bluuebunny/crossref_metadata_2025 huggingface dataset:
Analisi Proses Pembelajaran Matematika dengan Pendekatan Metakognitif-Diskursif Menggunakan Sistem Kategori
Authors: Napu Timotius Woda , Lubur Dorothea Novia Ludo , Nambers Dominikus Savio
Published: May 2024

Penelitian ini diharapkan dapat memberikan kontribusi signifikan dalam meningkatkan pemahaman siswa, pengembangan keterampilan metakognitif, serta meningkatkan interaksi dan diskusi yang produktif dalam pembelajaran matematika. Tujuan dari penelitian ini adalah untuk mengetahui proses pembelajaran matematika dengan pendekatan metakognitif-diskursif menggunakan sistem kategori. Jenis Penelitian yang digunakan dalam penelitian ini adalah penelitian deskriptif kualitatif untuk menggambarkan suatu fenomena atau peristiwa dengan menggunakan data kualitatif secara rinci dan detail. Subjek dalam penelitian ini adalah siswa kelas VIII A SMPK St. Paulus karuni yang terdiri dari 18 siswa dan diberikan pembelajaran matematika dengan pendekatan metakognitif-diskursif. Instrumen yang digunakan di dalam penelitian ini adalah lintasan belajar, buku kerja siswa dan lembar catatan harian. Untuk menjacapi tujuan dari penelitian ini, peneliti melakukan beberapa tahapan berupa pengembangan instrument, pengembangan kerangka analisis, implementasi pembelajaran, pengumpulan data, analisis data dan penarikan kesimpulan. Analisis data dalam penelitian ini menggunakan analisis data kualitatif dengan menganalisi proses pembelajaran menggunakan system kategori. Teknik analisis data yang dilakukan berupa reduksi data, penyajian data dan penarikan kesimpulan. Berdasarkan hasil analisis proses pembelajaran, diperoheh hasil yang positif. Hal ini terlihat bahwa aktivitas metakognitif lebih dominan dilakukan antara siswa dengan siswa sendiri tanpa dibanto oleh guru. Proses pembelajaran ini juga tidak terdapaat aktivitas diskursif negatif. Sebaliknya guru membangun budaya diskursif yang berdampak baik bagi siswa sehingga siswa sering terlibat dalam diskusi antara mereka sendiri. Hasil analisis sitem kategori juga menunjukkan bahwa adengan pembelajaran terdiri dari 19 segmen, 14 diantaranya (74%) adalah aktivitas siswa dengan siswa, sedangkan 5 segmen lainya (26%) adalah aktivitas guru dengan siswa.
Виборчі традиції Запорізьких козаків та сучасне виборче законодавство України: порівняльний аналіз
Authors: Марущак Ярослав
Published: May 2024

На сучасному етапі розвитку українського суспільства, історія нашої держави є цікавою для сучасних науковців у контексті не лише переосмислення існуючих фактів, але й з метою формування нових поглядів на певні соціальні явища, зокрема виборчі процеси. На відміну від більшості пострадянських країн, в Україні відбувається постійна зміна влади, а кожні спроби узурпації влади та встановлення тут диктатури закінчуються революціями, особливо за часів нашої незалежності. Використовуючи історичний, системний та міждисциплінарний підхід, з метою пошуку спільних норм, проведено порівняльний аналіз між тогочасними правилами і традиціями Запорізьких козаків та законодавством сучасної незалежної України у виборчій сфері. Проаналізовано основні принципи виборчого права сучасного Виборчого кодексу України, що був прийнятий з урахуванням світових демократичних тенденцій. Встановлено історичні паралелі між Запорізькою Січчю та сучасною Україною. Виявлена значна кількість спільних норм і положень, що співпадають з традиціями при проведенні виборів Кошового отамана у XVII столітті.
Activity of international media in Tajikistan
Authors: Gulov Sangin , Mahmood Ahmed
Published: May 2024

This article informs about the activities of international media in the information space of Tajikistan, including the history, beginning of radio "Ozodi"( Radio Free Europe/Radio Liberty), their goals and tasks, the nature of the propaganda of foreign media in Tajikistan, the conditions of their activity in modern times, the lack of observance of the balance of positions and opinions,and so on. The authors, with specific examples (the case related to the license of the BBC radio by the employees of the Radio "Ozodi"), clearly prove the importance of the presence of international foreign media in the information space of the region, especially Tajikistan, from the point of view of those who, by any means, maintain it. The activity of international media in the information space of another country as an internal media is one of the conditions imposed by superpower countries and human rights organizations. From the study and review of the history of establishment, formation and activity of international media, their goals and duties, it is clear that in the information space of Tajikistan, serious attention is shown to the existence and operation of international media by interested countries and organizations. The reviewed examples testify to this. In the opinion of the authors, if at first glance, making the same issue the subject of the report several times on the radio "Ozodi" appears as a sign of professional solidarity and creative competition, but a little deeper thinking reveals the truth of the interest of this international media. Because, as it is clear from the content of the reports, this media, with such a way of coverage, thinks that such actions of the authorities should be prevented by all possible means, so that there is no interference in the activities of the international media. The authors have strengthened their opinions based on the researchers' thoughts and opinions.
Георгій Павлович Клоков: біографія, творчий шлях, спадщина
Authors: Павленко Руслан
Published: May 2024

