Method For Determination Of Thickness Research Articles

Automatic asphalt layer interface detection and thickness determination from ground-penetrating radar data

Ground-penetrating radar (GPR) has been widely used in asphalt pavement layer thickness measurement. It requires the detection of pavement layer interfaces, which could be accomplished via manual inspection. This may be subjective and cause inaccurate thickness measurements due to the field data noise. Existing layer interface detection methods for thickness determination usually require customized programming and/or manual inputs for execution, which could hinder real-time applications. This article proposes an automatic method for asphalt pavement layer interface detection and thickness determination using GPR. The effects of in-situ noise levels on thickness measurement accuracy were discussed. The Canny edge detector was used to estimate the two-way travel time (TWTT) range. The wavelet transform was used for noise cancellation. Layer interface reflections were identified using the matched filter method for thickness determination. Vibration effect during the continuous GPR survey was mitigated using the empirical mode decomposition (EMD) method. A simulation study was conducted. The proposed method provided more accurate measurements than manual inspection for thickness values from 10.16 cm (4 in.) to 2.54 cm (1 in.). GPR field test was performed, and results were compared to field core thickness measurements. Results show that GPR-measured thickness errors are 6.5 % and 1.6 % using manual inspection and the proposed method, respectively. The proposed method is automatic and can be implemented using existing programming functions, which may enable real-time asphalt pavement thickness determination during GPR surveys.

Fast Fourier transform and multi-Gaussian fitting of XRR data to determine the thickness of ALD grown thin films within the initial growth regime

While a linear growth behavior is one of the fingerprints of textbook atomic layer deposition processes, the growth often deviates from that behavior in the initial regime, i.e., the first few cycles of a process. To properly understand the growth behavior in the initial regime is particularly important for applications that rely on the exact thickness of very thin films. The determination of the thicknesses of the initial regime, however, often requires special equipment and techniques that are not always available. We propose a thickness determination method that is based on X-ray reflectivity (XRR) measurements on double layer structures, i.e., substrate/base layer/top layer. XRR is a standard thin film characterization method. Utilizing the inherent properties of fast Fourier transformation in combination with a multi-Gaussian fitting routine permits the determination of thicknesses down to t≈2 nm. We evaluate the boundaries of our model, which are given by the separation and full width at half maximum of the individual Gaussians. Finally, we compare our results with data from x-ray fluorescence spectroscopy, which is a standard method for measuring ultra-thin films.

Non-spectroscopic Method for Simultaneous Determination of Thickness and Composition via 4D-STEM

Journal Article Non-spectroscopic Method for Simultaneous Determination of Thickness and Composition via 4D-STEM Get access Katsuaki Nakazawa, Katsuaki Nakazawa Institute of Industrial Science, University of Tokyo, Meguro-ku, Tokyo, Japan Search for other works by this author on: Oxford Academic Google Scholar Kazutaka Mitsuishi, Kazutaka Mitsuishi National Institute for Materials Science, Tsukuba, Ibaraki, Japan Search for other works by this author on: Oxford Academic Google Scholar Shin-ichi Amma, Shin-ichi Amma AGC Inc., Yokohama, Kanagawa, Japan Search for other works by this author on: Oxford Academic Google Scholar Teruyasu Mizoguchi Teruyasu Mizoguchi Institute of Industrial Science, University of Tokyo, Meguro-ku, Tokyo, Japan Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 26, Issue S2, 1 August 2020, Pages 240–242, https://doi.org/10.1017/S1431927620013926 Published: 01 August 2020

Adaptive ultrasound reflectometry for lubrication film thickness measurements

Adaptive ultrasound reflectometry methods for lubrication film thickness measurements is of great use for condition monitoring and prognostics of systems which have high repair costs and are remotely located, such as off-shore systems, as they recursively calibrate the incident ultrasound wave. Typical manual calibration requires a constant incident wave over the life-cycle of the system, or until new manual calibration can be conducted. Auto-calibration accounts for the changes in the incident ultrasound wave caused by changing environmental conditions, occurring over longer periods of time. The vision of adaptive ultrasound reflectometry methods is therefore increased robustness of lubrication film thickness measurements in a range of applications. In this article an adaptive scheme is proposed. The scheme is based on a thin-layer time-of-flight method for thickness determination, and an extended Kalman filter for estimation of the incident wave spectrum. The adaptive scheme is experimentally tested, and the feasibility of the algorithm is established, but serious issues regarding the robustness and reliability of the method are revealed by a disturbance analysis. However, the experiments and a theoretical layer phase-lag sensitivity analysis reveal that the estimation of the incident wave phase is of high importance for layer thicknesses above m, and for very thin layers below m the estimation of the magnitude dominates the measurement accuracy. This entails that the research in adaptive schemes should be directed towards phase- or magnitude-tracking performance, depending on the working range of the layer thickness, such that sufficient robustness and reliability of the algorithms can be assured.

