北京一号数据检测渤海海洋锋

本文基于引力模型,对北京一号对地观测小卫星数据渤海区域进行海洋锋面检测。针对北京一号小卫星数据的特点,选择红波段作为实验波段,并选择渤海湾南岸水色锋和辽东湾东岸辐射沙脊两个实验区域。算法首先对数据进行线性拉伸,波段运算等预处理,突出锋面信息,其中,拉伸区间由图像直方图确定,接着应用引力模型对预处理后的数据进行锋面检测。实验结果表明,本文算法能够对两个实验区域的锋面进行检测,得到的锋面信息连续、突出,证明了算法的有效性;针对北京一号对地观测小卫星数据,本文算法相比于传统锋面检测算法,能够得到更加连续的锋面信息,并能较好抑制近岸泥沙对锋面检测的干扰。     

GNSS ambiguity resolution with controllable failure rate for long baseline network RTK

Many large-scale GNSS CORS networks have been deployed around the world to support various commercial and scientific applications. To make use of these networks for real-time kinematic positioning services, one of the major challenges is the ambiguity resolution (AR) over long inter-station baselines in the presence of considerable atmosphere biases. Usually, the widelane ambiguities are fixed first, followed by the procedure of determination of the narrowlane ambiguity integers based on the ionosphere-free model in which the widelane integers are introduced as known quantities. This paper seeks to improve the AR performance over long baseline through efficient procedures for improved float solutions and ambiguity fixing. The contribution is threefold: (1) instead of using the ionosphere-free measurements, the absolute and/or relative ionospheric constraints are introduced in the ionosphere-constrained model to enhance the model strength, thus resulting in the better float solutions; (2) the realistic widelane ambiguity precision is estimated by capturing the multipath effects due to the observation complexity, leading to improvement of reliability of widelane AR; (3) for the narrowlane AR, the partial AR for a subset of ambiguities selected according to the successively increased elevation is applied. For fixing the scalar ambiguity, an error probability controllable rounding method is proposed. The established ionosphere-constrained model can be efficiently solved based on the sequential Kalman filter. It can be either reduced to some special models simply by adjusting the variances of ionospheric constraints, or extended with more parameters and constraints. The presented methodology is tested over seven baselines of around 100 km from USA CORS network. The results show that the new widelane AR scheme can obtain the 99.4 % successful fixing rate with 0.6 % failure rate; while the new rounding method of narrowlane AR can obtain the fix rate of 89 % with failure rate of 0.8 %. In summary, the AR reliability can be efficiently improved with rigorous controllable probability of incorrectly fixed ambiguities.     

地形重力波拖曳参数化对热带气旋强度和路径预报影响的研究

本文在GRAPES_TMM（Global/Regional Assimilation and Prediction System for Tropical Mesoscale Model）——中国南海台风模式版（面向南海和东南亚）中发展和引进了KA95（Kim and Arakawa,1995）地形重力波拖曳参数化方案（GWDO）,并对2012年主要的9个登陆台风进行了试验对比研究,考察了不同标准Richardson数（Ri_c）的GWDO试验对台风路径和强度预报的影响。结果表明,在引入地形重力波拖曳参数化过程后,模式对台风登陆时路径和强度的预报能力均要有提高,对台风预报时长越长,GWDO的影响也更为显著。对双台风“SAOLA”和“DAMREY”试验结果表明,GWDO对台风外围距台风中心150 km的对流层中下层风速减弱较为明显,减弱了GRAPES区域模式对台风强度预报偏强的现象,对台风强度长时间预报改善更为明显。不同标准Ri_c对重力波拖曳力的计算较为敏感,当Ri_c取1.0时,动能迅速的在低层被频散,能量无法有效地上传;Ri_c取0.25时,大部分的能量在中高层被频散。总的来说,Ri_c取0.75时对台风路径和强度预报改进更为显著,其结果可为业务预报提供指导意义。     

闭环极点与开环零极点的一种关系式

根据控制系统的特征方程和开环传递函数的关系 ,推导出闭环极点与开环零极点之间的关系式 ,并举例说明其应用 ,该公式简单且具有通用性和实用性。     

A study of stability of the seafloor foundation on a gently sloping continental shelf

