A novel environmental control system based on membrane dehumidification

This paper conducts a simulation study of a novel aircraft environmental control system based on membrane dehumidification(MD-ECS),and compares the system with the up-to-date four-wheel high pressure de-water system(4WHPDW-ECS).Mathematical models for the two systems are established,and a system simulation using a numerical technique is performed to analyze and compare the cooling performance of the two systems.Simulation results show that the cooling capacity of MD-ECS is much higher than that of 4WHPDW-ECS under the same working conditions,indicating that the novel system is theoretically feasible and promising.The effects of the sweep ratio of the membrane dehumidifier on the dehumidification and cooling performance of the system is also investigated.     

Comparison of model and experimental ionospheric parameters at high latitudes

Modern use and study of the auroral region needs to attract a wider class of models for describing conditions of radio wave propagation in the ionosphere. In this paper the possibilities of the International Reference Ionosphere model, well-proven and widespread in the mid-latitudes, are investigated in the high latitude zone. Model and measured values of the critical frequency foF2 for two mid-latitude stations (Juliusruh and Goosebay) and four high-latitude ones (Loparskaya, Sodankyla, Sondrestrom, Thule) are compared. Deviations of medians, variations from day to day and solar activity trends seemed to be similar for both areas. This similarity is irrespective of the RZ12 index. Special attention is paid to the TEC parameter and its determination using 6 versions of models, a new version of the model IRI2010 (IRI-Plas) among them. It is shown that the IRI-Plas model significantly improves the definition of TEC in contrast to the versions of IRI2007 and the new model NeQuick. The use of the median of the experimental equivalent slab thickness, together with the current values of the TEC, increases by a factor of two the agreement between calculated and measured foF2 values as compared with the variations from day to day. This allows foF2 to be defined in near-real time.     

球载高能天文望远镜的超视距自动跟踪

本文在HAPI-4原有系统的基础上，利用80C196超16位单片机，首次实现了球载姿态指向控制系统的数字化；借助于全球卫星定位系统GPS，实现了气球位置的高精度定位和时间的绝对定标；采用小型高密度磁带机作为球载数据流存储器，利用海事卫星实现超视距测控，形成了新一代的球载高能望远镜控制系统．     

Bacterial survival in response to desiccation and high humidity at above zero and subzero temperatures

Earthly microorganisms might have contaminated Mars for millions of years by intellectual activities or natural transfer. Knowledge on the preservation of microorganisms may help our searching for life on outer planets, particularly Mars-contaminated earthly microorganisms at ancient time. Extreme dryness is one of the current Mars characteristics. However, a humid or watery Mars at earlier time was suggested by evidence accumulated in recent decades. It raises the question that whether water helps preservation of the microorganisms or not, particularly those with high possibility of interplanetary transfer like spores and Deinococci. In this study, we examined the effects of desiccation and high humidity on survival and DNA double strand breaks (DSB) of Escherichia coli, Deinococcus radiodurans and spores of Bacillus pumilus at 25, 4 and −70 °C. They exhibited different survival rates and DSB patterns under desiccation and high humidity. Higher survival and less DSB occurred at lower temperature. We suggest that some Mars-contaminated bacteria might have been viably preserved on cold Mars regions for long periods, regardless of water availability. It is more likely to find ancient spores than ancient Deinococci on Mars. In our search for preserved extraterrestrial life, priority should be given to the Mars Polar Regions.     

