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。     

1980年固体火箭技术的成就

虽然美航宇局的航天飞机一再推迟发射日期,而赛奥科尔公司研制的固体火箭助推器(SRB)仍取得了明显的进展。1980年2月第三台即最后一台鉴定发动机进行了静态试车。航天飞机初次飞行用的第一段发动机在9月26日运到肯尼迪空间中心。赛奥科尔公司已完成了第二次飞行用的发动机和喷管出口锥的生产工作,第三次飞行用的发动机将于80年底生产出来。     

CELSS nutrition system utilizing snails

At the 40th IAF Congress in Malaga, a nutrition system for a lunar base CELSS was presented. A lunar base with a total of eight crew members was envisaged. In this paper, four species of plants--rice, soybean, lettuce and strawberry--were introduced to the system. These plants were sufficient to satisfy fundamental nutritional needs of the crew members. The supply of nutrition from plants and the human nutritional requirements could almost be balanced. Our study revealed that the necessary plant cultivation area per crew member would be nearly 40 m3 in the lunar base. The sources of nutrition considered in the study were energy, sugar, fat, amino acids, inorganic salt and vitamins; however, calcium, vitamin B2, vitamin A and sodium were found to be lacking. Therefore, a subsystem to supply these elements is of considerable value. In this paper, we report on a study for breeding snails and utilizing meat as food. Nutrients supplied from snails are shown to compensate for the above mentioned lacking elements. We evaluate the snail breeder and the associated food supply system as a subsystem of closed ecological life support system.     

Leg venous hemodynamics and leg volumes during a 42 day -6 degrees head-down bedrest

Seven healthy subjects were submitted to a 42-day head down bedrest, where leg venous compliance (venous distensibity index VDI) and leg volumes were assessed by mercury strain gauge plethysmography with venous occlusion and optoelectronic plethysmography, respectively. Plethysmographic and volometric measurements were made, before, during (at days 1, 4, 7, 14, 21, 26, 34 and 41), and after bedrest (days 1, 4, 7, 11 and 30 of the recovery period). Results showed a continuous decrease in leg volumes throughout bedrest, when VDI increased until day 26 of bedrest, and then decreased afterwards. The recovery period was characterized by a rapid return of VDI to prebedrest levels while leg volumes progressively normalised. These results showed that leg venous compliance changes are not always dependant upon skeletal muscle changes, and that factors other than size of muscle compartment are able to determine increases in leg venous compliance during long-term bedrest.     

Spatial orientation during locomotion [correction of locomation] following space flight

To investigate changes in spatial orientation ability and walking performance following space flight, 7 astronaut subjects were asked pre- and post-flight to perform a goal directed locomotion paradigm which consisted of walking a triangular path with and without vision. This new paradigm, involving inputs from different sensory systems, allows quantification of several critical parameters, like orientation performance, walking velocities and postural stability, in a natural walking task. The paper presented here mainly focusses on spatial orientation performance quantified by the errors in walking the previously seen path without vision. Errors in length and reaching the corners did not change significantly from pre- to post-flight, while absolute angular errors slightly increased post-flight. The significant decrease in walking velocity and a change in head-trunk coordination while walking around the corners of the path observed post-flight may suggest that during re-adaptation to gravity the mechanisms which are necessary to perform the task have to be re-accomplished.     

Influence of graviceptives cues at different level of visual information processing: the effect of prolonged weightlessness

We evaluated the influence of prolonged weightlessness on the performance of visual tasks in the course of the Russian-French missions ANTARES, Post-ANTARES and ALTAIR aboard the MIR station. Eight cosmonauts were subjects in two experiments executed pre-flight, in-flight and post-flight sessions.

In the first experiment, cosmonauts performed a task of symmetry detection in 2-D polygons. The results indicate that this detection is locked in a head retinal reference frame rather than in an environmentally defined one as meridional orientations of symmetry axis (vertical and horizontal) elicited faster response times than oblique ones. However, in weightlessness the saliency of a retinally vertical axis of symmetry is no longer significantly different from an horizontal axis. In the second experiment, cosmonauts performed a mental rotation task in which they judged whether two 3-D objects presented in different orientations were identical. Performance on this task is basically identical in weightlessness and normal gravity.     

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.     

Lower body negative pressure (LBNP) as a countermeasure for long term spaceflight

The article presents the current status of lower body negative pressure (LBNP) as a countermeasure for preventing orthostatic intolerance after space flight or bed rest. Devices discussed include the Chibis vacuum suit, the Anthrorack device, a collapsible device, and an inflatable device. Two bed rest studies examined the effect of LBNP and exercise on orthostatic tolerance; plasma volume; vasopressin, plasma renin activity, and catecholamines; and side effects.     

铸造高温合金熔炼工艺中的冶金原则

文中介绍了苏联铸造高温合金工艺中冶金原则的发展。除去合金化元素之外,杂质元素和微量添加元素是决定合金组织和性能的最重要因素之一。文中详细讨论了在不同条件下它们对合金高温性能的影响。结论中提出改进铸造高温合金冶炼工艺的若干有效的措施。