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排序方式: 共有1330条查询结果,搜索用时 15 毫秒
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In this paper, a general framework for the modelling of physical phenomena with stochastic dynamical systems switched by jump Markov processes is given. A methodology of the associated estimation procedures is provided. A particular attention is paid to the estimation of the underlying jump process, which is not observable.As an application, a stochastic model is proposed for the fatigue crack growth problem. The estimation of the model parameters is made on a real crack growth data set. We are thus able to simulate some crack growth paths which are used for reliability analysis through Monte Carlo techniques. 相似文献
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Simulating testing conditions leading to evaluate the intergranular stress corrosion cracking sensitivity of structural alloys is crucial to estimate the lifetime of in-service components. Former studies have pointed out that a simple modification of the design of slow strain rate tensile specimens was particularly convenient for evaluating the susceptibility to intergranular stress corrosion cracking of nickel-base alloys. The aim of the present work is to characterize and model the mechanical behaviour of such specimens. Validation of proposed modelling relies mainly on tensile tests carried on specimens equipped with strain gages. One of the striking results is that, for a given displacement rate of the heads of the specimen, a much slower strain rate can be obtained locally in comparison with the strain rate of an equivalent smooth specimen. 相似文献
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Chana PHUTTHANANON Pornkasem JONGPRADIST Daniel DIAS Xiangfeng GUO Pitthaya JAMSAWANG Julien BAROTH 《Frontiers of Structural and Civil Engineering》2022,16(5):638
This paper presents a reliability-based settlement analysis of T-shaped deep cement mixing (TDM) pile-supported embankments over soft soils. The uncertainties of the mechanical properties of the in-situ soil, pile, and embankment, and the effect of the pile shape are considered simultaneously. The analyses are performed using Monte Carlo Simulations in combination with an adaptive Kriging (using adaptive sampling algorithm). Individual and system failure probabilities, in terms of the differential and maximum settlements (serviceability limit state (SLS) requirements), are considered. The reliability results for the embankments supported by TDM piles, with various shapes, are compared and discussed together with the results for conventional deep cement mixing pile-supported embankments with equivalent pile volumes. The influences of the inherent variabilities in the material properties (mean and coefficient of variation values) on the reliability of the piled embankments, are also investigated. This study shows that large TDM piles, particularly those with a shape factor of greater than 3, can enhance the reliability of the embankment in terms of SLS requirements, and even avoid unacceptable reliability levels caused by variability in the material properties. 相似文献
98.
Synthesis,Chiral Separation,Absolute Configuration Assignment,and Biological Activity of Enantiomers of Retro‐1 as Potent Inhibitors of Shiga Toxin 下载免费PDF全文
Dr. Hajer Abdelkafi Dr. Aurélien Michau Alexandra Clerget David‐Alexandre Buisson Dr. Ludger Johannes Prof. Daniel Gillet Dr. Julien Barbier Dr. Jean‐Christophe Cintrat 《ChemMedChem》2015,10(7):1153-1156
The Shiga toxin (Stx) family is composed of related protein toxins produced by the bacteria Shigella dysenteriae and certain pathogenic strains of E. coli. No effective therapies for Stx intoxication have been developed yet. However, inhibitors that act on the intracellular trafficking of these toxins may provide new options for the development of therapeutic strategies. This study reports the synthesis, chromatographic separation, and pharmacological evaluation of the two enantiomers of Retro‐1, a compound active against Stx and other such protein toxins. Retro‐1 works by inhibiting retrograde transport of these toxins inside cells. In vitro experiments proved that the configuration of the stereocenter at position 5 is not crucial for the activity of this compound. X‐ray diffraction data revealed (S)‐Retro‐1 to be slightly more active than (R)‐Retro‐1. 相似文献
99.
Hannah Baars Julien Engel Lucas Mertens Daniela Meister Carsten Bolm 《Advanced Synthesis \u0026amp; Catalysis》2016,358(14):2293-2299
Carbamoyl fluorides are formed in reactions of hydroxylamines with difluorocarbene generated from sodium bromodifluoroacetate as readily available and non‐toxic carbene precursor. The process shows a high functional group tolerance, and the reaction path has been rationalized by computational calculations.
100.
A series of LiNi1/3Mn1/3Co1/3O2 samples with α-NaFeO2 structure belonging to the D3d5 space group were synthesized using tartaric acid as a chelating agent by wet-chemical method. Different acid to metal-ion ratios R have been used to investigate the effect of this parameter on the physical and electrochemical properties. We have characterized the reaction mechanism, the structure, and morphology of the powders by TGA, XRD, SEM and TEM imaging, completed by magnetic measurements, Raman scattering spectroscopy, and complex impedance experiments. We find that the LiNi1/3Mn1/3Co1/3O2 sintered at 900 °C for 15 h with an acid to metal-ion ratio R = 2 was the optimum condition for this synthesis. For this optimized sample, only 1.3% of nickel-ions occupied the 3b Wyckoff site of the lithium-ions sublattice. The electrochemical performance has been investigated using a coin-type cell containing Li metal as the anode. The electronic performance is correlated to the concentration of the Ni(3b) defects that increase the charge transfer resistance and reduce the lithium diffusion coefficient. The optimized cell delivered an initial discharge capacity of 172 mAh g−1 in the cut-off voltage of 2.8-4.4 V, with a coulombic efficiency of 93.4%. 相似文献