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排序方式: 共有3810条查询结果,搜索用时 31 毫秒
141.
The paper presents a technique of forming and evaluating the allowable clearance between a launch vehicle fairing and spacecraft.  相似文献   
142.
This paper deals with the technical features of designing an information-controlling system to prevent critical operating conditions of the helicopter flight, a technique for evaluating its effectiveness, analysis and synthesis of the measurement channels, forming of warning signals, and information support of the crew in abnormal situations.  相似文献   
143.
We determine the behavior of onboard gas-generator flowrate for generating the cavitation flow around a hybrid aerial underwater vehicle by using an annular wing on the underwater trajectory section.  相似文献   
144.
Junocam is a wide-angle camera designed to capture the unique polar perspective of Jupiter offered by Juno’s polar orbit. Junocam’s four-color images include the best spatial resolution ever acquired of Jupiter’s cloudtops. Junocam will look for convective clouds and lightning in thunderstorms and derive the heights of the clouds. Junocam will support Juno’s radiometer experiment by identifying any unusual atmospheric conditions such as hotspots. Junocam is on the spacecraft explicitly to reach out to the public and share the excitement of space exploration. The public is an essential part of our virtual team: amateur astronomers will supply ground-based images for use in planning, the public will weigh in on which images to acquire, and the amateur image processing community will help process the data.  相似文献   
145.
The paper discusses the applicability of cold gaseous nitrogen as a model working fluid in testing the hydrogen pump seals for power plants by three-dimensional modeling.  相似文献   
146.
This paper considers the axisymmetric transverse vibrations of aircraft nonuniform structural elements that are introduced by a thermal shock. Analytical solutions have been obtained and their numerical analysis has been performed.  相似文献   
147.
The work is devoted to observations of sharp growths of magnetospheric electron fluxes in the vicinity of the polar boundary of the outer radiation belt of the Earth according to the data of measurements on the Vernov and Lomonosov satellites. This precipitation was observed at the high-latitude boundary of the outer radiation belt toward the equator from the isotropization boundary, and can be caused by scattering waves of various physical natures, including electromagnetic and electrostatic waves.  相似文献   
148.
Airframe maintenance is traditionally performed at scheduled maintenance stops.The decision to repair a fuselage panel is based on a fixed crack size threshold,which allows to ensure the aircraft safety until the next scheduled maintenance stop.With progress in sensor technology and data processing techniques,structural health monitoring (SHM) systems are increasingly being considered in the aviation industry.SHM systems track the aircraft health state continuously,lead ing to the possibility of planning maintenance based on an actual state of aircraft rather than on a fixed schedule.This paper builds upon a model-based prognostics framework that the authors developed in their previous work,which couples the Extended Kalman filter (EKF) with a first order perturbation (FOP) method.By using the information given by this prognostics method,a novel cost driven predictive maintenance (CDPM) policy is proposed,which ensures the aircraft safety while minimizing the maintenance cost.The proposed policy is formally derived based on the trade-off between probabilities of occurrence of scheduled and unscheduled maintenance.A numerical case study simulating the maintenance process of an entire fleet of aircrafts is imple mented.Under the condition of assuring the same safety level,the CDPM is compared in terms of cost with two other maintenance policies:scheduled maintenance and threshold based SHM maintenance.The comparison results show CDPM could lead to significant cost savings.  相似文献   
149.
A high-accuracy numerical scheme is proposed for vortex methods of flow simulation around airfoils of arbitrary shape including airfoils with sharp edges, because it does not require the solution continuity on the airfoil.  相似文献   
150.
This paper considers issues of designing a gas-turbine engine in the helicopter system at the early design stages. The optimum and rational values of engine working process parameters at different flight speeds of the flight vehicle (FV) are analyzed. Several characteristics of mathematical models (MM) that form the helicopter–engine system, are described.  相似文献   
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