Experimental study on energy dissipation in a 1 kW arcjet thruster

As a simple and reliable propulsion system, arcjet thrusters have been used in multiple satellite missions. In order to improve the efficiency of arcjet thrusters, energy dissipation study was carried out in a 1 kW arcjet thruster with pure N2, H2-N2 and H2 as the propellant. Using a 698 nm interference filter, thermal radiation was isolated from arc and plume emissions and the internal nozzle temperature was obtained by converting the thermal radiation signals. Results show that the addition of hydrogen leads to higher nozzle temperature, which is the determining factor for the mode of arc root attachment. At lower nozzle temperatures, constricted type attachment with unstable motions of the arc root was observed, while a fully diffused and stable arc root was observed at elevated nozzle temperatures. Output energy distribution analysis shows that losses from frozen flow and exhaust thermal losses are the main parts in limiting the efficiency of arcjet thrusters.

Experimental study on energy dissipation in a 1 kW arcjet thruster

As a simple and reliable propulsion system, arcjet thrusters have been used in multiple satellite missions. In order to improve the efficiency of arcjet thrusters, energy dissipation study was carried out in a 1 kW arcjet thruster with pure N2, H2-N2 and H2 as the propellant. Using a 698 nm interference filter, thermal radiation was isolated from arc and plume emissions and the internal nozzle temperature was obtained by converting the thermal radiation signals. Results show that the addition of hydrogen leads to higher nozzle temperature, which is the determining factor for the mode of arc root attachment. At lower nozzle temperatures, constricted type attachment with unstable motions of the arc root was observed, while a fully diffused and stable arc root was observed at elevated nozzle temperatures. Output energy distribution analysis shows that losses from frozen flow and exhaust thermal losses are the main parts in limiting the efficiency of arcjet thrusters.

在相对论性激光_等离子体系统中初始物理参数对激光脉冲的影响

基于相对论性激光-等离子体动力学理论,研究了相对论性激光-等离子体系统中圆偏振入射脉冲激光和等离子体相互作用对激光脉冲宽度的影响.具体分析了在不同初始物理参数下脉冲激光的脉冲宽度在等离子体传播过程中的变化情况,重点分析了激光脉冲在等离子中压缩.计算结果表明增加入射激光的强度和入射脉冲宽度以及减小等离子体的初始密度,能够有效地实现脉冲宽度在等离子体中压缩;当激光脉冲的初始参数a0=0·12和τ=70以及等离子体密度n0=0·3时,脉冲宽度相对压缩T/τ接近于1/10,从而给出了激光压缩的理论优化参数.

CSRe与RIBLLⅡ实时数据交互系统

介绍了国家重大科学工程项目——兰州重离子加速器冷却存储环(HIRFL-CSR)的实验环(CSRe)以及RIBLLⅡ的子系统——实时数据交互系统。该系统主要实现对前端电源设备的实时同步控制,具体的实现方法是从控制Web界面输入的前端控制设备所需的数据信息传送至中心Oracle数据库,再更新至前端服务器的Oracle数据库,随后传送至ARM板中的sqlite数据库,给DSP板提供输入数据信息,通过同步触发事例对电源设备进行同步实时控制。该系统正在RIBLLⅡ的测试中,运行正常、可靠性强、性能稳定。

Circa AD 626 volcanic eruption；climatic cooling；and the collapse of the Eastern Turkic Empire

IEECAS SKLLQG

西安住宅室内空气醛酮类污染物特征

IEECAS SKLLQG

Analysis of sulfur-containing compounds in crude oils by comprehensive two-dimensional gas chromatography with sulfur chemiluminescence detection

This paper reports an analytical method for separating, identifying, and quantifying sulfur-containing compounds in crude oil fraction (IBP-360degreesC) samples based on comprehensive two-dimensional gas chromatography coupled with a sulfur chemiluminescence detector. Various sulfur-containing compounds and their groups were analyzed with one direct injection. 3620 peaks were detected including 1722 thiols/thioethers/ disulfides/1-ring thiophenes, 953 benzothiophenes, 704 dibenzothiophenes, and 241 benzonaphthothiophenes. The target sulfur compounds and their groups were identified based on the group separation feature and structured retention of comprehensive two-dimensional gas chromatography as well as standard substances. The quantitative analysis of major sulfur-containing compounds and total sulfur was based on the linear response of the sulfur chemiluminescence detector using the internal standard method. The sulfur contents of target sulfur compounds and their groups in 4 crude oil fractions were also determined. The recoveries for standard sulfur-containing compounds were in the range of 90-102%. The quantitative result of total sulfur in the Oman crude oil fraction sample was compared with those from ASTM D 4294 standard method (total S by X-ray fluorescence spectrometry), the relative deviation (RD%) was 4.2% and the precision of the method satisfactory.

科学管理人类智慧的宝库──关于加强文献资源共建共享基本模式的初探

科学管理人类智慧的宝库──关于加强文献资源共建共享基本模式的初探梁伟（中国科学院沈阳应用生态所）自有文字以来，文献资源的积累就是人类智慧的巨大宝库。过去，一个人若要完全占有这个宝库，视天下文献资源为己所藏，为我所用，恐怕会被人笑为是狂人的幻想，而今这...

变水处理与短期遮荫对作物水分利用效率的影响

变水处理与短期遮荫对棉花水分利用效率的影响研究表明 ,在充分供水 -水分胁迫 -复水的变水处理过程中 ,短期遮荫使净光合速率、蒸腾速率、水分利用效率降低 ;光照 -遮荫 -光照期间 ,总的水分利用效率以水分胁迫的最高 ,充分供水的次之 ,复水处理最低 ,其中遮荫 40 %的水分利用效率高于遮荫 75%的处理 .回归分析表明 ,水分利用效率与光合速率表现出极显著正相关 ,两者回归直线的斜率随水分胁迫而增大 ,而水分利用效率与蒸腾速率的关系较弱 ,多数处理两者相关达不到显著水平

内生真菌对植物抗旱性的影响

内生真菌广泛地存在于植物体内,它们在植物体内的生活不会对植物引起任何感病症状,而且内生真菌侵染对植物生长、生物和非生物胁迫抗性很好的促进作用,理解内生真菌在提高植物干旱胁迫耐受性方面的作用和机理对其在缓解植物干旱胁迫中的应用有重要意义。这篇综述介绍了植物内生真菌的多样性、对植物抗旱性的影响及其作用机理等方面的研究进展。内生真菌对植物抗旱性提高的机理包括:干旱耐受、干旱回避和干旱恢复。文中还对以后的研究进行了展望。

全程一致访问控制体系研究

针对系统中的访问控制体系由各种访问控制机制堆彻而成而带来的系统访问控制不一致问题,本文提出了全程一致访问控制的概念,随后给出了全程一致访问控制体系的结构、分工及准则,以指导全程一致访问控制体系的构建,然后采用了原型系统对全程一致的访问控制体系进行了验证.采用该体系,不但能有效发挥系统中各访问控制机制的优势,还能降低安全投入成本.