Scientific requirements for future spatially resolved white-light and broad-band high-cadence observations of the Sun

Several important issues are open in the field of solar variability and they wait their solution which up to now was attempted using critical ground-based instrumentations. However, accurate photometric data are attainable only from space. New observational material should be collected with high enough spatial and spectral resolution, covering the whole visible range of the electromagnetic spectrum as well infrared and ultraviolet to reconstruct the total solar irradiance: (1) the absolute contributions of different small-scale structural entities of the solar atmosphere from the white light flares and from micro-flares are still poorly known; (2) we do not know the absolute contributions of different structural elements of the solar atmosphere to the long-term and to the cyclic variations of the solar irradiance, including features of the polar regions of the Sun; (3) the variations of the chromospheric magnetic network are still poorly evaluated; (4) only scarce information is available about the spectral variations of different small-scale features in the high photosphere. Variability of the Sun in white light can be studied with higher spectral, spatial and time resolution using space-born telescopes, which are more appropriate for this purpose than ground based observatories because of better seeing conditions, no interference of the terrestrial atmosphere and a more precise calibration procedure. Scientific requirements for such observations and the possible experimental tools proposed for their solution. Suggested solar studies have broader astrophysical importance.     

Cosmic rays at High Mountain Observatories

The worldwide distribution of High Mountain Observatories provides a unique opportunity for performing contemporary measurements under different geomagnetic/altitude conditions and for collecting long-term data series. In this context, the history and some activities performed at two historical Research Stations are summarized: Chacaltaya Laboratory (Bolivia) and the Testa Grigia Research Station (Italy).     

提高UV-LIGA制备金微细零件的尺寸精度研究(英文)

在众多影响UV-LIGA(Ultra-violet lithography Galvanik abformung)技术制备微细金属零件尺寸精度的因素中,SU-8胶溶胀性是最主要的。通常采用隔离带方法降低SU-8胶的溶胀性,以提高电铸微细零件的尺寸精度。由于贵重金属会沉积到隔离带内,造成了贵重金属的浪费,增加制造成本,因此该方法不适合贵重金属微细零件制造。针对隔离带方法的弊端,提出了半隔离带方法,在保证电铸微细金属零件尺寸精度的前提下,避免了贵重金属的浪费。另外,还采用电解液喷射方法实现了高电流密度电铸,缩短了电铸时间,进一步提高了电铸微细金属零件的尺寸精度。试验结果表明:采用半隔离带方法和高电流密度,可以有效提高金微细零件的尺寸精度,当电流密度提高到0.6A/dm2,金微细零件的尺寸精度可以达到5μm。     

大尺寸测量系统配置中包络性与可达性分析

构建了包络性和可达性分析的原理与公式，定量判定当前测量设备空间位置是否合理，为实现在大尺寸测量方案规划阶段对测量设备的可行空间进行快速有效的规划提供依据。阐述了大尺寸测量系统总体架构与阶段任务划分，定义了包络性与可达性的输入输出关系。论述了包络性与可达性的原理与公式，包括可测量体素和外包络体的定义、数学模型和推导公式以及判定公式。最后，在CATIA环境下开发包络性和可达性分析工具，并以机翼翼肋为例，对该翼肋上待测关键特征进行包络性和可达性仿真分析。仿真结果表明，该包络性与可达性分析的原理与公式是可行的。     

时序信号设计的一种新方法

文章结合高速时序工作的特点，从实现的角度提出了一种利用软件调整时序的新方法。在可编程逻辑器件中，利用数字时钟管理器（DCM），通过模块化和增量式设计思想达到对高速时序信号的精确调节。最终实现了一个20MHz速率的时序控制，调节精度达到100ps。     

Is there an instrumental drift in the counting rate of some high latitude neutron monitors?

For the last six decades the neutron monitors have provided a continuous string of very reliable data to the heliophysics community. Although neutron monitors are not the primary source of data for the galactic cosmic rays, these data serve as a baseline reference for the data collected by the detectors on board the satellites and deep space probes, far away from earth orbit. The pressure corrected hourly data are available from the World Data Centers. These data have been used to derive deep insights pertaining to the electromagnetic states of the heliosphere and the modes of transport of energetic charged particles in the tangled interplanetary magnetic fields. We present evidence that some of the high latitude neutron monitors are undergoing long-term drifts in their baselines. In particular, we argue that there is no physical basis to justify the observed long-term downward trend in the baseline of the South Pole neutron monitor. The real reason may have to do with its maintenance at a distant location with challenging logistics and an improper normalization of its data after the 26 months break in the 1970s.