Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (16)
- Beitrag zu einem Tagungsband (12)
- Vortrag (3)
- Handbuch (1)
- Sonstiges (1)
- Posterpräsentation (1)
Sprache
- Englisch (27)
- Deutsch (6)
- Mehrsprachig (1)
Schlagworte
- Concrete (4)
- CO2 quality (3)
- Impurities (3)
- Pipeline network (3)
- Recommendations (3)
- Whole-chain CCS scenario (3)
- Beton (2)
- Civil engineering (2)
- Corrosion (2)
- GPR (2)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (7)
- 7 Bauwerkssicherheit (6)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (6)
- 7.6 Korrosion und Korrosionsschutz (5)
- 5 Werkstofftechnik (3)
- 5.1 Mikrostruktur Design und Degradation (3)
- 6 Materialchemie (3)
- 6.3 Strukturanalytik (3)
- 1 Analytische Chemie; Referenzmaterialien (1)
- 1.4 Prozessanalytik (1)
- 6.0 Abteilungsleitung und andere (1)
- 7.4 Baustofftechnologie (1)
- 8.5 Röntgenbildgebung (1)
- VP Vizepräsident (1)
- VP.1 eScience (1)
Eingeladener Vortrag
- nein (3)
Metaproteomics has matured into a powerful tool to assess functional interactions in microbial communities. While many metaproteomic workflows are available, the impact of method choice on results remains unclear. Here, we carry out a community-driven, multi-laboratory comparison in metaproteomics: the critical assessment of metaproteome investigation study (CAMPI). Based on well-established workflows, we evaluate the effect of sample preparation, mass spectrometry, and bioinformatic analysis using two samples: a simplified, laboratory-assembled human intestinal model and a human fecal sample. We observe that variability at the peptide level is predominantly due to sample processing workflows, with a smaller contribution of bioinformatic pipelines. These peptide-level differences largely disappear at the protein group level. While differences are observed for predicted community composition, similar functional profiles are obtained across workflows. CAMPI demonstrates the robustness of present-day metaproteomics research, serves as a template for multi-laboratory studies in metaproteomics, and provides publicly available data sets for benchmarking future developments.
Stahlbetontragwerke sind eine wichtige Konstruktionsweise im Bauwesen und ein wachsendes Anwendungsfeld für die Zerstörungsfreie Prüfung (ZfP).
Zur Sicherung der Tragsicherheit, strukturellen Integrität, Bestimmung von Geometrien und zur Detektion konstruktiver Elemente wie z.B. Bewehrung, Verankerungen und Spannkanälen besitzen zerstörungsfreie Prüfverfahren in diesem Bereich inzwischen große Relevanz. Durch den bislang erreichten Fortschritt in der Forschung und Entwicklung haben moderne akustische und elektromagnetische Verfahren eine beachtliche Leistungsfähigkeit erreicht. Von Geräteherstellern sind diese in kommerziellen Produktserien umgesetzt worden und finden eine zunehmend breite Anwendung in der Praxis. In einigen anderen Anwendungsgebieten, in denen die ZfP bereits fester Bestandteil von Überwachungen ist, wie z.B. im Maschinenbau und insbesondere in der Kerntechnik und der Luftfahrt, existieren umfangreiche Qualitätssicherungssysteme für die konforme Anwendung und zuverlässige Einbeziehung der ZfP. Dem relativ jungen Entwicklungsstadium moderner ZfP für Stahlbetonbauteile entsprechend müssen solche Konzepte im Bauwesen erst noch entwickelt bzw. implementiert werden.
Dementsprechend hat sich der Unterausschuss Qualitätssicherung (UA- S) des Fachausschusses ZfP im Bauwesen (ZfPBau) die Definition und Verbesserung der Qualität von ZfP-Anwendungen sowie insbesondere die verfahrensunabhängige Standardisierung von Prüfprozeduren und statistische Absicherung der Prüfergebnisse zum Ziel gemacht.
Die aktuellen Arbeitsfelder beinhalten die Entwicklung praxisgerechter Konzepte für Prüfprozeduren und deren Erprobung in einem Ringversuch sowie die Konzeption von Testkörpern hinsichtlich unterschiedlicher Aspekte wie Parameterstudien, Validierung, Kalibrierung und Simulation. Dabei werden Ansätze anderer Branchen durchaus einbezogen, die Anpassung an die spezifischen Bedürfnisse und Gegebenheiten des Bauwesens wird jedoch als wesentlich angesehen und stellt somit eine wichtige Vorgabe dar.
