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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Optimal development of location and technology independent machine learning photovoltaic performance predictive models
摘要： The Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) missions provide Level-1 brightness temperature (Tb) observations that are used for global soil moisture estimation. However, the nature of these Tb data differs: the SMOS Tb observations contain atmospheric and select reflected extraterrestrial (“Sky”) radiation, whereas the SMAP Tb data are corrected for these contributions, using auxiliary near-surface information. Furthermore, the SMOS Tb observations are multiangular, whereas the SMAP Tb is measured at 40? incidence angle only. This letter discusses how SMOS Tb, SMAP Tb, and radiative transfer modeling components can be aligned in order to enable a seamless exchange of SMOS and SMAP Tb data in soil moisture retrieval and assimilation systems. The aggregated contribution of the atmospheric and reflected Sky radiation is, on average, about 1 K for horizontally polarized Tb and 0.5 K for vertically polarized Tb at 40? incidence angle, but local and short-term values regularly exceed 5 K.
关键词： galaxy,Soil Moisture Ocean Salinity (SMOS),soil moisture,Atmosphere,Soil Moisture Active Passive (SMAP),brightness temperature (Tb)
更新于2025-09-19 17:13:59
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Contribution of cellulosic fibre filter on atmosphere moisture content in laser powder bed fusion additive manufacturing
摘要： Cellulosic materials are commonly used to manufacture the particulate filters used in laser powder bed fusion (LpBf) additive manufacturing (AM) equipment. An experimental approach has been used to calculate the moisture quantity and kinetics of sorption in a cellulosic filter at varying relative humidity (RH) levels. A prediction of the amount of moisture which can be theoretically held within a filter during storage before its use has been obtained. Subsequently, the quantity and the rate of moisture desorption which can be transferred into the build chamber during LpBf is presented. this work highlights the importance of filter storage and conditioning prior to use in additive manufacturing processing.
关键词： laser powder bed fusion,cellulosic fibre filter,atmosphere moisture content,additive manufacturing
更新于2025-09-19 17:13:59
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Laser and Optical Sounding of the Atmosphere
摘要： Lidar and searchlight instruments and techniques for atmospheric research developed at the V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, in recent years are described. Key results obtained using these techniques are presented.
关键词： aerosol,atmosphere,gas impurities,lidar,scattering
更新于2025-09-19 17:13:59
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Singular Atmospheric Optics: From Wavefront Dislocations to Synthesis of Vortex Laser Beams
摘要： Studies on the singular optics of scalar wave fields carried out in the world and at V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences (IAO SB RAS) are reviewed. The study results of the processes of origination and annihilation of phase singularities are generalized. The methods for singular phase reconstruction and their applicability to the problems of adaptive focusing of radiation in randomly inhomogeneous media are examined. The energy, statistical, and topological properties of vortex optical beams propagating through a turbulent atmosphere are analyzed. The results of the synthesis of vortex beams with quickly controllable orbital angular momentum by the matrix approach developed at IAO SB RAS are described.
关键词： vortex beam,turbulent atmosphere,probability density function,intensity fluctuations
更新于2025-09-19 17:13:59
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Gas chromatography vs. quantum cascade laser-based??N <sub/>2</sub> O flux measurements using a novel chamber design
摘要： Recent advances in laser spectrometry offer new opportunities to investigate the soil–atmosphere exchange of nitrous oxide. During two field campaigns conducted at a grassland site and a willow field, we tested the performance of a quantum cascade laser (QCL) connected to a newly developed automated chamber system against a conventional gas chromatography (GC) approach using the same chambers plus an automated gas sampling unit with septum capped vials and subsequent laboratory GC analysis. Through its high precision and time resolution, data of the QCL system were used for quantifying the commonly observed nonlinearity in concentration changes during chamber deployment, making the calculation of exchange fluxes more accurate by the application of exponential models. As expected, the curvature values in the concentration increase was higher during long (60 min) chamber closure times and under high-flux conditions (FN2O > 150 μg N m?2 h?1) than those values that were found when chambers were closed for only 10 min and/or when fluxes were in a typical range of 2 to 50 μg N m?2 h?1. Extremely low standard errors of fluxes, i.e., from ～ 0.2 to 1.7 % of the flux value, were observed regardless of linear or exponential flux calculation when using QCL data. Thus, we recommend reducing chamber closure times to a maximum of 10 min when a fast-response analyzer is available and this type of chamber system is used to keep soil disturbance low and conditions around the chamber plot as natural as possible. Further, applying linear regression to a 3 min data window with rejecting the first 2 min after closure and a sampling time of every 5 s proved to be sufficient for robust flux determination while ensuring that standard errors of N2O fluxes were still on a relatively low level. Despite low signal-to-noise ratios, GC was still found to be a useful method to determine the mean the soil–atmosphere exchange of N2O on longer timescales during specific campaigns. Intriguingly, the consistency between GC and QCL-based campaign averages was better under low than under high N2O efflux conditions, although single flux values were highly scattered during the low efflux campaign. Furthermore, the QCL technology provides a useful tool to accurately investigate the highly debated topic of diurnal courses of N2O fluxes and its controlling factors. Our new chamber design protects the measurement spot from unintended shading and minimizes disturbance of throughfall, thereby complying with high quality requirements of long-term observation studies and research infrastructures.
