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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

Visible Light-Induced[3+2]Annulation Reaction of Alkenes with Vinyl Azides:Direct Synthesis of Functionalized Pyrroles

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Chinese Journal of Chemistry 2024年第2期42卷 151-156页

作者： Ming Yang Xin-Yu wang Jie wang Yu-long Zhao Jilin Province Key Laboratory of Organic Functional Molecular Design&Synthesis Faculty of ChemistryNortheast Normal UniversityChangchunJilin 130024China

A photocatalytic[3+2]annulation of alkenes with vinyl azides was developed under irradiation by visible light in the presence of organic dye *** substrate scope and high functional group tolerance were demonstrated by more than 50 *** reaction provides a novel and efficient method for the synthesis of polyfunctionalized pyrroles under very mild metal-free conditions without other additives.

关键词： Photocatalysis Vinyl azides Alkenes Pyrroles Annulation Radical reactions

Surface Deposition of Ni(OH)_(2) and Lattice Distortion Induce the Electrochromic Performance Decay of NiO Films in Alkaline Electrolyte

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Energy & Environmental Materials 2024年第3期7卷 257-267页

作者： Kejun Xu Liuying wang Chaoqun Ge long wang Bin wang Zhuo wang Chuanwei Zhang Gu Liu Xi'an Research Institute of High Technology Xi'an 710025China School of Material Science and Engineering Zhengzhou UniversityZhengzhou 450001China School of Mechanical Engineering Xi'an University of Science and TechnologyXi'an 710054China

NiO,an anodic electrochromic material,has applications in energy-saving windows,intelligent displays,and military ***,its electrochromic mechanism and reasons for its performance degradation in alkaline aqueous electrolytes are complex and poorly understood,making it challenging to improve NiO thin *** studied the phases and electrochemical characteristics of NiO films in different states(initial,colored,bleached and after 8000 cycles)and identified three main reasons for performance ***,Ni(OH)_(2)is generated during electrochromic cycling and deposited on the NiO film surface,gradually yielding a NiO@Ni(OH)_(2)core-shell structure,isolating the internal NiO film from the electrolyte,and preventing ion ***,the core-shell structure causes the mode of electrical conduction to change from first-to second-order conduction,reducing the efficiency of ion transfer to the surface Ni(OH)_(2)***,Ni(OH)_(2)and NiOOH,which have similar crystal structures but different b-axis lattice parameters,are formed during electrochromic cycling,and large volume changes in the unit cell reduce the structural stability of the thin ***,we clarified the mechanism of electrochromic performance degradation of NiO films in alkaline aqueous electrolytes and provide a route to activation of NiO films,which will promote the development of electrochromic technology.

关键词： alkaline electrolyte electrochromism NiO film performance attenuation mechanism

Research on shell-side heat and mass transfer with multi-component in LNG spiral-wound heat exchanger under sloshing conditions

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Petroleum Science 2024年第2期21卷 1333-1345页

作者： Xue-Ping Du guang-Lei Yu Ya-Cheng Xu Zhi-Jie Chen Nai-Liang Li Huan-guang wang School of Low-carbon Energy and Power Engineering China University of Mining and TechnologyXuzhou221116JiangsuChina Key Laboratory of Thermo-Fluid Science and Engineering MOEXi'an Jiaotong UniversityXi'an710049ShaanxiChina Xi'an Aerospace Propulsion Test Technology Institute Xi'an710100ShaanxiChina

The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model. Besides, the mathematical model under the sloshing condition was obtained through mathematical derivation, and the corresponding UDF code was loaded into FLUENT as the momentum source term. The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition. The shell-side heat and mass transfer characteristics of the SWHE were investigated by adjusting the component ratio and other working conditions. It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects. The sloshing condition is beneficial to reduce the flow resistance. The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions, considering both the heat transfer and pressure *** results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNG SWHE under ocean sloshing conditions.

