排序方式: 共有275条查询结果,搜索用时 593 毫秒
231.
A mathematical model of the gliding unmanned aerial vehicle (UAV) motion is performed taking into account the interference effect of the main rotor on the UAV. Calculated values are presented for the interference addition to the aerodynamic coefficients of forces and moments on the UAV path section close to the carrier. The problems of stabilization and control are solved, providing stability of the UAV motion at the launch with due account of the aerodynamic interference and the effect of short-term upper stage engine operation, as well as a safe distance between the carrier and the UAV during their simultaneous motion. 相似文献
232.
H. E. Spence A. W. Case M. J. Golightly T. Heine B. A. Larsen J. B. Blake P. Caranza W. R. Crain J. George M. Lalic A. Lin M. D. Looper J. E. Mazur D. Salvaggio J. C. Kasper T. J. Stubbs M. Doucette P. Ford R. Foster R. Goeke D. Gordon B. Klatt J. O’Connor M. Smith T. Onsager C. Zeitlin L. W. Townsend Y. Charara 《Space Science Reviews》2010,150(1-4):243-284
233.
Corinne Lippe Simone D’Amico 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(11):3426-3443
This paper presents a novel methodology to control spacecraft swarms about single asteroids. This approach enables the use of small, autonomous swarm spacecraft in conjunction with a mothership, reducing the need for the Deep Space Network and improving performance in future asteroid missions. The methodology is informed by a semi-analytical model for the spacecraft relative motion that includes relevant gravitational effects without assuming J2-dominance as well as solar radiation pressure. The dynamics model is exploited in an Extended Kalman Filter (EKF) to produce an osculating-to-mean relative orbital element (ROE) conversion that relies on minimum knowledge of the asteroid gravity. The resulting real-time relative mean state estimate is utilized in a new formation-keeping control algorithm. The control problem is cast in mean relative orbital elements to leverage the geometric insight of secular and long-period effects in the definition of control windows for swarm maintenance. Analytical constraints that ensure collision avoidance and enforce swarm geometry are derived and enforced in ROE space. The proposed swarm-keeping algorithms are tested and validated in high-fidelity simulations for a reference asteroid mission. 相似文献
234.
F. M. Flasar V. G. Kunde M. M. Abbas R. K. Achterberg P. Ade A. Barucci B. B’ezard G. L. Bjoraker J. C. Brasunas S. Calcutt R. Carlson C. J. C’esarsky B. J. Conrath A. Coradini R. Courtin A. Coustenis S. Edberg S. Edgington C. Ferrari T. Fouchet D. Gautier P. J. Gierasch K. Grossman P. Irwin D. E. Jennings E. Lellouch A. A. Mamoutkine A. Marten J. P. Meyer C. A. Nixon G. S. Orton T. C. Owen J. C. Pearl R. Prang’e F. Raulin P. L. Read P. N. Romani R. E. Samuelson M. E. Segura M. R. SHOWALTER A. A. Simon-Miller M. D. Smith J. R. Spencer L. J. Spilker F. W. Taylor 《Space Science Reviews》2004,115(1-4):169-297
The Composite Infrared Spectrometer (CIRS) is a remote-sensing Fourier Transform Spectrometer (FTS) on the Cassini orbiter that measures thermal radiation over two decades in wavenumber, from 10 to 1400 cm− 1 (1 mm to 7μ m), with a spectral resolution that can be set from 0.5 to 15.5 cm− 1. The far infrared portion of the spectrum (10–600 cm− 1) is measured with a polarizing interferometer having thermopile detectors with a common 4-mrad field of view (FOV). The middle infrared portion is measured with a traditional Michelson interferometer having two focal planes (600–1100 cm− 1, 1100–1400 cm− 1). Each focal plane is composed of a 1× 10 array of HgCdTe detectors, each detector having a 0.3-mrad FOV. CIRS observations will provide three-dimensional maps of temperature, gas composition, and aerosols/condensates of the atmospheres of Titan and Saturn with good vertical and horizontal resolution, from deep in their tropospheres to high in their mesospheres. CIRS’s ability to observe atmospheres in the limb-viewing mode (in addition to nadir) offers the opportunity to provide accurate and highly resolved vertical profiles of these atmospheric variables. The ability to observe with high-spectral resolution should facilitate the identification of new constituents. CIRS will also map the thermal and compositional properties of the surfaces of Saturn’s icy satellites. It will similarly map Saturn’s rings, characterizing their dynamical and spatial structure and constraining theories of their formation and evolution. The combination of broad spectral range, programmable spectral resolution, the small detector fields of view, and an orbiting spacecraft platform will allow CIRS to observe the Saturnian system in the thermal infrared at a level of detail not previously achieved.This revised version was published online in July 2005 with a corrected cover date. 相似文献
235.
