开放大气等离子体中带电粒子密度时间演化的数值模拟

利用大气化学反应的零维模型,模拟了地面附近的大气化学反应,研究了电子和主要离子在大气化学反应中的动力学规律和机制,给出了电子密度及其他带电粒子密度随时间的演化图.所得结果对进一步了解大气中的物理化学反应和空气动力学的机理具有重要意义,对飞机的等离子体隐身和大气环境污染与监测也具有一定的参考价值.     

活塞式航空汽油机增压的模拟研究

为了改善活塞式航空汽油机的高空性能,基于GT-Power软件,建立了活塞式航空汽油机原机和增压机模型,对活塞式航空汽油机进行了原机、一级增压及二级增压模拟研究.研究表明,涡轮增压能有效改善活塞式航空发动机高空性能,一级增压后,该活塞式航空发动机极限工作高度达到海拔7km以上;气动二级增压后,则能达到海拔8～9km,而电控二级增压后,极限工作高度将达到海拔10～11km.     

星用镀膜光学透镜空间带电粒子辐射效应评价

针对K509玻璃基镀膜透镜空间带电粒子辐射效应,使用两种能量的电子和60 Coγ射线作为模拟源进行了辐照试验,并分析了辐照效应与轨道带电粒子辐射的差别.在此基础上,提出了一种针对镀膜光学透镜,使用低能电子和60 Coγ射线接续辐照,模拟空间带电粒子辐射效应的试验方法.     

固冲发动机高空模拟引射器设计与试验研究

该文针对固冲发动机排气压强低、流量小的特点,利用流体力学相关理论与方法,通过分析高空试验环境,探讨了主被动引射器的工程设计和性能计算方法,确立了最优的高空模拟试验方案.依据该方案建立了固冲发动机高空模拟主被动引射器试验装置.对某发动机的试验测试表明,该试验装置达到了预期的20 km高空模拟的要求,验证了设计和计算方法的正确性.     

东亚高空大气气溶胶的分布及沙尘输送特征研究

利用长达20 年的SAGEⅡ(stratospheric aerosol and gas experimentⅡ) 资料, 研究了东亚地区5.0 ～15.0 km 高空气溶胶多年时空分布特征和变化趋势, 并研究了东亚沙尘活动对高空及下游的气溶胶输送。发现东亚高空气溶胶水平分布呈现上中下3 层不同的分布特征, 下层 5. 0 ～8. 5 km 高值区对应气溶胶源区青藏高原和西北沙漠地区;中层 9. 0 ～10. 0 km 高值区对应温带气旋高发的中纬度地区;上层 10. 5 ～15. 0 km 表现为低纬气溶胶含量显著高于高纬地区。高空各层气溶胶的空间分布受天气系统的影响具有明显的季节变化。近10 年来东亚高空气溶胶呈减少趋势, 平均光学厚度约下降了0. 016。另外还发现沙尘活动与 5. 0 ～11. 5 km 范围内的气溶胶显著相关, 反映沙尘活动影响的高度范围可以达到整个对流层。定义沙尘暴高空影响指数, 用来分析东亚沙尘暴对下游地区的影响, 发现随着时间推移沙尘逐渐向东移动, 在约 12 天之后可以到达大西洋。     

星载微波辐射计遥感大气温度廓线的数值模拟

为了充分了解微波被动遥感大气温度廓线的能力,为星载微波辐射计研制及今后的资料解释提供必要的技术基础,开展了采用50～60 GHz氧气吸收带内的7个通道反演大气温度廓线的数值模拟研究.利用微波辐射传输模型模拟了微波辐射计各通道亮度温度,在此基础上建立了大气温度廓线的统计反演方案.统计反演的数值试验表明,50～60 GHz微波通道对大气温度廓线有一定的遥感反演能力.     

单韧致辐射用于BESⅢ亮度测量的模拟研究

快速实时的亮度监测器将为升级后的北京正负电子对撞机的操作提供很大帮助 .把单韧致辐射过程产生的光子转化为带电粒子 ,收集带电粒子在辐射体中产生的C erenkov光可用来测量亮度 .论文模拟研究了单韧致辐射过程的性质 ,并用GEANT3和GEANT4模拟了亮度测量的整个过程 ,初步给出设计参数的最优化结果     

带电粒子在磁场中运动情况的计算机模拟实验

利用 MATLAB语言开发了一个对带电粒子在磁场中的运动情况进行模拟的实验教学软件 ,模拟了单个带电粒子和一束正态分布的带电粒子束在磁场中的运动规律 ,并给出了软件的设计思想 .     

