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61.
FexNi100−x nanometric films were deposited on SiO2/Si substrates at room temperature using the pulsed laser deposition technique. The targets were Fe-Ni amorphous magnetic foils with composition Fe50Ni50, Fe35Ni65 and Fe22Ni78. Morphological and structural properties of the deposited films were investigated using scanning electron microscopy, Rutherford backscattering spectrometry, grazing incidence X-ray diffraction, and X-ray reflectivity. Electrical and magnetic characteristics of the films were investigated by using the four-point probe and the magneto-optic Kerr effect techniques, respectively. The film properties are strictly dependent on the Fe-Ni compositional ratio. 相似文献
62.
The present study is concerned with the determination of the optimal shape for a package containing multiple heating elements.
The optimization tool has been developed based on the inverse heat transfer (IHT) approach, incorporating a direct problem
solver, a numerical grid generator, a direct-differentiation sensitivity analyzer, and the conjugate gradient method. Shape
design that leads to a specified outer surface temperature distribution is predicted by the approach. In this study, the effects
of internal heat generation on optimal shapes of the packagings have also been evaluated. Several practical cases with various
imbedded heating elements and thermal conditions are studied. Results show that the approach provides an efficient computer-aided
design scheme for the shape profile determination. 相似文献
63.
介绍了电泳技术制备YBCO高温超导厚膜的实验方法和YBCO高温超导厚膜的电学性质测量 ,讨论了在学生小型科研实验或设计实验中开展此实验的学时安排、注意事项和实验内容的扩展 . 相似文献
64.
Frictionless indentation responses of transversely isotropic piezoelectric film/rigid substrate systems under circular cylindrical indenter (i.e., punch), conical indenter (i.e., cone), and spherical indenter (i.e., sphere) are investigated. Both insulating and conducting indenters are considered. The technique of Hankel transformation is employed to derive the corresponding dual integral equations for the mixed boundary value indentation problems. For the two limiting cases of infinitely thick and infinitely thin piezoelectric films, closed-form solutions are obtained. For piezoelectric films of finite thickness, a numerical method is constructed to solve the dual integral equations and semi-empirical models having only two unknown parameters are proposed for the responses of indentation force, electric charge and electric potential, and contact radius. With the two parameters inferred from the numerical results, the semi-empirical formulae are found to provide good estimates of the indentation responses for the two limiting cases of infinitely thick and thin piezoelectric films, as well as those in between. The inferred parameters in the proposed semi-empirical formulae for normalized indentation force and electric charge are checked against four different piezoelectric materials and are found to be insensitive to the selection of piezoelectric materials. It is believed that the proposed semi-empirical indentation formulae are useful in developing experimental indentation techniques to extract the material properties of piezoelectric films. 相似文献
65.
Tie-Jun Liu Yue-Sheng Wang Chuanzeng Zhang 《Archive of Applied Mechanics (Ingenieur Archiv)》2008,78(4):267-282
The main interest of this study is a new method to solve the axisymmetric frictionless contact problem of functionally graded
materials (FGMs). Based on the fact that an arbitrary curve can be approached by a series of continuous but piecewise linear
curves, the FGM is divided into a series of sub-layers with shear modulus varying linearly in each sub-layer and continuous
at the sub-interfaces. With this model, the axisymmetric frictionless contact problem of a functionally graded coated half-space
is investigated. By using the transfer matrix method and Hankel integral transform technique, the problem is reduced to a
Cauchy singular integral equation. The contact pressure, contact region and indentation are calculated for various indenters
by solving the equations numerically.
An erratum to this article can be found at 相似文献
66.
Multiwalled carbon nanotubes were modified by carboxy groups. Four independent methods for the determination of the degree
of functionalization of the surface were proposed: 13C NMR spectroscopy, thermogravimetry, titrimetry, and fluorimetry. The first two methods show the total content of carboxy
groups in the sample, and the latter two methods give information about the content of the surface groups only.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 291–295, February, 2008. 相似文献
67.
宁波城市设计的若干思考与建议 总被引:1,自引:0,他引:1
张柳燕 《宁波大学学报(理工版)》2004,17(2):166-169
通过探讨城市设计概念的形成过程和历史积淀,阐明其在城市建设中的意义,并运用城市设计的理论与分析方法,针对目前宁波城市大规模的规划、设计、改造现象,提出若干思考与建议. 相似文献
68.
Efficiencies of the maximum pseudolikelihood estimator and a number of related estimators for the case-cohort sampling design in the proportional hazards regression model are studied. The asymptotic information and lower bound for estimating the parametric regression parameter are calculated based on the effective score, which is obtained by determining the component of the parametric score orthogonal to the space generated by the infinite-dimensional nuisance parameter. The asymptotic distributions of the maximum pseudolikelihood and related estimators in an i.i.d. setting show that these estimators do not achieve the computed asymptotic lower bound. Simple guidelines are provided to determine in which instances such estimators are close enough to efficient for practical purposes. 相似文献
69.
基于错误概率达到最小的原则,该文在罐子模型序贯试验中构造了一种渐近最优设计。在这种设计下,不仅能使病员以较多机会分配到较好的处理,而且能使估计量的统计效率在一定意义下达到最优。 相似文献
70.
The paper analyzes new publications on the brittle fracture mechanics of prestressed materials. It is found out that new scientific results published in the International Journal of Solids and Structures in 2002 are a particular case of the results obtained at the Institute of Mechanics 20 years ago 相似文献