scholarly journals Topography changes and thermal distribution at the Kelud crater after the 2014 Plinian eruption

2020 ◽  
Vol 52 (3) ◽  
pp. 411
Author(s):  
Wahyudi Wahyudi ◽  
Ari Setiawan ◽  
Heriansyah Putra ◽  
Herlan Darmawan ◽  
Imam Suyanto ◽  
...  
Keyword(s):  
Crater Lake ◽  
Low Cost ◽  
Convection Heat Transfer ◽  
Deposition Process ◽  
Plinian Eruption ◽  
Aerial Images ◽  
Apparent Temperature ◽  
Surface Processes ◽  
Erosion And Deposition ◽  
Thermal Distribution

Topography of a volcano crater can change due to endogenic processes such as deformation or eruption, or surface processes. Erosion and deposition are surface processes that may occur and gradually change the slope of the inner volcano crater. Here, we investigated erosion and deposition processes that occurred in the Kelud crater after the 2014 plinian eruption. We used high-resolution Digital Elevation Models (DEMs) and orthomosaic images derived by drone photogrammetry that acquired between September 2018 and July 2019. We obtained hundreds of aerial images which were reconstructed to obtain 3D models of Kelud’s crater by using Structure from Motion (SfM) technique. Results show erosions at alluvial fans that dominantly located at the east valleys of Kelud crater. The erosion removed the volcanic materials up to -5 m which transported and deposited close to the vicinity of the Kelud crater. The deposition process causes the increase of the Kelud crater lake up to 3 m. Moreover, we also mapped the thermal distribution of the Kelud crater lake by using low cost thermal camera. Our thermal investigation is able to identify some hotspots at the vicinity of the Kelud crater lake with range temperature of 43.7°C – 55.3°C, while the average apparent temperature of the Kelud crater lake is ~ 29°C. This high temperature area may indicate underwater active fractures that continuously release volcanic gasses which leads to convection heat transfer through Kelud’s water lake.

Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality

2020 ◽  
Vol 90 (3) ◽  
pp. 30502
Author(s):  
Alessandro Fantoni ◽  
João Costa ◽  
Paulo Lourenço ◽  
Manuela Vieira
Keyword(s):  
Amorphous Silicon ◽  
High Throughput Screening ◽  
Simulation Analysis ◽  
Low Cost ◽  
Deposition Process ◽  
Large Area ◽  
Sidewall Roughness ◽  
Sensing Applications ◽  
Fabrication Defects ◽  
The Impact

Amorphous silicon PECVD photonic integrated devices are promising candidates for low cost sensing applications. This manuscript reports a simulation analysis about the impact on the overall efficiency caused by the lithography imperfections in the deposition process. The tolerance to the fabrication defects of a photonic sensor based on surface plasmonic resonance is analysed. The simulations are performed with FDTD and BPM algorithms. The device is a plasmonic interferometer composed by an a-Si:H waveguide covered by a thin gold layer. The sensing analysis is performed by equally splitting the input light into two arms, allowing the sensor to be calibrated by its reference arm. Two different 1 × 2 power splitter configurations are presented: a directional coupler and a multimode interference splitter. The waveguide sidewall roughness is considered as the major negative effect caused by deposition imperfections. The simulation results show that plasmonic effects can be excited in the interferometric waveguide structure, allowing a sensing device with enough sensitivity to support the functioning of a bio sensor for high throughput screening. In addition, the good tolerance to the waveguide wall roughness, points out the PECVD deposition technique as reliable method for the overall sensor system to be produced in a low-cost system. The large area deposition of photonics structures, allowed by the PECVD method, can be explored to design a multiplexed system for analysis of multiple biomarkers to further increase the tolerance to fabrication defects.

scholarly journals Development of an Additive Manufacturing System for the Deposition of Thermoplastics Impregnated with Carbon Fibers

2019 ◽  
Vol 3 (2) ◽  
pp. 35 ◽  
Author(s):  
Miguel Reis Silva ◽  
António M. Pereira ◽  
Nuno Alves ◽  
Gonçalo Mateus ◽  
Artur Mateus ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Additive Manufacturing ◽  
Carbon Fibers ◽  
Low Cost ◽  
Deposition Process ◽  
Processing Parameters ◽  
Yarn Diameter ◽  
Thermoplastic Matrix ◽  
Anisotropic Mechanical Properties ◽  
Long Carbon Fiber

