bluuebunny/crossref_metadata_2025 huggingface dataset:
Optically transparent gel for experimentally mimicking cavitation enhanced ultrasonic heating of tissue
Authors: Asai Ayumu , Moriyama Tatsuya , Yoshizawa Shin , Umemura Shin-ichiro
Published: April 2012

High intensity focused ultrasound (HIFU) is a noninvasive method for cancer treatment. However, there is a problem of a long treatment time for treating a large volume. It is known that cavitation bubbles, generated by extremely high intensity ultrasound pulses, enhance the heating effect of HIFU. In order to investigate a cavitation-enhanced highly-efficient method of HIFU, an optically transparent gel with both ultrasonic absorption and cavitation threshold similar to biological tissue is being developed. Such a polyacrylamide (PAA) gel was successfully produced by controlling the concentrations of both acrylamide and albumin. The effect of cavitation bubbles enhancing the ultrasonic heating was measured using the gel by exposing it to HIFU. The effect was considered in the bio-heat transfer equation (BHTE) by increasing the ultrasonic absorption coefficient in the region of the cavitation, whose volume was determined by high-speed-camera observation. The absorption coefficient was calculated by fitting between the temperature rise curves at the focal point in the experiment and numerical simulation. The simulation using the obtained absorption coefficients of the gel with and without cavitation showed overall agreement with the experiment using the gel. The developed gel and method will be useful for further development of this HIFU method.
Measurement of high intensity focused ultrasound fields using a combined measurement and SBE modeling approach
Authors: Chen Tao , Fan Tingbo , Xia Liyang , Hu Jimin , Liu Ru , Zhang Dong
Published: April 2012

Acoustic characterization of high Intensity focused ultrasound (HIFU) is essential for its development in clinical treatment. In the present study, a combined measurement and modeling approach is proposed. At relative low amplitude excitation, acoustic measurement in water is performed to calibrate the transmitter parameters; then the acoustic fields of HIFU transmitter can be predicted based on the SBE model. To verify the validity of this approach, a 1 MHz HIFU transmitter with large aperture is utilized in the study, and the HIFU field is measured by a HFO-660 fiber optic hydrophone. This study is helpful for the accurate characterization of HIFU fields. [This work is supported by the National Basic Research Program 973 (Grant No. 2011CB707900) from Ministry of Science and Technology, China, National Natural Science Foundation of China (10974093 and 11011130201), and the Fundamental Research Funds for the Central Universities (Grant Nos. 1103020402, 1116020410 and 1112020401)]
Activities of the cavitation bubbles in the wake of a shock pressure pulse recorded by an optical fiber hydrophone
Authors: Choi Min Joo , Cho Sung Chan , Kang Gwansuk , Coleman Andrew J.
Published: April 2012

The shock pulse used in an extracorporeal shock wave treatment (ESWT or ESWL) has a large negative pressure (< -5MPa) which can always produce acoustic cavitation. The resulting cavitation bubbles are known to play an important role in therapeutic effects, however, the bubble activities are not readily measurable yet. The present study considered a weird tail after the negative peak in the time history of pressure sensed by an optical fiber hydrophone which was usually abandoned in typical pressure field measurements. A shock pressure pulse in water causes change of mass density which modulates the optical refractive index. The change of the refractive index can be measured by the light reflection at the tip of the glass fiber submerged in water. The loss of water contact by cavitation bubbles at the fiber tip leads to an abnormal increase of high reflection which is clearly identified. This suggests that the weird tail of the hydrophone signal beyond the negative cycle of a shock pulse is closely related to the extent of the cavitation bubbles. This was experimentally validated in the shock wave field which was produced in water by a clinical ESWT system (ShineWave, HnT Medical, Republic of Korea) with an optical hydrophone (FOPH2000, RP Acoustics, Germany). Keywords: shock pressure pulse, ESWT, ESWL, cavitation, bubbles, optical fiber hydrophone
A novel formulation of lipid microbubbles coated with stearic acid modified polyethylenimine to enhance ultrasound-mediated gene delivery in vitro
Authors: Jin Qiaofeng , Wang Zhiyong , Yan Fei , Deng Zhiting , Li Lu , Zheng Hairong
Published: April 2012

The aim of this study was to assess the properties of a new designed cationic microbubbles as gene carriers and the relative gene transfection efficacy with ultrasound triggered microbubble destruction. Polyethylenimine as a high efficient gene transfection agent has higher cell toxicity with molecular weight increasing. Stearic acid was used to modify branched polyethylenimine to change its hydrophilic properties so that it can be assembled onto the lipid shell of the microbubbles and simultaneously decrease its cell toxicity. Cationic microbubbles was prepared by encapsulating perfluoropropane into phospholipids and stearic acid modified polyethylenimine hybrid shell using mechanical vibration method. The mean, median size and zeta potential of the microbubbles were measured 1.84±1.62um, 1.60um and 54mv respectively. Hoechst 33258 was used to stain the green fluorescent protein reporter plasmid which was charge-coupled to cationic microbubbles, and microbubbles was observed emitting blue light under a fluorescence microscope. About 4ug plasmid loaded by 108 microbubles that contain 5% mole ratio stearic acid modified polyethylenimine was measured by gel electrophoresis. A 1.25MHz single element transducer was used to mediate the gene transfection to MCF-7 cell by using the cationic microbubbles and enhancement of green fluorescent protein expression was observed.
Cytotoxicity enhancement of DOX-liposome-containing microbubbles combined with ultrasound to the multi-drug resistant cell
Authors: Deng Zhiting , Yan Fei , Li Lu , Jin Qiaofeng , Li Fei , Zheng Hairong
Published: April 2012

