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Comprehensive Analysis of Gender Classification Accuracy across Varied Geographic Regions through the Application of Deep Learning Algorithms to Speech Signals
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作者 Abhishek Singhal Devendra Kumar Sharma 《Computer Systems Science & Engineering》 2024年第3期609-625,共17页
This article presents an exhaustive comparative investigation into the accuracy of gender identification across diverse geographical regions,employing a deep learning classification algorithm for speech signal analysi... This article presents an exhaustive comparative investigation into the accuracy of gender identification across diverse geographical regions,employing a deep learning classification algorithm for speech signal analysis.In this study,speech samples are categorized for both training and testing purposes based on their geographical origin.Category 1 comprises speech samples from speakers outside of India,whereas Category 2 comprises live-recorded speech samples from Indian speakers.Testing speech samples are likewise classified into four distinct sets,taking into consideration both geographical origin and the language spoken by the speakers.Significantly,the results indicate a noticeable difference in gender identification accuracy among speakers from different geographical areas.Indian speakers,utilizing 52 Hindi and 26 English phonemes in their speech,demonstrate a notably higher gender identification accuracy of 85.75%compared to those speakers who predominantly use 26 English phonemes in their conversations when the system is trained using speech samples from Indian speakers.The gender identification accuracy of the proposed model reaches 83.20%when the system is trained using speech samples from speakers outside of India.In the analysis of speech signals,Mel Frequency Cepstral Coefficients(MFCCs)serve as relevant features for the speech data.The deep learning classification algorithm utilized in this research is based on a Bidirectional Long Short-Term Memory(BiLSTM)architecture within a Recurrent Neural Network(RNN)model. 展开更多
关键词 Deep learning recurrent neural network voice signal mel frequency cepstral coefficients geographical area GENDER
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Approach to blind estimation of the PN sequence in DS-SS signals with residual carrier 被引量:8
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作者 Tianqi Zhang Shaosheng Dai +2 位作者 Guoning Ma Wei Zhang Pu Miao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2010年第1期1-8,共8页
This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) dire... This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) direct sequence spread spectrum (DS-SS) signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR. 展开更多
关键词 direct sequence spread spectrum (DS-SS) signal pseudo-noise (PN) sequence blind estimation singular value de-composition digital phase lock loop residual carrier.
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A novel Doppler frequency measurement method based on the closed-loop signal correlation for deep space exploration
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作者 Tao Deng Mao-Li Ma +3 位作者 Qing-Bao He Qing-Hui Liu Ya-Jun Wu Xin Zheng 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2021年第9期75-82,共8页
In deep space exploration,it is necessary to improve the accuracy of frequency measurement to meet the requirements of precise orbit determination and various scientific studies.A phase detector is one of the key modu... In deep space exploration,it is necessary to improve the accuracy of frequency measurement to meet the requirements of precise orbit determination and various scientific studies.A phase detector is one of the key modules that restricts the tracking performance of phase-locked loop(PLL).Based on the phase relationship between adjacent signals in the time domain,a novel phase detector is presented to replace the arctangent phase detector.The new PLL,which is a closed loop signal correlation algorithm,shows good performance in tracking signals with high precision and the tracking accuracy of frequency of1 second integration is close to Cramer-Rao lower bound(CRLB)when setting proper parameters.Actual data processing results further illustrate the excellent performance of the novel PLL. 展开更多
关键词 Doppler measurement:Cramer-Rao lower bound carrier tracking:phase locked loop signal correlation
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Safety Assessment of Closed-Loop Level Crossing Control Systems by Means of STAMP(Systems-Theoretic Accident Model and Processes)
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作者 Tetsuya TAKATA Akira ASANO Hideo NAKAMURA 《Journal of Traffic and Transportation Engineering》 2018年第5期241-254,共14页
