scholarly journals Optical Monitoring of Microplastics Filtrated from Wastewater Sludge and Suspended in Ethanol

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 871
Author(s):  
Benjamin O. Asamoah ◽  
Pauliina Salmi ◽  
Jukka Räty ◽  
Kalle Ryymin ◽  
Julia Talvitie ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Optical Method ◽  
Specular Reflection ◽  
Speckle Pattern ◽  
Wastewater Sludge ◽  
Natural Environments ◽  
Optical Monitoring ◽  
Detection And Identification ◽  
Essential Parameter ◽  
Good Agreement

The abundance of microplastics (MPs) in the atmosphere, on land, and especially in water bodies is well acknowledged. In this study, we establish an optical method based on three different techniques, namely, specular reflection to probe the medium, transmission spectroscopy measurements for the detection and identification, and a speckle pattern for monitoring the sedimentation of MPs filtrated from wastewater sludge and suspended in ethanol. We used first Raman measurements to estimate the presence and types of different MPs in wastewater sludge samples. We also used microscopy to identify the shapes of the main MPs. This allowed us to create a teaching set of samples to be characterized with our optical method. With the developed method, we clearly show that MPs from common plastics, such as polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), and polyethylene (PE), are present in wastewater sludge and can be identified. Additionally, the results also indicate that the density of the plastics, which influences the sedimentation, is an essential parameter to consider in optical detection of microplastics in complex natural environments. All of the methods are in good agreement, thus validating the optics-based solution.

scholarly journals A Pragmatic Slope-Adjusted Curve Number Model to Reduce Uncertainty in Predicting Flood Runoff from Steep Watersheds

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1469 ◽  
Author(s):  
Muhammad Ajmal ◽  
Muhammad Waseem ◽  
Dongwook Kim ◽  
Tae-Woong Kim
Keyword(s):  
Goodness Of Fit ◽  
Curve Number ◽  
Natural Environments ◽  
Factor Effect ◽  
Average Slope ◽  
Slope Factor ◽  
Value Estimation ◽  
Watershed Slope ◽  
Runoff Events ◽  
Good Agreement

The applicability of the curve number (CN) model to estimate runoff has been a conundrum for years, among other reasons, because it presumes an uncertain fixed initial abstraction coefficient (λ = 0.2), and because choosing the most suitable watershed CN values is still debated across the globe. Furthermore, the model is widely applied beyond its originally intended purpose. Accordingly, there is a need for more case-specific adjustments of the CN values, especially in steep-slope watersheds with diverse natural environments. This study scrutinized the λ and watershed slope factor effect in estimating runoff. Our proposed slope-adjusted CN (CNIIα) model used data from 1779 rainstorm–runoff events from 39 watersheds on the Korean Peninsula (1402 for calibration and 377 for validation), with an average slope varying between 7.50% and 53.53%. To capture the agreement between the observed and estimated runoff, the original CN model and its seven variants were evaluated using the root mean square error (RMSE), Nash–Sutcliffe efficiency (NSE), percent bias (PB), and 1:1 plot. The overall lower RMSE, higher NSE, better PB values, and encouraging 1:1 plot demonstrated good agreement between the observed and estimated runoff by one of the proposed variants of the CN model. This plausible goodness-of-fit was possibly due to setting λ = 0.01 instead of 0.2 or 0.05 and practically sound slope-adjusted CN values to our proposed modifications. For more realistic results, the effects of rainfall and other runoff-producing factors must be incorporated in CN value estimation to accurately reflect the watershed conditions.

scholarly journals Broadband optical spin dependent reflection in self-assembled GaAs-based nanowires asymmetrically hybridized with Au

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Emilija Petronijevic ◽  
Alessandro Belardini ◽  
Grigore Leahu ◽  
Teemu Hakkarainen ◽  
Marcelo Rizzo Piton ◽  
...  
Keyword(s):  
Specular Reflection ◽  
Scattered Light ◽  
Semiconductor Nanostructures ◽  
Free Standing ◽  
Si Substrates ◽  
Polarization Control ◽  
Theoretical Predictions ◽  
Self Assembled ◽  
Insight Into ◽  
Good Agreement

