Why GPS makes distances bigger than they are   总被引：1，自引：0，他引：1  

Peter Ranacher  Richard Brunauer  Wolfgang Trutschnig  Stefan Van der Spek  Siegfried Reich 《International journal of geographical information science》2016,30(2):316-333

Global navigation satellite systems such as the Global Positioning System (GPS) is one of the most important sensors for movement analysis. GPS is widely used to record the trajectories of vehicles, animals and human beings. However, all GPS movement data are affected by both measurement and interpolation errors. In this article we show that measurement error causes a systematic bias in distances recorded with a GPS; the distance between two points recorded with a GPS is – on average – bigger than the true distance between these points. This systematic ‘overestimation of distance’ becomes relevant if the influence of interpolation error can be neglected, which in practice is the case for movement sampled at high frequencies. We provide a mathematical explanation of this phenomenon and illustrate that it functionally depends on the autocorrelation of GPS measurement error (C). We argue that C can be interpreted as a quality measure for movement data recorded with a GPS. If there is a strong autocorrelation between any two consecutive position estimates, they have very similar error. This error cancels out when average speed, distance or direction is calculated along the trajectory. Based on our theoretical findings we introduce a novel approach to determine C in real-world GPS movement data sampled at high frequencies. We apply our approach to pedestrian trajectories and car trajectories. We found that the measurement error in the data was strongly spatially and temporally autocorrelated and give a quality estimate of the data. Most importantly, our findings are not limited to GPS alone. The systematic bias and its implications are bound to occur in any movement data collected with absolute positioning if interpolation error can be neglected.  相似文献   

Zircon M127 – A Homogeneous Reference Material for SIMS U–Pb Geochronology Combined with Hafnium,Oxygen and,Potentially, Lithium Isotope Analysis          下载免费PDF全文

Lutz Nasdala  Fernando Corfu  John W. Valley  Michael J. Spicuzza  Fu‐Yuan Wu  Qiu‐Li Li  Yue‐Heng Yang  Chris Fisher  Carsten Münker  Allen K. Kennedy  Peter W. Reiners  Andreas Kronz  Michael Wiedenbeck  Richard Wirth  Chutimun Chanmuang  Manuela Zeug  Tamás Váczi  Nicholas Norberg  Tobias Häger  Alfred Kröner  Wolfgang Hofmeister 《Geostandards and Geoanalytical Research》2016,40(4):457-475

In this article, we document a detailed analytical characterisation of zircon M127, a homogeneous 12.7 carat gemstone from Ratnapura, Sri Lanka. Zircon M127 has TIMS‐determined mean U–Pb radiogenic isotopic ratios of 0.084743 ± 0.000027 for ²⁰⁶Pb/²³⁸U and 0.67676 ± 0.00023 for ²⁰⁷Pb/²³⁵U (weighted means, 2s uncertainties). Its ²⁰⁶Pb/²³⁸U age of 524.36 ± 0.16 Ma (95% confidence uncertainty) is concordant within the uncertainties of decay constants. The δ¹⁸O value (determined by laser fluorination) is 8.26 ± 0.06‰ VSMOW (2s), and the mean ¹⁷⁶Hf/¹⁷⁷Hf ratio (determined by solution ICP‐MS) is 0.282396 ± 0.000004 (2s). The SIMS‐determined δ⁷Li value is ?0.6 ± 0.9‰ (2s), with a mean mass fraction of 1.0 ± 0.1 μg g^?1 Li (2s). Zircon M127 contains ~ 923 μg g^?1 U. The moderate degree of radiation damage corresponds well with the time‐integrated self‐irradiation dose of 1.82 × 10¹⁸ alpha events per gram. This observation, and the (U–Th)/He age of 426 ± 7 Ma (2s), which is typical of unheated Sri Lankan zircon, enable us to exclude any thermal treatment. Zircon M127 is proposed as a reference material for the determination of zircon U–Pb ages by means of SIMS in combination with hafnium and stable isotope (oxygen and potentially also lithium) determination.  相似文献   

