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Capacitive micromachined ultrasound transducers for intravascular ultrasound imaging

Microsystems & Nanoengineering 2020年第1期6卷 565-577页

作者： Jiaqi Wang Zhou Zheng Jasmine Chan John T.W.Yeow Department of Systems Design Engineering Faculty of EngineeringUniversity of WaterlooWaterlooON N2L 3G1Canada

Intravascular ultrasound(IVUS)is a burgeoning imaging technology that provides vital information for the diagnosis of coronary arterial diseases.A significant constituent that enables the IVUS system to attain high-resolution images is the ultrasound transducer,which acts as both a transmitter that sends acoustic waves and a detector that receives the returning signals.Being the most mature form of ultrasound transducer available in the market,piezoelectric transducers have dominated the field of biomedical imaging.However,there are some drawbacks associated with using the traditional piezoelectric ultrasound transducers such as difficulties in the fabrication of high-density arrays,which would aid in the acceleration of the imaging speed and alleviate motion artifact.The advent of microelectromechanical system(MEMS)technology has brought about the development of micromachined ultrasound transducers that would help to address this issue.Apart from the advantage of being able to be fabricated into arrays with lesser complications,the image quality of IVUS can be further enhanced with the easy integration of micromachined ultrasound transducers with complementary metal-oxide-semiconductor(CMOS).This would aid in the mitigation of parasitic capacitance,thereby improving the signal-to-noise.Currently,there are two commonly investigated micromachined ultrasound transducers,piezoelectric micromachined ultrasound transducers(PMUTs)and capacitive micromachined ultrasound transducers(CMUTs).Currently,PMUTs face a significant challenge where the fabricated PMUTs do not function as per their design.Thus,CMUTs with different array configurations have been developed for IVUS.In this paper,the different ultrasound transducers,including conventional-piezoelectric transducers,PMUTs and CMUTs,are reviewed,and a summary of the recent progress of CMUTs for IVUS is presented.

关键词： piezoelectric transducers thereby

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Hybrid calibration method for six-component force/torque transducers of wind tunnel balance based on support vector machines

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Chinese Journal of Aeronautics 2013年第3期26卷 554-562页

作者： Ma Yingkun Xie Shilin Zhang Xinong Luo Yajun State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace Xi'an Jiaotong University

A hybrid calibration approach based on support vector machines （SVM） is proposed to characterize nonlinear cross coupling of multi-dimensional transducer. It is difficult to identify these unknown nonlinearities and crosstalk just with a single conventional calibration approach. In this paper, a hybrid model comprising calibration matrix and SVM model for calibrating linearity and nonlinearity respectively is built up. The calibration matrix is determined by linear artificial neural network （ANN）, and the SVM is used to compensate for the nonlinear cross coupling among each dimension. A simulation of the calibration of a multi-dimensional sensor is conducted by the SVM hybrid calibration method, which is then utilized to calibrate a six-component force/torque transducer of wind tunnel balance. From the calibrating results, it can be indicated that the SVM hybrid calibration method has improved the calibration accuracy significantly without increasing data samples, compared with calibration matrix. Moreover, with the calibration matrix, the hybrid model can provide a basis for the design of transducers.

关键词： Hybrid Multi-dimensional Nonlinear coupling Support vector machines transducers

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Analysis of acoustic directivity of spherical cap transducers

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Chinese Journal of Acoustics 2019年第2期38卷 -页

作者： XIA Jindong HUANG Haining ZHANG Chunhua Institute of Acoustics Chinese Academy of Sciences University of Chinese Academy of Sciences

In order to study the acoustic radiation from the spherical cap transducer,a theoretical model is used by solving the wave equation in spherical coordinates using the method of separation of variables,based on the spherical harmonic Fourier transform and boundary condition.The calculation formulas for the far field radiated pressure and directivity of spherical cap are derived.Some theoretical results are presented in the form of far-field directivity patterns of the spherical cap transducer for various polar angles of the spherical cap,radii of sphere baffle and operating frequencies.Both the diameter of the sphere baffle and the wavelength determine the directivity of acoustic radiation from a spherical cap.When the frequency is lower or the wavelength is longer than the diameter of the sphere baffle,the acoustic radiation from a spherical cap is omnidirectional.With the increase of the frequency or the diameter of the sphere baffle,the acoustic radiation from a spherical cap is more directional and the beamwidth more tends to spherical cap angle.Furthermore,the ripple in the beam is more obvious.The high frequency spherical cap transducer was fabricated and the directivity pattern was tested and the measurement data is shown to coincide with the theoretical results.This research can provide a guideline for designing the spherical cap transducers and arrays.

