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Decoupling of temporal/spatial broadening effects in Doppler wind LiDAR by 2D spectral analysis

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Chinese Physics B 2024年第3期33卷 447-452页

作者：刘珍张云鹏竹孝鹏刘继桥毕德仓陈卫标 Space Laser Engineering department Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Pulse echo accumulation is commonly employed in coherent Doppler wind LiDAR(light detection and ranging)under the assumption of steady ***,the measured spectral data are analyzed in the time dimension and frequency dimension to cope with the temporal wind shear and achieve the optimal accumulation time.A hardware-efficient algorithm combining the interpolation and cross-correlation is used to enhance the wind retrieval accuracy by reducing the frequency sampling interval and then reduce the spectral width calculation ***,the temporal broadening effect and spatial broadening effect are decoupled according to the strategy we developed.

关键词： Doppler wind LiDAR spectral analysis hardware efficiency spectrum broadening effects

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Multi-Material magnetic field-assisted additive manufacturing system for flexible actuators with programmable magnetic arrangements

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Frontiers of Mechanical Engineering 2024年第2期19卷 109-120页

作者： Yujie HUANG Haonan SUN Chengqian ZHANG Ruoxiang GAO Hongyao SHEN Peng ZHAO The State Key Laboratory of Fluid Power and Mechatronic Systems College of Mechanical EngineeringZhejiang UniversityHangzhou 310027China The Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province College of Mechanical EngineeringZhejiang UniversityHangzhou 310027China Center for X-mechanics Department of Engineering MechanicsZhejiang UniversityHangzhou 310027China

Manufacturing flexible magnetic-driven actuators with complex structures and magnetic arrangements to achieve diverse functionalities is becoming a popular *** various manufacturing technologies,magnetic-assisted digital light processing(DLP)stands out because it enables precise manufacturing of macro-scale structures and micro-scale distributions with the assistance of an external magnetic *** research on manufacturing magnetic flexible actuators mostly employs single materials,which limits the magnetic driving performance to some *** on these characterizations,we propose a multi-material magnetic field-assisted DLP technology to produce flexible actuators with an accuracy of 200μ*** flexible actuators are printed using two materials with different mechanical and magnetic *** the interface connectivity of multi-material printing,the effect of interfaces on mechanical properties is also *** results indicate good chemical affinity between the two materials we *** overlap or connection length of the interface moderately improves the tensile strength of multi-material *** addition,we investigate the influence of the volume fraction of the magnetic part on *** and experimental results indicate that increasing the volume ratio(20%to 50%)of the magnetic structure can enhance the responsiveness of the actuator(more than 50%).Finally,we successfully manufacture two multi-material flexible actuators with specific magnetic arrangements:a multi-legged crawling robot and a flexible gripper capable of crawling and grasping *** results confirm that this method will pave the way for further research on the precise fabrication of magnetic flexible actuators with diverse functionalities.

关键词： multi-material magnetic field-assisted manufacturing digital light processing flexible actuators magnetic arrangement

Nanofluidic memristor based on the elastic deformation of nanopores with nanoparticle adsorption

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National Science Review 2024年第04期11卷 46-54页

作者： Xi Zhou Yuanyuan Zong Yongchang Wang Miao Sun Deli Shi Wei Wang Guanghua Du Yanbo Xie department of Chemistry and Chemical Engineering Northwestern Polytechnical University School of Physical Science and Technology Northwestern Polytechnical University School of Aeronautics and Institute of Extreme mechanics Northwestern Polytechnical University Institute of Modern Physics Chinese Academy of Sciences

The memristor is the building block of neuromorphic computing. We report a new type of nanofluidic memristor based on the principle of elastic strain on polymer nanopores. With nanoparticles absorbed at the wall of a single conical polymer nanopore, we find a pinched hysteresis of the current within a scanning frequency range of 0.01–0.1 Hz, switching to a diode below 0.01 Hz and a resistor above 0.1 Hz. We attribute the current hysteresis to the elastic strain at the tip side of the nanopore, caused by electrical force on the particles adsorbed at the inner wall surface. Our simulation and analytical equations match well with experimental results, with a phase diagram for predicting the system transitions. We demonstrate the plasticity of our nanofluidic memristor to be similar to a biological synapse. Our findings pave a new way for ionic neuromorphic computing using nanofluidic memristors.

