Integration of lessons from recent research for “Earth to Mars” life support systems

Development of reliable and robust strategies for long-term life support for planetary exploration must be built from real-time experimentation to verify and improve system components. Also critical is incorporating a range of viable options to handle potential short-term life system imbalances. This paper revisits some of the conceptual framework for a Mars base prototype which has been developed by the authors along with others previously advanced (“Mars on Earth^®”) in the light of three years of experimentation in the Laboratory Biosphere, further investigation of system alternatives and the advent of other innovative engineering and agri-ecosystem approaches. Several experiments with candidate space agriculture crops have demonstrated the higher productivity possible with elevated light levels and improved environmental controls. For example, crops of sweet potatoes exceeded original Mars base prototype projections by an average of 46% (53% for best crop) ultradwarf (Apogee) wheat by 9% (23% for best crop), pinto bean by 13% (31% for best crop). These production levels, although they may be increased with further optimization of lighting regimes, environmental parameters, crop density etc. offer evidence that a soil-based system can be as productive as the hydroponic systems which have dominated space life support scenarios and research. But soil also offers distinct advantages: the capability to be created on the Moon or Mars using in situ space resources, reduces long-term reliance on consumables and imported resources, and more readily recycling and incorporating crew and crop waste products. In addition, a living soil contains a complex microbial ecosystem which helps prevent the buildup of trace gases or compounds, and thus assist with air and water purification. The atmospheric dynamics of these crops were studied in the Laboratory Biosphere adding to the database necessary for managing the mixed stands of crops essential for supplying a nutritionally adequate diet in space. This paper explores some of the challenges of small bioregenerative life support: air-sealing and facility architecture/design, balance of short-term variations of carbon dioxide and oxygen through staggered plantings, options for additional atmospheric buffers and sinks, lighting/energy efficiency engineering, crop and waste product recycling approaches, and human factor considerations in the design and operation of a Mars base. An “Earth to Mars” project, forging the ability to live sustainably in space (as on Earth) requires continued research and testing of these components and integrated subsystems; and developing a step-by-step learning process.     

飞机结冰热力学行为研究综述

热力学现象是制约飞机结冰特性的重要现象之一。开展飞机结冰过程热力学行为的研究旨在深入把握结冰过程的规律特征,从而为建立科学有效的结冰防护手段、保障结冰条件下的飞行安全奠定基础。本文回顾和介绍了飞机结冰热力学研究所涉及的过冷水滴存在的物理机制、结冰热力学条件、形核与晶体生长、耦合液/固相变的复合传热传质特性,以及热力学效应作用下的结冰物理特性等相关领域的研究进展及发展现状,并基于国外相关研究的发展趋势,提出了中国未来飞机结冰热力学研究需重点关注的方向。     

水平表面气流剪切作用下的水膜厚度

飞机结冰表面上的液态水受气流吹拂作用会发生向后溢流,从而影响结冰区域范围及防冰系统设计;为了获得水膜流动规律,对水平平板表面上气流剪切驱动的水膜流动进行了实验测量和建模分析。通过水膜流动风洞试验台产生高速气流驱动水膜的流动,使用色散共焦位移计测量同一位置的水膜在不同时刻的厚度变化,结果表明气-液界面由底层薄水膜和多种尺度的波动组成,具有变化速度快随机性强的特点。通过水膜厚度随气流速度及水膜雷诺数的变化规律,发现平均水膜厚度与两者均呈现出单调非线性的依赖关系。基于薄水膜流动理论和平均水膜厚度实验结果,提出了高速气流剪切作用下的气-液波动界面剪切因子计算式,适用于风速17.8~52.2m/s,水膜雷诺数26~128之间的平板水膜流动计算。     

