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Adaptive smooth length based on weighted average of neighboring particle density for SPH fluid simulation

DOI:10.3724/SP.J.2096-5796.20.00048

接受日期:2020-09-14

摘要 (6) | PDF (3)

Background In SPH fluid simulation method, the smooth length not only affects the process of neighbor search, but also affects the calculation accuracy of pressure solver. Therefore, it plays an important role in ensuring the accuracy and stability of SPH. Methods In this paper, an adaptive SPH fluid simulation method with variable smooth length is designed, in which the size of smooth length is adaptively adjusted by the ratio of particle density to the weighted average of the density of its neighboring particles. In addition, a neighbor search scheme and kernel function scheme are designed to solve the asymmetry problems caused by variable smooth length. Results Compared with some classical methods, the simulation efficiency of the proposed algorithm is competitive, and the variance of the number of neighbor particles is effectively reduced. As a result, the visual effect is closer to the physical reality. Conclusions In this paper, the precision of interpolation calculation in SPH algorithm is improved by using the adaptive smooth length scheme, so that the stability of the algorithm is enhanced and larger time step is possible.

Virtual 3D environment for exploring the spatial ability of students

DOI:10.3724/SP.J.2096-5796.20.00037

接受日期:2020-08-31

摘要 (61) | PDF (14)

Background Spatial ability is a unique type of intelligence, which is distinguishable from other forms of intelligence, which plays an essential role in success in many academic fields, especially in this technology era. Instruction assisted with 3D technology can display stereo graphics, and promote students’ understanding of the geometry structure and characteristics of graphics. Spatial ability includes several aspects of abilities. There are few software training different aspects of spatial ability for senior high school students. To explore the effective methods of training spatial ability for senior high school students. Methods First, this article proposed an inquiry design strategy to improve spatial ability. Then according to the strategy, unity3D was used to develop a 3D inquiry environment that can use leap motion to complete gesture interaction. Finally, researchers carried out experience activities and issued user experience questionnaires to participants to verify the application effect of the spatial ability inquiry environment, and used interviews to understand the user experience of participants exploring the leap motion device in the 3D inquiry environment. Conclusions The spatial ability inquiry environment can help learners to understand concepts better. The user shows a strong willingness to continue using. It also updates the teaching concept to a certain extent and emphasizes the student's dominant position.

Survey on lightweighting methods of huge 3D models for online Web3D visualization

DOI:10.3724/SP.J.2096-5796.20.00006

接受日期:2020-02-13

摘要 (78) | PDF (17)

Background With the rapid development of Web3D technologies, online Web3D visualization , especially for complex models or scenes, has been a great yet heavy demand. As the serious conflict between Web3D system load and the resource consumption in processing these huge models, the huge 3D model lightweighting methods for online Web3D visualization are reviewed in this paper. Methods Observing the geometry redundance introduced by man-made operations in modeling procedure, several categories of lightweighting related work which aim for reducing the data amount and resource consumption for Web3D visualization are elaborated. Results With comparing perspectives, the characteristics of each method are summarized and within the reviewed methods, the geometric redundance removal which achieves the lightweight goal by detecting and removing the repeated components is an appropriate way for current online Web3D visualization. Meanwhile, the learning algorithm, though not practical at present, is our expected topic. Conclusions Various aspects should be considered in an efficient lightweight method for online Web3D visualization, including characteristics of original data, combination or extended of the existed methods, and even scheduling strategy, cache management, rendering mechanism. Meanwhile, innovation methods, especially the learning algorithm is worth exploring.