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- 摘要
- 关键词
- 实验方案
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[Institution of Engineering and Technology 8th Renewable Power Generation Conference (RPG 2019) - Shanghai, China (24-25 Oct. 2019)] 8th Renewable Power Generation Conference (RPG 2019) - The Method of Grid Disturbance Test for Very Large Capacity Photovoltaic Inverter Based on Hardware-In-Loop Simulation Platform
摘要： A three-dimensional (3-D) finite-difference time-domain (FDTD) algorithm is used in order to simulate ground penetrating radar (GPR) for landmine detection. Two bowtie GPR transducers are chosen for the simulations and two widely employed antipersonnel (AP) landmines, namely PMA-1 and PMN are used. The validity of the modeled antennas and landmines is tested through a comparison between numerical and laboratory measurements. The modeled AP landmines are buried in a realistically simulated soil. The geometrical characteristics of soil’s inhomogeneity are modeled using fractal correlated noise, which gives rise to Gaussian semivariograms often encountered in the field. Fractals are also employed in order to simulate the roughness of the soil’s surface. A frequency-dependent complex electrical permittivity model is used for the dielectric properties of the soil, which relates both the velocity and the attenuation of the electromagnetic waves with the soil’s bulk density, sand particles density, clay fraction, sand fraction, and volumetric water fraction. Debye functions are employed to simulate this complex electrical permittivity. Background features like vegetation and water puddles are also included in the models and it is shown that they can affect the performance of GPR at frequencies used for landmine detection (0.5–3 GHz). It is envisaged that this modeling framework would be useful as a testbed for developing novel GPR signal processing and interpretations procedures and some preliminary results from using it in such a way are presented.
关键词： rough surface,GPR,water puddles,modeling,FDTD,antipersonnel (AP) landmines,roots,dispersive,fractals,Antennas,bowtie,GprMax,grass,vegetation
更新于2025-09-23 15:21:01
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Numerical modeling of coaxial powder stream in laser-powder-based Directed Energy Deposition process
摘要： Laser-powder-based Directed Energy Deposition (DED) process has been used extensively and becomes more and more popular in part manufacturing, repairing and prototype fabrication. It offers an effective way to deposit material via simultaneous delivery of the powders of desired material and laser beam. Complex physical events take place during the process and have great impacts on the success of the process, in which powder stream and its interaction with laser beam play a crucial role. In this paper, a new comprehensive numerical model for powder stream dynamics and heating process is developed to describe the coaxial powder stream and its interaction with laser beam. Reynolds Averaged Navier-stokes (RANS) approach is used for turbulent continuum gas flow while a discrete phase model (DPM) is applied to describe the dynamic behavior of the powder. Two-way coupling approach is adopted to account for the momentum transfer between gas and powder. A new thermal model is developed for powder stream, in which the interaction between powder stream and Gaussian laser beam is modelled through a novel numerical submodel. The obtained results of powder stream are compared with the experimental results from published literature and show good agreement.
关键词： Laser beam,Directed Energy Deposition,Coaxial powder stream,Numerical modeling
更新于2025-09-23 15:21:01
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High sensitivity simple structured displacement sensor using corrugated substrate-integrated waveguide (CSIW)
摘要： Cognitive radio is a promising technology for sharing the underutilized frequency bands that have been licensed to primary users. However, due to the uncertainty in detecting the existence of the primary user, the secondary user may interfere with the primary users when both primary and secondary users are active simultaneously. Therefore, understanding the interference and its consequences on the cognitive network is critical. Unlike the statistical models previously reported in the literature that aim at approximation of the interference, based on the solid mathematical analysis, we propose an accurate model for describing the co-channel interference with probability density function, cumulative distribution function, mean, and variance of the interference suffered by the primary users. The proposed model not only takes into account a number of factors, such as the spectrum-sensing scheme, the spatial distribution of secondary users, and the channel conditions, including shadowing and Nakagami fading, but also gives an exact mathematical expression of the influences from these factors. The developed framework supports practical applications such as evaluating the cognitive network of any spatial shape and density of the secondary users and the methods of power control and spectrum sensing used by the secondary users. Simulation results are provided to verify the effectiveness of the analytical model.
