Background: Searching the drug molecules from the medicinal plants become more and more popular given that herbal components have been widely considered to be safe. In medical virtual plant studies, development rules are difficult to be extracted, the construction of plant organs is highly dependent on equipment and the process is complicated. Aim: To establish three-dimensional structural virtual plant growth model. Methods: The quasi-binary tree structure and its properties were obtained through the research of theory on binary tree, then the relationship between quasi-binary tree structure and plant three-dimensional branching structure model was analyzed, and the three-dimensional morphology of plants was described. Results: A three-dimensional plant branch structure pattern extracting algorithm based on quasi-binary tree structure. By using 3-D L-system method, the extracted rules were systematized, and standardized. Further more, we built a comprehensive L-model system. With the aid of graphics and PlantVR, we implemented the plant shape and 3-D structure's reconstruction. Conclusion: Three-dimensional structure virtual plant growth model based on time-controlled L-system has been successfully established.
This paper is concerned with a discrete predator-prey model with Holling II functional response and delays. Applying Gaines and Mawhin’s continuation theorem of coincidence degree theory and the method of Lyapunov function, we obtain some sufficient conditions for the existence global asymptotic stability of positive periodic solutions of the model.
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