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Sealing Performance of Pressure-Adaptive Seal LI Yuanfeng (李元丰), WANG Yiling (王怡灵), ZHANG Wanxin∗ (张万欣), LIU Jinian (刘冀念), MA Jialu (马加炉) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 747-756.   DOI: 10.1007/s12204-022-2510-x Abstract （347）      PDF （2268KB）（150）       Knowledge map    A pressure-adaptive seal is developed to meet the demands of quick assembling and disassembling for an individual protection equipment in aerospace. The analysis model, which reflects the main characteristics of the seal structure, is built based on the finite element method and the Roth’s theory of rubber seal, and verified by the prototype test. The influences of precompression ratio, hardness of the sealing ring rubber, and friction coefficient on the sealing performance are investigated by variable parameter method. Results show that the model can describe the essential characteristics of the pressure-adaptive seal structure, which has good follow-up to the cavity pressure to achieve the purpose of pressure self-adaptive. The leakage rate correlates negatively with the precompression ratio of the sealing ring and the hardness of the sealing ring material, while is positively related to the friction coefficient between the sealing ring and the sealing edge. The maximum contact stress on sealing surface has negative correlation with the precompression ratio of the sealing ring, and positive correlation with the hardness of the seal ring material. The damage risk of the sealing ring increases with the increases of the precompression ratio of sealing ring, hardness of sealing ring material, and friction coefficient. Reference | Related Articles | Metrics

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Travel Intention of Electric Vehicle Sharing based on Theory of Multiple Motivations BAO Lewen (鲍乐雯), MIAO Rui, ∗ (苗 瑞), CHEN Zhihua (陈志华), ZHANG Bo (张 博), GUO Peng (郭 鹏), MA Yuze (马宇泽) J Shanghai Jiaotong Univ Sci    2023, 28 (1): 1-9.   DOI: 10.1007/s12204-023-2563-5 Abstract （195）      PDF （467KB）（88）       Knowledge map    Determining the travel intention of residents with shared electric vehicles (EVs) is significant for promoting the development of low-carbon transportation, considering that common problems such as high idle rate and lack of attractiveness still exist. To this end, a structural equation model (SEM) based on the theory of multiple motivations is proposed in this paper. First, the influencing motivations for EV sharing are divided into three categories: consumer-driven, program-driven, and enterprise-driven motivations. Then, the intentions of residents in Shanghai to travel with shared EVs are obtained through a survey questionnaire. Finally, an SEM is constructed to analyze quantitatively the impact of different motivations on the travel intention. The results show that consumer-driven motivations with impact weights from 0.14 to 0.63 have the overwhelming impact on travel intention, compared to program-driven motivations with impact weights from ?0.14 to 0.15 and enterprise-driven motivations with impact weights from 0.02 to 0.06. In terms of consumer-driven motivations, the weight of green travel awareness is the highest. The implications of these results on the policy to enable large-scale implementation of shared EVs are discussed from the perspectives of the resident, enterprise, and government. Reference | Related Articles | Metrics

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Adaptive Human-Robot Collaboration Control Based on Optimal Admittance Parameters YU Xinyi (禹鑫燚), WU Jiaxin (吴加鑫), XU Chengjun (许成军), LUO Huizhen (罗惠珍), OU Linlin∗ (欧林林) J Shanghai Jiaotong Univ Sci    2022, 27 (5): 589-601.   DOI: 10.1007/s12204-022-2460-3 Abstract （164）      PDF （1674KB）（78）       Knowledge map    In order to help the operator perform the human-robot collaboration task and optimize the task performance, an adaptive control method based on optimal admittance parameters is proposed. The overall control structure with the inner loop and outer loop is first established. The tasks of the inner loop and outer loop are robot control and task optimization, respectively. Then an inner-loop robot controller integrated with barrier Lyapunov function and radial basis function neural networks is proposed, which makes the robot with unknown dynamics securely behave like a prescribed robot admittance model sensed by the operator. Subsequently, the optimal parameters of the robot admittance model are obtained in the outer loop to minimize the task tracking error and interaction force. The optimization problem of the robot admittance model is transformed into a linear quadratic regulator problem by constructing the human-robot collaboration system model. The model includes the unknown dynamics of the operator and the task performance details. For relaxing the requirement of the system model, the integral reinforcement learning is employed to solve the linear quadratic regulator problem. Besides, an auxiliary force is designed to help the operator complete the specific task better. Compared with the traditional control scheme, the security performance and interaction performance of the human-robot collaboration system are improved. The effectiveness of the proposed method is verified through two numerical simulations. In addition, a practical human-robot collaboration experiment is carried out to demonstrate the performance of the proposed method. Reference | Related Articles | Metrics

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Solution to Long-Range Continuous and Precise Positioning in Deep Ocean for Autonomous Underwater Vehicles Using Acoustic Range Estimation and Inertial Sensor Measurements YANG Tao (杨 涛), ZHAO Jiankang∗ (赵健康) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 281-297.   DOI: 10.1007/s12204-022-2441-6 Abstract （157）      PDF （2619KB）（105）       Knowledge map    Although advances in research into autonomous underwater vehicles (AUVs) have been made to extend their working depth and endurance, underwater experiments and missions remain to be restricted by the positioning performance of AUVs. With the Global Navigation Satellite System (GNSS) precluded due to the rapid attenuation of radio signals in underwater environments, acoustic positioning methods serve as an effective substitution. A long-range continuous and precise positioning solution for AUVs in deep ocean is proposed in this study, relying on acoustic signals from beacons at the same depth and aided by onboard inertial sensors. A signal system is investigated to provide time of arrival (TOA) estimation in a resolution of milliseconds. Without pre-knowledge or local measurement of the accurate sound speed, an AUV is enabled to continuously locate its horizontal position based on rough ranges estimated by an iterative least square (ILS) based algorithm. For better accuracy and robustness, range deviations are compensated with a reference point of known position and outliers in the trajectory are eliminated by an implementation of the extended Kalman filter (EKF) coupled with the state-acceptance filter. The solution is evaluated in simulation experiments with environmental information measured on the spot, providing an average position error from ground truth below 10 m with a standard deviation below 5 m. Reference | Related Articles | Metrics

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Airframe Damage Region Division Method Based on Structure Tensor Dynamic Operator CAI Shuyu∗ (蔡舒妤), SHI Lizhong (师利中) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 757-767.   DOI: 10.1007/s12204-022-2498-2 Abstract （155）      PDF （1607KB）（69）       Knowledge map    In order to improve the accuracy of damage region division and eliminate the interference of damage adjacent region, the airframe damage region division method based on the structure tensor dynamic operator is proposed in this paper. The structure tensor feature space is established to represent the local features of damage images. It makes different damage images have the same feature distribution, and transform varied damage region division into consistent process of feature space division. On this basis, the structure tensor dynamic operator generation method is designed. It integrates with bacteria foraging optimization algorithm improved by defining double fitness function and chemotaxis rules, in order to calculate the parameters of dynamic operator generation method and realize the structure tensor feature space division. And then the airframe damage region division is realized. The experimental results on different airframe structure damage images show that compared with traditional threshold division method, the proposed method can improve the division quality. The interference of damage adjacent region is eliminated. The information loss caused by over-segmentation is avoided. And it is efficient in operation, and consistent in process. It also has the applicability to different types of structural damage. Reference | Related Articles | Metrics

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Path Planning and Optimization of Humanoid Manipulator in Cartesian Space LI Shiqi (李世其), LI Xiao∗ (李肖), HAN Ke (韩可), XIONG Youjun (熊友军), XIE Zheng (谢铮), CHEN Jinliang (陈金亮) J Shanghai Jiaotong Univ Sci    2022, 27 (5): 614-620.   DOI: 10.1007/s12204-022-2416-7 Abstract （153）      PDF （1591KB）（29）       Knowledge map    To solve the problems of low efficiency and multi-solvability of humanoid manipulator Cartesian space path planning in physical human-robot interaction, an improved bi-directional rapidly-exploring random tree algorithm based on greedy growth strategy in 3D space is proposed. The workspace of manipulator established based on Monte Carlo method is used as the sampling space of the rapidly-exploring random tree, and the opposite expanding greedy growth strategy is added in the random tree expansion process to improve the path planning efficiency. Then the generated path is reversely optimized to shorten the length of the planned path, and the optimized path is interpolated and pose searched in Cartesian space to form a collision-free optimized path suitable for humanoid manipulator motion. Finally, the validity and reliability of the algorithm are verified in an intelligent elderly care service scenario based on Walker2, a large humanoid service robot. Reference | Related Articles | Metrics

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Automatic Removal of Multiple Artifacts for Single-Channel Electroencephalography ZHANG Chenbei (张晨贝), SABOR Nabil, LUO Junwen (罗竣文), PU Yu (蒲 宇), WANG Guoxing (王国兴), LIAN Yong∗ (连 勇) J Shanghai Jiaotong Univ Sci    2022, 27 (4): 437-451.   DOI: 10.1007/s12204-021-2374-5 Abstract （150）      PDF （2934KB）（86）       Knowledge map    Removing different types of artifacts from the electroencephalography (EEG) recordings is a critical step in performing EEG signal analysis and diagnosis. Most of the existing algorithms aim for removing single type of artifacts, leading to a complex system if an EEG recording contains different types of artifacts. With the advancement in wearable technologies, it is necessary to develop an energy-efficient algorithm to deal with different types of artifacts for single-channel wearable EEG devices. In this paper, an automatic EEG artifact removal algorithm is proposed that effectively reduces three types of artifacts, i.e., ocular artifact (OA), transmission- line/harmonic-wave artifact (TA/HA), and muscle artifact (MA), from a single-channel EEG recording. The effectiveness of the proposed algorithm is verified on both simulated noisy EEG signals and real EEG from CHB- MIT dataset. The experimental results show that the proposed algorithm effectively suppresses OA, MA and TA/HA from a single-channel EEG recording as well as physical movement artifact. Reference | Related Articles | Metrics

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Modification Method of Longitudinal Bow Structure for Ice-Strengthened Merchant Ship DING Shifeng (丁仕风), ZHOU Li∗ (周 利), GU Yingjie (顾颖杰), ZHOU Yajun (周亚军) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 298-306.   DOI: 10.1007/s12204-022-2442-5 Abstract （144）      PDF （5084KB）（37）       Knowledge map    Merchant ships, which are quite different from icebreakers, usually require the light ice-strengthened bow under the floe-ice condition. According to ice-class B, requirements of China Classification Society (CCS), intermediate frames and thick hull plates are necessary for the ice belt area to resist floe-ice impact. However, due to the limited space, it is not practical to set so many intermediate longitudinals from manufacture point of view. In this paper, a modification method is proposed to solve the problem by maintaining the frame spacing and increasing the plate thickness. The aim is to make sure that the bow owns the equivalent ice-bearing capacity with the original frame spacing. At first, a bulk carrier with ice-class B is used for case study. According to the requirements of the ice class rule, a designed ice thickness is used to calculate the ice load acting on the bow area due to the impact of ice floe. Two structural models are presented to perform the strength analysis under ice load, including the out-shell plate model and the longitudinal model. The results show that increasing the plate thickness is helpful to remove the negative effect induced by enlarging the spacing of the longitudinal. A reasonable curve is presented to modify the bow for the ice-strengthened merchant ship, which shows the relationship between the increase of plate thickness and the spacing of longitudinal. Moreover, a model test of floe-ice–ship interaction is conducted to measure the dynamic ice load, based on which nonlinear dynamic FE analysis is used to verify the presented plate-thickness–longitudinal spacing curve. The results show that the proposed method can be used to improve the ice-strengthened bow structure effectively, which provides theoretical foundation to modify the requirement of CCS’s ice class rule. Reference | Related Articles | Metrics

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Switched Three-Dimensional Decoupling Stabilization of Underactuated Autonomous Underwater Vehicles FANG Haolin (房浩霖), ZHANG Jiawen (张家闻), LI Jiawang∗ (李家旺) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 383-392.   DOI: 10.1007/s12204-022-2446-1 Abstract （139）      PDF （897KB）（18）       Knowledge map    A three-dimensional stabilization problem for underactuated autonomous underwater vehicles (AUVs) is addressed in this paper. A novel coordinate transformation form consisting of state modifications and input transformations is introduced such that the whole system is divided into two decoupled one-order subsystems. Some switching functions are presented to further decouple the underactuated dynamics and to produce persis tently exciting (PE) signals for those underactuated states. Based on the aforementioned results, a quite simple control law is designed to achieve global three-dimensional asymptotic convergence of all states of underactuated AUVs. Comparative simulations are carried out to validate the effectiveness and performance of the proposed control scheme. Reference | Related Articles | Metrics

