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排序方式: 共有500条查询结果,搜索用时 15 毫秒
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2.
Quoc Ahn Tran Bastien Chevalier Miguel Angel Benz-Navarrete Pierre Breul Roland Gourvès 《Soils and Foundations》2019,59(6):2348-2355
This paper presents a calculation method for obtaining the continuous variation in stress between the tip and the soil during dynamic penetration tests, particularly in the case of using the Panda 3® penetration testing device. The originality of the method is that the tip stress can be computed continuously throughout the driving process. For each impact of the hammer on the penetrometer, data are recorded by sensors located at the top of the apparatus. Then, the stress at the tip and the displacement of the apparatus are calculated with a method based on the propagation of waves in the device. A three-dimensional numerical model of the penetration test, based on the Panda 3® specifications and using the discrete element method (DEM), is proposed in this paper. The purpose of the simulations is to validate the calculation method by comparing the curves of the tip stress versus the penetration distance obtained in two different ways, the first being the distance directly observed at the tip and the second being the distance calculated from the data recorded at the top of the penetrometer, as with the experimental device. The entire apparatus is represented, including the hammer, the rod, and the tip, and is driven into the model soil. The calculation method is applied, and the results are compared to the actual response of the soil to the driving of the penetrometer directly at the tip, which can be obtained with the numerical model. The responses are found to be very similar, confirming the theoretical framework and its underlying assumptions. This method is applied to dynamic penetration tests and provides the opportunity to obtain mechanical parameters other than the tip resistance from the tests. 相似文献
3.
M. Sanchiz F. Amadieu P.-V. Paubel A. Chevalier 《Behaviour & Information Technology》2020,39(10):1094-1109
ABSTRACT This study investigates how a search interface that displays users’ ultimate query (i.e. users’ current search goal) can cope with the age-related decrease of fluid abilities and support older users’ search behaviours. 30 young and 18 older adults completed 9 search problems with a regular web browser or with the experimental search interface. Results showed that older adults spent longer time on the search engine result pages, they needed more time to reformulate, and they had more difficulties exploring the search paths elaborated. Age-differences also appeared as soon as the beginning of the search. The support tool helped older users reformulate their queries more rapidly and elaborate more flexible search strategies at the beginning of the activity. Indeed, older adults who interacted with the support tool switched to the processing of a new search path more rapidly instead of exploiting their initial query (i.e. they visited fewer websites for the initial query produced and reformulated a query instead of keeping on conducting a deeper investigation of the search results provided in the search engine result page). Implications of these findings for the design of effective support tools for older users are discussed. 相似文献
4.
Carole Rodon Aline Chevalier 《International journal of human-computer interaction》2017,33(10):846-855
In this article, we fill a dearth in the literature of Internet self-efficacy (ISS) measurement. We introduce the translation and validation of the Chinese-Mandarin version of the 8-item Information Retrieval On the Web Self-Efficacy scale (IROWSE scale), which has been originally developed in the French language (Rodon & Meyer, 2017). After back-forward translation procedure and content clarity, we ran a test of this new version. We checked the intrinsic psychometric properties including reliability, factor structure (CFA), and criterion-related validity regarding skills for retrieving information on the Web, general attitude toward the Web, experience, gender, and age. Assessment of construct validity indicated, as expected, a one-factor model for the eight items (with coefficient alpha equal to 0.90). Its sum-scores were not confounded with skill levels or general attitudes, and it founds its sources in direct experiences. Furthermore, research would take into account the Internet World population more broadly beyond the West with this new version. 相似文献
5.
Christian Schroeder Thomas M. Grupp Bernhard Fritz Christoph Schilling Yan Chevalier Sandra Utzschneider Volkmar Jansson 《Journal of materials science. Materials in medicine》2013,24(5):1319-1325
The reduced intraoperative visibility of minimally invasive implanted unicondylar knee arthroplasty makes it difficult to remove bone and cement debris, which have been reported on the surface of damaged and retrieved bearings. Therefore, the aim of this study was to analyze the influence of bone and cement particles on the wear rate of unicompartmental knee prostheses in vitro. Fixed bearing unicompartmental knee prostheses were tested using a knee-wear-simulator according to the ISO standard 14243-1:2002(E) for 5.0 million cycles. Afterwards bone debris (particle size 671 ± 262 μm) were added to the test fluid in a concentration of 5 g/l for 1.5 million cycles, followed by 1.5 million cycles blended with cement debris (particle size 644 ± 186 μm) in the same concentration. Wear rate, knee-kinematics and wear-pattern were analyzed. The wear rate reached 12.5 ± 1.0 mm3/million cycles in the running-in and decreased during the steady state phase to 4.4 ± 0.91 mm3/million cycles. Bone particles resulted in a wear rate of 3.0 ± 1.27 mm3/million cycles with no influence on the wear rate compared to the steady state phase. Cement particles, however, lead to a significantly higher wear rate (25.0 ± 16.93 mm3/million cycles) compared to the steady state phase. The careful removal of extruded cement debris during implantation may help in reducing wear rate. Bone debris are suggested to have less critical influence on the prostheses wear rate. 相似文献
6.
