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IQC based robust stability verification for a networked system with communication delays

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Science China(Information Sciences) 2018年第12期61卷 112-126页

作者： Zhike WANG tong zhou Department of Automation and TNList Tsinghua University School of Aviation Operations and Services University of Air Force Aviation

In this paper, we consider robust stability analysis of a networked system with uncertain communication delays. Each of its subsystems can have different dynamics, and interconnections among its subsystems are arbitrary. It is assumed that there exists an uncertain but constant delay in each communication channel. Using the so called integral quadratic constraint(IQC) technique, a sufficient robust stability condition is derived utilizing a sparseness assumption of the interconnections, and a set of decoupled robustness conditions are further derived which depend only on parameters of each subsystem, the subsystem connection matrix(SCM) and the selected IQC multipliers. These characteristics result in an evident improvement of computational efficiency for robustness verification of the networked system with delay uncertainties, which is illustrated by some numerical results.

关键词： large scale networked system time delay robust stability integral quadratic constraints linear matrix inequalities

Robust state estimation for uncertain linear systems with random parametric uncertainties

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Science China(Information Sciences) 2017年第1期60卷 157-169页

作者： Huabo LIU tong zhou Department of Automation Tsinghua University College of Automation and Electrical Engineering Qingdao University Tsinghua National Laboratory for Information Science and Technology (TNList) Tsinghua University

In this paper, we investigate state estimations of a dynamical system with random parametric uncertainties which may arbitrarily affect a plant state-space model. A robust estimator is derived based on expectation minimization of estimation errors. An analytic solution similar to that of the well-known Kalman filter is derived for this new robust estimator which can be realized recursively with a comparable computational complexity. Under some weak assumptions, it is proved that this estimator converges to a stable system,the covariance matrix of estimation errors is bounded, and the estimation is asymptotically unbiased. Numerical simulations show that the obtained robust filter has an estimation accuracy comparable to other robust estimators and can be applied in a wider range.

关键词： robustness state estimation recursive estimation parametric uncertainty regularized leastsquares

Robustness analysis and distributed control of a networked system with time-varying delays

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Control Theory and Technology 2020年第3期18卷 293-306页

作者： Zhike WANG tong zhou Department of Automation Tsinghua UniversityBeijing W0084China School of Aviation Operations and Services University of Air Force AviationChangchun Jilin 130022China

This paper is concerned with the robustness analysis and distributed output feedback control of a networked system with uncertain time-varying communication *** system consists of a collection of linear time-invariant subsystems that are spatially interconnected via an arbitrary directed *** a dissipation inequality that incorporates dynamic hard lQCs(integral quadratic constraints)for the delay uncertainties,we derive some sufficient robustness conditions in the form of coupled linear matrix inequalities,in which the couplld parts reflect the interconnection structure of the *** then provide a procedure to construct a distributed controller to ensure the robust stability of the closed-loop system and to achieve a prescribed lzgain *** effectiveness of the proposed approach is demonstrated by some numerical examples.

关键词： Networked system time delay integral quadratic constraints(IQCs) robust stability distributed control

Tailoring magnetism in semiconductors

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Science China(Physics,Mechanics & Astronomy) 2018年第6期61卷 91-93页

作者： Igor Zutic tong zhou Department of Physics University at Buffalo State University of New York Buffalo NY 14260 USA

While logic devices in conventional electronics rely on the control of the charged carriers in the semiconductor chips, robust information storage in computer hard drives and magnetic random access memory is implemented using the carriers＇ spin in ferromagnetic metals. A long quest to realize magnetic semiconductors [1-3] can be simply summarized as： 1＋1〉2, in hope that combining the control of charge and spin in a single material would become more than just the sum of its separate parts （charge and spin） and enable new or improved functionalities [3].

关键词：半导体芯片磁力定制计算机硬盘铁磁性逻辑设备信息存储充电

Enhanced sampling in molecular dynamics simulations and their latest applications--A review

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Nano Research 2023年第12期16卷 13474-13497页

作者： Wenhui Shen tong zhou Xinghua Shi Laboratory of Theoretical and Computational Nanoscience National Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Molecular dynamics(MD)simulations are capable of reproducing dynamic evolution at the molecular scale,but are limited by temporal *** sampling has emerged as a powerful tool to improve sampling efficiency,thereby extending the simulation timescales of a range of simulation studies in materials,chemistry,biology,nanoscience,and related ***,we provide a systematic overview of established enhanced sampling methods and clarify the principles and interconnections between these ***,we categorically elaborate on the state-of-the-art applications of enhanced sampling in the last five *** these exemplified applications,we discuss the unique advantages of this technique,showing the prospects and challenges for its future *** review could help researchers in different fields gain a comprehensive understanding of the enhanced sampling technique,and jointly facilitate its application and advancement.