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Improved Nonsingular Fast Terminal Sliding Mode Control of Unmanned Underwater Hovering Vehicle HE Chenlua (何晨璐), FENG Zhengpinga,b∗ (冯正平) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 393-401.   DOI: 10.1007/s12204-022-2447-0 Abstract （136）      PDF （1034KB）（29）       Knowledge map    An improved nonsingular fast terminal sliding mode manifold based on scaled state error is proposed in this paper. It can significantly accelerate the convergence rate of the state error which is initially far from the origin and achieve the fixed-time convergence. In addition, conventional double power term based reaching law is improved to ensure the convergence of sliding state in the presence of disturbances. The proposed approach is applied to the hovering control of an unmanned underwater vehicle. The controller exhibits both fast convergence and strong robustness to model uncertainty and external disturbances Reference | Related Articles | Metrics

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Design and Overall Strength Analysis of Multi-Functional Elastic Connections Floating Breakwater System HUO Fali∗ (霍发力), YANG Hongkun (杨宏坤), GUO Jianting (郭建廷), JI Chunyan (嵇春艳), NIU Jianjie (牛建杰), WANG Ke (王 珂) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 326-338.   DOI: 10.1007/s12204-022-2413-x Abstract （134）      PDF （3201KB）（21）       Knowledge map    As a new type of marine structure, floating breakwater can provide suitable water area for coastal residents. In this paper, a multi-module floating breakwater with three cylinders was designed. According to the characteristics of each module, the elastic connector was created. The cabins with functions such as living, generating electricity and entertainment were arranged. A linear spring constrained design wave (LSCDW) method for strength analysis of floating marine structures with multi-module elastic connections was proposed. The numerical model was verified by 1 : 50 similarity ratio in the test tank. According to the analysis of design wave and extreme wave conditions, considering the mooring loads and environmental loads and connector loads, the overall strength of breakwater was analyzed by LSCDW method. These studies can provide new insights and theoretical guidance for the design of multi-module floating structures. Reference | Related Articles | Metrics

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Construction on Aerodynamic Surrogate Model of Stratospheric Airship QIN Pengfei (秦鹏飞), WANG Xiaoliang∗ (王晓亮) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 768-779.   DOI: 10.1007/s12204-022-2494-6 Abstract （131）      PDF （3866KB）（43）       Knowledge map    Stratospheric airship can stay at an altitude of 20 km for a long time and carry various loads to achieve long-term stable applications. Conventional stratospheric airship configuration mainly includes a low-resistance streamline hull and inflatable “X”-layout fins that realize the self-stabilization. A fast aerodynamic predictive method is needed in the optimization design of airship configuration and the flight performance analysis. In this paper, a predictive surrogate model of aerodynamic parameters is constructed for the stratospheric airship with “X” fins based on the neural network. First, a geometric shape parameterized model, and a flow field parameterized model were established, and the aerodynamic coefficients of airships with different shapes used as the training and test samples were calculated based on computational fluid dynamics (SA turbulence model). The improved Bayesian regularized neural network was used as the surrogate model, and 20 types of airships with different shapes were used to test the effectiveness of network. It showed that the correlation coefficients of Cx, Cy, Cz, CM,x, CM,y, CM,z were 0.928 7, 0.991 7, 0.991 9, 0.958 2, 0.986 1, 0.984 2, respectively. The aerodynamic coefficient distribution contour at different angles of attack and sideslip angles is used to verify the reliability of the method. The method can provide an effective way for a rapid estimation of aerodynamic coefficients in the airship design. Reference | Related Articles | Metrics

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Dynamic Stability Analysis of Backhoe Dredger Based on Time Domain Method CHEN Yihua1 (陈熠画), CHEN Xinquan1∗ (陈新权), YANG Qi1,2 (杨 启), OUYANG Yiping1 (欧阳义平) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 339-345.   DOI: 10.1007/s12204-021-2272-x Abstract （130）      PDF （1221KB）（18）       Knowledge map    When incidents happen with the positioning spud of a backhoe dredger, the hull loses stability, heels significantly, and may even capsize under extreme conditions. Coupling the hydrodynamics and spud vibrations, this paper investigates the dynamic stability of a backhoe dredger after spud failure based on the time domain method. The maximum dynamic heeling angle verifies the stability of the backhoe dredger. To identify the influences of environmental load, operating conditions, and spud-soil interactions, numerical motion simulations were conducted in the time domain. The main conclusions on dynamic stability consider the influences of relative environmental and operational factors. This study provides a powerful and efficient approach to analyze the dynamic stability of backhoe dredgers and to design flooding angles. Reference | Related Articles | Metrics

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Generation Approach of Human-Robot Cooperative Assembly Strategy Based on Transfer Learning LÜ Qibing (吕其兵), LIU Tianyuan (刘天元), ZHANG Rong (张荣), JIANG Yanan (江亚南), XIAO Lei (肖雷), BAO Jingsong∗ (鲍劲松) J Shanghai Jiaotong Univ Sci    2022, 27 (5): 602-613.   DOI: 10.1007/s12204-022-2493-7 Abstract （125）      PDF （3845KB）（35）       Knowledge map    In current small batch and customized production mode, the products change rapidly and the personal demand increases sharply. Human-robot cooperation combining the advantages of human and robot is an effective way to solve the complex assembly. However, the poor reusability of historical assembly knowledge reduces the adaptability of assembly system to different tasks. For cross-domain strategy transfer, we propose a human-robot cooperative assembly (HRCA) framework which consists of three main modules: expression of HRCA strategy, transferring of HRCA strategy, and adaptive planning of motion path. Based on the analysis of subject capability and component properties, the HRCA strategy suitable for specific tasks is designed. Then the reinforcement learning is established to optimize the parameters of target encoder for feature extraction. After classification and segmentation, the actor-critic model is built to realize the adaptive path planning with progressive neural network. Finally, the proposed framework is verified to adapt to the multi-variety environment, for example, power lithium batteries. Reference | Related Articles | Metrics

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Two-Stage Scheme for Disturbance Rejection Hovering Control of Underwater Vehicles BI Anyuana (毕安元), FENG Zhengpinga,b∗ (冯正平), ZHU Yuchena (朱昱琛), DENG Xua (邓 旭) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 375-382.   DOI: 10.1007/s12204-021-2341-1 Abstract （124）      PDF （1043KB）（22）       Knowledge map    A two-stage model-independent hovering control scheme for underwater vehicles, which are subject to unknown yet constant external disturbance, to eliminate steady-state depth error is proposed. Proportional derivative (PD) state feedback control law is adopted as the ballast mass planner at the first stage for the vehicle to reach both hydrostatic balance and a steady depth. The residual depth error is then removed by an additional disturbance rejection control at the second stage. Global asymptotic stability of the whole system is guaranteed via Lyapunov approach. The effectiveness of the proposed scheme is illustrated by the simulation of diving control of an underwater vehicle with hydraulic variable ballast system. Reference | Related Articles | Metrics

