Measuring interdiffusion at an interface between two elastomers with tapping-mode and contact-resonance atomic force microscopy imaging

Despite the common use of tapping-mode atomic force microscopy to image composites or polymer blends, very few studies have focused on the measurement of the interdiffusion at an interface between two polymers in contact. In this study, we show how to assess the interphase between two polymers with two methods. First, stable and robust tapping conditions are established, and the problem of the phase contrast is discussed. Second, a contact-resonance method is presented: the tip in contact with the sample is electrostatically excited at its resonance frequency by a self-controlled oscillator. The gain and frequency images allow us to measure the interdiffusion width. Both methods (using high and weak mechanical solicitation) give the same assessment of the interdiffusion width. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Wave drift force in a two-layer fluid of finite depth

Based on the momentum and energy conservation principles, a compact calculation formula is analytically derived for the wave-drift force on a 2-D body floating in a two-layer fluid of finite depth. In a two-layer fluid, two different wave modes (the surface-wave mode with longer wavelength and the internal-wave mode with shorter wavelength) exist not only in the incident wave but also in the body-scattered wave, and these wave characteristics are properly incorporated in the obtained formula. It is noted that, unlike the single-layer case, the wave-drift force can be negative in the incident wave of surface-wave mode, if the transmitted wave with internal-wave mode is large. Numerical computations are implemented for a Lewis-form body by means of the boundary-integral-equation method with Green’s function for the two-layer fluid problem. The effects of density ratio, interface position, and body motions on the wave-drift force are studied, and some important features are found for two-layer fluids.     

技术进步经济效益评价——中国长城铝业公司水泥厂产出增长中技术进步作用的评价

本文通过运用“生产函数法”、“增长速度方程”来定量分析技术进步在长城铝业公司水泥厂产出增长中的作用,从中找出该水泥厂生产经营过程中存在的问题及未来发展方向。     

谈用三爪卡盘装夹车削钢件时的切削用量

指出根据《金属切削手册》给出的切削用量范围确定切削用量，有可能不适当，特别是在三爪卡盘装夹硬度低的半径小的工件时容易发生这种情况，提出根据工件硬度、夹持长度、三爪的夹持半径等诸因素确定切削用量的方法。     

TbFe磁性薄膜的磁力显微镜成像研究

利用磁力显微镜（MFM）对TbFe磁性薄膜进行了不同抬举距离（分别为60～780nm）的磁力成像研究．在实验中，比较了低抬举距离（100nm以下）磁力像中样品-针尖的互相干扰；同时发现在高抬举距离磁力像中，随着抬举距离的增大，出现了与高凸起形貌对应的图像衬度特征，并随抬举距离的变化也改变着位置与强度，一直到抬举距离为仪器的极限值780nm时，形貌干扰仍未消失，对其形成机制进行了分析．     

Second-order Wagner theory of wave impact

The paper deals with the two-dimensional unsteady problem of the impact of a liquid parabola onto a rigid flat plate at a constant velocity. The liquid is assumed ideal and incompressible and its flow potential. The initial stage of the impact is the main concern in this study. The non-dimensional half-width of the contact region between the impacting liquid and the plate plays the role of a small parameter in this problem. The flow region is subdivided into four parts: (i) the main flow region, the dimension of which is of the order of the contact-region width, (ii) the jet-root region, where the curvature of the free surface is very high and the flow is strongly nonlinear, (iii) the jet region, where the flow is approximately one-dimensional, (iv) the far-field region, where the flow is approximately uniform at the initial stage of impact. A second-order solution in the main flow region has been derived and matched to the first-order inner solution in the jet-root region. The matching conditions provide an estimate of the dimension of the contact region for small time. Pressure distributions in both the main flow region and the inner region are derived. The accuracy of the obtained asymptotic formulae is estimated. The second-order hydrodynamic force acting on the plate is obtained and compared with available experimental data. A fairly good agreement is reported.     

P–I diagram method for combined failure modes of rigid-plastic beams

Closed-form solutions of pressure-impulse (P–I) diagrams for simply supported and fully clamped rigid-plastic beams subjected to impact load are developed. Two failure categories, i.e., bending failure and shear failure, are considered and the responses of the beams are analyzed based on five transverse velocity profiles. With proper failure criteria, the critical P–I equations for bending and shear failure are derived. After the simplification of the critical P–I equations, the influences of the shear-to-bending strength ratio and the boundary conditions on the P–I diagrams are discussed. The results are compared with those based on a single-degree-of-freedom (SDOF) model. It is shown that the proposed P–I diagram method can be conveniently applied to assess beam damage extents and damage patterns. Especially, the P–I diagrams have good agreement with those based on an elastic, perfectly plastic model when severe damage occurs.     

考虑次内力的桁架结构有限元分析

用有限元软件ANSYS对带式输送机栈桥的桁架结构进行了计算，结合实例着重探讨了考虑次内力时的桁架结构有限元分析在建模过程中需要解决的问题。     

波浪力计算中的一个新边界元方法

本文就波浪与结构物作用问题，提出了一个新的高阶边界元方法。较之Ｅａｔｏｃｋ Ｔｏｙｌｏｒ和Ｃｈａｕ的方法，本文在体内附助积分方程中应用了满足刚性水面条件和弱刚性底面条件的简单格林函数。计算速度相应地有所提高；漂浮结构的积分方程更为简洁；计算结果与Ｅａｔｏｃｋ Ｔａｙｌｏｒ和Ｃｈａｕ的方法具有几乎相同的精度和收敛速度。     

单线循环客运索道设计参数研讨(续三)

论证客运索道设计中的几个重要参数,建立抱索器钳口夹紧力计算公式,第一次给出钳口夹紧力与钢索金属断面积的比值,并进行了钢索弯曲应力计算公式的推导.