Thermoacoustic phenomena had been discovered early in the history. The develop ment of the related theory and practice is especially vigorous in recent years. The developments of the theory and experiments of thermoac...Thermoacoustic phenomena had been discovered early in the history. The develop ment of the related theory and practice is especially vigorous in recent years. The developments of the theory and experiments of thermoacoustics and its state-of arts are reviewed from the point of view of an acoustician展开更多
Ultrasound neuromodulation is a powerful tool for brain investigation and holds great promise for treating brain diseases.However,due to the heterogeneous acoustic properties of skulls,existing ultrasound neuromodulat...Ultrasound neuromodulation is a powerful tool for brain investigation and holds great promise for treating brain diseases.However,due to the heterogeneous acoustic properties of skulls,existing ultrasound neuromodulation faces the challenge of severe transcranial acoustic attenuation.To overcome such limitations,we report an implantable bio-chip for visible and controllable mi-crowave-induced transcranial acoustic generation(MI-tAG).The bio-chip is soft,flexible,and biocompatible,with a thickness of 3mm,making it suitable for human intracranial implantation.The constituted fluid channels can cover an area of 50 mm×60 mm,enabling widefield neuronstimulation.The particles filled in the fluid channels have both high microwave absorption.ensuring efficient ultrasound generation,and magnetism,allowing noncontact and flexible ma-nipulation by external magnetic fields.The experimental results demonstrate that the optimal MI-tAG can be realized by the combination of particles arranged in a linear pattern and corre-sponding illumination via a linearly polarized microwave.Stability evaluation indicates that the particles can maintain a consistent acoustic intensity without degradation for at least seven days.The results of in vitro and in vivo experiments show that the MII-tAG can manipulate ultrasound sources and visibly locate them in real time.This study provides a potential innovative approach for future ultrasound neuromodulation,inspiring the development of more useful methods to advance brain research.This study introduces a promising innovative approach for transcranial acoustic generation,potentially inspiring the development of more effective methods for ad-vancing ultrasound neuromodulation.展开更多
1.Challenges Thermoacoustic instability in combustors arises from the interaction between sound waves and unsteady heat release,commonly found in systems like gas turbines and aeroengines.This instability leads to und...1.Challenges Thermoacoustic instability in combustors arises from the interaction between sound waves and unsteady heat release,commonly found in systems like gas turbines and aeroengines.This instability leads to undesirable consequences such as structural damage and performance deterioration.The challenge lies in predicting and mitigating these instabilities due to the complex interplay of various physical phenomena like acoustic propagation,turbulent flow,and combustion chemistry,which are summarized in detail in Aimee S.Morgans and Dong Yang's published article.展开更多
Thermoacoustic instabilities,frequent in a wide range of combustors,arise from the intricate coupling between the flame's unsteady heat release and the combustor acoustic.The application of plasma,characterized by...Thermoacoustic instabilities,frequent in a wide range of combustors,arise from the intricate coupling between the flame's unsteady heat release and the combustor acoustic.The application of plasma,characterized by its substantial local energy addition and radical generation,has demonstrated potential in disrupting this coupling and thereby mitigating thermoacoustic oscillations.Notably,open-loop control using discharge plasma has been successfully implemented to suppress self-excited oscillations in a Rijke tube setup.Considering the broader context of a complex system that integrates both thermoacoustic systems and discharge plasma,experiments were done to see its performance in stability under different arrangement and discharge repetition rates of discharge plasma.These experimental investigations identified critical operating conditions essential for complete suppression:(A)the optimal location of discharge actuations,and(B)the minimum energy required for complete suppression.Moreover,the impact of discharge plasma,particularly when tuned to the eigenfrequencies of oscillations within the thermoacoustic system.was thoroughly examined.The insights gained from these successful suppression trials are instrumental in guiding the strategic design of both physical arrangement and electrical configurations for the control of combustion instabilities via discharge plasma.Furthermore,through the photographing of the swinging arcs and their thermal disturbances by high-speed camera and highspeed schlieren,the characteristics of arcs'thermal disturbances and the reasons affecting its suppression effectiveness were determined.展开更多
Thermoacoustic imaging(TAI)contrast comes from different electrical properties(EPs)of microwave absorption.However,the relationship between the permittivity distribution and the electric field polarization limits the ...Thermoacoustic imaging(TAI)contrast comes from different electrical properties(EPs)of microwave absorption.However,the relationship between the permittivity distribution and the electric field polarization limits the application of TAI in some extent.Here,we present a polarimetric thermoacoustic imaging(pTAI)system based on a rotary waveguide.By optimizing a rotary waveguide(insertion loss<0.2dB,return loss>15dB at 3GHz),the excitation wave emitted from a horn antenna can rotate freely in the direction of polarization.The multi-polarization pulsed microwave signal is used to evoke the thermoacoustic signals(TAS)of samples in different polarimetric directions.The simulation for pTAI with a multi-directional sample is first obtained.Then,we rotated the rotary waveguide at 10°/s and experimentally demonstrated the performance of pTAI by imaging three randomly placed soy sauce tubes and ex vivo beef.This study suggests that pTAI has potential for dielectric properties“diffusion”mapping,for example,provides conductivity tensor mapping of brain and muscle.展开更多