Multidrug resistance (MDR) in cancer cells is a significant obstacle to successful cancer therapy. Doxorubicin (DOX) is very active chemotherapeutic agent for the treatment of breast cancer and the efficacy of DOX is also restricted by multidrug resistance.Ultrasound (US) targeted destruction of drug loaded microbubbles (MBs) is gaining more and more attention as a promising strategy for locally drug delivery. In this article, through avidin–biotin binding of DOX-containing liposomes to the microbubbles, we developed DOX-liposome-containing microbubbles in order to investigate its effect of enhancing cellular uptake and cytotoxicity of DOX against drug-resistant cancer cells. The results demonstrated that treatment of cells with ultrasound and DOX-liposome-containing microbubbles caused a significant higher drug uptake in DOX-resistant MCF-7 cells, compared with control (DOX-liposome). More importantly, a significant enhancement of tumor growth inhibition against DOX-resistant MCF-7 cells was found when using the drug-liposome-containing microbubbles combined with ultrasound.Compared with DOX-liposome treatment, the cytotoxicity effect was greatly enhanced from 21% to 60%. By further mechanism study, DOX-loaded microbubbles plus ultrasound induced significant apoptosis in MDR line of MCF-7 cells.
The estimation of bone microstructure using characteristic refraction of fast wave
Authors: Mizuno Katsunori , Yamashita Keisuke , Fujita Bunri , Matsukawa Mami
Published: April 2012

Two-wave phenomenon, known as the wave propagation of fast and slow waves, has been observed in the cancellous bones when the ultrasonic wave propagates along the trabecular alignment. It is also reported that the acoustical parameters of the fast and slow waves related to not only bone mass but also bone microstructure. In this study, the characteristic refraction of the fast wave was focused, and a method was proposed to estimate the bone microstructure. Cylindrical specimens of cancellous bone were obtained from a bovine femur. Using a conventional ultrasound pulse technique, the receiver was moved to investigate the ultrasonic fields after the propagation in the specimen. In addition, the structure of the specimen was estimated by using the X-ray micro CT. The fast wave showed the “apparent refraction” following the trabecular alignment in the specimen, which was not observed from the slow wave behavior. The ultrasonic field after the sample propagation changed reflecting the trabecular alignment, which gives us the information of microstructure of cancellous bone. Especially, the evaluation of fast wave propagation can be useful for the estimation of bone microstructure and will support the ultrasound bone assessment in the in vivo situation.
Ultrasound propagation in trabecular bone: a numerical study of the influence of micro-cracks
Authors: Callé Samuel , Moreschi Hélène , Defontaine Marielle
Published: April 2012

The accumulation of microdamage in trabecular bone tissue is suspected of being a predictive indicator of osteoporosis diagnosis. To quantify this microdamage, the Dynamic AcoustoElastic Testing (DAET) method measures the time of flight (TOF) and amplitude variations of transmitted ultrasound (US) pulses, while the bone sample is submitted to a low frequency pressure (opening/closing of microcracks). However, DAET is both sensitive to viscoelastic properties changes and microcracks density. To estimate the microcraks density contribution, a numerical approach is proposed, allowing simulations of different levels of microdamaged media. A 2D pseudo-spectral time domain numerical model was then developed to simulate linear wave propagation in heterogeneous solids including thermo-viscous attenuation. The influence of the microcracks number, size and orientation on the US TOF and amplitude was particularly investigated. Results are discussed and compared with experimental data extracted from DAET measurements in trabecular bone samples.
Estimation of the radiation force on implanted medical devices: a theoretical study
Authors: Callé Samuel , Ferin Guillaume , Remenieras Jean-Pierre
Published: April 2012

Implantable medical devices, such as pacemaker or insulin pump, are more and more used to extend or improve the quality of life. The radiation force could actually be a solution to remotely control these devices in different applications (energy supply, drug delivery control...). The aim of this work is to quantify the amplitude and spatial repartition of the ultrasound radiation force which could be applied on such a system. Reflection of the incident acoustic beam at the interface (surface force) and attenuation of the US beam along the wave path (body force) both contribute to this force. In this study, these force contributions have been calculated in the case of a device implanted one centimeter under the skin. First, a heterogeneous axisymetric pseudo-spectral time domain method is used to estimate the ultrasound particle velocity and acoustic pressure (amplitude, spatial repartition) inside the device and at the interface. These parameters are then inserted in analytical expressions to precisely calculate the force applied on the implantable device. Surface and body forces contributions have been analyzed and the global force estimated for two configurations of 5 MHz transducers (plane and focused) and two types of device mechanical characteristics (semi-rigid and rigid).
Effects of eccentric acoustic source on the amplitude and arriving time of the first arrival in cased boreholes
Authors: Chen Dehua , Wang Xiuming , Zhang Hailan , Lin Weijun
Published: April 2012