关键词： Spiral-wound heat exchanger Sloshing conditions Two-phase flow Multi-component Heat and mass transfer

Two-dimensional particle-in-cell modeling of blow-off impulse by X-ray irradiation

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Nuclear Science and Techniques 2024年第3期35卷 53-69页

作者： Ruibo Li Jin-long Jiao Hui Luo Dezhi Zhang Dengwang wang Kai wang Graduate School of China Academy of Engineering Physics Beijing 100193China Zhejiang Institute of Modern Physics Institute of AstronomySchool of PhysicsZhejiang UniversityHangzhou 310027China National Key Laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear TechnologyXi’an 710024China

Space objects such as spacecraft or missiles may be exposed to intense X-rays in outer space,leading to severe *** reinforcement of these objects to reduce the damage caused by X-ray irradiation is a significant *** blow-off impulse(BOI)is a crucial physical quantity for investigating material damage induced by X-ray ***,the accurate calculation of BOI is challenging,particularly for large deformations of materials with complex *** this study,we develop a novel two-dimensional particle-in-cell code,Xablation2D,to calculate BOIs under far-field X-ray *** significantly reduces the dependence of the numerical simulation on the grid *** reliability of this code is verified by simulation results from open-source codes,and the calculated BOIs are consistent with the experimental and analytical results.

关键词： X-ray irradiation Energy deposition Blow-off impulse Particle in cells

Structure and 2p decay mechanism of^(18)Mg

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Nuclear Science and Techniques 2024年第6期35卷 145-154页

作者： long Zhou De-Qing Fang Si-Min wang Hui Hua Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China Shanghai Research Center for Theoretical Nuclear Physics NSFC and Fudan UniversityShanghai 200438China School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking UniversityBeijing 100871China

The recently discovered,extremely proton-rich nuclide 18 Mg exhibits ground-state decay via two sequential two-proton(2p)emissions through the intermediate nucleus,*** study investigates the structure and the initial 2p decay mechanism of^(18)Mgby examining the density and correlations of the valence protons using a three-body Gamow coupled-channel *** results show that the ground state of^(18)Mgis significantly influenced by the continuum,resulting in a significant s-wave ***,based on the current framework,this does not lead to a significant deviation in mirror symmetry in either the structure or spectroscopy of the 18Mg-18C ***,the time evolution analysis of the^(18)Mgground state suggests a simultaneous 2p emission during the first step of *** observed nucleon-nucleon correlations align with those of the light-mass 2p emitters,indicating a consistent decay behavior within this nuclear region.

关键词： Structure of^(18)Mg Two-proton decay Proton-proton correlation

Risk assessment of rockburst using SMOTE oversampling and integration algorithms under GBDT framework

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Journal of Central South University 2024年第8期31卷 2891-2915页

作者： wang, Jia-chuang Dong, long-jun School of Resources and Safety Engineering Central South University Changsha China

Rockburst is a common geological disaster in underground engineering, which seriously threatens the safety of personnel, equipment and property. Utilizing machine learning models to evaluate risk of rockburst is gradually becoming a trend. In this study, the integrated algorithms under Gradient Boosting Decision Tree (GBDT) framework were used to evaluate and classify rockburst intensity. First, a total of 301 rock burst data samples were obtained from a case database, and the data were preprocessed using synthetic minority over-sampling technique (SMOTE). Then, the rockburst evaluation models including GBDT, eXtreme Gradient Boosting (XGBoost), Light Gradient Boosting Machine (LightGBM), and Categorical Features Gradient Boosting (CatBoost) were established, and the optimal hyperparameters of the models were obtained through random search grid and five-fold cross-validation. Afterwards, use the optimal hyperparameter configuration to fit the evaluation models, and analyze these models using test set. In order to evaluate the performance, metrics including accuracy, precision, recall, and F1-score were selected to analyze and compare with other machine learning models. Finally, the trained models were used to conduct rock burst risk assessment on rock samples from a mine in Shanxi Province, China, and providing theoretical guidance for the mine’s safe production work. The models under the GBDT framework perform well in the evaluation of rockburst levels, and the proposed methods can provide a reliable reference for rockburst risk level analysis and safety management.

