Direct radiative forcing from black carbon aerosols over urban environment

There is growing evidence that the earth’s climate is changing and will likely continue to change in the future. It is still debated whether these changes are due to natural variability of the climate system or a result of increases in the concentration of greenhouse gases in the atmosphere. Black carbon (BC) has become the subject of interest for a variety of reasons. BC aerosol may cause environmental as well as harmful health effects in densely inhabited regions. BC is a strong absorber of radiation in the visible and near-infrared part of the spectrum, where most of the solar energy is distributed. Black carbon is emitted into the atmosphere as a byproduct of all combustion processes, viz., vegetation burning, industrial effluents and motor vehicle exhausts, etc. In this paper, we present results from our measurements on black carbon aerosols, total aerosol mass concentration and aerosol optical depth over an urban environment namely Hyderabad during January to May, 2003. Diurnal variations of BC indicate high BC concentrations during 6:00–9:00 and 19:00–23:00 h. Weekday variations of BC concentrations increase gradually from Monday to Wednesday and gradually decrease from Thursday to Sunday. Analysis of traffic density along with meteorological parameters suggests that the primary determinant for BC concentration levels and patterns is traffic density. Seasonal variations of BC suggest that the BC concentrations are high during dry season compared to rainy season due to the scavenging by air. The fraction of BC to total mass concentration has been observed to be 7% during January to May. BC showed positive correlation with total mass concentration and aerosol optical depth at 500 nm. Radiative transfer calculations suggests that during January to May, diurnal averaged aerosol forcing at the surface is −33 Wm² and at the top of the atmosphere (TOA) above 100 km it is observed to be +9 Wm⁻². The results have been discussed in detail in the paper.     

Modeling the charging of geosynchronous and interplanetary spacecraft using Nascap-2k

Nascap-2k is the updated version of the NASCAP/GEO spacecraft charging analysis code. In addition to packaging the physical content of NASCAP/GEO in a modern way, Nascap-2k incorporates other plasma analysis codes (in particular, the DynaPAC code) in order to extend its applicability to a wide variety of plasma environments. Nascap-2k also includes an interactive Object Toolkit for defining spacecraft surface models for analysis. In this paper we focus on the tenuous plasma charging capabilities of the code, with application to DSCS-III (geosynchronous environment), STEREO (solar wind environment) and MESSENGER (solar wind environment near 0.4 AU).     

Different space weather effects in anomalies of the high and low orbital satellites

Preliminary results of the EU INTAS Project 00810, which aims to improve the methods of safeguarding satellites in the Earth’s magnetosphere from the negative effects of the space environment, are presented. Anomaly data from the “Kosmos” series satellites in the period 1971–1999 are combined in one database, together with similar information on other spacecraft. This database contains, beyond the anomaly information, various characteristics of the space weather: geomagnetic activity indices (Ap, AE and Dst), fluxes and fluences of electrons and protons at different energies, high energy cosmic ray variations and other solar, interplanetary and solar wind data. A comparative analysis of the distribution of each of these parameters relative to satellite anomalies was carried out for the total number of anomalies (about 6000 events), and separately for high (5000 events) and low (about 800 events) altitude orbit satellites. No relation was found between low and high altitude satellite anomalies. Daily numbers of satellite anomalies, averaged by a superposed epoch method around sudden storm commencements and proton event onsets for high (>1500 km) and low (<1500 km) altitude orbits revealed a big difference in a behavior. Satellites were divided on several groups according to the orbital characteristics (altitude and inclination). The relation of satellite anomalies to the environmental parameters was found to be different for various orbits that should be taken into account under developing of the anomaly frequency models.     

腐蚀环境下LC4铝合金疲劳损伤累积规律研究

 进行了在加速腐蚀当量环境作用后, LC4 铝合金在同级载荷作用下疲劳损伤累积规律的实验研究。实验结果表明, 此时的同级载荷试验类似于常规条件下的/ 低、高0 两级载荷试验, 前级载荷对腐蚀作用后的后级载荷的疲劳行为也有/ 低载锻炼效应0, 因此, 提出了考虑腐蚀环境作用的损伤累积/ 迟滞0 模型。与实验结果的比较表明损伤累积/ 迟滞0模型有较好的预测精度。     

PIB模型在空间碎片环境建模中的运用

运用“箱中粒子”模型（PIB）对空间碎片环境的演变趋势进行了研究。首先介绍了PIB半解析性的模型：在建模过程中，把空间碎片的运动视为在一巨大箱体中任意运动的粒子，有其自身输入输出机制；随后，对近地轨道碎片环境进行多层多种类碎片的划分，在此基础上将PIB模型运用于近地轨道环境中，建立多层，分类PIB模型；利用国外文献中的观测资料进行仿真，对未来空间碎片环境的演变作出了预测。     

对区域环境污染管理政策工具选择的理论再思考

和传统的污染缴费管理制度相比，排污许可权交易制度是一种比较有效的环境管理政策工具。然而，在当前的区域行政管理体制下，该制度并不是解决我国区域环境污染控制管理的最优政策选择。从严格的意义上讲，最优的环境污染控制管理政策应当是以征收污染排放税为主，而实行排污权交易则只能作为辅助手段。在任何一个税收制度或者排污权交易制度下，应当建立区域环境管理中心权威机构，以解决单个地区跨界污染问题。     

估算低周腐蚀疲劳寿命的几个模型

 本文基于Coffin-Manson原理,阐述了用于估算低周腐蚀疲劳寿命的5个计算模型,用这些模型拟合了7种工程材料的试验数据,讨论了拟合结果、模型精度和各自的适用范围。     

基于组装的过程工程环境

描述了一个基于组装的过程工程环境，该环境包括过程定义，过程实例化，过程模拟，过程动作４个部分，采用了基于组装的过程建模方法，能够对重用过程库中的过程部件进行组装，生成新的过程模型，并由过程模型驱动实际运作。     

大型空间环境模拟器冷氮气回收技术

文章结合大型空间环境模拟试验的特点对林德循环和克劳特循环两种液化方法进行改进,提出节流膨胀和涡轮膨胀两种回收方案。计算出它们的较佳运行参数,分析和比较了两个方案的技术性和经济性,为我国空间环境模拟设备冷氮气回收系统研制提供了有益的参考。     

航天器爆炸冲击环境及其模拟试验技术

介绍了航天器爆炸冲击环境的特点、环境预示方法、以及爆炸冲击试验模拟技术的发展现状。