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<書評>Wolfgang Hans Stein, Revolutionskultur ohne Revolution. Die französischen Nationalfeste im Rheinland am Beispiel des Saardepartements 1794-1804
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Development of reinforced concrete column with replaceable plastic hinge based on metabolism concept
No full textTo update seismic performance and rapidly restore the transportation capacity of a bridge following an earthquake, this study introduces a new reinforced concrete (RC) column, termed “Metabolic RC column, ” which incorporates the Design for Disassembly and Metabolism Movement concepts. The proposed column features a plastic hinge comprising a permanent hinge and replaceable plastic zones. A Mesnager hinge is employed as the permanent hinge to resist the axial loads within the column cross section. In addition, cast-in-place RC members are used in replaceable plastic zones to dissipate the seismic energy. By replacing the plastic zone with an equivalent or superior alternative while the permanent hinge continues to carry the axial forces, the updating (i.e., metabolization) of the column seismic performance can be achieved without interrupting the daily operations of the structure. The feasibility of replacing plastic hinges while maintaining the resistance to axial loads was demonstrated through plastic zone replacement tests. Cyclic loading tests indicated that the maximum lateral load of the proposed Metabolic RC Column remained unchanged before and after the plastic zone replacement. The energy dissipated also remained nearly consistent before and after the plastic zone replacement. The largest reduction in dissipated energy at each displacement amplitude was approximately 6.7 % before and after replacement. Additionally, the cyclic loading tests emphasized the importance of minimizing damage to the permanent hinge and preventing the axial stiffness reduction to ensure maximum load capacity of the column after plastic zone replacement. Further, a numerical model was developed to replicate the load-displacement relationship of the specimens. The proposed model accurately calculated the maximum load of the specimen with an average error of approximately 3 % for each displacement amplitude and the dissipated energy with an error of approximately 6 %. The numerical analysis effectively captured the changes in the secondary stiffness of the columns before and after plastic zone replacement, attributing the differences in secondary stiffness to the reduced tensile forces exerted by the permanent hinge rebar
Index of braking behaviour in two dimensions within risk perception
No full textTime To Collision (TTC) and other physical indices are widely used to predict drivers' braking behaviour. However, these indices often overlook the psychological aspects of how drivers perceive risk. Moreover, such indices are predominantly one-dimensional and do not account for the shared space, where vehicles can move in two dimensions. In this study, we introduce an index designed to predict drivers' braking behaviour in the shared space, taking into account the drivers' risk perception. In Experiment 1, a functional equation was derived to estimate the probability that drivers would brake in a given situation. The results confirmed that the index provides an adequate reflection of drivers' risk perception. In Experiment 2, the braking rate estimated with the index provided a better fit to a third-person risk evaluation when compared to other physical indices
Advancing the hydrogen tolerance of ultrastrong aluminum alloys via nanoprecipitate modification
No full textUltrastrong metallic alloys, possessing unparalleled load-bearing abilities, are coveted in many sectors, thus attracting growing research efforts. However, these alloys encounter persistent usability challenges posed by hydrogen embrittlement, which causes unpredictable fracture through crack initiation. Due to complex hydrogen-microstructure interactions and their exacerbation under high stress, advances in hydrogen resistance in ultrastrong materials are sparse throughout their long history. Herein, we report a quantum-mechanics-informed strategy for hydrogen tolerance enhancement in ultrafine-grain-hardened Al-Zn-Mg-Cu alloys, approaching their current strength limit of approximately 1 GPa. This method involves the incorporation of hydrogen-absorbing T-phase precipitates into nanograins, to substantially reduce hydrogen coverage at potential crack initiation sites. We demonstrate, via synchrotron radiation X-ray micro-/nano-tomography, scanning transmission electron microscopy and atom probe tomography, that nanoprecipitates successfully withstand shear strains exceeding 1000 and are exploitable essentials for ultra strength-hydrogen synergy, contrasting their often-assumed secondary roles in nanocrystalline alloys due to possible strain-induced dissolution, which has intuitively excluded exploring them as central elements. Our approach potentially inspires new hydrogen-resisting alloys across a broad strength-composition space
