1. Articles in category: NDE/NDT

    1-24 of 335 1 2 3 4 ... 12 13 14 »
    1. A marine biofilm flow cell for in situ screening marine fouling control coatings using optical coherence tomography

      A marine biofilm flow cell for in situ screening marine fouling control coatings using optical coherence tomography

      A novel fouling marine flow cell was designed and fitted with a clear plastic lid to allow real-time imaging of biofilms using optical coherence tomography (OCT). Marine biofilms were grown under controlled shear flow on coupons coated with 6 different biocidal antifouling coatings (SPC1, SPC2, SPC3, SPC4, CDP1 and CDP2, AkzoNobel) and one inert coating which contained no biocidal actives (NB-D) for 8 weeks. One set of coupons coated with NB was statically immersed in sea water during the same time period (NB-S). Biofilm removal was assessed by increasing the flow velocity while OCT simultaneously measured the biofilm cross-sectional area ...

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    2. Gravity-Driven Flows in Two-Fluid Drops

      Gravity-Driven Flows in Two-Fluid Drops

      The direction in which fluid circulates in binary drops doesn't change when the drops are tilted, implicating gravity—not surface tension—as the driver of flow in these systems. rops of spilled coffee dry and leave behind ring-shaped patterns. The shape and uniformity of these patterns are determined by fluid flows that drive particle deposition within the drops. Now, Fouzia Ouali of Nottingham Trent University in the UK and colleagues have shown that in the case of drops composed of two fluids, gravity, not surface tension, as researchers previously thought, dominates convective flows. The team says that this result ...

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    3. Density-Driven Flows in Evaporating Binary Liquid Droplets

      Density-Driven Flows in Evaporating Binary Liquid Droplets

      In the evaporation of microlitre liquid droplets, the accepted view is that surface tension dominates and the effect of gravity is negligible. We report, through the first use of rotating optical coherence tomography, that a change in the flow pattern and speed occurs when evaporating binary liquid droplets are tilted, conclusively showing that gravitational effects dominate the flow. We use gas chromatography to show that these flows are solutal in nature, and we establish a flow phase diagram demonstrating the conditions under which different flow mechanisms occur.

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    4. Biophotonic approach for the characterization of initial bitter-rot progression on apple specimens using optical coherence tomography assessments

      Biophotonic approach for the characterization of initial bitter-rot progression on apple specimens using optical coherence tomography assessments

      The tremendous advances achieved in the biophotonics technologies have intensified the necessity for non-invasive modalities that can characterize diverse biological materials with increased sensitivity and resolution. Optical coherence tomography (OCT) is one of the techniques that has been applied for biological applications in medicine and agriculture to identify structural properties. Herein, we report the successful incorporation of OCT for the identification of morphological changes that occur as a result of the bitter rot disease, through continuous detection of structural changes. Detailed inner morphological structural changes occurring in fruit specimens were precisely analyzed as a function of the disease incubation period ...

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    5. Investigation of Puccinia triticina contagion on wheat leaves using swept source optical coherence tomography

      Investigation of Puccinia triticina contagion on wheat leaves using swept source optical coherence tomography

      We present an investigation on applicability of swept-source optical coherence tomography (SSOCT) to examine the internal structures of plant leaves. This study helps to identify the growth and spread of the leaf rust disease in leaves of wheat plants, caused by Puccinia triticina . The epidermal cell layer and parenchyma cell layer of the acquired OCT images are correlated with the histological images to show distinctive leaf morphological boundaries. In the OCT images, the thickness of the parenchyma cell layer in healthy and infected samples are compared and analyzed. Accurate morphological and quantitative information are obtained with our developed system for ...

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      Mentions: Raju Poddar
    6. Visualization of Ink Fluidity in Inkjet Imaging Process Using Method of Optical Coherence Tomography

      Visualization of Ink Fluidity in Inkjet Imaging Process Using Method of Optical Coherence Tomography

      In order to enhance the performance of the inkjet printer, it is important to be able to appropriately control the ink fluidity in the imaging process. For examples, it is useful to know how the ink fluidity changes when inside the inkjet head or when adhering to the media. As a method that can be used for this judgment, it was attempted to use method of optical coherence tomography was attempted. It is clarified that the fluidity distribution and its time change inside the ink can be visualized by optical measurement and signal analysis. It will bring way to know ...

