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Satellite anomaly detection based on reconstruction discrepancy theory utilizing a new dual-branch reconstruction model

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Science China Technological Sciences 2024年第10期67卷 3294-3307页

作者： ZHAO HaoTian QIU Shi LIU Ming cao xibin Research Center of Satellite Technology School of AstronauticsHarbin Institute of Technology

To enhance the accuracy of deep learning methods based on reconstruction discrepancy in satellite anomaly detection tasks, this study proposes a dual-branch reconstruction model(DbRM) and designs a comprehensive satellite anomaly detection framework around this model. Firstly, we introduce the temporal-channel mixer(TC-Mixer) module, which mainly comprises a self-attention layer for capturing long-range temporal dependencies in telemetry data, and two types of feed-forward networks(FFN) for extracting complex patterns in the temporal and channel dimension of telemetry data. This design endows the TC-Mixer module with robust capabilities for extracting complicated dependencies in telemetry data. Secondly, with the TC-Mixer module as the main component, we designed the DbRM. This model utilizes a shared latent representation layer, allowing the regeneration branch and forecasting branch of the DbRM to share most of the feature extraction network architecture. This approach significantly enhances the model's regression accuracy while reducing computational complexity. Thirdly, using the DbRM as the core network model, we devised a comprehensive satellite anomaly detection framework. This includes an anomaly criterion that considers the reconstruction discrepancy of both the regeneration and forecasting branches, the peak-over-threshold(POT) method for anomaly thresholding, and the MIC-based feature engineering method, etc. Finally, we conducted comparative experiments with several SOTA anomaly detection algorithms on two public and one private satellite anomaly detection datasets. The experimental results validate the effectiveness and superiority of our proposed method.

关键词： anomaly detection reconstruction discrepancy dual-branch reconstruction model (DbRM) satellite telemetry data time series

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Fluid-solid coupling numerical simulation of micro-disturbance grouting treatment for excessive deformation of shield tunnel

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Underground Space 2024年第6期19卷 87-100页

作者： Yanjie Zhang Zheng cao Chun Liu Hongwei Huang College of Civil Engineering and Architecture Henan University of TechnologyZhengzhou 450001China School of Earth Sciences and Engineering Nanjing UniversityNanjing 210023China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

Micro-disturbance grouting is a recovery technique to reduce the excessive deformation of operational shield tunnels in urban *** grout mass behaves as a fluid in the ground before hardening to form a grout–soil mixture,which highlights the necessity of using fluid–solid coupling method in the simulation of grouting *** a discrete element modeling environment,this paper proposes a novel fluid-solid coupling method based on the pore density flow *** demonstrate the effectiveness of this method,it is applied to numerical simulation of micro-disturbance grouting process for treatment of large transverse deformation of a shield tunnel in Shanghai Metro,*** simulation results reveal the mechanism of recovering tunnel convergence by micro-disturbance grouting in terms of compaction and fracture of soil,energy analysis during grouting,and mechanical response of soil-tunnel interaction ***,the influence of the three main grouting parameters(i.e.,grouting pressure,grouting distance,and grouting height)on tunnel deformation recovery efficiency is evaluated through parametric *** order to efficiently recover large transverse deformation of shield tunnel in Shanghai Metro,it is suggested that the grouting pressure should be about 0.55 MPa,the grouting height should be in the range of 6.2–7.0 m,and the grouting distance should be in the range of 3.0–3.6 *** results provide a valuable reference for grouting treatment projects of over-deformed shield tunnel in soft soil areas.

