- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Significant Wave Height Retrieval from Gaofen-3 Wave Mode Images
摘要： Significant wave height (Hs), is an important parameter, represented as the integration of directional wave spectra. Although many researchers have directly extracted Hs from SAR images and got a great accuracy of retrieval, those approaches are not suitable for GF-3 SAR data. In this paper, we propose an empirical approach for SAR Hs retrieval, using λc estimated from the real part of image cross spectra obtain from VV-polarized Gaofen-3 (GF-3) wave mode data acquired in different radar beams (called wave-code). Results using GF-3 wave mode data from January to February 2017 indicate that the bias and RMSE errors are: 189 wave-code, -0.13 m and 0.57 m; 190 wave-code, -0.07 m and 0.34 m; 193 wave-code, -0.3 m and 0.59 m; 199 wave-code, 0.16 m and 0.68 m; 215 wave-code, 0.2 m and 0.87 m. they show a relative behavior between the retrieved Hs and the Hs extracted from WAVEWATCH-III (WW3). However, there is a significant error when WW3-extracted Hs exceed 4 m. It seems that the model is not suitable for Hs retrieval on high sea conditions.
关键词： wave empirical retrieval,GF-3,cutoff wavelength estimation,synthetic aperture radar,wave mode
更新于2025-09-23 15:22:29
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High-Performance Tunable Narrowband SIW Cavity-Based Quadrature Hybrid Coupler
摘要： This letter presents, for the first time, a tunable narrowband substrate integrated waveguide (SIW) cavity-based quadrature hybrid coupler. Four high-quality factor (Q) SIW evanescent-mode cavity resonators are employed in the design and tuned using piezoelectric actuators. This allows the proposed coupler to have wide spurious-free range (SFR), low-power consumption, and high-power handling capability compared to other tunable planar couplers. The coupler can be tuned starting from 1.32 to 2.22 GHz with a measured insertion loss range from 1.29 to 0.7 dB. Over the full range, the measured 3-dB fractional bandwidth ranges from 5% to 18% while the phase error (∠S21 ? ∠S31) absolute bandwidth measured ±5° ranges from 40 to 82 MHz with an amplitude imbalance range between 1 and 0.3 dB. The measured reflection and isolation are better than 12 and 17 dB, respectively. Moreover, the coupler has a measured SFR of 5.1–3 fo (lowest–highest frequency).
关键词： tunable quadrature hybrid coupler,Evanescent-mode (EVA) cavity,tunable resonators
更新于2025-09-23 15:22:29
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[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - DEMON Spectrum Extraction Method Using Empirical Mode Decomposition
摘要： The noise radiated by a ship is modulated at a rate dictated by some parameters of the propeller and engine (number of blades, rotational speed). Evaluation of that modulation provides information on the ship, such as the shaft rotation frequency, that can be used for ship classification. The method for estimation of the envelope modulation is known as DEMON (Detection of Envelope Modulation on Noise). Traditionally, the ship noise is bandpass filtered in different frequency bands before the envelope analysis. The bandwidth and the number of the bandpass filters is not known. In this paper a new DEMON spectrum extraction method is proposed using empirical mode decomposition (EMD), in which the band number and width are automatically determined. In performance test, a feedforward neural network is used for 5 kinds ship noise classification, and the percentage of correct classification reaches 91.6%.
关键词： DEMON,empirical mode decomposition,Detection of envelope modulation on noise,feedforward neural network,EMD
更新于2025-09-23 15:22:29
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[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe, Japan (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - The 3D Imaging for Underwater Objects Using SAS Processing Based on Sparse Planar Array
摘要： Acoustic imaging of underwater objects has to include targets of two kinds which are unburied and buried, so that it can demonstrate the underwater environment thoroughly. Especially for the buried objects, it is much more difficult than unburied ones to obtain a qualified acoustical image due to the high backscattering reverberation generated by buried sediments. The three-dimensional downward-looking synthetic aperture sonar(SAS) imaging algorithm based on T-type sparse planar array is presented here to quantify and enhance the performance of underwater objects imaging and to improve the efficiency of sonar mapping as well. Pulse compression, multi narrow-beam nearfield beamforming and synthetic aperture method are applied in vertical direction, across-track direction and along-track direction, respectively. The simulation results show that with regard to the along-track direction, resolution is dependent on the length of the physical aperture and central frequency, as well as irrelevant to the range. Meanwhile, the signal-to-noise ratio(SNR) of image improves with the increase of the length of the synthetic aperture. The across-track direction resolution, however, degrades with the increase of the number of the along-track array elements. Moreover, the method is applied to the sea-trial data of shallow seawater area, where the depth of water is approximately 100 meters and the linear objects are buried at depth of about 3 meters. The results show that the presented algorithm is capable of leading the qualified imaging results for underwater targets.