В статі представлена стисла характеристика ключових моментів з нарису про життя і творчість Клокова Георгія Павловича. Здійснений перелік його найвідоміших хореографічних постановок на основі репертуару академічного фольклорно-хореографічного ансамблю «Славутич» (м. Дніпро), засновником якого він і був.
Модернізація електроприводів промислових роботів в Україні
Authors: Білюк Іван , Шарейко Дмитро , Савченко Олег , Гаврилов Сергій , Кошкін Дмитро , Пінзул Павло
Published: May 2024

Розглянуто модернізацію електроприводу промислового робота Almega AX - MV6L. Ці роботи широко використовуються в Україні для фігурного вирізування металевих виробів і формування фасок в довільному просторовому положенні. Удосконалення здійснюється за допомогою заміни комплектного електропривода з двигуном постійного струму на сервоелектропривод з синхронним двигуном та цифровою системою автоматичного керування. Синтез регуляторів здійснюється за допомогою методу логарифмічних частотних характеристик. Використання сервоелектропривода як більш простого, надійного і дешевого значно підвищить зазначені показники системи керування.
Вхідний контроль технічного стану аксіально-поршневих гідромашин в технологічному процесі їх ремонту
Authors: Мельянцов Петро , Лосіков Олександр , Сидоренко Віктор
Published: May 2024

Аксіально-поршневі гідромашини, які надходять до сервісних підприємств з їх ремонту, мають різний технічний, що суттєво впливає на якість та собівартість їх ремонту. Мета роботи полягала в зменшенні трудомісткості ремонтних робіт та забезпечення їх якості, розробленням метода діагностування технічного стану гідравлічних агрегатів в технологічному процесі їх ремонту. Для її реалізації розроблено метод діагностування технічного стану деталей качаючих вузлів гідромашин, застосуванням гідравлічного опресування з попередньою подачею рідини до корпусу агрегату під дренажним тиском. Отримані результати вказують на ефективність застосування розробленого методу та засобу діагностування технічного стану аксіально-поршневих гідромашин в технологічному процесії їх ремонту для умов сервісних підприємств.
PREVALÊNCIA DO CÂNCER DE MAMA EM MULHERES DOS 10 AOS 80 ANOS NA MACROREGIÃO OESTE DO PARANÁ
Authors: Frade João Victor de Oliveira Lima Nonaka , Frade Marcelo Nonaka , Gomes Ellen Carolina Zawoski
Published: May 2024

O câncer de mama é o tipo mais comum entre as mulheres e o principal motivo de óbito. Quando metastático, pode afetar outros tecidos corporais, principalmente os pulmões, fígado, ossos e cérebro, aumentando a morbimortalidade. Estimativas apontam aumento na incidência de câncer no Brasil, com destaque para as regiões Sul e Sudeste. Por esse motivo, conhecer a prevalência dessa doença e a principal faixa etária afetada é de suma importância. Dessa forma, objetiva-se com este estudo avaliar a prevalência do câncer de mama, entre 2021 e 2023, em mulheres de 10 a 80 anos, na macrorregião Oeste do Paraná. Para isso, dados foram coletados a partir da plataforma DATASUS, com identificador CID50, na macrorregiões Oeste do Paraná (41070), abrangendo o período de janeiro de 2021 à setembro de 2023. Os resultados revelam que a prevalência de câncer de mama aumentou em 85%, entre os anos de 2021 e 2023. Ainda, a principal faixa etária afetada, foram mulheres entre 40 e 59 anos. O diagnóstico precoce do câncer de mama e o tratamento adequado são de suma importância, melhorando o prognóstico das pacientes.
Technical note: Characterization of a single-beam gradient force aerosol optical tweezer for droplet trapping, phase transition monitoring, and morphology studies
Authors: Pei Xiangyu , Meng Yikan , Chen Yueling , Liu Huichao , Song Yao , Xu Zhengning , Zhang Fei , Preston Thomas C. , Wang Zhibin
Published: May 2024

