Space Weather Research in China

Recent progress in space weather research are briefly presented here from three aspects: establishment or improvement in observation systems, such as extra-soft X-ray detector and γ-ray detector onboard the spacecraft ‘Shen Zhou 2’, new solar radio broad-band spectrometer, magnetometer-chain, ionosonde and digisonde–chain, laser-lidar system and VHF radar; partial topic progresses included in CMEs, multi-streamer structures, evolution of interplanetary magnetic field B _z component, regional properties of traveling ionospheric disturbances, a fully-nonlinear global dynamical model for the middle and upper atmosphere, and a combined prediction method for geomagnetic disturbances; and space weather activity, such as ‘Meridian Project’ — a national major scientific project, ‘International Space Weather Meridian Circle Program’ — a suggestion of internationalization of ‘Meridian Project’, ‘Space Weather Research Plan’ — a major research plan from National Natural Science Foundation of China (NNSFC) and other space weather activities. This revised version was published online in August 2006 with corrections to the Cover Date.     

Remote sounding of atmospheric gravity waves with satellite limb and nadir techniques

Recent advances in satellite techniques hold great potential for mapping global gravity wave (GW) processes at various altitudes. Poor understanding of small-scale GWs has been a major limitation to numerical climate and weather models for making reliable forecasts. Observations of short-scale features have important implication for validating and improving future high-resolution numerical models. This paper summarizes recent GW observations and sensitivities from several satellite instruments, including MLS, AMSU-A, AIRS, GPS, and CLAES. It is shown in an example that mountain waves with horizontal wavelengths as short as 30 km now can be observed by AIRS, reflecting the superior horizontal resolution in these modern satellite instruments. Our studies show that MLS, AMSU-A and AIRS observations reveal similar GW characteristics, with the observed variances correlated well with background winds. As a complementary technique, limb sounding instruments like CRISTA, CLAES, and GPS can detect GWs with better vertical but poorer horizontal resolutions. To resolve different parts of the broad GW spectrum, both satellite limb and nadir observing techniques are needed, and a better understanding of GW complexities requires joint analyses of these data and dedicated high-resolution model simulations.     

检定模拟示波器测量不确定度评定

对模拟示波器的主要性能参数（垂直偏转系数、扫描时间系数、脉冲瞬态响应）的不确定度评定做了详细介绍。     

Three-dimensional transgenic cell model to quantify genotoxic effects of space environment.

In this paper we describe a three-dimensional, multicellular tissue-equivalent model, produced in NASA-designed, rotating wall bioreactors using mammalian cells engineered for genomic containment of multiple copies of defined target genes for genotoxic assessment. Rat 2 lambda fibroblasts, genetically engineered to contain high-density target genes for mutagenesis (Stratagene, Inc., Austin, TX), were cocultured with human epithelial cells on Cytodex beads in the High Aspect Ratio Bioreactor (Synthecon, Inc, Houston, TX). Multi-bead aggregates were formed by day 5 following the complete covering of the beads by fibroblasts. Cellular retraction occurred 8-14 days after coculture initiation culminating in spheroids retaining few or no beads. Analysis of the resulting tissue assemblies revealed: multicellular spheroids, fibroblasts synthesized collagen, and cell viability was retained for the 30-day test period after removal from the bioreactor. Quantification of mutation at the LacI gene in Rat 2 lambda fibroblasts in spheroids exposed to 0-2 Gy neon using the Big Blue color assay (Stratagene, Inc.), revealed a linear dose-response for mutation induction. Limited sequencing analysis of mutant clones from 0.25 or 1 Gy exposures revealed a higher frequency of deletions and multiple base sequencing changes with increasing dose. These results suggest that the three-dimensional, multicellular tissue assembly model produced in NASA bioreactors are applicable to a wide variety of studies involving the quantification and identification of genotoxicity including measurement of the inherent damage incurred in Space.     