Da die Tätigkeiten nicht auf einzelne Verfahren begrenzt sind, müssen generelle Vorgehensweisen entwickelt werden, die sich auf die jeweiligen Verfahren konkretisieren lassen. Der Vortrag gibt hierzu erste Einblicke in die Arbeit des Ausschusses.
The process of ensuring reliability of NDT applications contains various aspects, such as determining the performance and probability of success, the uncertainty in measurement, the provision of clear and functional procedures and ensuring the correct application accordingly. Test specimens have become powerful elements in supporting many of these aspects. Within the committee for NDT in Civil Engineering (NDT-CE) of the German Society for Nondestructive Testing (DGZfP), the subcommittee on Quality Assurance (UA-QS) therefore addresses the design and the integration of test specimens in the quality assurance process. Depending on the specific purpose, the requirements on test specimens can vary significantly based on the defined simulated scenario. The most prominent purposes of test specimens might be seen in providing references for inspection systems in regard to function control, calibration and validation. Further aspects can be parametric studies, basic investigation of physical principles related to NDT or a simplified and therefore comprehensive demonstration of inspection concepts (e.g. for teaching purposes). The specific purpose of a test specimen dictates the requirements regarding its conception, including the exact design, the material or the fabrication accuracy and the conditioning. In the development of a general guideline by the UA-QS for application-specific procedures and their validation, the use of test specimens is addressed and specific concepts for the design of test specimens are made. This includes the analysis of the measurement process regarding any given application, deriving an adequate calibration approach for it and designing test specimens (calibration specimens) accordingly. Furthermore, it includes the validation of the procedure taking into account all conditions related to the specific application in the field. The validation requires a statistically sufficient number of trials. Thorough evaluation of each trial can only be established if the ground-truth is known. Therefore, test specimens providing a realistic but controlled simulation of the inspection problem are valuable and indispensable elements in the validation process. The requirement of being fully realistic will often not be possible to fulfill due to practical restrictions. Any aspect that cannot be included in the simulation realistically needs to be simulated conservatively. This again, requires a sufficient understanding of the inspection principle and technique to ensure conservativeness. Among other quality-assurance-related aspects, the UA-QS establishes concepts and guidelines regarding sound and efficient approaches for the specific purposes of test specimens. This subcommittee brings together representatives of different Groups along the entire value chain of NDT-CE, including researchers, practitioners, manufacturers and clients. They all work together in establishing a common understanding and level of quality assurance in the industry.
The field of non-destructive testing of civil structures (NDT-CE) has been continuously growing. Due to the complexity and diversity of civil constructions as well as the heterogeneity of concrete, specific standards or guidelines for the application of modern NDT-CE are still missing. The development of individual solutions is the current approach, which is just as challenging as it is common for NDT-CE.
With the increasing development and commercialization of NDT-CE technology, the group of practitioners is growing. To ensure a good level of quality in the industry, it appears necessary to establish adequate means.
Naturally, the performance of NDT-CE methods regarding a specific application is strongly dependent on choosing the most suitable inspection technique and applying it correctly, generally referred to as the inspection procedure in the field of NDT. There are well-defined guidelines regarding procedure documentation and handling in many fields of NDT (e.g. nuclear, aerospace or automotive) according to the high importance of procedures in assuring a successful and reliable application. For a long time, this has not always been the case with NDT-CE, which is still considered a unique discipline of NDT. Part of the reason for that might be the young development state of NDTCE, the heterogeneity of building materials like concrete, timber or masonry as a material and the diversity of civil structures. In consequence, NDT-CE procedure development is considered challenging.
Among other aspects, addressed in the subcommittee on Quality Assurance (UA-QS) within the committee for NDT-CE of the German Society for Nondestructive Testing (DGZfP), part of its work aims at establishing an adequate basis for NDT-CE procedure development. While some of the highly developed approaches from other industries are taken into consideration, they need to be analyzed regarding their suitability for NDT-CE and adapted accordingly. For a procedure to be as defined as possible, it needs to contain sufficient information, such as the scope and limitations regarding material, geometry and condition of the test object, inspection parameters, calibration, data acquisition, analysis criteria as well as requirements regarding the inspection personnel.
