flow through a rectangular dam (with an impermeable horizontal bottom), are presented and discussed.

Surface electric resistance of YBa2Cu3O7-δ ceramics and its dependence on magnetic field

International Nuclear Information System (INIS)

Gorochev, O.A.; Graboj, I.Eh.; Kaul', A.R.; Mitrofanov, V.P.

1989-01-01

Method of dielectric resonator in the 4.2-300 K temperature range is used to measure surface electric resistance of YBa 2 Cu 3 O 7-δ ceramics samples produced by different technologies. The temperature dependence of surface resistance near transition temperature is calculated. At 77.3 K dependence of electric resistance on external magnetic field at H≤200Oe is determined. Calculated dependence is verified in experiment

Dependence of the microwave surface resistance of superconducting niobium on the magnitude of the rf field

Energy Technology Data Exchange (ETDEWEB)

Romanenko, A.; Grassellino, A. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)

2013-06-24

Utilizing difference in temperature dependencies we decoupled Bardeen-Cooper-Schrieffer (BCS) and residual components of the microwave surface resistance of superconducting niobium at all rf fields up to B{sub rf}{approx}115 mT. We reveal that the residual resistance decreases with field at B{sub rf} Less-Than-Or-Equivalent-To 40 mT and strongly increases in chemically treated niobium at B{sub rf}>80 mT. We find that BCS surface resistance is weakly dependent on field in the clean limit, whereas a strong and peculiar field dependence emerges after 120 Degree-Sign C vacuum baking.

A posteriori error estimates for finite volume approximations of elliptic equations on general surfaces

Energy Technology Data Exchange (ETDEWEB)

Ju, Lili; Tian, Li; Wang, Desheng

2008-10-31

In this paper, we present a residual-based a posteriori error estimate for the finite volume discretization of steady convection– diffusion–reaction equations defined on surfaces in R3, which are often implicitly represented as level sets of smooth functions. Reliability and efficiency of the proposed a posteriori error estimator are rigorously proved. Numerical experiments are also conducted to verify the theoretical results and demonstrate the robustness of the error estimator.

A NUMERICAL APPLICATION TO PREDICT THE RESISTANCE AND WAVE PATTERN OF KRISO CONTAINER SHIP

Directory of Open Access Journals (Sweden)

Yavuz Hakan Ozdemir

2016-06-01

Full Text Available In this study, the computational results for KRISO Container Ship (KCS are presented. CFD analyses are performed to simulate free surface flow around KCS by using RANS approach with success. Also the complicated turbulent flow zone behind the ship is well simulated. The RANS equations and the non-linear free surface boundary conditions are discretized by means of a finite volume scheme. The numerical methodology is found to be appropriate for simulating the turbulent flow around a ship in order to estimate ship total resistance and free surface. By the numerical results, total resistance is calculated for the ship model and the result is satisfactory with regard to the experimental one. As a result of well captured free surface, the wave elevation on/around the hull is compared with the experimental results.

Fracture Resistance, Surface Defects and Structural Strength of Glass

OpenAIRE

Rodichev, Y.M.; Veer, F.A.

2010-01-01

This paper poses the theory that the fracture resistance of basic float glass is dependent on it physicochemical properties and the surface defects fonned under the float glass production, glass processing and handling at the service conditions compose the aggregate basis for structural glass strength assessment. The effect of loading conditions, constructional and technological factors on the engineering strength of glass can be evaluated in certain cases using fracture mechanics with inform...

Effect of shape and resistivity of electrodes in a Faraday MHD duct

International Nuclear Information System (INIS)

Jayakumar, R.; Ghosh, S.

1976-01-01

The object of achieving uniform current distribution in the presence of high axial fields has prompted the use of resistive electrodes in flat and wedge geometries. In the case of flat geometry the technique involves the generation of voltage drop along the surface of the electrodes in the axial direction, due to the Faraday current collected by the electrode and flowing into a lead wire, to reduce or eliminate the discontinuity in the axial electrical field that would otherwise occur, say in case of metal electrodes. In the case of wedge shapes, higher resistance path is provided for the regions where current is likely to concentrate. In the case of flat geometry, the effect of the position of lead wire also influences the current distribution in the plasma and on the electrode surface. The resistive electrodes have been investigated for the actual current distribution by numerically solving the Laplace's equation for current stream function, arising out of Maxwell's equation and generalised Ohm's law. In the case of wedge electrode, the solution has been sought by numerical analysis of both plasma and electrode zones. It is shown that both geometries, the flat geometry with a lead wire shifted optimally from one edge and the wedge electrode can almost eliminate current concentration. (author)

Discrete exterior calculus discretization of incompressible Navier–Stokes equations over surface simplicial meshes

KAUST Repository

Mohamed, Mamdouh S.

2016-02-11

A conservative discretization of incompressible Navier–Stokes equations is developed based on discrete exterior calculus (DEC). A distinguishing feature of our method is the use of an algebraic discretization of the interior product operator and a combinatorial discretization of the wedge product. The governing equations are first rewritten using the exterior calculus notation, replacing vector calculus differential operators by the exterior derivative, Hodge star and wedge product operators. The discretization is then carried out by substituting with the corresponding discrete operators based on the DEC framework. Numerical experiments for flows over surfaces reveal a second order accuracy for the developed scheme when using structured-triangular meshes, and first order accuracy for otherwise unstructured meshes. By construction, the method is conservative in that both mass and vorticity are conserved up to machine precision. The relative error in kinetic energy for inviscid flow test cases converges in a second order fashion with both the mesh size and the time step.

Discrete exterior calculus discretization of incompressible Navier-Stokes equations over surface simplicial meshes

Science.gov (United States)

Mohamed, Mamdouh S.; Hirani, Anil N.; Samtaney, Ravi

2016-05-01

A conservative discretization of incompressible Navier-Stokes equations is developed based on discrete exterior calculus (DEC). A distinguishing feature of our method is the use of an algebraic discretization of the interior product operator and a combinatorial discretization of the wedge product. The governing equations are first rewritten using the exterior calculus notation, replacing vector calculus differential operators by the exterior derivative, Hodge star and wedge product operators. The discretization is then carried out by substituting with the corresponding discrete operators based on the DEC framework. Numerical experiments for flows over surfaces reveal a second order accuracy for the developed scheme when using structured-triangular meshes, and first order accuracy for otherwise unstructured meshes. By construction, the method is conservative in that both mass and vorticity are conserved up to machine precision. The relative error in kinetic energy for inviscid flow test cases converges in a second order fashion with both the mesh size and the time step.

Benney's long wave equations

International Nuclear Information System (INIS)

Lebedev, D.R.

1979-01-01

Benney's equations of motion of incompressible nonviscous fluid with free surface in the approximation of long waves are analyzed. The connection between the Lie algebra of Hamilton plane vector fields and the Benney's momentum equations is shown

Drag resistance measurements for newly applied antifouling coatings and welding seams on ship hull surface

DEFF Research Database (Denmark)

Wang, Xueting; Olsen, S. M.; Andres, E.

Drag resistances of newly applied antifouling coatings and welding seams on ship hull surface have been investigated using a pilot-scale rotary setup. Both conventional biocide-based antifouling (AF) coatings and silicone-based fouling release (FR) coatings have been studied and compared in their......Drag resistances of newly applied antifouling coatings and welding seams on ship hull surface have been investigated using a pilot-scale rotary setup. Both conventional biocide-based antifouling (AF) coatings and silicone-based fouling release (FR) coatings have been studied and compared...

Linear stability of resistive MHD modes: axisymmetric toroidal computation of the outer region matching data

International Nuclear Information System (INIS)

Pletzer, A.; Bondeson, A.; Dewar, R.L.

1993-11-01

The quest to determine accurately the stability of tearing and resistive interchange modes in two-dimensional toroidal geometry led to the development of the PEST-3 code, which is based on solving the singular, zero-frequency ideal MHD equation in the plasma bulk and determining the outer data Δ', Γ' and A' needed to match the outer region solutions to those arising in the inner layers. No assumption regarding the aspect ratio, the number of rational surfaces or the pressure are made a priori. This approach is numerically less demanding than solving the full set of resistive equations, and has the major advantage of non-MHD theories of the non-ideal layers. Good convergence is ensured by the variational Galerkin scheme used to compute the outer matching data. To validate the code, we focus on the growth rate calculations of resistive kink modes which are reproduced in good agreement with those obtained by the full resistive MHD code MARS. (author) 11 figs., 27 refs

Data fusion analysis of a surface direct-current resistivity and well pick data set

International Nuclear Information System (INIS)

Clayton, E.A.; Lewis, R.E.

1995-09-01

Pacific Northwest Laboratory (PNL) has been tasked with testing, debugging, and refining the Hanford Site data fusion workstation (DFW), with the assistance of Coleman Research Corporation (CRC), before delivering the DFW to the environmental restoration client at the Hanford Site. Data fusion is the mathematical combination (or fusion) of disparate data sets into a single interpretation. The data fusion software used in this study was developed by CRC. This report discusses the results of evaluating a surface direct-current (dc) resistivity and well-pick data set using two methods: data fusion technology and commercially available software (i.e., RESIX Plus from Interpex Ltd., Golden, Colorado), the conventional method of analysis. The report compares the two technologies; describes the survey, procedures, and results; and includes conclusions and recommendations. The surface dc resistivity and well-pick data set had been acquired by PNL from a study performed in May 1993 at Eielson Air Force Base near Fairbanks, Alaska. The resistivity survey data were acquired to map the top of permafrost in support of a hydrogeologic study. This data set provided an excellent opportunity to test and refine the dc resistivity capabilities of the DFW; previously, the data fusion software was untested on dc resistivity data. The DFW was used to evaluate the dc resistivity survey data and to produce a 3-dimensional earth model of the study area

Advancement in the Understanding of the Field and Frequency Dependent Microwave Surface Resistance of Niobium

Energy Technology Data Exchange (ETDEWEB)

Martinello, M. [Fermilab; Aderhold, S. [Fermilab; Chandrasekaran, S. K. [Fermilab; Checchin, M. [Fermilab; Grassellino, A. [Fermilab; Melnychuk, O. [Fermilab; Posen, S. [Fermilab; Romanenko, A. [Fermilab; Sergatskov, D. A. [Fermilab

2017-07-24

The radio-frequency surface resistance of niobium resonators is incredibly reduced when nitrogen impurities are dissolved as interstitial in the material, conferring ultra-high Q-factors at medium values of accelerating field. This effect has been observed in both high and low temperature nitrogen treatments. As a matter of fact, the peculiar anti Q-slope observed in nitrogen doped cavities, i.e. the decreasing of the Q-factor with the increasing of the radio-frequency field, come from the decreasing of the BCS surface resistance component as a function of the field. Such peculiar behavior has been considered consequence of the interstitial nitrogen present in the niobium lattice after the doping treatment. The study here presented show the field dependence of the BCS surface resistance of cavities with different resonant frequencies, such as: 650 MHz, 1.3 GHz, 2.6 GHz and 3.9 GHz, and processed with different state-of-the-art surface treatments. These findings show for the first time that the anti Q-slope might be seen at high frequency even for clean Niobium cavities, revealing useful suggestion on the physics underneath the anti Q-slope effect.

Elements of partial differential equations

CERN Document Server

Sneddon, Ian Naismith

1957-01-01

Geared toward students of applied rather than pure mathematics, this volume introduces elements of partial differential equations. Its focus is primarily upon finding solutions to particular equations rather than general theory.Topics include ordinary differential equations in more than two variables, partial differential equations of the first and second orders, Laplace's equation, the wave equation, and the diffusion equation. A helpful Appendix offers information on systems of surfaces, and solutions to the odd-numbered problems appear at the end of the book. Readers pursuing independent st

Erosion resistance of pipe bends with bio-inspired internal surfaces

Science.gov (United States)

Zhang, Chengchun; Matar, Omar

2013-11-01

Guided by the structure of a shell surface, a bio-inspired surface is proposed to enhance the erosion resistance of pipe bends carrying crude-oil and sand in the turbulent flow regime. A comparison of the erosion rate between a smooth bend and the bio-inspired one is carried out using numerical simulations: large eddy simulations are used to simulate turbulence, and these are coupled to a discrete element method for the solid particles. The results indicate that the bio-inspired surface can control effectively the liquid-solid flow near the wall, and decrease the particle-wall force. This, then, leads to a reduction in the erosion rate brought about by the sand transported by the crude-oil in the pipe bend. The China Scholarship Council is gratefully acknowledged.

Effects of striated laser tracks on thermal fatigue resistance of cast iron samples with biomimetic non-smooth surface

International Nuclear Information System (INIS)

Tong, Xin; Zhou, Hong; Liu, Min; Dai, Ming-jiang

2011-01-01

In order to enhance the thermal fatigue resistance of cast iron materials, the samples with biomimetic non-smooth surface were processed by Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser. With self-controlled thermal fatigue test method, the thermal fatigue resistance of smooth and non-smooth samples was investigated. The effects of striated laser tracks on thermal fatigue resistance were also studied. The results indicated that biomimetic non-smooth surface was benefit for improving thermal fatigue resistance of cast iron sample. The striated non-smooth units formed by laser tracks which were vertical with thermal cracks had the best propagation resistance. The mechanisms behind these influences were discussed, and some schematic drawings were introduced to describe them.

Resistance of Pseudomonas aeruginosa to liquid disinfectants on contaminated surfaces before formation of biofilms.

Science.gov (United States)

Sagripanti, J L; Bonifacino, A

2000-01-01

A comparison was made of the effectiveness of popular disinfectants (Cavicide, Cidexplus, Clorox, Exspor, Lysol, Renalin, and Wavicide) under conditions prescribed for disinfection in the respective product labels on Pseudomonas aeruginosa either in suspension or deposited onto surfaces of metallic or polymeric plastic devices. The testing also included 7 nonformulated germicidal agents (glutaraldehyde, formaldehyde, peracetic acid, hydrogen peroxide, sodium hypochlorite, phenol, and cupric ascorbate) commonly used in disinfection and decontamination. Results showed that P. aeruginosa is on average 300-fold more resistant when present on contaminated surfaces than in suspension. This increase in resistance agrees with results reported in studies of biofilms, but unexpectedly, it precedes biofilm formation. The surface to which bacteria are attached can influence the effectiveness of disinfectants. Viable bacteria attached to devices may require dislodging through more than a one-step method for detection. The data, obtained with a sensitive and quantitative test, suggest that disinfectants are less effective on contaminated surfaces than generally acknowledged.

A rapid numerical method for solving Serre-Green-Naghdi equations describing long free surface gravity waves

Science.gov (United States)

Favrie, N.; Gavrilyuk, S.

2017-07-01

A new numerical method for solving the Serre-Green-Naghdi (SGN) equations describing dispersive waves on shallow water is proposed. From the mathematical point of view, the SGN equations are the Euler-Lagrange equations for a ‘master’ lagrangian submitted to a differential constraint which is the mass conservation law. One major numerical challenge in solving the SGN equations is the resolution of an elliptic problem at each time instant. This is the most time-consuming part of the numerical method. The idea is to replace the ‘master’ lagrangian by a one-parameter family of ‘augmented’ lagrangians, depending on a greater number of variables, for which the corresponding Euler-Lagrange equations are hyperbolic. In such an approach, the ‘master’ lagrangian is recovered by the augmented lagrangian in some limit (for example, when the corresponding parameter is large). The choice of such a family of augmented lagrangians is proposed and discussed. The corresponding hyperbolic system is numerically solved by a Godunov type method. Numerical solutions are compared with exact solutions to the SGN equations. It appears that the computational time in solving the hyperbolic system is much lower than in the case where the elliptic operator is inverted. The new method is applied, in particular, to the study of ‘Favre waves’ representing non-stationary undular bores produced after reflection of the fluid flow with a free surface at an immobile wall.

Corrosion resistance and cytocompatibility of tantalum-surface-functionalized biomedical ZK60 Mg alloy

International Nuclear Information System (INIS)

Jin, Weihong; Wang, Guomin; Lin, Zhengjie; Feng, Hongqing; Li, Wan; Peng, Xiang; Qasim, Abdul Mateen; Chu, Paul K.

2017-01-01

Highlights: • Films comprising Ta_2O_5, Ta suboxide, and Ta are sputter-deposited on ZK60 Mg alloy. • The Ta-containing film significantly mitigates degradation of ZK60. • The modified ZK60 exhibits notably enhanced cell adhesion and proliferation. - Abstract: Tantalum (Ta) is introduced to the surface of the ZK60 Mg alloy by reactive magnetron sputtering to enhance the corrosion resistance and cytocompatibility. The film thickness and composition, corrosion behavior, and cytocompatibility are studied by various techniques systematically. The surface layer composed of Ta_2O_5, Ta suboxide, and Ta increases the corrosion resistance of ZK60 while simultaneously improving cell attachment, spreading, and proliferation in vitro. The enhancement mechanism is proposed and discussed.

Why did the bear cross the road? Comparing the performance of multiple resistance surfaces and connectivity modeling methods

Science.gov (United States)

Samuel A. Cushman; Jesse S. Lewis; Erin L. Landguth

2014-01-01

There have been few assessments of the performance of alternative resistance surfaces, and little is known about how connectivity modeling approaches differ in their ability to predict organism movements. In this paper, we evaluate the performance of four connectivity modeling approaches applied to two resistance surfaces in predicting the locations of highway...

A general analytical equation for phase diagrams of an N-layer ferroelectric thin film with two surface layers

Energy Technology Data Exchange (ETDEWEB)

Lu, Z X; Teng, B H; Rong, Y H; Lu, X H; Yang, X [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)], E-mail: phytbh@163.com

2010-03-15

Within the framework of effective-field theory with correlations, the phase diagrams of an N-layer ferroelectric thin film with two surface layers are studied by the differential operator technique based on the spin-1/2 transverse Ising model. A general analytical equation for the phase diagram of a ferroelectric thin film with arbitrary layer number as well as exchange interactions and transverse fields is derived, and then the effects of exchange interactions and transverse fields on phase diagrams are discussed for an arbitrary layer number N. Meanwhile, the crossover features, from the ferroelectric-dominant phase diagram (FPD) to the paraelectric-dominant phase diagram (PPD), for various parameters of an N-layer ferroelectric thin film with two surface layers are investigated. As a result, an N-independent common intersection point equation is obtained, and the three-dimensional curved surfaces for the crossover values are constructed. In comparison with the usual mean-field approximation, the differential operator technique with correlations reduces to some extent the ferroelectric features of a ferroelectric thin film.

Generalized reduced MHD equations

International Nuclear Information System (INIS)

Kruger, S.E.; Hegna, C.C.; Callen, J.D.

1998-07-01

A new derivation of reduced magnetohydrodynamic (MHD) equations is presented. A multiple-time-scale expansion is employed. It has the advantage of clearly separating the three time scales of the problem associated with (1) MHD equilibrium, (2) fluctuations whose wave vector is aligned perpendicular to the magnetic field, and (3) those aligned parallel to the magnetic field. The derivation is carried out without relying on a large aspect ratio assumption; therefore this model can be applied to any general toroidal configuration. By accounting for the MHD equilibrium and constraints to eliminate the fast perpendicular waves, equations are derived to evolve scalar potential quantities on a time scale associated with the parallel wave vector (shear-alfven wave time scale), which is the time scale of interest for MHD instability studies. Careful attention is given in the derivation to satisfy energy conservation and to have manifestly divergence-free magnetic fields to all orders in the expansion parameter. Additionally, neoclassical closures and equilibrium shear flow effects are easily accounted for in this model. Equations for the inner resistive layer are derived which reproduce the linear ideal and resistive stability criterion of Glasser, Greene, and Johnson

Near-surface characterization for seismic exploration based on gravity and resistivity data

Czech Academy of Sciences Publication Activity Database

Mrlina, Jan

(2016), č. článku 41892. [Middle East Geoscience Conference and Exhibition /12./. Manama, 07.03.2016-10.03.2016] Institutional support: RVO:67985530 Keywords : gravity and resistivity surveys * near-surface formations * seismic velocity Subject RIV: DC - Siesmology, Volcanology, Earth Structure

Hamilton's equations for a fluid membrane

International Nuclear Information System (INIS)

Capovilla, R; Guven, J; Rojas, E

2005-01-01

Consider a homogeneous fluid membrane described by the Helfrich-Canham energy, quadratic in the mean curvature of the membrane surface. The shape equation that determines equilibrium configurations is fourth order in derivatives and cubic in the mean curvature. We introduce a Hamiltonian formulation of this equation which dismantles it into a set of coupled first-order equations. This involves interpreting the Helfrich-Canham energy as an action; equilibrium surfaces are generated by the evolution of space curves. Two features complicate the implementation of a Hamiltonian framework. (i) The action involves second derivatives. This requires treating the velocity as a phase-space variable and the introduction of its conjugate momentum. The canonical Hamiltonian is constructed on this phase space. (ii) The action possesses a local symmetry-reparametrization invariance. The two labels we use to parametrize points on the surface are themselves physically irrelevant. This symmetry implies primary constraints, one for each label, that need to be implemented within the Hamiltonian. The two Lagrange multipliers associated with these constraints are identified as the components of the acceleration tangential to the surface. The conservation of the primary constraints implies two secondary constraints, fixing the tangential components of the momentum conjugate to the position. Hamilton's equations are derived and the appropriate initial conditions on the phase-space variables are identified. Finally, it is shown how the shape equation can be reconstructed from these equations

Superhydrophobic surface fabricated on iron substrate by black chromium electrodeposition and its corrosion resistance property

Energy Technology Data Exchange (ETDEWEB)

Zhang, Bo [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Feng, Haitao [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Lin, Feng [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Yabin [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Wang, Liping [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Dong, Yaping [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Li, Wu, E-mail: liwu2016@126.com [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China)

2016-08-15

Highlights: • Superhydrophobic surface was fabricated by black chromium electrodeposition and stearic acid modification. • The reaction process is simple, and of low cost, and no special instrument or environment is needed. • The obtained superhydrophobic surface presents good water repellency, and performs well at corrosion resistance. - Abstract: The fabrication of superhydrophobic surface on iron substrate is carried out through 20 min black chromium electrodeposition, followed by immersing in 0.05 M ethanolic stearic acid solution for 12 h. The resultant superhydrophobic complex film is characterized by scanning electron microscope (SEM), disperse Spectrometer (EDS), atomic force microscope (AFM), water contact angle (CA), sliding angle (SA) and X-ray photoelectron spectroscope (XPS), and its corrosion resistance property is measured with cyclic voltammetry (CV), linear polarization and electrochemical impedance spectroscopy (EIS). The results show that the fabricated superhydrophobic film has excellent water repellency (CA, 158.8°; SA, 2.1°) and significantly high corrosion resistance (1.31 × 10{sup 6} Ω cm{sup −2}) and excellent corrosion protection efficiency (99.94%).

Influence of gas-powder laser cladding’s technological parameters on structural characteristics of corrosion-resistant steels’ restored surface layer

Science.gov (United States)

Krylova, S. E.; Oplesnin, S. P.; Goltyapin, M. I.

2018-03-01

The results of the developed industrial technology for surface restoration of corrosion-resistant steels by laser surfacing are presented in the article. A comparative analysis of the microstructure of the welded wear-resistant layer, the fusion zone with the base material and the diffusion zone for different technological surfacing regimes are given. Dyrometric studies and nondestructive testing of the deposited layer for defects were performed

Resistive stability of the cylindrical spheromak

International Nuclear Information System (INIS)

DeLucia, J.; Jardin, S.C.; Glasser, A.H.

1983-11-01

The growth rates for resistive instabilities in a straight circular cylinder with spheromak profiles are computed by using two complementary methods. The first method employs boundary layer analysis and asymptotic matching, most valid for values of the magnetic Reynolds number S greater than or equal to 10 5 . The second method solved the full linearized resistive MHD equations as an initial value problem, utilizing zone packing around the mode rational surface. Resolution requirements limit this to S less than or equal to 10 7 . The results from these two methods agree to better than 1 in 10 3 in the overlap region 10 7 greater than or equal to S greater than or equal to 10 5 . A scan of parameter space reveals that for parabolic q-profiles, the least unstable configurations have q 0 R/a approx. 0.67. The Hall term in Ohm's Law is easily incorporated into both methods. Recalculating the resistive MHD growth rates in the presence of this term shows that the resistive interchange mode is completely stabilized for a large enough value of the ion cyclotron time

Development of a High Slip-resistant Footwear Outsole Using a Hybrid Rubber Surface Pattern

OpenAIRE

YAMAGUCHI, Takeshi; HOKKIRIGAWA, Kazuo

2014-01-01

Abstract: The present study examined whether a new footwear outsole with tread blocks and a hybrid rubber surface pattern, composed of rough and smooth surfaces, could increase slip resistance and reduce the risk of fall while walking on a wet floor surface. A drag test was performed to measure static and dynamic coefficient of friction (SCOF and DCOF, respectively) values for the footwear with the hybrid rubber surface pattern outsole and two types of commercially available boots that are co...

Stability analysis of resistive MHD modes via a new numerical matching technique

International Nuclear Information System (INIS)

Furukawa, M.; Tokuda, S.; Zheng, L.-J.

2009-01-01

Full text: Asymptotic matching technique is one of the principal methods for calculating linear stability of resistive magnetohydrodynamics (MHD) modes such as tearing modes. In applying the asymptotic method, the plasma region is divided into two regions: a thin inner layer around the mode-resonant surface and ideal MHD regions except for the layer. If we try to solve this asymptotic matching problem numerically, we meet practical difficulties. Firstly, the inertia-less ideal MHD equation or the Newcomb equation has a regular singular point at the mode-resonant surface, leading to the so-called big and small solutions. Since the big solution is not square-integrable, it needs sophisticated treatment. Even if such a treatment is applied, the matching data or the ratio of small solution to the big one, has been revealed to be sensitive to local MHD equilibrium accuracy and grid structure at the mode-resonant surface by numerical experiments. Secondly, one of the independent solutions in the inner layer, which should be matched onto the ideal MHD solution, is not square-integrable. The response formalism has been adopted to resolve this problem. In the present paper, we propose a new method for computing the linear stability of resistive MHD modes via matching technique, where the plasma region is divided into ideal MHD regions and an inner region with finite width. The matching technique using an inner region with finite width was recently developed for ideal MHD modes in cylindrical geometry, and good performance was shown. Our method extends this idea to resistive MHD modes. In the inner region, the low-beta reduced MHD equations are solved, and the solution is matched onto the solution of the Newcomb equation by using boundary conditions such that the parallel electric field vanishes properly as approaching the computational boundaries. If we use the inner region with finite width, the practical difficulties raised above can be avoided from the beginning. Figure

Surface composition, microstructure and corrosion resistance of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

International Nuclear Information System (INIS)

Li, P.; Lei, M.K.; Zhu, X.P.

2011-01-01

High-intensity pulsed ion beam (HIPIB) irradiation of AZ31 magnesium alloy is performed and electrochemical corrosion experiment of irradiated samples is carried out by using potentiodynamic polarization technology in order to explore the effect of HIPIB irradiation on corrosion resistance of magnesium alloy. The surface composition, cross-sectional morphology and microstructure are characterized by using electron probe microanalyzer, optical microscope and transmission electron microscope, respectively. The results indicated that HIPIB irradiation leads to a significant improvement in corrosion resistance of magnesium alloy, in terms of the considerable increase in both corrosion potential and pitting breakdown potential. The microstructural refinement and surface purification induced by HIPIB irradiation are responsible for the improved corrosion resistance. - Research Highlights: → A modified layer about 30 μm thick is obtained by HIPIB irradiation. → Selective ablation of element/impurity phase having lower melting point is observed. → More importantly, microstructural refinement occurred on the irradiated surface. → The modified layer exhibited a significantly improved corrosion resistance. → Improved corrosion resistance is ascribed to the combined effect induced by HIPIB.

On the field dependent surface resistance of niobium on copper cavities

CERN Document Server

Junginger, Tobias

2015-01-01

The surface resistance Rs of superconducting cavities prepared by sputter coating a thin niobium film on a copper substrate increases significantly stronger with the applied RF field compared to cavities of bulk material. A possible cause is that due to the thermal boundary resistance between the copper substrate and the niobium film Rs is enhanced due to global heating of the inner cavity wall. Introducing helium gas in the cavity and measuring its pressure as a function of applied field allowed to conclude that the inner surface of the cavity is heated up by only 60+/-60 mK when Rs increases with Eacc by 100 nOhm. This is more than one order of magnitude less than what one would expect from global heating. Additionally the effect of cooldown speed and low temperature baking have been investigated in the framework of these experiments. It is shown that for current state of the art niobium on copper cavities there is only a detrimental effect of low temperature baking. A fast cooldown results in a lowered Rs.

