Selection and hydroponic growth of bread wheat cultivars for bioregenerative life support systems

As part of the ESA-funded MELiSSA program, the suitability, the growth and the development of four bread wheat cultivars were investigated in hydroponic culture with the aim to incorporate such a cultivation system in an Environmental Control and Life Support System (ECLSS). Wheat plants can fulfill three major functions in space: (a) fixation of CO₂ and production of O₂, (b) production of grains for human nutrition and (c) production of cleaned water after condensation of the water vapor released from the plants by transpiration. Four spring wheat cultivars (Aletsch, Fiorina, Greina and CH Rubli) were grown hydroponically and compared with respect to growth and grain maturation properties. The height of the plants, the culture duration from germination to harvest, the quantity of water used, the number of fertile and non-fertile tillers as well as the quantity and quality of the grains harvested were considered. Mature grains could be harvested after around 160 days depending on the varieties. It became evident that the nutrient supply is crucial in this context and strongly affects leaf senescence and grain maturation. After a first experiment, the culture conditions were improved for the second experiment (stepwise decrease of EC after flowering, pH adjusted twice a week, less plants per m²) leading to a more favorable harvest (higher grain yield and harvest index). Considerably less green tillers without mature grains were present at harvest time in experiment 2 than in experiment 1. The harvest index for dry matter (including roots) ranged from 0.13 to 0.35 in experiment 1 and from 0.23 to 0.41 in experiment 2 with modified culture conditions. The thousand-grain weight for the four varieties ranged from 30.4 to 36.7 g in experiment 1 and from 33.2 to 39.1 g in experiment 2, while market samples were in the range of 39.4–46.9 g. Calcium levels in grains of the hydroponically grown wheat were similar to those from field-grown wheat, while potassium, magnesium, phosphorus, iron, zinc, copper, manganese and nickel levels tended to be higher in the grains of experimental plants. It remains a challenge for future experiments to further adapt the nutrient supply in order to improve senescence of vegetative plant parts, harvest index and the composition of bread wheat grains.     

中国旅游业的发展特征与趋势研究

中国旅游业经过高速成长,已成为国民经济的一个重要产业,目前具有资源开发的宽泛性与不均衡性、产品供给的基本适应性与多样性、市场的巨大性与消费的普遍性、要素配套的失衡性、新业态萌动的蓬勃性、目的地产业的聚集性与发展的区域性、政府旅游管理决策认识的科学性等发展特征,发展趋势是产业地位和作用强化、产业结构合理化和高度化、产业组织集团化、管理法制化和规范化、发展生态化和可持续化、支撑科技化、盈利模式复合化.在国内外相关条件不断提高和改善的环境下,中国的旅游业将会迎来一个新的快速发展的阶段.     

Statistical modelling of radio wave propagation under sporadic E-Layer influence

A technique of modelling the one-hop radio wave propagation at middle latitudes in the presence of sporadic E-Layer is presented. The technique is focused on the performance of the long-term forecast of the maximum usable frequency range and on the increase of the radio communication reliability. Examples of calculation for medium-distance paths are shown.     

看红色文化如何与动漫经济相结合——动画电影《西柏坡》简评

时下红色文化热,唱红歌活动大江南北如火如荼。红色电影《西柏坡》将红色文化教育、红色旅游经济与动漫传播相结合,是一次用动画形式弘扬红色文化的大胆尝试。     

区域经济外源性增长中的政企博弈

外源性经济增长是以吸引外商直接投资方式,促进区城经济增长的一种方式。在这种增长方式中,政府和投资者,有着不同目标利益取向,从而导致外商直接投资区域分布的不均衡性。本文运用博奕理论探讨多目标博奕对外商直接投资区域分布的影响。研究表明,外商直接投资的区位选择及投资额与政府投资建设的软硬环境密切相关,而且投资环境越优对外商直接投资的吸引力越大;而对政府而言,应从招商引资向招商选资转变,以便实现综合效益最优化和规避政府的投资风险。     

中国区域卫星导航系统星座的方案探讨

首先简要介绍了欧洲、日本发展卫星定位导航系统的情况。阐述了我国第二代区域卫星导航系统的必要性。指出了采用因轨道同步卫星和静止星的星座方案的优缺点。用计算机仿真详细研究了倾斜椭圆轨道同步卫星的轨道参数与定位性能关系。设计了一个静止卫星和椭圆同步卫星组成的7星星座，并且评估了该星座在我国及周边地区的性能。仿真计算表明，这种星座能够满足现阶段我国区域导航系统需要。     

TEM 理论在支线机场航线维修风险管理实践中的研究与应用

以国内某支线机场机务维修安全管理系统为案例,对该机场航线维修、维修质量、安全管理、风险管控、人为因素等相关内容进行分析统计,对实际工作的图表数据、业务流程、规章制度、行业标准等资料进行整理,运用TEM方法对航空器维修工作中的风险进行描述和分析,运用模糊层次分析法计算风险要素比重并进行排序,为机场航线维修安全管理和风险管控提出合理化安全建议,以求进一步提高支线机场机务风险管控能力。     

基于资源观的低空及低空经济

提出了将围绕低空空域资源以及存在于低空的气候资源和空气资源而展开的经济活动集合视为一种经济形态的设想,称之为低空经济,并对其产业构成和产业活动形式进行初步探索。对于中国这样一个自然资源相对匮乏、人口众多、经济尚不发达的负责任大国,发展低空经济尤其具有现实意义。     

求解区域网络问题的近似算法

区域网络是给定一个无向图G=(V,E),在图G中,存在一个子图是森林,森林中的若干个不相交的树称为若干个区域。该问题的目标是把该森林子图即若干个区域连结成一棵树,且使增加的边的权和最小。把该问题归结为图的Steiner tree问题,给出了求解该问题的一个近似算法,并证明其复杂性,最后用实例说明算法的准确性。     

高科技:新经济发展的动力之源

高科技是新经济发展的基础和动力 ,新技术革命直接提高了综合国力 ,高科技作为动力之源直接推动着新经济的发展 ,高科技以科学技术形态所表现出来的战略实力 ,已经成为增强综合国力和国际竞争力的关键性因素。