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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

Could natural phytochemicals be used to reduce nitrogen excretion and excreta‑derived N_(2)O emissions from ruminants?

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Journal of Animal Science and Biotechnology 2024年第2期15卷 490-508页

作者： Yuchao zhao ming liu Linshu Jiang Leluo Guan Beijing Key Laboratory of Dairy Cow Nutrition College of Animal Science and TechnologyBeijing University of AgricultureBeijing 102206China College of Animal Science and Technology China Agricultural UniversityBeijing 100193China Department of Agricultural Food and Nutritional ScienceUniversity of AlbertaEdmontonAB T6G 2R3Canada

Ruminants play a critical role in our food system by converting plant biomass that humans cannot or choose not to consume into edible high-quality ***,ruminant excreta is a significant source of nitrous oxide(N_(2)O),a potent greenhouse gas with a long-term global warming potential 298 times that of carbon *** phytochemicals or forages containing phytochemicals have shown the potential to improve the efficiency of nitrogen(N)utilization and decrease N_(2)O emissions from the excreta of *** inclusion of tannins can shift more of the excreted N to the feces,alter the urinary N composition and consequently reduce N_(2)O emissions from *** oils or saponins could inhibit rumen ammonia production and decrease urinary N *** grazed pastures,large amounts of glucosinolates or aucubin can be introduced into pasture soils when animals consume plants rich in these compounds and then excrete them or their metabolites in the urine or *** inhibitory compounds are excreted in the urine,they would be directly applied to the urine patch to reduce nitrification and subsequent N_(2)O *** phytochemicals’role in sustainable ruminant production is undeniable,but much uncertainty ***,transient effects,and adverse effects limit the effectiveness of these phytochemicals for reducing N *** this review,we will identify some current phytochemicals found in feed that have the potential to manipulate ruminant N excretion or mitigate N_(2)O production and deliberate the challenges and opportunities associated with using phytochemicals or forages rich in phytochemicals as dietary strategies for reducing N excretion and excreta-derived N_(2)O emissions.

关键词： Nitrogen metabolism Nitrous oxide Plant bioactive compounds Ruminant Urine patches

Rational design of superior catalysts from topological semimetals with nontrivial energy window

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Rare Metals 2024年第5期43卷 1956-1964页

作者： Min zhao Li-Rong Wang Wei liu ming-Hang Li Ying liu Xue-Fang Dai Guo-Dong liu Xiao-ming Zhang Key Laboratory of Reliability and Intelligence of Electrical Equipment School of Materials Science and Engineering ManufacturingHebei University of TechnologyTianjin 300130China

Materials featuring topological energy bands and nontrivial surface states hold significant promise in unlocking unprecedented opportunities for innovating electrocatalytic ***,it remains a challenge to realize superior topological catalysts which can carry both high catalytic activity and excellent catalytic ***,we propose that a family of Ni-based binary materials hosting fantasying topological conjunct-nodalpoint state and a large nontrivial energy window(NEWD)represents an ideal choice for such superior topological catalysts in hydrogen evolution *** presence of conjunct-nodal-points ensures long Fermi arcs on the surface,thereby enabling an extremely high catalytic *** NEWD plays a crucial role in stabilizing the high catalytic activity against external perturbations,such as strain and electron/hole *** roles for conjunctnodal-points and NEWD are substantiated by the observable weakening of catalytic performance during topological phase transitions,which result in the removal of the conjunct-nodal-points,NEWD and their corresponding long Fermi *** work unveils a hidden mechanism and opens a feasible route for developing superior quantum catalysts from novel topology point of view.

关键词： First-principles modeling Topological semimetal Nontrivial surface states Hydrogen evolution reaction

Swelling of Spherical Polyelectrolyte Gels

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Chinese Journal of Polymer Science 2024年第9期42卷 1386-1392,I0009页

作者： ming-Yu Duan Jia-Dong Chen Yi-ming liu zhao-Feng Peng Guang Chen Department of Advanced Manufacturing and Robotics College of EngineeringPeking UniversityBeijing 100871China

Polyelectrolyte(PE)gels,distinguished by their unique stimuli-responsive swelling behavior,serve as the basis of broad applications,such as artificial muscles and drug *** this work,we present a theoretical model to analyze the electrostatics and its contribution to the swelling behavior of PE gels in salt *** minimizing the free energy of PE gels,we obtain two distinct scaling regimes for the swelling ratio at equilibrium with respect to the salt *** compare our predictions for the swelling ratio with experimental measurements,which show excellent *** addition,we employ a finite element method to assess the applicability range of our theoretical model and *** anticipate that our model will also provide valuable insights into drug adsorption and release,deformation of red blood cells,4D printing and soft robotics,where the underlying mechanism of swelling remains enigmatic.

关键词： Gels Polyelectrolytes Swelling Stimuli-responsive Electrostatic interaction Cell model

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Petroleum Science 2024年第4期21卷 2383-2392页

作者： Li-ming zhao Cai-Ping Lu Yang liu Chao-Chao Li School of Mines China University of Mining and Technology Henan Institute of Geophysical Space Information

The similarities and differences in inherent mechanism and characteristic frequency between the onedimensional(1D) poroelastic model and the layered White model were investigated. This investigation was conducted under the assumption that the rock was homogenous and isotropic at the mesoscopic scale. For the inherent mechanism, both models resulted from quasi-static flow in a slow P-wave diffusion mode, and the differences between them originated from saturated fluids and boundary conditions. On the other hand, for the characteristic frequencies of the models, the characteristic frequency of the 1D poroelastic model was first modified because the elastic constant and formula for calculating it were misused and then compared to that of the layered White model. Both of them moved towards higher frequencies with increasing permeability and decreasing viscosity and diffusion length. The differences between them were due to the diffusion length. The diffusion length for the 1D poroelastic model was determined by the sample length, whereas that for the layered White model was determined by the length of the representative elementary volume(REV). Subsequently, a numerical example was presented to demonstrate the similarities and differences between the models. Finally, published experimental data were interpreted using the 1D poroelastic model combined with the Cole-Cole *** prediction of the combined model was in good agreement with the experimental data, thereby validating the effectiveness of the 1D poroelastic model. Furthermore, the modified characteristic frequency in our study was much closer to the experimental data than the previous prediction, validating the effectiveness of our modification of the characteristic frequency of the 1D poroelastic model. The investigation provided insight into the internal relationship between wave-induced fluid flow(WIFF)models at macroscopic and mesoscopic scales and can aid in a better understanding of the elastic modulus d

关键词： 1D poroelastic model Layered White model Quasi-static flow Slow P-wave diffusion Characteristic frequency Diffusion length

Solar manipulations of perpendicular magnetic anisotropy for flexible spintronics

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Frontiers of physics 2024年第4期19卷 73-79页

作者： Zhexi He Yifan zhao Yujing Du Meng zhao Yuxuan Jiang ming liu Ziyao Zhou State Key Laboratory for Manufacturing Systems Engineering Electronic Materials Research LaboratoryKey Laboratory of the Ministry of Education&International Center for Dielectric ResearchSchool of Electronic Science and EngineeringThe International Joint Laboratory for Micro/Nano Manufacturing and Measurement TechnologyXi’an Jiaotong UniversityXi’an 710049China School of Materials Science&Engineering Changzhou UniversityChangzhou 213164China

Flexible electronics/spintronics attracts researchers’attention for their application potential abroad in wearable devices,healthcare,and other *** devices’performance(speed,energy consumption)is highly dependent on manipulating information bits(spin-orientation in flexible spintronics).In this work,we established an organic photovoltaic(OPV)/ZnO/Pt/Co/Pt heterostructure on flexible PET substrates with perpendicular magnetic anisotropy(PMA).Under sunlight illumination,the photoelectrons generated from the OPV layer transfer into the PMA heterostructure,then they reduce the PMA strength by enhancing the interfacial Rashba field *** coercive field(Hc)reduces from 800 Oe to 500 Oe at its maximum,and the magnetization can be switched up and down *** stability of sunlight control of magnetization reversal under various bending conditions is also tested for flexible spintronic ***,the voltage output of sunlight-driven PMA is achieved in our prototype device,exhibiting an excellent angular dependence and opening a door towards solar-driven flexible spintronics with much lower energy consumption.

