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Estimation method for electronic tag emission power in the RFID positioning system
摘要： RFID positioning system plays an important role in the management of electronic tag lifecycle and safety monitoring. The traditional estimation methods for electronic tag emission power are relatively low in precision and require setting large numbers of reference tags. Therefore, a new method of electronic tag emission power estimation in the RFID positioning system is proposed in this paper. In the electronic tag of the RFID positioning system, it is required that the radio link between the reader and the electronic tags should pass through the air and electronic tags. And the path loss mainly includes the re?ection loss between the air-electronic tags interface and attenuation in the electronic tags. Based on the boundary conditions between the electronic tag emission frequency and the air-electronic tag interface, comparison measurement method for the electronic tag emission frequency of the open-ended coaxial probe is used to establish the electronic tag emission power estimation model in the RFID positioning system. The numerical analysis shows that the used electronic tag emission frequency comparison measurement has small measurement error, with the absolute value of the measured and simulated re?ection coef?cient difference less than 0.04. This algorithm has improved the precision of the measured emission power, reduced the work load for setting reference tags, and also provided a reference for the design of electronic tag monitoring system in the RFID positioning system.
关键词： estimation,emission power,Electronic tag,RFID positioning system
更新于2025-09-09 09:28:46
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[IEEE 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Greifswald, Germany (2018.9.23-2018.9.28)] 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Emission from Tungsten Nanostructured Tendril Bundles under Local Thermal Load
摘要： Unipolar arcing is a negative phenomenon which takes place during the plasma interaction with the first wall of thermonuclear devices. The mechanisms of arc initiation are still unclear. Formation of nanostructured tendril bundles is possible on the surface of plasma-facing tungsten, and field emission from such structure is expected to be rather high. Moreover such structure can be easily overheated and thermofield emission in this case could start. We show that field emission from such nanostructures is much higher than from tungsten fuzz or pure tungsten, and fusion-relevant heating conditions may lead to steady state thermofield current emission.
关键词： tungsten fuzz,thermofield emission,unipolar arcing,nanostructured tendril bundles
更新于2025-09-09 09:28:46
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Effect of BaO on the phase composition and properties of aluminates for Ba-W cathodes
摘要： In this study, we prepared (4.8+x)BaO·CaO·2Al2O3(0≤x≤1.6) aluminates by calcining the precursors under static air at 1500 °C for 120 min. The precursor powders were prepared using a liquid phase co-precipitation method. The effects of the molar content of BaO on the phase composition (before and after melting), melting properties, environmental stability, evaporation, and emission properties of the aluminates was investigated systematically The results showed that the phase of the aluminates completely transformed from Ba5CaAl4O12 to Ba3CaAl2O7 with an increase in the BaO content. After melting, the phase changed from Ba5CaAl4O12 to a mixed phase of Ba5CaAl4O12 and Ba3CaAl2O7. In the high-temperature molten state, the aluminates were in the ionic state, which generated a relatively low-energy Ba5CaAl4O12 phase during cooling crystallization. With every 0.4 mol increase in the BaO content, the initial melting temperature of the aluminates decreased by 10–20 ℃, while the environmental stability deteriorated gradually. When the aluminates reacted with H2O and CO2 in the air, the original phase still existed and the characteristic peaks gradually broadened, but with the formation of Ca(OH)2, CaCO3, and BaCO3. At 1050 °C, with an increase in the BaO content, the evaporation rate of the Ba-W cathodes increased and the emission current density first increased and then decreased. The main components of the Ba-W cathode evaporation were Ba and BaO. At n(BaO):n(CaO):n(Al2O3)=6:1:2, the Ba-W cathode showed the best emission performance, and its pulse emission current density at 1050 °C was as high as 35.31 A/cm2.
