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Result of the MICROSCOPE weak equivalence principle test / Pierre Touboul in Classical and Quantum Gravity, vol 39 n° 20 (October 2022)  

Public [article]  inClassical and Quantum Gravity > vol 39 n° 20 (October 2022) . - n° 2004009 Titre : Result of the MICROSCOPE weak equivalence principle test Type de document : Article/Communication Auteurs : Pierre Touboul, Auteur ; Gilles Métris, Auteur ; Manuel Rodrigues, Auteur ; et al., Auteur ; Isabelle Panet , Auteur Année de publication : 2022 Article en page(s) : n° 2004009 Note générale : bibliographie Pierre Touboul, Gilles Métris, Manuel Rodrigues, Joel Bergé, Alain Robert, Quentin Baghi, Yves André, Judicael Bedouet, Damien Boulanger, Stefanie Bremer, Patrice Carle, Ratana Chhun, Bruno Christophe, Valerio Cipolla, Thibault Damour, Pascale Danto, Louis Demange, Hansjoerg Dittus, Océane Dhuicque, Pierre Fayet, Bernard Foulon, Pierre-Yves Guidotti, Daniel Hagedorn, Emilie Hardy, Phuong-Anh Huynh, Patrick Kayser, Stephanie Lala, Claus Lämmerzah, Vincent Lebat, Françoise Liorzou, Meike List, Frank Löffler, Isabelle Panet, Martin Pernot-Borràs, Laurent Perraud, Sandrine Pires, Benjamin Pouilloux, Pascal Prieur, Alexandre Rebray, Serge Reynaud, Benny Rievers, Hanns Selig, Laura Serron, Timothy Sumner, Nicolas Tanguy, Patrizia Torresi and Pieter Visser. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] accéléromètre [Termes IGN] MICROSCOPE (mission) [Termes IGN] mission spatiale [Termes IGN] principe d'équivalence Résumé : (auteur) The space mission MICROSCOPE dedicated to the test of the equivalence principle (EP) operated from April 25, 2016 until the deactivation of the satellite on October 16, 2018. In this analysis we compare the free-fall accelerations (aA and aB) of two test masses in terms of the Eötvös parameter $\eta (\text{A,B})=2\frac{{a}_{\mathrm{A}}-{a}_{\mathrm{B}}}{{a}_{\mathrm{A}}+{a}_{\mathrm{B}}}$. No EP violation has been detected for two test masses, made from platinum and titanium alloys, in a sequence of 19 segments lasting from 13 to 198 h down to the limit of the statistical error which is smaller than 10−14 for η(Ti, Pt). Accumulating data from all segments leads to η(Ti, Pt) = [−1.5 ± 2.3 (stat) ± 1.5 (syst)] × 10−15 showing no EP violation at the level of 2.7 × 10−15 if we combine stochastic and systematic errors quadratically. This represents an improvement of almost two orders of magnitude with respect to the previous best such test performed by the Eöt-Wash group. The reliability of this limit has been verified by comparing the free falls of two test masses of the same composition (platinum) leading to a null Eötvös parameter with a statistical uncertainty of 1.1 × 10−15. Numéro de notice : A2022-690 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1088/1361-6382/ac84be En ligne : https://doi.org/10.1088/1361-6382/ac84be Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101804 [article]

MICROSCOPE Mission: Final Results of the Test of the Equivalence Principle / Pierre Touboul in Physical Review Letters, vol 129 n° 12 ([01/09/2022])  

