2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)最新文献

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Jammer classification with Federated Learning 干扰机分类与联邦学习
2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) Pub Date : 2023-04-24 DOI: 10.1109/PLANS53410.2023.10140124
Peng Wu, Helena Calatrava, T. Imbiriba, P. Closas
{"title":"Jammer classification with Federated Learning","authors":"Peng Wu, Helena Calatrava, T. Imbiriba, P. Closas","doi":"10.1109/PLANS53410.2023.10140124","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140124","url":null,"abstract":"Jamming signals can jeopardize the operation of GNSS receivers until deying its operation. Given their ubiquity, jamming mitigation and localization techniques are of crucial importance, for which jammer classification is of help. Data-driven models have been proven useful in detecting these threats, while their training using crowdsourced data still poses challenges when it comes to private data sharing. This article investigates the use of federated learning to train jamming signal classifiers locally on each device, with model updates aggregated and averaged at the central server. This allows for privacy-preserving training procedures that do not require centralized data storage or access to client local data. The used framework FedAvg is assessed on a dataset consisting of spectrogram images of simulated interfered GNSS signal. Six different jammer types are effectively classified with comparable results to a fully centralized solution that requires vast amounts of data communication and involves privacy-preserving concerns.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115801109","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: 1
Towards a set-based detector for GNSS integrity monitoring 基于集的GNSS完整性监测检测器研究
2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) Pub Date : 2023-04-24 DOI: 10.1109/PLANS53410.2023.10139987
Jing-wen Su, S. Schön, M. Joerger
{"title":"Towards a set-based detector for GNSS integrity monitoring","authors":"Jing-wen Su, S. Schön, M. Joerger","doi":"10.1109/PLANS53410.2023.10139987","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10139987","url":null,"abstract":"This paper aims to evaluate the performance of the set-based fault detection. This approach differs from probabilistic residual-based (RB) or solution separation (SS) fault detection and exclusion methods utilized in the Receiver Autonomous Integrity Monitoring (RAIM) and Advanced RAIM. In the basic positioning model, measurement-level intervals are constructed based on the investigated error models and propagated in a linear manner using interval mathematics and set theory. Convex polytope solutions provide a measure of observation consistency formulated as a constraint satisfaction problem. Consistency checks performed using set operations facilitate multiple-fault detection. Choosing set-emptiness as the detection criterion can alleviate the need for multiple test statistics. In this paper, we formulate the fault detection problem in the context of measurement intervals and propose a framework of integrity monitoring for the set-based detection. Considering a probabilistic error model, we implement the set-based detection methods and assess its integrity performance using Monte Carlo simulations. These evaluations will serve as a basis for further development of efficient estimators and integrity monitors.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130044512","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
Simultaneous LEO Satellite Tracking and Differential LEO-Aided IMU Navigation 低轨卫星同步跟踪与差分低轨辅助IMU导航
2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) Pub Date : 2023-04-24 DOI: 10.1109/PLANS53410.2023.10140087
Joe Saroufim, S. Hayek, Z. M. Kassas
{"title":"Simultaneous LEO Satellite Tracking and Differential LEO-Aided IMU Navigation","authors":"Joe Saroufim, S. Hayek, Z. M. Kassas","doi":"10.1109/PLANS53410.2023.10140087","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140087","url":null,"abstract":"A navigation framework with differential measurements from low Earth orbit (LEO) satellite signals of opportunity is presented. This framework comprises a navigating rover with unknown states and one or more base stations with known position(s). The framework fuses differenced pseudorange or Doppler measurements from the rover and base station(s) to LEO satellites with unkown states, in an extended Kalman filter (EKF)-based tightly-coupled LEO-aided inertial navigation system (INS), while estimating the rover's states simultaneously with the LEO satellites' states. Simulations are conducted to analyze the navigation performance due to including a varying number of differential base stations. The simulations considered an aerial vehicle equipped with a tactical-grade inertial measurement unit (IMU), an altimeter, a GNSS receiver, and a LEO receiver