多胞局域共振型超材料的减振实验研究

弹性波/声波超材料具有许多超常力学性质,为航空、航天和船舶等领域的装备减振降噪提供了新途径。本文介绍多胞局域共振型超材料的减振实验研究。该研究基于局域共振元胞的频散分析、波动传递率分析和周期结构的振动响应计算,讨论了超材料在带隙频率区内外的波动传播。设计制造了具有低频带隙的轻质周期性局域共振超材料构型,并用于空间桁架结构的振动抑制实验。实验结果表明,在15～45 Hz的带隙频率区间,多胞超材料减振装置可使振动传递率降低30 dB以上,展现出良好的减振效果。     

中国空间天文40周年

过去40年中国空间天文学研究取得了巨大的发展.尤其是近10年内发射了数颗天文卫星,未来几年还将有一些天文卫星计划发射.本文简要回顾了国际空间天文学的发展历程.对中国空间天文学过去40年的发展进行了回顾和总结,包括1970年代第一颗天文卫星计划、气球空间天文探测、基于载人航天工程的空间天文实验以及天文卫星等.此外,介绍了...     

Helio-geomagnetic influence in cardiological cases

The effects of the energetic phenomena of the Sun, flares and coronal mass ejections (CMEs) on the Earth’s ionosphere–magnetosphere, through the solar wind, are the sources of the geomagnetic disturbances and storms collectively known as Space Weather. The research on the influence of Space Weather on biological and physiological systems is open. In this work we study the Space Weather   impact on Acute Coronary Syndromes (ACS) distinguishing between ST-segment elevation acute coronary syndromes (STE–ACS) and non-ST-segment elevation acute coronary syndromes (NSTE–ACS) cases. We compare detailed patient records from the 2nd Cardiologic Department of the General Hospital of Nicaea (Piraeus, Greece) with characteristics of geomagnetic storms (_DST${\mathrm{D}}_{\mathit{ST}}$), solar wind speed and statistics of flares and CMEs which cover the entire solar cycle 23 (1997–2007). Our results indicate a relationship of ACS to helio-geomagnetic activity as the maximum of the ACS cases follows closely the maximum of the solar cycle. Furthermore, within very active periods, the ratio NSTE–ACS to STE–ACS, which is almost constant during periods of low to medium activity, changes favouring the NSTE–ACS. Most of the ACS cases exhibit a high degree of association with the recovery phase of the geomagnetic storms; a smaller, yet significant, part was found associated with periods of fast solar wind without a storm.     

Verification of shielding effect by the water-filled materials for space radiation in the International Space Station using passive dosimeters

The dose reduction effects for space radiation by installation of water shielding material (“protective curtain”) of a stack board consisting of the hygienic wipes and towels have been experimentally evaluated in the International Space Station by using passive dosimeters. The averaged water thickness of the protective curtain was 6.3 g/cm². The passive dosimeters consisted of a combination of thermoluminescent detectors (TLDs) and plastic nuclear track detectors (PNTDs). Totally 12 passive dosimeter packages were installed in the Russian Service Module during late 2010. Half of the packages were located at the protective curtain surface and the other half were at the crew cabin wall behind or aside the protective curtain. The mean absorbed dose and dose equivalent rates are measured to be 327 μGy/day and 821 μSv/day for the unprotected packages and 224 μGy/day and 575 μSv/day for the protected packages, respectively. The observed dose reduction rate with protective curtain was found to be 37 ± 7% in dose equivalent, which was consistent with the calculation in the spherical water phantom by PHITS. The contributions due to low and high LET particles were found to be comparable in observed dose reduction rate. The protective curtain would be effective shielding material for not only trapped particles (several 10 MeV) but also for low energy galactic cosmic rays (several 100 MeV/n). The properly utilized protective curtain will effectively reduce the radiation dose for crew living in space station and prolong long-term mission in the future.     

面向天文观测的空间科学卫星任务规划方法研究

面向天文观测的空间科学卫星任务规划是一个复杂的多目标优化问题.通过对天文观测类卫星的任务规划要素及约束条件进行抽象,建立了面向天文观测的多目标任务规划问题模型,在此基础上设计了基于NSGA-II的多目标观测任务规划算法,并通过实例进行了实验及结果分析.研究表明,该方法能够有效解决天文观测类卫星不同规模的任务规划问题.      

