Principles of Organizing Earthquake Forecasting Based on Multiparameter Sensor-WEB Monitoring Data

The paper describes an approach that allows, basing on the data of multiparameter monitoring of atmospheric and ionospheric parameters and using ground-based and satellite measurements, to select from the data stream a time interval indicating the beginning of the final stage of earthquake preparation, and finally using intelligent data processing to carry out a short-term forecast for a time interval of 2 weeks to 1 day before the main shock. Based on the physical model of the lithosphere-atmospheric-ionospheric coupling, the precursors are selected, the ensemble of which is observed only during the precursory periods, and their identification is based on morphological features determined by the physical mechanism of their generation, and not on amplitude selection based on statistical data processing. Basing on the developed maquette of the automatic processing service, the possibility of real-time monitoring of the situation in a seismically active region will be demonstrated using the territory of the Kamchatka region and the Kuril Islands

From Hector Mine M7.1 to Ridgecrest M7.1 Earthquake. A Look from a 20-Year Perspective

The paper provides a comparative analysis of precursory phenomena in the ionosphere and atmosphere for two strong earthquakes of the same magnitude M7.1 that happened in the same region (North-East from Los Angeles) within a time span of 20 years, the Hector Mine and Ridgecrest earthquakes. Regardless of the similarity of their location (South-Eastern California, near 160 km one from another), there was one essential difference: the Hector Mine earthquake happened during geomagnetically disturbed conditions (essential in the sense of ionospheric precursors identification). In contrast, the quiet geomagnetic conditions characterized the period around the time of the Ridgecrest earthquake. The Hector mine earthquake happened in the middle of the rising phase of the 23-rd solar cycle characterized by high solar activity, while the Ridgecrest earthquake happened by the very end of the 24th cycle under very low solar activity conditions. We provide a comprehensive multi-factor analysis, determine the precursory period for both earthquakes and demonstrate the close similarity of ionospheric precursors. Unlike the majority of papers dealing with earthquake precursor identification based on the “abnormality” of observed time-series mainly determined by amplitude difference between “normal” (usually climatic) behavior and “abnormal” behavior with amplitudes exceeding some pre-established threshold, we used the technique of cognitive recognition of the precursors based on the physical mechanisms of their generation and the morphology of their behavior during the precursory period. These permits to uniquely identify precursors even in conditions of disturbed environment as it was around the time of the Hector Mine earthquake. We demonstrate the close similarity of precursors’ development for both events. The leading time of precursor appearance for the same region and similar magnitude was identical. For the Hector Mine it was 11 October 1999—5 days in advance—and for 2019 Ridgecrest it was 28 June—7 days before the mainshock and five days before the strongest foreshock

Simulation of continuous detonation in H2-O2 mixture using adaptive mesh refinement

The necessity to have a fine resolution within a large computational domain represents an important difficulty especially for 3D simulations. To cope with this problem, the method of Adaptive Mesh Refinement (AMR) can be used. This paper presents some simulations performed with an Euler solver integrated in an AMR code. Results obtained for a model problem of detonation propagation in a layer of stoichiometric H2-O2 mixture are used to evaluate the AMR code efficiency. Examples of 2D and 3D simulations of continuous detonation wave are presented

PIV Measurements in an Underexpanded Hot Free Jet

International audienceThe objective of the work reported herein is to demonstrate the ability of the PIV technique to provide correct measurements of the velocity field in steady underexpanded hot free jets. A hot-gas generator capable to create jets with an initial diameter of 25 mm, total pressure up to 4 MPa, and total temperature up to 2200 K is presented together with the associated technique of stagnation conditions determination. The implementation of the PIV method is described paying attention to the choice of the PIV system components and to the seeding technique. Experimental results are presented on the observed jet structure and directly measured geometry of the Mach disk. The results on the velocity field are analyzed considering the effect of the kind of seeding particles as well as the jet stagnation conditions. Results from the experiment and numerical simulation are compared to validate the measurements of the velocity field

Rotating detonation combustors for propulsion: Some fundamental, numerical and experimental aspects

Propulsion systems based on the constant-pressure combustion process have reached maturity in terms of performance, which is close to its theoretical limit. Technological breakthroughs are needed to develop more efficient transportation systems that meet today’s demands for reduced environmental impact and increased performance. The Rotating Detonation Engine (RDE), a specific implementation of the detonation process, appears today as a promising candidate due to its high thermal efficiency, wide operating Mach range, short combustion time and, thus, high compactness. Following the first proofs of concept presented in the 1960s, the last decade has seen a significant increase in laboratory demonstrators with different fuels, injection techniques, operating conditions, dimensions and geometric configurations. Recently, two flight tests of rocket-type RDEs have been reported in Japan and Poland, supervized by Professors Kasahara (Nagoya University) and Wolanski (Warsaw University), respectively. Engineering approaches are now required to design industrial systems whose missions impose efficiency and reliability constraints. The latter may render ineffective the simplified solutions and configurations developed under laboratory conditions. This requires understanding the fundamentals of detonation dynamics relevant to the RDE and the interrelated optimizations of the device components. This article summarizes some of the authors’ experimental and numerical work on fundamental and applied issues now considered to affect, individually or in combination, the efficiency and reliability of the RDE. These are the structure of the detonation reaction zone, the detonation dynamics for rotating regimes, the injection configurations, the chamber geometry, and the integration constraints