For a successful implementation in the field, it is important to define the specific procedure as precisely as possible. Despite the necessity of a great amount of information to be included, the procedure needs to be suitable for efficient field application.
The UA-QS is developing a guideline for NDT-CE procedures suitable for application in this field of NDT to ensure correct and reproducible application. To demonstrate and evaluate this concept, specific examples of procedures are also produced. In particular, the UA-QS has developed a procedure for the detection and positioning of tendon ducts using Ground Penetrating Radar (GPR). This procedure is tested regarding the practical applicability in a roundrobin on a defined type of reference test block.
Recently, non-destructive testing in civil engineering (NDT-CE), in particular of concrete components, has successfully mastered the leap from research to practice. Several methods have been established for field inspections to determine the concrete cover of reinforcement or to estimate the compressive strength as well as other parameters related to the concrete material. In addition, the application of non-destructive testing is indispensable, if information about the inner structure - such as the location of rebars and tendon ducts or the damage-related condition assessment to detect grouting defects, honeycombs, delamination, or corrosion - is required. Besides the selection of a suitable NDT method and an appropriate inspection system, the reliability of the results depends largely on the person who applies the non-destructive inspection technique and evaluates the inspection results. To ensure a high quality of non-destructive concrete evaluation as well as to keep the uncertainty caused by the inspection personnel to a minimum, structured, consistent, and regulated theoretical as well as practical training of inspection personnel is essential. To close this gap, the subcommittee of education and training (UA-A) within the committee for NDT-CE of the German Society for Non-Destructive Testing (DGZfP) has been reactivated in 2018 to establish uniform training standards for non-destructive concrete inspections in the long term. The subcommittee consists of scientists, practitioners, authorities, and clients. So far, the national standard DIN 4871 “Non-destructive testing - Qualification of NDT personnel in Civil Engineering (NDT-CE)” was developed. This standard considers the civil-industry-specifics, for example, that standards for NDT of concrete, as well as related product standards with a few exceptions, still do not exist at the moment. Within this presentation, the concept, the connection to ISO 9712 and other standards as well as an overview of the recently developed German standard DIN 4871 will be presented.
So near and yet so far: harmonic radar reveals reduced homing ability of Nosema infected honeybees
(2014)
Pathogens may gain a fitness advantage through manipulation of the behaviour of their hosts. Likewise, host behavioural changes can be a defence mechanism, counteracting the impact of pathogens on host fitness. We apply harmonic radar technology to characterize the impact of an emerging pathogen - Nosema ceranae (Microsporidia) - on honeybee (Apis mellifera) flight and orientation performance in the field. Honeybees are the most important commercial pollinators. Emerging diseases have been proposed to play a prominent role in colony decline, partly through sub-lethal behavioural manipulation of their hosts. We found that homing success was significantly reduced in diseased (65.8%) versus healthy foragers (92.5%). Although lost bees had significantly reduced continuous flight times and prolonged resting times, other flight characteristics and navigational abilities showed no significant difference between infected and non-infected bees. Our results suggest that infected bees express normal flight characteristics but are constrained in their homing ability, potentially compromising the colony by reducing its resource inputs, but also counteracting the intra-colony spread of infection. We provide the first high-resolution analysis of sub-lethal effects of an emerging disease on insect flight behaviour. The potential causes and the implications for both host and parasite are discussed.
Molecular switches are of fundamental importance in nature, and light is an important stimulus to selectively drive the switching process. However, the local dynamics of a conformational change in these molecules remain far from being completely understood at the single-molecule level. Here, we report the direct observation of photoinduced tautomerization in single porphycene molecules on a Cu(111) surface by using a combination of low-temperature scanning tunneling microscopy and laser excitation in the near-infrared to ultraviolet regime. It is found that the thermodynamically stable trans configuration of porphycene can be converted to the metastable cis configuration in a unidirectional fashion by photoirradiation. The wavelength dependence of the tautomerization cross section exhibits a steep increase around 2 eV and demonstrates that excitation of the Cu d-band electrons and the resulting hot carriers play a dominant role in the photochemical process. Additionally, a pronounced isotope effect in the cross section (∼100) is observed when the transferred hydrogen atoms are substituted with deuterium, indicating a significant contribution of zero-point energy in the reaction. Combined with the study of inelastic tunneling electron-induced tautomerization with the STM, we propose that tautomerization occurs via excitation of molecular vibrations after photoexcitation. Interestingly, the observed cross section of ∼10–19 cm2 in the visible–ultraviolet region is much higher than that of previously studied molecular switches on a metal surface, for example, azobenzene derivatives (10–23–10–22 cm2). Furthermore, we examined a local environmental impact on the photoinduced tautomerization by varying molecular density on the surface and find substantial changes in the cross section and quenching of the process due to the intermolecular interaction at high density.
