subsurface defects

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Full-Scale Study of Infrared Thermography for Assessing Surface and Subsurface Defects in Pavements and Other Civil Infrastructure

Full-Scale Study of Infrared Thermography for Assessing Surface and Subsurface Defects in Pavements and Other Civil Infrastructure

For subsurface inspection, we were able to study the ability of thermography to locate defects underneath the surface of concrete specimens. Studying the effect of delamination depth on the temperature gradient will assist the better understanding of the effectiveness of thermography in monitoring applications. By using processed thermal images, we were able to detect the presence of air voids underneath concrete structures. We investigated the effect of the depth of these subsurface defects based on the processed images. It was found that the depth in which the defect is located has a major effect on how well it can be recognized by the thermal camera. The best results were acquired from defects that were imbedded close to the surface, up to 5 mm with an accuracy of more than 70%. A computer simulation of the test showed the same trend as seen inside the laboratory.
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The Use of Computed Tomography to Analyse Grinding Smudges and Subsurface Defects in Roller Bearing Rings

The Use of Computed Tomography to Analyse Grinding Smudges and Subsurface Defects in Roller Bearing Rings

This article shows that changes occurring on the surface of roller bearings in the form of grinding smudges stem from the subsurface material defects of these elements. The authors discuss how the smudges are created and show the results of computed tomography tests conducted for roller bearing rings with the above-mentioned defects. The ring reconstruction images are presented, and the defects are located and described with the use of reverse engineering. The defects identified are presented in radiographs. The topography tests confirmed the existence of subsurface defects that emerge on the surface in the form of smudges, once the grinding of an element starts.
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Study of Surface and Subsurface Defects in Materials by Photothermal Deflection Technique: Theory and Experience

Study of Surface and Subsurface Defects in Materials by Photothermal Deflection Technique: Theory and Experience

Photothermal deflection is widely used to study defects in materials. Both high spatial resolution and high sensitivity are required to detect them. In order to improve the theoretical model in the case of uniform heating (one dimensional heat treatment) we have chosen to heat the sample by a halogen lamp. The sample which contains a known surface and subsurface defects is first covered by a thin graphite layer and placed in air. The sample fixed on a vertical holder is able to move in the x and y directions thanks a two stepper motors. The measurement showed excellent agreement be- tween experimental and simulation results.
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Determining the dimension of subsurface defects by active infrared thermography – experimental research

Determining the dimension of subsurface defects by active infrared thermography – experimental research

the machine vision concept. To achieve the objective, that is flaw parameter assessment and automatic defect reporting, some extra techniques are coded, i.e. background estimation and contrast improvement, object labelling, fitting the experi- mental data to the 1-D analytical model of physical behaviour in order to estimate the defect depth and thermal properties with respect to those of the inspected material. The decision is based on the information extracted and evaluated from the region of interest. The advanced features are focused on fea- ture extraction, classification, and reporting. The algorithm of the defect depth estimation requires two input parameters: a thermal mismatch factor 0, also referred to as the ther- mal reflection coefficient (Osiander and Maclachlan Spicer, 1998), and diffusivity of the tested material. The IR Defect Detector offers the functionality of determining the sign of the factor 0 for each defect on the basis of the filtered con- trast (FC) sign or the relative incremental filtered contrast (RIFC; both described below) obtained for areas above the defects, based on a processed thermogram. The 0 sign was described verbally as a relation between the thermal proper- ties of the defect with respect to those of the tested material sample, i.e. “defect is thermal insulator/conductor ...”. For 0 < 0, the defect is a “thermal insulator”, and for 0 > 0 it is a “thermal conductor”. The absolute value of the mismatch factor 0 must be predicted by the user based on expert knowl- edge about the types of materials, i.e. an object that is being tested and non-homogeneity. The 0 factor is determined by the differences between the effusivities of the contiguous ma- terials. The larger the difference, the higher the thermal sig- nature of the nonhomogeneities. However, it is limited to a range < −1, 1 >.
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Methods for Detection of Subsurface Damage: A Review