带电粒子在外加电磁场中去捕获问题

带电粒子与电磁场相互作用过程中的去捕获问题对于等离子体物理学、带电粒子加速以及微波电子学等领域具有重要的意义.使用解析法研究了带电粒子的去捕获问题,并且对粒子的引导中心方程作了数值模拟.论文结果表明带电粒子的振动频率与电磁波频率发生共振时去捕获成为可能.     

高空薄云影响下的大气长波辐射遥感估算

作为地气系统能量交换的重要形式,精准的大气下行长波辐射数据对地表、大气层顶模型的建立以及全球生态环境和气象气候研究极其重要.目前关于遥感反演大气下行辐射的研究多以晴空条件为前提,很少考虑到高空薄云,使得这些方法应用范围受限.高空薄云对红外辐射具有不完全通透性,地表信息部分被云削减后透过云层到达传感器.由于云体温度极低,可明显降低传感器观测的星上亮温,加上其复杂的微物理学属性和多变的分布特征,对大气下行辐射的反演造成很大影响.通过研究不同性质的高空薄云,基于小样本理论、利用神经网络和支持向量机构建高空薄云存在时的大气下行辐射遥感反演模型,并结合实测站点数据对模型的精度进行检验.结果显示,两种算法的精度基本满足瞬时地表长波辐射研究的要求,解决了高空薄云影响下遥感反演大气下行辐射的难点.两种非线性模型直接以传感器的辐亮度、亮温组合、大气水汽含量以及光学厚度作为输入,既考虑了云的特征参数,又避免了计算大气下行辐射的误差传递,提高了算法的通用性和实用性.     

带电粒子在电子束法脱硝中的行为及作用

模拟研究了电子束法脱硝中带电粒子的特性，结果表明带电粒子反应速度非常快，其浓度达到平衡所需时间很短；非常电粒子可与其分开处理，带电粒子反应是自由基的重要来源。     

The vertical profile of winds on Titan

One of Titan's most intriguing attributes is its copious but featureless atmosphere. The Voyager 1 fly-by and occultation in 1980 provided the first radial survey of Titan's atmospheric pressure and temperature and evidence for the presence of strong zonal winds. It was realized that the motion of an atmospheric probe could be used to study the winds, which led to the inclusion of the Doppler Wind Experiment on the Huygens probe. Here we report a high resolution vertical profile of Titan's winds, with an estimated accuracy of better than 1 m s(-1). The zonal winds were prograde during most of the atmospheric descent, providing in situ confirmation of superrotation on Titan. A layer with surprisingly slow wind, where the velocity decreased to near zero, was detected at altitudes between 60 and 100 km. Generally weak winds (approximately 1 m s(-1)) were seen in the lowest 5 km of descent.     

In situ measurements of the physical characteristics of Titan's environment

On the basis of previous ground-based and fly-by information, we knew that Titan's atmosphere was mainly nitrogen, with some methane, but its temperature and pressure profiles were poorly constrained because of uncertainties in the detailed composition. The extent of atmospheric electricity ('lightning') was also hitherto unknown. Here we report the temperature and density profiles, as determined by the Huygens Atmospheric Structure Instrument (HASI), from an altitude of 1,400 km down to the surface. In the upper part of the atmosphere, the temperature and density were both higher than expected. There is a lower ionospheric layer between 140 km and 40 km, with electrical conductivity peaking near 60 km. We may also have seen the signature of lightning. At the surface, the temperature was 93.65 +/- 0.25 K, and the pressure was 1,467 +/- 1 hPa.     

碳排放CO2温室效应机制

基于两个化学反应(1)CO₂+H₂O→H₂CO₃和(2)H₂CO₃+3H₂O→H₂CO₃·3H₂O,采用量子化学方法,优化获得反应物和产物分子结构,计算其红外振动光谱和化学反应的热力学数据,确定这些化合物对红外辐射的吸收与强度.研究发现,反应(1)和(2)能自发发生反应,产生H₂CO₃和H₂CO₃·3H₂O(三水碳酸);H₂CO₃具有较强的红外辐射吸收(重要的吸收频率1 919.9 cm^-1和强度426.7 km/mol等),H₂CO₃·3H₂O具有很强的红外辐射吸收(重要的吸收频率3 145.9 cm^-1和强...     

