scholarly journals Properties of Vacuum Arcs Generated by Switching RMF Contacts at Different Ignition Positions

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5596
Author(s):  
Sergey Gortschakow ◽  
Steffen Franke ◽  
Ralf Methling ◽  
Diego Gonzalez ◽  
Andreas Lawall ◽  
...  
Keyword(s):  
High Speed ◽  
Near Infrared ◽  
Active Phase ◽  
Optical Filters ◽  
Green Energy ◽  
Anode Surface ◽  
Optical Absorption Spectroscopy ◽  
Design Development ◽  
Ignition Point ◽  
Zero Crossing

The influence of initiation behavior of the drawn arc on the arc motion, on arc characteristics during the active phase, as well as on the post-arc parameters, was studied. The study was focused on arc dynamics, determination of the anode surface temperature after current interruption, and diagnostics of metal vapor density after current zero crossing. Different optical diagnostics, namely high-speed camera video enhanced by narrow-band optical filters, near infrared spectroscopy, and optical absorption spectroscopy was applied. The initiation behavior of the drawn arc had a clear influence on arc parameters. Higher local electrode temperature occurs in case of the electrodes with ignition point near the outer electrode boundary. This further causes an enhanced density of chromium vapor, even in cases with lower arc duration. The results of this study are important for design development of switching RMF contacts for future green energy applications.

scholarly journals Determination of Cr Density in the Active Phase of a High-current Vacuum Arcs

2017 ◽  
Vol 4 (2) ◽  
pp. 190-193 ◽  
Author(s):  
S. Gortschakow ◽  
A. Khakpour ◽  
S. Popov ◽  
St. Franke ◽  
R. Methling ◽  
...  
Keyword(s):  
High Speed ◽  
Active Phase ◽  
State Density ◽  
Vacuum Arc ◽  
Anode Surface ◽  
High Current ◽  
Electrode Gap ◽  
Broadband Absorption ◽  
Vapour Density

Melting and evaporation of the anode surface strongly influence the interruption capability of vacuum circuit breakers, because they lead to injection of atomic vapour into the inter-electrode gap. Determination of the vapour density and its dynamics with respect to different anode phenomena is therefore of great importance. Results of Cr density measurements in a high-current vacuum arc by using broadband absorption spectroscopy are presented. The vapour density of atomic Cr is determined after the formation of anode spots as well as close to the current zero. Cr I resonance lines at 425.43 nm have been used for the analysis. An AC current pulse with maximum value of 7 kA and a frequency of 100 Hz is applied to a vacuum arc between two cylindrical butt electrodes made of CuCr7525 with a diameter of 10 mm. The high-current anode modes are observed by means of high-speed camera imaging. The temporal evolution of the Cr ground state density is presented and discussed.

scholarly journals Analysis of C2 Swan Bands in Ablation-Dominated Arcs in CO2 Atmosphere

2019 ◽  
Vol 6 (1) ◽  
pp. 82-86
Author(s):  
R. Methling ◽  
St. Franke ◽  
N. Götte ◽  
S. Wetzeler ◽  
D. Uhrlandt
Keyword(s):  
High Speed ◽  
Circuit Breaker ◽  
Optical Emission ◽  
Active Phase ◽  
Video Camera ◽  
Nozzle Geometry ◽  
Optical Absorption Spectroscopy ◽  
Iccd Camera ◽  
Copper Electrodes ◽  
Current Zero

A model circuit breaker in a high-pressure chamber filled with CO<sub>2</sub> atmosphere is used to operate a wall-stabilized arc of several kilo-amperes between tungsten-copper electrodes surrounded by polytetrafluoroethylene nozzles. Optical emission spectroscopy (OES) is carried out via quartz plates inserted into the nozzles using a combination of an imaging spectrometer either with a high-speed video camera or with an ICCD camera. Depending on the nozzle geometry and the current, continuum from C<sub>2</sub> Swan bands was detected as absorption as well as emission pattern. After current zero, optical absorption spectroscopy (OAS) using a xenon flashlamp as broadband background radiator was applied. An absorption around 493 nm was detected and attributed to CuF molecules. The study proofs the existence of C<sub>2</sub> in the active phase and the formation of CuF near to current zero.

scholarly journals A Radiometric Technique for Monitoring the Desulfurization Process of Blister Copper