Sculfort Ombeline McClure Melanie Nay Bastien Elias Marianne Llaurens Violaine 《Journal of chemical ecology》2021,47(6):577-587
Journal of Chemical Ecology - Chemical defences in animals are both incredibly widespread and highly diverse. Yet despite the important role they play in mediating interactions between predators... 相似文献
7.
Michelle Pinault Cyrille Guimaraes Jean‐Franois Dumas Stphane Servais Stephan Chevalier Pierre Besson Caroline Goupille 《European Journal of Lipid Science and Technology》2020,122(2)
The aim of this study is to identify high performance thin layer chromatography (HPTLC) conditions allowing the separation and quantification of mammalian cellular phospholipids (PLs) (sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, and especially phosphatidic acid, cardiolipin, and monolysocardiolipin, these latter two being specifically located in mitochondria membranes). In order to make this method faster and easier, a 1D HPTLC method is chosen, testing several eluents as well as several staining methods. A pre‐conditioning of HPTLC plates with boric acid and a copper staining reagent followed by carbonization are selected for the quality of PL separation and homogeneity of staining. The selected conditions are discussed and the method validation is performed according to the International Conference on Harmonization guidelines. Linearity is effective between 1 and 8 µg and limit of quantification is between 0.5 and 2.3 µg depending on PL classes. Precision measurements show coefficients of variation <6%, and when amounts are close to the detection limit, <12%. Lipid extracts of tumor cell lines or isolated mitochondria are used to assess PL profiles. This shows that the HPTLC method can be used routinely to follow level variations of PLs. Practical Applications: The changes in PL composition play a crucial role in tumor processes and regulate cellular functions modulating cellular signaling or mitochondrial metabolism. The simple and cost‐effective 1D HPTLC method that is developed is applied to lipid extracts of whole tumor cells or hepatocyte‐isolated mitochondria. It is sensitive as well as precise to detect variations of phosphatidic acid or cardiolipin levels linked to physio‐pathological conditions. It can also be used to investigate the composition changes of other membrane PLs. Moreover, with a simultaneous analysis of 14 samples/standards on the same plate (six plates per day), this method is adapted for large series of samples. 相似文献
8.
Marlin Magallanes-Perdomo Sylvain Meille Jean-Marc Chenal Elodie Pacard Jérôme Chevalier 《Journal of the European Ceramic Society》2012,32(11):2765-2775
A discussion of the effects of Bioglass® powder crystallisation on the in vitro bioactivity in simulated body fluid (SBF) is presented.Starting from Bioglass® powder, different glass–ceramics were obtained by thermal treatments between 580 °C and 800 °C, with variable crystallisation content (from 10 to 92 wt%). All samples (glass and glass–ceramics) showed apatite formation at their surface when immersed in SBF. In case of the glass and the samples with lowest crystallinity, the first step of apatite formation involved a homogenous dissolution followed by an amorphous calcium phosphate (CaP) layer precipitation. For the samples with a high crystallisation content, heterogeneous dissolution occurred. For the first time, the Stevels number of the amorphous phase is used to explain the possible dissolution of the crystalline phase present in materials with a similar chemical composition of the Bioglass®. All samples presented at 21 days of immersion in SBF B-type hydroxycarbonate apatite crystals. 相似文献
9.
Understanding the potential concerns and needs of residents is key to achieving good acceptability of sustainable drainage systems (SuDS). This paper highlights, through the application of a structured questionnaire, the potential value to residents of living in close proximity to a SuDS pond. The results show that although the pond's characteristics are not the main factor influencing the choice to move into an area, its effect is markedly positive. Contingent valuation of the benefits is used to show that the additional value brought by SuDS amenity, when monetised, can offset a pond's initial construction costs and ongoing maintenance, hence ensuring the return on investment for developers. By building on existing research, this paper highlights major changes in the perception and valuation of pond structures. 相似文献
10.
We give in this paper an alternative, and we believe simpler, proof of a deep result by Mathieu Baudet, namely that the equivalence
of symbolic constraints is decidable for deduction systems on a finite signature modulo a subterm convergent equational theory. 相似文献