scholarly journals Design and implementation of an illumination system to mimic skyglow at ecosystem level in a large-scale lake enclosure facility

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andreas Jechow ◽  
Günther Schreck ◽  
Christopher C. M. Kyba ◽  
Stella A. Berger ◽  
Lukas Thuile Bistarelli ◽  
...  
Keyword(s):  
Large Scale ◽  
Light Pollution ◽  
Homogeneous Surface ◽  
Light Emitting ◽  
Illumination System ◽  
In Situ Conditions ◽  
Ecosystem Level ◽  
White Light Emitting Diodes ◽  
The Impact

AbstractLight pollution is an environmental stressor of global extent that is growing exponentially in area and intensity. Artificial skyglow, a form of light pollution with large range, is hypothesized to have environmental impact at ecosystem level. However, testing the impact of skyglow at large scales and in a controlled fashion under in situ conditions has remained elusive so far. Here we present the first experimental setup to mimic skyglow at ecosystem level outdoors in an aquatic environment. Spatially diffuse and homogeneous surface illumination that is adjustable between 0.01 and 10 lx, resembling rural to urban skyglow levels, was achieved with white light-emitting diodes at a large-scale lake enclosure facility. The illumination system was enabled by optical modeling with Monte-Carlo raytracing and validated by measurements. Our method can be adapted to other outdoor and indoor skyglow experiments, urgently needed to understand the impact of skyglow on ecosystems.

Mimicking skyglow at ecosystem level in a large-scale lake enclosure facility

2021 ◽  
Author(s):  
Andreas Jechow ◽  
Günther Schreck ◽  
Christopher C. M. Kyba ◽  
Stella A. Berger ◽  
Lukas Thuile Bistarelli ◽  
...  
Keyword(s):  
Large Scale ◽  
Light Pollution ◽  
Homogeneous Surface ◽  
Light Emitting ◽  
Illumination System ◽  
In Situ Conditions ◽  
Ecosystem Level ◽  
White Light Emitting Diodes ◽  
The Impact

Abstract Light pollution is an environmental stressor of global extent that is growing exponentially in area and intensity. Artificial skyglow, a form of light pollution with large range, is hypothesized to have environmental impact at ecosystem level. However, testing the impact of skyglow at large scales and in a controlled fashion under in situ conditions has remained elusive so far. Here we present the first experimental setup to mimic skyglow at ecosystem level outdoors in an aquatic environment. Spatially diffuse and homogeneous surface illumination that is adjustable between 10 mlx and 10 lx, resembling rural to urban skyglow levels, was achieved with white light-emitting diodes at a large-scale lake enclosure facility. The illumination system was enabled by optical modeling with Monte-Carlo raytracing and validated by measurements. Our method can be adapted to other outdoor and indoor skyglow experiments, urgently needed to understand the impact of skyglow on ecosystems.

scholarly journals Imposed dynamic irradiation to intensify photocatalytic reactions

2021 ◽  
Author(s):  
Fabian Guba ◽  
Florian Gaulhofer ◽  
Dirk Ziegenbalg
Keyword(s):  
Large Scale ◽  
Reaction Rate ◽  
Photochemical Reactions ◽  
Test Reaction ◽  
Light Emitting ◽  
Photochemical Processes ◽  
Spatially Distributed ◽  
Photocatalytic Reactions ◽  
The Impact ◽  
Photonic Efficiency

AbstractDynamic irradiation is a potent option to influence the interaction between photochemical reactions and mass transport to design high performant and efficient photochemical processes. To systematically investigate the impact of this parameter, the photocatalytic reduction of nitrobenzene was conducted as a test reaction. Dynamic irradiation was realized through provoked secondary flow patterns, multiple spatially distributed light emitting diodes (LEDs) and electrical pulsation of LEDs. A combined experimental and theoretical approach revealed significant potential to enhance photochemical processes. The reaction rate was accelerated by more than 70% and even more important the photonic efficiency was increased by more than a factor of 4. This renders imposed dynamic irradiation an innovative and powerful tool to intensify photoreactions on the avenue to large scale sustainable photochemical processes.

