- 标题
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- 关键词
- 实验方案
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[IEEE 2018 IEEE International Conference on RFID Technology & Application (RFID-TA) - Macau (2018.9.26-2018.9.28)] 2018 IEEE International Conference on RFID Technology & Application (RFID-TA) - Near Field Sources Localization Based on Robust Propagator Method
摘要： The problem of joint direction-of-arrival (DOA) and range estimation of near-field multiple sources under α-stable distributed impulsive noise environments is studied in this paper. The proposed algorithm constructs the MUSIC spectral spectrum based on the noise subspace which is obtained by applying the propagator method on the fractional lower order statistical matrix of the array received signal, and then estimates the multiple sources’ DOA and range parameters by the spectral peak search. Compared with the corresponding algorithms based on second-order statistics, the proposed algorithm can effectively suppress the impulse noise by using the fractional lower-order statistics. At same time, the inherent large computational complexity of the eigenvalue decomposition based methods can also be avoided. Simulation experiments prove the effectiveness of the proposed algorithm.
关键词： impulsive noise,direction of arrival,fraction lower order statistics,range estimation,near-field,propagator method
更新于2025-09-23 15:23:52
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Microstructure and tribological properties of laser cladded self-lubricating nickel-base composite coatings containing nano-Cu and h-BN solid lubricants
摘要： In the present work, nickel-base composite powder (Ni60), nickel-base composite powder with the addition of h-BN solid lubricants (h-BN/Ni60) and nickel-base composite powder with the addition of nano-Cu encapsulated h-BN solid lubricants (nano-Cu/h-BN/Ni60) were used as raw materials to synthesize three different coatings on Q235 steels by laser cladding. Microstructures of these coatings were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. Tribological properties of these coatings were investigated at the temperatures from 25 °C to 600 °C. High temperature micro-hardness measurement was performed by Vickers micro-hardness tester. The results showed that the h-BN particles survived after laser cladding and displayed a homogeneous distribution in the nickel-base composite matrix. The encapsulation of h-BN by nano-Cu resulted in an increase of h-BN content in the coating. Although the addition of nano-Cu and h-BN led to a decrease on hardness, the nano-Cu/h-BN/Ni60 coating had the lowest friction coefficient and wear rate among the three coatings in a wide range of temperature from 25 °C to 500 °C. The mechanism of wear reduction by addition of nano-Cu encapsulated h-BN solid-lubricants was also discussed in this research.
关键词： Laser cladding,Self-lubricant coating,Steel substrate,Wear,Wide temperature range,Nickel-base composite
更新于2025-09-23 15:23:52
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Error correction for short-range optical interconnect using COTS transceivers
摘要： Nowadays, quantities of commercial off-the-shelf (COTS) optical transceivers are widely equipped in both exiting and abuilding data centers. As data centers are becoming larger and containing more servers, the method to ensure longer and steady transmission with COTS optical transceivers becomes one of the key issues. Meanwhile, variations in the manufacturing of COTS optical transceivers bring in fluctuation of packet error rate (PER) in communication. In this paper, we present an application layer adaptive forward error correction (AL-AFEC) coding scheme for COTS optical transceivers in optical interconnect to solve the problems mentioned above and test its performance in a 10 Gbps Ethernet (10GbE) link using 10GBASE-SR SFP+ modules. Experimental results show that the proposed scheme enables longer transmission distance and the instability introduced by manufactural variations is well settled. Since our scheme requires no extra hardware on optical transceivers, it is a considerable low-cost alternative to improve system reliability and achieve longer transmission distance for COTS optical transceivers.