Public [article]  inPhysical Review Letters > vol 129 n° 12 [01/09/2022] . - n° 121102 Titre : MICROSCOPE Mission: Final Results of the Test of the Equivalence Principle Type de document : Article/Communication Auteurs : Pierre Touboul, Auteur ; Gilles Métris, Auteur ; Manuel Rodrigues, Auteur ; et al., Auteur ; Isabelle Panet , Auteur Année de publication : 2022 Article en page(s) : n° 121102 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] accélération de la pesanteur [Termes IGN] accéléromètre [Termes IGN] erreur systématique [Termes IGN] MICROSCOPE (mission) [Termes IGN] principe d'équivalence Résumé : (auteur) The MICROSCOPE mission was designed to test the weak equivalence principle (WEP), stating the equality between the inertial and the gravitational masses, with a precision of 10−15 in terms of the Eötvös ratio η. Its experimental test consisted of comparing the accelerations undergone by two collocated test masses of different compositions as they orbited the Earth, by measuring the electrostatic forces required to keep them in equilibrium. This was done with ultrasensitive differential electrostatic accelerometers onboard a drag-free satellite. The mission lasted two and a half years, cumulating five months worth of science free-fall data, two-thirds with a pair of test masses of different compositions—titanium and platinum alloys—and the last third with a reference pair of test masses of the same composition—platinum. We summarize the data analysis, with an emphasis on the characterization of the systematic uncertainties due to thermal instabilities and on the correction of short-lived events which could mimic a WEP violation signal. We found no violation of the WEP, with the Eötvös parameter of the titanium and platinum pair constrained to η(Ti,Pt)=[−1.5±2.3(stat)±1.5(syst)]×10−15 at 1σ in statistical errors. Numéro de notice : A2022-691 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1103/PhysRevLett.129.121102 En ligne : https://dx.doi.org/10.1103/PhysRevLett.129.121102 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101806 [article]

Application of machine learning to predict transport modes from GPS, accelerometer, and heart rate data / Santosh Giri in International Journal of Health Geographics, vol 21 (2022)  

Public [article]  inInternational Journal of Health Geographics > vol 21 (2022) . - n° 19 Titre : Application of machine learning to predict transport modes from GPS, accelerometer, and heart rate data Type de document : Article/Communication Auteurs : Santosh Giri, Auteur ; Ruben Brondeel, Auteur ; Tarik El Aarbaoui, Auteur ; Basile Chaix, Auteur Année de publication : 2022 Article en page(s) : n° 19 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] accéléromètre [Termes IGN] bicyclette [Termes IGN] données GPS [Termes IGN] données médicales [Termes IGN] Ile-de-France [Termes IGN] transport public Résumé : (auteur) Background : There has been an increased focus on active transport, but the measurement of active transport is still difficult and error-prone. Sensor data have been used to predict active transport. While heart rate data have very rarely been considered before, this study used random forests (RF) to predict transport modes using Global Positioning System (GPS), accelerometer, and heart rate data and paid attention to methodological issues related to the prediction strategy and post-processing. Methods : The RECORD MultiSensor study collected GPS, accelerometer, and heart rate data over seven days from 126 participants living in the Ile-de-France region. RF models were built to predict transport modes for every minute (ground truth information on modes is from a GPS-based mobility survey), splitting observations between a Training dataset and a Test dataset at the participant level instead at the minute level. Moreover, several window sizes were tested for the post-processing moving average of the predicted transport mode. Results : The minute-level prediction rate of being on trips vs. at a visited location was 90%. Final prediction rates of transport modes ranged from 65% for public transport to 95% for biking. Using minute-level observations from the same participants in the Training and Test sets (as RF spontaneously does) upwardly biases prediction rates. The inclusion of heart rate data improved prediction rates only for biking. A 3 to 5-min bandwidth moving average was optimum for a posteriori homogenization. Conclusion : Heart rate only very slightly contributed to better predictions for specific transport modes. Moreover, our study shows that Training and Test sets must be carefully defined in RF models and that post-processing with carefully chosen moving average windows can improve predictions. Numéro de notice : A2022-077 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1186/s12942-022-00319-y Date de publication en ligne : 16/11/2022 En ligne : https://doi.org/10.1186/s12942-022-00319-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102445 [article]

Impact of temperature stabilization on the strapdown airborne gravimetry: a case study in Central Turkey / Mehmet Simav in Journal of geodesy, vol 94 n°4 (April 2020)  