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    7. Determination of mechanical properties of biofilms by modeling the deformation measured using optical coherence tomography

      Determination of mechanical properties of biofilms by modeling the deformation measured using optical coherence tomography

      The advantage of using non-invasive imaging such as optical coherence tomography (OCT) to asses material properties from deformed biofilm geometries can be compromised by the assumptions made on fluid forces acting on the biofilm. This study developed a method for the determination of elastic properties of biofilms by modelling the biofilm deformation recorded by OCT imaging with poroelastic fluid-structure interaction computations. Two-dimensional biofilm geometries were extracted from OCT scans of non-deformed and deformed structures as a result of hydrodynamic loading. The biofilm geometries were implemented in a model coupling fluid dynamics with elastic solid mechanics and Darcy flow in the ...

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    8. Feature Of The Week 08/31/2018: Spectroscopic Characterization of Si/Mo Thin-film Stack at Extreme Ultraviolet Range

      Feature Of The Week 08/31/2018: Spectroscopic Characterization of Si/Mo Thin-film Stack at Extreme Ultraviolet Range

      Using extreme ultraviolet (EUV) radiation for nanoscale imaging has recently seen much interest. As actinic patterned mask inspection tools are not available, chipmakers have to rely on wafer inspection to identify mask defects. To fulfill the requirements of mask inspection, EUV sources with high brightness, high stability (spatial and temporal), and cost effectiveness are needed. In a laser-produced-plasma (LPP) generated EUV system, a high-intensity laser beam is focused onto a tin target to form a hot plasma, which emits ultraviolet light. In this study, a fiber-laser excitation source was used to generate stable 13.5-nm EUV for spectroscopic optical coherence ...

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    9. Characterisation of textured surfaces under a laminar flow by Optical Coherence Tomography (Thesis)

      Characterisation of textured surfaces under a laminar flow by Optical Coherence Tomography (Thesis)

      Textured surfaces are present everywhere in nature and in our daily life, interacting constantly with a flow. In this report, we focus on how a textured surface with pillars responds to a laminar flow inside a confined channel. The study is mainly focused on the measurements of the bending of the pillars and of the velocity field, using optical coherence tomography. The potential of this technique, which is not very common in microfluidics, is explored here to characterise our system and its limits are discussed. The measurements of the bending and of the velocity field allow to get the value ...

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    10. Integrating optical coherence tomography with gravimetric and video analysis (OCT-Gravimetry-Video method) for studying the drying process of polystyrene latex system

      Integrating optical coherence tomography with gravimetric and video analysis (OCT-Gravimetry-Video method) for studying the drying process of polystyrene latex system

      Latex, an aqueous dispersion of sub-micron polymer particles, is widely used as polymer binder in waterborne coatings and adhesives. Drying of a latex is inhomogeneous, during which the spatial distribution of particles is non-uniform and changes with time, usually resulting in a compromise of the integrity of a dried film. To study drying inhomogeneity of latex, we developed a system integrating optical coherence tomography (OCT) with gravimetric and video analysis (OCT-Gravimetry-Video method) to non-destructively monitor the drying process of non-film-forming latexes consisting of hard polystyrene spheres over time. OCT structural and speckle images of the latex’s internal structure show ...

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    11. Effect of biofilm structural deformation on hydraulic resistance during ultrafiltration: A numerical and experimental study

      Effect of biofilm structural deformation on hydraulic resistance during ultrafiltration: A numerical and experimental study

      Biofilm formation in membrane systems negatively impacts the filtration system performances. This study evaluated how biofilm compression driven by permeate flow increases the hydraulic resistance and leads to reduction in permeate flux. We analysed the effect of biofilm compression on hydraulic resistance and permeate flux through computational models supported by experimental data. Biofilms with homogeneous surface structure were subjected to step-wise changes in flux and transmembrane pressure during compression and relaxation tests. Biofilm thickness under applied forces was measured non-invasively in-situ using optical coherence tomography (OCT). A numerical model of poroelasticity, which couples water flow through the biofilm with biofilm ...

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    12. Optical Coherence Tomography for NDE (Book Chapter)

      Optical Coherence Tomography for NDE (Book Chapter)

      Optical coherence tomography (OCT) is a noninvasive, high-resolution, interferometric imaging modality using near-infrared light to acquire cross sections and three-dimensional images of the subsurface microstructure of samples. Because of the rapid enhancement of OCT with respect to acquisition speed and axial resolution over the past years, OCT is becoming more and more attractive for applications in nondestructive testing and evaluation. In this chapter, a brief introduction to the technique and the instrumentation is first given, followed by an overview of application of OCT in NDE reported so far.

