Mirror Mode Waves Downstream of a Stream Interaction Region Forward Shock near 1 AU

Mirror mode waves in the solar wind are typically observed not as quasi-periodic sinusoidal signatures, but as trains of nonperiodic structures of two types: magnetic ??peaks?? and magnetic ??dips.?? Some trains of long durations have been called mirror mode storms. In this work we report mirror mode waves downstream of a stream interaction region (SIR) forward shock observed near 1?AU on 7?May 2007 with Solar Terrestrial Relations Observatory (STEREO) and Time History of Events and Macroscale Interactions during Substorms (THEMIS) data. The high-resolution magnetic-field data (0.125-second resolution) from STEREO are scanned to search for magnetic dips and peaks (or upgoing magnetic ??mesas??) in the solar wind. STEREO-A observes a mirror mode storm: the appearance of mirror mode waves (mainly magnetic peaks and upgoing mesas) is simultaneous with the entry into a high-density, high-temperature, and high plasma ?? accompanied by a depressed field region; the magnetic dips survive in the lower plasma-?? region. STEREO-B observes mirror mode waves (mainly magnetic peaks) with different amplitudes and asymmetric forms, which can survive in a low plasma ?? region. THEMIS-D, which was located in the solar wind, also observes mirror mode waves (mainly magnetic peaks and upgoing mesas) as well as an enhanced ion temperature anisotropy (T _????3T _??). The enhanced ion temperature anisotropy and high plasma ?? satisfy the mirror-instability criterion. These observations of STEREO and THEMIS-D show that mirror mode waves can be excited downstream of a SIR forward shock near 1?AU.     

Statistical analysis of the optical variability of QSO's

For 34 QSOs and 9 active galaxies with known optical variation and measured redshifts, the rate of optical variation appears to be positively correlated with the age: older quasars vary more violently than younger ones and active galaxies are the most violent of all.     

介质横向不均匀对震后地表位移场的影响

利用三维有限元模拟两层地球模型(包括弹性层和粘弹性层)介质的横向不均匀和断层错动的复杂性对震后地表位移场的影响，其数值结果包括弹性解和粘弹性解。结果表明，震后位移场的分布特征不仅与粘弹性层的流变特性有关，还与弹性层介质的剪切模量以及断层的同震错动有关。     

Alternative Fuzzy Cluster segmentation of remote sensing images based on Adaptive Genetic Algorithm

Remote sensing image segmentation is the basis of image understanding and analysis. However, the precision and the speed of segmentation can not meet the need of image analysis, due to strong uncertainty and rich texture details of remote sensing images. We proposed a new segmentation method based on Adaptive Genetic Algorithm (AGA) and Alternative Fuzzy C-Means (AFCM). Segmentation thresholds were identified by AGA. Then the image was segmented by AFCM. The results indicate that the precision and the speed of segmentation have been greatly increased, and the accuracy of threshold selection is much higher compared with traditional Otsu and Fuzzy C-Means (FCM) segmentation methods. The segmentation results also show that multi-thresholds segmentation has been achieved by combining AGA with AFCM.     

A comprehensive evaluation of tourism climate suitability in Qinghai Province, China

Qinghai Province is an important component of the Qinghai-Tibet Plateau in China. Scientific evaluation of the suitability of Qinghai’s climate for tourism can contribute to overcoming obstacles posed by climate on sustainable tourism development in Qinghai Province, including disparities between the low and high seasons, high altitude health concerns, and weather events. A tourism climate suitability evaluation model of the Qinghai-Tibet Plateau is constructed (Tourism Climate Suitability Index, or TCSI), and tourism climate suitability is comprehensively evaluated for Qinghai Province from climate data from 1960 to 2009. Results show that: (I) There is clear distributional characteristics of spatial-temporal variability of TCSI values in Qinghai Province. (II) Tourism climate suitability in Qinghai Province has significant seasonal and regional differences. The year is divided into a very suitable period (July and August), suitable tourism periods (from April and October), less suitable periods (From Nov to Mar). June to August is the most suitable tourism period in Qinghai. Qinghai Province is divided into five levels of tourism climate suitability: most suitable regions, very suitable regions, suitable regions, less suitable regions, and unsuitable region. (III) The key factor which influences regional differences in tourism climatic suitability is atmospheric oxygen. And the key factors which chiefly influence seasonal differences of tourism climate suitability are temperature and humidity, the wind chill factor, and barrier weather.     

Application of nonlinear optimization technique to back analyses of deep excavation

This study presents a nonlinear optimization technique (NOT) for conducting the back analyses of geotechnical engineering problems based on the field observations. Additional auxiliary techniques are incorporated to enhance the convergence and stability of the NOT. The developed NOT and additional auxiliary techniques are incorporated into a finite element code and then applied to the back analysis of excavation-induced wall deflection. A number of hypothetical excavation cases with various scenarios of stratigraphy and two quality excavation case histories are used to validate the developed NOT, in which the dominant soil parameters are treated as target parameters. Results show that the wall deflections of all hypothetical and actual excavation cases at each stage can be accurately and efficiently back-figured. The developed NOT has a potential to be an useful tool for preventing the building damage through accurately and efficiently predicting the excavation-induced deformations at subsequent stages.     

基于L1范数凸二次规划方法的航空重力测量数据稀疏重构（英文）

由于受到国界、测量成本和数据规模等因素的限制,航空重力测量本质上是一种欠奈奎斯特采样方法,本文通过离散傅里叶变换分析了航空重力测量的稀疏性,提出了利用压缩感知理论实现大规模重力异常数据高精度重构的思路。基于压缩感知理论,重力异常数据重构问题可以转化为基于L1范数的凸二次规划问题,本文结合预处理共轭梯度算法,提出了一种改进的内点法来解决此问题。进一步地,我们利用自主研发的SGA-WZ型捷联式航空重力仪在中国某地区进行了航空重力测量试验。通过对试验中测得的重力异常数据进行重构,与常用的线性插值重构方法对比,结果表明:本文提出的基于压缩感知理论的新方法能够以更高的重构精度,更有效地解决大规模重力异常数据的重构问题。     

拓宽古生物研究领域

现代古生物学应加强横向联系,与其他有关学科相互渗透,扩大研究领域,拓宽研究内容、利用新技术,包括数学的、物理的、化学的以及现代生物学的理论和研究方法与沉积岩石学研究结合起来,提高古生物学的理论基础,给国家生产建设提供可靠的基础资料。     

2000国家GPS大地控制网数据处理方法与结果

介绍了我国GPS大地控制网的基本情况,阐述了结合地壳运动观测网络工程建立全国统一的“2000国家GPS大地控制网”的意义,并介绍了整网平差中采用的技术方法和最后平差结果及精度。