Tunnel/predictor display with two-axis control coordination and simplification

A longitudinal-lateral control coordination and simplification concept is considered for a tunnel/predictor display, which presents the command flight path and a specified future aircraft position in a 3-dimensional format to the pilot, for improving flight path control. A basic element of the proposed concept is the generation of common longitudinal-lateral transfer characteristics of the predictor-aircraft system for the crossover frequency region. Control coordination is supported by a dynamics similarity between the longitudinal and the lateral response characteristics of the predictor position in closed-loop pilot control actions. The control coordination and simplification concept is considered to support the pilot in manual flight path control, directed at an enhancement of his control performance and at a reduction of his workload. Results from pilot-in-the-loop simulation experiments support the theoretical findings and show the effectiveness of the proposed predictor concept with control coordination.     

Broad-band spectral properties of accreting X-ray binary pulsars

Broad-band spectra of accreting X-ray binary pulsars can be fitted by a phenomenological model composed of a power law with a high energy rollover above 10 keV, plus a blackbody component with a temperature of few hundred eV. While, at least qualitatively, the hard tail can be explained in terms of (inverse) Compton scattering, the origin of the soft component cannot find a unique explanation. Recently, a qualitative picture able to explain the overall broad-band spectrum of luminous X-ray pulsars was carried out by taking into account the effect of bulk Comptonization in the accretion column. After a review of these recent theoretical developments, I will present a case study of how different modeling of the continuum affect broad features, in particular the cyclotron resonance features in Vela X-1.     

四维下降飞行技术的研究与仿真：定常航迹角法下降剖面解算

本文研究的是四维飞行性能管理系统的核心环节－飞机在终端区域内的四维下降技术，首先探讨了基于常值航迹角的定常Ｍ数／指示空速下降飞行技术，论述了其高度剖面的构成与特点，通过尤拉积分方法求解飞机运动方程，实现了高度冲面的解算。其次开发了对速度剖面的迭代过程，选取原则及方法。本文在进行理论分析的同时，还开发了满意的仿真软件，一了其应用价值。     

TC4钛合金的微动磨损及防护

对Ｔｉ－６Ａｌ－４Ｖ合金在１８℃，１００℃２５０℃下的微动磨损特性及防护工艺进行了研究。表明：该合金微动磨损的主要磨损形式是疲劳脱层，其磨损量随温度升高而下降，高渐微动磨损量与磨损区表面所形成的氧化层的性质及厚度有关。     

管理软件生成器系统CDBAG—4GL

阐述了“管理软件生成器系统CDBAG-4GL”的研制背景、系统组成、逻辑结构、功能及特点;并简要介绍了设计思想、生成原理以及实现技术要点等。“CD-BAG一4GL”已商品化,它可根据用户要求自动生成各类专用的管理信息系统。为应用开发人员和最终用户提供一个一体化的通用的快速开发工具和环境。作为第四代软件开发工具的生成器和第四代语言是提高应用开发效率和质量的有效途径。     

CVD-Si3N4陶瓷及其复合材料氧化行为研究进展

概述了CVD—Si3N4陶瓷及其复合材料在干燥氧气下的氧化行为。Si3N4陶瓷在高温下氧化时，除生成SiO2保护膜外，还生成一薄层比SiO2膜更优异的氧气扩散阻挡层(Si—O—N化合物层)，该层具有优异的抗氧化性能。介绍了两种氧化机制模型，同时分析了温度、杂质等对CVD—Si3N4陶瓷氧化行为的影响。     

硅氮烷环体的催化聚合及热解制备Si3 N4 材料

采用甲基氢二氯硅烷的氨解产物硅氮烷环体(MHSZ)为原料,以四丁基氟化铵为催化剂,制备了高分子量的硅氮烷聚合物(PHSZ),结合红外、核磁、凝胶色谱仪和热重分析了反应时间对合成的PHSZ结构、组成、分子量和陶瓷产率的影响。考察了低温氨气,高温N2气氛处理工艺对热解产物结构和组成的影响。结果表明,随着反应时间的延长,PHSZ高聚物的分子量提高,热失重降低;采用该热解方式PHSZ可转化为含碳量仅为0.5wt%的Si3N4材料,热解样品在1 600℃时完全结晶,晶相主要是α-Si3N4。     

基于计划到达时刻的四维航迹规划

为了加速空管自动化与智能化技术的应用与实施,提出了水平航迹与高度/速度剖面分阶段设计的四维航迹规划方法。基于动态时间规整与层次聚类方法实现历史雷达航迹聚类分析,完成水平航迹设计。建立速度剖面规划模型,通过航迹生成器与速度调整器交互协作,精细化控制进场时间,以满足计划到达时间要求。以上海浦东国际机场PINOT进场航班为例实施验证,结果表明,四维航迹规划方法可有效实现航班的计划到达时间,从而减少航班延误,提高终端空域运行效率。     

TC4钛合金静止轴肩和传统搅拌摩擦焊的温度场对比

基于有限元软件ABAQUS对6mm厚的TC4钛合金传统及静止轴肩搅拌摩擦焊温度场进行了有限元模拟.结果表明,对比传统搅拌摩擦焊接,静止轴肩搅拌摩擦焊接具有较小的高温区,前进方向上具有较大的温度梯度,厚度方向上呈现柱状椭球形分布,上、下表面温度峰值差异较小,具有重叠性较好的热循环曲线.     

The Primordial Helium-4 Abundance from Observations of a Large Sample of Blue Compact Dwarf Galaxies

We use a sample of 45 low-metallicity H II regions in blue compact dwarf (BCD) galaxies to determine the primordial helium abundance YP with a precision better than 5%. We have carefully investigated the physical effects which may make the He I line intensities deviate from their recombination values such as collisional and fluorescent enhancements, underlying He I stellar absorption and absorption by Galactic interstellar Na I. By extrapolating the Y vs. O/H and Y vs. N/H linear regressions to O/H = N/H = 0, we obtain YP = 0.244±0.002 and 0.245±0.001, respectively, higher than previous determinations (YP = 0.230 - 0.234). Part of the difference comes from the fact that previous investigators have not taken into account underlying He I stellar absorption, especially in the NW component of the BCD I Zw 18 which, because of its extremely low metallicity plays a key role in the determination of YP. We derive a slope dY/dZ = 2.3±1.0, considerably smaller than those derived before. With this smaller slope and taking into account the errors, chemical evolution models with an outflow of well-mixed material can be built for star-forming dwarf galaxies which satisfy all the observational constraints. Our YP gives _bh ₅₀ ² = 0.058±0.007,f consistent with the lower limit set by dynamical measurements and X-ray observations of clusters of galaxies. It is also consistent, within the framework of standard big bang nucleosynthesis theory, with measurements of primordial 7Li in galactic halo stars and with the D/H abundance measured in absorption systems toward quasars by Burles and Tytler (1997).