Detonation in hydrogen–nitrous oxide–diluent mixtures: An experimental and numerical study

Knowledge of H_2–N_2O mixtures explosive properties is important to the safety of nuclear waste storage and semi-conductor manufacturing processes. The present study provides new experimental data on H_2–N_2O detonations, and proposes a thermochemical model which is used to numerically simulate detonation propagation. Detonation cell size has been measured in a variety of H_2–N_2O–Ar mixtures. Even at low initial pressure, these mixtures are very sensitive to detonation with cell size of few millimeters. Using a reduced version of a detailed reaction scheme, 2-D Euler simulations have been used to examine the features of detonation in H_2–N_2O–Diluent mixtures. A PLIF model has been applied to allow for direct comparison with experimental results. Statistical analysis of the cellular cycle dynamics has been performed

Ionosphere sounding for pre-seismic anomalies identification (INSPIRE): results of the project and perspectives for the short-term earthquake forecast

The INSPIRE project was dedicated to the study of physical processes and their effects in ionosphere which could be determined as earthquake precursors together with detailed description of the methodology of ionospheric pre-seismic anomalies definition. It was initiated by ESA and carried out by an international consortium. The full set of key parameters of the ionospheric plasma was selected based on the retrospective analysis of the ground-based and satellite measurements of pre-seismic anomalies. Using this classification the multi-instrumental database of worldwide relevant ionospheric measurements (ionosonde and GNSS networks, LEO-satellites with in situ probes including DEMETER and FORMOSAT/COSMIC ROC missions) was developed for the time intervals related to selected test cases. As statistical processing shows, the main ionospheric precursors appear approximately 5 days before the earthquake within the time interval of 30 days before and 15 days after an earthquake event. The physical mechanisms of the ionospheric pre-seismic anomalies generation from ground to the ionosphere altitudes were formulated within framework of the Lithosphere-Atmosphere- Ionosphere Coupling (LAIC) model. The processes of precursor’s development were analyzed starting from the crustal movements, radon emission and air ionization, thermal and atmospheric anomalies, electric field and electromagnetic emissions generation, variations of the ionospheric plasma parameters, in particular vertical TEC and vertical profiles of the electron concentration. The assessment of the LAIC model performance with definition of performance criteria for earthquake forecasting probability has been done in statistical and numerical simulation domains of the Global Electric Circuit. The numerical simulations of the earthquake preparation process as an open complex system from start of the final stage of earthquake preparation up to the final point–main shock confirms that in the temporal domain the ionospheric precursors are one of the most late in the sequence of precursors. The general algorithm for the identification of the ionospheric precursors was formalized which also takes into account the external Space Weather factors able to generate the false alarms. The importance of the special stable pattern called the “precursor mask” was highlighted which is based on self-similarity of pre-seismic ionospheric variations. The role of expert decision in pre-seismic anomalies interpretation for generation of seismic warning is important as well. The algorithm performance of the LAIC seismo-ionospheric effect detection module has been demonstrated using the L’Aquila 2009 earthquake as a case study. The results of INSPIRE project have demonstrated that the ionospheric anomalies registered before the strong earthquakes could be used as reliable precursors. The detailed classification of the pre-seismic anomalies was presented in different regions of the ionosphere and signatures of the pre-seismic anomalies as detected by ground and satellite based instruments were described what clarified methodology of the precursor’s identification from ionospheric multi-instrumental measurements. Configuration for the dedicated multiobservation experiment and satellite payload was proposed for the future implementation of the INSPIRE project results. In this regard the multi-instrument set can be divided into two groups: space equipment and ground-based support, which could be used for realtime monitoring. Together with scientific and technical tasks the set of political, logistic and administrative problems (including certification of approaches by seismological community, juridical procedures by the governmental authorities) should be resolved for the real earthquake forecast effectuation.In years 2014–2016 works were supported by the ESA Project “INSPIRE, ionosphere Sounding for Pre-seismic anomalies Identification Research (INSPIRE)” nr 4000,111,456/14/NL/ MV. The work is supported by the National Center for Research and Development, Poland, through Grant ARTEMIS (decision no. DWM/PL-CHN/97/2019, WPC1/ ARTEMIS/2019); The authors thank also the Ministry of Science and Higher Education (MSHE), Poland for granting funds for the Polish contribution to the International LOFAR Telescope “(MSHE decision no. DIR/ WK/2016/2017/05–1)” and for maintenance of the LOFAR PL-612 Baldy (MSHE decisions: no. 59/E-383/SPUB/SP/ 2019.1). This work is supported by the National Science Centre, Poland, through Grants 2017/25/B/ST10/00479 and 2017/27/B/ST10/02190.Peer ReviewedPostprint (published version

