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Topological pseudospin switcher:Mechanism and acoustic realization

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 46-53页

作者： Jia-He Chen Yiyin Chen Yaoqieyu Song Yongxu Xu Xinrong Li Jingsong Wang Jiawei He Jiaxu Qu Zheng Li Xiaofei Li Wenqiang Lin Jiannan Chen Caixing Fu Zhi Hong Hang School of Physical Science and Technology&Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow UniversitySuzhou 215006China Institute for Advanced Study Soochow UniversitySuzhou 215006China Provincial Key Lab of Thin Films Soochow UniversitySuzhou 215006China

The control of the pseudospin of sound wave has attracted increasing attention in recent years.Utilizing the finite-size effect of topological acoustics,we successfully construct an H-shaped acoustic topological pseudospin switcher that sound wave energy can be easily switched through different passages.The interesting phenomenon of pseudospin flipping is numerically and experimentally demonstrated.A quantitative interference theory is proposed that the constructive and destructive interference of pseudospin states leads to pseudospin flipping and preserving in multiple frequencies.We verify the key parameters of the design,including the length of the passage and its interface state dispersion,and the theory can be extended to other topology acoustics and photonics systems.Moreover,the tunable topological sonic crystal we use provides adjustable convenience to pseudospin switcher design.The pseudospin switching behavior offers an efficient method to control the acoustic topological edge state transport,which has great potential in versatile applications,such as integrated acoustics,acoustic security,and information processing.

关键词： topological acoustics realization

Method for passivation of propellant residues in orbital stage tank of launch vehicle

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Chinese Journal of Aeronautics 2024年第1期37卷 64-76页

作者： Valeriy TRUSHLYAKOV Ivan LESNYAK Alexey PANICHKIN Department of Aviation and Rocket Building Omsk State Technical UniversityOmsk 644050Russia Sobolev Institute of Mathematics of the Siberian Branch of Russian Academy of Sciences Novosibirsk 630090Russia

The problem of removing unused liquid propellant residues from the tanks of spent spacecraft and orbital stages of Launch Vehicles(LV)leads to their explosion and the formation of space debris in orbits.To provide a solution to this problem,a method for removing liquid propellant residues from the LV tanks after the mission completion is proposed.The method is based on the gasification of liquid propellant residues in the tanks under acoustic-vacuum exposure and the discharge of the gasification products into the surrounding outer space.Experimental investigations were carried out on a Ground-based Experimental Installation(GEI)to determine the coefficient of heat transfer from the surface of an acoustic radiator to a liquid.The obtained coefficient was then used to calculate the energy costs for the gasification of kerosene.Numerical estimates are given on the example of the tank with kerosene residues from a spent second stage of the LV“Soyuz-2.1 v”.The optimal discharge rate at which kerosene does not freeze is 0.14 m^(3)/s.Moreover,the acoustic exposure leads to an increase in the mass of evaporated kerosene over a given time by96.1%,and the energy costs are 1756.7 kJ(approximately 50% of the remaining electrical energy).

关键词： Propellant Weightlessness Liquid evaporation Heat and mass transfer acoustics Vacuum Vapor bubbles

Acoustical properties of a 3D printed honeycomb structure filled with nanofillers:Experimental analysis and optimization for emerging applications

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Defence Technology（防务技术） 2024年第5期35卷 248-258页

作者： Jeyanthi Subramanian Vinoth kumar Selvaraj Rohan Singh Ilangovan S Naresh Kakur Ruban Whenish School of Mechanical Engineering Vellore Institute of TechnologyChennai600127Tamil NaduIndia Department of Mechanical Engineering SRM Institute of Science and TechnologyRamapuramChennai600089India Department of Chemical Engineering and Materials Science University of Southern CaliforniaLos Angeles90089USA Advanced Materials Research Centre Technology Innovation InstituteAbu Dhabi9639UAE Center for Biomaterials Cellular and Molecular TheranosticsVellore Institute of TechnologyVellore632014Tamil NaduIndia

The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E 1050-12.The Creality Ender-3,a 3D printer,was used for printing the honeycomb structures,and polylactic acid(PLA)material was employed for their construction.The organic,inorganic,and polymeric compounds within the composites were identified using fourier transformation infrared(FTIR)spectroscopy.The structure and homogeneity of the samples were examined using a field emission scanning electron microscope(FESEM).To determine the sound absorption coefficient of the 3D printed honeycomb structure,numerous samples were systematically developed using central composite design(CCD)and analysed using response surface methodology(RSM).The RSM mathematical model was established to predict the optimum values of each factor and noise reduction coefficient(NRC).The optimum values for an NRC of 0.377 were found to be 1.116 wt% carbon black,1.025 wt% aluminium powder,and 3.151 mm distance between parallel edges.Overall,the results demonstrate that a 3Dprinted honeycomb structure filled with nanofillers is an excellent material that can be utilized in various fields,including defence and aviation,where lightweight and acoustic properties are of great importance.