7075铝合金在不同温度盐水环境中的腐蚀疲劳行为

基于飞机结构材料7075铝合金在沿海地区服役时海水飞溅及曝晒导致的高温腐蚀疲劳损伤问题,研究了7075铝合金在35,55,75℃下3.5%NaCl溶液环境中的腐蚀疲劳寿命,并使用扫描电子显微镜(SEM)观察断口形貌,探讨了温度对腐蚀疲劳裂纹萌生扩展的影响机理。结果表明:同一应力水平下,温度越高,腐蚀疲劳寿命越短,300MPa时35,55,75℃下的中值寿命分别为33 001,30 931,15 346次循环。腐蚀损伤和疲劳损伤存在竞争关系,应力水平较高时,腐蚀较轻,试样寿命主要受应力水平影响,疲劳源多从铝合金基体与包铝层结合处萌生;应力水平较低时,腐蚀较严重,疲劳寿命随温度升高明显下降,疲劳源多从腐蚀坑处萌生。断口形貌显示高温环境主要通过加速腐蚀坑的形成来影响疲劳源的萌生,深坑状腐蚀坑应力集中严重,对疲劳性能伤害大。     

Assessing the feasibility of involving gaseous products resulting from physicochemical oxidation of human liquid and solid wastes in the cycling of a bio-technical life support system

The study addresses the possible ways of involving gaseous products produced by “wet” incineration of human wastes mixed with H₂O₂ in an alternating electric field in the cycling of the physical model of a bio-technical life support system (BTLSS). The resulting gas mixture contains CO₂ and O₂, which are easily involved in the cycling in the closed ecosystem, and NH₃, which is unacceptable in the atmosphere of the BTLSS. NH₃ fixation has been proposed, which is followed by nitrification and involvement of the resulting products in the mass exchange of the closed system. Experiments have been performed to show that plants can be grown in the atmosphere resulting from the closing of the gas loop that includes a physicochemical installation and a growth chamber with plants representing the phototrophic compartment of the BTLSS. The results of the study suggest the conclusion that the proposed method of organic waste oxidation can be a useful tool in creating a physical model of a closed-loop integrated BTLSS.     

Increased BLSS closure using mineralized human waste in plant cultivation on a neutral substrate

The purpose of this work was to study the full-scale potential use of human mineralized waste (feces and urine) as a source of mineral elements for plant cultivation in a biological life support system (BLSS). Plants that are potential candidates for a photosynthesizing link were grown on a neutral solution containing human mineralized waste. Spring wheat Triticum aestivum L., peas Pisum sativum L. Ambrosia cultivar and leaf lettuce Lactuca sativa L., Vitaminny variety, were used. The plants were grown hydroponically on expanded clay aggregates in a vegetation chamber in constant environmental conditions. During plant growth, a determined amount of human mineralized waste was added daily to the nutrient solution. The nutrient solution remained unchanged throughout the vegetation period. Estimated plant requirements for macro-elements were based on a total biological productivity of 0.04 kg day⁻¹ m⁻². As the plant requirements for potassium exceeded the potassium content of human waste, a water extract of wheat straw containing the required amount of potassium was added to the nutrient solution. The Knop’s solution was used in the control experiments.     

正电子素络合形成研究(Ⅱ)

本文讨论了不同测量条件对正电子素络合反应速度常数测定值的影响。实验结果表明,在稀溶液的条件下,使用我们特殊设计的盛装溶液的匣式容器能大大提高放射源的使用率并能完全避免放射性废水。     

高效离子电热水器的设计

描述一种由AT89C2051单片机控制的高效离子电热水器，该热水器使用安全，即开即热，转换效率高。     

高压水切割技术

复合材料的机械加工是一个特殊的问题.本文论述了用高压水切割技术对复合材料加工的原理和优点,简要说明了切割设备的组成,给出了主要的理论计算方法,并用实验数据进行了比较.最后指出了该技术的应用领域的扩展及其前景.     

水系统装置扬程的计算及泵的选型分析

为了提高水系统中水泵的实际运行效率和扬程利用率,降低发动机试验成本,减少能量浪费,以某型发动机台架试验水系统为研究对象,综合考虑了装置静扬程、管路的各种局部损失和沿程损失开展装置扬程的计算。同时根据水系统所需的装置扬程、流量及其变化规律,从泵的参数及其特性曲线入手,进行泵的选型分析,确定合适的泵的类型、台数及连接方式。通过水系统装置扬程的计算和泵的选型分析,结合泵带来的能效利用、工程投入和运行费用等因素,可在满足发动机试验需要的同时实现经济利益最大化,为今后类似水系统工程的设计提供借鉴和指导。