Nonclassical crystallization typically occurs via the attachment of individual nanoparticles. Intuitively, materials synthesized via this route should exhibit pronounced surface roughness and porosity as a hallmark of the formation process via particle accretion. Here, we demonstrate that nonclassical mineralization of calcium carbonate allows synthesis of ultra-smooth and dense surfaces with unprece-dented root-mean-square roughness of 0.285 nm, simply by con-trolling the hydration state of the nanosized building blocks using Mg doping. High fidelity coating of corrugated substrates can even be achieved. Nonclassical crystallization can thus lead to space-filling inorganic solid-state materials transgressing the implicit porosity commonly expected for particle-driven self-organization processes.
Recently, non-destructive testing in civil engineering (NDT-CE), in particular of concrete components, has successfully mastered the leap from research to practice. Several methods have been established for field inspections to determine the concrete cover of reinforcement or to estimate the compressive strength as well as other parameters related to the concrete material. In addition, the application of nondestructive testing is indispensable, if information about the inner structure - such as the location of rebars and tendon ducts or the damage-related condition assessment to detect grouting defects, honeycombs, delamination, or corrosion - is required. Besides the selection of a suitable NDT method and an appropriate inspection system, the reliability of the results depends largely on the person who applies the non-destructive inspection technique and evaluates the inspection results. To ensure a high quality of non-destructive concrete evaluation as well as to keep the uncertainty caused by the inspection personnel to a minimum, structured, consistent and regulated theoretical as well as practical training of inspection personnel is essential. To close this gap, the subcommittee of education (UA-A) within the committee for NDT-CE of the German Society for Nondestructive Testing (DGZfP) has been reactivated in 2018 to establish uniform training standards for nondestructive concrete inspections in the long term. The subcommittee consists of scientists, practitioners, authorities, and clients. So far, the national standard DIN 4871 “Non-destructive testing - Qualification and Certification of NDT personnel in Civil Engineering (NDT-CE)” was developed and is currently under review. This standard considers the civil-industry-specifics, for example, that standards for NDT of concrete, as well as related product standards with a few exceptions, still do not exist at the moment. Within this presentation, the concept, the connection to ISO 9712 and other standards as well as an overview of the developed German standard DIN 4871 will be presented.
A thorough characterization of base materials is the prereq- uisite for further research. In this paper, the characterization data of the reference materials (CEM I 42.5 R, limestone pow- der, calcined clay and a mixture of these three components) used in the second funding phase of the priority program 2005 of the German Research Foundation (DFG SPP 2005) are presented under the aspects of chemical and min- eralogical composition as well as physical and chemical properties. The data were collected based on tests performed by up to eleven research groups involved in this cooperative program.
To set up recommendations on how to define “reasonable minimum composition thresholds” for CO2 streams to access CO2 pipeline networks, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the CCS chain. All investigations were based on a generic “CCS cluster scenario” in which CO2 streams captured from a spatial cluster of eleven emitters (seven fossil-fired power plants, two cement plants, one refinery and one steel mill) are collected in a regional pipeline network. The resulting CO2 stream (19.78 Mio t impure CO2 per year) is transported in a trunk line (onshore and offshore) and injected into five generic replicate storage structures (Buntsandstein saline aquifers) offshore. Experimental investigations and modeling of selected impacts revealed beneficial as well as adverse impacts of different impurities and their combinations. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the considered variable compositions and mass flow rates were observed. We recommend to define minimum composition thresholds for each specific CCS project through limiting
i) the overall CO2 content,
ii) maximum contents of relevant impurities or elements,
iii) acceptable variability of concentrations of critical impurities, and defining impurity combinations to be avoided.
The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on: Corrosion of pipeline steel, pipeline network design and related transport costs, alteration of well bore cements, pressure development and rock integrity, geochemical reactions, and petrophysical and geomechanical rock properties.
All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein.
