An infinite panel model of giant magnetostrictive material loudspeaker system （GMMLS） is proposed by making use of finite element method（FEM）. Bending wave eigenfunction is introduced to describe the acoustic radi...An infinite panel model of giant magnetostrictive material loudspeaker system （GMMLS） is proposed by making use of finite element method（FEM）. Bending wave eigenfunction is introduced to describe the acoustic radiation condition of the panel. Far-field response in different conditions is calculated by changing the mass surface density. Conclusion is obtained by analyzing the curves simulated, that panel which has larger mass surface density can hardly generate far-field acoustic radiation for lower frequency, while the panel has smaller mass surface density generates far-field acoustic radiation for lower frequency evenly and stronger.展开更多
An audiobeam loudspeaker system based on the fixed-point digital signal processor(DSP)TMS320VC5509A(VC5509A for short)is developed to emit audible sound with high directivity along a selected path.This system is compo...An audiobeam loudspeaker system based on the fixed-point digital signal processor(DSP)TMS320VC5509A(VC5509A for short)is developed to emit audible sound with high directivity along a selected path.This system is composed of preamplifier,anti-aliasing filter,ADC(analog to digital converter),VC5509A basic system,DAC(digital to analog converter),smoothing filter,ultrasonic power amplifier and ultrasonic transducer array.VC5509A is used to implement the key signal preprocessing algorithms,such as signal preprocessing,amplitude modulation,carrier signal generator,etc.The experiments show that this system has the advantages of high accuracy and good stability.展开更多
In the conventional analogous circuit theory of the loudspeaker system, the vibrating air in box is considered as lumped parameter; in this paper we consider the air as distributed parameter. The sound field theory an...In the conventional analogous circuit theory of the loudspeaker system, the vibrating air in box is considered as lumped parameter; in this paper we consider the air as distributed parameter. The sound field theory and the analogous circuit theory are combined to analyze the characteristics of the loudspeaker system such as radiation acoustic power, frequency response and impedance response.展开更多
The meteorological early-warning loudspeaker is a specific initiative for the meteorological departments to address the issues concerning issues concerning agriculture,countryside and farmers.Its significance is that ...The meteorological early-warning loudspeaker is a specific initiative for the meteorological departments to address the issues concerning issues concerning agriculture,countryside and farmers.Its significance is that it can promptly deliver the early-warning information concerning some meteorological disasters(such as torrential rains,typhoons,cold wave,hail)to the areas affected,so as to provide reference and protection for agricultural production and effectively reduce the loss of agricultural producers.Up to now,the meteorological early-warning loudspeakers in Benxi have covered the villages.However,due to irregular occurrence of meteorological disasters,the listeners will turn off the information receivers of meteorological early-warning loudspeakers when they fail to receive meteorological information for a long time,so that the users can not promptly know the early-warning information regarding some sudden meteorological disasters.In view of this,the meteorological departments have introduced a series of management measures,such as the daily use of loudspeakers to publish weather forecast information,aimed at improving the online rate and usage rate of meteorological loudspeakers.And the management platform for online rate of meteorological early-warning loudspeakers is an important part of the management system.展开更多
An overview of the research conducted in the area of linear and nonlinear vibrations of loudspeakers and revolution shells was given in the turning-point frequency range in Chapter 1. It shows that some problems conce...An overview of the research conducted in the area of linear and nonlinear vibrations of loudspeakers and revolution shells was given in the turning-point frequency range in Chapter 1. It shows that some problems concerning vibrations of shells in the turning-point range have to be further studied. The linear vibrations of truncated revolution shells with the first-order turningpoint were systematically investigated in the turningpoint range from Chapter 2 to Chapter 6, including the general solutions for the free vibration, the eigenvalues under various boundary conditions, the forced vibrations driven by an edge force or an edge displacement and some related special effects, and the applications in loudspeaker vibrations. The nonlinear autoparametric vibration was examined in Chapter 7. Main results are listed as follows.展开更多