Automated Extraction of a Five‐Year LA‐ICP‐MS Trace Element Data Set of Ten Common Glass and Carbonate Reference Materials: Long‐Term Data Quality,Optimisation and Laser Cell Homogeneity          下载免费PDF全文

David Evans  Wolfgang Müller 《Geostandards and Geoanalytical Research》2018,42(2):159-188

LA‐ICP‐MS is increasingly applied to obtain quantitative multi‐element data with minimal sample preparation, usually achieved by calibration using reference materials (RMs). However, some ubiquitous RMs, for example the NIST SRM 61× series glasses, suffer from reported value uncertainties for certain elements. Moreover, no long‐term data set of analyses conducted over a range of ablation and tuning conditions exists. Thus, there has been little rigorous examination of the extent to which offsets between measured and reported values are the result of error in these values rather than analytically induced fractionation. We present new software (‘LA‐MINE’), capable of extracting LA‐ICP‐MS data with no user input, and apply this to our system, yielding over 5 years of data (~ 5700 analyses of ten glass and carbonate RMs). We examine the relative importance of systematic analytical bias and possible error in reported values through a mass‐specific breakdown of fourteen of the most commonly determined elements. Furthermore, these data, obtained under a wide range of different ablation conditions, enable specific recommendations of how data quality may be improved, for example the role of diatomic gas, the effect of differential inter‐glass fractionation factors and choice of transport tubing material. Finally, these data demonstrate that the two‐volume Laurin ablation cell is characterised by no discernible spatial heterogeneity in measured trace element ratios.  相似文献   

Correction to: Hydro-geochemical characteristics of the groundwater resources in the southern part of the Red River’s Delta plain,Vietnam     

Hoan V. Hoang  Lam V. Nguyen  Nhan D. Dang  Frank Wagner  Nhan Q. Pham 《Environmental Earth Sciences》2018,77(20):714

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The Austrian node of the natural resources satellite remote sensing cloud service platform:examples of Sino-Austrian cooperation     

Wolfgang Kainz  Xinming Tang  Yucai Xue 《地球空间信息科学学报》2021,24(1):145-151

The Austrian node of the Natural Resources Satellite Remote Sensing Cloud Service Platform was established in 2016 through a cooperation agreement between the Land Satellite Remote Sensing Application Center(LASAC),Ministry of Natural Resources of the Peoples Republic of China and the University of Vienna,Austria.Under this agreement panchromatic and multi-spectral data of the Chinese ZY-3 satellite are pushed to the server at the University of Vienna for use in education and research.So far,nearly 500 GB of data have been uploaded to the server.This technical note briefly introduces the ZY-3 system and illustrates the implementation of the agreement by the first China-Sat Workshop and several case studies.Some of them are already completed,others are still ongoing.They include a geometric accuracy validation of ZY-3 data,an animated visualization of image quick views on a spherical display to demonstrate the time series of the image coverage for Austria and Laos,and the use of ZY-3 data to study the spread of bark beetle in the province of Lower Austria.An accuracy study of DTMs from ZY-3 stereo data,as well as a land cover analysis and comparison of Austria with ZY-3 and other sensors are still ongoing.  相似文献   

FELLNER,WOLF-DIETRICH: Computer-Grafik. Reihe lnformatik Bd. 58, BI-Wissenschafisverlag Mannheim,Wien, Zurich, 1988, 400 Seiten, 184 Abbildungen,Preis: DM 48,- ISBN 3-411-03179-4     

Wolfgang Mai 《Astronomische Nachrichten》1990,311(4):264-264

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Evaluation of the Presence of Methane in Złoczew Lignite: Comparison with Other Lignite Deposits in Poland     

Macuda  Jan  Baran  Paweł  Wagner  Marian 《Natural Resources Research》2020,29(6):3841-3856