针对辐射前后环栅与条栅结构部分耗尽绝缘体上硅(SOI,Silicon On Insulator)器件关态电流的变化展开实验,研究结果表明辐射诱使关态电流增加主要取决于侧壁泄漏电流、背栅寄生晶体管导通、带-带隧穿与背栅泄漏电流的耦合效应.在条栅结构器件中,辐射诱生场氧化层固定电荷将使得器件侧壁泄漏电流增加,器件前、背栅关态电流随总剂量变化明显;在环栅结构器件中,辐射诱使背栅晶体管开启将使得前栅器件关态电流变大,而带-带隧穿与背栅泄漏电流的耦合效应将使得器件关态电流随前栅电压减小而迅速增加.基于以上结果,可通过改良版图结构以提高SOI器件的抗总剂量电离辐射能力. 相似文献
236.
针对使用传统卡尔曼滤波器对非线性系统进行故障诊断,估计精度低的问题,提出了一种新的故障诊断方法.该方法结合多模型自适应估计和简化中央差分卡尔曼滤波器的优点,能在线快速地检测出故障,利用中央差分代替了雅可比矩阵的求解,使系统状态估计准确收敛到真实值附近,而且避免了反复求解量测预测方差等一系列繁杂过程.在执行机构不同故障的情况下,通过与其他算法进行诊断对比,结果表明提出的算法在精度上和运行速度上具有明显的优势. 相似文献
237.
A. V. Gimbitskii R. N. Gil’fanov S. G. Dezider’ev A. G. Karimova 《Russian Aeronautics (Iz VUZ)》2015,58(4):426-430
This work is devoted to the experimental study of the method of thermal protection of the environment by shielding from the hot body of the high-temperature gas turbine engine on a model setup under conditions of free convection (bulk screen), and with the injection of air through a porous screen. The generalized dependences of thermal protection are obtained that permit the temperature of the screen and the casing under free convection and injection of air through a porous screen to be predicted. 相似文献
238.
A combined method for calculating the trajectories of suspended particles in the hydrodynamic velocity fields is proposed. The method utilizes capabilities of existing CFD codes and parallel computing on a computer with a graphics card that supports CUDA technology. The software package that implements the method is described. 相似文献
239.
V. A. Kuz’min E. I. Maratkanova I. A. Zagrai R. V. Rukavishnikova 《Russian Aeronautics (Iz VUZ)》2016,59(1):100-106
The paper presents technology and results of the computational experiment on investigation of thermal radiation in the combustion chamber of a model rocket engine. Dependence of optical properties, radiation characteristics and emission characteristics on the main determining factors and parameters is analyzed. 相似文献
240.
In this paper, attention was focused on the matter of simulating a flow, the mixture and vapor formation in the GTE combustion chamber without regard for combustion. The software developed by the authors was used for simulation. For comparison and analysis, also presented are the simulation results obtained in Fluent software. The characteristic features of a flow and the distribution of vaporous and droplet-liquid fuel throughout the flame tube model volume are revealed. 相似文献