Nolilinarity in thermoacoustics mainly comes from asee-amplitude sound waves)which is necessary for the thermoacoustic phenomena. Exact solutions are found for sound waves in a tube, Mathematical tecniques are develop...Nolilinarity in thermoacoustics mainly comes from asee-amplitude sound waves)which is necessary for the thermoacoustic phenomena. Exact solutions are found for sound waves in a tube, Mathematical tecniques are developed to solve the Riemann equations in cases unsuitable for conventional methods. The tube is characterized by its cross-sectional area and shape, which is reflected in the wave numer in the tube. Exact solutions for different tube configurations are found, includin thermacoustic stacks with temperature gradient. And composite tube containing sections of different characters is sloved, by using the continuity equations of volume velocity and pressure between sections.展开更多
Microwave-induced thermoacoustic imaging(MTI)has the advantages of high resolution,high contrast,non-ionization,and non-invasive.Recently,MTI was used in the¯eld of breast cancer screening.In this paper,based on ...Microwave-induced thermoacoustic imaging(MTI)has the advantages of high resolution,high contrast,non-ionization,and non-invasive.Recently,MTI was used in the¯eld of breast cancer screening.In this paper,based on the¯nite element method(FEM)and COMSOL Multiphysics software,a three-dimensional breast cancer model suitable for exploring the MTI process is proposed to investigate the in°uence of Young's modulus(YM)of breast cancer tissue on MTI.It is found that the process of electromagnetic heating and initial pressure generation of the entire breast tissue is earlier in time than the thermal expansion process.Besides,compared with normal breast tissue,tumor tissue has a greater temperature rise,displacement,and pressure rise.In particular,YM of the tumor is related to the speed of thermal expansion.In particular,the larger the YM of the tumor is,the higher the heating and contraction frequency is,and the greater the maximum pressure is.Di®erent Young's moduli correspond to di®erent thermoacoustic signal spectra.In MTI,this study can be used to judge di®erent degrees of breast cancer based on elastic imaging.In addition,this study is helpful in exploring the possibility of microwave-induced thermoacoustic elastic imaging(MTAE).展开更多
Puncture biopsy is an important clinical technique to obtain diseased tissue for pathological diagnosis,where imaging guidance is critical.In this paper,we describe a metal reflector-enhanced microwave-induced thermoa...Puncture biopsy is an important clinical technique to obtain diseased tissue for pathological diagnosis,where imaging guidance is critical.In this paper,we describe a metal reflector-enhanced microwave-induced thermoacoustic imaging(TAI)approach capable of guiding puncture biopsy for detection of breast cancer and joint diseases.Numerical experimentations simulating puncture guidance in breast cancer and knee gout models werefirst conducted using(CST STUDIO SUITE)(CST)software,and then ex-vivo experiments were performed followed by qualitative observations and semi-quantitative analysis.The results of both the simulations and ex-vivo experiments showed that our reflector-enhanced TAI could image the puncture needle in high resolution with a large depth of>12 cm.展开更多
This paper focuses on the temperature and pressure characteristics of a Swift-Backhaus type traveling-wave thermoacoustic prime mover during its onset and damping processes,in order to understand the intrinsic mechani...This paper focuses on the temperature and pressure characteristics of a Swift-Backhaus type traveling-wave thermoacoustic prime mover during its onset and damping processes,in order to understand the intrinsic mechanism of thermoacoustic oscillation onset and the feasibility of using low-grade thermal energy based on a low onset temperature. The influences of heat input and filling pressure on hysteretic loop,due to the noncoincidence between onset and damping processes,are measured and analyzed. The condition for the occurrence of hysteresis is also briefly discussed.展开更多
A miniature thermoacoustic prime mover, consuming heat to radiate sound, may be considered as a potential way of heat management in microcircuits because of its simplicity and stability. A prototype with variable reso...A miniature thermoacoustic prime mover, consuming heat to radiate sound, may be considered as a potential way of heat management in microcircuits because of its simplicity and stability. A prototype with variable resonant tube length of 10 to 25 cm was built, and experiments were carried out to observe its performance, such as onset temperature, oscillation amplitude and operating frequency. The results with atmospheric air showed that proper structures and operating conditions can make the system start an oscillation at a temperature lower than 100 ℃, which proves the feasibility of potential usage in electronic units. The influences of stack position, heat input power or tube inclination on the oscillation amplitude, onset temperature and operating frequency are also presented.展开更多
