2004年3月13日TC-1和Cluster卫星联合观测的磁通量传输事件

分析了2004年3月13日12:15到12:25UT期间TC-1和Cluster卫星簇的磁通门磁力计(FGM)和电子/电流试验仪(PEACE)的联合观测数据.在此期间,TC-1卫星位于日下点以南的磁层顶附近的磁鞘中,并在12:19UT左右观测到了一个典型的先正后负的磁鞘磁通量传输事件(FTE);而Cluster卫星簇位于北半球日侧高纬磁层项附近,并于12:23UT左右穿出磁层顶进入磁鞘,且在12:21 UT左右也观测到了一个典型的先正后负的磁层FTE.比较分析发现此两个FTE具有类似的磁场结构和等离子体特征,可能是同一个北向运动的FTE先后被TC-1和Cluster卫星观测到.利用Cluster 4颗卫星的多点同时观测数据,采用最小方向微分法和时空微分方法,推断Cluster卫星观测的这个FTE是尺度大小约为1.21Re的准二维结构,其运动方向为东北方向,与Cooling模型预测方向基本一致.利用Cooling模型的预测,推算了TC-1卫星在12:19UT观测的FTE的运动速度和尺度,进而得出随着通量管的极向运动,其速度和尺度均有所增加.     

Viscous fluid flow in an elastic pipeline

Basic equations of hydrodynamics in an elastic pipeline that are found using the vectorial notation of Newton’s law for a viscous fluid are presented. An analog of Poiseuille’s formula for the fluid flowrate in the elastic pipeline and the results of the comparative analysis of a viscous flow in elastic and rigid pipelines are given. It is shown that the ratio of the maximal fluid velocity in the pipeline cross section and the section-average velocity is similar for elastic and rigid pipelines.     

Algorithmic support of a small-sized navigation system on the basis of the magnetoinertial course transmitter

The algorithmic support of a small-sized navigation system on the basis of the magnetoinertial course transmitter is considered; the support makes it possible to significantly reduce accumulating errors that are due to incomplete data on wind parameters and decrease requirements for random errors of initial data sensors.     

A set of systems for labor standards computer-aided design

A set of systems for labor standard computer-aided design is described, namely, initial developments, advance and state-of-the art.     

Dynamic qualification of the HIRENASD elastic wing model

The High Reynolds Number Aero-Structural Dynamics (HIRENASD) project is conducted by the Collaborative Research Center “Flow Modulation and Fluid-Structure Interaction at Airplane Wings (SFB 401)” at RWTH Aachen University. It is funded by the Deutsche Forschungsgemeinschaft (German Research Foundation, DFG) since 2004. Steady and unsteady state experiments with an elastic semispan wing model were performed under transonic and high Reynolds number conditions in the European Transonic Windtunnel (ETW) in Cologne, Germany. The main components of the complete windtunnel assembly were the wing model itself, a piezoelectric 6-components balance and a mechanical excitation mechanism able to excite the wing model at selected resonance frequencies. These components were designed, sized and assembled at the Department of Aerospace and Lightweight Structures at RWTH Aachen University. The dynamic qualification of the windtunnel assembly under wind-off condition was carried out in the department's test laboratory. Modal survey testing based on the hammer impact method was performed, as well as response decomposition analysis using enforced excitation by means of the mechanical excitation mechanism itself. Within the qualification, a test procedure enabling investigations of modal parameter changes under wind-off and wind-on conditions in a cryogenic windtunnel was also verified.     

Solar sail trajectories with piecewise-constant steering laws

Solar sails have much attracted the interest of the scientific community as an advanced low-thrust propulsion means capable of promoting the reduction of mission costs and the feasibility of missions that are not practically accessible via conventional propulsion because of their large ΔV requirements. To reduce the overall flight time, a given mission is usually analyzed in the framework of a minimum time control problem, with the employment of a continuous steering law. The aim of this paper is to investigate the performance achievable with a piecewise-constant steering law whose aim is to substantially reduce the complex task of reorienting the sail over the whole mission. Unlike previous studies based on direct approaches, here we use an indirect method to optimally select the sail angle within a set of prescribed values. The corresponding steering law translates the results available for continuous controls to the discrete case, and is able of producing trajectories that are competitive in performance with the optimum variable direction program.     

Active aeroelastic control over a four control surface wing model

This paper describes the procedure implemented to design, develop and test an aeroelastic control system installed on a forward swept wing of the aeroelastic demonstrator X-DIA. A control method directly based on Nissim aerodynamic energy concept has been chosen. Two different modeling techniques have been adopted for the calculation of generalized aerodynamic forces, such as doublet lattice method and computational fluid dynamics and the obtained results are finally compared. The latter approach, applied to better estimate the control surfaces effectiveness, requires the capability to correctly model the control surface rotation and the grid deformation, usually addressed as non-trivial problems in CFD based aeroelastic analysis. A genetic algorithm optimization technique has been adopted to state and refine all the control gains.     

Experimental studies of the impulsive ultrasonic machining by a tool with an intermediate striker

Some experimental data on the process of impulsive ultrasonic machining are presented. Also given are the data on variations in the impulsive vibration frequency of a workpiece and a tool.     

Systems integration, user interface design, and tower air trafficcontrol

Tower air traffic control is currently performed using several unintegrated systems. While each of these systems supports performing an isolated task, the compilation of tools presents a number of challenges. This paper reports ways in which the Tower Control Computer Complex (TCCC) will support and enhance user management of numerous systems. Areas that will be notably improved include the consistency in the user interface of the air traffic control toolset, the task of manually integrating tools and information, toolset alert management, and toolset organization and administration     

Trapped antiprotons produced by cosmic rays in the Earth's magnetosphere.

The existence of significant fluxes of antiparticles in the Earth magnetosphere has been predicted on theoretical considerations in this article. These antiparticles (positrons or antiprotons) at several hundred kilometers of altitudes, we believe are not of direct extraterrestrial origin, but are the natural products of nuclear reactions of the high energy primary cosmic rays (CR) and trapped protons (TP) confined in the terrestrial radiation belt, with the constituents of terrestrial atmosphere. Extraterrestrial positrons and antiprotons born in nuclear reactions of the same CR particles passing through only 5-7 g/cm2 of interstellar matter, exhibit lower fluxes compared to the antiprotons born at hundreds of g/cm2 in the atmosphere, which when confined in the magnetic field of the Earth (in any other planet), get accumulated. We present the results of the computations of the antiproton fluxes at 10 MeV to several GeV energies due to CR particle interactions with the matter in the interstellar space, and also with the residual atmosphere at altitudes of approximately 1000 km over the Earth's surface. The estimates show that the magnetospheric antiproton fluxes are greater by two orders of magnitude compared to the extraterrestrial fluxes measured at energies <1-2 GeV.