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Stabilization of Continuous-Time Systems Against Stochastic Network Uncertainties:Fundamental Variance Bounds

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Journal of Systems Science & Complexity 2021年第5期34卷 1858-1878页

作者： qi tian CHEN Jie School of Automation Science and Engineering Key Laboratory of Autonomous Systems and Networked ControlSouth China University of TechnologyGuangzhou 510640China Department of Electrical Engineering City University of Hong KongHong KongChina

This paper studies the stabilizability and stabilization of continuous-time systems in the presence of stochastic multiplicative *** authors consider multi-input,multi-output(MIMO)linear time-invariant systems subject to multiple static,structured stochastic uncertainties,and seek to derive fundamental conditions to ensure that a system can be stabilized under a mean-square *** the stochastic control framework,this problem can be considered as one of optimal control under state-or input-dependent random noises,while in the networked control setting,a problem of networked feedback stabilization over lossy communication *** authors adopt a mean-square small gain analysis approach,and obtain necessary and sufficient conditions for a system to be meansquare stabilizable via output *** single-input,single-output(SISO)systems,the condition provides an analytical bound,demonstrating explicitly how plant unstable poles,nonminimum phase zeros,and time delay may impose a limit on the uncertainty variance required for mean-square *** MIMO minimum phase systems with possible delays,the condition amounts to solving a generalized eigenvalue problem,readily solvable using linear matrix inequality optimization techniques.

关键词： Mean-square small gain theorem multiplicative stochastic uncertainty networked control

Simulation and characteristics analysis of a wavefield in a thermoelastic medium adopting the rotated staggered-grid pseudospectral method and L-S theory

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Science China Earth Sciences 2021年第8期64卷 1390-1408页

作者： Yuanxie LI Cai liu Zhiqi GUO Yang liu Xuan FENG You tian qi LU College of Geo-exploration Science and Technology Jilin UniversityChangchun 130026China

The simulation of wave propagation in high-temperature media requires thermoelastic *** this paper,we apply the rotated-staggered-grid pseudo-spectral method(RSG-PSM)to solving thermoelastic governing equations based on L-S theory.A time splitting method is used to solve the stiffness problem of the equations,and we introduce the rotated staggered pseudo-spectral operator and centered pseudo-spectral operator to compute the first-order spatial derivatives and second-order spatial derivatives,*** the case of the heterogeneous-medium model,the Crank-Nicolson explicit method is used instead of the pseudo-spectral method to compute the *** properties and propagation of the thermal coupled wavefield are discussed,and we compare the simulation results obtained using the pseudo-spectral method,staggered-grid pseudo-spectral method,and *** the case of an isotropic homogeneous medium,we obtain stable and highly accurate results using the time splitting method combined with the ***,the algorithm cannot be applied with a large time step when the thermal conductivity changes dramatically,and the algorithm is unstable when the reference temperature has a gradient *** optimal combined application of the mesh generation mode and numerical algorithm is explored,laying a foundation for the extension of these methods to thermoporoelasticity,thermoviscoelasticity,and anisotropy.

关键词： Thermoelastic wave L-S theory Rotated-staggered-grid pseudo-spectral method Seismic wavefield simulation Time splitting method

Self-assembly and morphological characterization of two-component functional amyloid proteins

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Chinese Chemical Letters 2017年第5期28卷 1062-1068页

作者： qi qi tian-Xin Zhao Bo-Lin An Xuan-Yong liu Chao Zhong School of Physical Science and Technology Shanghai Tech UniversityShanghai 200120China Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 200050China University of Chinese Academy of Sciences Beijing 100049China