An acoustic pressure amplifier (APA) is capable of improving the match between a thermoacoustic engine and a load by elevating pressure ratio and acoustic power output. A standing-wave thermoacoustic engine driving a ...An acoustic pressure amplifier (APA) is capable of improving the match between a thermoacoustic engine and a load by elevating pressure ratio and acoustic power output. A standing-wave thermoacoustic engine driving a resistance- and-compliance (RC) load through an APA was simulated with linear thermoacoustics to study the impact of load impedance on the performance of the thermoacoustic system. Based on the simulation results, analysis focuses on the distribution of pressure amplitude and velocity amplitude in APA with an RC load of diverse acoustic resistances and compliance impedances. Variation of operating parameters, including pressure ratio, acoustic power, hot end temperature of stack, etc., versus impedance of the RC load is presented and analyzed according to the abovementioned distribution. A verifying experiment has been performed, which indicates that the simulation can roughly predict the system operation in the fundamental-frequency mode.展开更多
Photoacoustic tomography （PAT） is a powerful imaging merits and most compelling features of light and sound, technique for medical diagnosis because it combines the We describe a PAT experimental system constructed ...Photoacoustic tomography （PAT） is a powerful imaging merits and most compelling features of light and sound, technique for medical diagnosis because it combines the We describe a PAT experimental system constructed in our laboratory which consists of a Q-switched Nd：YAG pulse laser operating at 532nm with a 8-ns pulse width to generate the photoacoustic signals from a biological sample. Two-dimensional photoacoustic imaging of blood vessel networks lcm below the tissue surface is achieved, We also successfully demonstrate that the system is capable of imaging the blood vessels over the ex vivo rat brain with skull and skin intact.展开更多
Microwave induced thermoacoustic imaging(MTAI)has emerged as a potential biomedical imaging modality with over 20-year growth.MTAI typically employs pulsed microwave as the pumping source,and detects the microwave-ind...Microwave induced thermoacoustic imaging(MTAI)has emerged as a potential biomedical imaging modality with over 20-year growth.MTAI typically employs pulsed microwave as the pumping source,and detects the microwave-induced ultrasound wave via acoustic transducers.Therefore,it features high acoustic resolution,rich elect romagnetic contrast,and large imaging depth.Benefiting from these unique advantages,MTAI has been extensively applied to various fields including pathology,biology,material and medicine.Till now,MTAI has been deployed for a wide range of biomedical applications,including cancer diagnosis,joint evaluation,brain in-vestigation and endoscopy.This paper provides a comprehensive review on(1)essential physics(endogenous/exogenous contrast mechanisms,penetration depth and resolution),(2)hardware configurations and software implementations(excit ation source,antenna,ultrasound detector and image recovery algorithm),(3)animal studies and clinical applications,and(4)future directions.展开更多
A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system ...A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system consists of countless replicas.Each particle is confined in its own potential well,whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions.Based on the Schrodinger equation,the expressions of coefficient of performance(COP)and cooling rate for the refrigerator are obtained.Effects of heat leakage on the optimal performance are discussed.The optimal performance region of the refrigeration cycle is obtained by the using ofΩobjective function.The results obtained can enrich the thermoacoustic theory and expand the application of quantum thermodynamics.展开更多
Microwave-induced thermoacoustic imaging(TAI)is a noninvasive modality based on the differences in microwave absorption of various biological tissues.TAI has been extensively researched in recent years,and several stu...Microwave-induced thermoacoustic imaging(TAI)is a noninvasive modality based on the differences in microwave absorption of various biological tissues.TAI has been extensively researched in recent years,and several studies have revealed that TAI possesses advantages such as high resolution,high contrast,high imaging depth and fast imaging speed.In this paper,we reviewed the development of the TAI technique,its excitation source,data acquisition system and biomedical applications.It is believed that TAI has great potential applications in biomedical research and clinical study.展开更多
Here,we report a new method using combined magnetic resonance(MR)-Photoacoustic(PA)-Thermoacoustic(TA)imaging techmiques,and demonstrate its unique ability for in vrivo cancer detection using tumor-bearing mice.Circul...Here,we report a new method using combined magnetic resonance(MR)-Photoacoustic(PA)-Thermoacoustic(TA)imaging techmiques,and demonstrate its unique ability for in vrivo cancer detection using tumor-bearing mice.Circular scanning TA and PA imaging systems were used to recover the dielectric and optical property dist ributions of three colon carcinoma bearing mice While a 7.0-T magnetic resonance imaging(MRI)unit with a mouse body volume coil was utilized for high resolution structural imaging of the same mice.Three plastic tubes flled with soybean sauce were used as fiducial markers for the co-registration of MR,PA and TA images.The resulting fused images provided both enhanced tumor margin and contrast relative to the surrounding normal tissues.In particular,some finger-like protrusions extending into the surrounding tissues were revealed in the MR/TA infused images.These results show that the tissue functional optical and dielectric properties provided by PA and TA images along with the anatomical structure by MRI in one picture make accurate tumor identification easier.This combined MR-PA-TA-imaging strategy has the potential to offer a dinically useful triple-modality tool for accurate cancer detection and for intraoper ative surgical navigation.展开更多
