scholarly journals Sand Net Device to Control the Meanders of a Coastal River: The Case of the Authie Estuary (France)

2021 ◽  
Vol 9 (12) ◽  
pp. 1325
Author(s):  
Anh T. K. Do ◽  
Nicolas Huybrechts ◽  
Philippe Sergent
Keyword(s):  
Main Channel ◽  
In Situ Monitoring ◽  
Field Surveys ◽  
Coastal Defence ◽  
Shoreline Protection ◽  
Impact Area ◽  
Coastal River ◽  
The Impact ◽  
Strong Erosion

The Authie estuary is characterized by an important southern sand spit and a northern shoreline subject to strong erosion due to the meandering of the coastal river. In order to reduce this erosion, a new soft coastal defence, namely the sand net device (SND), has been implemented inside the Authie estuary. It consists of several nets assembled in an inverted V creating a porous structure and thus trapping sand as shoreline protection. However up to now, little proof has been provided on the explicit influence of this SND on the hydrodynamic pattern and associated morphodynamics. In this paper, field surveys of morphological developments combined with numerical modelling (Telemac-2D/3D) analyze the influence of the SND into flow pattern and morphodynamics. In situ monitoring clearly points out sedimentation around the SND and a deepening of the main channel. Modelling results show that, without SND, erosion is observed around its location. With a SND implemented, the velocity has been reduced and created a deviation in its direction by a circulation around the SND location. The impact area of the structure is around 500 m in both directions, upstream and downstream part.

scholarly journals Stability Assessment of Mining Excavations: the Impact of Large Depths

2018 ◽  
Vol 40 (3) ◽  
pp. 180-187
Author(s):  
Tadeusz Majcherczyk ◽  
Zbigniew Niedbalski ◽  
Łukasz Bednarek
Keyword(s):  
Rock Mass ◽  
In Situ Monitoring ◽  
Stability Assessment ◽  
Underground Excavations ◽  
Deformation Prediction ◽  
Large Depth ◽  
Coal Deposits ◽  
The Impact

AbstractBack in the early 1980s, coal deposits occurring at depths of ~700 m below surface were already regarded as large-depth deposits. Meanwhile, today the borderline depth of large-depth mining has extended to >1,000 m. Design, excavation and maintenance of mining roadways at the depth of >1,000 m have, therefore, become crucial issues in a practical perspective in recent years. Hence, it is now extremely important to intensify research studies on the influence of large depths on the behaviour of rock mass and deformation of support in underground excavations. The paper presents the results of the study carried out in five mining excavations at depths ranging from 950 to 1,290 m, where monitoring stations with measurement equipment were built. The analysis of data from laboratory and coal mine tests, as well as in situ monitoring, helped to formulate a set of criteria for stability assessment of underground excavations situated at large depths. The proposed methodology of load and deformation prediction in support systems of the excavations unaffected by exploitation is based on the criteria referring to the depth of excavation and the quality of rock mass. The depth parameter is determined by checking whether the analysed excavation lies below the critical depth, whereas the rock mass quality is determined on the basis of the roof lithology index (WL) and the crack intensity factor (n)

Comparative Study on in-situ Ellipsometric Monitoring of III-Nitride Film Growth via Plasma-Enhanced Atomic Layer Deposition

2019 ◽  
Vol 28 (03n04) ◽  
pp. 1940020
Author(s):  
Adnan Mohammad ◽  
Deepa Shukla ◽  
Saidjafarzoda Ilhom ◽  
Brian Willis ◽  
Ali Kemal Okyay ◽  
...  
Keyword(s):  
Growth Rate ◽  
Real Time ◽  
Film Growth ◽  
Atomic Layer ◽  
Layer Growth ◽  
In Situ Monitoring ◽  
Rf Plasma ◽  
Nitride Film ◽  
The Impact

