ON BIO-EFFECTS ON KARST LANDSCAPE IN JIUZHAIGOU CONSERVATION, SICHUAN PROVINCE, CHINA—WITH SPECIAL REFERENCE TO A MICROMORPHOLOFICAL APPROACH

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An improved ionosphere interpolation algorithm for network RTK in low-latitude regions

A traditional interpolation algorithm with the linear interpolation method (LIM) using a fixed number of reference stations is widely used in network RTK to obtain the ionospheric delays for the users. In low-latitude regions, where the ionosphere is relatively active, however, large interpolation errors exist, especially for satellites at low elevation angles. Considering the characteristics of “coinciding ionospheric pierce points (CIPPs)” with a similar nature of ionospheric delays, an improved interpolation algorithm is proposed. In this algorithm, all stations with CIPPs are used to establish the interpolation model; thus, more precise interpolation model is achieved. To validate the performance of the proposed algorithm, data from some reference stations in Guangdong Province of China were used, and the results are compared with those with the traditional interpolation algorithm. Numerical analysis shows that the interpolation accuracy of the proposed algorithm increases by 10–30% compared with the traditional one. Since the number of reference stations is flexible, the proposed algorithm can also balance the model accuracy with the computation burdens. In addition, the proposed algorithm is less affected by the selection of master reference station. In terms of network RTK on-the-fly positioning, the time-to-first-fix is reduced when replacing the traditional interpolation algorithm with the proposed one.     

入园率视角下长三角地区化工产业时空格局演化及影响因素

本文以全国化工产业密集区——长三角地区为例,基于规模以上中国工业企业详细数据,从化工企业入园率的视角出发,综合运用均值中心、标准差椭圆、核密度分析及空间自相关等分析方法,分析并揭示了1998—2013年长三角地区化工产业时空格局演化规律及影响因素。研究结果表明：1998—2013年长三角地区化工企业总体上呈现不断增长趋势,入园率由6.19%提升到36.98%;化工企业“西北-东南”方向分布明显,且近似呈“先东南,后西北”的路径迁移规律,较之全部企业,入园企业具有更高的离散度、更大的迁移幅度,入园企业与全部企业逐步由空间失配演变为空间匹配;中心集聚与外围扩散态势并存,发育并逐渐形成了环太湖集聚区、沿杭州湾集聚区、沿长江密集带及沿海密集带四大化工产业集聚片区,化工产业的区域空间结构趋于复杂化、有序化与稳定化;地级尺度上化工企业入园率不断提升,2003年与2013年呈显著的空间正相关,热点区逐渐由浙江东南转移到苏皖北部,冷点区从安徽北部迁移到浙江西北,基本完成了空间格局上的对称反转变换,但化工企业入园率与空间密度分布一直处于错配失衡状态。通过结合化工产业特性与长三角区域特征,定性探讨了长三角地区化工产业时空格局演化的影响因素,特别是阐述了化工产业“园区化”进程的作用机制。     

GNSS形变监测中系统误差的时空相关性研究

通过大量实测数据分析了系统误差的时空变化规律,论证了具有时空相关性的双差观测值系统误差残差的存在,实现了观测值的滤波及求差,提高了分离微小形变量的精度。     

南京梁代石刻微侵蚀的研究

从地貌学角度较系统地分析了梁代石灰岩石刻表面自然毁损的微侵蚀机制，本文指出，雨水沿缝合线渗流，经多种地衣及兰藻、绿藻等生物作用而大大加强了溶蚀作用，导致石刻的崩解，并讨论此种特殊微侵蚀形态的形成机制在地貌学理论研究中的意义。     

BP神经网络在基坑变形预测分析中的应用

本文提出了基坑变形预测与分析的BP神经网络方法,建立了基坑变形预测分析的模型,应用MATLAB语言编制计算程序进行计算并与实际工程监测值进行比较,从而验证了神经网络在基坑变形预测分析中的可行性、有效性。     

Assessment of code bias variations of BDS triple-frequency signals and their impacts on ambiguity resolution for long baselines

GPS Solutions - Carrier phase ambiguity resolution over long baselines is challenging in BDS data processing. This is partially due to the variations of the hardware biases in BDS code signals and...     

An efficient solution of real-time data processing for multi-GNSS network

Global navigation satellite systems (GNSS) are acting as an indispensable tool for geodetic research and global monitoring of the Earth, and they have been rapidly developed over the past few years with abundant GNSS networks, modern constellations, and significant improvement in mathematic models of data processing. However, due to the increasing number of satellites and stations, the computational efficiency becomes a key issue and it could hamper the further development of GNSS applications. In this contribution, this problem is overcome from the aspects of both dense linear algebra algorithms and GNSS processing strategy. First, in order to fully explore the power of modern microprocessors, the square root information filter solution based on the blocked QR factorization employing as many matrix–matrix operations as possible is introduced. In addition, the algorithm complexity of GNSS data processing is further decreased by centralizing the carrier-phase observations and ambiguity parameters, as well as performing the real-time ambiguity resolution and elimination. Based on the QR factorization of the simulated matrix, we can conclude that compared to unblocked QR factorization, the blocked QR factorization can greatly improve processing efficiency with a magnitude of nearly two orders on a personal computer with four 3.30 GHz cores. Then, with 82 globally distributed stations, the processing efficiency is further validated in multi-GNSS (GPS/BDS/Galileo) satellite clock estimation. The results suggest that it will take about 31.38 s per epoch for the unblocked method. While, without any loss of accuracy, it only takes 0.50 and 0.31 s for our new algorithm per epoch for float and fixed clock solutions, respectively.     

石灰岩表面溶针孔的初步研究——以川西北九寨沟、南斯拉夫第那尔喀斯特区域为例

本文讨论了壳状石内地衣作用于石灰岩表形成的尺度在10-4～10-3m的“溶针孔”的形成机理及其研究的潜在理论价值和实用意义。