颗粒增强金属基原位复合材料的制备技术回顾与展望

综述了国内外制备颗粒增强金属基复合材料的各种原位合成方法、工艺原理 ,并基于原位合成技术实现产业化的关键是优化工艺、降低成本的分析 ,对各种工艺的特点进行了探讨 ,在此基础上介绍了一种原位合成新工艺──反应稀释法。     

风洞流场扰动和转捩区流场的相关性分析

本文通过实验研究了风洞实验区流场的扰动与边界层转捩区内的速度脉动及其强度、谱特性和两者之间的相关性,提出了实验区流场的扰动对转捩区流场起作用的条件和规律(即转捩对外界扰动响应的条件),这项工作是研究修正风洞背景流场噪声和湍流度对转捩雷诺数影响的基础。     

航天器虚拟动态试验技术研究及展望

文章简要回顾了航天器结构动态设计技术的发展,并且指出随着现代航天器越来越复杂,数值分析方法与动态试验方法都无法满足设计的要求。为了解决这个问题,必须采用虚拟动态试验技术。文中较详细地介绍了复杂结构模型修改新技术、虚拟模态试验技术和振动台虚拟振动试验技术。文章最后还对该领域未来研究方向进行了展望。     

靶场时统中自适应Loran-C接收机的研究

针对运载火箭的时间同步问题,提出了一种基于ESPRIT算法估计Loran-C接收机天波延迟的信号处理新技术,为设计具有自适应调节最佳采样点的Loran-C接收机打下良好的基础。利用频谱相除技术构建了延迟时间测量的信号模型,研究了频谱相除后信号的幅频特性。针对通带外噪声被放大的现象,提出频域加窗的措施。最后,提出用ESPRIT算法估计了天波延迟,避免了诸如AR、ARMA、MUSIC等算法在整个时域计算参数的弊端,更适合于适时应用。仿真结果表明,频域加窗影响识别天波的分辨率,ESPRIT算法能够正确估计天波的延迟,而且比FFT具有更高的分辨率。     

Positron nonextensivity contributions on the rational solitonic,periodic, dissipative structures for MKP equation described critical plasmas

New closed forms have been exposed that rational, trigonometric, periodical, explosive, hyperbolic and shock solutions can be usable in the ionosphere plasma of earth. To explore the nonextensive impacts on the features of nonlinear waves in this plasma model, using Riccati-Bernoulli sub-ODE process, the MKP equation has been solved. This method is very important in the study of dynamics and motion in fluids. Some of the obtained new potential solutions are prefect achievements in plasma observations and applications in ionosphere.     

复合材料整体化结合界面失效模拟方法研究

复合材料结构界面失效分析有助于复合材料整体化结构细节设计,有必要进行界面失效问题分析.针对复合材料整体化结合界面进行有限元数值模拟失效分析方法研究,对承受不同载荷的结合界面选用不同的建模方法和失效模型.对于层压板失效,在Tsai-Hill判据基础上,增加破坏能判据;对于界面失效,提出基于应力、应变和破坏能的多级判据及其衰减方法.结果表明：本文方法建模简单、计算速度较快、计算结果与试验值吻合性好,可为复合材料整体化结构设计提供工程实用的分析方法.     

Ti1023主桨毂中央件的微动疲劳及其防护

微动疲劳普遍存在于航空结构中,是研究的热点之一。结合某型机Ti1023主桨毂中央件抗微动疲劳的工程实践,介绍了微动疲劳机理、影响因素和防护技术,为缺口敏感型Ti1023材料在其他动部件推广应用提供有益借鉴。     

A new narrow beam Doppler radar at 3 MHz for studies of the high-latitude middle atmosphere

A Doppler radar at 3.17 MHz has been installed at Saura close to the Andøya Rocket Range as part of the ALOMAR observatory at Andenes, Norway in summer 2002 to improve the ground based capabilities for measurements of small scale features and turbulence in the mesosphere. The main feature of the new Saura MF radar is the transmitting/receiving antenna which is arranged as a Mills Cross of 29 crossed half-wave dipoles with a minimum beam width of about 7°. Each dipole is fed by its own transceiver, and the individual phase control of the 58 transceiver modules on transmission and reception provides high flexibility in beam forming and pointing as well as transmission switching between ordinary and extraordinary mode circular polarisation. In addition, beams with different widths at the same pointing angle can be formed. For multiple receiver applications (spaced antenna wind measurements, all-sky meteor detections) four independent receiving channels are available.     

CAE技术在工程设计中的应用

本文介绍了602所应用CAE技术的现状,并介绍了应用有限元法进行结构分析的经验,和应用先进的CAE技术的体会,指出了工程应用中的不足,展望了CAE技术的应用前景。     

Operational modal analysis via image based technique of very flexible space structures

Vibrations represent one of the most important topics of the engineering design relevant to flexible structures. The importance of this problem increases when a very flexible system is considered, and this is often the case of space structures. In order to identify the modal characteristics, in terms of natural frequencies and relevant modal parameters, ground tests are performed. However, these parameters could vary due to the operative conditions of the system. In order to continuously monitor the modal characteristics during the satellite lifetime, an operational modal analysis is mandatory. This kind of analysis is usually performed by using classical accelerometers or strain gauges and by properly analyzing the acquired output. In this paper a different approach for the vibrations data acquisition will be performed via image-based technique. In order to simulate a flexible satellite, a free flying platform is used; the problem is furthermore complicated by the fact that the overall system, constituted by a highly rigid bus and very flexible panels, must necessarily be modeled as a multibody system. In the experimental campaign, the camera, placed on the bus, will be used to identify the eigenfrequencies of the vibrating structure; in this case aluminum thin plates simulate very flexible solar panels. The structure is excited by a hammer or studied during a fast attitude maneuver. The results of the experimental activity will be investigated and compared with respect to the numerical simulation obtained via a FEM-multibody software and the relevant results will be proposed and discussed.