Showing papers on "Surface roughness published in 1977"
TL;DR: In this article, it is shown that surface roughness can greatly reduce the adhesion between soft elastic solids and shows the importance of combining concepts of surface forces (or surface energies) with the principles of contact mechanics.
1,199 citations
TL;DR: In this paper, a model for short pulse scattering from a statistically random planar surface with particular application to current state-of-the-art radar altimetry is presented.
Abstract: This paper is concerned with the theoretical model for short pulse scattering from a statistically random planar surface with particular application to current state of the art radar altimetry, A short review of the assumptions inherent in the convolational model is presented. Simplified expressions are obtained for both the impulse response and the average backscattered power for near normal incidence under the assumptions common to satellite radar altimetry systems. In particular, it is shown that the conventional two-dimensional surface integration can be reduced to a closed form solution. Two applications of these results are presented relative to radar altimetry, namely, radar antenna pointing angle determination and altitude bias correction for pointing angle and surface roughness effects. It is also shown that these results have direct application to the analysis of the two frequency system proposed by Weissman, and a possible combined long pulse altimeter and two frequency system is suggested.
721 citations
TL;DR: In this article, the aerodynamic resistance to vertical transfer in the surface boundary layer can be formulated in terms of the friction velocity, height of observation, vertical heat flux, and surface roughness.
Abstract: The deposition of sulfur dioxide on growing vegetation is affected by diverse environmental factors, many of which undergo large diurnal and spatial variations. The aerodynamic resistance to vertical transfer in the surface boundary layer can be formulated in terms of the friction velocity, height of observation, vertical heat flux, and surface roughness. Also important are the resistance in the air layer closest to the surface elements and, in dry vegetation, the average stomatal resistance of the plants. The latter variable is among the most difficult to estimate, but over many agricultural field crops like those in the midwestern U.S., a typical minimum value of average stomatal resistance to SO2 transfer is about 0.7 s cm-1, as is indicated by various experimental data. The deposition velocity can be estimated as the inverse of the sum of the resistances of the layers, necessarily down to where the concentrations are zero; in the surface boundary layer, any of the various resistances might be dominant...
566 citations
TL;DR: A preferential etch for (100 and (111) oriented, p and n-type silicon has been developed in this paper with a relatively slow etch rate (∼1 μm per min) at room temperature providing etch control.
Abstract: A new preferential etch for (100) and (111) oriented, p‐ and n‐type silicon has been developed. Oxidation‐induced stacking faults, dislocations, swirl, and striations are clearly defined with minimum surface roughness or extraneous pitting. A relatively slow etch rate (∼1 μm per min) at room temperature provides etch control. The long shelf life of this etch allows the solution to be stored in large quantities.
333 citations
01 Jun 1977
TL;DR: In this paper, the effect of roughness of a solid surface on its wettability by a liquid has been studied theoretically using mechanistic arguments, and a plausible explanation for hysteresis of the drop shape and contact angle was provided for solid surfaces with concentric grooves.
Abstract: The effect of roughness of a solid surface on its wettability by a liquid has been studied theoretically using mechanistic arguments. By calculating the equilibrium shape of a liquid drop resting on a rough surface, we obtain the relation between the true (or microscopic) equilibrium contact angle at the three-phase contact line and the apparent contact angle observed macroscopically at the geometrical contour plane of the solid. By extending a proposal of Shuttleworth and Bailey, we provide a plausible explanation for hysteresis of the drop shape and contact angle which we evaluate for solid surfaces with concentric grooves. To calculate the equilibrium drop shape of a liquid on a solid surface whose roughness is more realistic than concentric grooves, we employ a perturbation method of solving approximately the Young-Laplace equation for the shape. Although the hysteresis in contact angle and drop shape cannot be evaluated by the method, the apparent contact angle and the local contact line positions are approximately predicted when the surface roughness has the form of cross grooves, hexagonal grooves, and radial grooves. Surfaces having random roughness are also considered and a modified form of the well-known Wenzel equation is derived which includes a factor for surface texture in addition to the conventional roughness factor.
313 citations
TL;DR: In this paper, the diffraction of electromagnetic waves from the rough surface of a material of finite permittivity is examined for the case where the wavelength of the incident radiation is comparable to the dimensions of the surface roughness.
