Chemie und Prozesstechnik
Filtern
Erscheinungsjahr
- 2022 (36) (entfernen)
Dokumenttyp
- Beitrag zu einem Tagungsband (36) (entfernen)
Sprache
- Englisch (36) (entfernen)
Schlagworte
- Concrete (5)
- Non-destructive testing (4)
- LIBS (3)
- NDT (3)
- Ultrasound (3)
- Air-coupled ultrasound (2)
- Circular economy (2)
- Civil engineering (2)
- DLP (2)
- DMD (2)
- Dimensional metrology (2)
- Inspection (2)
- Internal defects (2)
- Material classification (2)
- Nondestructive testing (2)
- Open Guided Waves Platform (2)
- Recycling (2)
- Super resolution (2)
- Thermography (2)
- Ultrasonic Guided Waves (2)
- Acoustic damping (1)
- Additive manufacturing (1)
- Additive manufacturing of concrete (1)
- Aeroacoustics (1)
- Ait-coupled ultrasound (1)
- Algorithmic Differentiation (1)
- Artificial Neural Network (1)
- Atmospheric pressure discharges (1)
- Basic qualification (1)
- Bingham fluid (1)
- Bistable amplifier (1)
- Bridge (1)
- Building materials (1)
- CT (1)
- CT simulation, spherical step-wedge (1)
- Calibrated reference standards (1)
- Capillary conductivity (1)
- Cascade impactor (1)
- Certification (1)
- Chlorine (1)
- Competencies (1)
- Composites (1)
- Computed Tomography (1)
- Conformity assessment (1)
- Conformity assessment body (1)
- Conical hole sheet (1)
- Contact area (1)
- Corrosion (1)
- Crack depth (1)
- Curriculum (1)
- Damage evolution (1)
- Data fusion (1)
- Diffusion (1)
- Digital maturity (1)
- Digital transformation (1)
- Digitalization (1)
- Durability assessment (1)
- Epitaxially grown 4H-SiC layers (1)
- FMEA (1)
- Failure Modes and Effects Analysis (1)
- Fluidic oscillators (1)
- Fluidics (1)
- Frequency modulation (1)
- Geometrical misalignment (1)
- Geometry (1)
- Herculaneum (1)
- High-entropy alloy (1)
- Human Factors (1)
- Hydrogen (1)
- Image processing (1)
- Image-based models (1)
- Imaging ellipsometry (1)
- Indirect noise (1)
- Insulation material (1)
- Inverse Methods (1)
- Laboratory (1)
- Liner (1)
- Main-flow oriented vorticity-nozzle interaction (1)
- Material testing (1)
- Microplastics (1)
- Multi-geometry cuboid (1)
- Multiple principal element alloy (1)
- Muon tomography (1)
- NDT Reliability (1)
- NDT-CE (1)
- Nondestructive evaluation (1)
- Nuclear magnetic resonance (1)
- Performance assessment (1)
- Plasma acoustics (1)
- Pore-size distribution (1)
- Probability of Detection (1)
- Process monitoring (1)
- Python (1)
- Quadtree meshes (1)
- Quality infrastructure (1)
- Quantification (1)
- Radiographic XCT geometry determination (1)
- Radiographic simulation software (1)
- Reconstruction (1)
- SAFT (1)
- SBFEM (1)
- Scaled Boundary Finite Element Method (1)
- Simulation (1)
- Software (1)
- Structural Health Monitoring (1)
- Structural health monitoring (1)
- Synchrotron radiation (1)
- Task specific numerical measurement uncertainty (1)
- Tendon duct (1)
- Testing (1)
- Thermal desorption analysis (1)
- Thermal extraction (1)
- Transient analysis (1)
- Tungsten-Edge (1)
- Tunnel Inspection (1)
- UFP (1)
- Ultrasonic (1)
- Ultrasonics (1)
- University (1)
- Validation (1)
- Water samples (1)
- Wave defect interaction (1)
- White light interference microscopy (1)
- Wide bandgap compound semiconductor (1)
- X-ray refraction radiography (1)
- X-ray tomography (1)
- XCT machine geometry (1)
- XRF (1)
- Zero Massflow Liner (ZML) (1)
- ink (1)
- inspection (1)
- papyrus (1)
- traceability (1)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (30)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (10)
- 8.4 Akustische und elektromagnetische Verfahren (10)
- 8.0 Abteilungsleitung und andere (8)
- 8.5 Röntgenbildgebung (5)
- 4 Material und Umwelt (2)
- 6 Materialchemie (2)
- 7 Bauwerkssicherheit (2)
- 4.2 Material-Mikrobiom Wechselwirkungen (1)
- 4.5 Kunst- und Kulturgutanalyse (1)
Hundreds of papyrus rolls, carbonized during the 79CE eruption of Mount Vesuvius, were discovered in 1754 at Herculaneum. Sophisticated mechanical methods for unrolling the best-preserved scrolls have been applied, with varying success. However, such processes have been abandoned, to prevent risk from irremediable damage or loss and to preserve the integrity of the extremely fragile rolls. Following the development of X-ray based non-invasive techniques, attempts to virtually unroll the scrolls were made. The most common ink in Antiquity was carbon-based, and the main element of carbonized papyrus is carbon, making these investigations difficult. However, some attempts with synchrotron X-ray phase-contrast tomography (XPCT) were successful. Recently, the identification of antique inks containing metals raised hope that if some of the inks contain metal the rolls can be virtually unrolled using conventional CT- technique. We investigated the inks of a selection of partially unrolled fragments stored at the Biblioteca Nazionale di Napoli with X-ray fluorescence in order to select the best candidates for tomography. Despite the many difficulties (analysis of several layers sticking together, letters barely visible, difficulty to separate contribution from the ink and from the papyrus, inhomogeneity of the support, fragility of the fragments…), encouraging results were found, with a number of inks from Greek fragments found to contain additions to the soot (Fe, Pb, Cu P).
