First-ply failure prediction of an unsymmetrical laminated ellipsoidal woven GFRP composite shell with incorporated surface-bounded sensors and internally pressurized

First-ply failure of an unsymmetrical laminated ellipsoidal woven Glass Fiber Reinforced Polymer (GFRP) composite shell internally pressurized was investigated analytically using the linear interpolation technique. The shell's boundary was fixed at its end. Tsai-Wu failure criterion was used as the composite failure design factor. The analytical results, including critical internal pressure and strains in global directions, were validated with the experimental results for some arbitrarily selected points on the shell surface along meridian axis. Manufacturing of laminated ellipsoidal composite shells was performed by using the Vacuum Infusion Process (VIP), a novel method commonly adopted for the fabrication of laminated composite shells. Surface-bounded sensors were installed on the shells' surface to measure the strain values after the internal pressure was applied. According to the analytical investigation findings, the failure factor was critical at the innermost ply. In addition, for each ply, the shell's edge was observed to be the region with the highest failure factor. The experimental findings confirmed that the failure occurred in the regions close to the shell's edge, as predicated by the analytical approach. The results from both approaches were in a close agreement. Subsequently, the effect of various parameters including thickness, aspect ratio, and stacking sequence on the first-ply failure of laminated ellipsoidal woven GFRP composite shell were investigated and the critical mechanical factors to avoid failure were determined.     

不同物性对椭球形颗粒在移动床中流动特性影响的模拟研究

采用多元颗粒模型对椭球形颗粒在移动床内的流动进行了离散单元法直接数值模拟。椭球形颗粒由3个叠加在一起的球元构成,建立了椭球形颗粒的碰撞机制,详细分析了其运动过程中的受力情况,主要是碰撞力和重力,并通过实验验证了模型的正确性。探讨不同物性颗粒在移动床内的流动特性,分析颗粒物性对流型、空隙率分布以及颗粒分离情况的影响。结果表明,滑动摩擦系数越小,颗粒流动越接近整体流,滑动摩擦系数越大,颗粒流动越接近漏斗流,且滑动摩擦系数越大,空隙率的波动范围越大,滑动摩擦系数越小,空隙率分布越均匀。滚动摩擦系数和弹性恢复系数对流型和空隙率的影响都很小。在二元混合物中,颗粒直径比越大,空隙率越小。不同尺寸颗粒混合物会导致颗粒分离,在下料时,颗粒直径比越大,细颗粒含量越少,但在物料卸出90%以后,细颗粒含量反而变大。滑动摩擦系数增大,在下料初始和最终阶段,细颗粒含量变大,而在下料中间阶段,细颗粒含量变少。     

Generating homogeneous magnetostatic field inside prolate and oblate ellipsoidal coil

Magnetostatic field distribution inside and outside of prolate and oblate ellipsoidal coil is analytically determined. The results are used to obtain the coil winding function for getting homogeneous magnetostatic field inside the prolate and oblate ellipsoidal coil when uniform current flows through it.     

共晶和过共晶铝硅合金活塞尺寸稳定性的研究

研究了两种共晶和两种过共晶铝硅合金活塞在２００℃的长期时效过程中的尺寸稳定性。研究发现，随着时效时间的延长，所有活塞顶部的直径都呈现不可逆长大；过共晶铝合金活塞的尺寸稳定性高于共晶铝合金活塞；共晶铝硅合金活塞顶部直径有两次突然长大，而过共晶铝合金活塞仅有一次。作者初步解释了上述现象     

椭圆封头偏交椭圆管的展开

运用数学分析及投影理论的方法,建立了椭圆封头偏交椭圆管的数学模型,推导了椭圆封头偏交椭圆管的展开方程,据此设计了椭圆接管展开图的通用程序。最后,给出了应用实例,证明该方法简单、直接,易于理解与操作,便于工程实际应用。     

Data mining derived from food analyses using non-invasive/non-destructive analytical techniques; determination of food authenticity,quality & safety in tandem with computer science disciplines

BackgroundFood quality, safety and authenticity are important issues for consumers, governments, as well as the food industry. In the last decade, several researchers have attempted to go beyond traditional microbiological, DNA-based and other methods using rapid techniques. This broad term involves a variety of sensors such as hyperspectral and multispectral imaging, vibrational spectroscopy, as well as biomimetic receptors.Scope and approachThe resulting data acquired from the above-mentioned sensors require the application of various case-specific data analysis methods for the purpose of simple understanding and visualization of the acquired high-dimensional dataset, but also for classification and prediction purposes.Key findings and conclusionsIt is evident that rapid techniques coupled with data analysis methods have given promising results in several food products with various sensors. Additionally there are several applications, new sensors and new algorithms that remain to be explored and validated in the future.     

2205双相钢复合板厚壁封头成形技术探讨

某高压气液分离器壳体选用2205＋16MnR双相钢复合钢板,椭圆封头厚度为（4＋80）mm。在封头压制成形过程中,需要保证封头基层的力学性能和2205复层的耐腐蚀性,难度较大。经过反复试制,有效解决了双相钢复合板厚壁封头成形的技术难题,为今后双相钢复合板厚壁封头的压制成形提供了经验。     

An Experimental Method for Three-Dimensional Dynamic Contact Angle Analysis

Abstract

Droplet dynamics analysis concerns the measurements of droplet volume, cap and base areas and contact angles, as they change in time to study evaporation, wettability, adhesion and other surface phenomena and properties. In a typical procedure, the two-dimensional measurements are based on a series of images recorded at successive stages of the experiment from a single view. Only a few basic dimensions of sessile droplets are commonly measured from such images, while many other quantities of interest are derived utilizing geometrical relationships. The reliability of these calculations is limited by the necessary assumption that the droplet shape can be approximated as a spherical cap. In reality, the sessile droplet shapes are influenced by gravity, liquid surface tension, local surface anisotropy and microstructure, which often produce non-spherical cap shapes.

This paper describes an experimental methodology for determination of key parameters, such as volume and contact angle for dynamic sessile droplets that can be approximated either by spherical or ellipsoidal cap geometries. In this method, images collected simultaneously from three cameras positioned orthogonally to each other are used to record the dynamic behavior of non-spherical droplets. Droplet shape is approximated as an ellipsoid of arbitrary orientation with respect to the cameras, which allows determination of volume and contact angle along the base perimeter. A major advantage of this method is that the dynamic parameters of droplets on anisotropic surfaces can be determined even when the orientation of the axes changes throughout the droplet lifetime. The method is illustrated with experimental results for a spherical and an ellipsoidal droplet.     

Interpreting Reservoir Permeabilities from Wireline Formation Test Data

In order to provide accurate permeabilities of reservoirs for productivity estimate in offshore oil fields, in this study a semianalytical model of unsteady ellipsoidal flow and a numerical simulation algorithm have been developed to interpret wireline formation test data. The model is derived from basic principles of fluid mechanics in porous medium, and the time variation of test flows and anisotropy of formations are both taken into account. The approaches had been applied successfully to interpreting the test data of a new pumpout wireline formation tester, and the results show the validity of the new method presented.