基于CGCS2000地心独立坐标系基准确定方法探讨

国家坐标系的独立坐标系建立后,原国家坐标系的控制点不能直接应用于独立坐标系中,需要确定并计算得出独立坐标系的基准。独立坐标系的基准确定直接关系到独立坐标系的精度及其与国家坐标系间的转换。随着测绘技术的发展,一些原有的传统基准确定方法已不能满足高精度地心坐标系的要求,因此本文对地心坐标系的独立坐标系的基准确定方法进行了探讨。     

Classification of vegetation in an open landscape using full-waveform airborne laser scanner data

Airborne laser scanning (ALS) is increasingly being used for the mapping of vegetation, although the focus so far has been on woody vegetation, and ALS data have only rarely been used for the classification of grassland vegetation. In this study, we classified the vegetation of an open alkali landscape, characterized by two Natura 2000 habitat types: Pannonic salt steppes and salt marshes and Pannonic loess steppic grasslands. We generated 18 variables from an ALS dataset collected in the growing (leaf-on) season. Elevation is a key factor determining the patterns of vegetation types in the landscape, and hence 3 additional variables were based on a digital terrain model (DTM) generated from an ALS dataset collected in the dormant (leaf-off) season. We classified the vegetation into 24 classes based on these 21 variables, at a pixel size of 1 m. Two groups of variables with and without the DTM-based variables were used in a Random Forest classifier, to estimate the influence of elevation, on the accuracy of the classification. The resulting classes at Level 4, based on associations, were aggregated at three levels — Level 3 (11 classes), Level 2 (8 classes) and Level 1 (5 classes) — based on species pool, site conditions and structure, and the accuracies were assessed. The classes were also aggregated based on Natura 2000 habitat types to assess the accuracy of the classification, and its usefulness for the monitoring of habitat quality. The vegetation could be classified into dry grasslands, wetlands, weeds, woody species and man-made features, at Level 1, with an accuracy of 0.79 (Cohen’s kappa coefficient, κ). The accuracies at Levels 2–4 and the classification based on the Natura 2000 habitat types were κ: 0.76, 0.61, 0.51 and 0.69, respectively. Levels 1 and 2 provide suitable information for nature conservationists and land managers, while Levels 3 and 4 are especially useful for ecologists, geologists and soil scientists as they provide high resolution data on species distribution, vegetation patterns, soil properties and on their correlations. Including the DTM-based variables increased the accuracy (κ) from 0.73 to 0.79 for Level 1. These findings show that the structural and spectral attributes of ALS echoes can be used for the classification of open landscapes, especially those where vegetation is influenced by elevation, such as coastal salt marshes, sand dunes, karst or alluvial areas; in these cases, ALS has a distinct advantage over other remotely sensed data.     

天文经纬度归心实用算式推证

文中分析天文经纬度归心公式中各变量的特点,推导基于2000国家大地坐标系统简单实用的归心计算公式,进一步给出由已确定变量推求归心元素测量精度的数学关系式。验证实用公式计算的归心改正数满足专用工程天文经纬度的计算精度需求。     

Equilibrium trading of climate and weather risk and numerical simulation in a Markovian framework

We consider financial markets with agents exposed to external sources of risk caused, for example, by short-term climate events such as the South Pacific sea surface temperature anomalies widely known by the name El Nino. Since such risks cannot be hedged through investments on the capital market alone, we face a typical example of an incomplete financial market. In order to make this risk tradable, we use a financial market model in which an additional insurance asset provides another possibility of investment besides the usual capital market. Given one of the many possible market prices of risk, each agent can maximize his individual exponential utility from his income obtained from trading in the capital market, the additional security, and his risk-exposure function. Under the equilibrium market-clearing condition for the insurance security the market price of risk is uniquely determined by a backward stochastic differential equation. We translate these stochastic equations via the Feynman–Kac formalism into semi-linear parabolic partial differential equations. Numerical schemes are available by which these semilinear pde can be simulated. We choose two simple qualitatively interesting models to describe sea surface temperature, and with an ENSO risk exposed fisher and farmer and a climate risk neutral bank three model agents with simple risk exposure functions. By simulating the expected appreciation price of risk trading, the optimal utility of the agents as a function of temperature, and their optimal investment into the risk trading security we obtain first insight into the dynamics of such a market in simple situations.