关键词： Ba-W cathode,Emission current,BaO content,Phase composition,Evaporation rate
更新于2025-09-09 09:28:46
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Stable Mesoporous Silica Nanoparticles Incorporated with MoS2 and AIE for Targeted Fluorescence Imaging and Photothermal Therapy of Cancer Cells
摘要： Theranostics for imaging-guided cancer treatment have obtained great attention in recent years for their outstanding capability of both tumor diagnosis and treatment. Molybdenum disulfide (MoS2) nanosheets revealed excellent photothermal conversion efficiency, which could be used as photothermal agents. However, MoS2 nanosheets would often quench or decrease the emission of fluorescence dyes when they were incorporated with these dyes to construct fluorescence-imaging-guided nanotheranostic systems. In this work, MoS2 nanosheets were embedded into mesoporous silica nanoparticles (MSNs), and Aggregation Induced Emission (AIE) fluorogen PhENH2 was chemically modified on the surface of MSNs, which could demonstrate more stable fluorescence emission compared with other MSNs with physically absorbed luminescent molecules. Moreover, folic acid (FA) was also chemically decorated on the nanoparticles to facilitate their targeted bioimaging and photothermal therapy. As expected, the obtained PhENH2-MoS2-FA MSNs could be efficiently taken up by MDA-MB-231 cells than HepG2 cells, owing to the over-expressed FA receptors on MDA-MB-231 cells. Meanwhile, these MDA-MB-231 cells could be efficiently killed under an 808 nm laser irradiation. These results indicated that the achieved multifunctional MSNs chemically decorated with AIE fluorogens would demonstrate more stable fluorescence for bioimaging-targeted photothermal therapy of MDA-MB-231 cells, which made them promising nanotheranostics for further cancer treatment.
关键词： Photothermal Therapy,Molybdenum Disulfide,Targeted Fluorescence Imaging,Aggregation Induction Emission,Stability
更新于2025-09-09 09:28:46
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Structural and photoluminescence properties of UV-excited Er3+ doped Ba2CaWO6 yellowish-green phosphors
摘要： Double perovskite Ba2CaWO6 phosphors doped with different concentrations of Er3+ have been synthesized by the conventional solid state reaction method in air at 1250 °C and are characterized by X-ray diffraction analysis (XRD), Energy Dispersive X-ray Spectrometer (EDS), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and Photoluminescence measurements. An intense green and weak red emissions are observed at 566 nm (4S3/2 →4I15/2), 680 nm (4F9/2 →4I15/2) under 314 nm, 378 nm corresponding to charge transfer band and rare earth excitations respectively. Under charge transfer excitation Ba2CaWO6:xEr3+ samples exhibit high intense emission peaks of Er3+ than the rare earth excitation. This is due to an efficient energy transfer from WO6 6- to Er3+. The maximum emission intensity was observed for 0.08 wt% concentration of Er3+ ions in Ba2CaWO6 phosphors. The critical energy transfer distance among Er3+ ions is calculated to be 15.18 ? and the quenching mechanism is due to dipole-dipole interaction. The energy transfer mechanism is discussed based on the energy level diagram of Er3+. The radiative lifetimes were determined from the fluorescence decay analysis. The CIE color coordinates were calculated from the emission spectra. The result shows that Ba2CaWO6:Er3+ phosphor can be considered as a potential candidate for UV excited yellowish-green phosphor for display applications.
关键词： Ba2CaWO6,phosphor,photoluminescence,Er3+,yellowish-green emission,energy transfer
更新于2025-09-09 09:28:46
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Preparation of silica/polymer nanocomposites with aggregation-induced emission properties as fluorescent responsive coatings
摘要： Fluorescent materials in the recent past have found numerous novel applications in various fields such as medicine, environment, electronics and coatings. For smart coating applications, durability, responsiveness and repeatable functionalities are desirable especially in their solid state. However, due to the known aggregation-caused quench (ACQ) effect, many traditional fluorescent molecules’ intensity tends to diminish at aggregated state. This ultimately affects the traditional fluorescent materials’ use in these applications. To develop smart coatings with suitable properties and responsiveness, herein, a novel aggregation-induced emission (AIE)-based composite fluorescent latex was prepared and systematically studied. Briefly, the approach involved first grafting tetraphenylethene (TPE) derivant onto the silica sol. The resultant modified silica sol could then emit strong fluorescent light courtesy of TPE’s restricted intramolecular rotation. Further, the modified silica sol was used as the surface to emulsion polymerize acrylic latex, forming a fluorescent composite core-shell structure. As a smart and responsive fluorescent composite coating, when cured, it showed fluorescent responsiveness to the external stimuli, such as water and toluene vapor, demonstrating possible application in smart paints.
