Analysis based on microcontact mechanism for the roughness dependent stick–slip motion

The stick–slip behavior occurring between an indenter with its round tip treated as a rigid sphere with a radius of 300 nm and the (1 0 0) Si specimen was considered. The characteristic slip distances were observed in the stick–slip behavior under small normal loads. A statistical evaluation of microcontact on the basis of Fourier cosine series was proposed to evaluate the dominant scales of roughness under different normal loads. The experimental results showed the elastic deformation exhibited in the contact between the indenter and the specimen when the contact load was smaller than 40 μN. The characteristic scales of roughness obtained by the proposed method revealed good agreement with the experimental results of slip distance under different contact loads. Through the proposed method, the roughness dependence of the stick–slip behavior can be further understood quantitatively.     

多孔氧枪喷头轴线上速度分布特征的研究

本文基于湍流时流理论，对多孔氧格喷头几何轴线上的速度分布特征进行了理论和实验研究．结果表明，多孔氧论喷头轴线上速度最大值的临界枪位可由下式计算并由大型喷头的实测结果得到了验证     

The beneficial effect of alkali metal salt on supported aqueous-phase catalysts for olefin hydroformylation

Alkali metal salt modified SAP (supported aqueous-phase) rhodium catalysts prepared by coimpregnation method using alkali metal chloride were found to be active and selective for olefin hydroformylation. The salt addition promoted the formation of aldehydes with high selectivity, the aldehyde yield being increased more than 2.5 times at a proper salt/Rh ratio. Changes in stretching frequency of the carbonyl species were detected during ethene hydroformylation, which appeared at ca. 1625 cm^–1 on the non-modified SAP catalyst sample, while at ca. 1586 cm^–1 on the KCl-modified one, as shown by in situ IR spectroscopy. The results of a deuterium isotope effect experiment showed that the hydroformylation rate for aldehyde formation on SAP rhodium catalyst under atmospheric pressure of CO/D₂ was about 1.3 times faster than that under CO/H₂, implying that the rate-determining step involved in aldehyde formation is most probably a step related with hydrogen. The role of the alkali metal salt is discussed in relation with the reaction mechanism.     

Electrooxidation of benzyl alcohol at high surface area nickel (NiS x ) electrodes in alkaline solution

The heterogeneous catalytic redox behaviour of NiS _x deposited electrodes was investigated with and without benzyl alcohol in KOH solution using cyclic voltammetry and linear sweep voltammetry. The limiting current density for benzyl alcohol oxidation on a NiS _x electrode was 22 times larger than that on a polished nickel electrode. The experimental results in galvanostatic electrolysis using fractional factorial design showed that the main and interaction effects of benzyl alcohol concentration, temperature, and OH^– concentration are the key variables influencing the selectivity of benzaldehyde formation during electrolysis.     

Automatic inspection of the width and gap of etching transistors in TFT-LCD panels using sub-pixel accuracy estimation

In this paper, the width and gap of etching transistors in TFT-LCD panels were measured using sub-pixel accuracy estimation, and the accuracy was tested in a noisy environment. The concept of line width measurement was introduced in terms of line distance and defect measurement based on the low and high spatial frequency distribution change of TFT-LCD panel image. Some patterns do not need to have the line width and distance measured, while others have different measurement requirements. The conductor border of a pattern is normally an area with a flat change of grey scale, but we are still able to find an accurate measurement with the proposed method. In the TFT-LCD testing pattern, there are circular etching structures, and for measurement we focus on the position of the center of the circle and the size of the radius. This method can be used quickly and accurately for measuring the TFT short, ITO open, marking, spot particle or scratching on the panel caused by over etching.     

A novel optimal working process in the design of parametric progressive dies

The objective of this study was to establish a genetic algorithm to solve the problems of ranking the working steps in progressive dies. The working area of punch in working station of progressive die was regarded as the basic reference for gene coding. The moment generated from punch to mold center is defined as fitness function. A common method, remainder stochastic sampling with replacement (RSSR), was adopted to carry out gene reproduction process calculation. We combined the fixed crossover rate and mutation rate to be the crossover and mutation process calculation basis and then obtained the optimum process in which the total moment relative to the mold center was at a minimum. Finally, we developed a “dimension-driven” Windows graphical program written in Visual C++ as an interface for parametric input and communicated with the ACAD software through a DXF file. This system is expected to be a helpful tool for designers facing demands for higher quality, lower cost and shorter delivery time for sheet metal products.     

Unconstrained and constrained curve fitting for reverse engineering

Curve fitting is commonly used in reverse engineering for the reconstruction of curves from measured points, and it is critically important to provide various kinds of curve-fitting algorithms to acquire curves that satisfy different constraint conditions. We divide the curve-fitting problem into unconstrained and constrained types. For the unconstrained type, three curve-fitting algorithms are investigated: general, smooth and extended curve fitting. The general curve fitting considers only the accuracy of the fitted curve; the smooth curve fitting can control both the accuracy and the fairness of the fitted curve, while the extended curve fitting can acquire a curve longer than the range of the measured points. For the constrained type, we propose three curve-fitting conditions: fixed end-points, closed curve and continuity to adjacent curves. Detailed discussion for each of the above cases is presented. Associated examples are also provided to illustrate the feasibility of the proposed algorithms.     

Ultrasonic vibration-assisted optical glass hot embossing process

A homemade apparatus was used to apply ultrasonic-vibration to assist the glass hot embossing processes. To operate at high temperatures for glass hot embossing, the ultrasonic vibration system was appropriately designed with an embedded cooling system, and an ultrasonic horn was specifically modified for high-temperature use. Molds with both V-groove and Fresnel structures were manufactured for hot embossing experiments on PSK-100 glass. The heights of the molded structures were increased significantly with the assistance of ultrasonic vibration. This technology demonstrates the capability to upgrade the performance of the glass hot embossing process.     

Application of neural networks to laser ultrasonic NDE of bonded structures

The purpose of this study is to develop artificial neural networks for the nondestructive evaluation of a bounded structure using laser generated surface waves. The radial basis model is employed and the inputs of the networks are the sampled dispersion curves while the output is the thickness of the bonding layer or unbond ratio. Numerical simulated dispersion curves with noises were used to train and test the neural networks. The dispersion curves of laser ultrasonic experiments acquired by spectral analysis method were also utilized to test the systems. For comparison, simplex inverse method was also introduced. The results demonstrate that neural networks are well suited for on-line evaluation of bonding thickness and unbond ratio of a bonded layered structure.     

Three-dimensional tracking and temporal analysis of liposomal transport in live cells using bright-field imaging

Gold nanoparticles (AuNPs) confined in liposomes of diameters around 200 nm produce strong scattering signal owing to surface plasmon resonance, and therefore bright-field optical tracking of the AuNP-encapsulating liposomes can be conducted in living cells. Using an optical profiling technique called noninterferometric wide-field optical profilometry and a bright-field tracking algorithm, the polynomial-fit Gaussian weight method, we analyze three-dimensional (3D) motion of such liposomes in living fibroblasts. The positioning accuracy in three dimensions is nearly 20 nm. We tag the liposome membranes with fibroblast growth factor-1 and reveal the intracellular transportation processes toward or away from the nucleus. On the basis of a temporal analysis of the intracellular 3D trajectories of AuNP-encapsulating liposomes, we identify directed and diffusive motions in the transportation processes.