The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for each individual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv) impurity combinations to be avoided.
The precipitation of struvite, a magnesium ammonium phosphate hexahydrate (MgNH₄PO₄ · 6H₂O) mineral, from wastewater is a promising method for recovering phosphorous. While this process is commonly used in engineered environments, our understanding of the underlying mechanisms responsible for the formation of struvite crystals remains limited. Specifically, indirect evidence suggests the involvement of an amorphous precursor and the occurrence of multi-step processes in struvite formation, which would indicate non-classical paths of nucleation and crystallization. In this study, we use synchrotron-based in situ x-ray scattering complemented by cryogenic transmission electron microscopy to obtain new insights from the earliest stages of struvite formation. The holistic scattering data captured the structure of an entire assembly in a time-resolved manner. The structural features comprise the aqueous medium, the growing struvite crystals, and any potential heterogeneities or complex entities. By analysing the scattering data, we found that the onset of crystallization causes a perturbation in the structure of the surrounding aqueous medium. This perturbation is characterized by the occurrence and evolution of Ornstein-Zernike fluctuations on a scale of about 1 nm, suggesting a non-classical nature of the system. We interpret this phenomenon as a liquid-liquid phase separation, which gives rise to the formation of the amorphous precursor phase preceding actual crystal growth of struvite. Our microscopy results confirm that the formation of Mg-struvite includes a short-lived amorphous phase, lasting >10 s.
The impact of the ovo proteins ovalbumin and lysozyme—present in the first stage of egg shell formation—on the homogeneous formation of the liquid amorphous calcium carbonate (LACC) precursor, was studied by a combination of complementing methods: in situ WAXS, SANS, XANES, TEM, and immunogold labeling. Lysozyme (pI = 9.3) destabilizes the LACC emulsion whereas the glycoprotein ovalbumin (pI = 4.7) extends the lifespan of the emulsified state remarkably. In the light of the presented data: (a) Ovalbumin is shown to behave commensurable to the 'polymer-induced liquid precursor' (PILP) process proposed by Gower et al. Ovalbumin can be assumed to take a key role during eggshell formation where it serves as an effective stabilization agent for transient precursors and prevents undirected mineralization of the eggshell. (b) It is further shown that the emulsified LACC carries a negative surface charge and is electrostatically stabilized. (c) We propose that the liquid amorphous calcium carbonate is affected by polymers by depletion stabilization and de-emulsification rather than 'induced' by acidic proteins and polymers during a so-called polymer-induced liquid-precursor process. The original PILP coating effect, first reported by Gower et al., appears to be a result of a de-emulsification process of a stabilized LACC phase. The behavior of the liquid amorphous carbonate phase and the polymer-induced liquid-precursor phase itself can be well described by colloid chemical terms: electrostatic and depletion stabilization and de-emulsification by depletion destabilization.
The capabilities of National Metrology Institutes (NMIsthose which are members of the Comité Consultatif pour la Quantité de Matière (CCQM)of the CIPM) and selected outside "expert" laboratories to quantitate (C4H9)3Sn+ (TBT) in a prepared marine sediment were assessed. This exercise was sanctioned by the 7th CCQM meeting, April 46, 2001, as an activity of the Inorganic Analysis Working Group and was jointly piloted by the Institute for National Measurement Standards of the National Research Council of Canada (NRC) and the Laboratory of the Government Chemist (LGC), UK. A total of 11 laboratories submitted results (7 NMIs, and 4 external labs). Two external laboratories utilized a standard calibration approach based on a natural abundance TBT standard, whereas all NMIs relied upon isotope dilution mass spectrometry for quantitation. For this purpose, a species specific 117Sn-enriched TBT standard was supplied by the LGC. No sample preparation methodology was prescribed by the piloting laboratories and, by consequence, a variety of approaches was adopted by the participants, including mechanical shaking, sonication, accelerated solvent extraction, microwave assisted extraction and heating in combination with Grignard derivatization, ethylation and direct sampling. Detection techniques included ICPMS (with GC and HPLC sample introduction), GCMS, GCAED and GCFPD. Recovery of TBT from a control standard (NRCC CRM PACS-2 marine sediment) averaged 93.5±2.4% (n=14). Results for the pilot material averaged 0.680±0.015 µmol kg1 (n=14; 80.7±1.8 µg kg1) with a median value of 0.676 µmol kg1. Overall, performance was substantially better than state-of-the-art expectations and the satisfactory agreement amongst participants permitted scheduling of a follow-up Key comparison for TBT (K-28), a Pilot intercomparison for DBT (P-43), and certification of the test sediment for TBT content and its release as a new Certified Reference Material (HIPA-1) with a TBT content of 0.679±0.089 µmol kg1 (expanded uncertainty, k=2, as Sn) (80.5±10.6 µg kg1). Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00216-003-2016-9.
