Power considerations for long duration balloon flights

A solar panel, silicad battery power supply system is described which provided 100 W of power for a balloon borne solar neutron experiment. The system operated successfully on a 22 day circum-global RACOON flight launched from Australia in January 1983.     

A hard X-ray experiment for long-duration balloon flights

The Naval Research Lab has developed a balloon-borne hard X-ray experiment which is designed for 60- to 90-day flight durations soon to be available with around the world Sky Anchor or RACOON balloon flights. The experiment's scintillation detector is sensitive to the 15 – 250 keV X-ray energy range. The experiment includes three microcomputer systems which control the data acquisition and provide the orientation and navigation information required for global balloon flights. The data system supports global data communications utilizing the GOES satellite as well as high bit rate communications through L-band li line-of-site transmissions     

Power supplies for long duration balloon flights

Long duration balloon flights require more electrical power than can be carried in primary batteries. This paper provides design information for selecting rechargeable batteries and charging systems. Solar panels for recharging batteries are discussed, with particular emphasis on cells mounting suitable for balloon flights and panel orientation for maximum power collection. Since efficient utilization of power is so important, modern DC to DC power conversion techniques are presented.On short flights of 1 day or less, system designers have not been greatly concerned with battery weight. But, with the advent of long duration balloon flights using superpressure balloons, anchor balloon systems, and RACOON balloon techniques, power supplies and their weight become of prime importance. The criteria for evaluating power systems for long duration balloon flights is performance per unit weight. Instrumented balloon systems have flown 44 days. For these very long duration flights, batteries recharged from solar cells are the only solution. For intermediate flight duration, say less than 10 days, the system designer should seriously consider using primary cells.     

Kinematics of Saturn's spokes

Voyager 2 images of Saturn's rings have been analyzed for spoke activity. More than 80 and 40 different spokes have been measured at the morning and at the evening ansa, respectively. Higher rate of spoke formation has been found at 145° ± 15° SLS and at 305° ± 15° SLS which persisted for at least 3 Saturn revolutions. Higher spoke activity (formation and growth in width) by more than a factor 3 has been observed over the nightside hemisphere of Saturn than over the dayside hemisphere. The age distribution (i.e. time from radial formation until observation, assuming Keplerian shear) of the leading (old) edges of spokes has its maximum at ～ 9,000 s and ～ 6,000 s for spokes observed at the morning ansa and at the evening ansa, respectively. The highest spoke age observed is ～ 20,000 s. The age distribution of the trailing (young) edges of spokes peaks at < 2,000 s at both ansae but has its mean at ～ 4,500 s and ～ 3,500 s, respectively. On the average the observed spokes grew in width for ～ 4,500 s at the morning ansa and for ～ 2,500 s at the evening ansa. The maximum time of growth in width was ～ 12,000 s.     

Interpretation of 6 and 21 cm observations of Jupiter

Observations of Jupiter's radio emission were made at a frequency of 1412 MHz (21cm) in 1977 and at 4885 MHz (6cm) in 1978 using the Westerbork Synthesis Radio telescope in the Netherlands. The thermal disk temperatures at these wavelengths yield values of 320±20 K at 21 cm and 220±8 K at 6 cm. The first value requires an overabundance of ammonia by a factor of three with respect to the solar value, the second one is in agreement with the value expected for a convective model atmosphere with solar abundances for all chemical elements. The data at this wavelength however show no or very little limb darkening on the planet, indicating that there is a layered rather than a uniformly mixed atmosphere. A sudden increase in the ammonia abundance by a factor of about three below the 210–220 K level is proposed to explain this fact and also both derived disk temperatures.     

Modeling of ionospheric parameter variations in East Asia during the moderate geomagnetic disturbances

The results of modeling of ionospheric disturbances observed in the East Asian region during moderate storms are presented. The numerical model for ionosphere–plasmasphere coupling developed at the ISTP SB RAS is used to interpret the data of observations at ionospheric stations located in the longitudinal sector of 90–130°E at latitudes from auroral zone to equator. There is obtained a reasonable agreement between measurements and modeling results for winter and equinox. In the summer ionosphere, at the background of high ionization by the solar EUV radiation in the quiet geomagnetic period the meridional thermospheric wind strongly impacts the electron concentration in the middle and auroral ionosphere. The consistent calculations of the thermospheric wind permit to obtain the model results which are closer to summer observations. The actual information about the space-time variations of thermosphere and magnetosphere parameters should be taken into account during storms.     