Abstract. Single particle analysis is essential for a better understanding of the particle transformation process and to predict its environmental impact. In this study, we developed an aerosol optical tweezer (AOT) Raman spectroscopy system to investigate the phase state and morphology of suspended aerosol droplets in real time. The system comprises four modules: optical trapping, reaction, illumination and imaging, and detection. The optical trapping module utilizes a 532 nm laser and a 100 × oil immersion objective to stably trap aerosol droplets within 30 s. The reaction module allows us to adjust relative humidity (RH) and introduce reaction gases into the droplet levitation chamber, facilitating experiments to study liquid–liquid phase transitions. The illumination and imaging module employs a high-speed camera to monitor the trapped droplets, while the detector module records Raman scattering light. We trapped sodium chloride (NaCl) and 3-methyl glutaric acid (3-MGA) mixed droplets to examine RH-dependent morphology changes. Liquid–liquid phase separation (LLPS) occurred when RH was decreased. Additionally, we introduced ozone and limonene/pinene to generate secondary organic aerosol (SOA) particles in situ, which collided with the trapped droplet and dissolved in it. To determine the trapped droplet's characteristics, we utilized an open-source program based on Mie theory to retrieve diameter and refractive index from the observed whispering gallery modes (WGMs) in Raman spectra. It is found that mixed droplets formed core–shell morphology when RH was decreased, and the RH dependence of the droplets' phase transitions generated by different SOA precursors varied. Our AOT system serves as an essential experimental platform for in situ assessment of morphology and phase state during dynamic atmospheric processes.
TROPESS-CrIS CO single-pixel vertical profiles: intercomparisons with MOPITT and model simulations for 2020 western US wildfires
Authors: Luo Ming , Worden Helen M. , Field Robert D. , Tsigaridis Kostas , Elsaesser Gregory S.
Published: May 2024

Abstract. The new TROPESS (TRopospheric Ozone and its Precursors from Earth System Sounding) profile retrievals of carbon monoxide (CO) from the Cross-track Infrared Sounder (CrIS) are evaluated against Measurement of Pollution in the Troposphere (MOPITT) CO version 9 data. Comparison results that were adjusted to common a priori constraints in the retrieval processes have improved agreement between the two data sets over direct comparisons. TROPESS-CrIS CO profiles are within 5 % of MOPITT but have higher concentrations in the lower troposphere and lower concentrations in the upper troposphere. For the intense western US wildfire events in September 2020, we compare CO fields simulated by the GISS climate model to the two satellite CO observations. We show intermediate steps of the comparison process to illustrate the evaluation of model simulations by deriving the “retrieved” model CO profiles as they would be observed by the satellite. This includes the application of satellite level-2 data along with their corresponding diagnostic operators provided in the TROPESS-CrIS and MOPITT products. The process allows a diagnosis of potential model improvements in modeling fire emissions and pollution transport.
An iterative algorithm to simultaneously retrieve aerosol extinction and effective radius profiles using CALIOP
Authors: Chang Liang , Li Jing , Ren Jingjing , Xiong Changrui , Zhang Lu
Published: May 2024

Abstract. The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite has been widely used in climate and environment studies to obtain the vertical profiles of atmospheric aerosols. To retrieve the vertical profile of aerosol extinction, the CALIOP algorithm assumes column-averaged lidar ratios based on a clustering of aerosol optical properties measured at surface stations. On one hand, these lidar ratio assumptions may not be appropriate or representative at certain locations. One the other hand, the two-wavelength design of CALIOP has the potential to constrain aerosol size information, which has not been considered in the operational algorithm. In this study, we present a modified inversion algorithm to simultaneously retrieve aerosol extinction and effective radius profiles using two-wavelength elastic lidars such as CALIOP. Specifically, a lookup table is built to relate the lidar ratio with the Ångström exponent calculated using aerosol extinction at the two wavelengths, and the lidar ratio is then determined iteratively without a priori assumptions. The retrieved two-wavelength extinction at each layer is then converted to the particle effective radius assuming a lognormal distribution. The algorithm is tested on synthetic data, Raman lidar measurements and then finally the real CALIOP backscatter measurements. Results show improvements over the CALIPSO operational algorithm by comparing with ground-based Raman lidar profiles.
Soil contamination in arid environments and assessment of remediation applying surface evaporation capacitor model; a case study from the Judean Desert, Israel
Authors: Golan Rotem , Gavrieli Ittai , Katzir Roee , Sharabi Galit , Nachshon Uri
Published: May 2024

Abstract. Many of the globe arid areas are exposed to severe soil contamination events, due to the presence of highly pollutant industries in these regions. In this work a case study from the Ashalim basin, at the Judean desert, Israel was used to examine the nature of solutes and contaminants transport in sandy terraces of an ephemeral stream that was exposed to a severe pollution event. In order to to shed new light on contaminants distribution along the soil profile and transport mechanisms, in arid environments, three complimentary approaches were used: (1) Periodic on-site soil profile sampling, recording the annual solute transport dynamics; (2) Laboratory analyses and controlled experiments in a rain simulator, to characterize solutes release and transport; and (3) Numerical simulation was used to define and understand the main associated processes. The study highlights the stubborn nature of the pollutants in these natural setting that dictates they will remain near the soil surface, despite the presence of sporadic rain events. It was shown that a vertical circulation of the contaminates is occurring with soil wetting and drying cycles. The ‘surface evaporation capacitor’ concept of Or and Lehmann from 2019 was examined and compared to field measurements and numerical simulations, and found to be a useful tool to predict the fate of the contaminants along the soil profile.
Vertical variability of aerosol properties and trace gases over a remote marine region: A case study over Bermuda
Authors: Ajayi Taiwo Adedayo , Choi Yonghoon , Crosbie Ewan C. , DiGangi Joshua P. , Diskin Glenn S. , Fenn Marta A. , Ferrare Richard A. , Hair Johnathan W. , Hilario Miguel Ricardo A. , Hostetler Chris A. , Kirschler Simon , Moore Richard H. , Shingler Taylor J. , Shook Michael A. , Soloff Cassidy , Thornhill Kenneth L. , Voigt Christiane , Winstead Edward L. , Ziemba Luke , Sorooshian Armin
Published: May 2024

