GPS网平差中的稳健估计     

冯玉钊  邱蕾 《地理空间信息》2009,7(2):45-48

GPS网平差利用三维基线向量为观测值，与常规的粗差探测不同，根据RECO法基本原理，以GPS网为例，说明RECO法在GPS网平差中粗差探测中的优越性，得出一些有益的结论。  相似文献   

Yields of Nucleosynthesis from massive and intermediate mass stars and constraints on their final evolution     

D. C. V. Mallik  Sushma V. Mallik 《Journal of Astrophysics and Astronomy》1985,6(3):113-130

Nucleosynthetic yields and production rates of helium and heavy elements are derived using new initial mass functions which take into account the recent revisions in O star counts and the stellar models of Maeder (1981a, b) which incorporate the effects of massloss on evolution. The current production rates are significantly higher than the earlier results due to Chiosi & Caimmi (1979) and Chiosi (1979), and a near-uniform birthrate operating over the history of the galactic disc explains the currently observed abundances. However, the yields are incompatibly high, and to obtain agreement it is necessary to assume that stars above a certain mass do not explode but proceed to total collapse. Further confirmation of this idea comes from the consideration of the specific yields and production rates of oxygen, carbon and iron and the constraints imposed by the observational enrichment history in the disc as discussed by Twarog & Wheeler (1982). Substantial amounts of⁴He and¹⁴C, amongst the primary synthesis species, are contributed by the intermediate mass stars in their wind phases. If substantial numbers of them exploded as Type I SN, their contribution to the yields of¹²C and⁵⁶Fe would be far in excess of the requirements of galactic nucleosynthesis. Either efficient massloss precludes such catastrophic ends for these stars, or the current stellar models are sufficiently in error to leave room for substantial revisions in the specific yields. The proposed upward revision of the¹²C (α,γ)¹⁶O rate may produce the necessary changes in stellar yields to provide a solution to this problem. Stars that produce most of the metals in the Galaxy are the same ones that contribute most to the observed supernova rate.  相似文献   

Consideration of time-correlated errors in a Kalman filter applicable to GNSS   总被引：1，自引：0，他引：1  

M. G. Petovello  K. O’Keefe  G. Lachapelle  M. E. Cannon 《Journal of Geodesy》2009,83(1):51-56

An algorithm for considering time-correlated errors in a Kalman filter is presented. The algorithm differs from previous implementations in that it does not suffer from numerical problems; does not contain inherent time latency or require reinterpretation of Kalman filter parameters, and gives full consideration to additive white noise that is often still present but ignored in previous implementations. Simulation results indicate that the application of the new algorithm yields more realistic and therefore useful state and covariance information than the standard implementation. Results from a field test of the algorithm applied to the problem of kinematic differential GPS demonstrate that the algorithm provides slightly pessimistic covariance estimates whereas the standard Kalman filter provides optimistic covariance estimates.  相似文献   

低轨卫星初始状态误差对反演地球重力场的影响     

张兴福  沈云中 《测绘科学》2009,34(3)

基于动力学法反演地球重力场的基本理论,研究了卫星初始状态向量误差对应用低轨卫星精密轨道数据反演地球重力场的影响。在仅考虑低轨卫星初始状态误差的情况下进行了模拟计算,结果表明:在利用低轨卫星精密轨道数据反演地球重力场时,卫星初始状态向量误差需要重新进行估计;在目前的轨道精度水平下,若不顾及误差方程二次项的影响,反演弧长不宜过长;卫星初始状态速度误差(约1.5mm/s)的影响要大于位置误差(约10 cm)的影响。  相似文献   

多种风电场风速预报订正方法的适用性研究与集成应用          下载免费PDF全文

徐丽娜  申彦波  冯震  叶虎 《干旱区地理》2022,45(4):1114-1124

以内蒙古中部某风电场为实验风电场,采用随机森林（Random forest,RF）方法、相似误差订正（Analogue correction of errors,ACE）方法以及概率密度匹配方法（Probability density function matching method,PDF）分别对风电场风速预报进行订正及适用性研究。结果表明：3种方法在各季均对中尺度天气预报模式（Weather research and forecasting model, WRF）风速预报具有不同程度的订正效果,RF方法可以有效改善WRF误差较大的问题,但兼具误差过分放大情况,ACE方法和PDF虽然对较大误差的改善能力不及RF方法,但是能够较好地控制误差过分放大问题。此外,3种方法针对小于5 m·s^-1的小风速段,订正效果不理想,随着风速的增加,订正能力逐渐增强。参照预报模型各自的优势,尝试开展多种预报模型的分风速等级集成应用,可以对不同风速等级下的WRF预报起到较好的改善作用。  相似文献   

一种顾及电子元件延迟的超宽带室内定位方法     

赵胤植  邹进贵  蔡礼贤  黄格格 《测绘通报》2022,(4):1-5+31

针对超宽带定位系统中存在多种误差影响定位精度的问题,本文全面分析了超宽带室内定位的误差源,给出了超宽带室内定位基本函数模型,提出了将电子元件延迟这一系统差与三维坐标同时作为参数进行估计,并通过高斯-牛顿迭代算法得到定位结果的方法。试验结果表明,该方法能有效消除位置系统偏差,两组静态试验均以全站仪测量结果作为真值,点位误差分别为4.1、2.3 cm,相较于已有方法分别提高了64%和87%,而动态试验结果更接近于参考轨迹,最大误差小于10 cm。  相似文献   

云南省施甸县摆田铅锌矿矿床地质特征及成因     

李星  王睿  和敬华  徐友智  胡兴涛 《云南地质》2014,(2):207-209

矿体赋存于上三叠统大水塘组顶部与中三叠统河湾街组底部断层接触带中,严格受构造控制.矿体呈透镜状～似层状,厚度变化较大.为一早期形成于断裂破碎带中后经地表长时间氧化淋滤叠加形成的热液—风化淋滤型铅锌矿床.  相似文献   

云南绿春杨家寨金多金属矿矿床特征及成矿规律     

郭建刚 《云南地质》2014,33(3):320-328

杨家寨金多金属矿位于西藏—三江造山系,兰坪—普洱双向弧后陆内盆地与绿春陆缘弧带结合部,矿体近矿围岩主要为下二叠统高井朝组安山质凝灰岩及安山岩,少部分为石英斑岩,矿体就位于与莫马洛断层（F4）成锐角度相交的次级构造、层间破碎带及层间剥离—滑脱构造带.成矿作用共分三个阶段：早二叠世晚期——矿源岩（层）形成阶段,燕山早期——矿床形成阶段;燕山晚期——矿床定位阶段.矿床类型为浅成低温热液构造—蚀变岩型多金属矿床.  相似文献   

德钦佛山托罗铅锌矿地质特征及成因分析     

马安妮  李蓬博  孟志勇  李守奎 《云南地质》2014,(1):141-143

在对该区野外地质调查的基础上,本文对该铅锌矿化带的成矿构造背景、矿化体特征进行了初步分析与总结,认为该矿受区域构造断裂控制,矿床类型为中低温热液脉状铅锌多金属矿床.该区成矿地质条件优越,矿化体较多,矿体在走向和倾向延伸方向仍可有新突破,并有找到新矿体的可能.  相似文献   

云南剑川新民铁矿地质及成因     

花仁忠  杨正学  田云 《云南地质》2014,(1):36-39,50

新民铁矿位于北北西—南南东向雪龙山—桥后断裂（弥沙河断裂）东侧之云岭褶皱束三级构造单元中,赋矿层位为中三叠统上兰组下亚段泥质灰岩.地层、构造控矿,为沉积—后期改造型铁矿床.  相似文献