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431.
本主要介绍了空调系统水管道绝热的一种新做法,并分析了这种做法的可行性与实用性,为空调水管道绝热施工提供了一条新的途径。 相似文献
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Optimal robust linearized impulsive rendezvous 总被引:3,自引:1,他引:2
The optimization of time-fixed linearized impulsive rendezvous with control uncertainty is investigated. One performance index related to the variances of the terminal state error is defined as the performance index of robustness which is calculated by linear covariance method. The two-objective optimization problem of minimizing the total characteristic velocity and the performance index of robustness is formulated based on the Clohessy–Wiltshire (C-W) system and solved by the nondominated sorting genetic algorithm. The Pareto-optimal solution sets of one homing rendezvous mission are provided and the Pareto optimality is verified by comparing with the fuel-optimal and the robustness-optimal solutions. It is shown that the proposed approach can quickly investigate the relation between the fuel cost and the trajectory robustness, besides evaluate different rendezvous maneuver schemes. 相似文献
435.
分析了造成矩形外罩产品底部不平和靠近底部处尺寸不一致的原因,并从工艺路线、工序零件结构和模具设计方面采取了有效的改进措施. 相似文献
436.
3技术状态更改控制技术状态是在技术文件中规定的、并在产品中达到的功能特性和物理特性。其中,功能特性指产品的性能指标、设计的约束条件和使用保障要求。物理特性指产品的形体特征,如尺寸、形状、公差和重量等。 相似文献
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针对冰箱侧板的生产,提出了步进冲切这一新的板料冲切方式。对原冰箱侧板生产线进行了大量改进,应用触摸屏整合操作界面。新的冲切工位大大减少了更换产品型号时生产线的准备时间,在实际生产中效果良好。 相似文献
439.
Zhen Yang Ya-Zhong Luo Jin Zhang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
A relative dynamics equation-set based on orbital element differences with J2 effects is derived, based on which a two-level approach is proposed to optimize the Mars orbital rendezvous phasing with a large difference in the initial ascending node. The up-level problem uses the revolution deviation between the target spacecraft and the chaser as the design variable, and employs a linear search to find the optimum. The low-level problem uses the maneuver revolutions, locations, and impulses as the design variables, and is solved using a hybrid genetic algorithm combined with sequential quadratic programming. To improve the solution accuracy, an iteration method is developed to satisfy the terminal constraints of the absolute numerical integration trajectory. Test cases involving Mars sample return missions with large initial node differences are presented, which show that the relative dynamics, two-level optimization model, and hybrid optimization algorithm are efficient and robust. Compared with previously published results, the total velocity increment has been further reduced by utilizing this proposed approach. It is found that a five-impulse plan requires the least quantity of propellant, and a propellant-optimal minimum rendezvous duration exists for this long-duration, large non-coplanar rendezvous problem. 相似文献
440.
For maritime radiation source target tracking in particular electronic counter measures(ECM)environment,there exists two main problems which can deteriorate the tracking performance of traditional approaches.The frst problem is the poor observability of the radiation source.The second one is the measurement uncertainty which includes the uncertainty of the target appearing/disappearing and the detection uncertainty(false and missed detections).A novel approach is proposed in this paper for tracking maritime radiation source in the presence of measurement uncertainty.To solve the poor observability of maritime radiation source target,using the radiation source motion restriction,the observer altitude information is incorporated into the bearings-only tracking(BOT)method to obtain the unique target localization.Then the two uncertainties in the ECM environment are modeled by the random fnite set(RFS)theory and the Bernoulli fltering method with the observer altitude is adopted to solve the tracking problem of maritime radiation source in such context.Simulation experiments verify the validity of the proposed approach for tracking maritime radiation source,and also demonstrate the superiority of the method compared with the traditional integrated probabilistic data association(IPDA)method.The tracking performance under different conditions,particularly those involving different duration of radiation source opening and switching-off,indicates that the method to solve our problem is robust and effective. 相似文献