The use of high brilliance and partial coherent synchrotron light for radiography and computed tomography (CT) allows to image micro-structured, multi-component specimens with different contrast modes and resolutions up to submicrometer range. This is of high interest for materials research, life science and non-destructive evaluation applications. An imaging setup for microtomography and radiography installed at BESSY II (a third generation synchrotron light source located in Berlin, Germany) as part of its first hard X-ray beamline (BAMline) can now be used for absorption, refraction as well as phase contrast dedicated to inhouse research and applications by external users. Monochromatic synchrotron light between 6 keV and 80 keV is attained via a fully automated double multilayer monochromator. For imaging applications the synchrotron beam transmitted by the sample is converted with a scintillator into visible light. By use of microscope optics this luminescence image is then projected onto, e.g., a CCD chip. Several scintillating materials are used in order to optimise the performance of the detector system. Different optical systems are available for imaging ranging from a larger field of view and moderate resolutions (macroscope up to 14 mm x 14 mm field of view) to high resolution (microscope down to 0.35 μm pixel size), offering magnifications from 1.8× to 40×. Additionally asymmetric cut Bragg crystals in front of the scintillator can be used for a further magnification in one dimension by a factor of about 20. Slow and fast cameras are available, with up to 16 bit dynamic range. We show the suitability of the setup for numerous applications from materials research and life science.
New evidences for a spinodal CaCO3 formation observed by contact-free in situ scattering techniques
(2007)
Ultrasound sensors should be embedded into concrete for monitoring concrete properties. These new longitudinal wave sensors with a center frequency of 60 kHz were examined regarding their suitability for ultrasonic measurements in concrete structures in terms of emission characteristics, sensitivity and frequency ränge.
For the measurement of the radiation patterns, the sensors were embedded vertically and horizontally in concrete cylinders. The directivity pattern was measured using a laser vibrometer.
The sensitivity of the sensor was determined in water using different sensors of the same type. It shows changes in the signal amplitude as well as variations in the frequency ränge for different transmitter-receiver combinations.
The attenuation of the concrete affects the achievable resolution of the measurements and thus, the maximum possible spacing of the sensors within a concrete element. Experimental tests helped optimizing the distances with respect to the required resolution and the effort of embedding the sensors. The signal attenuation in the concrete was measured in the frequency ränge of 60 kHz in response to various degrees of reinforcement and grain size. For this purpose, the sensors were cast at different distances in the specimens studied. The recorded Signals were evaluated for their amplitude and frequency spectrum.
The calcitic prisms of Pinna nobilis (Pinnidae, Linnaeus 1758) are shown to be perfect examples of a mesocrystalline material. Based on their ultrastructure and on the occurrence of an amorphous transient precursor during the early stages of prism formation, we provide evidence for the pathway of mesocrystallisation proposed by Seto et al. (2012), which proceeds not by self-organized oriented attachment of crystalline nano-bricks but by aggregation of initially amorphous nanogranules which later transform by epitaxial nucleation to a three-dimensional array of well aligned nanocrystals. We further fathom the role of a liquid amorphous calcium carbonate in biomineralisation processes and provide strong evidence for the occurrence of PILP-like intermediates during prism formation. We develop a new scenario of prism formation based on the presented findings presented findings and discuss the implications of a speculative liquid amorphous calcium carbonate (LACC) intermediate in vivo.
An in-depth investigation of tunnel linings is performed at Eisenhower Tunnel, 60 miles west of Denver, Colorado, using a combination of four nondestructive testing methods: air- and ground-coupled ground penetrating radar (GPR), ultrasonic echo (US echo), ultrasonic tomography (UST), and impact echo (IE). A robotic frame with pneumatically operated vacuum plates is used to automate GPR, US echo, and IE. UST was performed manually. These techniques are used to identify and locate the reinforcement mesh and structural steel ribs. Local changes in ultrasonic phase are calculated by phase analysis processing techniques and apparent relationships between positive and negative phase shifts and steel and air interfaces are observed. According to previous laboratory research, these relationships indicate the bonded state between the concrete and the embedded steel, but without ground truth verification this can only be suggested. It is shown that this combination of methods can be used synergistically to provide tunnel owners with the layout and possible condition of tunnel lining reinforcement and structural components.