The exciter component in a panel loudspeaker has a profound effect on the overall performance of the system. The equivalent circuit analysis of the combination of giant magnetostrictive material exciter and distribute...The exciter component in a panel loudspeaker has a profound effect on the overall performance of the system. The equivalent circuit analysis of the combination of giant magnetostrictive material exciter and distributed mode panel is introduced and how exciter parameters influence panel lo＇udspeaker＇ s performance is discussed. Numerical predictions are given in order to show how these influences are manifested.展开更多
Ambisonics is a series of flexible spatial sound reproduction systems based on spatial harmonics decomposition of sound field.Traditional horizontal and spatial Ambisonics reconstruct horizontal and spatial sound fiel...Ambisonics is a series of flexible spatial sound reproduction systems based on spatial harmonics decomposition of sound field.Traditional horizontal and spatial Ambisonics reconstruct horizontal and spatial sound field with certain order of spatial harmonics,respectively.Both the Shannon-Nyquist spatial sampling frequency limit for accurately reconstructing sound field and the complexity of system increase with the increasing order of Ambisonics.Based on the fact that the horizontal localization resolution of human hearing is higher than vertical resolution,mixed-order Ambisonics(MOA)reconstructs horizontal sound field with higher order spatial harmonics,while reconstructs vertical sound field with lower order spatial harmonics,and thereby reaches a compromise between the perceptual performance and the complexity of system.For a given order horizontal Ambisoncis or MOA reproduction,the number of horizontal loudspeakers is flexible,providing that it exceeds some low limit.By using Moore’s revised loudness model,the present work analyzes the influence of the number of horizontal loudspeakers on timbre both in horizontal Ambisonics and MOA reproduction.The binaural loudness level spectra(BLLS)of Ambisoncis reproduction are calculated and then compared with those of target sound field.The results indicate that below the Shannon-Nyquist limit of spatial sampling,increasing the number of horizontal loudspeakers influence little on BLLS then timbre.Above the limit,however,the BLLS for Ambisoncis reproduction deviate from those of target sound field.The extent of deviation depends on both the direction of target sound field and the number of loudspeakers.Increasing the number of horizontal loudspeakers may increase the change of BLLS then timbre in some cases,but reduce the change in some other cases.For MOA,the influence of the number of horizontal loudspeakers on BLLS and timbre reduces when virtual source departs from horizontal plane to the high or low elevation.The subjective evaluation experiment also validates the analysis.展开更多
A hemispherical array of 196 independent loudspeakers has been constructed for laboratory research on spatial hearing, auralization, sound-field quality and spatial audio signal processing. The array of small loudspea...A hemispherical array of 196 independent loudspeakers has been constructed for laboratory research on spatial hearing, auralization, sound-field quality and spatial audio signal processing. The array of small loudspeakers is supported by a geodesic frame with a radius is 2.4 m. With this relatively high spatial density of sound sources, spatially quantized rendering of sound fields should be viable for a variety of applications, and this paper considers the potential and limits of this approach in relation to human spatial hearing capacities. The paper also considers the combined use of multiple loudspeakers for the rendering low-frequency components of sound sources in order to extend the low-frequency response of the system.展开更多
The loudspeakers played a crucial role in rural community during the COVID-19 pandemic,and had returned to the public with the help of short video platforms.However,with the continued popularity of digital media,is th...The loudspeakers played a crucial role in rural community during the COVID-19 pandemic,and had returned to the public with the help of short video platforms.However,with the continued popularity of digital media,is the revival of the loudspeakers which belong to traditional media just a flash in the pan?What the historic process of return has the loudspeakers undergone?Based on these questions,the paper applies Bourdieu’s sense of practice theory,focuses on“habit”throughout,adopts the research methods of online ethnography and fieldwork,and conducts participant observation and targeted in-depth interviews in a village in North China for about nine months.The study found that:(1)There is the lag of habit in the state’s handling of social relations in villages.Based on rational habit,village cadres used the loudspeakers to manifest their physical presence and restructure their authority;the villagers,operating under perceptual habit,rationalized the presence of the loudspeakers through using the key words such as elders,nostalgia,and homesickness;(2)the loudspeakers was maintained under the habit of village cadres and ordinary villagers,and the outbreak of the epidemic made the loudspeakers as an habit truly“appearing”;(3)the young village cadres,on the other hand,acquired this habit through imitation,transposed the loudspeakers into the short video platform,and carried out different forms of experimentation and innovation,thus surpassing the previous forms of loudspeakers practice.The return of the loudspeakers is the result of the game of different habits.As a long-lasting affection medium,the loudspeakers,on the one hand,has become an important media scene and memory field indispensable to rural community,and on the other hand,the people living on this land have a deep attachment to the loudspeakers,which is indirectly transformed into the bearer of homesickness.This brings new inspiration for us to rethink the relationship between the traditional media and the new media,the iteration of cadres and the change of rural community.展开更多
Ambisonics is a series of spatial sound reproduction system based on spatial harmonics decomposition and each order approximation of sound field.Ambisonics signals are originally intended for loudspeakers reproduction...Ambisonics is a series of spatial sound reproduction system based on spatial harmonics decomposition and each order approximation of sound field.Ambisonics signals are originally intended for loudspeakers reproduction.By using head-related transfer functions(HRTFs)filters,binaural Ambisonics converts the Ambisonics signals for static or dynamic headphone reproduction.In present work,the performances of static and dynamic binaural Ambisonics reproduction are evaluated and compared.The mean binaural pressure errors across target source directions are first analyzed.Then a virtual source localization experiment is conducted,and the localization performances are evaluated by analyzing the percentages of front-back and up-down confusion,the mean angle error and discreteness in the localization results.The results indicate that binaural Ambsonics reproduction with insufficiently high order(for example,5-10 order)is unable to recreate correct high-frequency magnitude spectra in binaural pressures,resulting in degradation in localization for static reproduction.Because dynamic localization cue is included,dynamic binaural Ambisoncis reproduction yields obviously better localization performance than static reproduction with the same order.Even a 3-order dynamic binaural Ambisoncis reproduction exhibits appropriate localizations performance.展开更多
A novel theory of acoustics in solar energy supporting the principle of source and sink of solar energy is presented. The significance of the theory is in ascertaining the aftermaths of turning off solar energy. An am...A novel theory of acoustics in solar energy supporting the principle of source and sink of solar energy is presented. The significance of the theory is in ascertaining the aftermaths of turning off solar energy. An amplifier constituting of a parallel plate photovoltaic device connected to a potentiometer is illustrated. It was constructed with a pair of glass coated photovoltaic modules and polystyrene filled plywood board as back panel with air ventilation through a parallel plate channel of amplifier. The sample results obtained from experiments and simulation model are presented to support hypothesis of acoustics for a parallel plate photovoltaic device connected to a potentiometer. A phenomenon of photovoltaic amplification is formulated.展开更多
