A Fault Feature Extraction Model in Synchronous Generator under Stator Inter-Turn Short Circuit Based on ACMD and DEO3S

This paper proposed a new diagnosis model for the stator inter-turn short circuit fault in synchronous generators.Different from the past methods focused on the current or voltage signals to diagnose the electrical fault,the sta-tor vibration signal analysis based on ACMD(adaptive chirp mode decomposition)and DEO3S(demodulation energy operator of symmetrical differencing)was adopted to extract the fault feature.Firstly,FT(Fourier trans-form)is applied to the vibration signal to obtain the instantaneous frequency,and PE(permutation entropy)is calculated to select the proper weighting coefficients.Then,the signal is decomposed by ACMD,with the instan-taneous frequency and weighting coefficient acquired in the former step to obtain the optimal mode.Finally,DEO3S is operated to get the envelope spectrum which is able to strengthen the characteristic frequencies of the stator inter-turn short circuit fault.The study on the simulating signal and the real experiment data indicates the effectiveness of the proposed method for the stator inter-turn short circuit fault in synchronous generators.In addition,the comparison with other methods shows the superiority of the proposed model.

Audio Signal Generator System Based On State Machines

A state machine can make program designing quicker,simpler and more efficient. This paper describes in detail the model for a state machine and the idea for its designing and gives the design process of the state machine through an example of audio signal generator system based on Labview. The result shows that the introduction of the state machine can make complex design processes more clear and the revision of programs easier.

Study of ultra-wideband radar signals-generated technology using two-channel signal generator

Synthesis of ultra-wideband （UWB） linear frequency modulation radar signals is a very important technology for microwave imaging, target identification and detection of low radar-cross-section （RCS） targets. A new method of UWB radar signals generation with two-channel signal generator is presented. The realization structure is given; the principle and errors of signal synthesis are analyzed. At the same time, an automatic .adjustment measure of signal phase is proposed because of phase discontinuity of waveform in this method. The simulation experiment and analysis results indicate that radar signals with large instantaneous bandwidth can be generated by means of this method on the condition that the high-speed digital devices are limited.

THE STABLE RECONSTRUCTION OF STRONGLY-DECAYING BLOCK SPARSE SIGNALS

In this paper,we reconstruct strongly-decaying block sparse signals by the block generalized orthogonal matching pursuit(BgOMP)algorithm in the l2-bounded noise case.Under some restraints on the minimum magnitude of the nonzero elements of the strongly-decaying block sparse signal,if the sensing matrix satisfies the the block restricted isometry property(block-RIP),then arbitrary strongly-decaying block sparse signals can be accurately and steadily reconstructed by the BgOMP algorithm in iterations.Furthermore,we conjecture that this condition is sharp.

Frequency Stabilized GaP Continuous-Wave Terahertz Signal Generator for High-Resolution Spectroscopy

We constructed a GaP continuous-wave terahertz (CW-THz) signal generator based on different frequency generation that can tune automatically from 0.15 to 6.2 THz without mode-hopping. Independent frequency feedback control for the seed laser and power feedback control for the optical power amplifier realized higher accuracy and stability of the output THz-wave at the same time. After constructing THz spectrometer with the GaP CW-THz signal generator as a light source, we have confirmed frequency resolution to be 15 MHz by the measurement of the Doppler width of water vapor absorptions in vacuumed chamber, and frequency reproducibility to be within 5 MHz by comparing with absorption frequency data.

Development of a Double-Channel Medical Signal Generator Based on STM32 with High Performance

An open-ended and multifunctional double-channel signal generator, which based on a 32 bits monolithic integrated microcomputer, highly integrated device and LCD, is introduced in this paper. The instrument is composed of micro-computer STM32F103RD and some integrated chips (IC), which includes programmable waveform generators-AD9833 with highly frequency and phase precision. As a result, this signal generator may output not only double channels accurate sine, square or triangle waveforms with digital-controlled frequency and phase at the same time, but also many kinds of physiological signals that can be modified by USB connection with well open property. Therefore, it is convenient to measure and teach about hearing, research and study on frequency characteristic of human ear and impedance characteristic of human body in medical science. In addition, it is also very easy in experiment and research of college and medical physics for using double channels sine signal to show synthesis of two simple harmonic vibrations under different frequency, phase difference and direction, such as beat pattern and Lissajous figures. Thus it has many merits, such as the small volume, stable property, simple operation, visual display and so on. Consequently, it can be widely used in researching, teaching, debugging and maintaining.