关键词： cognitive radio,Interference modeling,cognitive network
更新于2025-09-23 15:21:01
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A theoretical modeling analysis for triboelectrification controlled light emitting diodes
摘要： In this paper, we demonstrate the use of triboelectric nanogenerator (TENG) as a mean of mechanical light triggering to control InGaN-based light-emitting diodes (LEDs). Light extraction from the LED is two successive steps process. First, the voltage produced by the TENG is used to control the gate-to-source current of a MOSFET transistor through adjusting the transistor channel width and length. The second step is forwarding the drain-source current resulting from MOSFET transistor to the LED as its injection current to induce spontaneous emission from the LED surface to the air. Three LED colors are considered: red, green and blue. Significant emitted power from these InGaN-based LEDs in the RGB wavelength band is observed for both P-MOSFET and N-MOSFET transistor configurations. The emitted optical spectrum is controlled by optimizing the combined TENG-MOSFET-RGB LED geometry; dimensions and the bias voltage between the drain and source terminals of the MOSFET transistor. With recent advances in TENGs as an energy harvesting technology, it is expected that this study offers an approach to enhance the light extraction of various LED devices. With the enhancements in the performance of optoelectronic devices, the field of tribo- phototronics has attracted more attention, and in this work, we introduce the first theoretical framework, to the best of our knowledge, based on finite element modeling. This study provides significant insights into the working principles of tribo-Phototronic devices as well as guidelines for future device design.
关键词： MOSFET,Light-emitting diodes,Finite element modeling,Triboelectric nanogenerator,Tribo-phototronics
更新于2025-09-23 15:21:01
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Wide band ridge gap waveguide (RGW) fan beam antenna with low side lobes based on parabolic reflector principle
摘要： Asthma is one of the most prevalent and costly chronic conditions in the United States, which cannot be cured. However, accurate and timely surveillance data could allow for timely and targeted interventions at the community or individual level. Current national asthma disease surveillance systems can have data availability lags of up to two weeks. Rapid progress has been made in gathering nontraditional, digital information to perform disease surveillance. We introduce a novel method of using multiple data sources for predicting the number of asthma-related emergency department (ED) visits in a specific area. Twitter data, Google search interests, and environmental sensor data were collected for this purpose. Our preliminary findings show that our model can predict the number of asthma ED visits based on near-real-time environmental and social media data with approximately 70% precision. The results can be helpful for public health surveillance, ED preparedness, and targeted patient interventions.
关键词： emergency department (ED) visits,Asthma,big data,environmental sensors,social media,predictive modeling
更新于2025-09-23 15:21:01
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Numerical model for small-signal modulation response in vertical-cavity surface-emitting lasers
摘要： We present a numerical model allowing for simulations of small-signal modulation (SSM) response of vertical-cavity surface-emitting lasers (VCSELs). The model of SSM response utilizes only the data provided by a static model of continuous-wave (CW) operation for a given bias voltage. Thus the fitting of dynamic measurement parameters is not needed nor used. The validity of this model has been verified by comparing experimental SSM characteristics of a VCSEL with the results of simulations. A good agreement between experiment and simulations has been observed. Based on the results obtained in the simulations of the existing laser, the impact of the number of quantum wells in the active region on the modulation properties has been calculated and analyzed.
关键词： optical data transfer,numerical modeling,semiconductor lasers,small-signal modulation response
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE Asia-Pacific Microwave Conference (APMC) - Singapore, Singapore (2019.12.10-2019.12.13)] 2019 IEEE Asia-Pacific Microwave Conference (APMC) - Embedded circularly polarized waveguide antenna based on quartz dielectric
摘要： This paper presents an optimal RC ladder-type equivalent circuit for the representation of the soil for dynamic thermal rating of underground cable installations. This is useful and necessary for their optimal and accurate real-time operation. The model stems from a nonuniform discretization of the soil into layers. The resistive and capacitive circuit elements are computed from the dimensions and physical parameters of the layers. The model is perfectly compatible with the International Electrotechnical Commission thermal–electric analog circuits for cables. The optimum model order is determined, for fast and slow thermal transients, from a comprehensive parametric study. It is shown that an exponential distribution of the soil layers leads to accurate results with differences of less than 0.5 ?C with respect to transient finite-element simulations. An optimal model with only five layers that delivers accurate results for all practical installations and for all time scenarios is presented. The model of this paper is a simple-to-use and accurate tool to design and analyze transient operation of underground cables. It represents a relevant improvement to the available operation and monitoring tools. For illustration purposes, a step-by-step model construction example is given. The model has been validated against numerous dynamic finite-element simulations.
