混凝土氯离子含量快速测定仪示值误差的校准

混凝土氯离子含量测定仪是采用氯离子选择性电极法测定混凝土中氯离子含量的计量器具,在建筑行业应用很广,国内尚没有相关计量规程规范。结合CLU-V型混凝土氯离子含量快速测定仪,分析其工作原理,对示值误差的校准方法进行探讨。     

质子导体材料的研究进展

质子导电性固体电解质(简称质子导体)具有广泛的应用前景,近年来成为研究的热点,文中介绍了有关质子导体材料的的研究进展,其中包括有机和无机质子导体材料的发展现状与存在的问题,并展望了质子导体材料的发展前景。     

混合导体透氧膜的制备及其应用

介绍了混合导体透氧膜在天然气增值转化中的重大应用，综述了近年来我国在混合导体透氧膜材料的开发及其在甲烷部分氧化制合成气反应过程中的应用。     

树脂吸附稀醋酸中氯离子的应用研究

本文通过对树脂吸附稀醋酸中的氯离子情况的介绍,结合其检测的一些实验数据,提出了树脂对稀醋酸中氯离子吸附的应用可行性分析,以供相关的生产人员参考。     

涂层导体的研究进展

据互联网报道,美国能源部在2002年1月召开了一次有关研发高温超导线材的研讨会,全面总结了至今世界各地研制YBCO涂层导体的进展,讨论了电力和工业应用对涂层导体的要求,并展望了涂层导体发展的前景和目标.     

高纯金属与半导体材料

601495半导体应变片和半导体应变片式传感器一(巫昊),《电子技术应用》,1973年,灿28一31 本文对半导体应变片的基本原理和特点及其在传感器上的应用作了一些介绍和讨论。     

盐雾环境下受荷混凝土中氯离子扩散试验

针对海洋盐雾环境,开展不同荷载水平作用下混凝土中氯离子扩散试验,测试混凝土中不同深度的氯离子含量,总结混凝土中氯离子扩散规律,拟合氯离子扩散荷载影响系数与构件应力状态之间的关系式。结果表明,拉应力作用下混凝土中氯离子含量增加,氯离子扩散系数增大;压应力作用下混凝土中氯离子含量降低,氯离子扩散系数减小;氯离子扩散系数随着时间增加逐渐减小,表面氯离子浓度随着时间的增加逐渐增大。考虑荷载影响的氯离子扩散模型可为预测实际工程受荷混凝土结构的使用寿命提供参考。     

质子-电子混合导体透氢膜

随着氢能源的到来,一种基于质子—电子混合导体透氢膜材料受到人们的普遍关注.质子—电子混合导体分为双相和单相混合导体两类.本文重点综述了上述两类质子-电子混合导体透氢膜的发展近况,并阐述了其透氢原理,分析了在氢分离等方面的应用,对其发展前景和方向进行了展望.     

电化学脱盐对结合氯离子稳定性的若干影响因素研究

采用电化学脱盐方法对砂浆试块进行电化学除氯,研究了电场作用下若干影响因素(水灰比、阳离子类型、氯离子浓度、矿物掺合料等)对结合氯离子失稳释放的影响。结果表明:随着水灰比增大,结合氯离子在电场作用下的稳定性减弱,结合氯离子释放能力增强。电场作用下阳离子类型不同的砂浆试块结合氯离子失稳释放能力的大小顺序为:Ca2+Mg2+≈Na+K+。在1%~5%的氯离子浓度范围内,3%氯离子浓度下结合氯离子转化率最高,结合氯离子释放能力在高氯离子浓度和低氯离子浓度下都会出现下降的情况。硅粉会降低电场作用下结合氯离子的释放能力;随着矿粉产量的增加,结合氯离子转化率也逐渐增大,说明矿粉可促进电场作用下结合氯离子的释放,增强脱盐时结合氯离子的释放能力;粉煤灰对电场作用下结合氯离子的释放也有促进作用,且粉煤灰掺量在20%左右时结合氯离子的释放能力最强。     

氧离子-电子混合导体透氧膜的发展及应用

氧离子-电子混合导体分为单相和双相混合导体两类。本文详细综述了单、双相混合导体透氧膜的研究进展及其在甲烷部分氧化制合成气、固体氧化燃料电池和CO2高温分解膜反应器中的应用,并阐述了其氧传输机理,对此类材料的发展前景和方向进行了展望。     

Errors in near-field radioholography

Formulae are given for the aperture plane phase errors which are incurred in near-field radioholography of reflector antennas when a simple Fresnel correction is used. Approximate analytic expressions are derived for circular data windows and antennas with parabolic illumination taper. Infocus and defocused cases are treated. Numerical simulations are used for estimating errors for square data windows     

Consistent mapping of common cause failure rates and alpha factors

The problem addressed is how to combine event experience data from multiple source plants to estimate common cause failure (CCF) rates for a target plant. Alternative models are considered for transforming CCF parameters from systems with different numbers of similar components to obtain CCF-rates for a specific group of components. Two sets of rules are reviewed and compared for transforming rates and assessment uncertainties from larger to smaller systems, i.e. mapping down. Mapping down equations are presented also for the alpha-factors and for the variances of CCF rates. Consistent rules are developed for mapping up CCF-rates and uncertainties from smaller to larger systems. These mapping up rules are not limited to a binomial CCF model. It is shown how consistency requirements set certain limits to possible parametric values. Empirical alpha factors are used to estimate robust mapping parameters, and mapping up equations are derived for alpha factors as well. An assessment uncertainty procedure is presented for treating incomplete or vague information when estimating CCF-rates. Numerical studies illustrate mapping rules and procedures. Recommendations are made for practical applications.     