Abrasion Resistance of Nano Silica Modified Roller Compacted Rubbercrete: Cantabro Loss Method and Response Surface Methodology Approach

Science.gov (United States)

Adamu, Musa; Mohammed, Bashar S.; Shafiq, Nasir

2018-04-01

Roller compacted concrete (RCC) when used for pavement is subjected to skidding/rubbing by wheels of moving vehicles, this causes pavement surface to wear out and abrade. Therefore, abrasion resistance is one of the most important properties of concern for RCC pavement. In this study, response surface methodology was used to design, evaluate and analyze the effect of partial replacement of fine aggregate with crumb rubber, and addition of nano silica on the abrasion resistance of roller compacted rubbercrete (RCR). RCR is the terminology used for RCC pavement where crumb rubber was used as partial replacement to fine aggregate. The Box-Behnken design method was used to develop the mixtures combinations using 10%, 20%, and 30% crumb rubber with 0%, 1%, and 2% nano silica. The Cantabro loss method was used to measure the abrasion resistance. The results showed that the abrasion resistance of RCR decreases with increase in crumb rubber content, and increases with increase in addition of nano silica. The analysis of variance shows that the model developed using response surface methodology (RSM) has a very good degree of correlation, and can be used to predict the abrasion resistance of RCR with a percentage error of 5.44%. The combination of 10.76% crumb rubber and 1.59% nano silica yielded the best combinations of RCR in terms of abrasion resistance of RCR.

Study of the Electromagnetic Waves Propagation over the Improved Fractal Sea Surface Based on Parabolic Equation Method

Directory of Open Access Journals (Sweden)

Wenwan Ding

2016-01-01

Full Text Available An improved fractal sea surface model, which can describe the capillary waves very well, is introduced to simulate the one-dimension rough sea surface. In this model, the propagation of electromagnetic waves (EWs is computed by the parabolic equation (PE method using the finite-difference (FD algorithm. The numerical simulation results of the introduced model are compared with those of the Miller-Brown model and the Elfouhaily spectrum inversion model. It has been shown that the effects of the fine structure of the sea surface on the EWs propagation in the introduced model are more apparent than those in the other two models.

Influence of surface condition on the corrosion resistance of copper alloy condenser tubes in sea water

Energy Technology Data Exchange (ETDEWEB)

Sato, S; Nagata, K; Yamauchi, S

1979-07-01

Investigation was made on the influence of various surface conditions of aluminum brass tube. The corrosion behavior of aluminum brass tube, with nine kinds of surface conditions, was studied in stagnant 0.1N NaHCo/sub 3/ solution and flowing sea water (natural, Fe/sup + +/ containing and S/sup - -/ containing water). Surface treatments investigated contained bright annealing, special annealing to form carbon film, hot oxidizing and pickling. Anodic polarization measurements in 0.1N NaHCO/sub 3/ solution showed that the oxidized surface was superior and that the pickled surface was inferior. However, relation between these characteristics and corrosion resistance in sea water has not been established. Electrochemical characteristics in flowing sea water were dependent on the surface conditions in the very beginning of immersion time; nobler corrosion potential for the surface with carbon film, higher polarization resistance for the bright annealed and the oxidized surface, and faster decrease of polarization resistance in S/sup - -/ containing sea water for the pickled surface. However, these differences disappeared in the immersion time of only 2 to 7 days. It was revealed, by the statistical analysis on the corrosion depth in corrosion test in flowing sea water and in jet impingement test, that the corrosion behavior was not influenced by surface conditions, but was significantly influenced by quality of sea water and sponge ball cleaning. Sulfide ion of 0.05 ppm caused severe pitting corrosion, and sponge ball cleaning of 5 chances a week caused erosion corrosion. From above results, it was concluded that surface conditions of aluminum brass were not important to sea water corrosion, and that quality of sea water and operating condition such as sponge ball cleaning were more significant.

Modeling electrochemical resistance with coal surface properties in a direct carbon fuel cell based on molten carbonate

Science.gov (United States)

Eom, Seongyong; Ahn, Seongyool; Kang, Kijoong; Choi, Gyungmin

2017-12-01

In this study, a numerical model of activation and ohmic polarization is modified, taking into account the correlation function between surface properties and inner resistance. To investigate the correlation function, the surface properties of coal are changed by acid treatment, and the correlations between the inner resistance measured by half-cell tests and the surface characteristics are analyzed. A comparison between the model and experimental results demonstrates that the absolute average deviations for each fuel are less than 10%. The numerical results show that the sensitivities of the coal surface properties affecting polarization losses change depending on the operating temperature. The surface oxygen concentrations affect the activation polarization and the sensitivity decreased with increasing temperature. The surface ash of coal is an additional index to be considered along with ohmic polarization and it has the greatest effect on the surface properties at 973 K.

Resistivity of thin gold films on mica induced by electron-surface scattering: Application of quantitative scanning tunneling microscopy

International Nuclear Information System (INIS)

Robles, Marcelo E.; Gonzalez-Fuentes, Claudio A.; Henriquez, Ricardo; Kremer, German; Moraga, Luis; Oyarzun, Simón; Suarez, Marco Antonio; Flores, Marcos; Munoz, Raul C.

2012-01-01

We report a comparison between the resistivity measured on thin gold films deposited on mica, with predictions based upon classical theories of size effects (Drude's, Sondheimer's and Calecki's), as well as predictions based upon quantum theories of electron-surface scattering (the modified theory of Sheng, Xing and Wang, the theory of Tesanovic, Jaric and Maekawa, and that of Trivedi and Aschroft). From topographic images of the surface recorded with a Scanning Tunneling Microscope, we determined the rms roughness amplitude, δ and the lateral correlation length, ξ corresponding to a Gaussian representation of the average height-height autocorrelation function, describing the roughness of each sample in the scale of length set by the Fermi wave length. Using (δ, ξ) as input data, we present a rigorous comparison between resistivity data and predictions based upon the theory of Calecki as well as quantum theoretical predictions without adjustable parameters. The resistivity was measured on gold films of different thickness evaporated onto mica substrates, between 4 K and 300 K. The resistivity data covers the range 0.1 < x(T) < 6.8, for 4 K < T < 300 K, where x(T) is the ratio between film thickness and electron mean free path in the bulk at temperature T. We experimentally identify electron-surface and electron-phonon scattering as the microscopic electron scattering mechanisms giving rise to the macroscopic resistivity. The different theories are all capable of estimating the thin film resistivity to an accuracy better than 10%; however the mean free path and the resistivity characterizing the bulk turn out to depend on film thickness. Surprisingly, only the Sondheimer theory and its quantum version, the modified theory of Sheng, Xing and Wang, predict and increase in resistivity induced by size effects that seems consistent with published galvanomagnetic phenomena also arising from electron-surface scattering measured at low temperatures.

A Calderón multiplicative preconditioner for coupled surface-volume electric field integral equations

KAUST Repository

Bagci, Hakan

2010-08-01

A well-conditioned coupled set of surface (S) and volume (V) electric field integral equations (S-EFIE and V-EFIE) for analyzing wave interactions with densely discretized composite structures is presented. Whereas the V-EFIE operator is well-posed even when applied to densely discretized volumes, a classically formulated S-EFIE operator is ill-posed when applied to densely discretized surfaces. This renders the discretized coupled S-EFIE and V-EFIE system ill-conditioned, and its iterative solution inefficient or even impossible. The proposed scheme regularizes the coupled set of S-EFIE and V-EFIE using a Calderón multiplicative preconditioner (CMP)-based technique. The resulting scheme enables the efficient analysis of electromagnetic interactions with composite structures containing fine/subwavelength geometric features. Numerical examples demonstrate the efficiency of the proposed scheme. © 2006 IEEE.

Influence of multi-wavelength laser irradiation of enamel and dentin surfaces at 0.355, 2.94, and 9.4 μm on surface morphology, permeability, and acid resistance.

Science.gov (United States)

Chang, Nai-Yuan N; Jew, Jamison M; Simon, Jacob C; Chen, Kenneth H; Lee, Robert C; Fried, William A; Cho, Jinny; Darling, Cynthia L; Fried, Daniel

2017-12-01

Ultraviolet (UV) and infrared (IR) lasers can be used to specifically target protein, water, and mineral, respectively, in dental hard tissues to produce varying changes in surface morphology, permeability, reflectivity, and acid resistance. The purpose of this study was to explore the influence of laser irradiation and topical fluoride application on the surface morphology, permeability, reflectivity, and acid resistance of enamel and dentin to shed light on the mechanism of interaction and develop more effective treatments. Twelve bovine enamel surfaces and twelve bovine dentin surfaces were irradiated with various combinations of lasers operating at 0.355 (Freq.-tripled Nd:YAG (UV) laser), 2.94 (Er:YAG laser), and 9.4 μm (CO 2 laser), and surfaces were exposed to an acidulated phosphate fluoride gel and an acid challenge. Changes in the surface morphology, acid resistance, and permeability were measured using digital microscopy, polarized light microscopy, near-IR reflectance, fluorescence, polarization sensitive-optical coherence tomography (PS-OCT), and surface dehydration rate measurements. Different laser treatments dramatically influenced the surface morphology and permeability of both enamel and dentin. CO 2 laser irradiation melted tooth surfaces. Er:YAG and UV lasers, while not melting tooth surfaces, showed markedly different surface roughness. Er:YAG irradiation led to significantly rougher enamel and dentin surfaces and led to higher permeability. There were significant differences in acid resistance among the various treatment groups. Surface dehydration measurements showed significant changes in permeability after laser treatments, application of fluoride and after exposure to demineralization. CO 2 laser irradiation was most effective in inhibiting demineralization on enamel while topical fluoride was most effective for dentin surfaces. Lasers Surg. Med. 49:913-927, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Radio-frequency surface resistance of tunmgsten in weak magnetic fields

International Nuclear Information System (INIS)

Bojko, V.V.; Toniya, V.A.

1988-01-01

The surface impedance of single crystal tungsten specimens under anomalous skin effect in a magnetic field H is investigated experimentally. It is found that in magnetic fields ranging from 0 to 1 kOe the surface resistance R of tungsten varies in a nonmonotonous manner and experiences several extrema. The position of the latter with respect to magnetic field strength depends on the conduction electron mean free path l, on the roughness of the specimen surface and frequency of the irradiating electromagnetic wave. It is found that such behavior of R(H) is due to variation of the nature of the conduction electron scattering at the metal-external medium interface with increasing H. The geometrical dimensions of the surface roughnesses are determined at which diffuse scattering of the current occurs. The results are compared with the theoretical calculations, and a number of contradictions between the theory and experiments are noted. The effect of the magnetic field of the electromagnetic wave H ∼ on the conductivity of tungsten in the absence of H is studied

Extremal Kähler metrics and Bach-Merkulov equations

Science.gov (United States)

Koca, Caner

2013-08-01

In this paper, we study a coupled system of equations on oriented compact 4-manifolds which we call the Bach-Merkulov equations. These equations can be thought of as the conformally invariant version of the classical Einstein-Maxwell equations. Inspired by the work of C. LeBrun on Einstein-Maxwell equations on compact Kähler surfaces, we give a variational characterization of solutions to Bach-Merkulov equations as critical points of the Weyl functional. We also show that extremal Kähler metrics are solutions to these equations, although, contrary to the Einstein-Maxwell analogue, they are not necessarily minimizers of the Weyl functional. We illustrate this phenomenon by studying the Calabi action on Hirzebruch surfaces.

An ultrathin wide-band planar metamaterial absorber based on a fractal frequency selective surface and resistive film

International Nuclear Information System (INIS)

Fan Yue-Nong; Cheng Yong-Zhi; Nie Yan; Wang Xian; Gong Rong-Zhou

2013-01-01

We propose an ultrathin wide-band metamaterial absorber (MA) based on a Minkowski (MIK) fractal frequency selective surface and resistive film. This absorber consists of a periodic arrangement of dielectric substrates sandwiched with an MIK fractal loop structure electric resonator and a resistive film. The finite element method is used to simulate and analyze the absorption of the MA. Compared with the MA-backed copper film, the designed MA-backed resistive film exhibits an absorption of 90% at a frequency region of 2 GHz–20 GHz. The power loss density distribution of the MA is further illustrated to explain the mechanism of the proposed MA. Simulated absorptions at different incidence cases indicate that this absorber is polarization-insensitive and wide-angled. Finally, further simulated results indicate that the surface resistance of the resistive film and the dielectric constant of the substrate can affect the absorbing property of the MA. This absorber may be used in many military fields

Superhydrophobic copper surfaces fabricated by fatty acid soaps in aqueous solution for excellent corrosion resistance

Energy Technology Data Exchange (ETDEWEB)

Xu, Wenlong; Hu, Yuanyuan; Bao, Wenda; Xie, Xiaoyu; Liu, Yiran; Song, Aixin, E-mail: songaixin@sdu.edu.cn; Hao, Jingcheng

2017-03-31

Highlights: • The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol. • The fabrication process of superhydrophobic metal surfaces greatly increases the safety in industrial manufacture in commercial scale. • The superhydrophobic copper surfaces show excellent corrosion resistance. - Abstract: A simple and safe one-step immersion method was developed to obtain the stable superhydrophobic copper surfaces with excellent corrosion resistance ability using fatty acids in water-medium instead of ethanol. An organic alkali, N,N-dimethylcyclohexylamine (DMCHA), was chosen to solve the poor solubility of fatty acids in water and the high Krafft point of carboxylate salts with inorganic counterions. The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol (more than 2 d), which is universally feasible for the fabrication of superhydrophobic metal surfaces in industry scale, thereby greatly increasing the safety in industrial manufacture.

Resistive Magnetohydrodynamics Simulation of Fusion Plasmas

International Nuclear Information System (INIS)

Tang, X.Z.; Fu, G.Y.; Jardin, S.C.; Lowe, L.L.; Park, W.; Strauss, H.R.

2001-01-01

Although high-temperature plasmas in laboratory magnetic fusion confinements are sufficiently collisionless that formal fluid closures are difficult to attain, the resistive MHD model has proven, by comparison with experimental data, to be useful for describing the large scale dynamics of magnetized plasmas. Resistive MHD model consists of Faraday's law for the evolution of the magnetic field and Navier-Stokes equation for the plasma flow. These equations are closed by the Ohm's law and an equation of state for the plasma

Combined slurry and cavitation erosion resistance of surface modified SS410 stainless steel

Science.gov (United States)

Amarendra, H. J.; Pratap, M. S.; Karthik, S.; Punitha Kumara, M. S.; Rajath, H. C.; Ranjith, H.; Shubhatunga, S. V.

2018-03-01

Slurry erosion and combined slurry and cavitation erosion resistance of thermal spray coatings are studied and compared with the as-received martensitic stainless steel material. 70Ni-Cr coatings are deposited on SS 410 material through plasma thermal spray process. The synergy effect of the combined slurry and cavitation erosion resistance of plasma thermal spray coatings were investigated in a slurry pot tester in the presence of bluff bodies known as Cavitation Inducers. Results showed the combined slurry and cavitation erosion resistance of martensitic stainless steel - 410 can be improved by plasma thermal spray coating. It is observed that the plasma spray coated specimens are better erosion resistant than the as- received material, subjected to erosion test under similar conditions. As-received and the surface modified steels are mechanically characterized for its hardness, bending. Morphological studies are conducted through scanning electron microscope.

Rapid fabrication of large-area, corrosion-resistant superhydrophobic Mg alloy surfaces.

Science.gov (United States)

Xu, Wenji; Song, Jinlong; Sun, Jing; Lu, Yao; Yu, Ziyuan

2011-11-01

A superhydrophobic magnesium (Mg) alloy surface was successfully fabricated via a facile electrochemical machining process, and subsequently covered with a fluoroalkylsilane (FAS) film. The surface morphologies and chemical compositions were investigated using a scanning electron microscope (SEM) equipped with an energy-dispersive spectroscopy (EDS) and a Fourier-transform infrared spectrophotometer (FTIR). The results show hierarchal rough structures and an FAS film with a low surface energy on the Mg alloy surfaces, which confers good superhydrophobicity with a water contact angle of 165.2° and a water tilting angle of approximately 2°. The processing conditions, such as the processing time and removal rate per unit area at a constant removal mass per unit area, were investigated to determine their effects on the superhydrophobicity. Interestingly, when the removal mass per unit area is constant at approximately 11.10 mg/cm(2), the superhydrophobicity does not change with the removal rate per unit area. Therefore, a superhydrophobic Mg alloy surface can be rapidly fabricated based on this property. A large-area superhydrophobic Mg alloy surface was also fabricated for the first time using a small-area moving cathode. The corrosion resistance and durability of the superhydrophobic surfaces were also examined.

Summary of theoretical and experimental investigation of grating type, silicon photovoltaic cells. [using p-n junctions on light receiving surface of base crystal

Science.gov (United States)

Chen, L. Y.; Loferski, J. J.

1975-01-01

Theoretical and experimental aspects are summarized for single crystal, silicon photovoltaic devices made by forming a grating pattern of p/n junctions on the light receiving surface of the base crystal. Based on the general semiconductor equations, a mathematical description is presented for the photovoltaic properties of such grating-like structures in a two dimensional form. The resulting second order elliptical equation is solved by computer modeling to give solutions for various, reasonable, initial values of bulk resistivity, excess carrier concentration, and surface recombination velocity. The validity of the computer model is established by comparison with p/n devices produced by alloying an aluminum grating pattern into the surface of n-type silicon wafers. Current voltage characteristics and spectral response curves are presented for cells of this type constructed on wafers of different resistivities and orientations.

Using electrical resistance tomography to map subsurface temperatures

Science.gov (United States)

Ramirez, Abelardo L.; Chesnut, Dwayne A.; Daily, William D.

1994-01-01

A method is provided for measuring subsurface soil or rock temperatures remotely using electrical resistivity tomography (ERT). Electrical resistivity measurements are made using electrodes implanted in boreholes driven into the soil and/or at the ground surface. The measurements are repeated as some process changes the temperatures of the soil mass/rock mass. Tomographs of electrical resistivity are calculated based on the measurements using Poisson's equation. Changes in the soil/rock resistivity can be related to changes in soil/rock temperatures when: (1) the electrical conductivity of the fluid trapped in the soil's pore space is low, (2) the soil/rock has a high cation exchange capacity and (3) the temperature changes are sufficiently high. When these three conditions exist the resistivity changes observed in the ERT tomographs can be directly attributed to changes in soil/rock temperatures. This method provides a way of mapping temperature changes in subsurface soils remotely. Distances over which the ERT method can be used to monitor changes in soil temperature range from tens to hundreds of meters from the electrode locations.

Using electrical resistance tomography to map subsurface temperatures

Science.gov (United States)

Ramirez, A.L.; Chesnut, D.A.; Daily, W.D.

1994-09-13

A method is provided for measuring subsurface soil or rock temperatures remotely using electrical resistivity tomography (ERT). Electrical resistivity measurements are made using electrodes implanted in boreholes driven into the soil and/or at the ground surface. The measurements are repeated as some process changes the temperatures of the soil mass/rock mass. Tomographs of electrical resistivity are calculated based on the measurements using Poisson's equation. Changes in the soil/rock resistivity can be related to changes in soil/rock temperatures when: (1) the electrical conductivity of the fluid trapped in the soil's pore space is low, (2) the soil/rock has a high cation exchange capacity and (3) the temperature changes are sufficiently high. When these three conditions exist the resistivity changes observed in the ERT tomographs can be directly attributed to changes in soil/rock temperatures. This method provides a way of mapping temperature changes in subsurface soils remotely. Distances over which the ERT method can be used to monitor changes in soil temperature range from tens to hundreds of meters from the electrode locations. 1 fig.

The orthogonal gradients method: A radial basis functions method for solving partial differential equations on arbitrary surfaces

KAUST Repository

Piret, Cécile

2012-05-01

Much work has been done on reconstructing arbitrary surfaces using the radial basis function (RBF) method, but one can hardly find any work done on the use of RBFs to solve partial differential equations (PDEs) on arbitrary surfaces. In this paper, we investigate methods to solve PDEs on arbitrary stationary surfaces embedded in . R3 using the RBF method. We present three RBF-based methods that easily discretize surface differential operators. We take advantage of the meshfree character of RBFs, which give us a high accuracy and the flexibility to represent the most complex geometries in any dimension. Two out of the three methods, which we call the orthogonal gradients (OGr) methods are the result of our work and are hereby presented for the first time. © 2012 Elsevier Inc.

On the temperature dependence of the excess resistivity in dilute volatile alloys

International Nuclear Information System (INIS)

Uray, L.; Vicsek, T.

1978-01-01

In recrystallized wires of many important refractory alloys, an appreciable part of the temperature dependence of the measured excess resistivity is related to the radial distribution of the volatile solutes (extrinsic temperature dependence). Both the extrinsic and the intrinsic part of the temperature dependence of the excess resistivity have been determined for dilute WFe, WCo and WRe alloys, by measuring the resistance as a function of temperature and the thickness of layers removed by electrothinning. In this way the parameters of the evaporation profiles were also determined. In the surface region at low temperatures the length scale of the inhomogeneity is comparable to the mean-free path. Therefore, the observed extrinsic temperature dependence of the excess resistivity was calculated directly from the Boltzmann equation. The WCo alloy is a Kondo system, since its resistivity shows a minimum a 20 K. (author)

Improving the contact resistance at low force using gold coated carbon nanotube surfaces

Science.gov (United States)

McBride, J. W.; Yunus, E. M.; Spearing, S. M.

2010-04-01

Investigations to determine the electrical contact performance under repeated cycles at low force conditions for carbon-nanotube (CNT) coated surfaces were performed. The surfaces under investigation consisted of multi-walled CNT synthesized on a silicon substrate and coated with a gold film. These planar surfaces were mounted on the tip of a PZT actuator and contacted with a plated Au hemispherical probe. The dynamic applied force used was 1 mN. The contact resistance (Rc) of these surfaces was investigated with the applied force and with repeated loading cycles performed for stability testing. The surfaces were compared with a reference Au-Au contact under the same experimental conditions. This initial study shows the potential for the application of gold coated CNT surfaces as an interface in low force electrical contact applications.

Fractional Diffusion Equations and Anomalous Diffusion

Science.gov (United States)

Evangelista, Luiz Roberto; Kaminski Lenzi, Ervin

2018-01-01

Preface; 1. Mathematical preliminaries; 2. A survey of the fractional calculus; 3. From normal to anomalous diffusion; 4. Fractional diffusion equations: elementary applications; 5. Fractional diffusion equations: surface effects; 6. Fractional nonlinear diffusion equation; 7. Anomalous diffusion: anisotropic case; 8. Fractional Schrödinger equations; 9. Anomalous diffusion and impedance spectroscopy; 10. The Poisson–Nernst–Planck anomalous (PNPA) models; References; Index.

Failure of the Nernst-Einstein equation to correlate electrical resistances and rates of ionic self-exchange across certain fixed charge membranes.

Science.gov (United States)

Gottlieb, M H; Sollner, K

1968-05-01

The electrical resistances and rates of self-exchange of univalent critical ions across several types of collodion matrix membranes of high ionic selectivity were studied over a wide range of conditions. The relationship which was observed between these quantities with membranes of a certain type, namely those activated with poly-2-vinyl-N-methyl pyridinium bromide, cannot be explained on the basis of current concepts of the movement of ions across ion exchange membranes. Rates of self-exchange across these membranes were several times greater than those calculated from the electrical resistances of the membranes on the basis of an expression derived by the use of the Nernst-Einstein equation. The magnitude of the discrepancy was greatest at low concentrations of the ambient electrolyte solution and was independent of the species of both critical and noncritical ions. The data obtained with other types of collodion matrix membranes were, at least approximately, in agreement with the predictions based on the Nernst-Einstein equation. Self-exchange rates across the anion permeable protamine collodion membranes, and across the cation permeable polystyrene sulfonic acid collodion membranes, were about 20% less than those calculated from the electrical resistances. The direction and magnitude of these differences, also observed by other investigators, are qualitatively understood as an electroosmotic effect. With cation permeable membranes prepared by the oxidation of preformed collodion membranes, almost exact agreement was obtained between measured and calculated self-exchange rates; the cause of the apparent absence of an electroosmotic effect with these membranes is unknown.

Resistive internal kink modes in a tokamak with high-pressure plasma

International Nuclear Information System (INIS)

Kuvshinov, B.N.; Mikhajlovskij, A.B.; Tatarinov, E.G.

1988-01-01

Theory of resistive internal kink modes in a tokamak with high-pressure plasma is developed. Equation for Fourie-image of disturbed displacment in a resistive layer ie derived with regard to effects of the fourth order by plasma pressure within the framework of single-liquid approach. In its structure this equation coincides with a similar equation for resistive balloon modes and has an exact solution expressed by degenerated hypergeometric function. A general dispersion equation for resistive kink modes is derived with regard to the effects indicated. It is shown that plasma pressure finiteness leads to the reduction of reconnection and tyring-mode increments

Crack resistance of pvd coatings : Influence of surface treatment prior to deposition

NARCIS (Netherlands)

Zoestbergen, E; de Hosson, J.T.M.

The crack resistance of three different PVD coatings, TiN, Ti(C,N), and a multilayer system of alternating TiN and TiAlN, have been investigated. The three coating systems were deposited onto substrates with a different surface roughness to study the influence of this pretreatment on the crack

Preparation and characterization of soy protein films with a durable water resistance-adjustable and antimicrobial surface.

Science.gov (United States)

Li, Shuzhao; Donner, Elizabeth; Xiao, Huining; Thompson, Michael; Zhang, Yachuan; Rempel, Curtis; Liu, Qiang

2016-12-01

A water resistant surface was first obtained by immobilizing hydrophobic copolymers, poly (styrene-co-glycidyl methacrylate) (PSG), with functional groups on soy protein isolate (SPI) films. XPS and AFM results showed that PSG copolymers were immobilized on the film by chemical bonding, and formed a rough surface with some bumps because of the segregation of two different phases on PSG copolymers. Water resistance of the modified films could be adjusted dramatically by further immobilizing different amounts of guanidine-based antimicrobial polymers, poly (hexamethylene guanidine hydrochloride) (PHMG) on the resulting hydrophobic surface. The introduction of hydrophilic PHMG on the resulting surface generated many micropores, which potentially increased the water uptake of the modified films. Furthermore, the modified SPI films showed higher thermostability compared to native SPI film and broad-spectrum antimicrobial activity by contact killing, attributed to the presence of PHMG on the surface. The modified SPI film with a multi-functional surface showed potential for applications in the packaging and medical fields. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Enhancing wear resistance of working bodies of grinder through lining crushed material

Science.gov (United States)

Romanovich, A. A.; Annenko, D. M.; Romanovich, M. A.; Apukhtina, I. V.

2018-03-01

The article presents the analysis of directions of increasing wear resistance of working surfaces of rolls. A technical solution developed at the level of the invention is proposed, which is simple to implement in production conditions and which makes it possible to protect the roll surface from heavy wear due to surfacing of wear-resistant mesh material, cells of which are filling with grinding material in the process of work. Retaining them enables one to protect the roll surface from wear. The paper dwells on conditions of pressing materials in cells of eccentric rolls on the working surface with a grid of rectangular shape. The paper presents an equation for calculation of the cell dimension that provides the lining of the working surface by a mill material with respect to its properties. The article presents results of comparative studies on the grinding process of a press roller grinder (PRG) between rolls with and without a fusion-bonded mesh. It is clarified that the lining of rolls working surface slightly reduces the quality of the grinding, since the material thickness in the cell is small and has a finely divided and compacted structure with high strength.

Improvement of pitting corrosion resistance of AISI 304L stainless steel by nano-pulsed laser surface melting

International Nuclear Information System (INIS)

Pacquentin, W.; Blanc, C.; Caron, N.; Thro, P.Y.; Cheniere, A.; Tabarant, M.; Moutiers, G.; Miserque, F.; Plouzennec, H.; Oltra, R.