关键词： confusion matrix K-fold cross-validation random search grid rockburst evaluation SMOTE oversampling

Microbial Sulfate Reduction and Its Role in Carbon Sequestration in Marine Sediments

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Journal of Earth Science 2024年第4期35卷 1378-1381页

作者： Xiting Liu Houjie wang Jiarui Liu guang-Chao Zhuang Key Laboratory of Submarine Geosciences and Prospecting Technology College of Marine GeosciencesOcean University of ChinaQingdao266100China Qingdao Marine Science and Technology Center Laboratory for Marine GeologyQingdao266237China Department of Earth Planetaryand Space SciencesUniversity of CaliforniaLos Angeles90095USA Frontiers Science Center for Deep Ocean Multispheres and Earth System(FDOMES)and Key Laboratory of Marine Chemistry Theory and Technology Ministry of EducationOcean University of ChinaQingdao266100China

0 INTRODUCTION The carbon buried in marine sediments in the form of organic carbon or carbonate minerals represents the largest pathway for carbon removal from Earth's surface environments(Sun and Turchyn,2014).Microbial sulfate reduction(MSR)is a fundamental biogeochemical process occurring in marine sediments,where sulfate-reducing bacteria(SRB)reduce sulfate(SO42-)to sulfide(S2-)using organic matter or methane as electron donors(Jorgensen,2021).

关键词： buried carbonate environments

Plume-lithosphere interaction in the Comei Large Igneous Province: Evidence from two types of mafic dykes in Gyangze, south Tibet, China

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China Geology 2024年第1期7卷 80-90页

作者： Ya-ying wang Ling-sen Zeng Li-e Gao Li-long Yan Ling-hao Zhao Jia-hao Gao Ying-long Di guang-xu Li Yi-hong Tian Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China National Research Center for Geoanalysis Chinese Academy of Geological SciencesBeijing 100037China China Nonferrous Metals(Guilin)Geology and Mining Co. LtdGuilin 541004China

Two suites of mafic dykes,T1193-A and T1194-A,outcrop in Gyangze area,southeast *** are in the area of Comei LIP and have indistinguishable field occurrences with two other dykes in Gyangze,T0902 dyke with 137.7±1.3 Ma zircon age and T0907 dyke with 142±1.4 Ma zircon age reported by wang YY et al.(2016),indicating coeval formation *** all the four diabase dykes into consideration,two different types,OIB-type and weak enriched-type,can be ***“OIB-type”samples,including T1193-A and T0907 dykes,show OIB-like geochemical features and have initial Sr-Nd isotopic values similar with most mafic products in Comei Large Igneous Provinces(LIP),suggesting that they represent melts directly generated from the Kerguelen mantle ***“weak enriched-type”samples,including T1194-A and T0902 dykes,have REEs and trace element patterns showing withinplate affinity but have obvious Nb-Ta-Ti negative *** show uniform lowerεNd(t)values(−6‒−2)and higher 87Sr/86Sr(t)values(0.706‒0.709)independent of their MgO variation,indicating one enriched mantle *** their closely spatial and temporal relationship with the widespread Comei LIP magmatic products in Tethyan Himalaya,these“weak enriched-type”samples are consistent with mixing of melts from mantle plume and the above ancient Tethyan Himalaya subcontinental lithospheric mantle(SCLM)in different *** weak enriched mafic rocks in Comei LIP form one special rock group and most likely suggest large scale hot mantle plume-continental lithosphere *** process may lead to strong modification of the Tethyan Himalaya lithosphere in the Early Cretaceous.

关键词： OIB type diabase Comei Large Igneous Province Weakly enriched diabase Plume-lithosphere interaction Nb-Ta-Ti negative anomaly Kerguelen plume Geological survey engineering Tibet Plateau