Haze removal for UAV reconnaissance images using layered scattering model

During the unmanned aerial vehicles(UAV) reconnaissance missions in the middle-low troposphere, the reconnaissance images are blurred and degraded due to the scattering process of aerosol under fog, haze and other weather conditions, which reduce the image contrast and color fidelity. Considering the characteristics of UAV itself, this paper proposes a new algorithm for dehazing UAV reconnaissance images based on layered scattering model. The algorithm starts with the atmosphere scattering model, using the imaging distance, squint angle and other metadata acquired by the UAV. Based on the original model, a layered scattering model for dehazing is proposed. Considering the relationship between wave-length and extinction coefficient, the airlight intensity and extinction coefficient are calculated in the model. Finally, the restored images are obtained. In addition, a classification method based on Bayesian classification is used for classification of haze concentration of the image, avoiding the trouble of manual working. Then we evaluate the haze removal results according to both the subjective and objective criteria. The experimental results show that compared with the origin image, the comprehensive index of the image restored by our method increases by 282.84%, which proves that our method can obtain excellent dehazing effect.     

大气参数偏差对再入弹头爆点射程的影响

统计出了实际大气状态参数与标准大气状态参数的最大偏差值,以等高程和等过载引信两种弹头引信方式建立了大气参数偏差对弹道式导弹弹头引爆点射程影响的数学模型,从理论上分析了大气参数偏差对弹道式导弹弹头引爆点对应射程产生影响的物理实质;进而以一种洲际弹道导弹为例,讨论出大气参数偏差引起弹头命中点射程偏差的具体数值。     

分布式卫星轨道构形的大气摄动分析及修正方法

在低轨道运行的分布式卫星受大气摄动的影响,其轨道构形很快遭到破坏,环绕卫星的相对运动轨迹中心不断发生漂移。本研究的目的在于建立一种降低大气摄动对分布式卫星轨道构形影响的补偿方法,以使分布式卫星的轨道构形能够更好地自然维持。研究基于考虑高度变化和太阳周日变化的大气密度模型,得出分布式卫星不同初始相位环绕卫星的长半轴摄动方程。并提出一种补偿大气摄动影响的长半轴修正方法。仿真结果显示,采用此大气摄动补偿方法能够在给定时间内大大降低大气摄动的影响,从而显著提高分布式卫星轨道构形的自然维持能力。     

Updated TUS space fluorescence detector for study of UHECR

The TUS (Tracking Ultra-violet Set up) space fluorescence detector has to be launched in 2010 as a separated platform in Foton (Bion) mission prepared by the Samara enterprise. This detector was designed for another satellite and the updated variant of the TUS detector for a new platform is presented. The data on UV glow of the atmosphere obtained in operation of one pixel of the TUS detector on board the Moscow State University “Universitetsky-Tatiana” satellite was taken into account in design of the updated TUS detector. The data on UV transient flashes registered in “Universitetsky-Tatiana” mission are of special interest. Electronics of the TUS detector able to select and register different types of UV events in the atmosphere is presented.     

Origin and stability of lunar polar volatiles

Temperature regime at the LCROSS impact site is studied. All detected species in the Cabeus crater as well as CH₄ and CO clathrate hydrates except H₂, CO, and CH₄ are stable against evaporation at the LCROSS impact site. CO and CH₄ can be chemisorbed at the surface of the regolith particles and exist in the form of clathrate hydrates in the lunar cold traps. Flux rates of delivery of volatile species by asteroids, micrometeoroids, O-rich, C-rich, and low-speed comets into the permanently shadowed regions are estimated. Significant amounts of H₂O, CO, H₂, H₂S, SO₂, and CO₂ can be impact-produced during collisions between asteroids and O-rich comets with the Moon while CH₃OH, NH₃ and complex organic species survive during low-speed comet impacts as products of disequilibrium processes. C-rich comets are main sources of CH₄, and C₂H₄.     

北京地区大气温度及重力波活动的季节变化

利用瑞利激光雷达观测数据,分析了北京地区35~70km高度范围内大气温度和重力波活动的季节变化.发现北京地区30~70km高度范围内的大气温度有明显的年周期变化：平流层顶最高温度出现在6,7月份,大约为270K;中间层70km高度最低温度也出现在6,7月份,大约为200K.以2014年10月14日晚数据为例,分析重力波势能密度,发现50km以下重力波势能存在耗散,而在50km以上重力波近乎无耗散地向上传播.通过对比35~50km高度范围内的平均势能密度,对北京地区重力波活动强弱的季节变化进行了研究.研究结果表明,北京上空重力波活动强度具有明显的年周期变化,冬季平均势能密度为18J·kg^-1,夏季为8J·kg^-1,且冬季重力波活动强度约为夏季的两倍.此外,还分析了春夏秋冬四个季节重力波势能密度随高度的变化.结果表明,不同季节和不同高度的重力波势能密度不同.     

GNSS无线电掩星大气探测混合星座设计

针对目前GNSS无线电掩星大气探测卫星星座参数依赖大量仿真计算进行统计选取的研究现状,通过将探测卫星星下点与大气测点间地心角距作为观测半径提出了一种虚拟“星—地”遥感假设,给出了一种崭新的掩星测点预估方法,具有计算速度快的特点.基于该方法推导了探测星座参数与大气探测覆盖性之间的极值相关特性,建立了GNSS无线电掩星大气探测卫星星座设计准则,并以GPS和BD为兼容性观测信源完成了GNSS掩星大气探测混合卫星星座设计.通过仿真试验,验证了设计方法的快速性和可行性,GPS+BD掩星大气探测混合星座每日可实现掩星探测量为COSMIC星座的3倍以上,12h内掩星测点全球分布均匀度提升12％.     

环境介质对脉冲放电强化层厚度和硬度的影响

摘 要 本文通过在不同的环境介质下进行强化实验发现，在氮气和二氧化碳气氛中采用高脉冲能量强化可获得较厚的强化层，且强化层硬度明显高于空气中获得的强化层。另外二氧化碳和氮气相比，前者的强化层硬度更高些。     

Lakshita – Mining and research hub at L5

In this paper, the design of an orbital space settlement named Lakshita located at L5 for 10,000 residents having area of 1 × 10⁶ m² has been proposed, with the aim of fulfilling mining activities and space research in micro – g. All calculations are made in the perspective of a dynamic demography which could lead to the doubling of the population in next 25 years with initial population of 4500. The settlement consists of one residential torus, one agricultural torus, industrial cylinder and two docking cylinders rotating coaxially at 1 rpm. 2.3% of the total volume of settlement is provided for two docking cylinders with 6 docking ports enabling the elastic flow of space traffic, thereby providing continuous loading and unloading of cargo and passengers. Four pressurized sliding cylinders with 5.7 × 10⁵ m³ volume above the down surface area moving along the spokes fulfill the need of adaptation of visitors at half the gravity level of primary settlement volumes, as well provide wobble control. 1.1 × 10⁵ torr of pressure is provided above the down surface area of the residential torus. The power generation of 400 Mw, required for the functional need of Lakshita, will be obtained through SPS located at L4. The 14 h day and 10 h night cycle will be maintained by four mirrors attached on either side from the central cylinder. The walls of the settlement will be made up of three consecutive layers of super adobe, Nextel and Kevler-49 respectively to provide radiation and debris protection. An assortment of various facilities like appropriate distribution and management of water through an intended network of pipelines, accurate management of waste within the settlement has been provided.