making pseudorange and Doppler measurements to 14 Starlink LEO satellites. The vehicle-mounted receiver clock was assumed to be an oven-controlled crystal oscillator (OCXO), while the satellites were equipped with chip-scale atomic clocks (CSACs). The aerial vehicle navigated for 28 km in 300 seconds, the last 23 km of which are without GNSS. It is shown that despite relying on two-line element (TLE) files for the LEO ephemerides, which suffer from errors on the order of kilometers, the differential framework could achieve submeter-level accuracy when using pseudo range measurements. With 3 bases, the vehicle's three-dimensional (3-D) position root mean-squared error (RMSE) drops dramatically, reaching a position RMSE of 28 cm when using pseudorange measurements and 1.94 m when using Doppler. Experimental results are presented for an unmanned aerial vehicle (UAV) navigating for 2.28 km in 120 seconds, while utilizing differential carrier phase measurements from 2 Orbcomm LEO satellites. It is shown that using TLE+SGP4 for the LEO satellites' ephemerides yields a 3-D position RMSE of 419 m, while the differential framework reduces it to 12.79 m.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134196719","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
Factor Graph Dimensionality Reduction using Lateral Motion Constraints for Aided Dead Reckoning Navigation 基于横向运动约束的辅助航位推算因子图降维
2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) Pub Date : 2023-04-24 DOI: 10.1109/PLANS53410.2023.10140049
Adam J. Rutkowski, Yetong Zhang, F. Dellaert
{"title":"Factor Graph Dimensionality Reduction using Lateral Motion Constraints for Aided Dead Reckoning Navigation","authors":"Adam J. Rutkowski, Yetong Zhang, F. Dellaert","doi":"10.1109/PLANS53410.2023.10140049","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140049","url":null,"abstract":"For navigation problems involving dead reckoning of odometry measurements aided with additional sensors, we introduce a method that treats the lateral components of the odometry measurements as constraints, thereby reducing the dimensionality of the state representation. The constrained lateral motion approach is best suited for factor graph representations of ground vehicle and fixed-wing aerial vehicle navigation, whereby the tangential component of motion is typically much greater than the lateral component. We conduct experiments in both 2D and 3D cooperative navigation scenarios aided by inter-vehicle range measurements, and show that we achieve faster convergence with more efficient optimization with our new parameterization.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117330946","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
A Map Based Multipath Error Model for Safety Critical Navigation in Railway Environments 基于地图的铁路安全关键导航多路径误差模型
2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) Pub Date : 2023-04-24 DOI: 10.1109/PLANS53410.2023.10140130
Florian Rößl, Omar García Crespillo, O. Heirich, Ana Kliman
{"title":"A Map Based Multipath Error Model for Safety Critical Navigation in Railway Environments","authors":"Florian Rößl, Omar García Crespillo, O. Heirich, Ana Kliman","doi":"10.1109/PLANS53410.2023.10140130","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140130","url":null,"abstract":"Critical railway systems, like signalling or automatic train control (ATC), are envisioned to rely on satellite-based localization. The safety aspect requires that the localization system does not only provide accurate information but also proper error uncertainty estimation and integrity quantification. This is challenging to be achieved for railway applications, since the environment is very complex and GNSS is typically affected by multiple local threats. In particular, multipath must be carefully modelled. In this work, we present a methodology to obtain a robust multipath error model for GNSS code observations that is adapted to each position along the railway track map. The method relies on the fact that the position of the train is constraint to the tracks and therefore the location specific impact of the environment is repeatable. The error model is therefore obtained and tested in this paper by the accumulation of data over several train runs collected with dedicated real measurement campaigns. The multipath error bounding capability is evaluated by using a modified horizontal ARAIM (H-ARAIM) adapted for the railway environment. Results show that the map-based error model can enable safe error quantification, in particular in challenging scenarios.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130861051","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
Fault Detection and Exclusion for INS/GPS/5G Tightly-Coupled Navigation INS/GPS/5G紧密耦合导航故障检测与排除
2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) Pub Date : 2023-04-24 DOI: 10.1109/PLANS53410.2023.10140134
Mu Jia, Z. M. Kassas