关键词： short-range optical interconnect,ethernet,vertical cavity surface emitting laser (VCSEL),application layer adaptive forward error correction,commercial off-the-shelf optical transceiver
更新于2025-09-23 15:23:52
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Variable-range-hopping conduction and polaron dielectric relaxation in Cu and Nb co-doped BaTiO3
摘要： BaTi0.7(Cu0.1Nb0.2)O3 ceramic was prepared using a solid-state method and its structure, valence states, conduction mechanism and dielectric properties were investigated in detail. A fine-grained microstructure and a distorted pseudo-cubic perovskite structure were confirmed by scanning electron microscopy, X-ray diffraction analysis and Raman spectroscopy. X-ray photoelectron spectroscopy analysis suggested that Cu in BaTi0.7(Cu0.1Nb0.2)O3 was polyvalent but the valence states of Ti and Nb were invariable. Mott’s variable-range-hopping (VRH) conduction was observed. The two colossal dielectric constant plateaus in low- and high-temperature ranges were ascribed to the electrode and grain boundary responses, respectively. The VRH model described the low-temperature relaxation well, indicating that the dielectric relaxation was a polaron relaxation rather than Maxwell–Wagner type. Both grain and grain boundary resistances were well fitted by the VRH model, suggesting that the VRH mechanism was tenable in both grain and grain boundaries. The electron paramagnetic resonance signal was ascribed to Cu ions, and the linewidth showed a linear relationship with T?1/4, corresponding to the charge transfer between different valence via Cu+-O-Cu2+ and Cu2+-O-Cu3+ paths. The hopping of carriers was also responsible for the conduction and polaron dielectric relaxations.
关键词： Variable-range-hopping conduction,Electron paramagnetic resonance.,Dielectric relaxation,Cu and Nb co-doped BaTiO3
更新于2025-09-23 15:23:52
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[IEEE 2018 International Semiconductor Conference (CAS) - Sinaia (2018.10.10-2018.10.12)] 2018 International Semiconductor Conference (CAS) - A High Performance Mixed-Voltage Digital Output Buffer
摘要： A digital push-pull output buffer is designed and implemented in a 0.18μm CMOS EEPROM process. The buffer acts as an interface between an internal low voltage and an external, higher level voltage. The circuit can operate in a wide range of power supply voltages, from 1.6V to 5.6V, at data rates of up to 20 Mbps. These performances were achieved through topology changes to a classic digital buffer.
关键词： push pull stage,high data rate,output buffer,wide voltage range
更新于2025-09-23 15:23:52
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Incoherent Range Walk Compensation for Spaceborne GNSS-R Imaging
摘要： Global navigation satellite system reflectometry (GNSS-R) receivers produce delay-Doppler maps (DDMs) by incoherently integrating coherent integration results. Due to system dynamics, during incoherent integration, the receiver aligns each coherent result by tracking the delay and Doppler of the specular point. This is known to cause a blurring of the spatial footprint of the Woodward ambiguity function (WAF) on the reflecting surface. In this paper, we demonstrate that the blurring of the WAF varies over the glistening zone (GZ), and even if a fixed point on the ground is tracked, blurring still occurs. We derive the expressions for the delay and Doppler change rates over the GZ and then predict the error introduced by range walk for typical GNSS-R scatterometry configurations. We find that ≈6 dB of loss is expected for a point scatterer near the edge of the GZ when a fixed point on the surface is tracked. The incoherent range walk compensation (IRWC) method is then presented for GNSS-R receivers to mitigate this loss. The IRWC method focuses the power in the DDM to the isodelay and iso-Doppler configuration occurring at the midpoint of the integration time. DDMs produced by tracking a fixed point with and without IRWC are simulated, and errors are found to be in agreement with those predicted. Spatial domain GNSS-R products will be improved with IRWC. Target detection will benefit from a larger usable swath, allowing longer tracking and detection times as a result of the increased target to clutter and noise ratio. At the same time, imaging applications will no longer suffer from a spatially variant blurring of the WAF, which limits the resolution of the estimated products. IRWC is shown to mitigate the range migration losses and improve the SNR of an imaging GNSS-R receiver by ≈6 dB near the edge of the GZ.