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    13. Spectroscopic characterization of Si/Mo thin-film stack at extreme ultraviolet range

      Spectroscopic characterization of Si/Mo thin-film stack at extreme ultraviolet range

      A noninvasive method for characterizing Si/Mo thin-film stack thickness and its complex transfer function using common-path optical coherence tomography is proposed, analyzed, and experimentally demonstrated. A laser-produced plasma (LPP)-based extreme ultraviolet (EUV) source was excited by a four-stage nanosecond Yb:fiber laser amplifier with a pulse energy of 1.01 mJ. The tabletop LPP EUV source was compact and stable for generating the EUV interference fringes. The measured complex transfer function of the Si/Mo stack was verified near the pristine 13.5-nm wavelength range.

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    14. Non-Destructive Classification of Diversely Stained Capsicum annuum Seed Specimens of Different Cultivars Using Near-Infrared Imaging Based Optical Intensity Detection

      Non-Destructive Classification of Diversely Stained Capsicum annuum Seed Specimens of Different Cultivars Using Near-Infrared Imaging Based Optical Intensity Detection

      The non-destructive classification of plant materials using optical inspection techniques has been gaining much recent attention in the field of agriculture research. Among them, a near-infrared (NIR) imaging method called optical coherence tomography (OCT) has become a well-known agricultural inspection tool since the last decade. Here we investigated the non-destructive identification capability of OCT to classify diversely stained (with various staining agents) Capsicum annuum seed specimens of different cultivars. A swept source (SS-OCT) system with a spectral band of 1310 nm was used to image unstained control C. annuum seeds along with diversely stained Capsicum seeds, belonging to different cultivar ...

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    15. Microscale light management and inherent optical properties of intact corals studied with optical coherence tomography

      Microscale light management and inherent optical properties of intact corals studied with optical coherence tomography

      Coral reefs are highly productive photosynthetic systems and coral optics studies suggest that such high efficiency is due to optimised light scattering by coral tissue and skeleton. Here, we characterise the inherent optical properties, i.e., the scattering coefficient, μ s , and the anisotropy of scattering, g , of 8 intact coral species using optical coherence tomography (OCT). Specifically, we describe light scattering by coral skeletons, coenoarc tissues, polyp tentacles and areas covered by fluorescent pigments (FP). Our results reveal that light scattering between coral species ranges from μ s = 3 mm -1 ( Stylophora pistillata ) to μ s = 25 mm -1 ( Echinopora lamelosa ). For ...

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    16. Depth-resolved measurement of the compression displacement fields on the front and rear surfaces of an epoxy sample

      Depth-resolved measurement of the compression displacement fields on the front and rear surfaces of an epoxy sample

      Compression is one of the typical parameters measured in material mechanics. In this research, the compression displacement fields on the front and rear surfaces of an epoxy sample are measured by using a tilt depth-resolved wavenumber-scanning Michelson interferometer. The light source is a distributed feedback laser diode, the wavenumber of which can be modulated to about 1.017 × 104 m–1 by the temperature without mode hopping. A random-sampling Fourier transform is designed to evaluate the phase differences before and after the applied loads. Experimental results show that the depth-resolved measurement of the compression displacement field is of high accuracy ...

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    17. Non-destructive and non-contact measurement of semiconductor optical waveguide using optical coherence tomography with a visible broadband light source

      Non-destructive and non-contact measurement of semiconductor optical waveguide using optical coherence tomography with a visible broadband light source

      We demonstrated non-destructive and non-contact measurement of semiconductor optical waveguide using optical coherence tomography with a visible broadband light source (vis-OCT). Vis-OCT can provide high axial and lateral resolutions of less than 1 µm, which were effective for measurement of optical waveguides with several-micrometer structure. We obtained cross-sectional images of ridge-type optical waveguides (RWGs) fabricated as test samples and measured the height and width of the RWGs. The height and width measured by vis-OCT were similar to these values measured by scanning electron microscopy. These results indicated that vis-OCT enables measurement of the height and width of optical waveguides without ...