2013-01-01

The stainless steel 304L is widely used, however, in particular conditions, it may be sensitive to pitting corrosion. Nano-pulsed laser surface melting is a surface treatment which allows improving the corrosion resistance of this steel. This treatment consists in focusing a laser beam on the surface of the material, involving its quite immediately melting through a few microns depth, then an ultra-fast solidification occurs with cooling rate about 1011 K/s. The laser parameters control the modifications of the physico-chemical properties. In particular, we studied the influence of the impacts overlap of an ytterbium laser-fiber on the corrosion resistance of a 304L stainless steel in conditions of an aerated and agitated solution of NaCl (concentration of 30 g/L). We obtained an increase of the pitting potential of 220 mV, highlighting an improvement of the corrosion resistance. The study of the chemical and structural modifications is not enough to explain the improvement of the corrosion resistance. Other phenomena must be taken into account, as the quality of the oxide layer, in terms of physico-chemical and mechanical properties. (authors)

Assessment of slipping resistance of footwear and floor surfaces. Influence of manufacture and utilization of the products.

Science.gov (United States)

Leclercq, S; Tisserand, M; Saulnier, H

1995-02-01

The slipping resistance of footwear or floor surfaces is a characteristic which it is vital to be able to quantify. Work is being carried out at the International Standard Organization (ISO) and at the European Committee for Standardization (CEN) into the slip resistance of both work shoes and protective footwear, involving analysis of the latest developments in both the validity of measuring methods and the extent of the influence of certain experimental parameters on the slip resistance. Two industrial factors, independent of the measuring process but essential to the determination of the coefficient of friction of the models have been experimentally studied, namely the effect of the manufacture of the footwear or floor surfaces on the scattering of the specific coefficient of friction of a referenced model and the effect on the coefficient of friction of mechanical wear and tear on the soles as a result of their use respectively. Work into slipping on industrial floor surfaces is less advanced. Yet, problems raised call for the same approach than for problems linked to slipping resistance of footwear, and applications will be also at first related to standardized measurement conditions.

Effect of internal short fibers, steel reinforcement, and surface layer on impact and penetration resistance of concrete

Directory of Open Access Journals (Sweden)

Ali Abd_Elhakam Aliabdo

2013-09-01

Full Text Available This paper presents an experimental program to investigate the impact and penetration resistance of concrete. The research work is divided into two approaches. These approaches are effect of concrete constituents and effect of surface layer. Effect of concrete aggregate type, w/c ratio, fiber type, fiber shape, fiber volume fraction, and steel reinforcement is considered in the first approach. The second approach includes using fiber reinforced concrete and glass fiber reinforced polymer as surface layers. The evaluating tests include standard impact test according to ASTM D 1557 and suggested simulated penetration test to measure the impact and penetration resistance of concrete. The test results of plain and fibrous concrete from ASTM D 1557 method indicated that steel fiber with different configurations and using basalt have a great positive effect on impact resistance of concrete. Moreover, the simulated penetration test indicates that steel fibers are more effective than propylene fibers, type of coarse aggregate has negligible effect, and steel fiber volume fraction has a more significant influence than fiber shape for reinforced concrete test panels. Finally, as expectable, surface properties of tested concrete panels have a significant effect on impact and penetration resistance.

Facile and scalable preparation of highly wear-resistance superhydrophobic surface on wood substrates using silica nanoparticles modified by VTES

Energy Technology Data Exchange (ETDEWEB)

Jia, Shanshan; Liu, Ming [College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Wu, Yiqiang, E-mail: wuyq0506@126.com [College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Hunan Provincial Collaborative Innovation Center for High-efficiency Utilization of Wood and Bamboo Resources, Central South University of Forestry and Technology, Changsha 410004 (China); Luo, Sha [College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Qing, Yan, E-mail: qingyan0429@163.com [College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Hunan Provincial Collaborative Innovation Center for High-efficiency Utilization of Wood and Bamboo Resources, Central South University of Forestry and Technology, Changsha 410004 (China); Chen, Haibo [College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China)

2016-11-15

Graphical abstract: Highly wear-resistance superhydrophobic surface on wood substrates was fabricated using silica nanoparticles modified by VTES. Display Omitted - Highlights: • Superhydrophobic surface on wood substrates was efficiently fabricated using nanoparticles modified by VTES. • The superhydrophobic surface exhibited a CA of 154° and a SAclose to 0°. • The superhydrophobic surface showed a durable and robust wear-resistance performance. - Abstract: In this study, an efficient, facile method has been developed for fabricating superhydrophobic surfaces on wood substrates using silica nanoparticles modified by VTES. The as-prepared superhydrophobic wood surface had a water contact angle of 154° and water slide angle close to 0°. Simultaneously, this superhydrophobic wood showed highly durable and robust wear resistance when having undergone a long period of sandpaper abrasion or being scratched by a knife. Even under extreme conditions of boiling water, the superhydrophobicity of the as-prepared wood composite was preserved. Characterizations by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy showed that a typical and tough hierarchical micro/nanostructure was created on the wood substrate and vinyltriethoxysilane contributed to preventing the agglomeration of silica nanoparticles and serving as low-surface-free-energy substances. This superhydrophobic wood was easy to fabricate, mechanically resistant and exhibited long-term stability. Therefore, it is considered to be of significant importance in the industrial production of functional wood, especially for outdoor applications.

Effect of surface modification on the corrosion resistivity in supercritical water

International Nuclear Information System (INIS)

Penttila, S.; Horvath, A.; Toivonen, A.; Zolnai, Z.

2011-01-01

This paper summarizes the results of high temperature corrosion studies of the candidate austenitic alloys at relevant operating conditions for SCWR. The high temperature and pressure above the thermodynamic critical point of water result in higher oxidation rate which might be critical for thin-wall components like fuel cladding. The goal of this work was to study the effect of surface preparation on the oxidation rate on Ti-stabilized austenitic alloy 1.4970. Surfaces were prepared with ion implantation using He"+- and N"+-ions. Samples were immersed in supercritical water at 650"oC/25 MPa, for up to 2000 hours. Added to this, conventional surface treatments were conducted for austenitic alloy 316L tube samples in order to study the effect of cold work in sample surface on corrosion resistance. The corrosion rate was evaluated by measuring the weight change of the samples. The compositions of the oxide layers were analyzed using scanning electron microscope (SEM) in conjunction with Energy Dispersive Spectroscopy (EDS). (author)

Generalized reduced magnetohydrodynamic equations

International Nuclear Information System (INIS)

Kruger, S.E.

1999-01-01

A new derivation of reduced magnetohydrodynamic (MHD) equations is presented. A multiple-time-scale expansion is employed. It has the advantage of clearly separating the three time scales of the problem associated with (1) MHD equilibrium, (2) fluctuations whose wave vector is aligned perpendicular to the magnetic field, and (3) those aligned parallel to the magnetic field. The derivation is carried out without relying on a large aspect ratio assumption; therefore this model can be applied to any general configuration. By accounting for the MHD equilibrium and constraints to eliminate the fast perpendicular waves, equations are derived to evolve scalar potential quantities on a time scale associated with the parallel wave vector (shear-Alfven wave time scale), which is the time scale of interest for MHD instability studies. Careful attention is given in the derivation to satisfy energy conservation and to have manifestly divergence-free magnetic fields to all orders in the expansion parameter. Additionally, neoclassical closures and equilibrium shear flow effects are easily accounted for in this model. Equations for the inner resistive layer are derived which reproduce the linear ideal and resistive stability criterion of Glasser, Greene, and Johnson. The equations have been programmed into a spectral initial value code and run with shear flow that is consistent with the equilibrium input into the code. Linear results of tearing modes with shear flow are presented which differentiate the effects of shear flow gradients in the layer with the effects of the shear flow decoupling multiple harmonics

Improving the corrosion resistance of proton exchange membrane fuel cell carbon supports by pentafluorophenyl surface functionalization

Science.gov (United States)

Forouzandeh, Farisa; Li, Xiaoan; Banham, Dustin W.; Feng, Fangxia; Joseph Kakanat, Abraham; Ye, Siyu; Birss, Viola

2018-02-01

In this study, the effect of surface functionalization on the electrochemical corrosion resistance of a high surface area, mesoporous colloid imprinted carbon powder (CIC), as well as microporous Vulcan carbon (VC, serving as the benchmark), was demonstrated, primarily for PEM fuel cell applications. CIC-22, which is highly hydrophilic and was synthesized with 22 nm silica colloid templates, and as-received, mildly hydrophobic, VC powders, were functionalized with 2,3,4,5,6-pentafluorophenyl (-PhF5) surface groups using a straightforward diazonium reduction reaction. These carbons were then subjected to corrosion testing, involving a potential cycling-step sequence in room temperature 0.5 M H2SO4. Using cyclic voltammetry and charge/time analysis, the double layer and pseudo-capacitive gravimetric charges of the carbons, prior to and after the application of these potential steps, were tracked in order to obtain information about surface area changes and the extent of carbon oxidation, respectively. It is shown that the corrosion resistance was improved by ca. 50-80% by surface functionalization, likely due to a combination of surface passivation (loss of carbon active sites) and increased surface hydrophobicity.

Soliton solutions to the fifth-order Korteweg-de Vries equation and their applications to surface and internal water waves

Science.gov (United States)

Khusnutdinova, K. R.; Stepanyants, Y. A.; Tranter, M. R.

2018-02-01

We study solitary wave solutions of the fifth-order Korteweg-de Vries equation which contains, besides the traditional quadratic nonlinearity and third-order dispersion, additional terms including cubic nonlinearity and fifth order linear dispersion, as well as two nonlinear dispersive terms. An exact solitary wave solution to this equation is derived, and the dependence of its amplitude, width, and speed on the parameters of the governing equation is studied. It is shown that the derived solution can represent either an embedded or regular soliton depending on the equation parameters. The nonlinear dispersive terms can drastically influence the existence of solitary waves, their nature (regular or embedded), profile, polarity, and stability with respect to small perturbations. We show, in particular, that in some cases embedded solitons can be stable even with respect to interactions with regular solitons. The results obtained are applicable to surface and internal waves in fluids, as well as to waves in other media (plasma, solid waveguides, elastic media with microstructure, etc.).

Surface effects of electrode-dependent switching behavior of resistive random-access memory

KAUST Repository

Ke, Jr Jian

2016-09-26

The surface effects of ZnO-based resistive random-access memory (ReRAM) were investigated using various electrodes. Pt electrodes were found to have better performance in terms of the device\\'s switching functionality. A thermodynamic model of the oxygen chemisorption process was proposed to explain this electrode-dependent switching behavior. The temperature-dependent switching voltage demonstrates that the ReRAM devices fabricated with Pt electrodes have a lower activation energy for the chemisorption process, resulting in a better resistive switching performance. These findings provide an in-depth understanding of electrode-dependent switching behaviors and can serve as design guidelines for future ReRAM devices.

Biofilm Formation of Staphylococcus aureus on Various Surfaces and Their Resistance to Chlorine Sanitizer.

Science.gov (United States)

Lee, Jung-Su; Bae, Young-Min; Lee, Sook-Young; Lee, Sun-Young

2015-10-01

This study investigated the effect of material types (polystyrene, polypropylene, glass, and stainless steel) and glucose addition on Staphylococcus aureus biofilm formation, and the relationship between biofilm formation measured by crystal violet (CV) staining and the number of biofilm cells determined by cell counts was studied. We also evaluated the efficacy of chlorine sanitizer on inhibiting various different types of S. aureus biofilms on the surface of stainless steel. Levels of biofilm formation of S. aureus were higher on hydrophilic surfaces (glass and stainless steel) than on hydrophobic surfaces (polypropylene and polystyrene). With the exception of biofilm formed on glass, the addition of glucose in broth significantly increased the biofilm formation of S. aureus on all surfaces and for all tested strains (P ≤ 0.05). The number of biofilm cells was not correlated with the biomass of the biofilms determined using the CV staining method. The efficacy of chlorine sanitizer against biofilm of S. aureus was not significantly different depending on types of biofilm (P > 0.05). Therefore, further studies are needed in order to determine an accurate method quantifying levels of bacterial biofilm and to evaluate the resistance of bacterial biofilm on the material surface. Biofilm formation of Staphylococcus aureus on the surface was different depending on the surface characteristics and S. aureus strains. There was low correlation between crystal violet staining method and viable counts technique for measuring levels of biofilm formation of S. aureus on the surfaces. These results could provide helpful information for finding and understanding the quantification method and resistance of bacterial biofilm on the surface. © 2015 Institute of Food Technologists®

Effect of surface treatment on the interfacial contact resistance and corrosion resistance of Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells

International Nuclear Information System (INIS)

Yang, Meijun; Zhang, Dongming

2014-01-01

The bipolar plate is an important component of the PEMFC (polymer electrolyte membrane fuel cell) because it supplies the pathway of electron flow between each unit cell. Fe–Ni–Cr alloy is considered as a good candidate material for bipolar plate, but it is limited to use as a bipolar plate due to its high ICR (interfacial contact resistance) and corrosion problem. In order to explore a cost-effective method on surface modification, various chemical and electrochemical treatments are performed on Fe–Ni–Cr alloy to acquire the effect of the surface modification on the ICR and corrosion behavior. The ICR and corrosion resistance of Fe–Ni–Cr alloy can be effectively controlled by the chemical treatment of immersion in the mixed acid solution with 10 vol% HNO 3 , 2 vol% HCl and 1 vol% HF for 10 min at 65 °C and then was placed in 30 vol% HNO 3 solution for 5 min. The chemical treatment is more effective on reducing ICR and improving corrosion resistance than that of electrochemical methods (be carried out in the 2 mol/L H 2 SO 4 solution with the electrical potential from −0.4 V to 0.6 V) for Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells. - Highlights: • The procedure of the surface treatments on Fe–Ni–Cr alloy as bipolar plate was described in detail. • Effects of various surface treatments on the interfacial contact resistivity and corrosion behavior were discussed. • The mechanism of the surface modification was particularly analyzed

Fracture resistance of dental nickel–titanium rotary instruments with novel surface treatment: Thin film metallic glass coating

Directory of Open Access Journals (Sweden)

Chih-Wen Chi

2017-05-01

Conclusion: The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure.

Extreme Wetting-Resistant Multiscale Nano-/Microstructured Surfaces for Viscoelastic Liquid Repellence

Directory of Open Access Journals (Sweden)

Aoythip Chunglok

2016-01-01

Full Text Available We demonstrate exceptional wetting-resistant surfaces capable of repelling low surface tension, non-Newtonian, and highly viscoelastic liquids. Theoretical analysis and experimental result confirm that a higher level of multiscale roughness topography composed of at least three structural length scales, ranging from nanometer to supermicron sizes, is crucial for the reduction of liquid-solid adhesion hysteresis. With Cassie-Baxter nonwetting state satisfied at all roughness length scales, the surface has been proven to effectively repel even highly adhesive liquid. Practically, this high-level hierarchical structure can be achieved through fractal-like structures of silica aggregates induced by siloxane oligomer interparticle bridges. The induced aggregation and surface functionalization of the silica particles can be performed simultaneously within a single reaction step, by utilizing trifunctional fluoroalkylsilane precursors that largely form a disordered fluoroalkylsiloxane grafting layer under the presence of sufficient native moisture preadsorbed at the silica surface. Spray-coating deposition of a particle surface layer on a precoated primer layer ensures facile processability and scalability of the fabrication method. The resulting low-surface-energy multiscale roughness exhibits outstanding liquid repellent properties, generating equivalent lotus effect for highly viscous and adhesive natural latex concentrate, with apparent contact angles greater than 160°, and very small roll-off angles of less than 3°.

Nanosecond laser surface modification of AISI 304L stainless steel: Influence the beam overlap on pitting corrosion resistance

International Nuclear Information System (INIS)

Pacquentin, Wilfried; Caron, Nadège; Oltra, Roland

2014-01-01

Surface modifications of AISI 304L stainless steel by laser surface melting (LSM) were investigated using a nanosecond pulsed laser-fibre doped by ytterbium at different overlaps. The objective was to study the change in the corrosion properties induced by the treatment of the outer-surface of the stainless steel without modification of the bulk material. Different analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and glow discharge optical emission spectrometry (GDOES) were used to characterize the laser-melted surface. The corrosion resistance was evaluated in a chloride solution at room temperature by electrochemical tests. The results showed that the crystallographic structure, the chemical composition, the properties of the induced oxide layer and consequently the pitting corrosion resistance strongly depend on the overlap rate. The most efficient laser parameters led to an increase of the pitting potential by more than 300 mV, corresponding to a quite important improvement of the corrosion resistance. This latter was correlated to chromium enrichment (47 wt.%) at the surface of the stainless steel and the induced absence of martensite and ferrite phases. However, these structural and chemical modifications were not sufficient to explain the change in corrosion behaviour: defects and adhesion of the surface oxide layer must have been taken into consideration.

Influence of the post-weld surface treatment on the corrosion resistance of the duplex stainless steel 1.4062

Science.gov (United States)

Rosemann, P.; Müller, C.; Baumann, O.; Modersohn, W.; Halle, T.

2017-03-01

The duplex stainless steel 1.4062 (X2CrNiN22-2) is used as alternative material to austenitic stainless steels in the construction industry. The corrosion resistance of welded seams is influenced by the base material, the weld filler material, the welding process and also by the final surface treatment. The scale layer next to the weld seam can be removed by grinding, pickling, electro-polished or blasting depending on the application and the requested corrosion resistance. Blasted surfaces are often used in industrial practice due to the easier and cheaper manufacturing process compared to pickled or electro-polished surfaces. Furthermore blasting with corundum-grain is more effective than blasting with glass-beads which also lower the process costs. In recent years, stainless steel surfaces showed an unusually high susceptibility to pitting corrosion after grinding with corundum. For this reason, it is now also questioned critically whether the corrosion resistance is influenced by the applied blasting agent. This question was specifically investigated by comparing grinded, pickled, corundum-grain- and glass-bead-blasted welding seams. Results of the SEM analyses of the blasting agents and the blasted surfaces will be presented and correlated with the different performed corrosion tests (potential measurement, KorroPad-test and pitting potential) on welding seams with different surface treatments.

Laser Tailoring the Surface Chemistry and Morphology for Wear, Scale and Corrosion Resistant Superhydrophobic Coatings.

Science.gov (United States)

Boinovich, Ludmila B; Emelyanenko, Kirill A; Domantovsky, Alexander G; Emelyanenko, Alexandre M

2018-06-04

A strategy, combining laser chemical modification with laser texturing, followed by chemisorption of the fluorinated hydrophobic agent was used to fabricate the series of superhydrophobic coatings on an aluminum alloy with varied chemical compositions and parameters of texture. It was shown that high content of aluminum oxynitride and aluminum oxide formed in the surface layer upon laser treatment allows solving the problem of enhancement of superhydrophobic coating resistance to abrasive loads. Besides, the multimodal structure of highly porous surface layer leads to self-healing ability of fabricated coatings. Long-term behavior of designed coatings in "hard" hot water with an essential content of calcium carbonate demonstrated high antiscaling resistance with self-cleaning potential against solid deposits onto the superhydrophobic surfaces. Study of corrosion protection properties and the behavior of coatings at long-term contact with 0.5 M NaCl solution indicated extremely high chemical stability and remarkable anticorrosion properties.

Rough surface electrical contact resistance considering scale dependent properties and quantum effects

International Nuclear Information System (INIS)

Jackson, Robert L.; Crandall, Erika R.; Bozack, Michael J.

2015-01-01

The objective of this work is to evaluate the effect of scale dependent mechanical and electrical properties on electrical contact resistance (ECR) between rough surfaces. This work attempts to build on existing ECR models that neglect potentially important quantum- and size-dependent contact and electrical conduction mechanisms present due to the asperity sizes on typical surfaces. The electrical conductance at small scales can quantize or show a stepping trend as the contact area is varied in the range of the free electron Fermi wavelength squared. This work then evaluates if these effects remain important for the interface between rough surfaces, which may include many small scale contacts of varying sizes. The results suggest that these effects may be significant in some cases, while insignificant for others. It depends on the load and the multiscale structure of the surface roughness

The Kapitza thermal boundary resistance between two solids

International Nuclear Information System (INIS)

Andersen, A.C.

1981-01-01

In this article, the author develops a model of the Kapitza resistance between two solids in which this resistance is seen to be related to the refraction of thermal phonons at the interface, which is a function of the accoustic properties of the two solids. By calculating a kapitza boundary resistance for the two solids in an ideal case (with ideal temperature, ideal interface, and phonon scattering produced only by the interface) and then producing a summation of the three phonon modes, the angles of incidence, and the phonon frequencies, the author produces an equation which expresses the resistance; this equation is known as the accoustic-mis-match model. By then removing the conditions of ideality and adjusting the equation accordingly, the author finds that the acoustic mismatch model is successful in describing the resistance behavior

Effects of laser polishing on surface microstructure and corrosion resistance of additive manufactured CoCr alloys

Science.gov (United States)

Wang, W. J.; Yung, K. C.; Choy, H. S.; Xiao, T. Y.; Cai, Z. X.

2018-06-01

Laser polishing of 3D printed metal components has drawn great interest in view of its potential applications in the dental implant industries. In this study, corrosion resistance, surface composition and crystalline structure of CoCr alloys were investigated. The corrosion resistance, micromorphology, composition, phase transformations and crystalline structures of samples were characterized using an electrochemical analyzer, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. The results indicate that high laser powers and low object distances within a certain range can facilitate the formation of complex oxide films, which exhibits high corrosion resistance. Further, object distances have a significant influence on cooling rates during the solidification of the melt pool in laser polishing, and fast cooling generates vast amounts of vacancies and defects, which result in the crystalline phase transformation from γ to ε. Consequently, the formed oxides play an important role in corrosion resistance on the outer layer, and inner layer with γ phase also helps keep the CoCr alloys in a stable structure with high resistant to corrosion. The two process parameters in laser polishing, laser power and object distances, are demonstrated as being important for controlling the surface microstructures and corrosion resistance of the additive manufactured CoCr alloy components.

Determination of Flow Resistance Coefficient for Vegetation in Open Channel: Laboratory study

Science.gov (United States)

Aliza Ahmad, Noor; Ali, ZarinaMd; Arish, Nur Aini Mohd; Munirah Mat Daud, Azra; Fatin Amirah Alias, Nur

2018-04-01

This study focused on determination of flow resistances coefficient for grass in an open channel. Laboratory works were conducted to examine the effects of varying of roughness elements on the flume to determine flow resistance coefficient and also to determine the optimum flow resistance with five different flow rate, Q. Laboratory study with two type of vegetation which are Cow Grass and Pearl Grass were implementing to the bed of a flume. The roughness coefficient, n value is determine using Manning’s equation while Soil Conservation Services (SCS) method was used to determine the surface resistance. From the experiment, the flow resistance coefficient for Cow Grass in range 0.0008 - 0.0039 while Pearl Grass value for the flow resistance coefficient are in between 0.0013 - 0.0054. As a conclusion the vegetation roughness value in open channel are depends on density, distribution type of vegetation used and physical characteristic of the vegetation itself

Magnetic field integral equation analysis of surface plasmon scattering by rectangular dielectric channel discontinuities.

Science.gov (United States)

Chremmos, Ioannis

2010-01-01

The scattering of a surface plasmon polariton (SPP) by a rectangular dielectric channel discontinuity is analyzed through a rigorous magnetic field integral equation method. The scattering phenomenon is formulated by means of the magnetic-type scalar integral equation, which is subsequently treated through an entire-domain Galerkin method of moments (MoM), based on a Fourier-series plane wave expansion of the magnetic field inside the discontinuity. The use of Green's function Fourier transform allows all integrations over the area and along the boundary of the discontinuity to be performed analytically, resulting in a MoM matrix with entries that are expressed as spectral integrals of closed-form expressions. Complex analysis techniques, such as Cauchy's residue theorem and the saddle-point method, are applied to obtain the amplitudes of the transmitted and reflected SPP modes and the radiated field pattern. Through numerical results, we examine the wavelength selectivity of transmission and reflection against the channel dimensions as well as the sensitivity to changes in the refractive index of the discontinuity, which is useful for sensing applications.

Hyper-resistivity and electron thermal conductivity due to destroyed magnetic surfaces in axisymmetric plasma equilibria

Energy Technology Data Exchange (ETDEWEB)

Weening, R. H. [Department of Radiologic Sciences, Thomas Jefferson University, 901 Walnut Street, Philadelphia, Pennsylvania 19107-5233 (United States)

2012-06-15

In order to model the effects of small-scale current-driven magnetic fluctuations in a mean-field theoretical description of a large-scale plasma magnetic field B(x,t), a space and time dependent hyper-resistivity {Lambda}(x,t) can be incorporated into the Ohm's law for the parallel electric field E Dot-Operator B. Using Boozer coordinates, a theoretical method is presented that allows for a determination of the hyper-resistivity {Lambda}({psi}) functional dependence on the toroidal magnetic flux {psi} for arbitrary experimental steady-state Grad-Shafranov axisymmetric plasma equilibria, if values are given for the parallel plasma resistivity {eta}({psi}) and the local distribution of any auxiliary plasma current. Heat transport in regions of plasma magnetic surfaces destroyed by resistive tearing modes can then be modeled by an electron thermal conductivity k{sub e}({psi})=({epsilon}{sub 0}{sup 2}m{sub e}/e{sup 2}){Lambda}({psi}), where e and m{sub e} are the electron charge and mass, respectively, while {epsilon}{sub 0} is the permittivity of free space. An important result obtained for axisymmetric plasma equilibria is that the {psi}{psi}-component of the metric tensor of Boozer coordinates is given by the relation g{sup {psi}{psi}}({psi}){identical_to}{nabla}{psi} Dot-Operator {nabla}{psi}=[{mu}{sub 0}G({psi})][{mu}{sub 0}I({psi})]/{iota}({psi}), with {mu}{sub 0} the permeability of free space, G({psi}) the poloidal current outside a magnetic surface, I({psi}) the toroidal current inside a magnetic surface, and {iota}({psi}) the rotational transform.

The effect of electron-surface scattering and thiol adsorption on the electrical resistivity of gold ultrathin films

International Nuclear Information System (INIS)

Henriquez, Ricardo; Del Campo, Valeria; Gonzalez-Fuentes, Claudio; Correa-Puerta, Jonathan; Moraga, Luis; Flores, Marcos; Segura, Rodrigo; Donoso, Sebastián; Marín, Francisca; Bravo, Sergio; Häberle, Patricio

2017-01-01

Highlights: • We prepared ultra thin films (10 nm) on mica on top of a chromium seedlayer (<1 nm). • We prepared samples with different topographies controlling the substrate temperature. • We studied the contribution of the different scattering mechanims on the resistivity. • We developed a discernment method based on thiol adsorption. - Abstract: In order to study the effect of electron-surface scattering in gold ultrathin films (∼10 nm), we have prepared a set of Au samples on mica on top of a chromium seedlayer (<1 nm). Chromium is added as a metallic surfactant which enables surpassing the electric percolation threshold for substrate temperatures above room temperature. We prepared samples with the same thickness but different topographies setting different substrate temperatures. These modifications modulate the contributions of the different electronic scattering mechanisms to the film resistivity. A second set of gold thin films deposited on mica at room temperature, with different thicknesses between 8 and 100 nm, was also prepared to compare the resisitivities of both sets through Mayadas and Shatzkes theory. We found that in samples with thicknesses below 15 nm, the electron-surface scattering is indeed the dominant mechanism influencing the film resistivity. To obtain further evidence of this prevalence, we developed a discrimination method based on thiol adsorption. The film with the highest resistivity increase is the sample in which electron-surface scattering is dominant. With this method, we observed that a large enhancement of the electron-surface scattering not only occurs in samples with large diameters grains, but also if the film has a reduced surface roughness.​

The effect of electron-surface scattering and thiol adsorption on the electrical resistivity of gold ultrathin films

Energy Technology Data Exchange (ETDEWEB)

Henriquez, Ricardo, E-mail: ricardo.henriquez@usm.cl [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile); Del Campo, Valeria; Gonzalez-Fuentes, Claudio [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile); Correa-Puerta, Jonathan [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Av. Universidad 330, Curauma, Valparaíso (Chile); Moraga, Luis [Universidad Central de Chile, Toesca 1783, Santiago 8370178 (Chile); Flores, Marcos [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Segura, Rodrigo [Instituto de Química y Bioquímica, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso (Chile); Donoso, Sebastián; Marín, Francisca; Bravo, Sergio; Häberle, Patricio [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile)

2017-06-15

Highlights: • We prepared ultra thin films (10 nm) on mica on top of a chromium seedlayer (<1 nm). • We prepared samples with different topographies controlling the substrate temperature. • We studied the contribution of the different scattering mechanims on the resistivity. • We developed a discernment method based on thiol adsorption. - Abstract: In order to study the effect of electron-surface scattering in gold ultrathin films (∼10 nm), we have prepared a set of Au samples on mica on top of a chromium seedlayer (<1 nm). Chromium is added as a metallic surfactant which enables surpassing the electric percolation threshold for substrate temperatures above room temperature. We prepared samples with the same thickness but different topographies setting different substrate temperatures. These modifications modulate the contributions of the different electronic scattering mechanisms to the film resistivity. A second set of gold thin films deposited on mica at room temperature, with different thicknesses between 8 and 100 nm, was also prepared to compare the resisitivities of both sets through Mayadas and Shatzkes theory. We found that in samples with thicknesses below 15 nm, the electron-surface scattering is indeed the dominant mechanism influencing the film resistivity. To obtain further evidence of this prevalence, we developed a discrimination method based on thiol adsorption. The film with the highest resistivity increase is the sample in which electron-surface scattering is dominant. With this method, we observed that a large enhancement of the electron-surface scattering not only occurs in samples with large diameters grains, but also if the film has a reduced surface roughness.​.