A Sensitive and Versatile Thickness Determination Method Based on Non-Inflection Terahertz Property Fitting.

The accuracy of thin-film characterization in terahertz spectroscopy is mainly set by the thickness uncertainty. Physical thickness measurement has limited accuracy for thin-film samples thinner than a few hundreds of micrometers and is sometimes even impossible. The temporal resolution of time-domain terahertz spectrometers is not sufficient to resolve such thin films. Previously reported numerical methods mainly only work for materials with low dispersion and absorption. Here, we propose a novel method for thickness determination by fitting a non-inflection offset exponential function to the material optical properties. Theoretical analysis predicts the best fitting to only be achieved when the correct thickness is given. Transmission measurements on a thin-film polymer, water, and a lactose pallet verify the theory and show the accurate thickness determination and property characterization on materials which are either achromatic or dispersive, transparent or absorptive, featureless or resonant. The measurements demonstrate the best versatility and sensitivity compared to the state-of-art. The method could be widely adapted to various types of research and industrial applications.

ANALYTICAL METHOD FOR DETERMINING THE THICKNESS OF DEPOSITS ON THE INTERNAL SURFACES OF HEAT EXCHANGERS

Using the exact analytical solution of the stationary thermal conductivity problem for a two layer flat wall under inhomogeneous boundary conditions of the first and third kind, an analytical method for thickness determination of the sediment layer on the inner surface of the pipeline wall by the temperature known from the experiment on its outer surface is developed. The thickness of the deposits is found from the solution of the inverse problem by substituting the experimental value of the temperature of the outer surface of the wall into the formula of an accurate analytical solution. According to the results of theoretical studies, the thickness of the deposits was equal to 1.3 cm. Due to the large diameter of the pipeline (0.6 m) and the insignificant thickness of the two layer wall (0.016 m), it was assumed to be flat. The thickness of the deposits according to experimental studies was equal to 1.1 cm. Therefore, the discrepancy between the results of theoretical and experimental studies is 15.3%. The sequence of obtaining a solution to a similar problem for a cylindrical wall is also presented.

Nondestructive determination of film thickness with laser-induced surface acoustic waves**Project supported by the National Natural Science Foundation of China (Grant No. 61571319).

The application of surface acoustic waves (SAWs) for thickness measurement is presented. By studying the impact of film thickness h on the dispersion phenomenon of surface acoustic waves, a method for thickness determination based on theoretical dispersion curve v(fh) and experimental dispersion curve v(f) is developed. The method provides a series of thickness values at different frequencies f, and the mean value is considered as the final result of the measurement. The thicknesses of six interconnect films are determined by SAWs, and the results are compared with the manufacturer’s data. The relative differences are in the range from 0.4% to 2.18%, which indicates that the surface acoustic wave technique is reliable and accurate in the nondestructive thickness determination for films. This method can be generally used for fast and direct determination of film thickness.

Acoustic Method Based on Integrity Coefficient for Testing the Loose Circle of Surrounding Rock

The thickness of the loose circle of surrounding rock is an important index in tunnel support parameter design and rock mass stability evaluation. Accurate and rapid determination of thickness is critical to ensure the safety of underground chamber construction. Field test is the most intuitive and accurate method for thickness determination. Acoustic method is also widely used because of its high precision, low cost, and simple operation. However, existing discriminative standards for analysis of test results are ambiguous and subjective; as such, a uniform standard that defines a loose circle has not been established yet. In this study, the complete degree of rock and loose rock mass is quantitatively analyzed by introducing the concept of and the calculation formula for the integrity coefficient of broken rock (Rv) and the integrity coefficient of loose circle (Lv). According to the formation principle of loose circle, the criteria and test method for surrounding rock loose circle are proposed on the basis of the integrity coefficient. The integrity coefficient of the loose circle (Rv) is assumed to be approximately equal to that of the broken rock (Lv) in chamber excavation. In the test of the surrounding rock loose circle in the Shimen tunnel at Baohan highway, the integrity coefficient (Rv) of the rock of the grade Ⅲ gneiss was 0.53 according to the combined indoor and field tests. The thickness of the type Ⅲ surrounding rock loose circle was 0.55-1.35 m, and the distribution along the circumference was not uniform. The arch shoulder was thick, and the wall was thin, consistent with the initial stress state of the surrounding rock. Comparison with the results of the original acoustic wave loosening test showed that the new discriminant method based on the integrity coefficient is more accurate and reliable. The proposed method could be used for the design and construction of tunnels.

