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[IEEE 2018 7th International Conference on Computer and Communication Engineering (ICCCE) - Kuala Lumpur, Malaysia (2018.9.19-2018.9.20)] 2018 7th International Conference on Computer and Communication Engineering (ICCCE) - CPW-Fed Patch Antenna with Reflecting Metasurface Covering for WLAN and WiMAX Applications
摘要： A coplanar waveguide (CPW)-fed multiband patch antenna with the integration reflecting metasurface covering has been designed and performance characteristics are critically analyzed. The proposed low profile antenna can offers the wireless communications services for WLAN and WiMAX applications. The rectangular shaped patch antenna consists of pair of C-, L- and splitted-T shape slotted radiator, and 2D reflective metasurface covering at the back of patch which is separated by dielectric layer of substrate. The details of the antenna design structure and performance criteria are discussed through numerical simulation using full-wave electromagnetic simulator. The simulation results shows that by employing the reflecting metasurface covering, the -10dB impedance bandwidth has considerably increased than the typical CPW-fed patch antenna: from 440 MHz to 570 MHz (29%), 390 MHz to 480 MHz (23%) and 900 MHz to 1060 MHz (18%) for three different operating bands centered at 2.5, 3.5 and 5.5 GHz respectively. The simulated result shows the antenna with RMC integration achieves peak gain of 6.56 dBi, 6.43 dBi and 6.97 dBi with average gain of 6.45 dBi, 6.27 dBi and 6.82 dBi at three operating bands respectively which are higher than the typical patch antenna.
关键词： patch antenna,low-profile,reflecting metasurface covering,CPW-fed,WiMAX/WLAN Applications,radiation pattern improvement
更新于2025-09-23 15:21:21
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Design and Implementation of Distributed Ultra-High Temperature Sensing System With a Single Crystal Fiber
摘要： Modern high-temperature processes, such as fossil energy production, nuclear reactors, and chemical reactors lack robust, distributed sensing systems to map temperatures in these high-value harsh-environment systems. Regular silica-fiber-based distributed temperature sensing systems usually only operate at temperatures below about 800 °C. In this paper, we present the design, implementation, and testing of a distributed ultra-high temperature sensing system using Raman scattering intensity, which operates from room temperature to above 1400 °C. Consideration is given to the impacts of thermal radiation, fluorescence, and the multimode nature of unclad single-crystal fiber to optimize the system. Results from picosecond and sub-nanosecond lasers were compared. Measurements were taken with a ～2 m sapphire optical fiber, which represents the longest commercially available length. A spatial resolution of 12.4 cm and position standard deviation of 0.28 mm were achieved up to the maximum testing temperature of 1400 °C, which is a new record for distributed temperature sensing systems.
关键词： Raman scattering,optical fiber applications,high-temperature,Crystals,time-domain analysis
更新于2025-09-23 15:21:21
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302?W triple-frequency, single-mode, linearly polarized Yb-doped all-fiber amplifier
摘要： Stimulated Brillouin scattering (SBS) effect is currently the major limitation for the power scaling of single-frequency/narrow linewidth fiber laser systems. A single-mode linearly polarized all-fiber amplifier system is set up to investigate SBS effect in triple-frequency high-power amplifiers. With this amplifier, up to 302 W output power with 83% slope efficiency is achieved and the SBS threshold is scaled up to 12 dB. To the best of our knowledge, this is the highest output power of multifrequency laser from a single-mode polarization maintaining fiber. Good spectral properties and high brightness make this laser source available for the application of second harmonic generation, coherent beam combining.
关键词： nonlinear optics,fiber laser and applications
更新于2025-09-23 15:21:21
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ZnO/Ag NANOPARTICLE-DECORATED SINGLE-WALLED CARBON NANOTUBES (SWCNTs) AND THEIR PROPERTIES
摘要： Raw single-walled carbon nanotubes (SWCNTs) were oxidized by using sulfuric acid and nitric acid at 3:1 ratio to produce oxygen functional groups attached to SWCNTs surfaces. Then, the oxidized SWCNTs are coated with zinc oxide and silver nanoparticles by chemical precipitation route to synthesize ZnO/Ag-SWCNTs nanocomposite material. The nanocomposite sample was analyzed via zeta potential analyzer, ultraviolet-visible (UV-Vis) spectrophotometer, ˉeld emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), X-ray di?raction (XRD), and Raman spectroscopy to investigate colloidal stability, optical, morphological, and structural properties. The SWCNT properties were found to be changed after the addition of ZnO/Ag nanoparticles. Hence, the new ZnO/Ag-SWCNTs nanocomposite is a good candidate for photocatalyst applications and biological applications.