Abstract. Remote marine regions comprise a high fraction of Earth’s surface, but in-situ vertically-resolved measurements over these locations remain scarce. Here we use airborne data during 15 vertical spiral soundings (0.15 – 8.5 km) over Bermuda during the NASA Aerosol Cloud meTeorology Interactions over the western ATlantic Experiment (ACTIVATE) to investigate the impact of different source regions on the vertical structure of trace gases, aerosol particles, and meteorological variables over 1000 km offshore of the U.S. East Coast. Results reveal significant differences in vertical profiles of variables between three different air mass source categories (North America, Ocean, Caribbean/North Africa) identified using the HYSPLIT model: (i) the strongest/weakest pollution signature from North America/Ocean category; (ii) North American air has the highest levels of CO, CH4, submicron particle number concentration, AMS mass, and highest organic mass fraction along with smoke layers in free troposphere (FT); (iii) Ocean air has the highest relative amount of nitrate, non-sea-salt sulfate, and oxalate, which are key acidic species participating in chloride depletion; (iv) pronounced coarse aerosol signature in the FT and reduced aerosol hygroscopicity in air masses from the Caribbean/North Africa associated with dust transport; and (v) considerable vertical heterogeneity for almost all variables examined, including higher O3 and submicron particle concentrations with altitude, suggestive that the FT is a potential contributor of both constituents in the marine boundary layer. This study highlights the importance of considering air mass source origin and vertical resolution to capture aerosol and trace gas properties over remote marine areas.
Biochar reduces early-stage mineralization rates of plant residues more in coarse than fine-texture soils – an artificial soil approach
Authors: Inagaki Thiago M. , Weldon Simon , Bucka Franziska B. , Farkas Eva , Rasse Daniel P.
Published: May 2024

Abstract. Quantifying the impact of biochar on carbon persistence across soil textures is complex, owing to the variability in soil conditions. Using artificial soils with precise textural and mineral composition, we could disentangle the effects of biochar from the effects of soil particle size. We can show that biochar application significantly reduces early-stage carbon mineralization rates of plant residues in various soil textures (from 5 to 41 % clay) but more significantly in sandy soils. This finding suggests that biochar can compensate for the lack of clay in promoting C persistence in soil systems. This short report significantly contributes to understanding soil texture and biochar application interactions.
Measurement report: Temporal variability of vertical profiles of CO2 and CH4 over urban environment
Authors: Zimnoch Mirosław , Gałkowski Michał , Sekuła Piotr , Chmura Łukasz , Bartyzel Jakub , Jasek-Kamińska Alina , Skiba Alicja , Nęcki Jarosław , Wachniew Przemysław , Jagoda Paweł
Published: May 2024

Abstract. Understanding the boundary layer dynamics over urban areas is important to improve estimates of the emissions of greenhouse gases (GHG), and predict their atmospheric mole fractions in these areas. Here we present the results of the annual vertical profiling measurement campaign performed in Krakow (Southern Poland). The campaign consisted of 12 monthly-based diurnal measurements of CO2 and CH4 molar fraction vertical profiles supplemented by meteorological parameters focused on the investigation of the dynamics of nocturnal boundary layer vertical structure within the urban boundary layer. The profile data were collected using two platforms: (i) a tethered touristic balloon operating commercially in the city centre and (ii) a drone system, with the selection of the platform based on operational availability and meteorological conditions. CO2 and CH4 molar fractions were measured using Picarro G2311-f (Picarro Inc., Santa Clara, California, USA) cavity ring-down spectrometer, while the meteorological conditions along the profile were measured using a set of temperature, relative humidity, pressure and wind low-cost sensors dedicated for application on-board of UAV platforms. The obtained results allowed us to analyse in-depth the formation, development and disappearance of the nocturnal boundary layer. In selected profiles, a CO2 and CH4 plumes located over the inversion layer (150–250 m AGL) were detected during the nighttime and morning hours. The application of high-resolution numerical simulations using the WRF-GHG model made it possible to identify the source of CO2 plume as a power plant located ca. 10 km southwest of the balloon launch location.
Phytoplankton adaptation to steady or changing environments affects marine ecosystem functioning
Authors: Hochfeld Isabell , Hinners Jana
Published: May 2024