There have been a large number of accidents at level crossings of railways and this has been considered to be a significant issue to be solved for the realization of safe and stable railway transport.A conventional le... There have been a large number of accidents at level crossings of railways and this has been considered to be a significant issue to be solved for the realization of safe and stable railway transport.A conventional level crossing control system is characterized by the use of two types of electronic train detectors;one detects a train approaching to a level crossing section and the other then detects the train having left the level crossing.By contrast,closed-loop level crossing control systems in which level crossing control equipment and train-borne equipment communicate with each other have been advocated and are expected to serve as an effective solution to the abovementioned issue.This paper describes the following three types of closed-loop level crossing control systems:decentralized level crossing control system,fully-centralized comprehensive level crossing control system and fully-centralized individual level crossing control system.This paper then assesses the safety of these systems in comparison to the conventional level crossing control system.For the purpose of the assessment of their safety,a new accident analysis model called STAMP(systems theoretic accident model and processes)that is suitable for software intensive systems is used to clarify the advantage of the proposed three types of level crossing control systems in terms of safety. 展开更多
关键词 Level CROSSING CONTROL railway signaling closed loop CONTROL method safety assessment STAMP
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Quality-of-Experience in Human-in-the-Loop Haptic Communications
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作者 LIU Qian ZHAO Tiesong 《ZTE Communications》 2019年第1期48-55,共8页
With the worldwide rapid development of 5 G networks, haptic communications, a key use case of the 5 G, has attracted increasing attentions nowadays. Its human-in-the-loop nature makes quality of experience(QoE) the l... With the worldwide rapid development of 5 G networks, haptic communications, a key use case of the 5 G, has attracted increasing attentions nowadays. Its human-in-the-loop nature makes quality of experience(QoE) the leading performance indicator of the system design. A vast number of high quality works were published on user-level, application-level and network-level QoE-oriented designs in haptic communications. In this paper, we present an overview of the recent research activities in this progressive research area. We start from the QoE modeling of human haptic perceptions, followed by the application-level QoE management mechanisms based on these QoE models. High fidelity haptic communications require an orchestra of QoE designs in the application level and the quality of service(QoS) support in the network level. Hence, we also review the state-of-the-art QoS-related QoE management strategies in haptic communications, especially the QoS-related QoE modeling which guides the resource allocation design of the communication network. In addition to a thorough survey of the literature, we also present the open challenges in this research area. We believe that our review and findings in this paper not only provide a timely summary of prevailing research in this area, but also help to inspire new QoE-related research opportunities in haptic communications. 展开更多
关键词 QoE human-in-the-loop HAPTIC COMMUNICATIONS KINEStheTIC signalS tactile signalS HAPTIC
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Study on Thixotropic Properties of Waxy Crude Oil Based on Hysteresis Loop Area 被引量:1
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作者 Liping Guo Yu Wang +2 位作者 Shuang Shi Xiaoyang Yu Xu Chen 《Engineering(科研)》 2015年第7期469-476,共8页
Thixotropic properties are one of the low temperature rheology behaviors of gelled waxy crudes. In order to study the thixotropic behavior of gelled waxy crudes oil under cyclic loading of linear increasing and decrea... Thixotropic properties are one of the low temperature rheology behaviors of gelled waxy crudes. In order to study the thixotropic behavior of gelled waxy crudes oil under cyclic loading of linear increasing and decreasing of shear rate, three different types of waxy crude oil were studied ex-perimentally by using MARSIII rheometer. It is found that hysteresis loop area could represent strength of thixotropic properties under that loading. With increasing of the rate of share rate sweep, the area of second hysteresis loop is much smaller than first one and began a slow decline from the third hysteresis loop. Areas of each hysteresis loops were decreased with increasing temperature, but it was different in decline rate—the lower the temperature, the greater the rate of decline. The maximum rate of decrease is the first hysteresis loop with exponential decline, and remaining hysteresis hoops approximately decrease linearly. In addition, based on the experi-mental results an empirical correlation is developed to describe the relationship of hysteresis loop area and rate of share rate sweep. 展开更多
关键词 WAXY CRUDE OIL Thixotropic HYSTERESIS loop area
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Combined optical fiber interferometric sensors for the detection of acoustic emission 被引量:2
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作者 LIANG Yi-jun MU Lin-lin LIU Jun-feng YU Xiao-tao 《Optoelectronics Letters》 EI 2008年第3期184-187,共4页
A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be use... A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors,and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system,so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the frequency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the frequency characteristics. 展开更多
