Selected Problems in Collisionless-Shock Physics

The physics of collisionless shocks is a very broad topic, which has been well studied for many decades. However, there are a number of important issues which remain unresolved. Moreover, there have been new findings, which cast doubt on well-established ideas. The purpose of this review is to address a subset of unresolved problems in collisionless shock physics from a theoretical and/or numerical modeling point of view. The topics which are addressed are: the nonstationarity of the shock front, the heating and dynamics of electrons through the shock layer, particle diffusion in turbulent electric and magnetic fields, particle acceleration, and the interaction of pickup ions with collisionless shocks.     

一种预测驾驶员操纵行为的建模方法

在飞机设计中,应用驾驶员数学模型预测飞机飞行品质是避免人机系统出现不良耦合的重要途径之一.驾驶员神经网络模型是利用飞行模拟实验数据建立的驾驶员模型.基于该模型,针对纵向单通道俯仰跟踪任务,详细讨论了具有不同增益、不同短周期振荡频率飞机构型的驾驶员操纵行为变化规律.研究结果表明:对于特性相似的飞机构型,其驾驶员操纵特性也相似.因此,提出了一种利用相似构型的驾驶员操纵行为特性建立驾驶员预测模型的方法.通过对预测模型进行精度评价,可以证明采用本方法能够获得比较满意的驾驶员操纵行为特性预测结果.     

Fractal assessment of microaccelerations at weak damping of natural oscillation in spacecraft elastic elements. II

Making use of the Weierstrass-Mandelbrot fractal function, some problems connected with the adequate assessment of microaccelerations aboard a spacecraft are considered. The ranges of values for the function parameters that make it possible to simulate the quasi-static component of microaccelerations are also determined.     

基于数学模型和测量参数进行故障诊断的结构排除法

本文对结构排除法进行了简单的介绍，在简单的例子上对利用结构排除法进行故障诊断做了示范，对应用多个测量参数进行诊断提出了简单易行的方法，提出了诊断管路泄漏的方法，最后对结构排除法的优点以及在应用中需深入研究的方向进行了分析。     

Enhancing the ATIC charge resolution

The Advanced Thin Ionization Calorimeter (ATIC) experiment is designed to investigate the charge composition and energy spectra of primary cosmic rays over the energy range from about 10¹¹ to 10¹⁴ eV during Long Duration Balloon (LDB) flights from McMurdo, Antarctica. Currently, analysis from the ATIC-1 test flight and ATIC-2 science flight is underway and preparation for a second science flight is in progress. Charge identification of the incident cosmic ray is accomplished, primarily, by a pixilated Silicon Matrix detector located at the very top of the instrument. While it has been shown that the Silicon Matrix detector provides good charge identification even in the presence of electromagnetic shower backscatter from the calorimeter, the detector only measures the charge once. In this paper, we examine use of the top scintillator hodoscope detector to provide a second measure of the cosmic ray charge and, thus, improve the ATIC charge identification.     

CREAM: 70 days of flight from 2 launches in Antarctica

The Cosmic-Ray Energetics And Mass balloon-borne experiment has been launched twice in Antarctica, first in December 2004 and again in December 2005. It circumnavigated the South Pole three times during the first flight, which set a flight duration record of 42 days. A cumulative duration of 70 days within 13 months was achieved when the second flight completed 28 days during two circumnavigations of the Pole on 13 January 2006. Both the science instrument and support systems functioned extremely well, and a total 117 GB of data including 67 million science events were collected during these two flights. Preliminary analysis indicates that the data extend well above 100 TeV and follow reasonable power laws. The payload recovered from the first flight has been refurbished for the third flight in 2007, whereas the payload from the second flight is being refurbished to be ready for the fourth flight in 2008. Each flight will extend the reach of precise cosmic-ray composition measurements to energies not previously possible.     

A Quasi-Spherical Air Pressure Probe

This paper considers an air pressure probe, the head part of which is made in the form of a polyhedron inscribed into a sphere. Wind tunnel testing of the probe models is performed, a mathematical model and an algorithm are constructed to calculate all the altitude and airspeed parameters, and an error estimation is given.     

Study of Dynamic Loads of Aircraft Bevel Gear Systems

This paper studies the dynamic loads of bevel gears with circular and straight teeth with the overlap factors less than two (ε_α < 2) and more than two (ε_α > 2). The advantages of the gears with straight teeth with ε_α > 2 are shown.     

Application of a discrete-continuous model of strength analysis to solve the identification problem of a thermally loaded structure

This paper proposes to solve the problem of determining the strength properties of materials for thin-walled structural elements under mechanical and thermal loading as an optimization problem. A mathematical statement of the problem under certain assumptions is given.     

Fuel atomization and mixing in unsteady swirling flows behind the gas-dynamic stabilizer

Features of fuel atomization and propagation in the flow behind a gas-dynamic stabilizer are considered. Estimations of the influence of transverse jets impulse magnitude on characteristics of mixing behind the stabilizer are obtained by numerical and experimental methods.