Functional amyloid has been increasingly applied as self-assembling nanostructures to construct multifunctional ***,little has been known how different side domains,varied fusion positions and subunits affect self-assembly and morphologies of amyloid ***,we constructed three groups of two-component amyloid proteins based on CsgA,the major protein components of Escherichia coli biofilms,to bridge these *** showed that all fusion proteins have amyloid features,as indicated by Congo red *** force microscopy（AFM） indeed reveals that these fusion proteins are able to self-assemble into fibrils,with an average diameter of 0.5-2 nm and length of hundreds of nanometers to several *** diameter of fibrils increases with the increase of the molecular weight of fusion domains,while the dynamic assembly of recombinant proteins was delayed as a result of the introduction of fusion ***,fusion of the same functional domains but at intermediate position seems to cause the most interference on fibril assembly compared with those fused at C or Nterminus,as mainly short and irregular fibrils were *** phenomenon appears more pronounced for randomly coiled mussel foot proteins（Mfps） than for rigid chitin-binding domain（CBD）.Finally,increase of the molecular weight of tandem repeats in protein monomer seemed to increase the fibril diameter of the resultant fibrils,but either reduction of the tandem repeats of CsgA to one single belta-sheet loop or increase in the number of tandem repeats of CsgAs from one to four produced shorter and intermittent fibrils compared with CsgA control *** studies therefore provide insights into self-assembly of two-component amyloid proteins and lay the foundation for rational design of multifunctional molecular biomaterials.

关键词： Amyloid Biofilms Atomic force microscopy Self-assembly Nanomaterials Supramolecular structure

A Note on Determine the Greatest Common Subfamily of Two NFSRs by Grbner Basis

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Journal of Systems Science & Complexity 2015年第5期28卷 1231-1242页

作者： WANG Zhongxiao qi Wenfeng tian tian Luoyang University of Foreign Language State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou Information Science and Technology Institute

For nonlinear feedback shift registers(NFSRs), their greatest common subfamily may be not unique. Given two NFSRs, the authors only consider the case that their greatest common subfamily exists and is unique. If the greatest common subfamily is exactly the set of all sequences which can be generated by both of them, the authors can determine it by Grbner basis theory. Otherwise, the authors can determine it under some conditions and partly solve the problem.

关键词： Greatest common subfamily Grbner basis nonlinear feedback shift register stream cipher

A New Distinguishing Attack on Grain-V1 with 111 Initialization Rounds

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Journal of Systems Science & Complexity 2019年第3期32卷 970-984页

作者： MA Zhen tian tian qi Wenfeng National Digital Switching System Engineering & Technological Research Center

The Grain-v1 stream cipher has been selected in the eSTREAM hardware finalists. In this paper, the authors derive a new distinguishing attack on Grain-v1 with 111 initialization rounds in a single-key setting. To achieve this goal, the authors present two delicate strategies targeting an obvious distinguishing probability of the output difference of reduced Grain-v1. The authors show that conditional differential cryptanalysis of reduced Grain-v1 with 111 initialization rounds could mount a distinguishing attack with success probability about 0.8281 for all secret keys. It is also shown that when the attacking round further increases to 112 and 113, the distributions of the output differences are nearly random. Thus far, to the best of the authors' knowledge, the attack on Grain-v1 with 111 initialization rounds is the best single-key cryptanalytic result for reduced versions of Grain-vl in terms of the number of attacking rounds.

关键词： Cryptanalysis differential cryptanalysis distinguishing attack Grain-v1 stream cipher

On Characteristic Functions of De Bruijn Sequences

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Chinese Journal of Electronics 2016年第2期25卷 304-311页

作者： TANG Zhenwei qi Wenfeng tian tian Department of Applied Mathematics Zhengzhou Information Science and Technology Institute

In 1982, H. Fredricksen presented the upper and lower bounds of the number of ones in the truth table of characteristic functions of de Bruijn sequences. In this paper, the distribution of ones in the truth table of characteristic functions of de Bruijn sequences is further studied. We provide the upper and lower bounds of the number of ones in the partial truth table of characteristic functions of de Bruijn sequences. Furthermore, the two bounds are tight.

关键词： Nonlinear feedback shift registers De Bruijn sequences Weight of the truth table

Interference coupling analysis based on a hybrid method: application to a radio telescope system

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Research in Astronomy and Astrophysics 2018年第2期18卷 7-18页

作者： qing-Lin Xu Yang qiu Jin tian qi liu School of Mechano-Electronic Engineering Xidian University Xinjiang Astronomical Observatory Chinese Academy of Sciences

Working in a way that passively receives electromagnetic radiation from a celestial body, a radio telescope can be easily disturbed by external radio frequency interference as well as electro- magnetic interference generated by electric and electronic components operating at the telescope site. A quantitative analysis of these interferences must be taken into account carefully for further electro- magnetic protection of the radio telescope. In this paper, based on electromagnetic topology theory, a hybrid method that combines the Baum-liu-Tesche （BLT） equation and transfer function is proposed. In this method, the coupling path of the radio telescope is divided into strong coupling and weak cou- pling sub-paths, and the coupling intensity criterion is proposed by analyzing the conditions in which the BLT equation simplifies to a transfer function. According to the coupling intensity criterion, the topological model of a typical radio telescope system is established. The proposed method is used to solve the interference response of the radio telescope system by analyzing subsystems with different coupling modes separately and then integrating the responses of the subsystems as the response of the entire system. The validity of the proposed method is verified numerically. The results indicate that the proposed method, compared with the direct solving method, reduces the difficulty and improves the efficiency of interference prediction.

关键词： telescopes -- methods: analytical - methods: numerical - waves

New process for production of ultra-thin grain oriented silicon steel

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Rare Metals 2006年第z1期25卷 454-457页

作者： GAO Xiuhua liu En qiU Chunlin qi Kemin tian Yanwen The State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 China The State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 China The State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 China The State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 China School of Materials and Metallurgy Northeastern University Shenyang 110004 China

The Hi-B silicon steels were cold rolled by cross shear rolling (CSR) with different mismatch speed ratio(MSR)s and conventional rolling(CR) respectively, followed by primary recrystallization annealing. The effects of MSR and annealing temperature on magnetic properties of ultra-thin grain oriented silicon steel were analyzed. Experimental results show that, with the increase of MSR, the magnetic properties can be remarkably improved. The higher the annealing temperature is, the higher the magnetic induction and the lower the iron loss in ultra-thin silicon steel is.

关键词： magnetic properties ultra-thin grain oriented silicon steel cross shear rolling primary recrystallization

Chondroitinase ABC combined with Schwann cell transplantation enhances restoration of neural connection and functional recovery following acute and chronic spinal cord injury

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Neural Regeneration Research 2025年第5期20卷 1467-1482页

作者： Wenrui Qu Xiangbing Wu Wei Wu Ying Wang Yan Sun Lingxiao Deng Melissa Walker Chen Chen Heqiao Dai qi Han Ying Ding Yongzhi Xia George Smith Rui Li Nai-Kui liu Xiao-Ming Xu Spinal Cord and Brain Injury Research Group Stark Neurosciences Research InstituteDepartment of Neurological SurgeryIndiana University School of MedicineIndianapolisINUSA Department of Hand Surgery the Second Hospital of Jilin UniversityChangchunJilin ProvinceChina Shriners Hospitals Pediatric Research Center Temple University School of MedicinePhiladelphiaPAUSA Department of Anatomy&Cell Biology Indiana University School of MedicineIndianapolisINUSA

Schwann cell transplantation is considered one of the most promising cell-based therapy to repair injured spinal cord due to its unique growth-promoting and myelin-forming properties.A the Food and Drug Administration-approved Phase I clinical trial has been conducted to evaluate the safety of transplanted human autologous Schwann cells to treat patients with spinal cord injury.A major challenge for Schwann cell transplantation is that grafted Schwann cells are confined within the lesion cavity,and they do not migrate into the host environment due to the inhibitory barrier formed by injury-induced glial scar,thus limiting axonal reentry into the host spinal *** we introduce a combinatorial strategy by suppressing the inhibitory extracellular environment with injection of lentivirus-mediated transfection of chondroitinase ABC gene at the rostral and caudal borders of the lesion site and simultaneously leveraging the repair capacity of transplanted Schwann cells in adult rats following a mid-thoracic contusive spinal cord *** report that when the glial scar was degraded by chondroitinase ABC at the rostral and caudal lesion borders,Schwann cells migrated for considerable distances in both rostral and caudal *** Schwann cell migration led to enhanced axonal regrowth,including the serotonergic and dopaminergic axons originating from supraspinal regions,and promoted recovery of locomotor and urinary bladder ***,the Schwann cell survival and axonal regrowth persisted up to 6 months after the injury,even when treatment was delayed for 3 months to mimic chronic spinal cord *** findings collectively show promising evidence for a combinatorial strategy with chondroitinase ABC and Schwann cells in promoting remodeling and recovery of function following spinal cord injury.

关键词： axonal regrowth bladder function chondroitinase ABC functional recovery glial scar lentivirus migration Schwann cell spinal cord injury transplantation