We present for the¯rst time in vivo imaging of rat brain using microwave-induced thermoacoustic tomography(TAT).The in vivo imaging of rat brain was realized through an unconventional delivery of microwave energy...We present for the¯rst time in vivo imaging of rat brain using microwave-induced thermoacoustic tomography(TAT).The in vivo imaging of rat brain was realized through an unconventional delivery of microwave energy from the front of rat brain(while the transducer was scanned along coronal plane of the animal brain),which maximized the microwave penetration into the brain.In addition,we found that the imaging contrast was highly dependent on the direction of the electric¯eld polarization(EFP)and that more tissue structures/compositions could be revealed when both X-and Y-EFPs were used for TAT.The in vivo TAT images of rat brain obtained were compared with the 3.0 T MRI images and histological photographs,and numerous important brain anatomical structures were identi¯ed.An example of our TAT approach for imaging a foreign object embedded in a rat brain was also demonstrated.This study suggests that TAT has a great potential to be used in neuroscience studies and in noninvasive imaging of brain disorders.展开更多
This study is concerned with the experimental and theoretical investigation of the combustion instabilities in a premixed swirl combustor.It is focused on the effects of the swirl mixing distance on the intrinsic ther...This study is concerned with the experimental and theoretical investigation of the combustion instabilities in a premixed swirl combustor.It is focused on the effects of the swirl mixing distance on the intrinsic thermoacoustic mode.The swirler as an origin of the swirling flow is also the source of the flow disturbance,which has effects on the flame response.The location of the swirler is varied in the experiment to study the effect on combustion instabilities and flame transfer functions.A low order model is built to analyze the thermoacoustic instabilities of the combustion system.The experimental results show that the ITA switches from an unstable state to a stable state as the swirl mixing distance changes with an increment of 15 mm;while the instability of the quarter-wave mode is not varied.The measured Flame Transfer Functions(FTFs)show that the gain curves of the frequency-dependent FTFs seem to be stretched or compressed with the modulation of the swirler position,which has effects on frequencies and instabilities of thermoacoustic modes.With the low order model,the effects of flame response on combustion instabilities are analyzed and the flame dominant nature of the ITA mode is confirmed.展开更多
Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues...Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues are complicated,thus result in severe artifacts.In this study,to reveal the underlying mechanisms of artifacts,we deeply investigate the distribution of specific absorption rate(SAR)inside tissue-mimicking phantoms with varied morphological features using both mathematical simulations and corresponding experiments.Our simulated results,which are confirmed by the associated experimental results,show that the SAR distri-bution highly depends on the geometries of the imaging targets and the polarizing features of the microwave.In addition,we propose the potential mechanisms including Mie-scattering,Fabry-Perot-feature,small curvature effect to interpret the diffraction effect in different scenarios,which may provide basic guidance to predict and distinguish the artifacts for TAI in both fundamental and clinical studies.展开更多
Microwave induced thermoacoustic tomography(TAT)is a noninvasive,nonionizing modality based on the inherent differences in microwave absorpt ion of malignant breast tissues and normal adipose dominated breast tissues....Microwave induced thermoacoustic tomography(TAT)is a noninvasive,nonionizing modality based on the inherent differences in microwave absorpt ion of malignant breast tissues and normal adipose dominated breast tissues.In this paper,a TAT system based on multielement acquisition system was built to receive signals.Slices from different layers in the sample were composed into a three-dimensional(3D)volume.Based on the 3D volume,inherent differences in microw ave absorption bet ween different biological tisues can be converted into structure information.Our experimental results of some minicked and human tumors indicate that TAT may potentially be used to detect early-stage breast cancers with high contrast.展开更多
文摘Thermoacoustic phenomena had been discovered early in the history. The develop ment of the related theory and practice is especially vigorous in recent years. The developments of the theory and experiments of thermoacoustics and its state-of arts are reviewed from the point of view of an acoustician
基金supported by the National Key R&D Program of China under grant 2023YFF0715303in part by the National Natural Science Foundation of China under Grant Nos.62305148,62105140,62022037,and 61775028+2 种基金in part by the Department of Science and Technology of Guangdong Province under Grant Nos.2019ZT08Y191 and 2022B1212010003in part by the Shenzhen Science and Technology Program under Grant Nos.JCYJ20220530114010023,RCJC20231211090039066,20231116104616001,KQTD20190929172743294,JCYJ20230807093105010,RCBS20231211090802011in part by the Startup Grant from Southern University of Science and Technology under Grant No.PDJH2021C008.