关键词： Fluid-solid coupling Discrete element method Pore density flow Micro-disturbance grouting Soil-tunnel interaction

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Distributed generalized Nash equilibrium seeking:event-triggered coding-decoding-based secure communication

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Science China(Information Sciences) 2024年第7期67卷 271-284页

作者： Shaofu YANG Wenying xU Wangli HE Jinde cao School of Computer Science and Engineering Southeast University School of Mathematics Southeast University Key Laboratory of Advanced Control and Optimization for Chemical Processes East China University of Science and Technology

In this paper, we consider the distributed generalized Nash equilibrium(GNE) seeking problem in strongly monotone games. The transmission among players is implemented through a digital communication network with limited bandwidth. For improving communication efficiency or/and security, an event-triggered coding-decoding-based communication is first proposed, where the data(decision variable) are first mapped to a series of finite-level codewords and, only when an event condition is satisfied, then sent to the neighboring agents. Moreover, a distributed communication-efficient GNE seeking algorithm is constructed accordingly,and the overrelaxation scheme is further taken into consideration. Through primal-dual analysis, the proposed algorithm is proven to converge to a variational GNE with fixed step-sizes by recasting it as an inexact forward-backward iteration. Finally, numerical simulations illustrate the benefit of the proposed algorithms in terms of saving communication resources.

关键词： noncooperative games event-triggered communication coding-decoding quantization

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Research on an innovative structure of an open-ribbed steel-ultra-high performance concrete composite bridge deck

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Frontiers of Structural and Civil Engineering 2024年第5期18卷 716-730页

作者： xudong SHAO xuan SUN Deqiang ZOU Junhui cao Chuanqi YANG School of Civil Engineering Hunan UniversityKey Laboratory for Wind and Bridge Engineering of Hunan ProvinceChangsha 410082China China Construction Fifth Engineering Division Co. Ltd.Changsha 410004China

To completely solve the problem of fatigue cracking issue of orthotropic steel bridge decks(OSDs),the authors proposed a steel–ultra-high performance concrete(UHPC)lightweight composite deck(LWCD)with closed ribs in *** on the successful application of that LWCD,an adaptation incorporating an innovative composite deck structure,i.e.,the hot-rolled section steel–UHPC composite deck with open ribs(SSD)is proposed in this paper,aiming to simplify the fabrication process as well as to reduce the cost of *** on a long-span cable-stayed bridge,a design scheme is proposed and is compared with the conventional OSD ***,a finite element(FE)calculation is conducted to reflect both the global and local behavior of the SSD scheme,and it is found that the peaked stresses in the SSD components are less than the corresponding allowable values.A static test is performed for an SSD strip specimen to understand the anti-cracking behavior of the UHPC layer under negative bending *** static test results indicate that the UHPC layer exhibited a satisfactory tensile toughness,the UHPC tensile strength obtained from the test is 1.8 times the calculated stress by the FE model of the real *** addition,the fatigue stresses of typical fatigue-prone details in the SSD are calculated and evaluated,and the influences of key design parameters on the fatigue performance of the SSD are *** to the fatigue results,the peaked stress ranges for all of the 10 fatigue-prone details are within the corresponding constant amplitude fatigue *** a fatigue test is carried out for another SSD strip specimen to explore the fatigue behavior of the fillet weld between the longitudinal and transverse *** specimen failed at the fillet weld after equivalent 47.5 million cycles of loading under the design fatigue stress range,indicating that the fatigue performance of the SSD could meet the fatigue design *** calculations and experim

关键词： steel-ultra-high performance concrete composite deck open rib strip model test static and fatigue performance orthotropic steel deck

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A FINITE DIFFERENCE METHOD FOR TWO DIMENSIONAL ELLIPTIC INTERFACE PRObLEMS WITH IMPERFECT CONTACT

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Journal of Computational Mathematics 2024年第5期42卷 1328-1355页

作者： Fujun cao Dongfang Yuan Dongxu Jia Guangwei Yuan School of Science Inner Mongolia University of Science and TechnologyBaotou 014010Inner MongoliaChina School of Science Tianjin University of TechnologyTianjin 300384China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsP.O.Box 8009Beijing 100088China

In this paper two dimensional elliptic interface problem with imperfect contact is considered,which is featured by the implicit jump condition imposed on the imperfect contact interface,and the jumping quantity of the unknown is related to the flux across the interface.A finite difference method is constructed for the 2D elliptic interface problems with straight and curve interface ***,the stability and convergence analysis are given for the constructed ***,in particular case,it is proved to be *** examples for elliptic interface problems with straight and curve interface shapes are tested to verify the performance of the *** numerical results demonstrate that it obtains approximately second-order accuracy for elliptic interface equations with implicit jump condition.

