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Observation of acoustic hybrid topological phases induced by the p-d orbital interactions

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 132-139页

作者： Xiao Xiang feng gao Yu-Gui Peng Peng Wu Zong-Lin Li Xue-feng Zhu School of Physics and Innovation Institute Huazhong University of Science and Technology

In spinless systems,growing attention has recently been attracted to synthetic gauge fields,which redefine the fundamental crystal symmetries by utilizing the projective algebraic ***,synthetic gauge fields have been commonly investigated in single orbital systems,and explorations on hybrid orbitals remain elusive in ***,we report the experimental observation of hybrid topological phases induced by hybrid synthetic gauge flux,which is formed by the interaction between p and d orbitals embedded in acoustic *** breaking the translation symmetries of Lxand/or Ly,we unambiguously demonstrate the first-order M?bius edge states and higher-order corner *** work establishes a platform for seeking exotic topological phases induced by hybrid-orbitals interactions and initializing the framework of hybrid-orbitalsrelated topological *** applications can be anticipated in scenarios such as high-quality sensing and robust wave trapping due to the stepwise energy distribution of the hybrid topological phase.

关键词： topological insulator synthetic gauge field projective symmetry corner states

Record-high efficiency perovskite LEDs achieved by accelerating radiative recombination

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Science China Materials 2024年第9期67卷 3039-3040页

作者： feng gao Department of Physics Chemistry and BiologyLinköping UniversityLinköping58183Sweden

Light-emitting diodes(LEDs)have revolutionized the lighting and displays due to their superior energy *** increasing demand for more efficient and brighter thin-film LEDs in flat-panel displays and solid-state lighting applications has driven extensive research into perovskite materials,which show great promise for high brightness and efficiency.

关键词： lighting radiative high

Effect of vacuum degree and aeration rate on sludge dewatering behavior with the aeration-vacuum method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第9期11卷 638-655页

作者： Yu-feng gao Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University Nanjing 210098 China Geotechnical Research Institute Hohai University Nanjing 210098 China The Science and Technology Division Hohai University Nanjing 210098 China

Due to large-scale dredging operations, a large amount of sludge is inevitably produced. Large areas of land are occupied when the dredged sludge is discarded in the disposal site as waste material. The sludge dewatering with aeration-vacuum (SDAV) method is suit for treating the sludge with high water content and high clay content in the disposal site. The water in the sludge can be discharged out. The volume of the sludge can be reduced quickly, and the recycling of the land can be accelerated by this method. Most importantly, this technique is an efficient way to deal with clogging problems when pumping water from high water content, high clay content dredged sludge. Vacuum degree range tests, the aeration rate range tests, and the influencing factors of sludge dewatering behavior tests were conducted with a self-developed SDAV model test device. Sludge samples were taken from the South-to-North Water Diversion East Line Project in Huai’an White-Horse Lake disposal site, Jiangsu Province, China. The optimal range of vacuum degree and aeration rate were obtained through the test results, and the mechanisms for how the two factors work and how they affect the sludge dewatering behavior were analyzed. The suitable vacuum degree range in SDAV is below 50 kPa, and the suitable aeration rate is about 1.0 m3/h. The low-vacuum degree contributes to reduce the ad-sorption effect of micro-channels on soil particles in filter material and to maintain the arch structures. Aeration has the effects of expansion, disturbance, changing Reynolds number, and dynamic sieve separating. The pump quantity of water per meter of filter tube (m) has different change rules as the vacuum degree changes under different aeration rates. The reason is that the formed arch structures’ conformation and permeability differ greatly under different combined-conditions of vacuum degree and aeration rate. The optimal combined-condition for dewatering the sludge is 35 kPa with 1.0 m3/h.

关键词： High water content dredged sludge Sludge dewatering with aeration-vacuum (SDAV) Vacuum degree Aeration rate Arch structures

Mechanism,Actuation,Perception,and Control of Highly Dynamic Multilegged Robots:A Review

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Chinese Journal of Mechanical Engineering 2020年第5期33卷 120-149页

作者： Jun He feng gao State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Multilegged robots have the potential to serve as assistants for humans,replacing them in performing dangerous,dull,or unclean ***,they are still far from being sufficiently versatile and robust for many *** paper addresses key points that might yield breakthroughs for highly dynamic multilegged robots with the abilities of running(or jumping and hopping)and ***,21 typical multilegged robots from the last five years are surveyed,and the most impressive performances of these robots are ***,current developments regarding key technologies of highly dynamic multilegged robots are reviewed in *** latest leg mechanisms with serial-parallel hybrid topologies and rigid–flexible coupling configurations are ***,the development trends of three typical actuators,namely hydraulic,quasi-direct drive,and serial elastic actuators,are *** that,the sensors and modeling methods used for perception are ***,this paper pays special attention to the review of control approaches since control is a great challenge for highly dynamic multilegged *** dynamics-based control methods and two model-free control methods are described in ***,key open topics of future research concerning the mechanism,actuation,perception,and control of highly dynamic multilegged robots are *** paper reviews the state of the art development for multilegged robots,and discusses the future trend of multilegged robots.