Non-reciprocal sound transmission is demonstrated in an electro-acoustic system consisting of two shunt loudspeakers with time-modulated circuits.The shunt circuit is modulated by periodically varying the resistance i...Non-reciprocal sound transmission is demonstrated in an electro-acoustic system consisting of two shunt loudspeakers with time-modulated circuits.The shunt circuit is modulated by periodically varying the resistance in time sequence,and a phase difference of time modulation is set between two sets of loudspeakers to produce a spatial bias.The spatiotemporal modulation of acoustic properties is thus formed to break the reciprocity.The theoretical model based on the transfer-matrix method is developed to predict acoustic scatterings of electro-acoustic systems.Acoustic asymmetric transmission in opposite directions is disclosed by the model and is verified by time-domain simulation results based on the finite-difference time-domain method.Asymmetric transmission in multiple frequency bands can be created by tuning circuit parameters,showing their ability in regulating acoustic non-reciprocal behavior.This study may provide a platform for the design of compact and non-reciprocal acoustic devices with applications to efficient noise control.展开更多
A new kind of flexible, stretchable, and transparent loudspeaker made with carbon nanotube （CNT） film was invented by a team led by Professor Fan Shoufan and Associate Professor Jiang Kaili from Tsinghua＇s Departme...A new kind of flexible, stretchable, and transparent loudspeaker made with carbon nanotube （CNT） film was invented by a team led by Professor Fan Shoufan and Associate Professor Jiang Kaili from Tsinghua＇s Department of Physics.展开更多
This paper analyses the influence of certain parameters and factors on the characteristics of the electropneumatic loudspeaker and describes the experimental work carried out. The developed portable electropneumatic l...This paper analyses the influence of certain parameters and factors on the characteristics of the electropneumatic loudspeaker and describes the experimental work carried out. The developed portable electropneumatic loudspeaker possesses good properties with a flat frequency response from 400 Hz to 2 kHz and a maximum sound pressrue output of 120dB at a distance 2 metre on axis from the horn mouth .The magnetic flux density at the magnetic gap is 19 ,000 gauss .The electropneumatic loudspeaker is small in size and lightweight.展开更多
The technique of coupling two loudspeakers to obtain a signal proportional to the velocity of the cone is known. The sound at a distant point from a loudspeaker is related to the diaphragm displacement. Since the indu...The technique of coupling two loudspeakers to obtain a signal proportional to the velocity of the cone is known. The sound at a distant point from a loudspeaker is related to the diaphragm displacement. Since the induced e.m.f is proportional to the voice coil velocity,measurement of induced e.m.f enables us to obtain the displacement of the cone and hence we can plot the SPL curve for a loudspeaker. This method has some limitations in that it is particularly applicable only when one is interested in using the output of the second speaker used as a sensor in some further applications.展开更多
Operation of a dielectric elastomer(DE)transducer is limited by the way it fails,and any other limits imposed by the user.For example,material rupture and dielectric breakdown are two examples of transducer failure,wh...Operation of a dielectric elastomer(DE)transducer is limited by the way it fails,and any other limits imposed by the user.For example,material rupture and dielectric breakdown are two examples of transducer failure,while tension loss is a user-imposed limit.Electromechanical instability may or may not result in transducer failure,but is often considered as a boundary to denote the onset of state transition.For a DE undergoing homogeneous deformation,constructing operational limits on work-conjugate state diagrams are rather straight-forward.However,for DE subjected to non-homogeneous deformation,the process is more complex.We present a method to plot the operational boundaries of a DE subject to non-homogeneous deformation,known commonly as the Universal Muscle Actuator or the loudspeaker configuration.Our analysis show that tension loss need not be imposed as a hard operational limit,and that there is further operational space for the transducer,post tension loss.By plotting the operational limits on work-conjugate planes,we determine an optimal inner-to-outer ring ratio and the required pre-stretches that maximize energy conversion.展开更多
文摘An infinite panel model of giant magnetostrictive material loudspeaker system （GMMLS） is proposed by making use of finite element method（FEM）. Bending wave eigenfunction is introduced to describe the acoustic radiation condition of the panel. Far-field response in different conditions is calculated by changing the mass surface density. Conclusion is obtained by analyzing the curves simulated, that panel which has larger mass surface density can hardly generate far-field acoustic radiation for lower frequency, while the panel has smaller mass surface density generates far-field acoustic radiation for lower frequency evenly and stronger.