The acoustic fields excited by eccentric acoustic source in cased boreholes bonded by cements with different densities are simulated numerically using 2.5-dimension (2.5D) finite-difference method (FDM). The effects of the source eccentricity on the amplitude and arriving time of the first arrival (FA) in the full waveform are investigated. The numerical results show that the amplitude of the FA will decrease quickly and its arriving time will go ahead as the source eccentricity increases. The change of the arriving time can be estimated approximatively using geometrical acoustics theory. As the eccentric distance of the acoustic source reaches 1/4 of the borehole radius, the amplitude of the FA will reduce to below 20% of the centered case. The quantitative varying trends of the amplitude and arriving time of the FA are the same both in the free pipe and in boned pipe. Therefore, during the cementing evaluation, the tool's eccentricity should be estimated through the arriving time of the first arrival, and then its amplitude should be corrected according the eccentricity. Otherwise, when the interface between the steel pipe and the cement is not boned well, the over-optimistic cementing evaluation could be led to because of the large reduction of the FA's amplitude aroused by eccentric acoustic source.
Phase spectrum correlation method to extracting anisotropic parameters from four-component dipole waveforms
Authors: Che Xiao-Hua , Wang Rui-Jia , Qiao Wen-Xiao
Published: April 2012

The anisotropy parameters extracted from 4-component dipole waveforms are always affected by dispersion of mode waves, the distribution of stress, the invasion zone and so on. It is impossible to extract the real anisotropy parameters in time domain process. In this paper, we develop a phase spectrum correlation method (PCM) to extract the anisotropic parameters in frequency domain. The PCM searches the real slowness difference of fast and slow flexural waves by comparing the coherence of phase spectra of the fast wave and slow wave. Contrast to the traditional time domain method, this method offers not only the normal shear anisotropy parameters but also an anisotropic map, an anisotropic monitor curve and so on, which can make the interpretation conclusion more reliable. The PCM is verified by both synthesized multi-pole array waveforms and experiment data. The results show that this method is fast and stable for anisotropy analysis.
Research on sensitivity of dipole receiving transducers
Authors: Che Chengxuan , Wang Xiuming , Chen Dehua , Cong Jiansheng
Published: April 2012

The dipole receiving transducers play an important part in Cross-dipole array acoustic well logging tools. It is necessary to study the properties of the dipole receiving transducer, especially the sensitivity of it. In this paper, transducers in two ways of wiring, including parallel connection and series connection, were considered numerically and experimentally. The sensitivities obtained by numerical and experimental method respectively were contrasted. The results show that as a receiving transducer, the receiving sensitivity in series connection is higher, which can guide us in the dipole receiving transducer design. Keywords: dipole, receiving sensitivity, receiving transducer
Numerical simulation of noise induced by contact between two rough surfaces
Authors: Viet Hung Dang , Alain Le Bot
Published: April 2012

The roughness noise generated during the sliding of two rough surfaces under light load is a complex phenomenon which is relevant to mechanics of multi contact interfaces. The objective of this study is to estimate the statistical properties of the local dynamic inaccessible to measurement (shock rate, shock duration, probability density function of local forces). A numerical approach based on a modal development has been proposed with two algorithms, penalty or Lagrange multipliers, to compute the contact force and six time integration schemas. The validity and the efficiency of this approach is discussed. In terms of CPU time, the comparisons show that the proposed approach is better than the classical finite element method. The analysis also shows that the source mechanism of roughness noise is the presence of shocks occurring between antagonist asperities transforming a part of kinetic energy into acoustical energy. It is also shown that roughness noise level is simultaneously an increasing function of the logarithm of the surface roughness and the sliding speed. Microscopically, the shock rate, the shock duration, the power being injected by individual shocks are correlated with these two macroscopic parameters.
Experimental investigation of elastic modes localized within a defect in a phononic slab
Authors: Bonello Bernard , Boyko Olga , Rénier Mathieu , Marchal Rémi
Published: April 2012

Heterostructures with periodic variations of both their optical refractive index and their elastic properties may induce band gaps for both electromagnetic and acoustic waves. As a consequence of the expected enhancement of the acousto-optic interactions, these artificial materials, called “PhoXonic crystals”, are of primary interest for new sensing applications. In this context, we have experimentally studied the localization of elastic energy within a defect. The heterostructures consist in arrays of voids periodically drilled throughout silicon plates (graphite symmetry) and featuring a vacancy, or a line of vacancies. An all-optical experimental technique allows for both the generation and the detection of the elastic guided waves. The non-contact probing allows one to monitor the displacements field inside the defects. First, we have measured the dispersion of broad band elastic waves guided in between the free surfaces of the sample. Then narrow band elastic guided waves, whose central frequency corresponds to resonance modes of the cavity are generated. The optical probe allows for the measurement of the out-of-plane displacements associated to the elastic modes localized within the cavity or transmitted through the phononic structure. The spatial distribution of elastic energy inside the cavity is measured and compared with numerical predictions. This work is supported by the European Community through the FET-Open project “TAILPHOX” (Grant No. 233883).
Negative stiffness metamaterials and periodic composites
Authors: Haberman Michael R. , Klatt Timothy D. , Wilson Preston S. , Seepersad Carolyn
Published: April 2012