In this paper a comparative in-situ ellipsometric analysis is carried out on plasma-assisted ALD-grown III-nitride (AlN, GaN, and InN) films. The precursors used are TMA, TMG, and TMI for AlN, GaN, and InN respectively, while Ar is used as purge gas. For all of the films N2/H2/Ar plasma was used as the co-reactant. The work includes real-time in-situ monitored saturation curves, unit ALD cycle analysis, and >500 cycle film growth runs. In addition, the films are grown at different substrate temperatures to observe the impact of temperature not only on the growth rate but on how it influenced the precursor chemisorption, ligand removal, and nitrogen incorporation surface reactions. All three nitride films confirm fairly linear growth character. The growth rate per cycle (GPC) for each film is also measured with respect to rf-plasma power to obtain the surface saturation conditions during ALD growth. The real-time in-situ monitoring of the film growth can really be beneficial to understand the atomic layer growth and film formation in each individual ALD cycle.

scholarly journals CO2 Concentration and Occupants’ Symptoms in Naturally Ventilated Schools in Mediterranean Climate

Buildings ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 197 ◽  
Author(s):  
Jesica Fernández-Agüera ◽  
Miguel Ángel Campano ◽  
Samuel Domínguez-Amarillo ◽  
Ignacio Acosta ◽  
Juan José Sendra
Keyword(s):  
Mediterranean Climate ◽  
Co2 Concentration ◽  
Building Envelope ◽  
In Situ Monitoring ◽  
Building Stock ◽  
Air Infiltration ◽  
The Mean ◽  
The Impact ◽  
Different Levels

A large part of the school building stock in Andalusia lacks ventilation facilities, so that the air renewal of the classrooms is achieved through the building envelope (air infiltration) or the opening of windows. This research analyses the airtightness of the classrooms in Andalusia and the evolution of CO2 concentration during school hours through in situ monitoring. Pressurization and depressurization tests were performed in 42 classrooms and CO2 concentration was measured in two different periods, winter and midseason, to study the impact of the different levels of aperture of windows. About 917 students (11–17 years of age) were surveyed on symptoms and effects on their health. The mean n50 values are about 7 h−1, whereas the average CO2 concentration values are about 1878 ppm, with 42% of the case studies displaying concentrations above 2000 ppm with windows closed.

Towards Remote Sensing of Atmospheric Trace Gases in the UV spectral range using Dual-Comb spectroscopy

2021 ◽  
Author(s):  
Clément Pivard ◽  
Sandrine Galtier ◽  
Patrick Rairoux
Keyword(s):  
Remote Sensing ◽  
Spectral Range ◽  
Near Infrared ◽  
Frequency Comb ◽  
Trace Gases ◽  
In Situ Monitoring ◽  
Atmospheric Trace Gases ◽  
The Impact ◽  
Uv Range

<p>The development of increasingly sensitive and robust instruments and new methodologies are essential to improve our understanding of the Earth’s climate and air pollution. In this context, Dual-Comb spectroscopy (DCS) appears as an emerging spectroscopy methodology to detect in situ, without air-sampling, atmospheric trace-gases.</p><p>DCS is a Fourier-transform type experiment that takes advantage of mode-locked femtosecond (fs) pulses. This methodology appears highly relevant for atmosphere remote-sensing studies because of its very fast acquisition rate (>kHz) that reduces the impact of atmospheric turbulences on the retrieved spectra. DCS has been successfully applied in near-infrared (NIR) spectral ranges for atmospheric greenhouse gas monitoring (water vapor, carbon dioxide, and methane) [1-2].</p><p>Its implementation in the UV range would offer a new spectroscopic intrumentation to target the most reactive species of the atmosphere (OH, HONO, BrO...) as they have their greatest absorption cross-sections in the UV range. UV-DCS would therefore be an answer to the lack of variability of today operationnal and in situ monitoring instrument for those reactive molecules.</p><p>We will present a potential light source for remote sensing UV-DCS and discuss the degree of immunity of UV-DCS to atmospheric turbulences. We will show to which extent the characteristics of the currently available UV sources are compatible with the unambiguous identification of UV absorbing gases by UV-DCS. We will finally present the performances of UV-DCS in terms of concentration detection limit for several UV absorbing molecules (OH, BrO, NO<sub>2</sub>, OClO, HONO, CH<sub>2</sub>O, SO<sub>2</sub>). This sensitivity study has been recently published [3] and the main results will be presented.</p><p> </p><p>[1] Rieker, G.B.; Giorgetta, F.R.; Swann, W.C.; Kofler, J.; Zolot, A.M.; Sinclair, L.C.; Baumann, E.; Cromer, C.;Petron, G.; Sweeney, C.; et al. « Frequency-comb-based remote sensing of greenhouse gases over kilometer air Paths ». Optica 1, p. 290–298 (2014)</p><p>[2] Oudin, J.; Mohamed, A.K.; Hébert, P.J. "IPDA LIDAR measurements on atmospheric CO2 and H2O using dual comb spectroscopy," Proc. SPIE 11180, International Conference on Space Optics — ICSO 2018, p. 111802N (12 July 2019)</p><p>[3] Galtier, S.; Pivard, C.; Rairoux, P. Towards DCS in the UV Spectral Range for Remote Sensing of Atmospheric Trace Gases. Remote Sens., 12, p.3444 (2020)</p>

