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2nd International Conference of Mechanical system Dynamics, ICMSD 2023

作者： Zhang, Wenfeng Cai, Xiaoshuang Liu, Zhendong Liu, Xiong Tong, Yifan Shanghai Aerospace Systems Engineering Institute Shanghai China School of Science Nanjing University of Science and Technology Nanjing China Institute of Launch Dynamics Nanjing University of Science and Technology Nanjing China National Key Laboratory of Complex Multibody System Dynamics Nanjing University of Science and Technology Nanjing China

ISBN: (纸本)9789819980475

In order to improve launching capability and performance, almost all launch vehicles in active service contain two or more stages. During the launch process, it is of vital importance to gradually reduce the weight of the launch vehicles by separating and jettisoning spent stages which have burned out its propellant. The separation process between the stages plays a crucial role in guaranteeing the safety of the launch vehicles and ensuring a successful launch. Consequently, it is essential for launch vehicle designers to well understand the stage-separation dynamics which is quite complex and affected by many system parameters. To evaluate the impact of the system parameters on the stage-separation mission, a parameterized model is established for a two-stage launch vehicle using the Modelica language along with the software MWorks. As representative parameters to evaluate, the mass-center positions of the first and second stages, both the positions and directions of the active forces, the residual thrusts, the positive thrusts, the retro thrusts, the masses and moments of inertia of the two stages, are all taken into account for dynamic analysis. The parameterized Modelica model is built by exploiting the idea of the equation-based causal modelling to numerically simulate the stage-separation process and evaluate the influence of the parameters on the system responses. simulation results based on representative case studies indicate that the separation process of the first and second stages can be well described by the Modelica model. Besides, a comparison with Adams software demonstrates the results of the Modelica model agree well with those obtained using Adams. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

关键词： Launch vehicles

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Performance comparison of lithium fractionation from magnesium via continuous selective nanofiltration/electrodialysis

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Chinese Journal of Chemical Engineering 2023年第7期59卷 42-50页

作者： Yong Xu Qingbai Chen Yang Gao Jianyou Wang Huiqing Fan Fei Zhao Tianjin Key Laboratory of Environmental Technology for Complex Trans-Media Pollution College of Environmental Science and EngineeringNankai UniversityTianjin 300350China College of Chemical Engineering and Material Quanzhou Normal UniversityQuanzhou 362000China Center for Water and Ecology State Key Joint Laboratory of Environment Simulation and Pollution ControlSchool of EnvironmentTsinghua UniversityBeijing 100084China

Although selective nanofiltration(SNF)and selective electrodialysis(SED)have been widely adopted in the field of Mg^(2+)/Li^(+)separation,their differences have not been illustrated *** this study,for the first time,SNF and SED processes in continuous mode were studied for Li+fractionation from the same brine with high Mg/Li ratios and their differences were discussed in *** a fair analysis of the two processes,typical factors were ***,the optimal operating pressure and feed flow rate for SNF were 2.4 MPa and 140 L·h^(-1),respectively,while the optimal cell-pair voltage and replenishment flow rate for SED were 1.0 V and 14 L·h^(-1),*** the Li^(+)fractionation capacity of the two processes were similar,the selectivity coefficient of SNF was 24.7% higher than that of SED and,thus,the Mg/Li ratio in purified stream of the former was 19.0% lower than that of the *** to higher ion driving force,SED had clear advantages in recovery ratio and concentration ***,the specific energy consumption of SED was 20.1% lower than that of *** study provided a better understanding and guidance for the application and improvement of the two technologies.

关键词： High Mg/Li brine Purification Membrane Nanofiltration Electrodialysis Lithium recovery

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MBSE-Based Guidance system simulation of Launch Vehicle 2nd

MBSE-Based Guidance System Simulation of Launch Vehicle

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2nd International Conference of Mechanical system Dynamics, ICMSD 2023

作者： Ma, Guowei Wang, Qingtao Zhang, Wenfeng Yu, Rendong Liu, Xiong School of Science Nanjing University of Science and Technology Nanjing China Institute of Launch Dynamics Nanjing University of Science and Technology Nanjing China National Key Laboratory of Complex Multibody System Dynamics Nanjing University of Science and Technology Nanjing China Shanghai Aerospace Systems Engineering Institute Shanghai China

ISBN: (纸本)9789819980475

In the traditional development process of the launch vehicle guidance system, the system is designed repeatedly in the earlier stage and the verification of the system is conducted in the later stage. This development mode may cause some problems, such as low design efficiency and high cost. In order to improve the shortcomings of the traditional development process, in this paper the MBSE (Model Based system Engineering) method is introduced in the design phase of the launch vehicle guidance system, and the MBSE-based design model is used to carry out system verification in real time. The application of this method greatly improves the design efficiency of the launch vehicle guidance system. The MBSE-based simulation model of the launch vehicle guidance system is established, the system perturbation guidance simulation is carried out, and the result is compared with the standard design trajectory to verify the correctness of the guidance system designed based on MBSE. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

关键词： Launch vehicles

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Modeling and simulation of Stage Separation system of Launch Vehicles Based on MWorks 2nd

Modeling and Simulation of Stage Separation System of Launch...

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2nd International Conference of Mechanical system Dynamics, ICMSD 2023

作者： Pu, Jinrui Wang, Qingtao Liu, Zhendong Cai, Xiaoshuang Liu, Xiong School of Science Nanjing University of Science and Technology Nanjing China Institute of Launch Dynamics Nanjing University of Science and Technology Nanjing China National Key Laboratory of Complex Multibody System Dynamics Nanjing University of Science and Technology Nanjing China Shanghai Aerospace Systems Engineering Institute Shanghai China

ISBN: (纸本)9789819980475

The current methods for modeling, simulating, and verifying the stage separation system of a launch vehicle are limited to specific models and cannot be universally validated. Moreover, it is a time-consuming and labor-intensive task to remodel a launch vehicle with different topologies. To address this issue, this paper proposes a solution using the software MWorks. The approach involves establishing basic component models for launch vehicles, including the first stage, second stage, thrust, and explosive bolts. These component models are then utilized to create a model library for the stage separation of a launch vehicle. By employing this library, the stage separation process of a specific launch vehicle model can be simulated and analyzed to ensure the safety of the separation under harsh conditions. This methodology offers a more efficient and flexible approach to validate the stage separation system of launch vehicles. By utilizing the established model library, the need for extensive remodeling is eliminated, saving both time and effort. The simulation results provide valuable insights into the safety and effectiveness of the stage separation process. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

关键词： Launch vehicles

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Pattern Analysis and Placement Optimization of the Four-horn Monopulse for Terahertz Communication

Pattern Analysis and Placement Optimization of the Four-horn...

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2023 Cross Strait Radio science and Wireless technology Conference, CSRSWTC 2023

作者： Lu, Yong-Han Zhu, Zhong-Bo Ma, Jing Shi, Bin Zhang, Yu-Ting Peng, Lin Guilin University of Electronic Technology Key Laboratory of Microwave and Optical Wave Application Technology Guangxi Guilin541004 China National Key Laboratory of Science and Technology on Space Microwave Xi'an710100 China Beijing Simulation Center Science and Technology on Special System Simulation Laboratory Beijing100854 China School of Optoelectronic Engineering Guangxi Key Laboratory of Optoelectronic Information Processing Guilin University of Electronic Technology Guilin541004 China

ISBN: (纸本)9798350358971

The mobile node communication in terahertz monopulse system requires narrow beam to align with the mobile target precisely. In this paper, the radiation pattern of four-horn monopulse antenna is analyzed by use of the geometric optics (GO) and aperture field integration method (AFIM), and an efficient placement optimization to reduce the beamwidth of four-horn monopulse is presented. The optimization combines the genetic algorithm (GA) with GO-AFIM. The GA is employed to seek the optimal positions of the four horns, and the GO and AFIM are introduced into the fitness function of GA to evaluate the individual fitness. The optimization result has narrowed the beamwidth and enhanced gain of radiation pattern. Compared with the simulation in full wave software, the proposed method costs less time in pattern analysis and performs more efficiently in placement optimization. © 2023 IEEE.

关键词： aperture field integration method (AFIM) geometric optics (GO) placement optimization terahertz monopulse

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A Generic Anti-Windup Design under Linear Active Disturbance Rejection Control Scheme

A Generic Anti-Windup Design under Linear Active Disturbance...

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2023 IEEE International Conference on Electrical, Automation and Computer Engineering, ICEACE 2023

作者： Hui, Li Cheng, Xu Hua, Ji Zhide, Yin Wanhai, Hu Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China The 3rd Research Academy of CASIC Beijing China

ISBN: (纸本)9798350309614

A generic anti-windup compensation strategy under Linear Active Disturbance Rejection Control scheme is proposed. The difference, between the controller output and the actuator output, after multiplied by a tunable parameter, together with controller output, is fed back to the extended state observer to compensate controller windup. While windup problem arises in control system, the controller output is expectedly produced, and the disadvantageous influence of nonlinearity on closed-loop dynamics is distinctly alleviated. The approach is employed to a near space vehicle with fin-deflection saturation. The numerical simulations show that the proposed approach has the better effectiveness in active disturbance rejection control designed situation than some previous anti-windup compensation strategy. © 2023 IEEE.

关键词： active disturbance rejection control anti-windup compensation two-step design method Windup problem

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NWD-YOLOv5: A YOLOv5 Model for Small Target Detection Based on NWD Loss 6

NWD-YOLOv5: A YOLOv5 Model for Small Target Detection Based ...

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6th International Conference on Robotics, Intelligent Control and Artificial Intelligence, RICAI 2024

作者： Zhou, Liliang Ran, Huaming Xiong, Rongling Tan, Ruijie National Key Laboratory of Complex Aviation System Simulation Chengdu610036 China 10th Research Institute China Electronics Technology Group Corporation Chengdu610036 China School of Mathematics Southwest Jiaotong University Chengdu611756 China

ISBN: (纸本)9798331541699

Target detection technology is vital in modern social management and urban security, with small target detection—accurately identifying tiny objects in large scenes—posing a key challenge for improving surveillance system accuracy and real-time performance. The YOLO series is still the mainstream target detection model, for the YOLOv5 model, as the IoU metric it adopts still uses the geometrical overlap of the detection frame as the basis of the loss calculation, while the experiments have proved that this metric is unable to effectively utilize the small-scale characteristics of small targets. Therefore, improving the loss metric in the existing framework can help the model to pay more attention to the spatial semantic features of small targets in the image in the training phase of the network, respectively, and thus improve the detection effect. In this paper, we propose the NWDYOLOv5 model, i.e., we introduce the NWD loss that measures the difference in the distribution of the detection frames for the existing target detection framework YOLOv5, which ensures that the loss of the small targets is not neglected in the calculation of the forward propagation loss of the model, and we purposefully modify the structure of the feature extraction network in the original framework by adding a feature extraction layer for the detection of the small targets, which enhances the ability of the model to capture the subtle features thus improving the accuracy of small target detection. Through comparative experiments, we evaluated the detection performance of the original YOLOv5 model, the YOLOv5 model using only the NWD loss, the YOLOv5 model with only the additional small-target detection layer, and the full NWD-YOLOv5 model for small-targeted human bodies on the screened COCO2017 public dataset, respectively. The experimental results show that compared to the original YOLOv5 model, the model with only the NWD loss improves the mAP@.5 metrics on small-target detection by 16.5

关键词： Digital elevation model

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Research on Key Technologies of Cross-domain Guidance 8

Research on Key Technologies of Cross-domain Guidance

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8th Symposium on Novel Photoelectronic Detection technology and Applications

作者： Guo, Xiaoyun Wu, Chengfeng Fang, Xueli Xu, Cheng Li, Hui Beijing Institute of Mechanical and Electrical Engineering Beijing China Beijing Institute of Mechanical and Electrical Engineering Science and Technology on Complex System Control and Intelligent Agent Cooperative Laboratory Beijing China Beijing Institute of Mechanical and Electrical Engineering Key Laboratory of Complex Aviation Simulation System Beijing China

