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Fabrication and performance of Lu2O3:Eu3+ nanowire arrays with different nanowire diameters
摘要： Lu2O3:Eu3+ nanowire arrays with different nanowire diameters were successfully fabricated by sol-gel process using submicron porous anodic aluminum oxide (AAO) templates. The nanowires in each array are homogeneous and highly ordered, and have uniform diameter defined by the template. They exhibit polycrystalline with Lu2O3 cubic structure. The crystallite sizes of the Lu2O3:Eu3+ nanowires increase with the increase of the pore diameters of AAO templates and are less than that of nanopowder prepared in the same conditions due to the confinement of AAO template on the coalescence of Lu2O3:Eu3+ nanocrystallites. The Lu2O3:Eu3+ nanowire arrays within AAO templates exhibit good performances of photoluminescence and X-ray excited optical luminescence. The emission peaks can be ascribed to 5D0→7FJ transitions of Eu3+ (J = 0, 1, 2, 3). The luminescent intensities of the Lu2O3:Eu3+ nanowire arrays also enhance with the increase of the pore diameters of AAO templates. This phenomenon is not only due to the increase of the filling ratio of Lu2O3:Eu3+, but also relates to the improvement of crystallinity. The latter mechanism is further confirmed by the fluorescent decay times of Eu3+ emission in the nanowires with different diameters. It is believed that the Lu2O3:Eu3+ nanowire array can become a promising high-spatial-resolution scintillation screen used in X-ray imaging.
关键词： Lu2O3:Eu3+ nanowire array,Diameter and crystallinity,Luminescence,AAO template and sol-gel method
更新于2025-09-23 15:21:21
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Zinc oxide array/polyurethane nanocomposite coating: Fabrication, characterization and corrosion resistance
摘要： Novel zinc oxide (ZnO) array/polyurethane (PU) nanocomposite coatings on the stainless steel substrates was fabricated via a simple process. ZnO arrays were prepared using zinc nitrate and hexamethylenetetramine by a seed growth method, followed by the spinning of PU. The morphologies, structure, wettability, mechanical performance and infrared radiation properties were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, surface contact angle, nano indentation and infrared radiation tests. The corrosion properties of the ZnO array/PU nanocomposite coating were evaluated by the electrochemical tests. The results showed that the ZnO arrays were hexagonal wurtzite and well dispersed in the composite coatings, resulting in slight increase in hydrophilicity. The mechanical properties of the coatings were improved with increased content of the ZnO arrays. The as-prepared ZnO array/PU nanocomposite coatings exhibited excellent corrosion resistance. The infrared radiation performance was observed to be slightly improved as well. It is believed that the unique organic/inorganic nanocomposite coating offers the effective strategy and potential applications for designing the functional coatings of good corrosion resistance and mechanical properties in various polymer systems.
关键词： PU,Composite,Corrosion,ZnO array
更新于2025-09-23 15:21:21
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Use of a commercial ion chamber detector array for the measurement of high spatial-resolution photon beam profiles
摘要： Linear accelerator (linac) commissioning and quality assurance measurements are time‐consuming tasks that often require a water tank scanning system to acquire pro?le scans for full characterization of dosimetric beam properties. To increase ef?ciency, a method is demonstrated to acquire variable resolution, photon beam pro?le data using a commercially available ion chamber array (0.5 cm detector spacing). Field sizes of 2 × 2, 5 × 5, 10 × 10, and 15 × 15 cm2 were acquired at depths in solid water of dmax, 5 cm, and 10 cm; additionally, beam pro?les for ?eld sizes of 25 × 25 and 40 × 40 cm2 were acquired at 5 cm depth in solid water at x‐ray energies of 6 and 23 MV. 1D composite pro?les were generated by combining discrete point measurements made at multiple couch positions. The 1D composite pro?le dataset was evaluated against a commissioning dataset acquired with a 3D water tank scan system utilizing (a) 0.125 cc ion chamber for 5 × 5, 10 × 10, 15 × 15, 25 × 25, and 40 × 40 ?eld sizes and (b) a solid state detector for 2 × 2 cm2 ?eld size. The two datasets were compared to the gamma criteria at 1%/1 mm and 2%/2 mm tolerance. Almost all pass rates exceeded 95% at 2%/2 mm except for the 6 MV 2 × 2 cm2 ?eld size at dmax. Pass rates at 1%/1 mm ranged from 51% to 99%, with an average pass rate of 82%. A fourfold reduction in MU was achieved for scans larger than 15 × 15 cm2 using this method compared to the water tank scans. Further, dynamic wedge measurements acquired with the ion chamber array showed reasonable agreement with the treatment planning system. This method opens up new possibilities for rapid acquisition of variable resolution 2D–3D dosimetric data mitigating the need for acquiring all scan data with in‐water measurements.