scholarly journals Response of atmospheric composition to COVID-19 lockdown measures during Spring in the Paris region (France)

2021 ◽  
Author(s):  
Jean-Eudes Petit ◽  
Jean-Charles Dupont ◽  
Olivier Favez ◽  
Valérie Gros ◽  
Yunjiang Zhang ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Meteorological Conditions ◽  
In Situ Monitoring ◽  
Pollutant Emissions ◽  
Atmospheric Composition ◽  
Secondary Pollutants ◽  
The Impact ◽  
Mitigation Policies

Abstract. Since early 2020, the COVID-19 pandemic has led to lockdowns at national scales. These lockdowns resulted in large cuts of atmospheric pollutant emissions, notably related to the vehicular traffic source where daily commuting of light-duty vehicles was almost completely stopped in numerous urban areas worldwide, especially during Spring 2020. As a result, air quality changed in manners that are still currently under investigation. Long-term in-situ monitoring of atmospheric composition provides, to this perspective, essential information. However, a robust quantitative assessment of the impact of lockdown measures on ambient concentrations is hindered by weather variability. Basic comparisons with previous years may thus be flawed, especially regarding secondary pollutants, whose concentrations strongly depends on meteorological conditions. In order to circumvent this difficulty, an innovative methodology has been developed. The Analog Application for Air Quality (A3Q) method is based on the comparison of each day of lockdown to a group of analog days having similar meteorological conditions. The A3Q method has been successfully evaluated and applied to a comprehensive in-situ dataset of primary and secondary pollutants obtained at the SIRTA observatory, a suburban background site of the Paris megacity (France). The overall slight decrease of PM1 concentrations (−14 %) compared to business-as-usual conditions conceals contrasting behaviours. Primary traffic tracers (NOx and traffic-related carbonaceous aerosols) dropped by 42–66 % during the lockdown period. Further, the A3Q method enabled us to characterize of changes triggered by NOx decreases. Particulate nitrate and secondary organic aerosols (SOA), two of the main springtime aerosol components in North-Western Europe, decreased by −45 % and −25 %, respectively. A NOx-relationship emphasizes the interest of NOx mitigation policies at the regional (i.e. city) scale, although long-range pollution advection sporadically overcompensated regional decreases. Variations of the oxidation state of SOA suggests discrepancies in SOA formation processes. At the same time, the expected ozone increase (+20 %) underlines the negative feedback of NO titration. These results provide a quasi-comprehensive observation-based insight on mitigation policies regarding air quality in future low-carbon urban areas.

Biofilms in Food Processing Environments: Challenges and Opportunities

2019 ◽  
Vol 10 (1) ◽  
pp. 173-195 ◽  
Author(s):  
Avelino Alvarez-Ordóñez ◽  
Laura M. Coughlan ◽  
Romain Briandet ◽  
Paul D. Cotter
Keyword(s):  
Food Processing ◽  
Biofilm Formation ◽  
In Situ Monitoring ◽  
Fermented Foods ◽  
Microbial Biofilms ◽  
Challenges And Opportunities ◽  
Intraspecies Variability ◽  
The Impact