Bacteria-Mineral Interactions on the Surfaces of Metal-Resistant Bacteria

International Nuclear Information System (INIS)

Malkin, A.J.

2010-01-01

The extraordinary ability of indigenous microorganisms, like metal-resistant bacteria, for biotransformation of toxic compounds is of considerable interest for the emerging area of environmental bioremediation. However, the underlying mechanisms by which metal-resistant bacteria transform toxic compounds are currently unknown and await elucidation. The project's objective was to study stress-induced responses of metal-resistant bacteria to environmental changes and chemical stimulants. This project involved a multi-institutional collaboration of our LLNL group with the group of Dr. H.-Y. Holman (Lawrence Berkeley National Laboratory). In this project, we have utilized metal-resistant bacteria Arthrobacter oxydans as a model bacterial system. We have utilized atomic force microscopy (AFM) to visualize for the first time at the nanometer scale formation of stress-induced structures on bacterial surfaces in response to Cr (VI) exposure. We have demonstrated that structure, assembly, and composition of these stress-induced structures are dependent on Cr (VI) concentrations. Our AFM observations of the appearance and development of stress-induced layers on the surfaces of Arthrobacter oxydans bacteria exposed to Cr (VI) were confirmed by Dr. Holman's biochemical, electron microscopy, and synchrotron infrared spectromicroscopy studies. In general, in vitro imaging of live microbial and cellular systems represents one of the most challenging issues in application of AFM. Various approaches for immobilization of bacteria on the substrate for in vitro imaging were tested in this project. Imaging of live bacteria was achieved, however further optimization of experimental methods are needed for high-resolution visualization of the cellular environmental structural dynamics by AFM. This project enhanced the current insight into molecular architecture, structural and environmental variability of bacterial systems. The project partially funded research for two book chapters (1

Coupled wave equations theory of surface-enhanced femtosecond stimulated Raman scattering.

Science.gov (United States)

McAnally, Michael O; McMahon, Jeffrey M; Van Duyne, Richard P; Schatz, George C

2016-09-07

We present a coupled wave semiclassical theory to describe plasmonic enhancement effects in surface-enhanced femtosecond stimulated Raman scattering (SE-FSRS). A key result is that the plasmon enhanced fields which drive the vibrational equation of motion for each normal mode results in dispersive lineshapes in the SE-FSRS spectrum. This result, which reproduces experimental lineshapes, demonstrates that plasmon-enhanced stimulated Raman methods provide unique sensitivity to a plasmonic response. Our derived SE-FSRS theory shows a plasmonic enhancement of |gpu|(2)ImχR(ω)gst (2)/ImχR(ω), where |gpu|(2) is the absolute square of the plasmonic enhancement from the Raman pump, χR(ω) is the Raman susceptibility, and gst is the plasmonic enhancement of the Stokes field in SE-FSRS. We conclude with a discussion on potential future experimental and theoretical directions for the field of plasmonically enhanced coherent Raman scattering.

Beyond Cassie equation: Local structure of heterogeneous surfaces determines the contact angles of microdroplets

Science.gov (United States)

Zhang, Bo; Wang, Jianjun; Liu, Zhiping; Zhang, Xianren

2014-01-01

The application of Cassie equation to microscopic droplets is recently under intense debate because the microdroplet dimension is often of the same order of magnitude as the characteristic size of substrate heterogeneities, and the mechanism to describe the contact angle of microdroplets is not clear. By representing real surfaces statistically as an ensemble of patterned surfaces with randomly or regularly distributed heterogeneities (patches), lattice Boltzmann simulations here show that the contact angle of microdroplets has a wide distribution, either continuous or discrete, depending on the patch size. The origin of multiple contact angles observed is ascribed to the contact line pinning effect induced by substrate heterogeneities. We demonstrate that the local feature of substrate structure near the contact line determines the range of contact angles that can be stabilized, while the certain contact angle observed is closely related to the contact line width. PMID:25059292

Measurements of the anomalous RF surface resistance of niobium using a dielectric resonator

International Nuclear Information System (INIS)

Moffat, D.; Bolore, M.; Bonin, B.; Jacques, E.; Safa, H.

1996-01-01

The surface resistance of high and low RRR niobium plates at 4.2 K and 1.8 K has been measured as a function of many processing and testing parameters. A dielectric resonator was used instead of a resonant cavity. This resonator offered the ability to make many, sensitive measurements with an efficient use of time and helium. It was found that the surface resistance, R s , of RRR=190 niobium increased noticeably from the theoretical value if the cooling rate was slower than∼10 K/min. Fast-cooled plates subsequently warmed to 130 K, and the recooled, showed a larger increase in R s than plates warmed to either 100 K or 160 K. Both chemically polished, and electropolished RRR=190 plates showed the effects of the 'Q-virus'. A heat treatment of 200 deg C made the RRR=190 plates less susceptible to the 'Q-virus'. RRR=30 niobium plates did not show any increase in R s , regardless of treatment. (author)

A resistance representation of schemes for evaporation from bare and partly plant-covered surfaces for use in atmospheric models

Energy Technology Data Exchange (ETDEWEB)

Mihailovic, D.T.; Pielke, R.A.; Rajkovic, B.; Lee, T.J.; Jeftic, M. (Novi Sad Univ. (Yugoslavia) Colorado State Univ., Fort Collins (United States) Belgrade Univ. (Yugoslavia))

1993-06-01

In the parameterization of land surface processes, attention must be devoted to surface evaporation, one of the main processes in the air-land energy exchange. One of the most used approaches is the resistance representation which requires the calculation of aerodynamic resistances. These resistances are calculated using K theory for different morphologies of plant communities; then, the performance of the evaporation schemes within the alpha, beta, and their combination approaches that parameterize evaporation from bare and partly plant-covered soil surfaces are discussed. Additionally, a new alpha scheme is proposed based on an assumed power dependence alpha on volumetric soil moisture content and its saturated value. Finally, the performance of the considered and the proposed schemes is tested based on time integrations using real data. The first set was for 4 June 1982, and the second for 3 June 1981 at the experimental site in Rimski Sancevi, Yugoslavia, on chernozem soil, as representative for a bare, and partly plant-covered surface, respectively. 63 refs.

Inductive Eigenmodes of a resistive toroidal surface in vacuum

Energy Technology Data Exchange (ETDEWEB)

Lo Surdo, C. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dipt. Innovazione

1999-07-01

In this paper it has been studied the Electro-Magnetic (EM) Eigenmodes, sufficiently slow as to legitimate the pre-Maxwell approximation of Maxwell's system (or inductive Eigenmodes), of a given smooth, toroidal-un knotted, electrically resistive surface {tau} with given smooth (surface) resistivity 0 < {rho}{sub d}egree < {infinity}, and lying in the (empty) R{sup 3}. Within the above limitations (to be made more precise), the geometry of {tau} is arbitrary. With the eigenvalue associated with the generic Eigenmode being defined as the opposite of its logarithmic time-derivative, one expects that the resulting spectrum be discrete and strictly positive. It shall be interested into the degenerate case where {tau} be cut (i.e. electrically broken) along one or more of its irreducible cycles. This case will be analyzed autonomously, rather than as a limit (for {rho}{sub d}egree {yields} {infinity} along the cuts) of the regular case. Without cuts, the Eigenproblem under consideration is nothing but the two-dimensional (2-dim) generalization of the classical case of a smooth, unknotted, electrically conductive, simple coil in infinite vacuum. Its analysis hinges on the classical potential theory, and turns out to be a special application of the linear, integrodifferential (elliptic) equation theory on a compact, multiply connected, 2-dim manifold. The attention and approach will be confined to strong (or classical) solutions, both in {tau} and C {tau} = R{sup 3} / {tau}. This study is divided in two parts: a General Part (Sects 1 divided 4) is devoted to the case of generic {tau} and {rho}{sub d}egree (within the convenient smoothness requirements), whereas a Special Part (Sects 5 divided 7) deals with the (more or less formal) discussion of a couple of particular cases ({tau} {identical_to} a canonical torus), both of which with uniform {rho}{sub d}egree. Some propaedeutical/supplementary information is provided in a number of Appendices. [Italian] Il presente

A novel method to prepare superhydrophobic, UV resistance and anti-corrosion steel surface

KAUST Repository

Isimjan, Tayirjan T.

2012-11-01

Both TiO 2 and SiO 2 coated steel surfaces containing micro- and nanoscale binary structures with different surface roughness were successfully fabricated by means of a facile layer by layer deposition process followed by heat treatment. The resulting surfaces were modified by the low free energy chemical PTES (1H,1H,2H,2H-Perfluorodecyltriethoxysilane). The experimental results of wettability exhibit that such modified surfaces have a strong repulsive force to water droplets, their static contact angles exceed 165°, receding angle>160°, advanced angles>170° and slide angle<1°. The resulting surfaces not only exhibit superhydrophobic properties but also show strong UV resistance (after coating SiO 2 on top of TiO 2) and strong stability to various solvents including 0.01% HCl solution. © 2012 Elsevier B.V.

An improved nucleate boiling design equation

International Nuclear Information System (INIS)

Basu, D.K.; Pinder, K.L.

1976-01-01

The effect of varying ΔT, the primary variable, on the value of heat transfer coefficient (h) in nucleate boiling is discussed. The three-parameter quadratic equation, h=P 1 + P 2 (ΔT) + P 3 (ΔT) 2 (where the constants, P 1 ,P 2 ,P 3 are functions of pressure, liquid properties and surface properties of the heater) is suggested. Ten sets of data at atmospheric pressure from six different workers and two more sets for pressure variation have been tested. The above quadratic equation fits the experimental data better than the existing two-parameter power relation, h=C(ΔT)sup(n) (where C is constant). The values of the three coeffcients in the quadratic equations are dependent on pressure, liquid properties and surface properties. A generalized empirical equation has been derived, which fits the selected pressure data well. (author)

Analysis of discrete reaction-diffusion equations for autocatalysis and continuum diffusion equations for transport

Energy Technology Data Exchange (ETDEWEB)

Wang, Chi-Jen [Iowa State Univ., Ames, IA (United States)

2013-01-01

In this thesis, we analyze both the spatiotemporal behavior of: (A) non-linear “reaction” models utilizing (discrete) reaction-diffusion equations; and (B) spatial transport problems on surfaces and in nanopores utilizing the relevant (continuum) diffusion or Fokker-Planck equations. Thus, there are some common themes in these studies, as they all involve partial differential equations or their discrete analogues which incorporate a description of diffusion-type processes. However, there are also some qualitative differences, as shall be discussed below.

Electrical resistivity dynamics beneath a fractured sedimentary bedrock riverbed in response to temperature and groundwater–surface water exchange

Directory of Open Access Journals (Sweden)

C. M. Steelman

2017-06-01

Full Text Available Bedrock rivers occur where surface water flows along an exposed rock surface. Fractured sedimentary bedrock can exhibit variable groundwater residence times, anisotropic flow paths, and heterogeneity, along with diffusive exchange between fractures and rock matrix. These properties of the rock will affect thermal transients in the riverbed and groundwater–surface water exchange. In this study, surface electrical methods were used as a non-invasive technique to assess the scale and temporal variability of riverbed temperature and groundwater–surface water interaction beneath a sedimentary bedrock riverbed. Conditions were monitored at a semi-daily to semi-weekly interval over a full annual period that included a seasonal freeze–thaw cycle. Surface electromagnetic induction (EMI and electrical resistivity tomography (ERT methods captured conditions beneath the riverbed along a pool–riffle sequence of the Eramosa River in Canada. Geophysical datasets were accompanied by continuous measurements of aqueous specific conductance, temperature, and river stage. Time-lapse vertical temperature trolling within a lined borehole adjacent to the river revealed active groundwater flow zones along fracture networks within the upper 10 m of rock. EMI measurements collected during cooler high-flow and warmer low-flow periods identified a spatiotemporal riverbed response that was largely dependent upon riverbed morphology and seasonal groundwater temperature. Time-lapse ERT profiles across the pool and riffle sequence identified seasonal transients within the upper 2 and 3 m of rock, respectively, with spatial variations controlled by riverbed morphology (pool versus riffle and dominant surficial rock properties (competent versus weathered rock rubble surface. While the pool and riffle both exhibited a dynamic resistivity through seasonal cooling and warming cycles, conditions beneath the pool were more variable, largely due to the formation of river

Study on the surface oxidation resistance of uranium metal in the atmosphere of carbon monoxide

International Nuclear Information System (INIS)

Wang Xiaolin; Fu Yibei; Xie Renshou

1999-01-01

The surface reactions of different layers on uranium metal with carbon monoxide at 25, 80 and 200 degree C are studied by X-ray photoelectron spectroscopy (XPS). The experimental results show that the carbon monoxide is adsorbed on the surface oxide layer of uranium and interacted each other. The content of oxygen in the surface oxide and O/U ratio are decreased with increasing the exposure of carbon monoxide to the surface layer. The effect of reduction on the metal surface is more obviously with a higher temperature and increasing of layer thickness. The investigation indicates the uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide

Travelling wave solutions for a surface wave equation in fluid mechanics

Directory of Open Access Journals (Sweden)

Tian Yi

2016-01-01

Full Text Available This paper considers a non-linear wave equation arising in fluid mechanics. The exact traveling wave solutions of this equation are given by using G'/G-expansion method. This process can be reduced to solve a system of determining equations, which is large and difficult. To reduce this process, we used Wu elimination method. Example shows that this method is effective.

Modelling conjugation with stochastic differential equations

DEFF Research Database (Denmark)

Philipsen, Kirsten Riber; Christiansen, Lasse Engbo; Hasman, Henrik

2010-01-01

Enterococcus faecium strains in a rich exhaustible media. The model contains a new expression for a substrate dependent conjugation rate. A maximum likelihood based method is used to estimate the model parameters. Different models including different noise structure for the system and observations are compared......Conjugation is an important mechanism involved in the transfer of resistance between bacteria. In this article a stochastic differential equation based model consisting of a continuous time state equation and a discrete time measurement equation is introduced to model growth and conjugation of two...... using a likelihood-ratio test and Akaike's information criterion. Experiments indicating conjugation on the agar plates selecting for transconjugants motivates the introduction of an extended model, for which conjugation on the agar plate is described in the measurement equation. This model is compared...

A Resistive Boundary Condition Enhanced DGTD Scheme for the Transient Analysis of Graphene

KAUST Repository

Li, Ping; Jiang, Li; Bagci, Hakan

2015-01-01

In this paper, the electromagnetic (EM) features of graphene are characterized by a discontinuous Galerkin timedomain (DGTD) algorithm with a resistive boundary condition (RBC). The atomically thick graphene is equivalently modeled using a RBC by regarding the graphene as an infinitesimally thin conductive sheet. To incorporate RBC into the DGTD analysis, the surface conductivity of the graphene composed of contributions from both intraband and interband terms is firstly approximated by rational basis functions using the fastrelaxation vector-fitting (FRVF) method in the Laplace-domain. Next, through the inverse Laplace transform, the corresponding time-domain matrix equations in integral can be obtained. Finally, these matrix equations are solved by time-domain finite integral technique (FIT). For elements not touching the graphene sheet, however, the well-known Runge-Kutta (RK) method is employed to solve the two first-order time-derivative Maxwell’s equations. The application of the surface boundary condition significantly alleviates the memory consuming and the limitation of time step size required by Courant-Friedrichs-Lewy (CFL) condition. To validate the proposed algorithm, various numerical examples are presented and compared with available references.

A Resistive Boundary Condition Enhanced DGTD Scheme for the Transient Analysis of Graphene

KAUST Repository

Li, Ping

2015-04-24

In this paper, the electromagnetic (EM) features of graphene are characterized by a discontinuous Galerkin timedomain (DGTD) algorithm with a resistive boundary condition (RBC). The atomically thick graphene is equivalently modeled using a RBC by regarding the graphene as an infinitesimally thin conductive sheet. To incorporate RBC into the DGTD analysis, the surface conductivity of the graphene composed of contributions from both intraband and interband terms is firstly approximated by rational basis functions using the fastrelaxation vector-fitting (FRVF) method in the Laplace-domain. Next, through the inverse Laplace transform, the corresponding time-domain matrix equations in integral can be obtained. Finally, these matrix equations are solved by time-domain finite integral technique (FIT). For elements not touching the graphene sheet, however, the well-known Runge-Kutta (RK) method is employed to solve the two first-order time-derivative Maxwell’s equations. The application of the surface boundary condition significantly alleviates the memory consuming and the limitation of time step size required by Courant-Friedrichs-Lewy (CFL) condition. To validate the proposed algorithm, various numerical examples are presented and compared with available references.

Targeting glucosylceramide synthase induction of cell surface globotriaosylceramide (Gb3) in acquired cisplatin-resistance of lung cancer and malignant pleural mesothelioma cells

Energy Technology Data Exchange (ETDEWEB)

Tyler, Andreas, E-mail: andreas.tyler@medbio.umu.se [Department of Medical Biosciences, Umeå University, S-901 85 Umea (Sweden); Johansson, Anders [Department of Odontology, Umeå University, S-901 85 Umea (Sweden); Karlsson, Terese [Department of Radiation Sciences, Oncology, S-901 85 Umea (Sweden); Gudey, Shyam Kumar; Brännström, Thomas; Grankvist, Kjell; Behnam-Motlagh, Parviz [Department of Medical Biosciences, Umeå University, S-901 85 Umea (Sweden)

2015-08-01

Background: Acquired resistance to cisplatin treatment is a caveat when treating patients with non-small cell lung cancer (NSCLC) and malignant pleural mesothelioma (MPM). Ceramide increases in response to chemotherapy, leading to proliferation arrest and apoptosis. However, a tumour stress activation of glucosylceramide synthase (GCS) follows to eliminate ceramide by formation of glycosphingolipids (GSLs) such as globotriaosylceramide (Gb3), the functional receptor of verotoxin-1. Ceramide elimination enhances cell proliferation and apoptosis blockade, thus stimulating tumor progression. GSLs transactivate multidrug resistance 1/P-glycoprotein (MDR1) and multidrug resistance-associated protein 1 (MRP1) expression which further prevents ceramide accumulation and stimulates drug efflux. We investigated the expression of Gb3, MDR1 and MRP1 in NSCLC and MPM cells with acquired cisplatin resistance, and if GCS activity or MDR1 pump inhibitors would reduce their expression and reverse cisplatin-resistance. Methods: Cell surface expression of Gb3, MDR1 and MRP1 and intracellular expression of MDR1 and MRP1 was analyzed by flow cytometry and confocal microscopy on P31 MPM and H1299 NSCLC cells and subline cells with acquired cisplatin resistance. The effect of GCS inhibitor PPMP and MDR1 pump inhibitor cyclosporin A for 72 h on expression and cisplatin cytotoxicity was tested. Results: The cisplatin-resistant cells expressed increased cell surface Gb3. Cell surface Gb3 expression of resistant cells was annihilated by PPMP whereas cyclosporin A decreased Gb3 and MDR1 expression in H1299 cells. No decrease of MDR1 by PPMP was noted in using flow cytometry, whereas a decrease of MDR1 in H1299 and H1299res was indicated with confocal microscopy. No certain co-localization of Gb3 and MDR1 was noted. PPMP, but not cyclosporin A, potentiated cisplatin cytotoxicity in all cells. Conclusions: Cell surface Gb3 expression is a likely tumour biomarker for acquired cisplatin

The Interface Structure of High-Temperature Oxidation-Resistant Aluminum-Based Coatings on Titanium Billet Surface

Science.gov (United States)

Xu, Zhefeng; Rong, Ju; Yu, Xiaohua; Kun, Meng; Zhan, Zhaolin; Wang, Xiao; Zhang, Yannan

2017-10-01

A new type of high-temperature oxidation-resistant aluminum-based coating, on a titanium billet surface, was fabricated by the cold spray method, at a high temperature of 1050°C, for 8 h, under atmospheric pressure. The microstructure of the exposed surface was analyzed via optical microscopy, the microstructure of the coating and elemental diffusion was analyzed via field emission scanning electron microscopy, and the interfacial phases were identified via x-ray diffraction. The Ti-Al binary phase diagram and Gibbs free energy of the stable phase were calculated by Thermo-calc. The results revealed that good oxidation resistant 50-μm-thick coatings were successfully obtained after 8 h at 1050°C. Two layers were obtained after the coating process: an Al2O3 oxidation layer and a TiAl3 transition layer on the Ti-based substrate. The large and brittle Al2O3 grains on the surface, which can be easily spalled off from the surface after thermal processing, protected the substrate against oxidation during processing. In addition, the thermodynamic calculation results were in good agreement with the experimental data.

Liouville master equation for multielectron dynamics: Neutralization of highly charged ions near a LiF surface

International Nuclear Information System (INIS)

Wirtz, Ludger; Reinhold, Carlos O.; Lemell, Christoph; Burgdoerfer, Joachim

2003-01-01

We present a simulation of the neutralization of highly charged ions in front of a lithium fluoride surface including the close-collision regime above the surface. The present approach employs a Monte Carlo solution of the Liouville master equation for the joint probability density of the ionic motion and the electronic population of the projectile and the target surface. It includes single as well as double particle-hole (de)excitation processes and incorporates electron correlation effects through the conditional dynamics of population strings. The input in terms of elementary one- and two-electron transfer rates is determined from classical trajectory Monte Carlo calculations as well as quantum-mechanical Auger calculations. For slow projectiles and normal incidence, the ionic motion depends sensitively on the interplay between image acceleration towards the surface and repulsion by an ensemble of positive hole charges in the surface ('trampoline effect'). For Ne 10+ we find that image acceleration is dominant and no collective backscattering high above the surface takes place. For grazing incidence, our simulation delineates the pathways to complete neutralization. In accordance with recent experimental observations, most ions are reflected as neutral or even as singly charged negative particles, irrespective of the charge state of the incoming ions

Biofilm-Forming Staphylococcus epidermidis Expressing Vancomycin Resistance Early after Adhesion to a Metal Surface

Directory of Open Access Journals (Sweden)

Toshiyuki Sakimura

2015-01-01

Full Text Available We investigated biofilm formation and time of vancomycin (VCM resistance expression after adhesion to a metal surface in Staphylococcus epidermidis. Biofilm-forming Staphylococcus epidermidis with a VCM MIC of 1 μg/mL was used. The bacteria were made to adhere to a stainless steel washer and treated with VCM at different times and concentrations. VCM was administered 0, 2, 4, and 8 hours after adhesion. The amount of biofilm formed was evaluated based on the biofilm coverage rates (BCRs before and after VCM administration, bacterial viability in biofilm was visually observed using the fluorescence staining method, and the viable bacterial count in biofilm was measured. The VCM concentration required to decrease BCR significantly compared with that of VCM-untreated bacteria was 4 μg/mL, even in the 0 hr group. In the 4 and 8 hr groups, VCM could not inhibit biofilm growth even at 1,024 μg/mL. In the 8 hr group, viable bacteria remained in biofilm at a count of 104 CFU even at a high VCM concentration (1,024 μg/mL. It was suggested that biofilm-forming Staphylococcus epidermidis expresses resistance to VCM early after adhesion to a metal surface. Resistance increased over time after adhesion as the biofilm formed, and strong resistance was expressed 4–8 hours after adhesion.

Experimental research on microhardness and wear resistances of pure Cu subjected to surface dynamic plastic deformation by ultrasonic impact

Science.gov (United States)

Chen, Zhaoxia; He, Yangming

2018-04-01

Dynamic plastic deformation (DPD) has been induced in the surface of pure Cu by ultrasonic impact treating (UIT) with the varied impact current and coverage percentage. The microstructures of the treated surface were analyzed by a scanning electron microscope (SEM). And the wear resistance of pure Cu was experimentally researched both with the treated and untreated specimens. The effect of DPD on the hardness was also investigated using microhardness tester. The results show that the grains on the top surfaces of pure Cu are highly refined. The maximum depth of the plastic deformation layer is approximately 1400 µm. The larger the current and coverage percentage, the greater of the microhardness and wear resistance the treated surface layer of pure Cu will be. When the impact current is 2 A and coverage percentage is 300%, the microhardness and wear resistance of the treated sample is about 276.1% and 68.8% higher than that of the untreated specimen, respectively. But the properties of the treated sample deteriorate when the UIT current is 3 A and the coverage percentage is 300% because of the formation of a new phase forms in the treated surface.

Estimating glomerular filtration rate using the new CKD-EPI equation and other equations in patients with autosomal dominant polycystic kidney disease

DEFF Research Database (Denmark)

Orskov, Bjarne; Borresen, Malene L; Feldt-Rasmussen, Bo

2010-01-01

(CKD-EPI) equation, the Cockcroft-Gault equation adjusted for body surface area and the MDRD equation with cystatin C. Performance was evaluated by mean bias, precision and accuracy. RESULTS: The MDRD equation with cystatin C had 97% of GFR estimates within 30% of measured GFR (accuracy). Both the CKD-EPI....... The CKD-EPI or the Cockcroft-Gault equations showed better performance compared to the 4-variable MDRD equation....

Surface potential measurement on contact resistance of amorphous-InGaZnO thin film transistors by Kelvin probe force microscopy

Science.gov (United States)

Han, Zhiheng; Xu, Guangwei; Wang, Wei; Lu, Congyan; Lu, Nianduan; Ji, Zhuoyu; Li, Ling; Liu, Ming

2016-07-01

Contact resistance plays an important role in amorphous InGaZnO (a-IGZO) thin film transistors (TFTs). In this paper, the surface potential distributions along the channel have been measured by using Kelvin probe force microscopy (KPFM) on operating a-IGZO TFTs, and sharp potential drops at the edges of source and drain were observed. The source and drain contact resistances can be extracted by dividing sharp potential drops with the corresponding drain to source current. It is found that the contact resistances could not be neglected compared with the whole channel resistances in the a-IGZO TFT, and the contact resistances decrease remarkably with increasing gate biased voltage. Our results suggest that the contact resistances can be controlled by tuning the gate biased voltage. Moreover, a transition from gradual channel approximation to space charge region was observed through the surface potential map directly when TFT operating from linear regime to saturation regime.

Effects of plasma treatment time on surface characteristics of indium-tin-oxide film for resistive switching storage applications

International Nuclear Information System (INIS)

Chen, Po-Hsun; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Pan, Chih-Hung; Shih, Chih-Cheng; Wu, Cheng-Hsien; Yang, Chih-Cheng; Chen, Wen-Chung; Lin, Jiun-Chiu; Wang, Ming-Hui; Zheng, Hao-Xuan; Chen, Min-Chen; Sze, Simon M.

2017-01-01

In this paper, we implement a post-oxidation method to modify surface characteristics of indium tin oxide (ITO) films by using an O_2 inductively coupled plasma (ICP) treatment. Based on field emission-scanning electron microscope (FE-SEM) and atomic force microscope (AFM) analysis, we found that the surface morphologies of the ITO films become slightly flatter after the O_2 plasma treatment. The optical characteristics and X-ray diffraction (XRD) experiments of either pure ITO or O_2 plasma treated ITO films were also verified. Even though the XRD results showed no difference from bulk crystallizations, the oxygen concentrations increased at the film surface after O_2 plasma treatment, according to the XPS inspection results. Moreover, this study investigated the effects of two different plasma treatment times on oxygen concentration in the ITO films. The surface sheet resistance of the plasma treated ITO films became nearly non-conductive when measured with a 4-point probe. Finally, we applied the O_2 plasma treated ITO films as the insulator in resistive random access memory (RRAM) to examine their potential for use in resistive switching storage applications. Stable resistance switching characteristics were obtained by applying the O_2 plasma treatment to the ITO-based RRAM. We also confirmed the relationship between plasma treatment time and RRAM performance. These material analyses and electrical measurements suggest possible advantages in using this plasma treatment technique in device fabrication processes for RRAM applications.