关键词： Soil modeling,Cable thermal rating,Underground cable installations,Transient ratings,Ampacity,Dynamic ratings
更新于2025-09-23 15:21:01
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Online optical inspection of air permeability of packaging materials during laser perforation
摘要： Laser perforations are formed in packaging to control the rate of gas exchange and maintain a balance between the respiration of the product and the permeation of the package. The air permeability of the packaging materials is typically measured using air-driven methods, but these do not allow for online measurement during the rapid production of perforations. The required permeability is generally obtained through trial and error. This paper describes the simulation of air-driven methods through computational fluid dynamics to study the effects of turbulence on the rate of air flow through perforations. A mathematical model is developed to quantify the influence of the micro-perforated size, the total area of exchange, and the thickness of the material on air permeability under certain temperature and pressure differences. The numerical results are in good agreement with the experimental results. An optical system based on the model is designed for the online inspection of packaging materials during the rapid production of laser perforations. Air permeability is precisely determined by analyzing continuous images of the perforations. Perforation characteristics such as shape, quantity, and density can also be measured to allow for feedback control of the perforation process according to the features of the packaged products. The validity and accuracy of the developed system are experimentally verified.
关键词： optical measurement,laser perforation,air permeability,CFD modeling
更新于2025-09-23 15:21:01
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Extraction of uncertain parameters of a single-diode model for a photovoltaic panel using lightning attachment procedure optimization
摘要： The aim of this work is to improve the estimation of parameters of solar photovoltaic models. An approach based on lightning attachment procedure optimization, which takes into account the uncertainties of measurements, is proposed. The approach includes three steps: the extraction of the parameters in a conventional manner, the determination of the partial uncertainties of all the parameters, and finally the determination of the instantaneous parameters based on the results of the first two steps. To validate the proposed theoretical developments, the approach is applied to four different photovoltaic parameter estimation problems. The results obtained are compared with those given by well-established algorithms to confirm the effectiveness of the proposed method, revealing that the proposed method exhibits very effective performance with a root-mean-square error on the order of 1 × 10?17, compared with 1 × 10?4 for existing literature methods.
关键词： Lightning attachment procedure optimization,Photovoltaic modeling,Parameter estimation,Uncertain measurements
更新于2025-09-23 15:21:01
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Integrating Stereo Images and Laser Altimeter Data of the ZY3-02 Satellite for Improved Earth Topographic Modeling
摘要： The positioning accuracy is critical for satellite-based topographic modeling in cases of exterior orientation parameters with high uncertainty and scarce ground control data. The integration of multi-sensor data can help to ensure precision topographical modeling in such situations. Presently, research on the combined processing of optical camera images and laser altimeter data has focused on planetary observations, especially on the Moon and Mars. This study presents an endeavor to establish a combined adjustment model with one constraint in image space for integration of ZY3-02 stereo images and laser altimeter data for improved Earth topographic modeling. The geometric models for stereo images and laser altimeter data were built first, and then, the laser ranging information was introduced to construct a combined adjustment model on the basis of the block adjustment model. One constraint that minimized the back-projection discrepancies in image space was incorporated into the combined adjustment. Datasets in several areas were collected as experimental data for the validation work. Experimental results demonstrated that the inconsistencies between stereo images and laser altimeter data for the ZY3-02 satellite can be reduced, and the elevation accuracy of stereo images can be significantly improved after applying the proposed combined adjustment. Experiments further proved that the improved height accuracy is insensitive to the number and relative position of laser altimeter points (LAPs) in stereo images. Moreover, additional plane control points (PCPs) were incorporated to achieve better planimetric accuracy. Experimental results in the Dengfeng area showed that the adjustment results derived by using LAPs and additional four PCPs were only slightly lower than those for the block adjustment with four ground control points (GCPs). Generally, the proposed approach can effectively improve the quality of Earth topographic model.
关键词： stereo images,combined adjustment,integration,earth topographical modeling,laser altimeter,ZY3-02 satellite
更新于2025-09-23 15:21:01