关键词： Finite difference method Elliptic interface problem Imperfect contact

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Analytic Formulae for Estimating Motor Proportion of Load Model Under Small Disturbance

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1599-1607页

作者： Ping Ju Shiqiu xia Yuqing Jin Lu cao School of Electrical and Power Engineering Hohai UniversityNanjing 211100China the East China branch of the State Grid Corporation of China Shanghai 200120China

In the composite load model(CLM),which is commonly used in China,an equivalent motor and equivalent static load are used to represent all electrical equipment and networks connected to a load *** research has determined typical values of electrical and mechanical parameters for load models of different load types,which improves the basis for load ***,the motor proportion parameter is not the same for different load buses or at different times;therefore,obtaining the actual motor proportion is key to establishing an accurate load *** the existing load modeling method,motor proportion is commonly identified along with other parameters under rare large disturbances;therefore,the value of the motor proportion is fixed by the time when a large disturbance *** this paper,formulae are derived to estimate motor proportion under small disturbances,and these formulae allow direct calculation of motor proportion without using any optimization *** proposed estimation formulae do not rely on any parameters of load model or power system but instead rely only on measurement of the voltage and active power at steady-state points before and after a small *** of universality of small disturbances in power systems,estimating time-varying motor proportion under small disturbances will be helpful for solving the time-varying problem of load ***,the proposed motor proportion estimation formulae are validated by simulations,physical experiments,and field experiments.

关键词： Composite load model load modeling motor proportion parameter estimation

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Hydrogen bond-bridged phosphorene flexible film for photodynamic inhibiting Staphylococcus aureus

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Nano Research 2024年第6期17卷 5461-5468页

作者： Ziyu Wei Wenting Li Zhifang Liu Yongfa Zhu Huaqiang cao Department of Chemistry Engineering Research Center of Advanced Rare Earth MaterialsTsinghua UniversityBeijing 100084China

Antibiotics are a widely used and effective treatment for bacterial ***,bacteria can gradually evolve during infection,leading to developing resistance to antibiotics,which renders previously effective treatments *** a useful and convenient manner to treat bacterial infections is a great ***,we report a flexible hydrogen-bond-bridged phosphorene film with photodynamic antibacterial properties and excellent mechanical properties,fabricated from electrochemical exfoliation of black phosphorus(bP).When illuminated under 700 nm light,the hydrogen bond-bridged phosphorene flexible film is capable of converting ground-state triplet oxygen(O_(2))into excited-state singlet oxygen(^(1)O_(2)),destroying the structure of the membrane of Staphylococcus aureus,and eventually leading to bacterial death,via breaking the C=C of unsaturated fatty acids within the bacterial cell membrane after the reaction between^(1)O_(2)and unsaturated fatty acids,thus realizing a highly efficient antibacterial approach,which is supported by gas chromatography-mass spectrometry(GC-MS)*** work establishes an effective phototherapy platform for treating bacterial traumatic infections.

关键词： hydrogen bond-bridged phosphorene flexible film photodynamic Staphylococcus aureus

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Preparation and performance improvement of a dual-component microcapsule self-healing system for silicone rubber insulating material

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High Voltage 2024年第2期9卷 453-465页

作者： Mingzhe Li bin cao Fanghui Yin Hongwei Mei Liming Wang Engineering Laboratory of Power Equipment Reliability in Complicated Coastal Environments Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhenChina

A key factor limiting the development of silicone rubber insulating materials is their short service life in harsh operating *** establishment of a self-healing system is desired to improve the long-term operational performance of silicone rubber and effectively extend its service *** this study,poly(urea-formaldehyde)microcapsules containing polydimethylsiloxane healing agents are prepared and a dual-component microcapsule self-healing system for silicone rubber material is established and *** addition,the key factors affecting the self-healing performance(such as microcapsule size,rupture rate,and microcapsule doping amount)are *** is found that when SYLGARDTM 184 is used as the healing agent and matrix,with a 4:6(A:b)doping ratio of dual-component microcapsules and 20 phr doping amount,the self-healing efficiency is approximately 51%.Furthermore,increasing the microcapsule rupture rate and the interface strength between the healing agent and the matrix can effectively improve the self-healing *** relationships between key factors and self-healing performance are theoretically *** on the relationships,the microcapsule self-healing system can be appropriately *** results of this paper can provide a reference for the development of long-life silicone rubber insulating materials.

