反辐射导弹趋向多目标打击能力

美国的新型反辐射导弹AARGM已经具备了打击非辐射源目标的多目标打击能力,这种能力将给反辐射导弹作战领域带来革命性的变化。近年来,以多模导引头技术、多模战斗部技术为代表的多种相关技术发展迅速,反辐射导弹正在进入一个崭新的＂多目标＂发展时期。     

The effects of simulated microgravity on cultured chicken embryonic chondrocytes.

Using the cultured chicken embryonic chondrocytes as a model, the effects of simulated microgravity on the microtubular system of the cellular skeleton, extracellular matrix, alkaline phosphatase activity, intracellular free calcium concentration and mitochondrial ATP synthase activity with its oligomycin inhibition rate were studied with a clinostat. The microtubular content was measured by a flow cytometer. The decrease of microtubular content showed the impairment of the cellular skeleton system. Observation on the extracellular matrix by the scanning electron microscopy showed that it decreased significantly after rotating, and the fibers in the extracellular matrix were more tiny and disorderly than that of the control group. It can be concluded that the simulated microgravity can affect the secreting and assembly of the extracellular matrix. In contrast to the control, there was a time course decrease in alkaline phosphatase activity of chondrocytes, a marker of matrix mineralization. Meanwhile a significant drop in the intracellular calcium concentration happened at the beginning of rotation. These results indicate that simulated microgravity can suppress matrix calcification of cultured chondrocytes, and intracellular free calcium may be involved in the regulation of matrix calcification as the second signal transmitter. No significant changes happened in the mitochondrial ATP synthase activity and its oligomycin inhibition rate. Perhaps the energy metabolism wasn't affected by the simulated microgravity. The possible mechanisms about them were discussed.     

Design and testing of spacecraft power systems using VTB

A study is presented on the design and testing of spacecraft power systems using the virtual test bed (VTB). The interdisciplinary components such as solar array and battery systems were first modeled in native VTB format and validated by experiment data. The shunt regulator and battery charge controller were designed in Simulink according to the system requirements and imported to VTB. Two spacecraft power systems were then designed and tested together with the control systems.     

VELOCITY FIELD OF THERMOCAPILLARY CONVECTION IN HIGH-TEMPERATURE OXIDE SOLUTION

We have investigated experimentally and theoretically the thermocapillary convec tive flow phenomena in a loop-shaped Pt wire heater of KNbO3 (20wt.%) and Li2B4O7 solutions. Optical evaluations in connection with thermocouple measure ments made it possible to get a new type of thermocapillary convective flow in the considered system. To study the kinematical behaviour of thermocapillary convec tion, we have measured the stream flow velocities. In a theoretical analysis, the flow velocity due to the thermocapillary effect alone was estimated by balancing the sur face tension forces by viscous forces. The velocity distribution in the solution near the margin of the heater was obtained, which is in agreement with the experimental result.     

硅液相外延生长的晶向自动偏离现象

通过对液相外延的薄膜Ｘ衍射测试，结果显示不论衬底是否偏离［１１１］晶向，外延层在同一衍射位置都出现了双峰。经比较分析，确认了硅（１１１）面在液相外延生长时存在晶向自动偏转现象。     

Fault tolerant control system design with explicit consideration of performance degradation

A new approach is proposed for active fault tolerant control systems (FTCS), which allows one to explicitly incorporate allowable system performance degradation in the event of partial actuator fault in the design process. The method is based on model-following and command input management techniques. The degradation in dynamic performance is accounted for through a degraded reference model. A novel method for,selecting such a model is also presented. The degradation in steady-state performance is dealt with using a command input adjustment technique. When a fault is detected by the fault detection and diagnosis (FDD) scheme, the reconfigurable controller is designed automatically using an eigenstructure assignment algorithm in an explicit model-following framework so that the dynamics of the closed-loop system follow that of the degraded reference model. In the mean time, the command input is also adjusted automatically to prevent the actuators from saturation. The proposed method has been evaluated using the lateral dynamics of an F-8 aircraft against actuator faults subject to constraints on the magnitude of actuator inputs. Very encouraging results have been obtained.     

Remote sounding of atmospheric gravity waves with satellite limb and nadir techniques

Recent advances in satellite techniques hold great potential for mapping global gravity wave (GW) processes at various altitudes. Poor understanding of small-scale GWs has been a major limitation to numerical climate and weather models for making reliable forecasts. Observations of short-scale features have important implication for validating and improving future high-resolution numerical models. This paper summarizes recent GW observations and sensitivities from several satellite instruments, including MLS, AMSU-A, AIRS, GPS, and CLAES. It is shown in an example that mountain waves with horizontal wavelengths as short as 30 km now can be observed by AIRS, reflecting the superior horizontal resolution in these modern satellite instruments. Our studies show that MLS, AMSU-A and AIRS observations reveal similar GW characteristics, with the observed variances correlated well with background winds. As a complementary technique, limb sounding instruments like CRISTA, CLAES, and GPS can detect GWs with better vertical but poorer horizontal resolutions. To resolve different parts of the broad GW spectrum, both satellite limb and nadir observing techniques are needed, and a better understanding of GW complexities requires joint analyses of these data and dedicated high-resolution model simulations.     

光纤测振和光探头信号的一些问题

本文介绍了光纤测振的基本原理,推导了理想光脉冲信号的形状和探测几率,其结果可为光源、光纤和叶片之间的匹配提供依据,也可在信号采集和处理中作参考。     

关于输出反馈特征结构配置的鲁棒性

本文讨论了多参数小扰动情况下,利用输出反馈进行特征结构配置的参数不灵敏的条件问题,证明了有关定理,给出了释例。     

曲壁气膜冷却数值计算的研究

 本文在一般二维边界层流动和换热计算方法的基础上,引入湍流混合长度的修正模型,用以考虑壁面曲率和注入冷气对换热的影响,研究计算了壁面的弯曲部分和曲率恢复部分换热的变化,并对曲面上的气膜冷却问题作了计算,取得较满意的结果。