Traceable determination of non-static XCT machine geometry: New developments and case studies
(2022)
It is fundamental to determine the machine geometry accurately for dimensional X-ray computed tomography (XCT) measurements. When performing high-accuracy scans, compensation of a non-static geometry, e.g. due to rotary axis errors or drift, might become necessary. Here we provide an overview of methods to determine and account for such deviations on a per projection basis. They include characterisation of stage error motions, in situ geometry measurements, numerical simulations, and reconstruction-based optimization relying on image quality metrics and will be discussed in terms of their metrological performance. Since a radiographic calibration is always required to provide an initial absolute geometry, this method will be presented as well. The improvements of the XCT geometry correction methods are presented by means of case studies. The methods can be applied individually or in combination and are intended to provide a toolbox for XCT geometry compensation.
Due to the diffusive nature of heat propagation in solids, the detection and resolution of internal defects with active thermography based non-destructive testing is commonly limited to a defect-depth-to-defect-size ratio greater than or equal to one. In the more recent past, we have already demonstrated that this limitation can be overcome by using a spatially modulated illumination source and photothermal super resolution-based reconstruction. Furthermore, by relying on compressed sensing and computational imaging methods we were able to significantly reduce the experimental complexity to make the method viable for investigating larger regions of interest. In this work we share our progress on improving the defect/inhomogeneity characterization using fully 2D spatially structured illumination patterns instead of scanning with a single laser spot. The experimental approach is based on the repeated blind pseudo-random illumination using modern projector technology and a high-power laser. In the subsequent post-processing, several measurements are then combined by taking advantage of the joint sparsity of the defects within the sample applying 2D-photothermal super resolution reconstruction. Here, enhanced nonlinear convex optimization techniques are utilized for solving the underlying ill-determined inverse problem for typical simple defect geometries. As a result, a higher resolution defect/inhomogeneity map can be obtained at a fraction of the measurement time previously needed.
A software toolbox is introduced that addresses several needs common to computed tomography (CT). Built for the WIPANO CTSimU project to serve as the reference implementation for its image processing and evaluation tasks, it provides a Python 3 interface that is adaptable to many conceivable applications. Foremost, the toolbox features a pipeline architecture for sequential 2D image processing tasks, such as flat field corrections and image binning, and enables the user to create their own processing modules. Beyond that, it provides means to measure line profiles and image quality assessment algorithms to calculate modulation transfer functions (MTF) or to determine the interpolated basic spatial resolution (iSRb) using a duplex wire image. It can also be used to calculate projection matrices for the reconstruction of scans with arbitrary industrial CT geometries and trajectories. The CTSimU project defined a framework of projection- and volume-based test scenarios for the qualification of radiographic simulation software towards its use in dimensional metrology. The toolbox implements the necessary evaluation routines and generates reports for all projection-based tests.
Alternative to conventional transmission-based radiography and computed tomography, X-ray refraction techniques are being increasingly used to detect damage in light materials. In fact, their range of application has been recently extended even to metals. The big advantage of X-ray refraction techniques is that they are able to detect nanometric defects, whose size would lie below the resolution of even state-of-the-art synchrotron-based X-ray computed tomography (SXCT). The superiority of synchrotron X-ray refraction radiography and tomography (SXRR and SXRCT) has been shown in the case of light materials, in particular composites. X-ray refraction techniques also yield a quantitifaction of the amount of damage (the so-called relative internal specific surface) and can well be compared with damage models. At the same time, it is impossible for SXRR and SXRCT to image single defects. We show that the combination of refraction- and transmission-based imaging techniques yields an impressive amount of additional information about the type and amount of defects in microstructured materials such as additively manufactured metals or metal matrix composites. We also show that the use of data fusion techniques allows the classification of defects in statistically significant representative volume elements.
