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Flexible Strain Sensors with Ultra‑High Sensitivity and Wide Range Enabled by Crack‑Modulated Electrical Pathways

Nano-Micro Letters 2025年第3期17卷 246-264页

作者： Yunzhao Bai Yunlei Zhou Xuanyu Wu Mengfei Yin Liting Yin Shiyuan Qu Fan Zhang Kan Li YongAn Huang State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074People’s Republic of China Flexible Electronics Research Center Huazhong University of Science and TechnologyWuhan 430074People’s Republic of China Hangzhou Institute of Technology Xidian UniversityHangzhou 311200People’s Republic of China School of Mechano‑Electronic engineering Xidian UniversityXi’an 710071People’s Republic of China department of aerospace and mechanical engineering University of Southern CaliforniaLos AngelesCA 90089USA

This study presents a breakthrough in flexible strain sensor technology with the development of an ultrahigh sensitivity and wide-range sensor,addressing the critical challenge of reconciling sensitivity with measurement *** by the structure of bamboo slips,we introduce a novel approach that utilises liquid metal to modulate the electrical pathways within a cracked platinum fabric *** resulting sensor demonstrates a gauge factor greater than 108 and a strain measurement capability exceeding 100%.The integration of patterned liquid metal enables customisable tuning of the sensor’s response,while the porous fabric structure ensures superior comfort and air permeability for the *** design not only optimises the sensor’s performance but also enhances the electrical stability that is essential for practical *** systematic investigation,we reveal the intrinsic mechanisms governing the sensor’s response,offering valuable insights for the design of wearable strain *** sensor’s exceptional performance across a spectrum of applications,from micro-strain to large-strain detection,highlights its potential for a wide range of real-world uses,demonstrating a significant advancement in the field of flexible electronics.

关键词： Flexible strain sensor Fabric Crack Response regulation Epidermal device

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Adaptive Control of a Two-Link Robot Using Batch Least-Square Identifier

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IEEE/CAA Journal of Automatica Sinica 2021年第1期8卷 86-93页

作者： Mostafa Bagheri Iasson Karafyllis Peiman Naseradinmousavi Miroslav Krstić the department of mechanical and aerospace engineering University of California San Diego and San Diego State UniversityLa JollaCA 92037 USA the department of Mathematics National Technical University of AthensAthina 10682Greece the department of mechanical engineering San DiegoCA 92182 USA the department of mechanical and aerospace engineering University of California San DiegoLa JollaCA 92037 USA

We design a regulation-triggered adaptive controller for robot manipulators to efficiently estimate unknown parameters and to achieve asymptotic stability in the presence of coupled *** manipulators are widely used in telemanipulation systems where they are subject to model and environmental *** conventional control algorithms on such systems can cause not only poor control performance,but also expensive computational costs and catastrophic ***,system uncertainties need to be estimated through designing a computationally efficient adaptive control *** focus on robot manipulators as an example of a highly nonlinear *** a case study,a 2-DOF manipulator subject to four parametric uncertainties is ***,the dynamic equations of the manipulator are derived,and the corresponding regressor matrix is constructed for the unknown *** a general nonlinear system,a theorem is presented to guarantee the asymptotic stability of the system and the convergence of parameters'***,simulation results are discussed for a two-link manipulator,and the performance of the proposed scheme is thoroughly evaluated.

关键词： Backstepping least-square identifier robot manipulators trigger-based adaptive control

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Cavitation dynamics in a vitrimer

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Acta Mechanica Sinica 2021年第5期37卷 767-772,I0001页

作者： Zhaoqiang Song Shengqiang Cai department of mechanical and aerospace engineering University of CaliforniaSan DiegoLa JollaCA 92093USA

Vitrimer is a polymer network with dynamic covalent bonds,which can be dynamically broken and *** to the dynamic covalent bonds,vitrimer behaves like an elastomer at high deformation rate or low temperature but a viscous fluid at low deformation rate or high *** this article,we study the cavitation dynamics in a vitrimer,which is known to be an important damaging mechanism in *** the formulation,a nonlinear three-dimensional rate-dependent constitutive model for the vitrimer is adopted,in which both of the strain stiffening and the kinetics of dynamic exchanging reactions are *** theory predicts strong dependence of the cavitation dynamics on the loading *** computational results may help to reveal some critical insights into the rate-dependent fracture in vitrimer.