{"title":"Fault Detection and Exclusion for INS/GPS/5G Tightly-Coupled Navigation","authors":"Mu Jia, Z. M. Kassas","doi":"10.1109/PLANS53410.2023.10140134","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140134","url":null,"abstract":"A solution separation-based fault detection and exclusion (FDE) framework is developed for GPS and 5G signal of opportunity (SOP) aided inertial navigation system (INS). The proposed framework fuses an inertial measurement unit (IMU) with GPS and 5G pseudorange measurements in a tightly-coupled fashion via an extended Kalman filter to estimate the ground vehicles' attitude, position, velocity, and clock errors. Solution separation tests are exploited to detect and exclude faults from GPS and 5G signals due to transmitter failures and local threats in urban environments (e.g., multipath). Experimental results are presented to evaluate the efficacy of the proposed framework under different sensor fusion scenarios. It is shown that fusing 5G signals enhances the FDE performance of the multi-sensor system in a suburban scenario: while INS/GPS fails to detect faulty GPS measurements, the INS/GPS/SOP is able to detect the fault. Moreover, over a trajectory of 1.91 km traversed in 200 s, using signals from two 5G gNBs, the INS/GPS/5G system achieved a position root-mean squared error (RMSE) of 0.81 m and maximum position error of 2.17 m. The undetected GPS fault in the INS/GPS system increased the RMSE and maximum position error to 1.83 m and 4.25 m, respectively.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117319927","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
Receiver Clock Estimation for RTK-Grade Multi-GNSS Multi-Frequency Synthetic Aperture Processing rtk级多gnss多频合成孔径处理接收机时钟估计
2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) Pub Date : 2023-04-24 DOI: 10.1109/PLANS53410.2023.10140032
M. Bochkati, Jürgen Dampf, T. Pany
{"title":"Receiver Clock Estimation for RTK-Grade Multi-GNSS Multi-Frequency Synthetic Aperture Processing","authors":"M. Bochkati, Jürgen Dampf, T. Pany","doi":"10.1109/PLANS53410.2023.10140032","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140032","url":null,"abstract":"There are several techniques that deal with multipath mitigation either on the observation level, i.e. satellite pseudorange and carrier-phase, or directly during the tracking process of the signals within a Global Navigation Satellite System (GNSS) receiver. One of these techniques is Synthetic Aperture Processing (SAP) [1] or “Supercorrelation” [2] which takes the advantage from using a longer coherent integration time, up to couple of seconds, or equivalently very low Phase Locked Loop (PLL) bandwidths. This effectively realizes a Synthetic Antenna Aperture (SAA) being proportional to the inverse of the PLL bandwidth multiplied by the velocity of the antenna. Large SAAs mitigate multipath well and thus the bandwidth of carrier-phase tracking loops should be decreased, e.g. down to 0.1 Hz or lower. This requires removal of Line of Sight (LOS) dynamics from the PLL via inertial aiding and additionally, proper tracking of the oscillator jitter by all tracking channels, so-called Cooperative Tracking Loops (Co-Op). Within an innovative research oriented MATLAB based GPS/Galileo L1/E1/L5/E5a receiver, this will be demonstrated in this paper with real satellite signals. Real Time Kinematics (RTK) processing of the produced GNSS observations demonstrates the high accuracy of this signal processing method.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117334330","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: 1
LTE transmitter states estimation using a combined code and carrier phase observation model 使用组合编码和载波相位观测模型的LTE发射机状态估计
2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) Pub Date : 2023-04-24 DOI: 10.1109/PLANS53410.2023.10139938
M. S. Hameed, Mathias Philips-Blum, Markel Arizabaleta-Diez, T. Pany
{"title":"LTE transmitter states estimation using a combined code and carrier phase observation model","authors":"M. S. Hameed, Mathias Philips-Blum, Markel Arizabaleta-Diez, T. Pany","doi":"10.1109/PLANS53410.2023.10139938","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10139938","url":null,"abstract":"This paper presents a localization framework that consists of a combined code and carrier phase observation model and can be used to estimate the unknown position and clock states of a Long Term Evolution (LTE) transmitter for navigation. The LTE signals are tracked within a Global Navigation Satellite System (GNSS) type receiver architecture, using Multi Sensor Navigation Analysis Tool (MuSNAT) software receiver, for four dynamic receiver trajectories around a target base station. The low noise carrier phase observation enables estimation of the base station position up to sub-meter level accuracy for signal measurements having a sufficiently long duration of stable carrier tracking. The