首次从理论上阐明石英谐振器在室温、低温下1/f噪声和Q值的关系

石英晶体振荡器的极限稳定度是由时域噪声本底相对应的石英谐振器频率噪声决定的。只有减小电子噪声的起伏,才能测量谐振器本身的谐振频率起伏。使用π型传输网络和相位平衡电桥,能够将激励源的相位起伏抑制50-60dB。此测量系统曾在室温下测量了大量的成对谐振器,发现1/f 频率噪声电平和 Q 值之间的相互关系遵循1/Q~4规律。为了将谐振器频率起伏的测量扩展到极低温,研究了一种能测不同谐振器对的新测量系统。因此,在4K 和1K 温度下测得了1/f 频率噪声,并观察到随着 Q 值的增加而噪声大大减小。现在有一种理论能解释1/Q~4规律。这就是根据声波衰减和速度变化引起的三声子相互作用过程来解释。声波衰减和速度变化这两种现象均可用热声子的张弛时间来加以说明。     

NPU翼型的气动力分析和改进设计

 在飞行器设计中用计算方法设计超临面翼型已完全取代了选用现成翼型的设计方法。为考察已设计出的NPU翼型是否满足飞行器设计要求我们对其进行了全面气动分析,发现这些翼型尚有不足之处,有必要进行改进设计。     

Biofeedback monitoring-devices for astronauts in space environment

After a reconsideration of the state-of-the-art in biofeedback research the implementation of biofeedback systems is envisioned as a countermeasure of stress for the psychoprophylaxis of the astronaut. A one-session experiment performed on two groups of subjects to assess the interference from EMG-feedback on the performance in a simultaneous psychomotor trial with a view to expanding biofeedback application is described. The results show that the experimental group performed in the same way as the control without feedback, but with less CNS activation. Some general conclusions are drawn from the advances in technology.     

Chronic orthostatic and antiorthostatic restraint induce neuroendocrine, immune and neurophysiologial disorders in rats

The tail-cast suspension rat model has been developed in ground laboratories interested in space physiology for extensive study of mechanisms causing the pathophysiological syndrome associated with space flights. We used individually-caged male rats to explore the effects of acute and chronic (7d) orthostatic restraint (OR) and head-down anti-orthostatic restraint (AOR) on a series of physiological variables. The acute restraint study showed that (1) the installation of the OR device induced an acute reaction for 2 days, with a substantial rise in ACTH (x2) and CORT (x6), and that (2) the head-down tilt from OR to AOR induced (i) within 10 min and lasting 60 min a 2-fold rise in the intra-cerebro-ventricular pressure (Picv) monitored with an icv telemetric recording system, which receded to normal between 60 and 120 min; and (ii) within 30 min a short-lived 4-fold rise in plasma ACTH and CORT levels. Chronic OR induced (1) the suppression of the diurnal ACTH/CORT rhythm, with increased mean levels, especially for ACTH, (2) a degraded circadian locomotor activity rhythm manifested by a significant reduction in the spectral power of the 24h periodicity and a concomitant emergence of shorter (ultradian) periodicities, (3) an associated, but less pronounced alteration of the diurnal rhythm in body temperature; and (4) a marked increase in baseline plasma levels of IL-1β and an increased reactivity in cytokine release following an E. coli endotoxin (LPS) challenge. AOR induced (1) a similar obliteration of the circadian ACTH/CORT rhythm, (2) the loss of close correlation between ACTH and CORT, (3) a generalized increase in baseline plasma IL-1β levels and (4) more extensive degradation of the arcadian periodicity for both locomotor activity and, to a lesser extent, body temperature, replaced by dominant spectral powers for ultradian periodicities (3 to 10h). In conclusion, both experimental paradigms — but AOR more than OR — caused a blockade of the arcadian rhythmicity of major physiological variables, the loss of normal correlations between ACTH and CORT, and inflammatory-immune hyperreactivity. These pathophysiological disorders may all be parts of a complex chronic stress syndrome.     

Cardiac and vascular adaptation to 0g with and without thigh cuffs (Antares 14 and Altair 21 day Mir spaceflights)

Cardiovascular Actaptation was evaluated on 2 astronauts: one wearing thigh cuffs from flight day 1 to 8 (14d flight), the second without cuffs (21d flight). Ultrasound investigations were performed at rest and during LBNP. Results: Without thigh cuffs the cardiovascular Actaptation consists in (1) the development of a hypovolemia with an increase of the heart rate and the cardiac output, (2) the decrease of the vascular tone in the deep (mesenteric and splanchnic) and peripheral (Lower limbs) vascular areas. The use of thigh cuffs maintains the volemia and the cardiac output at the preflight level (without heart rate increase) and prevents the loss of vascular tone in the deep and peripheral areas. Moreover the adaptative process changes since the cuffs are removed and even the volemia seems to be unaffected at this stage the vascular tone decreases to a comparable extend as during the flight without cuffs. Nevertheless during the flight without cuffs or 3 days after removing the cuffs hemodynamic signs of decreased orthostatic tolerance are present during the inflight and the 3 days post flight LBNP. Presently the possible contribution of the thigh cuffs to the reduction of the vascular deconditioning has not been tested yet.     

Radiation protection in space

Radiation environment, basic concepts of radiation protection, and specific aspects of the space radiation field are reviewed. The discussion of physico-chemical and subcellular radiation effects includes mechanisms of radiation action and cellular consequences. The discussion of radiobiological effects includes unique aspects of HZE particle effects, space flight findings, terrestrial findings, analysis of somatic radiation effects and effects on critical organs, and early and delayed effects. Other topics include the impact of the space flight environment, measurement of radiation exposure, establishing radiation protection limits, limitations in establishing space-based radiation exposure limits, radiation protection measures, and recommendations.     

Space radiation dosimetry

In this report dosimetric measurements are presented which were performed during the missions Spacelab 1, D 1, Biocosmos 8 and Biocosmos 9. Detector packages consisting of plastic nuclear track detectors, nuclear emulsions and thermoluminescence dosimeters were exposed at different locations inside and outside spacecrafts behind more or less well defined shielding thicknesses. These detector systems which supplement each other in their registration characteristic allow to record all biological relevant portions of the radiation field separately. Dose equivalents for the astronauts have been calculated from the measurements using the quality factors as defined in the old and the new recommendations of the International Commission on Radiation Protection (ICRP).     

用航空遥感器对海岸带海洋水色的分析

本文介绍了一种利用航空遥感器分析海岸带海洋水色的方法,这种方法已应用于亚得利亚海北部试验区,在不同高度上所获得的多光谱数据中。从海洋水色辐射计(工作谱段与海岸带彩色扫描仪相同)和六通道辐射计(工作在叶绿素自然荧光的光谱区域)所获得的数据,已用水色遥感辐射过程的模型,对大气和海面的影响进行了修正。遥感得到的水辐射光谱以及叶绿素和沉积物浓度经大气和海面影响修正之后的数据,证实了这种方法对悬浮或溶解于海水中的物质具有定量分析的能力。     

单片集成温度传感器

本文介绍利用双极型晶体管和集成电路构成温度传感器的各种方法。讨论了单晶体管敏感元件的性能。文中提出二种集成电路,其一的输出电流精确地正比于绝对温度。另一种新型的集成电路的输出电流可按°C、°F或任意分度。此外还介绍了一些供特殊应用的集成温度传感器,其中包括精密的小量程温度传感器、具有逻辑及模似信号输出的温度传感器和温控振荡器。