高层大气模型对空间站轨道漂移和寿命的影响分析

本文以轨道摄动分析方法一阶理论为基础，其中大气阻力摄动采用数值积分方法，给出一种可利用各种大气模型进行轨道摄动分析的计算方法，并利用三种高层大气模型（ＣＩＲＡ—７２，ＣＩＲＡ—８６和ＤＴＭ）和三个太阳活动水平（Ｆ１０．７＝１００，１５０和２００）分析比较了大气阻力振动对高度为４００ｋｍ的空间站轨道漂移和寿命的影响，以及估算修正轨道漂移所需的能量。给出的定量分析结果将为空间站或航天飞行器的轨道设计和能量估算提供依据。     

碳势控制数学模型的建立

研究了甲醇－乙酸乙酯气喷气炉内直接制备气氛的碳势控制问题，建立了温度Ｔ、甲烷含量、二氧化碳含量为参数的三因素碳势计算模型。该模型直实地反映了该炉气的碳变变化情况。经过几百次的试验表明，实测碳势值与模型计算值最大偏差为０．０５３％。     

1Cr11Ni23Ti3MoB材料气体渗氮工艺研究

某零组件渗氮时,其渗氮层易出现裂纹及剥落的问题。经研究发现,1Cr11Ni23Ti3MoB材料渗氮时,由于渗氮温度、氨分解率过低,导致零件表面氮势过高,极易在渗层内产生大量微裂纹,并会导致渗层表面出现剥落的现象。通过控制渗氮温度、渗氮时间、氨分解率,有效的解决该类质量问题。     

Ion production and ionization effect in the atmosphere during the Bastille day GLE 59 due to high energy SEPs

The influence of high energy particles, specifically cosmic rays, on atmospheric physics and chemistry is highly discussed. In most of the proposed models the role of ionization in the atmosphere due to cosmic rays is not negligible. Moreover, effect(s) on minor constituents and aerosols are recently observed, specifically over the polar regions during strong solar particle events. According to the recent findings for such effects it is necessary an essential increase of ion production, specifically during the winter period. The galactic cosmic rays are the main source of ionization in the Earth’s stratosphere and troposphere. Occasionally, the atmospheric ionization is significantly enhanced during strong solar energetic particles events, specifically over the polar caps. During the solar cycle 23 several strong ground level enhancements were observed. One of the strongest was the Bastille day event occurred on 14 July 2000. Using a full Monte Carlo 3-D model, we compute the atmospheric ionization, considering explicitly the contribution of cosmic rays with galactic and solar origin, focusing on high energy particles. The model is based on atmospheric cascade simulation with the PLANETOCOSMICS code. The ion production rate is computed as a function of the altitude above the sea level. The ion production rate is computed on a step ranging from 10 to 30?min throughout the event, considering explicitly the spectral and angular characteristics of the high energy part of solar protons as well as their time evolution. The corresponding event averaged ionization effect relative to the average due to galactic cosmic rays is computed in lower stratosphere and upper troposphere at various altitudes, namely 20?km, 15?km, 12?km and 8?km above the sea level in a sub-polar and polar regions. The 24^h and the weekly ionization effects are also computed in the troposphere and low stratosphere. Several applications are discussed.     

新型高空探测系统

研发了一种新型全自动高空探测系统,其利用GPS定位,宽波瓣天线捕捉和低噪声接收的方法替代雷达或无线电经纬仪对高空探测仪进行跟踪定位和获取信息,具有不受低仰角的限制,目标不易丢失,性能价格比高等特点,成功将GPS应用于1680 MHz遥测数据传输体制.利用该系统进行了空中大气电场的探测实验,获得了满意的探测结果.由于系统轻便、操作简单、成本较低以及良好的机动性和可靠性,在近地空间环境探测和高空大气科学探测试验及常规的气象探测中有广阔的应用前景.     

High-fidelity geometry models for improving the consistency of CHAMP,GRACE, GOCE and Swarm thermospheric density data sets

During the last two decades, accelerometers on board of the CHAMP, GRACE, GOCE and Swarm satellites have provided high-resolution thermosphere density data to improve our knowledge on atmospheric dynamics and coupling processes in the thermosphere-ionosphere region. Most users of the data have focused on relative density variations. Scale differences between datasets and models have been largely neglected or removed using ad hoc scale factors. The origin of these scale differences arises from errors in the aerodynamic modelling, specifically in the modelling of the satellite outer surface geometry and of the gas-surface interactions. Therefore, the first step to remove the scale differences is to enhance the geometry modelling. This work forms the foundation for the future improvement of characterization of satellite aerodynamics and gas-surface interactions models at TU Delft, as well as for extending the use of sideways and angular accelerations in the aerodynamic analysis of accelerations and derivation of thermosphere datasets. Although work to improve geometry and aerodynamic force models by other authors has focused on CHAMP and GRACE, this paper includes the GOCE and Swarm satellites as well. In addition, it uses a density determination algorithm that is valid for arbitrary attitude orientations, enabling a validation making use of attitude manoeuvres. The results show an improvement in the consistency of density data between these four missions, and of data obtained before, during and after attitude manoeuvres of CHAMP and Swarm. The new models result in larger densities, compared to the previously used panel method. The largest average rescaling of density, by switching to the new geometry models is reached for Swarm at 32%, the smallest for GRACE at 5%. For CHAMP and GOCE, mean differences of 11% and 9% are obtained respectively. In this paper, an overview of the improvements and comparisons of data sets is provided together with an introduction to the next research phase on the gas-surface interactions.     

A new model for atmospheric radiation under clear sky condition at various altitudes

Atmospheric radiation is one of the major factors that dominate the thermal behaviors of aerostats. A high-performance model is needed to evaluate the atmospheric radiation. Based on the atmospheric radiation database containing 24,862 data points compiled from 7 stations with the elevation from sea level to 2373 m and the reference code MODTRAN, a new atmospheric radiation model is proposed using regression and optimization software. It has excellent prediction accuracy with the coefficient of determination of 0.94, the root mean square error of 15.1 W/m², and the mean absolute percentage error of 4.13% for the database. Comparison with the well-known existing model shows that the new model has the highest prediction accuracy. The new model predictions agree with the MODTRAN calculations at various altitudes very well, and thus it can be used for estimating the thermal performances of a high altitude aerostat.     

纳米二氧化钛吸入对小鼠肺部和血清生化指标的影响

将成年健康的小鼠(每组8只)暴露在含有1 500 mg/m3纳米二氧化钛气溶胶密闭装置内,以暴露在空气中的小鼠作为对照,研究了纳米二氧化钛对小鼠肺部组织和血清生化指标的影响.经过不同时间的暴露后将小鼠处死,收集血样并取肺部组织进行生化指标分析和组织病理学检验.血清生化指标检测结果显示,在所有的试验组中,乳酸脱氢酶的活性均提高,丙氨酸氨基转移酶的活性和尿素氮在暴露28天组中增加,肌酐在暴露14天组和28天组中均增加,其他血清学指标未见明显异常.组织病理学检测结果显示,暴露28天的肺泡间隙有纳米粒子存在,并且肺部炎症逐渐增强.