The creation of negative stiffness (NS) metamaterials is of interest for damping treatments, vibration isolation, and even more exotic applications such as acoustic lenses displaying negative refraction. This work will present ongoing efforts to produce NS metamaterial elements that rely on a bistable microscale geometry that leads to NS under quasistatic loading conditions. A candidate bistable microstructure employing thermal mismatch will be introduced along with finite element simulations predicting its full stiffness tensor. Effective medium modeling will show the broadband utility of these elements to enhance acoustic absorption for low volume fraction bi-material composites. The special case of a bi-material periodic composite containing NS inclusions will then be explored. It will be shown that a periodic composite containing NS inclusions permits the simultaneous elimination of the acoustic branch and reduction of the lower frequency of the optical branch passband to arbitrarily low frequencies. Physical interpretations of these results and potential applications will be discussed. This material is based upon work supported by the U. S. Army Research Office under grant number W911NF-11-1-0032.
An investigation on polymer modulus test using laser-based finite element method
Authors: Yin Yao , Liu Bi-Long , Bai Guo-Feng , Zhou Cheng-Guang , Liu Ke
Published: April 2012

A laser-based finite element(FEM) method for determination of the complex modulus of visco-elastic material is re-examined in this paper. The parametric sensitivity on FEM inverse algorithm and the applicable scope on material damping are investigated. Measurement of time-temperature superposition (TTS) has been achieved at the developed test systems. The discrepancy is within 10% in comparison with the measured date from a commercial Dynamic Mechanical Analysis (DMA), and this validates the accuracy of the developed test system.
An effective medium approach and elastic metamaterials
Authors: Peng Pai , Wu Ying
Published: April 2012

Metamaterials are artificial materials that are designed to manipulate waves as desired. The unusual properties of a metamaterial are derived from its complex building blocks which make the development of effective medium theory challenging. In this work, effective medium parameters, such as anisotropic mass density and moment of inertia, are obtained for metamaterials based on mechanical models consisting of masses and springs. The effective moment of inertia is capable of providing a clear understanding of the mechanism of rotational modes which are widely observed in both two- and three-dimensional phononic crystals and metamaterials. The effective medium descriptions are served as guidance in the engineering of the building block to achieve rich resonances that lead to intriguing properties of the metamaterial. (Support of this work comes from KAUST Start-up Package)
Noise improvement measures of Hong Kong International Airport
Authors: Hung Tim Wan Choi , Lee Chee Kwan
Published: April 2012

Hong Kong International Airport (HKIA) at Chek Lap Kok was designed in the early 90s and commenced operation in 1998 to meet Noise Exposure Contour (NEF) 25 standard under the Hong Kong Planning Standards and Guidelines. No new noise sensitive receiver is to be located within the NEF 25 contour. The NEF 25 contour of the airport covers largely sea areas. Only a small number of acoustically insulated village houses close to the airport marginally lie within the NEF25 contour. Despite all these planning efforts, aircraft noise from the airport operation still triggered considerable complaints from public about aircraft noise nuisance upon the airport came into operation in 1998. To address the nuisance, the Civil Aviation Department and the Environmental Protection Department of the Government of The Hong Kong Special Administrative Region implemented a number of improvement measures to reduce noise disturbance caused by these aircrafts on areas near the flight paths. This paper gives a retrospective view of aircraft noise problem in Hong Kong and experience gained after its operation.
Noise around Suvarnabhumi Airport
Authors: Lertsawat Krittika , Kovudhikulrungsri Lalin , Phoolsawat Surocha , Suksaard Tanaphan
Published: April 2012

The noise levels in the vicinity of the Suvarnabhumi Airport (NBIA) were reported by the relevant authorities, including the noise levels before and after the opening of it since 2006. The overview of noise around NBIA will be illustrated in this paper. Meanwhile, the new guidelines on the airport noise management are under the consideration and development by the Pollution Control Department in corporation with other relevant agencies in compatible with the international recommendations on ISO 20906:2009, ISO 1996-1:2003, and ISO1996-2:2007. It should be into active within the next two years for applying to the airport projects in Thailand.
Change of noise index and guideline values for airport noise in Japan
Authors: Yamada Ichiro
Published: April 2012

In Japan, mitigation of noise impact around airport has been promoted within the frame work of environmental noise measures, based on a noise guideline for aircraft noise enacted in 1974. Prompted by a subtle contradiction on noise index, the guideline was revised in 2007 and is planned to be enforced from April, 2013. The new guideline uses Lden as the cumulative noise evaluation index, instead of the conventional WECPNL. This paper explains details of revision of the guideline and the way to have specified new standard values. It also discusses the relationship of Lden with WECPNL at various airports in Japan.
Vocal fold vibratory and acoustic features in fatigued Karaoke singers
Authors: Wang Gaowu , Lo Andy , Chan Karen , Kong Jiangping , Yiu Edwin
Published: April 2012

