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Research Progress of the Sampling Theorem Associated with the Fractional Fourier Transform 分数傅立叶变换采样定理的研究进展
Journal of Beijing Institute of Technology (English Edition) Pub Date : 2021-09-30 DOI: 10.15918/J.JBIT1004-0579.2021.041
Jinming Ma, R. Tao
{"title":"Research Progress of the Sampling Theorem Associated with the Fractional Fourier Transform","authors":"Jinming Ma, R. Tao","doi":"10.15918/J.JBIT1004-0579.2021.041","DOIUrl":"https://doi.org/10.15918/J.JBIT1004-0579.2021.041","url":null,"abstract":"Sampling is a bridge between continuous-time and discrete-time signals, which is important to digital signal processing. The fractional Fourier transform (FrFT) that serves as a generalization of the FT can characterize signals in multiple fractional Fourier domains, and therefore can provide new perspectives for signal sampling and reconstruction. In this paper, we review recent developments of the sampling theorem associated with the FrFT, including signal reconstruction and fractional spectral analysis of uniform sampling, nonuniform samplings due to various factors, and sub-Nyquist sampling, where bandlimited signals in the fractional Fourier domain are mainly taken into consideration. Moreover, we provide several future research topics of the sampling theorem associated with the FrFT.","PeriodicalId":39252,"journal":{"name":"Journal of Beijing Institute of Technology (English Edition)","volume":"30 1","pages":"195-204"},"PeriodicalIF":0.0,"publicationDate":"2021-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48497265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
A Random Nonstationary Pulse Train Model 随机非平稳脉冲序列模型
Journal of Beijing Institute of Technology (English Edition) Pub Date : 2021-09-30 DOI: 10.15918/J.JBIT1004-0579.2021.055
L. Cohen
{"title":"A Random Nonstationary Pulse Train Model","authors":"L. Cohen","doi":"10.15918/J.JBIT1004-0579.2021.055","DOIUrl":"https://doi.org/10.15918/J.JBIT1004-0579.2021.055","url":null,"abstract":"A simple and mathematically tractable model of a nonstationary process is developed. The process is the sum of waves where the parameters of the waves are random. Explicit expressions for the mean and autocorrelation function at each position as a function of time are obtained. In the case of infinite time, the model evolves into a stationary process. The time-frequency distribution at each position is also obtained. An explicit example is given where the initial waves are Gaussian. The case where there is dispersion in the propagation is also discussed.","PeriodicalId":39252,"journal":{"name":"Journal of Beijing Institute of Technology (English Edition)","volume":"30 1","pages":"228-237"},"PeriodicalIF":0.0,"publicationDate":"2021-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43395141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Emergency Control Strategy for Distributed Skid-Steering Vehicles 分布式滑转向车辆的应急控制策略
Journal of Beijing Institute of Technology (English Edition) Pub Date : 2021-06-30 DOI: 10.15918/J.JBIT1004-0579.20109
Xueyuan Li, Chen Jiang, Jin Chen, Yu Zhang
{"title":"Emergency Control Strategy for Distributed Skid-Steering Vehicles","authors":"Xueyuan Li, Chen Jiang, Jin Chen, Yu Zhang","doi":"10.15918/J.JBIT1004-0579.20109","DOIUrl":"https://doi.org/10.15918/J.JBIT1004-0579.20109","url":null,"abstract":"Based on the lateral properties of tire and the input variable of braking force, a 2-DOF lateral dynamic analytical model of wheel skid-steered vehicle is established in this paper. Based on the model, the steady-state yaw velocity gain and steering radius in the process of skid-steering are analyzed theoretically. Then the control boundary and distribution strategy of the braking force are given. An all-terrain vehicle was used to carry out a real vehicle test, and verified that the strategy can ensure the safe steering of the vehicle when the driving force is lost.","PeriodicalId":39252,"journal":{"name":"Journal of Beijing Institute of Technology (English Edition)","volume":"30 1","pages":"75-81"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42583622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Design and Analysis of a Soft Actuator Based on Cable-Driven Method 基于索驱动法的软执行器设计与分析