关键词： service rubber performance

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Numerical investigation of dynamic characteristics of dual throat nozzle and bypass dual throat nozzle in thrust vectoring starting process

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Chinese Journal of Aeronautics 2024年第10期37卷 184-206页

作者： Yuqi ZHANG Jinglei xU Minglei cao Ruifeng PAN Shuai HUANG Key Laboratory of Inlet and Exhaust System Technology of Ministry of Education Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory of Mechanics and Control of Aeronautics and Astronautics Structures Nanjing 210016China

The bypass Dual Throat Nozzle(bDTN)is a novel fluidic Thrust Vectoring(TV)nozzle,it switches to TV state by opening the valve in the *** greatly manipulate the bDTN,the dynamic characteristics in the TV starting process should be *** paper conducts numerical simulations to grasp the variation processes of performances and the flow field evolution of bDTN and Dual Throat Nozzle(DTN).The dynamic responses of TV starting in typical DTN models are investigated at ***,the TV starting processes of bDTN in different Nozzle Pressure Ratio(NPR)conditions are simulated,and the valve opening durations(T)are also *** the expected TV direction is achieved in the DTN,the jet is deflected to the opposite direction at the beginning of the dynamic process,which is called the reverse TV ***,this phenomenon disappears in the *** larger injection width of DTN intensifies unsteady oscillations,and the reverse TV phenomenon is *** the bDTN,T determines the delay degree of performance variations compared to the static results,which is called hysteresis *** NPR=10,the hysteresis affects the final stable performance of *** study analyses the dynamic characteristics in DTN and bDTN,laying a foundation for further design of nozzles and control strategies.

关键词： Dual Throat Nozzle(DTN) bypass Dual Throat Nozzle(bDTN) Dynamic characteristic Thrust vectoring starting process Cavity vortex Hysteresis effect

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Variations of shear-wave splitting parameters in the source region of the 2023 Türkiye doublet earthquakes

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Earthquake Science 2024年第2期37卷 174-187页

作者： xuelai cao Lijun Chang Institute of Geophysics China Earthquake AdministrationBeijing 100081China

In this study,the shear-wave splitting parameters of local seismic events from the source regions of the 2023 Türkiye MW7.7 and MW7.6 doublet earthquakes(event 1 and event 2,respectively)were measured from June 1,2022,to April 25,2023,and their spatiotemporal characteristics were *** results revealed clear spatial and temporal ***,the dominant fast-wave polarization direction at each station shows a strong correlation with the direction of the maximum horizontal principal compressive stress,as characterized by focal mechanism solutions of seismic events(MW≥3.5)near the *** dominant fast-wave polarization direction and the regional stress field also showed a strong correlation with the intermovement of the Arabian Plate,African Plate,and Anatolian *** the Nurdagi-Pazarcik fault zone,the seismic fault of event 1,stations closer to the middle of the fault where the mainshock occurred exhibited notably greater delay times than stations located towards the ends of the fault and far from the *** addition,the stations located to the east of the Nurdagi-Pazarcik fault and to the north of the Sürgüfault also exhibited large delay *** spatial distribution of shear-wave splitting parameters obtained from each station indicates that the upper-crust anisotropy in the source area is mainly controlled by the regional stress field,which is closely related to the state of the block *** the seismogenic process of the MW7.7 earthquake,more stress accumulated in the middle of the Nurdagi-Pazarcik fault than at either end of the *** the influence of the MW7.7 and MW7.6 events,the stress that accumulated during the seismogenic process of the earthquake doublet may have migrated towards some areas outside the aftershock intensive area after the earthquakes,and the crustal stress and its adjustment range near the outer stations increased *** the exception of two stations with few effective events,all

关键词： Türkiye doublet earthquakes shear-wave splitting upper crustal anisotropy stress field

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