Abstract. Global warming poses a major threat to marine ecosystems, which fulfill important functions for humans and the climate. Ecosystem models are therefore increasingly used to estimate future changes in the functioning of marine ecosystems. However, projections differ notably between models. We propose that a major uncertainty factor in current models is that they ignore the high adaptive potential of phytoplankton, key players in marine ecosystems. Here, we use a 0-dimensional evolutionary ecosystem model to study how phytoplankton adaptation can affect estimations of future ecosystem-level changes. We found that phytoplankton adaptation can notably change simulated ecosystem dynamics, with the effect depending on environmental conditions. In a steady environment, adaptation allows for a more efficient use of resources, which enhances primary production and related ecosystem functions. In a warming environment, on the contrary, adaptation mitigates dominance changes among functionally different taxa and consequently leads to weaker changes in related ecosystem functions. Our results demonstrate that by neglecting phytoplankton adaptation, models may systematically overestimate future changes in the functioning of marine ecosystems. Future work can build on our results and include evolutionary processes into more complex model environments.
Dynamic and thermodynamic contribution to the October 2019 exceptional rainfall in West Central Africa
Authors: Kenfack Kevin , Marra Francesco , Djomou Zéphirin Yepdo , Tchotchou Lucie A. Djiotang , Tamoffo Alain T. , Vondou Derbetini A.
Published: May 2024

Abstract. Exceptional rainfall hit West Central Africa in October 2019. To understand the underlying mechanisms, we diagnosed the regional moisture and Moist Static Energy (MSE) budgets with a view to highlighting the importance of the dynamic and thermodynamic effects associated with this historic event. Analysis of the moisture budget reveals that the precipitation anomalies in October were mainly controlled by dynamic effects (72.5 % of the sum of dynamic and thermodynamic contributions). Horizontal moisture advection induced by horizontal wind anomalies controls extreme precipitation north of West Central Africa, while vertical moisture advection induced by vertical velocity anomalies controls extreme precipitation south of West Central Africa. Changes in the thermodynamic effect, although not the key factor responsible for the events of October 2019, contribute up to 27.5 % of the total effect. Diagnosis of the MSE balance shows that the anomalous vertical motion is dominated by the dynamic effect, i.e. the wet enthalpy advection induced by the horizontal wind anomalies. The horizontal advection of the MSE induced by the variation of the wet enthalpy and the vertical advection of the MSE induced by the variation of the MSE seem less important. The variations in the MSE balance are linked to its meridional component, in particular the meridional wind anomalies in the dynamic effect and the meridional variations in latent heat in the thermodynamic effect. This is due to the increase in sea surface temperatures in the equatorial Atlantic, associated with the anomalous thermal depression over the Sahara, which has increased rainfall over West Central Africa. Our results suggest that dynamic and thermodynamic effects should be jointly considered for adequately anticipating this kind of extreme event. Understanding the associated mechanisms could help us improve our projections and increase the region's population resilience to these extreme weather events.
First results of the polar regional climate model RACMO2.4
Authors: van Dalum Christiaan T. , van de Berg Willem Jan , Gadde Srinidhi N. , van Tiggelen Maurice , van der Drift Tijmen , van Meijgaard Erik , van Ulft Lambertus H. , van den Broeke Michiel R.
Published: May 2024

Abstract. A next version of the polar regional climate model RACMO (referred to as RACMO2.4p1) is presented in this study. The principal update includes embedding of the package of physical parameterizations of the Integrated Forecast System (IFS) cycle 47r1. This constitutes changes in the precipitation, convection, turbulence, aerosol and surface schemes, and includes a new cloud scheme with more prognostic variables and a dedicated lake model. Furthermore, the stand-alone IFS radiation physics module ecRad is incorporated in RACMO, and a multi-layer snow module for non-glaciated regions is introduced. Other updates involve the introduction of a fractional land-ice mask, new and updated climatological data sets, such as aerosol concentrations and leaf-area index, and the revision of several parameterizations specific to glaciated regions. As a proof of concept, we show first results for Greenland, Antarctica and a region encompassing the Arctic. By comparing the results with observations and the output from the previous model version (RACMO2.3p3), we show that the model performs well regarding the surface mass balance, surface energy balance, temperature, wind speed, cloud content and snow depth. The advection of snow hydrometeors strongly impacts the ice sheet's local surface mass balance, particularly in high-accumulation regions such as southeast Greenland and the Antarctic Peninsula. We critically assess the model output and identify some processes that would benefit from further model development.
Enhancing Data Analysis in Distributed Acoustic Sensing through Implementation of a Channel Quality Index
Authors: Rodríguez Tatiana , Cubas Armas Melania , Latorre Hugo , Ventosa Sergi , Ugalde Arantza
Published: May 2024

Managing large datasets in distributed acoustic sensing (DAS) presents significant challenges due to their terabyte-scale or larger size. Effectively addressing these challenges necessitates proactive measures to mitigate the impact of bad data before processing. Moreover, the dynamic nature of data quality in recorded channels requires continuous monitoring for efficient data cleaning.This study proposes a novel approach building upon prior research to automatically detect and eliminate clusters of flawed channels. Leveraging a metric that identifies channels exhibiting dissimilarity from their neighboring data points, we then employ machine-learning-based anomaly detection techniques to establish a threshold for data exclusion. Our method incorporates user input to accommodate the variability of threshold selection across different use cases, aiming to enhance the likelihood of excluding data considered inadequate for subsequent processing.This approach is applied to two distinct sets of DAS data collected from the Canary Islands. The first dataset spans two months in 2020, while the second dataset covers a period of six months between 2022 and 2023. While both datasets share substantial location overlap, one main difference is an updated interrogator for the second experiment. We demonstrate the capacity of our method to identify the evolution of channel quality over the acquisition of both datasets, thereby illustrating its efficacy in adapting to dynamic environmental and equipment-related factors.
Seismic events detection through the REFIMEVE optical fiber network
Authors: Menina Sabrina , Mazouth-Laurol Maxime , Pointard Benjamin , Le Targat Rodolphe , Cantin Etienne , Lopez Olivier , Amy-Klein Anne , Chardonnet Christian , Pottie Paul-Eric
Published: May 2024