Methods for Detection of Subsurface Damage: A Review

Eddy current detection (ECD) is an efficient non- destructive method for detection of surface and sub- surface defects in conductive materials. Eddy currents are loops of electrical current induced by an alternat- ing magnetic field in a conductor due to Faraday’s law of induction. In ECD, an ECD probe applies an excitation magnetic field to a part being detected to induce eddy currents in the part. The eddy currents create a magnetic field that reacts back on the excitation field, which results in a change in the impedance of the probe. Thus, a surface or subsurface defect can be detected based on the change in the impedance. ECD is widely applied to detecting subsurface defects [110] and residual stresses [111]. HE et al. proposed the induction thermography [112] and the eddy current pulse phase thermography [113] to detect SSD in steels and carbon fiber reinforced plastics. Practi- cally, ECD has a limited application to the conductive and non-ferromagnetic materials, such as titanium alloys, alu- minum alloys and carbon fiber reinforced composites.
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Machine learning based automatic defect 
		detection in non stationary thermal wave imaging

Machine learning based automatic defect detection in non stationary thermal wave imaging

Detection of subsurface non uniformity is crucial in deciding the strength of objects for various industrial applications. Non stationary thermal wave imaging is emerging as a reliable qualitative assessment procedure to detect anomalies in a wide range of materials. This paper proposes a supervised machine learning based classification modality to detect the subsurface defects using quadratic frequency modulated thermal wave imaging and experimentation has been carried over glass fibre reinforced polymer material (GFRP) with 10 Teflon patches having different depths and sizes and Carbon fibre reinforced polymer (CFRP) with 25 bottom holes having different sizes and depths. In this paper three well known supervised machine learning techniques, Decision tree (DT), Support vector machine (SVM) and k-nearest neighbour (KNN) classifiers are used for defect detection. Detection capability and reliability of defect detection have been assessed using signal to noise ratio and probability of detection respectively.
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Subsurface exploration: engineering geophysics

Subsurface exploration: engineering geophysics

Observations are normally made on a grid. The station interval along each traverse line forming the grid should not exceed the expected dimensions of the feature to be located. A station interval of between 1 and 2m is normally used for the location of abandoned mineshafts. For the location of clay filled sink holes in chalk McDowell (1975) suggests a station interval (and distance between traverses) of less than half the expected lateral extent of the feature. The field data must be corrected for diurnal and secular variations in the Earth’s magnetic field. Diurnal variation is measured throughout the survey by periodically returning to a base station and measuring the field strength. The field data once corrected for these variations are normally presented in the form of a contoured magnetic map. Figure 4.4 shows a magnetic map for a site at Mangotsfield, Bristol. The contour values are relative to the regional magnetic field strength. Characteristic shapes may be recognized from magnetic maps and related to subsurface bodies in terms of general geometry and orientation (if they are not equidimensional) magnetic profiles are often drawn across anomalies to aid interpretation.
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Role of Copy Number Variants in Structural Birth Defects

Role of Copy Number Variants in Structural Birth Defects

Genome-wide scanning has enabled researchers and clinicians to detect potentially pathogenic aberrations in children with normal karyotypes. Al- though the optimal approach for detecting CNVs is in fl ux, and the con- fi dence with which particular ones can be declared pathogenic continues to improve, it is already clear that certain CNVs are clinically signi fi cant and critical to understanding birth defects. To that end, a multicenter National Institutes of Health study led by Ronald Wapner at Columbia University is cur- rently conducting a blinded prospec- tive comparison of prenatal detection rates of cytogenetic abnormalities by using microarray versus metaphase
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Water discharge and nutrient leaching from organic mixed crop rotation

Water discharge and nutrient leaching from organic mixed crop rotation

Water discharge and nutrient leaching studies were conducted in an experimental field under organic farming practice for 20 years. The experimental field is located on a moraine soil in Juva, eastern Finland. The soil profile was undisturbed since subsurface drainage in 1989. The six-year crop rotation (5.9 ha) consists of spring cereal with undersown grass seeds (1st year), two-year grassland (2nd and 3rd), winter cereal (4th), green manure (5th) and spring cereal (6th). The water discharge measurements cover five years out of the six-year crop rotation each year (in 2005, the 6th year plot was missing) and the area covers 4.9 ha.
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Advances in Real-Time Skin Rendering

