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791.
基于协调决策的各种流量管理策略已被广泛应用于空域拥挤问题,但是如何整合这些流量管理策略重排拥挤的航班,实现空域资源公平有效地分配,一直是一个难题。流量管理部门对拥塞空域的主要管理目标是系统总延误成本最小,而航空公司则是以自身获利最大化为目标。航空公司可在协调决策过程中,隐藏必要的信息,以实现自身利益的最大化,但是这样会增加系统的总延误成本。为实现流量管理部门与航空公司的目标一致性,提高空域资源的分配效率,文中提出了基于拍卖的方法解决预战术和战术流量管理阶段的空域拥挤问题,并利用博弈理论对航空公司的决策进行了分析建模。通过一个仿真实验,验证了拍卖的分配结果能够降低拥挤空域的总延误成本。最后,根据实验数据分析了通过按拥挤航班数量比例重分配拍卖收入给航空公司方案,该方案能有效地降低航空公司的航班延误损失,提高空域资源分配的公平性和有效性。 相似文献
792.
Jagadish Singh Aishetu Umar 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
We have studied the positions and stability of the collinear equilibrium points, L1,2,3 of an infinitesimal body in the elliptic restricted three-body problem (ER3BP) when both primaries of the system are luminous and oblate spheroids moving in elliptic orbits around their common center of mass. We observe that their positions are affected by the radiation pressure forces, oblateness and the eccentricity of the orbits, but the stability character remains unchanged and are unstable. The effects of the parameters involved on the collinear points, in particular for the binary systems Achird, Luyten 726-8, Kruger 60, Alpha Centauri AB and Xi Bootis, and their stability in general have been investigated numerically using the analytical results obtained. 相似文献
793.
在飞机结构的设计定型阶段,要综合考虑载荷谱和结构特性的分散评估机群的可靠寿命。为此,进行了某型飞机结构细节的TA15M钛合金模拟试件在3个单机谱下的耐久性试验,断口判读得到主裂纹扩展(a,t)数据,反推得到了当量初始缺陷尺寸(EIFS)。对比分析表明,载荷谱分散对EIFS分布参数无影响,估计得到了通用EIFS分布参数。建立了考虑载荷谱分散的裂纹扩展对数正态随机变量模型及参数估计方法,由此确定裂纹超越概率并进行损伤度评估,建立了综合考虑载荷谱和结构特性分散的概率断裂力学方法(PFMA)。 相似文献
794.
模拟金属的局部腐蚀,采用元胞自动机方法(CA),提出模拟金属表面局部腐蚀的元胞自动机模型框架,将金属-溶剂体系离散成元胞网格,对金属腐蚀中涉及的转化、渗透、扩散等过程进行局部规则的定义。引入参数,λ和ε,建立腐蚀速率的参数化模型。在此基础上利用Matlab编程实现了对无防护层和有防护层金属表面局部腐蚀的复杂模拟。模拟结果表明:=1时,无防护层的金属表面发生普遍的均匀腐蚀,金属内部发生多种形式的局部腐蚀;而含防护层的金属表面腐蚀,在不同的参数λ和ε条件下,可得到不同的点腐蚀形貌。结果表明,CA方法可以实现对金属表面局部腐蚀的复杂模拟,而参数化模型的λ和ε则引起了腐蚀形貌的差异。 相似文献
795.
Chigomezyo M. Ngwira Lee-Anne McKinnell Pierre J. Cilliers 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Intense geomagnetic activity is known to give rise to large geomagnetically induced currents (GICs) in power transmission grids. Recordings of geomagnetic activity provide an efficient and economical way for power transmission system operators to assess GIC risks in retrospective studies. This study investigates local geomagnetic indicators (i.e., hourly peak value, hourly range indicator and hourly standard deviation) in order to determine their usefulness for understanding the drivers of GICs in the South African power network. Results show that the GICs have a higher correlation with the geomagnetic indicators derived from the East–West component of the horizontal geomagnetic field, than the indicators derived from the North–South component of the horizontal field. This directional dependence corresponds very well with the North–South orientation of the power lines feeding the power transformers at the South African Grassridge electrical substation GIC site. It therefore follows that, the geoelectric field driving the GICs at Grassridge is North–South oriented. Further, it is shown that the hourly range indicator has a higher correlation with the GICs than the hourly standard deviation for this particular network configuration. 相似文献
796.
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799.
800.
《中国航空学报》2023,36(4):299-314
A multi-objective optimization method was proposed for different dome reinforcement methods of a filament-wound solid rocket motor composite case based on a Radial Basis Function (RBF) model. Progressive damage of the composite case was considered in a simulation based on Hashin failure criteria, and simulation results were validated by hydraulic burst tests to precisely predict the failure mode, failure position, and burst pressure. An RBF surrogate model was established and evaluated by Relative Average Absolute Error (RAAE), Relative Maximum Absolute Error (RMAE), Root Mean Squared Error (RMSE), and R2 methods to improve the optimization efficient of dome reinforcement. In addition, the Non-dominated Sorting Genetic Algorithm (NSGA-II) was employed to establish multi-objective optimization models of variable-angle and variable-polar-radius dome reinforcements to investigate the coupling effect of the reinforcement angle, reinforcement layers, and reinforcement range on the case performance. Optimal reinforcement parameters were obtained and used to establish a progressive damage model of the composite case with dome reinforcement. In accordance with progressive damage analysis, the burst pressure and performance factor were obtained. Results illustrated that variable-angle dome reinforcement was the optimal reinforcement method compared with variable-polar-radius dome reinforcement as it could not only ensure the reinforcement angle’s continuous changing but also decrease the mass of composite materials. Compared with the unreinforced case, the reinforced case exhibited an increase in the burst pressure and performance factor of 36.1% and 23.5%, respectively. 相似文献