This work presents an innovative system that allows the oriented deposition of continuous fibers or long fibers, pre-impregnated or not, in a thermoplastic matrix. This system is used in an integrated way with the filamentary fusion additive manufacturing technology and allows a localized and oriented reinforcement of polymer components for advanced engineering applications at a low cost. To demonstrate the capabilities of the developed system, composite components of thermoplastic matrix (polyamide) reinforced with pre-impregnated long carbon fiber (carbon + polyamide), 1 K and 3 K, were processed and their tensile and flexural strength evaluated. It was demonstrated that the tensile strength value depends on the density of carbon fibers present in the composite, and that with the passage of 2 to 4 layers of fibers, an increase in breaking strength was obtained of about 366% and 325% for the 3 K and 1 K yarns, respectively. The increase of the fiber yarn diameter leads to higher values of tensile strength of the composite. The obtained standard deviation reveals that the deposition process gives rise to components with anisotropic mechanical properties and the need to optimize the processing parameters, especially those that lead to an increase in adhesion between deposited layers.

scholarly journals Dynamics of Erosion and Deposition in a Partially Restored Valley-Bottom Gully

Land ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 62
Author(s):  
Alberto Alfonso-Torreño ◽  
Álvaro Gómez-Gutiérrez ◽  
Susanne Schnabel
Keyword(s):  
High Resolution ◽  
Sediment Deposition ◽  
Aerial Images ◽  
Valley Bottom ◽  
Erosion And Deposition ◽  
Channel Dynamics ◽  
Check Dams ◽  
Before And After ◽  
Multi Temporal ◽  
Spatio Temporal

Gullies are sources and reservoirs of sediments and perform as efficient transfers of runoff and sediments. In recent years, several techniques and technologies emerged to facilitate monitoring of gully dynamics at unprecedented spatial and temporal resolutions. Here we present a detailed study of a valley-bottom gully in a Mediterranean rangeland with a savannah-like vegetation cover that was partially restored in 2017. Restoration activities included check dams (gabion weirs and fascines) and livestock exclosure by fencing. The specific objectives of this work were: (1) to analyze the effectiveness of the restoration activities, (2) to study erosion and deposition dynamics before and after the restoration activities using high-resolution digital elevation models (DEMs), (3) to examine the role of micro-morphology on the observed topographic changes, and (4) to compare the current and recent channel dynamics with previous studies conducted in the same study area through different methods and spatio-temporal scales, quantifying medium-term changes. Topographic changes were estimated using multi-temporal, high-resolution DEMs produced using structure-from-motion (SfM) photogrammetry and aerial images acquired by a fixed-wing unmanned aerial vehicle (UAV). The performance of the restoration activities was satisfactory to control gully erosion. Check dams were effective favoring sediment deposition and reducing lateral bank erosion. Livestock exclosure promoted the stabilization of bank headcuts. The implemented restoration measures increased notably sediment deposition.

Deposition of Bead Arrays With Variable Diameter by Self-Focusing of Electrohydrodynamic Jets

2017 ◽  
Author(s):  
Nicolas Martinez-Prieto ◽  
Gabriela Fratta ◽  
Jian Cao ◽  
Kornel Ehmann
Keyword(s):  
Low Cost ◽  
Three Dimensional ◽  
Deposition Process ◽  
Direct Writing ◽  
Variable Diameter ◽  
Self Focusing ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Number Of Passes ◽  
Bead Arrays

Electrohydrodynamic processes were used for direct-writing of bead arrays with controllable bead sizes. Experiments were conducted to align layers of bead-on-string structures in an effort to create three-dimensional patterns. The results show that the jet focuses on previously deposited droplets allowing for the selective deposition of material over already deposited patterns. Jet attraction to already deposited solutions on the substrate is attributed to the charge transport at the liquid ink-metal collector interface and the dielectric properties of the water/poly(ethylene oxide) solution under an electric field. The deposition process consists of 3 steps: (1) deposition of a layer of bead-on-string structures, (2) addition of extra volume to the beads by subsequent passes of the jet, and (3) evaporation of the solvent resulting in an array of beads with varying sizes. Patterns with up to 20 passes were experimentally obtained. The beads’ height was seen to be independent of the number of passes. The process reported is a simple, fast, and low-cost method for deposition of bead arrays with varying diameters.

scholarly journals Simulation of wind-induced snow transport in alpine terrain using a fully coupled snowpack/atmosphere model