关键词： molecular dynamics enhanced sampling free energy barrier time scale biological system

Robust state estimation for uncertain linear systems with deterministic input signals

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Control Theory and Technology 2014年第4期12卷 383-392页

作者： Huabo LIU tong zhou Department of Automation Tsinghua University College of Automation Engineering Qingdao University Tsinghua National Laboratory for Information Science and Technology (TNList) Tsinghua University

In this paper, we investigate state estimations of a dynamical system in which not only process and measurement noise, but also parameter uncertainties and deterministic input signals are involved. The sensitivity penalization based robust state estimation is extended to uncertain linear systems with deterministic input signals and parametric uncertainties which may nonlinearly affect a state-space plant model. The form of the derived robust estimator is similar to that of the well-known Kalman filter with a comparable computational complexity. Under a few weak assumptions, it is proved that though the derived state estimator is biased, the bound of estimation errors is finite and the covariance matrix of estimation errors is bounded. Numerical simulations show that the obtained robust filter has relatively nice estimation performances.

关键词： Robust estimation Deterministic input Regularized least-squares

Highly efficient and stable 2D/3D perovskite solar cells based on surface reconstruction and energy level alignment

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Science China Chemistry 2024年第9期67卷 3083-3090页

作者： Qiaohui Li Hang Liu tong zhou Key Laboratory of Rubber-Plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-PlasticsQingdao University of Science and TechnologyQingdao 266042China The Centre of Nanoscale Science and Technology and Key Laboratory of Functional Polymer Materials Institute of Polymer ChemistryCollege of ChemistryNankai UniversityTianjin 300071China

Realizing simultaneous adjustment of energy levels and work functions in two-dimensional/three-dimensional(2D/3D)perovskite solar cells(PSCs)is a ***,a pseudohalide 3,5-bis(trifluoromethyl)benzylammonium tetrafluoroborate(TFPMABF_(4))was used to react with unreacted Pb I2on the surface of 3D bulky perovskite to form a mixed halide of 2D perovskite denoted(TF-PMA)_(2)FA_(2)Pb_(3)I_(8)(BF_(4))_(2).This novel 2D/3D perovskite enables the simultaneous adjustment of energy levels and work functions on the surface of active *** to the significantly enhanced quality of 2D/3D perovskite film,decreased surface defects and increased charge carrier lifetime,the 2D/3D PSCs exhibit an outstanding power conversion efficiency(PCE)of 25.15%and a high V_(OC)of 1.194 ***,2D/3D PSCs exhibit remarkable enhancements in environmental stability,unencapsulated devices retaining more than 90%of their initial PCE at 50%humidity for 2,280 h.

关键词： 2D/3D perovskite perovskite solar cells organic spacers energy levels alignment

The potential of using blood circular RNA as liquid biopsy biomarker for human diseases

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Protein & Cell 2021年第12期12卷 911-946页

作者： Guoxia Wen tong zhou Wanjun Gu State Key Laboratory of Bioelectronics School of Biological Sciences and Medical EngineeringSoutheast UniversityNanjing210096China Department of Physiology and Cell Biology Reno School of MedicineUniversity of NevadaRenoNV89557USA

Circular RNA(circRNA)is a novel class of single-stranded RNAs with a closed loop *** majority of circRNAs are formed by a back-splicing process in pre-mRNA *** expression is dynamically regulated and shows spatiotemporal patterns among cell types,tissues and developmental *** have important biological functions in many physiological processes,and their aberrant expression is implicated in many human *** to their high stability,circRNAs are becoming promising biomarkers in many human diseases,such as cardiovascular diseases,autoimmune diseases and human *** this review,we focus on the translational potential of using human blood circRNAs as liquid biopsy biomarkers for human *** highlight their abundant expression,essential biological functions and significant correlations to human diseases in various components of peripheral blood,including whole blood,blood cells and extracellular *** addition,we summarize the current knowledge of blood circRNA biomarkers for disease diagnosis or prognosis.

关键词： peripheral blood circular RNA liquid biopsy human diseases translational biomarkers

An automatic Q-factor matching method for eliminating 77%of the ZRO of a MEMS vibratory gyroscope in rate mode

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Microsystems & Nanoengineering 2024年第3期10卷 35-48页

作者： Jingbo Ren tong zhou Yi zhou Yixuan Li Yan Su School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210000China

Mismatching quality factors(Q-factors)is one of the main factors causing zero-rate output(ZRO)in degenerate(DE)Micro-Electro-Mechanical Systems(MEMS)vibratory *** eliminate the ZRO of the DE MEMS gyroscope,this study introduces a method for real-time identification and automatic matching of Q-factors in rate *** leveraging the vibration characteristics of the DE MEMS vibratory gyroscope in rate mode,dedicated online test methods are designed to determine the Q-factors for both the drive and sense modes,enabling online identification of the Q-factor ***,an automatic Q-factor matching system is designed utilizing the mechanical-thermal dissipation mechanism of the resistive *** effectiveness of this proposed method is validated through simulations and experiments conducted on a MEMS disk resonator gyroscope(DRG).The results show a measurement error within 4%for Q-factor identification,and automatic Q-factor matching effectively reduces the ZRO by 77%.Employing this automatic Q-factor matching method successfully reduces the ZRO that is caused by the mismatching of Q-factors in the MEMS DRG from 0.11°/s to 0.025°/s and improves the bias instability(BI)from 0.40°/s to 0.19°/s.

关键词： matching mode method