关键词： underwater object imaging,downward-looking mode,nearfield beamforming,synthetic aperture processing
更新于2025-09-23 15:22:29
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Hydrogen sensing characteristics of AlGaInP/InGaAs enhancement/depletion-mode co-integrated doping-channel field-effect transistors
摘要： In this article, the hydrogen sensing characteristics of Al0.25Ga0.25In0.5P/In0.1Ga0.9As enhancement/depletion-mode co-integrated pseudomorphic doping-channel field-effect transistors by wet selectively etching process are demonstrated. At drain current of 0.1 mA/mm, the threshold voltages are of (cid:1)0.97 (t0.6) V and (cid:1)1.22 (t0.31) V in air and at hydrogen concentration of 9800 ppm, respectively, for the depletion (enhancement)-mode device. In addition, by employing the co-integrated FETs the transfer characteristics of the direct-coupled FET logic (DCFL) obviously vary under hydrogen ambience. The VOH value reduces and the VOL value increases in the DCFL with the measurement of hydrogen detection.
关键词： Threshold voltage,Hydrogen sense,Doping-channel field-effect transistor,Enhancement/depletion-mode,AlGaInP/InGaAs,Direct-coupled FET logic
更新于2025-09-23 15:22:29
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Simple Design Procedure of a Broadband Circularly Polarized Slot Monopole Antenna Assisted by Characteristic Mode Analysis
摘要： In this paper, a systematic design procedure of a compact and broadband circularly polarized (CP) antenna is proposed. The antenna is first designed with a C-shaped monopole, and then a C-shaped slotted patch is utilized to produce CP radiation in the lower frequency band. Thus, the antenna's overall CP bandwidth (BW) is significantly increased. In addition, unlike the conventional method in which the operation is verified by the simulated surface current distribution, characteristic mode analysis (CMA) is carried out to give more insight into different modes on the antenna and generation of circular polarization. The CMA also helps to realize a structural optimization and identify an efficient feed location. The optimized antenna prototype with a compact size of 0.29λo × 0.29λo × 0.01λo (λo is the minimum wavelength at the minimum operation frequency) achieves a usable 10-dB reflection coefficient and 3-dB axial ratio fractional BW of 91% (2.1–5.6 GHz). The antenna realized broadside gain varies from 1.5 to 3.2 dBic within this measured overlapped BW.
关键词： UWB antenna,slot,circularly polarized (CP),monopole,characteristic mode (CM)
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC) - Shenzhen, China (2018.11.4-2018.11.7)] 2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC) - Performance Comparison of Primary Side PFM and Secondary Side PWM for SS Wireless Power Transfer CC/CV Control Strategy
摘要： Wireless Power Transfer (WPT) system for Electric Vehicle (EV) battery charging application popularity is increasing due to the safety, convenience, and eco-friendly issue. Nowadays, Lithium-Ion battery is well known as one of the potential for EV. However, Constant Current/Constant Voltage (CC/CV) control strategy needs to be adopted for achieving high efficiency charging and maintaining battery lifetime. By analyzing the gain curve, Pulse Frequency Modulation (PFM) can be used to perform CC/CV charging due to the load variation. The operating switching frequency needs to be considered and limited to prevent instability of the system. A typical drawback in the PFM control is the use of serial communication module for feedback data transmission from the secondary to the primary side. Therefore, the rectifier side controlled WPT can be a solution to remove the feedback communication part. In this paper, Pulse Width Modulation (PWM) applied in the secondary side (rectifier) for achieving CC/CV charging is investigated and compared with the traditional PFM control. The comparison study is verified by implementing a 3kW Series-Series (SS) WPT topology in the Power Simulation (PSIM) software. It shows that the secondary side PWM control strategy can achieve 94% efficiency during the 35 Ω load in CC mode, while the primary side PFM control only can achieve 88% efficiency.