Electric discharge in the Martian atmosphere,Paschen curves and implications for future missions

Electric discharge between two electrically charged surfaces occurs at a well-defined, gas-dependent combination of atmospheric pressure and the distance between those two surfaces, as described by Paschen’s law. The understanding of when the discharge will occur in the conditions present on Mars is essential for designing space-flight hardware that will operate on the Martian surface as well as understanding electrical discharge processes occurring in the Martian atmosphere. Here, we present experimentally measured Paschen curves for a gas mixture representative of the Martian atmosphere and compare our results to breakdown voltages of carbon dioxide, nitrogen, and helium as measured with our system and from the literature. We will discuss possible implications for instrument development as well as implications for processes in the Martian atmosphere. The DC voltage at which electric discharge occurred between two stainless steel spheres was measured at pressures from 10⁻² to 100 torr in all gases. We measured a minimum voltage for discharge in the Mars ambient atmosphere of 410 ± 10 V at 0.3 torr cm. As an application, the breakdown properties of space-qualified, electrical wires to be used in the Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) were studied.     

月球表面太空风化作用及其效应

太空风化作用普遍发生在月球、小行星等一些无大气层的天体表面, 主要包括太阳风离子辐射和微陨石撞击等作用. 通过对真实月球样品太空风化作用的研究成果以及低能离子和激光照射等地面模拟实验结果的系统综述和分析, 重点分析了月壤颗粒中非晶质层和纳米铁的成因, 指出太空风化研究中存在的太阳风离子辐射和微陨石撞击贡献难以区分及模拟实验模拟效果尚不充分的问题.进而提出月球太空风化研究不能简单套用其他天体的模型, 并建议未来开展更多月球和陨石样品的精细化学分析.      

Miniaturized laser-induced plasma spectrometry for planetary in situ analysis – The case for Jupiter’s moon Europa

Jupiter’s icy moon Europa is one of most promising places in our Solar System where possible extraterrestrial life forms could exist either in the past or even presently. The Europa Lander mission, an exciting part of the international Europa Jupiter System Mission (EJSM/Laplace), considers in situ planetary exploration of the moon. The distance of Europa from the Earth and the Sun asks for autonomous analytical tools that maximize the scientific return at minimal resources, demanding new experimental concepts. We propose a novel instrument, based on the atomic spectroscopy of laser generated plasmas for the elemental analysis of Europa’s surface materials as far as it is in reach of the lander for example by a robotic arm or a mole, or just onboard the lander. The technique of laser-induced plasma spectrometry provides quantitative elemental analysis of all major and many trace elements. It is a fast technique, i.e. an analysis can be performed in a few seconds, which can be applied to many different types of material such as ice, dust or rocks and it does not require any sample preparation. The sensitivity is in the range of tens of ppm and high lateral resolution, down to 50 μm, is feasible. In addition, it provides the potential of depth profiling, up to 2 mm in rock material and up to a few cm in more transparent icy matrices. Key components of the instrument are presently developed in Germany for planetary in situ missions. This development program is accompanied by an in-depth methodical investigation of this technique under planetary environmental conditions.     

Leaf proteomic analysis of three rice heritable mutants after seed space flight

To explore the proteomic changes of heritable variant rice plants induced by space environment, three mutants were selected after seed space flight by comparing the phenotypes with their on-ground controls. R955 grew more tillers and became dwarf, 971-5 acquired higher grain yield and better stress resistance, 974-5 matured earlier. Leaf proteins were extracted during the tiller development and analyzed by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). More than 300 proteins were detected as reproducible Coomassie Brilliant Blue stained spots with pI values from around 4.0 to 7.0. Five proteins that changed significantly over the controls were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). The main functions of these proteins were photosynthesis, stress defense and metabolism including RuBisCO activase, glycine rich RNA binding protein, peroxidase, triosephosphate isomerase and phosphoenolpyruvate carboxylase, which might be probably associated with the altered phenotypes. Quantitative analyses were also applied: less total protein spots and more down-regulated protein spots were detected in the mutants, indicating there might be a major loss of protein in heritable variant rice plants after seed space flight. These results may provide new insights to understand the biological effects of space environment to rice.     

空间科学实验地面支持系统平台

相对于其他空间任务, 空间科学实验具有用户分散、实验进程控制 (遥科学实验)要求实时或准实时、多种类型空间科学数据处理要求等特点. 针对空间科学实验的特点和对地面支持系统的要求, 结合实践八号卫星(SJ-8)、探测双星(TC-1, TC-2) 和神舟系列飞船(SZ) 的空间科学实验地面支持系统的任务完成情况, 以及未来空间科学实验任务的需求, 提出了地面支持系统平台的构架设想. 该系统平台支持空间科学实验的状态监视与控制, 支持遥科学实验, 能够支持空间科学实验数据标准产品的定制处理, 满足空间科学实验多任务的要求, 具有通用性和可扩展性.