The Hydrogen Exospheric Density Profile Measured with ASPERA-3/NPD

We have evaluated the Lyman-α limb emission from the exospheric hydrogen of Mars measured by the neutral particle detector of the ASPERA-3 instrument on Mars Express in 2004 at low solar activity (solar activity index = 42, F_10.7=100). We derive estimates for the hydrogen exobase density, n _H = 10¹⁰ m^?3, and for the apparent temperature, T > 600 K. We conclude that the limb emission measurement is dominated by a hydrogen component that is considerably hotter than the bulk temperature at the exobase. The derived values for the exosphere density and temperature are compared with similar measurements done by the Mariner space probes in the 1969. The values found with Mars Express and Mariner data are brought in a broader context of exosphere models including the possibility of having two hydrogen components in the Martian exosphere. The present observation of the Martian hydrogen exosphere is the first one at high altitudes during low solar activity, and shows that for low solar activity exospheric densities are not higher than for high solar activity.     

Dynamics of Coronal Loop Oscillations Recent Improvements and Computational Aspects

We will discuss the observed, heavily damped transversal oscillations of coronal loops. These oscillations are often modeled as transversal kink oscillations in a cylinder. Several features are added to the classical cylindrical model. In our models we include loop curvature, longitudinal density stratification, and highly inhomogeneous radial density profiles. In this paper, we will first give an overview of recently obtained results, both analytically and numerically. After that, we shed a light on the computational aspects of the modeling process. In particular, we will focus on the parallellization of the numerical codes.     

Ground penetrating radar VIY-2

VIY-2 ground penetrating radar (GPR) with unique sounding possibilities and use simplicity is presented at this paper. VIY-2 GPR combines all units (synchronizer, transmitting and receiving modules, powering, and antenna system) into single case. The VIY-2 GPR communicates with computer via standard interface RS232 or USB1.0. Technical solutions utilized by the VIY-2 GPR reduce deployment time and simplify surveying process. The VIY-2 GPR design features and its components interaction are considered at this paper. Some field results are also presented here. The VIY-2 GPR design concept allows reducing the data acquisition time,, optimizing the time-varying gain control function, applying depth-stacking dependence, controlling the surveying window position and interference reducing by pulse repetition frequency randomizing.     

Track-before-detect procedures for early detection of moving target from airborne radars

In this paper we present a family of track-before-detect (TBD) procedures for early detection of moving targets from airborne radars. Upon a sectorization of the coverage area, the received echoes are jointly processed in the azimuth-range-Doppler domain and in the time domain through a Viterbi-like algorithm that exploits the physically admissible target transitions between successive illuminations, in order to collect all of the energy back-scattered during the time on target (TOT). A reduced-complexity implementation is derived assuming, at the design stage, that the target does not change resolution cell during the TOT in each scan. The constant false alarm rate (CFAR) constraint is also englobed in the proposed procedures as well as the possibility of working with quantized data. Simulation results show that the proposed algorithms have good detection and tracking capabilities even for high target velocities and low quantization rates.     

单晶铝纳米级硬度试验研究

使用纳米硬度计对单晶铝进行了纳米压痕试验，利用原子力显微镜对压痕形貌进行扫描并计算硬度值，重点观察和分析了纳米级条件下单晶铝的硬度性质，结果表明，当压痕深度小于2000nm时，单晶铝纳米硬度存在尺寸效应现象；从材料性质的角度分析了纳米硬度尺寸效应现象；探讨了纳米硬度和传统硬度本质上的区别，指出其根本原因在于不同尺度下人们对材料性质的关注点不同。     

Rocket berthing to an asteroid: Design problems

The results of research in a process of a probe rocket berthing to an asteroid are presented. Control laws were obtained as solutions of three problems, namely berthing considering transient processes in a rocket engine, fastest berthing with regard to fuel consumption and berthing in a scheduled time considering fuel consumption. A program trajectory obtained at solving of the first problem is suitable for mathematical modeling of berthing with the feedback control law and stabilization of angular motion. The solutions of the problems are reduced to simple formulas for controlling parameters calculation in the corresponding structures of control laws. The results can be applied in designing promising space vehicles intended for berthing to other space objects.     

Analysis of geometrically nonlinear shells of revolution based on the finite element method with the vector interpolation of desired quantities

In this paper, we present an algorithm for geometrically nonlinear finite element analysis of the shells of revolution. Use is made of the most proper algorithms for vector interpolation of displacements through the nodal unknowns and an efficient algorithm for obtaining the stress-strain increment relation at a step of loading. By comparing the results of analyzing a geometrically nonlinear shell of revolution obtained on the basis of the ANSYS software with the scalar interpolation of displacements with those obtained on the basis of an author-developed finite element, it has been shown that application of the FEM vector displacement interpolation leads to increasing the accuracy of the finite element solutions in analyzing the stress-strain state of the geometrically nonlinear shells.     

Isotopic Signatures of Presolar Materials in Interplanetary Dust

Interplanetary dust particles collected in the stratosphere frequently exhibit enrichments in deuterium (D) and ¹⁵N relative to terrestrial materials. These effects are most likely due to the preservation of presolar interstellar materials. While the elevated D/H ratios probably resulted from mass fractionation during chemical reactions at very low < 100 K temperatures, the origin of the N isotopic anomalies remains unresolved. The bulk of the N-bearing material may have obtained its isotopic signatures from low temperature chemistry, but a nucleosynthetic origin is also possible. This revised version was published online in August 2006 with corrections to the Cover Date.     

Type II Solar Radio Bursts: Theory and Space Weather Implications

Recent data and theory for type II solar radio bursts are reviewed, focusing on a recent analytic quantitative theory for interplanetary type II bursts. The theory addresses electron reflection and acceleration at the type II shock, formation of electron beams in the foreshock, and generation of Langmuir waves and the type II radiation there. The theory's predictions as functions of the shock and plasma parameters are summarized and discussed in terms of space weather events. The theory is consistent with available data, has explanations for radio-loud/quiet coronal mass ejections (CMEs) and why type IIs are bursty, and can account for empirical correlations between type IIs, CMEs, and interplanetary disturbances. This revised version was published online in August 2006 with corrections to the Cover Date.