Journal of Beijing Institute of Technology (English Edition) Pub Date : 2021-06-30 DOI: 10.15918/J.JBIT1004-0579.20081
L. Bai, Hao Yan
{"title":"Design and Analysis of a Soft Actuator Based on Cable-Driven Method","authors":"L. Bai, Hao Yan","doi":"10.15918/J.JBIT1004-0579.20081","DOIUrl":"https://doi.org/10.15918/J.JBIT1004-0579.20081","url":null,"abstract":"In order to improve the performance of soft actuators, a novel soft actuator is designed, which is driven by a cable. Firstly, the operating principle of this soft actuator is illustrated. Compared with the traditional soft actuators driven by cables, the new designed structure can achieve the forward and reverse bending movements, relying on a single flexible shaft. Secondly, with the help of silicone rubber and 3D printed molds, a fabrication process of the actuator is developed. Thirdly, to verify the bending property, the finite element method is proposed. Some key factors causing the problems of repeatability and hysteresis are analyzed with the results of simulation and experiments. Finally, the grasping tests are carried out, and the integrated soft robotic gripper demonstrates the ability of grasping objects in different shapes and sizes. Due to its high universality and flexibility, this soft actuator shows great potential in industrial manufacturing and medical equipment.","PeriodicalId":39252,"journal":{"name":"Journal of Beijing Institute of Technology (English Edition)","volume":"30 1","pages":"179-186"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48622726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Cellular Property of the Detonation Wave of Pre-mixed Methane-Oxygen in Annular Tube 环形管内预混甲烷-氧气爆震波的细胞特性
Journal of Beijing Institute of Technology (English Edition) Pub Date : 2021-06-30 DOI: 10.15918/J.JBIT1004-0579.20092
Niu Shuzhen, Yinghua Zhang, Zhao Huanjuan, Yan Yiran
{"title":"Cellular Property of the Detonation Wave of Pre-mixed Methane-Oxygen in Annular Tube","authors":"Niu Shuzhen, Yinghua Zhang, Zhao Huanjuan, Yan Yiran","doi":"10.15918/J.JBIT1004-0579.20092","DOIUrl":"https://doi.org/10.15918/J.JBIT1004-0579.20092","url":null,"abstract":"In order to investigate the detonation propagation in the annular tube, the experiments are conducted with methane-oxygen mixture. Annual tubes with different inner diameter D0 were configured and smoked foils were fixed on both outer wall and the inner wall of the annular tube to record the detonation structure. Firstly, it is found that transverse wave modes on both outer wall and the inner wall of the annular tube increase with increasing initial pressure and inner diameter of the channel. In addition, the measurement of angle between the transverse wave and the tube axis disagrees acoustic theory within the error range. In the results, the angle and the cell size changes less with pressure and more with different position of the channel, demonstrating the strongly dependence of the tube geometric. What’s more, the trajectories of right-running transverse wave were traced and some of the transverse waves disappeared in the polycarbonate tube, because the initial energy of different transverse waves are different and the energy required to sustain the transverse vibration of spinning detonation must be derived from the chemical energy release at the front.","PeriodicalId":39252,"journal":{"name":"Journal of Beijing Institute of Technology (English Edition)","volume":"30 1","pages":"225-235"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47162669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Measurement Model and Dynamic Performance Analysis of Inlet Electrostatic Sensor on Aircraft Engine 航空发动机进气静电传感器的测量模型及动态性能分析
Journal of Beijing Institute of Technology (English Edition) Pub Date : 2021-06-30 DOI: 10.15918/J.JBIT1004-0579.20057
Zheng-mao Feng, Yu Fu, Jinglin Wang, Shen Yong, Cao Liang, Hongfu Zuo