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 842
Author(s):  
Alejandro Vásquez ◽  
Francisco Pérez ◽  
Maximiliano Roa ◽  
Ignacio Sanhueza ◽  
Hugo Rojas ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spectral Emissivity ◽  
Optical Probe ◽  
Blister Copper ◽  
Optical Absorption Spectroscopy ◽  
Total Irradiance ◽  
Desulfurization Process ◽  
Radiometric Technique ◽  
Collimating Lens ◽  
Total Emissivity

In this paper, a novel optical technique for following the progress of the blister copper desulfurization process is presented. The technique is based on the changes observed in the continuous spectrum of the visible–near-infrared (VIS–NIR) radiation that the blister melt emits while the chemical reactions of the sulfur elimination process are taking place. Specifically, the proposed technique uses an optical probe composed of an optical fiber, a collimating lens, and a quartz tube, which is immersed in the melt. This optical probe provides a field of view of the blowing zone where the desulfurization reaction occurs. The experimental results show that the melt VIS–NIR total irradiance evolves inversely to the SO2 concentration reported by a gas analyzer based on differential optical absorption spectroscopy. Furthermore, the blister copper spectral emissivity as well as the total emissivity observed throughout the process show strong correlation with the sulfur content during desulfurization reaction.

Optical Absorption Spectroscopy of DNA-Wrapped HiPco Carbon Nanotubes

2019 ◽  
Vol 943 ◽  
pp. 95-99
Author(s):  
Li Jun Wang ◽  
Kazuo Umemura
Keyword(s):  
Carbon Nanotubes ◽  
Aqueous Solution ◽  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Optical Characterization ◽  
Optical Absorption Spectroscopy ◽  
Double Stranded Dna

Optical absorption spectroscopy provides evidence for individually dispersed carbon nanotubes. A common method to disperse SWCNTs into aqueous solution is to sonicate the mixture in the presence of a double-stranded DNA (dsDNA). In this paper, optical characterization of dsDNA-wrapped HiPco carbon nanotubes (dsDNA-SWCNT) was carried out using near infrared (NIR) spectroscopy and photoluminescence (PL) experiments. The findings suggest that SWCNT dispersion is very good in the environment of DNA existing. Additionally, its dispersion depends on dsDNA concentration.

scholarly journals Satellite monitoring of different vegetation types by differential optical absorption spectroscopy (DOAS) in the red spectral range

2007 ◽  
Vol 7 (1) ◽  
pp. 69-79 ◽  
Author(s):  
T. Wagner ◽  
S. Beirle ◽  
T. Deutschmann ◽  
M. Grzegorski ◽  
U. Platt
Keyword(s):  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Spectral Range ◽  
Near Infrared ◽  
Vegetation Type ◽  
Differential Optical Absorption Spectroscopy ◽  
Trace Gas ◽  
Satellite Monitoring ◽  
Optical Absorption Spectroscopy ◽  
Vegetation Types

Abstract. A new method for the satellite remote sensing of different types of vegetation and ocean colour is presented. In contrast to existing algorithms relying on the strong change of the reflectivity in the red and near infrared spectral region, our method analyses weak narrow-band (few nm) reflectance structures (i.e. "fingerprint" structures) of vegetation in the red spectral range. It is based on differential optical absorption spectroscopy (DOAS), which is usually applied for the analysis of atmospheric trace gas absorptions. Since the spectra of atmospheric absorption and vegetation reflectance are simultaneously included in the analysis, the effects of atmospheric absorptions are automatically corrected (in contrast to other algorithms). The inclusion of the vegetation spectra also significantly improves the results of the trace gas retrieval. The global maps of the results illustrate the seasonal cycles of different vegetation types. In addition to the vegetation distribution on land, they also show patterns of biological activity in the oceans. Our results indicate that improved sets of vegetation spectra might lead to more accurate and more specific identification of vegetation type in the future.

scholarly journals Highly Efficient Near-Infrared Detector Based on Optically Resonant Dielectric Nanodisks

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 428
Author(s):  
Reza Masoudian Saadabad ◽  
Christian Pauly ◽  
Norbert Herschbach ◽  
Dragomir N. Neshev ◽  
Haroldo T. Hattori ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
High Speed ◽  
Near Infrared ◽  
Infrared Detector ◽  
High Quantum Efficiency ◽  
Fast Detection ◽  
High Quantum ◽  
Resonant Modes ◽  
Infrared Wavelengths ◽  
Dielectric Metasurface