In the past few years, many new developments have demonstrated the possibility of using long-distance optical fiber links as a vast distributed network of sensors for environmental detection, and more specifically for earthquake detection [e.g, 1-2]. In fact, the mechanical and physical properties of the optical fiber and the light waves propagating inside it are sensitives to the mechanical stresses and external disturbances, respectively, such as the seismic waves [e.g; 3]. In France and through the ultra-stable frequency signal developed in the SYRTE and the spiderweb configuration of the French national metrological network REFIMEVE (REseau FIbré MEtrologique à Vocation Européenne), several seismic events were detected on the optical fibers since 2015.
 
We would like to propose a statistical analysis of the last three years' records, focusing on seismic events of magnitude > 6 around the globe. In this work, we narrowed our study on 3 long-distance links (between 200 – 600 km), where we explored the similarities and differences of the seismic records properties among the 3 links. Our investigation showed that we do not detect systematically all the selected seismic events on the REFIMEVE network.  However, we observed that the higher number of seismic event detection was made on the longer optical fiber link (Paris-Lyon; 600 km length). To highlight the difference between the observed and not observed seismic events on REFIMEVE network, we first explored the noise level effect. The results showed that the noise is quasi-stable and that the variability of the noise level is so insignificant that it is insufficient to explain the difference between observed and unobserved events. Then, we explored the different seismic source parameters (such as the epicentral distance, the depth, the focal mechanisms, the magnitude). At this time, our results do not show clear pattern between the source parameters that could explain the difference between the observed and not observed seismic events. However, we would like to present the first catalogs of seismic events that we have been able to build on our observations of the various links. 
 
 
 
[1] D. C. Bowden et al., Geophysical Research Letters (2022) doi: 10.1029/2022GL098727.
[2] E. Ip et al., in Optical Fiber Communication Conference (OFC) 2022  (2022) https://ieeexplore.ieee.org/document/9748358
[3] A. Trabattoni et al., Geophysical Journal International (2023),  https://doi.org/10.1093/gji/ggad365
Analysis of seismograms associated with a debris flow at Sakurajima volcano, Japan, observed with the DAS system
Authors: Taguchi Kimiko , Nishimura Takeshi , Emoto Kentaro , Hamanaka Satoru , Nakamichi Haruhisa , Nakahara Hisashi , Hirose Takashi
Published: May 2024

Debris flows occur frequently in volcanic regions and cause serious damage to nearby residents and infrastructure. Hence, it is essential to detect debris flows quickly and understand their mechanisms for mitigating the hazard. At Sakurajima volcano, Japan, which has one of the highest incidences of debris flows in Japan due to frequent rainfall and explosive eruptions, we conducted an observation along the Nojiri river, located in the southwestern part of Sakurajima, during November 11 and December 9 in 2022 utilizing an existing fiber-optic cable with a length of about 4.4 km and a sampling frequency of 200 Hz. During the observation period, we succeeded in recording seismic signals generated by the debris flow on November 29.
The duration and predominant frequency of the seismograms are similar to those associated with debris flows at other volcanoes, and are distinguished from those associated with pyroclastic flows and floods. Because the seismograms show unclear onsets and continuous oscillations for more than about 15 minutes, we apply two methods to track the debris flow. One method is to determine the propagation direction of the seismic wave from the arrival time difference determined by the waveform correlations. Another method uses the spatial distribution of the seismic wave amplitudes recorded at individual DAS channels. Assuming isotropic radiation for high-frequency components of seismograms and a constant wave velocity, we evaluate the strength of seismic waves generated along the river. The results using both methods track the debris flow migrating downstream with increasing time. The obtained passage time of the debris flow at each dam along the river roughly coincides with the time when the debris flow passage was recorded by the video camera. The debris flow velocity ranged 1.1-4.6 m/s with the average of 4.2 m/s. These results show that DAS observation is quite useful for quantitatively evaluating the spatio-time distribution of debris flows along the river and for understanding the mechanism of debris flow. Also, we can conduct debris flow monitoring continuously at volcanoes without being affected by the weather or the debris flow itself because the fiber-optic cable is buried underground.
Evidence of wind turbines as a metamaterial-like urban layer: Monitoring of the seismic wavefield by Distributed Acoustic Sensing
Authors: Pilz Marco , Philippe Roux , Mohammed Shoaib Ayjaz , Lin Chen-Ray , Cotton Fabrice
Published: May 2024