{"title":"Measurement Model and Dynamic Performance Analysis of Inlet Electrostatic Sensor on Aircraft Engine","authors":"Zheng-mao Feng, Yu Fu, Jinglin Wang, Shen Yong, Cao Liang, Hongfu Zuo","doi":"10.15918/J.JBIT1004-0579.20057","DOIUrl":"https://doi.org/10.15918/J.JBIT1004-0579.20057","url":null,"abstract":"Online electrostatic monitoring technology, which is equipped with foreknowledge information for aircraft engine faults, can effectively enhance flight safety and reduce costs. This paper provides a theoretical foundation for inlet electrostatic sensor design, which is the key issue of this technology. First, the induced principle of inlet electrostatic sensor is analyzed. Then, factors affecting spatial sensitivity distribution are quantitatively analyzed to obtain the sensitivity distribution frequency spectrum and dynamic response performance. This sensor is equivalent to a low-pass spatial filter. Results show that bandwidth changes depending on particle speed, radial position, and axial length. The optimal ring size is designed accordingly, considering sensor sensitivity, uniformity, mechanical processing, and installation.","PeriodicalId":39252,"journal":{"name":"Journal of Beijing Institute of Technology (English Edition)","volume":"30 1","pages":"202-209"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42490773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Analysis and Classification of Speech Imagery EEG Based on Chinese Initials 基于汉语声母的语音图像脑电图分析与分类
Journal of Beijing Institute of Technology (English Edition) Pub Date : 2021-06-30 DOI: 10.15918/J.JBIT1004-0579.20095
Yongsheng Zhao, Yingzi Liu, Y. Gao
{"title":"Analysis and Classification of Speech Imagery EEG Based on Chinese Initials","authors":"Yongsheng Zhao, Yingzi Liu, Y. Gao","doi":"10.15918/J.JBIT1004-0579.20095","DOIUrl":"https://doi.org/10.15918/J.JBIT1004-0579.20095","url":null,"abstract":"Brain-computer interfaces (BCI) can provide external information communication for people with normal thinking but impaired motor functions. For patients with language disorders, speech imagery BCIs make it possible to communicate normally. However, there are few studies on Chinese speech imagery at present. Almost all studies employed fixed experimental content, without considering the diversity in subjects. With the purpose of improving the effect of a Chinese speech imagery BCI system, a novel experiment of Chinese initials imagery was designed. The experiment is divided into two parts. A preliminary experiment used to select content for subjects. Formal experiment-specific experimental content was designed for subjects. After preprocessing, feature extraction was carried out by common spatial patterns (CSP) and discrete wavelet transform (DWT), and then a support vector machine (SVM) and extreme learning machine (ELM) were used for classification. Finally, the best performance was obtained by the model using DWT and ELM with a highest accuracy of 73.04%. This study shows that the novel experiment is feasible and can potentially extend the capability of utilizing speech imagery in future BCI applications.","PeriodicalId":39252,"journal":{"name":"Journal of Beijing Institute of Technology (English Edition)","volume":"30 1","pages":"44-51"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42530748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Improved Chroma Resampling Algorithm Based on Interpolation Method 基于插值法的改进色度重采样算法
Journal of Beijing Institute of Technology (English Edition) Pub Date : 2021-06-30 DOI: 10.15918/J.JBIT1004-0579.20120
Shiwei Ren, Qiuchen Ji, Wei Gao, Yue Ma
{"title":"Improved Chroma Resampling Algorithm Based on Interpolation Method","authors":"Shiwei Ren, Qiuchen Ji, Wei Gao, Yue Ma","doi":"10.15918/J.JBIT1004-0579.20120","DOIUrl":"https://doi.org/10.15918/J.JBIT1004-0579.20120","url":null,"abstract":"An improved algorithm based on bilinear interpolation was proposed. It could deal with the shortcoming of chroma component information loss in the original video image chroma resampling algorithm. With the bilinear interpolation method, the chroma component matrix in the YCbCr color space was scaled in both the horizontal and vertical directions. It could reduce information loss while meeting the corresponding standard data format. The new algorithm could retain more information from the source image’s