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Biomimetic soft robotic wrist with 3.DOF motion and stiffness tunability based on ring-reinforced pneumatic actuators and a particle jamming joint

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science china(Technological sciences) 2024年第3期67卷 774-790页

作者： HU TeTe LU xinjiang YI Jian WANG YuHui XU Du State Key Laboratory of Precision Manufacturing for Extreme Service Performance School of Mechanical and Electrical EngineeringCentral South UniversityChangsha 410083China

The human wrist, a complex articulation of skeletal muscles and two-carpal rows, substantially contributes to improvements in maneuverability by agilely performing three-degree-of-freedom(3.DOF) orienting tasks and regulating stiffness according to variations in interaction forces. However, few soft robotic wrists simultaneously demonstrate dexterous 3.DOF motion and variable stiffness;in addition, they do not fully consider a soft-rigid hybrid structure of integrated muscles and two carpal *** this study, we developed a soft-rigid hybrid structure to design a biomimetic soft robotic wrist(BSRW) that is capable of rotating in the x and y directions, twisting around the z-axis, and possessing stiffness-tunable capacity. To actuate the BSRW, a lightweight soft-ring-reinforced bellows-type pneumatic actuator(SRBPA) with large axial, linear deformation(η_(lcmax)=70.6%,η_(lemax)=54.3.) and small radial expansion(η_(demax)=3.7%) is designed to mimic the motion of skeletal muscles. To represent the function of two-carpal rows, a compact particle-jamming joint(PJJ) that combines particles with a membrane-covered ballsocket mechanism is developed to achieve various 3.DOF motions and high axial load-carrying capacity(>60 N). By varying the jamming pressure, the stiffness of the PJJ can be adjusted. Finally, a centrally positioned PJJ and six independently actuated SRBPAs, which are in an inclined and antagonistic arrangement, are sandwiched between two rigid plates to form a flexible,stable, and compact BSRW. Such a structure enables the BSRW to have a dexterous 3.DOF motion, high load-carrying ability,and stiffness tunability. Experimental analysis verify 3.DOF motion of BSRW, producing force of 29.6 N and 3. N and torque of2.2 Nm in corresponding rotations. Moreover, the range of rotational angle and stiffness-tuning properties of BSRW are studied by applying jamming pressure to the PJJ. Finally, a system combining a BSRW and a soft enclosing gripper is proposed to demo

关键词： pneumatic soft actuators particle jamming robotic wrist soft robotics stiffness-tunable

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CMC surfaces in the hyperbolic 3.space

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Chinese science Bulletin 1998年第7期43卷 547-550页

作者： YU Zuhuan 1, 2 and LI Zhenqi 1, 3.1. Institute of mathematics, Fudan university, Shanghai 20043., china 2. Department of mathematics,Sichuan Union university, Chengdu 610064, china 3. Department of mathematics, Nanchang university, Nanchang 3. nstitute of Mathemalics Fudan University Shanghai China Department of mathematics Sichuan Union University Chengdu China Department of mathematics Nanchang University Nanchang China

CMC-H surfaces satisfying H≥1 are studied. It is proved that these surfaces possess a natural representation which is a generalization of the Bryant’s result.

关键词： hyperbolic space CMC surface Weierstrass representation.

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Congruences on ideal nil-extension of completely regular semigroups

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Chinese science Bulletin 1998年第5期43卷 379-381页

作者： REN Xueming 1, 2 GUO Yuqi 2 and CEN Jiaping (Shum Kar-ping) 3.. Department of mathematics, Xi’an university of Architecture & Technology, Xi’an 710055, china 2. Department of mathematics, Yunnan university, Kunming 650091, china 3. Department of Department of mathematics Xi’an University of Architecture & Technology Xi’an China Department of mathematics Yunnan University Kunming China Department of mathematics Chinese University of Hong Kong Hong Kong

Let S be an ideal nil-extension of a completely regular semigroup K by a nil semigroup Q with zero. A concept of admissible congruence pairs (δ,ω) of S is introduced, where δ and ω are a congruence on Q and a congruence on K respectively. It is proved that every congruence on S can be uniquely respresented by an admissible congruence pair (δ,ω) of S. Suppose that ρ K denotes the Rees congruence induced by the ideal K of S. Then it is shown that for any congruence σ on S,a mapping Γ:σ|→(σ Q,σ K) is an order-preserving bijection from the set of all congruences on S onto the set of all admissible congruence pairs of S,where σ K is the restriction of σ to K and σ Q=(σ∨ρ K)/ρ K. Moreover,the lattice of congruences of S is also discussed. As a special case,every congruence on completely Archimedean semigroups S is described by an admissible quarterple of S. The following question is asked: Is the lattice of congruences of the completely Archimedean semigroup a semimodular lattice?

关键词： completely regular semigroups ideal nil-extension congruences.

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Characteristics of fMRI BOLD signal and its neurophysiological mechanism

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Progress in Natural science:Materials International 2007年第6期17卷 630-638页

作者： Zhao Xiaohu1,2, Wu Yigen3.and Guo Shengli3.1. College of Life sciences, Zhejiang university, Hangzhou 3.0058, china 2. Imaging Department of Tongji Hospital of Tongji university, Shanghai 200065, china 3. College of mathematics and Physics, Nanjing university of Information science and Technology, Nanjing 210044, china) College of Life sciences Zhejiang University Hangzhou 310058 China Imaging Department Tongji Hospital Tongji University Shanghai 200065 China College of mathematics and Physics Nanjing University of Information Science and Technology Nanjing 210044 China

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

关键词： functional magnetic resonance imaging blood oxygen level dependent nonlinear response neural electrophysiological activity.

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Some properties on multivariate filter banks with a matrix factorization

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Progress in Natural science:Materials International 2005年第2期15卷 20-30页

作者： LIAN Qiaofang1, XIAO Hongying2* and CHEN Qiuhui3.1. Department of mathematics, Beijing Jiaotong university, Beijing 100044, china 2. Institute of mathematics, Academy of mathematics and system sciences, Chinese Academy of sciences, Beijing 100080, china 3. Department of Scientific Computing and Computer Applications, Zhongshan university, Guangzhou 510275, china) Dept. of mathematics Beijing Jiaotong Univ. Beijing 100044 China Inst. of mathematics Acad. of Math. and System Sci. Chinese Acad. of Sciences Beijing 100080 China Dept. of Scientific Computing Zhongshan Univ. Guangzhou 510275 China

A class of multivariate filter banks with a matrix factorization has been developed by Chen et al. The main purpose of this paper is to discuss some further properties of this kind of filter bank, such as the completeness, accuracy of the corresponding scaling functions and the relationships with Daubechies' wavelets and the multi-wavelets provided by Chui and Lian. Moreover, some examples are given to show that this kind of filter bank has a higher accuracy for the scaling functions.

关键词： filter banks completeness accuracy matrix factorization

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Online uniform machine covering with the known largest size

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Progress in Natural science:Materials International 2007年第11期17卷 1271-1278页

作者： Cao Shunjuan1,2 and Tan Zhiyi1,3.1. Department of mathematics, Zhejiang university, Hangzhou 3.0027, china 2. Department of mathematics, Zhejiang Forestry university, Hangzhou 3.13.0, china 3. State Key Laboratory of CAD & CG, Zhejiang university, Hangzhou 3.0027, china) Department of mathematics Zhejiang University Hangzhou 310027 China Department of mathematics Zhejiang Forestry University Hangzhou 311300 China State Key Laboratory of CAD and CG Zhejiang University Hangzhou 310027 China

This paper investigates the semi-online scheduling problem with the known largest size on two uniform machines. The objective is to maximize the minimum machine completion time. Both lower bounds and algorithms are given. Algorithms are optimal for the majority values of s≥1, where s is the speed ratio of the two machines. The largest gap between the competitive ratio and the lower bound is about 0.064. Moreover, the overall competitive ratio 2 matches the overall lower bound.

关键词： scheduling and covering uniform machine design and analysis of algorithm online competitive ratio

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The construction of infinite families of any k-tight optimal and singular k-tight optimal directed double loop networks

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science china mathematics 2007年第7期50卷 1055-1064页

作者： Bao-xing CHEN~(1+) Xie-bin CHEN~2 Ji-xiang MENG~3.Wen-jun XIAO~4 1 Department of Computer science,Zhangzhou Teachers College,Zhangzhou 3.3.00,china 2 Department of mathematics and Information science,Zhangzhou Teachers College,Zhangzhou 3.3.00,china 3.College of mathematics & system science,xinjiang university,urumqi 83.046,china 4 Department of Computer science,South china {13. of Technology,Guangzhou 510641,china Department of Computer science Zhangzhou Teachers College Zhangzhou China Department of mathematics and Information science Zhangzhou Teachers College Zhangzhou China College of mathematics & system science Xinjiang University Urumqi China Department of Computer science South China University of Technology Guangzhou China

The double loop network(DLN)is a circulant digraph with n nodes and outdegree *** is an important topological structure of computer interconnection networks and has been widely used in the designing of local area networks and distributed *** the number n of nodes,how to construct a DLN which has minimum diameter?This problem has attracted great attention.A related and longtime unsolved problem is:for any given non-negative integer k,is there an infinite family of k-tight optimal DLN?In this paper,two main results are obtained:(1)for any k≥0,the infinite families of k-tight optimal DLN can be constructed,where the number n(k,e,c)of their nodes is a polynomial of degree 2 in e with integral coefficients containing a parameter c.(2)for any k≥0, an infinite family of singular k-tight optimal DLN can be constructed.

关键词： double loop network diameter k-tight optimal singular k-tight optimal 05C12 05C20 05C85

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On the periodic solutions of a type of differential-iterative equations

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Chinese science Bulletin 1998年第3期43卷 204-206页

作者： GE Weigao 1, LIU Zhengrong 2 and YU Yuanhong 3.1. Department of Applied mathematics, Beijing Institute of Technology, Beijing 100081, china 2. Department of mathematics, Yunnan {3., Kunming 650091, china 3. Institute of Applied mathematics, C Department of Applied mathematics Beijing Institute of Technology Beijing China Department of mathematics Yunnan University Kunming China Institute of Applied mathematics Chinese Academy of Sciences Beijing China

Sufficient conditions for the existence of periodic solutions to a type of nonautonomous differential_iterative equations are given.

关键词： differential_iterative equation periodic solution fixed point.

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On conformal measures for infinitely renormalizable quadratic polynomials

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science china mathematics 2005年第10期48卷 1411-1420页

作者： HUANG Zhiyong~1 JIANG Yunping~(2,3. & WANG Yuefei~3.1. School of Information,Renmin university of china,Beijing 100872,china 2. Department of {3.,Queens College,City university of New York,NY 113.7,USA Department of {3.,Graduate School,City university of New York,New York,NY 10016,USA 3. Academy of {3. and systems science,Chinese Academy of sciences,Beijing 100080,china School of Information Renmin University of China Beijing China Department of mathematics Queens College City University of New York NY USA Department of mathematics Graduate School City University of New York New York USA Academy of mathematics and systems science Chinese Academy of Sciences Beijing China

We study a conformal measure for an infinitely renormalizable quadratic polynomial. We prove that the conformal measure is ergodic if the polynomial is unbranched and has complex bounds. The main technique we use in t... 详细信息

关键词： Julia set, conformal measure, three-dimensional puzzle, infinitely renormalizable quadratic polynomial.

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The regular representation and regular covariant representation of crossed products of Woronowicz C^(*)-algebras

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science china mathematics 2005年第9期48卷 1245-1259页

作者： ZHANG Xiaoxia~(1,2) & GUO Maozheng~(1,3. 1. School of Mathematical sciences,Peking university,Beijing 100871,china 2. Department of {3.,Yantai university,Yantai 264005,china 3. LMAM,Peking university,Beijing 100871,china School of Mathematical sciences Peking University Beijing China Department of mathematics Yantai University Yantai China LMAM Peking University Beijing China

In this paper,it is shown that the regular representation and regular covariant representation of the crossed products A×α G correspond to the twisted multiplicative unitary operators,where A is a Woronowicz C~*-algebra acted upon by a discrete group ***,it is also shown that the regular covariant C~*-algebra is the Woronowicz C~*-algebra which corresponds to a multiplicative ***,an explicit description of the multiplicative unitary operator for C(SU_q(2) )×α (?) is given in terms of those of the Woronowicz C~*-algebra C(SU_q(2) ) and the discrete group G.

关键词： multiplicative unitary operator, Woronowicz C*-algebra, crossed product.

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