Karaoke is a popular singing entertainment particularly in Asia and is gaining more popularity in the rest of world. In Karaoke, an amateur singer sings with the background music and video (usually guided by the lyric captions on the video screen) played by Karaoke machine, using a microphone and an amplification system. As the Karaoke singers usually have no formal training, they may be more vulnerable to vocal fatigue as they may overuse and/or misuse their voices in the intensive and extensive singing activities. It is unclear whether vocal fatigue is accompanied by any vibration pattern or physiological changes of vocal folds. In this study, 20 participants aged from 18 to 23 years with normal voice were recruited to participate in an prolonged singing task, which induced vocal fatigue. High speed laryngscopic imaging and acoustic signals were recorded before and after the singing task. Images of /i/ phonation were quantitatively analyzed using the High Speed Video Processing (HSVP) program (Yiu, et al. 2010). It was found that the glottis became relatively narrower following fatigue, while the acoustic signals were not sensitive to measure change following fatigue. [Supported in part by HKRGC-GRF#757811]
Body radiation patterns of singing voices
Authors: Takada Orie , Bader Rolf
Published: April 2012

Most musical instruments exhibit complex patterns of sound radiation, which change with direction, played pitch, and many other factors. The same holds true for the body of a singer, regarded as an instrument, singing with her or his voice but activating also parts of the chest, neck, face, etc. The study examines differences in sound radiation of different body parts between various techniques and singing styles. Radiation patterns of the classical singing voice as well as non-classical singing styles, the Musical style, overtone singing, and Pop music, all produced by professional singers, were investigated using a microphone array comprising 128 microphones. The results are visualized displaying the strength of voice radiations and marking areas of radiation of the singer's upper body. The experiment shows that radiation patterns of the singing voice depend on vocal techniques, the vowel employed, and pitch. Additionally accelerometer measurements at lower body parts like the legs or foots show the transmission of the singing vibrations even to these remote body parts.
Changes in the vocal tract shape of sopranos at high pitch
Authors: Takemoto Hironori , Honda Kiyoshi , Saitou Takeshi , Tanabe Yosuke , Kishimoto Hiroko , Kitamura Tatsuya
Published: April 2012

As sopranos increase their fundamental frequency (F0) to sing at higher pitches, they also increase the first resonance frequency (R1) of their vocal tract. This is probably to avoid sudden F0 changes when F0 and R1 cross. It is unclear, however, how sopranos change vocal tract shape to increase R1. Therefore, the vocal tract shapes of two Japanese sopranos during production of the sung vowel /a/ in the modal register (A4 and D5) and in the falsetto register (G5) were measured by MRI. The measured vocal tract shapes were compared with each other and their area functions were extracted to calculate acoustic characteristics. Results showed that changes in the vocal tract shape were small between A4 and D5, while changes were large between D5 and G5. At G5, it was observed in both subjects that the lower jaw opened, the pharyngeal wall and tongue root advanced, and the larynx retracted. In addition, one subject shortened the laryngeal cavity length. All these changes achieved R1 increase, in agreement with the acoustic sensitivity function. Thus, in conclusion, sopranos selectively modified parts of the vocal tract with high sensitivity to R1. This research was partly supported by Kakenhi (Grant Nos. 21500184, 21300071, 22520156).
An active vibration isolation system for an air-compressor in marine applications
Authors: Yang Tiejun , Zhu Minggang , Liu Xueguang , Du Jingtao , Liu Zhigang
Published: April 2012

Similar to a diesel engine, the main vibration sources of an air-compressor are to and fro inertial forces of its piston, rod, and crankshaft. An active vibration isolation system is developed for an air-compressor in a tug boat. This system consists of four inertial actuators and a DSP processor. A four-input and four-output adaptive control strategy is applied and the reference input signal comes from a laser tachometer on the shaft of the motor. The active vibration isolation experiment is conducted in a tug boat when only the air-compressor is working. The experimental results demonstrate that good vibration reductions are obtained at not only error sensor's locations but also the hull under the compressor. Some discussion and conclusions are given at last.
Difference potential based active noise shielding in three dimensional settings
Authors: Lam Yiu Wai , Utyuzhnikov Sergey , Kelly Liam
Published: April 2012

Active noise shielding based on the Difference Potential Method has been developed and validated in previous publications. The key ability of the method, to provide global noise cancellation while automatically preserving wanted sound in multi-connected domains, has been demonstrated clearly in 1D experiments. In this paper, the tests are extended to 3D. The shielded domain is a 1mx1mx1m box with 1-3 sides open. Up to 4 control sources were used on each of the open sides to shield the domain from external noise. Noise attenuation of around 10dB was achieved up to about 350 Hz. The attenuation is lower than the >20dB attenuation achieved in previous 1D experiments. A reason for this is the sensitivity of the cancellation to the positioning of sensors and controls and the physical size of the control sources. Furthermore, up till now the method relies on separate measurements of the total sound field without the control sources. In realistic applications where noise and wanted sound are non-stationary, the total sound field has to be measured in real time with the control sources operating. In such cases a new mathematical formulation is needed, and this paper will discuss how such a solution can be achieved.
Active noise control systems integrated with infant cry detection and classification for infant incubators
Authors: Liu Lichuan , Kuo Kevin
Published: April 2012