AbstractHybridization of semiconductor nanostructures with asymmetric metallic layers offers new paths to circular polarization control and chiral properties. Here we study, both experimentally and numerically, chiral properties of GaAs-based nanowires (NWs) which have two out of six sidewalls covered by Au. Sparse ensembles of vertical, free-standing NWs were fabricated by means of lithography-free self-assembled technique on Si substrates and subsequently covered by Au using tilted evaporation. We report on optical spin-dependent specular reflection in the 680–1000 nm spectral range when the orientation of the golden layers follows the rule of extrinsic chirality. The analysis shows reflection peaks of the chiral medium whose intensity is dependent on the light handedness. We further propose a novel, time-efficient numerical method that enables a better insight into the far-field intensity and distribution of the scattered light from a sparse NW ensembles. The measurements done on three different samples in various orientations show good agreement with theoretical predictions over a broad wavelength range.

scholarly journals Simple Optical Measurements of Pre-treated Surface Roughness for Thermal Spray

2020 ◽  
pp. 1-10
Author(s):  
Yukihiko Yamagata ◽  
Ryo Iwasaka ◽  
Keita Shigyo ◽  
Juntaro Tanaka ◽  
Yasuyuki Kawaguchi ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Thermal Spray ◽  
Optical Method ◽  
Light Emitting Diode ◽  
Optical Measurements ◽  
Light Emitting ◽  
Satisfactory Performance ◽  
Roughened Surface ◽  
Spray Technique ◽  
Good Agreement

For achieving satisfactory performance of coating layers obtained using the thermal spray technique, pre-treatments are carried out by roughening the smooth surfaces of metals to more than a few tens of μm.  Although a surface roughness tester is reliable for quantitatively measuring the surface roughness, it requires expertise and a long measuring time.  In the present article, a simple optical method is presented which the authors hope will replace the above surface roughness tester. The proposed method relies on first projecting a narrow beam of light from a light-emitting diode obliquely over the roughened surface, and then on measuring the distortion of the light as observed perpendicular to the surface.  Proof-of-principle experiments were performed first against a surface roughness comparator, and then against actual blasted surfaces using both the optical method and the surface roughness tester, yielding the two methods to be in good agreement.

Experimental and Numerical Analysis of Thermal Deformation in Thermoelectric Coolers

2011 ◽  
Vol 70 ◽  
pp. 399-404
Author(s):  
Wei Chung Wang ◽  
Ting Ying Wu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Analysis ◽  
Thermal Deformation ◽  
Speckle Pattern ◽  
Electronic Speckle Pattern Interferometry ◽  
Thermoelectric Cooler ◽  
The Finite Element Method ◽  
Thermoelectric Coolers ◽  
Good Agreement

In this paper, the electronic speckle pattern interferometry (ESPI) and the finite element method (FEM) were used to obtain the thermal deformation induced in a centrally supported thermoelectric cooler (TEC). The results of ESPI and FEM are in good agreement and show that the warpage varies linearly with respect to the temperature difference between the two ceramic plates inside the TEC.

scholarly journals Evaluation of SMAP Freeze/Thaw Retrieval Accuracy at Core Validation Sites in the Contiguous United States

2018 ◽  
Vol 10 (9) ◽  
pp. 1483 ◽  
Author(s):  
Simon Kraatz ◽  
Jennifer Jacobs ◽  
Ronny Schröder ◽  
Eunsang Cho ◽  
Michael Cosh ◽  
...  
Keyword(s):  
United States ◽  
Sampling Error ◽  
Temporal Trends ◽  
Natural Environments ◽  
Aggregation Method ◽  
Freeze Thaw ◽  
Earth Observing System ◽  
Soil Temperatures ◽  
Spatial And Temporal Trends ◽  
Good Agreement

