bob手机在线登陆学报自然版

2020, 40(3): .

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2020, 40(3): .

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Relevant Research on Electromagnetic Pulse Protection of RF Front-End

TAN Zhi-liang, LI Ya-nan, SONG Pei-jiao

2020, 40(3): 231-242. doi: 10.15918/j.tbit1001-0645.2018.332

Abstract(1154) PDF(513)

Abstract:
The electromagnetic pulse (EMP) weapons have brought forward a severe challenge to the communication system,especially the radio frequency (RF) front-end circuit.The RF front-end circuit is the key part of the vulnerable link under the strong EMP attack.It is of great significance for the communication system to improve the overall capacity of electromagnetic protection.In this paper,the research content of the EMP protection in the RF front end was analyzed.In terms of three basic elements,namely electromagnetic pulse effect research,electromagnetic pulse protection technology,and electromagnetic compatibility standard,the studies were summarized,including simulation modeling,experimental testing,and protection strategies at home and abroad.Finally,several frontier problems with EMP protection were also summarized,which maybe provide some references for the future researches and applications.

Pseudo Lamped-Blade Simulation Method of Turbomachinery Based on Single-Blade Transient Simulation

YAN Qing-dong, KE Zhi-fang, WEI Wei, LI Jin

2020, 40(3): 243-249. doi: 10.15918/j.tbit1001-0645.2019.08.415

Abstract(1838) PDF(556)

Abstract:
Since the higher cost and difficulty in mesh quality control of full blade simulation method, a pseudo-lumped-blade simulation method (PLSM) was proposed to analyse the blade-row interaction as well as its effect on the performance of the hydrodynamic torque converter. Firstly, a three-dimensional, transient, single-blade passage model was established based on a D400 hydrodynamic torque converter. And then the PLSM was used to calculate the time-independent blade's torque as well as the time-dependent impeller torque, so as to further study on the blade-row interaction effect and its impact on torque converter performance. Finally, the PLSM was validated in pump wheel, turbine and idler pulley samples. The results show that, the most error of the torque is less than 11.1% and the analysis error for the original characteristic of torque converter is less than 4.37%. It implies that PLSM is effective and reliable, and can not only reduce the calculation costs, but also be of great help to further study the blade-row interaction for hydrodynamic torque converters.

Performance of Triboelectric Nanogenerators Based on Hyperelastic Polydimethylsiloxane

WANG Xiao-li, NIU Zhi-hao, YANG Wei-xu

2020, 40(3): 250-253,281. doi: 10.15918/j.tbit1001-0645.2018.394

Abstract(1176) PDF(471)

Abstract:
Polydimethylsiloxane (PDMS), which is often used in triboelectric nanogenerators, is a kind of hyperelastic polymer. However, the theoretical analysis of PDMS has made use of the linear elastic constitutive assumption in so far, and its effectiveness has not been proved by experiments. Firstly, the contact mechanics and electrostatic induction performance of PDMS triboelectric nanogenerators were simulated based on the hyperelastic constitutive equation. Secondly, PDMS pyramid texture was prepared by photolithography and replica technique. Finally, the test rig for triboelectric nanogenerators was constructed, and the experimental and theoretical results were compared. The results show that the contact area and open-circuit voltage of triboelectric nanogenerators increase with the increase of applied pressure first and then tend to be stable. Compared with the hyperelastic constitutive relation, the linear elastic constitutive relation overestimates the contact area between the metal and PDMS, and therefore underestimates the pressure required to stabilize the open-circuit voltage of triboelectric nanogenerators. The simulation results based on the hyperelastic PDMS constitutive relation are more consistent with the experimental results.

Research on the Longitudinal Tracking of Adaptive Cruise Control System for Vehicles Considering of Measurement Noise

HUANG Ju-hua, ZOU Han-peng, LIU Ming-chun

2020, 40(3): 254-261. doi: 10.15918/j.tbit1001-0645.2018.410

Abstract(1034) PDF(426)

Abstract:
Aiming at adaptive cruise control (ACC) system with noise,a feedback correction model predictive controller (MPC) was proposed based on adaptive compensation method,composed of a Kalman filter and a model predictive controller.Firstly,a longitudinal tracking vehicle dynamics model of ACC control system was established,making use of a Kalman filter to estimate state variables and eliminate measurement noise.Then,the feedback correction mechanism was used to improve the prediction model for following vehicles to deal with the influence of uncertain parameters and external interference on model accuracy.And the softening vectors factors were used to deal with hard constraints,making the reasonable solutions be found in the optimization process.Finally,the controller proposed in this paper was transformed into a quadratic programming problem with constraints,taking the rolling optimization characteristics of the MPC to realize ACC.Experimental results show that the method proposed in this paper can effectively improve the safety and comfort of ACC system,providing a powerful anti-jamming ability.

