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Containment-Based Multiple PCC Voltage regulation Strategy for Communication Link and Sensor Faults

IEEE/CAA Journal of Automatica Sinica 2023年第11期10卷 2045-2055页

作者： Meina Zhai Qiuye Sun rui Wang Huaguang Zhang College of Information Science and Engineering Northeastern UniversityShenyang 110819China IEEE

The distributed AC microgrid(MG) voltage restoration problem has been extensively studied. Still, many existing secondary voltage control strategies neglect the co-regulation of the voltage at the point of common coupling(PCC) in the AC multi-MG system(MMS). When an MMS consists of sub-MGs connected in series, power flow between the sub-MGs is not possible if the PCC voltage regulation relies on traditional consensus control objectives. In addition, communication faults and sensor faults are inevitable in the MMS. Therefore, a resilient voltage regulation strategy based on containment control is ***, the feedback linearization technique allows us to deal with the nonlinear distributed generation(dG) dynamics, where the PCC regulation problem of an AC MG is transformed into an output feedback tracking problem for a linear multi-agent system(MAS) containing nonlinear dynamics. This process is an indispensable pre-processing in control algorithm design. Moreover, considering the unavailability of full-state measurements and the potential faults present in the sensors, a novel follower observer is designed to handle communication faults. Based on this, a controller based on containment control is designed to achieve voltage regulation. In regulating multiple PCC voltages to a reasonable upper and lower limit, a voltage difference exists between sub-MGs to achieve power flow. In addition, the secondary control algorithm avoids using global information of directed communication network and fault boundaries for communication link and sensor faults. Finally, the simulation results verify the performance of the proposed strategy.

关键词： Communication link faults directed graph fully distributed control voltage regulation control

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Impacts of short-term rainfall and snowfall exclusions on hydraulic,economic and stomatal traits of Larix gmelinii in northeastern china

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Journal of Forestry research 2025年第1期36卷 245-257页

作者： Yaxin Zhang Xiaochun Wang rui Zhang Aolin Niu Chuankuan Wang Ying Jin School of Ecology Northeast Forestry UniversityHarbin150040People’s Republic of China Key Laboratory of Sustainable Forest Ecosystem Management Ministry of EducationNortheast Forestry UniversityHarbin150040People’s Republic of China

Ongoing climate change has a considerable influence on the seasonality,timing,and intensity of rainfall worldwide,and is also predicted to decrease snow cover in cold *** is a widely distributed tree species in boreal Eurasia,calling for a comprehensive understanding of how larch adapts to changes in both rainfall and snowfall by adjusting carbon-water ***,we conducted a short-term rainfall(−60% ambient rainfall;three-year)and snowfall(−73% ambient snowfall;two-year)exclusions experiment in Larix gmelinii forest in northeastern china,and aimed to explore the responses of hydraulic(leaf pressure-volume traits,leaf and branch hydraulic conductivity and embolism resistance),stomatal(stomatal closure point and stomatal safety margin),and economic(photosynthetic rate,nutrient and non-structural carbohydrates contents)traits to rainfall and snowfall *** the weak alternation of leaf and branch hydraulic traits,both rainfall and snowfall reductions significantly led to early stomatal closure and increased stomatal safety margins(the difference between stomatal closure point and xylem embolism threshold,describing drought resistance by merging both hydraulic and stomatal strategies).reductions in rainfall and snowfall induced water or/and low-temperature stress,resulting in more conservative leaf economic traits,including a reduced photosynthetic rate,lower leaf nitrogen concentration,and higher leaf *** addition,larch responded to reductions in rainfall and snowfall by up-regulating non-structural carbohydrates in the xylem,which helps repair embolism or lower the freezing point acting as ***,our findings reveal that larch could adapt to the drought and snowpack reduction by strict stomatal regulation and investing non-structural carbohydrates in embolism repairing,at the cost of carbon assimilation.

关键词： Embolism resistance Stomatal closure point Stomatal safety margins Non-structural carbohydrates Larix gmelinii

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Self‐adaptive electrostatic discharge performance of ZnO microvaristors doped silicone rubber composites

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High Voltage 2023年第6期8卷 1180-1187页

作者： Ya Sun Zhikang Yuan Jun Hu Zhiwen Huang Xuan Liu Gang Sun Qi Li Jinliang He State Key Laboratory of Power Systems Department of Electrical EngineeringTsinghua UniversityBeijingChina

With the increase in applied voltage and the decrease in volume,integrated electronic modules have become electrostatic *** microvaristors doped silicone rubber(Sir)composite,with electric field‐dependent conductivity,shows promising prospects for solving the electrostatic *** this study,20 vol%to 50 vol%ZnO/Sir composite films,filled with 10–30μm ZnO microvaristors,were prepared and put into the test of electrostatic *** with the insulating and conducting materials,ZnO/Sir composites achieve the lowest initial voltage and a short time constant of electrostatic *** the increase of ZnO microvaristors volume fraction,from 20%to 50%,the initial voltage and the time constant of electrostatic discharge drop from 1.78 to 0.72 kV and 3.1 ms to 0.4μ*** the ZnO volume fraction is higher than 30%,there is no residual voltage after 0.1 *** explore the reason behind different electrostatic discharge performances of the ZnO/Sir composites,the conductivities of the com-posites were *** is found that the break‐over voltage of the composite drops with the increase in the ZnO microvaristors volume *** a high voltage im-pulse is applied on the ZnO/Sir film,the composite will turn to the conducting state and release the electrostatic charge adaptively so that the initial voltage can be *** work supplies a novel electrostatic discharge idea for electric and electronic devices.

关键词： composites composite rubber

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Unknown Application Layer Protocol recognition Method Based on deep Clustering

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china Communications 2024年第12期21卷 275-296页

作者： Wu Jisheng Hong Zheng Ma Tiantian Si Jianpeng Institute of Command and Control Engineering Army Engineering University of PLANanjing 210007China

In recent years,many unknown protocols are constantly emerging,and they bring severe challenges to network security and network *** unknown protocol recognition methods suffer from weak feature extraction ability,and they cannot mine the discriminating features of the protocol data *** address the issue,we propose an unknown application layer protocol recognition method based on deep *** clustering which consists of the deep neural network and the clustering algorithm can automatically extract the features of the input and cluster the data based on the extracted *** with the traditional clustering methods,deep clustering boasts of higher clustering *** proposed method utilizes network-in-network(NIN),channel attention,spatial attention and Bidirectional Long Short-term memory(BLSTM)to construct an autoencoder to extract the spatial-temporal features of the protocol data,and utilizes the unsupervised clustering algorithm to recognize the unknown protocols based on the *** method firstly extracts the application layer protocol data from the network traffic and transforms the data into one-dimensional ***,the autoencoder is pretrained,and the protocol data is compressed into low dimensional latent space by the autoencoder and the initial clustering is performed with ***,the clustering loss is calculated and the classification model is optimized according to the clustering *** classification results can be obtained when the classification model is *** with the existing unknown protocol recognition methods,the proposed method utilizes deep clustering to cluster the unknown protocols,and it can mine the key features of the protocol data and recognize the unknown protocols *** results show that the proposed method can effectively recognize the unknown protocols,and its performance is better than other methods.

关键词： attention mechanism clustering loss deep clustering network traffic unknown protocol recognition

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MusicFace: Music-driven expressive singing face synthesis

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Computational Visual Media 2024年第1期10卷 119-136页

作者： Pengfei Liu Wenjin deng Hengda Li Jintai Wang Yinglin Zheng Yiwei ding Xiaohu Guo Ming Zeng School of Informatics Xiamen UniversityXiamen361000China Department of Computer Science The University of Texas at DallasRichardsonTexas75080-3021USA

It remains an interesting and challenging problem to synthesize a vivid and realistic singing face driven by music. In this paper, we present a method for this task with natural motions for the lips, facial expression, head pose, and eyes. due to the coupling of mixed information for the human voice and backing music in common music audio signals, we design a decouple-and-fuse strategy to tackle the challenge. We first decompose the input music audio into a human voice stream and a backing music stream. due to the implicit and complicated correlation between the two-stream input signals and the dynamics of the facial expressions, head motions, and eye states, we model their relationship with an attention scheme, where the effects of the two streams are fused seamlessly. Furthermore, to improve the expressivenes of the generated results, we decompose head movement generation in terms of speed and direction, and decompose eye state generation into short-term blinking and long-term eye closing, modeling them separately. We have also built a novel dataset, SingingFace, to support training and evaluation of models for this task, including future work on this topic. Extensive experiments and a user study show that our proposed method is capable of synthesizing vivid singing faces, qualitatively and quantitatively better than the prior state-of-the-art.

