Application of the mechanical oscillator technique to the investigation of EVA decompression

The ultrasonic bubble detection technique has been used as a versatile tool in the investigation of hypobaric decompression procedures for the last two decades. However, this method can only detect relatively large bubbles > 30-50 micrometers (usually in venous blood) and not the very first stages of bubble formation. Recently, the mechanical oscillator technique has been applied in air diving trials in order to detect small blood density changes due to hypothetical fluid shifts. However, sharp density drops were found in the decompression process, and these have been attributed to gas bubble formation. In this study, this method was applied together with Doppler controls to a series of altitude decompressions to 300 and 500 hPa, which represents the range of EVA operational pressures currently used or planned. Six subjects participated in both series; the oscillator sample tube could be pressurized. By the application of pressure on a blood sample containing questionable gas bubbles, these are reduced in volume, like in recompression therapy, and thus the density of the sample is increased. This effect has been shown in all 6 subjects undergoing decompression to 300 hPa, whereas in the 500 hPa series only 3 out of 6 subjects corresponded with gas phase formation immediately after decompression. Typically, Doppler bubbles appeared only after some latency time between 20 and 60 min; after this time, the density effect had nearly vanished. It is concluded that the mechanical oscillator technique represents a complementary research instrument to the Doppler method, because it is able to deliver a quantitative resolution of the early stage of gas phase formation.     

CASH 2021: commercial access and space habitation

Issues about commercialization of space have been a growing concern in the past decade for the space community. This paper focuses on the work from a team of 51 students attending the Summer Session Program of the International Space University in Bremen, Germany. CASH 2021 (Commercial Access and Space Habitation) documents a plan that identifies commercial opportunities for space utilization that will extend human presence in space, and will chart the way forward for the next 20 years. The group selected four commercial sectors that show the most promise for the future: tourism, entertainment, space system service, assembly and debris removal, and research and development/production. The content of this document presents the results of their research. Historical activities in each of the commercial sectors are reviewed along with the current market situation. To provide a coherent background for future commercialization possibilities a scenario has been developed. This scenario includes a postulated upon ideal future and includes social, political and economic factors that may affect the space industry over the timeline of the study. The study also presents a roadmap, within the limited optimistic scenario developed, for the successful commercialization of space leading to future human presence in space. A broad range of commercially viable opportunities, not only within the current limits of the International Space Station, but also among the many new developments that are expected by 2021 are discussed.     

Results of space experiment program "Interferon"

The results of the biological space experiment "Interferon" performed by two international cosmonaut teams (26 May 1980, and 16 May 1981) aboard space laboratory Solyut-6 are reported: (1) Human lymphocytes separated from blood of healthy donors and placed into "Interferon I" equipment could be kept for 7 days in suspension culture under spaceflight conditions. Interferon production could be induced in human lymphocytes by preparations of different origin: virus, synthetic polyribonucleotides, bacterial protein and plant pigment. An increased lymphocyte interferon production in space laboratory compared to ground control was observed. (2) Human interferon preparations and interferon inducers placed in space laboratory at room temperature for 7 days maintained their biological activity. (3) A decrease of induced interferon production and natural killer activity of lymphocytes isolated from peripheral blood of cosmonauts was observed on the 1st day on Earth after 7-days spaceflight.     

整体构件周向叶片电解加工流场设计及实验

针对整体构件周向叶片的特点与加工难点,设计了带有内置绝缘腔的电解套型加工工具阴极,建立了两种进液方式的流场三维模型,采用有限元法对两种进液方式的流场进行仿真计算。计算结果表明由绝缘腔的叶盆叶背两侧进液并对出液口进行优化的流场方式较好,电解液流速较高且流场较均匀。使用根据有限元仿真结果设计的阴极开展实验,结果表明实验与流场仿真结果相符,采用优化流场模型的加工过程流场稳定,加工效率较高。     

基于非结构自适应网格和嵌入边界法的残差格式研究

嵌入边界法由于在求解NS方程时能够简化网格生成问题而在计算流体领域受到越来越广泛的关注.简言之,嵌入边界法能够简化大变形和运动条件下多物理流动模拟、流固相互作用耦合问题,然而壁面边界条件的精确处理仍旧是该方法需要解决的问题.在本文工作中,为考虑壁面边界条件而在NS方程中增加了补偿项,同时采用非结构网格自适应技术保持了壁面边界条件的精度.     

基于目标机动新模型的被动寻的导弹制导律

假设某些目标能作正交于其速度矢量的规避机动,提出一种新的随机动态目标模型.利用增益修正广义卡尔曼滤波器来估计目标状态和在线建立目标机动的角速率.推导出可使二次型性能指标极小化的制导律,对于二维的只有角测量的情况,数值仿真表明,所提出的目标模型会使目标状态的估计得到明显的改进.此外,还给出采用这种新制导方法对终端脱靶距离的影响,并与高斯-马尔可夫模型作了比较.     

靶场标准化及自动化计划第二阶段

一、靶场背景 美国主要的航天发射场,包括东靶场(位于弗罗里达州卡纳维拉尔角)和西靶场(位于加利福尼亚州范登堡空军基地)起源于50年代,在随后的几十年内进行了逐步扩展和改进。直到前不久移交给空军空间司令部时,这些靶场才更多地用作研究和开发单位,而不只是操作运行单位。逐步改造使它们具备了支持发射新型航天器、弹道导弹以及逐步发展起来的     

“脑资源”枯竭 美国航宇公司人才告急

AVIATIONWEEK》》&SPACETECHNOLOGYBrainDrainThreatensAerospaceVitality高级工程人员的短缺正在严重削弱美国航空界的活力，这种情况短期内难以得到解决美国航字工业正在面临一个越来越严重的问题，可以说是一个危机，而且按照一些资深观察家的观点，这种情况还看不到什么时候可以得到改善的迹象。这个危机被称为‘脑资源枯竭”，又称为“智力外流”。随着新兴电子商务公司的不断涌现，如何吸引高技术人才以及留住高智商技术人员已越来越困难，特别在一些关键的行业，如电子、软件和系统工程等更是突出，人才短缺已经对工业…     

欧洲空间操作中心的精密轨道确定

目前,欧洲空间操作中心正在进行着一项需4年时间的开发计划,以支持未来的需要高精度轨道确定的ESA近地飞行任务。该工作是围绕着欧洲空间操作中心已开发的供轨道确定和误差分析用的一个软件系统进行的,该软件含有适合于各种轨道摄动和测量类型的先进模型。除了卫星轨道参数外,它还能对地球物理参数和测地参数进行估计和误差分析。     

Recent SETI observations at Arecibo

During 1980 and 1981, the 305-m radio telescope at the Arecibo Observatory in Puerto Rico was used to conduct a high resolution search for narrowband signals from the direction of 210 nearby solar type stars and 5 OH masers. For each star at least 4 MHz of bandwidth surrounding the 21-cm HI line and/or the 18-cm OH lines was studied with a spectral resolution of 5.5 Hz in both right and left circular polarization. The formal limit of sensitivity achieved during the course of this search varied depending upon the particular receivers available. In all cases the search could have detected a narrowband transmitter of power comparable to the Arecibo planetary radar, had any such been transmitting on the frequencies searched during the time of observation out to the distance of the farthest target star. As in previous searches, the number of "false alarms" encountered was far greater than predicted on the basis of Gaussian noise statistics. A small number of stars have exhibited signals which cannot immediately be explained in terms of astrophysical or man-made sources and deserve reobservation. This is typical of the results of previous non-real-time searches and does not yet constitute the detection of an ETI.