关键词： nanofluidics memristor neurocomputing elastic deformation

Nonlinear Filtering With Sample-Based Approximation Under Constrained Communication:Progress, Insights and Trends

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IEEE/CAA Journal of Automatica Sinica 2024年第07期11卷 1539-1556页

作者： Weihao Song Zidong Wang Zhongkui Li Jianan Wang Qing-Long Han IEEE the State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering ScienceCollege of Engineering Peking University the department of Computer Science Brunel University London the School of Aerospace Engineering Beijing Institute of Technology the School of Science Computing and Engineering Technologies Swinburne University of Technology

The nonlinear filtering problem has enduringly been an active research topic in both academia and industry due to its ever-growing theoretical importance and practical *** main objective of nonlinear filtering is to infer the states of a nonlinear dynamical system of interest based on the available noisy measurements. In recent years, the advance of network communication technology has not only popularized the networked systems with apparent advantages in terms of installation,cost and maintenance, but also brought about a series of challenges to the design of nonlinear filtering algorithms, among which the communication constraint has been recognized as a dominating concern. In this context, a great number of investigations have been launched towards the networked nonlinear filtering problem with communication constraints, and many samplebased nonlinear filters have been developed to deal with the highly nonlinear and/or non-Gaussian scenarios. The aim of this paper is to provide a timely survey about the recent advances on the sample-based networked nonlinear filtering problem from the perspective of communication constraints. More specifically, we first review three important families of sample-based filtering methods known as the unscented Kalman filter, particle filter,and maximum correntropy filter. Then, the latest developments are surveyed with stress on the topics regarding incomplete/imperfect information, limited resources and cyber ***, several challenges and open problems are highlighted to shed some lights on the possible trends of future research in this realm.

关键词： Communication constraints maximum correntropy filter networked nonlinear filtering particle filter sample-based approximation unscented Kalman filter

Cell mechanics Regulates the Dynamic Anisotropic Remodeling of Fibril Matrix at Large Scale

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Research 2024年第3期2023卷 401-415页

作者： Mingxing Ouyang Yanling Hu Weihui Chen Hui Li Yingbo Ji Linshuo Qiu Linlin Zhu Baohua Ji Bing Bu Linhong Deng Institute of Biomedical Engineering and Health Sciences School of Medical and Health Engineering and School of PharmacyChangzhou UniversityChangzhou213164China Institute of Biomechanics and Applications Department of Engineering MechanicsZhejang UniversityHangzhou310027China.

Living tissues often have anisotropic and heterogeneous organizations, in which developmental processes are coordinated by cells and extracellular matrix modeling. Cells have the capability of modeling matrix in long distance;however, the biophysical mechanism is largely unknown. We investigated the dynamic remodeling of collagen I (COL) fibril matrix by cell contraction with designed patterns of cell clusters. By considering cell dynamic contractions, our molecular dynamics simulations predicted the anisotropic patterns of the observed COL bundling in experiments with various geometrical patterns without spatial limitation. The pattern of COL bundling was closely related to the dynamic remodeling of fibril under cell active contraction. We showed that cell cytoskeletal integrity (actin filaments and microtubules), actomyosin contractions, and endoplasmic reticulum calcium channels acting as force generations and transductions were essential for fiber bundling inductions, and membrane mechanosensory components integrin and Piezo played critical roles as well. This study revealed the underlying mechanisms of the cell mechanics-induced matrix remodeling in large scales and the associated cellular mechanism and should provide important guidelines for tissue engineering in potential biomedical applications.

关键词： contraction Dynamic Matrix

A Comprehensive Study of a Low-Grade Heat-Driven Cooling and Power System Based on Heat Current Method

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Journal of Thermal Science 2024年第4期33卷 1523-1541页

作者： ZHAO Tian XU Ronghong XIN Yonglin HE Kelun MA Huan YUAN Mengdi CHEN Qun School of Energy Storage Science and Engineering North China University of TechnologyBeijing100144China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing100084China

Combined cooling and power(CCP)system driven by low-grade heat is promising for improving energy *** work proposes a CCP system that integrates a regenerative organic Rankine cycle(RORC)and an absorption chiller on both driving and cooling fluid *** system is modeled by using the heat current method to fully consider nonlinear heat transfer and heat-work conversion constraints and resolve its behavior *** off-design system simulation is performed next,showing that the fluid inlet temperatures and flow rates of cooling water as well as RORC working fluid strongly affect system *** off-design operation even becomes infeasible when parameters deviate from nominal values largely due to limited heat transfer capability of components,highlighting the importance of considering heat transfer constraints via heat current *** optimization aiming to minimize the total thermal conductance is also *** efficiency increases by 7.9%and decreases by 12.4%after optimization,with the hot fluid inlet temperature increase from 373.15 to 403.15 K and mass flow rate ranges from 10 to 30 kg/s,emphasizing the necessity of balancing system cost and performance.