省级基础地理信息数据坐标转换软件设计与实现

介绍了数字线划图、数字高程模型、数字正射影像图、数字栅格地图由1980西安坐标系向2000国家大地坐标系的转换关键技术,阐述了省级基础地理信息数据坐标转换软件的设计原则、总体架构、主要功能及实现方法,对高效、快速将1980西安坐标系下的成果转到2000国家大地坐标系具有一定的指导作用。     

GPS RTK positioning via Internet-based 3G CDMA2000/1X wireless technology

The latest evolution in digital wireless technology, third-generation (3G) Code Division Multiple Access/Single Carrier (CDMA2000/1X) wireless network, is applicable for transmitting real-time kinematic (RTK) GPS correction messages. Fast and reliable, publicly available wireless networks, combined with highly accessible Internet connectivity, allows the multicasting of messages to mobile users, who are no longer restricted to traditional private UHF wireless networks. Nationwide public wireless network systems continue to expand and can provide an inexpensive infrastructure for the emerging multi-reference network system. Transmission performance via the Internet-based CDMA2000/1X outperforms UHF technology in transmission throughput and latency, as well as in the RTK initialization time and positional accuracy.     

Global tectonics and the plate motion obtained from the ITRF97 station velocity vectors

~~Global tectonics and the plate motion obtained from the ITRF97 station velocity vectors@马宗晋 @任金卫 @张进~~     

Bestimmung polarer Phosphorsäureester in Trink‐ und Oberflächenwasser mittels HPLC‐MS‐MS

Determination of Organophosphorus Pesticides in Water by HPLC‐MS‐MS In the EC Water Framework Directive 2000/60/EG and in CEC 76/464/EEC there are 16 organophosphorus pesticides (insecticides and acaricides) listed which belong to so‐called priority substances. The committed quality aims of these substances frequently require maximum concentrations below 0.1 μg/L. In this paper a HPLC‐MS‐method is described. The reported limits of determination of organophosphorus pesticides are lower than the demanded limits. High analytical sensitivity is reached by solid‐phase extraction (SPE) and by injecting large volumes. For some of these substances no sample enrichment is needed and low detection limits are obtained by direct injection of the original water sample.     

Seismic soil pressure for building walls: An updated approach

The Mononobe–Okabe (M–O) method developed in the 1920s in Japan continues to be widely used despite many criticisms and its limitations. The method was developed for gravity walls retaining cohesionless backfill materials. In design applications, however, the M–O method, or any of its derivatives, is commonly used for below ground building walls. In this regard, the M–O method is one of the most abused methods in the geotechnical practice. Recognizing the limitation of the M–O method, a simplified method was recently developed to predict lateral seismic soil pressure for building walls. The method is focused on the building walls rather than retaining walls and specifically considers the dynamic soil properties and frequency content of the design motion in its formulation.     

Comparisons, processing and interpretation of the surveyed data by GMS-06 and other magnetotelluric sounding systems

In recent years, the data collecting and processing of magnetotelluric sounding （MT） have progressed greatly. How to improve the quality of field surveyed data and obtain the high quality parameters such as apparent resistivity and phase is the most important link during the overall flow. It is closely related to the signal-to-noise ratio of magnetic sensors, the resolution of data collecting units and relevant processing methods as well. Produced by Germany Metronix Measurement Instruments and Electronics Ltd., the new type multi-channel geophysical measurement system GMS-06 was already adopted and used by domeslic units such as Institute of Geology and Geophysics of Chinese Academy of Sciences and Tongji University. Based on the brief introduction of GMS-06, this paper will give the comparisons and analyses of the synchronous surveyed MT data by GMS-06, MMS-03 MT system which was also produced by Metronix and V5-2000 MT system produced by Canada Phoenix Geophysics Ltd.. Then the preliminary processing and interpretation results of the long period MT data observed by GMS-06 in the area of Shanghai and Zhejiang are also discussed in the paper.