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Physics-informed deep Koopman operator for Lagrangian dynamic systems

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Science China(Information Sciences) 2024年第9期67卷 146-163页

作者： Xuefeng WANG yang CAO Shaofeng CHEN yu KANG Department of Automation University of Science and Technology of China State Key Laboratory of Fire Science University of Science and Technology of China Institute of Advanced Technology University of Science and Technology of China

Accurate mechanical system models are crucial for safe and stable control. Unlike linear systems,Lagrangian systems are highly nonlinear and difficult to optimize because of their unknown system *** research thus used deep neural networks to generate linear models of original systems by mapping nonlinear dynamic systems into a linear space with a Koopman observable function encoder. The controller then relies on the Koopman linear model. However, without physical information constraints, ensuring control consistency between the original nonlinear system and the Koopman system is tough, as the learning process of the Koopman observation function is unsupervised. This paper thus proposes a two-stage learning algorithm that uses structural subnetworks to build a physics-informed network topology to simultaneously learn the Koopman observable functions and the system energy representation. In the Koopman matrix learning session, a quadratic-constrained optimization problem is solved to ensure that the Koopman representation satisfies the energy difference matching hard constraint. The proposed energy-preserving deep Lagrangian Koopman(EPDLK) framework effectively represents the dynamics of the Lagrangian system while ensuring control consistency. The effectiveness of EPDLK is compared with those of various Koopman observable function construction methods in multistep prediction and trajectory tracking tasks. EPDLK achieves better control consistency by guaranteeing energy difference matching, which facilitates the application of the control law generated on the Koopman system directly to the original nonlinear Lagrangian system.

关键词： Koopman operator Lagrangian physics-informed nonlinear model predictive control (MPC)

Understanding Discrepancy of Power System Dynamic Security Assessment with Unknown Faults: A Reliable Transfer Learning-based Method

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 427-431页

作者： Chao Ren Han yu Yan Xu Zhao yang Dong School of Computer Science and Engineering Nanyang Technological UniversitySingapore School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore

This letter proposes a reliable transfer learning(RTL)method for pre-fault dynamic security assessment(DSA)in power systems to improve DSA performance in the presence of potentially related unknown *** takes individual discrepancies into consideration and can handle unknown faults with incomplete *** experiment results demonstrate high DSA accuracy and computational efficiency of the proposed RTL *** analysis shows RTL can guarantee system performance.

关键词： Adversarial training dynamic security assessment maximum classifier discrepancy missing data transfer learning

Intrinsic lithiophilic carbon host derived from bacterial cellulose nanofiber for dendrite-free and long-life lithium metal anode

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Nano Research 2024年第5期17卷 4203-4210页

作者： Gangyi Xiong Jiayu yu Yalan Xing Puheng yang Shichao Zhang School of Materials Science and Engineering Beihang UniversityBeijing 100191China School of Physics Science and Nuclear Energy Engineering Beihang UniversityBeijing 100191China

Although lithium metal is considered a promising anode for advanced Li-S and Li-air batteries,the uncontrolled dendrite growth and infinite volume change impede its practical ***,we report an ideal framework composed of carbonized bacterial cellulose(CBC)nanofibers,which shows intrinsic lithiophilicity to molten lithium without any lithiophilic surface *** wetting behavior of molten lithium can be significantly improved because its surface functional groups provide thermodynamical driving force,and the high surface roughness derived from nanocracks leads to rapid infusion in *** hybrid anode exhibits long cycle life up to 2000 h and excellent deep stripping-platting capacity up to 20 mAh·cm^(-2).When the anode is assembled with LiFePO_(4) cathode,the full cell delivers a good cycling stability up to 700 *** is attributed to the intrinsic lithiophilic scaffold,which can not only lower the nucleation barrier of Li and provide uniform nucleation sites for stable Li stripping/plating,but also offer interspace to accommodate volume fluctuation of lithium during long *** work provides a new manner to achieve a series of intrinsic lithiophilic carbon skeletons based on the large family of biomass materials and organic materials.

关键词： intrinsic lithiophilicity lithium metal anode bacterial cellulose lithium dendrite long cycling life

One-pot synthesis of a giant twisted double-layer chiral macrocycle via [4+8] imine condensation and its X-ray structure

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Chinese Chemical Letters 2024年第10期35卷 241-243页

作者： yu Pang Min Wang Ning-Hua yang Min Xue Yong yang School of Science Department of PhysicsKey Laboratory of Optical Field Manipulation of Zhejiang ProvinceZhejiang Sci-Tech UniversityHangzhou 310018China School of Chemistry and Chemical Engineering Key Laboratory of Surface&Interface Science of Polymer Materials of Zhejiang ProvinceZhejiang Sci-Tech UniversityHangzhou310018China

Trifluoroacetic acid(TFA)catalyzed condensation reaction between tetraaminooxacalix[4]arene and N-alkylcarbazole-3,6-dicarbaldehyde in CH_(2)Cl2afforded a single product in 87%–89%***-defined yet undissolvable1H NMR spectra suggested formation of robust and discrete structures in solution.X-ray single crystal analysis further revealed a giant twisted double-layer chiral macrocycle in the solid state,which was formed from[4+8]condensation of the two reactants via 16 imine *** calculations discovered that only the[4+8]twisted product is thermodynamically favorable,which accounts for its highly selective and efficient formation out of a library of many other combinations.

