导航(英文)最新文献

Hybrid Multilateration and Triangulation 混合多边化和三角化

导航(英文) Pub Date : 2021-08-31 DOI: 10.4236/pos.2021.121001

Eric Widdison, D. Long

引用次数: 1

Ripple Tectonics—When Subduction Is Interrupted 波纹构造——当俯冲中断时

导航(英文) Pub Date : 2020-06-30 DOI: 10.4236/pos.2020.113303

Z. Ben‐Avraham, G. Schubert, E. Lodolo, U. Schattner

{"title":"Ripple Tectonics—When Subduction Is Interrupted","authors":"Z. Ben‐Avraham, G. Schubert, E. Lodolo, U. Schattner","doi":"10.4236/pos.2020.113303","DOIUrl":"https://doi.org/10.4236/pos.2020.113303","url":null,"abstract":"Subduction plays a fundamental role \u0000in plate tectonics and is a significant factor in modifying the structure and topography \u0000of the Earth. It is driven by convection forces that change over a >100 Myr time \u0000scale. However, when an oceanic plateau approaches, it plugs the subduction, and \u0000causes slab necking and tearing. This abrupt change may trigger a series of geodynamic \u0000(tectonic, volcanic) and sedimentary responses recorded across the convergence boundary \u0000and its surrounding regions by synchronous structural modifications. We suggest \u0000that a large enough triggering event may lead to a ripple tectonic effect that propagates \u0000outwards while speeding up the yielding of localized stress states that otherwise \u0000would not reach their threshold. The ripple effect facilitates tectonic, volcanic, \u0000and structural events worldwide that are seemingly unrelated. When the world’s largest \u0000oceanic plateau, Ontong Java Plateau (OJP), choked the Pacific-Australian convergence \u0000zone at ~6 Myr ago, it induced kinematic modifications throughout the Pacific region \u0000and along its plate margins. Other, seemingly unrelated, short-lived modifications \u0000were recorded worldwide during that time window. These modifications changed the \u0000rotation of the entire Pacific plate, which occupies ~20% of the Earth’s surface. \u0000In addition, the Scotia Sea spreading stopped, global volcanism increased, the Strait \u0000of Gibraltar closed, and the Mediterranean Sea dried up and induced the Messinian \u0000salinity crisis. In this paper, we attribute these and many other synchronous events \u0000to a new “ripple tectonics” mechanism. We suggest that the OJPincipient collision \u0000triggered the Miocene-Pliocene transition. Similarly, we suggest that innovative \u0000GPS-based studies conducted today may seek the connectivity between tectonic, seismic, \u0000and volcanic events worldwide.","PeriodicalId":56806,"journal":{"name":"导航(英文)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44646685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Combined Multifactor Evidence of a Giant Lower-Mantle Ring Structure below the Eastern Mediterranean 东地中海以下巨大下地幔环结构的综合多因素证据

导航(英文) Pub Date : 2020-04-08 DOI: 10.4236/pos.2020.112002

L. Eppelbaum, Z. Ben‐Avraham, Y. Katz, S. Cloetingh, M. Kaban

{"title":"Combined Multifactor Evidence of a Giant Lower-Mantle Ring Structure below the Eastern Mediterranean","authors":"L. Eppelbaum, Z. Ben‐Avraham, Y. Katz, S. Cloetingh, M. Kaban","doi":"10.4236/pos.2020.112002","DOIUrl":"https://doi.org/10.4236/pos.2020.112002","url":null,"abstract":"In the Arabian-Northern African region, interaction of the Nubian, Arabian and Eurasian plates and many small tectonic units is conspicuous. In order to better understand this interaction, we use satellite derived gravity data (retracked to the Earth’s surface) recognized now as a powerful tool for tectono-geodynamic zonation. We applied the polynomial approximation to the gravity data which indicated the presence of a large, deep ring structure in the eastern Mediterranean centered below the Island of Cyprus. Quantitative analysis of residual gravity anomaly provides an estimate of the deep anomalous body’s upper edge at a depth of about 1700 km. Computations of the residual gravity anomalies for the lower mantle also indicate presence of anomalous sources. The GPS vector pattern coinciding with the gravity trend implies counter clockwise rotation of this structure. Independent analyses of the geoid isolines map and seismic tomography data support the existence of a deep anomaly. Paleomagnetic data analysis from the surrounding regions confirms a counter clockwise rotation. Numerous petrological, mineralogical, geodynamical and tectonic data suggest a relation between this deep structure and near-surface processes. This anomaly sheds light on a number of phenomena including the Cyprus gravity anomaly, counter clockwise rotation of the Mesozoic terrane belt and asymmetry of basins along continental transform faults.","PeriodicalId":56806,"journal":{"name":"导航(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45918976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Development of Information Triangulation Method for Prediction of Earthquake Center Zone Using Distributed Measurements of Emitted Electromagnetic Radiation 利用发射电磁辐射的分布式测量预测地震中心区的信息三角法的发展

