Layer-oriented Element Integration Algorithm of Conformal Perfectly Matched Layer

As an efficient artificial truncating boundary condition, conformal perfectly matched layer (CPML) is a kind of multilayer anisotropic absorbing media. To reduce computing effort of CPML, this article proposes a layer-oriented element integration algorithm. In this algorithm, the relative dielectric constant and permeability are considered as constants for each the very thin monolayer of CPML, and the element integration of multilayer along the normal direction is substituted by the element integration of monolayer. The CPML is divided into multilayer elements, whose element matrixes are evaluated by monolayer integration. Numerical examples show that the layer-oriented element integration algorithm is reliable and the CPML formed with this algorithm possesses high-efficient absorbing performance.     

新一代战斗机全机地面强度试验技术

介绍了全机地面强度试验及验证要求，分析了试验的新问题和新挑战。通过试验顶层规划，采用全新设计模式、先进的加载技术，从试验的边界条件、综合平台、动力系统、测量与控制、损伤检测与监测等方面制定了总体技术方案。研究并应用了全硬式单侧双向加载技术、试验综合平台设计技术、试验边界条件模拟技术、动力系统设计技术等多项新技术，提高了设计效率、加快了试验实施速度、提升了试验安全性和可靠性。这些新技术在新一代战斗机多架次全机静力/疲劳试验中成功应用，结果表明各试验系统安全、可靠，达到了试验要求和预期试验目标，实现了全机地面强度试验技术的跨越式进步，技术成果为后续型号试验提供了较高参考价值。     

微型涡流发生器控制超临界翼型边界层分离实验研究

在低速风洞中研究了微型涡流发生器对超临界翼型边界层分离的控制。根据超临界翼型边界层分离特性，提出了涡流发生器的流动机理。研究了梯形涡流发生器不同高度和弦向位置对边界层分离控制效果的影响。研究表明，微型涡流发生器对超临界翼型边界层分离的控制主要起减阻作用；适宜采用微型涡流发生器对超临界翼型边界层分离进行控制，其最佳位置应在分离线前2～5日涡流发生器高度之间。     

无速度传感器永磁同步电机直接转矩控制系统

详细阐述了零矢量在永磁直接转矩控制系统中的作用，指出如果合理应用零矢量，不仅能使永磁电机(PMSM)的DTC系统正常运行，而且能减少转矩脉动的频率和改善系统的性能。还研究了PMSM的DTC系统的无速度传感器技术，构建了包含零矢量在内的无速度传感器PMSM的DTC系统，仿真和实验都证明了理论的正确性。在无速度传感器的条件下，PMSM的DTC系统实现了宽范围调速，调速比达到了1：100。     

沟槽面湍流边界层湍流度分布

应用激光测速(LDV)技术对沟槽面湍流边界层湍流度分布进行了精细的测量,实验结果表明,在湍流边界层区域沟槽面湍流度最大值比光滑面要小,但出现的位置比光滑面要远.此外,紧靠沟槽面,即y++<4内,沟槽面有较大的湍流度,说明沟槽面有使近壁区流动紊动增加的趋势.对于y/δ≥0.06的区域,湍流度可用u′\u=2.3 exp (-0.9y/δ)描述,而在y/δ<0.06内,则有u′/u =36.4y/δ.     

一种再入飞行器结构的热流载荷反演方法

提出了一种基于共轭梯度法的再入飞行器热流载荷反演方法.以一维结构为例验证反演方法的有效性,并分析了材料温变热物性参数和传感器测量误差对反演精度的影响;进而针对热防护结构和返回舱结构开展了热流载荷反演分析.结果表明:本文方法能有效地反演热防护结构和返回舱结构的热流载荷;考虑材料的温变热物性参数会使得反演过程存在非线性因素...     

Solar and magnetic control on night-time enhancement in TEC near the crest of the Equatorial Ionization Anomaly

The ionospheric Total Electron Content (TECs), derived by dual frequency signals from the Global Positioning System (GPS) recorded near the Indian equatorial anomaly region, Bhopal (23.2°N, 77.4°E, Geomagnetic 14.2°N) were analyzed for the period of January, 2005 to February, 2008. The work deals with monthly, diurnal, solar and magnetic activity variations on night-time enhancement in TEC. From a total of 157 night-time enhancements, 75 occur during pre-midnight and 82 post-midnight hours. The occurrence of night-time enhancement in TEC is utmost during summer months, followed by equinox and winter months. The occurrence of night-time enhancement in TEC decreases with increase in solar and magnetic activities. We observed that peak size and half amplitude duration are positively correlated, while time of occurrence of night-time enhancement in TEC and time of peak enhancement are negatively correlated with solar activity. The peak size, half amplitude duration, time of peak enhancement and time of occurrence of night-time enhancement in TEC shows negative correlation with magnetic activity. The results have been compared with the earlier ones and discussed in terms of possible source mechanism responsible for the enhancement at anomaly crest region.     

Study of magnetic flux emergence and related activity in active region NOAA 10314

We study the extremely complex active region (AR) NOAA 10314, that was observed from March 13–19, 2003. This AR was the source of several energetic events, among them two major (X class) flares, along a few days. We follow the evolution of this AR since the very first stages of its emergence. From the photospheric evolution of the magnetic polarities observed with SOHO/MDI we infer the morphology of the flux tube that originates the AR. Using a computation technique that combines Local Correlation Tracking with magnetic induction constrains, we compute the rate of magnetic helicity injection at the photosphere during the observed evolution. From our results we conclude that the AR originated by the emergence of a severely deformed magnetic flux tube having a dominantly positive magnetic helicity.     

Latent heat flux and air temperature anomalies along an active fault zone associated with recent Iran earthquakes

Pre-earthquake physical and chemical interactions in the earth’s ground may cause anomalies in latent heat flux, air and surface temperature. Earthquakes occur when the energy accumulated in rocks releases. Sometimes, the movements of the ground cause ruptures in the earth’s surface and sometimes the two sides of an existing fault shift towards each other. In a structurally complex and inhomogeneous collision region such as the Iranian Plateau, seismicity is not the result of activity of a single fault but is due to energy discharge in fault zones hundreds of kilometers wide.     

Monitoring the South Atlantic Anomaly using ATSR instrument series

The South Atlantic Anomaly (SAA) has been monitored for 19 years using the Along Track Scanning Radiometer (ATSR) series of instruments onboard the ERS-1, ERS-2 and ENVISAT ESA satellites. The time evolution of the night-time particle induced noise in the short wavelength infrared (SWIR, 1.6 μm) and visible (VIS, 0.55 μm) channels of the ATSR instrument series have been analysed. The monthly location and extension of the SAA are inferred by fitting a two-dimensional, elliptical Gaussian function to the coordinates of the night-time hot spots detected over the SAA region. The location of the centre of the SAA is found to drift westwards with an average drift rate of about 0.24 deg/year and northward with an average drift rate of about 0.12 deg/year. Irregularities are found where the drift speed is inverted and the SAA moves eastward and southward. Results indicate that, as expected, the retrieved values of SAA’s strength and extension are anti-correlated with the solar activity expressed by the solar flux at 10.7 cm (F10.7). Finally, the peak-to-peak amplitude of the seasonal variation of the SAA strength, estimated from monthly VIS data, is found to be 30% of the average value with the annual to semiannual amplitude ratio of 1.38.