基金Science and Technology Development Plan of Shandong Province(No.2010GSF10809)
文摘An audiobeam loudspeaker system based on the fixed-point digital signal processor(DSP)TMS320VC5509A(VC5509A for short)is developed to emit audible sound with high directivity along a selected path.This system is composed of preamplifier,anti-aliasing filter,ADC(analog to digital converter),VC5509A basic system,DAC(digital to analog converter),smoothing filter,ultrasonic power amplifier and ultrasonic transducer array.VC5509A is used to implement the key signal preprocessing algorithms,such as signal preprocessing,amplitude modulation,carrier signal generator,etc.The experiments show that this system has the advantages of high accuracy and good stability.
文摘In the conventional analogous circuit theory of the loudspeaker system, the vibrating air in box is considered as lumped parameter; in this paper we consider the air as distributed parameter. The sound field theory and the analogous circuit theory are combined to analyze the characteristics of the loudspeaker system such as radiation acoustic power, frequency response and impedance response.
文摘The meteorological early-warning loudspeaker is a specific initiative for the meteorological departments to address the issues concerning issues concerning agriculture,countryside and farmers.Its significance is that it can promptly deliver the early-warning information concerning some meteorological disasters(such as torrential rains,typhoons,cold wave,hail)to the areas affected,so as to provide reference and protection for agricultural production and effectively reduce the loss of agricultural producers.Up to now,the meteorological early-warning loudspeakers in Benxi have covered the villages.However,due to irregular occurrence of meteorological disasters,the listeners will turn off the information receivers of meteorological early-warning loudspeakers when they fail to receive meteorological information for a long time,so that the users can not promptly know the early-warning information regarding some sudden meteorological disasters.In view of this,the meteorological departments have introduced a series of management measures,such as the daily use of loudspeakers to publish weather forecast information,aimed at improving the online rate and usage rate of meteorological loudspeakers.And the management platform for online rate of meteorological early-warning loudspeakers is an important part of the management system.
文摘An overview of the research conducted in the area of linear and nonlinear vibrations of loudspeakers and revolution shells was given in the turning-point frequency range in Chapter 1. It shows that some problems concerning vibrations of shells in the turning-point range have to be further studied. The linear vibrations of truncated revolution shells with the first-order turningpoint were systematically investigated in the turningpoint range from Chapter 2 to Chapter 6, including the general solutions for the free vibration, the eigenvalues under various boundary conditions, the forced vibrations driven by an edge force or an edge displacement and some related special effects, and the applications in loudspeaker vibrations. The nonlinear autoparametric vibration was examined in Chapter 7. Main results are listed as follows.
文摘The exciter component in a panel loudspeaker has a profound effect on the overall performance of the system. The equivalent circuit analysis of the combination of giant magnetostrictive material exciter and distributed mode panel is introduced and how exciter parameters influence panel lo＇udspeaker＇ s performance is discussed. Numerical predictions are given in order to show how these influences are manifested.
基金supported by the National Natural Science Foundation of China(11674105)State Key Lab.of Subtropical Building Science,South China University of Technology.
文摘Ambisonics is a series of flexible spatial sound reproduction systems based on spatial harmonics decomposition of sound field.Traditional horizontal and spatial Ambisonics reconstruct horizontal and spatial sound field with certain order of spatial harmonics,respectively.Both the Shannon-Nyquist spatial sampling frequency limit for accurately reconstructing sound field and the complexity of system increase with the increasing order of Ambisonics.Based on the fact that the horizontal localization resolution of human hearing is higher than vertical resolution,mixed-order Ambisonics(MOA)reconstructs horizontal sound field with higher order spatial harmonics,while reconstructs vertical sound field with lower order spatial harmonics,and thereby reaches a compromise between the perceptual performance and the complexity of system.For a given order horizontal Ambisoncis or MOA reproduction,the number of horizontal loudspeakers is flexible,providing that it exceeds some low limit.By using Moore’s revised loudness model,the present work analyzes the influence of the number of horizontal loudspeakers on timbre both in horizontal Ambisonics and MOA reproduction.The binaural loudness level spectra(BLLS)of Ambisoncis reproduction are calculated and then compared with those of target sound field.The results indicate that below the Shannon-Nyquist limit of spatial sampling,increasing the number of horizontal loudspeakers influence little on BLLS then timbre.Above the limit,however,the BLLS for Ambisoncis reproduction deviate from those of target sound field.The extent of deviation depends on both the direction of target sound field and the number of loudspeakers.Increasing the number of horizontal loudspeakers may increase the change of BLLS then timbre in some cases,but reduce the change in some other cases.For MOA,the influence of the number of horizontal loudspeakers on BLLS and timbre reduces when virtual source departs from horizontal plane to the high or low elevation.The subjective evaluation experiment also validates the analysis.
