排序方式: 共有86条查询结果,搜索用时 15 毫秒
51.
52.
53.
略论军用装备的基本可靠性和任务可靠性 总被引:1,自引:0,他引:1
详细论述了军用装备的基本可靠性和任务可靠性的基本概念、主要区别以及两者间的相互关系,并探讨了军用装备的基本可靠性和任务可靠性在工程论证中的有关问题。分析认为,对军用装备来说,基本可靠性和任务可靠性是完全不同的两个概念,对宇宙飞船、飞机、导弹一类的飞行器尤其如此。 相似文献
54.
55.
《中国航空学报》2020,33(12):3318-3330
In order to obtain the optimized aircraft design concept which meets the increasingly complex operation environment at the conceptual design stage, System-of-systems (SoS) engineering must be considered. This paper proposes a novel optimization method for the design of aircraft Mission Success Space (MSS) based on Gaussian fitting and Genetic Algorithm (GA) in the SoS area. First, the concepts in the design and evaluation of MSS are summarized to introduce the Contribution to System-of-Systems (CSS) by using a conventional effectiveness index, Mission Success Rate (MSR). Then, the mathematic modelling of Gaussian fitting technique is noted as the basis of the optimization work. After that, the proposed optimal MSS design is illustrated by the multi-objective optimization process where GA acts as the search tool to find the best solution (via Pareto front). In the case study, a simulation system of penetration mission was built. The simulation results are collected and then processed by two MSS design schemes (contour and neural network) giving the initial variable space to GA optimization. Based on that, the proposed optimization method is implemented under both schemes whose optimal solutions are compared to obtain the final best design in the case study. 相似文献
56.
Space science missions are increasingly challenged today: in ambition, by increasingly sophisticated hypotheses tested; in development, by the increasing complexity of advanced technologies; in budgeting, by the decline of flagship-class mission opportunities; in management, by expectations for breakthrough science despite a risk-averse programmatic climate; and in planning, by increasing competition for scarce resources. How are the space-science missions of tomorrow being formulated? The paper describes the JPL Innovation Foundry, created in 2011, to respond to this evolving context. The Foundry integrates methods, tools, and experts that span the mission concept lifecycle. Grounded in JPL's heritage of missions, flight instruments, mission proposals, and concept innovation, the Foundry seeks to provide continuity of support and cost-effective, on-call access to the right domain experts at the right time, as science definition teams and Principal Investigators mature mission ideas from “cocktail napkin” to PDR. The Foundry blends JPL capabilities in proposal development and concurrent engineering, including Team X, with new approaches for open-ended concept exploration in earlier, cost-constrained phases, and with ongoing research and technology projects. It applies complexity and cost models, project-formulation lessons learned, and strategy analyses appropriate to each level of concept maturity. The Foundry is organizationally integrated with JPL formulation program offices; staffed by JPL's line organizations for engineering, science, and costing; and overseen by senior Laboratory leaders to assure experienced coordination and review. Incubation of each concept is tailored depending on its maturity and proposal history, and its highest-leverage modeling and analysis needs. 相似文献
57.
Understanding of the space debris environment and accuracy of its observation-validated models are essential for optimal design and safe operation of satellite systems. Existing ground-based optical telescopes and radars are not capable of observing debris smaller than several millimeters in size. A new experimental and instrumental approach – the space-based Local Orbital Debris Environment (LODE) detector – aims at in situ measuring of debris with sizes from 0.2–10 mm near the satellite orbit. The LODE concept relies on a passive optical photon-counting time-tagging imaging system detecting solar photons (in the visible spectral range) reflected by debris crossing the sensor field of view. In contrast, prior feasibility studies of space-based optical sensors considered frame detectors in the focal plane. The article describes the new experimental concept, discusses top-level system parameters and design tradeoffs, outlines an approach to identifying and extracting rare debris detection events from the background, and presents an example of performance characteristics of a LODE sensor with a 6-cm diameter aperture. The article concludes with a discussion of possible sensor applications on satellites. 相似文献
58.
Dynamics and operation optimization of partial space elevator with multiple climbers 总被引:1,自引:0,他引:1
Gefei Shi Gangqiang Li Zhanxia Zhu Zheng H. Zhu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(10):3213-3222
This work studies the dynamics and optimal stabilization method of a partial space elevator (PSE) system with multiple climbers. All satellites and climbers are assumed as lumped masses that are connected by straight, massless, and inextensible tethers. A general dynamic model is derived for the PSE with multiple climbers. It is found different climber moving patterns of climbers have major influence of dynamic behavior of PSE. Optimal control is used to develop optimal operation modes to suppress the libration of PSE with multiple climbers. Moreover, a new operation mode is proposed to approach the desired mission objectives. It is found that all libration angles can be suppressed to zero by the end of the transfer period if two climbers can be kept at a constant speed. At the same time, the magnitudes of libration angles can be kept bounded by regulating the speed of the middle climber relative to other two climbers. 相似文献
59.
A. Nathues H. Boehnhardt A.W. Harris C. Jentsch S. Schaeff F. Weischede A. Wiegand N. Schmitz W. Goetz Z. Kachri 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
ASTEX (ASTeroid EXplorer) is a concept study of an in situ exploration mission to two Near-Earth-Asteroids (NEAs), which consists of an orbiting element and two individual lander units. The target candidates have different mineralogical compositions, i.e. one asteroid is chosen to be of “primitive’’ nature, the other to be a fragment of a differentiated asteroid. The main scientific goals of the ASTEX mission are the exploration of the physical, geological, and mineralogical nature of the NEAs. The higher level goal is the provision of information and constraints on the formation and evolution of our planetary system. The study identified realistic mission scenarios, defined the strawman payload as well as the requirements and options for the spacecraft bus including the propulsion system, the landers, the launcher, and assessed and defined the requirements for the mission’s operational ground segment. 相似文献
60.