文摘Ultrasound neuromodulation is a powerful tool for brain investigation and holds great promise for treating brain diseases.However,due to the heterogeneous acoustic properties of skulls,existing ultrasound neuromodulation faces the challenge of severe transcranial acoustic attenuation.To overcome such limitations,we report an implantable bio-chip for visible and controllable mi-crowave-induced transcranial acoustic generation(MI-tAG).The bio-chip is soft,flexible,and biocompatible,with a thickness of 3mm,making it suitable for human intracranial implantation.The constituted fluid channels can cover an area of 50 mm×60 mm,enabling widefield neuronstimulation.The particles filled in the fluid channels have both high microwave absorption.ensuring efficient ultrasound generation,and magnetism,allowing noncontact and flexible ma-nipulation by external magnetic fields.The experimental results demonstrate that the optimal MI-tAG can be realized by the combination of particles arranged in a linear pattern and corre-sponding illumination via a linearly polarized microwave.Stability evaluation indicates that the particles can maintain a consistent acoustic intensity without degradation for at least seven days.The results of in vitro and in vivo experiments show that the MII-tAG can manipulate ultrasound sources and visibly locate them in real time.This study provides a potential innovative approach for future ultrasound neuromodulation,inspiring the development of more useful methods to advance brain research.This study introduces a promising innovative approach for transcranial acoustic generation,potentially inspiring the development of more effective methods for ad-vancing ultrasound neuromodulation.
文摘1.Challenges Thermoacoustic instability in combustors arises from the interaction between sound waves and unsteady heat release,commonly found in systems like gas turbines and aeroengines.This instability leads to undesirable consequences such as structural damage and performance deterioration.The challenge lies in predicting and mitigating these instabilities due to the complex interplay of various physical phenomena like acoustic propagation,turbulent flow,and combustion chemistry,which are summarized in detail in Aimee S.Morgans and Dong Yang's published article.
基金supported by the Fundamental Research Funds for the Central Universities,China(No.501XTCX2023146001).
文摘Thermoacoustic instabilities,frequent in a wide range of combustors,arise from the intricate coupling between the flame's unsteady heat release and the combustor acoustic.The application of plasma,characterized by its substantial local energy addition and radical generation,has demonstrated potential in disrupting this coupling and thereby mitigating thermoacoustic oscillations.Notably,open-loop control using discharge plasma has been successfully implemented to suppress self-excited oscillations in a Rijke tube setup.Considering the broader context of a complex system that integrates both thermoacoustic systems and discharge plasma,experiments were done to see its performance in stability under different arrangement and discharge repetition rates of discharge plasma.These experimental investigations identified critical operating conditions essential for complete suppression:(A)the optimal location of discharge actuations,and(B)the minimum energy required for complete suppression.Moreover,the impact of discharge plasma,particularly when tuned to the eigenfrequencies of oscillations within the thermoacoustic system.was thoroughly examined.The insights gained from these successful suppression trials are instrumental in guiding the strategic design of both physical arrangement and electrical configurations for the control of combustion instabilities via discharge plasma.Furthermore,through the photographing of the swinging arcs and their thermal disturbances by high-speed camera and highspeed schlieren,the characteristics of arcs'thermal disturbances and the reasons affecting its suppression effectiveness were determined.
基金supported in part by the National Natural Science Foundation of China(No.82071940)the National Key R&D Program of China(No.2018YFF01013603)。
文摘Thermoacoustic imaging(TAI)contrast comes from different electrical properties(EPs)of microwave absorption.However,the relationship between the permittivity distribution and the electric field polarization limits the application of TAI in some extent.Here,we present a polarimetric thermoacoustic imaging(pTAI)system based on a rotary waveguide.By optimizing a rotary waveguide(insertion loss<0.2dB,return loss>15dB at 3GHz),the excitation wave emitted from a horn antenna can rotate freely in the direction of polarization.The multi-polarization pulsed microwave signal is used to evoke the thermoacoustic signals(TAS)of samples in different polarimetric directions.The simulation for pTAI with a multi-directional sample is first obtained.Then,we rotated the rotary waveguide at 10°/s and experimentally demonstrated the performance of pTAI by imaging three randomly placed soy sauce tubes and ex vivo beef.This study suggests that pTAI has potential for dielectric properties“diffusion”mapping,for example,provides conductivity tensor mapping of brain and muscle.