Public [article]  inJournal of geodesy > vol 94 n°4 (April 2020) Titre : Impact of temperature stabilization on the strapdown airborne gravimetry: a case study in Central Turkey Type de document : Article/Communication Auteurs : Mehmet Simav, Auteur ; David Becker, Auteur ; Hasan Yildiz, Auteur ; Matthias Hoss, Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] accéléromètre [Termes IGN] centrale inertielle à composants liés [Termes IGN] contrôle thermique [Termes IGN] étalonnage d'instrument [Termes IGN] filtre de Kalman [Termes IGN] gravimétrie aérienne [Termes IGN] réalité de terrain [Termes IGN] température [Termes IGN] Turquie Résumé : (auteur) Airborne gravimetry with strapdown inertial sensors has been a valuable tool for many years to fill in the gravity data gaps on the areas not accessible by land. Accuracies of 1 mGal level with off-the-shelf navigation-grade inertial measurement units (IMU) can only be achieved provided that the accelerometer drifts mainly caused by the temperature variations inside the IMU housing are separated from the gravity signal. Although there are several strategies proposed in the literature to deal with this inseparability problem, we use a thermal stabilization system (iTempStab) added on an iNAT-RQH navigation-grade IMU and investigate its performance over a test region in central Turkey with moderate topography and highly qualified ground truth gravity data. Two test flights were performed in 2017 and 2018 with and without iTempStab add-on following almost the same flight trajectories. During the first flight in 2017 with iNAT-RQH only, which lasted almost 5.5 h, there were considerable temperature variations inside the IMU housing from 39.1 to 46.0 °C. A simple thermal correction based on a laboratory calibration done before the flight was applied to the vertical Z-accelerometer in the pre-processing stage. However, temperature changes were within 0.1 °C during the second test flight in 2018 with TempStab add-on. The temperature stabilization gained by the iTempStab add-on produced better cross-over statistics. While the RMSE of the non-adjusted cross-over residuals was about 2.6 mGal, it reduced by 50% with iTempStab add-on. The adjusted cross-over differences of the 2018 flight yielded an RMSE of about 0.5 mGal, which is a remarkable precision for the strapdown gravimetry. The comparison with upward continued ground gravity data at flight altitudes suggests that the thermal stabilization system shows also remarkable improvements in the residual statistics. The range of the residuals decreases from ± 10 to ± 5 mGal, the standard deviation decreases from 2.19 to 0.94 mGal, and the RMSE decreases from 2.24 to 1.48 mGal, respectively, with the iTempStab add-on. It can be concluded that the thermal stabilization system significantly improves the accelerometer stability and therefore the precision and accuracy of the strapdown airborne gravity estimates. Numéro de notice : A2020-158 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01369-5 Date de publication en ligne : 17/03/2020 En ligne : https://doi.org/10.1007/s00190-020-01369-5 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94812 [article]

Robust deformation monitoring of bridge structures using MEMS accelerometers and image-assisted total stations / Mohammad Omidalizarandi (2020)  