Driving Style Recognition in the Vehicle Starting Condition Based on the Modified Fisher Discrimination

JIN Hui, LÜ Ming

2020, 40(3): 262-266. doi: 10.15918/j.tbit1001-0645.2019.083

Abstract(1081) PDF(338)

Abstract:
According as the driving data of the vehicle starting condition collected from experiments, the driving style characteristic parameters were selected based on principal component analysis (PCA) method. Then, clustering and analyzing the driving data with Gaussian mixture mode (GMM) clustering algorithm, a driving style recognizer was developed based on Fisher discrimination. Finally, the classical Fisher discrimination and the modified Fisher discrimination were utilized to identify the test set of driving style data comparatively. The results show that, the recognition accuracy with modified Fisher discrimination can reach more than 85%, proving the availability and veracity of this modified Fisher discrimination in the estimation of driving style and vehicle moving performance.

Energy Absorption Analysis and Optimization of a Bionic Thin-Walled Tube Based on Shrimp Chela

HUANG Han, XU Shu-cai, DU Wen-jing, ZOU Meng, SONG Jia-feng, ZHANG Jin-huan

2020, 40(3): 267-274. doi: 10.15918/j.tbit1001-0645.2018.342

Abstract(1491) PDF(537)

Abstract:
A thin-walled tube with bionic cell was developed based on shrimp chela structure of odontodactylus scyllarus to improve the crashworthiness and energy absorption of thin-walled tube. The finite element method was adopted to simulate the axial and radial energy absorption of the bionic thin-wall tube. A response surface method was used to obtain optimal structure of the bionic thin-wall tube. Simulation results show that, the specific energy absorption(SEA) of bionic thin-walled tube can be improved by 11.1% (axial) and 24.6% (lateral), respectively, compared with the normal thin-walled tube. The optimization structure dimensions can be obtained. The optimal value of SEA is 27.0 kJ/kg (axial) and 10.8 kJ/kg (lateral), respectively. This research provides new methods for lightweight designing of thin-walled structures.

State of Charge Estimation and Hardware-in-Loop Verification of Lithium-ion Battery Based on BCRLS-AEKF

WANG Zhi-fu, LIU Zhao-jian, LI Ren-jie

2020, 40(3): 275-281. doi: 10.15918/j.tbit1001-0645.2019.068

Abstract(1556) PDF(389)

Abstract:
The parameter identification and state of charge (SOC) estimation of lithium-ion battery under colored noise were studied and verified by hardware-in-the-loop experiments. In the parameter identification process of the power battery model, the bias compensation recursive least squares with forgetting factor (BCRLS) was used to compensate the deviation, improving the parameter identification accuracy of the colored noise data. On this basis, an adaptive extended Kalman algorithm (AEKF) was used to estimate the SOC, making the estimation result in the filtering algorithm adaptively updated with the change of the statistical characteristics of the noise, and the joint estimation of the model parameters and the battery state be realized. Finally, the battery voltage and current information output was simulated by the BMS test system, and the hardware-in-the-loop experiment was completed to verify the proposed method. The experimental results show that the battery terminal voltage and SOC error estimated by the proposed algorithm are less than 10 mV and 0.5%, respectively.

Representation Learning Based on Path Selection in Complex Networks

LIU Qiong-xin, LONG Hang, ZHENG Pei-xiong

2020, 40(3): 282-289. doi: 10.15918/j.tbit1001-0645.2018.053

Abstract(973) PDF(359)

Abstract:
Path-based and representation-based reasoning are two major methods on knowledge inference. A combination of both algorithms can improve the accuracy of knowledge reasoning. However, there are still some problems, such as inefficiencies in learning, low prediction accuracy and over-fitting of the model. A representation learning method based on path selection was proposed in this paper to further filter the path feature information, to hold the key paths and to use the balance parameter to process the triples of missing path information. In this paper, a public data set was used to test the model. Experiments show that the model can effectively improve the generalization ability and accuracy.

A Spatial Gamut Mapping Framework Based on Detail Preservation

ZHU Ming, JIAO Hui-min, ZHAO Xing-yun, YANG Jing-kun

2020, 40(3): 290-297. doi: 10.15918/j.tbit1001-0645.2017.334

Abstract(1017) PDF(485)

Abstract:
Considering the defects of point wise gamut mapping algorithms (GMAs) in detail-preservation and the halos introduced by spatial gamut mapping algorithms (SGMAs), a SGMA framework was proposed to effectively preserve the image detail and inhibit spatial filtering halos. Firstly,the influences of different Guided-filtering parameters on detail-reproduction were analyzed in detail to determine the optimal filtering parameters. Then, two point wise gamut mapping operators "CUSP" and "HpMinDE" were modified for the proposed SMGA framework according to the characteristics of layered gamut mapping. Finally, some evaluating experiments were carried out. The results show that, in aspects of image preference and reproduction accuracy, the proposed SGMA is obviously better than the other two classical algorithms of the same type and the classical optimization iterative algorithm. The superiority of the proposed SGMA in halos-inhibition were also tested and verified by means of the standard halos-testing image.

An Unambiguous Acquisition Algorithm Based on Correlation Shift for BOC(n,n)

SUN Xi-yan, HAO Fang, JI Yuan-fa, YU Bao-guo, HAO Qing-ru, GAN Xing-li, ZHEN Wei-min

2020, 40(3): 298-304. doi: 10.15918/j.tbit1001-0645.2018.078

Abstract(1119) PDF(368)

Abstract:
In the course of GPS modernization, in order to avoid mutual interference between navigation signal frequency bands, the BOC modulation technology is adopted to realize rational utilization of frequency band resources. However, there are multiple side peaks in the auto-correlation function of the BOC modulated signal, which will make the acquisition ambiguous. In this paper, a new unambiguous acquisition algorithm was proposed to solve this problem. According to the characteristics of the correlation function of BOC unit, the side-peak cancellation was finally achieved by multiplying a new function after the half-chip shift and the code with polarity reversed. Simulation results show that the algorithm proposed in this paper can mitigate the interference of the side peak, reduce the main peak span to half-chip width, and acquire the same sensitivity as the ASPeCT method.However, the peak-to-average ratio is increased by about 10% and the computational complexity is reduced by 40%.

Soft Clustering Node Split Hierarchical Model

LUO Sen-lin, SUN Zhi-peng, PAN Li-min

2020, 40(3): 305-309. doi: 10.15918/j.tbit1001-0645.2018.116

Abstract(1017) PDF(374)

Abstract:
Aiming at the structural redundancy and error migration existing in the classification decision tree algorithm, a soft clustering node split hierarchical model was proposed. Through the decision-making model at the leaf nodes and the method of splitting nodes by soft clustering, the efficient partitioning of the sample space was realized, and a simplified hierarchical model was generated. Using the hierarchical discriminant method, samples were predicted with weighted summation methods from the leaf nodes to the root node of hierarchical structure model to reduce the effect of model structure on classification performance, and to improve the model's ability in discriminant errors adjustment. Compared with CART, ID3 and C4.5, the model proposed by the method is simple and showes the best classification performance on two data sets, F₁-measure is 0.53 and 0.38 respectively. The experimental result indicates the soft clustering node split hierarchical model can avoid the redundant structure and alleviate the problem of error migration.

Rumor Detection in Microblogs Based on Topic and Prevention Model

MA Ming, LIU Yun, LIU Di-jun, BAI Jian

2020, 40(3): 310-315. doi: 10.15918/j.tbit1001-0645.2018.384

Abstract(1151) PDF(383)

Abstract:
In view of the difficulty in extracting features of Weibo's short texts and the existence of a large number of officially certified microblogs that had not been used efficiently, a microblog rumors detection method was proposed based on topics and prevention model. Firstly, the official rumors were extracted and categorized according to the subject and were organized according to the user, spread frame and content characters, forming the subsets of official rumors based on a certain topic. And then, the similarity between the microblog and the official rumors with an identical topic was calculated. Merging the values with the traditional features, the result was taken as statistical features put into supervised machine learning. Finally, some experiments were carried out to validate the detection method. The results show that, compared with the traditional supervised machine learning, the method can improve the performance of Weibo rumors detection by about 3%, and can achieve rumor prevention.

A Fast and Robust Image Registration Algorithm Based on Contrast Harris

WU Yi-quan, XIE Fen

2020, 40(3): 316-324. doi: 10.15918/j.tbit1001-0645.2018.094

Abstract(1019) PDF(444)

Abstract:
In order to further improve the robustness, speed and adaptability of the image registration algorithm, a fast and robust image registration algorithm based on contrast Harris was proposed. Firstly, the contrast of the block image was calculated according to the difference of the gray value between the central pixel and its neighborhood pixels, and the threshold of the corner detection was determined adaptively. The pseudo corner points were removed by the gray similarity. Then the corner points were detected in the constructed scale space. As a result, the problems were solved, such as scale sensitive of corner points extracted with Harris algorithm, manual setting of threshold, existence of pseudo corner points, uneven distribution. Finally, the partial mismatched pairs of matched points were removed by slope and distance constraint and the matched pairs were finely aligned by random sample consensus. The experimental results show that, compared with four registration algorithms, the proposed registration algorithm possesses better robustness to JPEG compression, blurred images, visual angle, illumination, rotation and scale changes. The accuracy of registration is higher, the degree of adaptation is stronger and the time of registration can be reduced significantly.

Phase Pattern Characteristics of Frequency Diversity Array Radar Beam

GE Jia-ang, XIE Jun-wei, ZHANG Hao-wei, FENG Xiao-yu, ZHANG Jing

2020, 40(3): 325-331. doi: 10.15918/j.tbit1001-0645.2018.144

Abstract(1109) PDF(387)

Abstract:
In this paper,the phase pattern characteristics of the frequency diversity array(FDA)radar beam were studied.Since the frequency increment was introduced between the array elements,the FDA radar transmitting beam pattern showed two-dimension dependence on the angle and distance,the spatial beam direction changed with the distance,producing the phenomenon of bending,however,the phase pattern of the FDA radar did not show this characteristic.In this paper,two modeling methods,the phase distribution algorithm of FDA beam and Euler's formula,were proposed to establish the FDA beam phase distribution model firstly.Simulating and analyzing the two modeling methods,the Euler's formula was confirmed to be fit for studying the phase distribution of the FDA beam.Based on the optimal model,the phase distribution characteristics of the contour line,equiangular line and isometry line were simulated and analyzed,and thus,the in-phase wavefront of FDA beam were determined.The theoretical analysis and simulation results show that the phase distribution of the FDA beam does not produce the bending phenomenon compared with the phased array,and the distribution characteristic is basically the same as the phased array.

Design and Implementation of Wideband High-Speed Adaptive Coding and Modulation Modem

SHI De-sheng, WU Nan, WANG Hua, LI Zhi-xin, KUANG Jing-ming

2020, 40(3): 332-338. doi: 10.15918/j.tbit1001-0645.2018.688

Abstract(1036) PDF(360)

Abstract:
Adaptive broadband modem is achieved by that, the receiver signals the estimated channel quality via an available return channel to gateway to select the best modulation and coding scheme to adapt the channel change timely. In this paper, some key algorithms were studied for the adaptive broadband modem system, including the algorithm for carrier recovery, SNRs estimation, frame synchronization, and adaptive threshold switching. The architecture and hardware implementation schemes of the wideband adaptive coding and modulation demodulator were presented. The traditional hardware realization structure was improved for carrier frequency recovery and high-order modulations de-mapping based on soft decision. Performance of the implemented modem was tested and analyzed. The test results show that the prototype can work normally at symbol rates from 2 MS/s to 45 MS/s. The difference between the BER performance of base band loop and the theoretical limit is less than 0.2 dB, the difference between the BER performance of the intermediate frequency loop and the theoretical limit is less than 1 dB. The system link adaptive algorithm can track and match the imitative rain-field 0.65 dB/s channel attenuation well.

Research on Frequency Domain CFAR Detection Algorithm for LFMCW Signal in Non-Stationary Noise Environment

SU Yu, JIANG De-fu

2020, 40(3): 339-346. doi: 10.15918/j.tbit1001-0645.2019.163

Abstract(947) PDF(496)

Abstract:
In order to improve the real-time detection capability of an electronic reconnaissance system for linear frequency modulation continuous wave(LFMCW)signals in non-stationary noise environment, a low complexity algorithm for segmental detection of signals was proposed. Setting the width of the window function based on the maximum chirp rate assumption, and dividing the intercepted signal evenly into multiple segments, a short-time harmonic model was established in each time period, and the signal was weighted for discrete Fourier transform with multiple orthogonal window functions. On this basis, a detection model was derived according with the F distribution. The model was designed to be independent of noise power, so the constant false alarm rate (CFAR) detection of signals in non-stationary noise environment could be carried out without statistical noise power before detection. The parameters that affect the performance of the algorithm were simulated and analyzed, and compared with the single window detection algorithm to verify the excellent detection performance of the algorithm in non-stationary noise environment.

A New Approach to the Solution of Lyapunov Equation

MIRAU Silas, SONG Yang, SUN Hua-fei

2020, 40(3): 347-350. doi: 10.15918/j.tbit1001-0645.2018.356

Abstract(1210) PDF(424)

Abstract:
A new approach was proposed based on the Log-Euclidean metric to solve the Lyapunov equation. First, the origin of Lyapunov equation was introduced. Then the Riemannian metrics on a manifold of symmetric positive definite matrices and the geodesic distance function under Log-Euclidean metric were presented. Last, the iterative formula for the solution to Lyapunov equation was obtained, and some simulation results were shown.

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