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    18. Bacterial inactivation and in situ monitoring of biofilm development on graphene oxide membrane using optical coherence tomography

      Bacterial inactivation and in situ monitoring of biofilm development on graphene oxide membrane using optical coherence tomography

      In an attempt to advance GO-based environmental applications, herein we probed the anti-biofouling properties and mechanisms of graphene oxide (GO) surface coating. A flexible and mechanically stable GO membrane was fabricated using vacuum filtration technique and its ability to inactivate bacterial growth and subsequent biofilm formation was investigated. Our preliminary results authenticate that the GO membrane, owing to its unique physicochemical surface properties, exhibits superior antibacterial activity against planktonic cell proliferation. An optical coherence tomography (OCT)-based nondestructive in situ monitoring of bacterial biofilm evolution and behavior revealed that the GO surface initially inhibited biofilm growth for 24 h under ...

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    19. Evaluation of fouling in nanofiltration for desalination using a resistance-in-series model and optical coherence tomography

      Evaluation of fouling in nanofiltration for desalination using a resistance-in-series model and optical coherence tomography

      Resistance-in-series models have been applied to investigate fouling behavior. However, it is difficult to model the influence of morphology on fouling behavior because resistance is indirectly calculated from the water flux and transmembrane pressure. In this study, optical coherence tomography (OCT) was applied to evaluate the resistance of the fouling layer based on fouling morphology. Sodium alginate, humic acid, and bovine serum albumin (BSA) with high salts concentrations (conductivity: 23 mS/cm) were used as model foulants. At the same total fouling resistance, BSA showed the highest cake layer thickness (BSA (114.5 μm) > humic acid (53.5 μm) > sodium ...

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    20. Quality assessment of the optical thin films using line field spectral domain optical coherence tomography

      Quality assessment of the optical thin films using line field spectral domain optical coherence tomography

      Cross-sectional and three-dimensional images show the effectiveness of the system. In this study, the industrial inspection of optical thin film on touch screen panels was demonstrated using line field spectral domain optical coherence tomography. The conventional Fourier domain optical coherence tomography system requires a single scanner for two-dimensional cross-sectional images and two scanners for volumetric images. Our developed line field spectral domain optical coherence tomography has the advantage of needing only a single scanner for volumetric images, while two-dimensional cross-sectional images are obtained by the parallel acquisition of an illuminated line on a sample using an area camera. Further, the ...

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    21. In vivo automated quantification of quality of apples during storage using optical coherence tomography images

      In vivo automated quantification of quality of apples during storage using optical coherence tomography images

      Moisture content is an important feature of fruits and vegetables. As 80% of apple content is water, so decreasing the moisture content will degrade the quality of apples (Golden Delicious). The computational and texture features of the apples were extracted from optical coherence tomography (OCT) images. A support vector machine with a Gaussian kernel model was used to perform automated classification. To evaluate the quality of wax coated apples during storage in vivo , our proposed method opens up the possibility of fully automated quantitative analysis based on the morphological features of apples. Our results demonstrate that the analysis of the ...

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    22. Evaluating the effect of different draw solutes in a baffled osmotic membrane bioreactor-microfiltration using optical coherence tomography with real wastewate

      Evaluating the effect of different draw solutes in a baffled osmotic membrane bioreactor-microfiltration using optical coherence tomography with real wastewate

      This study investigated the performance of an integrated osmotic and microfiltration membrane bioreactor for real sewage employing baffles in the reactor. To study the biofouling development on forward osmosis membranes optical coherence tomography (OCT) technique was employed. On-line monitoring of biofilm growth on a flat sheet cellulose triacetate forward osmosis (CTA-FO) membrane was conducted for 21 days. Further, the process performance was evaluated in terms of water flux, organic and nutrient removal, microbial activity in terms of soluble microbial products (SMP) and extracellular polymeric substance (EPS), and floc size. The measured biofouling layer thickness was in the order sodium chloride ...

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    23. In situ biofilm quantification in Bioelectrochemical Systems using Optical Coherence Tomography

      In situ biofilm quantification in Bioelectrochemical Systems using Optical Coherence Tomography

      Detailed studying of microbial growth in bioelectrochemical systems is required for their proper design and operation. Here we report on the use of Optical Coherence Tomography (OCT) as a tool for in situ and non‐invasive quantification of biofilm growth on electrodes (bioanodes). An experimental platform is designed and described in which transparent electrodes are used to allow for real‐time, three‐dimensional biofilm imaging. The accuracy and precision of the developed method is assessed by relating OCT results to well‐established standards for biofilm quantification (COD and Total N) and show high correspondence to these standards. Biofilm thickness as ...

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