文摘A hemispherical array of 196 independent loudspeakers has been constructed for laboratory research on spatial hearing, auralization, sound-field quality and spatial audio signal processing. The array of small loudspeakers is supported by a geodesic frame with a radius is 2.4 m. With this relatively high spatial density of sound sources, spatially quantized rendering of sound fields should be viable for a variety of applications, and this paper considers the potential and limits of this approach in relation to human spatial hearing capacities. The paper also considers the combined use of multiple loudspeakers for the rendering low-frequency components of sound sources in order to extend the low-frequency response of the system.
文摘The loudspeakers played a crucial role in rural community during the COVID-19 pandemic,and had returned to the public with the help of short video platforms.However,with the continued popularity of digital media,is the revival of the loudspeakers which belong to traditional media just a flash in the pan?What the historic process of return has the loudspeakers undergone?Based on these questions,the paper applies Bourdieu’s sense of practice theory,focuses on“habit”throughout,adopts the research methods of online ethnography and fieldwork,and conducts participant observation and targeted in-depth interviews in a village in North China for about nine months.The study found that:(1)There is the lag of habit in the state’s handling of social relations in villages.Based on rational habit,village cadres used the loudspeakers to manifest their physical presence and restructure their authority;the villagers,operating under perceptual habit,rationalized the presence of the loudspeakers through using the key words such as elders,nostalgia,and homesickness;(2)the loudspeakers was maintained under the habit of village cadres and ordinary villagers,and the outbreak of the epidemic made the loudspeakers as an habit truly“appearing”;(3)the young village cadres,on the other hand,acquired this habit through imitation,transposed the loudspeakers into the short video platform,and carried out different forms of experimentation and innovation,thus surpassing the previous forms of loudspeakers practice.The return of the loudspeakers is the result of the game of different habits.As a long-lasting affection medium,the loudspeakers,on the one hand,has become an important media scene and memory field indispensable to rural community,and on the other hand,the people living on this land have a deep attachment to the loudspeakers,which is indirectly transformed into the bearer of homesickness.This brings new inspiration for us to rethink the relationship between the traditional media and the new media,the iteration of cadres and the change of rural community.
基金This work was supported by the National Natural Science Foundation of China(11674105)State Key Lab of Subtropical Building Science,South China University of Technology.
文摘Ambisonics is a series of spatial sound reproduction system based on spatial harmonics decomposition and each order approximation of sound field.Ambisonics signals are originally intended for loudspeakers reproduction.By using head-related transfer functions(HRTFs)filters,binaural Ambisonics converts the Ambisonics signals for static or dynamic headphone reproduction.In present work,the performances of static and dynamic binaural Ambisonics reproduction are evaluated and compared.The mean binaural pressure errors across target source directions are first analyzed.Then a virtual source localization experiment is conducted,and the localization performances are evaluated by analyzing the percentages of front-back and up-down confusion,the mean angle error and discreteness in the localization results.The results indicate that binaural Ambsonics reproduction with insufficiently high order(for example,5-10 order)is unable to recreate correct high-frequency magnitude spectra in binaural pressures,resulting in degradation in localization for static reproduction.Because dynamic localization cue is included,dynamic binaural Ambisoncis reproduction yields obviously better localization performance than static reproduction with the same order.Even a 3-order dynamic binaural Ambisoncis reproduction exhibits appropriate localizations performance.
