1. Articles in category: NDE/NDT

    1-24 of 314 1 2 3 4 ... 11 12 13 »
    1. 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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    2. 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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    3. 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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    4. Understanding and improving optical coherence tomography imaging depth in selective laser sintering nylon 12 parts and powder

      Understanding and improving optical coherence tomography imaging depth in selective laser sintering nylon 12 parts and powder

      Optical coherence tomography (OCT) has shown promise as a process sensor in selective laser sintering (SLS) due to its ability to yield depth-resolved data not attainable with conventional sensors. However, OCT images of nylon 12 powder and nylon 12 components fabricated via SLS contain artifacts that have not been previously investigated in the literature. A better understanding of light interactions with SLS powder and components is foundational for further research expanding the utility of OCT imaging in SLS and other additive manufacturing (AM) sensing applications. Specifically, in this work, nylon powder and sintered parts were imaged in air and in ...

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    5. Microdefect identification in polymers by mapping depth-resolved phase-difference distributions using optical coherence tomography

      Microdefect identification in polymers by mapping depth-resolved phase-difference distributions using optical coherence tomography

      A novel method for the identification of microdefects in transparent or semi-transparent polymers and polymer composites is established, which maps the depth-resolved phase-difference distribution during polymer deformation using optical coherence tomography (OCT), and detects internal microdefects using the defect-induced phase-difference-distribution anomalies. For validation, epoxy resin, silicone rubber and glass fiber-reinforced resin matrix composite samples with internal defects with different dimensions were measured by using a line-field spectral-domain OCT system. Small defects, which could not be observed from the cross-sectional images, were identified from the measured phase-difference distributions; fibers and microdefects of a similar size in the polymer composites were distinguished ...

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    6. Loquat Bruise Detection Using Optical Coherence Tomography Based on Microstructural Parameters

      Loquat Bruise Detection Using Optical Coherence Tomography Based on Microstructural Parameters

      Slight postharvest bruises of loquats remarkably affect the quality and shelf life of the fruits, but they are difficult to identify using visual inspection. Sub-surface structural changes in cells caused by mechanical injury or impact can be detected using spectroscopy-based methods from different angles. Optical coherence tomography (OCT), a non-destructive technology, can acquire cross-sectional images to analyze sub-surface structures of loquats, thus offering the potential to identify fruit bruises. This study proposes an automated OCT image processing method for extracting large cells from loquat images, which involves a series of steps including image denoising, boundary detection, filtering, binarization, segmentation, and ...

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    7. Non-destructive biomechanical testing of tissues using a vibrational optical coherence tomography setup (Thesis)

      Non-destructive biomechanical testing of tissues using a vibrational optical coherence tomography setup (Thesis)

      The mechanical properties of tissues and implants contribute to their physiological functionality, and have been vast areas of research in fields such as Dermatology, Cardiology, Neurology, Ophthalmology, Orthopedics and Urology. Several tests and modalities have been used to measure the mechanical properties of tissues and implants including tensile, compressive, shear, and bending in one or more axial directions. However, majority of these tests are destructive, rendering the material unusable post-testing; whereas most of the non-destructive imaging modalities such as magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR) and ultrasound are costly and have lower spatial resolution. Optical coherence tomography (OCT ...

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    8. Quantitative discrimination of pearls using polarization-sensitive optical coherence tomography

      Quantitative discrimination of pearls using polarization-sensitive optical coherence tomography

      We propose a robust method that can quantitatively discriminate genuine pearls from imitation ones by introducing the concept of entropy in the polarization-sensitive optical coherence tomography (PS-OCT). Qualitatively, by examining the birefringence properties of the nacre region of pearls with PS-OCT, the genuine pearls can be easily discriminated. To quantify the amount of birefringence formation, however, the concept of phase retardation entropy is introduced, which is expected to have a higher value when a PS-OCT tomogram has more diverse phase retardation values in its histogram. Experimental confirmation demonstrated that the phase retardation entropy of a genuine pearl was always higher ...