The deflection and the control of the effects of the complex urban seismic wavefield on the built environment is a major challenge in earthquake engineering. The interactions between the soil and the structures and between the structures themselves strongly modify the lateral variability of ground motion seen in connection to earthquake damage, meaning that the urban environment must be considered not only as a passive receiver, but as an active source of seismic energy. In a large-scale experiment, we have investigated the idea that flexural and compressional resonances of a large number of neighbouring wind turbines strongly influence the propagation of the seismic wavefield. We can demonstrate that surface waves are strongly damped in several distinct frequency bands when interacting at the resonances of a set of wind turbines. The ground-anchored arrangement of these turbines produces unusual amplitude and phase patterns in the observed seismic wavefield. By using Distributed Acoustic Sensing it is possible to map the spatially varying ground motion and to confirm that the mechanical resonances are responsible for the strong coupling between the wind turbines and the seismic wavefield observed in certain frequency ranges of engineering interest.
Inter-channel lossless data compression for Distributed Acoustic Sensing
Authors: Seguí Aleix , Ugalde Arantza , Ventosa Sergi
Published: May 2024

Extensive monitoring initiatives driven by the urgency to address climate change have led to the rise of long-term projects, particularly in offshore environments. These projects are evolving into complex, multi-decadal operations, necessitating comprehensive monitoring. Distributed Acoustic Sensing (DAS) arrays offer unique advantages in long-distance, high-density, real-time monitoring. However, the long-term archiving of DAS data presents significant challenges, due to the need for vast storage capacities (on the order of hundreds of terabytes per year). Innovative data compression techniques are essential to make continuous high-sample-rate DAS data storage feasible.
DAS data is composed of multiple channels carrying highly correlated and coherent signals. These characteristics allow us to exploit inter-channel compression techniques, which leverage the signal from consecutive channels for prediction-based compression. Inter-channel compression methods achieve a much higher compression ratio compared to compressing each channel separately and have been little studied. In this work, we present novel inter-channel compression algorithms and demonstrate state-of-the-art lossless compression. For this purpose, a lossless coding scheme was implemented inspired by successful video coding techniques, following a pipeline composed of intra-prediction, inter-prediction, transform, and entropy coding. The implementation is divided into an encoder and a decoder. The encoder uses a bitrate optimization search and can be tuned for either speed or high-compression modes, while the decoder is optimized for quick signal reconstruction. The designed algorithms and the provided implementation facilitate the deployment of long-term DAS recording and archiving.
DeepDAS: An Earthquake Phase Identification Tool Using Submarine Distributed Acoustic Sensing Data
Authors: Xiao Han , Tilmann Frederik
Published: May 2024

The EU-INFRATECH funded SUBMERSE project will establish continuous monitoring of several oceanic telecom cables for landing sites in Portugal, Greece, and Svalbard. We develop tools for the automated analysis of these upcoming data sets as well as other submarine DAS data. We try to leverage DeepLab v3, a Deep Neural Network (DNN) architecture for semantic segmentation, to train a machine learning model for earthquake detection and P and S wave picking using submarine Distributed Acoustic Sensing (DAS) data. The input data being two-dimensional necessitated the adoption of the DeepLab v3 model, known for its superior performance in image segmentation. The complexity of submarine DAS data, characterized by diverse ocean noise environment and levels, as well as varying parameters such as cable length, shape, channel spacing, deployment environment, and location, led us to employ a larger model for effective earthquake detection.
 
Given the scarcity of submarine DAS seismic records, we adopted a strategy to pre-train our model using terrestrial DAS seismic records before fine-tuning it with submarine DAS records including Madeira Island, Svalbard Island, Chile and Greece coast. This approach aimed to leverage the abundant and diverse seismic event data available from land-based DAS system to establish a robust base model. Subsequently, the model was fine-tuned using the scarcer, yet critically important, submarine DAS data to adapt its earthquake detection capabilities to the unique characteristics and challenges presented by the submarine environment. This two-step training process allowed us to efficiently exploit the available data resources, ensuring that our model benefited from a broad learning base while achieving specialized performance for submarine earthquake detection.
 
Our results demonstrate the model's robust ability to identify seismic events and label P and S waves accurately. For three-component seismometer data it is generally assumed, that distinction of P and S waves relies primarily on the polarization of the arrivals.  Our model's capacity to recognize P and S waves in single-component DAS data is therefore intriguing. We conducted tests under various scenarios to understand how the model discriminates between P and S waves: inverting the sequence of P and S waves did not affect identification performance, suggesting that order does not play a role. Even when the input consisted solely of P or S waves, the model could still identify them, indicating the identification is not based on their simultaneous or nonsimultaneous appearance. Amplifying the P wave's amplitude by five or ten times—surpassing the S wave's amplitude—still allowed for discrimination of P and S waves, albeit with diminished accuracy, highlighting that amplitude information is significant. However, our model also learned additional aspects we have yet to understand, suggesting it captures more complex patterns 
Assessing Submarine Earthquake Detectability with Fiber-Optic Cables in the Canary Islands 
Authors: Cubas Armas Melania , Rodríguez Tatiana , Latorre Hugo , Ventosa Sergi , Villaseñor Antonio , Ugalde Arantza
Published: May 2024