Transient effects in atmosphere and ionosphere preceding the 2015 M7.8 and M7.3 Gorkha–Nepal earthquakes

We analyze retrospectively/prospectively the transient variations of six different physical parameters in the atmosphere/ionosphere during the M7.8 and M7.3 earthquakes in Nepal, namely: 1) outgoing longwave radiation (OLR) at the top of the atmosphere (TOA); 2) GPS/TEC; 3) the very-low-frequency (VLF/LF) signals at the receiving stations in Bishkek (Kyrgyzstan) and Varanasi (India); 4) Radon observations; 5) Atmospheric chemical potential from assimilation models; and; 6) Air Temperature from NOAA ground stations. We found that in mid-March 2015, there was a rapid increase in the radiation from the atmosphere observed by satellites. This anomaly was located close to the future M7.8 epicenter and reached a maximum on April 21–22. The GPS/TEC data analysis indicated an increase and variation in electron density, reaching a maximum value during April 22–24. A strong negative TEC anomaly in the crest of EIA (Equatorial Ionospheric Anomaly) occurred on April 21, and a strong positive anomaly was recorded on April 24, 2015. The behavior of VLF-LF waves along NWC-Bishkek and JJY-Varanasi paths has shown abnormal behavior during April 21–23, several days before the first, stronger earthquake. Our continuous satellite OLR analysis revealed this new strong anomaly on May 3, which was why we anticipated another major event in the area. On May 12, 2015, an M7.3 earthquake occurred. Our results show coherence between the appearance of these pre-earthquake transient’s effects in the atmosphere and ionosphere (with a short time-lag, from hours up to a few days) and the occurrence of the 2015 M7.8 and M7.3 events. The spatial characteristics of the pre-earthquake anomalies were associated with a large area but inside the preparation region estimated by Dobrovolsky-Bowman. The pre-earthquake nature of the signals in the atmosphere and ionosphere was revealed by simultaneous analysis of satellite, GPS/TEC, and VLF/LF and suggest that they follow a general temporal-spatial evolution pattern that has been seen in other large earthquakes worldwide

Contribution au développement des outils de simulation numérique de la combustion supersonique

fichier pdf généré le 2006-04-21This thesis, consisting of four chapters, concerns the improvement and development of models for the numerical simulation of the supersonic combustion. Chapter 1 describes the theoretical base of a computational code dedicated to the simulation of compressible reactive turbulent flows. Chapter 2 presents the improvements introduced in the k-epsilon turbulence model, namely the implementation of the Pope and Sarkar corrections and the validation of the model for compressible flows such as the plane mixing layer and round jet. A stabilizing limitation has been proposed for the Pope correction ensuring an accurate prediction of the jet spreading rate. A postprocessing of data from a direct simulation of a turbulent non-isothermal two-species mixing layer permitted to evaluate the ratio of the turbulent Prandtl and Schmidt numbers. Chapter 3 is devoted to the chemical kinetic models. A new method for the automatic reduction of chemical kinetic mechanisms has been elaborated and then applied to the development of reduced chemical models for the reactive mixtures CH4-H2-air and H2-vitiated air. A new empirical correlation for the autoignition delay time of the CH4-H2-air mixture has been proposed. The reduced mechanisms have been validated for homogeneous conditions and for a diffusive medium. Chapter 4 presents the methodology and results of a numerical study on a supersonic combustion chamber. The methodological aspects of this study are: the validation of numerical models, the choice of the boundary conditions, the mesh adaptation, and the comparison of two- and three-dimensional configurations.Cette thèse, composée de quatre chapitres, porte sur l'amélioration et le développement de modèles pour la simulation numérique de la combustion supersonique. Le 1er chapitre décrit les bases théoriques d'un code de calcul destiné à la simulation des écoulements compressibles réactifs turbulents. Le 2e chapitre présente les améliorations apportées au modèle de turbulence k-epsilon, notamment l'implantation des corrections de Pope et Sarkar et la validation du modèle pour des écoulements compressibles tels que la couche de mélange plane et le jet rond. Une limitation stabilisatrice a été proposée pour la correction de Pope assurant une prédiction précise de l'épanouissement du jet rond. Un post-traitement de données d'une simulation directe d'une couche de mélange turbulente non isotherme bi-espèces a permis d'évaluer le rapport des nombres de Prandtl et de Schmidt turbulents. Le 3e chapitre est consacré aux modèles cinétiques chimiques. Une nouvelle méthode de réduction automatique de mécanismes cinétiques chimiques a été élaborée puis appliquée au développement de modèles chimiques réduits pour les mélanges réactifs CH4-H2-air et H2-air vicié. Une nouvelle corrélation empirique pour le délai d'autoinflammation du mélange CH4-H2-air a été proposée. Les mécanismes réduits ont été validés dans des conditions homogènes et dans un milieu diffusif. Le 4e chapitre présente la méthodologie et les résultats d'une étude numérique sur une chambre de combustion supersonique. L'aspect méthodologique de cette étude concerne : la validation des modèles numériques, le choix des conditions aux limites, l'adaptation du maillage et la comparaison des configurations bi- et tridimensionnelle