导航(英文) Pub Date : 2020-02-29 DOI: 10.4236/pos.2019.111001

Hikmat Hamid Asadov, L. I. Nuriyeva

引用次数: 0

Simultaneous Localization and Mapping Solutions Using Monocular and Stereo Visual Sensors with Baseline Scaling System 基于基线缩放系统的单目和立体视觉传感器的同步定位和制图解决方案

导航(英文) Pub Date : 2019-10-16 DOI: 10.4236/pos.2019.104004

A. Afifi, B. Woo

{"title":"Simultaneous Localization and Mapping Solutions Using Monocular and Stereo Visual Sensors with Baseline Scaling System","authors":"A. Afifi, B. Woo","doi":"10.4236/pos.2019.104004","DOIUrl":"https://doi.org/10.4236/pos.2019.104004","url":null,"abstract":"In this paper, SLAM systems are introduced using monocular and stereo visual \u0000sensors. The SLAM solutions are implemented in both indoor and outdoor. The SLAM samples have been taken in \u0000different modes, such as a straight line that enables us to measure the \u0000drift, in addition to the loop sample that is used to test the loop closure and \u0000its corresponding trajectory deformation. In order to verify the trajectory \u0000scale, a baseline method has been used. In addition, a ground truth has been \u0000captured for both indoor and outdoor samples to measure the biases and drifts \u0000caused by the SLAM solution. Both monocular and stereo SLAM data have been \u0000captured with the same visual sensors which in the stereo situation had a \u0000baseline of 20.00 cm. It has been shown that, the stereo SLAM localization \u0000results are 75% higher precision than the monocular SLAM solution. In addition, \u0000the indoor results of the monocular SLAM are more precise than the outdoor. \u0000However, the outdoor results of the stereo SLAM are more precise than the \u0000indoor results by 30%, which is a result of the small stereo baseline cameras. In the vertical SLAM \u0000localization component, the stereo SLAM generally shows 60% higher precision \u0000than the monocular SLAM results.","PeriodicalId":56806,"journal":{"name":"导航(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48841178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Real-Time GPS/Galileo Precise Point Positioning Using NAVCAST Real-Time Corrections 使用NAVCAST实时校正的实时GPS/Gileo精确点定位

导航(英文) Pub Date : 2019-08-31 DOI: 10.4236/pos.2019.103003

A. Elmezayen, A. El-Rabbany

{"title":"Real-Time GPS/Galileo Precise Point Positioning Using NAVCAST Real-Time Corrections","authors":"A. Elmezayen, A. El-Rabbany","doi":"10.4236/pos.2019.103003","DOIUrl":"https://doi.org/10.4236/pos.2019.103003","url":null,"abstract":"Real-time precise point positioning (PPP) is possible through the use of real-time precise satellite orbit and clock corrections, which are available through a number of organizations including the International GNSS Service (IGS) real-time service (IGS-RTS). Unfortunately, IGS-RTS is only available for the GPS and GLONASS constellations. In 2018, a new real-time service, NAVCAST, which provides real-time precise orbit and clock corrections for the GPS and Galileo constellations, was launched. In this research, the potential performance of real-time PPP which makes use of NAVCAST real-time corrections is analyzed using various static and kinematic datasets. In the static dataset, 24 hours of observations from eight IGS stations in Canada over three different days were utilized. The static results show that the contribution of Galileo satellites can improve the positioning accuracy, with 30%, 34%, and 31% in east, north, and up directions compared to the GPS-only counterparts. In addition, centimeter-level positioning accuracy in the horizontal direction and decimeter-level positioning accuracy in the vertical direction can be achieved by adding Galileo observations. In the kinematic dataset, a real vehicular test was conducted in urban and suburban combined areas. The real-time kinematic GPS/Galileo PPP solutions demonstrate an improvement of about 53%, 45%, and 70% in east, north, and up directions compared to the GPS-only counterparts. It is shown that the real-time GPS/Galileo PPP can achieve a sub-decimeter horizontal positioning accuracy and about meter-level vertical positioning accuracy through the use of NAVCAST real-time corrections.","PeriodicalId":56806,"journal":{"name":"导航(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48060512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Rigid Bridges Health Dynamic Monitoring Using 100 Hz GPS Single-Frequency and Accelerometers 100Hz GPS单频加速度计在刚性桥梁健康动态监测中的应用