关键词： Aggregation induced emission,Nanocomposites,Photoluminescence,Fluorescent responsiveness,Restricted intramolecular rotation
更新于2025-09-09 09:28:46
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Dual-Emission Fluorescent Microspheres for the Detection of Biothiols and Hg2+
摘要： Dual-emission nanosensor for Hg2+ detection was prepared by coupling CA-AEAPMS on the surface of RBS-doped modified silica microspheres. The CA-AEAPMS was synthesized by using N-(β-aminoethyl)-γ-aminopropyl methyldimethoxysilane (AEAPMS) and citric acid as the main raw material. The obtained nanosensor showed characteristic fluorescence emissions of Rhodamine B (red) and CA-AEAPMS (blue) under a single excitation wavelength (360 nm). Upon binding to Hg2+, only the fluorescence of CA-AEAPMS was quenched, resulting in the ratiometric fluorescence response of the dual-emission silica microspheres. This ratiometric nanosensor exhibited good selectivity to Hg2+ over other metal ions, because of the amide groups on the surface of CA-AEAPMS serving as the Hg2+ recognition sites. The ratio of F450/F580 linearly decreased with the increasing of Hg2+ concentration in the range of 0 to 3 × 10?6 M, and a detection limit was as low as 97 nM was achieved. Then, the addition of three thiol-containing amino acids (Cys, Hcy, GSH) to the quenched fluorescence solution with Hg2+ can restore the fluorescence, and the detection limits of the three biothiols (Cys, Hcy, GSH) are 0.133 μM, 0.086 μM, and 0.123 μM, respectively.
关键词： dual-emission,fluorescence,silica microspheres
更新于2025-09-09 09:28:46
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A Graphene-Coated Mo Tip Array for Highly-Efficient Nanostructured Electron Field Emitters
摘要： An ef?cient electron ?eld emitter based on a monolayer graphene coated well aligned Mo tip array has been designed, fabricated, and evaluated. The advantages of this hybrid nanostructure ?lm morphology are explored and discussed. Ef?cient and stable ?eld emissions with low turn-on ?elds have been observed with the new devices. It is further found that the combination of graphene and Mo tip array leads to signi?cant improvements in ef?ciency for the nanoscale heterostructure emitters.
关键词： molybdenum,tip array,?eld emission,graphene
更新于2025-09-09 09:28:46
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Discrete Wavelet Transform (DWT) Assisted Partial Least Square (PLS) Analysis of Excitation-Emission Matrix Fluorescence (EEMF) Spectroscopic Data Sets: Improving the Quantification Accuracy of EEMF Technique
摘要： In the present work, it is shown that quantitative estimation efficiency of the partial least square (PLS) calibration model can be significantly improved by pre-processing the EEMF with discrete wavelet transform (DWT) analysis. The application of DWT essentially reduces the volume of data sets retaining all the analytically relevant information that subsequently helps in establishing a better correlation between the spectral and concentration data matrices. The utility of the proposed approach is successfully validated by analyzing the dilute aqueous mixtures of four fluorophores having significant spectral overlap with each other. The analytical procedure developed in the present study could be useful for analyzing the environmental, agricultural, and biological samples containing the fluorescent molecules at low concentration levels.
关键词： Partial least square analysis,Discrete wavelet analysis,Fluorophores,Wavelet analysis,Excitation-emission matrix fluorescence
更新于2025-09-09 09:28:46
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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - SPECT Reconstruction and Analysis for the Inspection of Spent Nuclear Fuel
摘要： A gamma-emission-tomography (GET) system for the inspection of spent nuclear fuel (SNF) has been developed and tested on multiple fuel types. This tool can be used for verification of the integrity of an assembly and consistency with fissile-material content. Parallel-beam line integrals are measured by a discrete array of CdZnTe detectors that view the fuel through a 1.5mm wide by 100mm thick tungsten collimator. Detectors and electronics are on a rotating platform within a watertight stainless steel torus. During operation, the system is underwater and fuel is lowered through the center of the torus and held stationary as data are collected. Tomographic data collection requires a time on the order of minutes. In field experiments, data with count rates in the range of 50kcps to >500kcps per pixel have been recorded. In the reconstructed images, missing or replaced pins in all assembly types can be visually discriminated in the lattice of fuel pins. Automated detection of missing/replaced pins is the metric used for determination of optimal processing steps. Effectiveness of reconstruction and data-processing tools is measured by a tools ability to improve performance on the pin-discrimination task. This paper describes the data preprocessing, image reconstruction, image analysis, and performance evaluation of this system.
关键词： gamma-ray emission tomography,image quality metrics,safeguards,attenuation correction,image reconstruction,spent nuclear fuel
更新于2025-09-09 09:28:46