2013 ◽  
Vol 7 (3) ◽  
pp. 2191-2245 ◽  
Author(s):  
V. Vionnet ◽  
E. Martin ◽  
V. Masson ◽  
G. Guyomarc'h ◽  
F. Naaim-Bouvet ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Winter Season ◽  
Coupled Model ◽  
Deposition Process ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Blowing Snow ◽  
Erosion And Deposition ◽  
Atmospheric Flow ◽  
Snow Transport

Abstract. In alpine regions, wind-induced snow transport strongly influences the spatio-temporal evolution of the snow cover throughout the winter season. To gain understanding on the complex processes that drive the redistribution of snow, a new numerical model is developed. It couples directly the detailed snowpack model Crocus with the atmospheric model Meso-NH. Meso-NH/Crocus simulates snow transport in saltation and in turbulent suspension and includes the sublimation of suspended snow particles. A detailed representation of the first meters of the atmosphere allows a fine reproduction of the erosion and deposition process. The coupled model is evaluated against data collected around the experimental site of Col du Lac Blanc (2720 m a.s.l., French Alps). For this purpose, a blowing snow event without concurrent snowfall has been selected and simulated. Results show that the model captures the main structures of atmospheric flow in alpine terrain, the vertical profile of wind speed and the snow particles fluxes near the surface. However, the horizontal resolution of 50 m is found to be insufficient to simulate the location of areas of snow erosion and deposition observed by terrestrial laser scanning. When activated, the sublimation of suspended snow particles causes a reduction in deposition of 5.3%. Total sublimation (surface + blowing snow) is three times higher than surface sublimation in a simulation neglecting blowing snow sublimation.

Spatio-temporal dynamics of erosion and deposition in a partially restored valley-bottom gully

2021 ◽  
Author(s):  
Alberto Alfonso-Torreño ◽  
Álvaro Gómez-Gutiérrez ◽  
Susanne Schnabel
Keyword(s):  
Temporal Dynamics ◽  
Land Use Changes ◽  
Degradation Process ◽  
Gully Erosion ◽  
Aerial Images ◽  
Negative Consequences ◽  
Valley Bottom ◽  
Erosion And Deposition ◽  
Check Dams ◽  
Spatio Temporal

<p>Soil erosion by water is a frequent soil degradation process in rangelands of SW Spain. The two main erosive processes in these areas are sheetwash erosion in hillslopes and gully erosion due to concentrated flow in valley bottoms. Land use changes and overgrazing play a key role in the genesis and development of gullies and gully erosion is a frequent process with negative consequences at the valley bottoms of these landscapes.</p><p>The development of new techniques allows monitoring of gully dynamics with an increase at spatial and temporal resolutions. Here we present a detailed study of a valley-bottom gully in a Mediterranean rangeland with a savannah-like vegetation cover that was partially restored in February 2017. Restoration activities included check dams (gabion weirs and fascines) and livestock exclosure by fencing. The objectives of this study were: (1) to analyze the effectiveness of the restoration measures, (2) to study erosion and deposition dynamics before and after the restoration activities, (3) to examine the role of micro-morphology on the observed topographic changes and (4) to compare the current and recent channel dynamics with previous studies conducted in the same study area through different methods and spatio-temporal scales, quantifying medium-term changes. Topographic changes were estimated using multi-temporal high-resolution DEMs produced using Structure-from-Motion (SfM) photogrammetry and aerial images acquired by a fixed-wing Unmanned Aerial Vehicle (UAV). DEMs and orthophotographs with a Ground Sampling Distance of 0.02 m were produced by means of SfM photogrammetric techniques. The average Root Mean Square Error (RMSE) estimated during the SfM processing was 0.03 m.</p><p>The performance of the restoration activities was satisfactory to control gully erosion. Check dams were effective favoring sediment deposition and reducing lateral bank erosion. Nevertheless, erosion was observed immediately downstream in 9% of the check dams. Livestock exclosure in the most degraded area promoted the stabilization of bank headcuts and revegetation. The sediments retained behind check dams reduced the longitudinal slope gradient of the channel bed and established a positive feedback mechanism for channel revegetation.</p><p><strong>Keywords</strong>: gully erosion, restoration, topographic change, UAV+SfM, rangeland.</p>

Novel electrolyte additive of graphene oxide for prolonging the lifespan of Zinc-ion batteries

2021 ◽  
Author(s):  
Xuyang Wang ◽  
Alina Kirianova ◽  
Xieyu Xu ◽  
Yanguang Liu ◽  
Olesya Kapitanova ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Coulombic Efficiency ◽  
Low Cost ◽  
Concentration Field ◽  
Phase Field Model ◽  
Deposition Process ◽  
Zinc Ion ◽  
Ion Concentration ◽  
Environmental Friendliness ◽  
Nucleation Overpotential