Effects of plasma treatment time on surface characteristics of indium-tin-oxide film for resistive switching storage applications

Energy Technology Data Exchange (ETDEWEB)

Chen, Po-Hsun [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Chang, Ting-Chang, E-mail: tcchang3708@gmail.com [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Advanced Optoelectronics Technology Center, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Chang, Kuan-Chang, E-mail: kcchang@pkusz.edu.cn [Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); School of Electronic and Computer Engineering, Peking University, Shenzhen 518055 (China); Tsai, Tsung-Ming; Pan, Chih-Hung; Shih, Chih-Cheng; Wu, Cheng-Hsien; Yang, Chih-Cheng; Chen, Wen-Chung; Lin, Jiun-Chiu; Wang, Ming-Hui [Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Zheng, Hao-Xuan; Chen, Min-Chen [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Sze, Simon M. [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu 300, Taiwan, ROC (China)

2017-08-31

In this paper, we implement a post-oxidation method to modify surface characteristics of indium tin oxide (ITO) films by using an O{sub 2} inductively coupled plasma (ICP) treatment. Based on field emission-scanning electron microscope (FE-SEM) and atomic force microscope (AFM) analysis, we found that the surface morphologies of the ITO films become slightly flatter after the O{sub 2} plasma treatment. The optical characteristics and X-ray diffraction (XRD) experiments of either pure ITO or O{sub 2} plasma treated ITO films were also verified. Even though the XRD results showed no difference from bulk crystallizations, the oxygen concentrations increased at the film surface after O{sub 2} plasma treatment, according to the XPS inspection results. Moreover, this study investigated the effects of two different plasma treatment times on oxygen concentration in the ITO films. The surface sheet resistance of the plasma treated ITO films became nearly non-conductive when measured with a 4-point probe. Finally, we applied the O{sub 2} plasma treated ITO films as the insulator in resistive random access memory (RRAM) to examine their potential for use in resistive switching storage applications. Stable resistance switching characteristics were obtained by applying the O{sub 2} plasma treatment to the ITO-based RRAM. We also confirmed the relationship between plasma treatment time and RRAM performance. These material analyses and electrical measurements suggest possible advantages in using this plasma treatment technique in device fabrication processes for RRAM applications.

A one-layer satellite surface energy balance for estimating evapotranspiration rates and crop water stress indexes.

Science.gov (United States)

Barbagallo, Salvatore; Consoli, Simona; Russo, Alfonso

2009-01-01

Daily evapotranspiration fluxes over the semi-arid Catania Plain area (Eastern Sicily, Italy) were evaluated using remotely sensed data from Landsat Thematic Mapper TM5 images. A one-source parameterization of the surface sensible heat flux exchange using satellite surface temperature has been used. The transfer of sensible and latent heat is described by aerodynamic resistance and surface resistance. Required model inputs are brightness, temperature, fractional vegetation cover or leaf area index, albedo, crop height, roughness lengths, net radiation, air temperature, air humidity and wind speed. The aerodynamic resistance (r(ah)) is formulated on the basis of the Monin-Obukhov surface layer similarity theory and the surface resistance (r(s)) is evaluated from the energy balance equation. The instantaneous surface flux values were converted into evaporative fraction (EF) over the heterogeneous land surface to derive daily evapotranspiration values. Remote sensing-based assessments of crop water stress (CWSI) were also made in order to identify local irrigation requirements. Evapotranspiration data and crop coefficient values obtained from the approach were compared with: (i) data from the semi-empirical approach "K(c) reflectance-based", which integrates satellite data in the visible and NIR regions of the electromagnetic spectrum with ground-based measurements and (ii) surface energy flux measurements collected from a micrometeorological tower located in the experiment area. The expected variability associated with ET flux measurements suggests that the approach-derived surface fluxes were in acceptable agreement with the observations.

Effect of fluoride on ion exchange, remineralization and acid resistance of surface enamel

Energy Technology Data Exchange (ETDEWEB)

Aponte-Merced, L A; Feagin, F F [Alabama Univ., Birmingham (USA)

1979-01-01

In a system of constant ion activities the rates of F/sup -/ exchange in enamel, under conditions of exchange alone and remineralization, depended on the concentration of F/sup -/ in solutions. Acid resistance of surface minerals resulted from exchange of F/sup -/ for OH/sup -/ in the enamel at pH 7.0 and 4.5. The level of 0.5 mM NaF, compared to 0.05 and 5.0 mM, caused maximum rates of isotopic exchange of /sup 45/Ca and maximum acid resistance of enamel. Similarly low levels of F/sup -/ may be feasible for use in caries prevention in the absence and presence of remineralization.

Analysis of Leaky Modes in Photonic Crystal Fibers Using the Surface Integral Equation Method

Directory of Open Access Journals (Sweden)

Jung-Sheng Chiang

2018-04-01

Full Text Available A fully vectorial algorithm based on the surface integral equation method for the modelling of leaky modes in photonic crystal fibers (PCFs by solely solving the complex propagation constants of characteristic equations is presented. It can be used for calculations of the complex effective index and confinement losses of photonic crystal fibers. As complex root examination is the key technique in the solution, the new algorithm which possesses this technique can be used to solve the leaky modes of photonic crystal fibers. The leaky modes of solid-core PCFs with a hexagonal lattice of circular air-holes are reported and discussed. The simulation results indicate how the confinement loss by the imaginary part of the effective index changes with air-hole size, the number of rings of air-holes, and wavelength. Confinement loss reductions can be realized by increasing the air-hole size and the number of air-holes. The results show that the confinement loss rises with wavelength, implying that the light leaks more easily for longer wavelengths; meanwhile, the losses are decreased significantly as the air-hole size d/Λ is increased.

Ultrasensitive probing of the protein resistance of PEG surfaces by secondary ion mass spectrometry

DEFF Research Database (Denmark)

Kingshott, P.; McArthur, S.; Thissen, H.

2002-01-01

The highly sensitive surface analytical techniques X-ray photoelectron spectroscopy (XPS) and time-of-flight static secondary ion mass spectrometry (ToF-SIMS) were used to test the resistance of poly(ethylene glycol) (PEG) coatings towards adsorption of lysozyme (LYS) and fibronectin (FN). PEG co...

Er,Cr:YSGG Laser Energy Delivery: Pulse and Power Effects on Enamel Surface and Erosive Resistance.

Science.gov (United States)

de Oliveira, Renan Mota; de Souza, Vinicius Matsuzaki; Esteves, Camila Machado; de Oliveira Lima-Arsati, Ynara Bosco; Cassoni, Alessandra; Rodrigues, José Augusto; Brugnera Junior, Aldo

2017-11-01

High power lasers have been suggested as a useful tool for dental caries and erosion prevention due to the increase of enamel acid resistance. to evaluate the effect of Er,Cr:YSGG (erbium,chromium:yttrium, scandium, gallium, garnet) laser irradiation pulse frequency and power on enamel surface and acid erosion resistance. By combining pulse frequency (5-75 Hz) and power settings (0.10-1.00 W), 20 irradiated groups and one nonirradiated control group were tested. A total of 63 bovine enamel blocks (n = 3/group) were prepared for surface hardness and roughness evaluation, performed in three phases: baseline, after irradiation, and after erosive challenge. Enamel blocks were irradiated with Er,Cr:YSGG laser with MZ8 tip (iPlus; Waterlase, Biolase, CA) for 30 sec according to experimental group and submitted. Erosive challenge consisted of four cycles alternating immersion in 0.01 M HCl (5 mL/mm 2 ; 2 min; at 37°C) and immersion in artificial saliva for 3 h. Analysis of variance (three-way ANOVA), Tukey's test, and Pearson correlation were performed for the statistical analysis (p hardness. After erosive challenge, 5 and 75 W groups showed increase in surface hardness; 0.25, 0.5, 0.75, and 1 W groups showed minor alterations in surface roughness. the irradiation of Er,Cr:YSGG laser with different parameters of power and pulse frequency settings may alter enamel surface and erosive resistance differently. Pulse frequency of 30 Hz and power of 0.50 W was considered the best parameter to prevent enamel acid erosion.

Surface microstructures and corrosion resistance of Ni-Ti-Nb shape memory thin films

Science.gov (United States)

Li, Kun; Li, Yan; Huang, Xu; Gibson, Des; Zheng, Yang; Liu, Jiao; Sun, Lu; Fu, Yong Qing

2017-08-01

Ni-Ti-Nb and Ni-Ti shape memory thin films were sputter-deposited onto silicon substrates and annealed at 600 °C for crystallization. X-ray diffraction (XRD) measurements indicated that all of the annealed Ni-Ti-Nb films were composed of crystalline Ni-Ti (Nb) and Nb-rich grains. X-ray photoelectron spectroscopy (XPS) tests showed that the surfaces of Ni-Ti-Nb films were covered with Ti oxides, NiO and Nb2O5. The corrosion resistance of the Ni-Ti-Nb films in 3.5 wt.% NaCl solution was investigated using electrochemical tests such as open-circuit potential (OCP) and potentio-dynamic polarization tests. Ni-Ti-Nb films showed higher OCPs, higher corrosion potentials (Ecorr) and lower corrosion current densities (icorr) than the binary Ni-Ti film, which indicated a better corrosion resistance. The reason may be that Nb additions modified the passive layer on the film surface. The OCPs of Ni-Ti-Nb films increased with further Nb additions, whereas no apparent difference of Ecorr and icorr was found among the Ni-Ti-Nb films.

Visualization of Two Phase Flow in a Horizontal Flow with Electrical Resistance Tomography based on Extended Kalman Filter

International Nuclear Information System (INIS)

Lee, Jeong Seong; Malik, Nauman Muhammad; Khambampati, Anil Kumar; Rashid, Ahmar; Kim, Sin; Kim, Kyung Youn

2008-01-01

For the visualization of the phase distribution in two phase flows, the electrical resistance tomography (ERT) technique is introduced. In ERT, the internal resistivity distribution is reconstructed based on the known sets of the injected currents and measured voltages on the surface of the object. The physical relationship between the internal resistivity and the surface voltages is governed by a partial differential equation with appropriate boundary conditions. This paper considers the estimation of the phase distribution with ERT in two phase flow in a horizontal flow using extended Kalman filter. To evaluate the reconstruction performance of the proposed algorithm, the experiments simulated two phase flows in a horizontal flow were carried out. The experiments with two phase flow phantom were done to suggest a practical implication of this research in detecting gas bubble in a feed water pipe of heat transfer systems

Heat-resistant organic molecular layer as a joint interface for metal reduction on plastics surfaces

International Nuclear Information System (INIS)

Sang, Jing; Aisawa, Sumio; Hirahara, Hidetoshi; Kudo, Takahiro; Mori, Kunio

2016-01-01

Graphical abstract: - Highlights: • In situ adsorption behaviors of TES on PA6 surface were clarified by QCM. • Highest adsorption of TES on PA6 was obtained in pH 3 and 0.1 M solution. • Molecular layers of TES with uniform structures were prepared on PA6 surface. • TES layer improved PA6 local heat resistance from 150 °C to 230 °C. • TES molecular layer successfully reduced Ag ion to Ag"0. - Abstract: Heat-resistant organic molecular layers have been fabricated by triazine-based silane coupling agent for metal reduction on plastic surfaces using adsorption method. These molecular layers were used as an interfacial layer between polyamide (PA6) and metal solution to reduce Ag"+ ion to Ag"0. The interfacial behaviors of triazine molecular layer at the interfaces between PA6 and Ag solution were investigated using quartz crystal microbalance (QCM). The kinetics of molecular adsorption on PA6 was investigated by using triazine-based silane coupling agent solutions at different pH and concentration. X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and local nano thermal analysis were employed to characterize the surfaces and interfaces. The nano thermal analysis results show that molecular layers of triazine-based silane coupling agent greatly improved heat resistance of PA6 resin from 170 °C up to 230 °C. This research developed an in-depth insight for molecular behaviors of triazine-based silane coupling agent at the PA6 and Ag solution interfaces and should be of significant value for interfacial research between plastics and metal solution in plating industry.

Heat-resistant organic molecular layer as a joint interface for metal reduction on plastics surfaces

Energy Technology Data Exchange (ETDEWEB)

Sang, Jing [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Aisawa, Sumio, E-mail: aisawa@iwate-u.ac.jp [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Hirahara, Hidetoshi [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Kudo, Takahiro [Sulfur Chemical Institute, 210, Collabo MIU, 4-3-5, Ueda, Morioka 020-0066 (Japan); Mori, Kunio [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Sulfur Chemical Institute, 210, Collabo MIU, 4-3-5, Ueda, Morioka 020-0066 (Japan)

2016-04-15

Graphical abstract: - Highlights: • In situ adsorption behaviors of TES on PA6 surface were clarified by QCM. • Highest adsorption of TES on PA6 was obtained in pH 3 and 0.1 M solution. • Molecular layers of TES with uniform structures were prepared on PA6 surface. • TES layer improved PA6 local heat resistance from 150 °C to 230 °C. • TES molecular layer successfully reduced Ag ion to Ag{sup 0}. - Abstract: Heat-resistant organic molecular layers have been fabricated by triazine-based silane coupling agent for metal reduction on plastic surfaces using adsorption method. These molecular layers were used as an interfacial layer between polyamide (PA6) and metal solution to reduce Ag{sup +} ion to Ag{sup 0}. The interfacial behaviors of triazine molecular layer at the interfaces between PA6 and Ag solution were investigated using quartz crystal microbalance (QCM). The kinetics of molecular adsorption on PA6 was investigated by using triazine-based silane coupling agent solutions at different pH and concentration. X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and local nano thermal analysis were employed to characterize the surfaces and interfaces. The nano thermal analysis results show that molecular layers of triazine-based silane coupling agent greatly improved heat resistance of PA6 resin from 170 °C up to 230 °C. This research developed an in-depth insight for molecular behaviors of triazine-based silane coupling agent at the PA6 and Ag solution interfaces and should be of significant value for interfacial research between plastics and metal solution in plating industry.

Hamilton's equations for a fluid membrane

Energy Technology Data Exchange (ETDEWEB)

Capovilla, R [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados, Apdo. Postal 14-740, 07000 Mexico, DF (Mexico); Guven, J [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apdo. Postal 70-543, 04510 Mexico, DF (Mexico); Rojas, E [Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)

2005-10-14

Consider a homogeneous fluid membrane described by the Helfrich-Canham energy, quadratic in the mean curvature of the membrane surface. The shape equation that determines equilibrium configurations is fourth order in derivatives and cubic in the mean curvature. We introduce a Hamiltonian formulation of this equation which dismantles it into a set of coupled first-order equations. This involves interpreting the Helfrich-Canham energy as an action; equilibrium surfaces are generated by the evolution of space curves. Two features complicate the implementation of a Hamiltonian framework. (i) The action involves second derivatives. This requires treating the velocity as a phase-space variable and the introduction of its conjugate momentum. The canonical Hamiltonian is constructed on this phase space. (ii) The action possesses a local symmetry-reparametrization invariance. The two labels we use to parametrize points on the surface are themselves physically irrelevant. This symmetry implies primary constraints, one for each label, that need to be implemented within the Hamiltonian. The two Lagrange multipliers associated with these constraints are identified as the components of the acceleration tangential to the surface. The conservation of the primary constraints implies two secondary constraints, fixing the tangential components of the momentum conjugate to the position. Hamilton's equations are derived and the appropriate initial conditions on the phase-space variables are identified. Finally, it is shown how the shape equation can be reconstructed from these equations.

Two dimensional generalizations of the Newcomb equation

International Nuclear Information System (INIS)

Dewar, R.L.; Pletzer, A.

1989-11-01

The Bineau reduction to scalar form of the equation governing ideal, zero frequency linearized displacements from a hydromagnetic equilibrium possessing a continuous symmetry is performed in 'universal coordinates', applicable to both the toroidal and helical cases. The resulting generalized Newcomb equation (GNE) has in general a more complicated form than the corresponding one dimensional equation obtained by Newcomb in the case of circular cylindrical symmetry, but in this cylindrical case , the equation can be transformed to that of Newcomb. In the two dimensional case there is a transformation which leaves the form of the GNE invariant and simplifies the Frobenius expansion about a rational surface, especially in the limit of zero pressure gradient. The Frobenius expansions about a mode rational surface is developed and the connection with Hamiltonian transformation theory is shown. 17 refs

Analysis of atmospheric flow over a surface protrusion using the turbulence kinetic energy equation with reference to aeronautical operating systems

Science.gov (United States)

Frost, W.; Harper, W. L.

1975-01-01

Flow over surface obstructions can produce significantly large wind shears such that adverse flying conditions can occur for aeronautical systems (helicopters, STOL vehicles, etc.). Atmospheric flow fields resulting from a semi-elliptical surface obstruction in an otherwise horizontally homogeneous statistically stationary flow are modelled with the boundary-layer/Boussinesq-approximation of the governing equation of fluid mechanics. The turbulence kinetic energy equation is used to determine the dissipative effects of turbulent shear on the mean flow. Iso-lines of turbulence kinetic energy and turbulence intensity are plotted in the plane of the flow and highlight regions of high turbulence intensity in the stagnation zone and sharp gradients in intensity along the transition from adverse to favourable pressure gradient. Discussion of the effects of the disturbed wind field in CTOL and STOL aircraft flight path and obstruction clearance standards is given. The results indicate that closer inspection of these presently recommended standards as influenced by wind over irregular terrains is required.

Transport equation solving methods

International Nuclear Information System (INIS)

Granjean, P.M.

1984-06-01

This work is mainly devoted to Csub(N) and Fsub(N) methods. CN method: starting from a lemma stated by Placzek, an equivalence is established between two problems: the first one is defined in a finite medium bounded by a surface S, the second one is defined in the whole space. In the first problem the angular flux on the surface S is shown to be the solution of an integral equation. This equation is solved by Galerkin's method. The Csub(N) method is applied here to one-velocity problems: in plane geometry, slab albedo and transmission with Rayleigh scattering, calculation of the extrapolation length; in cylindrical geometry, albedo and extrapolation length calculation with linear scattering. Fsub(N) method: the basic integral transport equation of the Csub(N) method is integrated on Case's elementary distributions; another integral transport equation is obtained: this equation is solved by a collocation method. The plane problems solved by the Csub(N) method are also solved by the Fsub(N) method. The Fsub(N) method is extended to any polynomial scattering law. Some simple spherical problems are also studied. Chandrasekhar's method, collision probability method, Case's method are presented for comparison with Csub(N) and Fsub(N) methods. This comparison shows the respective advantages of the two methods: a) fast convergence and possible extension to various geometries for Csub(N) method; b) easy calculations and easy extension to polynomial scattering for Fsub(N) method [fr

Fracture resistance of dental nickel-titanium rotary instruments with novel surface treatment: Thin film metallic glass coating.

Science.gov (United States)

Chi, Chih-Wen; Deng, Yu-Lun; Lee, Jyh-Wei; Lin, Chun-Pin

2017-05-01

Dental nickel-titanium (NiTi) rotary instruments are widely used in endodontic therapy because they are efficient with a higher success rate. However, an unpredictable fracture of instruments may happen due to the surface characteristics of imperfection (or irregularity). This study assessed whether a novel surface treatment could increase fatigue fracture resistance of dental NiTi rotary instruments. A 200- or 500-nm thick Ti-zirconium-boron (Ti-Zr-B) thin film metallic glass was deposited on ProTaper Universal F2 files using a physical vapor deposition process. The characteristics of coating were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. In cyclic fatigue tests, the files were performed in a simulated root canal (radius=5 mm, angulation=60°) under a rotating speed of 300rpm. The fatigue fractured cross sections of the files were analyzed with their fractographic performances through scanning electron microscopy images. The amorphous structure of the Ti-Zr-B coating was confirmed by transmission electron microscopy and X-ray diffractometry. The surface of treated files presented smooth morphologies without grinding irregularity. For the 200- and 500-nm surface treatment groups, the coated files exhibited higher resistance of cyclic fatigue than untreated files. In fractographic analysis, treated files showed significantly larger crack-initiation zone; however, no significant differences in the areas of fatigue propagation and catastrophic fracture were found compared to untreated files. The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure. Copyright © 2016. Published by Elsevier B.V.

Silane effects on the surface morphology and abrasion resistance of transparent SiO2/UV-curable resin nano-composites

International Nuclear Information System (INIS)

Hsiang, Hsing-I.; Chang, Yu-Lun; Chen, Chi-Yu; Yen, Fu-Su

2011-01-01

Transparent ultraviolet curable nano-composite coatings consisting of nano-sized SiO 2 and acrylate resin have been developed to improve the abrasion resistance of organic polymers. The nano-sized SiO 2 particles were surface-modified using various amounts of 3-methacryloxypropyltrimethoxysilane. The 3-methacryloxypropyltrimethoxysilane concentration effects on the surface morphology and abrasion resistance of the transparent SiO 2 /ultraviolet-curable resin nano-composites were investigated using scanning electron microscopy, atomic force microscopy, and ultraviolet-visible spectrophotometer. The results showed that as the 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio increased from 0.2 to 0.6, the dispersion, compatibility and cross-linking density between the 3-methacryloxypropyltrimethoxysilane-modified SiO 2 particles and acrylate resin were improved, leading to an increase in abrasion resistance. However, as the 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio was increased to 1.5, the additional 3-methacryloxypropyltrimethoxysilane may exceed that needed to fill the pores with the probability of SiO 2 nano-particles existing on the coating surface was lower than that for samples with a 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio of 0.6. This produced a decrease in abrasion resistance.

Nonclassical Symmetries for Nonlinear Partial Differential Equations via Compatibility

International Nuclear Information System (INIS)

El-Sabbagh, Mostafa F.; Ahmad, Ali T.

2011-01-01

The determining equations for the nonclassical symmetry reductions of nonlinear partial differential equations with arbitrary order can be obtained by requiring the compatibility between the original equations and the invariant surface conditions. The (2+1)-dimensional shallow water wave equation, Boussinesq equation, and the dispersive wave equations in shallow water serve as examples illustrating how compatibility leads quickly and easily to the determining equations for their nonclassical symmetries. (general)

Exact solution of nonsteady thermal boundary layer equation

International Nuclear Information System (INIS)

Dorfman, A.S.

1995-01-01

There are only a few exact solutions of the thermal boundary layer equation. Most of them are derived for a specific surface temperature distribution. The first exact solution of the steady-state boundary layer equation was given for a plate with constant surface temperature and free-stream velocity. The same problem for a plate with polynomial surface temperature distribution was solved by Chapmen and Rubesin. Levy gave the exact solution for the case of a power law distribution of both surface temperature and free-stream velocity. The exact solution of the steady-state boundary layer equation for an arbitrary surface temperature and a power law free-stream velocity distribution was given by the author in two forms: of series and of the integral with an influence function of unheated zone. A similar solution of the nonsteady thermal boundary layer equation for an arbitrary surface temperature and a power law free-stream velocity distribution is presented here. In this case, the coefficients of series depend on time, and in the limit t → ∞ they become the constant coefficients of a similar solution published before. This solution, unlike the one presented here, does not satisfy the initial conditions at t = 0, and, hence, can be used only in time after the beginning of the process. The solution in the form of a series becomes a closed-form exact solution for polynomial surface temperature and a power law free-stream velocity distribution. 7 refs., 2 figs

Effect of nitriding surface treatment on the corrosion resistance of dental nickel-titanium files in 5.25% sodium hypochlorite solution

Energy Technology Data Exchange (ETDEWEB)

Liu, J.-F. [Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Department of Dentistry, Taichung Veterans General Hospital, Taichung, Taiwan (China); Lin, M.-C. [Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Department of Dental Laboratory Technology, Central Taiwan University of Science and Technology, Taichung, Taiwan (China); Hsu, M.-L. [Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Li, U.-M. [Dental Department, Cardinal Tien Hospital, Hsintien, Taiwan (China); Lin, C.-P. [Department of Dentistry, National Taiwan University, Taipei, Taiwan (China); Tsai, W.-F.; Ai, C.-F. [Institute of Nuclear Energy Research, Atomic Energy Council, Taoyuan, Taiwan (China); Chen, L.-K. [Department of Dentistry, Taipei City Hospital, Taipei, Taiwan (China); Huang, H.-H. [Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Department of Dentistry, Taipei City Hospital, Taipei, Taiwan (China); Institute of Oral Biology, National Yang-Ming University, Taipei, Taiwan (China)], E-mail: hhhuang@ym.edu.tw

2009-05-05

This study investigated the effect of nitriding surface treatment on the corrosion resistance of commercial dental alloy, in the form of helical nickel-titanium (Ni-Ti) files, when treated with 5.25% sodium hypochlorite (NaOCl) solution. The surface of dental helical Ni-Ti files was modified using nitriding treatment at 200 deg. C, 250 deg. C and 300 deg. C in an NH{sub 3}-containing environment. The surface morphology and chemical composition of the Ni-Ti files were analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The corrosion resistance of the Ni-Ti files when treated with a clinical solution of 5.25% NaOCl was evaluated using the linear polarization method and by potentiodynamic polarization curve measurement. The nitriding treatments at different temperatures created titanium nitride (TiN) on the surface of the helical Ni-Ti files. The Ni-Ti files nitrided at 200 deg. C and 250 deg. C showed higher polarization resistance and higher passive film breakdown potential together with a lower passive current than untreated files. The presence of TiN on dental Ni-Ti files significantly increased the corrosion resistance of the files in the presence of 5.25% NaOCl solution.

Effect of nitriding surface treatment on the corrosion resistance of dental nickel-titanium files in 5.25% sodium hypochlorite solution

International Nuclear Information System (INIS)

Liu, J.-F.; Lin, M.-C.; Hsu, M.-L.; Li, U.-M.; Lin, C.-P.; Tsai, W.-F.; Ai, C.-F.; Chen, L.-K.; Huang, H.-H.

2009-01-01

This study investigated the effect of nitriding surface treatment on the corrosion resistance of commercial dental alloy, in the form of helical nickel-titanium (Ni-Ti) files, when treated with 5.25% sodium hypochlorite (NaOCl) solution. The surface of dental helical Ni-Ti files was modified using nitriding treatment at 200 deg. C, 250 deg. C and 300 deg. C in an NH 3 -containing environment. The surface morphology and chemical composition of the Ni-Ti files were analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The corrosion resistance of the Ni-Ti files when treated with a clinical solution of 5.25% NaOCl was evaluated using the linear polarization method and by potentiodynamic polarization curve measurement. The nitriding treatments at different temperatures created titanium nitride (TiN) on the surface of the helical Ni-Ti files. The Ni-Ti files nitrided at 200 deg. C and 250 deg. C showed higher polarization resistance and higher passive film breakdown potential together with a lower passive current than untreated files. The presence of TiN on dental Ni-Ti files significantly increased the corrosion resistance of the files in the presence of 5.25% NaOCl solution.

Introduction to partial differential equations with applications

CERN Document Server

Zachmanoglou, E C

1988-01-01

This text explores the essentials of partial differential equations as applied to engineering and the physical sciences. Discusses ordinary differential equations, integral curves and surfaces of vector fields, the Cauchy-Kovalevsky theory, more. Problems and answers.

