Static analysis of point-supported super-elliptical plates

This paper reports the static analysis of point-supported super-elliptical plates of uniform thickness subjected to a uniformly distributed lateral load. The plate perimeter was defined by a super-elliptic function with a power, corresponding to shapes ranging from an ellipse to a rectangle. The analysis was based on the Kirchhoff–Love plate theory and the computations were carried out by the Ritz method. Lagrange multipliers were used to satisfy the boundary conditions. Isotropic and homogeneous plates with 20 different shapes were examined for two distinct aspect ratios. Convergence studies were performed for the central deflection and the central bending moments. The results were checked against those of a corner-supported square plate and good agreement was obtained.     

蜃景效应及其光热偏转光谱

本文介绍一种十分灵敏的探测固体表面、液体和薄膜材料光学和热学特性的新方法.这一方法──光热偏转光谱技术,是通过探测被加热待测样品表面的热梯度的途径进一步确定其光学和热学特性.应用这种探测技术在室温和低温条件下所作的测试结果表明,它比其它方法都显得优越.     

Infrared Photothermal Deflection Spectroscopy of Carbon-Supported Metal Catalysts

The infrared (IR) study of surface species and reactions occurring on solids has contributed markedly to our understanding of surface chemistry and heterogeneous catalysis, and a wide variety of solids has been examined. However, an entire class of catalysts consisting of metal dispersed on carbon has never been studied because the carbon catalyst support absorbs IR radiation so strongly in even the thinnest practical layers that conventional IR techniques fail. As IR data would be helpful in understanding how such catalysts function, we have explored the feasibility of examining carbon-supported catalysts with photothermal beam deflection spectroscopy (PDS) and describe the first IR spectra ot surface species on a Ni-on-carbon catalyst.     

求解集中载荷作用下悬臂板的挠曲方程

应用功的互等定理,求解了悬臂厚矩形板在集中载荷作用下的挠曲面方程;同时也通过编程计算给出了具有实际价值的计算结果,进一步证明了应用功的互等法求解厚矩形板的正确性和优越性.     

Constructal design method dealing with stiffened plates and symmetry boundaries

A new computational procedure for modelling the structural behavior of stiffened plates with symmetry boundary conditions is here presented. It uses two-dimensional finite elements as a way to decrease computational time without losing precision thanks to a relatively small number of elements applied for analyzing out-of-plane displacements (deflections) and stresses. Adding, the constructal design method was included in the procedure, together with the exhaustive search technique, with the scope to optimize the stress/strain status of stiffened plates by design changes. For the purpose, a reference plate without stiffeners was initially design and used as starting point. Part of the volume was reshaped into stiffeners: thickness was reduced maintaining unchanged weight, length and width. The main goal was to minimize strains and stresses by geometric changes. Results demonstrated that, thanks to this design procedure, it is always possible to find an adequate geometry transformation from reference plate into stiffeners, allowing significant improvements in mechanical behavior.     

Optical polarization measurement for measuring deflection radius of the optically anisotropic flexible-polymeric substrate

This study proposes an optical methodology to measure the deflection radius of flexible polymeric substrates; to our best knowledge, this is the first report taking into consideration the optical anisotropy effect of these substrates for such measurements. The relation between the deflection-induced optical phase retardation of two distinct refraction beams and the deflection radius was derived. Full-field phase maps were obtained via a polarization measurement system and the phase-stepping technique. The measurement results for three substrates having nominal deflection radii of 50, 55, and 60 mm were, correspondingly, 51.39 ± 0.37, 57.56 ± 1.00, and 58.71 ± 0.85 mm (error = 2.78%, 4.65%, and 2.15%, respectively); thus, the measurement precision was confirmed.     

Deflection of high-energy negative particles in a bent crystal through axial channeling and multiple volume reflection stimulated by doughnut scattering

Different kinds of deflection in a silicon crystal bent along the 〈111〉 axis was observed for 150 GeV/c   negative particles, mainly π⁻${\pi }^{-}$ mesons, at one of the secondary beams of the CERN SPS. The whole beam was deflected to one side in quasi-bound states of doughnut scattering (DSB) by atomic strings with the efficiency (95.4 ± 0.2)% and with the peak position close to the bend crystal angle, α=185 μrad$\alpha =185\text{μrad}$. It was observed volume capture of π⁻${\pi }^{-}$ mesons into the DSB states with a probability higher than 7%. A beam deflection opposite to the crystal bend was observed for some orientations of the crystal axis due to doughnut scattering and subsequent multiple volume reflections of π⁻${\pi }^{-}$ mesons by different bent planes crossing the axis.     

Analysis of space off-axis and performance of Cassegrain optical antenna system

The research of optical antenna is of greatest importance in the field of modern optical communication. For optical antenna, alignment of optical system is a significant factor, which influences the transmission quality of optical antenna system. Antenna off-axis is one of the important factors influencing the transmission quality of optical antenna system. In this paper, we analyze and numerically simulate how power attenuation ratio and gain of Cassegrain antenna vary with the antenna deflection angle and the distance that the central axis of receiving antenna deviates from z-axis, when space off-axis happens to the system. Finally, the coupling efficiency of Cassegrain antenna is tested experimentally, and the results show that the coupling efficiency of the Cassegrain antenna dramatically reduces in the case of off-axis. These studies provide a theoretical basis for optical antenna system to achieve accurate alignment in optical communication.     

Second order Kerr deflection

We perform a full second order calculation of the deflection of light along the equatorial plane in the Kerr metric. Previous Kerr deflection calculations were interested in obtaining the correction due to rotation to the Einstein deflection. By expanding to first order in the rotational parameter a, they obtain the Einstein deflection of 4M/r _o and the second order deflection due to rotation of , (where r _o is the point of closest approach). In this paper, we are interested in going beyond the rotational contribution for the purpose of astrophysical applications. We therefore keep all terms up to second order in our final weak field expansion. Besides the rotational contribution, we also obtain an extra second order term of . Since M > a, this extra term is greater than the rotational contribution of in astrophysical applications. When a/M is close to unity the terms are of the same order of magnitude.