- 标题
- 摘要
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- 实验方案
- 产品
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Poly(vinylidene fluoride)-based nanocomposite employing oriented Bi2S3 nanorods with double-shell structure for high dielectric performance and loss suppression
摘要： For polymer-based nanocomposites, designing the nanostructures of fillers, their distribution inside matrix as well as interfaces with the polymer is of crucial importance to achieve high dielectric performances. One-dimensional semiconductor Bi2S3 nanorods coated with homogeneous SiO2 and polydopamine (PDA) double shell layers were imported into the poly(vinylidene fluoride) (PVDF) with parallel arrangement via uniaxial stretching to form Bi2S3@SiO2@PDA/PVDF nanocomposite. The dielectric performances of oriented Bi2S3@SiO2@PDA/PVDF were studied in comparison with its counterparts employing Bi2S3 fillers without shell layers or alignment. A microcapacitor model was used to accurately estimate the dielectric constant along perpendicular direction. Coating conductive Bi2S3 nanorods with insulating SiO2@PDA double layer remarkably reduces the dielectric loss of the nanocomposite, while alignment of one-dimensional Bi2S3@SiO2@PDA nanorods endows electrical properties anisotropy, which was understood from J-V curves measured along two directions and moreover, via three-dimensional finite element analysis, unambiguously revealing the effects of aligned core-shell structured fillers on local electric field and current density distribution. This study provides a promising and facile approach for designing high performance dielectrics.
关键词： Polymer-matrix composites,Anisotropy,Numerical simulation,Dielectric performances,Ordered structure,Core-shell structure
更新于2025-09-04 15:30:14
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The Role of the Effect of Shadowing of Some Wavy Regions by Other Wavy Regions in the Formation of an Image of Snell’s Window
摘要： The shadowing of some regions of a wavy water surface by other regions can significantly influence the backscattered signal not only in the problem of remote monitoring of a water reservoir at grazing angles (e.g., in radar), but also in the problems of underwater vision. In this work, we present the results of a theoretical study of this phenomenon with respect to the model of underwater imaging of the sky (Snell’s window) near the image boundary. The numerical-simulation method is used to develop the statistically mean image of Snell’s window, which allows for the shadowing effects, and the corrected formula of the estimate of a wave parameter, namely, the water-surface slope variance, is obtained using the value of blurring of the boundary of Snell’s window.
关键词： underwater vision,wavy water surface,shadowing,numerical simulation,Snell’s window
更新于2025-09-04 15:30:14
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5?W 1952?nm Brillouin-free efficient single clad TDFA
摘要： We report the performance of a two stage single clad (SC) Thulium-doped fiber amplifier (TDFA), delivering an output power of 5 W at 1952 nm without stimulated Brillouin scattering (SBS) for a single-frequency input signal. A slope efficiency greater than 60%, a signal gain greater than 60 dB and an input dynamic range > 30 dB were achieved. The amplifier topology was optimized with a simulation tool, experimental results and simulations are in good agreement.
关键词： Multistage,Single-frequency,Brillouin,Single clad,Fiber amplifier,Simulation,Thulium
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Increased reliability of outdoor millimeter-wave link simulations by leveraging lidar point cloud
摘要： Exploitation of the millimeter-wave (mmWave) band for both the small-cell radio access (RAN) and in-street backhauling must contribute to strongly increase the capacity of next-generation outdoor wireless networks. Beside the numerous technological challenges faced by the equipment manufacturers, the definition of practical deployment requirements and elaboration of efficient network design procedures are key issues for future network providers and the refinement of business models. The work reported in the present paper is part of research activity on small-cell and wireless backhaul design methodologies. The authors analyze how digital geographical data and radio propagation models may be enhanced and tailored to answer new mmWave simulation requirements. Three different propagation methods are compared in an urban 60 GHz scenario: based on free building database, traditional high-resolution map data, or Lidar point cloud. The advantage of the multi-paths prediction versus direct-path is also investigated, using the Lidar point cloud as a simulation input.
关键词： millimeter-wave propagation,Lidar point cloud,simulation
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE ANDESCON - Santiago de Cali, Colombia (2018.8.22-2018.8.24)] 2018 IEEE ANDESCON - Solar Energy Supply for the Rural Parish GAD's of Ecuador
摘要： In the present article a design of a photovoltaic solar system will be made for the electric power supply in the 790 GAD's Parish facilities of Ecuador, the designed system will start working when the connection to the public network or by unforeseen cuts of electric power, a situation that is very recurrent in rural areas of Ecuador and through this system the continuity of the service to the inhabitants of the corresponding jurisdiction is guaranteed. It is a very interesting purpose since the National Government should promote this type of initiatives in a medium term, due to the change of the productive matrix in correspondence with the National Plan a Lifetime and the Constitution of the Republic of Ecuador of 2009 where the State considers electric power services as a basic service.