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Gram Matrix-Based Convolutional Neural Network for Biometric Identification Using Photoplethysmography Signal WU Caiyu, (吴彩钰), SABOR Nabil, ZHOU Shihong, (周世鸿), WANG Min, (王 敏), YING Liang (应 亮), WANG Guoxing∗ (王国兴) J Shanghai Jiaotong Univ Sci    2022, 27 (4): 463-472.   DOI: 10.1007/s12204-022-2426-5 Abstract （123）      PDF （1049KB）（20）       Knowledge map    As a kind of physical signals that could be easily acquired in daily life, photoplethysmography (PPG) signal becomes a promising solution to biometric identification for daily access management system (AMS). State- of-the-art PPG-based identification systems are susceptible to the form of motions and physical conditions of the subjects. In this work, to exploit the advantage of deep learning, we developed an improved deep convolutional neural network (CNN) architecture by using the Gram matrix (GM) technique to convert time-serial PPG signals to two-dimensional images with a temporal dependency to improve accuracy under different forms of motions. To ensure a fair evaluation, we have adopted cross-validation method and “training and testing” dataset splitting method on the TROIKA dataset collected in ambulatory conditions. As a result, the proposed GM-CNN method achieved accuracy improvement from 69.5% to 92.4%, which is the best result in terms of multi-class classification compared with state-of-the-art models. Based on average five-fold cross-validation, we achieved an accuracy of 99.2%, improved the accuracy by 3.3% compared with the best existing method for the binary-class. Reference | Related Articles | Metrics

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Machine Learning-Based Approach to Liner Shipping Schedule Design DU Jian1∗ (杜 剑), ZHAO Xu2 (赵 旭), GUO Liming2 (郭力铭), WANG Jun2 (王 军) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 411-423.   DOI: 10.1007/s12204-021-2338-9 Abstract （117）      PDF （524KB）（26）       Knowledge map    This paper studied a tactical liner shipping schedule design issue under sail and port time uncertainties, which is the determination of the planned arrival time at each port call as well as the punctuality rate and number of assigned ship on the route. A number of studies have tried to introduce the operational speed adjustment measure into this tactical schedule design issue, to alleviate the discrepancies between designed schedule and maritime practice. On the one hand, weather conditions can lead to speed loss phenomenon of ships, which may result in the failure of ships’ punctual arrivals. On the other hand, improving the ability of speed adjustment can decrease the late-arrival compensation, but increase the fuel consumption cost. Then, we formulated a machine learning-based liner shipping schedule design model aiming at above-mentioned two limitations on speed adjustment measure. And a machine learning-based approach has been designed, where the speed adjustment simulation, the neural network training and the reinforcement learning were included. Numerical experiments were conducted to validate our results and derive managerial insights, and then the applicability of machine learning method in shipping optimization issue has been confirmed. Reference | Related Articles | Metrics

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Experimental Study on Hydrodynamic Response of Semisubmersible Platform-Based Bottom-Hinged Flap Wave Energy Converter LIN Yana∗ (林 焰), PEI Feib (裴 斐) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 307-315.   DOI: 10.1007/s12204-022-2443-4 Abstract （115）      PDF （1368KB）（36）       Knowledge map    A semisubmersible platform-based (SPB) bottom-hinged flap (BHF) wave energy converter (WEC) concept is presented in this paper, and its platform hydrodynamic response was studied experimentally. Aimed at studying the special WEC-mounted platform response problem, both regular and irregular wave experiments were conducted. The frequency domain results of regular wave experiments are described in the form of response amplitude operators. The time domain results of irregular wave experiments are treated by statistical analysis and fast Fourier transformation. Regular wave experiments and irregular wave experiments show good consistency. The mooring system strongly affects the whole system, which is a considerable factor for WEC design. The influences of BHF mounted on the platform are revealed in both statistic and frequency spectral ways. The results of experiments give a guide for SPB design aiming to support BHF-WEC. Reference | Related Articles | Metrics

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System Life and Reliability Modeling of a Multiple Power Takeoffs Accessory Gearbox Transmission WANG Kai∗ (汪 凯), WANG Xianliang (王宪良), ZHU Jiazan (朱加赞), OU Daisong (欧代松), PAN Daifeng (潘代锋) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 855-866.   DOI: 10.1007/s12204-022-2473-y Abstract （115）      PDF （1635KB）（17）       Knowledge map    A mathematical model for system life and reliability of a multiple power takeoffs aeroengine accessory gearbox transmission is presented. The geometry model of gear train is distributed into several subsystems by different transmitted powers. The lives of each component are combined to determine the units, subsystems and entire system lives sequentially according to a strict series probability model. The unit and subsystem interface models are defined to dispose the loads of common components. The algorithm verification is presented and a numerical example is given to illustrate the use of this program. The initial design could not fulfill the life requirement. A design modification shows that the gear train has a more balanced life distribution by strengthening the weak parts, and the overall life of entire system is increased above the design requirement. This program can help the designer to approach an optimal accessory gearbox transmission design efficiently. Reference | Related Articles | Metrics

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Breast Pathological Image Classification Based on VGG16 Feature Concatenation LIU Min (刘 敏), YI Ming (易 鸣), WU Minghu∗ (武明虎), WANG Juan (王 娟), HE Yu (何 宇) J Shanghai Jiaotong Univ Sci    2022, 27 (4): 473-484.   DOI: 10.1007/s12204-021-2398-x Abstract （107）      PDF （5914KB）（15）       Knowledge map    Breast cancer is one of the malignancies that endanger women’s health all over the world. Considering that there is some noise and edge blurring in breast pathological images, it is easier to extract shallow features of noise and redundant information when VGG16 network is used, which is affected by its relative shallow depth and small convolution kernel. To improve the pathological diagnosis of breast cancers, we propose a classification method for benign and malignant tumors in the breast pathological images which is based on feature concatenation of VGG16 network. First, in order to improve the problems of small dataset size and unbalanced data samples, the original BreakHis dataset is processed by data augmentation technologies, such as geometric transformation and color enhancement. Then, to reduce noise and edge blurring in breast pathological images, we perform bilateral filtering and denoising on the original dataset and sharpen the edge features by Sobel operator, which makes the extraction of shallow features by VGG16 model more accurate. Based on transfer learning, the network model trained with the expanded dataset is called VGG16-1, and another model trained with the image denoising and sharpening and mixed with the original dataset is called VGG16-2. The features extracted by VGG16-1 and VGG16-2 are concatenated, and then classified by support vector machine. The final experimental results show that the average accuracy is 98.44%, 98.89%, 98.30% and 97.47%, respectively, when the proposed method is tested with the breast pathological images of 40×, 100×, 200× and 400× on BreakHis dataset. Reference | Related Articles | Metrics

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Hydrodynamic Performance of Air-Filled Wave Attenuator for Wave Control: Experimental Study PEREIRA Eric Joseph1 (佩雷拉·埃里克·约瑟夫), TEH Hee-Min1,2∗ (郑希铭), MA Zhe3 (马 哲) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 316-325.   DOI: 10.1007/s12204-022-2444-3 Abstract （104）      PDF （901KB）（26）       Knowledge map    Numerous types of floating breakwaters have been proposed, tested and commercialized in the past decades. The majority of these breakwaters are made of solid bodies; hence, they are relatively bulky and are not readily to be rapidly installed at the targeted sites when immediate wave protection of the coastal and offshore facilities is needed. Furthermore, the application of these hard floating structures at the recreational beaches is rather unlikely due to potential deadly marine traffic collision. To overcome these problems, a flexible air-filled wave attenuator (AFWA) has been developed in the present study. This floating breakwater is made of flexible waterproof membrane materials. The main body consists of a rectangular air-filled prism and is ballasted by sandbags located around the floating module. The objective of this study is to evaluate the wave transmission, wave reflection, energy dissipation, motion responses and mooring forces of the AFWA under the random wave actions using physical modelling. The test model located in a 20 m long wave flume was subjected to a range of wave heights and periods. The wave profiles in the vicinity of the test model were measured using wave probes for determination of wave transmission, reflection and energy loss coefficients. The motion responses in terms of heave, surge and pitch, and wave forces acting on the mooring lines were measured using a motion tracking system and load cells, respectively. The experimental results reveal that the AFWA is effective in attenuating up to 95% in the incoming wave height and has low-wave-reflection properties, which is commendable for floating breakwaters. Reference | Related Articles | Metrics

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Improved Spatial Registration Algorithm for Sensors on Multiple Mobile Platforms LÜ Runyan (吕润妍), PENG Na (彭娜), WU Yi (吴怡), CAI Yunze∗ (蔡云泽) J Shanghai Jiaotong Univ Sci    2022, 27 (5): 638-648.   DOI: 10.1007/s12204-022-2457-y Abstract （100）      PDF （1035KB）（15）       Knowledge map    This paper focuses on the spatial registration algorithm under the earth-centered earth-fixed (ECEF) coordinate system for multiple mobile platforms. The sensor measurement biases are discussed with the platform attitude information taken into consideration. First, the biased measurement model is constructed. Besides, the maximum likelihood registration (MLR) algorithm is discussed to simultaneously estimate the measurement biases and the target state. Finally, an improved online MLR (IMLR) algorithm is proposed through a sliding window of adaptive size. Simulation results demonstrate that the proposed IMLR algorithm effectively improves the realtime ability of the system and can approach similar estimation accuracy to the conventional MLR algorithm. Reference | Related Articles | Metrics

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Bending Prediction Method of Multi-Cavity Soft Actuator HUO Qianjun (霍前俊), LIU Sheng∗ (刘胜), XU Qingyu (徐青瑜), ZHANG Yuanfei (张远飞), ZHANG Yaoyao (张耀耀), LI Xu (李旭) J Shanghai Jiaotong Univ Sci    2022, 27 (5): 631-637.   DOI: 10.1007/s12204-021-2334-0 Abstract （99）      PDF （1302KB）（12）       Knowledge map    The multi-cavity soft actuator is assembled from single-cavity soft actuator through a reasonable geometric distribution. It has the characteristic that the pneumatic soft actuator is driven by its own deformation and has more degrees of freedom. Pneumatic soft actuator is widely used as an emerging discipline and its strong compliance has been greatly developed and applied. However, as the most application potential type of soft actuators, there is still a lack of simple and effective deformation prediction methods for studying the spatial deformation of multi-cavity soft actuators. To solve this problem, a vector equation method is proposed based on the analysis of the principle of the space deformation of the two-cavity, three-cavity and four-cavity soft actuators. Furthermore, a nonlinear mathematical model of the air pressure, space position and deformation trajectory of the soft actuator end is established by combining the vector equation method. Finally, the three-channel soft actuator is verified through experiments. The results show that the mathematical model can better predict the space deformation trajectory of the soft actuator, which provides a new research method for studying the space deformation of the multi-channel soft actuator. Reference | Related Articles | Metrics

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Multiobjective Optimization of Hull Form Based on Global Optimization Algorithm LIU Jiea (刘 洁), ZHANG Baojib∗ (张宝吉) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 346-355.   DOI: 10.1007/s12204-022-2445-2 Abstract （99）      PDF （942KB）（27）       Knowledge map    Rankine source method, optimization technology, parametric modeling technology, and improved mul tiobjective optimization algorithm were combined to investigate the multiobjective optimization design of hull form. A multiobjective and multilevel optimization design framework was constructed for the comprehensive navigation performance of ships. CAESES software was utilized as the optimization platform, and nondominated sorting genetic algorithm II (NSGA-II) was used to conduct multiobjective optimization research on the resis tance and sea-keeping performance of the ITTC Ship A-2 fishing vessel. Optimization objectives of this study are heave/pitch response amplitude and wave-making resistance. Taking the displacement and the length between perpendiculars as constraints, we optimized the profile of the hull. Analytic hierarchy process (AHP) and tech nique for order preference by similarity to ideal solution (TOPSIS) were used to sort and select Pareto solutions and determine weight coefficient of each navigation performance objective in the general objective. Finally, the hydrodynamic performance before and after the parametric deformation of the hull was compared. The results show that both the wave-making resistance and heave/pitch amplitude of the optimized hull form are reduced, and the satisfactory optimal hull form is obtained. The results of this study have a certain reference value for the initial stage of multiobjective optimization design of hull form. Reference | Related Articles | Metrics

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Further Result on the Observer Design for One-Sided Lipschitz Systems YANG Ming1 (杨 明), HUANG Jun1∗ (黄 俊), ZHANG Wei2 (章 伟) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 817-822.   DOI: 10.1007/s12204-020-2252-6 Abstract （99）      PDF （328KB）（69）       Knowledge map    This paper investigates the problem of observer design for a class of control systems. Different from current works, the nonlinear functions in the system only satisfy the property of the one-sided Lipschitz (OSL) condition but not quadratic inner-boundedness (QIB). Moreover, the case where the OSL constant is negative is specially investigated. Firstly, a full-order observer is constructed for the original system. Then, a reduced-order observer is also designed by using the decomposition method. The advantage and effectiveness of the proposed design scheme are shown in a numerical simulation. Reference | Related Articles | Metrics

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Effect of Moving Endwall on Hub Leakage Flow of Cantilevered Stator in a Linear Compressor Cascade ZHENG Biaojie (郑标颉), MA Yuchen (马宇晨), TENG Jinfang∗ (滕金芳), JU Zhenzhou (居振州), ZHU Mingmin (朱铭敏) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 780-789.   DOI: 10.1007/s12204-022-2468-8 Abstract （97）      PDF （2018KB）（27）       Knowledge map    The cantilevered stator has the advantages of reducing mass and axial length of highly loaded compressor. The details of the hub leakage flow resulting from the clearance between the high-speed moving hub and the cantilevered stator hub are unclear. In this paper, the effect of a moving endwall on the hub leakage flow of a cantilevered stator in a linear compressor cascade was studied. After the simulation method was verified with the experimental results, the time-averaged results of unsteady Reynolds averaged Navier-Stokes (URANS) were selected to study a case with a hub clearance of 2 mm. The results show that the effect of the moving endwall of the cantilevered cascade on the general characteristics with below 30% span increases the leakage mass flow rate and reduces the static pressure coefficient at three conditions of 0°, 6°, and -7° incidences, and the change is most significant at -7° incidence. The effect of the moving endwall on the total pressure loss coefficient varies with different operating conditions, which decreases by 15.94% at 0° incidence, and increases by 4.77% and 18.51% at 6° incidence and -7° incidence, respectively. The influence of the moving endwall is below 14% span at -7° incidence, below 23% span at 0° incidence, and below 30% span at 6° incidence. These effects correspond to the static pressure coefficient and the difference of static pressure coefficient representing the blade loading. In designing the cantilevered stator and matching between the stages of a multistage compressor, the quantitative research results of this paper have certain guiding significance. Reference | Related Articles | Metrics

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Intelligent Driving Assistance System for Safe Expressway Driving in Rainy and Foggy Weather based on IoT YAN Beirui (燕北瑞), FANG Cheng (方 成), QIU Hao (邱 昊), ZHU Wenfeng∗ (朱文峰) J Shanghai Jiaotong Univ Sci    2023, 28 (1): 10-19.   DOI: 10.1007/s12204-023-2564-4 Abstract （97）      PDF （2162KB）（17）       Knowledge map    The feature bends and tunnels of mountainous expressways are often affected by bad weather, specifically rain and fog, which significantly threaten expressway safety and traffic efficiency. In order to solve this problem, a vehicle–road coordination system based on the Internet of Things (IoT) is developed that can share vehicle–road information in real time, expand the environmental perception range of vehicles, and realize vehicle–road collaboration. It helps improve traffic safety and efficiency. Further, a vehicle–road cooperative driving assistance system model is introduced in this study, and it is based on IoT for improving the driving safety of mountainous expressways. Considering the influence of rain and fog on driving safety, the interaction between rainfall, water film, and adhesion coefficient is analyzed. An intelligent vehicle–road coordination assistance system is constructed that takes in information on weather, road parameters, and vehicle status, and takes the stopping sight distance model as well as rollover and sideslip model as boundary constraints. Tests conducted on a real expressway demonstrated that the assistance system model is helpful in bad weather conditions. This system could promote intelligent development of mountainous expressways. Reference | Related Articles | Metrics

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Data Driven Model-Free Adaptive Control Method for Quadrotor Trajectory Tracking Based on Improved Sliding Mode Algorithm YUAN Dongdong (袁冬冬), WANG Yankai∗ (王彦恺) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 790-798.   DOI: 10.1007/s12204-020-2254-4 Abstract （96）      PDF （1004KB）（29）       Knowledge map    In order to solve the problems of dynamic modeling and complicated parameters identification of trajectory tracking control of the quadrotor, a data driven model-free adaptive control method based on the improved sliding mode control (ISMC) algorithm is designed, which does not depend on the precise dynamic model of the quadrotor. The design of the general sliding mode control (SMC) algorithm depends on the mathematical model of the quadrotor and has chattering problems. In this paper, according to the dynamic characteristics of the quadrotor, an adaptive update law is introduced and a saturation function is used to improve the SMC. The proposed control strategy has an inner and an outer loop control structures. The outer loop position control provides the required reference attitude angle for the inner loop. The inner loop attitude control ensures rapid convergence of the attitude angle. The effectiveness and feasibility of the algorithm are verified by mathematical simulation. The mathematical simulation results show that the designed model-free adaptive control method of the quadrotor is effective, and it can effectively realize the trajectory tracking control of the quadrotor. The design of the controller does not depend on the kinematic and dynamic models of the unmanned aerial vehicle (UAV), and has high control accuracy, stability, and robustness. Reference | Related Articles | Metrics

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Submarine Multi-Model Switching Control Under Full Working Condition Based on Machine Learning LIANG Liang1 (梁 良), SHI Ying1∗ (石 英), MOU Junmin2∗ (牟军敏) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 402-410.   DOI: 10.1007/s12204-021-2284-6 Abstract （96）      PDF （629KB）（26）       Knowledge map    A continuous submarine depth control strategy based on multi-model and machine learning switching method under full working condition is proposed in this paper. A submarine motion model with six-degree-of freedom is first built and decoupled according to the force analysis. The control set with corresponding precise model set is then optimized according to different working conditions. The multi-model switching strategy is studied using machine learning algorithm. The simulation experiments indicate that a multi-model controller comprised of the proportional-integral-derivative (PID), fuzzy PID (FPID) and model predictive controllers with support vector machine (SVM) switching strategy can realize the continuous submarine depth control under full working condition, showing a good control performance compared with a single PID controller. Reference | Related Articles | Metrics

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Effects of Elastic Joints on Performances of a Close-Chained Rod Rolling Robot ZHAO Chenliang (赵晨亮), ZHANG Xiuli∗ (张秀丽), HUANG Senwei (黄森威), YAO Yan’an (姚燕安) J Shanghai Jiaotong Univ Sci    2022, 27 (5): 621-630.   DOI: 10.1007/s12204-021-2289-1 Abstract （93）      PDF （1792KB）（14）       Knowledge map    In rolling experiments, the performances of spider-like robot are limited greatly by its motors’ driving ability; meanwhile, the ground reaction forces are so great that they damaged the rods. In this paper, we solve above problems both mechanically and by control. Firstly, we design the parameters of the central pattern generator (CPG) network based on the kinematics of the robot to enable a smooth rolling trajectory. And we also analyze the kinematic rolling and dynamic rolling briefly. Secondly, we add torsion springs to the passive joints of the spider-like robot aiming to make use of its energy storage capacity to compensate the insufficient torque. The simulation results show that the optimized CPG control parameters can reduce the fluctuation of the mass center and the ground reaction forces. The torsion spring can reduce the peak torque requirements of the actuated joints by 50%. Reference | Related Articles | Metrics

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Case Study of a Personalized Scoliosis Brace Based on 3D Printing LU Dezhi 1,2‡ (鲁德志), LI Wentao1‡ (李文韬), WANG Xiaowen2 (王孝文), SONG Yan2 (宋 艳), ZHANG Pingping2 (张萍萍), FENG Haiyang2 (冯海洋), WU Yuncheng1 (吴云成), XU Yuanjing3 (许苑晶), LI Tao4 (李 涛), MA Zhenjiang1∗ (马振江), WANG Jinwu1,2∗ (王金武) J Shanghai Jiaotong Univ Sci    2022, 27 (4): 528-534.   DOI: 10.1007/s12204-022-2461-2 Abstract （93）      PDF （653KB）（14）       Knowledge map    We evaluated the effect of a new type of brace (primary material 3300PA) for treating scoliosis, which was produced based on 3D printing technology combined with a non-contact optical mold-taking and computer- aided design. Through the production of a brace for a 13-year-old patient with adolescent idiopathic scoliosis by a multidisciplinary team, the digital design and 3D printing of a personalized scoliosis brace were introduced. Parameters such as the Cobb angle, angle of trunk inclination, spine-coronal plane balance parameters, sagittal vertical axis (SVA), and Scoliosis Research Society-22 score (SRS-22) were measured to evaluate the treatment effect of the brace. The model-taking process of the non-contact optical scanner was successful, data were valid, and personalized scoliosis brace made by the computer-aided design and 3D printing fitted well with the patient. Before wearing, immediate in-brace, and 6 months after wearing, the Cobb angles were 29?, 9?, a n d 1 4?, respectively. The offsets between the C7 vertebra plumb line (C7PL) and central sacral vertical line (CSVL) were 3.2 cm, 2.2 cm, and 2.1 cm, respectively. SVAs were 3.3 cm, 2.9 cm, and 0.3 cm, respectively. Apex vertebral translocations were 4.3 cm, 0.3 cm, and 0.1 cm, respectively. The SRS-22 was 76 before brace application and 91 at the 6-month follow-up. The spine curve returned to normal, and the correction effect was obvious. The scoliosis brace indicates the integration between digital medicine and 3D printing technology, which has personalization and customization as advantages. The brace has good wearing comfort, invisibility, and orthopedic function, follows the psychological needs of teenagers, improves patients’ compliance, and improves the correction of the deformity. Reference | Related Articles | Metrics

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Numerical Simulation of the Flow in a Waterjet Intake Under Different Motion Conditions XU Huilia (许慧丽), ZOU Zaojiana,b∗ (邹早建) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 356-364.   DOI: 10.1007/s12204-021-2321-5 Abstract （91）      PDF （2634KB）（19）       Knowledge map    By solving the three-dimensional incompressible Reynolds-averaged Navier-Stokes equations, numerical simulations of the viscous flow within a flush type intake duct of a waterjet under different motion conditions are carried out. Therein, the effects of the steering and reversing unit as well as the impeller shaft on the flow field are taken into account. The numerical results show that the static pressure under backward conditions with the reversing jet flow is the lowest, and the cavitations are most likely to occur within the intake duct. The flow field under forward conditions is less uniform because of the shaft, while the velocity uniformity under backward conditions is improved. The shaft rotation causes an asymmetric secondary flow above the shaft under all conditions. The pressure contours under backward conditions with the reversing jet flow are sensitive to the presence of the shaft. This study can provide some references for the design optimization of waterjet propulsion system. Reference | Related Articles | Metrics

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Multi-UAV Route Re-Generation Method Based on Trajectory Data YUAN Dongdong (袁冬冬), WANG Yankai∗ (王彦恺), BAI Jiaqi (白嘉琪) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 806-816.   DOI: 10.1007/s12204-021-2332-2 Abstract （90）      PDF （1409KB）（17）       Knowledge map    A large quantity of unmanned aerial vehicle (UAV) trajectory data related to air traffic information has important value in engineering fields. However, the cost of data and trajectory processing limits the applications, and as the number of UAVs increases rapidly, future UAVs’ path data will be very large. Therefore, this paper designs a multi-UAV route re-generation method based on trajectory data, which can realize the UAVs’ path data compression, de-aggregation, and regeneration tasks. Based on the trajectory data, the three-dimensional Douglas-Peucker algorithm is used to compress the trajectory data to reduce the storage space. The improved B-spline path smoothing algorithm based on the reversing control point is used to depolymerize and smooth the path. Simulation experiments show that the above multi-UAV route re-generation algorithm can obtain a more optimized path while maintaining the important characteristics of the original path. Reference | Related Articles | Metrics

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Game Theory Based Sensor Management in Reducing Target Threat Level Assessment Risk PANG Ce∗ (庞策), SHAN Ganlin (单甘霖) J Shanghai Jiaotong Univ Sci    2022, 27 (5): 649-659.   DOI: 10.1007/s12204-021-2372-7 Abstract （90）      PDF （822KB）（14）       Knowledge map    Sensor management schemes are calculated to reduce target threat level assessment risk in this paper. Hidden Markov model and risk theory are combined to build the target threat level model firstly. Then the target threat level estimation risk is defined. And the sensor management schemes are optimized with the smallest target threat level assessment risk. What’s more, the game theory is applied to calculate the optimal sensor management scheme. Some simulations are conducted to prove that the proposed sensor management method is effective. Reference | Related Articles | Metrics

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Target Detection Algorithm Based On Human Judge Mechanism SHI Jichao1 (石继超), WANG Ziheng2 (王子恒), ZHAO Xianchao1 (赵现朝), ZHANG Zhinan1∗ (张执南) J Shanghai Jiaotong Univ Sci    2022, 27 (5): 660-670.   DOI: 10.1007/s12204-022-2450-5 Abstract （90）      PDF （1795KB）（11）       Knowledge map    A D-G-YOLOV3 algorithm was proposed to identify and judge recyclables, which introduced a dense feature network to replace the feature pyramid network. The network closely connects and fits the feature maps and simulates human judgment mechanism. A three-stage judgment is made for judgment objects with lower confidence. Based on the judgment of the original image, the second-stage judgment is carried out after the channel contrast is increased. Finally, sampling is performed on the region of interest where the second-stage confidence score wins for the third stage of judgment, and then judgment result is sent to the gated recurrent unit network for final inference. The result shows that through experiments on the same recyclables data set, the algorithm reduces the missed detection rate by 15.54%, and the false detection rate by 0.97%, while improves the accuracy rate by 16.51%. Reference | Related Articles | Metrics