关键词： Vitrimer Cavitation dynamics Strain stiffening Viscoelasticity

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21-Component compositionally complex ceramics: Discovery of ultrahigh-entropy weberite and fergusonite phases and a pyrochlore–weberite transition

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Journal of Advanced Ceramics 2022年第4期11卷 641-655页

作者： Mingde QIN Heidy VEGA Dawei ZHANG Sarath ADAPA Andrew J.WRIGHT Renkun CHEN Jian LUO department of Nano engineering University of California San DiegoLa Jolla 92093USA department of Chemistry and Biochemistry University of California San DiegoLa Jolla 92093USA Program of Materials Science and engineering University of California San DiegoLa Jolla 92093USA department of mechanical and aerospace engineering University of California San DiegoLa Jolla 92093USA

Two new high-entropy ceramics(HECs)in the weberite and fergusonite structures,along with the unexpected formation of ordered pyrochlore phases with ultrahigh-entropy compositions and an abrupt pyrochlore–weberite transition,are discovered in a 21-component oxide *** the Gibbs phase rule allows 21 equilibrium phases,9 out of the 13 compositions examined possess single HEC phases(with ultrahigh ideal configurational entropies:~2.7kB per cation or higher on one sublattice in most cases).Notably,(15RE_(1/15))(Nb_(1/2)Ta_(1/2))O_(4) possess a single monoclinic fergusonite(C2/c)phase,and(15RE_(1/15))_(3)(Nb_(1/2)Ta_(1/2))_(1)O_(7) form a single orthorhombic(C222_(1))weberite phase,where 15RE_(1/15) represents Sc_(1/15)Y_(1/15)La_(1/15)Pr_(1/15)Nd_(1/15)Sm_(1/15)Eu_(1/15)Gd_(1/15)Tb_(1/15)Dy_(1/15)Ho_(1/15)Er_(1/15)Tm_(1/15) Yb_(1/15)Lu_(1/15).Moreover,a series of eight(15RE_(1/15))_(2+x)(Ti_(1/4)Zr_(1/4)Ce_(1/4)Hf_(1/4))_(2−2x)(Nb_(1/2)Ta_(1/2))_(x)O_(7) specimens all exhibit single phases,where a pyrochlore–weberite transition occurs within 0.75

关键词： compositionally complex ceramics high-entropy ceramics(HECs) weberite pyrochlore fergusonite ultrahigh-entropy ceramics many-component ceramics

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Refraction characteristics of phononic crystals

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Acta Mechanica Sinica 2015年第4期31卷 481-493页

作者： Sia Nemat-Nasser department of mechanical and aerospace engineering University of California

Some of the most interesting refraction prop- erties of phononic crystals are revealed by examining the anti-plane shear waves in doubly periodic elastic composites with unit cells containing rectangular and/or elliptical multi- inclusions. The corresponding band structure, group velocity, and energy-flux vector are calculated using a powerful mixed variational method that accurately and efficiently yields all the field quantities over multiple frequency pass-bands. The background matrix and the inclusions can be anisotropic, each having distinct elastic moduli and mass densities. Equifrequency contours and energy-flux vectors are read- ily calculated as functions of the wave-vector components. By superimposing the energy-flux vectors on equifrequency contours in the plane of the wave-vector components, and supplementing this with a three-dimensional graph of the corresponding frequency surface, a wealth of information is extracted essentially at a glance. This way it is shown that a composite with even a simple square unit cell con- taining a central circular inclusion can display negative or positive energy and phase velocity refractions, or simply performs a harmonic vibration （standing wave）, depending on the frequency and the wave-vector. Moreover, that the same composite when interfaced with a suitable homoge- neous solid can display：（1） negative refraction with negative phase velocity refraction; （2） negative refraction with pos- itive phase velocity refraction; （3） positive refraction with negative phase velocity refraction; （4） positive refraction with positive phase velocity refraction; or even （5） completereflection with no energy transmission, depending on the fre- quency, and direction and the wavelength of the plane-wave that is incident from the homogeneous solid to the interface. For elliptical and rectangular inclusion geometries, analyti- cal expressions are given for the key calculation quantities. Expressions for displacement, velocity, linear m

关键词： Doubly periodic composites - Phononiccrystals Band structure Group and energy-flux vectors

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Nonlinear dynamics investigation of contact force in a cam–follower system using the Lyapunov exponent parameter,power spectrum analysis,and Poincarémaps

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International Journal of mechanical System Dynamics 2022年第2期2卷 214-230页

作者： Louay S.Yousuf department of mechanical engineering San Diego State UniversitySan DiegoCaliforniaUSA

The aim of this article is to detect the detachment between the cam and the follower using the largest Lyapunov exponent parameter,the power density function of fast Fourier transform,and Poinarémaps due to the nonlinear dynamics phenomenon of the *** detachment between the cam and the follower was investigated for different cam speeds and different internal distances of the follower guide from *** study focuses on the use of the cam–follower system with a bionic quadruped robot through a linkage *** absorber(spring–damper–mass)systems at the very end of the follower were used to improve the dynamic performance and to reduce the detachment between the cam and the *** SolidWorks program was used in the numerical solution,while a high‐speed camera at the foreground of the OPTOTRAK 30/20 equipment was used to identify the follower *** friction and impact were considered between the cam and the follower and between the follower and its *** general,when the cam and the follower are in permanent contact,there is no loss in potential energy,and no impact or *** detachment between the cam and the follower increases with increasing coefficient of restitution in the presence of the impact.