关键词： Parish GAD,simulation,renewable energy,productive matrix,COOTAD,rural electrification,good living
更新于2025-09-04 15:30:14
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SOI Thin Microdosimeter Detectors for Low Energy Ions and Radiation Damage Studies
摘要： The responses of two silicon on insulator (SOI) 3D microdosimeters developed by the Centre for Medical Radiation Physics (CMRP) were investigated with a range of different low energy ions, with high linear energy transfer (LET). The two microdosimeters n-SOI and p-SOI were able to measure the LET of different ions including 7Li, 12C, 16O and 48Ti with ranges below 350 μm in silicon. No plasma effects were seen in the SOI microdosimeters when irradiated with the high LET ions. A Monte Carlo simulation using Geant4 was compared to the experimental measurements, whereby some discrepancies were observed for heavier ions at lower energies. This discrepancy can be partly attributed to uncertainties in the thickness of the energy degraders and overlayers of the devices. The microdosimetric measurements of low energy 16O ions were obtained and compared to a therapeutic 16O ion beam. The radiation hardness of the two devices was studied using the Ion Beam Induced Charge Collection technique (IBIC). Both types of microdosimeters when biased had no essential changes in charge collection efficiency (CCE) in the SV after irradiation with low energy ions.
关键词： LET,radiation damage,SOI microdosimeters,Geant4 simulation,low energy ions,IBIC
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Hybrid simulations with measurements as improved technique to obtain the complex antenna responses on structures
摘要： With the growth of multiple antenna systems (SIMO, MIMO), the knowledge of the complex antenna responses have to be obtained with a good accuracy to be used in the vector signal processing step. However these responses may depend on the structure where antennas are integrated. Furthermore, these structures completely change between terrestrial, naval or aerial applications. Actual techniques to obtain antenna responses are mainly based on measurements and are often limited or complex in the case of integration over a non-trivial structure (building, vehicle, plane, boat …). An emergent technique is to hybridized measurements and simulations to obtain the desired accurate data.
关键词： measurement,simulation,antenna complex responses,refit,radiation pattern,hybridization
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Towards Performance Optimisation of the FDTD Method via Matrix Casting Approach
摘要： This publication presents matrix casting approach for the FDTD method. Applied in 2D and 3D dimensions it is subsequently parallelised with OpenMP and tested in basic air-filled and realistic landmine-detection scenarios.
关键词： performance analysis,finite difference methods,numerical simulation,electromagnetic propagation
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Lens Antennas Focus Determination Using Full-Wave Simulation
摘要： The determination of the focal length in lens antennas is usually difficult. This work applies the potential of a code used for the implementation of a full-wave, two-dimensional (2D) electromagnetic simulator based on the method of moments (MoM), which allows solving in very short time electromagnetic scattering problems using the two-dimensional (2D) Lippmann-Schwinger equation [1-3]. The results obtained with this code of hyperbolic lenses and biconvex lenses allow determining the location of the focus and comparing them with theoretical analytical results.
关键词： focusing,lens,millimeter-wave antennas,simulation
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Efficient Uncertainty Evaluation of Vector Network Analyser Measurements Using Two-Tier Bayesian Analysis and Monte Carlo Method
摘要： Antennas are a key element in any communication system and vector network analyser (VNA) is popular tool for charactering antenna impedance bandwidth. In this paper, an efficient uncertainty evaluation method is proposed for VNA measurement based on its uncertainty propagation mechanism using Bayesian analysis and Monte Carlo method. The proposed method is generic and can be applied to VNA with arbitrary number of ports. In order to obtain the complete information of measurement uncertainty distribution, a two-tier Bayesian analytic process is carried out. The proposed method contains three steps. In the first step, the posterior distribution of each uncertainty source of VNA calibrations is deduced by the use of prior and current sample information through the first-tier Bayesian analysis. In the second step, the obtained posterior distributions of uncertainty sources are taken into the Monte Carlo simulation of one-port VNA measurement uncertainties. In the last step, the results obtained in the second step are used as the prior distribution of the secondary Bayesian evaluation, then the evaluation results of the measurement uncertainty can be obtained with the means, variances and skewness of the probabilistic distribution. The numerical analysis using an antenna measurement results demonstrate the high-efficiency and reliability of this proposed method.
关键词： Bayesian analysis,VNA,uncertainty,Monte Carlo simulation,measurement
更新于2025-09-04 15:30:14