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Design and Verification of Parallel Hip Exoskeleton Considering Output Torque Anisotropy

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Journal of Bionic Engineering 2024年第3期21卷 1305-1320页

作者： Jilong xu Yunzhan niu Fucai Liu Engineering research Center of the Ministry of Education for Intelligent Control System and Intelligent Equipment Yanshan UniversityQinhuangdao066004China Key Laboratory of Industrial Computer Control Engineering of Heibei Province Yanshan UniversityQinhuangdao066004China College of Mechanical Engineering Yanshan UniversityQinhuangdao066004China

In rehabilitation training,it is crucial to consider the compatibility between exoskeletons and human legs in ***,most exoskeletons today adopt an anthropomorphic serial structure,which results in rotational centers that are not precisely aligned with the center of the hip *** address this issue,we introduce a novel exoskeleton called the Parallel Hip Exoskeleton(PH-Exo)in this ***-Exo is meticulously designed based on the anisotropic law of output *** the friction of the drive components,a dynamic model of the human-machine complex is *** analysis demonstrates that PH-Exo not only exhibits outstanding torque performance but also achieves high controllability in both flexion/extension and adduction/abduction ***,a robust controller is designed to address model uncertainty,friction,and external *** experiments indicate that under the control of the robust controller,each motor achieves excellent tracking performance.

关键词： Hip exoskeleton Parallel mechanism Misalignment Anisotropy Output torque

An Asynchronous Variational Integrator for Contact Problems Involving Elastoplastic Solids

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Acta Mechanica Solida Sinica 2024年第2期37卷 305-315页

作者： Zongwu niu Zixiao Wang Yongxing Shen University of Michigan-Shanghai Jiao Tong University Joint Institute Shanghai Jiao Tong UniversityShanghai200240China School of Agriculture and Biology Shanghai Jiao Tong UniversityShanghai200240China Department of Biostatistics Johns Hopkins Bloomberg School of Public HealthBaltimoreMaryland21205USA

Simulations of contact problems involving at least one plastic solid may be costly due to their strong nonlinearity and requirements of *** this work,we develop an explicit asynchronous variational integrator(AVI)for inelastic non-frictional contact problems involving a plastic *** AVI assigns each element in the mesh an independent time step and updates the solution at the elements and nodes *** asynchrony makes the AVI highly efficient in solving such bi-material *** advantage of the AVI,the constitutive update is locally performed in one element at a time,and contact constraints are also enforced on only one *** time step of the contact element is subdivided into multiple segments,and the fields are updated *** a contact event,only one element involving a few degrees of freedom is considered,leading to high *** proposed formulation is first verified with a pure elastodynamics benchmark and further applied to a contact problem involving an elastoplastic solid with non-associative volumetric *** numerical results indicate that the AVI exhibits excellent energy behaviors and has high computational efficiency.

关键词： Asynchronous variational integrator Plasticity Contact Computational efficiency Finite element method

An integrative mathematical model of microwave ion thruster for mHz-frequency thrust noise analysis

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Chinese Journal of Aeronautics 2024年第4期37卷 121-136页

作者： xiang niu Hui LIU Daren YU Plasma Propulsion Laboratory Harbin Institute of TechnologyHarbin 150001China

Many high-precision space missions need thrusters to produce thrust with low noise to compensate for disturbances and ensure satellite platform stability. Microwave ion thruster is characterized with a wide thrust range and potential for these missions. A cost-effective and accurate mathematical model is crucial for mHz-frequency thrust noise analysis and feedback controller design. The Particle-In-Cell(PIC) and global models are two common simulation tools. The PIC model is characterized with high accuracy but huge computation cost, which is difficult to analyze long-time performance characteristics. Now, the global model is only used for the discharge chamber with low accuracy and cannot reflect ion extraction properties. In this paper, an integrative mathematical model is built for a 1-cm microwave ion thruster and can reflect ion beamlet divergence and impingement on the Accelerator Grid(AG). Simulation results show good agreement with experiments at 0.06 sccm. However, the model demonstrates worse consistency with experiments when the flux increases to 0.1 sccm, which may be because the influence of neutral gas on the Electron Cyclotron resonance(ECr) is not considered in the model. A long-time(1000 s) simulation is conducted with this model under 35 μN. It takes 3 hrs, and the thrust noise reaches 1 μN/Hz^(0.5) at 1 mHz.

关键词： Electric propulsion Microwave ion thruster Integrative model Sheath property Ion beamlet divergence Thrust noise Plasma

Vascularization ability of glioma stem cells in different three-dimensional microenvironments

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regenerative Biomaterials 2024年第1期3卷 34-43页

作者： xuanzhi Wang Tao xu Chaoshi niu Department of Neurosurgery The First Affliated Hospital of USTCDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefeiAnhui230036China Department of Neurosurgery Sichuan Provincial People's HospitalUniversity of Electronic Science and Technology of ChinaChengdu 610072People's Republic of China Center for Bio-intelligent Manufacturing and Living Matter Bioprinting Research Institute of Tsinghua University in ShenzhenTsinghua UniversityShenzhen 518057People's Republicof China

Glioblastoma(GBM)is among the most common and aggressive adult central nervous system *** prominent charac-teristic of GBM is the presence of abnormal microvessels.A significant correlation between angiogenesis and prognosis has been *** reconstructing this neovascula-rization and tumor microenvironment through personalized in vitro disease models presents a significant ***,it is crucial to develop new anti-angiogenic therapies for *** this study,3D bioprinted glioma stem cell(GSC)-laden hydrogel scaffolds,hybrid Gsc hydrogels and ceil-free hydrogel scaffolds were manufactured to investigate the vas-cularization ability of GsCs in varying 3D microenvironments.