Modification of hypersonic waveriders by vorticity-based boundary layer displacement thickness determination method

For general hypersonic vehicles flying at high altitudes and Mach numbers, the appearance of the large boundary layer displacement thickness can change the pressure distribution and aerodynamic characteristics significantly. As for the waverider, another side effect is that the shock wave position is deflected downward evidently even at the design Mach number, which is adverse for the shock wave being attached to the leading edge and may lead to more leakage of high pressure gas from the lower surface onto the upper surface. Therefore, this paper first develops a vorticity-based method to determine the boundary layer displacement thickness, in combination with the tangent wedge/cone method. Then, trying to alleviate the high pressure gas leakage near the leading edge, modification of a viscous optimized waverider is conducted under the condition of strong viscous interaction, by deducting the corresponding boundary layer displacement thickness from the original lower surface along the normal direction. Results show that the shock wave position around the lower surface of the modified waverider under the condition of strong viscous interaction is very close to that of the inviscid basic flowfield around the original waverider, which means less leakage of high pressure gas. But it's found that such change has little influence on the aerodynamic characteristics of the upper surface. However, an interesting discovery is that due to the lower pressure near the leading edge of the modified lower surface, the wave drag is lowered for the same lift, thus the lift-to-drag ratio is improved. The modified waverider also exhibits higher lift-to-drag ratio at large angles of attack when compared to waveriders with upper expansion surfaces. Overall, a vorticity-based boundary layer displacement thickness determination method is proposed in this paper, which is then used to modify waveriders to achieve higher aerodynamic efficiency.

Thickness determination of TiN and TiAl coatings on steel substrates using X‐ray diffraction method and their composition measurements by GD‐OES

This paper presents a nondestructive X‐ray diffraction method for the accurate determination of thicknesses of polycrystalline TiN and amorphous‐like TiAl coatings deposited by DC magnetron sputtering onto thick polycrystalline stainless steel and carbon steel substrates. This method relies on the measurement of intensity loss of a substrate reflection caused by the deposition of the coating. The uncertainty of the thickness measurements by the X‐ray diffraction depends on the mass absorption coefficient of the coating material and the quality of the collected diffraction patterns. For the coatings considered, thicknesses determined by the X‐ray diffraction method show very good agreement with the thickness values measured by scanning electron microscopy and ball crater techniques.

Determination of Cutting Forces in Grinding with Crossed Axes of Tool and Workpiece

AbstractIn the work the analysis of existent methods of determination of local and general forces of cutting at polishing of surfaces with a type as the arc of circumference is given. The dependence for determination of speed polishing and method for determination of thickness of the cut away layer on condition of equality of the tricked into and taken off volumes of material are offered. The method of determination of cutting forces, which takes into account cutting and deforming grain, is suggested. The method of determining the thickness of a cutting layer of one of the cutting edge, from the condition that the volume of material that is brought and is cut in each local point of contact spots has been proposed. The proposed method takes into account the compliance of the processing system and the discontinuity of the abrasive surface of the tool. By experimental way upper limits of thickness cutting layer when using different abrasive materials for a wide range of cutting speeds have been obtained.

Annular arrays for novel ultrasonic measurement techniques

Abstract. The paper shows how the precise knowledge of the sound field of an ultrasonic annular array can contribute to the development of novel measurement techniques. Emphasis is placed on (a) a non-invasive method for sound velocity measurements in fluids using the echo signals from scattering p]articles, (b) a non-invasive method for the combined determination of thickness and sound velocity in layered structures by using a novel focusing technique, and (c) a non-scanning curvature measurement method exploiting the wave front curvature of a reflected wave. To demonstrate the methods, the principles as well as results of simulations and measurements are discussed.

Characterization of the topography and thickness of gallium thin films by scanning tunneling microscopy

ABSTRACTScanning tunneling microscopy (STM) was employed to characterize the topography of 32 and 4 µm thick gallium films; thicknesses that have not yet been addressed. The STM images revealed submicron grains on both surfaces although a reduced grain density was observed on the thinner film. The granular structure may be explained by a thin gallium oxide layer that acted as an elastic membrane against liquid gallium underneath that expanded during freezing of the sample. We also believe that the same gallium oxide layer is also responsible for an intriguing effect that appears as soon as the tungsten tip lands on the gallium film: the onset of continuous regular z-oscillations of the tip even at rest. This is an effect that we believe has not been previously reported in the literature. We have also demonstrated, for the first time, a new thickness determination method for the gallium film based on an STM image obtained during the solid-to-liquid phase transition.

Image Segmentation Based Determination of Elastane Core Yarn Diameter

Yarn diameter is one of the key knitted fabric parameters, whose accurate determination, however, continues to be a difficult task. The goal of the study presented was to calculate the diameter of dry and wet relaxed yarns with and without incorporated elastane using imageprocessing and -analysis tools implemented in MATLAB. Compared to the images of wet relaxed samples, a much more sophisticated segmentation approach had to be implemented for dry relaxed yarn images due to their weaker yarn-background contrast. The values calculated were compared with those obtained with the conventional yarn thickness determination method developed by Sadikov. Linear correlation between the two techniques was found to be substantial – coefficients of determination for the yarn diameters of the wet and dry relaxed samples were 0.87 and 0.72, respectively. Unlike Sadikov’s method, our newly developed technique calculates yarn core diameter without hairiness.

