Titan and exobiological aspects of the Cassini-Huygens mission

Titan, the largest satellite of Saturn, has a dense N2-CH4 atmosphere rich in organic compounds, both in gas and in aerosol phases. Its surface is probably covered by oceans of liquid methane-ethane mixtures, with many dissolved organics. This quasi planet appears as a natural laboratory to study chemical evolution toward complex organic systems in a planetary environment over a long time scale. With the Cassini-Huygens mission NASA and ESA will jointly send an orbiter (Cassini) around Saturn and a probe (Huygens) in the atmosphere of Titan. This mission, currently planned to be launched in 1996-1997 for a Saturn - Titan arrival in 2004, offers a unique opportunity to study in detail extra-terrestrial organic processes. Consequently, it has important implications in the field of exobiology and the origins of life.     

Tonic vibration reflexes and background force level

On Earth, the functional stretch reflex is an important component in the maintenance of posture and muscle tone. In parabolic flight experiments, we evaluated whether the functional stretch reflex, as reflected in the tonic vibration reflex, adjusts appropriately for changes in background gravitoinertial force level. Virtually immediate alterations of appropriate sign occurred.     

用静磁表面波延迟线构成振荡器

本文介绍利用外延钇铁石榴石(以下简称YIG)膜的静磁表面波构成静磁表面波延迟线振荡器的实验研究。通过“提升”换能器的应用,得到了一种压缩延迟线带宽的新方法。我们发现,单模工作的调谐范围主要受延迟线外部电路电长度的限制。外部电长度每改变360°,延迟线上就出现频率跃变。已经得到的最大调谐范围大约为600兆赫。这个范围主要受所用的AVANTEK砷化镓场效应晶体管放大器的限制,该放大器的电长度大致等效于45厘米的空气传输线。结论是,如果外部电路的电长度能尽量缩短(理想地做到O),就可能在一个倍频程或更宽频带内实现单模工作。     

数字频率合成的新途径

本文介绍了从1Hz到399999Hz以1Hz步进频率合成新技术。合成的波形是对称方波,与晶体管—晶体管逻辑(TTL)相容。它所使用的合成算法为高效率使用系统的数字式仪器创造了条件。整套设备是由一个输入装置、一个BCD/二进制转换器、一个二进制分频器、一个数字式比较器和一个锁相环(PLL)倍频器组成。     

A PREDICTION OF THE VORTEX-RING STATE BOUNDARY BASED ON MODEL TESTS

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THE DIFFUSION BONDING OF Ti－6AI－4V TITANIUM ALLOY UNDER SUPERPLASTIC CONDITION

ＴＨＥＤＩＦＦＵＳＩＯＮＢＯＮＤＩＮＧＯＦＴｉ－６ＡＩ－４ＶＴＩＴＡＮＩＵＭＡＬＬＯＹＵＮＤＥＲＳＵＰＥＲＰＬＡＳＴＩＣＣＯＮＤＩＴＩＯＮ￥ＺｈａｎｇＺｈｏｎｇｙｕａｎ；ＣａｉＣｈｅｎｇｈｅ；ＬｉｎＺｈａｏｒｏｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａ...     

LARGE-EDDY SIMULATIONS OF TURBULENT CAVITY FLOWS WITH DYNAMIC SGS MODEL AND LBM ALGORITHM

INTRODUCTIONLarge- eddy simulation ( LES) method is apowerfull tool in numerical simulations of turbu-lence. On the other hand,lattice Boltzmannmethod( LBM) is a new method in computationalfluid dynamics ( CFD) ,especially when used inlarge scale parallel applications.Therefore it isuseful to build the dynamic SGS model intoLBM.In this paper the new method of dynamicSGS model with LBM is described in detail andsome results using the method to numericallysimulate the two and three…     

A NOVEL INTEGRATED OPTICS MIORODISPLACEMENT SENSOR

ＡＮＯＶＥＬＩＮＴＥＧＲＡＴＥＤＯＰＴＩＣＳＭＩＯＲＯＤＩＳＰＬＡＣＥＭＥＮＴＳＥＮＳＯＲ￥ＷａｎｇＨｕｍａｎ（ＤｅｐａｒｔｍｅｎｔｏｆＡｕｔｏｍａｔｉｃＣｏｎｔｒｏｌ，ＮＵＡＡ２９ＹｕｄａｏＳｔｒｅｅｔ，Ｎａｎｊｉｎｇ２１００１６，Ｐ．Ｒ．Ｃｈｉｎ...     

VARIABLE STRUCTURE MODEL－FOLLOWING ADAPTIVE CONTROL DESIGN FOR ROBOT MANIPULATORS

ＶＡＲＩＡＢＬＥＳＴＲＵＣＴＵＲＥＭＯＤＥＬ－ＦＯＬＬＯＷＩＮＧＡＤＡＰＴＩＶＥＣＯＮＴＲＯＬＤＥＳＩＧＮＦＯＲＲＯＢＯＴＭＡＮＩＰＵＬＡＴＯＲＳＺｈａｏＤｏｎｇｂｉａｏ；ＺｈｕＪｉａｎｙｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃａｌＥｎｇｉｎ...