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High-Precision Doppler Frequency Estimation Based Positioning Using OTFS Modulations by Red and Blue Frequency Shift Discriminator 被引量:1
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作者 Shaojing Wang Xiaomei Tang +3 位作者 Jing Lei Chunjiang Ma Chao Wen Guangfu Sun 《China Communications》 SCIE CSCD 2024年第2期17-31,共15页
Orthogonal Time Frequency and Space(OTFS) modulation is expected to provide high-speed and ultra-reliable communications for emerging mobile applications, including low-orbit satellite communications. Using the Dopple... Orthogonal Time Frequency and Space(OTFS) modulation is expected to provide high-speed and ultra-reliable communications for emerging mobile applications, including low-orbit satellite communications. Using the Doppler frequency for positioning is a promising research direction on communication and navigation integration. To tackle the high Doppler frequency and low signal-to-noise ratio(SNR) in satellite communication, this paper proposes a Red and Blue Frequency Shift Discriminator(RBFSD) based on the pseudo-noise(PN) sequence.The paper derives that the cross-correlation function on the Doppler domain exhibits the characteristic of a Sinc function. Therefore, it applies modulation onto the Delay-Doppler domain using PN sequence and adjusts Doppler frequency estimation by red-shifting or blue-shifting. Simulation results show that the performance of Doppler frequency estimation is close to the Cramér-Rao Lower Bound when the SNR is greater than -15dB. The proposed algorithm is about 1/D times less complex than the existing PN pilot sequence algorithm, where D is the resolution of the fractional Doppler. 展开更多
关键词 channel estimation communication and navigation integration Orthogonal Time frequency and Space pseudo-noise sequence red-blue frequency shift discriminator
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Gigahertz frequency hopping in an optical phase-locked loop for Raman lasers
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作者 毛德凯 税鸿冕 +3 位作者 殷国玲 彭鹏 王春唯 周小计 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期60-65,共6页
Raman lasers are essential in atomic physics,and the development of portable devices has posed requirements for time-division multiplexing of Raman lasers.We demonstrate an innovative gigahertz frequency hopping appro... Raman lasers are essential in atomic physics,and the development of portable devices has posed requirements for time-division multiplexing of Raman lasers.We demonstrate an innovative gigahertz frequency hopping approach of a slave Raman laser within an optical phase-locked loop(OPLL),which finds practical application in an atomic gravimeter,where the OPLL frequently switches between near-resonance lasers and significantly detuned Raman lasers.The method merges the advantages of rapid and extensive frequency hopping with the OPLL’s inherent low phase noise,and exhibits a versatile range of applications in compact laser systems,promising advancements in portable instruments. 展开更多
关键词 Raman lasers optical phase-locked loop frequency hopping
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Research of Frequency Discriminator on Frequency Lock Loops 被引量:1
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作者 徐颖 吴嗣亮 王菊 《Journal of Beijing Institute of Technology》 EI CAS 2008年第4期462-465,共4页
Frequency lock loops (FLL) discriminating algorithms for direct-sequence spread-spectrum are discussed. The existing algorithms can't solve the problem of data bit reversal during one pre-detection integral period.... Frequency lock loops (FLL) discriminating algorithms for direct-sequence spread-spectrum are discussed. The existing algorithms can't solve the problem of data bit reversal during one pre-detection integral period. And when the initial frequency offset is large, the frequency discriminator can' t work normally. To solve these problems, a new FLL discriminating algorithm is introduced. The least-squares discriminator is used in this new algorithm. As the least-squares discriminator has a short process unit period, the correspond- ing frequency discriminating range is large. And the data bit reversal just influence one process unit period, so the least-squares discriminated result will not be affected. Compared with traditional frequency discriminator, the least-squares algorithm can effectively solve the problem of data bit reversal and can endure larger initial frequency offset. 展开更多
关键词 frequency discriminating four-quadrant arctangent LEAST-SQUARES
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A 5-GHz frequency synthesizer with constant bandwidth for low IF ZigBee transceiver applications
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作者 姜亚伟 李智群 +1 位作者 舒海涌 侯凝冰 《Journal of Southeast University(English Edition)》 EI CAS 2010年第1期6-10,共5页
A fully integrated integer-N frequency synthesizer is implemented.The synthesizer is designed for low intermediate frequency (IF)ZigBee transceiver applications.Techniques used to make the loop bandwidth constant ac... A fully integrated integer-N frequency synthesizer is implemented.The synthesizer is designed for low intermediate frequency (IF)ZigBee transceiver applications.Techniques used to make the loop bandwidth constant across the whole output frequency range of the voltage controlled oscillator(VCO)are adopted to maintain phase noise optimization and loop stability.In-phase and quadrature(IQ)signals are generated by a 1/2 frequency divider at the output of the VCO.The synthesizer is fabricated in 0.18 μm radio frequency(RF) complementary metal oxide semiconductor transistor (CMOS)technology.The chip area is 1.7 mm2.The synthesizer is measured on wafer.It consumes totally 28.8 mW excluding output buffers from a supply voltage of 1.8 V.The measured phase noise is -110 and -122 dBc/Hz at the offset of 1 and 3 MHz from a 2.405 GHz carrier,respectively.The measured reference spur at a 2 MHz offset from a 2.405 GHz carrier is-48.2 dBc.The measured setting time of the synthesizer is about 160 μs. 展开更多
关键词 phase-locked loop phase noise auto frequency calibration ZIGBEE voltage controlled oscillator
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Analysis of single frequency modulation for passive hydrogen maser 被引量:2
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作者 Hefei Zheng Jing Li +2 位作者 Wenming Wang Lianshan Gao Keming Feng 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2017年第4期661-668,共8页
Based on the theory of the passive hydrogen maser, along with the technology of frequency modulation and modulation transfer spectroscopy, the theoretical expression of the single frequency modulation for the passive ... Based on the theory of the passive hydrogen maser, along with the technology of frequency modulation and modulation transfer spectroscopy, the theoretical expression of the single frequency modulation for the passive hydrogen maser and the function of the cavity and H line error signals separation are derived, which are basically coincident with the experiment. The absorption and dispersion spectrum curves with different resonance widths show that the cavity and hydrogen transition serve as discriminators, and the two error signals can be separated. Through the calculations of the two error signals in the passive hydrogen maser, it analyzes the traditional method of the two error signals separation, and then describes a new improved method for the passive hydrogen servo loops consisting in the use of a single modulation frequency and frequency discrimination. A null interaction of the two error signals for the new selection of the phase setting is deduced theoretically and validated by the simulation. The preliminary experimental result confirms the feasibility of this new approach, which can reduce the influence from the cavity frequency variety on the crystal oscillator and contribute significantly to the long term performance of the passive hydrogen maser. 展开更多
关键词 passive hydrogen maser single frequency modulation frequency discrimination
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A 1-GHz Charge Pump PLL Frequency Synthesizer for IEEE 1394b PHY 被引量:2
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作者 Jin-Yue Ji Hai-Qi Liu Qiang Li 《Journal of Electronic Science and Technology》 CAS 2012年第4期319-326,共8页
The design procedure of an 1-GHz phase-locked loop (PLL)-based frequency synthesizer used in IEEE 1394b physical (PHY) system is presented in this paper. The PLL's loop dynamics are analyzed in depth and theoreti... The design procedure of an 1-GHz phase-locked loop (PLL)-based frequency synthesizer used in IEEE 1394b physical (PHY) system is presented in this paper. The PLL's loop dynamics are analyzed in depth and theoretical relationships between all loop parameters are clearly described. All the parameters are derived and verified by Verilog-A model, which ensures the accuracy and efficiency of the circuit design and simulation. A 4-stage ring oscillator is employed to generate 1-GHz oscillation frequency and is divided into low frequency clocks by a feedback divider. The architecture is a third-order, type-2 charge pump PLL. The simulated settling time is less than 4μs. The RMS value of period jitter of the PLL's output is 2.1 ps. The PLL core occupies an area of 0.12 mm2, one fourth of which is occupied by the MiM loop capacitors. The total current consumption of the chip is 16.5 mA. The chip has been sent for fabrication in 0.13 μm complementary metal oxide semiconductor (CMOS) technology. 展开更多
关键词 frequency synthesizer Matlab mixed-signal simulation phase-locked loop Verilog-A.
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Pump-induced carrier envelope offset frequency dynamics and stabilization of an Yb-doped fiber frequency comb
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作者 赵健 李文雪 +4 位作者 杨康文 沈旭玲 白东碧 陈修亮 曾和平 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第12期204-208,共5页
In this paper, we demonstrate a carrier envelope phase-stabilized Yb-doped fiber frequency comb seeding by a nonlinear-polarization-evolution(NPE) mode-locked laser at a repetition rate of 60 MHz with a pulse durati... In this paper, we demonstrate a carrier envelope phase-stabilized Yb-doped fiber frequency comb seeding by a nonlinear-polarization-evolution(NPE) mode-locked laser at a repetition rate of 60 MHz with a pulse duration of 191 fs.The pump-induced carrier envelope offset frequency( f0) nonlinear tuning is discussed and further explained by the spectrum shift of the laser pulse. Through the environmental noise suppression, the drift of the free-running f0 is reduced down to less than 3 MHz within an hour. By feedback control on the pump power with a self-made phase-lock loop(PLL)electronics the carrier envelope offset frequency is well phase-locked with a frequency jitter of 85 m Hz within an hour. 展开更多
关键词 optical frequency comb phase-locked loop mode locking fiber laser
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A 1.2-to-1.4 GHz low-jitter frequency synthesizer for GPS application
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作者 胡正飞 HUANG Min-di ZHANG Li 《Journal of Chongqing University》 CAS 2013年第2期97-102,共6页
A fully integrated frequency synthesizer with low jitter and low power consumption in 0.18 μm CMOS (complementary metal-oxide semiconductor) technology is proposed in this paper.The frequency synthesizer uses a novel... A fully integrated frequency synthesizer with low jitter and low power consumption in 0.18 μm CMOS (complementary metal-oxide semiconductor) technology is proposed in this paper.The frequency synthesizer uses a novel single-end gain-boosting charge pump, a differential coupled voltage controlled oscillator (VCO) and a dynamic logic phase/frequency detecor (PFD) to acquire low output jitter.The output frequency range of the frequency synthesizer is up to 1 200 MHz to 1 400 MHz for GPS (global position system) application.The post simulation results show that the phase noise of VCO is only 127.1 dBc/Hz at a 1 MHz offset and the Vp-p jitter of the frequency synthesizer output clock is 13.65 ps.The power consumption of the frequency synthesizer not including the divider is 4.8 mW for 1.8 V supply and it occupies a 0.8 mm×0.7 mm chip area. 展开更多
关键词 frequency synthesizer phase-locked loop voltage controlled oscillator phase/frequency detector charge pump
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Comparative Study of Low-Pass Filter and Phase-Locked Loop Type Speed Filters for Sensorless Control of AC Drives
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作者 Dong Wang Kaiyuan Lu +1 位作者 Peter Omand Rasmussen Zhenyu Yang 《CES Transactions on Electrical Machines and Systems》 2017年第2期207-215,共9页
High quality speed information is one of the key issues in machine sensorless drives,which often requires proper filtering of the estimated speed.This paper comparatively studies typical low-pass filters(LPF)and phase... High quality speed information is one of the key issues in machine sensorless drives,which often requires proper filtering of the estimated speed.This paper comparatively studies typical low-pass filters(LPF)and phase-locked loop(PLL)type filters with respect to ramp speed reference tracking and steady-state performances,as well as the achievement of adaptive cutoff frequency control.An improved LPF-based filter structure with no ramping and steady-state errors caused by filter parameter quantization effects is proposed,which is suitable for applying LPF for sensorless drives of AC machines,especially when fixed-point digital signal processor is selected e.g.in mass production.Furthermore,the potential of adopting PLL for speed filtering is explored.It is demonstrated that PLL type filters can well maintain the advantages offered by the improved LPF.Moreover,it is found that the PLL type filters exhibit almost linear relationship between the cutoff frequency of the PLL filter and its proportional-integral(PI)gains,which can ease the realization of speed filters with adaptive cutoff frequency for improving the speed transient performance.The proposed filters are verified experimentally.The PLL type filter with adaptive cutoff frequency can provide satisfactory performances under various operating conditions and is therefore recommended. 展开更多
关键词 Adaptive cutoff frequency low-pass filter machine sensorless drive phase-locked loop speed filter static error
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Discriminant Classification Model of DNA Sequence 被引量:1
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作者 王显金 阳军 《Agricultural Science & Technology》 CAS 2011年第6期781-784,共4页
[Objective] The research aimed to construct the discriminant classification model of DNA sequence by combining with the biology knowledge and the mathematical method.[Method] According to the polarity nature of side c... [Objective] The research aimed to construct the discriminant classification model of DNA sequence by combining with the biology knowledge and the mathematical method.[Method] According to the polarity nature of side chain radical in the amino acid,the classification information of amino acid which represented the sequence characteristic from the content and array situation of base was extracted from the different sequences that the amino acid content was different.The four-dimension vector was used to represent.Mahalanobis distance and Fisher discriminant methods were used to classify the given sequence.[Result] In the model,the back substitution rates of sample obtained by two kinds of classification methods were both 100%,and the consistent rate of classification was 90%.[Conclusion] In the model,the calculation method was simple,and the accuracy of classification result was higher.It was superior to the discriminant classification model which was only based on the base content. 展开更多
关键词 DNA sequence CODON discriminant analysis frequency
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Anti-noise performance of the pulse coupled neural network applied in discrimination of neutron and gamma-ray 被引量:3
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作者 Hao-Ran Liu Zhuo Zuo +3 位作者 Peng Li Bing-Qi Liu Lan Chang Yu-Cheng Yan 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2022年第6期89-101,共13页
In this study,the anti-noise performance of a pulse-coupled neural network(PCNN)was investigated in the neutron and gamma-ray(n-γ)discrimination field.The experiments were conducted in two groups.In the first group,r... In this study,the anti-noise performance of a pulse-coupled neural network(PCNN)was investigated in the neutron and gamma-ray(n-γ)discrimination field.The experiments were conducted in two groups.In the first group,radiation pulse signals were pre-processed using a Fourier filter to reduce the original noise in the signals,whereas in the second group,the original noise was left untouched to simulate an extremely high-noise scenario.For each part,artificial Gaussian noise with different intensity levels was added to the signals prior to the discrimination process.In the aforementioned conditions,the performance of the PCNN was evaluated and compared with five other commonly used methods of n-γdiscrimination:(1)zero crossing,(2)charge comparison,(3)vector projection,(4)falling edge percentage slope,and(5)frequency gradient analysis.The experimental results showed that the PCNN method significantly outperforms other methods with outstanding FoM-value at all noise levels.Furthermore,the fluctuations in FoM-value of PCNN were significantly better than those obtained via other methods at most noise levels and only slightly worse than those obtained via the charge comparison and zerocrossing methods under extreme noise conditions.Additionally,the changing patterns and fluctuations of the FoMvalue were evaluated under different noise conditions.Hence,based on the results,the parameter selection strategy of the PCNN was presented.In conclusion,the PCNN method is suitable for use in high-noise application scenarios for n-γdiscrimination because of its stability and remarkable discrimination performance.It does not rely on strict parameter settings and can realize satisfactory performance over a wide parameter range. 展开更多
关键词 Pulse coupled neural network Zero crossing frequency gradient analysis Vector projection Charge comparison Neutron and gamma-ray discrimination Pulse shape discrimination
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Comparison of ISFs and LSFs in Speech/Music Discrimination System
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作者 洪英 赵胜辉 匡镜明 《Journal of Beijing Institute of Technology》 EI CAS 2005年第3期234-237,共4页
The immittance spectral frequencies (ISFs) is proposed as a new set of classification features and compared with the linear spectral frequencies (LSFs) applied in a frame-level wideband speech/music discrimination... The immittance spectral frequencies (ISFs) is proposed as a new set of classification features and compared with the linear spectral frequencies (LSFs) applied in a frame-level wideband speech/music discrimination system. These two sets of features can be shared by the classifier and coding module to reduce the total computational complexity, making our classification system suitable for multi-mode audio coding applications. A performance assessment and comparison of the features are made. The experiment results show that the ISFs and LSFs have similar good performance when using full covariance matrices in classification models and the ISFs perform slightly better when using diagonal matrices. Their statistical differences for speech and music signals are also revealed. 展开更多
关键词 immittance spectral frequencies linear spectral frequencies speech/music discrimination
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PHASE-LOCKING OF HIGH POWER GYROTRON OSCILLATOR
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作者 Tang Changjian (Department of Applied Physics, Chengdu University of Science & Technology of China, Chengdu 610065)Yang Zhonghai Liu Pukun(Institute of High Energy Electronics, University of Electronic Science & Technology of China, Chengdu 610054) 《Journal of Electronics(China)》 1996年第1期89-96,共8页
The phase-locking process is studied for high-power gyrotron oscillator driven by an external signal. The phase-locking nonlinear differential equations are derived, and the condition of phase-locking is shown and ana... The phase-locking process is studied for high-power gyrotron oscillator driven by an external signal. The phase-locking nonlinear differential equations are derived, and the condition of phase-locking is shown and analyzed. The phase-locking signal can be introduced after gyrotron oscillates into saturation or before it. Two different ways of inputting signal make markable influence on the phase-locking process, this phenomenon is discussed. In this paper, the numerical calculations and analysis are given for gyrotron TE13 mode. 展开更多
关键词 Microwave OSCILLATOR GYROTRON SELF-CONSISTENT nonlinear theory phase-lockING STABILIZED frequency
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Discrimination Between Nuclear Explosions and Earthquakes: An Application of Wigner Distribution
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作者 Shen Ping and Zheng ZhizhenInstitute of Geophysics,SSB,Beijing 100081,ChinaCenter for Seismic Data and Informadon,SSB,Beijing 100045,China 《Earthquake Research in China》 1996年第3期93-102,共10页
In this paper,the nonstationary theory of Wigner Distribution is used to discriminate between underground nuclear explosions and natural earthquakes.Five underground explosions in Kazakhstan region and seven regional ... In this paper,the nonstationary theory of Wigner Distribution is used to discriminate between underground nuclear explosions and natural earthquakes.Five underground explosions in Kazakhstan region and seven regional earthquakes in its adjacent areas have been analyzed.The result shows that the transient spectra of underground nuclear explosions are concentrated in the frequency range of 5-10 Hz,while the transient spectra of natural earthquakes are distributed widely from lower frequency to higher frequency.The transient frequency of nuclear explosions shows linearity in the first stage(0【t【0.75 s)and its initial frequency is negative.The transient frequency of natural earthquakes rapidly changes in a jumping form and its initial frequency alternates between being positive and negative.The obtained results show that the method is more effective than previous ones in discriminating between underground nuclear explosions and earthquakes.This paper also gives a preliminary explanation of the discrepancy 展开更多
关键词 TRANSIENT spectrum TRANSIENT frequency discriminATION UNDERGROUND NUCLEAR explosion Natural EARTHQUAKE
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A Control Strategy of Frequency Self-adaptation Without Phase-locked Loop for VSC-HVDC
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作者 Yunfeng Li Guangfu Tang +3 位作者 Ting An Hui Pang Zhiyuan He Yanan Wu 《CSEE Journal of Power and Energy Systems》 SCIE 2017年第2期131-139,共9页
A control strategy of frequency self-adaptation without phase-locked loop(PLL)underαβstationary reference frame(αβ-SRF)for a VSC-HVDC system is presented to improve the operational performance of the system under ... A control strategy of frequency self-adaptation without phase-locked loop(PLL)underαβstationary reference frame(αβ-SRF)for a VSC-HVDC system is presented to improve the operational performance of the system under severe harmonic distortion conditions.The control strategy helps to eliminate the cross-coupling under dq synchronous reference frame(dq-SRF),and is achieved through two key technologies:1)positive phase sequence(PPS)and negative phase sequence(NPS)fundamental components are extracted from the AC grid voltage with an improved multiple complex coefficient filter(IMCF),and 2)grid instantaneous frequency is rapidly and precisely tracked using a frequency self-adaptation tracking algorithm(FATA)without PLL.The proposed strategy is applied to a point-to-point VSCHVDC system and validated by means of simulations.The results are compared to those with the traditional vector control strategy under dq-SRF.Simulation results illustrate that the proposed strategy results in better system performance than that with the traditional strategy in terms of harmonic suppression under normal and severe operating conditions of the AC system. 展开更多
关键词 frequency self-adaptation tracking algorithm high voltage direct current improved multiple complex coefficient filter modular multilevel converter phase-locked loop voltage source converter
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基于特征融合和B-SVM的鸟鸣声识别算法 被引量:1
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作者 陈晓 曾昭优 《声学技术》 CSCD 北大核心 2024年第1期119-126,共8页
为了实现在野外通过低成本嵌入式系统识别鸟类,提出了基于特征融合和B-SVM的鸟鸣声识别方法。对鸟鸣声信号提取梅尔频率倒谱系数、翻转梅尔频率倒谱系数、短时能量和短时过零率组成特征参数,通过线性判别算法对特征参数进行特征融合。... 为了实现在野外通过低成本嵌入式系统识别鸟类,提出了基于特征融合和B-SVM的鸟鸣声识别方法。对鸟鸣声信号提取梅尔频率倒谱系数、翻转梅尔频率倒谱系数、短时能量和短时过零率组成特征参数,通过线性判别算法对特征参数进行特征融合。利用黑寡妇算法通过测试集对支持向量机模型的核参数和损失值进行优化得到B-SVM模型。利用Xeno-canto鸟鸣声数据集对本文算法进行了测试,结果表明该方法的识别准确率为93.23%。算法维度参数的大小和融合特征维度的高低是影响算法识别效果的重要因素。在相同条件下,文中所提的基于特征融合和B-SVM模型的鸟鸣声识别算法相较于其他特征参数和模型,识别的准确率更高,为野外鸟类识别提供了参考。 展开更多
关键词 鸟鸣声识别 梅尔频率倒谱系数 线性判别算法 黑寡妇优化算法 支持向量机
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基于高频激光除漆的LIBS监测平台设计与应用研究
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作者 杨文锋 郑鑫 +5 位作者 林德惠 钱自然 李绍龙 左都全 李果 王迪升 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2024年第9期2600-2606,共7页
基于激光诱导击穿光谱(LIBS)技术的飞机漆层清洗监测,需要对峰值功率密度范围进行限定,以确保等离子体激发和漆层清洗的稳定性。然而,对于广泛使用的高频(kHz级)脉冲激光除漆技术,其峰值功率密度相对偏低,除漆过程中等离子体激发受到限... 基于激光诱导击穿光谱(LIBS)技术的飞机漆层清洗监测,需要对峰值功率密度范围进行限定,以确保等离子体激发和漆层清洗的稳定性。然而,对于广泛使用的高频(kHz级)脉冲激光除漆技术,其峰值功率密度相对偏低,除漆过程中等离子体激发受到限制;且高频激光烧蚀材料产生的强连续背景光谱干扰了等离子体光谱采集。论文依据蒙皮功能漆层可控清洗需求,基于LabVIEW嵌入式开发系统的控制软件编写及激光清洗、光谱采集、控制与显示模块的集成,设计了一款适用于高频激光除漆的LIBS监测平台。选取2024-T3铝合金双漆层试样作为研究对象,采集波长介于360~700nm范围内的漆层/基体体系光谱(面漆层:Tc;底漆层:Pr;基体:As)。采用平滑滤波,基线校正和归一化对原始光谱进行预处理,并选取12条特征谱线进行主成分分析(PCA),其降维数据作为线性判别分析(LDA)的输入变量,以此建立PCA-LDA判别模型。最后将所建模型导入LIBS监测平台,通过试验验证了高频激光除漆LIBS监测平台的分类准确性。结果表明:仅以累积方差解释率大于85%作为主成分选取原则,不能满足除漆过程LDA的分类需要;通过优化LDA的主成分个数,最终选取前9个主成分作为LDA的输入,显著提升了LIBS平台的检测准确率,此时基于LIBS光谱的PCA-LDA模型分类准确率达92.5%。由此可见,设计的高频激光除漆LIBS监测平台能够完成漆层/基体体系不同结构层的材料识别,从而实现了高频脉冲激光可控除漆的有效监测。 展开更多
关键词 高频脉冲激光 激光诱导击穿光谱 可控清洗 监测 判别模型
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基于FastICA-LDA的光伏并网逆变器故障诊断
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作者 张磊 余茂全 夏远洋 《新余学院学报》 2024年第5期40-48,共9页
为了实现逆变器开路故障诊断,提出了一种新的诊断方法。该方法采用快速独立成分分析算法判定逆变器是否发生单管开路故障,如果发生单管开路故障,计算旋转电流Id频域下的特征值,将这些特征值作为线性判别分析模型的输入值,最后由LDA模型... 为了实现逆变器开路故障诊断,提出了一种新的诊断方法。该方法采用快速独立成分分析算法判定逆变器是否发生单管开路故障,如果发生单管开路故障,计算旋转电流Id频域下的特征值,将这些特征值作为线性判别分析模型的输入值,最后由LDA模型输出逆变器工作状态编号,从而实现单管开路定位。经过MATLAB仿真验证表明,所提方法对光伏并网逆变器故障的诊断效果较好。 展开更多
关键词 并网逆变器 开路故障 频域特征 快速独立成分分析 线性判别分析
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调制转移光谱对激光频率起伏分辨率的影响因素分析及优化方法 被引量:1
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作者 王越伟 卢飞飞 +1 位作者 侯晓凯 王军民 《中国光学(中英文)》 EI CAS CSCD 北大核心 2024年第4期801-809,共9页
采用电光位相调制器对泵浦光进行位相调制,得到射频调制转移光谱(MTS),并研究MTS光谱的类色散信号中心过零点斜率优化问题。通过改变泵浦光的调制频率,泵浦光与探测光的光斑大小,研究MTS光谱信号过零点斜率与二者之间的参数依赖关系,在... 采用电光位相调制器对泵浦光进行位相调制,得到射频调制转移光谱(MTS),并研究MTS光谱的类色散信号中心过零点斜率优化问题。通过改变泵浦光的调制频率,泵浦光与探测光的光斑大小,研究MTS光谱信号过零点斜率与二者之间的参数依赖关系,在泵浦光调制频率为~3.6 MHz(大约是自然线宽的0.69倍)时,得到最佳的MTS光谱信号。最后利用最优的MTS光谱将DL Pro@852 nm激光频率锁定到铯原子D2线(F=4)-(F=5’)循环跃迁,在60 min采样时间内激光频率起伏约为170 kHz,与自由运转时激光器~11 MHz的频率起伏相比,频率起伏得到了显著改善。 展开更多
关键词 调制转移光谱 激光频率鉴别 激光频率稳定 铯原子D2线 循环跃迁 电光位相调制
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Baseline drift effect on the performance of neutron and γ ray discrimination using frequency gradient analysis 被引量:2
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作者 刘国福 罗晓亮 +3 位作者 杨俊 林存宝 胡青青 彭进先 《Chinese Physics C》 SCIE CAS CSCD 2013年第6期63-69,共7页
Frequency gradient analysis (FGA) effectively discriminates neutrons and γ rays by examining the frequency-domain features of the photomultiplier tube anode signal. This approach is insensitive to noise but is inev... Frequency gradient analysis (FGA) effectively discriminates neutrons and γ rays by examining the frequency-domain features of the photomultiplier tube anode signal. This approach is insensitive to noise but is inevitably affected by the baseline drift similar to other pulse shape discrimination methods. The baseline drift effect is attributed to factors such as power line fluctuation, dark current, noise disturbances, hum, and pulse tail in front-end electronics. This effect needs to be elucidated and quantified before the baseline shift can be estimated and removed from the captured signal. Therefore, the effect of baseline shift on the discrimination performance of neutrons and ~ rays with organic scintillation detectors using FGA is investigated in this paper. The relationship between the baseline shift and discrimination parameters of FGA is derived and verified by an experimental system consisting of an americium-beryllium source, a BC501A liquid scintillator detector, and a 5 GSample/s 8-bit oscilloscope. The theoretical and experimental results both show that the estimation of the baseline shift is necessary, and the removal of baseline drift from the pulse shapes can improve the discrimination performance of FGA. 展开更多
关键词 baseline drift frequency gradient analysis digital discrimination liquid scintillator
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