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Air Combat Assignment Problem Based on Bayesian Optimization Algorithm FU Lia (傅 莉), LONG Xia∗ (龙 洗), HE Wenbinb (何文斌) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 799-805.   DOI: 10.1007/s12204-021-2270-z Abstract （89）      PDF （519KB）（26）       Knowledge map    In order to adapt to the changing battlefield situation and improve the combat effectiveness of air combat, the problem of air battle allocation based on Bayesian optimization algorithm (BOA) is studied. First, we discuss the number of fighters on both sides, and apply cluster analysis to divide our fighter into the same number of groups as the enemy. On this basis, we sort each of our fighters’ different advantages to the enemy fighters, and obtain a series of target allocation schemes for enemy attacks by first in first serviced criteria. Finally, the maximum advantage function is used as the target, and the BOA is used to optimize the model. The simulation results show that the established model has certain decision-making ability, and the BOA can converge to the global optimal solution at a faster speed, which can effectively solve the air combat task assignment problem. Reference | Related Articles | Metrics

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Reliability Evaluation of Two-Phase Degradation Process with a Fuzzy Change-Point LIU Kai1 (刘 凯), DANG Wei1 (党 炜), ZOU Tianji1,2∗ (邹田骥), LÜ Congmin1 (吕从民), LI Peng1,2 (李 鹏), ZHANG Haitao1 (张海涛) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 867-872.   DOI: 10.1007/s12204-021-2323-3 Abstract （88）      PDF （484KB）（33）       Knowledge map    For some products, degradation mechanisms change during testing, and therefore, their degradation patterns vary at different points in time; these points are called change-points. Owing to the limitation of measurement costs, time intervals for degradation measurements are usually very long, and thus, the value of change-points cannot be determined. Conventionally, a certain degradation measurement is selected as the change-point in a two-phase degradation process. According to the tendency of the two-phase degradation process, the change-point is probably located in the interval between two neighboring degradation measurements, and it is a fuzzy variable. The imprecision of the change-point may lead to the incorrect product’s reliability evaluation results. In this paper, based on the fuzzy theory, a two-phase degradation model with a fuzzy change-point and a statistical analysis method are proposed. First, a two-phase Wiener degradation model is developed according to the membership function of the change-point. Second, the reliability evaluation is carried out using maximum likelihood estimation and a fuzzy simulation approach. Finally, the proposed methodology is verified via a case study. The results of the study show that the proposed methodology can achieve more believable reliability evaluation results compared with those of the conventional approach. Reference | Related Articles | Metrics

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Semantic Segmentation-Based Road Marking Detection Using Around View Monitoring System XU Hanqing (徐汉卿), YANG Ming∗ (杨 明), DENG Liuyuan (邓琉元), LI Hao (李 颢), WANG Chunxiang, (王春香), HAN Weibin (韩伟斌), YU Yuelong (于跃龙) J Shanghai Jiaotong Univ Sci    2022, 27 (6): 833-843.   DOI: 10.1007/s12204-021-2401-6 Abstract （88）      PDF （1134KB）（27）       Knowledge map    Road marking detection is an important branch in autonomous driving, understanding the road information. In recent years, deep-learning-based semantic segmentation methods for road marking detection have been arising since they can generalize detection result well under complicated environments and hold rich pixel-level semantic information. Nevertheless, the previous methods mostly study the training process of the segmentation network, while omitting the time cost of manually annotating pixel-level data. Besides, the pixel-level semantic segmentation results need to be fitted into more reliable and compact models so that geometrical information of road markings can be explicitly obtained. In order to tackle the above problems, this paper describes a semantic segmentation-based road marking detection method using around view monitoring system. A semiautomatic semantic annotation platform is developed, which exploits an auxiliary segmentation graph to speed up the annotation process while guaranteeing the annotation accuracy. A segmentation-based detection module is also described, which models the semantic segmentation results for the more robust and compact analysis. The proposed detection module is composed of three parts: vote-based segmentation fusion filtering, graph-based road marking clustering, and road-marking fitting. Experiments under various scenarios show that the semantic segmentation-based detection method can achieve accurate, robust, and real-time detection performance. Reference | Related Articles | Metrics

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Dynamic Modeling and Performance Evaluation of a Novel Humanoid Ankle Joint LI Yanbiao∗ (李研彪), CHEN Ke (陈 科), SUN Peng (孙 鹏), WANG Zesheng (王泽胜) J Shanghai Jiaotong Univ Sci    2022, 27 (4): 570-578.   DOI: 10.1007/s12204-022-2422-9 Abstract （88）      PDF （1322KB）（10）       Knowledge map    Aimed at the problems of design difficulty and weak kinematic performance caused by spherical joint, a novel PRC+PRCR+RR humanoid ankle joint based on the partially decoupled spherical parallel mechanism is proposed. According to screw theory, the degree of freedom and decoupling characteristics of this mechanism are analyzed. Based on Klein formula and virtual work principle, the kinematic expressions of each link and dynamic model are established. The correctness of the dynamic model is verified by combining the virtual prototype software and the ankle pose function obtained by gait planning and Fourier fitting. The workspace of this mechanism is mapped into a two-dimensional polar coordinate system with the azimuth and elevation angles of the spherical coordinate system as parameters. The motion/force transmission index and constraint index of this mechanism are evaluated and expressed in the workspace, showing this mechanism with excellent kinematic characteristics. Reference | Related Articles | Metrics

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Shipping Economics Development: A Review from the Perspective of the Shipping Industry Chain for the Past Four Decades XIA Qiliang (夏启亮), CHEN Feier ∗ (陈飞儿) J Shanghai Jiaotong Univ Sci    2022, 27 (3): 424-436.   DOI: 10.1007/s12204-022-2449-y Abstract （87）      PDF （622KB）（34）       Knowledge map    To know the development of shipping economics, it is meaningful to overview shipping economics systemically from the perspective of markets and the shipping industry chain. To stimulate future research, this article presents an introduction to the evolution of research models including static models, dynamic models and networks theory, the characteristics of shipping markets including volatility, seasonal and market cycle, and a comprehensive review of the development of shipping economics in the past four decades. We review shipping economics in the following steps: single market’s research is generalized including the freight market, financial market including FFA market and investment market, shipbuilding market, and secondhand market; two markets’ correlation, information transmission, spillover effects, and other rules in shipping markets are surveyed; the correlation and risk of multi-markets are also investigated. Then, we summarize relationships of the shipping industry chain. Finally, we figure out issues in this field that need further study. Reference | Related Articles | Metrics