paper presents the localization results of a research-oriented Amarisoft base station pertaining to two receiver platforms - a ground vehicle and an airborne Unmanned Aerial Vehicle (UAV). For each platform, the received LTE signal quality is first analyzed using Code-Minus-Carrier (CMC) time series and then for time durations where the code and phase tracking is stable, the observations are fed into a Kalman filter which estimates the transmitter 3-dimensional position, clock bias and drift over time as well as the LTE carrier phase float ambiguity. The estimated position states results are then compared against a ground-truth measurement of the transmit antenna coordinates, which is obtained using GNSS Real Time Kinematic (RTK) and triangulation with a surveying multi-station device.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125725896","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
A Parametric Study on Autonomous Integrity Monitoring using non-GNSS Signals 基于非gnss信号的自主完整性监测参数化研究
2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) Pub Date : 2023-04-24 DOI: 10.1109/PLANS53410.2023.10139988
F. Rothmaier, J. A. D. Peral-Rosado
{"title":"A Parametric Study on Autonomous Integrity Monitoring using non-GNSS Signals","authors":"F. Rothmaier, J. A. D. Peral-Rosado","doi":"10.1109/PLANS53410.2023.10139988","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10139988","url":null,"abstract":"Navigation integrity is a well-established concept in the aviation domain. Motivated by the increased research on autonomy across all transportation sectors, integrity algorithms are now being explored for new use cases and measurement types. The attempt generally is to pair Global Navigation Satellite Systems (GNSS) signals with an inertial measurement unit (IMU) and measurements from other sensors, such as a camera or signals of opportunity. Two conflicting aspects make this a very challenging problem. On the one hand, tighter protection levels are demanded than those currently available in aviation. On the other hand, these new types of measurements have been less well studied than those from GNSS signals. In addition, they are often received in challenging environments such as urban areas, making it significantly more challenging to bound the errors tails. In this paper, we attempt to identify how this gap between demanded performance and less reliable ranging measurements from fifth generation (5G) cellular networks can be closed. First, we show how to include measurements from non-GNSS sources (i.e., 5G) into a well-established integrity algorithm. We then present a parametric study showing the effect of varying key parameters in the integrity algorithm, such as the measurement's nominal distribution, the probabilities that this nominal distribution is not valid, as well as the continuity and integrity requirements. Our results provide guidance on acceptable values for the nominal measurement model, they indicate that fault rates have to be kept below 10–4 and that a relaxation of the integrity requirement can result in significantly tighter protection levels.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125733880","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
LEO-PNT Mega-Constellations: a New Design Driver for the Next Generation MEO GNSS Space Service Volume and Spaceborne Receivers LEO-PNT巨型星座:下一代MEO GNSS空间业务量和星载接收机的新设计驱动力
2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) Pub Date : 2023-04-24 DOI: 10.1109/PLANS53410.2023.10140052
F. Menzione, M. Paonni
{"title":"LEO-PNT Mega-Constellations: a New Design Driver for the Next Generation MEO GNSS Space Service Volume and Spaceborne Receivers","authors":"F. Menzione, M. Paonni","doi":"10.1109/PLANS53410.2023.10140052","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140052","url":null,"abstract":"A huge number of LEO-PNT research activities were initiated in the past, but today many companies have already started to implement or deploy such kind of services by adapting pre-existent broadband telecom mega-constellation or exploiting reduced cost platforms embarking dedicated payloads. This new paradigm can be disruptive with respect to the conventional MEO approach. Actually, from a policy point of view, the feeling is that, in the long term scenario where such a system will flight, a user terminal can potentially exploit thousands of signals, whose small percentage is transmitted by the MEO GNSS. This can be referred to as “MEO shadowing”. This paper works in the opposite direction, trying to assess how fundamental the core MEO-GNSS infrastructure is not only for the effective deployment of the LEO-PNT services, but also for the MEO GNSS evolution. A change of perspective should be considered.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124736663","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: 3
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