碳布缝合预制体孔隙与热解碳沉积时变相依的多尺度研究

以甲烷为前驱体,碳布缝合织物为预制体,采用等温化学气相渗透(ICVI)工艺,在1 368 K温度和1 s滞留时间下制备了C/C复合材料。采用压汞仪表征不同致密化时间下预制体的孔隙分布,采用偏光显微镜观察热解碳的结构。结果表明:预制体的孔隙分布呈现多峰分布,热解碳的沉积速率与[A/V]值成反比,热解碳的结构与预制体的比表面积相关,沉积初期比表面积较大时,得到的热解碳织构为各相同性和低织构热解碳,随着沉积的进行,比表面积逐渐减小,在纤维束的边沿等部位出现了高织构热解碳。     

面向故障仿真的舵机系统建模方法研究

传统的基于传递函数和非线性微分方程的舵机系统模型无法直接描述舵机组件的物理参数,而这些参数直接反应组件的健康状况。专业的电路仿真软件的出现,为解决这一问题提供了方法。针对舵机系统故障仿真的需求,设计舵机模型原理框图;选用电路仿真软件Proteus搭建舵机的电路模型,设计单片机程序,实现舵机位置随动功能;分析模型的时域响应和频域响应特性,验证舵机系统电路仿真设计方法的可行性。以直流电机线圈电阻的故障模式为例,进行了故障仿真分析。     

A380客舱窗框结构设计的分析与研究

A380作为新一代大型客机的代表,数量庞大的大尺寸舷窗设计是众所瞩目的关键课题之一。通过与其他机型采用的窗框方案对比,重点分析A380窗框结构方案的优势,研究窗框结构的受载情况,将静力试验数据与有限元分析结果对比验证,从主结构的材料选用方面将A380的锻件窗框与不同材料的窗框进行对比分析。结果表明:A380客舱窗框结构的设计概念与现有机型相比,有效降低了加工复杂性、制造风险及研制成本,可为后续机型的窗框设计提供借鉴和参考。     

一种提高单片机内嵌式A/D分辨力的方法

单片机内嵌式Ａ／Ｄ的使用要比外置式Ａ／Ｄ简单、方便，且容易获得更高的信噪比，但其分辨力相对比较低，难以满足精密测量的使用要求。本文介绍了一种提高单片机内嵌式Ａ／Ｄ转换器分辨力有效实用法，简单外转电路和单片机内部软件计算可以将原分辨力将提高１￣３倍。     

Going to Alpha Centauri B and setting up a Radio Bridge

How to exploit the Sun as a gravitational lens has been studied extensively during the last 20 years, especially by this author (Refs. 1, 2, 3, 4, 5, 6 and 7). In essence, a spacecraft dubbed FOCAL (an acronym for “Fast Outgoing Cyclopean Astronomical Lens”) should be launched in the direction of the sky opposite to the area of the sky we wish to see highly magnified both at radio and other frequencies. After FOCAL reached the minimal focal distance of 550 AU from the Sun, highly magnified radio images of celestial objects located on the opposite side of the Sun will automatically be produced. In this paper we apply the FOCAL mission concept to the goal of exploring the neighborhood of the Alpha Centauri B star, where the nearest exoplanet to the Solar system was recently discovered. We suggest that:     

Validation of B0 and B1 in the IRI 2001 model at low solar activity for Ilorin an equatorial station

A new set of data obtained at low solar activity from Ilorin, Nigeria (geog. latitude 8.5°N, geog longitude, 4.6°E, dip 4.1°S) is used to validate the IRI 2001 model at low solar activity. The results show in general a good agreement between model and observed B0 at night but an over estimation during daytime. The overestimation is greatest during the morning period (0600LT–1000LT). The model prediction for B1 is fairly good at night and during the day. A dependence of B0 on solar zenith angle χ is observed during the daytime. A formulation of the form B0 = A[cos(χ)ⁿ] is therefore proposed. Values of the constants n and A were determined for the period of low solar activity for this station.     

KNR634A仪表着陆系统频率调谐码解算方法

KNR634A仪表着陆系统的频率调谐码为19位串行码，其中前3位为方式码，后16位包含了频率信息。本文介绍其解算方法。     

D406A钢板成形分析及防止拉深缺陷的对策

针对D406A钢板成形时容易产生开裂、起皱等缺陷的原因进行分析,选择优化的拉深工艺方案,软化处理拉深坯料,增加适当的热处理工序,正确选择和涂覆润滑剂,拉深过程中及时研磨模具工作面等。经验证,预防措施可保证拉深成形的合格率,拉伸件的质量稳定可靠。     

PHOTOMOS继电器在ZT—1自动投放接口盒测试仪中的应用

介绍最新半导体器件ＰＨＯＴＯＭＯＳ集成继电器的特点及其在ＺＴ－１型自动投放接口盒测试仪中的应用。