Advances in Real-Time Skin Rendering

• We would like to apply the subsurface scattering We would like to apply the subsurface scattering effects using PRT to our shadow mapped lighting. effects using PRT to our shadow map[r]

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A study to assess the functional and aesthetic outcome of soft tissue reconstruction of leg and foot defects using conventional and microvascular free flap techniques

A study to assess the functional and aesthetic outcome of soft tissue reconstruction of leg and foot defects using conventional and microvascular free flap techniques

I, Dr. S. Mahesh Kumar solemnly declare that dissertation titled “A STUDY TO ASSESS THE FUNCTIONAL AND AESTHETIC OUTCOME OF SOFT TISSUE RECONSTRUCTION OF LEG AND FOOT DEFECTS USING CONVENTIONAL AND MICROVASCULAR FREE FLAP TECHNIQUES” is a bonafide work done by me at Govt. Stanley Medical College & Hospital during September 2010 to August 2012 under the guidance and supervision of Prof. Dr. J. MOHAN, M.S, M.Ch (Plastic Surgery) and Head of the Department.

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Modeling subsurface hydrology in floodplains

Modeling subsurface hydrology in floodplains

In this paper, we introduce HaughFlow, a light-weight, flexible model which couples the one-dimensional Richards equation (Richards, 1931) for vertical moisture transport, with the Boussinesq equation (Boussi- nesq, 1904) for lateral saturated flow perpendicular to the river channel. HaughFlow is a modern, more flexi- ble version of the Pikul et al. (1974) model, with an optimization procedure for calibrating key parameters and capability for a range of output data visualizations. HaughFlow requires minimal inputs, ensuring model application is as simple as possible. The simplicity of the model structure allows us to investigate the roles of each subsurface flow component, and to specifically identify the influence of a shallow hyporheic- dominated water table on patterns of soil-water saturation throughout the vadose zone. HaughFlow assumes lateral hyporheic flow is the dominant driver of water table levels in the riparian corridor; the model is thus applicable to floodplains where the river and groundwater are hydraulically connected. A source/sink term in the Boussinesq equation, as described by Zucker et al. (1973) and Pikul et al. (1974), is used to fully represent the interplay between the vadose and phreatic zones. This term allows the soil- moisture conditions in the vadose zone to influence water table dynamics. A capillary fringe, induced by boundary conditions at the water table, allows for water table contributions to soil-moisture in the vadose zone.
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SUBSURFACE INVESTIGATION and FOUNDATION RECOMMENDATIONS

SUBSURFACE INVESTIGATION and FOUNDATION RECOMMENDATIONS

Changes in the water content o f these soils may cause the soil to swell or shrink, which may cause movement or cracking o f slabs.. Potential water sources include but are not limit[r]

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Subsurface Oceans of Galilean Moons

Subsurface Oceans of Galilean Moons

We have entered a new era in the exploration of the Sun and its effects on interplanetary space with the launch of two spacecraft: NASA ’ s Parker Solar Probe which is travelling far c[r]

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CRYSTAL DEFECTS: Point defects

CRYSTAL DEFECTS: Point defects

10/11/2004 Ettore Vittone- Fisica dei Semiconduttori - Lectio XIII 11 Sources used for silicon doping:.. High temperature are needed to give sufficient mobility to adsorbed atoms for f[r]

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Petroleum and natural gas industries Well integrity standard

Petroleum and natural gas industries Well integrity standard

 The journey of improving well integrity started with API 14 series for well safety systems, by introducing standards for subsurface safety systems, like storm chokes, subsurface safe[r]

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Workshop to develop deep-life continental scientific drilling projects

