螺栓挤压推力终止系统验证试验

本文总结了螺栓挤压推力终止系统(BETTS)的设计、研制和验证试验。该系统在阿诺德工程研制中心(AEDC)进行了多次冷试,一次海平面热试和两次高空点火推力终止试验,试验所用的发动机是政府向化学系统分公司提供的“民兵”发动机空壳体装药后制成的。通过大发动机热试,证明本计划所验证的这种BETTS可以消除前部碎片,大大地简化药柱和发动机壳体的设计,提高末级性能。另外,这种方法设计简单,从而可以降低推进系统的成本。BETTS用爆炸螺栓和挤压螺栓的组合代替连接喷管法兰和发动机壳体法兰的普通螺栓。接到指令后,爆炸螺栓立即打开,喷管循着挤压螺栓向后平移,发动机气体迅速排出,从而使推进剂熄火。挤压螺栓控制着喷管的移动速度和最大运动行程。以前根据NO.F04611—75—C—0044合同(CSD计划2549)曾成功地在缩比发动机上进行了BETTS热试和在飞行重量的“民兵”Ⅲ第三级发动机上进行了冷试。     

HTPB推进剂的老化及使用寿命

为了进行老化评价研究,选择和研制了三种不同固体含量的(88～91%)端羟基聚丁二烯(HTPB)推进剂。已经证实,88%固体含量的HTPB推进剂符合以前提出的老化模型。这种老化模型已成功地进一步用于较高固体含量的推进剂以及其它计划用的HTPB推进剂的实测力学性能老化数据。采用这种老化模型,根据加速热老化试验数据予测了长期力学性能,予测数据与六年实测老化数据相当一致。利用予测的推进剂破坏性能,结合火箭发动机的要求,来确定予先选定安全裕度的发动机药柱的使用寿命。本文列出了各种复合推进剂老化速率的比较数据。根据老化结果的分析,提出了一个宽范围老化行为的数学表达式。     

The Suess-Urey mission (return of solar matter to Earth)

The Suess-Urey (S-U) mission has been proposed as a NASA Discovery mission to return samples of matter from the Sun to the Earth for isotopic and chemical analyses in terrestrial laboratories to provide a major improvement in our knowledge of the average chemical and isotopic composition of the solar system. The S-U spacecraft and sample return capsule will be placed in a halo orbit around the L1 Sun-Earth libration point for two years to collect solar wind ions which implant into large passive collectors made of ultra-pure materials. Constant Spacecraft-Sun-Earth geometries enable simple spin stabilized attitude control, simple passive thermal control, and a fixed medium gain antenna. Low data requirements and the safety of a Sun-pointed spinner, result in extremely low mission operations costs.     

The effect of head-down tilt on brain potentials related to visual attention

To study the possible effect of simulated weightlessness on brain function state, the brain event-related potentials (ERPs) in a simple visual selective response task were compared between HDT and HUT in 9 normal subjects. The results were: The Target(T) and non-Target(NT) flash signals both induced significant slow positive potentials which were supposed to related to the attention state; the amplitude of the positive potentials in frontal regions decreased significantly especially for NT-ERPs during HDT comprared with that during HUT. The data reported provide new evidence indicating that more attention should be paid on the brain function study during space flight.     

DO 28飞行试验数据一致性检验

 本文研究DO28试验机飞行试验数据一致性检验及其误差校正。建立了由非线性运动学方程及内容广泛的校正环节构成的一致性检验模型,解决了大地风场重构、测量信号时间延迟估计、ψ转换及测量控制信号的校正。为DO28参数估计提供了可靠、准确的飞行试验数据。     

Multistage integration model for human egomotion perception

Human computational vision models that attempt to account for the dynamic perception of egomotion and relative depth typically assume a common three-stage process: first, compute the optical flow field based on the dynamically changing image; second, estimate the egomotion states based on the flow; and third, estimate the relative depth/shape based on the egomotion states and possibly on a model of the viewed surface. We propose a model more in line with recent work in human vision, employing multistage integration. Here the dynamic image is first processed to generate spatial and temporal image gradients that drive a mutually interconnected state estimator and depth/shape estimator. The state estimator uses the image gradient information in combination with a depth/shape estimate of the viewed surface and an assumed model of the viewer's dynamics to generate current state estimates; in tandem, the depth/shape estimator uses the image gradient information in combination with the viewer's state estimate and assumed shape model to generate current depth/shape estimates. In this paper, we describe the model and compare model predictions with empirical data.     

四川振动座谈会在绵阳召开

四川省力学学会、西南结构力学研究所、四川省振动工程学会(筹)于1987年11月4日至7日在绵阳市联合召开了“四川省振动工程学术交流座谈会”。出席代表86人,他们来自中央部属(在川)、省、市20多单位。代表都是在力学、数学、机械、航空、核工程、电子、冶金、化工、电力、建筑、石油、地震等各领域从事振动工程、研究、教学、应用的     

STUDY ON THE SOLUTION OF DYNAMIC THERMOELASTICITY SYSTEM

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A PARALLEL IMAGINARY EBE METHOD FOR SOLVING POSITIVE DEFINITE LINEAR SYSTEMS

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ELECTRONIC CONTROL OF TURBINE POWER UNITS

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