相关分析与谱分析在表面形貌研究中的应用

本文通过对表面形貌进行相关分析与谱分析,提出了相对波度和有效波度、相对波长和有效波长的概念,并且指出相关分析与谱分析是研究表面形貌润滑效应的有力工具。作者认为,当相对波度为有效波度时,应当同时考虑波长和幅值的摩擦学效应;当相对波度为高频的粗糙度时,只需考虑表面形貌的幅值效应。     

Phase split of liquid–liquid two-phase flow at a horizontal T-junction

This paper provides data on the split of liquid/liquid two-phase flow at a horizontal T-junction. Phase maldistribution was measured for kerosene–water flow at the T-junction with equal pipe diameters of 67.4 mm. Data were taken with both stratified flow with a mixture at interface and dispersed flows approaching the junction. The degree of phase maldistribution was not very great but preferential emergence of either phase from the side-arm was observed depending on the flow rates of the two-phases. There are similarities with the limited split data from liquid/solid flows and the degree of separation is seen to depend on the dispersed/continuous phase density ratio. The data were compared to predictions from the correlation by Seeger et al. The Seeger equation gives but reasonable agreement.     

冲击载荷形状对阻尼介质中结构最终塑性变形的影响

分析了在阻尼介质中当保持相关参量相同时，冲击载荷形状对简支刚塑性圆板和圆柱薄壳的最终塑性变形的影响。在结构物高载阶段的运动中，考虑了阻尼介质对塑性铰区移行的影响。结果表明:在阻尼介质中，文献［６］中相关参量的概念仍然可以沿用，但结构的最终塑性变形与相关参量的关系式Ｗ＿ｏｆ＝Ｉ￣２＿ｅＧ（Ｐ＿ｅ）应由更一般的表达式来代替。     

GPS技术在金川露天矿边坡变形监测中的应用

本文结合金川露天矿边坡变形GPS监测研究，主要论述监测基点的选择，基点WGS-84坐标的确定，变形监测网的布设，GPS数据采集、处理和质量，坐标转换的实施等，给出反演推出的若干四等三角点及其它控制点的变形数据，这些数据和造成变形的物理成因符合得很好，最后概括出GPS技术应用于变形观测的若干优点。     

Reynolds stress, mean velocity, and dynamic static pressure measurement by a four-hole pressure probe

An improved version of the four-hole directional pressure probe, or Cobra probe, is described, in which the frequency response has been extended to 1.5 kHz. The probe measures all three orthogonal mean and turbulent velocity components at a point in the flow field. The probe also resolves the local mean and turbulent components of static pressure, allowing moments between the fluctuating velocity components and pressure to be determined. The techniques developed to allow the improved frequency response and the use of the probe in turbulent, developed pipe flow (a calibration flow) are described. Also given are the turbulent pressure-velocity correlations, which show a high degree of anticorrelation for one velocity component.     

Shape memory behavior in Fe3Al-modeling and experiments

The Fe₃Al alloy with D0₃ structure exhibits large recoverable strains due to reversible slips. Tension and compression experiments were conducted on single crystals of Fe₃Al, and the onset of slip in forward and reverse directions were obtained utilizing high-resolution digital image correlation technique. The back stress provides the driving force for reversal of deformation upon unloading, resulting in a superelastic phenomenon as in shape memory alloys. Using density functional theory simulations, we obtain the energy barriers (GSFE – generalized stacking fault energy) for {1?1?0}〈1?1?1〉 and {1?1?2}〈1?1?1〉 slips in D0₃ Fe₃Al and the elastic moduli tensor, and undertake anisotropic continuum calculations to obtain the back stress and the frictional stress responsible for reversible slip. We compare the theoretically obtained slip stress magnitudes (friction and back stress) with the experimental measurements disclosing excellent agreement.     

Characterization of the channel walls roughness in photonic crystal fibers

We present electron microscope (FEI NanoSEM) and atomic force microscopy measurements of surface roughness in nanochannels in photonic crystal fibers (PCF). A method was invented to cleave the PCF along the axis without damaging the surface structure in the nanochannels allowing us to characterize the morphology of the nanochannels in the PCF. A multi-wall carbon nanotube mounted onto commercial AFM probes and super sharp silicon non-contact mode AFM probes were used to characterize the wall roughness in the nanochannels. The roughness is shown to have a Gaussian distribution, and has an amplitude smaller than 0.5 nm. The height–height correlation function is an exponential correlation function with an autocorrelation length of 13 nm, and 27 nm corresponding with scan sizes of 200×100 nm², and 1600×200 nm², respectively.     

Bochner-Kodaira Techniques on K¨ahler Finsler Manifolds

A horizontal Hodge Laplacian operator $\square_{\mathcal {H}}$ is defined for Hermitian holomorphic vector bundles over PTM on K¨ahler Finsler manifold, and the expression of $\square_{\mathcal {H}}$ is obtained explicitly in terms of horizontal covariant derivatives of the Chern-Finsler connection. The vanishing theorem is obtained by using the $\partial_{\mathcal {H}}\ov{\partial}_{\mathcal {H}}$-method on K¨ahler Finsler manifolds.     

Predicting Polymorphism of Electrospun Polyvinylidene Fluoride Membranes by Their Morphologies

Although electrospinning of polyvinylidene fluoride (PVDF) has been studied for more than 10 years, the crystalline phase differentiation of the electrospun mats is still normally through the combination of different characterization techniques, and the relationship between polymorphism and morphology of the fibers in electrospun PVDF membranes has never been reported. Here, we show their close relationships by conducting room-temperature electrospinning experiments on various polymer/solvent systems. The electrospun membranes full of bead-free fibers have a very high fraction of β-phase, F(β), over 90%, and high orientation, whereas the membranes comprising beads and/or a large number of beaded fibers most often result in a low fraction of β-phase (F(β) normally below 50%) and low orientation. On the other hand, electrospun membranes consisting of both bead-free fibers and a very limited number of beaded fibers showed a medium high fraction of β-phase, F(β) more than 70% but less than 90%. These findings suggest the feasibility of intuitively predicting the crystalline phase of electrospun PVDF membranes directly by their morphologies, which is obviously simple, inexpensive and convenient for future investigations.