关键词： photon beam pro?les,gamma analysis,quality assurance,ion chamber array
更新于2025-09-23 15:21:21
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Compact antipodal Vivaldi antenna with rectangular slots and shaping of flare to cover 6 to 18 GHz
摘要： The compact antipodal Vivaldi antenna (AVA) with regular rectangular slots in the taper region is presented in this paper intended for electronic warfare applications. The antenna has a simple configuration with compact size. Micro strip line feeding is employed. The rectangular slots at regular intervals and terminal elliptical shaping of taper on top and bottom layers of antenna substrate enhance impedance bandwidth. The slot loading in the taper portion also enhances the gain. The novel feature of this antenna is its small aperture size which is 25 mm. Small aperture size is required for array applications to avoid grating lobes and element pattern nulls. A return loss of less than ?10 dB (VSWR <2.0) is obtained over 6 to 18 GHz. The antenna is designed using Ansoft HFSS software and the same is implemented in hardware. Return loss, radiation patterns, and gain have been measured and results reported.
关键词： Electronic Warfare,Printed antennas,Array elements
更新于2025-09-23 15:21:21
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Filtering two-element waveguide antenna array based on solely resonators
摘要： This paper presents a design approach of a filtering antenna arrays based on the coupling matrix theory. The approach generates filtering functionality using the resonating array radiating elements and the resonator based feed network regardless to the physical structure. To implement the approach, a novel topology for a two-element array is presented, here three rectangular waveguide cavity resonators have been employed to form the filtering array. The array has a fractional bandwidth of 10% at the centre frequency 10 GHz with a reflection coefficient magnitude within the passband of 20 dB. The realised gain over the passband is 9.8 ± 0.4 dBi. The array has been fabricated and the measurements are in very good agreement with the simulations, validating the approach.
关键词： antenna array,filtering antenna array,coupling matrix,waveguide resonators
更新于2025-09-23 15:21:01
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Coupling between plasmonic nanohole array and nanorod arrays: the emerging of a new extraordinary optical transmission mode and epsilon-near-zero property
摘要： The compound Ag nanohole structures with an Ag nanorod in the middle of an Ag nanohole are investigated by finite-difference-time-domain calculations. The structure shows strong polarization-dependent optical properties. A new extraordinary optical transmission (EOT) mode is observed when the polarization direction is aligned with the long axis of the nanorods, and its resonance wavelength red-shifts exponentially with the nanorod length. Around this resonance wavelength, the real part of the effective permittivity also becomes zero, demonstrating the epsilon-near-zero (ENZ) property. The new EOT mode is found to be the result of the enhanced local radiation of the nanorods as well as the electromagnetic coupling to the nanoholes to produce the enhanced transmission. The tunable resonance wavelength, EOT, strong near-field enhancement, and ENZ properties make the structure ideal for many potential applications, such as ultrathin optical filter, polarizers, surface-enhanced spectroscopies, etc.
关键词： tunable transmission,epsilon-near-zero,nanohole array,extraordinary optical transmission,nanorod array
更新于2025-09-23 15:21:01
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Stereoselective Sensing of <scp>l</scp> - and <scp>d</scp> -Amino Acids: Development of a Fluorescence-Array Based on Readily Available Chiral Phosphoric Acids
摘要： A chiral sensor-array for the identification of amino-acids was developed, using six readily available bis- and tris-phosphoric acids in combination with Ni2 + and Eu3 +, resulting in a fluorescence-based array with twelve sensors. This array was successfully applied for the chemoselective identification of 19 amino-acids, but also for the enantioselective discrimination between the l- and d-enantiomers.