Abstract: The diffraction of electromagnetic waves from the rough surface of a material of finite permittivity is examined for the case where the wavelength of the incident radiation is comparable to the dimensions of the surface roughness. Two methods of calculation studied are the Rayleigh method and the extinction-theorem integral-equation method. The latter is shown to have a unique exact solution. This property is, in turn, used to show how the Rayleigh method can be modified to give convergent results. The extinction theorem is also used to reduce the Rayleigh equations to a simpler form. These reduced equations, which are extremely convenient to use in the case of small roughness, are applied in this case to find perturbative expressions for the reflected field and for the surface-plasmon dispersion relation.
223 citations
TL;DR: In this paper, the broadening of Landau levels and the transport quantities, such as the transverse and Hall conductivity and cyclotron resonance linewidth, are calculated in an inversion layer on the (100) surface of p-type Si at zero temperature.
Abstract: The broadening of Landau levels and the transport quantities, such as the transverse and Hall conductivity and cyclotron resonance linewidth, are calculated in an inversion layer on the (100) surface of p -type Si at zero temperature. Main scattering mechanisms are assumed to be charged impurity scattering and surface roughness scattering. A new expression for the surface roughness scattering is obtained. The self-consistent Born approximation is employed for the effect of scattering, and the random phase approximation for the screening. Because of the singular density of states the screening depends on the position of the Fermi level and becomes weak when it lies at the tail region of each Landau level. Scattering potentials become strong and of slowly varying type in this case. Except such a special case, overall features agree with the results obtained for short-ranged scatterers.
188 citations
TL;DR: In this paper, the effects of texture on reflectivity and transmission through an exact calculation of a boundary layer whose complex dielectric constant is an appropriate average of the material and air was obtained.
158 citations
TL;DR: In this paper, the influence of surface roughness on the heat transfer of a circular cylinder to the cross-flow of air has been studied and the transition from a laminar to a turbulent boundary layer as a function of Reynolds number and roughness parameter was investigated.
150 citations
TL;DR: In this article, a structure function is proposed as a means of quantifying variations in surface texture, which is related simply to the autocorrelation function but is without some of its disadvantages.
145 citations
TL;DR: In this article, the authors discussed the measurement of the finish of diamond-turned surfaces by differential light scattering and analyzed the two-dimensional power spectral density of the surface roughness, which can then be used to specify surface finish and predict scattering under a variety of conditions.
Abstract: This paper discusses the measurement of the finish of diamond-turned surfaces by differential light scattering. Experimental scattering data are analyzed by electromagnetic theory to give the two-dimensional power spectral density of the surface roughness. These spectral densities are direct functional measures of the surface quality, and may be characterized in terms of topographic finish parameters. These parameters can then be used to specify surface finish, to predict scattering under a variety of conditions, and to aid in studies of other functional properties of these surfaces. Scattering spectra are separated in-to three groups corresponding to three classes of surface roughness: periodic tool marks and one- and two-dimensional random roughness. Periodic tool marks give rise to discrete diffraction lines in the scattering spectrum and are characterized by their surface periods and their Fourier amplitudes. Random one- and two-dimensional roughness give rise to one- and two-dimensional continua underlying the diffraction lines and are characterized by band-limited values of the rms surface heights and slopes, and transverse length parameters. Using HeNe light, vertical roughnesses are measured from a fraction of an Angstrom to several hundred Angstroms, for transverse spatial wavelengths from a fraction of a micron to several hundred microns. We re-view experimental techniques for making these measurements with emphasis on the scatterometer developed in our laboratory, which uses a fixed source-detector geometry and a rotating sam-ple. Results are illustrated by a number of scattering spectra taken with this instrument.
TL;DR: In this article, the relations between surface statistics and the near and far-field scattered light statistics are surveyed, mainly using scalar diffraction theory, and the methods which have been proposed and used are grouped and described according to whether they operate in the near or the far field and whether they use monochromatic or polychromatic light.
Abstract: The relations between surface statistics and the near- and far-field scattered light statistics are surveyed, mainly using scalar diffraction theory. The methods which have been proposed and used are grouped and described according to whether they operate in the near-field or the far-field and whether they use monochromatic or polychromatic light. Several methods emerge as promising for practical application to non-contacting and non-destructive testing.