关键词： biological applications,photocatalyst applications,Single-walled carbon nanotubes (SWCNTs),ZnO/Ag nanocomposite,chemical precipitation
更新于2025-09-23 15:21:01
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The effects of growth TiO <sub/>2</sub> nanotubes on forged Ti <sub/>6</sub> Al <sub/>4</sub> V alloy and selectivelaser sintered Ti <sub/>6</sub> Al <sub/>4</sub> V alloy surfaces for environment and medical applications
摘要： The paper describes the effect of growth TiO2 nanotubes on titanium surfaces by anodic oxidation for environmental and medical applications. The importance of the metallurgical state of TiAl6V alloy on the growing of TiO2 nanotubes by anodization will be highlighted. Starting from the possibility of obtaining the TiO2 nanotubes, the paper presents results on TiO2 nanotubes grown by electrochemical anodization method, using a solution containing HF 0,4% and having as electrodes, graphite as cathode and titanium alloy specimens obtained by two technologies: by cold plastic deformation as well as by additive manufacturing process SLS, as anode. So, the nanotubes were produced by anodization and analysed by scanning electron microscopy. The aim of this paper is to compare the electrochemical formation of TiO2 on the surface of both specimens knowing that the titanium alloys and its oxides are used in many biomedical and environmental applications, thus providing the importance of nanotubes and the fact that their properties open doors in these fields.
关键词： medical applications,TiO2 nanotubes,environmental applications,anodic oxidation,Ti6Al4V alloy
更新于2025-09-23 15:21:01
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Suppression of amplitude modulation induced by polarization mode dispersion using a multi-degree-of-freedom fiber filter
摘要： Polarization mode dispersion (PMD) in ?bers for high-power lasers can induce signi?cant frequency modulation to amplitude modulation (FM-to-AM) conversion. However, existing techniques are not suf?ciently ?exible to achieve ef?cient compensation for such FM-to-AM conversion. By analyzing the nonuniform transmission spectrum caused by PMD, we found that the large-scale envelope of the transmission spectrum has more serious impacts on the amount of AM. In order to suppress the PMD-induced FM-to-AM conversion, we propose a novel tunable spectral ?lter with multiple degrees of freedom based on a half-wave plate, a nematic liquid crystal, and an axis-rotated polarization-maintaining ?ber. Peak wavelength, free spectral range (FSR), and modulation depth of the ?lter are decoupled and can be controlled independently, which is veri?ed through both simulations and experiments. The ?lter is utilized to compensate for the PMD-induced FM-to-AM conversion in the front end of a high-power laser facility. The results indicate that, for a pulse with phase-modulation frequency of 22.82 GHz, the FM-to-AM conversion could be reduced from 18% to 3.2% within a short time and maintained below 6.5% for 3 h. The proposed ?lter is also promising for other applications that require ?exible spectral control such as high-speed channel selection in optical communication networks.
关键词： laser facility,laser systems,optimization,high-power laser,laser facility and engineering,advanced laser technology and applications,?ber laser and applications,modeling,design
更新于2025-09-23 15:21:01
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Mixed-Cation Mixed-Metal Halide Perovskites for Photovoltaic Applications: A Theoretical Study
摘要： Perovskite solar cells based on multiple cations have shown excellent optoelectronic properties with high power conversion efficiency. Herein, the structural, electronic, and optical properties of mixed-cation mixed-metal perovskites MA1?xCsxPb0.25Sn0.75I3 were studied by employing the first-principles calculations for the first time. Our calculated results reveal that these perovskite materials possess direct band gaps in the range of 1.0?1.3 eV. Moreover, these compounds show excellent photovoltaic performance in terms of strong optical absorption coefficients compared with MAPbI3. Particularly, they also exhibit good structural stability and decrement of lead content. These results demonstrated that mixed-cation mixed-metal perovskites may be potential candidates for high-efficiency light-absorbing materials.
