GNSS多天线基线网单历元模糊度同步解算法

提出多天线基线网单历元模糊度同步解算法，其具体实现步骤为：1）根据宽巷组合模糊度易于固定的优点，采用附加已知基线长度约束法同步解算各基线的宽巷模糊度，得到dm~cm级精度的近似基线分量；2）将解算得到的各近似基线分量作为约束，同步解算各基线的基频模糊度，以获取mm级精度的基线矢量。该方法的关键在于检验各历元宽巷模糊度解算的正确性，以获取可靠的近似基线分量，为解算各基线的基频模糊度提供准确的基线先验信息。由于动态情况下各历元观测信息比较少，单纯依赖ratio检验不可靠，提出结合基线误差、单位权中误差、基线网模糊度闭合环及ratio值等对多组宽巷模糊度进行检验，避免ratio值设置不当导致模糊度检验中发生纳伪和弃真问题。实测数据结果证明，该处理方法使得模糊度解算的成功率提高1%~2%，可以获取移动平台更丰富的导航信息，提高其服务能力。     

Helmert方差分量估计在GPS/GLONASS/BDS组合定位权比确定中的应用

因GNSS系统间观测噪声、轨道精度的差异，采用经验权比进行组合定位难以得到最优结果。基于此，在GPS/GLONASS/BDS组合定位中引入Helmert方差分量估计，对GPS/GLONASS/BDS组合单点定位和基线解算中各系统观测值进行合理定权。实验表明，采用该方法确定的伪距观测值最佳权比为5∶1∶1，相位观测值最佳权比为1∶1∶1，有效提高了GPS/GLONASS/BDS组合定位的精度和可靠性。     

A case study on Landscape Component Niche based on Landscape Pattern Indices: Yanchi,Ningxia Province,China

Yanchi County is located in the agro-pastoral ecotone and belongs to the ecologically fragile area of Northwest China.It is important to study the evolution of landscape pattern to curb its environmental degradation.In order to intuitively show how the landscape pattern of the study area changes over time,Landsat Thematic Mappers(TM)and Landsat Operational Land Imager(OLI)data of 1991,2000,2010 and 2017 were used.This paper attempts to apply niche theories and methods into landscape ecology,and constructs a niche model of landscape components by using"n-dimentional hypervolume niche theory"and landscape pattern indices.By evaluating the spatial and temporal evolution of niche from the perspective of two-dimensional space to reflect the changes of landscape pattern in the study area over the past 26 years,new theories and methods were introduced for the characterization of landscape pattern.The results indicate that:1)The larger the attribute and dominance value of landscape components,the higher the ecological niche and the stronger the control effect on the overall landscape.2)The ecological niche of each landscape component was significantly different,just as its control effect on the overall landscape.3)The dynamic change of the ecological niche of each landscape component was different,with grassland,unused land and arable land always in a high dominant position,although the ecological niche of construction land and water area was always low.In general,the introduction of niche theory into the landscape ecology provided a new method to study the changes in regional landscape pattern.     

基于 SRP 概念模型的祁连山地区生态脆弱性评价

基于生态敏感性-生态恢复力-生态压力度（SRP）概念模型，从地形、气候、植被和社会经济 因子选取 8 个评价指标，利用遥感和 GIS 技术，采用主成分分析方法求取权重，对祁连山地区启动 水源涵养区生态环境保护和综合治理规划研究前后近 10 a 的生态脆弱性程度进行系统、定量地评 估，旨在揭示生态脆弱性的分布特征、时空演变及动因，为区域生态保护、资源利用和可持续发展 提供参考。结果表明：（1）从研究区生态脆弱性分布来看，祁连山地区主要以轻度和重度脆弱为 主，脆弱性程度从西北向东南地区逐渐减弱，西北地区植被覆盖度小，海拔高，生态环境较为恶劣 是导致脆弱性程度较高的原因；（2）祁连山地区 3 期生态脆弱程度呈逐渐下降趋势，综合指数分别 为 3.307、3.118 和 3.103；2005 年 生 态 脆 弱 性 较 高 ，极 度 脆 弱 面 积 为 28 610 km²，2010 年 下 降 为 11 723 km²，2015 年降低为 6 174 km²，极度脆弱面积逐渐减少；（3）从祁连山地区生态脆弱性演变动 因来看，8 个指标对生态脆弱性影响均较为显著，但在不同的时间影响程度各不相同，2005—2015 年 3 期数据中对生态脆弱性影响最大的均为植被指数，降水次之，地形因子影响最小。总体来看， 近年来祁连山地区生态脆弱性程度有所降低，但仍然需要加强保护力度，促进生态环境可持续 发展。     