Public Titre : Robust deformation monitoring of bridge structures using MEMS accelerometers and image-assisted total stations Type de document : Thèse/HDR Auteurs : Mohammad Omidalizarandi, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2020 Collection : DGK - C, ISSN 0065-5325 num. 859 Importance : 260 p. Format : 21 x 30 cm Note générale : bibliographie Diese Arbeit ist gleichzeitig veröffentlicht in: Wissenschaftliche Arbeiten der Fachrichtung Geodäsie und Geoinformatik der Universität Hannover, ISSN 0174-1454, Nr. 366 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] accéléromètre [Termes IGN] algorithme espérance-maximisation [Termes IGN] auscultation d'ouvrage [Termes IGN] méthode robuste [Termes IGN] microsystème électromécanique [Termes IGN] pont [Termes IGN] surveillance d'ouvrage [Termes IGN] tachéomètre électronique [Termes IGN] topométrie de précision Résumé : (auteur) Today, short- and long-term structural health monitoring (SHM) of bridge structures has received considerable attention. However, permanent, cost-effective, and reliable monitoring are still challenging issues. From a surveying or civil engineer's point of view, vibration-based SHM is often carried out by inspecting the changes in the dynamic responses of bridge structures known as modal parameters, such as eigen frequencies, eigenforms and modal damping. The use of cost-effective micro-electro-mechanical-systems (MEMS) accelerometers with a high sampling frequency is becoming more affordable and feasible for the aforementioned monitoring task. Within this dissertation, a three-step scenario is proposed to choose a suitable MEMS accelerometer despite of its purchase price, measurement range and sampling frequency. Firstly, a robust calibration procedure is proposed and implemented to model MEMS related systematic errors such as biases, scale factors, and non-orthogonality angles between the axes. Secondly, a controlled excitation experiment is conducted by using a high-precision shaker. Thirdly, a statictest experiment is accomplished over a long period. Robust, accurate, and automatic estimation of the modal parameters is particularly challenging when vibration measurements are contaminated with a high coloured measurement noise, e.g., due to cost-effective MEMS acceleration data. This is even more challenging when the structure is continuously under imposed forces due to moving vehicles or wind. For this purpose, a robust and automatic vibration analysis procedure the so–called robust time domain modal parameter identification (RT-MPI) approach is proposed and implemented. It is a novel approach in the sense of automatic excitation (e.g. ambient) window selection, automatic and reliable identification of initial eigen frequencies even closely spaced ones as well as robustly and accurately estimating the modal parameters. To estimate frequencies, damping ratio coefficients, amplitudes, and phase shifts, an observation model consisting of a damped harmonic oscillation (DHO) model, an autoregressive model of coloured measurement noise and a stochastic model in the form of the heavy-tailed family of scaled t-distributions with unknown degree of freedom and scale factor, is employed. The aforementioned three parametric models are jointly adjusted by means of a generalised expectation maximisation (GEM) algorithm. The proposed RT-MPI algorithm is also able to estimate amplitudes in a metric unit and with a high accuracy for the recorded acceleration data by means of double integration of the DHO model. The eigenforms are characterised in a subsequent step, and by using the estimated parameters from the GEM algorithm. In addition, having amplitudes in the metric unit allows to characterise deflection eigen forms in their true scales for selected excitation windows within short time intervals. The deformation/displacement monitoring by merely using the MEMS accelerometer is challenging, since it suffers from accuracy degradation with time for absolute position/displacement estimates. Therefore, the MEMS accelerometers and an image-assisted total station (IATS) are fused by performing one-dimensional (1D) coordinate update within the Kalman filtering framework. To generate 1D displacement data from the IATS, video frames of a passive target, that is attached to a bridge structure, are captured by means of a telescope camera of the IATS. A passive target centroid detection algorithm is proposed and implemented, which is robust and reliable with respect to poor environmental conditions, such as low lighting, dusty situations, and skewed angle targets. Next, an angular conversion factor of the telescope camera is calibrated, which allows to convert the generated displacement data from pixel to metric unit. Experiments are performed in four case studies including simulation, controlled excitation and two real applications of a footbridge structure and a synthetic bridge. The estimated modal parameters are compared and validated by their true values as well as their corresponding estimates obtained from reference sensors such as reference accelerometer, geophone, and laser tracker. Additionally, the estimated eigen frequencies and damping ratio coefficients are compared with a well-known covariance driven stochastic subspace identification (SSI-COV) approach. The results show that the MEMS accelerometers are suitable for identifying all occurring eigen frequencies of the bridge structures. Moreover, the vibration analysis procedure demonstrates that amplitudes are estimated in submillimetre range accuracy, frequencies with an accuracy of better than 0.1 Hz and damping ratio coefficients with an accuracy of better than 0.1 and 0.2%for modal and system damping, respectively. The analysis reveals the superiority of the proposed RT-MPI algorithm compared to the SSI-COV algorithm. Finally, a high accurate displacement time series at the level of submillimetre is generated by fusion of the IATS and the MEMS measurements. Numéro de notice : 17680 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère En ligne : https://dgk.badw.de/fileadmin/user_upload/Files/DGK/docs/c-859.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98021

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Error analysis of a new planar electrostatic gravity gradiometer for airborne surveys / Karim Douch in Journal of geodesy, vol 89 n° 12 (december 2015)  

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Drift mode accelerometry for spaceborne gravity measurements / John W. Conklin in Journal of geodesy, vol 89 n° 11 (november 2015)  

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