Benjamin Kromoser  Johann Kollegger 《Structural Concrete》2020,21(1):4-14

Concrete shells are very efficient structures, spanning wide areas with very little construction material. Unfortunately the formwork needed to erect concrete shells is still very labor and material intensive. An alternative construction method which is more time and resource friendly is Pneumatic Forming of Hardened Concrete. A simple air cushion in combination with additional post‐tensioning tendons are used to transform a flat concrete plate into a double curved shell. This paper describes the design and construction of the first practical large‐scale application of this building method for the construction of the deer pass “AM 2” over the newly built two‐track rail Koralmbahn in Carinthia in the south of Austria. The plan measurements of the bridge are 36.2 m by 38.7 m with the height of the shell from the top edge of the foundations to the vertex mounting to 7.6 m. Within the construction process a flat 100 mm thick hardened concrete plate with a weight of 546 t was lifted to the designed double curved shell. This thin concrete shell served as lost formwork for the final bridge.  相似文献   

    

Patrick Huber  Tobias Huber  Johann Kollegger 《Structural Concrete》2020,21(1):393-408

In recent years, the assessment of the shear resistance of existing post‐tensioned multispan bridges has become a frequent task for civil engineers. New models developed for this purpose need to be verified, since the number of shear‐related results of tests executed under real loading conditions at the interior support of multispan systems is very limited. In this study, eight shear tests carried out on four specimens are presented. The effects of different prestressing grades, cross‐sections, and amounts of transverse reinforcement are investigated. Two test setups were used in order to reproduce the internal forces occurring at the interior and end supports, respectively, of actual multispan bridges. With the aid of close‐range photogrammetry, detailed measurements of the kinematics of the critical flexural‐shear cracks were performed. In this study, it is demonstrated that arching action plays a major role for the shear capacity of slender post‐tensioned beams. The predictions of the shear capacity determined with various shear design models show that these models are conservative, especially with respect to the shear capacity for the region around the interior supports. However, the evaluation of the models also shows that the flexural‐shear crack model yields very promising results of the shear capacity of post‐tensioned beams with low shear reinforcement ratios.  相似文献   

    

Eunice S. Dogbe  Mohsen Mandegari  Johann F. Grgens 《Biofuels, Bioproducts and Biorefining》2020,14(5):1089-1104

The downward trend of global sugar market prices, as well as rising energy prices, threaten the survival of the South African sugar industry. Operating a single‐stage sugar crystallization process, which produces less crystalline sugar along with sucrose‐rich A‐molasses as a by‐product, to which value can be added in an integrated biorefinery, could be a viable solution for the industry. It would offer a diversification option as opposed to the current three‐stage crystallization process designed to achieve maximum sugar recovery. This study presents a rigorous Aspen Plus simulation development and economic assessment of different biorefinery scenarios producing succinic acid (SA) and short‐chain fructooligosaccharides (scFOS) from A‐molasses at target market sizes of 440 kt/year and 160 kt/year, respectively, considering the production capacity and market price interplays. In all, seven scenarios of single‐ or multi‐product(s) biorefinery annexed to an existing sugar mill were developed and assessed. Due to the integration benefits, all scenarios studied delivered an internal rate of return (IRR) between 24.1–61.1%, significantly above the required discount rate of 9.7%. In particular, co‐production of SA and scFOS syrup at production rates 40.5 kt/year and 13.5 kt/year from 70% and 30% of the A‐molasses, respectively resulted in the IRR of 56.1% and was considered the most attractive scenario based on the diverse bio‐production, economic performance and easy market entry of the products determined by low minimum selling prices. The proposed integration can lead to the sustainable operation of existing sugar mills by utilizing resources more efficiently, employment of product diversification and job creation. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd  相似文献   

    

Mariia Kramarenko  Catarina G. Ferreira  Guillermo Martínez-Denegri  Constanza Sansierra  Johann Toudert  Jordi Martorell 《Solar RRL》2020,4(4)