TL;DR: In this paper, a study of the influence of surface roughness on the net work of adhesion when a smooth, high viscoelastic solid is first brought into contact with and then pulled away from a roughened Perspex surface was performed.
Abstract: A study of the influence of surface roughness on the net work of adhesion when a smooth, high viscoelastic solid is first brought into contact with and then pulled away from a roughened Perspex surface. The work of adhesion was observed to be strongly dependent upon the rate at which these surfaces were pulled apart. The rate dependence of the adhesion could be calculated by normalizing the data obtained for the normally smooth surface. At small roughness value an increase in the adhesion was observed.
TL;DR: In this paper, a slab model of the boundary layer was used to study the dynamics of the internal boundary layer associated with changes in surface temperature and the vertical velocity induced by variations in the horizontal velocity could play an important role in controlling the expansion of the mixed layer.
Abstract: A slab model of the boundary layer was used to study the dynamics of the internal boundary layer associated with changes in surface temperature. The usual numerical procedure involving finite differences was avoided by solving the governing equations in a Lagrangian framework. The results of the modelling study showed that mixed-layer growth was enhanced by: (a) an increase in surface roughness; (b) an increase in the surface temperature change; and (c) a decrease in the horizontal velocity. It was found that the vertical velocity induced by variations in the horizontal velocity could play an important role in controlling the expansion of the mixed layer. The second part of the study involved the formulation of a model by simplifying the governing equations. The analytical solution obtained from the model compared favourably with the results of the numerical model. Furthermore, the analytical expression for the mixed-layer height was virtually identical to that presented by Raynor et al. (1974) to fit their observational data.
TL;DR: In this article, frustrated total reflection was used to optically excite electromagnetic surface plasma waves (SPW) in two different layered structures, where the surface roughness of the evaporated Mg${\mathrm{F}}_{2}$ films was found to increase with film thickness and this roughness has a pronounced effect on the SPW resonances.
Abstract: The method of frustrated total reflection is used to optically excite electromagnetic surface plasma waves (SPW) in two different layered structures. The first system studied has two films (Mg${\mathrm{F}}_{2}$-Ag) between glass and air, and the second has three films (Ag-Mg${\mathrm{F}}_{2}$-Ag) between glass and air. Surface roughness of the evaporated Mg${\mathrm{F}}_{2}$ films is found to increase with film thickness and this roughness has a pronounced effect on the SPW resonances. A cermet is imagined to form at the Mg${\mathrm{F}}_{2}$-Ag interface, and its effective optical constants can be evaluated using the Maxwell Garnett theory. If this cermet is treated as a separate layer in the structure, then good agreement is found with the experimentally observed resonances. A calculation of the Poynting vector field, current distributions, and surface charge densities, resulting from an incident monochromatic plane wave, shows the different modes of oscillation corresponding to each resonance.
01 Jun 1977
TL;DR: In this paper, a saturated solution of ammonium bifluoride is shown to be capable of producing chemically polished AT-cut quartz surfaces over a broad range of conditions.
Abstract: : Etching in a saturated solution of ammonium bifluoride is shown to be capable of producing chemically polished AT-cut quartz surfaces over a broad range of conditions The quality of chemical polish depends primarily on the surface finish prior to etching, the depth of etch and the quality of quartz used The speed of polishing depends primarily on the temperature of the etching bath In an 88 degree C etching bath, starting with 3 micrometers lapped blanks, chemically polished blanks with a surface roughness of 01 micrometer and a roughness angle of 1 degree can be produced in 15 minutes Starting with a finer surface finish can produce a smoother chemically polished surface Chemically polished blanks are shown to be extremely strong Fundamental mode 20 MHz resonators made with chemically polished natural quartz blanks showed no Q degradation with increasing depth of etch
TL;DR: In this paper, a multilayer sandwich structure composed of alternate layers of Ni and Cr (ten layers 370 A thick and twenty layers 115 A thick respectively) with initial surface roughness of not greater than 100 A and approximately 1 μm were obtained by sputtering with 1 keV argon ions and simultaneous Auger electron spectroscopy.
TL;DR: In this paper, a systematic perturbation theory is developed to study the interaction of electromagnetic waves at rough dielectric surfaces, and explicit expressions for both first-order and second-order fields (in terms of the surface roughness parameter) at all points in space are presented.