Study on Deformation and Damage of Rock Mass Subject to High In Situ Stress by Using a Elastoplastic Damage Model and Considering the Impact of Weak Planes

2013 ◽  
Vol 838-841 ◽  
pp. 705-709
Author(s):  
Yun Hao Yang ◽  
Ren Kun Wang
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Damage Model ◽  
Back Analysis ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
High In Situ Stress ◽  
Underground Caverns ◽  
The Impact

Large scale underground caverns are under construction in high in-situ stress field at Houziyan hydropower station. To investigate deformation and damage of surrounding rock mass, a elastoplastic orthotropic damage model capable of describing induced orthotropic damage and post-peak behavior of hard rock is used, together with a effective approach accounting for the presence of weak planes. Then a displacement based back analysis was conducted by using the measured deformation data from extensometers. The computed displacements are in good agreement with the measured ones at most of measurement points, which confirm the validities of constitutive model and numerical simulation model. The result of simulation shows that damage of surrounding rock mass is mainly dominated by the high in-situ stress rather than the weak planes and heavy damage occur at the cavern shoulders and side walls.

scholarly journals Does changing to brighter road lighting improve road safety? Multilevel longitudinal analysis of road traffic collision frequency during the relighting of a UK city

2020 ◽  
Vol 74 (5) ◽  
pp. 467-472 ◽  
Author(s):  
Paul Marchant ◽  
James David Hale ◽  
Jon Paul Sadler
Keyword(s):  
Road Safety ◽  
Large Scale ◽  
Road Traffic ◽  
Multilevel Modelling ◽  
Personal Injury ◽  
Light Emitting ◽  
Road Lighting ◽  
Road Traffic Collision ◽  
White Light Emitting Diodes ◽  
The City

BackgroundA step change in the night environment is taking place, with the large-scale installation of bright, broad-spectrum road lighting such as white light-emitting diodes (LEDs). One justification for this is a reduction in road traffic collisions (RTCs). This study aimed to estimate the effect of new lighting on personal injury RTCs within a large UK city.MethodsWe analysed a 9-year time series of weekly RTC personal injury counts in 132 areas of the city using multilevel modelling. The RTC rate over a full 24-hour period was the primary outcome; darkness and daylight RTC rates were secondary. The background change in RTC rate was separated from the change associated with the number of newly installed bright lamps by including a polynomial underlying time trend for the logarithm of the mean number of collisions per week for each area. The study was based on a rigorous, predesigned and archived protocol.ResultsWithin-area coefficients for the broad lighting effect were positive; as the number of bright lamps in an area increased, so did the RTC rate. The estimate for the increase in the within-area 24-hour RTC rate is 11% (95% CI 2% to 20%). The estimate of darkness-only RTCs is 16% (95% CI 2% to 32%). If the effect of lighting on darkness RTC rate is adjusted by that for daylight, one obtains 4% (95% CI −12% to +23%).ConclusionNo evidence was found for bright lamps leading to an improvement in road safety in any of the analyses. For this city, introducing brighter road lighting may have compromised safety rather than reducing harm.

scholarly journals What Is the Impact of Additional Tropical Observations on a Modern Data Assimilation System?

2019 ◽  
Vol 147 (7) ◽  
pp. 2433-2449
Author(s):  
Laura C. Slivinski ◽  
Gilbert P. Compo ◽  
Jeffrey S. Whitaker ◽  
Prashant D. Sardeshmukh ◽  
Jih-Wang A. Wang ◽  
...  
Keyword(s):  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Mean Square ◽  
Observational Network ◽  
In Situ Observations ◽  
The Mean ◽  
The Impact ◽  
Assimilation System

Abstract Given the network of satellite and aircraft observations around the globe, do additional in situ observations impact analyses within a global forecast system? Despite the dense observational network at many levels in the tropical troposphere, assimilating additional sounding observations taken in the eastern tropical Pacific Ocean during the 2016 El Niño Rapid Response (ENRR) locally improves wind, temperature, and humidity 6-h forecasts using a modern assimilation system. Fields from a 50-km reanalysis that assimilates all available observations, including those taken during the ENRR, are compared with those from an otherwise-identical reanalysis that denies all ENRR observations. These observations reveal a bias in the 200-hPa divergence of the assimilating model during a strong El Niño. While the existing observational network partially corrects this bias, the ENRR observations provide a stronger mean correction in the analysis. Significant improvements in the mean-square fit of the first-guess fields to the assimilated ENRR observations demonstrate that they are valuable within the existing network. The effects of the ENRR observations are pronounced in levels of the troposphere that are sparsely observed, particularly 500–800 hPa. Assimilating ENRR observations has mixed effects on the mean-square difference with nearby non-ENRR observations. Using a similar system but with a higher-resolution forecast model yields comparable results to the lower-resolution system. These findings imply a limited improvement in large-scale forecast variability from additional in situ observations, but significant improvements in local 6-h forecasts.