GNSS single frequency ionospheric range delay corrections: NeQuick data ingestion technique

A study of the performance of the NeQuick model and the Klobuchar model for GNSS single frequency range delay correction on a global scale was done using data for moderate solar activity. In this study NeQuick was used in the way intended for Galileo. This study is to assess the performance of the two models at each ionospheric geographic region during moderate solar activity as previously published studies were concentrated only on high solar activity. The results obtained showed that NeQuick outperformed Klobuchar for the whole year at the three geographical regions of the ionosphere. In terms of monthly root mean square of mismodeling, NeQuick outperformed Klobuchar by 15 TECU or more at low-latitudes, 5 TEC or more at mid-latitudes, and 1 TECU or more at high-latitudes.     

Sunspot numbers,interplanetary magnetic field,and cosmic ray intensity at earth: Nexus for the twentieth century

The pivotal role played by the interplanetary magnetic field (B) in modulating galactic cosmic ray (GCR) intensity in the heliosphere is described. We show that the inverse correlation observed by Forbush (1958) between GCRs and sunspot numbers (SSNs) is reflected in high correlation between SSNs and B (cc = 0.94). The SSN data are available since 1700 and the derived B data since 1835. The paleo-cosmic ray data are available for several millennia in the form of ¹⁰Be radionuclide sequestered in polar ice. The data of the ion chambers (ICs) at the Cheltenham–Fredericksburg–Yakutsk (CFY) sites are combined to create a data string for 1937–1988. In turn, these data are used to extend the measurements of the low energy GCR ions (>0.1 GeV) at balloon altitudes at high latitudes in Russia to 1937. These data are then correlated to B and the fit parameters are used to extend the low energy ion data to 1900, creating the instrumental era GCR time series for the twentieth century. The derived GCR time series is compared to ¹⁰Be measured at two sites in Greenland, namely Dye 3 and NGRIP for 1900–2000 to check the internal consistency of datasets for the long-term trend. We find that the annual mean rate (%) for 1965 at NGRIP is an outlier. We replace it with the mean of 1964 and 1965 rates and construct a new re-normalized time series at NGIP, improving the agreement with the derived instrumental era GCR time series for the twentieth century as well. This should encourage its use by heliophysics community for varied applications.     

Hemispheric,seasonal and latitudinal dependence of storm-time ionosphere during low solar activity period

Analysis of the seasonal, hemispheric and latitudinal variation of the ionospheric F2 peak during periods of disturbed geomagnetic conditions in 2011, a year of low solar activity, had been studied using hourly data obtained from low- and mid-latitude ionosonde stations. Our results showed an enhancement in F2-layer maximum electron density (NmF2) at daytime over low latitudes. For the mid-latitude stations, NmF2 depletion pre-dominates the daytime and overturned at nighttime. In general, the variation in terms of magnitude is higher in the low-latitude than at mid-latitude. The nighttime decrease in NmF2 is accompanied by a corresponding F2 peak height (hmF2) increase and overturned at daytime. The hmF2 response during the equinoctial months is lower than the solstices. NmF2 shows distinct seasonal, hemispheric and latitudinal dependence in its response. Appearance of a significant ionospheric effect in southern hemisphere is higher than in the northern hemisphere, and is more pronounced in the equinoxes at low latitudes. At mid-latitudes, the ionospheric effect is insignificant at both hemispheres. A negative ionospheric response dominates the whole seasons at the mid-latitude except for March equinox. The reverse is the case for the hmF2 observation. The amplitudes of both the NmF2 and hmF2 increase with increasing latitude and maximize in the southern hemisphere in terms of longitude.     

High precision orbits for the international GPS service for geodynamics (IGS)

The objectives of the IGS include the regular computation of precise orbits for the GPS satellites, an essential prerequisite for geodetic, geophysical and navigation applications of GPS relying on accuracies at the level of metres to centimetres. This involves the deployment of advanced GPS receivers at a considerable number of globally distributed ground points, including several ESA tracking sites; the largely automated daily retrieval and processing of large amounts of remotely generated data; and regular independent comparisons of solutions computed by the various participating analysis centres, showing for example differences of typically 15 cm in solutions for all orbits in the GPS constellation. The paper reviews the IGS activities being carried out at ESOC in the context of the overall service.     

氮氧化物羽烟在电离层局部的光热效应

在航天器羽烟一次性抛出和呈球状近似情况下,模拟了电离层E层NO羽烟与周围大气压力平衡时的最大亮度及其随时间的变化．在110km抛出的5molNO羽烟可使它获得瞬时夜间中等偏强极光那样的亮度,在140km抛出的同样数量的NO羽烟亮度却急剧地减弱．还模拟了白天夜间温度为1000K的NO2羽烟在190km和250km两个高度、50mol和500mol两种抛出总量所造成的局部大气温度短时间内的下降．在F层下部,夜间较大抛出量所造成的冷却效应是显著的．     

Effects of air velocity on photosynthesis of plant canopies under elevated CO2 levels in a plant culture system.

