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81.
M. Alghane Y. Q. Fu B. X. Chen Y. Li M. P. Y. Desmulliez A. J. Walton 《Microfluidics and nanofluidics》2012,13(6):919-927
This paper reports an experimental and numerical investigation on the scaling effects in the flow hydrodynamics for confined microdroplets induced by a surface acoustic wave (SAW). The characteristic parameters of the flow hydrodynamics were studied as a function of the separation height, H, between the LiNbO3 substrate and a top glass plate, for various droplets volumes and radio-frequency powers. The ratio of the gap height to attenuation length of the SAW, H/l SAW, is shown to be an important parameter affecting the streaming flow induced in this confined regime. The reported numerical and experimental results are in good agreement over the range examined in this study and demonstrate that, at a lower gap heights of H?≤?100?μm, a significant decrease in streaming velocity or Reynolds number is induced, with the velocity approaching zero when the gap height is decreased to ~50?μm. An increase in the gap height results in an increased streaming velocity; however, if the gap height exceeds 70?% of the SAW attenuation length, any further increase in the gap height induces a drop in the streaming velocity. 相似文献
82.
An important direction of metamodeling research focuses on developing methods which can iteratively improve the accuracy of
the metamodel. The intention of these kinds of strategies is to use a space reduction strategy to lead response surface refinement
to a smaller design space; and new sample points are commonly generated near the optimum. The potential risk is that some
characteristics of given problems might be lost, especially for nonlinear problems. Therefore, a novel metamodel-assisted
optimization called “Min–Median–Max” (M3) is proposed. This algorithm classifies sample points into three categories (maximum,
median and minimum) based on corresponding objective function values, new sample points should be generated by considering
combination of three kinds of samples. In order to avoid local convergence and control size of sample points, particle swarm
optimization (PSO) algorithm and radial basis function (RBF) metamodeling technique are integrated to implement the suggested
M3 strategy. To validate the performance of the M3 strategy, multiple mathematical test functions are used for evaluating
the accuracy and efficiency. As a practical engineering application, drawbead design of a stamping system is optimized. The
results demonstrate applicability and effectiveness of the M3 algorithm. 相似文献
83.
将磁流变技术应用于火炮反后坐装置是目前正在发展的一种降低火炮后坐力的新技术,优化火炮反后坐装置控制,达到实时调节阻力。针对某型号火炮,在建立动力学模型和电磁模型的基础上设计了磁流变反后坐系统。为实现理想的后坐控制规律,提出了PID和模糊控制算法。利用ADAMS和MATLAB进行联合仿真,仿真结果表明,在后坐行程范围内,最大后坐阻力分别为3.71×105N,3.53×105N,相比传统火炮减小了13%和17%,并且模糊控制的后坐阻力曲线具有良好的"平台效应",实现了控制目标,表明磁流变阻尼器良好的可控性和应用于火炮后坐系统中的可行性。 相似文献
84.
In this paper a hybrid finite element method is applied in evaluation of the stress intensity factors K
I
and K
II
of unidirectional fiber reinforced composites. In order to satisfy the stress singularity at the crack tip a singular super-element based on a modified complementary energy principle is developed. The stress and displacement fields in the super-element are expressed in terms of polynomials of two complex variables 1 and 2 in the transformed -plane. The stiffness matrix of the super-element was determined by using a line integral along the boundary of the super-element. The displacement vector was expressed in terms of the element nodal displacement vector {q} and a properly selected shape function defined along the element boundary.Numerical results for K
I
and K
II
of glass-epoxy and graphite-epoxy unidirectional composites with cracks along the diameter of a circular cut out as well as elliptical cut outs were evaluated
Résumé On applique, dans la présente étude, une méthode d'éléments finis hybrides à l'évaluation des facteurs d'intensité de contrainte KI et KII pour des composites renforcés de fibres unidirectionnelles. Pour tenir compte de la singularité de la contrainte à l'extrémité de la fissure, on développe un super élément singulier en se basant sur un principe modifié d'énergie complémentaire. Les champs de contraintes et de déplacements dans le super-élément sont exprimés sous forme polynormale de deux variables complexes 1, et 2 dans le plan de la transformée. La matrice de rigidité du super élément est, quant à elle, définie en utilisant une intégrale linéaire le long du contour de l'élément. Le vecteur de déplacement est exprimé par un vecteur (9) de déplacement nodal de l'élément, et par une fonction de forme appropriée, définie le long du contour de l'élément.On évalue les résultats numériques pour KI et KII, correspondant à des composites à fibres unidirection-nelles de types verre-epoxy et graphite-epoxy, oú des fissures se situeraient sur le diamètre de découpes circulaires et elliptiques相似文献
85.
Silicon - This work investigates the influence of silicon based coupling agents on visco-elastic properties of natural filler dispersed epoxy resin composites. Also this work attempts to explore... 相似文献
86.
Chai Linjiang Xia Jiying Murty Korukonda L. Gu Xinfu Fan Jiangkun Yao Zhongwen 《Metallurgical and Materials Transactions A》2022,53(8):3179-3193
Metallurgical and Materials Transactions A - A hot-rolled Ti–6Al–4V sheet was annealed at 960 °C (sub β-transus temperature) and then subjected to different coolings [in water... 相似文献
87.
Chikh A. Serier M. Al-Sabur R. Siddiquee A. N. Gangil N. 《Russian Journal of Non-Ferrous Metals》2022,63(6):690-700
Russian Journal of Non-Ferrous Metals - Adequate heat input provided by the proper combination of friction stir welding (FSW) parameters is critical to sound welding. Optimum parameter setting... 相似文献
88.
89.
90.
Sodium-ion battery (SIB) is an ideal device that could replace lithium-ion battery (LIB) in grid-scale energy storage system for power because of the low cost and rich reserve of raw material. The key challenge lies in developing electrode materials enabling reversible Na+ insertion/desertion and fast reaction kinetics. Herein, a core-shell structure, FeS2 nanoparticles encapsulated in biphase TiO2 shell (FeS2@TiO2), is developed towards the improvement of sodium storage. The diphase TiO2 coating supplies abundant anatase/rutile interface and oxygen vacancies which will enhance the charge transfer, and avoid severe volume variation of FeS2 caused by the Na+ insertion. The FeS2 core will deliver high theoretical capacity through its conversion reaction mechanism. Consequently, the FeS2@TiO2 nanorods display notable performance as anode for SIBs including long-term cycling performance (637.8 mA·h·g-1 at 0.2 A·g-1 after 300 cycles, 374.9 mA·h·g-1 at 5.0 A·g-1 after 600 cycles) and outstanding rate capability (222.2 mA·h·g-1 at 10 A·g-1). Furthermore, the synthesized FeS2@TiO2 demonstrates significant pseudocapacitive behavior which accounts for 90.7% of the Na+ storage, and efficiently boosts the rate capability. This work provides a new pathway to fabricate anode material with an optimized structure and crystal phase for SIBs. 相似文献