Workshop to develop deep-life continental scientific drilling projects

ied in freshwater lakes, soils, surface sediments and, more recently, marine deep subsurface sediments (Nagano et al., 2010; Edgcomb et al., 2011), but are currently not known to be important players in the continental subsurface. In the ma- rine deep subsurface, fungi appear to be reducing nitrate and degrading lignin (Cathrine and Raghukumar, 2009; Guber- natorova and Dolgonosov, 2010), and have been reported in biological samples collected from the deep continental sub- surface (Sinclair and Ghiorse, 1989; Reitner et al., 2005). Other eukaryotic components found in the deep continen- tal biosphere include yeasts (Ekendahl et al., 2003), protists (Sinclair and Ghiorse, 1989), and nematodes (Borgonie et al., 2011). Exploration for these ecologically important, but nu- merically less abundant, members of subsurface ecosystems will require the capability of accessing high volume subsur- face material (fluids and/or solids) from any proposed ICDP site.
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An ionic limit to life in the deep subsurface

An ionic limit to life in the deep subsurface

Little is known about the variability in brine composition in evaporite deposits and their impact on deep subsurface microbiology. Work carried out on the microbial communities in evaporite sequences has generally focused on halite-rich environments. In these environments both halophilic archaea and bacteria have been identified, with the order Halobacteriales being a prominent feature (e.g., Denner et al., 1994; Vreeland et al., 2000; Radax et al., 2001; Fish et al., 2002; Stan-Lotter et al., 2002; Mormile et al., 2003; Gruber et al., 2004). Gypsum horizons found 200 m below the Dead Sea were also found to contain Halobacteriales (Thomas et al., 2014). Whilst the literature on deep subsurface halite-rich environments is limited, it is worth noting that evaporite sequences consist of many soluble salt minerals assemblages that include no or little halite. Therefore, waters through the entire evaporite sequence will be more chemically diverse than those typically encountered in the halite dominated sections.
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Probing the subsurface of the two faces of Iapetus

Probing the subsurface of the two faces of Iapetus

Abstract. Saturn’s moon Iapetus, which is in synchronous rotation, is covered by an optically dark material mainly on its leading side, while its trailing side is significantly brighter. Because longer wavelengths probe deeper into the sub- surface, observing both sides at a variety of wavelengths brings to light possi- ble changes in thermal, compositional, and physical properties with depth. We have observed Iapetus’s leading and trailing hemispheres at 1.2 and 2.0 mm, using the NIKA2 camera mounted on the IRAM 30-m telescope, and compared our observations to others performed at mm to cm wavelengths. We calibrate our observations on Titan, which is simultaneously observed within the field of view. Due to the proximity of Saturn, it is sometimes difficult to separate Iape- tus’s and Titan’s flux from that of Saturn, detected in the telescope’s side lobes. Preliminary results show that the trailing hemisphere brightness temperatures at the two wavelengths are equal within error bars, unlike the prediction made by Ries (2012)[1]. On the leading side, we report a steep spectral slope of increas- ing brightness temperature (by 10 K) from 1.2 to 2.0 mm, which may indicate rapidly varying emissivities within the top few centimeters of the surface. Com- parison to a diffuse scattering model and a thermal model will be necessary to further constrain the thermophysical properties of the subsurface of Iapetus’s two faces.
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Evaluating Roadway Subsurface Drainage Practices

Evaluating Roadway Subsurface Drainage Practices

An extensive literature review was performed covering national-level and state-level research studies mainly focusing on the effects of subsurface drainage on performance of asphalt and concrete pavements. Several studies concerning the effects of a recycled portland cement concrete (RPCC) subbase on PCC pavement drainage systems were also reviewed. A detailed forensic test plan was developed in consultation with the project technical advisory committee (TAC) for inspecting and evaluating the Iowa pavement subdrains. Field investigations were conducted on 64 selected (jointed plain concrete pavement/JPCP and hot-mix asphalt/ HMA) pavement sites during the fall season of 2012 and were mainly focused on the drainage outlet conditions. Statistical analysis was conducted on the compiled data from field investigations to further investigate the effect of drainage on pavement performance.
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