关键词： gas chromatography,soil–atmosphere exchange,chamber design,nitrous oxide,quantum cascade laser,flux measurements
更新于2025-09-19 17:13:59
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The effect of annealing conditions: temperature, time, ramping rate and atmosphere on nanocrystal Cu2ZnSnS4 (CZTS) thin film solar cell properties
摘要： Cu2ZnSnS4 (CZTS) nanoparticles were fabricated successfully using the hot injection method; CZTS films were deposited by spin coating of nanocrystal ink. The aim of this work is to study the effect of annealing parameters: temperature, time, ramping rate and atmosphere on CZTS thin film structure and optical properties. XRD, Raman Spectroscopy, SEM, EDX mapping are used to analyse the films and they demonstrate the increase in quality and improvement in the crystallinity of CZTS and the homogeneity of elements which is one of the important factors for CZTS thin film solar cells. The crystallinity, structure and chemical composition of CZTS thin films increased and improved under annealing in H2S+N2 atmosphere which demonstrated that annealing at 500 oC for 1 h with a ramping rate of 10 oC/min under H2S+N2 atmosphere is a suitable condition for the fabrication of CZTS thin films used in solar cell devices.
关键词： Annealing temperature,CZTS,Cu2ZnSnS4,Annealing time,Thin film solar PV,Annealing atmosphere,Annealing ramping rate
更新于2025-09-16 10:30:52
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Fiber Optic and Atmospheric Optical Communication || Atmospheric Communication Channels
摘要： The atmosphere is a gaseous envelope that surrounds the Earth from the ground surface up to several hundred kilometers. The atmosphere consists of different kinds of gaseous, liquid, and crystal structures, including effects of gas molecules (atoms), aerosol, cloud, fog, rain, hail, dew, rime, glaze, and snow. Except for the first two, the others are usually called hydrometeors in the literature. Furthermore, due to irregular and sporadic air streams and motions, that is, irregular wind motions, chaotic structures defined as atmospheric turbulence are also present in the atmosphere.
关键词： Hydrometeors,Atmosphere,Aerosol,Turbulence,Optical Communication
更新于2025-09-12 10:27:22
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Phase Offset Tracking for Free Space Digital Coherent Optical Communication System
摘要： The coherent receiving method can improve the sensitivity of an optical signal receiver for free space optical communication system effectively. To implement coherent receiving, the phase offset between the local laser in the receiver and the received optical signal through the atmosphere needs to be measured and estimated. The commonly used algorithm is the Viterbi-Viterbi phase offset estimation method (VVPE) and this method always produces great errors especially with low SNR (signal to noise ratio). To improve the estimation performance, we present a new method combing the VVPE with the Kalman filter (VVPE-KF) to estimate the phase offset. This method can lower the estimation error by no less than 60%, when the SNR is low. To verify the performance of this new method, the constant parameter channel and atmosphere turbulence channel are employed to evaluate the algorithm. The impact of the atmosphere turbulence intensity on the tracking error is discussed.
关键词： estimation method,Kalman filter,estimation error,atmosphere turbulence,Viterbi-Viterbi algorithm,phase offset
更新于2025-09-12 10:27:22
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Design and Manufacturing of a Protective Nozzle for Highly Reactive Materials Processing via Laser Material Deposition
摘要： Laser Material Deposition (LMD) is a near-net-shape additive process. Powder particles are usually employed as filler material, which is injected through a powder nozzle (coaxial or off-axis) and then completely molten by a laser beam. The possibility to add material on complex 3D surfaces makes LMD a key process in the repair and wear/corrosion protection applications. The present work is focused on the improvement of the design & manufacturing of a LMD nozzle, what introduces two main advantages: the possibility to process a wider variety of materials by generating a protective atmosphere and the improvement of the efficiency of the nozzle. The results of numerical simulations are used for optimizing the design of the protective cone of the LMD nozzle, which is then manufactured and experimentally validated. Finally, the proper performance of the resultant nozzle is tested depositing Ti6Al4V.
关键词： efficiency,reactive materials,protective atmosphere,simulation,laser material deposition,oxidation-free,laser cladding,coaxial nozzle
更新于2025-09-12 10:27:22
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Decoy State Quantum Key Distribution via Beam-Wandering Modeled Atmosphere Channel
摘要： We investigate the decoy state quantum key distribution via the atmosphere channels. We consider the efficient decoy state method with one-signal state and two-decoy states. Our results show that the decoy state method works even in the channels with fluctuating transmittance. Nevertheless, the key generation rate will be dramatically decreased by atmosphere turbulence, which sheds more light on the characterization of atmosphere turbulence in realistic free-space based quantum key distributions.
关键词： quantum key distribution,atmosphere turbulence,decoy state,beam-wandering model
更新于2025-09-12 10:27:22