关键词： 3D printing Honeycomb structure acoustics Field emission scanning electron microscope Response surface methodology

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A primary study of the acoustics of Chinese traditional theatrical buildings

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声学技术 2003年第Z1期22卷 2-5页

作者： WANG Jiqing (Institute of acoustics, Tongji University, Shanghai 200092, China ) Institute of acoustics Tongji University Shanghai 200092 China

The traditional performing arts and theatrical buildings in China can be traced back to a long history and were well developed during Song and Yuan Dynasties, 11th-14th centuries. Pavilion stage, opened on three sides and thrusting into the audience area, was unique and the most popular form in the open-air theatres, the courtyard theatres, and the indoor theatres up to the present day. As the traditional Chinese opera is performed in an abstract way, no stage settings are required and used. Therefore, the pavilion stage including the flat or domed ceiling and the back wall is virtually functioned as a reflective shell, which increases the early reflections and also intensifies the sound in the audience area. Meanwhile, it provides sufficient self-support to the performers. Acoustical parameters including reverberation time RT, early decay time EDT, acoustic ratio C （50）, strength index （loudness） G, and stage support factor ST1 were measured and reported on several traditional theatrical buildings.

关键词： auditorium acoustics, theatrical building, acoustics of traditional performance

Introduction of ACTA ACUSTICA and Chinese Journal of acoustics

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Chinese Journal of acoustics 2024年第2期43卷 274-274页

ACTA ACUSTICA(声学学报, in Chinese) and Chinese Journal of acoustics(in English) are the publications of the Institute of acoustics, Chinese Academy of Sciences,edited by the Acoustical Society of China and the Editorial Board of Chinese Journal of acoustics, to publish original works in all branches of acoustics, and to promote the international understanding and collaboration in the field of acoustics.

关键词：声学学报 acoustics acoustics

Introduction of ACTA ACUSTICA and Chinese Journal of acoustics

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Chinese Journal of acoustics 2024年第1期43卷 132-132页

ACTA ACUSTICA (声学学报,in Chinese) and Chinese Journal of acoustics(in English) are the publications of the Institute of acoustics,Chinese Academy of Sciences,edited by the Acoustical Society of China and the Editorial Board of Chinese Journal of acoustics,to publish original works in all branches of acoustics,and to promote the international understanding and collaboration in the field of acoustics.

关键词：声学学报 acoustics acoustics

The measuring method of early lateral energy fraction in the scale model experiments

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声学技术 2004年第S1期23卷 49-52页

作者： NI Qiyu~1, FANG Yuan~2, WU Qixue~2, SUN Guangrong~2 (1. Yangzhou University, Yangzhou 225002, China 2. Institute of acoustics, Nanjing University, Nanjing 210093,China) Yangzhou University Yangzhou 225002 China Institute of acoustics Nanjing University Nanjing 210093China

This paper introduces a measuring method of early lateral energy fraction in the scale model experiments. According to the interference principle of half wave length making the high frequency figure-8 directional microphone. With the signal-processing technique, a receiving and analyzing system, for the measurements of lateral energy fraction in the scale model is realized.

关键词： room acoustics scale model experiment early lateral reflective sound

Characteristics of the internal waves and their effects on the sound transmission in the Midst of the Yellow Sea

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Chinese Journal of acoustics 1999年第1期18卷 47-55页

作者： YAN Jin ZHANG Renhe ZHOU Shihong SHA Liewei (National Laboratory of acoustics, Chinese Academy of Sciences Beijing 100080)

In the late summer of 1996, a combined acoustics and physical oceanography experiment (YS96) was performed in the midst of the Yellow Sea. Here the oceanographic data are analyzed and the internal wave spectrum is constructed. It shows that the internal wavesare dominated by the first modes and the spectral density is approximately proportional to w-s/z. Based on the internal wave spectrum, a model of the induced sound-speed distribution is developed, and computer simulation is conducted for CW signal propagation by using the PE method. Numerical results of the sound intensity fluctuations are preseflted for comparison with the experimental data.

关键词： Yellow shallow ocean acoustics Cambridge Naval Polar dynamical Proceedings perturbations

Thermodynamics-acoustics Coupling Studies on Self-Excited Combustion Oscillations Maximum Growth Rate

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Journal of Thermal Science 2022年第5期31卷 1591-1603页

作者： ZHAO Dan Department of Mechanical Engineering College of EngineeringUniversity of CanterburyPrivate Bag 4800Christchurch8041New Zealand

Unlike electric vehicles and electric aircrafts,hydrocarbon-fuelled(fossil)engine systems are much noisier.By conducting one-step chemical reaction-thermodynamics-acoustics coupling studies and experimental measurements,we explore the universal physics of how hydrocarbon-fuelled combustion is a noise maker.We also explain that how combustion-sustained noise at a particular frequencyωis intrinsically selected.These frequencies correspond to the acoustic resonance nature of the combustor.We find that a reacting gas in which the rate of chemical reacting increases with temperature is intrinsically and naturally unstable with respect to acoustic wave motion,since its modal growth rateαis greater than 0.Acoustic disturbances tend to exponentially i.***.exp(αt)increase first and then are limited by nonlinear effects and finally grow into limit cycle oscillations.The growth rateαis found to increase first and then decrease with the gradient of the heat release rate with respect to the temperature change,i.***.heat capacity.The maximum(α/ω)_(max)depends on the specific heat ratioγ,which is related to the speed of sound.The unstable nature could be changed by introducing some acoustic dissipative/damping mechanisms,such as the boundary layer viscous drag and boundary losses.It is shown that such losses could lead to increased critical heat capacity,below which stable combustors can be designed.Finally,the acoustical energy consisting of both potential and kinetic energy is found to grow exponentially faster by 100%than the acoustic disturbance amplitude.

关键词： thermodynamics acoustics hydrocarbon chemical reaction energy conversion thermo-acoustics