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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 - Anomaly Preserving Content-Aware Hyperspectral Image Size Reduction
摘要： With the increase in the number and availability of imaging sensors, data size or dimensionality reduction, compression, archiving and retrieval algorithms are gaining importance. Whereas in the past, for hyperspectral images, the size reduction has been mostly concerned with the spectral domain, the increase in the number and spatial sizes of the hyperspectral images has raised the question whether a spatial reduction is also feasible. However, this reduction should be conducted in a content-aware fashion and should preserve the important and relevant information in the scene whether for archiving and retrieval purposes, or for following image processing tasks. In this work, an anomaly-preserving content-aware size reduction approach is proposed for hyperspectral images. The approaches utilizes seam carving with a spatial homogeneity energy function to preserve anomalies while performing reduction. Synthetic and real datasets are used to validate the proposed methodology.
关键词： size reduction,Anomaly,content-aware,hyperspectral,seam carving
更新于2025-09-23 15:21:21
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SYNTHESIS OF THINNED ARRAY WITH SIDE LOBE LEVELS REDUCTION USING IMPROVED BINARY INVASIVE WEED OPTIMIZATION
摘要： As a very powerful optimization algorithm, invasive weed optimization has been widely applied to continuous optimization problems in electromagnetic (EM) field. However, the optimization of a thinned array can be formulated as a discrete-variable optimization problem with solutions encoded as binary strings. Therefore, in this paper, an improved binary invasive weed optimization (IBIWO) is proposed to design a thinned array with minimum side lobe levels. To evaluate the performance of the proposed algorithm, two examples have been presented and solved. Simulation results of the proposed thinned arrays obtained by IBIWO are compared with published results to verify the effectiveness of the proposed method.
关键词： binary invasive weed optimization,side lobe levels reduction,IBIWO,thinned array
更新于2025-09-23 15:21:21
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Adaption of an array spectroradiometer for total ozone column retrieval using direct solar irradiance measurements in the UV spectral range
摘要： A compact array spectroradiometer that enables precise and robust measurements of solar UV spectral direct irradiance is presented. We show that this instrument can retrieve total ozone column (TOC) accurately. The internal stray light, which is often the limiting factor for measurements in the UV spectral range and increases the uncertainty for TOC analysis, is physically reduced so that no other stray-light reduction methods, such as mathematical corrections, are necessary. The instrument has been extensively characterised at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. During an international total ozone measurement intercomparison at the Iza?a Atmospheric Observatory in Tenerife, the high-quality applicability of the instrument was verified with measurements of the direct solar irradiance and subsequent TOC evaluations based on the spectral data measured between 12 and 30 September 2016. The results showed deviations of the TOC of less than 1.5 % from most other instruments in most situations and not exceeding 3 % from established TOC measurement systems such as Dobson or Brewer.
关键词： stray-light reduction,direct solar irradiance measurements,array spectroradiometer,total ozone column,UV spectral range
更新于2025-09-23 15:21:21
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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 - Speckle Noise Reduction of Time Series Sar Images Based on Wavelet Transform and Kalman Filter
摘要： Synthetic Aperture Radar (SAR) imaging systems can provide valuable sources of earth observation data for various applications. Speckle noise reduction of images produced by these systems is a challenging issue. In this paper, a novel method is proposed for reducing the speckle noise from time series SAR images. This method is mainly based on wavelet transform and Kalman filter. The proposed method is applied to a time series SAR images acquired by Sentinel-1 over Tehran, Iran. To demonstrate the performance of the proposed method, both qualitative and quantitative evaluations are reported compared to those of conventional speckle filtering methods. The experimental results show the good performance and efficiency of the proposed method for the speckle reduction of multitemporal SAR images. As well, the results show that the proposed method can preserve the major edge structures and the spatial resolution while reducing the time of processing.