关键词： combined cooling and power system organic Rankine cycle absorption chiller cascade heat utilization heat current method off-design analysis

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Zero-Sum Continuous-Time Markov Games with One-Side Stopping

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Journal of the Operations Research Society of China 2024年第1期12卷 169-187页

作者： Yurii Averboukh Laboratory of Stochastic Analysis and Its Applications National Research University Higher School of Economics(HSE)Moscow109028Russia department of Differential Equations Krasovskii Institute of Mathematics and MechanicsYekaterinburg620108Russia

The paper is concerned with a variant of the continuous-time finite state Markov game of control and stopping where both players can affect transition rates,while only one player can choose a stopping *** dynamic programming principle reduces this problem to a system of ODEs with unilateral *** system plays the role of the Bellman *** show that its solution provides the optimal strategies of the ***,the existence and uniqueness theorem for the deduced system of ODEs with unilateral constraints is derived.

关键词： Continuous-time Markov games Dynamic programming Verification theorem Stopping time

Investigation on the influence of vortex generator on particle resuspension

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Particuology 2024年第3期86卷 126-136页

作者： Dongchi Yu Jun-Li Lin Jin-Han Xie ASML 80W Tasman DrSan Jose95134CaliforniaUSA department of mechanics and Engineering Science at College of Engineering and State Key Laboratory for Turbulence and Complex Systems Peking UniversityBeijing100081China

The vortex generator(VG)and its well-known effect in flow optimization are widely studied and employed across different engineering ***,while the same working principles of VG may be well suited for the applications on surface-cleaning technologies,such promising potential is hardly,if any,explored in the published ***,in the present study,the influence on flow-induced particle resuspension brought by a rectangular vG in a channel flow is investigated with the help of highfidelity computational fluid dynamics *** increases of particle removal forces and resuspension rates are discovered in long,strip-like regions with reduced boundary-layer thickness resulted from the vG-induced vortices,and the enhancement effect is especially significant for configurations with the VG installed at a greater angle of *** is also shown that while the resuspension enhancements on the lower and the upper surfaces of the channel exhibit distinct statistical characteristics,having a VG in the channel improves the overall particle-removing capability of the channel flow by introducing higher surface-averaged removal forces and particle resuspension *** but not least,the increase of resuspension rate is especially significant for the smaller,micron-scale particles which are otherwise hardly disturbed by a VG-less channel flow,and such resuspension-enhancement effectgenerally subsides with increasing particle size.

关键词： Particle resuspension Vortexgenerator CFD Surface cleaning

Enriched Constant Elements in the Boundary Element Method for Solving 2D Acoustic Problems at Higher Frequencies

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Computer Modeling in Engineering & Sciences 2024年第3期138卷 2159-2175页

作者： Zonglin Li Zhenyu Gao Yijun Liu School of Astronautics Harbin Institute of TechnologyHarbin150001China department of mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhen518055China

The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at ***,BEM models must meet the requirement of 6–10 elements per wavelength,using the conventional constant,linear,or quadratic ***,a large storage size of memory and long solution time are often needed in solving higher-frequency *** this work,we propose two new types of enriched elements based on conventional constant boundary elements to improve the computational efficiency of the 2D acoustic *** first one uses a plane wave expansion,which can be used to model scattering *** second one uses a special plane wave expansion,which can be used tomodel radiation *** examples are investigated to showthe advantages of the enriched *** with the conventional constant elements,the new enriched elements can deliver results with the same accuracy and in less computational *** improvement in the computational efficiency is more evident at higher frequencies(with the nondimensional wave numbers exceeding 100).The paper concludes with the potential of our proposed enriched elements and plans for their further improvement.

关键词： Enriched boundary elements constant elements 2D acoustic problems higher frequency