Flutter analysis of an airfoil with bounded random parameters in incompressible flow via Gegenbauer polynomial approximation

The effects of parameter uncertainty on the flutter characteristics of a two-dimensional airfoil in an incompressible flow were investigated through Gegenbauer polynomial approximation. The uncertain parameters, such as the linear and cubic pitch stiffness coefficients are modeled as bounded random variables with λ-PDFs (probability density functions). With the aid of Gegenbauer polynomial approximation, the two-dimensional stochastic airfoil system is transformed at first into its equivalent deterministic one. Then the Hopf-bifurcation point is determined through the equivalent deterministic system, and the onset of the flutter, together with the flutter frequency against the probability density distribution parameter and the intensity of the random variable is explored. In addition, the ranges of the peak pitch and plunge responses against the flight speed and the PDFs of the peak pitch response are obtained. Numerical results show how the probability density distribution parameters and the intensities of random parameters affect the flutter onset speed, flutter angular frequency, the upper and lower boundaries of peak responses, and the PDFs of peak responses.     

Next generation test support systems for the aircraft life cycle

The objective of this paper is to present the experience of EADS in using a common test support system for integration and qualification testing, aircraft ground equipment (AGE), in-service software maintenance facilities (ISMF) and ground crew training. EADS uses its test support system AIDASS (Advanced Integrated Data Acquisition and Stimulation System) in different phases of the aircraft life cycle. AIDASS is comprised of a real-time front-end system and a standard PC for the user interface. The EADS test support system is used in almost all phases of the aircraft life cycle, for instance, for integration and verification testing, as aircraft ground equipment, for in-service software maintenance and training of ground crews. This test support system is used for the software maintenance in the TORNADO program at different airforces in Europe. The airforces also share test setups with industry     

MEMS Electronically Steerable Antennas for Fire Control Radars

Large apertures are of great benefit to applications that are prime powered limited as is found on aerostat and other airborne platforms. Electronically scanned array antennas are often proposed for these applications. However, increasing the aperture area with conventional array technology is met with prohibitive cost, weight, and prime power increases because of the dense spacing of phase shifters and/or active T/R modules. This discusses the recent development of RF MEMS (Microelectromechanical System) switch technology and the use of these switches in a Radanttrade lens configuration for arrays of approximately 10 m² at X-band. A proof-of-concept 0.4 m² MEMS Electronically Steerable Antenna (ESA) containing 25,000 MEMS switches has been successfully designed, fabricated, and tested. The 0.4 m² MEMS ESA was then integrated with an AN/APG-67 radar system to form the MEMS Demonstration Radar System. The MEMS Demonstration Radar System successfully detected both airborne and ground moving targets during a series of extensive radar demonstrations. This is believed to be the first large scale employment of MEMS switches in a scanning antenna and radar system. The low-cost, lightweight, and low power technology demonstrated can enable weight and power constrained platforms with electronic steering.     

Investigation of promising ceramic materials in discharge chambers of stationary plasma thrusters

The characteristics of the insulator wear process in the discharge chamber of a stationary plasma thruster (SPT) are analyzed. The results of studying the erosion resistance to ionic spraying of different ceramic compositions are presented. It is shown experimentally that the integral characteristics (the value of thrust and thrust efficiency) as well as the SPT lifetime can be improved in changing from the conventional hot-pressed boron silicate (BN + SiO₂) ceramics to the BN + Si₃N₄ ceramic compositions.     

NIST微波散射参数和功率测量

介绍了NIST开展的微波散射参数(S参数)及功率测量业务。包括在这两项业务中的各自的测量内容,系统的校准技术,对系统及所用的标准件的描述和对于不同测量所考虑的测量不确定度。此外还介绍了在S参数测量及功率测量的未来工作方向。     

Unmanned aircraft navigation for shipboard landing using infrared vision

This paper addresses the problem of determining the relative position and orientation of an unmanned air vehicle with respect to a ship using three visible points of known separation. The, images of the points are obtained from an onboard infrared camera. The paper develops a numerical solution to this problem. Both simulation and flight test results are presented.     

Voting fusion adaptation for landmine detection

This paper presents a voting fusion application for use with a remotely controlled multisensor vehicle platform for antitank landmine detection. Data from three landmine detection sensors mounted at the front of the vehicle enhance the probability of detection and, when combined via data fusion, limit the false alarm density to practical levels. The performance of the voting fusion scheme presented in this paper is contrasted with a heuristic data fusion approach developed by General Dynamics Canada.     

Planetary protection considerations for MarsNet and Mars sample return missions.

The ESA MarsNet mission proposal consists most probably of a trio of Mars landers. These landers each contain a variety of scientific equipment. The network of stations demands for a definition of its planetary protection requirements. With respect to the MarsNet mission only forward contamination problems will be considered. Future involvement of European efforts in planetary exploration including sample returns will also raise the problem of back contamination. A tradeoff study for the overall scientific benefit with respect to the approximative cost is necessary. Planetary protection guide-lines will be proposed by an interdisciplinary and international board of experts working in the fields of both biology and planetary science. These guide-lines will have to be flexible in order to be modified with respect to new research results, e.g. on adaptation of microorganisms to extreme (space) conditions. Experiments on the survival of microorganisms at conditions of simulated Mars surface and subsurface will have to be conducted in order to obtain a baseline data collection as a reference standard for future guide-lines.     

The J-MASS Marketplace: a new way for DoD to do business

It is current DoD policy to use commercial off-the-shelf software whenever it meets DoD requirements. The application of this policy to modeling and simulation has resulted in the concept of “The Joint Modeling and Simulation System (J-MASS) Marketplace.” J-MASS is designed as an Open Systems Architecture with the capability for the Simulation Support Environment (SSE) to be expanded by the addition of site specific software. In the “J-MASS Marketplace” industry will build commercial tools to work with J-MASS and individual organizations will license what they need for their particular site. The J-MASS SSE is a framework or backplane into which everything else plugs. A J-MASS product release would have the core capabilities, but the unique needs of various organizations would be satisfied by industry. This paper addresses how the J-MASS Marketplace could work and how compliance can be defined. It will outline opportunities for industry in both building software for the Marketplace and in defining the Marketplace concept     

Features of active sidestick controllers

This paper discusses the advantages of incorporating active sidesticks into a modern aircraft cockpit. Active sidestick controllers for manual pilot inputs in pitch and roll are examined for commercial transport aircraft. Options and requirements for sidesticks are reviewed. The recommendation of an active sidestick controller is developed providing both cross-cockpit coupling and autopilot backdrive capability. These characteristics provide pilot cues identical to traditional cable-linked column/yoke configurations