Effect of Surface Contaminants Remained on the Blasted Surface on Epoxy Coating Performance and Corrosion Resistance

International Nuclear Information System (INIS)

Baek, Kwang Ki; Park, Chung Seo; Kim, Ki Hong; Chung, Mong Kyu; Park, Jin Hwan

2006-01-01

One of the critical issues in the coating specification is the allowable limit of surface contaminant(s) - such as soluble salt(s), grit dust, and rust - after grit blasting. Yet, there is no universally accepted data supporting the relationship between the long-term coating performance and the amount of various surface contaminants allowed after grit blasting. In this study, it was attempted to prepare epoxy coatings applied on grit-blasted steel substrate dosed with controlled amount of surface contaminants - such as soluble salt(s), grit dust, and rust. Then, coating samples were subjected to 4,200 hours of cyclic test(NORSOK M-501), which were then evaluated in terms of resistance to rust creepage, blistering, chalking, rusting, cracking and adhesion strength. Additional investigations on the possible damage at the paint/steel interface were carried out using an Electrochemical Impedance Spectroscopy(EIS) and observations of under-film-corrosion. Test results suggested that the current industrial specifications were well matched with the allowable degree of rust, whereas the allowable amount of soluble salt and grit dust after grit blasting showed a certain deviation from the specifications currently employed for fabrication of marine vessels and offshore facilities

Building unique surface structure on aramid fibers through a green layer-by-layer self-assembly technique to develop new high performance fibers with greatly improved surface activity, thermal resistance, mechanical properties and UV resistance

Energy Technology Data Exchange (ETDEWEB)

Zhou, Lifang; Yuan, Li; Guan, Qingbao; Gu, Aijuan, E-mail: ajgu@suda.edu.cn; Liang, Guozheng, E-mail: lgzheng@suda.edu.cn

2017-07-31

Highlights: • A green technology is setup to build unique surface structure on aramid fiber (AF). • The method is layer-by-layer self-assembling SiO{sub 2} and layered double hydroxide. • The surface of AF is adjustable by controlling the self-assembly cycle number. • New AF has excellent surface activity, anti-UV, thermal and mechanical properties. • The origin behind attractive performances of new AFs was intensively studied. - Abstract: Combining green preparation and high performance is becoming the direction of sustainable development of materials. How to simultaneously overcome the two bottlenecks (poor surface activity and UV resistance) of aramid fibers (AFs) while improving thermal and mechanical properties through a green process is still an interesting issue with big challenge. Herein, new AFs (BL-AFs) were prepared by alternately self-assembling SiO{sub 2} and MgAlFe layered double hydroxide (LDH) on surfaces of AFs, successively, through a green layer-by-layer (LBL) self-assembly technique without using high temperature and organic solvent. The structures and properties of BL-AFs were systematically studied, which are controllable by adjusting the number of self-assembly cycle. The new fibers with three or more self-assembly cycles have remarkably improved surface activity, thermal resistance, mechanical properties and UV resistance compared with AFs. Typically, with three self-assembly cycles, the initial degradation temperature and char yield of the new fiber (3BL-AF) are as high as 552.9 °C and 81.2%, about 92 °C and 25.2% higher than those of AF, respectively; after 168 h-UV irradiation, the retention of tensile performances of 3BL-AF fiber is as high as 91–95%, about 29–14% higher than that of AF, showing the best overall performances among all modified AFs prepared using a green technique reported so far. The origin behind the attractive performances of BL-AFs is revealed through correlating with structures of original and

Low-resistance gateless high electron mobility transistors using three-dimensional inverted pyramidal AlGaN/GaN surfaces

International Nuclear Information System (INIS)

So, Hongyun; Senesky, Debbie G.

2016-01-01

In this letter, three-dimensional gateless AlGaN/GaN high electron mobility transistors (HEMTs) were demonstrated with 54% reduction in electrical resistance and 73% increase in surface area compared with conventional gateless HEMTs on planar substrates. Inverted pyramidal AlGaN/GaN surfaces were microfabricated using potassium hydroxide etched silicon with exposed (111) surfaces and metal-organic chemical vapor deposition of coherent AlGaN/GaN thin films. In addition, electrical characterization of the devices showed that a combination of series and parallel connections of the highly conductive two-dimensional electron gas along the pyramidal geometry resulted in a significant reduction in electrical resistance at both room and high temperatures (up to 300 °C). This three-dimensional HEMT architecture can be leveraged to realize low-power and reliable power electronics, as well as harsh environment sensors with increased surface area

Low-resistance gateless high electron mobility transistors using three-dimensional inverted pyramidal AlGaN/GaN surfaces

Energy Technology Data Exchange (ETDEWEB)

So, Hongyun, E-mail: hyso@stanford.edu [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States); Senesky, Debbie G. [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

2016-01-04

In this letter, three-dimensional gateless AlGaN/GaN high electron mobility transistors (HEMTs) were demonstrated with 54% reduction in electrical resistance and 73% increase in surface area compared with conventional gateless HEMTs on planar substrates. Inverted pyramidal AlGaN/GaN surfaces were microfabricated using potassium hydroxide etched silicon with exposed (111) surfaces and metal-organic chemical vapor deposition of coherent AlGaN/GaN thin films. In addition, electrical characterization of the devices showed that a combination of series and parallel connections of the highly conductive two-dimensional electron gas along the pyramidal geometry resulted in a significant reduction in electrical resistance at both room and high temperatures (up to 300 °C). This three-dimensional HEMT architecture can be leveraged to realize low-power and reliable power electronics, as well as harsh environment sensors with increased surface area.

Giant magnetoresistance, three-dimensional Fermi surface and origin of resistivity plateau in YSb semimetal.

Science.gov (United States)

Pavlosiuk, Orest; Swatek, Przemysław; Wiśniewski, Piotr

2016-12-09

Very strong magnetoresistance and a resistivity plateau impeding low temperature divergence due to insulating bulk are hallmarks of topological insulators and are also present in topological semimetals where the plateau is induced by magnetic field, when time-reversal symmetry (protecting surface states in topological insulators) is broken. Similar features were observed in a simple rock-salt-structure LaSb, leading to a suggestion of the possible non-trivial topology of 2D states in this compound. We show that its sister compound YSb is also characterized by giant magnetoresistance exceeding one thousand percent and low-temperature plateau of resistivity. We thus performed in-depth analysis of YSb Fermi surface by band calculations, magnetoresistance, and Shubnikov-de Haas effect measurements, which reveals only three-dimensional Fermi sheets. Kohler scaling applied to magnetoresistance data accounts very well for its low-temperature upturn behavior. The field-angle-dependent magnetoresistance demonstrates a 3D-scaling yielding effective mass anisotropy perfectly agreeing with electronic structure and quantum oscillations analysis, thus providing further support for 3D-Fermi surface scenario of magnetotransport, without necessity of invoking topologically non-trivial 2D states. We discuss data implying that analogous field-induced properties of LaSb can also be well understood in the framework of 3D multiband model.

The effect of morphology and surface composition on radiation resistance of heterogeneous material CdS-PbS

Energy Technology Data Exchange (ETDEWEB)

Malyar, I. V., E-mail: imalyar@yandex.ru; Stetsyura, S. V., E-mail: stetsyurasv@info.sgu.ru [Chernyshevsky Saratov State University (Russian Federation)

2011-07-15

As a result of a complex study of the heterophase photosensitive material CdS-PbS by the methods of scanning electron microscopy and Auger spectrometry, it has been found that the radiation resistance of this material depends on the morphology and phase composition at its surface. It is shown that, as the temperature of annealing is increased, aggregations with predominant content of PbS grow; simultaneously, the composition of these aggregations varies as a consequence of the reaction of substitution of sulfur atoms with oxygen atoms. The latter of the aforementioned processes brings about a decrease in the radiation resistance of the heterophase photosensitive material CdS-PbS, which is accounted for by a decrease in the gettering due to appearance of an intermediate oxidized layer between PbS and CdS. An increase in the sizes and number of spherical aggregations at the surface, which consist of crystallites with predominant content of PbS, brings about an increase in the radiation resistance.

Edge chipping and flexural resistance of monolithic ceramics☆

Science.gov (United States)

Zhang, Yu; Lee, James J.-W.; Srikanth, Ramanathan; Lawn, Brian R.

2014-01-01

Objective Test the hypothesis that monolithic ceramics can be developed with combined esthetics and superior fracture resistance to circumvent processing and performance drawbacks of traditional all-ceramic crowns and fixed-dental-prostheses consisting of a hard and strong core with an esthetic porcelain veneer. Specifically, to demonstrate that monolithic prostheses can be produced with a much reduced susceptibility to fracture. Methods Protocols were applied for quantifying resistance to chipping as well as resistance to flexural failure in two classes of dental ceramic, microstructurally-modified zirconias and lithium disilicate glass–ceramics. A sharp indenter was used to induce chips near the edges of flat-layer specimens, and the results compared with predictions from a critical load equation. The critical loads required to produce cementation surface failure in monolithic specimens bonded to dentin were computed from established flexural strength relations and the predictions validated with experimental data. Results Monolithic zirconias have superior chipping and flexural fracture resistance relative to their veneered counterparts. While they have superior esthetics, glass–ceramics exhibit lower strength but higher chip fracture resistance relative to porcelain-veneered zirconias. Significance The study suggests a promising future for new and improved monolithic ceramic restorations, with combined durability and acceptable esthetics. PMID:24139756

Numerical Simulations of Scattering of Light from Two-Dimensional Rough Surfaces Using the Reduced Rayleigh Equation

Directory of Open Access Journals (Sweden)

Tor eNordam

2013-09-01

Full Text Available A formalism is introduced for the non-perturbative, purely numerical, solution of the reduced Rayleigh equation for the scattering of light from two-dimensional penetrable rough surfaces. Implementation and performance issues of the method, and various consistency checks of it, are presented and discussed. The proposed method is found, within the validity of the Rayleigh hypothesis, to give reliable results. For a non-absorbing metal surface the conservation of energy was explicitly checked, and found to be satisfied to within 0.03%, or better, for the parameters assumed. This testifies to the accuracy of the approach and a satisfactory discretization. As an illustration, we calculate the full angular distribution of the mean differential reflection coefficient for the scattering of p- or s-polarized light incident on two-dimensional dielectric or metallic randomly rough surfaces defined by (isotropic or anisotropic Gaussian and cylindrical power spectra. Simulation results obtained by the proposed method agree well with experimentally measured scattering data taken from similar well-characterized, rough metal samples, or to results obtained by other numerical methods.

On the Basic Equations of the Magnetostatics

Directory of Open Access Journals (Sweden)

A. M. Makarov

2016-01-01

Full Text Available The paper studies the physical relationship between the main objects of the magnetic field in a continuous medium with magnetization effects. Consistently considers the following hypotheses: a hypothesis of the primacy and the physical reality of the magnetization vector field environment, a similar hypothesis about the real existence of Ampere currents (molecular currents, magnetization currents, a hypothesis of a magnetic dipole moment of the medium volume element in view of bulk density of electric currents in this volume. A more rigorous derivation of the basic differential equations of magnetostatics from the Biot-Savart-Laplace equation is proposed.The well-known works justifying basic equations of magnetostatics use a procedure wherein when proving the local differential ratio is used a transformation of some volume integral to the surface integral bounding this volume. Thus, there is a specific way to select a closed surface that is either a surface in a vacuum (beyond the medium volume under consideration, or a surface of the conductor (a normal component of currents to the surface, here, becomes zero. In the paper the control surface is arbitrarily carried out within the volume of the medium under consideration, thereby leading to the mathematically sound result.The paper analyzes the hypotheses listed above. The main feature of analysis is a succesively using concept of bilateralism surface bounding the medium volume of the arbitrary finite dimensions. The analysis allowed us to reveal the physical adequacy of the considered hypotheses, derive the appropriate differential equations for the basic vector fields of magnetostatics and obtain a new condition. The resulting condition for the closedness of magnetization currents is recorded in entire compliance with the well-known Gauss electrostatic law, which avoids the need for additional, but not always reasonable assumptions.

Quasisymmetry equations for conventional stellarators

International Nuclear Information System (INIS)

Pustovitov, V.D.

1994-11-01

General quasisymmetry condition, which demands the independence of B 2 on one of the angular Boozer coordinates, is reduced to two equations containing only geometrical characteristics and helical field of a stellarator. The analysis is performed for conventional stellarators with a planar circular axis using standard stellarator expansion. As a basis, the invariant quasisymmetry condition is used. The quasisymmetry equations for stellarators are obtained from this condition also in an invariant form. Simplified analogs of these equations are given for the case when averaged magnetic surfaces are circular shifted torii. It is shown that quasisymmetry condition can be satisfied, in principle, in a conventional stellarator by a proper choice of two satellite harmonics of the helical field in addition to the main harmonic. Besides, there appears a restriction on the shift of magnetic surfaces. Thus, in general, the problem is closely related with that of self-consistent description of a configuration. (author)

Sun's pole-equator flux differences

Energy Technology Data Exchange (ETDEWEB)

Belvedere, G [Istituto di Astronomia dell' Universita di Catania, Italy; Paterno, L [Osservatorio Astrofisico di Catania, Italy

1977-04-01

The possibility that large flux differences between the poles and the equator at the bottom of the solar convective zone are compatible with the small differences observed at the surface is studied. The consequences of increasing the depth of the convective zone due to overshooting are explored. A Boussinesq model is used for the convective zone and it is assumed that the interaction of the global convection with rotation is modelled through a convective flux coefficient whose perturbed part is proportional to the local Taylor number. The numerical integration of the equations of motion and energy shows that coexistence between large pole-equator flux differences at the bottom and small ones at the surface is possible if the solar convective zone extends to a depth of 0.4 R(Sun). The angular velocity distribution inside the convective zone is in agreement with the ..cap alpha omega..-dynamo theories of the solar cycle.

An Equal-Strain Analytical Solution for the Radial Consolidation of Unsaturated Soils by Vertical Drains considering Drain Resistance

Directory of Open Access Journals (Sweden)

Feng Zhou

2018-01-01

Full Text Available Developing an analytical solution for the consolidation of unsaturated soils remains a challenging task due to the complexity of coupled governing equations for air and water phases. This paper presents an equal-strain model for the radial consolidation of unsaturated soils by vertical drains, and the effect of drain resistance is also considered. Simplified governing equations are established, and an analytical solution to calculate the excess pore-air and pore-water pressures is derived by using the methods of matrix analysis and eigenfunction expansion. The average degrees of consolidation for air and water phases and the ground surface settlement are also given. The solutions of the equal-strain model are verified by comparing the proposed free-strain model with the equal-strain model, and reasonably good agreement is obtained. Moreover, parametric studies regarding the drain resistance effect are graphically presented.

Improving the tribocorrosion resistance of Ti6Al4V surface by laser surface cladding with TiNiZrO2 composite coating

Science.gov (United States)

Obadele, Babatunde Abiodun; Andrews, Anthony; Mathew, Mathew T.; Olubambi, Peter Apata; Pityana, Sisa

2015-08-01

Ti6Al4V alloy was laser cladded with titanium, nickel and zirconia powders in different ratio using a 2 kW CW ytterbium laser system (YLS). The microstructures of the cladded layers were examined using field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Corrosion and tribocorrosion tests were performed on the cladded surface in 1 M H2SO4 solution. The microstructure revealed the transformation from a dense dendritic structure in TiNi coating to a flower-like structure observed in TiNiZrO2 cladded layers. There was a significant increase in surface microindentation hardness values of the cladded layers due to the present of hard phase ZrO2 particles. The results obtained show that addition of ZrO2 improves the corrosion resistance property of TiNi coating but decrease the tribocorrosion resistance property. The surface hardening effect induced by ZrO2 addition, combination of high hardness of Ti2Ni phase could be responsible for the mechanical degradation and chemical wear under sliding conditions.

Method of determination of temperature and heat resistance of the points on the integrated circuit crystal surface

Directory of Open Access Journals (Sweden)

Popov V. M.

2011-12-01

Full Text Available Method for visualization of integrated circuit (IC surface temperature by means of the liquid crystal film deposited from solution on its surface is proposed. The boundaries of local regions represent isotherms with corresponding phase transitions. On the base of isotherms positions and consumed by IC power thermal resistances between crystal and environment are determined.

The one-parameter-model - a constitutive equation applied to a heat resistant alloy

International Nuclear Information System (INIS)

Schwarze, E.; Schuster, H.; Nickel, H.

1992-01-01

In the present work a constitutive model earlier developed and used to predict experimental results of hot tests and fatigue tests from creep experiments of metallic materials were modified to comply with the properties of a high temperature resistant material. The improved model accounts for the properties of a material developing a density and a structure of dislocation lines which are capable of interactions with particles (carbides) from a second phase. The time and temperature dependent evolution of the carbide structure has been described by an equation which explains the formation of seeds as well as their growths (Ostwald ripening). The extended model was applied to Incoloy 800H which is known to develop a carbide structure. Therefore hot tensile and fatigue tests, creep and relaxation experiments using the heats ADU and BAK (KFA specifications) at temperature between 800deg C and 900deg C were performed including both solution treated specimens and specimens heat treated for 10, 100 and 1000 hours. As compared with the results from tensile tests where the carbide structures play a subordinated role, alternately, these structures have a decisive influence on the creep properties of specimens during the primary creep phase, i.e. low stresses and high temperatures. (orig.) [de

A Surface Temperature Initiated Closure (STIC) for surface energy balance fluxes

DEFF Research Database (Denmark)

Mallick, Kaniska; Jarvis, Andrew J.; Boegh, Eva

2014-01-01

The use of Penman–Monteith (PM) equation in thermal remote sensing based surface energy balance modeling is not prevalent due to the unavailability of any direct method to integrate thermal data into the PM equation and due to the lack of physical models expressing the surface (or stomatal......) and boundary layer conductances (gS and gB) as a function of surface temperature. Here we demonstrate a new method that physically integrates the radiometric surface temperature (TS) into the PM equation for estimating the terrestrial surface energy balance fluxes (sensible heat, H and latent heat, λ......E). The method combines satellite TS data with standard energy balance closure models in order to derive a hybrid closure that does not require the specification of surface to atmosphere conductance terms. We call this the Surface Temperature Initiated Closure (STIC), which is formed by the simultaneous solution...

Resistivity and Seismic Surface Wave Tomography Results for the Nevşehir Kale Region: Cappadocia, Turkey

Science.gov (United States)

Coşkun, Nart; Çakır, Özcan; Erduran, Murat; Arif Kutlu, Yusuf

2014-05-01

The Nevşehir Kale region located in the middle of Cappadocia with approximately cone shape is investigated for existence of an underground city using the geophysical methods of electrical resistivity and seismic surface wave tomography together. Underground cities are generally known to exist in Cappadocia. The current study has obtained important clues that there may be another one under the Nevşehir Kale region. Two-dimensional resistivity and seismic profiles approximately 4-km long surrounding the Nevşehir Kale are measured to determine the distribution of electrical resistivities and seismic velocities under the profiles. Several high resistivity anomalies with a depth range 8-20 m are discovered to associate with a systematic void structure beneath the region. Because of the high resolution resistivity measurement system currently employed we were able to isolate the void structure from the embedding structure. Low seismic velocity zones associated with the high resistivity depths are also discovered. Using three-dimensional visualization techniques we show the extension of the void structure under the measured profiles.

Effect of swift heavy ion irradiation on surface resistance of DyBa 2

Indian Academy of Sciences (India)

We report the observation of a pronounced peak in surface resistance at microwave frequencies of 4.88 GHz and 9.55 GHz and its disappearance after irradiation with swift ions in laser ablated DyBa2Cu3O7- (DBCO) thin films. The measurements were carried out in zero field as well as in the presence of magnetic fields ...

Investigation of the magnetic neutral line region with the frame of two-fluid equations: A possibility of anomalous resistivity inferred from MMS observations

Science.gov (United States)

Kobayashi, Y.; Kitamura, N.; Ieda, A.; Yoshizumi, M.; Imada, S.; Tsugawa, Y.; Burch, J. L.; Russell, C. T.; Moore, T. E.; Giles, B. L.; Paterson, W.; Torbert, R. B.; Ergun, R.; Saito, Y.; Yokota, S.; Machida, S.

2017-12-01

Magnetic reconnection is a basic physical process by which energy of magnetic field is converted into the kinetic energy of plasmas. In recent years, MMS missionconsisting of four spacecraft has been conducted aiming at elucidating the physical mechanism of merging themagnetic fields in the vicinity of the magnetic neutral linethat exists in the central part of the structure. In this paper, we examine the magnetic field frozen-in relation near the magnetic neutral line as well as the causal relationship between electron and ion dynamics in the frame of two fluid equations.Theoretically, it is shown that electrons are frozen-in to the magnetic fields while ion's frozen-in relation is broken in the ion dissipation region. However, when we examined the observational data around 1307 UT on October 16, 2015 when MMS spacecraft passed through the vicinity of the magnetic neutral line [Burch et al., Science 2016] , it was confirmed that the frozen-ion relation was not established for electrons in the ion dissipation region. In addition, we found that intense wave electric fields in this region. From the spectral analysis of the waves, it turned out that their characteristic frequencies are the lower-hybrid and electron cyclotron frequencies.In the framework of the two-fluid equation, we can evaluate the values of each term of the equations of motion for both ions and electrons except for the collision term from MMS spacecraft data. Therefore, it is possible to obtain collision terms for both species. Since magnetospheric plasma is basically collisionless, it is considered that the collision term is due to anomalous resistivity associated with the excited waves . On the other hand, in the two-fluid equation system, the two vectors corresponding to the collision terms of ions and electrons have the same absolute value. Because the force exerted between the two is the internal force, they should face in the opposite direction. However, the vectors corresponding to the

Strong Control of Salts on Near Surface Liquid Water Content in a High Polar Desert Indicated by Near Surface Resistivity Mapping with a Helicopter-Borne TEM Sensor, Lower Taylor Valley, Antarctica

Science.gov (United States)

Foley, N.; Tulaczyk, S. M.; Auken, E.; Mikucki, J.; Myers, K. F.; Dugan, H.; Doran, P. T.; Virginia, R. A.

2016-12-01

Closed depressions in the Lower Taylor Valley (McMurdo Dry Valleys, Antarctica) have near surface (top 5m) electrical resistivity that is lower by about an order of magnitude than the resistivity of nearby slopes and ridges (100s of ohm-m vs. 1000s). We interpret this spatial pattern as being due to long term concentration of salts carried by liquid water and/or deliquescent vapor fronts. High concentration of salts in the top decimeters to meters beneath the surface may prolong the existence and abundance of liquid water in this otherwise very cold and dry high polar desert. Due to its connections with life and chemical transport, liquid water is a much studied feature in the McMurdo Dry Valleys. This setting can be used as an analogue for similar features on the surface of Mars, where liquid water tracks have been observed and are believed to be controlled by eutectic brines. Our study demonstrates the utility of mapping at a regional scale via helicopter-borne Transient EM. Airborne EM covers more ground and can measure deeper than surface-based measurements, at the expense of resolution. This allows creating valley-scale datasets which could not feasibly be collected on the ground. Our remote measurements complement physical samples that indicate that soluble salts concentrate in certain areas of surface soil where water moves ions and is later removed by evaporation or sublimation. In areas where we measured low resistivity, the integrated liquid water fraction in the top 5m may be a few to several percent by volume, equivalent to a few or several dozens of cm of water layer thickness. This estimate assumes that the interstitial waters have very low resistivity, comparable to seawater or hypersaline brines at freezing (0.2-0.35 ohm-m). If soil water was considerably fresher than this, liquid water content would have to reach dozens of percent throughout the top 5m for bulk resistivities to drop to 100s of ohm-m. We consider the latter case to be unlikely as

Boussinesq evolution equations

DEFF Research Database (Denmark)

Bredmose, Henrik; Schaffer, H.; Madsen, Per A.

2004-01-01

This paper deals with the possibility of using methods and ideas from time domain Boussinesq formulations in the corresponding frequency domain formulations. We term such frequency domain models "evolution equations". First, we demonstrate that the numerical efficiency of the deterministic...... Boussinesq evolution equations of Madsen and Sorensen [Madsen, P.A., Sorensen, O.R., 1993. Bound waves and triad interactions in shallow water. Ocean Eng. 20 359-388] can be improved by using Fast Fourier Transforms to evaluate the nonlinear terms. For a practical example of irregular waves propagating over...... a submerged bar, it is demonstrated that evolution equations utilising FFT can be solved around 100 times faster than the corresponding time domain model. Use of FFT provides an efficient bridge between the frequency domain and the time domain. We utilise this by adapting the surface roller model for wave...

Optimizing thermal shock resistance of layered refractories

Energy Technology Data Exchange (ETDEWEB)

Hein, Jarno; Kuna, Meinhard [Institute of Mechanics and Fluid Dynamics, Technical University Bergakademie Freiberg, Lampadiusstrasse 4, 09599 Freiberg (Germany)

2012-06-15

Severe thermal shocks may cause critical thermal stresses and failure in refractories or ceramic materials. To increase the thermal shock resistance, layered material structures are suggested. In order to optimize properties of these alternative structures, thermo-mechanical simulations are required. In this study, a finite difference method (FDM) is used for solving the partial differential equation of heat conduction with spatially varying parameters. The optimization of the strip's thermal shock resistance is exemplarily done on a 10 layered strip subjected to constant temperature jump on the top surface. Each layer can be set with different porous Al{sub 2}O{sub 3} and MgO ceramics, whose material properties are theoretically determined. In this study, an improved optimization method is developed that consists of a combination and sequence of Monte Carlo simulations and evolution strategies to overcome certain disadvantages of both techniques. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

KAUST Repository

Almuhammadi, Khaled Hamdan; Lubineau, Gilles; Alfano, Marco Francesco; Buttner, Ulrich

2016-01-01

Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a

Grafting of phosphorylcholine functional groups on polycarbonate urethane surface for resisting platelet adhesion

Energy Technology Data Exchange (ETDEWEB)

Gao, Bin [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@hotmail.com [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China); Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Lu, Jian; Zhang, Li; Zhao, Miao; Shi, Changcan; Khan, Musammir [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Guo, Jintang [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China)

2013-07-01

In order to improve the resistance of platelet adhesion on material surface, 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto polycarbonate urethane (PCU) surface via Michael reaction to create biomimetic structure. After introducing primary amine groups via coupling tris(2-aminoethyl)amine (TAEA) onto the polymer surface, the double bond of MPC reacted with the amino group to obtain MPC modified PCU. The modified surface was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results verified that MPC was grafted onto PCU surface by Michael reaction method. The MPC grafted PCU surface had a low water contact angle and a high water uptake. This means that the hydrophilic PC functional groups improved the surface hydrophilicity significantly. In addition, surface morphology of MPC grafted PCU film was imaged by atomic force microscope (AFM). The results showed that the grafted surface was rougher than the blank PCU surface. In addition, platelet adhesion study was evaluated by scanning electron microscopy (SEM) observation. The PCU films after treated with platelet-rich plasma demonstrated that much fewer platelets adhered to the MPC-grafted PCU surface than to the blank PCU surface. The antithrombogenicity of the MPC-grafted PCU surface was determined by the activated partial thromboplastin time (APTT). The result suggested that the MPC modified PCU may have potential application as biomaterials in blood-contacting and some subcutaneously implanted devices. - Highlights: • MPC was successfully grafted onto polycarbonate urethane surface via Michael reaction. • High concentration of PC functional groups on the surface via TAEA molecule • Biomimetic surface modification • The modified surface showed high hydrophilicity and anti-platelet adhesion.

Influence of desiccation procedures on the surface wettability and corrosion resistance of porous aluminium anodic oxide films

Energy Technology Data Exchange (ETDEWEB)

Zheng Meng, E-mail: ZhengMeng@eng.hokudai.ac.jp [Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-Ku, Sapporo 060-8628 (Japan); Sakairi, Masatoshi [Faculty of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-Ku, Sapporo 060-8628 (Japan); Jha, Himendra [Technische Universitaet Muenchen, Lichtenbergstrasse 4, D-85748 Garching (Germany)

2012-02-15

Highlights: Black-Right-Pointing-Pointer Simple desiccation treatment without coating or etching produces hydrophobicity of porous anodic oxide film. Black-Right-Pointing-Pointer Treatment time can be shortened by controlling desiccation condition. Black-Right-Pointing-Pointer Surface microstructure is the key point to determine the wettability. Black-Right-Pointing-Pointer The hydrophobic surfaces show better corrosion resistance than oxide aluminium. - Abstract: A hydrophobic oxide film was formed on aluminium by anodizing followed by desiccation treatment. Films subjected to gradual heating and cooling exhibit larger water contact angles than samples exposed to fast heating and cooling at the same temperature. From SEM and Auger Electron Spectroscopic observations, the low wettability surface shows a regular porous morphology with no significant chemical composition differences due to the different treatments. The desiccation process improves the corrosion resistance, shown by immersion in NaCl. The change in morphology by the desiccation processes is considered a main reason to lower the wettability, which further affects the corrosion properties.

A composite velocity procedure for the compressible Navier-Stokes equations

Science.gov (United States)

Khosla, P. K.; Rubin, S. G.

1982-01-01

A new boundary-layer relaxation procedure is presented. In the spirit of the theory of matched asymptotic expansions, a multiplicative composite of the appropriate velocity representations for the inviscid and viscous regions is prescribed. The resulting equations are structured so that far from the surface of the body the momentum equations lead to the Bernoulli relation for the pressure, while the continuity equation reduces to the familiar compressible potential equation. Close to the body surface, the governing equations and solution techniques are characteristic of those describing interacting boundary-layers; although, the full Navier-Stokes equations are considered here. Laminar flow calculations for the subsonic flow over an axisymmetric boattail simulator geometry are presented for a variety of Reynolds and Mach numbers. A strongly implicit solution method is applied for the coupled velocity components.

Synergistic Effect of Superhydrophobicity and Oxidized Layers on Corrosion Resistance of Aluminum Alloy Surface Textured by Nanosecond Laser Treatment.