关键词： amino-acids,chiral sensor-array,fluorescence-based array,enantioselective discrimination,chemoselective identification
更新于2025-09-23 15:21:01
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The Design of Dual Circularly Polarized Series-Fed Arrays
摘要： This paper presents the design of dual circularly polarized (CP) series-fed arrays based on Sequential rotation (SR) technique with uniform radiation elements. The radiation elements and feeding network used in the array are uniform, which leads to the possibility of dual-CP radiation by series-fed SR arrays. Meanwhile, the elements radiate unequal powers due to this arrangement. The relationship between the axial ratio (AR) and four key parameters of the array is derived and thoroughly discussed. Good polarization purity and port isolation can be realized by optimizing these parameters. A dual-CP array working at 10 GHz is designed with the help of the analysis. Experimental results show that the proposed antenna has good properties.
关键词： Circularly polarized antenna,Series-Fed array,Sequential rotation,Dual circularly polarized,Antenna array,Axial ratio
更新于2025-09-23 15:21:01
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[IEEE 2020 7th International Conference on Signal Processing and Integrated Networks (SPIN) - Noida, India (2020.2.27-2020.2.28)] 2020 7th International Conference on Signal Processing and Integrated Networks (SPIN) - Active Power Filter for Harmonic Mitigation of Power Quality Issues in Grid Integrated Photovoltaic Generation System
摘要： Single phase tied with Photovoltaic arrangement (PV) employed on perturbed & observed (P&O) maximum energy point tracking technique with shunt active power filter allied to a rectifier feed R-L nonlinear load. The traditional Perturbed & Observed technique maximum energy point tracking topology is applied to attained maximum output power from Photovoltaic array(PVA), Proportional Integral conventional controller with phase detector (PLL) (PD) phase synchronization are executed to produce reference current. It provide at control unit of pulse width modulation topology( PWM) is utilized in inverter to get steady output voltage. Self supported DC bus PWM converter is regulated from PV array. In proposed architecture is minimized total harmonic pollution existing in supply current owing to power electronic load is (PEL). Total current harmonic pollution (THDi) factor obtain better than compensated using dynamic filter shunt active power filter (SAPF) and power compensation. Hence, reactive power (KVAR) is delivered through system decrease and active power (KW) enhance. The suggested scheme has been implemented by way of MATLAB/SIMULINK 2015(a) environment.
关键词： Pulse width Modulated (PWM) Converter,Proportional Integral controller,Maximum Power Point Tracking (P & O) Scheme,Shunt Active Power Filter (SAPF),Photovoltaic Array (PVA)
更新于2025-09-23 15:21:01
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Enhanced optical efficiency and color purity for organic light-emitting diodes by finely optimizing parameters of nanoscale low-refractive index grid
摘要： To extract the confined waveguided light in organic light-emitting diodes (OLEDs), inserting a low refractive index (RI) periodic structure between the anode and organic layer has been widely investigated as a promising technology. However, the periodic-structure-based light extraction applied inside devices has been shown to severely distort spectrum and affect EL characteristics. In this study, a simple light extraction technology using periodic low-RI nanodot array (NDA) as internal light extraction layer has been demonstrated. The NDA was fabricated simply via laser interference lithography (LIL). The structural parameters of periodic pattern, distance, and height were easily controlled by the LIL process. From computational analysis using finite-difference time-domain (FDTD) method, the NDA with 300 nm pitch and 0.3 coverage ratio per unit cell with 60 nm height showed the highest enhancement with spectral-distortion-minimized characteristics. Through both computational and experimental systematic analysis on the structural parameters of low-RI NDA-embedded OLEDs, highly efficient OLEDs have been fabricated. Finally, as representative indicators, hexagonal and rectangular positioned NDA-embedded OLEDs showed highly improved external quantum efficiencies of 2.44 (+29.55%) and 2.77 (+57.38%), respectively. Furthermore, the disadvantage originating from the nanoscale surface roughness on the transparent conductive oxide was minimized.
关键词： organic light-emitting diodes,nanodot array,FDTD simulation,laser interference lithography,light extraction,low refractive index
更新于2025-09-23 15:21:01