Heterogeneous reactions on the surface of fine particles in the atmosphere

Fine particles play an important role in the atmosphere. Research on heterogeneous reactions on the surface of fine particles is one of the frontier areas of atmospheric science. In this paper, physical and chemical characteristics of fine particles in the atmosphere and the interactions between trace gases and fine particles are described, methods used in heterogeneous reactions research are discussed in detail, progress in the study of heterogeneous reactions on the surface of fine particles in the atmosphere is summarized, existing important questions are pointed out and future research directions are suggested.     

Evidence of atmospheric sulphur in the martian regolith from sulphur isotopes in meteorites

Sulphur is abundant at the martian surface, yet its origin and evolution over time remain poorly constrained. This sulphur is likely to have originated in atmospheric chemical reactions, and so should provide records of the evolution of the martian atmosphere, the cycling of sulphur between the atmosphere and crust, and the mobility of sulphur in the martian regolith. Moreover, the atmospheric deposition of oxidized sulphur species could establish chemical potential gradients in the martian near-surface environment, and so provide a potential energy source for chemolithoautotrophic organisms. Here we present measurements of sulphur isotopes in oxidized and reduced phases from the SNC meteorites--the group of related achondrite meteorites believed to have originated on Mars--together with the results of laboratory photolysis studies of two important martian atmospheric sulphur species (SO2 and H2S). The photolysis experiments can account for the observed sulphur-isotope compositions in the SNC meteorites, and so identify a mechanism for producing large abiogenic 34S fractionations in the surface sulphur reservoirs. We conclude that the sulphur data from the SNC meteorites reflects deposition of oxidized sulphur species produced by atmospheric chemical reactions, followed by incorporation, reaction and mobilization of the sulphur within the regolith.     

Halocarbons produced by natural oxidation processes during degradation of organic matter

Volatile halogenated organic compounds (VHOC) play an important role in atmospheric chemical processes-contributing, for example, to stratospheric ozone depletion. For anthropogenic VHOC whose sources are well known, the global atmospheric input can be estimated from industrial production data. Halogenated compounds of natural origin can also contribute significantly to the levels of VHOC in the atmosphere. The oceans have been implicated as one of the main natural sources, where organisms such as macroalgae and microalgae can release large quantities of VHOC to the atmosphere. Some terrestrial sources have also been identified, such as wood-rotting fungi, biomass burning and volcanic emissions. Here we report the identification of a different terrestrial source of naturally occurring VHOC. We find that, in soils and sediments, halide ions can be alkylated during the oxidation of organic matter by an electron acceptor such as Fe(III): sunlight or microbial mediation are not required for these reactions. When the available halide ion is chloride, the reaction products are CH3Cl, C2H5Cl, C3H7Cl and C4H9Cl. (The corresponding alkyl bromides or alkyl iodides are produced when bromide or iodide are present.) Such abiotic processes could make a significant contribution to the budget of the important atmospheric compounds CH3Cl, CH3Br and CH3I.     

Numerical simulation of ionization enhancement in the topside ionosphere of cusp foot-point region caused by low energy particle precipitation

The Graz Ionospheric Flux Tube Simulations (GIFTS) has been improved. The improved GIFTS model was used to numerically investigate the energy particle precipitation on the distribution of electron density in the ionospheric cusp foot-point region under conditions of large plasma convection during magnetic storm. After including the effects of low energy incident particles, the ionospheric electron densities increase remarkably above altitude of ∼250 km, showing a peak at about 350 km. The percent enhancements of electron densities increase gradually with altitude, exceeding 60% near the upper boundary of the calculation. The calculated ionospheric F ₂-peak was remarkably enhanced and lifted up by the incident low energy electrons. Biography: CAI Hongtao(1976–), male, Associate professor, Ph.D., research direction: polar magnetosphere and ionosphere.     

纳米材料的室温或近室温超声波固相化学反应合成

在室温或近室温条件和超声波作用下，通过固相化学反应合成出了金属氧化物、金属硫化物、金属草酸盐、金属碳酸盐、金属钼酸盐等五类纳米材料．用粉末X射线衍射(XRD)、透射电镜(TEM)和电子衍射法对其物相、晶粒形貌和晶粒大小进行了表征．结果表明，用该方法合成纳米材料具有产率高、不需要溶剂、反应时间短、室温或近室温反应和纳米材料稳定性好等显著优点。