文摘A novel theory of acoustics in solar energy supporting the principle of source and sink of solar energy is presented. The significance of the theory is in ascertaining the aftermaths of turning off solar energy. An amplifier constituting of a parallel plate photovoltaic device connected to a potentiometer is illustrated. It was constructed with a pair of glass coated photovoltaic modules and polystyrene filled plywood board as back panel with air ventilation through a parallel plate channel of amplifier. The sample results obtained from experiments and simulation model are presented to support hypothesis of acoustics for a parallel plate photovoltaic device connected to a potentiometer. A phenomenon of photovoltaic amplification is formulated.
基金supported by the National Natural Science Foundation of China (Grant Nos.11872111,11991030,11991033,and 11622215)the 111 Project (Grant No.B16003).
文摘Non-reciprocal sound transmission is demonstrated in an electro-acoustic system consisting of two shunt loudspeakers with time-modulated circuits.The shunt circuit is modulated by periodically varying the resistance in time sequence,and a phase difference of time modulation is set between two sets of loudspeakers to produce a spatial bias.The spatiotemporal modulation of acoustic properties is thus formed to break the reciprocity.The theoretical model based on the transfer-matrix method is developed to predict acoustic scatterings of electro-acoustic systems.Acoustic asymmetric transmission in opposite directions is disclosed by the model and is verified by time-domain simulation results based on the finite-difference time-domain method.Asymmetric transmission in multiple frequency bands can be created by tuning circuit parameters,showing their ability in regulating acoustic non-reciprocal behavior.This study may provide a platform for the design of compact and non-reciprocal acoustic devices with applications to efficient noise control.
文摘A new kind of flexible, stretchable, and transparent loudspeaker made with carbon nanotube （CNT） film was invented by a team led by Professor Fan Shoufan and Associate Professor Jiang Kaili from Tsinghua＇s Department of Physics.
文摘This paper analyses the influence of certain parameters and factors on the characteristics of the electropneumatic loudspeaker and describes the experimental work carried out. The developed portable electropneumatic loudspeaker possesses good properties with a flat frequency response from 400 Hz to 2 kHz and a maximum sound pressrue output of 120dB at a distance 2 metre on axis from the horn mouth .The magnetic flux density at the magnetic gap is 19 ,000 gauss .The electropneumatic loudspeaker is small in size and lightweight.
文摘The technique of coupling two loudspeakers to obtain a signal proportional to the velocity of the cone is known. The sound at a distant point from a loudspeaker is related to the diaphragm displacement. Since the induced e.m.f is proportional to the voice coil velocity,measurement of induced e.m.f enables us to obtain the displacement of the cone and hence we can plot the SPL curve for a loudspeaker. This method has some limitations in that it is particularly applicable only when one is interested in using the output of the second speaker used as a sensor in some further applications.
基金This work was supported by the Agency for Science,Technology and Research(Singapore)and Department of Science&Technology(India)(A*STAR-DST)[R-265-000-524-305(SERC 1425203140)]。
文摘Operation of a dielectric elastomer(DE)transducer is limited by the way it fails,and any other limits imposed by the user.For example,material rupture and dielectric breakdown are two examples of transducer failure,while tension loss is a user-imposed limit.Electromechanical instability may or may not result in transducer failure,but is often considered as a boundary to denote the onset of state transition.For a DE undergoing homogeneous deformation,constructing operational limits on work-conjugate state diagrams are rather straight-forward.However,for DE subjected to non-homogeneous deformation,the process is more complex.We present a method to plot the operational boundaries of a DE subject to non-homogeneous deformation,known commonly as the Universal Muscle Actuator or the loudspeaker configuration.Our analysis show that tension loss need not be imposed as a hard operational limit,and that there is further operational space for the transducer,post tension loss.By plotting the operational limits on work-conjugate planes,we determine an optimal inner-to-outer ring ratio and the required pre-stretches that maximize energy conversion.