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Pablo Lopez-Iscoa  Nirajan Ojha  Diego Pugliese  Ayush Mishra  Regina Gumenyuk  Nadia Giovanna Boetti  Davide Janner  Johann Troles  Bruno Bureau  Catherine Boussard-Plédel  Jonathan Massera  Daniel Milanese  Laeticia Petit 《Journal of the American Ceramic Society》2019,102(11):6882-6892

The aim of this study was to fabricate a bioactive optical fiber able to monitor “in situ” its reaction with the body through changes in its optical properties. Core and cladding preforms were prepared with the composition (97.25*(0.50P₂O₅-0.40SrO-0.10Na₂O)-2.5ZnO-0.25Er₂O₃) and (98.25*(0.50P₂O₅-0.40SrO-0.10Na₂O)-1.75ZnO) (in mol%), respectively, and successfully drawn into a multimode core/clad optical fiber. Optical and near-Infrared images assessed the proper light guiding properties of the fiber. The fibers favor the precipitation of a Ca-P reactive layer at its surface concomitant with a reduction in the fiber diameter, when immersed in SBF, often assigned as a sign of bioactivity. It is clearly shown here that the bio-response of the fiber upon immersion in SBF can be tracked from the decrease in the intensity of the Er³⁺ ions emission at 1.5 µm. This confirms that the newly developed optical fiber, which combines good optical properties with a suitable bioactive behavior, is a promising platform for the development of novel biomedical devices for biophotonic and photomedical applications. Finally, the successful splicing of the newly developed fiber with commercial optical fibers was an evidence of the possibility to integrate the newly developed phosphate fiber within existing components used in the field of biomedicine.  相似文献   

    

Georg Fröhlich  Johann Halbartschlager 《化学，工程师，技术》2019,91(10):1417-1433

Cleaning, conversion coating, and electrocoating are typical wet‐chemical process units in high‐volume painting plants for car bodies. These surface treatment processes must meet ever higher demands in terms of quality, cost savings, and environmental compatibility. Besides the efficient use of energy, the conservation of water resources plays a key role, for which both the integration of existing and the development of new technologies for process bath care are essential core elements. This article discusses the use of various state‐of‐the‐art technologies.  相似文献   

    

Yikai Xu  Magdalena P. Konrad  Johann L. Trotter  Colin P. McCoy  Steven E. J. Bell 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(2)

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Ulrich Koller  Johann W. Bauer 《International journal of molecular sciences》2022,23(10)

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Elisabeth Mayr  Michael Ablinger  Thomas Lettner  Eva M. Murauer  Christina Guttmann-Gruber  Josefina Pin Hofbauer  Stefan Hainzl  Manfred Kaiser  Alfred Klausegger  Johann W. Bauer  Ulrich Koller  Verena Wally 《International journal of molecular sciences》2022,23(3)

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Anna Musia&#x;  Pawe&#x; Holewa  Pawe&#x; Wyborski  Marcin Syperek  Andrei Kors  Johann Peter Reithmaier  Grzegorz S&#x;k  Mohamed Benyoucef 《Advanced Quantum Technologies》2020,3(2)

The authors demonstrate pure triggered single‐photon emission from quantum dots (QDs) around the telecommunication C‐band window, with characteristics preserved under non‐resonant excitation at saturation, that is, the highest possible, lifetime‐limited emission rates. The direct measurement of emission dynamics reveals photoluminescence decay times in the range of (1.7–1.8) ns corresponding to maximal photon generation rates exceeding 0.5 GHz. The measurements of the second‐order correlation function exhibit, for the best case, a lack of coincidences at zero time delay—no multiple photon events are registered within the experimental accuracy. This is achieved by exploiting a new class of low‐density and in‐plane symmetric InAs/InP QDs grown by molecular beam epitaxy on a distributed Bragg reflector, perfectly suitable for non‐classical light generation for quantum optics experiments and quantum‐secured fiber‐based optical communication schemes.  相似文献