导航(英文) Pub Date : 2019-05-31 DOI: 10.4236/pos.2019.102002

J. A. Neto, J. Trabanco, A. Larocca, Andre Luiz Barbosa Nunes da Cunha, Marcelo Santos

{"title":"Rigid Bridges Health Dynamic Monitoring Using 100 Hz GPS Single-Frequency and Accelerometers","authors":"J. A. Neto, J. Trabanco, A. Larocca, Andre Luiz Barbosa Nunes da Cunha, Marcelo Santos","doi":"10.4236/pos.2019.102002","DOIUrl":"https://doi.org/10.4236/pos.2019.102002","url":null,"abstract":"This article presents the modal frequency recordings of a rigid bridge, monitored by the GPS receivers (Global Positioning System) with a data recording rate of 100 Hz and accelerometers. The GPS data processing was performed through the double-difference phase, using the adjusted interferometry technique (i.e. phase residue method—PRM®). In the method, the double-difference phase of the carrier L1 is realized by using two satellites only, one was positioned at the zenith of the structure and the other satellite was positioned near the horizon. The results of the parametric adjustment of the PRM observations were finalized through software Interferometry, mathematical algorithm were applied and compared with the accelerometer. The comparison served to validate the use of GPS as a fast and reliable instrument for the preliminary monitoring of the dynamic behavior of the bridge, road artworks which are common in several countries, especially in the Brazilian road network. The data time series from the GPS and accelerometers were processed using the Wavelet. The detection of frequencies means that the combination of 100 Hz GPS receivers and the PRM allows detecting vibrations up to 5 mm. It presented significant results which were never obtained by the Fourier Transform.","PeriodicalId":56806,"journal":{"name":"导航(英文)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41428942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The CanX-7 ADS-B Mission: Signal Propagation Assessment CanX-7 ADS-B任务:信号传播评估

导航(英文) Pub Date : 2019-02-28 DOI: 10.4236/pos.2019.101001

R. Vincent, Kelly Freitag

{"title":"The CanX-7 ADS-B Mission: Signal Propagation Assessment","authors":"R. Vincent, Kelly Freitag","doi":"10.4236/pos.2019.101001","DOIUrl":"https://doi.org/10.4236/pos.2019.101001","url":null,"abstract":"The CanX-7 Automatic Dependent Surveillance-Broadcast (ADS-B) nanosatellite mission collected more than four million ADS-B messages between October 2016 and April 2017. An analysis of data collected over the north Atlantic Ocean from 05 to 28 Oct included 20,707 position messages in which the angle from satellite nadir to aircraft was determined. The proximity of the received signal strength to the noise floor of the sensor allowed for an analysis of optimal aircraft-satellite orientation for ADS-B transmission detection. The results showed a significant disparity between descending and ascending passes of the satellite. For descending passes, the average nadir angle was 50.1° with 90% of the contacts greater than 40°. The ascending passes had an average nadir angle of 31.6° with only 24.8% of the contacts exceeding 40°. The evidence suggests that the satellite magnetic torquer may not have been fully aligned with the north magnetic pole as the satellite moved northward, resulting in ascending pass nadir angles that were not reflective of the full range of values. Further analysis of the descending passes showed agreement with an ADS-B signal propagation model with peak reception at nadir angles of 51° ± 8°. For space-based ADS-B operations, the results support the replacement of the current aircraft upper quarter-wave monopole to an antenna that will transmit more energy directly above the airframe.","PeriodicalId":56806,"journal":{"name":"导航(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41637893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2