文摘Nolilinarity in thermoacoustics mainly comes from asee-amplitude sound waves)which is necessary for the thermoacoustic phenomena. Exact solutions are found for sound waves in a tube, Mathematical tecniques are developed to solve the Riemann equations in cases unsuitable for conventional methods. The tube is characterized by its cross-sectional area and shape, which is reflected in the wave numer in the tube. Exact solutions for different tube configurations are found, includin thermacoustic stacks with temperature gradient. And composite tube containing sections of different characters is sloved, by using the continuity equations of volume velocity and pressure between sections.
基金supported by the National Natural Science Foundation of China(Nos.12174208 and 32227802)National Key Research and Development Program of China(No.2022YFC3400600)+2 种基金Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030009)Fundamental Research Funds for the Central Universities(Nos.2122021337 and 2122021405)the 111 Project(No.B23045).
文摘Microwave-induced thermoacoustic imaging(MTI)has the advantages of high resolution,high contrast,non-ionization,and non-invasive.Recently,MTI was used in the¯eld of breast cancer screening.In this paper,based on the¯nite element method(FEM)and COMSOL Multiphysics software,a three-dimensional breast cancer model suitable for exploring the MTI process is proposed to investigate the in°uence of Young's modulus(YM)of breast cancer tissue on MTI.It is found that the process of electromagnetic heating and initial pressure generation of the entire breast tissue is earlier in time than the thermal expansion process.Besides,compared with normal breast tissue,tumor tissue has a greater temperature rise,displacement,and pressure rise.In particular,YM of the tumor is related to the speed of thermal expansion.In particular,the larger the YM of the tumor is,the higher the heating and contraction frequency is,and the greater the maximum pressure is.Di®erent Young's moduli correspond to di®erent thermoacoustic signal spectra.In MTI,this study can be used to judge di®erent degrees of breast cancer based on elastic imaging.In addition,this study is helpful in exploring the possibility of microwave-induced thermoacoustic elastic imaging(MTAE).
基金supported in part by the Chinese Postdoctoral Science Foundation(2022MD723722)in part by the National Natural Science Foundation of China(62001075)in part by the Chongqing postdoctoral research project(special funding project 2021XM2026).
文摘Puncture biopsy is an important clinical technique to obtain diseased tissue for pathological diagnosis,where imaging guidance is critical.In this paper,we describe a metal reflector-enhanced microwave-induced thermoacoustic imaging(TAI)approach capable of guiding puncture biopsy for detection of breast cancer and joint diseases.Numerical experimentations simulating puncture guidance in breast cancer and knee gout models werefirst conducted using(CST STUDIO SUITE)(CST)software,and then ex-vivo experiments were performed followed by qualitative observations and semi-quantitative analysis.The results of both the simulations and ex-vivo experiments showed that our reflector-enhanced TAI could image the puncture needle in high resolution with a large depth of>12 cm.
基金the National Natural Science Foundation of China (Nos. 50776075 and 50536040)the Natural ScienceFoundation of Zhejiang Province (No. Y107229), China
文摘This paper focuses on the temperature and pressure characteristics of a Swift-Backhaus type traveling-wave thermoacoustic prime mover during its onset and damping processes,in order to understand the intrinsic mechanism of thermoacoustic oscillation onset and the feasibility of using low-grade thermal energy based on a low onset temperature. The influences of heat input and filling pressure on hysteretic loop,due to the noncoincidence between onset and damping processes,are measured and analyzed. The condition for the occurrence of hysteresis is also briefly discussed.
基金Project supported by the National Natural Sciences Foundation of China (No. 50536040), the China Postdoctoral Science Foundation(No. 2005038280), and the Natural Sciences Foundation of ZhejiangProvince (No. Y104326), China
文摘A miniature thermoacoustic prime mover, consuming heat to radiate sound, may be considered as a potential way of heat management in microcircuits because of its simplicity and stability. A prototype with variable resonant tube length of 10 to 25 cm was built, and experiments were carried out to observe its performance, such as onset temperature, oscillation amplitude and operating frequency. The results with atmospheric air showed that proper structures and operating conditions can make the system start an oscillation at a temperature lower than 100 ℃, which proves the feasibility of potential usage in electronic units. The influences of stack position, heat input power or tube inclination on the oscillation amplitude, onset temperature and operating frequency are also presented.
基金Project supported by the National Natural Sciences Foundation of China (No. 50536040)the University Doctoral Subject Special Foundation of China (No. 20050335047)+1 种基金the Postdoctoral Science Foundation of Zhejiang Province (No. 2006-bsh-21)the Natural Science Foundation of Zhejiang Province (No. Y107229), China
文摘An acoustic pressure amplifier (APA) is capable of improving the match between a thermoacoustic engine and a load by elevating pressure ratio and acoustic power output. A standing-wave thermoacoustic engine driving a resistance- and-compliance (RC) load through an APA was simulated with linear thermoacoustics to study the impact of load impedance on the performance of the thermoacoustic system. Based on the simulation results, analysis focuses on the distribution of pressure amplitude and velocity amplitude in APA with an RC load of diverse acoustic resistances and compliance impedances. Variation of operating parameters, including pressure ratio, acoustic power, hot end temperature of stack, etc., versus impedance of the RC load is presented and analyzed according to the abovementioned distribution. A verifying experiment has been performed, which indicates that the simulation can roughly predict the system operation in the fundamental-frequency mode.