关键词： 3D bioprinting xenograft tumors GSC-laden hydrogel scaffold glioblastoma angiogenesis

Jackson-type inequalities on high-dimensional spheres

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Science China Mathematics 2024年第11期67卷 2571-2586页

作者： Yeli niu Feng Dai Department of Mathematics Shanghai Normal University Department of Mathematical and Statistical Sciences University of Alberta

We study Jackson's inequality on high-dimensional spheres with respect to the modulus of smoothness defined via the rotation *** obtain a version of Jackson's inequality with a dimensionfree constant,extending Newman and Shapiro's well-known results in 1964 from the case of r = 1 and p = ∞ to more general *** results partially overcome the curse of *** also establish similar results on the equivalence of the K-functional and modulus of smoothness.

关键词： modulus of smoothness $K$-functional Jackson's inequality high-dimensional approximation

Event-triggered sliding mode control of linear repetitive processes and its application in metal rolling process

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Science China(Information Sciences) 2024年第3期67卷 167-181页

作者： xinyu LV Yugang niu James LAM Key Laboratory of Smart Manufacturing in Energy Chemical Process (East China University of Science and Technology) Ministry of Education Department of Mechanical Engineering The University of Hong Kong

This paper investigates the design problem of a sliding mode controller for linear repetitive processes(LrPs) with a finite pass length on each pass. Under limited communication resources, an eventtriggered mechanism is implemented from the sensors to the controller, whose triggered sequence is consistent with the evolution direction of LrPs. To periodically orchestrate communication between the controller and actuator, a round-robin scheduling mechanism is established based on the pass length. A sliding function involving the state and pass profile is constructed, and the sliding mode controller is designed using triggered states and pass profile signals. Feasible controller gains are attained to ensure the stability of the resultant closed-loop system. Finally, the proposed strategy is implemented for a multi-roll metal rolling process.

关键词： event-triggered mechanism linear repetitive processes metal rolling process round-robin scheduling sliding mode control

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Bilayer solid-electrolyte interphase structure enables a 440 Wh kg^(-1) lithium metal pouch cell to achieve 130 cycles

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Science China Chemistry 2024年第3期67卷 751-752页

作者： xiong Liu Chaojiang niu School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China

Lithium(Li) metal has been considered one of the most promising anodes due to its high theoretical capacity, lightweight and low electrochemical potential. The cell-level energy density of rechargeable lithium metal batteries(LMBs) is expected to surpass 500 Wh kg^(-1) after replacing the graphite anode in lithium-ion batteries [1].

关键词： lithium electrolyte layer

SETD2 in cancer:functions,molecular mechanisms,and therapeutic regimens

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Cancer Biology & Medicine 2024年第9期21卷 725-730页

作者： Yawen Weng Jing xue Ningning niu State Key Laboratory of Systems Medicine for Cancer Stem Cell Research CenterRen Ji HospitalShanghai Cancer InstituteShanghai Jiao Tong University School of MedicineShanghai 200127China

In recent years,the histone methyltransferase SET domain containing 2(SETD2)has garnered significant attention for its involvement in *** we aim to summarize the research advances regarding SETD2 in tumors,elucidate the role in global epigenetic regulation,highlight potential therapeutic regimens for patients with SETD2 deficiency,and outline future research directions.

关键词： SETD2 regimen therapeutic

Modeling tuberous sclerosis complex with human induced pluripotent stem cells

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World Journal of Pediatrics 2024年第3期20卷 208-218页

作者： Weibo niu Benjamin Siciliano Zhexing Wen Department of Psychiatry and Behavioral Sciences Emory University School of MedicineWhitehead Research Building 447615 Michael StreetAtlantaGA 30322USA The Graduate Program in Molecular and Systems Pharmacology Laney Graduate SchoolEmory UniversityAtlanta.GA 30322.USA Department of Cell Biology Emory University School of MedicineWhitehead Research Building 447615 Michael StreetAtlantaGA30322USA Department of Neurology Emory University School of MedicineWhitehead Research Building 447.615 Michael StreetAtlantaGA 30322USA

Background Tuberous sclerosis complex(TSC)is an autosomal dominant genetic disorder with a birth incidence of I:6000 in the United States that is characterized by the growth of non-cancerous tumors in multiple organ systems including the brain,kidneys,lungs,and ***,TSCis also associated with signicant neurological manifestations including epilepsy TSC-associated neuropsychiatric disorders,intellectual disabilities,and autism spectrum *** in the TSCI or TSC2 genes are well-established causes of TSC,which lead to TSC1/TSC2 deficiency in organs and hyper-activation of the mammalian target of rapamycin signaling *** models have been widely used to study the effect of TSCl/2 genes on the development and function of the *** considerable progress in understanding the molecular mechanisms underlying TSC in animal models,a human-specific model is urgently needed to investigate the effects of TSCl/2 mutations that are unique to human *** sources Literature reviews and research articles were published in PubMed-indexed *** Human-induced pluripotent stem cells(iPSCs),which capture risk alleles that are identical to their donors and have the capacity to differentiate into virtually any cell type in the human body,pave the way for the empirical study of previously inaccessible biological systems such as the developing human *** In this review,we present an overview of the recent progress in modeling TSC with human iPSC models,the existing limitations,and potential directions for future research.

关键词： Induced pluripotent stem cells Three-dimensional cultures Tuberous sclerosis complex Two-dimensional cultures