http://journal.bit.edu.cn/jbit/ JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY blgywb@bit.edu.cn blgywb@bit.edu.cn en blgywb@bit.edu.cn 1004-0579 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20141?pageType=en Zongling Li, Qingjun Zhang, Teng Long, Baojun Zhao 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 1-10. Zongling Li, Qingjun Zhang, Teng Long, Baojun Zhao 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 1-10. Ship Target Detection and Recognition Method on Sea Surface Based on Multi-Level Hybrid Network Zongling Li, Qingjun Zhang, Teng Long, Baojun Zhao 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 1-10. article doi:10.15918/j.jbit1004-0579.20141 10.15918/j.jbit1004-0579.20141 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20141?pageType=en 1 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20120?pageType=en Shiwei Ren, Qiuchen Ji, Wei Gao, Yue Ma 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). JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 11-17. Shiwei Ren, Qiuchen Ji, Wei Gao, Yue Ma 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). JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 11-17. Improved Chroma Resampling Algorithm Based on Interpolation Method Shiwei Ren, Qiuchen Ji, Wei Gao, Yue Ma 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 11-17. article doi:10.15918/j.jbit1004-0579.20120 10.15918/j.jbit1004-0579.20120 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20120?pageType=en 11 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20103?pageType=en Jihua Lu, Yuhang Yin, Tiankai He, Dapeng Fu, Peng Yin, Xuanhao Ni A combined prime interleaving design is proposed for a spreading spectrum system with frequency hopping (FH), direct sequence (DS), and coherent detection. Obtaining a lower bit error rate (BER) is the object of classical anti-jamming communication systems. By employing combined prime interleaving, we get lower BER results compared with conventional block interleaving under the same signal-to-noise ratio (SNR) level by merit of superior storage and interleaving effects. Prime interleaving requires only one row to interleave while both block and random interleaving require the whole interleaving matrix, which results in lower latency time. Simulations reveal that the proposed combined interleaving design has comparative performance with random interleaving, and has advantages in transmission reliability and system delay. Moreover, the prime interleaving outputs slightly worse BER compared with random interleaving over the same SNR. Compared with random interleaving, the proposed combined interleaving has 0.25 dB worse SNR over the same average BER. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 18-22. Jihua Lu, Yuhang Yin, Tiankai He, Dapeng Fu, Peng Yin, Xuanhao Ni A combined prime interleaving design is proposed for a spreading spectrum system with frequency hopping (FH), direct sequence (DS), and coherent detection. Obtaining a lower bit error rate (BER) is the object of classical anti-jamming communication systems. By employing combined prime interleaving, we get lower BER results compared with conventional block interleaving under the same signal-to-noise ratio (SNR) level by merit of superior storage and interleaving effects. Prime interleaving requires only one row to interleave while both block and random interleaving require the whole interleaving matrix, which results in lower latency time. Simulations reveal that the proposed combined interleaving design has comparative performance with random interleaving, and has advantages in transmission reliability and system delay. Moreover, the prime interleaving outputs slightly worse BER compared with random interleaving over the same SNR. Compared with random interleaving, the proposed combined interleaving has 0.25 dB worse SNR over the same average BER. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 18-22. Anti-Interference Design Based on Prime Interleaving for a Combined FH and DS Spreading Spectrum System Jihua Lu, Yuhang Yin, Tiankai He, Dapeng Fu, Peng Yin, Xuanhao Ni 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 18-22. article doi:10.15918/j.jbit1004-0579.20103 10.15918/j.jbit1004-0579.20103 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20103?pageType=en 18 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20094?pageType=en Xiaolin Dai, Xuhong Sun, Jiacheng He, Anxu Li, Dawei Gong In this work, a Rao-Blackwellized particle filter simultaneous localization and mapping based on grey wolf optimizer (called GWO-RBPF) is proposed. The proposed method aims to improve the accuracy of the mapping while maintaining the number of particles. GWO-RBPF utilizes the local exploration and global development ability of the grey wolf optimizer to improve the estimation performance of the Rao-Blackwellized particle filter, so that the low-weight particles can approach high-weight particles. Meanwhile, the pose information of the particles is optimized by the grey wolf optimizer. The proposed method is applied to the benchmark datasets and real-world datasets. The experimental results show that our method outperforms conventional method in terms of map accuracy versus the number of particles. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 23-34. Xiaolin Dai, Xuhong Sun, Jiacheng He, Anxu Li, Dawei Gong In this work, a Rao-Blackwellized particle filter simultaneous localization and mapping based on grey wolf optimizer (called GWO-RBPF) is proposed. The proposed method aims to improve the accuracy of the mapping while maintaining the number of particles. GWO-RBPF utilizes the local exploration and global development ability of the grey wolf optimizer to improve the estimation performance of the Rao-Blackwellized particle filter, so that the low-weight particles can approach high-weight particles. Meanwhile, the pose information of the particles is optimized by the grey wolf optimizer. The proposed method is applied to the benchmark datasets and real-world datasets. The experimental results show that our method outperforms conventional method in terms of map accuracy versus the number of particles. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 23-34. Improved Grid-Based Rao-Blackwellized Particle Filter SLAM Based on Grey Wolf Optimizer Xiaolin Dai, Xuhong Sun, Jiacheng He, Anxu Li, Dawei Gong 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 23-34. article doi:10.15918/j.jbit1004-0579.20094 10.15918/j.jbit1004-0579.20094 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20094?pageType=en 23 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20112?pageType=en Limin Wu, Huihua Feng, Ziwei Zhang, Yao Wang, Boru Jia, Xiaodong Yan A numerical model for energy flow calculation of the free piston internal combustion power system (FPICPS) was established, which was compared with the traditional internal combustion engine (IC engine) with the same structure and input conditions. The piston motion characteristics and energy transfer process of FPICPS are studied by numerical simulation method. The results show that the changes of cylinder pressure, temperature and piston motion characteristics of free piston engine (FP engine) lag behind those of IC engine, and the piston peak acceleration of the FP engine is approximately 2.8 times that of IC engine. The proportion of compression stroke and expansion stroke of IC engine is basically the same, while the expansion stroke of FP engine only accounts for 41.6% of the whole operating cycle. FP engine have obvious advantages in heat transfer and air leakage loss, their percentages are 11.82% and 0.83%, respectively. The percentage of indicated power in FP engine and IC engine are 27.44% and 25.98%, respectively. And 79.64% of FP engine indicated power is converted into the motor electromagnetic energy. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 35-43. Limin Wu, Huihua Feng, Ziwei Zhang, Yao Wang, Boru Jia, Xiaodong Yan A numerical model for energy flow calculation of the free piston internal combustion power system (FPICPS) was established, which was compared with the traditional internal combustion engine (IC engine) with the same structure and input conditions. The piston motion characteristics and energy transfer process of FPICPS are studied by numerical simulation method. The results show that the changes of cylinder pressure, temperature and piston motion characteristics of free piston engine (FP engine) lag behind those of IC engine, and the piston peak acceleration of the FP engine is approximately 2.8 times that of IC engine. The proportion of compression stroke and expansion stroke of IC engine is basically the same, while the expansion stroke of FP engine only accounts for 41.6% of the whole operating cycle. FP engine have obvious advantages in heat transfer and air leakage loss, their percentages are 11.82% and 0.83%, respectively. The percentage of indicated power in FP engine and IC engine are 27.44% and 25.98%, respectively. And 79.64% of FP engine indicated power is converted into the motor electromagnetic energy. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 35-43. Theoretical Modeling and Energy Conversion Process of Free Piston Internal Combustion Power System Limin Wu, Huihua Feng, Ziwei Zhang, Yao Wang, Boru Jia, Xiaodong Yan 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 35-43. article doi:10.15918/j.jbit1004-0579.20112 10.15918/j.jbit1004-0579.20112 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20112?pageType=en 35 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20095?pageType=en Yongsheng Zhao, Ying Liu, Yunlong Gao 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 44-51. Yongsheng Zhao, Ying Liu, Yunlong Gao 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 44-51. Analysis and Classification of Speech Imagery EEG Based on Chinese Initials Yongsheng Zhao, Ying Liu, Yunlong Gao 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 44-51. article doi:10.15918/j.jbit1004-0579.20095 10.15918/j.jbit1004-0579.20095 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20095?pageType=en 44 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20101?pageType=en Lijun Hao, Chunxiao Hao, Liang Ji, Hang Yin, Weiqiang Zhang, Xiaohu Wang, Jin Liu In this study, an instantaneous vehicle emission model was developed and validated. A group of emission regression functions with vehicle speed and VSP as variables was established using the multiple linear regression method and embedded in the instantaneous emission model to predict vehicle emissions. The inputs of the instantaneous vehicle emission model consist of the driving cycle, vehicle parameters and accessories use, all of which are used to calculate the instantaneous vehicle specific power (VSP). The simulated results of the emission model are second-by-second emission rates, emission factors and fuel consumption over the target driving cycle. The predicted emissions as well as fuel consumption of four passenger cars were very close to the tested emission data, and the prediction errors of emission factors and fuel consumptions were acceptable. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 52-63. Lijun Hao, Chunxiao Hao, Liang Ji, Hang Yin, Weiqiang Zhang, Xiaohu Wang, Jin Liu In this study, an instantaneous vehicle emission model was developed and validated. A group of emission regression functions with vehicle speed and VSP as variables was established using the multiple linear regression method and embedded in the instantaneous emission model to predict vehicle emissions. The inputs of the instantaneous vehicle emission model consist of the driving cycle, vehicle parameters and accessories use, all of which are used to calculate the instantaneous vehicle specific power (VSP). The simulated results of the emission model are second-by-second emission rates, emission factors and fuel consumption over the target driving cycle. The predicted emissions as well as fuel consumption of four passenger cars were very close to the tested emission data, and the prediction errors of emission factors and fuel consumptions were acceptable. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 52-63. Statistical Modeling of Exhaust Emissions from Gasoline Passenger Cars Lijun Hao, Chunxiao Hao, Liang Ji, Hang Yin, Weiqiang Zhang, Xiaohu Wang, Jin Liu 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 52-63. article doi:10.15918/j.jbit1004-0579.20101 10.15918/j.jbit1004-0579.20101 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20101?pageType=en 52 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20102?pageType=en Guangxin Wang, Lili Zhu, Jiaqi Yue, Yuting Shen A calculation formula of boundary size is proposed to analyze the conjugate meshing of nutation face gear transmission by using the condition of no tip change and root undercutting. Furthermore, the influence of tooth shape design parameters on the boundary dimension of nutation face gears is studied. Based on the meshing principle of spacial gears, the conjugate conditions of the “face-face” gear pair are derived, the calculation method of discrete points of tooth surface is given, and the three-dimensional model of the nutation face gear transmission device is also established, which helps the design and manufacturing of high-quality nutation face gear transmissions and improves its transmission performance. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 64-74. Guangxin Wang, Lili Zhu, Jiaqi Yue, Yuting Shen A calculation formula of boundary size is proposed to analyze the conjugate meshing of nutation face gear transmission by using the condition of no tip change and root undercutting. Furthermore, the influence of tooth shape design parameters on the boundary dimension of nutation face gears is studied. Based on the meshing principle of spacial gears, the conjugate conditions of the “face-face” gear pair are derived, the calculation method of discrete points of tooth surface is given, and the three-dimensional model of the nutation face gear transmission device is also established, which helps the design and manufacturing of high-quality nutation face gear transmissions and improves its transmission performance. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 64-74. Conjugate Meshing Analysis of Nutation Drive with Face Gears Guangxin Wang, Lili Zhu, Jiaqi Yue, Yuting Shen 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 64-74. article doi:10.15918/j.jbit1004-0579.20102 10.15918/j.jbit1004-0579.20102 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20102?pageType=en 64 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20109?pageType=en Xueyuan Li, Chenze Jiang, Jin Chen, Yu Zhang 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 75-81. Xueyuan Li, Chenze Jiang, Jin Chen, Yu Zhang 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 75-81. Emergency Control Strategy for Distributed Skid-Steering Vehicles Xueyuan Li, Chenze Jiang, Jin Chen, Yu Zhang 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 75-81. article doi:10.15918/j.jbit1004-0579.20109 10.15918/j.jbit1004-0579.20109 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20109?pageType=en 75 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20110?pageType=en Layue Zhao, Minggang Du, Yang Yang, Jixuan Bian An optimized hob to increase the bending strength of involute gears by changing the root fillet profile is presented in this paper. The maximum bending stress which determines the service life of a gear in many applications depends on stress concentration caused by the gear root fillet. Better control of the root fillet can result in gears with higher bending strength. The optimised hob tool is a modification based on the standard hob tool, with constant normal base pitch, but a different pressure angle and module, which will generate a different gear root fillet area. The comparison analysis demonstrates that the gear generated by the optimised hob has higher bending strength than that generated by the common standard hob. For analysis and validation of results, three methods of predicting bending stress - ISO standard, three-dimensional tooth contact analysis (3D-TCA) method, and finite element analysis (FEA) are applied and discussed. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 82-91. Layue Zhao, Minggang Du, Yang Yang, Jixuan Bian An optimized hob to increase the bending strength of involute gears by changing the root fillet profile is presented in this paper. The maximum bending stress which determines the service life of a gear in many applications depends on stress concentration caused by the gear root fillet. Better control of the root fillet can result in gears with higher bending strength. The optimised hob tool is a modification based on the standard hob tool, with constant normal base pitch, but a different pressure angle and module, which will generate a different gear root fillet area. The comparison analysis demonstrates that the gear generated by the optimised hob has higher bending strength than that generated by the common standard hob. For analysis and validation of results, three methods of predicting bending stress - ISO standard, three-dimensional tooth contact analysis (3D-TCA) method, and finite element analysis (FEA) are applied and discussed. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 82-91. Research on an Optimized Hob to Increase the Bending Strength of Involute Gears by Changing the Root Fillet Profile Layue Zhao, Minggang Du, Yang Yang, Jixuan Bian 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 82-91. article doi:10.15918/j.jbit1004-0579.20110 10.15918/j.jbit1004-0579.20110 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20110?pageType=en 82 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20125?pageType=en Fan Zhi, Yigang Zhang, Xiang Zhou, Jing Zhang, Wu Lu A new model-based method is proposed to improve the moving performance of the planar near-field scanning frame. First, the geometric error model of the planar near-field scanning frame is established based on homogeneous coordinate transformation and multi-body system theory. Then, 21 underdetermined parameters in the geometric error model are derived by using the laser interferometer measurement system with unique light path and configurations. Based on the established error model, online error compensation in combination with structural optimization are proposed to reduce geometric errors efficiently. Finally, the proposed method is utilized to derive a novel planar near-field scanning frame. Scanning planeness in <i<XY</i< plane with <i<z</i< = 10 mm is calculated by using the Monte Carlo simulation method, results show that the calculated scanning planeness satisfies demands for the planar near-filed scanning frame, which validates the effectiveness of the proposed method. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 92-102. Fan Zhi, Yigang Zhang, Xiang Zhou, Jing Zhang, Wu Lu A new model-based method is proposed to improve the moving performance of the planar near-field scanning frame. First, the geometric error model of the planar near-field scanning frame is established based on homogeneous coordinate transformation and multi-body system theory. Then, 21 underdetermined parameters in the geometric error model are derived by using the laser interferometer measurement system with unique light path and configurations. Based on the established error model, online error compensation in combination with structural optimization are proposed to reduce geometric errors efficiently. Finally, the proposed method is utilized to derive a novel planar near-field scanning frame. Scanning planeness in <i<XY</i< plane with <i<z</i< = 10 mm is calculated by using the Monte Carlo simulation method, results show that the calculated scanning planeness satisfies demands for the planar near-filed scanning frame, which validates the effectiveness of the proposed method. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 92-102. New Model-Based Method to Improve the Moving Performance of the Planar Near-Field Scanning Frame Fan Zhi, Yigang Zhang, Xiang Zhou, Jing Zhang, Wu Lu 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 92-102. article doi:10.15918/j.jbit1004-0579.20125 10.15918/j.jbit1004-0579.20125 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20125?pageType=en 92 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20121?pageType=en Bo Wang, Tao Wang Pneumatic servo systems are affected by nonlinear factors, especially friction between the inner wall of the cylinder and the piston. The limit-cycle oscillation caused by friction can easily result in dead-zone nonlinearity in a pneumatic servo system, reducing the system performance and repeatability. In this study, the impact of friction, which has a negative influence on a pneumatic servo welding system, is effectively reduced by observing and compensating the friction. The system is treated as a pneumatic position/force servo system before and after contact between the welding gun electrodes. A reduced-order observer and a Kalman filter are applied to observe and estimate dynamic and static friction. Then friction is compensated by using feed-forward control. The experimental results show that a steady-state error of within 1.3% is achieved for a step signal. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 103-110. Bo Wang, Tao Wang Pneumatic servo systems are affected by nonlinear factors, especially friction between the inner wall of the cylinder and the piston. The limit-cycle oscillation caused by friction can easily result in dead-zone nonlinearity in a pneumatic servo system, reducing the system performance and repeatability. In this study, the impact of friction, which has a negative influence on a pneumatic servo welding system, is effectively reduced by observing and compensating the friction. The system is treated as a pneumatic position/force servo system before and after contact between the welding gun electrodes. A reduced-order observer and a Kalman filter are applied to observe and estimate dynamic and static friction. Then friction is compensated by using feed-forward control. The experimental results show that a steady-state error of within 1.3% is achieved for a step signal. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 103-110. Observation and Compensation of Friction in a Pneumatic Servo Welding System Bo Wang, Tao Wang 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 103-110. article doi:10.15918/j.jbit1004-0579.20121 10.15918/j.jbit1004-0579.20121 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20121?pageType=en 103 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20104?pageType=en Fuhui Guo, Pingli Lu A fault-tolerant control (FTC) scheme is proposed based on integral sliding mode(ISM) for attitude control of hypersonic re-entry vehicle (HRV) under partial loss of actuator effectiveness. First, the inner/outer loop mathematical model of HRV in the present of actuator failure is given with specific analysis on torque. Then prescribed performance approach is introduced to the ISM controller design by error transformation. Specifically, the transformation error rather than tracking error is chosen as the sliding variable to establish the sliding mode surface and reaching law. As a result, the attitude tracking error of HRV is limited into the expected range. Meanwhile, the transient process and the steady state behavior are both considered. Considering that the unknown fault information of actuator can cause adverse effect on HRV, an extended state observer(ESO) is adopted to estimate the unknown actuator failure. Thus the observer result is served as compensation for the loss of the controlled system performance. Simulation results show that the proposed scheme can fulfil the tracking task with prescribed performance. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 111-120. Fuhui Guo, Pingli Lu A fault-tolerant control (FTC) scheme is proposed based on integral sliding mode(ISM) for attitude control of hypersonic re-entry vehicle (HRV) under partial loss of actuator effectiveness. First, the inner/outer loop mathematical model of HRV in the present of actuator failure is given with specific analysis on torque. Then prescribed performance approach is introduced to the ISM controller design by error transformation. Specifically, the transformation error rather than tracking error is chosen as the sliding variable to establish the sliding mode surface and reaching law. As a result, the attitude tracking error of HRV is limited into the expected range. Meanwhile, the transient process and the steady state behavior are both considered. Considering that the unknown fault information of actuator can cause adverse effect on HRV, an extended state observer(ESO) is adopted to estimate the unknown actuator failure. Thus the observer result is served as compensation for the loss of the controlled system performance. Simulation results show that the proposed scheme can fulfil the tracking task with prescribed performance. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 111-120. Hypersonic Re-entry Vehicle Fault-Tolerant Control Against Actuator Failure via Integral Sliding Mode Fuhui Guo, Pingli Lu 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 111-120. article doi:10.15918/j.jbit1004-0579.20104 10.15918/j.jbit1004-0579.20104 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20104?pageType=en 111 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20098?pageType=en Xiwei Peng, Haiyang Yu, Xiangjie Zhu, Yiran Li Large friction force and large dead zone are two typical nonlinear characteristics of electro-hydraulic proportional valve controlled hydraulic cylinder position control system. Aiming at those characteristics, a dead zone dynamic compensation algorithm is researched in order to reduce the lag time and control error. At the same time, a control strategy of radial basis function (RBF) neural network combined with auto disturbance rejection control (ADRC) is researched according to the impact of different conditions. The experimental result shows that the proposed algorithm improves performance of the electro-hydraulic proportional valve controlled hydraulic cylinder position control system. In positioning control experiment, the overshoot is 0 and the stability error is 0. In tracking control experiment, the lag time is reduced from the original 1.5 s to 0.2 s with no flat top phenomenon and the maximum error was reduced from 20 mm to 3 mm. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 121-128. Xiwei Peng, Haiyang Yu, Xiangjie Zhu, Yiran Li Large friction force and large dead zone are two typical nonlinear characteristics of electro-hydraulic proportional valve controlled hydraulic cylinder position control system. Aiming at those characteristics, a dead zone dynamic compensation algorithm is researched in order to reduce the lag time and control error. At the same time, a control strategy of radial basis function (RBF) neural network combined with auto disturbance rejection control (ADRC) is researched according to the impact of different conditions. The experimental result shows that the proposed algorithm improves performance of the electro-hydraulic proportional valve controlled hydraulic cylinder position control system. In positioning control experiment, the overshoot is 0 and the stability error is 0. In tracking control experiment, the lag time is reduced from the original 1.5 s to 0.2 s with no flat top phenomenon and the maximum error was reduced from 20 mm to 3 mm. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 121-128. Electro-Hydraulic Proportional Position Control Using Auto Disturbance Rejection Based on RBF Neural Network Xiwei Peng, Haiyang Yu, Xiangjie Zhu, Yiran Li 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 121-128. article doi:10.15918/j.jbit1004-0579.20098 10.15918/j.jbit1004-0579.20098 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20098?pageType=en 121 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20003?pageType=en Minfeng Wei, Min Xu, Fengdi Zhang Accurate dynamic state estimation plays an important role in power systems. Although various filtering algorithms, such as unscented Kalman filter (UKF) and particle filter (PF), have been proposed based on phasor measurement units (PMUs), they occupy a huge communication bandwidth without specific concern, which puts heavy burden on the communication network especially when wireless communications are widely applied in smart grids. In order to relieve this communication burden, the event-triggered cubature Kalman filter (ETCKF) is proposed based on the stochastic event-triggered schedule in this paper, which guarantees that only the measurements containing innovational information are transmitted and has advantages over other event-triggered schedules, such as the deterministic event-triggered schedule, since it can maintain the Gaussian property of the conditional distribution of the system state. Based on the developed nonlinear event-triggered schedule, the cubature Kalman filter (CKF), using the third-degree spherical-radial cubature rule, further provides more accurate estimation than UKF and has lower computational complexity than PF. The proposed filter can effectively reduce the communication rate while ensuring the accuracy of filtering. Finally, the standard IEEE 39-bus system is utilized to verify the feasibility and performance of the proposed method. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 129-140. Minfeng Wei, Min Xu, Fengdi Zhang Accurate dynamic state estimation plays an important role in power systems. Although various filtering algorithms, such as unscented Kalman filter (UKF) and particle filter (PF), have been proposed based on phasor measurement units (PMUs), they occupy a huge communication bandwidth without specific concern, which puts heavy burden on the communication network especially when wireless communications are widely applied in smart grids. In order to relieve this communication burden, the event-triggered cubature Kalman filter (ETCKF) is proposed based on the stochastic event-triggered schedule in this paper, which guarantees that only the measurements containing innovational information are transmitted and has advantages over other event-triggered schedules, such as the deterministic event-triggered schedule, since it can maintain the Gaussian property of the conditional distribution of the system state. Based on the developed nonlinear event-triggered schedule, the cubature Kalman filter (CKF), using the third-degree spherical-radial cubature rule, further provides more accurate estimation than UKF and has lower computational complexity than PF. The proposed filter can effectively reduce the communication rate while ensuring the accuracy of filtering. Finally, the standard IEEE 39-bus system is utilized to verify the feasibility and performance of the proposed method. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 129-140. Dynamic State Estimation for Power System with Communication Constraint Using Event-Triggered Cubature Kalman Filter Minfeng Wei, Min Xu, Fengdi Zhang 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 129-140. article doi:10.15918/j.jbit1004-0579.20003 10.15918/j.jbit1004-0579.20003 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20003?pageType=en 129 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20083?pageType=en Zhiying Yao, Haiqing Cao A novel finite time non-smooth controller of the second system with disturbances is proposed. Its stability is proved by homogeneous system theory, its strong disturbances rejection ability is studied by numerical simulation. The azimuth non-smooth compounded controller of the small float satellite antenna including the non-smooth feed-forward controller, non-smooth feedback controller and the non-smooth proportional and differential (PD) controller is applied to control the azimuth attitude of the antenna. The accurate disturbances estimation of the non-smooth feed-forward controller, the strong disturbances rejection of the non-smooth feedback controller and the rapid response of the non-smooth PD controller are studied. Experiments validate the azimuth non-smooth compounded controller of the small float satellite antenna can control the azimuth attitude of the antenna in time and guarantee the communication between the antenna and the target satellite with high quality. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 141-150. Zhiying Yao, Haiqing Cao A novel finite time non-smooth controller of the second system with disturbances is proposed. Its stability is proved by homogeneous system theory, its strong disturbances rejection ability is studied by numerical simulation. The azimuth non-smooth compounded controller of the small float satellite antenna including the non-smooth feed-forward controller, non-smooth feedback controller and the non-smooth proportional and differential (PD) controller is applied to control the azimuth attitude of the antenna. The accurate disturbances estimation of the non-smooth feed-forward controller, the strong disturbances rejection of the non-smooth feedback controller and the rapid response of the non-smooth PD controller are studied. Experiments validate the azimuth non-smooth compounded controller of the small float satellite antenna can control the azimuth attitude of the antenna in time and guarantee the communication between the antenna and the target satellite with high quality. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 141-150. A Novel Non-smooth Controller of the Second Order System with Disturbances and Its Application Zhiying Yao, Haiqing Cao 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 141-150. article doi:10.15918/j.jbit1004-0579.20083 10.15918/j.jbit1004-0579.20083 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20083?pageType=en 141 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20004?pageType=en Xin Teng, Defu Lin, Long Xiao, Fengdi Zhang This paper proposes an autonomous approach and landing guidance law for a reusable launch vehicle (RLV) at the specified runway touchdown. With the full nonlinear point-mass dynamics, the multiple sliding surfaces guidance (MSSG) technique is developed for the closed-loop guidance law to guarantee a successful approach and landing (A&L) movement, which has the same advantage in the finite time convergent property as higher order sliding mode control. Its global stability is proved using Lyapunov theory. The resultant guidance law has features in on-line trajectories calculation without any off-line analysis only using the boundary conditions of the A&L phase and instantaneous states of the RLV. Therefore, it is capable of targeting different touchdown points on the runway and overcoming large initial condition errors. Simulations are provided to verify the effectiveness of the proposed law. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 151-158. Xin Teng, Defu Lin, Long Xiao, Fengdi Zhang This paper proposes an autonomous approach and landing guidance law for a reusable launch vehicle (RLV) at the specified runway touchdown. With the full nonlinear point-mass dynamics, the multiple sliding surfaces guidance (MSSG) technique is developed for the closed-loop guidance law to guarantee a successful approach and landing (A&L) movement, which has the same advantage in the finite time convergent property as higher order sliding mode control. Its global stability is proved using Lyapunov theory. The resultant guidance law has features in on-line trajectories calculation without any off-line analysis only using the boundary conditions of the A&L phase and instantaneous states of the RLV. Therefore, it is capable of targeting different touchdown points on the runway and overcoming large initial condition errors. Simulations are provided to verify the effectiveness of the proposed law. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 151-158. Investigation of Reusable Launch Vehicle Landing Guidance Control with Multiple Sliding Surface Technique Xin Teng, Defu Lin, Long Xiao, Fengdi Zhang 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 151-158. article doi:10.15918/j.jbit1004-0579.20004 10.15918/j.jbit1004-0579.20004 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20004?pageType=en 151 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20126?pageType=en Baiyan Sun, Zhen Chen, Congzhe Gao, Xiangdong Liu A power decoupling control for wind turbine converter based on series-connected modular multilevel converter (SCMMC) and open-winding permanent magnetic synchronous generator (OW-PMSG) is proposed in this paper. The phase dc links of the SCMMC are series connected and the windings of the OW-PMSG are independent, which is different from conventional MMC. To improve the robustness of the system under imbalanced power disturbance, an ac power decoupling control is proposed with perfect power independent control of the three phase power and phase dc-link voltages. Besides, multi-frequency-bandwidth proportional-resonant (MFBPR) controller in the <i<abc</i< stationary frame without coordinates transformation is presented, which simplifies the control of the SCMMC. The accurate current control is based on the MFBPR controller and it is easy to improve the quality of the current with this controller. The proposed power decoupling control is verified through simulation and a 3 kW laboratory prototype. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 159-170. Baiyan Sun, Zhen Chen, Congzhe Gao, Xiangdong Liu A power decoupling control for wind turbine converter based on series-connected modular multilevel converter (SCMMC) and open-winding permanent magnetic synchronous generator (OW-PMSG) is proposed in this paper. The phase dc links of the SCMMC are series connected and the windings of the OW-PMSG are independent, which is different from conventional MMC. To improve the robustness of the system under imbalanced power disturbance, an ac power decoupling control is proposed with perfect power independent control of the three phase power and phase dc-link voltages. Besides, multi-frequency-bandwidth proportional-resonant (MFBPR) controller in the <i<abc</i< stationary frame without coordinates transformation is presented, which simplifies the control of the SCMMC. The accurate current control is based on the MFBPR controller and it is easy to improve the quality of the current with this controller. The proposed power decoupling control is verified through simulation and a 3 kW laboratory prototype. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 159-170. Power Decoupling Control for Wind Turbine Converter Based on Series-Connected Modular Multilevel Converter Baiyan Sun, Zhen Chen, Congzhe Gao, Xiangdong Liu 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 159-170. article doi:10.15918/j.jbit1004-0579.20126 10.15918/j.jbit1004-0579.20126 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20126?pageType=en 159 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20069?pageType=en Lijun Feng, Hao Yan A nonlinear adaptive robust control method based on a differentiable LuGre friction model is proposed for the problems of uncertain parameters, nonlinear friction and time-varying disturbances in valve-controlled symmetrical cylinder system. The proposed method can effectively compensate the uncertain nonlinear characteristics and external disturbances in the system by combining adaptive robust control with state and disturbance observations, as well as sliding mode differential technique. The global stability and boundedness of the proposed control method are proven by applying the Lyapunov theory. The simulation results show that this control method can deal with the problems of the uncertain nonlinearities and disturbances within the system. The proposed control method also presents excellent dynamic performance and robustness. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 171-178. Lijun Feng, Hao Yan A nonlinear adaptive robust control method based on a differentiable LuGre friction model is proposed for the problems of uncertain parameters, nonlinear friction and time-varying disturbances in valve-controlled symmetrical cylinder system. The proposed method can effectively compensate the uncertain nonlinear characteristics and external disturbances in the system by combining adaptive robust control with state and disturbance observations, as well as sliding mode differential technique. The global stability and boundedness of the proposed control method are proven by applying the Lyapunov theory. The simulation results show that this control method can deal with the problems of the uncertain nonlinearities and disturbances within the system. The proposed control method also presents excellent dynamic performance and robustness. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 171-178. Nonlinear Adaptive Robust Control of Valve-Controlled Symmetrical Cylinder System Lijun Feng, Hao Yan 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 171-178. article doi:10.15918/j.jbit1004-0579.20069 10.15918/j.jbit1004-0579.20069 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20069?pageType=en 171 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20081?pageType=en Long Bai, Hao Yan 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 179-186. Long Bai, Hao Yan 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 179-186. Design and Analysis of a Soft Actuator Based on Cable-Driven Method Long Bai, Hao Yan 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 179-186. article doi:10.15918/j.jbit1004-0579.20081 10.15918/j.jbit1004-0579.20081 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20081?pageType=en 179 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20052?pageType=en Xu Yang, Ming Zhang, Rong Cheng, Yu Zhu, Leijie Wang Vector fitting is modified in this study for the parametric identification of a model with an undamped rigid body mode in the frequency domain. The modal model of a six-degree-of-freedom (6DOF) wafer stage is identified using the modified vector fitting method. The modal model is typically fitted from the matrix fraction description (MFD) form of the transfer function, which increases the cost function. The vector fitting in frequency domain provides an approach to fitting the modal model directly from frequency response functions(FRFs) via a partial rational basis function, the poles of which can be obtained by pole relocation technology. The traditional vector fitting method is not applicable in identifying systems containing rigid body modes. The method is reformulated here and effectively applied for wafer stage identification. The accuracy of the fitted model is validated by control loop simulation. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 187-195. Xu Yang, Ming Zhang, Rong Cheng, Yu Zhu, Leijie Wang Vector fitting is modified in this study for the parametric identification of a model with an undamped rigid body mode in the frequency domain. The modal model of a six-degree-of-freedom (6DOF) wafer stage is identified using the modified vector fitting method. The modal model is typically fitted from the matrix fraction description (MFD) form of the transfer function, which increases the cost function. The vector fitting in frequency domain provides an approach to fitting the modal model directly from frequency response functions(FRFs) via a partial rational basis function, the poles of which can be obtained by pole relocation technology. The traditional vector fitting method is not applicable in identifying systems containing rigid body modes. The method is reformulated here and effectively applied for wafer stage identification. The accuracy of the fitted model is validated by control loop simulation. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 187-195. Wafer Stage Modal Model Identification by Modified Vector Fitting Method Xu Yang, Ming Zhang, Rong Cheng, Yu Zhu, Leijie Wang 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 187-195. article doi:10.15918/j.jbit1004-0579.20052 10.15918/j.jbit1004-0579.20052 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20052?pageType=en 187 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20027?pageType=en Xinyue Zhao, Yanxuan Wu, Wei Zhang 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 196-201. Xinyue Zhao, Yanxuan Wu, Wei Zhang 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 196-201. Structural Optimization of Anti-Interference of Small Ducted Aircraft Xinyue Zhao, Yanxuan Wu, Wei Zhang 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 196-201. article doi:10.15918/j.jbit1004-0579.20027 10.15918/j.jbit1004-0579.20027 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20027?pageType=en 196 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20057?pageType=en Zhengxing Feng, Yu Fu, Jinglin Wang, Yong Shen, Liang Cao, Hongfu Zuo 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 202-209. Zhengxing Feng, Yu Fu, Jinglin Wang, Yong Shen, Liang Cao, Hongfu Zuo 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 202-209. Measurement Model and Dynamic Performance Analysis of Inlet Electrostatic Sensor on Aircraft Engine Zhengxing Feng, Yu Fu, Jinglin Wang, Yong Shen, Liang Cao, Hongfu Zuo 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 202-209. article doi:10.15918/j.jbit1004-0579.20057 10.15918/j.jbit1004-0579.20057 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20057?pageType=en 202 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20054?pageType=en Shenghua Fu, Wenzhong Lou, Jingkui Wang, Tong’an Ji, Weitong Liu In order to improve the accuracy of nodes in wireless sensor networks (WSNs). An multi-barycenter localization algorithm based on improved received signal strength indication (RSSI) ranging is proposed. The algorithm first optimizes the RSSI values by the iterative filtering, the distance values of WSNs nodes could be more accurately calculated. And then a multi-barycenter algorithm is introduced to optimize the trilateral localization. The simulation results show that the algorithm can improve the positioning accuracy by 30% compared with the traditional trilateral localization algorithm. Finally, through the localization test of 5 WSN nodes, the measured localization deviation of the WSN nodes is controlled at about 2 m when the distance of sensor node is 80 m. The proposed method could improve localization accuracy effectively without increasing computing resources. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 210-217. Shenghua Fu, Wenzhong Lou, Jingkui Wang, Tong’an Ji, Weitong Liu In order to improve the accuracy of nodes in wireless sensor networks (WSNs). An multi-barycenter localization algorithm based on improved received signal strength indication (RSSI) ranging is proposed. The algorithm first optimizes the RSSI values by the iterative filtering, the distance values of WSNs nodes could be more accurately calculated. And then a multi-barycenter algorithm is introduced to optimize the trilateral localization. The simulation results show that the algorithm can improve the positioning accuracy by 30% compared with the traditional trilateral localization algorithm. Finally, through the localization test of 5 WSN nodes, the measured localization deviation of the WSN nodes is controlled at about 2 m when the distance of sensor node is 80 m. The proposed method could improve localization accuracy effectively without increasing computing resources. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 210-217. Multi-barycenter Nodes Localization Method in Wireless Sensor Network Based on Improved RSSI Shenghua Fu, Wenzhong Lou, Jingkui Wang, Tong’an Ji, Weitong Liu 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 210-217. article doi:10.15918/j.jbit1004-0579.20054 10.15918/j.jbit1004-0579.20054 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20054?pageType=en 210 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20088?pageType=en Yun Duan, Zhen Yang, Wenchao Ge, Yongduo Sun To determine and check explosive thermal vulnerability, cook-off test and vented pipe test are general methods in experimental research. Heating temperature and internal temperature real-time monitoring are important for experimental research. Aimed at the risk of the explosive thermal analysis and the portability of field environment test instrument, potable temperature monitoring system had been developed based on NI cDAQ hardware equipment. The monitoring system uses NI cDAQ 9184, NI Compact DAQ4, NI 9214 data acquisition module to realize the acquisition of the temperature data. The data transmission module uses wireless AP. The software developed by LabVIEW8.5 realizes the development of modules with the ability of data real-time display and data storage. The system had the advantage of small size, light weight, high precision, real-time and the ability of real-time measurement of explosive temperature change in 500 m far away. It is a reliable temperature test instrument for the study of explosive thermal analysis. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 218-224. Yun Duan, Zhen Yang, Wenchao Ge, Yongduo Sun To determine and check explosive thermal vulnerability, cook-off test and vented pipe test are general methods in experimental research. Heating temperature and internal temperature real-time monitoring are important for experimental research. Aimed at the risk of the explosive thermal analysis and the portability of field environment test instrument, potable temperature monitoring system had been developed based on NI cDAQ hardware equipment. The monitoring system uses NI cDAQ 9184, NI Compact DAQ4, NI 9214 data acquisition module to realize the acquisition of the temperature data. The data transmission module uses wireless AP. The software developed by LabVIEW8.5 realizes the development of modules with the ability of data real-time display and data storage. The system had the advantage of small size, light weight, high precision, real-time and the ability of real-time measurement of explosive temperature change in 500 m far away. It is a reliable temperature test instrument for the study of explosive thermal analysis. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 218-224. Explosive Thermal Analysis Monitoring System Based on Virtual Instrument Yun Duan, Zhen Yang, Wenchao Ge, Yongduo Sun 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 218-224. article doi:10.15918/j.jbit1004-0579.20088 10.15918/j.jbit1004-0579.20088 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20088?pageType=en 218 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20092?pageType=en Shuzhen Niu, Yinghua Zhang, Huanjuan Zhao, Yiran Yan 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 <i<D</i<<sub<0</sub< 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 225-235. Shuzhen Niu, Yinghua Zhang, Huanjuan Zhao, Yiran Yan 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 <i<D</i<<sub<0</sub< 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. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 225-235. Cellular Property of the Detonation Wave of Pre-mixed Methane-Oxygen in Annular Tube Shuzhen Niu, Yinghua Zhang, Huanjuan Zhao, Yiran Yan 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 225-235. article doi:10.15918/j.jbit1004-0579.20092 10.15918/j.jbit1004-0579.20092 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20092?pageType=en 225 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20012?pageType=en Wenjia Chen, Jinlin Li, He Wang, Ying Gao, Shuangquan Xin, Jinchuan Cao, Hao Li Data mining techniques were utilized to improve the regional cardiovascular diseases (CVDs) prevention and in addition to find why rural residents are in worse statues of CVDs. Decision tree (DT) was chosen to build a high-risk CVDs people identification model, and the steps of identifying are reduced, with 99.4% precision in the classification. In comparison with the top 18 key features assessed by Random Forest, rural people were at higher risk due to the factors such as higher total cholesterol, blood glucose, blood pressure, body mass index(BMI) and waistline. Urban people had higher hypertensive historical prevalence but lower hypertensive comorbidity prevalence than rural people because of better control of high blood pressure. Smoking, drinking and medicine taking affected current blood pressure and lipid. More tobacco use of rural female and more alcohol intake of rural male can take part of responsibilities for worse CVDs prevalence and control in rural area. In the intervention and prevention of CVDs in a region, high-risk people should be more focused on. And rural and urban residents should be separately implemented with intervenable methods because of different disease history statues, control effect and current statue. Gender also should be considered when lifestyles are significantly different. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 236-246. Wenjia Chen, Jinlin Li, He Wang, Ying Gao, Shuangquan Xin, Jinchuan Cao, Hao Li Data mining techniques were utilized to improve the regional cardiovascular diseases (CVDs) prevention and in addition to find why rural residents are in worse statues of CVDs. Decision tree (DT) was chosen to build a high-risk CVDs people identification model, and the steps of identifying are reduced, with 99.4% precision in the classification. In comparison with the top 18 key features assessed by Random Forest, rural people were at higher risk due to the factors such as higher total cholesterol, blood glucose, blood pressure, body mass index(BMI) and waistline. Urban people had higher hypertensive historical prevalence but lower hypertensive comorbidity prevalence than rural people because of better control of high blood pressure. Smoking, drinking and medicine taking affected current blood pressure and lipid. More tobacco use of rural female and more alcohol intake of rural male can take part of responsibilities for worse CVDs prevalence and control in rural area. In the intervention and prevention of CVDs in a region, high-risk people should be more focused on. And rural and urban residents should be separately implemented with intervenable methods because of different disease history statues, control effect and current statue. Gender also should be considered when lifestyles are significantly different. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 236-246. High-Risk People Identification and Key Risk Factor Comparison of Cardiovascular Diseases in Northern China Rural and Urban Areas Wenjia Chen, Jinlin Li, He Wang, Ying Gao, Shuangquan Xin, Jinchuan Cao, Hao Li 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 236-246. article doi:10.15918/j.jbit1004-0579.20012 10.15918/j.jbit1004-0579.20012 JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/doi/10.15918/j.jbit1004-0579.20012?pageType=en 236 http://journal.bit.edu.cn/jbit/article/id/093ba4ef-4d2d-41fc-a801-2e305acc71aa JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 1-1. JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 1-1. fengdi2021-zk Contents 2021-06-30 Personal use only, all commercial or other reuse prohibited JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY. 2021 30(zk): 1-1. article doi: JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY 30 zk 2021-06-30 http://journal.bit.edu.cn/jbit/article/id/093ba4ef-4d2d-41fc-a801-2e305acc71aa 1

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