Abstract Aqueous zinc-ion batteries have attracted the attention of the industry due to their low cost, good environmental friendliness, and competitive gravimetric energy density. However, zinc anodes, similar to lithium, sodium and other alkali metal anodes, are also plagued by dendrite problems. Zinc dendrites can penetrate through polymer membranes, and even glass fiber membranes which seriously hinders the development and application of aqueous zinc-ion batteries. To resolve this issue, certain additives are required. Here we have synthesized an electrochemical graphene oxide with novel electrolyte based on tryptophan, which allows to obtain few-layered sheets with a remarkably uniform morphology, good aqueous solution dispersion, easy preparation and environmental friendliness. We used this electrochemical graphene oxide as an additive to the electrolyte for aqueous zinc-ion batteries. The results of phase-field model combined with experimental characterization revealed that the addition of this material effectively promotes the uniform distribution of the electric field and the Zn-ion concentration field, reduces the nucleation overpotential of Zn metal, and provides a more uniform deposition process on the metal surface and improved cyclability of the aqueous Zn-ion battery. The resultant Zn|Zn symmetric battery with the electrochemical graphene oxide additive affords a stable Zn anode, which provided service for more than 500 hours at 0.2 mA cm-2 and even more than 250 hours at 1.0 mA cm-2. The Coulombic efficiency (98.7%) of Zn|Cu half-cells and thus cyclability of aqueous Zn-ion batteries using electrochemical graphene oxide is significantly better compared to the additive-free electrolyte system. Therefore, our approach paves a promising avenue to foster the practical application of aqueous Zn-ion batteries for energy storage.

Modeling, Testing, and Evaluation of a Building-Integrated Photovoltaic-Thermal Collector

2009 ◽  
Author(s):  
Charles D. Corbin ◽  
Michael J. Brandemuehl
Keyword(s):  
Heat Transfer ◽  
Thermal Efficiency ◽  
Low Cost ◽  
Convection Heat Transfer ◽  
Calibration Error ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Electrical Efficiency ◽  
Building Integrated Photovoltaic ◽  
Low Efficiency

The performance of Building-Integrated Photovoltaic-Thermal (BIPV/T) collector is examined in this study. A full scale-test collector is monitored over several weeks in the summer of 2008 and measured data is used to calibrate a heat transfer model implemented in a common scientific computing software package. Following calibration, error between experimental measurements and the calibrated model outputs is within the limits of measurement uncertainty. Collector simulations are constructed to examine thermal efficiency, the effectiveness of the collector as a night-sky radiator, the effect of heat collection on electrical efficiency, the effect of two common exterior convection coefficients on collector performance, and the effect of eliminating the air gap between the PV and absorber surfaces. Overall collector thermal efficiency is relatively low compared to existing collectors. However, the potential low cost of the system could allow larger collector areas to compensate for low efficiency, especially in warm climates. Combined thermal and electrical efficiency can be as high as 34%. Additional analysis also indicates that the predicted thermal performance is highly dependent on the thermal resistance between the PV cells and the absorber plate and is sensitive to assumptions regarding wind-driven convection heat transfer coefficients.

Characterizations of ZnS/CuInS2 Film Fabricated by Electrochemical Deposition Process for Solar Cell Devices

2012 ◽  
Vol 15 (2) ◽  
pp. 103-106 ◽  
Author(s):  
Yih-Min Yeh ◽  
Hsiang Chen ◽  
Chuan Hao Liao ◽  
Ching Bang Chen ◽  
Bin Yi Chen
Keyword(s):  
Electrochemical Deposition ◽  
Low Cost ◽  
Deposition Process ◽  
Thin Film Solar Cells ◽  
Constant Current ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sulfur Atmosphere ◽  
Surface Morphologies ◽  
Zns Films

In this study, CuInS2 (CIS) films were fabricated by a two-step, non-vacuum process. Electrochemical deposition (ECD) was first used to prepare Cu-In precursors on Mo substrate under constant current. Then, CuInS2 films were prepared by sulfurization of the Cu-In precursors in sulfur atmosphere. The surface morphologies, compositions, and transmittance of the CuInS2 and ZnS films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and UV-VIS, respectively. The results show that a high-quality CIS thin film solar cells by low-cost, non-vacuum process could be obtained.

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