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S. Guo X. LiuW. Ai Y. TangJ. Zhu X. WangM. Wei L. QinY. Yang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(5):736-741
Based on a formerly developed ground-based prototype of space plant-growing facility, the development of its improved prototype has been finished, so as to make its operating principle better adapt to the space microgravity environment. According to the developing experience of its first generation prototype and detailed demonstration and design of technique plan, its blueprint design and machining of related components, whole facility installment, debugging and trial operations were all done gradually. Its growing chamber contains a volume of about 0.5 m3 and a growing area of approximate 0.5 m2; the atmospheric environmental parameters in the growing chamber and water content in the growing media were controlled totally and effectively; lighting source is a combination of both red and blue light emitting diodes (LED). The following demonstrating results showed that the entire system design of the prototype is reasonable and its operating principle can nearly meet the requirements of space microgravity environment. Therefore, our plant-growing technique in space was advanced further, which laid an important foundation for next development of the space plant-growing facility and plant-cultivating experimental research in space microgravity condition. 相似文献
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对机场多跑道系统的障碍物限制面——内水平面的边界确定方法进行了系统研究。通过将N条(N≥3)复杂构形跑道简化为2N个点集,根据国际民航组织内水平面障碍物限制面形成原理并利用多边形凹凸性几何特征,给出了内水平面边界的确定方法和计算步骤。 相似文献
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Improved NSGA-II Multi-objective Genetic Algorithm Based on Hybridization-encouraged Mechanism 总被引:1,自引:0,他引:1
To improve performances of multi-objective optimization algorithms, such as convergence and diversity, a hybridization- encouraged mechanism is proposed and realized in elitist nondominated sorting genetic algorithm (NSGA-Ⅱ). This mechanism uses the normalized distance to evaluate the difference among genes in a population. Three possible modes of crossover operators--"Max Distance", "Min-Max Distance", and "Neighboring-Max"--are suggested and analyzed. The mode of "Neighboring-Max", which not only takes advantage of hybridization but also improves the distribution of the population near Pareto optimal front, is chosen and used in NSGA-Ⅱ on the basis of hybridization-encouraged mechanism (short for HEM-based NSGA-Ⅱ). To prove the HEM-based algorithm, several problems are studied by using standard NSGA-Ⅱ and the presented method. Different evaluation criteria are also used to judge these algorithms in terms of distribution of solutions, convergence, diversity, and quality of solutions. The numerical results indicate that the application of hybridization-encouraged mechanism could effectively improve the performances of genetic algorithm. Finally, as an example in engineering practices, the presented method is used to design a longitudinal flight control system, which demonstrates the obtainability of a reasonable and correct Pareto front. 相似文献