文摘Photoacoustic tomography （PAT） is a powerful imaging merits and most compelling features of light and sound, technique for medical diagnosis because it combines the We describe a PAT experimental system constructed in our laboratory which consists of a Q-switched Nd：YAG pulse laser operating at 532nm with a 8-ns pulse width to generate the photoacoustic signals from a biological sample. Two-dimensional photoacoustic imaging of blood vessel networks lcm below the tissue surface is achieved, We also successfully demonstrate that the system is capable of imaging the blood vessels over the ex vivo rat brain with skull and skin intact.
基金This work was supported in part by the National Natural Science Foundation of China(62022037,62105140,61775028,81571722 and 61528401)in part by Department of Science and Technology of Guangdong Province(2019ZT08Y191,SZBL2020090501013)+3 种基金Guangdong Provincial Key Laboratory of Advanced Biomaterials(2022B1212010003)Guangdong Provincial Department of Education(2021ZDZX1064)Shenzhen Science and Technology Program(JCYJ20200109141222892,KQTD20190-929172743294)in part by Startup grant from Southern University of Science and Technology.
文摘Microwave induced thermoacoustic imaging(MTAI)has emerged as a potential biomedical imaging modality with over 20-year growth.MTAI typically employs pulsed microwave as the pumping source,and detects the microwave-induced ultrasound wave via acoustic transducers.Therefore,it features high acoustic resolution,rich elect romagnetic contrast,and large imaging depth.Benefiting from these unique advantages,MTAI has been extensively applied to various fields including pathology,biology,material and medicine.Till now,MTAI has been deployed for a wide range of biomedical applications,including cancer diagnosis,joint evaluation,brain in-vestigation and endoscopy.This paper provides a comprehensive review on(1)essential physics(endogenous/exogenous contrast mechanisms,penetration depth and resolution),(2)hardware configurations and software implementations(excit ation source,antenna,ultrasound detector and image recovery algorithm),(3)animal studies and clinical applications,and(4)future directions.
基金Project(51176143)supported by the National Natural Science Foundation of ChinaProject(K201919)supported by the Scientific Research Foundation of Wuhan Institute of TechnologyChina。
文摘A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system consists of countless replicas.Each particle is confined in its own potential well,whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions.Based on the Schrodinger equation,the expressions of coefficient of performance(COP)and cooling rate for the refrigerator are obtained.Effects of heat leakage on the optimal performance are discussed.The optimal performance region of the refrigeration cycle is obtained by the using ofΩobjective function.The results obtained can enrich the thermoacoustic theory and expand the application of quantum thermodynamics.
基金the National Natural Science Foundation of China(61627827,61331001,81630046,91539127)the Science and Technology Planning Project of Guangdong Province,China(2015B020233016,2014B020215003,2014A020215031,2017A020215135)+3 种基金the Distinguished Young Teacher Project in Higher Education of Guangdong,China(YQ2015049)the Science and Technology Youth Talent for Special Project of Guangdong,China(2015TQ01X882)Young Teachers Scienti¯c Research Cultivating Fund of South China Normal University(16KJ05)China Postdoctoral Science Foundation(2017M610533).
文摘Microwave-induced thermoacoustic imaging(TAI)is a noninvasive modality based on the differences in microwave absorption of various biological tissues.TAI has been extensively researched in recent years,and several studies have revealed that TAI possesses advantages such as high resolution,high contrast,high imaging depth and fast imaging speed.In this paper,we reviewed the development of the TAI technique,its excitation source,data acquisition system and biomedical applications.It is believed that TAI has great potential applications in biomedical research and clinical study.
基金supported by the Chinese Govern-ment's 1000-Talent Plan via the University of Elec-tronic Science and Technology of China and by the J.Crayton Pruitt Family Endowment(to HJ)the National Natural Science Foundation of China(81130027 and 81520108014)+1 种基金the National"Twelfth FiveYear"Plan for Science&Technology Support(2012BAI23B08)the National Basic Research Program of China(973 Program,2011CB935800)(to FG).
