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11.
以国际上在标识、鉴别与授权标准方面已有的工作为基础,提出了我国电子认证与授权管理标准体系框架。 相似文献
12.
T. Beda 《Journal of Polymer Science.Polymer Physics》2007,45(13):1713-1732
A constitutive phenomenological model completing the Gent‐Thomas concept is carried out to formulate laws governing the hyperelastic behavior of incompressible rubber materials. It is shown that the phenomenological Gent‐Thomas model (1958) and the constrained chain model (1992) give similar precise results at small to moderate deformation. On the other hand, comparisons of the outcome of the proposed model with that of the molecular model from the combined concepts of Flory‐Erman and Boyce‐Arruda (2000), and with those of the phenomenological models of Ogden (1982), Yeoh‐Fleming (1997), Pucci‐Saccomandi (2002) and Beda (2005) are made. Residual inconveniences raised by attractive continuum models in rubber elasticity literature have been successfully overcome. Results from both the statistical and phenomenological mechanics concepts are compared with the data of some useful classical materials (rubbers of Treloar, Rivlin‐Saunders, Pak‐Flory and Yeoh‐Fleming). The results permit one to see salient equivalence of the two theories for a more reliable prediction of stress‐stretch response for all states of any mode of deformation. A complete and exhaustive analysis of the Mooney plot that combines small and very large extension‐compression has been quite essential in assessing the validity of models. A method of identification of material parameters is presented and data of the simple tension suffice for the determination of the parameter values. It is shown that the ordinary identification procedures, such as the usual least squares, a very much used numerical method in materials investigation, can be unsuitable in some cases of hyperelastic modeling. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1713–1732, 2007 相似文献
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14.
Auguet C. Martorell F. Moll F. Torra V: 《Journal of Thermal Analysis and Calorimetry》2002,70(1):277-290
The miniaturized calorimetric devices furnish a reduced working flat surface and permits measurements with extremely low-mass
quantities. The experimental sensitivity shows relevant position dependence with x-y surface coordinates and with z-distance. The device identification is realized via a 2-D model based in Fourier general equation.
Using the Marquardt method the experimental flat surface device can be identified and the fitted parameters used to simulate
the behavior of the experimental system. From the model, the effects of several dissipation configurations can be evaluated.
Also, via the RC-analogy, a way to 3-D experimental devices is roughly described.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
一个安全有效的身份鉴别协议与对应的数字签名方案 总被引:3,自引:0,他引:3
本文利用二元一次不定方程和Schnorr身份鉴别协议,构造出一个新的身份鉴别协议,该协议在RSA问题和离散对数问题是难解的假设下是安全的,同时给出了所对应的数字签名方案。 相似文献
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CDMA时变色散信道的两级盲辨识算法 总被引:1,自引:0,他引:1
本文通过对时变信道的扩展函数在时频域进行正则采样,得到了CDMA时变系统的离散正则模型。针对该模型提出了一种具有较低运算量的两级盲辨识算法。为避免两级算法产生的误差传播效应,文章将理想SIMO模型等效为加性噪声模型来处理。与基展开模型方法相比,该算法具有不需利用观测数据的高阶统计量估计展开基频率的优点。文章通过仿真验证了该算法是可行的。 相似文献
18.
We present a Bayesian theory of object identification. Here, identifying an object means selecting a particular observation from a group of observations (variants), this observation (the regular variant) being characterized by a distributional model. In this sense, object identification means assigning a given model to one of several observations. Often, it is the statistical model of the regular variant, only, that is known. We study an estimator which relies essentially on this model and not on the characteristics of the “irregular” variants. In particular, we investigate under what conditions this variant selector is optimal. It turns out that there is a close relationship with exchangeability and Markovian reversibility. We finally apply our theory to the case of irregular variants generated from the regular variant by a Gaussian linear model. 相似文献
19.
Philippe Quevauviller Rob Ritsema Roberto Morabito Wilfried M. R. Dirkx Salvatore Chiavarini Jos M. Bayona Olivier F. X. Donard 《应用有机金属化学》1994,8(6):541-549
Biogeochemical pathways of tin species in the environment are still controversial, e.g. with regard to methylation and transmethylation phenomena, owing to the fact that the identification of methylated tin-compounds is often difficult. The previous tentative identification of a mixed methylbutyltin compound in sediment and biological samples by GC/AAS after hydride generation gave an illustration of this problem. This compound was previously identified in sediments by other authors and also suspected to occur in a contaminated sediment sample from the Boyardville Marina, France. The retention time obtained by GC/AAS corresponded to the actual retention time of a mixed methylbutyltin calibrant. However, additional checks demonstrated that the compound detected was actually monophenyltin. This evidence was produced by a thorough analysis of a selected sediment sample by alternative techniques such as GC/AAS and GC/AES after pentylation, GC/FPD and GC/MS. The results presented highlight the need for a full identification of compounds to avoid mis-interpretation. 相似文献
20.
通过对宁波港的交通环境,现有VTS系统及港口发展的趋势研究,提出了改善宁波港通航环境,建立和完善VTS系统的有效措施。 相似文献