关键词： interfacial magnetoelectric coupling perpendicular magnetic anisotropy deterministic magnetization reversal photovoltaic control of magnetism

（Salen）Ti（Ⅳ）-Catalyzed Asymmetric Ring-opening of meso Epoxides Using Dithiophosphorus Acid as the Nucleophile

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Chinese Chemical Letters 2006年第2期17卷 143-146页

作者： Zheng Hong ZHOU zhao ming LI Bing liu Kang Ying LI Li Xin WANG Guo Feng zhao Qi Lin ZHOU Chu Chi TANG State Key Laboratory of Elemento-Organic Chemistry Institute of Elemento-Organic Chemistry Nankai University Tianjin 300071

The asymmetric ring-opening of epoxides with dithiophosphorus acids catalyzed by a （salen）Ti（Ⅳ） complex formed in situ from the reaction of Ti（OPr-i）4 and the chiral Schiff base derived from （1R,2R）-（＋）-diaminocyclohexane was realized. The resulting products were obtained with low to good enantioselectivity （up to 73% ee）.

关键词： (Salen)Ti(Ⅳ) complex ring-opening dithiophosphorus acid enantioselectivity meso epoxide.

NUMERICAL SIMULATON OF IMPROVED BOUSSINESQ EQUATIONS BY A FINITE ELEMENT METHOD

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Journal of Hydrodynamics 2003年第4期15卷 31-40页

作者： zhao ming, Teng Bin, liu Shu-xue State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China Lab. of Coastal and Offshore Eng. Dalian Univ. of Technol. Dalian 116024 China

The improved Boussinesq equations for varying depth derived by Beji andNadaoka significantly improved the linear dispersive properties of wave models in intermediate waterdepths. In this study, a finite element method was developed to solve the improved Boussinesqequations. A spongy layer was applied at the open boundary of the computational domain to absorb thewave energy. The fourth-order predictor-corrector method was employed in the time *** test cases were illustrated. The numerical results of this model were compared withlaboratory data and those from other numerical models. It turns out that the present numerical modelis capable of giving satisactory prediction for wave propagation.

关键词： boussinesq equations finite element method numerical simulation

Twisted Integration of Complex Oxide Magnetoelectric Heterostructures via Water‑Etching and Transfer Process

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Nano-Micro Letters 2024年第1期16卷 360-369页

作者： Guannan Yang Guohua Dong Butong Zhang Xu Xu Yanan zhao Zhongqiang Hu ming liu State Key Laboratory for Manufacturing Systems Engineering Electronic Materials Research LaboratoryKey Laboratory of the Ministry of EducationEngineering Research Center of Spin Quantum Sensor ChipsUniversities of Shaanxi ProvinceSchool of Electronic Science and EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China

Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain *** recent years,lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal ***,twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures.A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process,which could provide some insight in to the physical *** this work,the La_(0.67)Sr_(0.33)MnO_(3)(001)/0.7Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.3PbTiO_(3)(011)(LSMO/PMN-PT)heterostructures with *** *** angles were assembled via water-etching and transfer *** transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO.A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO[110]easy axis is observed for the 45°Sample by applying a 7.2 kV cm^(−1)electrical field,significantly different from a uniaxial anisotropy with LSMO[100]easy axis for the 0°*** fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45°twist angle causes different lattice distortion of LSMO,thereby enhancing both the fourfold and uniaxial *** work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.

关键词： Magnetoelectric heterostructures Twist angle Epitaxial lift-off Magnetic anisotropy Ferromagnetic resonance