Muon density measurements with the KASCADE central detector

Frequency distributions of local muon densities in high-energy extensive air showers (EAS) are presented as signature of the primary cosmic ray energy spectrum in the knee region. Together with the gross shower variables like shower core position, angle of incidence, and the shower sizes, the KASCADE experiment is able to measure local muon densities for two different muon energy thresholds. The spectra have been reconstructed for various core distances, as well as for particular subsamples, classified on the basis of the shower size ratio N_μ/N_e. The measured density spectra of the total sample exhibit clear kinks reflecting the knee of the primary energy spectrum. While relatively sharp changes of the slopes are observed in the spectrum of EAS with small values of the shower size ratio, no such feature is detected at EAS of large N_μ/N_e ratio in the energy range of 1–10 PeV. Comparing the spectra for various thresholds and core distances with detailed Monte Carlo simulations the validity of EAS simulations is discussed.     

Variability of Soft X—ray Spectral Shape in Blazars Observed by ROSAT

1 INTRODUCTION Blazars, including BL Lac objects, highly polarized and optically violently variable quasars,and flat-spectrum radio quasars (FSRQs), are characterized by highly variable non-thermalemission which dominates their characteristics from radio to y-ray bands. The mechanismbelieved to be responsible for their broadband emission is synchrotron radiation followed by in-verse Compton (IC) scattering at higher energies (e.g. Blandford & Konigl 1979). Relativisticbeaming of a jet…     

江汉盆地钻孔测井资料确定地应力最大水平主压应力方向

利用钻孔测井资料并运用地层倾角测量信息分析法，给出了江汉盆地地应力最大水平主压应力方向为ＮＥ６０～６５°     

盘山山前地下水与矿泉水污染成因分析

文章利用主成分分析方法,结合揭示变量和样品之间在成因或空间上联系的对应分析,通过SPSS统计分析软件,对盘山山前地区地下水和矿泉水污染成因进行分析。研究表明,盘山山前存在地下水和矿泉水污染;局部范围的污染主要是由于食品厂等企业的排污引起的,污染成分主要是Cl-和NO3—N,主要污染地区是塔院地区,其次是西大佛塔至南营,污染程度与至污染源的距离有关;大部分地区存在三氮面状污染,农业氮肥的施用是其主要原因。     

"868"菌粉作饲料添加剂提高甲鱼免疫力

以0.5％量添加"868"菌粉作甲鱼饲料添加剂，喂养3个月，用甲醛灭活的嗜水气假单胞菌免疫后，观察甲鱼抗体产生和中性白细胞吞噬能力的变化情况.结果表明，"868"菌粉可促进甲鱼抗体产生，且甲鱼白细胞吞噬率提高了4.1％，吞噬指数提高了8.4％.     

First results from the North Iceland experiment

Between June 2004 and September 2004 a temporary seismic network was installed on the northern insular shelf of Iceland and onshore in north Iceland. The seismic setup aimed at resolving the subsurface structure and, thus, the geodynamical transition from Icelandic crust to typical oceanic crust along Kolbeinsey Ridge. The experiment recorded about 1,000 earthquakes. The region encloses the Tjörnes Fracture Zone containing the Husavik–Flatey strike-slip fault and the extensional seismic Grimsey Lineament. Most of the seismicity occurs in swarms offshore. Preliminary results reveal typical mid-ocean crust north of Grimsey and a heterogeneous structure with major velocity anomalies along the seismic lineaments and north–south trending subsurface features. Complementary bathymetric mapping highlight numerous extrusion features along the Grimsey Lineament and Kolbeinsey Ridge. The seismic dataset promises to deliver new insights into the tectonic framework for earthquakes in an extensional transform zone along the global mid-ocean ridge system.