Tunnel lining evaluation is performed in the Hanging Lake Tunnel near Glenwood Springs, Colorado, using variations of four nondestructive evaluation (NDE) methods: air- and ground-coupled ground penetrating radar (GPR), ultrasonic echo (US echo), ultrasonic tomography (UST), and impact echo (IE). Potential regions of interest are identified using high-speed air-coupled GPR and visual inspection. A robotic frame with pneumatically-operated vacuum plates was used to automate the ground-coupled GPR, US echo, and IE tests, while the UST technique was used manually. This study shows that a particular combination of NDE techniques is a powerful tool for assessing the condition of tunnel linings and can detect potential anomalies such as delamination, depth of surface cracks, reinforcement depth and layout, and lining thickness. By mapping the phase shift of the ultrasonic pulses at detected interface, the potential bonding of layer interfaces and reinforcement is assessed.
The research project "Ultrasonic Net for Concrete Monitoring (UNeCOM)" aims at developing a methodology for an embedded ultrasonic network for the condition assessment of infrastructure constructions. Civil engineering structures made of concrete, which are located in tectonically active regions or undergo special loading conditions, may require continuous monitoring. It is important to assess the condition of the building and its stability to recognise and classify the effect of a seismic event or evolving damage at early stages before failure occurs. Embedded ultrasonic sensors offer the possibility to detect changes in the material and degradation mechanisms from inside the structure in areas which are difficult or impossible to inspect otherwise. In contrast to conventional ultrasonic testing methods, where the concrete surfaces are scanned with ultrasound probes, this new approach uses sensors, which are embedded into concrete, eliminating the effect of variable coupling conditions between sensors and concrete. This method allows an integral detection of changes in the concrete structure, for example due to seismic activities, to detect mechanical impacts, as well as degradation of the material due to overloading. Such methods have great relevance especially for the monitoring of constructions like power plants, bridges, offshore structures and other structures with high technical safety requirements. The sensor network can be controlled remotely through the internet which is also being used for data transfer. The embedded sensor network is designed to monitor structural damage and concrete degradation globally with high sensitivity.
In geothermal power plants materials e.g. pumps are exposed to extremely corrosive thermal water. This results in corrosion fatigue and so inevitably the reduction of the lifetime of these components. Also in the field of the carbon dioxide storage technology (carbon capture and storage CCS) components are exposed to a corrosive environment and mechanical stress. In order to gain knowledge upon the corrosion fatigue strength of materials a corrosion chamber for "in situ" conditions was designed and successfully applied.Two different steels X46Cr13 and X5CrNiCuNb16-4 have been tested and their corrosion fatigue behavior was compared. To simulate the frequency of operating pumps (30 – 40 Hz) a resonant testing machine was used. In addition technical CO2 was introduced into the closed system at a rate close to 9 L/h to keep stable environmental conditions. The samples have a surface roughness of Rz = 4 to simulate technical machined surfaces. The calculated tensile strength of X46Cr13 with soft annealed microstructure (coagulated cementite in ferrite-perlite matrix) is about 680 MPa and the yield strength is about 345 MPa. The tensile strength of X5CrNiCuNb16-4 is about 1078 MPa and the yield strength about 928 MPa. Testing parameters are: corrosion media: saline aquifer water (Stuttgart Aquifer) temperature of the brine at 60 °C and load ratio of R=-1. For X46Cr13 a stress amplitude between 160 MPa to 270 MPa and for X5CrNiCuNb16-4 a stress amplitude between 150 to 500 was chosen. Cycles until crack initiation differ strongly and were found to start at 5 x 104 up to 12.5 x 106 cycles.X46Cr13 has reached a maximum number of cycles (12.5 x 106) at a stress amplitude of 173 MPa. X5CrNiCuNb16-4 has reached the maximum number of cycles (10 x 106) at a stress amplitude of 150 MPa. The range of scatter for X5CrNiCuNb16-4 is very high (1:34) in comparison the range of scatter for X46Cr13 (1:3.5).
