Control in the cockpit: crews vs. computers

In the no-holds-barred competition between Boeing and Europe's Airbus Industrie for dominance in the world's commercial jet airliner markets, the question of who--or what--is in charge in the cockpit has been a significant selling point. Airbus, which pioneered highly automated flight controls with its A320 narrow-body transport in the late 1980s, likes to emphasize the "protection" features built into the aircraft through those automated systems. Boeing, which employs many of the same concepts in its new 777 twin-engine widebody transport, tends to put more emphasis on crew involvement in the operation of that aircraft. Is there a difference? In fact, the question has broader implications than those involving the marketing battle between Boeing and Airbus. Airlines, aircraft manufacturers, flight training specialists, human factors gurus, and aviation authorities in various countries are struggling with the isse as automation becomes more and more prevalent on passenger and cargo-carrying aircraft around the world.     

Blood volume regulating hormones, fluid and electrolyte modifications during 21 and 198-day space flights (Altair-MIR 1993)

During the Altair MIR' 93 mission we studied several parameters involved in blood volume regulation. The experiment was done on two cosmonauts before (B-60, B-30), during (D6, D12, D18 for French and D7, D12, D17 for Russian) and after the flight (R+1, R+3 and R+7). Space flight durations were different for two cosmonauts: for the Russian the flight duration was 198 days and for the French 21 days. On board the MIR station only urinary (volume and electrolytes, atrial natriuretic peptide (ANP), cyclic guanosine monophosphate (cGMP) and catecholamines) and salivary (cGMP and cortisol) samples were collected, centrifuged and stored in freezer. Lithium was used as a tracer to know exactly the 24 h urine output (CNES urine collection Kit). Before and after flight, blood was drawn with an epicite needle and vacutainer system for hormonal assays (renin, antidiuretic hormone, cGMP, ANP and aldosterone) in two positions: after 30 min rest in upright seated position and after 90 min of supine position. Salivary samples were collected simultaneously. During flight a decrease of diuresis and ANP and an increase of osmolality were found. No modifications of hematocrit, but an increase of salivary cGMP and cortisol were also observed. The decrease of urinary ANP is in favor of hypovolemia as described in previous flights. The postflight examinations revealed changes in fluid-electrolyte metabolism which indicate a hypohydration status and a stimulation of hormonal system responsible for water and electrolyte retention in order to readapt to the normal gravity.     

用声表面波传感器进行压力和温度测量

本文介绍两种不同的声表面波传感器,即弱压压力传感器和声表面波温度传感器。压力传感器制作在一薄的石英晶片上,使两束表面弹性波在同一方向但在两个不同的侧向位置上传播。加在下表面上的压力的变化引起强烈的弯曲,从而改变两波的波速。采用差动检测法能够测出波速的变化(或者相应振荡器的频率偏移),同时也能够人大地消除因温度波动所引起的假速度(或频率)的变化。通过计算应变分布和相应频率漂移来得出石英薄片上声表面波延迟线具有最大压力灵敏度,而温度影响最小的两位置。把Y切割的理论结果与在105MHz取得的测帚结果进行了比较, 用具有LST和JCL晶向的石英片制作的温度传感器已在灵敏度(28ppm/K)、线性、响应时间(0.1S)和分辨力(50μK)方面进行了测试。将用表面波温度传感器取得的温度测量结果与用体波温度传感器(LC切)所测得的结果进行比较,提出一种采用声表面波温度探头的新型石英温度计。     

VARIABLE STRUCTURE MODEL－FOLLOWING ADAPTIVE CONTROL DESIGN FOR ROBOT MANIPULATORS

ＶＡＲＩＡＢＬＥＳＴＲＵＣＴＵＲＥＭＯＤＥＬ－ＦＯＬＬＯＷＩＮＧＡＤＡＰＴＩＶＥＣＯＮＴＲＯＬＤＥＳＩＧＮＦＯＲＲＯＢＯＴＭＡＮＩＰＵＬＡＴＯＲＳＺｈａｏＤｏｎｇｂｉａｏ；ＺｈｕＪｉａｎｙｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃａｌＥｎｇｉｎ...     

FAST SOLUTION OF TURBULENT SEPARATION BY STRAWN''''S METHOD

ＦＡＳＴＳＯＬＵＴＩＯＮＯＦＴＵＲＢＵＬＥＮＴＳＥＰＡＲＡＴＩＯＮＢＹＳＴＲＡＷ＇ＳＭＥＴＨＯＤＹｉｎＪｕｎｆｅｉ（ＤｅｐａｒｔｍｅｎｔｏｆＰｏｗｅｒＥｎｇｉｎｅｅｒｉｎｇ，ＮＵＡＡ２９ＹｕｄａｏＳｔｒｅｅｔ，Ｎａｎｊｉｎｇ２１００１６，Ｐ．Ｒ．Ｃｈ...     

BUCKLING ANALYSIS OF POLAR ORTHOTROPIC ANNULAR PLATES UNDER UNIFORM PRESSURES

ＢＵＣＫＬＩＮＧＡＮＡＬＹＳＩＳＯＦＰＯＬＡＲＯＲＴＨＯＴＲＯＰＩＣＡＮＮＵＬＡＲＰＬＡＴＥＳＵＮＤＥＲＵＮＩＦＯＲＭＰＲＥＳＳＵＲＥＳＹｏｕＲｅｎｃｈａｎ；ＷａｎｇＹｏｎｇｌｉａｎｇ；ＷａｎｇＸｉｎｗｅｉ（ＤｅｐａｒｔｍｅｎｔｏｆＡｉｒｃｒａｆｔＥ...     

DATA MODEL FOR MULTIMEDIA DATABASE SYSTEM NHMDB BASED ON NF~2 DATA MODEL

ＤＡＴＡＭＯＤＥＬＦＯＲＭＵＬＴＩＭＥＤＩＡＤＡＴＡＢＡＳＥＳＹＳＴＥＭＮＨＭＤＢＢＡＳＥＤＯＮＮＦ~２ＤＡＴＡＭＯＤＥＬ￥ＧｕｏＨｏｎｇｙｉｎｇ；ＬｉｎＪｕｎｈａｉ；ＴｉａｎＣａｎｇｈａｉ（ＤｅｐａｒｔｍｅｎｔｏｆＣｏｍｐｒｔｅｒＳｃｉｅｎｃｅａｎ?..     

GHOST FLUID METHOD FOR RICHTMYER-MESHKOV INSTABILITY SIMULATION

INTRODUCTIONThe energy of the Richtmyer- Meshkov in-stability is excited by the interaction between ashock wave and a contact interface across thatfluids are different.Itis very important thatcap-ture the interface in multi- material flows exact-ly.Here we will apply the ghost fluid method tosimulate two dimensional Richtmyer- Meshkovinstability.The mathematical equation used to simulatethe Ritchmyer- Meshkov instability is the com-pressible Euler equation for two ideal gases.ρρuρvE…     

长期时效对铌合金C-103,Cb-lZr,Cb-752和钼合金Mo-TZM塑性的影响

铌合金和钼合金在空间动力系统中具有潜在的用途。因此,安排了一计划测定在这些合金中是否发生时效脆性,也测定了铌合金的时效脆性是否取决于合金成分。研究的合金包括主要在现代空间动力系统结构应用中选用的C-103,加上备用的Cb-lZr合金。研究中也包括了Cb-752和钼合金Mo-TZM。合金试样在700°—1025℃范围内五个温度下时效1000小时。弯曲塑脆性转变温度和金相特征描述作为主要的评价方法。时效试样随后掺以氢也以弯曲试验来确定时效是否增加铌和钼合金对氢脆的敏感性。结果表明,C-103铌合金对时效脆性是不敏感的。试样在时效条件下,甚至在掺有氢的情况下,显示出一个低于-196℃的塑脆性转变温度。Cb-lZr和Mo-TZM合金也不显示出时效脆性。然而,与未掺氢的时效材料的塑脆性转变温度(低于-196℃)相比,时效的Cb-lZr试样的掺氢使塑脆性转变温度增加到-100℃。时效的Mo-TZM合金不会被氢所掺杂。相反地说,在900℃长期时效的Cb-752合金产生某些时效脆性。这由塑脆性转变温度的增加(从低于-196℃到大约-150℃)来表明。脆性可归因于在此合金中的添加溶质钨和锆的临界成份。光学显微镜检查表明,在时效期间,锆在晶界上发生偏析。此偏析导致随后的沿晶界的脆性断裂。Cb—752合金也对氢脆敏感。掺有约40ppm氢的退火和时效试样具有高于室温的转变温度。