New method for thickness determination and microscopic imaging of graphene-like two-dimensional materials**Project supported by the State Key Development Program for Basic Research of China (Nos. 2012CB921304, 2013CB632805, 2012CB619306) and the National Natural Science Foundation of China (No. 61474114).

We employed the microscopic reflectance difference spectroscopy (micro-RDS) to determine the layer-number and microscopically image the surface topography of graphene and MoS2 samples. The contrast image shows the efficiency and reliability of this new clipping technique. As a low-cost, quantifiable, no-contact and non-destructive method, it is not concerned with the characteristic signal of certain materials and can be applied to arbitrary substrates. Therefore it is a perfect candidate for characterizing the thickness of graphene-like two-dimensional materials.

A Method For Determination Of Specific Electrical Resistance Of Steel And Nano-Coating Sputtered On It

The paper describes methods developed to determine specific electrical conductivity and relative magnetic permeability of cylindrical steel items and nano-coatings deposited on them by sputtering. Research enables development of a new method for determination of thickness of vacuum deposited nano- coating that is based on application of skin effect.

Thickness determination of electrochemical titanium oxide (Ti/TiO2) formed in HClO4 solutions

Anodic Titanium oxide films were potentiodinamically grown on Ti foil and glass/Ti in 0.010 M HClO4 at 50mVs−1. The current density-potential curves (j−E) showed that the oxide grows according to the physical model for high-field conduction. However, for final potential (Ef) higher than 1.5V vs. Ag/AgCl (sat. KCl) the oxygen evolution reaction becomes more significant, and the formation of bubbles prevented or made more difficult the application of in situ techniques for the simultaneous study of the thickness and optical properties of the anodic layer. We developed a method based on electron probe microanalysis (EPMA) to calculate oxide thickness using ex situ ellipsometry as a reference technique. The normalized intensity of the O Kα peaks was measured for anodic oxides corresponding to Ef values from spontaneous oxide up to 50V, where a linear relationship was observed for a narrower range of final potentials. This behaviour was studied with Monte Carlo simulations. After calibration with ellipsometric results, to take into account sample damage during the electron irradiation, EPMA was applied as a method for thickness determination at Ef ≥ 1.0V. Once the method was established, ex situ thickness determinations became independent of the preparation method of the oxide layer, which represents a comparative advantage against ex situ ellipsometry.

Methods of characterization of synthetic opal films

We developed methods for determination of thickness, number of layers and filling fraction of silica particles for synthetic opals. We show that the filling fraction is considerably less than for ideal close-packed structure, which is important for practical and theoretical applications.

Spectroscopic reflectometry as in‐operando method for thickness determination of anodic oxide films on titanium

The present work focuses on the development of an in‐operando technique based on the visible spectroscopic reflectometry (VSR) for simultaneous determination of the oxide film formation during anodizing. The establishment of the VSR as in‐operando technique requires an extensive validation by comparative in‐situ but non‐operando thickness measurements under aqueous conditions. The investigations were carried out on anodic oxide films on pure titanium. The authors demonstrate the VSR as a simple and robust method for measurement under electrolyte covering. Additionally, an empirical correction algorithm extends the limitation of the visible reflectometry in thin film thickness. Reliable film thickness values can be measured down to ≥5 nm. The in‐operando mode yields additional information about the film growth time resolved. Copyright © 2013 John Wiley & Sons, Ltd.

Simultaneous thickness, velocity, density, and attenuation measurement of a thin layer by time-resolved acoustic microscopy

An ultrasonic method for simultaneous determination of thickness, velocity, density and attenuation of thin layer using a time-resolved acoustic microscopy is proposed. Reflection from the thin layer is represented as a function of three dimensionless parameters which are determined from the experimentally normal incidence component of the two dimensional reflection spectrum R(θ,ω) derived based on the inversion of V(z,t) technique with time-resolved acoustic microscopy. The thickness of the thin layer is derived from the signals received from the layer itself considering the geometrical relations when the lens focused on the sample’s surfaces. The simultaneous determination of thickness, velocity, density and attenuation of thin stainless steel plate by using a point-focusing transducer with nominal frequency of around 50MHz were carried out. The determined material properties are comparable, in which the thickness, velocity and density can be measured with a percentage biases less than 5% and the attenuation is close to its real value. The present preliminary work shows the high efficiency, viability and capability of the new non-destructive technique in simultaneously characterize basic mechanical and geometrical properties of thin layers.