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排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
Compared to other fields of engineering, in mechanical engineering, the Discrete Element Method (DEM) is not yet a well known
method. Nevertheless, there is a variety of simulation problems where the method has obvious advantages due to its meshless
nature. For problems where several free bodies can collide and break after having been largely deformed, the DEM is the method
of choice. Neighborhood search and collision detection between bodies as well as the separation of large solids into smaller
particles are naturally incorporated in the method. The main DEM algorithm consists of a relatively simple loop that basically
contains the three substeps contact detection, force computation and integration. However, there exists a large variety of
different algorithms to choose the substeps to compose the optimal method for a given problem. In this contribution, we describe
the dynamics of particle systems together with appropriate numerical integration schemes and give an overview over different
types of particle interactions that can be composed to adapt the method to fit to a given simulation problem. Surface triangulations
are used to model complicated, non-convex bodies in contact with particle systems. The capabilities of the method are finally
demonstrated by means of application examples.
Commemorative Contribution. 相似文献
32.
岩体渗透率与应力关系是进行岩体渗流应力耦合分析的基础。基于龙滩水电站边坡岩体渗流压水试验结果和边坡岩体岩性及物理力学性质,对岩体渗透系数和地应力进行了分析计算,给出了边坡岩体渗透率随应力变化的关系式,为进行边坡岩体渗流一应力耦合分析提供了可靠数据。 相似文献
33.
对弹性杆与水下壳体接触冲击问题进行了研究,用有限元法模拟壳体,边界无法模拟无限域流体,通过温面上的耦合条件进行联立求解,文中给出了典型算例,并进行了有关讨论。 相似文献
34.
The crystallization of poly(phenylene sulfide) (PPS) in a polymer–magnetic Nd—Fe—B powder suspension was studied. Isothermal crystallization behavior was analyzed by way of differential scanning calorimetry, and the kinetics were described via the Avrami equation. The Avrami parameters and the crystallization times were strongly affected by both the particle size and the presence of a coupling agent coated on the filler particles. The small Nd—Fe—B particles exhibited long induction and half‐times, whereas the large particles tended to have short crystallization times. Particles ranging from 38 to 150 μ appeared to have similar crystallization times and to have no significant change in the value of Avrami index with melt crystallization temperature. As a result of these analyses, the dynamic mechanical properties were determined to correlate the fundamental polymer crystallization characteristics and the physical properties of the PPS binder. The enhancement of the wetting of the filler to the binder was promoted through the coupling agent, as confirmed by dynamic mechanical testing performed on the samples. The storage modulus typically decreased because of the presence of the uncoated small particles. Conversely, the loss modulus was enhanced because of the presence of the coated small particles in the PPS binder. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1091–1102, 2002 相似文献
35.
Michael E. G. Ferguson Peter L. Spedding 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):262-278
Experimental data for air–water two-phase co-current flow in two different pipe diameters were used to test the prediction of pressure drop by a number of existing theories and correlations. Several models are shown to be useful for prediction, particularly with the stratified regimes which have proved difficult to handle in the past. The model suggested by Olujic proved to be of particular value. 相似文献
36.
In this study a thermodynamic model for the phase behavior of aqueous salt+polymer solutions is developed. The model is based on the solution theory of Hill, which included scaling laws for the polymer molecular mass dependence and Pitzer–Debye–Hückel theory. This model was tested for systems composed of two different molecular mass of polyethylene glycols (PEG) and five different inorganic salts. All the model parameters were determined from independent measurements. The agreement between the experimental and predicted phase diagrams by this model is good. 相似文献
37.
38.
Jeong Ho Moon Hak Soo Han Yong Gun Shul Do Hoon Jang Muyng Do Ro Du Suk Yun 《Progress in Organic Coatings》2007
This study relates to the development of coatings for optical discs in high-density digital versatile disc systems (HD-DVD or blue lay disk) that use a high numerical aperture of 0.85 at 405 nm wavelength and have a protective top layer over a primer layer for protection against damage and dust. Ultraviolet-curable raw materials of two acrylic monofunctional monomers ( isobornylacrylate, IBA and tetrahydrofurfurylacrylate, THFA) and two kinds of urethaneacrylate oligomers (OUMD and OUME) have been easily mixed with photoinitiators. Curing rate of these materials was characterized by FT-IR. In case of top coats, VTES (vinyltriethoxysilane) and acrylic acid were added to enhance the abrasion resistance. These two kinds of UV-curable resinous materials having no solvent were synthesized and investigated as means for making a blue ray disk having good optical and mechanical properties. In addition, dynamic characteristics including reflectivity, fluctuation of RF signal and noise level were also investigated. 相似文献
39.
江汉平原印支期以来的盆山耦合关系及下古生界油气响应 总被引:5,自引:1,他引:4
利用构造地质学和油气系统理论,以盆地构造-沉积分析技术为手段,研究了印支期以来江汉平原与周缘造山带的耦合关系,探讨了江汉平原的构造演化及其对油气成藏的控制作用。印支期以来江汉平原及周缘经历了挤压、拉张、挤压3次大的构造应力场的转换,使古生代海相碳酸盐岩沉积为主的盆地具有改造盆地的特点;一方面强烈的抬升、剥蚀使早期聚集的油气经历改造和再分配、再聚集过程,另一方面燕山期构造活动使逆冲推覆构造成为该区重要勘探领域。综合分析表明,位于台、盆转换带的宜昌-珂理-簰州区带是目前江汉平原及周缘下古生界油气勘探的有利地区。 相似文献
40.
一种协调的科技文献分类方法 总被引:1,自引:0,他引:1
科技文献之间的相互引证关系反映了一种科学交流活动,显示了科学文献之间(甚至是学科之间)的内在联系,而通过追溯文献之间的这种关系,可以改善和提高传统的基于内容的科技文献的分类的方法。论文利用有相互引证关系,有同引关系,以及有耦合关系的两篇文献一般是属于同一类的这一特点,提出了文献之间的引用相似度,同引相似度,耦合相似度这三个概念,再利用这三个概念生成了文献之间的“结构相似度”,并将它用于K-NN分类法中得出一种基于结构的分类法。最后,论文将这种基于结构的分类法和基于内容的NaveBayes分类法结合起来提出了一种新的协调分类法。 相似文献