- 标题
- 摘要
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- 实验方案
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Extraction of rare earth oxides from discarded compact fluorescent lamps
摘要： Discarded CFL samples are evaluated as a potential source of REEs (Y, Eu, Ce, Tb). The phosphors powder obtained from mechanical separation contains 31% rare earth values. The quantitative XRD analysis of phosphor sample yielded 39.9% red (YOX: Y1.90Eu0.10O3), 14.6% green (CAT: Al11Ce0.67MgO19Tb0.33), and 21.4% blue (BAM: Al10.09Ba0.96Mg0.91O17: Eu2+) phosphor along with 14.1% silica. Planetary ball milling was found promising in the liberation of REEs from given phosphor sample. A short milling of 20–30 min and 3–4 M acid concentration was found adequate for optimal recovery (> 90%) of REEs. Calcination of the precipitates resulted in the formation of REO with Y-Eu purity of > 98% and > 90% recovery rate. Eu, Y phase dissolution behavior was found completely different than Ce, Tb phase due to inert nature of Al11Ce0.67MgO19Tb0.33 till 120 min milling and 6 M acid concentration in leaching. Excessive milling promotes overall dissolution along with impurities dissolution and which further restrict the precipitation process. Based on the complete material balance 13 g of a mixed oxide of Y and Eu can be obtained from 100 units of CFLs.
关键词： Discarded CFL,Phosphor,Rare earth elements,Leaching,Mechanical milling
更新于2025-11-21 11:18:25
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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - A Low-Profile Dual-Polarized Patch Antenna with Bandwidth Enhanced by Stacked Parasitic Elements
摘要： In this paper, a low-profile dual-linear polarized patch antenna composed of two stacked substrates, one air gap layer, and one grounded substrate is proposed. There is a feeding patch element with two excited probes placed on the top side of the grounded substrate, and one parasitic patch element and a 2×2 parasitic array patch elements printed on the lower and upper stacked substrate, respectively. The T- and rectangular slots and T-stubs are employed on/near the orthogonal axis of the patches for the impedance matching and two orthogonal polarizations improvement. Furthermore, four stacked complementary split-ring resonators (CSRRs) are loaded in the two stacked substrates mainly to adjust the impedance matching and port isolation with an induced dual-polarized resonance. Thanks to the stacked patches and CSRRs, an enhanced impedance bandwidth from 1.2% to 7.4% was achieved by the introduced three additional dual-polarized resonances. Simulated results show the antenna has a impedance bandwidth across 2.362-2.544 GHz (fractional bandwidth 7.4%), a maximum realized gain of 10 dBi, and port isolation better than 22 dB over the operational bandwidth. In addition, a low profile of 0.048λ0 (where λ0 is the free-space wavelength at the central frequency) is maintained in the proposed antenna.
关键词： Dual-polarized,stacked parasitic elements,low-profile,multilayer patch antenna
更新于2025-09-23 15:23:52
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Atomically precise expansion of unsaturated silicon clusters
摘要： Small- to medium-sized clusters occur in various areas of chemistry, e.g. as active species of heterogeneous catalysis or transient intermediates during chemical vapor deposition. The manipulation of stable representatives is mostly limited to the ligand periphery, virtually excluding the systematic variation of the property-determining cluster scaffold. We now report the deliberate expansion of a stable unsaturated silicon cluster from six to seven and finally eight vertices. The consecutive application of lithium/naphthalene as reducing agent and decamethylsilicocene as electrophilic source of silicon results in the expansion of the core by precisely one atom with the potential of infinite repetition.
关键词： silicon,cluster compounds,main group elements,subvalent compounds,anions
更新于2025-09-23 15:23:52
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Graphene electrode diagnostic with IR imaging of Joule heat emission
摘要： Conductive graphene electrode of large area is required for some applications like for example photovoltaics or touch screens. Such large area graphene membrane needs specific test methods to assess defects which may obstacle its performance. In this work the infrared imaging of Joule heated graphene was proposed to estimate its uniformity and mechanical continuity. Thermal signatures of the typical mechanical defects like scratches and local resistivity inhomogeneity were identified. Distribution of the heat emission around such defects were simulated using finite elements method and then experimentally verified by recording of thermal landscape around the corresponding real graphene defects. Proposed method gives micrometric resolution and ability to inspection of large area electrodes depending on applied optics. Presented results give suggestions how graphene imperfections generate observed hot points related to graphene layer defects.
关键词： Finite elements,Joule heat,Defect,Graphene,Infrared
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) - Kiev (2018.7.2-2018.7.5)] 2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) - Referencing of U A V Images Using the Nelder-Mead Method
摘要： The paper analyses the existing methods of images coordinate referencing using approximating functions and the classical methods for restoring elements of external orientation. It reveals that those methods do not take into account the peculiarities of the images received from unmanned aerial vehicles. The paper investigates the possibility of using Nelder-Mead simplex method instead. To define the elements of external orientation the angles of external orientation were taken for the independent variables. The spatial position was calculated on the basis of angles and given reference points.