To obtain basic data for adequate air circulation for promoting plant growth in closed plant production modules in bioregenerative life support systems in space, effects of air velocities ranging from 0.1 to 0.8 m s-1 on photosynthesis in tomato seedlings canopies were investigated under atmospheric CO2 concentrations of 0.4 and 0.8 mmol mol-1. The canopy of tomato seedlings on a plug tray (0.4 x 0.4 m2) was set in a wind-tunnel-type chamber (0.6 x 0.4 x 0.3 m3) installed in a semi-closed-type assimilation chamber (0.9 x 0.5 x 0.4 m3). The net photosynthetic rate in the plant canopy was determined with the differences in CO2 concentrations between the inlet and outlet of the assimilation chamber multiplied by the volumetric air exchange rate of the chamber. Photosynthetic photon flux (PPF) on the plant canopy was kept at 0.25 mmol m-2 s-1, air temperature at 23 degrees C and relative humidity at 55%. The leaf area indices (LAIs) of the plant canopies were 0.6-2.5 and plant heights were 0.05-0.2 m. The net photosynthetic rate of the plant canopy increased with increasing air velocities inside plant canopies and saturated at 0.2 m s-1. The net photosynthetic rate at the air velocity of 0.4 m s-1 was 1.3 times that at 0.1 m s-1 under CO2 concentrations of 0.4 and 0.8 mmol mol-1. The net photosynthetic rate under CO2 concentrations of 0.8 mmol mol-1 was 1.2 times that under 0.4 mmol mol-1 at the air velocity ranging from 0.1 to 0.8 m s-1. The results confirmed the importance of controlling air movement for enhancing the canopy photosynthesis under an elevated CO2 level as well as under a normal CO2 level in the closed plant production modules.     

纤维增强熔模铸造复合型壳的性能及断口形貌

为提高熔模铸造硅溶胶型壳的强度性能,采用天然植物/硅酸铝双纤维来增强熔模铸造型壳.将质量比为1:1天然植物/硅酸铝双纤维加入到制壳用涂料中来制备型壳试样,对不同纤维加入量条件下所获得的纤维增强型壳试样的常温强度、不同温度焙烧后的抗弯强度及高温自重变形量的变化规律进行了研究,并利用SEM观察型壳试样断口形貌.结果表明,当纤维加入量从0.2%逐渐增加到1.0%时,其常温抗弯强度先增加后减小;纤维加入量为0.6%时其常温抗弯强度值达到2.94 MPa.高温自重变形量则先减小后增大.加入0.6%纤维的增强型壳试样经900℃焙烧后,其抗弯强度达4.04 MPa,与未采用纤维增强的型壳试样的抗弯强度接近.断口形貌观察结果表明,纤维增强硅溶胶型壳试样受力破坏失效主要由于硅溶胶凝胶膜的断裂、硅酸铝纤维拔出、断裂及脱粘等综合作用所致.     

Numerical model for thermal and solutal convection and multizone physical vapour transport

Theoretical and numerical solutions are proposed for the prediction of the thermal and solutal convection in a long horizontal ampoule in the presence of local temperature gradients at the walls as involved in the multizone furnace applications. A finite difference method is used for a Boussinesq fluid in a two-dimensional cavity with modelized wall temperature gradients, locally applied. The results are carried out without and with an interfacial mass flux at the source and sink. A seed has been also modelized at the horizontal walls.     

航空供氧系统高空性能参数数值仿真

根据航空供氧系统高空性能的工作原理,利用理论简化结构模型和气体动力学知识,建立了供氧系统部分高空性能参数的数学模型.在Matlab/Simulink系统仿真环境下,对高空部分性能参数进行了数值仿真计算,分析了高空性能中的充氧时间控制以及供氧面罩余压与拉力管内压力的比值特性和各种结构参数对面罩余压大小的影响.通过对仿真计算结果与试验结果的对比分析,表明所建立的数学模型是有效的,采用的仿真计算方法符合计算精度要求,对供氧系统高空性能的设计和改进工作具有一定的参考作用.     