Abstract

The possibility of seafloor failure under external loadings on a gently sloping continental shelf is controlled, to a large extent, by the geotechnical characters of subbottom sediments (e.g., shear strength, compressibility, and liquefaction potential) and structural factors (e.g., sedimentary stratification). By means of undis‐turbing coring, in‐situ acoustic measurement, and subbottom profiling, the authors conducted an investigation into the seafloor instabilities and possibilities of sediment slope failure within the continental shelf off the Pearl River mouth, which is one of the most important areas for offshore development in the northern South China Sea. Based on in‐situ and laboratory measurements and tests for sediment physical properties, static and dynamic behavior, and acoustic characteristics, the analyses indicate: (1) subbottom sediments that originated from terrigenous clay during the Pleistocene are compact and overconsolidated, and the mean sound velocity in such sediments is relatively high; (2) the maximum vertical bearing capacity of subbottom sediments is efficiently conservative on the safe side for dead loads of light structures, and the trench walls are stable enough while trenching to a depth of about 2 m below the seafloor under still water; and (3) it is quite improbable that the subbottom sediments liquefy under earthquake (M ≤ 6) or storm wave loading.     

四川拉拉铜矿床赋矿层位变质沉积岩地球化学特征

拉拉铜矿区赋矿层位变质沉积岩的主量元素(ICV(av)=3.04,K2O/Al2O3(av)=0.22,CIA(av)=53.1)及Cs、Rb显著亏损特征,表明其物源区岩石只含有较少的粘土矿物和碱性长石,为中—低化学风化程度,且处于较不稳定的构造环境;多数样品的微量元素表现为显著富集高场强元素、亏损过渡族元素及Cr/Zr(av)=0.15、Th/Sc(av)=0.58,且具轻稀土富集、重稀土平坦((La/Yb)n(av)=25.7)的稀土元素配分模式,表明物源区以长英质组分为主;Sm、Nd同位素组成特征也显示其物源区以长英质组分为主,且沉积于大陆岛弧的弧后拉张环境。同时,结合矿区赋矿层位变钠质火山岩的构造判别结果,认为拉拉铜矿床也形成于该构造背景下。     

渐消滤波原理及其理论分析

动态导航与定位的质量取决于对动态载体扰动和观测异常扰动的认知和控制。本文首先分析了渐消滤波的理论背景和基本原则；基于其基本原则，推导了渐消滤波解；然后从理论模型、极值原则全面分析了渐消滤波理论存在的问题。分析认为，理论上，渐消滤波具有控制状态模型误差影响的能力；现有渐消因子的求解在实践中可能出现负定现象，求解时必须附加条件。     

2004年南海夏季风的爆发及中南半岛陆面过程的可能影响 I： 诊断分析

南海夏季风的爆发受高原、海洋(海气相互作用)、冷空气和陆地(陆面过程或陆气相互作用)等多种因素的影响,其中中南半岛由于是连接南海夏季风和印度、孟加拉湾季风的关键区,而且孟加拉湾不仅是亚洲最早爆发夏季风的地区,又是副热带高压最早断裂的地区。因此它的陆面过程对南海夏季风的影响是不可忽视的。文章从2004年南海夏季风爆发前后的环流和降水分析其活动特征,并进一步研究中南半岛陆面过程对南海夏季风的爆发日期和强度的影响。2004年南海夏季风于5月19日爆发,利用NCEP再分析资料及地面站点降水资料对这次季风爆发前后的环流形势和降水分布进行分析,结果表明:强对流活动由孟加拉湾移到中南半岛,引起中南半岛的降水增大,导致陆面过程发生改变(包含土壤湿度,感热、潜热通量,向上长波辐射),最终使得中南半岛—南海之间的低层气温差出现符号逆转,为南海夏季风的爆发提供了必要的条件。此外,中南半岛—南海低层气温差同南海夏季风的活跃程度有密切的联系。通常负的温差出现后不久,南海夏季风即进入活跃期或非活跃期,正的温差出现之后则常常是南海夏季风的中断期。     

Wood textures in Jinman copper deposit in western Yunnan and their genetic implications

Jinman vein copper deposit in western Yunnan occurs in a salt-bearing red clastic rock formation composed of sandstone, siltstone and shale. Wood texture is considerably developed in the ores. The metallic minerals making up the wood textures mainly include pyrite, chalcopyrite and bornite. Studies on the samples and examination of their micrographs and electron micrographs have confirmed that they belong to xenoxylon, reflecting that the ore-hosting rock series is the product of sedimentation in the terrestrial environment. Organic geochemistry and sulfur and carbon isotopic composition data indicate that the formation of the deposit is substantially related with underground hot brines and biological processes.     

大同—阳高61.和5.8级地震的地电阻率异常

1987年1月至1991年6月期间,先后在大同——阳高发生了6.1级和5.8级地震,距震中330km内15个地电阻率台站中,有7个台站出现有不同性质的ρ_x异常,占总台数的47％。这表明地电阻率前兆是预报地震的有效方法。