关键词 Acoustic emissions Acoustics Electric network analysis Fiber optics Fibers Fourier transforms Geodetic satellites INTERFEROMETERS Interferometry Lattice vibrations Light sources Michelson interferometers Optical fibers Optical in Acoustic emission sensors Acoustic Emission signals Fiber loop reflectors Fourier Frequency characteristics Interferometric sensors Laser sources Light energy Light intensities Operating points OPTICAL Vibration signals
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Langmuir films stability phenomenon of glycerol dialkyl nonitol tetraether at the air-water interface for variations spreading time 被引量:3
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作者 Sri Vidawati Udo Bakowsky Ulrich Rothe 《Advances in Biological Chemistry》 2012年第3期233-237,共5页
Langmuir films behavior of asymmetric glycerol dialkyl nonitol tetraether (GDNT) lipids at the air-water interface (temperature 19℃ ± 1℃) investigated the stability of the mean ratio of Langmuir films for diffe... Langmuir films behavior of asymmetric glycerol dialkyl nonitol tetraether (GDNT) lipids at the air-water interface (temperature 19℃ ± 1℃) investigated the stability of the mean ratio of Langmuir films for different spreading time prior to the transfer film. Floating monolayer films stability is an important parameter to obtain high-quality Langmuir-Blodgett films for their aplications. Hysteresis loop of the compression-decompression (μ-A) isotherms of Langmuir film GDNT used to analyze the thermodynamic stability of the monolayer films and its features. Langmuir films stability of tetraether lipid GDNT shown more stable at the time of spreading longer than a short time. 展开更多
关键词 Asymmetric GLYCEROL DIALKYL Nonitol Tetraether Lipid Surface Pressure-area ISOtheRM LANGMUIR Films STABILITY Hysteresis loop
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Signal averaging for noise reduction in anesthesia monitoring and control with communication channels
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作者 Zhi-Bin Tan Le-Yi Wang Hong Wang 《Journal of Biomedical Science and Engineering》 2009年第7期564-573,共10页
This paper investigates impact of noise and signal averaging on patient control in anesthesia applications, especially in networked control system settings such as wireless connected systems, sensor networks, local ar... This paper investigates impact of noise and signal averaging on patient control in anesthesia applications, especially in networked control system settings such as wireless connected systems, sensor networks, local area networks, or tele-medicine over a wide area network. Such systems involve communication channels which introduce noises due to quantization, channel noises, and have limited communication bandwidth resources. Usually signal averaging can be used effectively in reducing noise effects when remote monitoring and diagnosis are involved. However, when feedback is intended, we show that signal averaging will lose its utility substantially. To explain this phenomenon, we analyze stability margins under signal averaging and derive some optimal strategies for selecting window sizes. A typical case of anesthe-sia depth control problems is used in this development. 展开更多
关键词 ANEStheSIA Depth ANEStheSIA Monitoring ANEStheSIA Control signal AVERAGING Noise Reduction Open and CLOSED loop SYSTEMS Communications NETWORKED SYSTEMS
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Blind Deconvolution Processing of Loop Inductance Signals for Vehicle Reidentification
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《Journal of Civil Engineering and Architecture》 2011年第11期957-966,共10页
Vehicle reidentification is an elegant solution for gathering several pieces of valuable traffic information, e.g., space mean speed, travel time, vehicle tracking, and origin/destination data. Recently, a number of v... Vehicle reidentification is an elegant solution for gathering several pieces of valuable traffic information, e.g., space mean speed, travel time, vehicle tracking, and origin/destination data. Recently, a number of vehiclereidentification algorithms utilizing inductive loop signals have been proposed to take advantage of the widespread availability of loop detectors. These algorithms, however, all directly utilize the raw inductance signals for pattern matching and feature extraction without deconvolution. The raw loop signals are essentially a convolved output between the true vehicle inductance signature and the loop system function, and thus a deconvolution is needed in order to expose the detailed features of individual vehicles. The purpose of this paper is to present a recent investigation on restoration of true inductance signatures by applying a blind deconvolution process. The main advantage of blind deconvolution over the conventional deconvolution is that the computation does not require modeling of a precise loop-detector system function. Experimental results show that the proposed blind deconvolution reveals much more detailed features of inductance signals and, as a result, increases the vehicle reidentification accuracy. 展开更多
关键词 Vehicle reidentification blind deconvolution loop inductance signals.
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The contribution of oligodendrocytes and oligodendrocyte progenitor cells to central nervous system repair in multiple sclerosis: perspectives for remyelination therapeutic strategies 被引量:9
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作者 Adriana Octaviana Dulamea 《Neural Regeneration Research》 SCIE CAS CSCD 2017年第12期1939-1944,共6页
Oligodencrocytes(OLs) are the main glial cells of the central nervous system involved in myelination of axons. In multiple sclerosis(MS), there is an imbalance between demyelination and remyelination processes, th... Oligodencrocytes(OLs) are the main glial cells of the central nervous system involved in myelination of axons. In multiple sclerosis(MS), there is an imbalance between demyelination and remyelination processes, the last one performed by oligodendrocyte progenitor cells(OPCs) and OLs, resulting into a permanent demyelination, axonal damage and neuronal loss. In MS lesions, astrocytes and microglias play an important part in permeabilization of blood-brain barrier and initiation of OPCs proliferation. Migration and differentiation of OPCs are influenced by various factors and the process is finalized by insufficient acummulation of OLs into the MS lesion. In relation to all these processes, the author will discuss the potential targets for remyelination strategies. 展开更多
关键词 multiple sclerosis oligodencrocytes oligodendrocyte progenitor cells DEMYELINATION REMYELINATION semaphorin basic helix-loop-helix transcription factor oligodendrocyte transcription factor 2 leucin-rich repeatand immunoglobulin-like-domain-containing nogo receptor-interacting protein I canonical Notch signaling endocrine receptors
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Simulation of Automotive Engine Phase Signal Based on Closed-Loop Strategy
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作者 Runlong Cui Mingfa Yao Tao Chen 《Transactions of Tianjin University》 EI CAS 2017年第4期394-400,共7页
In this paper, an automotive engine phase signal simulation algorithm is proposed based on a closed-loop feedback strategy, and its corresponding model is built. The signal incentives are carried out in the front-end,... In this paper, an automotive engine phase signal simulation algorithm is proposed based on a closed-loop feedback strategy, and its corresponding model is built. The signal incentives are carried out in the front-end, and the synchronization capture and comparison are conducted in the back-end. The phase simulation of signal output is achieved using closed-loop strategy, which can effectively eliminate the inconsistency between crankshaft and camshaft phases, and thus the accuracy and flexibility of phase signal generation are guaranteed. Experimental results show that the proposed algorithm is real time, and the deviation of simulated signals from actual phase signals is small. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg. 展开更多
关键词 Crankshafts Engines
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Profibus-DP总线在印染拉幅定形机电气控制系统上的应用
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作者 周振环 《产业用纺织品》 2024年第2期48-52,共5页
对印染拉幅定形机的电气控制系统进行概述。该系统采用先进的西门子Profibus-DP总线通信技术,配备丹佛斯FC302变频器构成速度闭环控制方式。通过信号级联输出方式,实现各传动单元之间的速度同步,提高速度信号的实时性和精确度。此外,介... 对印染拉幅定形机的电气控制系统进行概述。该系统采用先进的西门子Profibus-DP总线通信技术,配备丹佛斯FC302变频器构成速度闭环控制方式。通过信号级联输出方式,实现各传动单元之间的速度同步,提高速度信号的实时性和精确度。此外,介绍了风机变频器和温控表所采用的Modbus总线通信方式,该通信方式实现了更好的设备数据整合与数据交换。 展开更多
关键词 印染拉幅定形机 PRofIBUS-DP总线 速度闭环 触摸屏 MODBUS总线 变频器 信号级联 可编程逻辑控制器
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Adaptively Robust Phase Lock Loop for Low C/N Carrier Tracking in a GPS Software Receiver 被引量:13
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作者 MIAO Jian-Feng CHEN Wu +1 位作者 SUN Yong-Rong LIU Jian-Ye 《自动化学报》 EI CSCD 北大核心 2011年第1期52-60,共9页
在 GPS 应用程序的一个重要问题是怎么追踪 GPS (全球放系统) 在低 carrier-to-noise 比率(C/N ) 下面精确并且连续地发信号。在这份报纸,一个适应地柔韧的过滤器基于低 C/N 搬运人阶段锁循环(PLL ) 在一个 GPS 软件接收装置平台下面... 在 GPS 应用程序的一个重要问题是怎么追踪 GPS (全球放系统) 在低 carrier-to-noise 比率(C/N ) 下面精确并且连续地发信号。在这份报纸,一个适应地柔韧的过滤器基于低 C/N 搬运人阶段锁循环(PLL ) 在一个 GPS 软件接收装置平台下面被开发。就传统的追踪循环上的低 C/N 搬运人信号的效果而言,追踪循环的平行关联被建立。一个线性最佳的评估者被设计在 kinematics 模型和大小处理依赖噪音。而且,一个适应地柔韧的过滤器基于三片断功能被设计调整因素。当收到的信号在有利条件下面时,新过滤器的表演很类似于一个标准 Kalman 过滤器。为追踪的一个实际弱搬运人,这新提高的 PLL 聪明地根据全部的阶段神经质分析调节循环参数。它成功地由适应地平衡更新的动态模型状态和大小的影响抵抗孤立点和动态模型错误。新过滤器的坚韧性和效率被测试实验的一些真实数据表明。结果证实有追踪循环的这个适应地柔韧的阶段的阶段错误的标准差能在 24 dB-Hz 附近与卫星 C/N 比率到达 0.01 个周期,它显著地改进表演。 展开更多
关键词 GPS C/N 全球地位系统 参数控制
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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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Continuous Tracking of GPS Signals with Data Wipe-Off Method
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作者 Dah-Jing Jwo Kun-Chan Lee 《Computers, Materials & Continua》 SCIE EI 2022年第5期3803-3820,共18页
The decentralized pre-filter based vector tracking loop(VTL)configuration with data wipe-off(DWO)method of the Global Positioning System(GPS)receiver is proposed for performance enhancement.It is a challenging task to... The decentralized pre-filter based vector tracking loop(VTL)configuration with data wipe-off(DWO)method of the Global Positioning System(GPS)receiver is proposed for performance enhancement.It is a challenging task to continuously track the satellites’signals in weak signal environment for the GPS receiver.VTL is a very attractive technique as it can provide tracking capability in signal-challenged environments.In the VTL,each channel will not form a loop independently.On the contrary,the signals in the channels of VTL are shared with each other;the navigation processor in turn predicts the code phases.Thus,the receiver can successfully track signals even the signal strength from individual satellite is weak.The tracking loop based on the pre-filter provides more flexible adjustment to specific environments to reduce noise interference.Therefore,even if the signals from some satellites are very weak the receiver can track them from the navigation results based on the other satellites.The navigation data,which contains information necessary to perform navigation computations,are binary phase-shift keying(BPSK)modulated onto the GPS carrier phase with the bit duration of 20 ms(i.e.,50 bits per second)for the GPS L1 C/A signals.The coherent integration interval can be extended for improved tracking performance in signal-challenged environment.However,tracking accuracy is decreased by possible data bit sign reversal.The DWO algorithm can be employed to remove the data bit in I and Q correlation values so as to avoid energy loss due to bit transitions when the integration interval of the correlator is extended over 20 ms under the low carrier-to-noise ratio(C/No)environments.The proposed method has an advantage to provide continuous tracking of signals and obtain improved navigation performance.Performance evaluation of the tracking capability as well as positioning accuracy will be presented. 展开更多
关键词 Global positioning system(GPS) vector tracking loop PRE-FILTER data wipe-off weak signal
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Design of Image Signal Processor for Hardware Size
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作者 Junghwan PARK Jong-sik PARK +3 位作者 Jaekyung WEE Boo-gyoun KIM Seok LEE Seong-soo LEE 《Journal of Measurement Science and Instrumentation》 CAS 2010年第4期391-394,共4页
The Image sensor needs various image processing by Image Signal Processor (ISP) to improve image quality. Conventional cameras have their own software ISP functions to perform in PC instead of using commercial ISP c... The Image sensor needs various image processing by Image Signal Processor (ISP) to improve image quality. Conventional cameras have their own software ISP functions to perform in PC instead of using commercial ISP chips. However these methods have problems such as large computation for image processing. In this paper, th authors proposed ISP that significantly reduced chip area by efficiently sharing of hardware and software. Large operation blocks are designed to hardware for high performances, and hardware is imployed simultaneously with software considering the size of the hardware. The implemented ISP can process Video Graphics Array (VGA) (640 * 480) images and has 91 450 gates size in 0. 35 μm process. 展开更多