关键词： Analysis of acoustic directivity of spherical cap transducers

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A review of high-intensity focused ultrasound as a novel and non-invasive interventional radiology technique

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Journal of Interventional Medicine 2022年第3期5卷 127-132页

作者： Ruihong Yao Jihong Hu Wei Zhao Yongde Cheng Chaofan Feng Medical Imaging Department The First Affiliated Hospital of Kunming Medical UniversityKunmingChina Editorial Board of the Journal of Interventional Medicine Shanghai China

High-intensity focused ultrasound(HIFU) is a non-invasive interventional radiology technology, which has been generally accepted in clinical practice for the treatment of benign and malignant tumors. HIFU can cause targeted tissue coagulative necrosis and protein denaturation by thermal or non-thermal effects, guided by diagnostic ultrasound or magnetic resonance imaging, without destruction of the normal adjacent tissue, under sedation or general anesthesia. HIFU has become an important alternative to standard treatments of solid tumors, including surgery, radiation, and medications. The aim of this review is to describe the development, principle, devices, and clinical applications of HIFU.

关键词： HIFU Clinical application transducers Tumor

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Quiet Zone Design in Diffuse Fields Using Ultrasonic transducers

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Journal of Applied Mathematics and Physics 2015年第2期3卷 247-253页

作者： Wen-Kung Tseng Graduate Institute of Vehicle Engineering National Changhua University of Education Changhua City Taiwan

This paper presents quiet zone design using ultrasonic transducers for local active control in pure tone diffuse fields. Most of researches in local active noise control used conventional loudspeakers for the secondary sources to produce quiet zones. Recently ultrasonic transducers have been used for the secondary sources to control the plane wave in active noise control. However there is no research related to active noise control in diffuse fields using ultrasonic transducers. Therefore this study uses ultrasonic transducers for the secondary sources to control the diffuse fields. The quiet zone produced using ultrasonic transducers in single tone diffuse fields has been analyzed through simulations in this work. The results showed that quiet zones created using ultrasonic transducers were larger than those created using conventional loudspeakers. This is due to the fact that the audible sound pressure produced by the ultrasonic transducers decays slowly with the distance. Therefore the secondary field created by an ultrasonic transducer could fit the primary field better and the larger zone of quiet could be obtained using the ultrasonic transducer. Also the audible sound produced by the ultrasonic transducers is directional;therefore the sound pressure amplification outside the quiet zones was lower.

关键词： Quiet Zone Design Ultrasonic transducers Local Active Control Diffuse Fields Plane Wave

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Focusing Ultrasonic Field of Holed Cap Spherical Shell Transducer Using the Spheroidal Beam Equation

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Chinese Physics Letters 2002年第3期19卷 355-357页

作者：夏荣民寿文德等 DepartmentofBiomedicalEngineering ShanghaiJiaoTongUniversityShanghai200030

A large aperture transducer with an inner hole has been used to validate the feasibility of using the spheroidal beam equation to solve the acoustic field of the inner holed transducer. The numerical results of severa... 详细信息

关键词： transducers

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Ultrasonic Wireless Communication Through Metal Barriers

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Sound & Vibration 2019年第2期53卷 2-15页

作者： Jianing Zhang Ziying Yu Hengxu Yang Ming Wu Jun Yang State Key Laboratory of Acoustics and Key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijingChina University of Chinese Academy of Sciences BeijingChina

Ultrasound can be used as a carrier to realize wireless communication to and from a metal-enclosed space,which has the characteristics such as immunity to the electromagnetic shielding effect and non-destructive penetration of metal obstacles.This paper firstly reviews the previous studies in the field of ultrasonic wireless communication through metal barriers,and summarizes their achievements and the existing problems.Secondly,an overview of the research methods involved in studying the characteristic of acoustic-electric channel is presented,and the principles are introduced for the actual measurement method,equivalent circuit method,ABCD parameter method,finite element analysis method and time-domain finite difference method.Then,an overview of the communication algorithms are presented such as orthogonal frequency division multiplexing(OFDM),single-carrier frequency domain equalization and multiple input multiple output OFDM.Finally,the potential future study are proposed in light of the trend of development and unsolved problems.

关键词： Wireless communication ultrasound piezoelectric transducers metal barriers

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ULTRASONIC INVESTIGATION OF BLOOD

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Chinese Journal of Acoustics 1989年第2期8卷 170-177页

作者： Feng, Ruo Nanjing Univ Nanjing China

Ultrasonic biophysicists and physicians have continuously exhibited great interest in studying the ultrasonic properties of blood. It is shown that compressibility of red cell appears to be inversely proportional with its hemoglobin content. Among ultrasonic attenuation produced by red cell structure level in blood, absorption of red cell plays predominant role, viscous relative motion loss accounts for less than 15%, and cell scattering contribution is negligible. The coagulation process of blood is accompanied by significant change of sound parameters. The marked advantage has been found in test of blood coagulation process by using ultrasonic technique than the traditional viscous method. Blood coagulation causes sound attenuation, sound backscattering and nonlinearity parameter B/A to increase, but the attenuation frequency dependence hardly changes. All of these findings are of an important realistic significance for developing ultrasonic medicine.