Fast detection of near-infrared (NIR) photons with high responsivity remains a challenge for photodetectors. Germanium (Ge) photodetectors are widely used for near-infrared wavelengths but suffer from a trade-off between the speed of photodetection and quantum efficiency (or responsivity). To realize a high-speed detector with high quantum efficiency, a small-sized photodetector efficiently absorbing light is required. In this paper, we suggest a realization of a dielectric metasurface made of an array of subwavelength germanium PIN photodetectors. Due to the subwavelength size of each pixel, a high-speed photodetector with a bandwidth of 65 GHz has been achieved. At the same time, high quantum efficiency for near-infrared illumination can be obtained by the engineering of optical resonant modes to localize optical energy inside the intrinsic Ge disks. Furthermore, small junction capacitance and the possibility of zero/low bias operation have been shown. Our results show that all-dielectric metasurfaces can improve the performance of photodetectors.

scholarly journals Nanoprinted high-neuron-density optical linear perceptrons performing near-infrared inference on a CMOS chip

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Elena Goi ◽  
Xi Chen ◽  
Qiming Zhang ◽  
Benjamin P. Cumming ◽  
Steffen Schoenhardt ◽  
...  
Keyword(s):  
Machine Learning ◽  
High Speed ◽  
Near Infrared ◽  
Single Layer ◽  
Infrared Region ◽  
Optical Devices ◽  
Medical Diagnostics ◽  
Oxide Semiconductor ◽  
Process Data ◽  
Neuron Density

AbstractOptical machine learning has emerged as an important research area that, by leveraging the advantages inherent to optical signals, such as parallelism and high speed, paves the way for a future where optical hardware can process data at the speed of light. In this work, we present such optical devices for data processing in the form of single-layer nanoscale holographic perceptrons trained to perform optical inference tasks. We experimentally show the functionality of these passive optical devices in the example of decryptors trained to perform optical inference of single or whole classes of keys through symmetric and asymmetric decryption. The decryptors, designed for operation in the near-infrared region, are nanoprinted on complementary metal-oxide–semiconductor chips by galvo-dithered two-photon nanolithography with axial nanostepping of 10 nm1,2, achieving a neuron density of >500 million neurons per square centimetre. This power-efficient commixture of machine learning and on-chip integration may have a transformative impact on optical decryption3, sensing4, medical diagnostics5 and computing6,7.

scholarly journals Online Tool Wear Classification during Dry Machining Using Real Time Cutting Force Measurements and a CNN Approach

2018 ◽  
Vol 2 (4) ◽  
pp. 72 ◽  
Author(s):  
German Terrazas ◽  
Giovanna Martínez-Arellano ◽  
Panorios Benardos ◽  
Svetan Ratchev
Keyword(s):  
Tool Wear ◽  
High Speed ◽  
Big Data Analytics ◽  
Design Development ◽  
Online Tool ◽  
Overall Evaluation ◽  
Intelligent Information ◽  
Key Enabling Technologies ◽  
Processing Techniques ◽  
Tool Wear Classification

The new generation of ICT solutions applied to the monitoring, adaptation, simulation and optimisation of factories are key enabling technologies for a new level of manufacturing capability and adaptability in the context of Industry 4.0. Given the advances in sensor technologies, factories, as well as machine tools can now be sensorised, and the vast amount of data generated can be exploited by intelligent information processing techniques such as machine learning. This paper presents an online tool wear classification system built in terms of a monitoring infrastructure, dedicated to perform dry milling on steel while capturing force signals, and a computing architecture, assembled for the assessment of the flank wear based on deep learning. In particular, this approach demonstrates that a big data analytics method for classification applied to large volumes of continuously-acquired force signals generated at high speed during milling responds sufficiently well when used as an indicator of the different stages of tool wear. This research presents the design, development and deployment of the system components and an overall evaluation that involves machining experiments, data collection, training and validation, which, as a whole, has shown an accuracy of 78 % .

scholarly journals Orbiting Carbon Observatory-2 (OCO-2) cloud screening algorithms; validation against collocated MODIS and CALIOP data