Infant incubators are widely used in neonatal intensive care units (NICU) for the pre-term or sick babies. In this paper, we propose an active noise control (ANC) system integrated with infant cry detection and classification function for infant incubators. The incubator ANC system reduces the high noise level which results in numerous adverse health effects for infants, and the cry detector and analyzer monitors the infants' physical conditions using the same ANC system hardware. The infant crying signals picked up by the error microphone of ANC inside the incubator are detected, the signals' features are extracted by using linear prediction coding (LPC), and Mel-frequency cepstral coefficients (MFCC) methods. The database of different signals and their associated infant health features will be established through training phase. The signal classification algorithm is based on shortest distance and Bayesian classifier. Simulation is conducted to evaluate the performance of proposed system using a Giraffe incubator from GE Healthcare. The experiments show that the proposed ANC system can reduce the harmful noise and the cry classification algorithm can recognize infant cries in order to develop the innovative, low cost methods to monitor the infant's health conditions.
Protecting soundscapes in U.S. National Parks: lessons learned and tools developed
Authors: Newman Peter , Fristrup Kurt , Trevino Karen , Lawson Steve , Taff Derrick , Weinzimmer Dave , Archie Tim
Published: April 2012

Researchers and protected area managers' are working together to protect natural soundscapes in U.S. National Parks. In this paper, soundscapes have been defined as the total acoustics environment and includes the sounds of nature and as well as anthropogenic noise (unwanted sounds). In particular, human-caused noise can mask the sounds of nature and detract from the quality of the visitor experience and have negative impacts on wildlife in parks and protected areas. Over the past decade, researchers at Colorado State University have teamed up with the United States National Park Service (USNPS) to explore, build simulation models of, and derive management actions in National Parks in order to protect natural quiet and the soundscapes of national parks. This paper will provide an overview of challenges and successes of these efforts in order to create a list of lessons learned. In particular, results (maps, models and experiments) of studies in Denali National Park, Rocky Mountain National Park Yosemite National Park and Sequoia Kings National Park will be shown and presented in order to show how these data can lead to informed management decision making. This research was funded by the USNPS Natural Sounds Program as well as support from aforementioned parks.
Further research on separating anthropogenic from natural sounds in a park setting
Authors: Gillette Jack , Kemball Jeremy , Schomer Paul
Published: April 2012

This paper is a continuation of work presented last year on this subject. Last year's work involved separating nearly all anthropogenic sound from natural sound except for jet aircraft. This year a method to detect jet aircraft has been developed, so that now one is able to separate all anthropogenic sound from natural sound. Testing of the detection of non-aircraft anthropogenic sound has been continued with a wide body of data. For the detection of anthropogenic sound (other than jet aircraft) we rely on the assumption that nearly all of this sound involves the use of motors and, hence, except for aircraft, creates fundamental tones that are well below 1000 Hz, where as natural sounds (e.g., insects, birds, frogs) nearly always will create tones with fundamental frequencies above 1000 Hz. This paper present the results of the testing for aircraft noise detection and the additional testing of the detection of non-aircraft anthropogenic sound.
Cavitation micro-bubble behavior in ultrasound field for HIFU therapy enhancement
Authors: Matsumoto Yoichiro , Okita Kohei , Takagi Shu
Published: April 2012

The incepted cavitation micro-bubbles at the target tissue are used to enhance tissue heating in High-Intensity Focused Ultrasound therapy. The control of the inertial cavitation is required to achieve the efficient tissue ablation. The high-intensity ultrasound is used to incept a cavitation, so that the duration time is short enough to prevent the tissue coagulation. The low-intensity ultrasound follows just after the high-intensity ultrasound to continuously drive the cavitating micro-bubbles and coagulate the tissue. Following the experiment, we simulate the focusing of ultrasounds through a mixture containing micro-bubbles with considering the size and number density distributions in space. The numerical simulation shows that the heating region coincides with the cavitation incepted region by high-intensity ultrasound where the micro-bubbles are remaining as cavitation nuclei. The numerical results elucidate well the experimental ones.
Postexcitation collapse as a characteristic of single ultrasound contrast agent destruction
Authors: King Daniel , OBrien Jr William
Published: April 2012