Life Cycle Assessment (LCA) and Social Life Cycle Assessment (SLCA) are applied in evaluating possible social and environmental impacts of the state-of-art welding technologies, such as Manual Metal Arc Welding (MMAW), Manual Gas Metal Arc Welding (GMAW), Automatic GMAW and Automatic Laser-Arc Hybrid Welding (LAHW). The LCA results indicate that for 1 meter weld seam, MMAW consumes the largest amount of resources (like filler material and coating on electrodes) and energy, which contributes to comparatively higher environmental impacts in global warming potential, acidification, photochemical ozone creation potential and eutrophication than other chosen processes. With regard to social aspects, the health issues and fair salary are under survey to compare the relative potential risk on human health caused by fumes in different welding technologies, and to indicate the sufficiency of current salary of welders in Germany. The results reflect that the wage status of welders is still fair and sufficient. The manual processes bring much higher potential risk of welders health than the automatic processes, especially MMAW.
During Rutherford cable production the wires are plastically deformed and their initially round shape is distorted. Using X-ray absorption tomography we have determined the 3D shape of an unreacted Nb3Sn 11 T dipole Rutherford cable, and of a reacted and impregnated Nb3Sn cable double stack. State-of-theart image processing was applied to correct for tomographic artefacts caused by the large cable aspect ratio, for the segmentation of the individual wires and subelement bundles inside the wires, and for the calculation of the wire cross sectional area and shape variations. The 11 T dipole cable cross section oscillates by 2% with a frequency of 1.24 mm (1/80 of the transposition pitch length of the 40 wire cable). A comparatively stronger cross sectional area variation is observed in the individual wires at the thin edge of the keystoned cable where the wire aspect ratio is largest.
Structural Silicone Glazing (SSG) is a curtain walling method that utilizes silicone sealants to adhere glass, ceramic, metal or composite panels to supporting framing members by means of a peripheral adhesive joint. In SSG curtain walls, silicone sealants serve not only as a weather seal, but also act as a structural bonding element, eliminating the need for exterior retainers and covers.
The paper discusses some essential findings of two recent research studies on the durability and service life of structural silicone glazing sealants and structures. The first study demonstrates, that specimens of a first generation 2-part silicone sealant taken from a SSG façade after 23+2 years of real life successfully passed the European ETAG002-1 performance criteria for residual strength. In a second study, a new performance-based durability test method was developed in partnership with the Federal Institute for Materials Research Berlin/Germany (BAM). This method is based on simultaneously exposing system test specimens to artificial weathering and complex, multiaxial mechanical loadings. 2-part structural silicone sealants of the first and of the second generation where subjected to this test, which is considered to correspond to an anticipated service life of 50 years.
A big problem with the chemistry literature is that it is not standardized with respect to precise operational parameters, and real time corrections are hard to make without expert knowledge. This lack of context means difficult reproducibility because many steps are ambiguous, and hence depend on tacit knowledge. Here we present the integration of online NMR into an automated chemical synthesis machine (CSM aka. “Chemputer” which is capable of small-molecule synthesis using a universal programming language) to allow automated analysis and adjustment of reactions on the fly. The system was validated and benchmarked by using Grignard reactions which were chosen due to their importance in synthesis. The system was monitored in real time using online-NMR, and spectra were measured continuously during the reactions. This shows that the synthesis being done in the Chemputer can be dynamically controlled in response to feedback optimizing the reaction conditions according to the user requirements.
During the mineralisation of metal carbonates MCO3 (M = Ca, Sr, Ba, Mn, Cd, Pb) liquid-like amorphous intermediates emerge. These intermediates that form via a liquid/liquid phase separation behave like a classical emulsion and are stabilized electrostatically. The occurrence of these intermediates is attributed to the formation of highly hydrated networks whose stability is mainly based on weak interactions and the variability of the metal-containing pre-critical clusters. Their existence and compositional freedom are evidenced by electrospray ionization mass spectrometry (ESI-MS). Liquid intermediates in non-classical crystallisation pathways seem to be more common than assumed.
The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on:
• corrosion of pipeline steel,
• pipeline network design and related transport costs,
• alteration of well bore cements,
• pressure development and rock integrity,
• geochemical reactions, and
• petrophysical and geomechanical rock properties.
All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein.
The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for each individual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv) impurity combinations to be avoided.