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201.
This paper proposes a model of the mechanical behaviour of corroded reinforced concrete members subjected to bending under
service load. The model is based on the formulation of a macro-element to be used in FEM analysis, having a length equal to
the distance between two consecutive flexural cracks and a cross-section equal to the member cross-section. The mechanical
formulation is directly written in generalized variables (bending moment and curvature) and is based on the concept of the
transfer length necessary for the transmission of tensile load from re-bar to tensile concrete thanks to the bond. It is thus
possible to take into account the effect of reinforcement corrosion on the bond between re-bar and concrete, by increasing
the transfer length versus intensity of corrosion. The variation of the transfer length versus corrosion is expressed using
a scalar damage parameter. A first experimental validation is performed on a 17-year-old beam kept in a chloride environment
under its service load. 相似文献
202.
Viaduct roads have wide application in big cities with high traffic loads, in order to decrease traffic density and to connect
subways to highways. Viaduct roads are constructed using steel structures instead of concrete ones in areas of earthquake
risks. The low weight of steel structures however causes problems such as vibration and noise. There is increasing demand
especially in populated areas to suppress vibration and noise on highway roads for reducing noise-related environmental pollution.
In this study, bending vibrations of rectangular plate viaduct roads, which are supported by six fixed elements of rectangular
cross-sectional elements are considered. Natural frequencies are obtained using the Rayleigh-Ritz technique, finite elements
analysis, experimentally and neural networks (NN). 相似文献
203.
French Douglas J.; No?l Marc; Vigneau Fran?ois; French Julie A.; Cyr Chantal P.; Evans R. Thomas 《Canadian Metallurgical Quarterly》2005,37(3):181
This study examined the psychometric properties of the PCS-CF, a French-Canadian adaptation of the Pain Catastrophizing Scale (Sullivan, Bishop & Pivik, 1995). One hundred and twenty undergraduate students (83 women; 37 men) completed the PCS-CF and measures of anxiety and depression prior to immersing their hand in ice water for 1-minute. A subset of 39 participants (28 females; 11 males) also completed a second pain task involving an ascending series of electrocutaneous stimulations. Participants' verbal and non-verbal pain behaviours during and immediately after the immersion task were recorded and subsequently independently coded. Reliability analyses revealed that the PCS-CF total score and subscale scores have a high degree of internal consistency and test-retest reliabilities that are comparable to the original Pain Catastrophizing Scale. PCS-CF scores were associated with higher levels of self-reported pain during the ice water immersion task and decreased pain tolerance during electrocutaneous stimulation. Individuals with elevated PCS-CF scores also displayed a more diverse repertoire of pain behaviours than their low PCS-CF counterparts. Previous findings that catastrophizing scores are able to discriminate criterion groups of males and females were also replicated. Given the highly correlated factors obtained in analyses of the dimensionality of the PCS-CF, the structure suggested by the authors of the original scale is only partially supported. However, the results taken together suggest that the PCS-CF is both a reliable and valid measure of the pain catastrophizing construct that is psychometrically comparable to the original PCS. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
204.
The calculations of the elastic scattering properties of ultra-cold francium isotopes are reported in detail. A parametric model potential for the triplet molecular states of the Fr2 is represented, and the scattering lengths at and the effective range re are calculated using WKB and Numerov methods for Fr--Fr in the triplet state. The convergence of these scattering properties depending on a K0 parameter and core radius is also investigated using two methods: Quantum Defect Theory and analytical formula of Symskoviski. 相似文献
205.
Ba2(Zn0.5Ti0.5X)O6 compounds from the general ABO3 perovskite family were synthesized by the classical solid-state route for X = Nb and Ta with various A/B ratios (1.005, 1 and 0.995). After the calcination step at 1100 °C, both compounds (X = Nb and Ta) contain mainly the cubic disordered ‘Ba2(Zn0.5Ti0.5X)O6’ phase but traces of BaTiO3 and secondary phases are often detectable. Nevertheless, after the sintering stage at higher temperature (from 1300 to 1500 °C) and for all A/B ratios investigated, Ti enters into the cubic perovskite structure, resulting in the formation of a unique ‘Ba2(Zn0.5Ti0.5X)O6’ phase. Attractive dielectric properties have been measured on the tantalum-based compound for A/B = 0.995 (Q ∼2000 at 7.4 GHz and ? = 39.6) as well as on the niobium-based phase for A/B = 1.005 (Q ∼2200 at 6.1 GHz and ? = 54.8). All these characteristics were confirmed at 1 MHz and a linear dependence of the permittivity versus temperature from −60 to 180 °C has also been evidenced for both formulations. Sinterability, dielectric properties and microstructure of such compounds are discussed with respect to the stoichiometry. 相似文献
206.
On the probabilistic-deterministic transition involved in a fragmentation process of brittle materials 总被引:1,自引:0,他引:1
François Hild Christophe DenoualPascal Forquin Xavier Brajer 《Computers & Structures》2003,81(12):1241-1253
Dynamic loadings produce high stress waves leading to the fragmentation of brittle materials such as ceramics, concrete, glass and rocks. The main mechanism used to explain the change of the number of fragments with stress rate is a shielding phenomenon. However, under quasi-static loading conditions, a weakest link hypothesis may be applicable. Therefore, depending on the local strain or stress rate, different fragmentation regimes are observed. One regime corresponds to single fragmentation for which a probabilistic approach is needed. Conversely, the multiple fragmentation regime may be described by a deterministic approach. The transition between the two fragmentation regimes is discussed for high performance concrete, glass and SiC ceramics. 相似文献
207.
Jacques Angel Alain Boissier Sylvain Lallemant Franois Leblanc Bertrand Pcout Jacob W. Lin James Tung 《Journal of the Society for Information Display》2003,11(3):533-538
Abstract— As the need for high‐resolution ultra‐low‐power bistable displays grows, it is important to rapidly implement the mass‐production manufacturing of BiNem® LCDs. The cost‐effective approach for BiNem® manufacturing is based on using STN manufacturing process technologies since BiNem® and STN displays have a similar internal structure. The key differences between BiNem® and STN displays from a manufacturing point of view will be discussed. We show that industrial STN manufacturing equipment can be used to produce BiNem® LCDs at competitive costs. Reflective e‐book display modules with VGA resolution are produced in the pilot‐production series. 相似文献
208.
209.
A distributed multimedia document presentation involves retrieval of objects from one or more document servers and their
presentation at the client system. The presentation of the multimedia objects has to be carried out in accordance with the
specification of temporal relationships between the objects. The retrieval of multimedia objects from the document server(s)
is influenced by factors such as temporal specification of objects presentations, throughput offered by the network service
provider, and the buffer resources on the client system. Flexibility in the temporal specification of the multimedia document
may help in deriving an object retrieval schedule that can handle variations in network throughput and buffer resource availability.
In this paper, we develop techniques for deriving a flexible object retrieval schedule for a distributed multimedia document
presentation. The schedule is based on flexible temporal specification of the multimedia document using the difference constrai
nts approach. We show how the derived retrieval schedule can be validated and modified to ensure that it can work with the
offered network throughput and the available buffer resources. 相似文献
210.