关键词： integration,global navigation satellite system reflectometry (GNSS-R),reflectometry,imaging,target detection,receiver,incoherent range walk compensation (IRWC),Dynamic corrections
更新于2025-09-23 15:23:52
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HLS Based Approach to Develop an Implementable HDR Algorithm
摘要： Hardware suitability of an algorithm can only be verified when the algorithm is actually implemented in the hardware. By hardware, we indicate system on chip (SoC) where both processor and field-programmable gate array (FPGA) are available. Our goal is to develop a simple algorithm that can be implemented on hardware where high-level synthesis (HLS) will reduce the tiresome work of manual hardware description language (HDL) optimization. We propose an algorithm to achieve high dynamic range (HDR) image from a single low dynamic range (LDR) image. We use highlight removal technique for this purpose. Our target is to develop parameter free simple algorithm that can be easily implemented on hardware. For this purpose, we use statistical information of the image. While software development is verified with state of the art, the HLS approach confirms that the proposed algorithm is implementable to hardware. The performance of the algorithm is measured using four no-reference metrics. According to the measurement of the structural similarity (SSIM) index metric and peak signal-to-noise ratio (PSNR), hardware simulated output is at least 98.87 percent and 39.90 dB similar to the software simulated output. Our approach is novel and effective in the development of hardware implementable HDR algorithm from a single LDR image using the HLS tool.
关键词： system on chip,high-dynamic range image,low-dynamic range image,field-programmable gate array,high-level synthesis
更新于2025-09-23 15:22:29
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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 - Two-dimensional Spectrum for Diving Stage SAR Processing with High-order Equivalent Range Model
摘要： For airborne synthetic aperture radar (SAR) processing in its diving stage, the diving velocity brings additional range variance to the range history in the synthetic aperture time. The traditional hyperbolic range model is not accurate enough to approximate the actual range equation and the precise two-dimensional spectrum cannot be achieved. In order to address this problem, a highly accurate spectrum deduction based on high-order equivalent range model is proposed in this paper. By introducing the high-order terms, more degrees-of-freedom are obtained for the equivalent range model and the actual range history can be accurately fitted. Based on the achieved range model, the two-dimensional spectrum for diving stage SAR can be accessed. Simulation experiments are carried out to validate the effectiveness of proposed spectrum.
关键词： two-dimensional spectrum,diving stage,range model,Synthetic aperture radar (SAR)
更新于2025-09-23 15:22:29
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Distance-Range-Oriented Constellation Design for VLC-SCMA Downlink with Signal-dependent Noise
摘要： In this paper, the constellation design for a sparse code multiple access (SCMA) based visible light communication (VLC) downlink is studied. The noise at the receiving avalanche photodiode (APD) is dependent on the signal intensity, and the associated design problems are typically intractable. We point out that for such a system both the minimum Euclidean distance (MED) and Rotated-MED based methods are not the optimal optimization objective, and propose a distance-range-oriented (DRO) modulation, where a linear combination of the minimum and maximum Euclidean distance is considered. We observe in the simulation results that the proposed DRO-based scheme outperform the MED and Rotated-MED based ones across a wide range of signal and noise levels.
关键词： distance range,signal-dependent noise,Constellation design,SCMA,visible light communication
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Radar (RADAR) - Brisbane, Australia (2018.8.27-2018.8.31)] 2018 International Conference on Radar (RADAR) - Space-Range-Doppler Focus Processing: A Novel Solution for Moving Target Integration and Estimation Using FDA-MIMO Radar
摘要： Frequency diverse array (FDA) is an emerging array technique that employs a small frequency increment across its array elements to produce a range-angle-dependent beampattern, which provides promising applications for joint angle-range estimation of targets. However, the FDA has several problems for signal processing, such as angle and range coupling and Doppler integration, and few papers deal with FDA for moving target. In this paper, we combine the FDA and MIMO technique and propose the concept of space (angle)-range-Doppler (SRD) focus processing, which is a novel solution for moving target integration and estimation. It utilizes the property of FDA and high-resolution Doppler processing of MIMO. Based on the data model of FDA-MIMO radar, we provide a practical method for SRD processing via A&D joint estimation and sparse time-frequency distribution (STFD). Both theoretical and numerical simulation results verify that proposed method has better ability for joint range-angle-Doppler processing, which can be used for low-observable moving target detection and estimation under complex environment.
关键词： Moving target integration,Space-Range-Doppler (SRD) focus processing,Frequency diverse array (FDA) radar,Sparse time-frequency distribution (STFD)
更新于2025-09-23 15:22:29