Seasonal freeze-thaw (FT) impacts much of the northern hemisphere and is an important control on its water, energy, and carbon cycle. Although FT in natural environments extends south of 45°N, FT studies using the L-band have so far been restricted to boreal or greater latitudes. This study addresses this gap by applying a seasonal threshold algorithm to Soil Moisture Active Passive (SMAP) data (L3_SM_P) to obtain a FT product south of 45°N (‘SMAP FT’), which is then evaluated at SMAP core validation sites (CVS) located in the contiguous United States (CONUS). SMAP landscape FT retrievals are usually in good agreement with 0–5 cm soil temperature at SMAP grids containing CVS stations (>70%). The accuracy could be further improved by taking into account specific overpass time (PM), the grid-specific seasonal scaling factor, the data aggregation method, and the sampling error. Annual SMAP FT extent maps compared to modeled soil temperatures derived from the Goddard Earth Observing System Model Version 5 (GEOS-5) show that seasonal FT in CONUS extends to latitudes of about 35–40°N, and that FT varies substantially in space and by year. In general, spatial and temporal trends between SMAP and modeled FT were similar.

scholarly journals Analysis of the Optical Properties of Screen-Printed and Aerosol-Printed and Plated Fingers of Silicon Solar Cells

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
R. Woehl ◽  
M. Hörteis ◽  
S. W. Glunz
Keyword(s):  
Solar Cells ◽  
Total Internal Reflection ◽  
Silicon Solar Cells ◽  
Effective Width ◽  
Contact Width ◽  
Aerosol Printing ◽  
Printing Technique ◽  
Essential Parameter ◽  
Good Agreement ◽  
Screen Printed

One main efficiency loss in industrial solar cells is the shading of the cell caused by the metal front side contacts. With the aerosol-printing technique plus an additional light-induced plating (LIP) step, not only is the geometrical contact width narrowed compared to screen-printed contacts but also the shape of the finger changes. In this work, the effective shading of different finger types is analysed with two different measurement methods. The essential parameter for characterising the finger is the effective width which can be reduced drastically compared to the geometrical width due to total internal reflection at the glass-air layer and the reflection from the roundish edges of the contact fingers into the cell. This parameter was determined with different methods. It could be shown that for aerosol-printed fingers the effective (optical) width is only 38% of its geometrical width, while for standard screen-printed fingers it is 47%. The measured values are compared to a theoretical model for an aerosol-printed and plated finger and are in good agreement.

Optical monitoring of electrogenerated species via specular reflection at glancing incidence

1979 ◽  
Vol 51 (6) ◽  
pp. 749-752 ◽  
Author(s):  
Richard L. McCreery ◽  
Richard. Pruiksma ◽  
Robert. Fagan
Keyword(s):  
Specular Reflection ◽  
Optical Monitoring

scholarly journals A MIXED BOOLEAN AND DEPOSIT MODEL FOR THE MODELING OF METAL PIGMENTS IN PAINT LAYERS

2015 ◽  
Vol 34 (2) ◽  
pp. 125 ◽  
Author(s):  
Enguerrand Couka ◽  
François Willot ◽  
Dominique Jeulin
Keyword(s):  
Correlation Functions ◽  
Poisson Point Process ◽  
Volume Fraction ◽  
Specular Reflection ◽  
Paint Layer ◽  
Metal Particles ◽  
Sem Images ◽  
Deposit Model ◽  
Stack Model ◽  
Good Agreement

Pigments made of metal particles of around 10 µm or 20 µm produce sparkling effects in paints, due to the specular reflection that occurs at this scale. Overall, the optical aspect of paints depend on the density and distribution in space of the particles. In this work, we model the dispersion of metal particles of size up to 50 µm, visible to the eyes, in a paint layer. Making use of optical and scanning electron microscopy (SEM) images, we estimate the dispersion of particles in terms of correlation functions. Particles tend to aggregate into clusters, as shown by the presence of oscillations in the correlation functions. Furthermore, the volume fraction of particles is non-uniform in space. It is highest in the middle of the layer and lowest near the surfaces of the layer. To model this microstructure, we explore two models. The first one is a deposit model where particles fall onto a surface. It is unable to reproduce the observed measurements. We then introduce a "stack" model where clusters are first modeled by a 2D Poisson point process, and a bi-directional deposit model is used to implant particles in each cluster. Good agreement is found with respect to SEM images in terms of correlation functions and density of particles along the layer height.

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