This review examines the impact of microbial communities colonizing food processing environments in the form of biofilms on food safety and food quality. The focus is both on biofilms formed by pathogenic and spoilage microorganisms and on those formed by harmless or beneficial microbes, which are of particular relevance in the processing of fermented foods. Information is presented on intraspecies variability in biofilm formation, interspecies relationships of cooperativism or competition within biofilms, the factors influencing biofilm ecology and architecture, and how these factors may influence removal. The effect on the biofilm formation ability of particular food components and different environmental conditions that commonly prevail during food processing is discussed. Available tools for the in situ monitoring and characterization of wild microbial biofilms in food processing facilities are explored. Finally, research on novel agents or strategies for the control of biofilm formation or removal is summarized.

scholarly journals In Situ Monitoring of Additive Manufacturing Using Digital Image Correlation: A Review

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1511
Author(s):  
Filipa G. Cunha ◽  
Telmo G. Santos ◽  
José Xavier
Keyword(s):  
Additive Manufacturing ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Field Measurements ◽  
In Situ Monitoring ◽  
Image Correlation ◽  
Full Field ◽  
The Impact ◽  
Am Processes

This paper is a critical review of in situ full-field measurements provided by digital image correlation (DIC) for inspecting and enhancing additive manufacturing (AM) processes. The principle of DIC is firstly recalled and its applicability during different AM processes systematically addressed. Relevant customisations of DIC in AM processes are highlighted regarding optical system, lighting and speckled pattern procedures. A perspective is given in view of the impact of in situ monitoring regarding AM processes based on target subjects concerning defect characterisation, evaluation of residual stresses, geometric distortions, strain measurements, numerical modelling validation and material characterisation. Finally, a case study on in situ measurements with DIC for wire and arc additive manufacturing (WAAM) is presented emphasizing opportunities, challenges and solutions.

scholarly journals Detecting impacts of extreme events with ecological in situ monitoring networks

2017 ◽  
Vol 14 (18) ◽  
pp. 4255-4277 ◽  
Author(s):  
Miguel D. Mahecha ◽  
Fabian Gans ◽  
Sebastian Sippel ◽  
Jonathan F. Donges ◽  
Thomas Kaminski ◽  
...  
Keyword(s):  
Extreme Events ◽  
Event Detection ◽  
Extreme Event ◽  
Decay Rates ◽  
In Situ Monitoring ◽  
Monitoring Networks ◽  
Terrestrial Biosphere ◽  
Detection Rates ◽  
The Impact

Abstract. Extreme hydrometeorological conditions typically impact ecophysiological processes on land. Satellite-based observations of the terrestrial biosphere provide an important reference for detecting and describing the spatiotemporal development of such events. However, in-depth investigations of ecological processes during extreme events require additional in situ observations. The question is whether the density of existing ecological in situ networks is sufficient for analysing the impact of extreme events, and what are expected event detection rates of ecological in situ networks of a given size. To assess these issues, we build a baseline of extreme reductions in the fraction of absorbed photosynthetically active radiation (FAPAR), identified by a new event detection method tailored to identify extremes of regional relevance. We then investigate the event detection success rates of hypothetical networks of varying sizes. Our results show that large extremes can be reliably detected with relatively small networks, but also reveal a linear decay of detection probabilities towards smaller extreme events in log–log space. For instance, networks with  ≈  100 randomly placed sites in Europe yield a  ≥  90 % chance of detecting the eight largest (typically very large) extreme events; but only a  ≥  50 % chance of capturing the 39 largest events. These findings are consistent with probability-theoretic considerations, but the slopes of the decay rates deviate due to temporal autocorrelation and the exact implementation of the extreme event detection algorithm. Using the examples of AmeriFlux and NEON, we then investigate to what degree ecological in situ networks can capture extreme events of a given size. Consistent with our theoretical considerations, we find that today's systematically designed networks (i.e. NEON) reliably detect the largest extremes, but that the extreme event detection rates are not higher than would be achieved by randomly designed networks. Spatio-temporal expansions of ecological in situ monitoring networks should carefully consider the size distribution characteristics of extreme events if the aim is also to monitor the impacts of such events in the terrestrial biosphere.

scholarly journals Use of In Situ Burning as an Oil Spill Response Tool: Follow-Up of Four Case Studies