基于System Generator的GPS信号捕获模块的实现

System Generator for DSP是业内领先的高级系统级FPGA开发工具.本文基于该软件设计并实现了4通道GPS信号捕获模块,其中包括平均采样、本地C/A码、FFT/IFFT运算、复数乘法运算、扫频控制和结果返回等6个模块,并利用Xilinx的Viertx-5XC5VSX50T-FF665芯片对模块进行了硬件协同验证.测试结果表明:设计实现的捕获模块能够准确地捕获GPS信号,与利用硬件描述语言的方法相比,本文的方法大大缩短了开发周期.

基于System Generator的任意信号发生器的设计与实现

本文利用直接数字频率合成（DDS）技术，采用Xilinx公司推出的System Generator与MATLAB Simulink系统工具，介绍一种自行设计的基于FPGA的DDS电路，实现了任意信号发生器的信号发生器的功能，具有失真度小，稳定度高的优点。

Generative Adversarial Network-Based Electromagnetic Signal Classification: A Semi- Supervised Learning Framework

Generative adversarial network(GAN)has achieved great success in many fields such as computer vision,speech processing,and natural language processing,because of its powerful capabilities for generating realistic samples.In this paper,we introduce GAN into the field of electromagnetic signal classification(ESC).ESC plays an important role in both military and civilian domains.However,in many specific scenarios,we can’t obtain enough labeled data,which cause failure of deep learning methods because they are easy to fall into over-fitting.Fortunately,semi-supervised learning(SSL)can leverage the large amount of unlabeled data to enhance the classification performance of classifiers,especially in scenarios with limited amount of labeled data.We present an SSL framework by incorporating GAN,which can directly process the raw in-phase and quadrature(IQ)signal data.According to the characteristics of the electromagnetic signal,we propose a weighted loss function,leading to an effective classifier to realize the end-to-end classification of the electromagnetic signal.We validate the proposed method on both public RML2016.04c dataset and real-world Aircraft Communications Addressing and Reporting System(ACARS)signal dataset.Extensive experimental results show that the proposed framework obtains a significant increase in classification accuracy compared with the state-of-the-art studies.

REALIZATION OF FUZZY-FILTER CONTROL ON A BRUSHLESS AC GENERATOR

The transistor voltage regulators have been widely adopted in the brushless AC generators in aircraft. This paper researches the digital voltage regulator. The paper presents the hardware platform of the digital voltage regulator, which is based on a DSP chip — TMS320C32. A novel fuzzy filter control structure is developed from normal fuzzy control strategy. And the fuzzy filter control algorithm is adopted in the hardware platform successfully. The computer simulation has been conducted. Some control parameters have been obtained through the simulation. The same parameters have been applied in the digital regulation experiments on a brushless AC generator. In the experiment, the digital voltage regulator results in good responses. From the experiment results, it can be seen that the new control algorithm is efficient for the digital voltage regulator.

基于System Generator的雷达干扰信号模拟

针对雷达干扰信号模拟中算法设计快速验证的应用需求,为降低系统可重构开发中的复杂程度,研究了一种基于System Generator模型的FPGA设计开发方法,并以噪声调频和噪声卷积算法实现。对应用实例进行了设计演示验证,为雷达干扰信号算法验证实验提供技术参考。

GENERALIZED INVERSE GROUP OF SIGNAL AND ITS IMPLEMENTATION WITH NEURAL NETWORKS

A new concept, the generalized inverse group (GIG) of signal, is firstly proposed and its properties, leaking coefficients and implementation with neural networks are presented. Theoretical analysis and computational simulation have shown that (1) there is a group of finite length of generalized inverse signals for any given finite signal, which forms the GIG; (2) each inverse group has different leaking coefficients, thus different abnormal states; (3) each GIG can be implemented by a grouped and improved single-layer perceptron which appears with fast convergence. When used in deconvolution, the proposed GIG can form a new parallel finite length of filtering deconvolution method. On off-line processing, the computational time is reduced to O(N) from O(N2). And the less the leaking coefficient is, the more reliable the deconvolution will be.

Three-step self-calibrating generalized phase-shifting interferometry

An accurate and fast three-step self-calibrating generalized phase-shifting interferomertry(SGPSI) is proposed. In this approach, two new phase-shifting signals are constructed by the difference interferograms normalization and noise suppressing, then the unknown phase shift between the two difference phase-shifting signals is estimated quickly through searching the minimum coefficient of variation of the modulation amplitude, a limited number of pixels are selected to participate in the search process to further save time, and finally the phase is reconstructed through the searched phase shift. Through the reconstruction of phase map by the simulation and experiment, and the comparison with several mature algorithms, the good performance of the proposed algorithm is proved, and it eliminates the limitation of requiring more than three phase-shifting interferograms for high-precision SGPSI. We expect this method to be widely used in the future.

SOFT SWITCHED SYNCHRONOUS RECTIFIER WITH PHASE-SHIFTED FULL BRIDGE CONVERTER AND ITS SMALL-SIGNAL ANALYSIS

By using the output inductors and body capacitances without adding any component compared with hard switching synchronous rectifier,the topology of a soft switched synchronous rectifier with phase-shifted full bridge zero voltage switching DC/DC converter is proposed. The converter efficiency is maximized due to soft switching of the full bridge MOSFETs and the synchronous MOSFETs, and also the low conduction loss of synchronous MOSFET. The operation principles of the circuit are analyzed in detail and the small-signal model is derived, also the converter dynamic characteristics are analyzed. Frequency responses of transfer functions under different values of transformer primary leakage inductance are discussed. The experimental results were obtained from a 400 V input and 100 A/12 V output DC/DC converter operating at 100 kHz. The results show that the converter efficiency is 2% higher in rated power than traditional diode rectifier.

Broad-Band All-Optical Wavelength Conversion of Differential Phase-Shift Keyed Signal Using an SOA-Based Nonlinear Polarization Switch

Broad-band all-optical wavelength conversion of differential phase-shift keyed （DPSK） signal is experimentally demonstrated. This scheme is composed of a one-bit delay interferometer demodulation stage followed by a semiconductor optical amplifier （SOA） based nonlinear polarization switch. A wavelength converter for the 10 G b/s DPSK signal is presented, which has a wide wavelength range of more than 30 nm. The converted signals experience small power penalties less than 1.4 dB compared with the original signal, at a bit error rate of 10-9. Additionally, the optical spectra, the measured waveforms and the open eye diagrams of the converted signals show a high quality wavelength conversion performance.

Numerical Studies of the Generalized <i>l</i>₁Greedy Algorithm for Sparse Signals

The generalized l1 greedy algorithm was recently introduced and used to reconstruct medical images in computerized tomography in the compressed sensing framework via total variation minimization. Experimental results showed that this algorithm is superior to the reweighted l1-minimization and l1 greedy algorithms in reconstructing these medical images. In this paper the effectiveness of the generalized l1 greedy algorithm in finding random sparse signals from underdetermined linear systems is investigated. A series of numerical experiments demonstrate that the generalized l1 greedy algorithm is superior to the reweighted l1-minimization and l1 greedy algorithms in the successful recovery of randomly generated Gaussian sparse signals from data generated by Gaussian random matrices. In particular, the generalized l1 greedy algorithm performs extraordinarily well in recovering random sparse signals with nonzero small entries. The stability of the generalized l1 greedy algorithm with respect to its parameters and the impact of noise on the recovery of Gaussian sparse signals are also studied.