关键词： One-pot synthesis Oxacalixarene Dynamic covalent chemistry Chiral macrocycle X-ray single crystal

Aging Mongolian pine plantations face high risks of drought-induced growth decline:evidence from both individual tree and forest stand measurements

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Journal of Forestry Research 2024年第2期35卷 109-120页

作者： Mingyong Li Leilei yang yu Cao Dedong Wu Guangyou Hao CAS Key Laboratory of Forest Ecology and Management Institute of Applied EcologyChinese Academy of SciencesShenyang 110016People’s Republic of China Key Laboratory of Terrestrial Ecosystem Carbon Neutrality Liaoning ProvinceShenyang 110016People’s Republic of China Daqinggou Ecological Research Station Institute of Applied EcologyChinese Academy of SciencesShenyang 110016People’s Republic of China University of Chinese Academy of Sciences Beijing 100049People’s Republic of China Research Institute of Sand Control and Utilization Liaoning ProvinceFuxin 123000People’s Republic of China

Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited *** important species for afforestation in dry environments of northern China,Mongolian pine(Pinus sylvestris *** Litv.)has recently exhibited growth decline and dieback on many sites,particularly pronounced in old-growth ***,changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly *** this study,tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young(9-13 years)and aging(35-52 years)plantations of Mongolian pine in a water-limited area of northern China.A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger *** addition,all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older *** of growth to drought of the older plantation might be attributed to more severe hydraulic limitations,as reflected by their lower sapwood-and leaf-specific hydraulic *** study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with *** results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.

关键词： Tree age Drought stress Mongolian pine plantation Tree rings Remote sensing Plant hydraulics

Systematic Elastostatic Stiffness Model of Over-Constrained Parallel Manipulators Without Additional Constraint Equations

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Chinese Journal of Mechanical Engineering 2024年第4期37卷 258-276页

作者： Chao yang Wenyong yu Wei Ye Qiaohong Chen Fengli Huang College of Mechanical and Electrical Engineering Jiaxing UniversityJiaxing 314001ZhejiangChina Zhejiang Siekon Transmission Technology Co. Ltd.Jiaxing 314001ZhejiangChina National and Local Joint Engineering Research Center of Reliability Analysis and Testing for Mechanical and Electrical Products Zhejiang Sci-Tech UniversityHangzhou 310018ZhejiangChina School of Computer Science and Technology Zhejiang Sci-Tech UniversityHangzhou 310018ZhejiangChina

The establishment of an elastostatic stiffness model for over constrained parallel manipulators(PMs),particularly those with over constrained subclosed loops,poses a challenge while ensuring numerical *** study addresses this issue by proposing a systematic elastostatic stiffness model based on matrix structural analysis(MSA)and independent displacement coordinates(IDCs)extraction *** begin,the closed-loop PM is transformed into an open-loop PM by eliminating constraints.A subassembly element is then introduced,which considers the flexibility of both rods and *** approach helps circumvent the numerical instability typically encountered with traditional constraint *** IDCs and analytical constraint equations of nodes constrained by various joints are summarized in the appendix,utilizing multipoint constraint theory and singularity analysis,all unified within a single coordinate ***,the open-loop mechanism is efficiently closed by referencing the constraint equations presented in the appendix,alongside its elastostatic *** proposed method proves to be both modeling and computationally efficient due to the comprehensive summary of the constraint equations in the Appendix,eliminating the need for additional *** example utilizing an over constrained subclosed loops demonstrate the application of the proposed *** conclusion,the model proposed in this study enriches the theory of elastostatic stiffness modeling of PMs and provides an effective solution for stiffness modeling challenges they present.

