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Cascaded plasmonic nanorod antenna for large broadband local electric field enhancement
摘要： During whistler wave excitation, electron energy is transferred from electrons to waves. There is little observational evidence that such a process operates effectively in the magnetotail, however. Using a large observational database from the THEMIS mission, we investigate whistler wave excitation within and around dipolarizing flux bundles (DFBs), critical energy transporters in the magnetotail, and the evacuation of perpendicular electron energy by whistler wave Poynting flux. We find that perpendicular anisotropy of suprathermal (~10keV) electrons is the major free energy source for whistler wave excitation near DFBs. During earthward transport of electrons by DFBs, 3.7% of the suprathermal electron energy flux is evacuated in the form of whistler wave Poynting flux. This suggests that whistler waves play an important role in electron thermodynamics in the magnetotail by significantly modifying the otherwise adiabatically-shaped electron distributions.
关键词： dipolarizing flux bundles,THEMIS mission,electron energy,whistler waves,magnetotail
更新于2025-09-11 14:15:04
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Micron-Sized Constrictions Fabricated Using the Femtosecond Laser Technique on YBCO Thin Films
摘要： In this paper, I report on the fabrication of micron-sized constrictions in YBCO thin films using the femtosecond laser technique. The constrictions are S-shaped superconducting weak links fabricated on YBCO thin films. The constrictions show a measurable superconducting current flowing through them. Current-voltage (I–V) characteristics were used to determine the critical current IC of the constrictions at 77 K. The width of the constrictions was determined at the narrowest point using SEM (scanning electron microscope). Three micron-sized constrictions were fabricated with a width of 2.88 μm, 1.72 μm, and 1.69 μm and a length of 5 μm. Based on the width and length of these constrictions in relation to the coherence length (ξ) of the YBCO, these constrictions should conduct supercurrent by Abrikosov vortices. The SEM images show that the femtosecond laser heats the samples beyond the geometric boundary, damaging some of the superconductive phases of the YBCO constrictions. As a result, the constrictions conduct current by one-dimensional depairing.
关键词： Atomic force microscope (AFM),Abrikosov vortices,Flux pinning,YBCO thin film,Lasers,Critical currents,Scanning electron microscopy (SEM)
更新于2025-09-11 14:15:04
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Field Demonstration Of A Nanophotonics Enabled Solar Membrane Distillation Reactor For Desalination
摘要： Nanophotonics Enhanced Solar Membrane Distillation (NESMD) is a highly innovative process that overcomes the intrinsic limitation of membrane distillation (MD) in energy consumption, thermal efficiency, and scalability. It applies nanophotonic materials based photothermal coating on a commercial PTFE membrane surface. The coating serves as a solar-thermal collector, absorbs sunlight, and generates highly localized heat, while the rest of the membrane performs the MD function. In the current work, an original pilot-scale NESMD reactor was designed, developed, built and tested at 29.7174° N, 95.4018° W to investigate the capability of NESMD reactor to desalinate 40 g/l NaCl solution under different intensities of solar irradiance. The preliminary experimental data showed a 99.8% salt removal with a water flux ranging between 0.12 LMH (Liter/m2 hr) at 88 W/m2 (cloudy condition) and 0.77 LMH (Liter/m2 hr) at 1012 W/m2 with an average water flux of 0.55 LMH without energy recovery. Further investigations and improvements are required to enhance the performance of the reactor since it is still a new technology.
关键词： thermal efficiency,water flux,Solar membrane distillation,photothermal coating,solar irradiance
更新于2025-09-11 14:15:04
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Data Acquisition System for ITER Neutron Diagnostic Divertor Neutron Flux Monitor
摘要： The ITER nuclear diagnostics Divertor Neutron Flux Monitor (DNFM) is designed to determine the ITER fusion power. DNFM diagnostic provides a neutron yield and fusion power measurements for both deuterium-deuterium and deuterium-tritium plasmas with the required time resolution and uncertainty. The data acquisition system (DAQ) is a part of the DNFM diagnostic. This system is designed for signal processing of the three neutron detectors modules, each including six fission chambers (FC). The DAQ system performs the following functions: FCs bias generation and signals detection; transformation of the measurement data into neutron flux values at the location of the detector module; detectors module FCs and measurement channels calibration with external neutron source; data transfer to the upper systems – CODAC; diagnostics of measurement channels and their components, including a detector modules and a communication lines.
关键词： Divertor Neutron Flux Monitor,Neutron Diagnostic,Fission Chambers,ITER,Data Acquisition System
更新于2025-09-11 14:15:04
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Mapping the flux penetration profile in a 2G-HTS tape at the microscopic scale: deviations from a classical critical state model
摘要： Understanding vortex behaviour at microscopic scales is of extreme importance for the development of higher performance coated conductors with larger critical currents. Here, we study and map the critical state in a YBCO-based coated conductor at different temperatures using two distinct operation modes of scanning Hall microscopy. An analytical Bean critical state model for long superconducting strips is compared with our measurements and used to estimate the critical current density. We find several striking deviations from the model; pronounced flux front roughening is observed as the temperature is reduced below 83 K due to vortex-bundle formation when strong broadening of the flux front profile is also seen. In higher magnetic fields at the lower temperature of 65 K, fishtail-like magnetization peaks observed in local magnetization measurements are attributed to flux-locking due to an increase in the critical current density near the edges of the tape, which we tentatively link to vortex pinning matching effects. Our measurements provide valuable insights into the rich vortex phenomena present in coated conductor tapes at the microscopic scale.