关键词： Mathematical Models transducers Applications Ultrasonic Waves Velocity Ultrasonics Applications

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Flight Vehicle Performance and Aerodynamic Control

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丛书名： AIAA Education Series

2001年

作者： Frederick O. Smetana

ISBN: (数字)9781600861857

ISBN: (纸本)9781563474637

Flight Vehicle Performance and Aerodynamic Control is designed to serve as a text for either an 11-week or a 16-week course at the sophomore level. It explains typical methods used to estimate aircraft performance, the theoretical basis of these methods, and how various parameters derived from the aircraft geometry can be used to estimate the requirements of control surfaces and the aerodynamic forces required to actuate these surfaces. This book includes time-tested computer programs that perform the analyses in a manner that reduces student error and improves result accuracy. Because the source code is given, users with a FORTRAN compiler can modify the program to suit particular needs. The major advantage of the software is that more realistic problems may be treated and the effects of parametric programs are more accurate than calculators. The programs are available as executables for Windows machines as well as in ASCII source code versions that can be readily compiled and then executed on Unix, Linux, and Macintosh machines, and on mainframes.

关键词： Aerodynamic Performance Aerodynamics Aeronautical Engineering Aeronautics Aerospace Engineering Aerospace Sciences Aircraft Carriers Aircraft Components and Structure Aircraft Conceptual Design Aircraft Design Aircraft Dynamic Modes Aircraft Engines Aircraft Instruments Aircraft Operations Aircraft Operations and Technology Aircraft Performance Aircraft Stability and Control Aircraft Stabilizer Aircraft Wing Components Aircraft Wing Design Aircrafts Airfoil Airfoil Nomenclature Airspeed Astrodynamics Astronautics Atmospheric Science Aviation Aviation Authorities and Organizations Aviation Safety Avionics Civil Aviation Combat Aircraft Combustion Chambers Compressors Energy Energy Conversion Energy Economics Energy Forms Energy Forms, Production and Conversion Energy Production Fixed-Wing Aircraft Flight Control Surfaces Flight Dynamics Flight Mechanics Flight Test Flight Training Fluid Dynamics Fluid Flow Properties Fluid Mechanics Fossil Fuels Fuel Injection Fuels Gas Turbine Guidance, Navigation, and Control Systems Heat Engines Helicopters Hydraulics Hydrodynamics Ignition Systems Jet Aircraft Liquid Fuels Longitudinal Static Stability Military Airbases Military Aircraft Military Aviation Non-Renewable Energy Petroleum Power Station Propulsion and Power Reciprocating Engine Rocket Engine Rocketry Rotorcrafts Sensors Short Takeoff and Landing Takeoff and Landing transducers Turbines Turbomachinery Unmanned Aerial Vehicle Wind Engineering Wind Tunnels Wind Turbine Wing Configurations Wing Planforms

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Paramyxovirus evasion of innate immunity: Diverse strategies for common targets

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World Journal of Virology 2013年第2期2卷 57-70页

作者： Michelle D Audsley Gregory W Moseley Department of Biochemistry and Molecular Biology Monash University

The paramyxoviruses are a family of > 30 viruses that variously infect humans, other mammals and fish to cause diverse outcomes, ranging from asymptomatic to lethal disease, with the zoonotic paramyxoviruses Nipah and Hendra showing up to 70% case-fatality rate in humans. The capacity to evade host immunity is central to viral infection, and paramyxoviruses have evolved multiple strategies to overcome the host interferon(IFN)-mediated innate immune response through the activity of their IFN-antagonist proteins. Although paramyxovirus IFN antagonists generally target common factors of the IFN system, including melanoma differentiation associated factor 5, retinoic acid-inducible gene-I, signal transducers and activators of transcription(STAT)1 and STAT2, and IFN regulatory factor 3, the mechanisms of antagonism show remarkable diversity between different genera and even individual members of the same genus; the reasons for this diversity, however, are not currently understood. Here, we review the IFN antagonism strategies of paramyxoviruses, highlighting mechanistic differences observed between individual species and genera. We also discuss potential sources of this diversity, including biological differences in the host and/or tissue specificity of different paramyxoviruses, and potential effects of experimental approaches that have largely relied on in vitrosystems. Importantly, recent studies using recombinant virus systems and animal infection models are beginning to clarify the importance of certain mechanisms of IFN antagonism to in vivo infections, providing important indications not only of their critical importance to virulence, but also of their potential targeting for new therapeutic/vaccine approaches.

关键词： Paramyxoviridae Innate immunity Signal transducers and activators of transcription 1 Signal transducers and activators of transcription 2 Melanoma differentiation associated factor 5 Retinoic acid-inducible gene-I

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