关键词： Parallel manipulator Elastostatic stiffness model Matrix structural analysis Subassembly element Independent displacement coordinates

Ru-doped functional porous materials for electrocatalytic water splitting

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Nano Research 2024年第3期17卷 982-1002页

作者： Chongao Tian Rui Liu yu Zhang Wenxiu yang Bo Wang Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials Advanced Technology Research Institute(Jinan)Advanced Research Institute of Multidisciplinary ScienceSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Library Beijing Institute of TechnologyBeijing 100081China

Electrolytic water splitting(EWS)is an attractive and promising technique for the production of hydrogen ***,the sluggish kinetic rate of hydrogen/oxygen evolution reactions leads to a high overpotential and low energy *** to date,Pt/Ir-based nanocatalysts have become the state-of-the-art EWS catalysts,but disadvantages such as high cost and low earth abundance greatly limit their applications in EWS *** an attractive candidate for the Pt/Ir catalysts,series of Ru-based nanomaterials have aroused much attention for their low price,Pt-like hydrogen bond strength,and high EWS *** particular,Ru-doped functional porous materials have been becoming one of the most representative EWS catalysts,which can not only achieve the dispersion and adjustment for active Ru sites,but also simultaneously solve the problems of mass transfer and catalytic conversion in *** this review,the design and preparation strategies of Ru-doped functional porous materials toward EWS in recent years are summarized,including Ru-doped metal organic frameworks(MOFs),Ru-doped porous organic polymers(POPs),and their ***,detailed structure–activity relationships induced by the tuned geometric/electronic structures of Ru-doped functional porous materials are further depicted in this *** but not least,the challenges and perspectives of Ru-doped functional porous materials catalysts are reasonably proposed to provide fresh ideas for the design of Ru-based EWS catalysts.

关键词： Ru-based catalyst functional porous materials electrolytic water splitting oxygen evolution reaction hydrogen evolution reaction

Bile acids,gut microbiota,and therapeutic insights in hepatocellular carcinoma

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Cancer Biology & Medicine 2024年第2期21卷 144-162页

作者： yang Song Harry CH Lau Xiang Zhang Jun yu Institute of Digestive Disease and Department of Medicine and Therapeutics State Key Laboratory of Digestive DiseaseLi Ka Shing Institute of Health SciencesCUHK Shenzhen Research InstituteThe Chinese University of Hong KongHong KongChina Department of Gastroenterology Zhongshan Hospital Xiamen UniversityXiamen 361004China

Hepatocellular carcinoma(HCC)is a prevalent and aggressive liver *** interplay between bile acids(BAs)and the gut microbiota has emerged as a critical factor in HCC development and *** normal conditions,BA metabolism is tightly regulated through a bidirectional interplay between gut microorganisms and *** gut microbiota plays a critical role in BA metabolism,and BAs are endogenous signaling molecules that help maintain liver and intestinal *** note,dysbiotic changes in the gut microbiota during pathogenesis and cancer development can disrupt BA homeostasis,thereby leading to liver inflammation and fibrosis,and ultimately contributing to HCC ***,understanding the intricate interplay between BAs and the gut microbiota is crucial for elucidating the mechanisms underlying *** this review,we comprehensively explore the roles and functions of BA metabolism,with a focus on the interactions between BAs and gut microorganisms in ***,therapeutic strategies targeting BA metabolism and the gut microbiota are discussed,including the use of BA agonists/antagonists,probiotic/prebiotic and dietary interventions,fecal microbiota transplantation,and engineered *** summary,understanding the complex BA-microbiota crosstalk can provide valuable insights into HCC development and facilitate the development of innovative therapeutic approaches for liver malignancy.

关键词： Bile acid gut microbiota hepatocellular carcinoma therapeutics microbiota modulation

Paradoxical herniation associated with hyperbaric oxygen therapy after decompressive craniectomy: A case report

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World Journal of Clinical Cases 2024年第10期12卷 1793-1798页

作者： Zhong-Xing Ye Xin-Xin Fu yang-zong Wu Ling Lin Liang-Qi Xie yu-Ling Hu Yi Zhou Zhu-Gui You Hai Lin Department of Neurosurgery The Second People's Hospital of Fujian Province(The Second Affiliated Hospital of Fujian University of Traditional Chinese Medicine)Fuzhou 350001Fujian ProvinceChina Department of Neurosurgery The Second Hospital of LongyanLongyan 364000Fujian ProvinceChina Department of Neurosurgery Zhangping City HospitalLongyan 364400Fujian ProvinceChina

BACKGROUND Whether hyperbaric oxygen therapy(HBOT)can cause paradoxical herniation is still *** SUMMARY A 65-year-old patient who was comatose due to brain trauma underwent decompressive craniotomy and gradually regained consciousness after *** was administered 22 d after surgery due to speech *** herniation appeared on the second day after treatment,and the patient’s condition worsened after receiving mannitol treatment at the rehabilitation *** timely skull repair,the paradoxical herniation was resolved,and the patient regained consciousness and had a good recovery as observed at the follow-up *** Paradoxical herniation is rare and may be caused by ***,the underlying mechanism is unknown,and the understanding of this phenomenon is *** use of mannitol may worsen this *** skull repair can treat paradoxical herniation and prevent serious complications.

关键词： Decompressive craniectomy Hyperbaric oxygen therapy Mannitol Paradoxical herniation Case report