关键词 Image signal Processing vision camera low area image process
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Multi-Order Intermittent Chaotic Synchronization of Closed Phase Locked Loop
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作者 Samir M. Shariff 《International Journal of Modern Nonlinear Theory and Application》 2018年第2期48-55,共8页
For the model of a Closed Phase Locked Loop (CPLL) communication System consists of both the transmission and receiver ends. This model is considered to be in a multi-order intermittent chaotic state. The chaotic sign... For the model of a Closed Phase Locked Loop (CPLL) communication System consists of both the transmission and receiver ends. This model is considered to be in a multi-order intermittent chaotic state. The chaotic signals are then synchronized along side with our system. This chaotic synchronization will be demonstrated and furthermore, a modulation will be formed to examine the system if it will perfectly reconstruct or not. Finally we will demonstrate the synchronization conditions of the system. 展开更多
关键词 CHAOTIC SYNCHRONIZATION CHAOTIC signal Communication Systems CLOSED Phase Locked loop System Multi-Order Model
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Efficiently identifying coalbed methane enrichment areas by detecting and locating low-frequency signals in the coal mine
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作者 Siyu Miao Guanwen Cheng +4 位作者 Haijiang Zhang Yuqi Huang Ning Gu Huasheng Zha Ji Gao 《Geohazard Mechanics》 2023年第1期86-93,共8页
Low-frequency signals have been widely found in the conventional oil/gas field and volcanic region as well as during hydraulic fracturing of unconventional oil/gas reservoirs.Their generation mechanism has been ascrib... Low-frequency signals have been widely found in the conventional oil/gas field and volcanic region as well as during hydraulic fracturing of unconventional oil/gas reservoirs.Their generation mechanism has been ascribed to the flow of gas/fluid in the fractures,which can induce the Krauklis wave around fractures and can further excite low-frequency seismic body wave signals at diffraction points.Thus,it is theoretically feasible to determine the gas/fluid enrichment areas and migration pathways by locating the low-frequency signals.Here we have utilized a surface dense seismic array deployed above the Sijiazhuang coal mine in Shanxi province to detect and locate such low-frequency signals that are dominant in the frequency range of 1.5–4.0 Hz.Waveform migrationbased location method is employed to locate these signals that have low signal to noise ratios.We further compare the distribution of low-frequency signals and coalbed methane concentrations that are estimated based on ambient noise tomography result with the same seismic array.The spatial consistency between low-frequency signals and coalbed methane enrichment areas suggests that detecting and locating low-frequency signals with a surface seismic array is an efficient way to identify gas enrichment areas and potential gas migration pathways. 展开更多
关键词 Coalbed methane Enrichment areas Efficiently detecting Low-frequency signals Coal mine
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跟网型变换器的小扰动同步稳定机理分析与致稳控制 被引量:2
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作者 李红 梁军杨 +2 位作者 王振民 李国进 陈延明 《电工技术学报》 EI CSCD 北大核心 2024年第12期3802-3815,共14页
弱电网下,跟网型变换器易出现因阻尼不足导致的小扰动同步失稳问题。为此,该文借鉴复转矩分析理论,计及复杂控制耦合,建立跟网型变换器的复转矩模型。量化多环控制耦合、线路阻抗、控制参数等因素对系统阻尼转矩的影响,从阻尼的角度揭... 弱电网下,跟网型变换器易出现因阻尼不足导致的小扰动同步失稳问题。为此,该文借鉴复转矩分析理论,计及复杂控制耦合,建立跟网型变换器的复转矩模型。量化多环控制耦合、线路阻抗、控制参数等因素对系统阻尼转矩的影响,从阻尼的角度揭示跟网型变换器的小扰动同步失稳机理。根据理论分析,提出一种基于相位补偿的锁相环阻尼重塑控制策略,通过补偿多环控制耦合引入的负阻尼,增强变换器的小扰动同步稳定性。最后,开展相应的仿真与实验,验证理论分析的正确性与改进控制策略的有效性。 展开更多
关键词 跟网型变换器 小扰动同步稳定 多环控制耦合 复转矩分析法 阻尼重塑
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