Bayesian estimation of a normal mean parameter using the Linex loss function and robustness considerations

Summary This paper presents a derivation of an explicit analytical form for the Bayes estimator of the normal location parameter using the Linex loss function with a general class of prior distributions. Exact and approximate results based on Pericchi and Smith’s paper (1992) are given, where the priors are double-exponential and Studentt, respectively. The results of this paper provide a link between the robust Bayesian analysis for the normal location parameter when adopting either the Linex loss function or the squared error loss function.     

A non-singular boundary integral formula for determining the T-stress for cracks of arbitrary geometry

A simple, yet accurate 2-D boundary integral equation (BIE) for determining the T-stress for cracks of arbitrarily geometry is introduced in this paper. The formulation is based upon the asymptotic expansion for the stress field in the vicinity of a crack tip. It can be conveniently implemented in the post-processing stage of a boundary element fracture analysis. As demonstrated in this work, the proposed BIE is non-singular, and thus it can directly be collocated at the crack tip under consideration. The technique requires a similar computational effort as that used in calculating the stress components at an interior point of a domain. Consequently, this new approach is very computationally effective and accurate for evaluating the elastic T-stress. Five test examples, involving straight, kink and curved cracks, are studied to validate the proposed technique and to assess its accuracy.     

Superconducting transition temperatures in the Ru-1232 system, RuSr2(Gd1? x Ln x Ce1.8Sr0.2)Cu2O z (Ln = Sm, Dy, and Ho)

We have investigated effects of the lanthanide element Ln and the composition changes on the superconducting transition temperatureT _c in the Ru-1232 system, RuSr₂(Gd_1−x Ln _x Ce_1.8Sr_0.2)Cu₂O _z (Ln = Sm, Dy, and Ho). At first, in the case of the samples with Ln = Sm among almost the single 1232 phase samples, the values of the superconducting onset temperatureT _co are almost the same forx=0.00−0.15, and each of the lattice parametersa andc is almost constant. While, in each of the cases of the samples with Ln = Dy and Ho, the sample withx=0.05 shows the maximum values for both the superconducting onset temperatureT _co and the zero resistivity temperatureT _cz. Especially for the sample with Ln = Dy, the values ofT _co andT _cz are 18.5 and 6.5 K, respectively. These are higher than those of the mother sample of RuSr₂(GdCe_1.8Sr_0.2)Cu₂O _z . Moreover, from variations ofT _co, lattice parameters ofa andc in the RuSr₂(Gd_1−x Dy _x Ce_1.8Sr_0.2)Cu₂O _z system as a function of Dy contentx, the relationship between the superconducting transition temperature and the lattice parameters in the present system are investigated.     

独角仙鞘翅微结构及其纳米力学性能

利用SEM对独角仙鞘翅的微结构进行了观测, 并借助纳米压痕仪测试分析了鞘翅的纳米力学性能。SEM试验表明独角仙鞘翅是一种具有拱形空腔的中空轻质生物复合材料, 其断面占空比为26.36%。鞘翅由外表皮和内表皮构成, 而内表皮又通过11~12层纤维层采用45°角正交叠加铺设, 层间辅以许多微纤维丝交叉连接方式编织在一起, 形成层合板结构。试验测得鞘翅外表皮纳米力学性能分别为: 硬度(0.28±0.13) GPa, 弹性模量(5.62±1.21) GPa, 接触刚度 (1.67±0.14)×10⁴ N/m。其纳米力学性能呈现拓扑分布规律, 由头部至尾部区域有增大趋势。试验测试结果为后续研究中设计一种基于独角仙鞘翅的新型轻质仿生结构提供了仿生学模型和理论参考。     

Temperature dependence of the infrared optical properties of YBa2Cu3O7: A plasmon damping model

The temperature dependence observed in the mid- and near-infrared optical properties of YBa₂Cu₃O₇ is explained in terms of the Drude model for free charge carriers. In the Drude model, the linear temperature dependence of the dc resistivity arises from the free charge carriers having a temperature-dependent mean free path. This temperature dependence results in the plasmon contribution to the dielectric constant having a damping coefficient which also varies linearly with temperature. We find that the temperature dependence which is observed in the absorption and reflection spectra of YBa₂Cu₃O₇ is consistent with this simple model.     

On the symmetry of phosphorous doped ZnSe

The site symmetry of P doped ZnSe is analysed in detail here, as the recent experiments suggest two possible symmetriesT _d andC _3V. The reduction toC _3V is attributed to the presence of natural impurity, Ga. Our calculations based on molecular model and Green’s functions suggest that the symmetryC _3V is possible with ZnSe : P when Jahn Teller distortion of about ～ 0.2 Å (towards one of Zn atom) is assumed. This has been supported by other experiments.     

The construction of constitutive relations for isotropic strain-hardening elastoplastic materials of the differential type of complexity <Emphasis Type="Italic">n</Emphasis>. Part 1. Finite strains

Using approaches in rational continuum mechanics, we have developed a mathematical theory of strict construction and specialization of constitutive equations for simple (in Noll’s sense) isotropic strain-hardening elastoplastic materials of the differential type of complexity n (analogs of the Rivlin–Ericksen solids of complexity n) as the most important representatives of the materials with infinitesimal fading path shape memory (a fading path shape memory on an arbitrarily small interval of the “past”). The strains are assumed to be arbitrary. The hierarchy of the constitutive relations is constructed according to the level of complexity of the material response to deformation. Translated from Problemy Prochnosti, No. 2, pp. 27–42, March–April, 2009.     

The construction of constitutive relations for isotropic strain-hardening elastoplastic materials of the differential type of complexity <Emphasis Type="Italic">n</Emphasis>. Part 2. Infinitesimal strains

A method of specialization of the physical equations constructed earlier by the author for isotropic hardening elastoplastic materials of the differential type of complexity n for finite strains is developed within the theory of infinitesimal strains. With this method, a number of constitutive relations are derived in the form of the hierarchy according to the level of complexity of the material response to deformation. For n = 1, the conditions for the existence of a loading surface are established. Translated from Problemy Prochnosti, No. 4, pp. 29–47, July–August, 2009.