关键词： PFM Controlled WPT,Wireless Power Transfer (WPT),CC/CV Mode,PWM Controlled WPT
更新于2025-09-23 15:22:29
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Planning Solar in Energy-Managed Cellular Networks
摘要： Recently, there has been a lot of interest on the energy efficiency and environmental impact of wireless networks. Given that the base stations are the network elements that use most of this energy, much research has dealt with ways to reduce the energy used by the base stations by turning them off during periods of low load. In addition to this, installing a solar harvesting system made up of solar panels, batteries, charge controllers, and inverters is another way to further reduce the network environmental impact, and some research has been dealing with this for individual base stations. In this paper, we show that both techniques are tightly coupled. We propose a mathematical model that captures the synergy between solar installation over a network and the dynamic operation of energy-managed base stations. We study the interactions between the two methods for networks of hundreds of base stations and show that the order in which each method is introduced into the system does make a difference in terms of cost and performance. We also show that installing solar is not always the best solution even when the unit cost of the solar energy is smaller than the grid cost. We conclude that planning the solar installation and energy management of the base stations has to be done jointly.
关键词： Cellular networks,solar power,energy management,sleep mode
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC) - Shenzhen, China (2018.11.4-2018.11.7)] 2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC) - Parity-time-symmetric Wireless Power Transfer System Using Switch-mode Nonlinear Gain Element
摘要： Parity-time (PT) symmetry, a concept ranging from quantum field theories and mathematical physics to classical optics, is generalized to a wireless power transfer (WPT) system in [7]. However, the already introduced system is based on an operational amplifier, limiting the power transfer efficiency of the whole system. In this paper, the concept of PT symmetry is generalized to a switch-mode WPT system. PT symmetry is achieved with a nonlinear gain element which is a single-phase bridge inverter, achieving robust wireless power transfer scheme. It is shown in simulation that the system could adjust the frequency within tens of switching period, providing attractive way of dynamic charging. The analysis of the whole system is based on coupled mode theory (CMT).
关键词： averaged model,switch-mode,Parity-time symmetry,coupled modes,wireless power transfer
更新于2025-09-23 15:22:29
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Three-Dimensional Resource Allocation in Space Division Multiplexing Elastic Optical Networks
摘要： In this paper, we present a comprehensive model to address three-dimensional resource assignment (3D-RA) in space division multiplexing elastic optical networks using few-mode multi-core fibers (FM-MCFs). Accordingly, we present new 3D-RA algorithms in which the consequential resources include the spectrum, modes, and cores. We consider all spectral and spatial diversity types in FM-MCFs and introduce five 3D-RA scenarios including (i) single-mode and single-core (SMSC), (ii) single-mode and multi-core (SMMC), (iii) multi-mode and single-core (MMSC), (iv) multi-mode and multi-core (MMMC), and finally, (v) hybrid 3D-RA. In each scenario, the fractional joint (FrJ-) and independent (Ind-) switching (Sw) schemes are introduced and explored for the proposed scenarios. By using the FrJ- and Ind-Sw schemes, we performed the simulation process for the above-mentioned scenarios. The simulation results confirm the efficiency of the proposed 3D-RA algorithms. Furthermore, various 3D-RA scenarios are comprehensively compared using the obtained results in terms of vital metrics introduced in this work. It is also indicated that the SMSC and MMSC scenarios present superior performance for Ind-Sw and FrJ-Sw 3D-RA scenarios, respectively, in comparison to other proposed non-hybrid scenarios. The obtained results also reveal that the quad-hybrid 3D-RA scenario results in the lowest blocking probability in comparison with all other introduced scenarios in both switching schemes. These results recommend an efficient simulation system for compatible transceivers for Ind- and FrJ-Sw schemes.
关键词： Spectral and spatial resource allocation,Few mode-multi core fiber,Space division multiplexing,Elastic optical network
更新于2025-09-23 15:22:29