Safety Performance Functions for Traffic Signals:Phasing and Geometry

A significant proportion of urban crashes,especially serious and fatal crashes,occur at traffic signals.Many of the black-spots in both Australia and New Zealand cities occur at high volume and/or high-speed traffic signals.Given this,crash reduction studies often focus on the major signalised intersections.However,there is limited information that links the phasing configuration,degree of saturation and overall cycle time to crashes.While a number of analysis tools are available for assessing the efficiency of intersections,there are very few tools that can assist engineers in assessing the safety effects of intersection upgrades and new intersections.Safety performance functions have been developed to help quantify the safety impact of various traffic signal phasing configurations and level of intersection congestion at low and high-speed traffic signals in New Zealand and Australia.Data from 238 signalised intersection sites in Auckland,Wellington,Christchurch,Hamilton,Dunedin and Melbourne was used to develop crash prediction models for key crash-causing movements at traffic signals.Different variables(road features)effect each crash type.The models indicate that the safety of intersections can be improved by longer cycle times and longer lost inter-green times,especially all-red time,using fully protected right turns and by extending the length of right turn bays.The exception is at intersections with lots of pedestrians where shorter cycle times are preferred as pedestrian crashes increase with longer wait times.A number of factors have a negative impact on safety including,free left turns,more approach lanes,intersection arms operating near or over capacity in peak periods and higher speed limits.

6G新型时延多普勒通信范式:OTFS的技术优势、设计挑战、应用与前景

在未来的通信网络中,被广泛期待的第6代移动通信系统(The Sixth Generation of Mobile Communications System,6G)技术将面临诸多挑战,其中包括在高速移动场景下的超高可靠通信问题。正交时频空间(Orthogonal Time Frequency Space,OTFS)调制技术克服了传统通信系统在高速移动环境下多径和多普勒效应的影响,为实现6G超高可靠通信提供了新的可能性。该文首先介绍了OTFS的基本原理、数学模型、干扰与优势分析。然后,归纳分析了OTFS技术在同步、信道估计、信号检测技术上的研究现状。接着,从车联网、无人机、卫星通信、海洋通信4个典型应用场景分析了OTFS的应用趋势。最后,从降低多维匹配滤波器、相位解调和信道估计、硬件实现的复杂度和提高对时频资源的高度利用4个角度探讨了未来研究OTFS需要克服的困难和挑战。

基于自适应虚拟电阻的低压微电网有功均分下垂控制策略

由于低压微电网中各分布式电源的线路阻抗不匹配,传统的下垂控制策略难以按照下垂系数合理分配有功功率。为此,提出一种无需通信的自适应虚拟电阻下垂控制方法。通过将微电网中每个分布式发电机(DG)单元输出的有功功率和电压传送给自适应虚拟电阻控制器中,在保证电压和频率稳定控制的前提下实现功率按逆变器容量比例进行精确分配。论文对改进方法的微电网逆变器进行小信号稳定性分析,以优化控制器有关控制参数。仿真和实验结果验证了所提控制方法的有效性。

基于充电站谐波特性的频率自适应有源电力滤波控制策略

随着分布式新能源在充电站的接入,源荷的随机特性使电网基频发生波动,进一步加剧站内谐波电流越限风险。对此,提出了一种频率自适应的有源电力滤波谐波检测与跟踪策略。首先,设计了一种改进式广义积分器与延时相消相结合的混合滤波器结构,提高原有广义积分器的滤波性能和动态响应能力,并可消除直流偏置及不平衡分量的影响。其次,通过引入前馈补偿的改进锁相环消除频率波动引起的误差,实现频率自适应谐波检测。最后,基于频率波动导致的谐波跟踪误差,采用结合无限脉冲响应滤波器的快速重复控制,可依据检测频率实现动态调整。仿真和实验结果表明,所提出的控制策略在充电负荷侧可稳定地检测电网频率。且在频率波动的工况下具有较优的谐波补偿能力,在32 ms实现对谐波电流的补偿,治理后电流谐波畸变率下降到5%以下,对不同工况下的充电站具有通用性。