Analytical relations for thin-film total internal reflection phase retarders

Single-layer coatings on total internal reflection boundaries that produce any specific phase retardation are analyzed. One- and two-reflection phase-retarding systems are considered. Simple quadratic equations are obtained for an unknown layer phase thickness at a given angle of incidence and phase retardation. Equations for specific multilayer coatings that are equivalent to single-layer designs are also deduced. Diagrams of solution zones for refractive indices are given comparatively for one- and two-reflection systems.     

Properties,applications and manufacture of wear-resistant hard material coatings for tools

Wear processes during machining with cemented carbides and the effect of coatings on wear and on toughness are described. The requirements for coatings relating to optimum tool life are reviewed. Recently developed multilayer coatings with and without ceramic layers are described and examples for improvements in the tool lifetime are given. Additionally, some examples for the application of coatings for milling and chipless forming are presented.The wear-reducing effect of coatings on steel tools is described and possibilities for applications of steel tools coated using chemical vapour deposition (CVD) are elucidated. A number of examples for coated cutting and chipless forming steel tools are described.Finally, useful processes for the coating production are considered. A comparison between physical vapour deposition and CVD processes with respect to the coating temperature, the consistency and the adhesion of the coating is presented. The CVD process for economic production is considered and a suitable coating unit is outlined.     

Reliability analysis of hydraulic systems of LHD machines using the power law process model

Earlier, a preliminary study of the reliability characteristics of a fleet of load-haul-dump (LHD) machines deployed at Kiruna mine showed that the engine and the hydraulics are the two most critical subsystems. Hydraulic systems are selected for further study because such systems are still under a development phase. Maintenance data for two years for these machines are analyzed. The tests for trends and serial correlation showed that times between successive failures for the hydraulic systems are in most cases not independent and identically distributed. Goodness-of-fit tests showed that the power law process model provides a good fit to the failure data of the hydraulic systems. Methods for parameter estimation in the power law process model and estimation of optimal maintenance intervals for such systems are presented. Emphasis is on the use of graphical methods for data analysis.     

Simulation of wave propagation in three-dimensional random media

Quantitative error analyses for the simulation of wave propagation in three-dimensional random media, when narrow angular scattering is assumed, are presented for plane-wave and spherical-wave geometry. This includes the errors that result from finite grid size, finite simulation dimensions, and the separation of the two-dimensional screens along the propagation direction. Simple error scalings are determined for power-law spectra of the random refractive indices of the media. The effects of a finite inner scale are also considered. The spatial spectra of the intensity errors are calculated and compared with the spatial spectra of intensity. The numerical requirements for a simulation of given accuracy are determined for realizations of the field. The numerical requirements for accurate estimation of higher moments of the field are less stringent.     

Vibration of infinite piezoelectric cylinders with anisotropic properties using cylindrical finite elements

Natural frequencies for free vibration of infinite piezoelectric cylinders are computed using finite elements that are formulated in cylindrical coordinates. The finite-element method is used to model the cross-section of the cylinder in r, theta coordinates using circular sectors. Material constants that are functions of theta are allowed to vary in each circular sector and are computed using standard tensor transformations. The accuracy of the finite-element formulation is verified using previous results for isotropic cylinders and axisymmetric piezoelectric cylinders. New results are tabulated for frequencies of free vibration of solid and hollow piezoelectric cylinders of LiNbO(3) of crystal class 3m. Displacements for typical mode shapes are illustrated graphically.     

Higher-order extrema in two-dimensional wave fields

Higher-order extrema with topological indices greater than unity are discussed. Explicit constructions are given for their wave functions, and simple geometric rules are presented for analysis of their topological indices. Experimental means for verifying the theory with use of Gaussian laser beams are considered, unusual properties of optical vortices constructed from this new type of critical point are described, and applications to topologically based optical arithmetic are suggested.     

Interacting dissimilar semi-elliptical surface flaws under tension and bending

Stress intensity factors for two dissimilar interacting semi-elliptical coplanar surface flaws (cracks) in a semi-infinite elastic body are obtained under overall tension and bending. First the basic equations for a general planar crack normal to the free surface are established, using the method of equivalent eigen- or transformation strains (the body force method). Then the results are specialized for application to elliptical cracks. Numerical values are obtained for various configurations and crack shapes. Results are compared with those of two-dimensional collinear cracks. Finally, an approximate procedure for estimating the stress intensity factors for a general three-dimensional crack is suggested.     

Nonlocally related PDE systems for one-dimensional nonlinear elastodynamics

Complete dynamical PDE systems of one-dimensional nonlinear elasticity satisfying the principle of material frame indifference are derived in Eulerian and Lagrangian formulations. These systems are considered within the framework of equivalent nonlocally related PDE systems. Consequently, a direct relation between the Euler and Lagrange systems is obtained. Moreover, other equivalent PDE systems nonlocally related to both of these familiar systems are obtained. Point symmetries of three of these nonlocally related PDE systems of nonlinear elasticity are classified with respect to constitutive and loading functions. Consequently, new symmetries are computed that are: nonlocal for the Euler system and local for the Lagrange system; local for the Euler system and nonlocal for the Lagrange system; nonlocal for both the Euler and Lagrange systems. For realistic constitutive functions and boundary conditions, new dynamical solutions are constructed for the Euler system that only arise as symmetry reductions from invariance under nonlocal symmetries.