Measurement of the response of single, unconstrained ultrasound contrast agents (UCAs) is useful for facilitating experiment interpretation and theoretical comparison. An experimental setup has been developed to characterize the acoustic large amplitude response of microbubbles called double passive cavitation detection (PCD) which consists of three confocally aligned transducers. The symmetric single bubble responses from within the confocal region are analyzed for the presence or absence of a postexcitation signal (PES), a rebound characteristic response to large amplitude pressures that may follow the initial harmonic UCA response. Experimental sensitivity to the PES is explored by receiving with transducers of different frequencies. Theoretical models indicate postexcitation rebound occurs following shell rupture and inertial cavitation of the UCA. The postexcitation response curves as a cavitation metric are useful for characterizing distinct collapse thresholds among UCAs which arise due to material differences; additionally, the thresholds may be considered as destruction thresholds and compared to a variety of in-vitro and in-vivo studies to aid in understanding the resultant bioeffects in these studies. (NIH Grant R37EB002641.)
High-speed observation of bubble dynamics influenced by surfactant molecules
Authors: Choi Pak-Kon , Deno Shota
Published: April 2012

Surfactant molecules affect the dynamics of acoustic bubbles such as the oscillation of expansion and contraction and a bubble coalescence when adsorbed with bubble/liquid interface. A high-speed shadowgraph of acoustic bubbles was observed in surfactant SDS solutions using a high-speed camera with a speed of a million fps. The experimental results of time evolution of bubble diameter showed that a surfactant-adorbed bubble favors a spherical oscillation. Histograms of maximum bubble diameters obtained at several frequencies indicated that the number of large-size bubble considerably decreased compared to the case of pure water and this tendency was marked at higher frequencies. The histograms measured at various SDS concentrations at 87 kHz showed that the decrease in the number is significant at 5 mM. The results are elucidated in terms of electrostatic repulsion between charged bubbles, which inhibits the bubble coalescence.
An axisymmetric model of ultrasound contrast agent collapse following shell rupture
Authors: King Daniel A. , Freund Jonathan B. , O'Brien William D.
Published: April 2012

Widely used spherically symmetric models of ultrasound contrast agents (UCA) are unable to capture complicated collapse behaviors when the UCA shell ruptures. Observations from acoustic passive cavitation detection analysis of collapsing UCAs as well as images from high speed videos of UCA destruction suggest that including spatial asymmetry in the shell interface conditions of models may be useful for studying collapse, onset of fragmentation, and initiation of postexcitation rebound. The concept of lipid shell rupture is incorporated into an axisymmetric boundary element method formulation as a circular hole developing during the growth phase of an initially spherical bubble. The different material interfaces are represented by a spatially varying surface tension due to different pressure discontinuity conditions from the inner gas region to the outer fluid region. Results from the simplified geometrical model simulations demonstrate that shell fragments may influence the evolution of collapsing UCA and indicate the possibility of microbubble jetting following lipid shell rupture. (NIH Grant R37EB002641.)
Theoretical microbubble dynamics in a homogeneous viscoelastic medium at capillary breaching thresholds
Authors: Patterson Brandon , Miller Douglas , Johnsen Eric
Published: April 2012

In order to predict ultrasound-induced bioeffects in diagnostic and therapeutic procedures, the dynamics of cavitation microbubbles in viscoelastic media must be determined. For this theoretical study, measured 1.5-7.5 MHz pulse pressure waveforms, which were used in experimental determinations of capillary breaching thresholds for contrast enhanced diagnostic ultrasound in rat kidney (Miller et al. Ultras. Med. Biol. 2008;34:1678), were used to calculate cavitation nucleated from contrast agent microbubbles. A numerical model for cavitation in tissue was developed using the Keller-Miksis equation (compressible Rayleigh-Plesset equation), with various viscoelastic models (Kelvin-Voigt, Maxwell and Standard Linear Solid). From this model, the bubble dynamics corresponding to the experimentally obtained capillary breaching thresholds were determined. For example, the particular value of the maximum radius and temperature corresponding to this threshold was determined for a range of ultrasound pulses and bubble sizes, and was shown to be frequency-dependent. It was observed that the bioeffects thresholds do not correspond exactly to inertial cavitation thresholds, suggesting the possibility of a more complex mechanism of injury. We plan to identify local, secondary bioeffect mechanisms, which might be constant for threshold conditions at different frequencies.
Theoretical cavitation thresholds in vivo and their relationship to the mechanical index
Authors: Church Charles C.
Published: April 2012

The mechanical index (MI) displayed on the screens of most modern diagnostic ultrasound machines is a relative indication of bioeffect risk. The current definition of the MI, the ratio of the rarefactional pressure in situ to the square root of the center frequency of the acoustic wave, is based on an analytic evaluation of the threshold for violent cavitation of pre-existing gas bubbles in biologically relevant fluids, i.e., water and blood. An alternative approach assuming spontaneous nucleation of bubbles when these liquids are under tension produced by an acoustic field indicated that the threshold was nearly independent of frequency in water but directly proportional to frequency in blood. More recently, it has been suggested that the lipid bilayers surrounding and within individual cells may rupture when subjected to a rarefactional pressure, thereby producing cavitation nuclei that may be further acted upon by the acoustic field. By combining theoretical thresholds for bilayer-nucleation and cavitation in tissue, it is shown that the maximum acoustic pressure permitted by the US FDA for the safe use of diagnostic ultrasound is lower than necessary in most circumstances. An evidence-based safety threshold for non-thermal effects of diagnostic ultrasound will be proposed. (NIH Grant R21EB013763-01)
Cortical activation during the perception of intelligible and unintelligible speech as measured via high- density electroencephalography
Authors: Utianski Rene , Caviness John , Liss Julie , Lotto Andrew , Lansford Kaitlin
Published: April 2012

