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Effects of ignition voltage and electrode structure on electric ignition and combustion characteristics of Ammonium Dinitramide(ADN)-based liquid propellants in electric ignition mode in inert gas environment

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Chinese Journal of Aeronautics 2024年第4期37卷 229-242页

作者： Lei LI Guoxiu LI Hongmeng LI Zhaopu YAO Tao ZHANG Jinze WU Shuo ZHANG School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Beijing institute of control engineering Beijing 100190China

Hydrazine is toxic and carcinogenic, which greatly increases the difficulty of application and no longer meets the needs of green aerospace. As a green propellant, the Ammonium Dinitramide(ADN)-based liquid propellant has the advantages of higher specific impulse, being non-toxic,pollution-free, and easy storage. However, an ADN-based space engine in orbit has exposed the problems of high-temperature deactivation of catalysts and cold-start failure. An active ignition technology—electric ignition technology was explored in this paper to break through the technical bottleneck of catalyst deactivation and the inability to a cold start. An experimental system of a constant-volume combustor for the ADN-based liquid propellant based on the electric ignition method was established. The electric ignition and combustion characteristics of the ADN-based liquid propellant in a volume combustor with an electric ignition method were studied. The influencing mechanisms of the ignition voltage and the electrode structure on the electric ignition characteristics of the ADN-based liquid propellant were investigated. An elevation of the ignition voltage could facilitate the ignition process of the ADN-based liquid propellant, curtail electric energy input and heating effect, while exerting an adverse impact on the combustion process of the *** increase in the ignition voltage enhanced the ignition process of the propellant while simultaneously suppressing its combustion process when utilizing mesh electrodes. Compared to the strip electrodes, the mesh electrodes increased the contact area between the electrodes and the propellant,increased the electric energy input power in the electric ignition process, and reduced the ignition delay time. The mesh electrodes could promote the combustion process of the propellant to a certain extent.

关键词： ADN-based liquid propellant Resistive ignition Electrical ignition characteristic Combustion Inert gas

Automatic modulation recognition of radiation source signals based on two-dimensional data matrix and improved residual neural network

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Defence Technology（防务技术） 2024年第3期33卷 364-373页

作者： Guanghua Yi Xinhong Hao Xiaopeng Yan Jian Dai Yangtian Liu Yanwen Han Science and Technology on Electromechanical Dynamic control Laboratory School of Mechatronical EngineeringBeijing Institute of TechnologyBeijing 100081China BIT Tangshan research institute Beijing 100081China

Automatic modulation recognition(AMR)of radiation source signals is a research focus in the field of cognitive ***,the AMR of radiation source signals at low SNRs still faces a great ***,the AMR method of radiation source signals based on two-dimensional data matrix and improved residual neural network is proposed in this ***,the time series of the radiation source signals are reconstructed into two-dimensional data matrix,which greatly simplifies the signal preprocessing ***,the depthwise convolution and large-size convolutional kernels based residual neural network(DLRNet)is proposed to improve the feature extraction capability of the AMR ***,the model performs feature extraction and classification on the two-dimensional data matrix to obtain the recognition vector that represents the signal modulation *** analysis and simulation results show that the AMR method based on two-dimensional data matrix and improved residual network can significantly improve the accuracy of the AMR *** recognition accuracy of the proposed method maintains a high level greater than 90% even at -14 dB SNR.

关键词： Automatic modulation recognition Radiation source signals Two-dimensional data matrix Residual neural network Depthwise convolution

A model reduction approach for discrete-time linear time-variant systems with delayed inputs

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Science China(Information Sciences) 2024年第4期67卷 197-217页

作者： Ai-Guo WU Guang-Ren DUAN Yu WANG Jie ZHANG School of Mechanical engineering and Automation Harbin Institute of Technology(Shenzhen) HIT Wuhu Robot Technology research institute Center for control Science and Technology Southern University of Science and Technology

A model reduction approach is presented for discrete-time linear time-variant input-delayed systems. According to this proposed approach, a dynamical variable is constructed by taking advantage of the current state and historical information of input. It is revealed that the behavior of this dynamical variable is governed by a discrete-time linear delay-free system. It is worth noting that the presented variable transformation does not require the system matrix to be invertible. Based on the reduced delay-free models,stabilizing control laws can be easily obtained for the original delayed system. For the case with a single input delay, the constructed variable is an exact prediction for the future state, and thus the stabilizing control law could be designed by replacing the future state with its prediction. Finally, three discrete-time periodic systems with delayed input are employed to illustrate how to utilize the presented model reduction approaches.

关键词： reduction approach predictor-based feedback time-varying systems delayed input periodic system

Analysis and Optimization of Transient Mode Switching Behavior for Power Split Hybrid Electric Vehicle with Clutch Collaboration

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Automotive Innovation 2024年第1期7卷 150-165页

作者： Dehua Shi Sheng Liu Yujie Shen Shaohua Wang Chaochun Yuan Long Chen Automotive engineering research institute Jiangsu UniversityZhenjiang 212013China Jiangsu Province engineering research Center of Electric Drive System and Intelligent control for Alternative Vehicles Zhenjiang 212013China

The power split hybrid electric vehicle(HEV)adopts a power coupling configuration featuring dual planetary gearsets and multiple clutches,enabling diverse operational modes through clutch engagement and *** multi-clutch configuration usually involves the collaboration of two clutches during the transient mode switching process,thereby substantially elevating control *** study focuses on power split HEVs that integrate multi-clutch mechanisms and investigates how different clutch collaboration manners impact the characteristics of transient mode *** powertrain model for the power-split HEV is established utilizing matrix-based *** the formulation of clutch torque curves and clutch collaboration models,this research systematically explores the effects of clutch engagement timing and the duration of clutch slipping state on transient mode switching *** upon this analysis,an optimization problem for control parameters pertaining to the two collaborative clutches is *** simulated annealing algorithm is employed to optimize these control *** results demonstrate that the clutch collaboration manners have a great influence on the transient mode switching *** with the pre-calibrated benchmark and the optimal solution derived by the genetic algorithm,the maximal longitudinal jerk and clutch slipping work during the transient mode switching process is reduced obviously with the optimal control parameters derived by the simulated annealing *** study provides valuable insights for the dynamic coordinated control of the power-split HEVs featuring complex clutch collaboration mechanisms.

关键词： Power split hybrid electric vehicle Transient mode switching Clutch collaboration Simulated annealing Powertrain model

Feature-aided pose estimation approach based on variational auto-encoder structure for spacecrafts

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Chinese Journal of Aeronautics 2024年第8期37卷 329-341页

作者： Yanfang LIU Rui ZHOU Desong DU Shuqing CAO Naiming QI Department of Aerospace engineering Harbin Institute of TechnologyHarbin 150001China Suzhou research institute of HIT Suzhou 215104China Shanghai institute of Spaceflight control Technology Shanghai 201109China Shanghai Key Laboratory of Aerospace Intelligent control Technology Shanghai 201109China

Real-time 6 Degree-of-Freedom(DoF)pose estimation is of paramount importance for various on-orbit *** from the development of deep learning,Convolutional Neural Networks(CNNs)in feature extraction has yielded impressive achievements for spacecraft pose *** improve the robustness and interpretability of CNNs,this paper proposes a Pose Estimation approach based on Variational Auto-Encoder structure(PE-VAE)and a Feature-Aided pose estimation approach based on Variational Auto-Encoder structure(FA-VAE),which aim to accurately estimate the 6 DoF pose of a target *** methods treat the pose vector as latent variables,employing an encoder-decoder network with a Variational Auto-Encoder(VAE)*** enhance the precision of pose estimation,PE-VAE uses the VAE structure to introduce reconstruction mechanism with the whole ***,FA-VAE enforces feature shape constraints by exclusively reconstructing the segment of the target spacecraft with the desired *** evaluation against leading methods on public datasets reveals similar accuracy with a threefold improvement in processing speed,showcasing the significant contribution of VAE structures to accuracy enhancement,and the additional benefit of incorporating global shape prior features.

关键词： Pose estimation Variational auto-encoder Feature-aided Pose Estimation Approach On-orbit measurement tasks Simulated and experimental dataset

Mixed H_(∞)/Passive Exponential Synchronization for Delayed Memristive Neural Networks with Switching Event-Triggered control

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Journal of Systems Science & Complexity 2024年第1期37卷 294-317页

作者： WU Wenhuang GUO Lulu CHEN Hong Shanghai research institute for Intelligent Autonomous Systems Tongji UniversityShanghai 200092China Department of control Science and engineering Tongji UniversityShanghai 201804China

This paper is devoted to event-triggered synchronization of delayed memristive neural networks with H∞and passivity *** aim is to guarantee the exponential synchronization and mixed H∞and passivity control for memristive neural networks by using event-triggered ***,a switching system is constructed under the event-triggered control ***,by adopting a piece-wise Lyapunov functional,a sufficient condition is established for the exponential synchronization and mixed H_(∞)and passivity ***,an event-triggered controller design scheme is proposed using matrix decoupling ***,the effectiveness of the designed controller is exemplified by a numerical example.

关键词： Event-triggered control exponential synchronization memristive neural networks time delays.

An adaptive 3D reconstruction method for asymmetric dual-angle multispectral stereo imaging system on UAV platform

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Science China(Information Sciences) 2024年第8期67卷 285-299页

作者： Chen WANG Xian LI Yanfeng GU Zixu WANG School of Electronics and Information engineering Harbin Institute of Technology Beijing institute of control and Electronic Technology

A multispectral imaging system often cannot capture 3D spatial information owing to hardware limitations, which diminishes the effectiveness across various domains. To address this problem, we have developed a multispectral stereo imaging system along with an adaptive 3D reconstruction algorithm. Unlike existing unmanned aerial vehicle stereo imaging systems, our multispectral stereo imaging system uses two multispectral cameras with asymmetric spectral bands positioned at different angles. This design enables the acquisition of a higher number of bands and lateral spatial information while maintaining a lightweight structure. This system introduces challenges such as large geometric distortions and intensity differences between multiple bands. To accurately recover 3D spatial information, we propose an adaptive 3D reconstruction method. This method employs a position and orientation system-assisted projection transformation and a normalized threshold adjustment strategy. Finally, mutual information is used to reconstruct the multispectral images densely, effectively addressing nonlinear differences and generating a comprehensive multispectral point cloud. Our stereo system was used for two real data collections in different regions, and the efficacy of the proposed 3D reconstruction method was validated by comparing it with existing methods and commercial software.

关键词： multispectral images 3D reconstruction stereo imaging system unmanned aerial vehicle feature extraction

Autonomous navigation method of satellite constellation based on adaptive forgetting factors

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Chinese Journal of Aeronautics 2024年第7期37卷 317-332页

作者： Dong WANG Jing YANG Kai XIONG School of Automation Science and Electrical engineering Beihang UniversityBeijing 100191China Science and Technology on Space Intelligent control Laboratory Beijing Institute of Control EngineeringBeijing 100094China

To address the problem that model uncertainty and unknown time-varying system noise hinder the filtering accuracy of the autonomous navigation system of satellite constellation,an autonomous navigation method of satellite constellation based on the Unscented Kalman Filter with Adaptive Forgetting Factors(UKF-AFF)is *** process noise covariance matrix is estimated online with the strategy that combines covariance matching and adaptive adjustment of forgetting *** adaptive adjustment coefficient based on squared Mahalanobis distance of state residual is employed to achieve online regulation of forgetting factors,equipping this method with more *** intersatellite direction vector obtained from photographic observations is introduced to determine the constellation satellite orbit together with the distance measurement to avoid rank deficiency *** that the number of available measurements varies online with intersatellite visibility in practical applications such as time-varying constellation configurations,the smooth covariance matrix of state correction determined by innovation and gain is adopted and constructed *** analysis of the proposed method is also *** effectiveness of the proposed method is verified by the Monte Carlo simulation and comparison *** estimation accuracy of constellation position and velocity of UKF-AFF is improved by 30%and 44%respectively compared to those of the extended Kalman filter,and the method proposed is also better than other several adaptive filtering methods in the presence of significant model uncertainty.

关键词： Constellation autonomous navigation Unscented Kalman filter Adaptive forgetting factor Model uncertainty Stability analysis

Synergistic effects of peroxydisulfate on UV/O3 process for tetracycline degradation:Mechanism and pathways

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Chinese Chemical Letters 2024年第10期35卷 434-439页

作者： Fengrui Yang Debing Wang Xinying Zhang Jie Zhang Zhichao Wu Qiaoying Wang State Key Laboratory of Pollution control and Resource Reuse Shanghai Institute of Pollution Control and Ecological Security School of Environmental Science and Engineering Tongji University Fujian Provincial engineering research Center of Rural Waste Recycling Technology College of Environment & Safety Engineering Fuzhou University

Tetracycline（TC） as a typical emerging pollutant is becoming a serious threat to the environment and human health. A combined advanced oxidation technology of UV/Ozone（O3）/peroxydisulfate（PDS） process was developed to explore an efficient and economic treatment process of TC in wastewater. Furthermore,the reactive sites and transformation pathways of TC were explored and the toxicity of the intermediates was quantified with a quantitative structure-activity relationship（QSAR） assessment. The degradation performance of TC was substantially enhanced in UV/O3/PDS process with a kobsof 0.0949 min-1,which was 2.3 times higher than UV/O3and 3.2 times than sole UV. The results demonstrated that there was a superior synergistic effect of PDS on UV/O3processes for the degradation of TC. Electron paramagnetic resonance（EPR） analysis and quenching experiments show that·OH, SO4·-, O2·-and1O2all contributed to TC degradation in the UV/O3/PDS process and exhibited a synergistic effect, which inhibited the generation of harmful products. In addition, the UV/O3/PDS system can effectively degrade TC in a wide range of substrate concentrations and pH, and also showed excellent adaptability to various concentrations of anions（Cl-and HCO3-）. This study proves the feasibility of UV/O3/PDS process for treating TC contaminated wastewater with complicated water matrix.

关键词： Degradation Synergistic effect Tetracycline UV/ozonation/peroxydisulfate Wastewater