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    9. Optical coherence tomography characterization of femtosecond laser manufactured microfluidic circuits

      Optical coherence tomography characterization of femtosecond laser manufactured microfluidic circuits

      Dimensional characterization of microfluidic circuits were performed using three-dimensional models constructed from OCT images of such circuits. Were fabricated microchannels on the same BK7 glass plate, under different laser ablation conditions and substrate displacement velocity in relation to laser beam. Were used the following combination of energy, from 30 μJ to 60 μJ and velocity from 588 mm/min to 1176 mm/min, at 1 kHz laser repetition rate and 40 fs of pulse duration (FWHM). For OCT imaging we used an OCP930SR (Thorlabs System Inc) with 930 nm central wavelength, 6 μm of lateral and axial resolution, and image ...

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    10. Evaluation of the polymerization shrinkage of experimental flowable composite resins through optical coherence tomography

      Evaluation of the polymerization shrinkage of experimental flowable composite resins through optical coherence tomography

      This study evaluated the polymerization shrinkage of two experimental flowable composite resins (CR) with different proportions of Urethane dimethacrylate (UDMA)/triethylene glycol dimethacrylate (TEGDMA) monomers in the organic matrix (50:50 and 60:40, respectively). A commercially available flowable CR, Tetric N-Flow (Ivoclair Vivadent, Liechtenstein, Germany), was employed as the control group. The resins were inserted in a cylindrical teflon mold (7 mm diameter, 0.6 mm height) and scanned with OCT before photoactivation, immediately after and 15 minutes after light-curing (Radii-Cal, SDI, Australia, 1,200 mW/cm 2 ) exposure. A Callisto SD-OCT system (Thorlabs Inc, USA), operating at 930 ...

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    11. Interferometric mapping of material properties using thermal perturbation

      Interferometric mapping of material properties using thermal perturbation

      Optical phase changes induced by transient perturbations provide a sensitive measure of material properties. We demonstrate the high sensitivity and speed of such methods, using two interferometric techniques: quantitative phase imaging (QPI) in transmission and phase-resolved optical coherence tomography (OCT) in reflection. Shot-noise–limited QPI can resolve energy deposition of about 3.4 mJ/cm 2 in a single pulse, which corresponds to 0.8 °C temperature rise in a single cell. OCT can detect deposition of 24 mJ/cm 2 energy between two scattering interfaces producing signals with about 30-dB signal-to-noise ratio (SNR), and 4.7 mJ/cm 2 ...

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    12. Assessment of Ductile, Brittle, and Fatigue Fractures of Metals Using Optical Coherence Tomography

      Assessment of Ductile, Brittle, and Fatigue Fractures of Metals Using Optical Coherence Tomography

      ome forensic in situ investigations, such as those needed in transportation (for aviation, maritime, road, or rail accidents) or for parts working under harsh conditions (e.g., pipes or turbines) would benefit from a method/technique that distinguishes ductile from brittle fractures of metals—as material defects are one of the potential causes of incidents. Nowadays, the gold standard in material studies is represented by scanning electron microscopy (SEM). However, SEM instruments are large, expensive, time-consuming, and lab-based; hence, in situ measurements are impossible. To tackle these issues, we propose as an alternative, lower-cost, sufficiently high-resolution technique, Optical Coherence Tomography ...

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    13. Researchers use non-visible imaging approach to reveal secrets of ancient Egyptian mummies

      Researchers use non-visible imaging approach to reveal secrets of ancient Egyptian mummies

      In addition to the multispectral camera, the team of researchers utilized optical coherence tomography (OCT), which uses similar wavelengths to multispectral imaging, but works at a much smaller scale, according to UCL. The system is arranged so that light travels a similar distance along two paths, one a reference arm and the other interrogating the sample. As light penetrates the sample and reflects back off different layers, the distance it travels changes. This change in distance is measured precisely using interferometry. It can image to depths of around a millimeter and give micrometer resolution, thus making it suitable for imaging ...

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    14. 3D imaging technology inspects hard-to-reach spaces

      3D imaging technology inspects hard-to-reach spaces

      With recent developments in fiber-based optical 3D metrology , the scope of 3D imaging applications has been expanded to include hard-to-reach spaces such as tubes and bores. 3D imaging can be accomplished in various ways, including single and multi-camera methods, structured light systems, laser triangulation, pattern projection, and those based on the Time of Flight principle. 3D vision systems such as these add a new dimension to machine vision systems, bringing the development of new applications for industry. Advances in high-speed fiber-based low-coherence interferometry, a high-resolution 3D measurement technology, have resulted in the development of new in-line inspection applications. One company ...

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    15. Modern acrylic paints probed by optical coherence tomography and infrared reflectography

      Modern acrylic paints probed by optical coherence tomography and infrared reflectography

      Contemporary art is particularly delicate as the synthetic materials used for their realization are of poorer quality and durability than the traditional materials. It follows that the contemporary artworks often require imminent restorations as well as in-depth analytical studies of the constituting materials. The non-invasiveness of the scientific methods is a key issue in the diagnostics of contemporary art because it minimizes the need of sampling. In this respect, the potential of Optical Coherence Tomography (OCT) imaging to probe the internal structure of the commercial acrylic paint layers, as a function of their thickness, was investigated and compared with that ...

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    16. Blackbird, TU Munich, Collaborate for OCT in Auto Manufacturing

      Blackbird, TU Munich, Collaborate for OCT in Auto Manufacturing

      Remote laser welding system manufacturer Blackbird Robotersysteme GmbH is participating in a research project with the Technical University of Munich’s Institute for Machine Tools and Industrial Management and multiple industrial partners to explore optical coherence tomography's potential for remote laser welding in auto manufacturing. The project will investigate innovative technology for more flexibility in body construction, particularly electro mobility. Germany's Federal Ministry of Education and Research is sponsoring the project under the Photonics Research Germany research incentive program. The German government's goal is to advance electromobility. Disappointed electric vehicle sales point to inflexible production structures which ...

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    17. Optical coherence tomography of the first printed edition of Euclid

      Optical coherence tomography of the first printed edition of Euclid

      My last piece of work of 2017 was a treat, and worth resurrecting this blog for. Some time ago, Tabitha Tuckett in UCL Special Collections and I had a stimulating chat which sparked a handful of potentially intriguing projects. Today’s was to see whether we could find any interesting features associated with the printed diagrams in the margins of the first printed edition of Euclid’s Elements . Euclid wrote the Elements in about 300BC and it effectively defined mathematics for the next two thousand years. He wrote it in Greek (some of it is probably a compilation of earlier ...

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    18. Fouling development in direct contact membrane distillation: Non-invasive monitoring and destructive analysis

      Fouling development in direct contact membrane distillation: Non-invasive monitoring and destructive analysis

      Fouling development in direct contact membrane distillation (DCMD) for seawater desalination was evaluated combining in-situ monitoring performed using optical coherence tomography (OCT) together with destructive techniques. The non-invasive monitoring with OCT provided a better understanding of the fouling mechanism by giving an appropriate sampling timing for the membrane autopsy. The on-line monitoring system allowed linking the flux trend with the structure of fouling deposited on the membrane surface. The water vapor flux trend was divided in three phases based on the deposition and formation of different foulants over time. The initial flux decline was due to the deposition of a ...

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    19. Quantification of particulate matter attached to the bulk-biofilm interface and its influence on local mass transfer

      Quantification of particulate matter attached to the bulk-biofilm interface and its influence on local mass transfer

      A large fraction of the chemical oxygen demand (COD) in municipal wastewater is associated with the particulate matter. The presence of these particles might impose a negative impact on the mass transfer in biofilm systems when they attach to the bulk-biofilm interface. We thus investigated the impact of real wastewater particles by combining optical coherence tomography (OCT) and oxygen microsensor measurements. The deposition of wastewater particles of different size classes onto the biofilm surface was captured in 3D by means of OCT in a lab-scale flume. The thickness of the particle layer was calculated from OCT images. The influence of ...