关键词： mixed-cation mixed-metal perovskites,electronic properties,optical properties,first-principles calculations,photovoltaic applications,structural stability
更新于2025-09-23 15:21:01
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Formation of stable 2D methylammonium antimony iodide phase for lead-free perovskite-like solar cells
摘要： The presence of lead in novel hybrid perovskite-based solar cells remains a significant issue regarding commercial applications. Therefore, antimony-based perovskite-like A3M2X9 structures are promising new candidates for low toxicity photovoltaic applications. So far, MA3Sb2I9 was reported to only crystallize in the ‘zero-dimensional’ (0D) dimer structure with wide indirect bandgap properties. However, the formation of the 2D layered polymorph is more suitable for solar cell applications due to its expected direct and narrow bandgap. Here, we demonstrate the first synthesis of phase pure 2D layered MA3Sb2I9, based on antimony acetate dissolved in alcoholic solvents. Using in situ XRD methods, we confirm the stability of the layered phase towards high temperature, but the exposure to 75 % relative humidity for several hours leads to a rearrangement of the phase with partial formation of the 0D structure. We investigated the electronic band structure and confirmed experimentally the presence of a semi-direct bandgap at around 2.1 eV. Our work shows that careful control of nucleation via processing conditions can provide access to promising perovskite-like phases for photovoltaic applications.
关键词： antimony,perovskite solar cells,2D materials,lead-free,photovoltaic applications
更新于2025-09-23 15:21:01
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Profound optical analysis for novel amorphous Cu2FeSnS4 thin films as an absorber layer for thin film solar cells
摘要： In this study, quaternary kesterite Cu2FeSnS4 (CFTS4) has been selected due to its interesting optical and electrical characteristics. The CFTS4 films were prepared by exploiting the chemical bath deposition process at room temperature. The films were prepared at different deposition periods (1, 3, 5 and 7 h). The EDAX technique was helped in evaluating the compositional element ratio which near to 2:1:1:4. The morphology and structure of CFTS4 films have been examined by utilizing X-ray diffraction, and field emission scanning electron microscope techniques. XRD charts revealed the absence of sharp peaks and approved the amorphous nature of films under investigations. The transmittance and reflectance data were employed to compute the linear and nonlinear optical constants of the as-deposited CFTS4 films. The energy gap calculations for the CFTS4 films grown on glass substrate displayed a direct energy gap and by increasing the deposition time, a reduction in energy gap values from 1.41 to 1.19 eV was obtained. The deep analysis of linear/nonlinear optical properties as a function of deposition time has revealed many characteristics of the investigated films. Moreover, the nonlinear parameters (refractive index n2, nonlinear absorption coefficient βc and the third-order nonlinear optical susceptibility χ(3)) of the CFTS4 films were boosted with rising up the film thickness and their high values imply the possibility of utilizing these films in various optoelectronic applications.
关键词： Optical conductivity,Energy gap,Optoelectronic applications,Chemical bath deposition technique,CFTS4 thin films
更新于2025-09-23 15:21:01
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Nickel doped TiO <sub/>2</sub> films by a modified laser plasma source for photocatalytic applications
摘要： We reports a study on pure and Ni-doped TiO2 thin ?lms produced via laser ablation technique. The novelty of the work consists that both synthesis and doping were carried out in a single process, using a modi?ed laser ion source to simultaneously make pulsed laser deposition (PLD) and low-energy ion implantation (by post-acceleration method). In particular, two titania ?lms were synthesized via PLD starting from a rutile target. One of the two ?lms was doped with Ni ions, accelerated with a voltage of 20 kV. The total implanted dose, evaluated by a Faraday cup, resulted to be 1 × 1014 ions/cm2. The crystalline phase of the obtained TiO2 ?lms was analysed by Raman spectroscopy. A higher photocatalytic activity, measured under UV irradiation using methylene blue, was estimated for the Ni-doped titania ?lm with respect the pure one.
关键词： Plasma generation (laser-produced, RF, x ray-produced),Accelerator Applications,Plasma diagnostics - probes
更新于2025-09-23 15:21:01