环境气象条件对光学探测器性能的影响研究

环境气象条件对光学探测器的性能影响很大。针对南、北方的典型气象条件计算了两个波段下的大气透过率和天空辐射亮度,给出了大气环境条件对探测器探测能力的影响分析。     

单推三分析化验误差来源研究

单推三分析化验误差来源是多方面的,确定单推三分析过程误差来源,能为操作人员提供减少或消除误差的依据。影响单推三分析结果的主要因素有几个:标准溶液浓度的变化,滴定过程各终点的读数,环境温度的变化。在分析化验过程中,第一终点读数对硝酸肼、氨的分析结果不产生影响,但对肼有影响;第二终点读数对肼、氨分析结果有影响,但对硝酸肼无影响;第三终点读数对上述三种物质的分析结果都有影响,尤其是硝酸肼,其分析化验结果很容易超出要求范围。     

Performance evaluation of GPS augmentation using Quasi-Zenith Satellite System

The current global positioning system (GPS) provides limited availability and capability for a country like Japan where mountainous terrain and urban canyons do not allow a clear skyline to the horizon. At present, the Japanese Quasi-Zenith Satellite System (QZSS) is under investigation through a cooperative effort between the government and the private sector. QZSS is considered a multi-function satellite system, as it is able to provide communication, broadcasting, and positioning services for mobile users in a specified region with a high elevation angle. The additional GPS compatible signals from QZSS can remarkably improve the availability, accuracy, and capability of GPS positioning. This work focuses on the performance of GPS augmentation using the proposed QZSS. The QZSS satellite constellation and signal structure are briefly reviewed. Positioning with pseudo-range and carrier phase are discussed. The performance of GPS augmentation using QZSS in the Asian-Pacific and Australian area is studied using software simulations. The results are presented using the number of visible satellites as a measure of availability, GDOP as a measure of accuracy, and ambiguity success rate as a measure of capability of carrier-phase-based positioning with spatial and temporal variations. The results show that the QZSS will improve not only the availability and accuracy of GPS positioning, but will also enhance the capability of the GPS carrier-phase-based positioning in Japan and neighboring regions.     

不满足匹配条件的不确定离散系统的鲁棒控制

研究了一类不满足匹配条件的不确定离散系统的二次鲁棒镇定问题，系统的不确定部分为时变、范数有界。通过求解离散代数Riccati方程获得鲁棒镇定增益阵，同时，此Riccati方程的对称正定解也是建立闭环系统渐近稳定性的Lyapunov矩阵。所获得的结论与现有的结果相比，不需要引入增广系统或辅助系统，就可以解决同时含有状态矩阵和输入矩阵不确定性的离散系统的鲁棒镇定问题，本结果可以看成是以前获得的关于连续系统鲁棒镇定结果的离散系统对应。     

Frequency-controlled series-resonant converter with synchronous rectifier

This paper presents an analysis and experimental results for a frequency-controlled series-resonant dc-dc converter that consists of a Class-D zero-voltage-switching (ZVS) series-resonant inverter and a center-tapped synchronous rectifier. If the dc output voltage is low, the efficiency of the converter is dominated by the efficiency of the rectifier. Low on-resistance metal-oxide-semiconductor field-effect transistors (MOSFETs) are used in the rectifier instead of diodes because the forward voltage drop across the rectifying device is low, resulting in a high efficiency. The dc output voltage is regulated against variations in the load resistance and the dc input voltage by varying the operating frequency. Experimental results are presented for a converter with a dc input voltage of 150 V, an output voltage of 5 V, and a dc load resistance ranging from 0.5 to 5.5 R. The measured efficiency was 86% for a 50 W output and 89% for a 25 W output. The theoretical results were in good agreement with the measured results.     

无人机雷达散射截面的数值模拟及突防分析

用数值模拟的方法获得了无人机雷达散射截面的空间分布，建立了无人机突防的数学模型，并对其突防能力进行了分析。