Anisotropic parameter identification using inhomogeneous tensile test

In this contribution, an inverse identification strategy of constitutive laws for elastoplastic behaviour is presented. The proposed inverse algorithm is composed on an appropriate finite element calculation combined with an optimisation procedure. It is applied to identify material anisotropic coefficients using a set up of easy performed laboratory tests. The used experimental data are the plane tensile test and the off axes tensile tests. The identified behaviour models are mainly based on Hill's quadratic yield criterion. Two cases of this yield criterion have been considered: the transverse isotropic and the orthotropic one under an associated and non-associated flow rule assumptions for each case. The yield surface has been assumed to expand isotropically (isotropic strain hardening law) as a function of the plastic work.In order to better describe anisotropic plastic properties of the studied materials, a recently planar anisotropic yield function is used. It is a non-quadratic yield criterion which takes account of anisotropic yield stresses as well as anisotropic strain ratios. It is subsequently shown that the agreement between inverse identification results and experimental measurements were improved.We prove also that the presented strategy is a good alternative to the simplified homogeneous tests assumption, especially for the plane tensile test.     

基于Chebyshev-Taylor-Fourier混合级数模型函数的多源气动数据融合方法

针对飞行器气动力多源数据融合、 飞行试验气动辨识问题,提出了一种基于Chebyshev-Taylor-Fourier混合级数模型函数、不确定度平衡权函数和加权最小二乘原理的多源数据融合和辨识方法.该方法采用二元Cheby-shev级数、Taylor级数和Fourier级数技术建立飞行器气动模型函数,采用权函数技术平衡各...     

Parameter identification for viscoelastic materials

Starting from the general stress-strain relation for a linear Boltzmann-Volterra material, which is in agreement with the principle of inertia, a new identification procedure is proposed. Instead of running one long-range relaxation experiment, following asingle suitably specified deformation history, material characterization is done using the data ofn short relaxation experiments followingn different deformation histories. To interpret these data a direct non-iterative algorithm has been developed. Compared with other methods, for example curve fitting by using Gauss' method, this direct method is numerically stable and allows a simple direct evaluation of the error due to the scattering of experimental data. The method has been applied to the determination of the relaxation times of an unsaturated polyester material.     

Online Tracking of Maneuvering Target Trajectory Based on Chaotic Time Series Prediction

Online prediction of maneuvering target trajectory is one of the most popular research directions at present. Specifically, the primary factors balancing, between prediction accuracy and response time, will give the research substance. This paper presents an online trajectory prediction algorithm based on small sample chaotic time series (OTP-SSCT). First, we optimize in terms of data breadth. The dynamic split window is built according to the motion characteristics of the maneuvering target, thus realizing trajectory segmentation and constructing a small sample chaotic time series prediction set. Second, since fully considering the motion patterns of maneuvering targets, we introduce the spatiotemporal features into the particle swarm optimization (PSO) model identification algorithm, which improves the identification sensitivity of key trajectory data points. Furthermore, we propose a feedback optimization strategy of residual compensation to correct the trajectory prediction values to improve the prediction accuracy. For the initial value sensitivity problem of the PSO model identification algorithm, we propose a new initial population strategy, which improves the effectiveness of initial parameters on model identification. Through simulation experiment analysis, it is verified that the proposed OTP-SSCT algorithm achieves better prediction accuracy and faster response time.     

一类不确定延迟神经网络的自适应投影同步

研究了一类参数不确定的延迟神经网络的投影同步,基于Lyapunov稳定性理论,设计了一种新型的自适应控制方法.该方法能同时实现一类参数不确定延迟神经网络的参数识别和投影同步.数值模拟证明了该方法的有效性. 关键词： 延迟神经网络 Lyapunov稳定性理论 参数识别 投影同步     

Breaking chaotic shift key communication via adaptive key identification

This paper proposes an adaptive parameter identification method for breaking chaotic shift key communication from the transmitted signal in public channel. The sensitive dependence property of chaos on parameter mismatch is used for chaos adaptive synchronization and parameter identification. An index function about the synchronization error is defined and conjugate gradient method is used to minimize the index function and to search the transmitter's parameter (key). By using proposed method, secure key is recovered from transmitted signal generated by low dimensional chaos and hyper chaos switching communication. Multi-parameters can also be identified from the transmitted signal with noise.     

皱叶香茶菜化学成分的研究

从采自西藏的皱叶香茶菜中分离鉴定了3对B-闭联对映贝壳杉烯型二萜化合物:二萜化合物皱叶香茶菜素(Ⅰ)和二氢皱叶香茶菜素(Ⅱ);isodocarpin(Ⅲ)和dihydroisodocarpin(Ⅳ)及Carpalasionin(Ⅴ)和dihydrocarpalasionin(Ⅵ)。(Ⅰ)、(Ⅲ)和(Ⅴ)分别与对应的二氢化合物(Ⅱ)、(Ⅳ)和(Ⅵ)以混合物的形式被分离和鉴定。化合物(Ⅱ)为新化合物,(Ⅰ)、(Ⅳ)和(Ⅵ)首次在自然界发现,(Ⅲ)和(Ⅴ)为已知化合物。     

加筋板材料辨识的导纳特征表达与冲击声特征提取

以表征物理属性的导纳特征为中间量,提取与加筋板材料属性有关的冲击声特征。先用相关分析方法获得金属加筋板物理属性的导纳特征表达以及导纳特征与冲击声特征之间的联系,间接得到表征声源物理属性的冲击声特征,然后通过支持向量机分类器验证不同特征在金属加筋板材料分类辨识中的性能。结果表明,所得的4组冲击声特征能准确识别出不同的材料,单个特征的识别率与对应材料属性的可分程度有关,理想冲击声声特征比音色特征的平均识别率更高。由此可见,利用导纳特征提取与材料属性相关冲击声特征的方法是有效的,且所提的特征能够很好的反映声源材料属性。     

Mass spectrometric methods for the analysis of chlorinated and nitrated isoflavonoids: a novel class of biological metabolites

Electrospray ionization combined with tandem mass spectrometry was applied to a study of some representative chlorinated and nitrated isoflavones-potential metabolites of isoflavones in inflammatory cells. Upon collision-induced dissociation of deprotonated [M - H](-) ions of these compounds, a number of structurally characteristic product ions were produced. The product ion analysis of 3'- and 8-chlorodaidzein in the tandom mass spectra led to ready differentiation of these isomers. 3-Nitro derivatives of both genistein and daidzein have product ions due to the losses of HNO(2) and two OH groups. Chlorinated derivatives of isoflavones were detected in cell-based experiments and their structures were proposed by comparing the tandem mass spectra of their product ions with those of standards. This work provides a suitable analytical basis to aid the characterization of chlorinated and nitrated metabolites in studies in vivo and in vitro.     

基于液相色谱-质谱联用的代谢组学研究中代谢物的结构鉴定进展

基于液相色谱-质谱联用的代谢组学技术因其高效分离能力和高灵敏检测能力已成为生命科学研究的重要手段,但由于缺乏有效的通用标准谱图库,检测到的大量代谢物的结构难以鉴定。这制约了代谢组学覆盖度的提高和生物标志物的发现,造成化学和生物信息的严重丢失,成为代谢组学发展的主要技术瓶颈。随着质谱仪器及计算机技术的进步,基于大气压电离质谱（API-MS）的代谢物结构鉴定技术飞速发展,本文从质谱仪器、代谢物分子结构式判别、数据库及谱图检索以及计算机辅助谱图解析等方面,对代谢物结构鉴定的最新进展进行了综述。