关键词： face synthesis singing music generative adversarial network

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Calculating the number of radial cracks around a wellbore fractured by liquid CO_(2) phase transition blasting technology

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Journal of rock Mechanics and Geotechnical Engineering 2024年第11期16卷 4515-4531页

作者： Kun Jiang Shouchun deng Yixuan Li Haibo Li State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

Integrating liquid CO_(2)phase transition blasting(LCPTB)technology with hydraulic fracturing(HF)methods can help reduce wellbore damage,create multiple radial fractures,and establish a complex fracture *** approach significantly increases the recovery efficiency of low-permeability oil and gas *** calculating the number of fractures caused by LCPTB is necessary to predict production enhancement effects and optimize subsequent HF ***,few studies are reported on large-scale physical model experiments in terms of a method for calculating the fracture *** study analyzed the initiation and propagation of cracks under LCPTB,derived a calculation formula for crack propagation radius under stress waves,and then proposed a new,fast,and accurate method for calculating the fracture number using the principle of mass *** ten rock-breaking tests using LCPTB,the study confirmed the effectiveness of the proposed calculation approach and elucidated the variation rule of explosion pressure,rock-breaking scenario,and the impact of varying parameters on fracture *** results show that the new calculation method is suitable for fracturing technologies with high pressure *** include enlarging the diameter of the fracturing tube and increasing the liquid CO_(2) mass in the tube to enhance fracture ***,the method can be applied to other fracturing technologies,such as explosive fracturing(EF)within HF formations,indicating its broader applicability and potential impact on optimizing unconventional resource extraction technologies.

关键词： Liquid CO_(2)phase transition blasting(LCPTB) rock fracturing Fracture number Physical model experiment

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Perturbed low-thrust geostationary orbit transfer guidance via polynomial costate estimation

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Chinese Journal of Aeronautics 2024年第3期37卷 181-193页

作者： Zhao LI Hengnian LI Fanghua JIANG Junfeng LI State Key Laboratory of Astronautic Dynamics Xi’an Satellite Control CenterXi’an 710043China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

This paper proposes an optimal,robust,and efficient guidance scheme for the perturbed minimum-time low-thrust transfer toward the geostationary *** Earth’s oblateness perturbation and shadow are taken into *** is difficult for a Lyapunov-based or trajectory-tracking guidance method to possess multiple characteristics at the same time,including high guidance optimality,robustness,and onboard computational *** this work,a concise relationship between the minimum-time transfer problem with orbital averaging and its optimal solution is identified,which reveals that the five averaged initial costates that dominate the optimal thrust direction can be approximately determined by only four initial modified equinoctial orbit elements after a coordinate *** on this relationship,the optimal averaged trajectories constituting the training dataset are randomly generated around a nominal averaged *** polynomial regression models are trained on the training dataset and are regarded as the costate *** the transfer,the spacecraft can obtain the real-time approximate optimal thrust direction by combining the costate estimations provided by the estimators with the current state at any ***,all these computations onboard are *** simulation results show that the proposed guidance scheme possesses extremely high guidance optimality,robustness,and onboard computational efficiency.

关键词： Low thrust Orbital transfer Trajectory optimization Guidance Indirect method Orbital averaging Machine learning Geostationary satellites

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Uncovering the germanium sustainability up to 2050 in china

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Frontiers of Environmental Science & Engineering 2025年第2期19卷 169-180页

作者： Meiion Wong Jinhui Li Xianlai Zeng State Key Laboratory of Iron and Steel Industry Environmental Protection School of EnvironmentTsinghua UniversityBeijing 100084China

Germanium,a critical yet often overlooked metal,has experienced significant shifts in its global market,largely driven by china’s dominant ***,concerns are growing over the sustainability of germanium supply in china due to imbalances in mining,manufacturing,recycling,and rising *** this study,we employ substance flow analysis to provide a quantitative assessment of china’s germanium flow system in 2019,and we project future demand and anthropogenic mineral generation up to 2050 using stock-driven *** results indicate that by 2050,domestic demand for germanium will increase to 164–187 t—double the demand in 2019—with infrared optics and solar cells being the primary drivers.A supply shortage is anticipated before 2040,although recycling through urban mining could meet around 30%of the *** findings underscore the urgent need to address emerging supply challenges and offer critical insights for policymakers and stakeholders to inform strategic decision-making.