关键词： wavelet transform,speckle noise reduction,kalman filter,Time series SAR images
更新于2025-09-23 15:21:21
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Ordered Mesoporous C?N? with a Combined Triazole and Triazine Framework and Its Graphene Hybrids
摘要： Mesoporous carbon nitrides (MCN) with C3N4 stoichiometry could find applications in fields ranging from catalysis, sensing, and adsorption–separation to biotechnology. The extension of the synthesis of MCN with different nitrogen contents and chemical structures promises access to even a wide range of applications. Here we show mesoporous C3N5 with a combined triazole and triazine framework prepared via a simple self-assembly of 5-amino-1H-tetrazole (5-ATTZ). We are able to hybridize these nanostructures with graphene by using graphene–mesoporous silica hybrids as a template to tune the electronic properties. Density functional theory calculations in combination with various spectroscopic analyses clearly demonstrate that the C3N5 consists of 1 triazole and 2 triazine moieties. The triazole-based mesoporous C3N5 and its graphene hybrids are found to be highly active for oxygen reduction reaction (ORR) with a higher diffusion-limiting current density and a decreased overpotential than those of bulk g-C3N4. We expect that this simple approach to the triazole-based mesoporous C3N5 could be extended for the preparation of series of new class of MCN nanostructures and their hybrids.
关键词： oxygen reduction reaction,porous materials,electrocatalysts,N-rich carbon nitrides,structure
更新于2025-09-23 15:21:21
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The Novel W Parasitic Strip for the Circularly Polarized Microstrip Antennas Design and the Mutual Coupling Reduction between Them
摘要： This paper presents a novel W shaped parasitic strip to design the circularly-polarized (CP) simultaneous transmit and receive (STAR) antennas and reduce the mutual coupling (MC) between them. By disturbing the current fields and inducing the current distribution on the antenna patches, the CP radiation and MC reduction are achieved. The designed CP antennas have 30 MHz 10-dB impedance bandwidth, 16 MHz 3-dB AR bandwidth and approximate 5.08 dBic peak CP gain. This technique also reduce the MC from ?7 dB to ?50 dB when the antennas are placed with a 0.18 λ0 center-to-center distance and a 0.033 λ0 edge-to-edge distance, where λ0 is the free-space wavelength. When achieving the MC reduction, the antenna radiation pattern restores to that of the isolated antenna. Furthermore, the antenna CP gain and efficiency is improved comparing those of the antenna without the parasitic strip or the classic corner cut CP antenna.
关键词： closely spaced,circularly polarized,Mutual coupling reduction,parasitic strip
更新于2025-09-23 15:21:21
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Non-oxidation reduction strategy for highly selective detection of ascorbic acid with dual-ratio fluorescence and colorimetric signals
摘要： Ascorbic acid (AA), one of the most important vitamins, acts a critical role in various physiological reactions and is involved in many diseases. Thus, the development of highly selectivity methods for detecting AA level with the presence of different reducing substances is of great significance in complicated serum matrix. In this paper, a non-oxidation reduction regulation (NRR) strategy was designed to construct a novel dual-ratio fluorescence and colorimetric dual-readout assay for highly selective detection of AA. The strategy involves three processes: Ag+ oxidated o-phenylenediamine (OPD) to 2,3-diaminophenazine (OPDox), AA inhibited the generation of OPDox and the AA was oxidized to dehydroascorbic acid (DHAA). The specific performance of DHAA NRR, due to the condensation reaction between dicarbonyl group of DHAA and diamine group of OPD, that is confirmed by ESI-MS and 1H NMR spectra analysis, can remarkably enhance the selectivity of AA detection. Additionally, the proposed method based on NRR strategy not only provides a sensing platform for probing AA but also shows promising outlook in biomedical studies.