关键词： Multilegged robot Mechanism Actuation Perception Control

FEM Analysis on Acoustic Performance of Wall Flow Diesel Particulate Filters

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 701-706页

作者： gao Wenzhi feng Liming State Key Laboratory of Engines Tianjin University Tianjin 300072 China

Diesel powered vehicles, in compliance with the more strict exhaust emission standards such as Euro V, is likely to require a diesel particulate filter （DPF）. A DPF used on a vehicle will affect the acoustic emission of the diesel engine, so it is important to investigate the sound propagation rule in DPF and further to propose the optimum DPF design. However, due to the geometrical complexity of the DPF, the traditional analysis method, such as analytical method, can not assess the acoustic performance of DPF accurately in medium and high frequency band. In this paper, a combined approach of finite element analysis and viscosity correction is proposed to predict acoustic performance of DPF. A simplified model of the full DPF is established and is used to analyze the sound propagation characteristic of the DPF. The distribution of the sound pressure and velocity, the transmission matrix of the DPF are obtained using the finite element method. In addition, the method of the viscosity correction is used in the transmission matrix of the DPF to evaluate the acoustic performance of DPF. Based on the FEM computation and the viscosity correction, the transmission losses under the rated load and idle condition of a diesel engine are calculated. The calculation results show that DPF can effectively attenuate exhaust noise, and sound attenuation increase with the rise of the frequency. Sound attenuation is better under rated condition than idle condition of diesel engine, particularly in frequency above 1 000 Hz.

关键词： diesel particulate filter acoustic performance FEM model viscosity correction

A closure model on velocity structure functions in homogeneous isotropic turbulence

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Applied Mathematics and Mechanics(English Edition) 2017年第11期38卷 1627-1634页

作者： Le FANG feng gao Laboratory of Mathematics and Physics Ecole Centrale de Pekin Beihang University Beijing 100191 China Co-Innovation Center for Advanced Aero-Engine Beihang University Beijing 100191 China Faculty of Engineering and Physical Sciences University of Surrey Guildford GU2 7XH U. K.

Closure models started from Chou＇s work have been developed for more than 70 years, aiming at providing analytical tools to describe turbulent flows in the spectral space. In this study, a preliminary attempt is presented to introduce a closure model in the physical space, using the velocity structure functions as key parameters. The present closure model appears to qualitatively reproduce the asymptotic scaling behav- iors at small and large scales, despite some inappropriate behaviors such as oscillations. Therefore, further improvements of the present model are expected to provide appropriate descriptions of turbulent flows in the physical space.

关键词： homogeneous isotropic turbulence closure model structure function

Type Synthesis of Walking Robot Legs

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Chinese Journal of Mechanical Engineering 2018年第1期31卷 53-65页

作者： Da Xi feng gao State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University

Walking robots use leg structures to overcome obstacles or move on complicated terrains. Most robots of current researches are equipped with legs of simple structure. The specific design method of walking robot legs is seldom studied. Based on the generalized-function(GF) set theory, a systematic type synthesis process of designing robot legs is introduced. The specific mobility of robot legs is analyzed to obtain two main leg types as the goal of *** synthesis problem is decomposed into two stages, actuation and constraint synthesis by name,corresponding to the combinatorics results of linear Diophantine equations. Additional restrictions are discussed to narrow the search range to propose practical limb expressions and kinematic-pair designs. Finally, all the fifty-one leg structures of four subtypes are carried out, some of which are chosen to make up robot prototypes, demonstrating the validity of the method. This paper proposed a novel type synthesis methodology, which could be used to systematically design various practical robot legs and the derived robots.

关键词： Type synthesis Robot leg GF set Number synthesis Linear Diophantine equation

Design of a Servo Mechanical Press with Redundant Actuation

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Chinese Journal of Mechanical Engineering 2009年第4期22卷 574-579页

作者： GUO Weizhong gao feng State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai 200240 China

A servo press is a new type of mechanical press that is driven by programmable motors and offers superior performance such as low noise, excellent efficiency and high precision for metal forming operations. Similar to multi-link mechanical presses, a servo mechanical press tends to grow in size as the tonnage increases that calls for larger, heavy duty servo motors, which could be expensive and may not even be available. In this paper, a new concept of servo mechanical press with redundant actuation is proposed firstly using two servo motors driving one input shaft, i.e. one-point-two-motor mode that makes it possible to produce a larger press with available servomotors. Then the punching mechanism design is detailed. The performance indices are set up including mechanical advantage reciprocal and link force ratios. A bounded feasible solution space is constructed for dimensional synthesis based on non-dimensional link lengths and assembly conditions. The performance atlases are depicted over the bounded feasible solution space that lead to a visual solution of the punching mechanism with global optimization. Finally, case studies are given to illustrate the design method with visual global optimization, and a prototype with 200 t punching force is being developed in our laboratory to demonstrate efficacy of the new concept for servo mechanical press. The presented research provides a feasible solution to the development of heavy-duty servo mechanical presses and finds potential applications in the development of other types of heavy equipments with electric drive.

关键词： servo mechanical press redundant actuation mechanism design visual global optimization prototype

Type Design for Heavy-payload Forging Manipulators

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Chinese Journal of Mechanical Engineering 2012年第2期25卷 197-205页

作者： GE Hao gao feng State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China

Heavy-payload forging manipulators are mainly characterized by large load output and large capacitive-load *** relationship between outputs and inputs,which will greatly influence the control and the reliability,is the key issue in type design for heavy-payload forging *** this paper,a type design method by considering the incidence relationship between output characteristics and actuator inputs is presented and used to design the mechanism for forging *** concept of modeling method based on the outputs tasks is defined and *** principle of type design from the viewpoints of the relationship between output characteristics and actuator inputs is *** idea of establishing the incidence relationship between output characteristics and actuator inputs is *** incidence relationship matrix between outputs and inputs is also *** design flow is obtained,and the incidence relationship between outputs and inputs for heavy-payload forging manipulators is divided into three parts after detailed understanding of the functional *** types of mechanisms for heavy-payload forging manipulators are given,and the corresponding spatial mechanical sketches are also drawn,some new designed mechanisms have been adopted by company or used as *** novel forging manipulators which satisfy certain functional requirements provide an effective help for the design of forging manipulators and patent application.

关键词： heavy-payload type design forging manipulators kinematic characteristics