Abstract: A systematic perturbation theory is developed to study the interaction of electromagnetic waves at rough dielectric surfaces. The Ewald-Oseen extinction theorem is used as the basis of the perturbation theory. Explicit expressions for both first-order and second-order fields (in terms of the surface roughness parameter) at all points in space are presented. The incident field is treated very generally and thus it can be in any state of polarization. The surface is characterized by a structure function and hence the results are valid both for periodic and statistical surfaces. The first-order fields are used to calculate various types of scattering cross sections for arbitrary incident fields characterized by coherence matrices. The coherence matrix for scattered fields is given. The equivalent electric and magnetic surface currents on a flat surface which would lead to the same expressions for first-order fields as those obtained for the rough surface, are calculated using the extinction theorem. The extinction cross section is calculated using an appropriately formulated optical theorem. This leads in a straightforward manner to a change in the value of the reflectivity as compared to the value on a flat surface. The experiment of Teng and Stern is discussed briefly in the light of the expressions for extinction cross sections. Finally, first-order and second-order fields are used to discuss Smith-Purcell radiation, i.e., the radiation emitted by an electron moving parallel to a grating surface. This case corresponds to the conversion of evanescent waves into homogeneous waves due to surface roughness. The relation of some of our results to those of Crowell, Elson, Ritchie, Juranek, Lalor, Marvin et al., Maradudin, and Mills is also discussed.
TL;DR: It is concluded that the combined use of microroughness measurements and SEM is of considerable value in this type of studies since more information may be obtained than by any of these methods used separately.
Abstract: Root surface roughness, resulting from calculus removal by hand curette, ultrasonic curette and rotating diamond or Roto-Pro points, was examined by combined use of microroughness measurements and scanning electron microscopy (SEM). Mandibular incisors were placed in a jaw model with a rubber "gingiva" in an attempt to simulate a clinical situation. After cleaning with the various instruments, the surface roughness was measured by an industrial profilometer followed by SEM evaluation. A microroughness index (MRI) was developed and showed that the instruments could be separated into three groups, where the hand curette produced least roughness, followed by the Roto-Pro instrument, while the ultrasonic curette and the diamond left the most uneven surfaces. A SEM roughness index (SRI) based on defined criteria, corresponded well with the results from the profilometer measurements, except that using this index the diamond scored higher than the ultrasonic curette. This was probably due to considerable calculus remnants remaining in the ultrasonic specimens. Characteristic features of the root surface morphology of the cleaned teeth are described. It is concluded that the combined use of microroughness measurements and SEM is of considerable value in this type of studies since more information may be obtained than by any of these methods used separately.
TL;DR: In this article, the optical constants, surface roughness, and band gap of amorphous Si3N4 films on quartz substrate are determined from optical measurements, and a model for continuous and symmetric state density is presented, and the localized volume V0 and the total concentration of the states NT are estimated.
Abstract: The optical constants, surface roughnesses, and band gap Eg of amorphous Si3N4 films on quartz substrate are determined from optical measurements. The results of the Si3N4 samples with different preparation are compared and discussed. Absorption tails at the band edges indicate localized states in the forbidden gap. A model for continuous and symmetric state density is presented, and the localized volume V0 and the total concentration of the states NT are estimated.
TL;DR: In this paper, the authors measured skin friction on an axisymmetric body with and without injection through the surface in a turbulent, low-speed flow and found a good correlation between the present experiment and previous experiment and theory was shown for the solid-wall data.
Abstract: Experimental studies were conducted to measure directly the skin friction on an axisymmetric body with and without injection through the surface in a turbulent, low-speed flow. Measurements also were taken of velocity profiles and the axial turbulence intensity throughout the boundary layer. The axisymmetric model, with interchangeable solid, smooth and porous, slightly rough walls, was tested at ReL from 4.96 to 6.11xl0 6. Particular attention was paid to the law-of-the-wall region of the boundary layer. For both the law-of-the-wall and axial turbulent intensities, good correlation between the present experiment and previous experiment and theory was shown for the solid-wall data. Porous-wall tests with no injection showed an increase in the local skin friction and an attendant shift in the log region of the law-of-the-wall because of the slight roughness of the permeable-wall over the solid-wall values. For cases with blowing through the permeable wall, direct measurements of the skin friction showed a decrease over the unblown cases with the permeable wall. However, substantial blowing was required to reduce the skin friction below that obtained on the solid, smooth wall at the same conditions. The logarithmic region of the law-of-the-wall with blowing was found to be independent of the blowing rate over the range tested when compared to the porous, unblown wall results. These experimental data were used to construct extensions of both the Van Driest and Reichardt transport models. The Reichardt model proved more useful, and excellent results were achieved. A,A',B A +
TL;DR: In this paper, the average contrast of speckle patterns produced in the far field region of the illuminated metal surfaces has been measured for these samples as a function of the illumination width of the laser light over the object surface and is found to have a relation with their CLA (center line average height) roughness.