关键词： O-phenylenediamine,Non-oxidation reduction regulation,Ascorbic acid,Dual-ratio,Dual-readout
更新于2025-09-23 15:21:21
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Environmentally Benign Metal-Free Reduction of GO Using Molecular Hydrogen: A Mechanistic Insight
摘要： A simple yet effective methodology to obtain high-quality reduced graphene oxide (RGO) using a tetrahydrofuran suspension of GO under hydrogen at moderate pressure has been demonstrated. The extent of reduction as a function of the pressure of hydrogen gas, temperature, and time was studied, where the abstraction of oxygen is achievable with least mutilation of C-sp2 bonds, hence upholding the integrity of the graphene sheet. Herein, the formation of a short-lived species is proposed, which is possibly responsible for such reduction. A detailed theoretical calculation along with in situ UV?visible experiments reveals the existence of a transient solvated electron species in the reaction medium. The hydrogen RGO (HRGO) achieved a C/O atomic ratio of 11.3. The conductivity measurements show that HRGO reached as high as 934 S/m, which indicates a high quality of RGO. The process is hassle-free, environmentally benign, and can be scaled up effortlessly without compromising the quality of the material.
关键词： reduced graphene oxide,high-quality RGO,environmentally benign,hydrogen reduction,solvated electron
更新于2025-09-23 15:21:21
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Turning Au Nanoclusters Catalytically Active for Visible-Light-Driven CO2 Reduction through Bridging Ligands
摘要： Developing visible-light photocatalytic materials is an ultimate goal for solar-driven CO2 conversion. Au nanoclusters may potentially serve as the components for harvesting visible light, but can hardly perform the solar-driven CO2 reduction due to the lack of catalytic sites. Herein, we report an effective strategy for turning Au nanoclusters catalytically active for visible-light CO2 reduction, in which metal cations (Fe2+, Co2+, Ni2+ and Cu2+) are grafted to the Au NCs using L-cysteine as a bridging ligand. The metal-S bonding bridge facilitates the electron transfer from Au NCs to metal cations so that the grafted metal cations can receive photo-induced electrons and work as catalytic sites for CO2 reduction. The varied d-band centers and binding energies with CO2 for different metal cations allow tuning electron transfer efficiency and CO2 activation energy. Furthermore, the photostability of Au NCs-based catalyst can be significantly enhanced through the encapsulation with metal-organic frameworks. This work opens a new door for the photocatalyst design based on metal clusters, and sheds light on the surface engineering of metal clusters toward specific applications.
关键词： gold cluster,CO2 reduction,ligand,catalytic sites,Photocatalysis
更新于2025-09-23 15:21:21
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Biomass-derived carbon boosted catalytic properties of tungsten-based nanohybrids for accelerating the triiodide reduction in dye-sensitized solar cells
摘要： Manganese tungstate (MWO), zinc tungstate (ZWO), and copper tungstate (CWO) embedded biomass-derived carbon (MWO-C, ZWO-C, CWO-C) was synthesized by hydrothermal treatment and investigated as counter electrode (CE) catalyst to test electrochemical activity. Biomass-derived carbon was used as the shape controlling agent, which changed the morphology of MWO from spherical to spindle-like. Owing to the synergistic effect between tungsten-based bimetal oxides and biomass-derived carbon, the MWO-C, ZWO-C, and CWO-C catalysts exhibited enhanced electrochemical performance in dye-sensitized solar cells (DSSCs) system. The MWO-C, ZWO-C and CWO-C catalysts in DSSCs showed outstanding power conversion efficiency (PCE) of 7.33%, 7.61%, and 6.52%, respectively, as compared with 7.04% for Pt based devices. Biomass-derived carbon improves the catalytic properties of tungsten-based nanohybrids. The results showed that biomass-derived carbon-enhanced inorganic compound as CE catalysts are promising alternatives to Pt-based CE catalysts for energy conversion devices.
关键词： Triiodide reduction reaction,Counter electrode catalyst,Biomass-derived carbon,Tungsten-based nanohybrids,Dye-sensitized solar cells
更新于2025-09-23 15:21:01