Torsional Surface Waves in an Initially Stressed Anisotropic Porous Medium

It is well known that the homogeneous elastic half space does not allow the torsional surface wave to propagate. The present article attempts to study the possibility of propagation of such waves in a liquid-filled initially stressed poroelastic layer over nonhomogeneous half space. The study concludes that torsional surface waves may propagate in the poroelastic layer. The presence of fluid in pores and initial compressive stresses diminishes the velocity. The nonhomogeneity in rigidity and density of the half space also has a certain role to play in initiating, enhancing, or diminishing the velocity of torsional surface waves.     

Cyclic resistance of fly ash influenced by anisotropic stress condition,sand contents,and gravel content

A series of cyclic triaxial tests were performed to study the effect of anisotropic stress, sand content (in a fly ash-sand mixture), and addition of gravel on the cyclic resistance of fly ash. The results indicated that the failure mode of pure fly ash in the presence of isotropic stress was cyclic mobility and that the cyclic resistance of pure fly ash was significantly lower than that of clean Nakdong River sand for given test conditions. The cyclic resistance of pure fly ash decreased when the effective confining stress increased from 100 to 200 kPa, as expected. The failure of pure fly ash conducted in the absence of stress reversal was due to the initial axial strain accumulation and subsequent sudden runaway deformation, and this failure mode differed dramatically from that of fly ash conducted under symmetrical stress reversal. An increase in the anisotropic ratio resulted in a decrease in the cyclic resistance of pure fly ash. Nakdong River sand and gravels were added to pure fly ash and it was examined whether the cyclic resistance of fly ash increased. Addition of sand was observed to decrease the cyclic resistance for 10% and 20% sand content by volume, regardless of the amount of increase in the dry density of the samples. Furthermore, the cyclic resistance of fly ash-gravel mixtures was greater than that of pure fly ash by approximately 17%.     

基于区域划分的各向异性四边形网格重建方法

针对四边形网格模型中数量众多的四边形单元影响图像处理和曲面重构效率的问题,提出一种新的生成各向异性四边形网格算法,以去除冗余单元,减少单元数量。在已形成的四边形网格模型的基础上利用区域划分与多次各向异性法相结合的技术方法,实现了在同一网格模型不同区域设定不同的各向异性,合并数量不同的四边形单元,形成不同的网格密度。实例验证表明,算法在不降低网格模型相关指标的前提下,能够最大程度减少单元数量,对具有平坦区域的网格模型有更好的效果。     

Anisotropic corrosion of iron in pH 1 sulphuric acid

Anisotropic corrosion behaviour of a single grain of pure iron in 0.05 mol dm⁻³ sulphuric acid (pH 1) was investigated by a simple polarization technique. Both corrosion potential and corrosion current were found to be dependent on crystallographic orientation of the iron grain. A high corrosion current flowed on a grain showing a relatively noble corrosion potential, although both cathodic and anodic Tafel slopes were independent of the orientation. It was shown that cathodic hydrogen evolution reaction (HER) governed the corrosion reaction on the iron grain. Covalent bonding of Fe and H and coverage of H on Fe seem to play important roles in the HER and anisotropic corrosion behaviour of pure iron.     

A wedge crack in an anisotropic material under antiplane shear

A crack emanating from the apex of an infinite wedge in an anisotropic material under antiplane shear is investigated. An isotropic wedge crack subjected to concentrated forces is first solved by using the conformal mapping technique. The solution of an anisotropic wedge crack is obtained from that of the transformed isotropic wedge crack based on a linear transformation method. Expressions for the stress intensity factor for the anisotropic wedge crack with both concentrated and distributed loads are derived. The stress intensity factors are numerically calculated for generally orthotropic wedge cracks with various crack and wedge angles as well as anisotropic parameters.     

Mechanical Properties of Pear as a Function of Location and Orientation

Abstract

This study provides data on the fundamental mechanical properties of pear tissue and its relationship with specimen orientation and location. The compression tests were performed on Dangshan pear using the Instron Universal Testing Machine. The values of failure stress, failure strain, failure energy, and Young's modulus on the specimen orientation and location in pear were obtained. The four mechanical properties are significantly affected by specimen orientation, latitude, and depth, but not affected by the longitude of the specimen.     

Anisotropic transport properties of quantum dot arrays fabricated by the edge-defined nanowires

The anisotropic transport properties of quantum dot arrays fabricated by the nanoimprinted multilayer quantum wires have been investigated. The vertical transport characteristics are estimated by the carrier capture time from the electron reservoir to the low dimensional structures, which turned out to be longer than the spontaneous emission lifetime. The lateral transport characteristics are modeled after the quantum conductance between quantum dot arrays which are readily available from the miniband structures. The resulting lateral transport revealed that lateral quantum conductance can be minimized when the Fermi level is kept at the center of the miniband gap when the gap is larger than 4 kT.     

An adaptive normal estimation method for scanned point clouds with sharp features

Normal estimation is an essential task for scanned point clouds in various CAD/CAM applications. Many existing methods are unable to reliably estimate normals for points around sharp features since the neighborhood employed for the normal estimation would enclose points belonging to different surface patches across the sharp feature. To address this challenging issue, a robust normal estimation method is developed in order to effectively establish a proper neighborhood for each point in the scanned point cloud. In particular, for a point near sharp features, an anisotropic neighborhood is formed to only enclose neighboring points located on the same surface patch as the point. Neighboring points on the other surface patches are discarded. The developed method has been demonstrated to be robust towards noise and outliers in the scanned point cloud and capable of dealing with sparse point clouds. Some parameters are involved in the developed method. An automatic procedure is devised to adaptively evaluate the values of these parameters according to the varying local geometry. Numerous case studies using both synthetic and measured point cloud data have been carried out to compare the reliability and robustness of the proposed method against various existing methods.     

Microcontact printing of indium metal using salt solution “ink”

Poly(dimethlysiloxane) stamps were made from Si masters fabricated using photolithography and anisotropic etching. GaCl₃ and In(NO₃)₃ were microcontact printed onto Si substrates, creating arrays of micron size metal salt deposits. The In(NO₃)₃ deposits were further processed by annealing in an N₂ :H₂ (9:1) forming gas environment at 600 °C which converted the deposits into In metal. The ability to inexpensively pattern metal arrays on semiconductor surfaces has implications for ohmic contacts and, with additional processing, arrays of semiconductor crystallites for optoelectronic applications.     

Curing kinetics of anisotropic conductive adhesive film

Polymer-based conductive-adhesive materials have become widely used in many electronic packaging interconnect applications, such as chip-on-glass, chip-on-flex, etc. Among all the conductive-adhesive materials, anisotropic conductive adhesive film (ACF) is an attractive interconnect material because of its fine pitch capability. Anisotropic conductive-adhesive film is a thermosetting, epoxy matrix impregnated with a small amount of electrically conductive particles. During component assembly, the epoxy resin is cured to provide mechanical connection, and the conducting medium provides electrical connection in the z direction. The thermal cure process is critical to develop the ultimate electrical and mechanical properties of the ACF. In this paper, the curing reaction of ACF was studied with a differential scanning calorimeter (DSC) under isothermal conditions in the range of 120–180°C. An autocatalyzed kinetic model was used to describe the curing reaction. The rate constant and the reaction orders were determined and used to predict the progress of the curing reaction. A good agreement is found between the proposed kinetic model and the experimental reaction-rate data. The reaction-rate constants were correlated with the isothermal temperature by the Arrhenius equation. The glass-transition temperature also has been studied as a function of cure degree and moisture absorption.