color, which improved image recovery. In addition, the paper proposed a new format with a higher compression ratio on the basis of ensuring visual performance. Experimental results showed that, compared with the original chroma resampling algorithm, the processing result of the improved algorithm had a significant improvement in the performance of parameters such as composite peak signal noise ratio (CPSNR).","PeriodicalId":39252,"journal":{"name":"Journal of Beijing Institute of Technology (English Edition)","volume":"30 1","pages":"11-17"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47759927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Ship Target Detection and Recognition Method on Sea Surface Based on Multi-Level Hybrid Network 基于多级混合网络的海面舰船目标检测与识别方法
Journal of Beijing Institute of Technology (English Edition) Pub Date : 2021-06-30 DOI: 10.15918/J.JBIT1004-0579.20141
Zongling Li, Qingjun Zhang, Teng Long, Baojun Zhao
{"title":"Ship Target Detection and Recognition Method on Sea Surface Based on Multi-Level Hybrid Network","authors":"Zongling Li, Qingjun Zhang, Teng Long, Baojun Zhao","doi":"10.15918/J.JBIT1004-0579.20141","DOIUrl":"https://doi.org/10.15918/J.JBIT1004-0579.20141","url":null,"abstract":"This paper proposes a method of ship detection and recognition based on a multi-level hybrid network, designing a noise reducing and smoothing image enhancement algorithm based on multi-level two-dimensional template filter and three-layer pyramid structure. This work constructs an adaptive segmentation detection and ultra-lightweight target classification network model combining global and local image gray statistics. With a combination of traditional image processing and deep learning methods, the demand for computing and storage resources is reduced greatly. This method can detect and recognize the ship targets near the sea-sky-level quickly and has been verified by real flight camera data, and the accuracy rate is more than 90%. In comparison to the Tiny YOLOV3 network, the accuracy rate is reduced by 5%, but the calculation efficiency is increased by 50 times, and the parameters are reduced by 550 times.","PeriodicalId":39252,"journal":{"name":"Journal of Beijing Institute of Technology (English Edition)","volume":"30 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44635320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 7
Structural Optimization of Anti-Interference of Small Ducted Aircraft 小型导管飞行器的抗干扰结构优化
Journal of Beijing Institute of Technology (English Edition) Pub Date : 2021-06-30 DOI: 10.15918/J.JBIT1004-0579.20027
X. Zhao, Yanxuan Wu, Wei Zhang
{"title":"Structural Optimization of Anti-Interference of Small Ducted Aircraft","authors":"X. Zhao, Yanxuan Wu, Wei Zhang","doi":"10.15918/J.JBIT1004-0579.20027","DOIUrl":"https://doi.org/10.15918/J.JBIT1004-0579.20027","url":null,"abstract":"The small ducted type aircraft has small volume and light weight, and the ducted body occupies a large proportion in the pneumatic surface of the whole machine. The presence of the ducted causes the aircraft to produce momentum resistance and additional resistance moments under the side wind/gust interference. The effect is to produce the rise torque that causes the aircraft to “rise up”, which makes the aircraft more susceptible to side wind/gust interference and deviates from the stable equilibrium state. Therefore, compared with the open rotor unmanned aerial vehicle(UAV), the small ducted aircraft itself has worse anti-interference ability. The above analysis shows that the ring structure of the culvert makes the aircraft itself more vulnerable to the side wind/gust interference in the environment and forms an additional resistance moment. Therefore, how to improve the inherent anti-jamming capability of the small ducted aircraft through structural optimization is the problem to be solved in this paper.","PeriodicalId":39252,"journal":{"name":"Journal of Beijing Institute of Technology (English Edition)","volume":"30 1","pages":"196-201"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48464905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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