2015 ◽  
Vol 8 (12) ◽  
pp. 12663-12707 ◽  
Author(s):  
T. E. Taylor ◽  
C. W. O'Dell ◽  
C. Frankenberg ◽  
P. Partain ◽  
H. Q. Cronk ◽  
...  
Keyword(s):  
Surface Pressure ◽  
Near Infrared ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Algorithm ◽  
Orthogonal Polarization ◽  
Screening Methods ◽  
Data Set ◽  
Atmospheric Scattering ◽  
Carbon Dioxide Co2 ◽  
Cloud Screening

Abstract. The objective of the National Aeronautics and Space Administration's (NASA) Orbiting Carbon Observatory-2 (OCO-2) mission is to retrieve the column-averaged carbon dioxide (CO2) dry air mole fraction (XCO2) from satellite measurements of reflected sunlight in the near-infrared. These estimates can be biased by clouds and aerosols within the instrument's field of view (FOV). Screening of the most contaminated soundings minimizes unnecessary calls to the computationally expensive Level 2 (L2) XCO2 retrieval algorithm. Hence, robust cloud screening methods have been an important focus of the OCO-2 algorithm development team. Two distinct, computationally inexpensive cloud screening algorithms have been developed for this application. The A-Band Preprocessor (ABP) retrieves the surface pressure using measurements in the 0.76 μm O2 A-band, neglecting scattering by clouds and aerosols, which introduce photon path-length (PPL) differences that can cause large deviations between the expected and retrieved surface pressure. The Iterative Maximum A-Posteriori (IMAP) Differential Optical Absorption Spectroscopy (DOAS) Preprocessor (IDP) retrieves independent estimates of the CO2 and H2O column abundances using observations taken at 1.61 μm (weak CO2 band) and 2.06 μm (strong CO2 band), while neglecting atmospheric scattering. The CO2 and H2O column abundances retrieved in these two spectral regions differ significantly in the presence of cloud and scattering aerosols. The combination of these two algorithms, which key off of different features in the spectra, provides the basis for cloud screening of the OCO-2 data set. To validate the OCO-2 cloud screening approach, collocated measurements from NASA's Moderate Resolution Imaging Spectrometer (MODIS), aboard the Aqua platform, were compared to results from the two OCO-2 cloud screening algorithms. With tuning to allow throughputs of &amp;simeq; 30 %, agreement between the OCO-2 and MODIS cloud screening methods is found to be &amp;simeq; 85 % over four 16-day orbit repeat cycles in both the winter (December) and spring (April–May) for OCO-2 nadir-land, glint-land and glint-water observations. No major, systematic, spatial or temporal dependencies were found, although slight differences in the seasonal data sets do exist and validation is more problematic with increasing solar zenith angle and when surfaces are covered in snow and ice and have complex topography. To further analyze the performance of the cloud screening algorithms, an initial comparison of OCO-2 observations was made to collocated measurements from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). These comparisons highlight the strength of the OCO-2 cloud screening algorithms in identifying high, thin clouds but suggest some difficulty in identifying some clouds near the surface, even when the optical thicknesses are greater than 1.

scholarly journals Heterostructured silicon-germanium-silicon p-i-n avalanche photodetectors for chip-integrated optoelectronics -INVITED

2021 ◽  
Vol 255 ◽  
pp. 01002
Author(s):  
Daniel Benedikovic ◽  
Leopold Virot ◽  
Guy Aubin ◽  
Jean-Michel Hartmann ◽  
Farah Amar ◽  
...  
Keyword(s):  
Health Monitoring ◽  
Optical Communications ◽  
Silicon Germanium ◽  
High Speed ◽  
Near Infrared ◽  
Building Blocks ◽  
Electrical Signal ◽  
Avalanche Photodetectors ◽  
Infrared Wavelengths ◽  
Germanium Silicon

Optical photodetectors are at the forefront of photonic research since the rise of integrated optics. Photodetectors are fundamental building blocks for chip-scale optoelectronics, enabling conversion of light into an electrical signal. Such devices play a key role in many surging applications from communication and computation to sensing, biomedicine and health monitoring, to name a few. However, chip integration of optical photodetectors with improved performances is an on-going challenge for mainstream optical communications at near-infrared wavelengths. Here, we present recent advances in heterostructured silicon-germanium-silicon p-i-n photodetectors, enabling high-speed detection on a foundry-compatible monolithic platform.

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