高纬磁层顶尾部边界层的离子流剪切不稳定性

研究了高纬磁层顶层部边界层在非均匀磁场条件下的离子流剪切不稳定性，由于考虑了尾向电流，我们发现离子流剪切不稳定性的激发与扰动波长有关，并得到了激发该不稳定性的准临界波长的表达式，对于磁层顶存在的波长为地球半径量级的表面波扰动，离子流剪切不稳定性倾向于发生在磁层顶边界层的内边界，沿磁层顶外边界传播的稳定的表面波和其内边界的离子流剪切不稳定性同时存在，这将有助于解释磁鞘太阳与动量持续不断地向地磁层的传输。     

低高度内辐射带高能质子空间分布位形的研究

利用国际地磁参考场模式(IGRF模式)分析了1970-2000年低高度南大西洋负磁异常区位形的漂移与变化，给出了几个高度异常区中心位置磁场强度的变化和位置的变化。利用带电粒子的运动学方程，简要分析了低高度辐射带高能粒子的运动，得出在低高度，磁场是决定辐射带高能粒子空间强度与分布的决定性因素．低高度辐射带空间分布位形的变化特征应该与低高度南大西洋负磁异常区的变化特征基本一致．低高度南大西洋负磁异常区的特征可以作为低高度辐射带空间分布位形的一个初步判据。     

GSO卫星系统布设中的通信干扰评估方法

针对地球静止轨道（GSO）卫星系统在卫星和地球站布设中的同频干扰评估问题，设计了地球站及卫星的全球分布对下行和上行通信链路的干扰评估场景，以及考虑波束业务特征影响的多条链路的集总干扰场景，构建了不同场景下的干扰评估和分析计算的模型，提出了一种基于干扰函数极值的评估方法。所提方法通过建立干扰系统地球站的随机分布集合和受扰系统的干扰函数，结合国际电联（ITU）提供的全球地形数据、天线波束参数、电磁波传播模型，能够实现对2个GSO卫星系统间的卫星轨位和地球站布设的定量化计算分析。采用所提方法对位于47°E±6°的GSO卫星系统、位于（23°N，26°E）地球站的同向下行链路，以及位于（23°N，26°E）的地球站对26°E±6°的GSO卫星系统的同向上行链路的干扰情况进行了定量化计算。结果表明:在卫星轨位间隔为2°时的干扰噪声比值为-12.29 dB，与ITU建议书中规定的-12.2 dB的限值之间的误差为0.7%，证明了所提方法的有效性和可行性。所提方法还可以统计GSO卫星系统在任意角度间隔和全球布设场景下的干扰分布情况，对于干扰评估和规避措施的制定具有一定的借鉴意义。      

First estimations of the aerosol optical thickness using Langley Method at Southern Brazil (29.4°S, 53.8°W)

The first estimations of the aerosol optical thickness (AOT) using Langley Method at Southern Space Observatory (SSO) at Southern Brazil (29.4°S, 53.8°W) are presented. In addition to ozone and sulphur dioxide columns, AOT can be obtained using Brewer Spectrophotometer at specific wavelengths: 306.3, 310.1, 313.5, 316.8 and 320.1 nm. The AOT was obtained for the period from November/2002 to May/2003. Very low AOT averages were obtained, whose values were about 0.21 ± 0.03 at 306.3 nm, 0.21 ± 0.02 at 310.1 nm, 0.19 ± 0.02 at 313.5 nm, 0.20 ± 0.02 at 316.8 nm and 0.20 ± 0.02 at 320.0 nm for all period analysed. Different behaviour of AOT were obtained at two daily specific periods of aerosol accumulation, one in the afternoons from November/2002 to February/2003, caused mainly by a mild biomass burning season’s in the region and other in the mornings from March to May/2003, due the high relative humidity presented in the region studied.     

Voyager photopolarimeter observations of Saturn and Titan

The Voyager 2 photopolarimeter experiment observed the intensity and polarization of scattered sunlight from the atmospheres of Saturn and Titan in the near-UV at 2640 Å and in the near-IR at 7500 Å. Measurements of Saturn's limb brightening and polarization at several phase angles up to 70° indicate that a significant optical depth of UV absorbers are present in the top 100 mbar of Saturn's atmosphere in the Equatorial Zone and north polar region, and possibly at other latitudes as well. UV absorbers are prominent in polar regions, suggesting that charged particle precipitation from the magnetosphere may be important in their formation.The whole-body polarization of Titan is strongly positive in both the UV and near IR. If spherical particles are responsible for the polarization, no single size distribution or refractive index can account for the polarization at both wavelengths. The model atmosphere proposed by Tomasko and Smith [1], characterized by a gradient in particle size with altitude, seems capable of explaining the Voyager observations. If non-spherical particles predominate, the Voyager observations place important constraints on their scattering properties.