scholarly journals In Situ Observation of Stress Accumulation during Sub-Merged Arc Welding

2014 ◽  
Vol 996 ◽  
pp. 417-423 ◽  
Author(s):  
Arne Kromm ◽  
Thomas Kannengiesser
Keyword(s):  
Arc Welding ◽  
Large Scale ◽  
X Ray Diffraction ◽  
X Ray ◽  
Residual Stress State ◽  
Testing Facility ◽  
Large Scale Testing ◽  
The Impact ◽  
Stress Accumulation

Results obtained from laboratory tests mostly need to be verified under fabrication conditions in order to incorporate design specifics (joint configuration and restraint), which effect the residual stress state considerably. For this purpose, multi-pass sub merged arc welding was performed in a special large-scale testing facility. The impact of varying interpass temperatures could be proven in-situ by means of a pronounced stress accumulation during welding and subsequent heat treatment accompanied by stress determination using X-ray diffraction.

Heme b distributions through the Atlantic Ocean: in situ identification of iron limited phytoplankton

2020 ◽  
Author(s):  
Evangelia Louropoulou ◽  
Martha Gledhill ◽  
Eric P. Achterberg ◽  
Thomas J. Browning ◽  
David J. Honey ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Large Scale ◽  
North Atlantic Ocean ◽  
Iron Status ◽  
Mean Value ◽  
Particulate Material ◽  
South Atlantic ◽  
Phytoplankton Communities ◽  
The Impact

<p>Heme <em>b</em> is an iron-containing cofactor in hemoproteins that participates in the fundamental processes of photosynthesis and respiration in phytoplankton. Heme <em>b</em> concentrations typically decline in waters with low iron concentrations but due to lack of field data, the distribution of heme <em>b</em> in particulate material in the ocean is poorly constrained. Within the framework of the Helmholtz Research School for Ocean System Science and Technology (HOSST) and the GEOTRACES programme, the authors compiled datasets and conducted multidisciplinary research (e.g. chemical oceanography, microbiology, biogeochemical modelling) in order to test heme <em>b</em> as an indicator of <em>in situ</em> iron-limited phytoplankton. This study was initiated in the North Atlantic Ocean and expanded to the under-sampled South Atlantic Ocean for comparison of the results considering the different phytoplankton populations. Here, we report particulate heme <em>b</em> distributions across the Atlantic Ocean (59.9°N to 34.6°S). Heme <em>b</em> concentrations in surface waters ranged from 0.10 to 33.7 pmol L<sup>-1</sup> (median=1.47 pmol L<sup>-1</sup>, n=974) and were highest in regions with a high biomass. The ratio of heme <em>b</em> to particulate organic carbon (POC) exhibited a mean value of 0.44 μmol heme<em> b</em> mol<sup>-1 </sup>POC. We identified the ratio of 0.10 µmol heme <em>b</em> mol<sup>-1</sup> POC as the cut-off between heme <em>b</em> replete and heme <em>b</em> deficient phytoplankton. By this definition, the ratio heme <em>b</em> relative to POC was consistently below 0.10 μmol mol<sup>-1</sup> in areas characterized by low Fe supply; these were the Subtropical South Atlantic gyre and the seasonally iron limited Irminger Basin. Thus, the ratio heme <em>b</em> relative to POC gave a reliable indication of iron limited phytoplankton communities in situ. Furthermore, the comparison of observed and modelled heme <em>b</em> suggested that heme <em>b</em> could account for between 0.17-9.1% of biogenic iron. This range was comparable to previous culturing observations for species with low heme <em>b</em> content and species growing in low Fe (≤0.50 nmol L<sup>-1</sup>) or nitrate culturing media. Our large scale observations of heme<em> b</em> relative to organic matter suggest the impact of changes in iron supply on phytoplankton iron status.</p>

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