Corrosion of concrete reinforcement is one of the major damage mechanisms affecting both the load-bearing capacity and the serviceability of re-inforced concrete structures significantly. When externally discernible damages are observed during visual inspections on the structure, the extent of the damage inside the concrete is often already significant. Corrosion caused by carbonation often leads to severe discoloration of the surface or even large-area spalling of the concrete cover. In contrast, chloride-induced corrosion is usually difficult to observe visually but can cause much more serious damage in less time. The effect occurs locally and can lead to weakening of the cross-section of the reinforce-ment. This, in turn, can cause sudden structural collapses without prior notice.
In the meanwhile, various non-destructive and minimally invasive testing methods are available to evaluate the resistance to penetration of corrosion-pro-moting pollutants and to detect active corrosion. In this paper, a bridge crossing the river Regen is used as a case-study to demonstrate how the information ob-tained applying different testing methods can be combined and evaluated in the context of structural reassessments. Both the results of the permeability testing and the electrical resistance measurement are considered, as well as active corro-sion areas are localized using the half-cell potential mapping combined with the concrete cover measurement with the eddy current method and ground penetrat-ing radar. The results are evaluated using drill cores and in addition laser-induced breakdown spectroscopy was applied to obtain information about possible chlo-ride ion transport into the concrete.
Temperature Compensation Strategies for Lamb Wave Inspection using Distributed Sensor Networks
(2022)
The application of temperature compensation strategies is crucial in structural health monitoring approaches based on guided waves. Actually, the varying temperature influences the performance of the inspection system inducing false alarms or missed detection, with a consequent reduction of reliability. This paper quantitatively describes a method to compensate the temperature effect, namely the optimal baseline selection (OBS), extending its application to the case of distributed sensor networks (DSN). The effect of temperature separation between baseline time-traces in OBS are investigated considering multiple couples of sensors employed in the DSN. A combined strategy that uses both OBS and frequent value warning is considered. Theoretical results are compared, using data from two several experiments, which use different frequency analysis with either predominantly A0 mode or S0 mode data or both. The focus is given on the fact that different paths are available in a sensor network and several possible combination of results are available. Nonetheless, introducing a frequent value warning it is possible to increase the efficiency of the OBS approach making use of fewer signal processing algorithms. These confirm that the performance of OBS quantitatively agrees with predictions and also demonstrate that the use of compensation strategies improve detectability of damage.
Sound production due to main-flow oriented vorticity-nozzle interaction in absence of a net swirl
(2022)
The downstream acoustic response due to the interaction of main-flow oriented vorticity with a choked nozzle in a swirl-free flow was experimentally demonstrated. The response was obtained by means of impulsive radial air injection in the pipe upstream from the nozzle. The resulting downstream acoustic data are shown to obey a scaling rule that differs, from the one for swirl-nozzle interaction, which according to the literature is proportional to the square of the swirl number. In contrast, here evidence is presented that points to the scaling of main-flow oriented vorticity noise with the cross-sectional average of the square of the transversal velocity at the throat divided by the square of the critical sound speed.
In a joint project of partners from industry and research, the automated recycling of construction and demolition waste (CDW) is investigated and tested by combing laser-induced breakdown spectroscopy (LIBS) and near-infrared (NIR) spectroscopy. Joint processing of information (data fusion) is expected to significantly improve the sorting quality of various materials like concrete, main masonry building materials, organic components, etc., and may enable the detection and separation of impurities such as SO3-cotaining building materials (gypsum, aerated concrete, etc.). The project focuses primarily on the Berlin site to analyze the entire value chain, minimize economic/technological barriers and obstacles at the cluster level, and sustainably increase recovery and recycling rates. First measurements with LIBS and NIR spectroscopy show promising results in distinguishing various material types and indicate the potential for a successful combination. In addition, X-ray fluorescence (XRF) spectroscopy is being performed to obtain more information about the quantitative elemental composition of the different building materials. Future work will apply the developed sorting methodology in a fully automated measurement setup with CDW on a conveyor belt.
Atmospheric pressure plasmas interact in various physical ways with their surroundings. They release heat and generate charge carriers, which leads to two effects. The first effect is the generation of acoustic waves due to heat release, known as the thermoacoustic effect, and the second effect is the perturbation of the resting fluid provoked by the release of charge carriers, called “ionic wind”. The direct connection between the charge carrier production of the discharge arrangement and the surroundings also allows the detection of acoustic waves by tracking the electrical current of the arrangement.
This contribution introduces a multi-fluid model approach to describe the acoustic interaction of atmospheric plasmas. In addition, we present experimental results on commercially available and in-house fabricated discharge arrangements for either emitting or receiving acoustic waves.