Science.gov (United States)

Boinovich, Ludmila B; Emelyanenko, Alexandre M; Modestov, Alexander D; Domantovsky, Alexandr G; Emelyanenko, Kirill A

2015-09-02

We report a new efficient method for fabricating a superhydrophobic oxidized surface of aluminum alloys with enhanced resistance to pitting corrosion in sodium chloride solutions. The developed coatings are considered very prospective materials for the automotive industry, shipbuilding, aviation, construction, and medicine. The method is based on nanosecond laser treatment of the surface followed by chemisorption of a hydrophobic agent to achieve the superhydrophobic state of the alloy surface. We have shown that the surface texturing used to fabricate multimodal roughness of the surface may be simultaneously used for modifying the physicochemical properties of the thick surface layer of the substrate itself. Electrochemical and wetting experiments demonstrated that the superhydrophobic state of the metal surface inhibits corrosion processes in chloride solutions for a few days. However, during long-term contact of a superhydrophobic coating with a solution, the wetted area of the coating is subjected to corrosion processes due to the formation of defects. In contrast, the combination of an oxide layer with good barrier properties and the superhydrophobic state of the coating provides remarkable corrosion resistance. The mechanisms for enhancing corrosion protective properties are discussed.

Numerical method for the eigenvalue problem and the singular equation by using the multi-grid method and application to ordinary differential equation

International Nuclear Information System (INIS)

Kanki, Takashi; Uyama, Tadao; Tokuda, Shinji.

1995-07-01

In the numerical method to compute the matching data which are necessary for resistive MHD stability analyses, it is required to solve the eigenvalue problem and the associated singular equation. An iterative method is developed to solve the eigenvalue problem and the singular equation. In this method, the eigenvalue problem is replaced with an equivalent nonlinear equation and a singular equation is derived from Newton's method for the nonlinear equation. The multi-grid method (MGM), a high speed iterative method, can be applied to this method. The convergence of the eigenvalue and the eigenvector, and the CPU time in this method are investigated for a model equation. It is confirmed from the numerical results that this method is effective for solving the eigenvalue problem and the singular equation with numerical stability and high accuracy. It is shown by improving the MGM that the CPU time for this method is 50 times shorter than that of the direct method. (author)

Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

Energy Technology Data Exchange (ETDEWEB)

Pawel, Steven J [ORNL; Hsu, Julia [Massachusetts Institute of Technology (MIT)

2010-11-01

The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.

AUTOJOM, Quadratic Equation Coefficient for Conic Volume, Parallelepipeds, Wedges, Pyramids. JOMREAD, Check of 3-D Geometry Structure from Quadratic Surfaces

International Nuclear Information System (INIS)

2005-01-01

Nature of physical problem solved: AUTOJOM is a computer program that will generate the coefficients of any quadratic equation used to define conic volumes and also the coefficients of the planes needed to define parallelepipeds, wedges, and pyramids. JOMREAD is a computer code to check any 3D geometry composed of and constructed with quadratic surfaces

Effects of Thermal Resistance on One-Dimensional Thermal Analysis of the Epidermal Flexible Electronic Devices Integrated with Human Skin

Science.gov (United States)

Li, He; Cui, Yun

2017-12-01

Nowadays, flexible electronic devices are increasingly used in direct contact with human skin to monitor the real-time health of human body. Based on the Fourier heat conduction equation and Pennes bio-heat transfer equation, this paper deduces the analytical solutions of one - dimensional heat transfer for flexible electronic devices integrated with human skin under the condition of a constant power. The influence of contact thermal resistance between devices and skin is considered as well. The corresponding finite element model is established to verify the correctness of analytical solutions. The results show that the finite element analysis agrees well with the analytical solution. With bigger thermal resistance, temperature increase of skin surface will decrease. This result can provide guidance for the design of flexible electronic devices to reduce the negative impact that exceeding temperature leave on human skin.

On Dust Charging Equation

OpenAIRE

Tsintsadze, Nodar L.; Tsintsadze, Levan N.

2008-01-01

A general derivation of the charging equation of a dust grain is presented, and indicated where and when it can be used. A problem of linear fluctuations of charges on the surface of the dust grain is discussed.

Development of a High Slip-resistant Footwear Outsole Using a Hybrid Rubber Surface Pattern

Science.gov (United States)

YAMAGUCHI, Takeshi; HOKKIRIGAWA, Kazuo

2014-01-01

Abstract: The present study examined whether a new footwear outsole with tread blocks and a hybrid rubber surface pattern, composed of rough and smooth surfaces, could increase slip resistance and reduce the risk of fall while walking on a wet floor surface. A drag test was performed to measure static and dynamic coefficient of friction (SCOF and DCOF, respectively) values for the footwear with the hybrid rubber surface pattern outsole and two types of commercially available boots that are conventionally used in food factories and restaurant kitchens with respect to a stainless steel floor covered with glycerol solution. Gait trials were conducted with 14 participants who wore the footwear on the wet stainless steel floor. The drag test results indicated that the hybrid rubber surface pattern sole exhibited higher SCOF (≥0.44) and DCOF (≥0.39) values than the soles of the comparative footwear (pfootwear with the hybrid rubber surface pattern outsole were significantly lower than those for the comparative footwear, which resulted in no falls during trials. PMID:25055846

Boundary Shape Control of the Navier-Stokes Equations and Applications

Institute of Scientific and Technical Information of China (English)

Kaitai LI; Jian SU; Aixiang HUANG

2010-01-01

In this paper,the geometrical design for the blade's surface(s)in an impeller or for the profile of an aircraft,is modeled from the mathematical point of view by a boundary shape control problem for the Navier-Stokes equations.The objective function is the sum of a global dissipative function and the power of the fluid.The control variables are the geometry of the boundary and the state equations are the Navier-Stokes equations.The Euler-Lagrange equations of the optimal control problem are derived,which are an elliptic boundary value system of fourth order,coupled with the Navier-Stokes equations.The authors also prove the existence of the solution of the optimal control problem,the existence of the solution of the Navier-Stokes equations with mixed boundary conditions,the weak continuity of the solution of the Navier-Stokes equations with respect to the geometry shape of the blade's surface and the existence of solutions of the equations for the G(a)teaux derivative of the solution of the Navier-Stokes equations with respect to the geometry of the boundary.

Inductance and resistance measurement method for vessel detection and coil powering in all-surface inductive heating systems composed of outer squircle coils

Science.gov (United States)

Kilic, Veli Tayfun; Unal, Emre; Demir, Hilmi Volkan

2017-05-01

In this work, we investigate a method proposed for vessel detection and coil powering in an all-surface inductive heating system composed of outer squircle coils. Besides conventional circular coils, coils with different shapes such as outer squircle coils are used for and enable efficient all-surface inductive heating. Validity of the method, which relies on measuring inductance and resistance values of a loaded coil at different frequencies, is experimentally demonstrated for a coil with shape different from conventional circular coil. Simple setup was constructed with a small coil to model an all-surface inductive heating system. Inductance and resistance maps were generated by measuring coil's inductance and resistance values at different frequencies loaded by a plate made of different materials and located at various positions. Results show that in an induction hob for various coil geometries it is possible to detect a vessel's presence, to identify its material type and to specify its position on the hob surface by considering inductance and resistance of the coil measured on at least two different frequencies. The studied method is important in terms of enabling safe, efficient and user flexible heating in an all-surface inductive heating system by automatically detecting the vessel's presence and powering on only the coils that are loaded by the vessel with predetermined current levels.

Traffic accidents and road surface skidding resistance : an investigation into the statistical relationship between the skidding resistance of the road surface and relative road risk. Summary of the research report of Sub-committee V of the Working Group on Tyres, Road Surfaces and Skidding Accidents of the Institute for Road Safety Research, SWOV

NARCIS (Netherlands)

Schlösser, L.H.M

1975-01-01

This study forms part of an extended research programme of the Working Group on Tyres, Road-surfaces and Skidding accidents. According to the terms of reference a statistical relationship had to be established between the skidding resistance of a road-surface and the number of accidents per million

Reduced, three-dimensional, nonlinear equations for high-β plasmas including toroidal effects

International Nuclear Information System (INIS)

Schmalz, R.

1980-11-01

The resistive MHD equations for toroidal plasma configurations are reduced by expanding to the second order in epsilon, the inverse aspect ratio, allowing for high β = μsub(o)p/B 2 of order epsilon. The result is a closed system of nonlinear, three-dimensional equations where the fast magnetohydrodynamic time scale is eliminated. In particular, the equation for the toroidal velocity remains decoupled. (orig.)

Facile fabrication of superhydrophobic surface with excellent mechanical abrasion and corrosion resistance on copper substrate by a novel method.

Science.gov (United States)

Su, Fenghua; Yao, Kai

2014-06-11

A novel method for controllable fabrication of a superhydrophobic surface with a water contact angle of 162 ± 1° and a sliding angle of 3 ± 0.5° on copper substrate is reported in this Research Article. The facile and low-cost fabrication process is composed from the electrodeposition in traditional Watts bath and the heat-treatment in the presence of (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane (AC-FAS). The superhydrophobicity of the fabricated surface results from its pine-cone-like hierarchical micro-nanostructure and the assembly of low-surface-energy fluorinated components on it. The superhydrophobic surface exhibits high microhardness and excellent mechanical abrasion resistance because it maintains superhydrophobicity after mechanical abrasion against 800 grit SiC sandpaper for 1.0 m at the applied pressure of 4.80 kPa. Moreover, the superhydrophobic surface has good chemical stability in both acidic and alkaline environments. The potentiodynamic polarization and electrochemical impedance spectroscopy test shows that the as-prepared superhydrophobic surface has excellent corrosion resistance that can provide effective protection for the bare Cu substrate. In addition, the as-prepared superhydrophobic surface has self-cleaning ability. It is believed that the facile and low-cost method offer an effective strategy and promising industrial applications for fabricating superhydrophobic surfaces on various metallic materials.

Effect of surface fields on the dynamic resistance of planar HgCdTe mid-wavelength infrared photodiodes

Energy Technology Data Exchange (ETDEWEB)

He, Kai; Wang, Xi; Zhang, Peng; Chen, Yi-Yu [Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhou, Song-Min; Xie, Xiao-Hui; Lin, Chun, E-mail: chun-lin@mail.sitp.ac.cn; Ye, Zhen-Hua; Wang, Jian-Xin; Zhang, Qin-Yao, E-mail: qinyao@mail.sitp.ac.cn [Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Li, Yang [Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2015-05-28

This work investigates the effect of surface fields on the dynamic resistance of a planar HgCdTe mid-wavelength infrared photodiode from both theoretical and experimental aspects, considering a gated n-on-p diode with the surface potential of its p-region modulated. Theoretical models of the surface leakage current are developed, where the surface tunnelling current in the case of accumulation is expressed by modifying the formulation of bulk tunnelling currents, and the surface channel current for strong inversion is simulated with a transmission line method. Experimental data from the fabricated devices show a flat-band voltage of V{sub FB}=−5.7 V by capacitance-voltage measurement, and then the physical parameters for bulk properties are determined from the resistance-voltage characteristics of the diode working at a flat-band gate voltage. With proper values of the modeling parameters such as surface trap density and channel electron mobility, the theoretical R{sub 0}A product and corresponding dark current calculated from the proposed model as functions of the gate voltage V{sub g} demonstrate good consistency with the measured values. The R{sub 0}A product remarkably degenerates when V{sub g} is far below or above V{sub FB} because of the surface tunnelling current or channel current, respectively; and it attains the maximum value of 5.7×10{sup 7} Ω · cm{sup 2} around the transition between surface depletion and weak inversion when V{sub g}≈−4 V, which might result from reduced generation-recombination current.

Analysis of the dual phase lag bio-heat transfer equation with constant and time-dependent heat flux conditions on skin surface

Directory of Open Access Journals (Sweden)

Ziaei Poor Hamed

2016-01-01

Full Text Available This article focuses on temperature response of skin tissue due to time-dependent surface heat fluxes. Analytical solution is constructed for DPL bio-heat transfer equation with constant, periodic and pulse train heat flux conditions on skin surface. Separation of variables and Duhamel’s theorem for a skin tissue as a finite domain are employed. The transient temperature responses for constant and time-dependent boundary conditions are obtained and discussed. The results show that there is major discrepancy between the predicted temperature of parabolic (Pennes bio-heat transfer, hyperbolic (thermal wave and DPL bio-heat transfer models when high heat flux accidents on the skin surface with a short duration or propagation speed of thermal wave is finite. The results illustrate that the DPL model reduces to the hyperbolic model when τT approaches zero and the classic Fourier model when both thermal relaxations approach zero. However for τq = τT the DPL model anticipates different temperature distribution with that predicted by the Pennes model. Such discrepancy is due to the blood perfusion term in energy equation. It is in contrast to results from the literature for pure conduction material, where the DPL model approaches the Fourier heat conduction model when τq = τT . The burn injury is also investigated.

Calibration of region-specific gates equation for LRFD.

Science.gov (United States)

2014-02-01

The objectives of this research are to recalibrate the FHWA-modi ed Gates equation : and update the associated LRFD resistance factor for pile types and local soil conditions : encountered in Louisiana. This research is consistent with FHWA recomm...

On computation of relaxation constant α in Landau–Lifshitz–Gilbert equation

Energy Technology Data Exchange (ETDEWEB)

Gladkov, Serguey, E-mail: sglad@newmail.ru; Bogdanova, Sofiya, E-mail: sonjaf@list.ru

2014-11-15

Due to the quasi-classical kinetic equation (QKE) for the magnon distribution function to calculate the velocity of the domain wall motion V in magnetic fields H>H{sub a}, where H{sub a}− magnetic anisotropy field. Based on the comparison of this formula for Vthe analytic expression of relaxation constant α in Landau–Lifshitz–Gilbert equation was found. We used the detected correlation between the system's entropy and the environment's resistance force, and obtained an expression for the spin-lattice braking force that is applied to the moving domain wall. We calculated the mobility ratio of the domain wall. - Highlights: • The resistance force acting on the domain wall was calculated. • Mobility coefficient of domain wall was calculated. • The strict calculation of relaxation constant in equation Landau-Lifshitz- Gilbert.

Dependence of trapped-flux-induced surface resistance of a large-grain Nb superconducting radio-frequency cavity on spatial temperature gradient during cooldown through Tc

Science.gov (United States)

Huang, Shichun; Kubo, Takayuki; Geng, R. L.

2016-08-01

Recent studies by Romanenko et al. revealed that cooling down a superconducting cavity under a large spatial temperature gradient decreases the amount of trapped flux and leads to reduction of the residual surface resistance. In the present paper, the flux expulsion ratio and the trapped-flux-induced surface resistance of a large-grain cavity cooled down under a spatial temperature gradient up to 80 K /m are studied under various applied magnetic fields from 5 to 20 μ T . We show the flux expulsion ratio improves as the spatial temperature gradient increases, independent of the applied magnetic field: our results support and enforce the previous studies. We then analyze all rf measurement results obtained under different applied magnetic fields together by plotting the trapped-flux-induced surface resistance normalized by the applied magnetic field as a function of the spatial temperature gradient. All the data can be fitted by a single curve, which defines an empirical formula for the trapped-flux-induced surface resistance as a function of the spatial temperature gradient and applied magnetic field. The formula can fit not only the present results but also those obtained by Romanenko et al. previously. The sensitivity rfl of surface resistance from trapped magnetic flux of fine-grain and large-grain niobium cavities and the origin of d T /d s dependence of Rfl/Ba are also discussed.

Fabricating superhydrophobic polymer surfaces with excellent abrasion resistance by a simple lamination templating method.

Science.gov (United States)

Xu, Qian Feng; Mondal, Bikash; Lyons, Alan M

2011-09-01

Fabricating robust superhydrophobic surfaces for commercial applications is challenging as the fine-scale surface features, necessary to achieve superhydrophobicity, are susceptible to mechanical damage. Herein, we report a simple and inexpensive lamination templating method to create superhydrophobic polymer surfaces with excellent abrasion resistance and water pressure stability. To fabricate the surfaces, polyethylene films were laminated against woven wire mesh templates. After cooling, the mesh was peeled from the polymer creating a 3D array of ordered polymer microposts on the polymer surface. The resulting texture is monolithic with the polymer film and requires no chemical modification to exhibit superhydrophobicity. By controlling lamination parameters and mesh dimensions, polyethylene surfaces were fabricated that exhibit static contact angles of 160° and slip angles of 5°. Chemical and mechanical stability was evaluated using an array of manual tests as well as a standard reciprocating abraser test. Surfaces remained superhydrophobic after more than 5500 abrasion cycles at a pressure of 32.0 kPa. In addition, the surface remains dry after immersing into water for 5 h at 55 kPa. This method is environmental friendly, as it employs no solvents or harsh chemicals and may provide an economically viable path to manufacture large areas of mechanically robust superhydrophobic surfaces from inexpensive polymers and reusable templates.

On a Linear Equation Arising in Isometric Embedding of Torus-like Surface

Institute of Scientific and Technical Information of China (English)

Chunhe LI

2009-01-01

The solvability of a linear equation and the regularity of the solution are discussed.The equation is arising in a geometric problem which is concerned with the realization of Alexandroff's positive annul in R3.

Moderate temperature-dependent surface and volume resistivity and low-frequency dielectric constant measurements of pure and multi-walled carbon nanotube (MWCNT) doped polyvinyl alcohol thin films

Science.gov (United States)

Edwards, Matthew; Guggilla, Padmaja; Reedy, Angela; Ijaz, Quratulann; Janen, Afef; Uba, Samuel; Curley, Michael

2017-08-01

Previously, we have reported measurements of temperature-dependent surface resistivity of pure and multi-walled carbon nanotube (MWNCT) doped amorphous Polyvinyl Alcohol (PVA) thin films. In the temperature range from 22 °C to 40 °C with humidity-controlled environment, we found the surface resistivity to decrease initially, but to rise steadily as the temperature continued to increase. Moreover, electric surface current density (Js) was measured on the surface of pure and MWCNT doped PVA thin films. In this regard, the surface current density and electric field relationship follow Ohm's law at low electric fields. Unlike Ohmic conduction in metals where free electrons exist, selected captive electrons are freed or provided from impurities and dopants to become conduction electrons from increased thermal vibration of constituent atoms in amorphous thin films. Additionally, a mechanism exists that seemingly decreases the surface resistivity at higher temperatures, suggesting a blocking effect for conducting electrons. Volume resistivity measurements also follow Ohm's law at low voltages (low electric fields), and they continue to decrease as temperatures increase in this temperature range, differing from surface resistivity behavior. Moreover, we report measurements of dielectric constant and dielectric loss as a function of temperature and frequency. Both the dielectric constant and dielectric loss were observed to be highest for MWCNT doped PVA compared to pure PVA and commercial paper, and with frequency and temperature for all samples.

SUS 321 HTB boiler tubing with fire grained internal surface resistant to steam-induced oxidation

International Nuclear Information System (INIS)

Kanero, Takahiro; Minami, Yuusuke; Kodera, Toshihide

1981-01-01

Considerable amount of scale is produced by high temperature steam on the austenitic stainless steel tubes used for the superheaters and reheaters of large boilers for power generation. The scale of outer layer separates off due to the thermal stress at the time of starting-up and stopping, and causes the blocking of pipes and the erosion of turbine blades. Following the increase of nuclear power generation, large boilers are used for medium load, accordingly it is expected that the troubles like these increase. In this paper, the manufacturing method and the properties of SUS 321 HTB with fine grain internal surface are reported, which was developed to reduce the rate of growth of scale and to prevent the separation of scale. In order to prevent the separation of scale from austenitic stainless steel tubes, the reduction of scale thickness, surface treatment such as chrome plating, the use of alloys with excellent oxidation resistance, the formation of chrome-rich film rapidly, the heat treatment of cold-worked tubes and so on were carried out. The nitrification of SUS 321 H steel brought about two-phase structure of the fine grain internal surface with excellent oxidation resistance and the rest of coarse grains with high creep strength. (Kako, I.)

Improving wettability of photo-resistive film surface with plasma surface modification for coplanar copper pillar plating of IC substrates

Science.gov (United States)

Xiang, Jing; Wang, Chong; Chen, Yuanming; Wang, Shouxu; Hong, Yan; Zhang, Huaiwu; Gong, Lijun; He, Wei

2017-07-01

The wettability of the photo-resistive film (PF) surfaces undergoing different pretreatments including the O2sbnd CF4 low-pressure plasma (OCLP) and air plasma (AP), is investigated by water contact angle measurement instrument (WCAMI) before the bottom-up copper pillar plating. Chemical groups analysis performed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectra (XPS) shows that after the OCLP and wash treatment, the wettability of PF surface is attenuated, because embedded fluorine and decreased oxygen content both enhance hydrophobicity. Compared with OCLP treatment, the PF surface treatment by non-toxic air plasma displays features of Csbnd O, Osbnd Cdbnd O, Cdbnd O and sbnd NO2 by AIR-FTIR and XPS, and a promoted wettability by WCAM. Under the identical electroplating condition, the surface with a better wettability allows electrolyte to spontaneously soak all the places of vias, resulting in improved copper pillar uniformity. Statistical analysis of metallographic data shows that more coplanar and flat copper pillars are achieved with the PF treatment of air plasma. Such modified copper-pillar-plating technology meets the requirement of accurate impedance, the high density interconnection for IC substrates.

Extension of Gibbs-Duhem equation including influences of external fields

Science.gov (United States)

Guangze, Han; Jianjia, Meng

2018-03-01

Gibbs-Duhem equation is one of the fundamental equations in thermodynamics, which describes the relation among changes in temperature, pressure and chemical potential. Thermodynamic system can be affected by external field, and this effect should be revealed by thermodynamic equations. Based on energy postulate and the first law of thermodynamics, the differential equation of internal energy is extended to include the properties of external fields. Then, with homogeneous function theorem and a redefinition of Gibbs energy, a generalized Gibbs-Duhem equation with influences of external fields is derived. As a demonstration of the application of this generalized equation, the influences of temperature and external electric field on surface tension, surface adsorption controlled by external electric field, and the derivation of a generalized chemical potential expression are discussed, which show that the extended Gibbs-Duhem equation developed in this paper is capable to capture the influences of external fields on a thermodynamic system.

The Closest Point Method and Multigrid Solvers for Elliptic Equations on Surfaces

KAUST Repository

Chen, Yujia; Macdonald, Colin B.

2015-01-01

© 2015 Society for Industrial and Applied Mathematics. Elliptic partial differential equations are important from both application and analysis points of view. In this paper we apply the closest point method to solve elliptic equations on general

Oxidation resistant peroxide cross-linked UHMWPE produced by blending and surface diffusion

International Nuclear Information System (INIS)

Gul, Rizwan M; Oral, Ebru; Muratoglu, Orhun K

2014-01-01

Ultra-high molecular weight polyethylene (UHMWPE) has been widely used as acetabular cup in total hip replacement (THR) and tibial component in total knee replacement (TKR). Crosslinking of UHMWPE has been successful used to improve its wear performance leading to longer life of orthopedic implants. Crosslinking can be performed by radiation or organic peroxides. Peroxide crosslinking is a convenient process as it does not require specialized equipment and the level of crosslinking can be manipulated by changing the amount of peroxide added. However, there is concern about the long-term stability of these materials due to possible presence of by-products. Vitamin E has been successfully used to promote long-term oxidative stability of UHMWPE. In this study, UHMWPE has been crosslinked using organic peroxide in the presence of Vitamin E to produce an oxidation resistant peroxide crosslinked material. Crosslinking was performed both in bulk by mixing peroxide and resin, and only on the surface using diffusion of peroxides.The results show that UHMWPE can be crosslinked using organic peroxides in the presence of vitamin E by both methods. However, the level of crosslinking decreases with the increase in vitamin E content. The wear resistance increases with the increase in crosslink density, and oxidation resistance significantly increases due to the presence of vitamin E

Oxidation resistant peroxide cross-linked UHMWPE produced by blending and surface diffusion

International Nuclear Information System (INIS)

Gul, R. M.; Oral, E.; Muratoglu, O. K.

2013-01-01

Ultra-high molecular weight polyethylene (UHMWPE) has been widely used as acetabular cup in total hip replacement (THR) and tibial component in total knee replacement (TKR). Crosslinking of UHMWPE has been successful used to improve its wear performance leading to longer life of orthopedic implants. Crosslinking can be performed by radiation or organic peroxides. Peroxide crosslinking is a convenient process as it does not require specialized equipment and the level of crosslinking can be manipulated by changing the amount of peroxide added. However, there is concern about the long-term stability of these materials due to possible presence of by-products. Vitamin E has been successfully used to promote long-term oxidative stability of UHMWPE. In this study, UHMWPE has been crosslinked using organic peroxide in the presence of Vitamin E to produce an oxidation resistant peroxide crosslinked material. Crosslinking was performed both in bulk by mixing peroxide and resin, and only on the surface using diffusion of peroxides.The results show that UHMWPE can be crosslinked using organic peroxides in the presence of vitamin E by both methods. However, the level of crosslinking decreases with the increase in vitamin E content. The wear resistance increases with the increase in crosslink density, and oxidation resistance significantly increases due to the presence of vitamin E. (author)

Measurement uncertainty evaluation of cellular spheroids surface tension in compressing tests using Young-Laplace equation

Science.gov (United States)

Beatrici, Anderson; Santos Baptista, Leandra; Mauro Granjeiro, José

2018-03-01

Regenerative Medicine comprises the Biotechnology, Tissue Engineering and Biometrology for stem cell therapy. Starting from stem cells extracted from the patient, autologous implant, these cells are cultured and differentiated into other tissues, for example, articular cartilage. These cells are reorganized into microspheres (cell spheroids). Such tissue units are recombined into functional tissues constructs that can be implanted in the injured region for regeneration. It is necessary the biomechanical characterization of these constructed to determine if their properties are similar to native tissue. In this study was carried out the modeling of the calculation of uncertainty of the surface tension of cellular spheroids with the use of the Young-Laplace equation. We obtained relative uncertainties about 10%.

A consistent hierarchy of generalized kinetic equation approximations to the master equation applied to surface catalysis.

Science.gov (United States)

Herschlag, Gregory J; Mitran, Sorin; Lin, Guang

2015-06-21

We develop a hierarchy of approximations to the master equation for systems that exhibit translational invariance and finite-range spatial correlation. Each approximation within the hierarchy is a set of ordinary differential equations that considers spatial correlations of varying lattice distance; the assumption is that the full system will have finite spatial correlations and thus the behavior of the models within the hierarchy will approach that of the full system. We provide evidence of this convergence in the context of one- and two-dimensional numerical examples. Lower levels within the hierarchy that consider shorter spatial correlations are shown to be up to three orders of magnitude faster than traditional kinetic Monte Carlo methods (KMC) for one-dimensional systems, while predicting similar system dynamics and steady states as KMC methods. We then test the hierarchy on a two-dimensional model for the oxidation of CO on RuO2(110), showing that low-order truncations of the hierarchy efficiently capture the essential system dynamics. By considering sequences of models in the hierarchy that account for longer spatial correlations, successive model predictions may be used to establish empirical approximation of error estimates. The hierarchy may be thought of as a class of generalized phenomenological kinetic models since each element of the hierarchy approximates the master equation and the lowest level in the hierarchy is identical to a simple existing phenomenological kinetic models.

Hole-to-surface resistivity measurements at Gibson Dome (drill hole GD-1) Paradox basin, Utah

Science.gov (United States)

Daniels, J.J.

1984-01-01

Hole-to-surface resistivity measurements were made in a deep drill hole (GD-1), in San Juan County, Utah, which penetrated a sequence of sandstone, shale, and evaporite. These measurements were made as part of a larger investigation to study the suitability of an area centered around the Gibson Dome structure for nuclear waste disposal. The magnitude and direction of the total electric field resulting from a current source placed in a drill hole is calculated from potential difference measurements for a grid of closely-spaced stations. A contour map of these data provides a detailed map of the distribution of the electric field away from the drill hole. Computation of the apparent resistivity from the total electric field helps to interpret the data with respect to the ideal situation of a layered earth. Repeating the surface measurements for different source depths gives an indication of variations in the geoelectric section with depth. The quantitative interpretation of the field data at Gibson Dome was hindered by the pressure of a conductive borehole fluid. However, a qualitative interpretation of the field data indicates the geoelectric section around drill hole GD-1 is not perfectly layered. The geoelectric section appears to dip to the northwest, and contains anomalies in the resistivity distribution that may be representative of localized thickening or folding of the salt layers.

