Static Analysis of Functionally Graded Sandwich Plates Using an Efficient and Simple Refined Theory

In this paper, a new displacement based high-order shear deformation theory is introduced for the static response of function-ally graded sandwich plate. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, has strong similarity with classical plate theory in many aspects, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. Two common types of functionally graded sandwich plates, namely, the sandwich with functionally graded facesheet and homogeneous core and the sandwich with homogeneous facesheet and functionally graded core, are considered. Governing equations are derived from the principle of virtual displacements. The closed-form solution of a simply supported rectangular plate subjected to sinu-soidal loading has been obtained by using the Navier method. The validity of the present theory is investigated by comparing some of the present results with those of the classical, the first-order and the other higher-order theories. It can be concluded that the proposed theory is accurate and simple in solving the static bending behavior of functionally graded sandwich plates.     

Microstructure and Magnetic Anisotropy of FeCoNbB Films

Effect of Nb contents on microstructure and magnetic properties of FeCoNbB films has been studied. X-ray diffraction (XRD) analysis reveals that Nb plays a role in refining grain and in facilitating formation of amorphous structure. When Nb content is more than 8 at%, the films transform from crystalline to amorphous structure, accompanied by variations in magnetic properties. An unusual out-of-plane anisotropy component is consequently observed. It can be suggested that the anisotropy induced by increasing Nb contents be attributed to stress-related magnetoelastic anisotropy. The undesirable anisotropy is greatly reduced by thermal annealing, reducing film thicknesses or applying an external magnetic field together with Si addition.     

己二酸酯类增塑剂向橄榄油中迁移量的测定方法

采用精馏橄榄油为模拟物,对PVC食品接触材料中四种己二酸酯类增塑剂向脂类食品模拟物的迁移量进行了检测,并对萃取条件和萃取试剂进行了优化,采用GC—MS技术,通过外标法进行迁移量的检测。研究表明,此方法具有方法简便,重现性好,灵敏度高,定性、定量准确可靠的特点,最低检测限可达5mg／kg,回收率为83．20％～106．13％,标准偏差为1．60％～3．34％,可实际应用于PVC食品接触材料己二酸酯类增塑剂迁移量的检测。     

姿态航向参考系统中磁罗盘安装误差补偿研究

在飞行状态下,姿态航向参考系统的航向由磁航姿计算机的姿态和磁罗盘的磁通量算得,由于磁罗盘和航姿计算机在机上有安装误差,使得算出的航向有一定偏差,针对这一问题,文章提出了一种补偿机上磁罗盘安装误差的方法。机上试验表明:该方法补偿了磁罗盘在机上的安装误差,可有效提高磁航向的精度。     

Fundamentals of Design and Technology of Rolling Element Bearings

This article presents an overview of fundamentals of rolling element bearing designs and technologies. The aim is to outline the complex interrelation of all fundamentals with the rolling contact fatigue and the attainable bearing life. Such fundamentals include, amongst others, bearing stressing and life capability. The article shows the different types of rolling bearing stressing and the analysis of the stress distribution (principal stresses and equivalent stresses) in the material under the rolling contact area. It becomes obvious that the contamination of the bearing with foreign particles leads to a drastic reduction in bearing life. Furthermore, it demonstrates the impact of the bearing lubrication and coating as well as the effect of additives on the attainable life and wear. Further fundamentals of rolling element bearing design are the materials, the material cleanliness and the heat treatment. The article reveals the importance of the cleanliness of bearing steels as well as different types of inclusions and their effect on rolling contact fatigue. Additionally the article describes how to optimize the material properties (strength, toughness and residual stress) by the heat treatment processes. The outcome of these investigations is that endurance life of a rolling element bearing can be achieved if specific operating conditions, an adequate lubrication, good system cleanliness and specific bearing stressing are met. The article provides a guideline for bearing engineers on how designs and technologies can be applied to optimizing a bearing for a particular industry or aerospace application.     

Solar MHD Waves and Solar Neutrinos

We analyze here how solar neutrino experiments could detect time fluctuations of the solar neutrino flux due to magnetohydrodynamics (MHD) perturbations of the solar plasma. We state that if such time fluctuations are detected, this would provide a unique signature of the Resonant Spin-Flavor Precession (RSFP) mechanism as a solution to the Solar Neutrino Problem. This revised version was published online in August 2006 with corrections to the Cover Date.     

航材管理中的成本控制与保障率组合研究

从系统角度考察航材成本与保障率的关系，研究影响保障率的动因，并将各种因素同成本对应起来，旨在实现以最合适的成本保证公司运营效率最大化的目标，以及从需求出发制定确实有效的成本改进方法。     

航天钐钴永磁直流电动机

阐述了导弹用高功率／重量比直流电动机的电磁设计和结构设计。电磁设计的重点在于电磁参数的确定和分级优化确定转子及磁钢的尺寸；结构设计的重点在于磁钢的固定和绕组端部的固定，经样机和小批生产均取得极为满意的结果。     

Comparison of heliospheric conditions near the earth during four recent solar maxima

Statistical properties of the daily averaged values of the solar activity (sunspot numbers, total solar irradiance and 10.7 cm radio emission indices), the solar wind plasma and the interplanetary magnetic field parameters near the Earth’s orbit are investigated for a period from 1964 to 2002 covering the maxima of four solar cycles from 20th to 23rd. Running half-year averages show significant solar cycle variations in the solar activity indices but only marginal and insignificant changes in comparison with background fluctuations for heliospheric bulk plasma and magnetic field parameters. The current 23rd cycle maximum is weaker than 21st and 22nd maxima, but slightly stronger than 20th cycle in most of solar and heliospheric manifestations.     

Asymmetric magnetic field inside a cylindrical flux rope

In order to consider an asymmetric field distribution inside a cylindrical tube with a circular cross section, with the field magnitude maximum reached at a point different from the geometrical centre of the tube, we propose a new solution obtained in bi-cylindrical coordinates. If the parameter of the system is very large, the solution approaches the well known symmetric Lundquist solution. The new solution models a field magnitude shift due to relative motion of the cylinder and the ambient solar wind. If the cylinder is moving much faster than the ambient medium, its field maximum is shifted forward, otherwise it is shifted in the opposite direction.