文摘Here,we report a new method using combined magnetic resonance(MR)-Photoacoustic(PA)-Thermoacoustic(TA)imaging techmiques,and demonstrate its unique ability for in vrivo cancer detection using tumor-bearing mice.Circular scanning TA and PA imaging systems were used to recover the dielectric and optical property dist ributions of three colon carcinoma bearing mice While a 7.0-T magnetic resonance imaging(MRI)unit with a mouse body volume coil was utilized for high resolution structural imaging of the same mice.Three plastic tubes flled with soybean sauce were used as fiducial markers for the co-registration of MR,PA and TA images.The resulting fused images provided both enhanced tumor margin and contrast relative to the surrounding normal tissues.In particular,some finger-like protrusions extending into the surrounding tissues were revealed in the MR/TA infused images.These results show that the tissue functional optical and dielectric properties provided by PA and TA images along with the anatomical structure by MRI in one picture make accurate tumor identification easier.This combined MR-PA-TA-imaging strategy has the potential to offer a dinically useful triple-modality tool for accurate cancer detection and for intraoper ative surgical navigation.
文摘We present for the¯rst time in vivo imaging of rat brain using microwave-induced thermoacoustic tomography(TAT).The in vivo imaging of rat brain was realized through an unconventional delivery of microwave energy from the front of rat brain(while the transducer was scanned along coronal plane of the animal brain),which maximized the microwave penetration into the brain.In addition,we found that the imaging contrast was highly dependent on the direction of the electric¯eld polarization(EFP)and that more tissue structures/compositions could be revealed when both X-and Y-EFPs were used for TAT.The in vivo TAT images of rat brain obtained were compared with the 3.0 T MRI images and histological photographs,and numerous important brain anatomical structures were identi¯ed.An example of our TAT approach for imaging a foreign object embedded in a rat brain was also demonstrated.This study suggests that TAT has a great potential to be used in neuroscience studies and in noninvasive imaging of brain disorders.
基金supported the National Natural Science Foundation of China(Nos.51676126 and 51776191)。
文摘This study is concerned with the experimental and theoretical investigation of the combustion instabilities in a premixed swirl combustor.It is focused on the effects of the swirl mixing distance on the intrinsic thermoacoustic mode.The swirler as an origin of the swirling flow is also the source of the flow disturbance,which has effects on the flame response.The location of the swirler is varied in the experiment to study the effect on combustion instabilities and flame transfer functions.A low order model is built to analyze the thermoacoustic instabilities of the combustion system.The experimental results show that the ITA switches from an unstable state to a stable state as the swirl mixing distance changes with an increment of 15 mm;while the instability of the quarter-wave mode is not varied.The measured Flame Transfer Functions(FTFs)show that the gain curves of the frequency-dependent FTFs seem to be stretched or compressed with the modulation of the swirler position,which has effects on frequencies and instabilities of thermoacoustic modes.With the low order model,the effects of flame response on combustion instabilities are analyzed and the flame dominant nature of the ITA mode is confirmed.
基金This study was supported by the National Natural Science Foundation of China(Nos.62022037,61775028,81571722,61528401 and 61921002)Guangdong province(2019ZT08Y191)+1 种基金Shenzhen Science and Technology Program(KQTD20190929172743294)Startup grant from Southern University of Science and Technology.
文摘Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues are complicated,thus result in severe artifacts.In this study,to reveal the underlying mechanisms of artifacts,we deeply investigate the distribution of specific absorption rate(SAR)inside tissue-mimicking phantoms with varied morphological features using both mathematical simulations and corresponding experiments.Our simulated results,which are confirmed by the associated experimental results,show that the SAR distri-bution highly depends on the geometries of the imaging targets and the polarizing features of the microwave.In addition,we propose the potential mechanisms including Mie-scattering,Fabry-Perot-feature,small curvature effect to interpret the diffraction effect in different scenarios,which may provide basic guidance to predict and distinguish the artifacts for TAI in both fundamental and clinical studies.
基金supported by the National Basic Research Program of China(2011CB910402,2010CB732602)the Program for Changjiang Scho-lars and Innovative Research Team in University(IRT0829)+3 种基金the National Natural Science Foun-dation of China(81127004,11104087)the Foun-dation for Distinguished Young Talents in Higher Education of Guangdong,China(LYM10061)the Specialized Research Fund for the Doctoral Program of Higher Education(20114407120001)the Science and Technology Project of Bejing,China(2012J4100114).
文摘Microwave induced thermoacoustic tomography(TAT)is a noninvasive,nonionizing modality based on the inherent differences in microwave absorpt ion of malignant breast tissues and normal adipose dominated breast tissues.In this paper,a TAT system based on multielement acquisition system was built to receive signals.Slices from different layers in the sample were composed into a three-dimensional(3D)volume.Based on the 3D volume,inherent differences in microw ave absorption bet ween different biological tisues can be converted into structure information.Our experimental results of some minicked and human tumors indicate that TAT may potentially be used to detect early-stage breast cancers with high contrast.