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    20. Defect inspection of actuator lenses using swept-source optical coherence tomography

      Defect inspection of actuator lenses using swept-source optical coherence tomography

      Actuator lens industries have gained an enormous interest with the enhancement of various latest communication devices, such as mobile phone and notebooks. The quality of the aforementioned devices can be degraded due to the internal defects of actuator lenses. Therefore, in this study, we implemented swept-source optical coherence tomography (SS-OCT) system to inspect defects of actuator lenses. Owing to the high-resolution of the SS-OCT system, defected foreign substances between the actuator lenses, defective regions of lenses and surface stains were more clearly distinguished through three-dimensional (3D) and two-dimensional (2D) cross-sectional OCT images. Therefore, the implemented SS-OCT system can be considered ...

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    21. BMW tests optical coherence tomography for better welding

      BMW tests optical coherence tomography for better welding

      Germany’s Federal Ministry of Education and Research (BMBF) has backed a project to explore the potential of optical coherence tomography (OCT) to improve remote laser welding in car production. Funded under the country’s “Photonics Research Germany” program, the effort includes representatives from auto giant BMW, who will work alongside laser welding and OCT experts at Precitec, Blackbird Robotersysteme, Emil Bucher, and the Technical University of Munich. The project utilizes a Blackbird scanner comprising an “intelliWELD” PR scan head provided by Scanlab , a control unit, and an integrated OCT scanner. The team adds that imaging relies on ultra-fast workpiece ...

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    22. Characterization of the Coating and Tablet Core Roughness by Means of 3D Optical Coherence Tomography

      Characterization of the Coating and Tablet Core Roughness by Means of 3D Optical Coherence Tomography

      This study demonstrates the use of optical coherence tomography (OCT) to simultaneously characterize the roughness of the tablet core and coating of pharmaceutical tablets. OCT is a high resolution non-destructive and contactless imaging methodology to characterize structural properties of solid dosage forms. Besides measuring the coating thickness, it also facilitates the analysis of the tablet core and coating roughness. An automated data evaluation algorithm extracts information about coating thickness, as well as tablet core and coating roughness. Samples removed periodically from a pan coating process were investigated, on the basis of thickness and profile maps of the tablet core and ...

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      Mentions: Daniel Markl
    23. Evaluating the effects of organic matter bioavailability on nanofiltration membrane using real-time monitoring

      Evaluating the effects of organic matter bioavailability on nanofiltration membrane using real-time monitoring

      We studied the influence of bioavailability of organic matter on membrane fouling layer development by comparing the filtration of two feed waters (wetland water and graywater). Dissolved organic carbon (DOC) concentration, size exclusion chromatography (SEC), and fluorescence excitation-emission matrix (FEEM) were used to characterize the bioavailability of organic matter in these water samples during the nanofiltration process. The wetland sample contained a high proportion of humic acid- and fulvic acid-like matter with low bioavailability, whereas the graywater sample comprised substantial amounts of aromatic proteins and microbial byproduct-like matter with high bioavailability. In addition, the molecular size distribution revealed that the ...

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    24. Biofouling investigation in membrane filtration systems using Optical Coherence Tomography (OCT) (Thesis)

      Biofouling investigation in membrane filtration systems using Optical Coherence Tomography (OCT)  (Thesis)

      Biofouling represents the main problem in membrane filtration systems. Biofouling arises when the biomass growth negatively impacts the membrane performance parameters (i.e. flux decrease and feed channel pressure drop). Most of the available techniques for characterization of biofouling involve membrane autopsies, providing information ex-situ destructively at the end of the process. OCT, is non-invasive imaging technique, able to acquire scans in-situ and non-destructively. The objective of this study was to evaluate the suitability of OCT as in-situ and non-destructive tool to gain a better understanding of biofouling behavior in membrane filtration systems. The OCT was employed to study the ...

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