基于小波倒谱模型的滤波处理技术及其在超声应力检测中的应用

在超声检测中,应力是通过超声时间延迟来测量的,而超声回波的时间延迟对噪声非常敏感。噪声严重影响应力的测量精度,噪声引起的时间延迟甚至与应力引起的时间延迟处于同一量级。而以往消噪处理都是基于盲信息,没有考虑系统响应特点,消噪效果不好,需一种有效的消噪方法。提出了一种基于倒谱模型新的滤波处理技术,从系统响应的角度,建立超声通道的小波倒谱模型,并通过对钢轨应力测试信号进行滤波处理,试验结果令人满意。     

小展弦比飞机非线性气动特性风洞与飞行相关性研究

在较大迎角范围，如何由风洞试验数据预计全尺寸小展弦比飞机的非线性气动特性，并与飞行值相关，始终是国际航空界致力解决的重大问题，本项研究采用风洞试验与工程计算相结合的方法，对支架，洞壁、进气，喷流，雷诺数及静弹性等影响相关性的诸因素予以修正，并计及配平影响，从而比较准确地预计出全尺寸收音机的非线性气动特性，预计值与试飞值相比较结果验证了本项研究的可靠性和实用性。     

Interaction of artificially injected plasma flows with ionospheric plasma

Results of rocket experiments on study of plasma flows (PF) artificially injected by sources separated from vehicles and their effect on medium parameters in ionosphere at altitudes 160:230 km are presented.PF were injected comprising lithium ions with velocities 1,2 x 10⁴ m/sec. and cesium-potassium ions with velocities (1,4–1,5)x10³ m/sec. Mass flow rate in case of lithium PS is 2 mg/sec, and in case of cesium-potassium PS is 0,2 g/sec. During experiments mass-spectrometer measurements of ion medium content in ranges of different ion masses were held, disturbancies of electric fields with frequencies up to 20 kHz and electron flows with energies 0,7keV, 4,6keV and over 40 keV were controlled at distancies from 150m to (500–600)m between plasma source and scientific equipment.     

基于GPS/IMU/太阳敏感器的空间飞行器组合姿态确定

GPS定姿是GPS在空间飞行器上应用的一个重要方向 ,本文在建立GPS 惯性组件 太阳敏感器组合定姿系统的非线性模型的基础上 ,采用扩展卡尔曼滤波实现了该组合定姿方案。通过理论分析和仿真结果均验证了方案的可行性。为GPS定姿在空间飞行器的实际应用提供一定的参考。     

Who is who in Algol-land ? - Part II -

In part I (De Greve and Packet) we have investigated the occurrence of reversed phases of mass-transfer during Case A evolution in close binaries. If the initial period of a system is shorter than 1–2 days (Early Case A) the reversed phase starts before core hydrogen exhaustion of the gainer (part I). This type of evolution is characterized by at least two phases of slow mass-transfer.We have computed the evolution of four Early Case A systems with initial masses of the loser equal to 3 Mo and 5 Mo. These four systems start mass-exchange when Xc of the primary has decreased to 0.525 (75% of its initial value). They all experience two phases of slow mass-transfer.We find that both phases have about the same duration for all systems. The mass ratios are clearly distinct, being closer to unity during the first phase. In the Hertzsprung-Russell, mass-radius and mass-luminosity diagrams both components remain close to the main-sequence band during slow mass-transfer. Evolution as an Algol is ended when both components overflow their outer critical surface after a second reversal of the mass-transfer.Observed Algol systems evolving in Early Case A are scarce. A search thruogh the catalogue by Giuricin et al. gives us the following candidates: X Tri, SX Aur and V Pup. Based on their mass ratios, SX Aur can tentatively be assigned to the first phase of slow mass transfer and X Tri to the second phase. For V Pup (which is more massive) this choice can not be made with certainty.     

航行情报服务(AIS)及其属性初探

本篇首次运用情报的广义属性从理论上分析和概括了航行情报的定义、宗旨和有关性质,并给出了航行情报服务的流程图和交流图。对促进和加强这一学科的教学研究有一定的参考意义。     

Forces acting on a foreign particle near a solidification front

The interaction of inert foreign particles and a solid-liquid interface during solidification is considered. The viscous drag on the particle which produces a force on the interface is calculated under general assumptions as well as the disjoining force for small particles and the buoyancy force for large ones.