Psychomotor performance during a 28 day head-down tilt with and without lower body negative pressure

Several factors may affect psychomotor performance in space: sensory-motor changes, sleep disturbances, psychological modifications induced by the social isolation and confinement. However, psychomotor performance is difficult to assess. A battery of standardized and computerized tests, so-called "Automated Portable Test System" (APTS) was devised to ascertain the cognitive, perceptive and motor abilities and their possible fluctuations according to environmental effects. Antiorthostatic bedrest, often used to simulate weightlessness, (particularly cardiovascular modifications) also constitutes a situation of social confinement and isolation. During two bedrest experiments (with head-down tilt of -6 degrees) of 28 days each, we intended to assess psychomotor performance of 6 males so as to determine whether: on the one hand, it could be altered by remaining in decubitus; on the other, the Lower Body Negative Pressure sessions, designed to prevent orthostatic intolerance back on Earth, could improve the performance. To accomplish this, part of the APTS tests as well as an automated perceptive attention test were performed. No downgrading of psychomotor performance was observed. On the contrary, the tasks were more accurately performed over time. In order to assess the experimental conditions on the acquisition phase, the learning curves were modelled. A beneficial effect of the LBNP sessions on simple tests involving the visual-motor coordination and attention faculties can only be regarded as a mere trend. Methods used in this experiment are also discussed.     

A novel target detection approach based on adaptive radar waveform design

To resolve problems of complicated clutter, fast-varying scenes, and low signal-clutterratio (SCR) in application of target detection on sea for space-based radar (SBR), a target detection approach based on adaptive waveform design is proposed in this paper. Firstly, complicated sea clutter is modeled as compound Gaussian process, and a target is modeled as some scatterers with Gaussian reflectivity. Secondly, every dwell duration of radar is divided into several sub-dwells. Regular linear frequency modulated pulses are transmitted at Sub-dwell 1, and the received signal at this sub-dwell is used to estimate clutter covariance matrices and pre-detection. Estimated matrices are updated at every following sub-dwell by multiple particle filtering to cope with fast-varying clutter scenes of SBR. Furthermore, waveform of every following sub-dwell is designed adaptively according to mean square optimization technique. Finally, principal component analysis and generalized likelihood ratio test is used for mitigation of colored interference and property of constant false alarm rate, respectively. Simulation results show that, considering configuration of SBR and condition of complicated clutter, 9 dB is reduced for SCR which reliable detection requires by this target detection approach. Therefore, the work in this paper can markedly improve radar detection performance for weak targets.     

Stuart Ross Taylor,Destiny or Chance; our Solar System and its Place in the Cosmos

Space Science Reviews -     

LYM-3量具研磨机装夹定位的改进

叙述了量具研磨机的结构工作原理（不含千分尺部分）以及各种参数变化对研磨的影响。对存在的问题进行了系统归类和对比分析，提出了改进方法，如单独配研磨器减少研磨行程，利用钳口铜块画刻线确定卡尺位置，找正主尺与直角尺两侧面重合而确保外量爪与滑块平行。     

Exploitation of the W-band for high capacity satellite communications

The scientific mission DAVID (Data and Video Interactive Distribution) of the Italian Space Agency (ASI) will pioneer the use of the W-band for a challenging telecommunications experiment. The unavailability of channel measurements and the technological limitations in that frequency range imply a system assessment based on channel extrapolation and a wise error control strategy. In that frame, a system approach is proposed that will allow the exploitation of the W-band for high capacity satellite communications. The results obtained through that approach in the assessment of the DAVID W-band experiment are provided and their perspectives identified and discussed.     

卫星用累积检漏法技术研究——三种定量比对校验方法分析

卫星用累积检漏技术是目前世界各国宇航工程检漏工作者较多采用的一种检漏方法，但在使用该方法时必须配备定量比对校验方法。介绍了各国常用的三种定量比对校验方法：标准漏孔比对法、定量气体浓度比对法和定量气体量比对法。对这三种校验方法进行了比较和分析，并从优点、缺点和技术含量三个方面进行了综合评估，认为累积检漏法中的氦质谱检漏仪选用定量气体浓度比对法较合理些。这种方法具有检漏时间短、检测误差小等特点。     

The W-band data collection experiment of the DAVID mission

The data collection experiment (DCE) of the scientific mission DAVID (DAta and Video Interactive Distribution) of the Italian Space Agency (ASI) will pioneer the use of the W-band for telecommunications experiments. In particular the collection of high volumes of data from remote or virtually remote sites will be achieved through the exploitation of a W-band link in a time window of a few minutes per satellite pass. The experiment will hence demonstrate the capability of the W-band channel to be used reliably for a telecommunication link. At the same time, the experiment will provide useful elements for the characterisation of the W-band channel, in order to be able to design properly future operational systems working at W-band.     

满足一等量块检定要求的接触式激光量块干涉仪

最新研制的接触式激光量块干涉仪主要用于测量一、二等量块的中心长度，其长度测量不确定度达到（0.02 0.2L)μm。文中介绍了其工作原理、测量不确定度分析，给出了量块测量的验证数据。     

Radiation-induced health effects on atmospheric flight crew members: clues for a radiation-related risk analysis.

There are few human data on low-dose-rate-radiation exposure and the consequent acute and late effects. This fact makes it difficult to assess health risks due to radiation in the space environment, especially for long-term missions. Epidemiological data on civilian flight personnel cohorts can provide information on effects due to the low-dose and low-dose rate mixed high- and low-LET radiation environment in the earth's atmosphere. The physical characteristics of the radiation environment of the atmosphere make the results of the studies of commercial flight personnel relevant to the studies of activities in space. The cooperative international effort now in progress to investigate dose reconstructions will contribute to our understanding of radiation risks for space exploration.