基于查表的开环MPM预失真器

提出了一种基于查表的开环记忆多项式模型(MPM,Memory Polynomial Model)预失真器.从MPM预失真器系数估计和执行信号预失真处理两方面加以考虑.首先,利用预失真器和高功率放大器(HPA,High Power Amplifier)传输特性的互补性,由采集到的HPA输入、输出基带数据进行单次最小二乘估计得到MPM预失真器的系数,避免了以往递归结构的收敛性和计算量大等问题.然后,利用MPM预失真器的特点,建立了基于输入信号强度索引的一维向量表,通过查表实现MPM预失真器的幂次累加项,极大地减少了实现预失真器所需的计算量及硬件开销.仿真显示,采用提出的预失真器可以有效补偿HPA对信号的记忆非线性失真,有效带宽内获得了近20 dB的功率改善,也显著改善了系统误码性能.     

电子对抗有效载荷地面测试与评估技术

描述电子对抗有效载荷地面测试系统的设计内容,介绍了测试系统的主要组成、功能及测试工作原理,常有的测试项目、测试方法,载荷的数据整理、评估与分析等,为以后电子对抗载荷地面系统搭建提供参考借鉴作用。     

《诗经》中女性生命价值的解读

中国的伦理文化中,对母性的塑造一方面是对"女色"的危害进行严惩,另一方面是对女性进行引导,使她们能够按照指定的方向行进,最终使所有的女性都安于贤妻良母的价值规范。透过《诗经》及后世对《诗经》的解读即可看出男性对女性的价值期待。     

Numerical simulation of a rotary engine primary compressor impacted by bird

In order to examine the process of a rotary engine primary compressor impacted by bird, a finite element model of a bird impacted on plate is developed with the explicit code PAM-CRASH. The smooth particles hydrodynamic (SPH) method is used to simulate the bird because of the SPH method showing no signs of instability and correctly modeling the breaking-up of the bird into particles. Good agreement between the simulation results and experimental results indicates that the numerical method of bird strike used in the present paper is reasonable. Then a rotary engine primary compressor impacted by three different configurations bird named straight-ended cylinder bird, quadrangular bird, hemispherical-ended bird are investigated using the numerical simulation method. It is found that the whole process of bird strike sustained about 3.5 ms and the bird is slashed by blade during the strike. The geometry configuration of bird affected the displacement and von Mises stress of some blades severely, just because the breaking bird’s mass is affected by the bird’s configuration. In the event of bird striking on the site of"up"some blades may develop plastic deformation and it is very adverse for the safety work of the engine.     

Decision-making of Aircraft Optimum Configuration Utilizing Multidimensional Game Theory

As multi-discipline coupling and components interference often affect the aircraft configuration decision-making and analysis during conceptual design process, this article presents an approach of multidimensional game theory based on aircraft components to deal with this problem. The idea is that the configuration decision-making process is regarded as the game for different disciplines and technologies, and the aircraft components are players. The payoff function with highest total gain means that according to the game protocols and multidimensional theory, the optimal aircraft configuration within the strategy set will be chosen. The decision-making model is applied to conceptual design process of the high altitude long endurance (HALE) unmanned aerial vehicle (UAV) based on the assessment of technological risk. The obtained optimum configuration is quite consistent with the current HALE UAV development trends. Thus, taking into account the coupling and interference factors, the multidimensional gaming model based on aircraft components will be an effective analysis method in the decision-making process of aircraft optimum configuration.     

自动微装配技术在航空机载光机电传感器装调中的应用

介绍了自动微装配技术在机载传感器装调中应用的整体思路及应用方案,通过对微小型零件夹持、精密定位、显微视觉和在线测量等先进装调中关键技术的研究,开发了光纤陀螺、高精度加速度计等产品成套自动装配的技术装备,解决了目前精度不高、装调一致性差、手工作业和产能不足等问题,从而整体提升了机载产品制造技术的水平.     

Measurements of heat transfer and pressure in a trailing edge cavity of a turbine blade

 An experimental investigation is conducted to obtain the heat transfer and pressure drop data for an integral trailing edge cavity test section that simulates a novel turbine blade's internal cooling passage with bleed holes. Local heat transfer is measured on both the suction and pressure sides by a transient liquid crystal technique, while pressures at six positions are recorded by pressure calibrators. Moreover, flow characteristic and its effect on heat transfer are analyzed for conditions with or without bleed flow. The experimental results show that, in the cases with bleed flow, local heat transfer on the pressure side exceeds that on the suction side in the first and second channels. In the cases without bleed flow, in the first and third channels, local heat transfer on the suction side weakens whilst it increases significantly on the pressure side. For the second channel, non-bleed condition leads to a more balanced heat transfer distribution between the upstream and downstream channel. Besides, after the bleed holes are blocked, heat transfer in the first bend region on the suction side declines sharply, while the opposite phenomenon occurs for the second bend region on the pressure side. In both bleed and non-bleed cases, the total pressure of six measurement positions decreases continuously along the channel at the same Reynolds number and it promotes for higher Reynolds number. Among all the measurement points, under the same flow rate condition, the highest speed occurs at Position 5, which also shows the maximum difference between the total and static pressures. When the bleed holes are blocked, the total pressure at each measurement position appears to increase.     

声波激振的微观机理探讨

在对物质粒子运动和能量传递以及微观粒子运动和能量变化两个层面进行辨证分析和逻辑推理的基础上,结合航空发动机流道内的实际情况,对声波激振的微观机理作了整体描述.得出了若干初步的定性结论.文中分析研究有助于建立物体振动微观粒子运动分析计算的数理模型,推论方法和结论,还有待进一步深入研究确证.     

Student and Teacher Attitudes towards the Role of the Mother Tongue in English Class: Report of a Questionnaire Study

This article presents the results of a questionnaire study on the role of the mother tongue in English class. The participants were 50 students and 10 teachers. The goal of the study was to investigate (1) the attitudes of both teachers and students towards the use of Chinese; (2) the actual and potential function of Chinese in English class. The results of this study indicate that Chinese was still quite extensively used in English class,that both the teachers and the students respond positively to a reaso...