Closed bioregenerative life support systems: Applicability to hot deserts

Water scarcity in hot deserts, which cover about one-fifth of the Earth’s land area, along with rapid expansion of hot deserts into arable lands is one of the key global environmental problems. As hot deserts are extreme habitats characterized by the availability of solar energy with a nearly complete absence of organic life and water, space technology achievements in designing closed ecological systems may be applicable to the design of sustainable settlements in the deserts. This review discusses the key space technology findings for closed biogenerative life support systems (CBLSS), which can simultaneously produce food, water, nutrients, fertilizers, process wastes, and revitalize air, that can be applied to hot deserts. Among them are the closed cycle of water and the acceleration of the cycling times of carbon, biogenic compounds, and nutrients by adjusting the levels of light intensity, temperature, carbon dioxide, and air velocity over plant canopies. Enhanced growth of algae and duckweed at higher levels of carbon dioxide and light intensity can be important to provide complete water recycling and augment biomass production. The production of fertilizers and nutrients can be enhanced by applying the subsurface flow wetland technology and hyper-thermophilic aerobic bacteria for treating liquid and solid wastes. The mathematical models, optimization techniques, and non-invasive measuring techniques developed for CBLSS make it possible to monitor and optimize the performance of such closed ecological systems. The results of long-duration experiments performed in BIOS-3, Biosphere 2, Laboratory Biosphere, and other ground-based closed test facilities suggest that closed water cycle can be achieved in hot-desert bioregenerative systems using the pathways of evapotranspiration, condensation, and biological wastewater treatment technologies. We suggest that the state of the art in the CBLSS design along with the possibility of using direct sunlight for photosynthesis and recent advances in photovoltaic engineering can be used as a basis for building sustainable settlements producing food, water, and energy in hot deserts.     

舰艇计量保障初探

舰艇是量值传递的特定领域,为确保舰艇装备技能的充分有效,必须开展舰艇装备的计量保障,这已经引起很多国家的重视,并采取了多种措施。结合以上情况和我国舰艇计量现状,笔者对舰艇计量保障模式进行了初步探讨,并针对相应问题,提出了一些设想。     

回归模型在房地产市场方面的应用

本文通过建立的回归模型，对商品住宅的销售量进行了预测。     

运载火箭动力系统试验承力环的静力试验

建立了某型号运载火箭动力系统试验用承力环的非破坏性静力试验方案,以评估该承力环的强度和刚度。为模拟发动机关机时的载荷冲击,将静力试验最大载荷设定为发动机额定总推力的2倍,包含水平和垂直两个分量,均分为8个载荷步加载。在承力环上设置了27个三向应变测点和12个轴向位移测点,以监测一些关键点的应力和位移。测量结果显示,在最大载荷下,当量应力达到303 MPa,低于材料屈服强度;轴向变形达到3.16 mm,低于设计许用变形;应力最大点位于支腿销孔处。对销孔孔距的变化进行了测量,并对附近的钢板表面进行了MT探伤。数据结果表明,该承力环在两倍的动力系统试验额定载荷下有足够的强度和刚度,可用于该试验。     

矩阵函数在解线性方程组中的应用

本文利用矩阵函数及其微积分运算来求解一阶线性常系数非齐次微分方程组。     

一个新的向量等式

给出一个新的向量恒等式，首先采用函数论方法严格证明了该恒等式，其次从向量分析角度指出该恒等式与向量加法的三角形法则之间的密切联系，最后从质量守恒的观点给出该恒等式的一种物理解释。     

基于偏心率和倾角矢量的共位隔离策略

在同一个标准的位置保持窗口内并置多颗卫星,并且避免相互之间的碰撞、干扰和遮蔽,是充分利用地球静止轨道资源的一种比较好的办法。针对我国卫星共位隔离的工程需要,文章提出了一种基于偏心率矢量和倾角矢量实现共位隔离的方法,给出了基于偏心率矢量和倾角矢量联合隔离的基本方法、约束方程,以及工程实现时的位置保持策略。通过仿真计算和工程实际应用,验证了该方法的正确性。     

国内新机设计对综合保障设计技术发展的需求

以下一代先进战斗机研制需求为背景, 通过对国内外综合保障技术发展现状的分析, 提出了国内急需发展的综合保障设计技术, 对从事综合保障设计、研究的工程技术人员和大专院校学者有一定的参考价值。     

浅谈装备计量保障

介绍了计量保障的概念及新时期实施装备计量保障的政策导向；介绍了GJB5109-2004的要点；分析了新标准颁布实施后，将给承制方(供应商)带来的各种机遇和挑战。     

我国利润表编制中存在的问题与改进

文章论述了利润表设计的理论依据,通过我国利润表同国外利润表比较,发现我国利润表的编制基础对会计信息的陈报存在不利影响,并结合实际情况,提出了未来利润表改进办法.