Abstract: On the basis of our previous studies on measurements of surface roughness properties using the average speckle contrast, we have actually applied a speckle technique to measure the fine scale roughness of various metal surfaces produced with different finishing processes. The average contrast of speckle patterns produced in the far-field region of the illuminated metal surfaces has been measured for these samples as a function of the illuminated spot width of the laser light over the object surface and is found to have a relation with their CLA (center line average height) roughness. Measurements of surface roughness now become possible for metal objects having various surface profiles by investigating the average contrast variation of speckle intensity distributions as a function of the illuminated spot width of the laser light.
TL;DR: In this article, the authors used scanning electron microscopy for direct observation of the effects of surface roughness on the spreading of liquids, making it possible to view moving liquid drops at distances less than 1 μm from the advancing contact line.
01 Jan 1977
TL;DR: In this paper, the authors used a passive microwave sensor to estimate the average soil moisture within two depths; however, it appeared that a frequency less than 10.6 GHz would be preferable for the surface measurement.
Abstract: The author has identified the following significant results. Experimental measurements were utilized to demonstrate a procedure for estimating soil moisture, using a passive microwave sensor. The investigation showed that 1.4 GHz and 10.6 GHz can be used to estimate the average soil moisture within two depths; however, it appeared that a frequency less than 10.6 GHz would be preferable for the surface measurement. Average soil moisture within two depths would provide information on the slope of the soil moisture gradient near the surface. Measurements showed that a uniform surface roughness similar to flat tilled fields reduced the sensitivity of the microwave emission to soil moisture changes. Assuming that the surface roughness was known, the approximate soil moisture estimation accuracy at 1.4 GHz calculated for a 25% average soil moisture and an 80% degree of confidence, was +3% and -6% for a smooth bare surface, +4% and -5% for a medium rough surface, and +5.5% and -6% for a rough surface.
TL;DR: In this article, the effect of volume and surface plasma excitation on the spectra of Ag(111) evaporated electrodes on mica in aqueous electrolytes was measured within the wavelength range of 500 to 200 nm for p- and s-polarized light as a function of the angle of incidence, bias potential and surface roughness.
TL;DR: In this paper, a vortex simulator is used to study the role of surface friction in the formation of multiple vortices, and it is shown that over a rough surface more swirl is necessary to initiate the transition to a greater number of vortexes than over a smooth surface.
Abstract: A vortex simulator is used to study multiple vortices with particular interest on the role of surface friction in their formation. Measurements with a hot-film anemometer show that the maximum velocity in a multiple-vortex system of four is greater than that for a single vortex created with the same volume flow rate. The friction experiments indicate that over a rough surface more swirl is necessary to initiate the transition to a greater number of vortices than over a smooth surface. Thus, for a tornado on the verge of a transition to multiple vortices, translation across a smoother terrain could act as a catalyst for the process.
TL;DR: In this paper, it is proposed that the increase in surface roughness which occurs with increasing strain reduces the effective thickness of a plastically stretched sheet metal so that a tensile instability condition occurs at surface strains smaller than those predicted by the classical analysis.
TL;DR: In this paper, surface roughness was used to couple the surface waves out, and the results were used to deduce characteristic parameters of bulk excitons in ZnO, where optical mixing is used to excite surface exciton polaritons.
Abstract: Dispersion and damping characteristics of surface exciton polaritons in ZnO have been measured by nonlinear optical technique. Optical mixing was used to excite surface exciton polaritons while surface roughness was used to couple the surface waves out. The results were used to deduce characteristic parameters of bulk excitons in ZnO.