新型除氧喷嘴的雾化性能

对新型撞击式除氧喷嘴产生的雾滴尺寸、分布与喷嘴几何参数及工作压力的关系进行了研究。测量使用激光大粒径测量仪,其实时测量范围为75～3000μm。该喷嘴在工作压力为0.1～0.6MPa 时产生,雾滴的索太尔平均粒径小于900μm,粒径随供水压力增加而减小。应进一步研究这种喷嘴的几何参数,特别是射流孔口直径及孔口至撞击杆的距离对雾化的影响,以提高它的雾化性能。     

一种变速恒频（VSCF）飞机发电机系统的数学仿真

目前，可变频输入恒频输出的直流环路变换器已成为极具发展前途，并可替代恒速机械传动装置的装置之一，可作为来自飞机发电机的一种恒频电源。更换和维修的简便性、维护要求的降低以及具有判定飞机上所有电气系统元件位置的能力结合起来，使维护时间明显减少了。介绍了典型电气系统数字仿真的一种实用计算方法，该方法把整个电源网络初步分为一组恰当的子网络，然后利用连接矩阵把各子网络的计算方程与整个网络的方程组合。给出了整个系统的典型结果，其具体性能使许多重要的设计考虑在制造前就得到了研究。     

Conversations with Norman Augustine. Interview by Linda Voss

Topics discussed in the interview include trends and economic issues in the aerospace industry, the role of the aerospace industry in national security, and mergers and new ventures in the aerospace industry.     

Beyond the principle of plentitude: a review of terrestrial planet habitability

We review recent work that directly or indirectly addresses the habitability of terrestrial (rocky) planets like the Earth. Habitability has been traditionally defined in terms of an orbital semimajor axis within a range known as the habitable zone, but it is also well known that the habitability of Earth is due to many other astrophysical, geological, and geochemical factors. We focus this review on (1) recent refinements to habitable zone calculations; (2) the formation and orbital stability of terrestrial planets; (3) the tempo and mode of geologic activity (e.g., plate tectonics) on terrestrial planets; (4) the delivery of water to terrestrial planets in the habitable zone; and (5) the acquisition and loss of terrestrial planet carbon and nitrogen, elements that constitute important atmospheric gases responsible for habitable conditions on Earth's surface as well as being the building blocks of the biosphere itself. Finally, we consider recent work on evidence for the earliest habitable environments and the appearance of life itself on our planet. Such evidence provides us with an important, if nominal, calibration point for our search for other habitable worlds.     

先进的航天发动机试验

本文报导一种航天发动机的高空模拟点火试验。这种发动机综合利用了几种先进技术:90%固体燃料的端羟基聚丁二烯/铝粉/过氯酸铵/奥克托金推进剂;在凯夫拉壳体内的头端满装药;无支撑的整体喉部和收敛段入口;特轻的喷管和用充气膨胀的作动筒展开的可延伸出口锥。这次试验结束了法国欧洲动力公司和美国联合工艺公司化学系统分部之间为期两年的分工协作的研究和试制工作。所达到的比冲值被认为是复合推进剂在样机发动机中的一个最高记录。     

Recent results of the joint ESA-DARA/IBMP experiments Biokosmos "Seeds"

Comparison of experimental data obtained from short (SDEF) and long duration exposure flights (LDEF) have recently led to results which will be significant for longer and/or repeated sojourn of man in space. Under orbital conditions biological stress and damage are induced in test subjects by cosmic radiation, especially the high energetic, densely ionizing component of heavy ions. Plant seeds were successful model systems for a biotest in studying the physiological damages and mutagenic effect caused by ionizing cosmic radiation in particular stem cells. Dosimetrically, the subdivision into charge- and Let-groups reveals the contribution of the intermediate group (LET = 350-1000 MeV/cm) due to the medium heavy ions (Z = 6-10). Their relative contribution increases with the lower inclination of the orbit of LDEF-1; on the other hand, the total fluence becomes higher with longer duration of the flight. The observed endpoints of the biological radiation damage hint at a correlation with particle dose rate rather than with the dose; additionally, data on shielding effects inside and outside the space craft and its exposure were gained from the different SDEF- and LDEF-missions.     

Invariant and energy analysis of an axially retracting beam

The mechanism of a retracting cantilevered beam has been investigated by the invariant and energy-based analysis. The time-varying parameter partial differential equation governing the transverse vibrations of a beam with retracting motion is derived based on the momentum theorem. The assumed-mode method is used to truncate the governing partial differential equation into a set of ordinary differential equations (ODEs) with time-dependent coefficients. It is found that if the order of truncation is not less than the order of the initial conditions, the assumed-mode method can yield accurate results. The energy transfers among assumed modes are discussed during retrac-tion. The total energy varying with time has been investigated by numerical and analytical methods, and the results have good agreement with each other. For the transverse vibrations of the axially retracting beam, the adiabatic invariant is derived by both the averaging method and the Bessel function method.     

过氯酸铵粒度对燃烧横向气流响应的影响

对线性速度耦合的燃烧响应函数发展了一种分析模型。该模型讨论了压力成分(由于复台推进剂的不均匀性)及横向气流速度扰动的请参数响应。过氯酸铵(AP)粒度的影响可通过对弹道的控制特性及推进剂成分的波动影响来考虑。横向气流有两个力面的影响:横向气流速度对各种响应参数的影响以及对速度扰动的响应。本文讨论了这两个问题,叙述了由一系列参数计算而导出重要趋势。     

小型化GPS接收机

首先介绍小型化 GPS 接收机的设计思想、数字化、按功能分配集成芯片模块、射频,中频电路采用 MMIC,数字电路采用 VHSIC/VLSI 等。给出接收机的组成。然后讨论合成 MMIC 信号处理蕊片、多功能接口蕊片及数字处理芯片等。软件用 Ada 语言编写,文中列出软件的主要功能。     

航天飞机尾部服务塔的设计和研制

航天飞机的成功发射取决于两个尾部服务塔的正常工作。通过完整的设计、研制和试验计划保证了尾部服务塔工作的可靠性。在前一篇文章(参考文献1)中，已叙述了尾部服务塔的方案验证试验。本文提出了方案验证试验的结果和对尾部服务塔样机设计所带来的影响。简述了设计准则，对所提出的尾部服务塔样机试验作了阐述。