Papers by Keyword: Aspect Ratio

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Authors: Hong Mei Wang, Lin Lu, Xiao Long Liu, Feng Gao
Abstract: Three kinds of lead-free soldering tin powder particles produced by means of ultrasonic vibration atomization were studied in this paper. For tin powder particles had higher edge angle and more irregular shape which were the two most key elements that may influence the quality of soldering paste, aspect ratio and fractal dimension of those particles were treated as the facts that could reflect the morphology of soldering tin powder particles. Geometrical projected images of those particles were acquired by optical microscope and image computing were processed by morphologic method. Since particles adhesion phenomenon often occurred in actual image processing of soldering tin powder particles, Roberts operator was used for edge detection and in the meantime, Erosion method and Dilation method in morphological operation were applied to segment those adhesive particles. It was shown that the morphologic method proposed in this paper could be applied to segment those images of adhesive particles.
Authors: Zong Zhe Li, Zheng Hua Wang, Wei Cao, Lu Yao
Abstract: A robust aspect ratio based agglomeration algorithm to generate high quality coarse grids for unstructured grid is proposed in this paper. The algorithm focuses on multigrid techniques for the numerical solution of Euler equations, which conform to cell-centered finite volume scheme, combines isotropic vertex-based agglomeration to yield large increases in convergence rates. Aspect ratio is used as fusing weight to capture the degree of cell convexity and give an indication of cell quality, agglomerating isotropic cells sharing a common vertex. Consequently, we conduct agglomeration multigrid method to solve Euler equations on 2D isotropic unstructured grid, and compare the results with MGridGen
Authors: Takahiro Matsueda
Abstract: Aspect ratio is a key factor to calculate stress intensity factor (SIF) K using fracture mechanics. While cracks are approximated to be semi-circle or semi-ellipse for simply evaluation, their shapes are changed by stress concentration source. In this study, a new method to modify aspect ratio of a crack at a notch root is proposed. Modified aspect ratio in this method succeeded to decrease prediction error of fatigue crack initiation stress, σw1 which was calculated using experimental value.
Authors: Zi Zhen Wang, Ri He Wang, Yu Huan Bu, Xun Shan
Abstract: Crack universally existing underground is an important kind of pores. In order to study the elastic wave propagation in fractured medium through experiment, a new method to make artificial core with certain cracks using oil well cement and camphor sheet or thin steel sheet is put forward. Geometric parameters of the crack, such as shape, size and aspect ratio, are approximately equal to that of camphor sheet or thin steel sheet. Using the thin steel sheet to make crack can be more easy and accurate to control the crack angle than using camphor sheet. The crack opening scales at millimeters. The aspect ratio of cracks formed by camphor sheet ranges from 1.4 to 8, and aspect ratio of cracks formed by thin steel sheet ranges from 2.5 to 70. This method is proved simple and feasible by experiment practice, which can provide artificial cores with certain crack for acoustic wave propagation study.
Authors: Sheng Xian Wei, Feng Yan, Cui Qiong Yan, De Rong Zhao
Abstract: A calculation model to optimize aspect ratios of a large scale solar collector array installed on the limited horizontal roofs has been developed. The relations between the average daily solar radiation collection on the collector array and the aspect ratio have been studied. The results show that there is an optimum aspect ratio to maximize the solar energy collection on the collector arrays. The optimum aspect ratios of the collector array covering a floor area of 1000 m2, 500 m2, 200 m2 and 100 m2 for Beijing are 10/1, 5/1, 5/1 and 3/1, respectively. For the sake of convenient applications, the optimum aspect ratios of five types of collector arrays with different floor area used in 13 cities in China are given.
Authors: Hyun Kyu Lee, Jong Ho Kim, Jong Bong Kim
Abstract: A hinge bracket is usually produced by bending of a sheet panel or welding of a hollow bar into a sheet panel. The hinge bracket that is made by bending or welding, however, does not have sufficient durability due to the stress concentration on the bended region or low corrosion resistance of the welded region. In order to make hinge bracket with high durability, a bracket is needed to be produced by forming process. In this study, a thickening process of a sheet panel for the hinge bracket is investigated. The maximum thickening limit in one stage was determined for various aspect ratios of specimen. Finally, the optimum multi-stage forming process was designed for hinge bracket forming and the process was verified by numerical experiment.
Authors: Si Youl Jang, Hyun Sang Kong
Abstract: The measurement of ultra low aspect ratio fluid film thickness is very crucial technique both for the verification of lubrication media characteristics and for the clearance design in many precision components such as MEMS, precision bearings and other slideways. Many technologies are applied to the measurement of ultra low aspect ratio fluid film thickness (i.e. elastohydrodynamic lubrication film thickness). In particular, in-situ optical interferometric method has many advantages in making the actual contact behaviors realized with the experimental apparatus. This measurement method also does the monitoring of the surface defects and fractures happening during the contact behavior, which are delicately influenced by the surface conditions such as load, velocity, lubricant media as well as surface roughness. Careful selection of incident lights greatly enhances the fringe resolutions up to ~1.0 nanometer scale with digital image processing technology. In this work, it is found that coaxial aligning trichromatic incident light filtering system developed by the author can provide much finer resolution of ultra low aspect ratio fluid film thickness than monochromatic or dichromatic incident lights, because it has much more spectrums of color components to be discriminated according the variations of film thickness. For the measured interferometric images of ultra low aspect ratio fluid film thickness it is shown how the film thickness is finely digitalized and measured in nanometer scale with digital image processing technology and space layer method. The developed measurement system can make it possible to visualize the contact deformations and possible fractures of contacting surface under the repeated loading condition.
Authors: Quan Lai Li, Chuan Zhen Huang, Jun Wang, Hong Tao Zhu, Zeng Wen Liu
Abstract: Micro abrasive air jet machining technology is being increasingly used in the fields of micro cutting. Since the aspect ratio is a major interest characteristics of kerf in micro cutting, an experimental investigation is carried out to study the effect of cutting process parameters on the aspect ratio in this study. It is found that the aspect ratio increases with an increase in air pressure, abrasive flow rate and jet incidence angle, while decreases with an increase in nozzle traverse speed. Furthermore a predictive model for aspect ratio is developed using the dimensional analysis technique. It is shown that the model predictions are in good agreement with the experimental results. The research results may be meaningful to efficiently control the aspect ratio.
Authors: Bing Cheng Liu, Xiao Ming Liang, Hong Yu Guo
Abstract: Nowadays, ring die, which is a key component in ring mouleded roll forming machine, is applied more in domestic. But it has a higher machine maintenance costs and lower efficienc, and its life becomes shorter under the conditions of high temperature and pressure. By comparing the different simulation length-diameter ratio of the stress field cloud maps, which are anlyzed by ANSYS software, the best length-diameter ratio was gotten in this paper.
Authors: Duck Young Yoon, Keiichiro Tohgo, Kwang Hee Im, Young Tae Cho
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