关键词： coated conductors,second generation superconducting tape,scanning Hall microscopy,flux front
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Modtran <sup>?</sup> 6 Multiple Line-Of-Sight (MLOS) Option
摘要： The MODTRAN6 radiative transfer model enjoys widespread use throughout the remote sensing community. A multiple line-of-sight option is now available that dramatically increases processing time when spectral transmittances and radiances are required for multiple paths within a scene. The option is demonstrated for three applications: (1) modeling residuals between plane-parallel and spherical earth atmosphere hemispherical fluxes; (2) computing wave boundary layer weighting functions; and (3) generating look-up tables for simulating an airborne visible through shortwave infrared hyperspectral sensor.
关键词： weighting functions,MODTRAN radiative transfer,wave boundary layer,DISORT scatter,hyperspectral sensor look-up table,hemispherical flux
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - An AC Four-Terminal Low Value Resistance Bridge
摘要： This paper describes a current transformer based ac four-terminal low value resistance measurement bridge. The design and performance of this bridge is presented, which compares resistors from 10 to 0.1 ohm over a frequency range of 100 Hz-10 kHz. The reference ratio arm used in this bridge is a special designed high accurate zero-flux current transformer (ZFCT). The current ratio value of the ZFCT is self-calibrated by using the conventional build up method. An auxiliary current transformer combined with variable impedance is used to constitute the wagner circuit.
关键词： zero-flux current transformer,ac bridge,resistance measurement,Measurement
更新于2025-09-10 09:29:36
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Review of the solar flux distribution in concentrated solar power: non-uniform features, challenges, and solutions
摘要： Concentrated solar flux distribution in the concentrated solar power (CSP) systems is extremely non-uniform, which can lead to high local temperature and large temperature gradient in solar receivers that will cause great challenges for the safety and efficient operation of the system. This paper introduces the non-uniform flux features in four CSP technologies including the parabolic-trough collector, the linear Fresnel collector, the solar power tower, and the parabolic-dish collector. Challenges including degeneration of the materials, thermal stress and deformation, and overburning are summarized. The corresponding solutions proposed to tackle these challenges are emphatically reviewed, and a recommendation for the optimization of the solar collector is provided from this review, which is that the solar flux distribution and the heat transfer ability of the heat transfer fluid (HTF) should match with each other as well as possible. From this point of view, the existing solutions are classified into two groups. One is optimizing the heat transfer ability of the HTF to match with the flux distribution, which is called the passive approach. The other is homogenizing the flux distribution to match with the identical heat transfer ability of the HTF, which is called the active approach. This review can help to have a better understanding of the non-uniform solar flux features in CSPs, and provide guidance for solving the corresponding challenges.
关键词： Non-uniform temperature,Solar receiver,Concentrated solar power,Non-uniform solar flux,Challenges and solutions,Solar concentrator
更新于2025-09-10 09:29:36
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Fouling process and anti-fouling mechanisms of dynamic membrane assisted by photocatalytic oxidation under sub-critical fluxes
摘要： Membrane fouling is often considered as a hindrance for the application of microfiltration /ultrafiltration (MF/UF) for drinking water production. A novel process of photocatalytic membrane reactor/dynamic membrane (PMR/DM), operating in a continuous mode under sub-critical flux, was proposed for the mitigation of membrane fouling caused by humic acids (HAs) in water. The mechanism of membrane fouling alleviation with synergistic photocatalytic oxidation and dynamic layer isolating effect was comprehensively investigated from the characterization of foulants evolution responsible for the reversible and irreversible fouling. The results showed that the PMR/DM utilized photocatalytic oxidation to enhance the porosity and hydrophilicity of the fouling layer by converting the high molecular weight (MW) and hydrophobic HA molecules with carboxylic functional groups and aromatic structures into low-MW hydrophilic or transphilic fractions, including tryptophan-like or fulvic-like substances. The fouling layer formed in the PMR/DM by combination of photocatalytic oxidation and DM running at sub-critical flux of 100 L?h-1?m-2, was more hydrophilic and more porous, resulting in the lowest trans-membrane pressure (TMP) growth rates, as compared to the processes of ceramic membrane (CM), DM and PMR/CM. Meanwhile, the dynamic layer prevented the foulants, particularly the high-MW hydrophobic fractions, from contacting the primary membrane, which enabled the membrane permeability to be restored easily.
关键词： Photocatalytic Membrane Reactor,Sub-critical Flux,Dynamic Membrane,Humic Acids,Membrane Fouling
更新于2025-09-10 09:29:36
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[IEEE 2017 International Renewable and Sustainable Energy Conference (IRSEC) - Tangier (2017.12.4-2017.12.7)] 2017 International Renewable and Sustainable Energy Conference (IRSEC) - Modeling the Solar Station with the Parabolic Trough Collector Receiver
摘要： In this paper, we present a detailed mathematic model of the Parabolic Trough Collector (PTC) receiver, which has been theoretically studied. The PTC receiver contains a circular tube absorber with a suitable selective layer, surrounded by a glass cover locate along the focal line of PTC receiver. We have established a mathematical model to control the fluid temperature as well as the absorber and the glass cover temperatures.
关键词： heat transfer fluid,solar energy,solar flux,outlet temperatures,Parabolic Trough Collector Receiver
更新于2025-09-10 09:29:36