关键词： Critical metal Germanium Substance flow analysis recycling Sustainability

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Chaotic characteristics of a quadruple-well triple Sd oscillator with multiple homoclinic orbits

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NONLINEAr dYNAMICS 2025年第11期113卷 13807-13835页

作者： Li, Jing Sun, ran Zhu, Shaotao Beijing Univ Technol Interdisciplinary Res Inst Sch Math Stat & Mech Beijing Peoples R China Beijing Univ Technol Coll Comp Sci Beijing Peoples R China

Nonlinear oscillators with multiple potential wells are widely used in practical structures such as vibration absorbers and energy harvesters due to their lower energy thresholds. The study of the chaotic characteristics of various homoclinic oscillators is of great significance for further understanding multi-stable systems, since homoclinic orbits characterize the boundary between different types of motion. The proper design of triple smooth-discontinuous (Sd) oscillators can achieve four-well characteristics, and the elastic restoring force of the system can be approximated as a piecewise linear function. Unlike bistable and tri-stable oscillators, this oscillator exhibits multiple types of homoclinic orbits, and analytical expressions for these types of orbits are derived by analyzing the geometric structure of phase space. By utilizing the energy relationships of the Hamiltonian system and extending the Melnikov method, the threshold curves of these three types of homoclinic orbits are derived. Finally, the relationship between these threshold curves and the chaotic characteristics of the system is investigated through numerical simulations.

关键词： Quadruple-well Multiple homoclinic orbits Chaotic phenomena Melnikov function

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Thermal decomposition mechanism and kinetics of bastnaesite in suspension roasting process:A comparative study in N_(2) and air atmospheres

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Journal of rare Earths 2024年第9期42卷 1809-1816,I0006页

作者： Wenbo Li Jijia Chen Shaokai Cheng Junyan Sun Xiaolong Zhang School of Resources and Civil Engineering Northeastern UniversityShenyang110819China National-Local Joint Engineering Research Center of High-Efficient Exploitation Technology for Refractory Iron Ore Resources Shenyang110819China

To investigate the thermal decomposition behavior and reaction kinetics of bastnaesite in suspension roasting,the gas and solid products of bastnaesite roasted in N2 and air atmospheres were examined using a gas analyzer,X-ray diffraction(Xrd),scanning electron microscopy(SEM),and energy dispersive spectrometry(EdS).Subsequently,the kinetic parameters of bastnaesite in the suspension roasting process were derived and calculated using the isothermal *** results show that the decomposition product of bastnaesite in N_(2) is ***,once the roasting temperature exceeds 600℃,CO is generated in addition to CO_(2),and all the Xrd diffraction peaks of CeOF are shifted to the right,indicating that CO_(2) can oxidize CeOF and lead to the transformation of Ce(Ⅲ) into Ce(Ⅳ).When roasted in air,the decomposition product CeOF can be completely converted to CeF3 and Ce_(7)O_(12) as it easily ***,the reaction rate of bastnaesite in air is higher than that of N_(2),and the starting reaction temperature is lower than that of N_(2).A large number of irregular cracks and holes appear on the surface of solid-phase products following suspension roasting,which are due to the thermal decomposition of bastnaesite that produces CO_(2) as well as the reconstruction of the lattice of the solid-phase *** reaction kinetic model of bastnaesite roasted in N_(2)(temperature range 600-750℃) and air(temperatu re range 500-575℃) confo rms to the A_(3/2) model with the mechanism function G(α)=-ln(1-α)^(2/3),and the reaction activation energy is 59.78 kj/mol and lnA is 1.65 s^(-1) in N_(2) *** air,the reaction activation energy is 100.30 kj/mol and lnA is 9.63 s^(-1).

关键词： rare earths Bastnaesite Suspension roasting Thermal decomposition mechanism reaction kinetics

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