Nowadays, fiber-optic telecommunication cables are serving a multitude of purposes beyond their conventional role. One such application is earthquake detection, which is particularly advantageous in submarine environments, where data acquisition is inherently more challenging and costly. Leveraging Distributed Acoustic Sensing (DAS) technology, these cables undergo a remarkable metamorphosis, transforming into a network of seismic sensors spaced just meters apart, and spanning remote and inaccessible environments with ease.Nevertheless, the quality of DAS data relies on varios factors that surpass the interrogator’s performance, such as the seafloor topography and cable characteristics and coupling. Equally critical is the development of robust software capable of discerning earthquake waves amidst a cacophony of noise and a broad spectrum of signals in the submarine environment.With this aim in mind, this study utilizes DAS data from a telecommunications fiber-optic cable linking the islands of Tenerife and Gran Canaria within the Canary Islands region. Our dataset spans approximately 2 months in 2020 and encompasses readings from both cable ends, each equipped with an interrogator, providing coverage of approximately 60 kilometers on each side. Situated between these islands lies a submarine volcano, which exhibits seismic activity nearly every day. Additionally, the recent installation of new land stations has enabled to observe an increase in seismicity to the east of Gran Canaria. Hence, this dark-fiber could enhance our ability to monitor the volcano and to accurately locate the source of this newfound seismic activity.Leveraging the pre-trained PhaseNet-DAS model, we detect P and S waves of seismic events and compare our findings with those published by the National Geographic Institute (IGN) earthquake bulletin. Through comparative analysis of both cable ends, we ascertain their earthquake detection capabilities, delineating sensitivity levels and identifying cable segments with optimal event detection and minimal noise interference. 
Exploring the Limitations and Solutions for Large Earthquake Observations with DAS
Authors: Lin Chen-Ray , von Specht Sebastian , Ma Kuo-Fong , Cotton Fabrice
Published: May 2024

Distributed Acoustic Sensing (DAS) has become a widely used tool for measuring the strain of seismic wavefields with high spatial and temporal resolution along a long-distance fiber-optic cable. However, there is still a lack of knowledge in using DAS data for large earthquake observations, such as strain-velocity conversion and instrumental recording limitations. A common issue in large earthquake observations is the saturation of seismic waveforms, which exceed the dynamic range of instruments. This saturation effect causes signal clipping and difficulties in determining earthquake magnitude for earthquake early warning, performing advanced spectral analysis, and assessing ground-motion variability and associated uncertainties. In this study, we deployed two collocated DAS interrogators connected to fiber-optic cable with different cable installation styles and a broadband seismometer to record ground motion from an earthquake sequence located 100 km away, with magnitudes ranging from MW 3.81 to 7.06. We demonstrate that signal clipping in DAS is influenced not only by earthquake magnitude but also by interrogator type and cable coupling. We observe that signal clipping in DAS records increases amplitudes at all frequencies in the signal spectra, resulting in white noise-like effects. We develop a frequency-based approach using multitaper spectral analysis and time-varying coherence estimation between interrogators to identify signal clipping instances within the DAS dataset and ensure data quality control in large earthquake observations. With our understanding of the saturation effect in records, we can devise strategies and solutions based on gauge length, sampling rate, and local phase velocity to avoid signal clipping when using DAS for large earthquake observations.
Expressions of signal saturation in Distributed Dynamic Strain Sensing (DDSS) and how can we address them: An example of seismo-acoustic sources at Mt. Etna, Italy.
Authors: Diaz-Meza Sergio , Jousset Philippe , Currenti Gilda , Wollin Christopher , Krawczyk Charlotte , Clarke Andy , Chalari Athena
Published: May 2024

Mt. Etna is an iconic volcanoe, not only for being the bigest one in Europe, but also due to its complex behavior, which produces a wide range of frequencies in the seismo-acoustic wavefield (0.05-100 Hz). This characteristic has made it a great example for volcano research and as a unique natural laboratory for testing new seismic instrumentation. During three months in 2019, we deployed a multi-instrument network comprising infrasound sensors and broad-band seismometers (BB). In addition, to understand the capabilities of fibre optic seinsing methods in such a complex environment, we deployed two types of fibre optic cables at 30 cm beneath non-consolidated scoria. Both fibres were simultaneously used for meassurements in Distributed Dynamic Strain Sensing (DDSS), also known as Distributed Acoustic Sensing (DAS). The first fibre was a 1.5 km standard telecom fibre, interrogated by a iDAS unit. The second fibre was a 0.5 km enginnered fibre. The standard and engineered fibres were interrogated simultaneously using an iDAS and a Carina unit, respectively. We recorded numerous seismo-acoustic events, which some of them are shown as saturated signals in the DDSS records. In this work we present methods to detect and indentify signal saturation in DDSS data. In addition, we demonstrate how the true strain-rate signal can be recovered from saturated records, and in the process, overcome the limitations of the dynamic range set by the initial adquisition parameneters during DDSS recordings. We also propose strategies to avoid saturation in future DDSS campaings based on the implementation of proper acquisition parameters.