High-density electroencephalography (EEG) was used to evaluate cortical activity patterns during the auditory processing of speech presented at various levels of degradation in a sentence verification task. 25 healthy participants listened to true-false sentences produced with one of 3 channel levels (1, 6, 16), ranging from unintelligible, moderately intelligible, and highly intelligible. Behavioral data were collected via button press (reaction time and accuracy) for each sentence. The analysis of cortical activation patterns includes 1) the identification of independent components that account for variations of activity associated with degradation levels and 2) the examination of associated event-related potentials. Statistical analyses will be performed on individuals' cortical activity, in tandem with behavioral data. Preliminary results reveal differences in the timing and magnitude of frontal and temporal lobe activation that coincide with task difficulty. Results of the present investigation will inform hypotheses about regions of interest for further investigation and will bear on models of connected speech perception, including the neurobiological underpinnings of individual differences and manifestations in a listener's understanding of degraded speech.
Cortical and brainstem differentiation of neural responses to hits versus misses
Authors: Bressler Scott , Lin Vincent , Aksyonova Diana , Shinn-Cunningham Barbara
Published: April 2012

Near threshold, the same physical stimuli sometimes are perceived, but sometimes go unheard. Past visual studies have shown cortical evoked response potentials (ERPs) recorded via electroencephalography (EEG) are greater when an input is perceived than when it is not detected. Here, this approach was extended to ask whether there are detectable differences in neural activity in response to detected and undetected sounds, and whether these differences are present not only cortically, but also even earlier in the auditory system. Listeners are asked to detect the presence of a threshold-level tone complex presented in noise, presented amidst “no tone complex” catch trials. Tone-present trials are binned based on perceptual outcome (“hits” versus “misses”). Cortical ERPs from “hits” trials were found to be more robust than ERPs from “misses.” Moreover, post-stimulus alpha activity (8-12 Hz) differs; specifically, “misses” showed sustained alpha activity beginning 200 ms post-stimulus, while “hits” showed an amplitude decrease in alpha around 250-300 ms. FFRs from the same EEG data for “hits” and “misses” are being compared to determine whether perceptual differences are observable early in the auditory processing stream.
Prediction method of aircraft interior noise and validation testing
Authors: Qin Haoming , Pan Kai
Published: April 2012

VA-one software is based on Statistical Energy Analysis theory. In this paper, acoustic modeling and prediction of interior noise of Fuselage Acoustic Research Facility (FARF) are accomplished with this software. With its support, the subsystem partition method and modeling method of airframe are proposed; further validation by testing method is also studied. With several different kinds of sidewall structures, the FARF is excited by speaker arrays and shakers while acoustic and vibration energy were measured and added into model as input. The interior damping loss factor was obtained by reverberant time measurement. Then the sound pressure level was predicted. Good coherent between prediction and measurement was obtained while methods of testing and data processing are validated. All these are very important to improve the capability of prediction of interior noise of aircraft.
Sound random incidence absorption characteristics of a thin plate with PZT shunted with passive electrical circuits
Authors: Xiang Chen
Published: April 2012

Sound absorption of a thin plate with PZT shunted with passive electrical circuits in diffuse field Sound absorbing properties of a plate with piezoelectric shunted circuit in diffuse field is investigated in this paper. A theoretical model of a thin plate with piezoelectric patch and electrical circuit under random sound incidence is proposed and numerically analyzed. Measurement is also carried out in a reverberation room and found to be in good agreements with the theoretical model. Theoretical and measured results confirmed that this technology has a potential to improve sound absorption at low frequency
Near-field effect as sound transmission through a panel-cavity system
Authors: Liu Bilong
Published: April 2012

Evidence from measurement indicates that sound pressure level inside cabin is dominant for the seats close to the windows. It could be 3~6 dB(A) higher than that of the seats close to the corridor for a commercial aircraft during cruising. This near-field phenomenon of transmitted sound is modeled and investigated by the sound transmission through a panel-cavity system. The distribution of transmitted sound pressure level behind the flexural panel is calculated and the effect of local absorption layer behind the flexural panel is specially included for a comparison. Simple measurement is also carried out to show that the size and thickness of local absorption layer is sensitive to the near-field of transmitted sound.
The aircraft acoustics research and achievements of AVIC
Authors: Huang Wenchao , Yang Hai
Published: April 2012

Passing through decades of research, development, applications and improvements, the AVIC has sent their ARJ-21 and MA-600 for the first flight and drawing greater prospect for future. The acoustic research for aircraft in AVIC mainly focus on three aspects: interior noise environment for passenger comfort, exterior noise emission for mandatory airworthiness regulation and sonic fatigue for safety issue, while integrated design strategy, optimization routine and validation procedure were developed, supporting aircrafts development and aiming the future.