ISBN: (数字)9781510653122

ISBN: (纸本)9781510653115

Cross-domain synergy and intelligence will become important features of future warfare. Cross-domain guidance is one of the typical forms of cross-domain synergy. It can significantly improve the ability to respond quickly to random targets and time-sensitive targets and enhance the anti-jamming ability in the case of confrontation. This article introduces the concept and winning mechanism of cross-domain guidance, analyzes the research progress of cross-domain guidance at home and abroad, combs the key technologies of cross-domain guidance, summarizes the current challenges and problems in cross-domain guidance research, and proposes development suggestions. © 2022 SPIE

关键词： Optical engineering

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Evolutionary Interest Representation Network for Click-Through Rate Prediction

Evolutionary Interest Representation Network for Click-Throu...

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2023 IEEE International Conference on Web Services, ICWS 2023

作者： Zhou, Renjie Jin, Zhenming Wan, Jian Zhang, Jilin Guo, Xingyu Liu, Qiang Hangzhou Dianzi University Key Laboratory of Complex Systems Modeling and Simulation of the Ministry of Education School of Computer Science and Technology Hangzhou China Hangzhou Dianzi University Key Laboratory of Complex Systems Modeling and Simulation of the Ministry of Education Itmo Joint Institute Hangzhou China Zhejiang University of Science and Technology School of Information and Electronic Engineering Hangzhou China Zhejiang Police College Dept. of Computer and Information Technology Hangzhou China

ISBN: (纸本)9798350304855

The rapid development of the Internet has revo-lutionized our lives, providing us with an array of convenient services. However, this revolution has also led to the problem of data overload. Personalized recommendation services have been widely recognized as an effective solution to this problem by both the industrial and academic communities. Accurate prediction of click-through rate (CTR) is a critical task in personalized recommendation systems since it can improve the user's shopping experience, ultimately increasing revenue for the platform. To achieve accurate CTR prediction, it is crucial to capture user interests. While several methods for interest modeling exist, challenges related to user interest evolution and user behavior noise need further attention. This paper proposes a novel CTR prediction model named the Evolutionary Interest Representation Network (EIRN), which learns the evolving interest representation of users from their behaviors, profiles, and environmental attributes. In the model, we introduce an advertisement correlation graph decomposition layer and a noise filter layer to enhance and purify the user behavior representation. An interest extraction layer is designed to capture sequential correlations and common characteristics between user behaviors, representing their interests. Additionally, as user interests evolve over time and their importance changes, an attention-based interest evolution layer is designed to track the evolution of user interests. Our proposed method is validated using four public datasets and an industrial dataset, showing its superiority over existing CTR prediction methods. © 2023 IEEE.

关键词： Forecasting

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Multi-View Subspace Clustering Via Simultaneously Cycle Projection and Similarity Learning

Multi-View Subspace Clustering Via Simultaneously Cycle Proj...

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International Conference on Wavelet Active Media technology and Information Processing (ICWAMTIP)

作者： Xiang Tao Liu Jie Qiao Wenshen Xiao Siying Ye Mao National Key Laboratory of Complex Aviation System Simulation Southwest China Institute of Electronic Technology Chengdu China University of Electronic Science and Technology of China Chengdu China

ISBN: (数字)9798331519254

ISBN: (纸本)9798331519261

At present, most of the existing methods combine the data from different views mechanically to obtain the latent subspace with complementary information, which not only fails to make full use of the data information from specific perspectives but also brings redundancy. Therefore, we propose a novel multi-view subspace clustering method. It utilizes cycle projection to obtain a subspace construction model. At the same time, by learning the global structure and local manifold structure of this subspace while assigning learnable weights to different views, the consensus information among views and specific information from different views are captured according to the importance of different views. In this way, our method effectively reduces the original noise and redundancy, and further carries out the improvement of complementarity and consistency among views. The proposed method is optimized by using the Augmented Lagrangian Multiplier with Alternating Direction Minimization (ALM- ADM) algorithm. Experiment results on benchmark datasets confirm the effectiveness of our method.

关键词： Manifolds Technological innovation Clustering methods Redundancy Noise Clustering algorithms Information processing Media Minimization Similarity learning

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