关键词： nonlinear dynamics Lyapunov exponent non‐periodic motion contact force

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Particles dispersion on fluid-liquid interfaces

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Particuology 2011年第1期9卷 1-13页

作者： Sathish Gurupatham Bhavin Dalal Md.Shahadat Hossain Ian S.Fischer Pushpendra Singh Daniel D.Joseph department of mechanical engineering New Jersey Institute of Technology department of aerospace engineering and Mechanics University of Minnesota department of mechanical and aerospace engineering University of California Irvine

This paper is concerned with the dispersion of particles on the fluid-liquid interface. In a previous study we have shown that when small particles, e.g., flour, pollen, glass beads, etc., contact an air-liquid interface, they disperse rapidly as if they were in an explosion. The rapid dispersion is due to the fact that the capillary force pulls particles into the interface causing them to accelerate to a large velocity. In this paper we show that motion of particles normal to the interface is inertia dominated; they oscillate vertically about their equilibrium position before coming to rest under viscous drag. This vertical motion of a particle causes a radially-outward lateral （secondary） flow on the interface that causes nearby particles to move away. The dispersion on a liquid-liquid interface, which is the primary focus of this study, was relatively weaker than on an air-liquid interface, and occurred over a longer period of time. When falling through an upper liquid the particles have a slower velocity than when falling through air because the liquid has a greater viscosity. Another difference for the liquid-liquid interface is that the separation of particles begins in the upper liquid before the particles reach the interface. The rate of dispersion depended on the size of the particles, the densities of the particle and liquids, the viscosities of the liquids involved, and the contact angle. For small particles, partial pinning and hysteresis of the three-phase contact line on the surface of the particle during adsorption on liquid-liquid interfaces was also important. The frequency of oscillation of particles about their floating equilibrium increased with decreasing particle size on both air-water and liquid-liquid interfaces, and the time to reach equilibrium decreased with decreasing particle size. These results are in agreement with our analysis.

关键词： Adsorption Interfacial tension Particle dispersion Fluid–liquid interface Capillary force Viscous drag

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Crafting chirality in three dimensions via a novel fabrication technique for bound states in the continuum metasurfaces

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Light(Science & Applications) 2024年第3期13卷 390-392页

作者： Zaid Haddadin Anna My Nguyen Lisa V.Poulikakos department of Electrical&Computer engineering University of California San DiegoLa JollaCAUSA department of mechanical&aerospace engineering University of California San DiegoLa JollaCAUSA Program of Materials Science&engineering University of California San DiegoLa JollaCAUSA

An additional deposition step was added to a multi-step electron beam lithographic fabrication process to unlock the height dimension as an accessible parameter for resonators comprising unit cells of quasi-bound stat... 详细信息

关键词： dimensions dimension intrinsic

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Prescribed-Time Control of Stochastic Nonlinear Systems with Reduced Control Effort

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Journal of Systems Science & Complexity 2021年第5期34卷 1782-1800页

作者： LI Wuquan KRSTIC Miroslav School of Mathematics and Statistics Science Ludong UniversityYantai 264025China department of mechanical and aerospace engineering University of CaliforniaSan DiegoLa JollaCA 92093USA

A new prescribed-time state-feedback design is presented for stochastic nonlinear strictfeedback *** from the existing stochastic prescribed-time design where scaling-free quartic Lyapunov functions or scaled quadratic Lyapunov functions are used,the design is based on new scaled quartic Lyapunov *** designed controller can ensure that the plant has an almost surely unique strong solution and the equilibrium at the origin of the plant is prescribed-time mean-square *** that,the authors redesign the controller to solve the prescribed-time inverse optimal mean-square stabilization *** merit of the design is that the order of the scaling function in the controller is reduced dramatically,which effectively reduces the control *** simulation examples are given to illustrate the designs.

关键词： Control effort prescribed-time design stochastic nonlinear strict-feedback systems

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Closed-loop subspace identification algorithm based on correlation function estimates

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Science China(Information Sciences) 2015年第3期58卷 173-182页

作者： WANG Jia MILLER Daniel WANG HongWei GU Hong department of Biotechnology Dalian Medical University School of Control Science and engineering Dalian University of Technology department of mechanical engineering University of California San Diego

A novel subspace identification method based on correlation function which estimates a state-space system dynamics of unknown plant operating in closed-loop experimental condition is proposed in this *** is shown that the cross-correlation function of the output and external input signals are equal to the crosscorrelation function of the input and external signals filtered through the system dynamics since noise signal has no correlation with the external *** proposed algorithm is developed to obtain unbiased estimates of system matrices based on time-shifted invariance of the correlation function *** the algorithm is compared to other popular subspace methods in the simulation study and the results show the effectiveness of our method in the presence of colored noise and low signal-to-noise ratios.

关键词： subspace identification method correlation function estimates closed-loop system asymptotic properties the system dynamics

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