关键词： elements of external orientation,Nelder-Mead simplex algorithm,Images coordinate referencing,approximating functions,triangulation net
更新于2025-09-23 15:23:52
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Defect formation of CuI-doped by group-IIB elements
摘要： First-principles calculations have been performed to investigate the doping defects in CuI with group-IIB elements such as Zn, Cd and Hg. The calculated transition energies for substitutional Zn, Cd and Hg are 1.32, 1.28 and 0.60 eV, respectively. These group-IIB elements at the substitutional sites complex with a copper vacancy (VCu) have the lower formation energies as compared to dopants located at the substitutional sites or interstitial sites, respectively. Among all the complex defects considered, [HgCu + VCu] has the lowest formation energy and it induces the acceptor level ε(0/?) = 0.18 eV above the valence-band maximum (VBM), which is close to the acceptor level ε(0/?) = 0.1 eV of VCu, suggesting that Hg may be a good dopant for CuI to improve its p-type conductivity.
关键词： group-IIB elements,defects formation,first-principles calculation,Semiconductor
更新于2025-09-23 15:23:52
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Faulty elements diagnosis of phased array antennas using a generative adversarial learning-based stacked denoising sparse autoencoder
摘要： Diagnosis of faulty elements in a linear phased array antenna is of great importance in the wireless communication field which has been received increasing attention. As a result of element or elements failure in the linear phased array antennas, the whole radiation pattern will suffer from high side lobe levels, wide bandwidth and unexpected nulls. To this end, we suggest a novel approach by combining the generative adversarial learning and the stacked denoising sparse autoencoder to determine the location of the faulty elements in antennas. The suggested approach can learn discriminative features from radiation pattern images adaptively and automatically with less expert knowledge. Meanwhile, the suggested approach is able to overcome the strong noise, the high dimensional size of the radiation pattern and the small fault samples. In this regard, the suggested approach possesses superiority in discriminant capability in contrast to the existing related approaches.
关键词： stacked denoising sparse autoencoder,phased array antennas,Faulty elements diagnosis,generative adversarial learning
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 7th International Conference on Photonics (ICP) - Kuah (2018.4.9-2018.4.11)] 2018 IEEE 7th International Conference on Photonics (ICP) - Passive Element Fault Analysis at the Last Mile of the FTTH Network in Malaysia
摘要： The optical transceiver performance for GPON FTTH (OLTTx and ONURx) for 300 live subscribers at legacy area has been monitored hourly for a duration of four months. The optical performance is then plotted against its faults due to the passive element at the last mile of the GPON FTTH network. The results show that the fault rate for aerial type of fiber distribution (FDP) is higher (1.3%) than building, street cabinet and underground FDP types. More than 65% of the faults are contributed by optical fibers (drop fibers) and the rest is due to fiber connectors. The optical power received (ONURx) spectrum shows three types of patterns before disconnection; sudden disconnection, fluctuation and degradation of ONURx. This study provides preliminary information necessary for developing the passive element fault prediction for GPON FTTH at the last mile of the network.
关键词： link loss,GPON FTTH network,optical transmit power: receive power,optical fiber,signals degradation,passive elements
更新于2025-09-23 15:22:29
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Silver nanoflowers-enhanced Tb(III)/La(III) co-luminescence for the sensitive detection of dopamine
摘要： A sensitive fluorescent analytical method for the detection of dopamine (DA) was developed based on surface-enhanced Tb(III)/La(III) co-luminescence using silver nanoflowers (AgNFs). Anisotropic AgNFs show strong surface-enhanced fluorescence effect owing to the abundant sharp tips. Tb(III)/La(III)-DA complexes mainly bind to the sharp tips of AgNFs and thus shorten the distance between the complexes. The shortened distance gives rise to obvious surface-enhanced Tb(III)/La(III) co-luminescence effect. In this work, AgNFs offer many superior properties, such as enhanced intrinsic green fluorescence of Tb(III) (λex/λem = 310/546 nm), increased fluorescence lifetime, and improved energy transfer efficiency. Under the optimum conditions, the fluorescence intensity is linearly correlated with the concentration of DA in the range of 0.80–10 nM (R2 = 0.9970), and the detection limit is 0.34 nM (S/N = 3). The fluorescent nanoprobe was successfully applied to the determination of DA in human serum samples with recoveries ranging from 99.1 to 102.6%.
关键词： Co-luminescence,Anisotropic nanoparticles,Surface-enhanced fluorescence,Rare earth elements,Dopamine,Silver nanoflowers
更新于2025-09-23 15:22:29
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High-frequency behaviour of corner singularities in Helmholtz problems
摘要： We analyze the singular behaviour of the Helmholtz equation set in a non-convex polygon. Classically, the solution of the problem is split into a regular part and one singular function for each re-entrant corner. The originality of our work is that the “amplitude” of the singular parts is bounded explicitly in terms of frequency. We show that for high frequency problems, the “dominant” part of the solution is the regular part. As an application, we derive sharp error estimates for finite element discretizations. These error estimates show that the “pollution effect” is not changed by the presence of singularities. Furthermore, a consequence of our theory is that locally refined meshes are not needed for high-frequency problems, unless a very accurate solution is required. These results are illustrated with numerical examples that are in accordance with the developed theory.
关键词： Helmholtz problems,pollution effect,corner singularities,finite elements
更新于2025-09-23 15:22:29