Bioconversion systems for food and water on long term space missions

An imperative for prolonged Space flight missions is the conservation of resources. Extensive resupply could pose technological and logistical challenges for those responsible for the management and successful completion of the mission. Therefore, the biological waste water reclamation system (BWWR) which requires little or no expendable supplies and the waste cellulose to edible mushroom conversion system (CMCS) which is conceived as a low energy crop waste recycling system are prototype instruments which have been conceived as solutions to the mission resupply problem. Out tests, conducted with relatively crude devices based on the original concepts, indicate that further research on the basic principles underlying the systems and refinement of the engineering designs will lead to hardware with the potential to satisfy the requirement for minimal re-supply while providing recycled water and edible mushrooms.     

Natural killer cells after ALTAIR mission

Reduced in vitro NK cytotoxic activity have routinely been observed after both prolonged and short-term space flights. This study investigated the effects of space flight on NK cell functions, NK cell counts and the production of IL-2 and TNF by lymphocytes of French-Russian crew members. In the French cosmonaut, after 21 days space flight, the cytotoxic activity of NK cells, the capacity the NK cells to bind and lyse the individual target cells and the percentage of NK cells were decreased. In this cosmonaut a twofold reduction TNF production in cultures of lymphocytes stimulated with PMA and with the mixture of PHA and PMA was observed on the first day after landing. However, the activity of the production of TNF in 48-hour PHA-cultures of lymphocytes was unchanged and the biological activity of IL-2 was not reduced. The immunological examination did not detecte any substantial deviations from the norm in both russian cosmonauts after 197 days space flight. Various explanations for decreased cytotoxicity in cosmonauts after space flight can be proposed, and these include the defective function of NK cells and reduced numbers of circulating effector cells.     

As assessment of habitat pressure, oxygen fraction, and EVA suit design for space operations

At high cabin pressure [e.g. 1013 hPa (14.7 psi) 21% O2] there are serious issues relative to specification of suit pressure and the need for prebreathing. A high pressure suit will be costly but use of the existing, flexible suit requires up to 6 h of prebreathing. Or one could use a cabin pressure of 700 hPa (10.2 psi) prior to extravehicular activity (EVA) in order to use the existing suit with only 1 h of prebreathing. If these normal cabin pressures and O2 levels are utilized, existing physiological and medical databases apply, providing a known basis for evaluating effects of long duration space missions. If a 345 hPa (5 psi), 70-100% O2 atmosphere is adopted the existing suit can be used with no prebreathing required. However, there is no reference database on physiological effects under the conditions of lower pressure and higher O2 concentration. This paper considers the major issues involved in defining habitat pressure, O2 fraction, and EVA suit design for operations in space. A preliminary model for evaluating habitat/suit pressure and O2% strategies is presented.     

XilinxFPGA／CPLD器件的正确选择

介绍了现场可编程门阵列FPGA器件及相应设计软件的市场调研结果,提出了选择FPGA器件的一般规则,并结合实际应用给出了Xilinx FPGA器件的选择方法。     

Modern and ancient extremely acid saline deposits: terrestrial analogs for martian environments?

Extremely acid (pH <1) saline lakes and groundwaters existed in the mid-Permian of the mid-continent of North America. Modern counterparts have been found in acid saline lake systems throughout southern Australia. We compare and contrast the Permian Opeche Shale of North Dakota and Nippewalla Group of Kansas to modern Australian salt lakes in southern Western Australia and in northwest Victoria. With the exception of some minor variations in pH, evaporite mineralogy, and water geochemistry, the Permian and modern systems are similar and characterized by: (1) ephemeral saline continental playas hosted by red siliciclastic sediments, (2) evaporite minerals, including abundant sulfates, (3) Al-Fe-Si-rich waters with low pH values, (4) acidophilic microbes, and (5) paucity of carbonates. The composition of these terrestrial systems is strikingly similar to compositional data returned from the martian surface. Specifically, both Earth and martian systems have high amounts of iron oxides and sulfates, and little, if any, carbonates. We propose that the modern and ancient terrestrial acid saline environments may be good analogs for possible environments on Mars.     

磷酸掺杂型高温质子交换膜燃料电池关键材料研究进展

高温质子交换膜燃料电池(HT-PEMFC)由于较高的工作温度(130~220℃),具有较快的电极反应动力学、较强的抗燃料/空气中杂质毒化能力、广泛的燃料来源(甲醇重整气、工业副产氢等)及简单的水/热管理系统等优点。因此,HT-PEMFC将成为聚合物膜燃料电池的重要前沿发展方向之一。重点介绍了北京航空航天大学团队近十年来在HT-PEMFC关键材料-高温膜、催化层和膜电极等方面的研究进展,针对磷酸(PA)掺杂型高温膜的质子传导率和机械性能之间的最佳平衡点、催化层中PA分布和迁移对电池性能的影响机制,以及大尺寸膜电极一致性对电堆性能影响与衰减机制等科学问题,从聚电解质膜材料的分子设计、有序催化层结构调控和大尺寸膜电极电堆优化等工作进行了梳理,对HT-PEMFC技术所面临的技术挑战问题与未来发展趋势做出了评述和展望。      

薄壁机匣铣削加工颤振抑制研究

薄壁类工件由于其刚性较差,在铣削过程中相对于厚壁工件来说更易产生振动,因此需要采取一些措施来抑制颤振。从调谐质量阻尼器(TMD)的吸振原理出发,根据有限元分析和模态试验结果设计了抑振辅助夹具。所设计的辅助夹具不需要额外的动力装置、结构简单、易安装、灵活方便且适用性广。试验结果表明,采用抑振夹具后,机匣零件铣削过程中系统的低阶振动幅值降低了90%,高阶振动幅值降低了70%,刀具和工件的耦合振动幅值降低了80%。