2003 ◽  
Vol 2003 (1) ◽  
pp. 123-128 ◽  
Author(s):  
Jacqueline Michel ◽  
Zach Nixon ◽  
Heidi Hinkeldey
Keyword(s):  
Crude Oil ◽  
Case Studies ◽  
Oil Spill ◽  
Salt Lake ◽  
Effective Means ◽  
Burn Treatment ◽  
Impact Area ◽  
Sabine Lake ◽  
The Impact

ABSTRACT Four in situ burning sites that varied widely in the physical setting, oil type, timing of the burn, and post-burn treatment were assessed 0.5–1.5 years post-burn: two condensate spills in intertidal marshes at Mosquito Bay, LA in April 2001 and near Sabine Lake, LA in February 2000; crude oil spill in a ponded wetland in Minnesota in July 2000; and a spill of diesel in a salt flat/wetland north of Great Salt Lake, UT in January 2000. When used quickly after a release, burning is most effective at reducing damage to vegetation and the areal extent of impact. Where crude oil was burned within hours after the release at the Minnesota site, the impact area was restricted to 3 acres. In contrast, the diesel in the Utah spill spread over 38 acres within 3 days. The window of opportunity for in situ burning to be an effective means of oil removal can be days to months, depending on the spill conditions. The condensate spill at Mosquito Bay site was effectively burned 6–7 days after the release was reported. For spills with snow and ice cover, burning may still be effective months later. In fact, it may be necessary to consider additional burns during thaw periods and during the final thaw. Burning will not reduce the toxic effects of the oil that occurred prior to the burn. It can, however, be very effective at reducing the extent and degree of impacts by quickly removing the remaining oil. In three of the four case studies, the area burned was significantly larger than the oiled area (up to 10 x). Healthy, green, unoiled vegetation is not always an effective fire break, particularly downwind; fires can quickly jump the kinds of fire breaks placed during spill emergencies in wetlands (e.g., vegetation laid down by the passage of airboats).

scholarly journals Detecting impacts of extreme events with ecological in-situ monitoring networks

2017 ◽  
Author(s):  
Miguel D. Mahecha ◽  
Fabian Gans ◽  
Sebastian Sippel ◽  
Jonathan F. Donges ◽  
Thomas Kaminski ◽  
...  
Keyword(s):  
Extreme Events ◽  
Event Detection ◽  
Extreme Event ◽  
Decay Rates ◽  
In Situ Monitoring ◽  
Monitoring Networks ◽  
Terrestrial Biosphere ◽  
Detection Rates ◽  
The Impact

Abstract. Extreme hydrometeorological conditions typically impact ecophysiological processes of terrestrial vegetation. Satellite based observations of the terrestrial biosphere provide an important reference for detecting and describing the spatiotemporal development of such events. However, in-depth investigations of ecological processes during extreme events require additional in-situ observations. The question is if the density of existing ecological in-situ networks is sufficient for analyzing the impact of extreme events, or what are expected event detection rates of ecological in-situ networks of a given size. To assess these issues, we build a baseline of extreme reductions in the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), identified by a new event detection method tailored to identify extremes of regional relevance. We then investigate the event detection success rates of hypothetical networks of varying sizes. Our results show that large extremes can be reliably detected with relatively small network, but also reveal a linear decay of detection probabilities towards smaller extreme events in log-log space. For instance, networks with ≈ 100 randomly placed sites in Europe yield a ≥ 90 % chance of detecting the largest 8 (typically very large) extreme events; but only a ≥ 50 % chance of capturing the largest 39 events. These finding are consistent with probability-theoretic considerations, but the slopes of the decay rates deviate due to temporal autocorrelation issues and the exact implementation of the extreme event detection algorithm. Using the examples of AmeriFlux and NEON, we then investigate to what degree ecological in-situ networks can capture extreme events of a given size. Consistent with our theoretic considerations, we find that today's systematic network designs (i.e. NEON) reliably detects the largest extremes. But the extreme event detection rates are not higher than they would be achieved by randomly designed networks. Spatiotemporal expansions of ecological in-situ monitoring networks should carefully consider the size distribution characteristics of extreme events if the aim is also to monitor their impacts in the terrestrial biosphere.

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