Bacterial Cheating Limits the Evolution of Antibiotic Resistance

Science.gov (United States)

Yurtsev, Eugene; Xiao Chao, Hui; Datta, Manoshi; Artemova, Tatiana; Gore, Jeff

2012-02-01

The emergence of antibiotic resistance in bacteria is a significant health concern. Bacteria can gain resistance to the antibiotic ampicillin by acquiring a plasmid carrying the gene beta-lactamase, which inactivates the antibiotic. This inactivation may represent a cooperative behavior, as the entire bacterial population benefits from removal of the antibiotic. The presence of a cooperative mechanism of resistance suggests that a cheater strain - which does not contribute to breaking down the antibiotic - may be able to take advantage of resistant cells. We find experimentally that a ``sensitive'' bacterial strain lacking the plasmid conferring resistance can invade a population of resistant bacteria, even in antibiotic concentrations that should kill the sensitive strain. We use a simple model in conjunction with difference equations to explain the observed population dynamics as a function of cell density and antibiotic concentration. Our experimental difference equations resemble the logistic map, raising the possibility of oscillations or even chaotic dynamics.

Remotely Sensed, catchment scale, estimations of flow resistance

Science.gov (United States)

Carbonneau, P.; Dugdale, S. J.

2009-12-01

Despite a decade of progress in the field of fluvial remote sensing, there are few published works using this new technology to advance and explore fundamental ideas and theories in fluvial geomorphology. This paper will apply remote sensing methods in order to re-visit a classic concept in fluvial geomorphology: flow resistance. Classic flow resistance equations such as those of Strickler and Keulegan typically use channel slope, channel depth or hydraulic radius and some measure channel roughness usually equated to the 50th or 84th percentile of the bed material size distribution. In this classic literature, empirical equations such as power laws are usually calibrated and validated with a maximum of a few hundred data points. In contrast, fluvial remote sensing methods are now capable of delivering millions of high resolution data points in continuous, catchment scale, surveys. On the river Tromie in Scotland, a full dataset or river characteristics is now available. Based on low altitude imagery and NextMap topographic data, this dataset has a continuous sampling of channel width at a resolution of 3cm, of depth and median grain size at a resolution of 1m, and of slope at a resolution of 5m. This entire data set is systematic and continuous for the entire 20km length of the river. When combined with discharge at the time of data acquisition, this new dataset offers the opportunity to re-examine flow resistance equations with a 2-4 orders of magnitude increase in calibration data. This paper will therefore re-examine the classic approaches of Strickler and Keulagan along with other more recent flow resistance equations. Ultimately, accurate predictions of flow resistance from remotely sensed parameters could lead to acceptable predictions of velocity. Such a usage of classic equations to predict velocity could allow lotic habitat models to account for microhabitat velocity at catchment scales without the recourse to advanced and computationally intensive

Integration of Chandrasekhar's integral equation

International Nuclear Information System (INIS)

Tanaka, Tasuku

2003-01-01

We solve Chandrasekhar's integration equation for radiative transfer in the plane-parallel atmosphere by iterative integration. The primary thrust in radiative transfer has been to solve the forward problem, i.e., to evaluate the radiance, given the optical thickness and the scattering phase function. In the area of satellite remote sensing, our problem is the inverse problem: to retrieve the surface reflectance and the optical thickness of the atmosphere from the radiance measured by satellites. In order to retrieve the optical thickness and the surface reflectance from the radiance at the top-of-the atmosphere (TOA), we should express the radiance at TOA 'explicitly' in the optical thickness and the surface reflectance. Chandrasekhar formalized radiative transfer in the plane-parallel atmosphere in a simultaneous integral equation, and he obtained the second approximation. Since then no higher approximation has been reported. In this paper, we obtain the third approximation of the scattering function. We integrate functions derived from the second approximation in the integral interval from 1 to ∞ of the inverse of the cos of zenith angles. We can obtain the indefinite integral rather easily in the form of a series expansion. However, the integrals at the upper limit, ∞, are not yet known to us. We can assess the converged values of those series expansions at ∞ through calculus. For integration, we choose coupling pairs to avoid unnecessary terms in the outcome of integral and discover that the simultaneous integral equation can be deduced to the mere integral equation. Through algebraic calculation, we obtain the third approximation as a polynomial of the third degree in the atmospheric optical thickness

Effects of toroidicity on resistive tearing modes

International Nuclear Information System (INIS)

Izzo, R.; Monticello, D.A.; Manickam, J.; Strauss, H.R.; Grimm, R.; McGuire, K.

1983-03-01

A reduced set of resistive MHD equations is solved numerically in three dimensions to study the stability of tokamak plasmas. Toroidal effects are included self-consistently to leading and next order in inverse aspect ratio, epsilon. The equations satisfy an energy integral. In addition, the momentum equation yields the Grad-Shafranov equation correct to all orders in epsilon. Low beta plasma are studied using several different q-profiles. In all cases, the linear growth rates are reduced by finite toroidicity. Excellent agreement with resistive PEST is obtianed. In some cases, toroidal effects lead to complete stabilization of the mode. Nonlinear results show smaller saturated island widths for finite aspect ratio compared to the cylindrical limit. If the current channel is wide enough so as to produce steep gradients towards the outside of the plasma, both the finite aspect ratio cases and cylindrical cases disrupt

[The influence of autoclave sterilization on surface characteristics and cyclic fatigue resistance of 3 nickel-titanium rotary instruments].

Science.gov (United States)

Li, Xiang-fen; Zheng, Ping; Xu, Li; Su, Qin

2015-12-01

To investigate the effects of autoclave sterilization on surface characteristics and cyclic fatigue resistance of 3 types of nickel-titanium rotary instruments (K3, Mtwo, ProTaper). Three brands of NiTi rotary endodontic instruments of the same size (tip diameter 0.25 mm and constant 0.06 taper) were selected: K3, Mtwo and Protaper (F2). 24 instruments for each brand were used to evaluate the effects of autoclave sterilization on inner character in the as-received condition and after subjection to 0, 1, 5, and 10 sterilization cycles (6 for each group). Time to fracture (TtF) from the start of the test to the moment of file breakage and the length of the fractured fragment were recorded. Means and standard deviations of TtF and fragment length were calculated. The data was analyzed with SPSS13.0 software package. Another 12 NiTi rotary instruments for each brand were used, 6 subjected to 10 autoclave sterilization cycles and the other as control. Scanning electron microscope was used to observe the changes in surface topography and inner character. For cyclic fatigue resistance, when sterilization was not performed, K3 showed the highest value of TtF means and ProTaper the lowest. The differences between each brand were statistically significant (Pinstruments were intensified greatly after 10 cycles of sterilization. Cycle fatigue resistance is different among instruments of different brands. Autoclave sterilization may increase fatigue resistance of the 3 brands. Autoclave sterilization may increase the surface roughness and inner defects in cross section.

Effect of irrigation on surface roughness and fatigue resistance of controlled memory wire nickel-titanium instruments.

Science.gov (United States)

Cai, J-J; Tang, X-N; Ge, J-Y

2017-07-01

To investigate the effect of irrigation on the surface roughness and fatigue resistance of HyFlex and M3 controlled memory (CM) wire nickel-titanium instruments. Two new files of each brand were analysed by atomic force microscopy (AFM). Then, the instruments were dynamically immersed in either 5.25% sodium hypochlorite (NaOCl) or 17% ethylene diamine tetraacetic acid (EDTA) solution for 10 min, followed by AFM analysis. The roughness average (Ra) and root mean square (RMS) values were analysed statistically using an independent sample t-test. Then, 36 files of each brand were randomly assigned to three groups (n = 12). Group 1 (the control group) was composed of new instruments. Groups 2 and 3 were dynamically immersed in 5.25% NaOCl and 17% EDTA solutions for 10 min, respectively. The number of rotations to failure for various groups was analysed using the one-way analysis of variance software. For M3 files, the Ra and RMS values significantly increased (P  0.05) NaOCl. The resistance to cyclic fatigue of both HyFlex and M3 files did not significantly decrease (P > 0.05) by immersing in 5.25% NaOCl and 17% EDTA solutions. Except the HyFlex files immersed in NaOCl, the surface roughness of other files exposed to irrigants increased. However, a change in the surface tomography of CM wire instruments caused by contact with irrigants for 10 min did not trigger a decrease in cyclic fatigue resistance. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Antibiotic-Resistant Enteric Bacteria in Environmental Waters

Directory of Open Access Journals (Sweden)

Lisa M. Casanova

2016-11-01

Full Text Available Sources of antibiotic resistant organisms, including concentrated animal feeding operations (CAFOs, may lead to environmental surface and groundwater contamination with resistant enteric bacteria of public health concern. The objective of this research is to determine whether Salmonella, Escherichia coli, Yersinia enterocolitica, and enterococci resistant to clinically relevant antibiotics are present in surface and groundwater sources in two eastern North Carolina counties, Craven and Wayne. 100 surface and groundwater sites were sampled for Salmonella, E. coli, and enterococci, and the bacteria isolated from these samples were tested for susceptibility to clinically relevant antibiotics. Salmonella were detected at low levels in some surface but not groundwater. E. coli were in surface waters but not ground in both counties. Enterococci were present in surface water and a small number of groundwater sites. Yersinia was not found. Bacterial densities were similar in both counties. For Salmonella in surface water, the most frequent type of resistance was to sulfamethoxazole. There was no ciprofloxacin resistance. There were a few surface water E. coli isolates resistant to chloramphenicol, gentamicin, and ampicillin. Enterococci in surface water had very low levels of resistance to vancomycin, chloramphenicol, ampicillin, and streptomycin. E. coli and enterococci are present more frequently and at higher levels in surface water than Salmonella, but groundwater contamination with any of these organisms was rare, and low levels of resistance can be found sporadically. Resistant bacteria are relatively uncommon in these eastern N.C. surface and groundwaters, but they could pose a risk of human exposure via ingestion or primary contact recreation.

Diffusive limits for linear transport equations

International Nuclear Information System (INIS)

Pomraning, G.C.

1992-01-01

The authors show that the Hibert and Chapman-Enskog asymptotic treatments that reduce the nonlinear Boltzmann equation to the Euler and Navier-Stokes fluid equations have analogs in linear transport theory. In this linear setting, these fluid limits are described by diffusion equations, involving familiar and less familiar diffusion coefficients. Because of the linearity extant, one can carry out explicitly the initial and boundary layer analyses required to obtain asymptotically consistent initial and boundary conditions for the diffusion equations. In particular, the effects of boundary curvature and boundary condition variation along the surface can be included in the boundary layer analysis. A brief review of heuristic (nonasymptotic) diffusion description derivations is also included in our discussion

Chronological change of electrical resistance in GeCu2Te3 amorphous film induced by surface oxidation

International Nuclear Information System (INIS)

Saito, Yuta; Shindo, Satoshi; Sutou, Yuji; Koike, Junichi

2014-01-01

Unusual chronological electrical resistance change behavior was investigated for amorphous GeCu 2 Te 3 phase change material. More than a 1 order decrease of electrical resistance was observed in the air even at room temperature. The resistance of the amorphous film gradually increased with increasing temperature and then showed a drop upon crystallization. Such unusual behavior was attributed to the oxidation of the amorphous GeCu 2 Te 3 film. From the compositional depth profile measurement, the GeCu 2 Te 3 film without any capping layer was oxidized in air at room temperature and the formed oxide was mainly composed of germanium oxide. Consequently, a highly-conductive Cu-rich layer was formed in the vicinity of the surface of the film, which reduced the total resistance of the film. The present results could provide insight into the chronological change of electrical resistance in amorphous chalcogenide materials, indicating that not only relaxation of the amorphous, but also a large atomic diffusion contributes to the chronological resistance change. (paper)

Impact of an Environmental Cleaning Intervention on the Presence of Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococci on Surfaces in Intensive Care Unit Rooms

Science.gov (United States)

Goodman, Eric R.; Platt, Richard; Bass, Richard; Onderdonk, Andrew B.; Yokoe, Deborah S.; Huang, Susan S.

2009-01-01

OBJECTIVES To evaluate the adequacy of discharge room cleaning and the impact of a cleaning intervention on the presence of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) on environmental surfaces in intensive care unit (ICU) rooms. DESIGN Prospective environmental study. SETTING AND SAMPLE Convenience sample of ICU rooms in an academic hospital. METHODS AND INTERVENTION The intervention consisted of (1) a change from the use of pour bottles to bucket immersion for applying disinfectant to cleaning cloths, (2) an educational campaign, and (3) feedback regarding adequacy of discharge cleaning. Cleaning of 15 surfaces was evaluated by inspecting for removal of a preapplied mark, visible only with an ultraviolet lamp (“black light”). Six surfaces were cultured for MRSA or VRE contamination. Outcomes of mark removal and culture positivity were evaluated by χ2 testing and generalized linear mixed models, clustering by room. RESULTS The black-light mark was removed from 44% of surfaces at baseline, compared with 71% during the intervention (P <.001). The intervention increased the likelihood of removal of black-light marks after discharge cleaning (odds ratio, 4.4; P < .001), controlling for ICU type (medical vs surgical) and type of surface. The intervention reduced the likelihood of an environmental culture positive for MRSA or VRE (proportion of cultures positive, 45% at baseline vs 27% during the intervention; adjusted odds ratio, 0.4; P = .02). Broad, flat surfaces were more likely to be cleaned than were doorknobs and sink or toilet handles. CONCLUSIONS Increasing the volume of disinfectant applied to environmental surfaces, providing education for Environmental Services staff, and instituting feedback with a black-light marker improved cleaning and reduced the frequency of MRSA and VRE contamination. PMID:18624666

Analytic study of resistive instabilities

Energy Technology Data Exchange (ETDEWEB)

Svensson, Magnus

2003-05-01

In a fusion plasma there is always a small amount of resistivity that may cause instabilities. Although their rather slow growth rates they can be of major importance for fusion plasma confinement. In this work a MAPLE-code was rewritten and simplified to make it possible to analytically solve the linearized MHD-equations with resistivity in an RFP-configuration. By using the MHD-equations and expanding the unknown perturbed quantities u{sub 1r}(r) and B{sub 1r}(r) as Taylor series and solving each coefficient we could get eigenvalues, dispersion relations and a relation between the growth rate and the resistivity. The new code was first used to solve two cases with no resistivity and simple unstable equilibria which after running gave the correct expected results. The difference from running the original code with these two cases was the greater speed of the calculations and the less memory needed. Then by using an ideal MHD-stable equilibrium in a plasma with no resistivity the code gave us solutions which unfortunately were not of the expected kind but the time of the calculations was still very fast. The resistivity was finally added to the code with the ideal MHD-stable equilibrium. The program also this time gave incorrect results. We could, however, see from a relation between the growth rate and the resistivity that the solution may be approximately correct in this domain. Although we did not get all the correct results we have to consider the fact that we got results, that were not possible before. Before this work was carried out we could not get any results at all in the resistive cue because of the very long memory demanding expressions. In future work and studies it is not only possible to get the desired eigenvalues {gamma} as function of {eta} but also possible to get expressions for eigenfunctions, dispersion relations and other significant relations with a number of variable parameters. We could also use the method for any geometry and possibly for

Analytic study of resistive instabilities

International Nuclear Information System (INIS)

Svensson, Magnus

2003-05-01

In a fusion plasma there is always a small amount of resistivity that may cause instabilities. Although their rather slow growth rates they can be of major importance for fusion plasma confinement. In this work a MAPLE-code was rewritten and simplified to make it possible to analytically solve the linearized MHD-equations with resistivity in an RFP-configuration. By using the MHD-equations and expanding the unknown perturbed quantities u 1r (r) and B 1r (r) as Taylor series and solving each coefficient we could get eigenvalues, dispersion relations and a relation between the growth rate and the resistivity. The new code was first used to solve two cases with no resistivity and simple unstable equilibria which after running gave the correct expected results. The difference from running the original code with these two cases was the greater speed of the calculations and the less memory needed. Then by using an ideal MHD-stable equilibrium in a plasma with no resistivity the code gave us solutions which unfortunately were not of the expected kind but the time of the calculations was still very fast. The resistivity was finally added to the code with the ideal MHD-stable equilibrium. The program also this time gave incorrect results. We could, however, see from a relation between the growth rate and the resistivity that the solution may be approximately correct in this domain. Although we did not get all the correct results we have to consider the fact that we got results, that were not possible before. Before this work was carried out we could not get any results at all in the resistive cue because of the very long memory demanding expressions. In future work and studies it is not only possible to get the desired eigenvalues γ as function of η but also possible to get expressions for eigenfunctions, dispersion relations and other significant relations with a number of variable parameters. We could also use the method for any geometry and possibly for non

Study of surface properties of ATLAS12 strip sensors and their radiation resistance

Energy Technology Data Exchange (ETDEWEB)

Mikestikova, M., E-mail: mikestik@fzu.cz [Academy of Sciences of the Czech Republic, Institute of Physics, Na Slovance 2, 18221 Prague 8 (Czech Republic); Allport, P.P.; Baca, M.; Broughton, J.; Chisholm, A.; Nikolopoulos, K.; Pyatt, S.; Thomas, J.P.; Wilson, J.A. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Kierstead, J.; Kuczewski, P.; Lynn, D. [Brookhaven National Laboratory, Physics Department and Instrumentation Division, Upton, NY 11973-5000 (United States); Hommels, L.B.A. [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Ullan, M. [Centro Nacional de Microelectronica (IMB-CNM, CSIC), Campus UAB-Bellaterra, 08193 Barcelona (Spain); Bloch, I.; Gregor, I.M.; Tackmann, K. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Hauser, M.; Jakobs, K.; Kuehn, S. [Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg (Germany); and others

2016-09-21

A radiation hard n{sup +}-in-p micro-strip sensor for the use in the Upgrade of the strip tracker of the ATLAS experiment at the High Luminosity Large Hadron Collider (HL-LHC) has been developed by the “ATLAS ITk Strip Sensor collaboration” and produced by Hamamatsu Photonics. Surface properties of different types of end-cap and barrel miniature sensors of the latest sensor design ATLAS12 have been studied before and after irradiation. The tested barrel sensors vary in “punch-through protection” (PTP) structure, and the end-cap sensors, whose stereo-strips differ in fan geometry, in strip pitch and in edge strip ganging options. Sensors have been irradiated with proton fluences of up to 1×10{sup 16} n{sub eq}/cm{sup 2}, by reactor neutron fluence of 1×10{sup 15} n{sub eq}/cm{sup 2} and by gamma rays from {sup 60}Co up to dose of 1 MGy. The main goal of the present study is to characterize the leakage current for micro-discharge breakdown voltage estimation, the inter-strip resistance and capacitance, the bias resistance and the effectiveness of PTP structures as a function of bias voltage and fluence. It has been verified that the ATLAS12 sensors have high breakdown voltage well above the operational voltage which implies that different geometries of sensors do not influence their stability. The inter-strip isolation is a strong function of irradiation fluence, however the sensor performance is acceptable in the expected range for HL-LHC. New gated PTP structure exhibits low PTP onset voltage and sharp cut-off of effective resistance even at the highest tested radiation fluence. The inter-strip capacitance complies with the technical specification required before irradiation and no radiation-induced degradation was observed. A summary of ATLAS12 sensors tests is presented including a comparison of results from different irradiation sites. The measured characteristics are compared with the previous prototype of the sensor design, ATLAS07. - Highlights: �

Delivery of parameterization schemes for the determination of the regional evapotranspiration of different land surfaces. Final report; Bereitstellung von Parameterisierungsverfahren zur Bestimmung der regionalen Verdunstung verschiedener Landoberflaechen. Abschlussbericht 1997

Energy Technology Data Exchange (ETDEWEB)

Haenel, H.D.; Loepmeier, F.J.

1998-03-01

The task was the delivery of parameterization schemes for the calculation of the regional evapotranspiration of different land surfaces. The main weight was on the discussion of existing approaches and on the development of new ones for the calculation of evapotranspiration. After consideration of different concepts the well-known Penman-Monteith equation proved to the optimal basis of calculation. The surface resistance, respectively the related bulk-stomata resistance, is an important part of the resistance pattern (analogous to Ohm`s law) on which the Penman-Monteith equation is based. Under consideration of the dependence of these resistances of the spatial scale (leaf, canopy) as well as of the time scale (hour, day) possibilities for their estimation were discussed. An important step to determine the surface resistances from literature data of vegetation evapotranspiration was the development of a converting scheme of Haude`s factors to surface resistances. For bare soil an approach was developed which allows approximately to give a new interpretation to surface resistances from evapotranspiration courses, described in literature as proportional to the square root of time. (orig.) [Deutsch] Die Aufgabenstellung bestand in der Bereitstellung von Parametrisierungsverfahren zur Bestimmung der regionalen Verdunstung verschiedener Landoberflaechen. Dabei lag das Schwergewicht auf der Diskussion bereits bestehender und der Entwicklung neuer Ansaetze zur Berechnung der Verdunstung. Nach der Betrachtung unterschiedlicher Konzepte erwies sich die bekannte Penman-Monteith-Gleichung als optimale Berechnungsgrundlage. Ein wesentlicher Bestandteil des der Penman-Monteith-Gleichung zugrundeliegenden Widerstandsschemas (Analogie zum Ohmschen Gesetz) ist der Oberflaechenwiderstand bzw. der damit verwandte Bulk-Stomatawiderstand. Unter Beruecksichtigung der Abhaengigkeit dieser Widerstaende sowohl von der raeumlichen Skala (Blatt/Bestand) als auch von der zeitlichen Skala

Constitutional equations of thermal stresses of particle-reinforced composite

International Nuclear Information System (INIS)

Asakawa, Atsushi; Noda, Naotake; Tohgo, Keiichiro; Tsuji, Tomoaki.

1994-01-01

Functionally gradient materials (FGM) have been developed as ultrahigh-heat-resistant materials in aircraft, space engineering and nuclear fields. In the heat-resistant FGM which contain particles (ceramics) in the matrix (metal), the matrix will be subjected to plastic deformation, particles will be debonded, and finally cracks will be generated. The constitutive equations of FGM which take into account the damage process and change in temperature are necessary in order to solve these phenomena. In this paper, the constitutive equations of particle-reinforced composites with consideration of the damage process and change in temperature are estimated by the equivalent inclusion method in terms of elastoplasticity. The stress-strain relations and the coefficients of linear thermal expansion of the composites (Al-PSZ and Ti-PSZ) are calculated in ultrahigh temperature. (author)

Wave resistance calculation method combining Green functions based on Rankine and Kelvin source

Directory of Open Access Journals (Sweden)

LI Jingyu

2017-12-01

Full Text Available [Ojectives] At present, the Boundary Element Method(BEM of wave-making resistance mostly uses a model in which the velocity distribution near the hull is solved first, and the pressure integral is then calculated using the Bernoulli equation. However,the process of this model of wave-making resistance is complex and has low accuracy.[Methods] To address this problem, the present paper deduces a compound method for the quick calculation of ship wave resistance using the Rankine source Green function to solve the hull surface's source density, and combining the Lagally theorem concerning source point force calculation based on the Kelvin source Green function so as to solve the wave resistance. A case for the Wigley model is given.[Results] The results show that in contrast to the thin ship method of the linear wave resistance theorem, this method has higher precision, and in contrast to the method which completely uses the Kelvin source Green function, this method has better computational efficiency.[Conclusions] In general, the algorithm in this paper provides a compromise between precision and efficiency in wave-making resistance calculation.

The influence of the carbon surface chemical composition on Dubinin-Astakhov equation parameters calculated from SF{sub 6} adsorption data-grand canonical Monte Carlo simulation

Energy Technology Data Exchange (ETDEWEB)

Furmaniak, Sylwester; Terzyk, Artur P; Gauden, Piotr A [Department of Chemistry, Physicochemistry of Carbon Materials Research Group, N Copernicus University, Gagarin Street 7, 87-100 Torun (Poland); Kowalczyk, Piotr [Nanochemistry Research Institute, Curtin University, PO Box U1987, Perth, WA 6845 (Australia); Harris, Peter J F, E-mail: aterzyk@chem.uni.torun.pl [Centre for Advanced Microscopy, University of Reading, Whiteknights, Reading RG6 6AF (United Kingdom)

2011-10-05

Using grand canonical Monte Carlo simulation we show, for the first time, the influence of the carbon porosity and surface oxidation on the parameters of the Dubinin-Astakhov (DA) adsorption isotherm equation. We conclude that upon carbon surface oxidation, the adsorption decreases for all carbons studied. Moreover, the parameters of the DA model depend on the number of surface oxygen groups. That is why in the case of carbons containing surface polar groups, SF{sub 6} adsorption isotherm data cannot be used for characterization of the porosity. (paper)

Nuclear reactor vessel surface inspecting technique applying electric resistance probe

International Nuclear Information System (INIS)

Yamaguchi, T.; Enami, K.; Yoshioka, M.

1975-01-01

A new technique for inspecting the inner surface of the PWR type nuclear reactor vessel by use of an electric resistance probe is introduced, centering on a data processing system. This system is composed of a mini-computer, a system typewriter, an interface unit, a D-A converter and controller, and X-Y recorder and others. Its functions are judging flaws and making flaw detection maps. In order to judge flaws by flaw detection signals, three kinds of flaw judging methods have been developed. In case there is a flaw, its position and depth are calculated and listed on the system typewriter. The flaw detection maps are expressed in four kinds of modes and they are displayed on the X-Y recorder. (auth.)

Correlation between morphology, electron band structure, and resistivity of Pb atomic chains on the Si(5 5 3)-Au surface

International Nuclear Information System (INIS)

Jałochowski, M; Kwapiński, T; Łukasik, P; Nita, P; Kopciuszyński, M

2016-01-01

Structural and electron transport properties of multiple Pb atomic chains fabricated on the Si(5 5 3)-Au surface are investigated using scanning tunneling spectroscopy, reflection high electron energy diffraction, angular resolved photoemission electron spectroscopy and in situ electrical resistance. The study shows that Pb atomic chains growth modulates the electron band structure of pristine Si(5 5 3)-Au surface and hence changes its sheet resistivity. Strong correlation between chains morphology, electron band structure and electron transport properties is found. To explain experimental findings a theoretical tight-binding model of multiple atomic chains interacting on effective substrate is proposed. (paper)

Nano structure Formations and Improvement in Corrosion Resistance of Steels by Means of Pulsed Electron Beam Surface Treatment

International Nuclear Information System (INIS)

Zhang, K.M.; Zou, J.X.; Zou, J.X.; Grosdidier, T.; Zou, J.X.; Grosdidier, T.; Grosdidier, T.

2013-01-01

The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nano structure formations of steels by using a low energy high pulsed electron beam (LEHCPEB) treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nano structure formations of steels by using a low energy high pulsed electron beam (LEHCPEB) treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels

Using packaged software for solving two differential equation problems that arise in plasma physics

International Nuclear Information System (INIS)

Gaffney, P.W.

1980-01-01

Experience in using packaged numerical software for solving two related problems that arise in Plasma physics is described. These problems are (i) the solution of the reduced resistive MHD equations and (ii) the solution of the Grad-Shafranov equation

Stainless Steel Foil with Improved Creep-Resistance for Use in Primary Surface Recuperators for Gas Turbine Engines

International Nuclear Information System (INIS)

Browning, P.F.; Fitzpatrick, M.; Grubb, J.F.; Klug, R.C.; Maziasz, P.J.; Montague, J.P.; Painter, R.A.; Swindeman, R.W.

1998-01-01

Primary surface recuperators (PSRs) are compact heat-exchangers made from thin-foil type 347 austenitic stainless steel, which boost the efficiency of land-based gas turbine engines. Solar Turbines uses foil folded into a unique corrugated pattern to maximize the primary surface area for efficient heat transfer between hot exhaust gas on one side, and the compressor discharge air on the other side of the foil. Allegheny-Ludlum produces 0.003 - 0.0035 in. thick foil for a range of current turbine engines using PSRs that operate at up to 660 degrees C. Laboratory-scale processing modification experiments recently have demonstrated that dramatic improvements can be achieved in the creep resistance of such typical 347 stainless steel foils. The modified processing enables fine NbC carbide precipitates to develop during creep at 650-700 degrees C, which provides strength even with a fine grain size. Such improved creep-resistance is necessary for advanced turbine systems that will demand greater materials performance and reliability at higher operating conditions. The next challenges are to better understand the nature of the improved creep resistance in these 347 stainless steel foil, and to achieve similar improvements with scale-up to commercial foil production

Development of low-friction and wear-resistant surfaces for low-cost Al hot stamping tools