Natural Resources Research - Catastrophic cases of methane explosion during exploratory drilling within the Be?chatów ortholignite deposit have led to testing for methane in other Polish...  相似文献   

Extension of the Paraná Basin to offshore Brazil: Implications for coalbed methane evaluation     

Michael Holz  Wolfgang Kalkreuth  Silvia Beatriz Alves Rolim 《Marine and Petroleum Geology》2010

Coalbed methane (CBM) is a worldwide exploration target of the petroleum industry. In Brazil, the most important coal-bearing succession is associated with the Permian Rio Bonito Formation of the Paraná Basin. The gas-prone areas are located at the southeastern margin of the Paraná Basin and possibly in the offshore region of the northern part of the Pelotas Basin. Coalfields end abruptly at the present day shoreline, a result of rifting of Gondwana and the evolution of the South Atlantic Ocean. All geologic indicators suggest that in pre-rift times the coal seams extended further eastwards, probably now lying deeply buried below the sedimentary succession of the Pelotas Basin. The present paper discusses structural, stratigraphic, seismic and aeromagenetic data that support the preservation of continental crust beneath ocean sediment. If the coal beds had similar lateral extent to known onshore coals, and coal beds extended across the projected extension of the Parana basin, and there was a conservative 5 m of cumulative coal thickness, then a potential methane volume can be estimated for this newly inferred resource. Average onshore coal gas content is 32 scf/ton (1.00 m³/ton). If this is similar in the offshore coal deposits, then the hypothetical methane volume in the offshore area could be in excess of 1.9 × 10¹² scf (56 × 10⁹ m³). Metamorphism from dikes associated with rifting are potential complicating factors in these deposits, and since no borehole reaching the deep-lying strata in the offshore area are available, this is a hypothetical gas resource with a certain level of uncertainty which should be tested in the future by drilling a deep borehole.  相似文献   

Reconstructing tsunami run-up from the characteristics of tsunami deposits on the Thai Andaman Coast     

Chanchai Srisutam  Jean-Frank Wagner 《Coastal Engineering》2010

Tsunamis can leave deposits on the land surface they inundate. The characteristics of tsunami deposits can be used to calculate tsunami run-up height and velocity. This paper presents a reconstruction of tsunami run-up from tsunami deposit characteristics in a simple mathematical model. The model is modified and applied to reconstruct tsunami run-ups at Ao Kheuy beach and Khuk Khak beach, Phangnga province, Thailand. The input parameters are grain-size and maximum run-up distance of the sediment. The reconstructed run-up heights are 4.16–4.91 m at Ao Kheuy beach and 5.43–9.46 m at Khuk Khak beach. The estimated run-up velocities (maximum velocity) at the still water level are 12.78–19.21 m/s. In the area located 70–140 m inland to the end of run-up inundation, estimated mean run-up velocities decrease from approximately 1.93 m/s to 0 m/s. Reasonably good agreements are found between reconstructed and observed run-up heights. The tsunami run-up height and velocity can be used for risk assessment and coastal development programs in the tsunami affected area. The results show that the area from 0 to 140 m inland was flooded by high velocity run-ups and those run-up energies were dissipated mainly in this area. The area should be designated as either an area where settlement is not permitted or an area where effective protection is provided, for example with flood barriers or forest.  相似文献   

Final Stages of Stellar Evolution and Nucleosynthesis: What do We Know and What Would We Like to Know?     

Wolfgang Hillebrandt 《Astrophysics and Space Science》2002,281(1-2):173-182

Recent developments in theoretical model-calculations for the synthesis of the chemical elements during late stages of stellar evolution are reviewed. Special emphasis is put on a discussion of various astrophysical sites, including core-collapse and thermonuclear supernovae, and the physics of turbulent reactive fluids. Results of numerical simulations are presented and discussed, together with new results concerning solar-system abundances as well as abundances observed in very metal-poor stars, in the context of searches for constraints on the still rather uncertain nuclear physics data and astrophysical models. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献