Journal articles: 'Acoustical transmission line'

1

Tyutekin, V. V. "Acoustical characteristics of a multichannel transmission line." Acoustical Physics 46, no. 6 (2000): 710–15. http://dx.doi.org/10.1134/1.1326727.

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Chen, Yeongchin. "Acoustical transmission line model for ultrasonic transducers for wide-bandwidth application." Acta Mechanica Solida Sinica 23, no. 2 (2010): 124–34. http://dx.doi.org/10.1016/s0894-9166(10)60014-6.

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Sü, Zühre, and Mehmet Çalışkan. "Acoustical Design and Noise Control in Metro Stations: Case Studies of the Ankara Metro System." Building Acoustics 14, no. 3 (2007): 203–21. http://dx.doi.org/10.1260/135101007781998910.

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The aim of this research is to demonstrate the importance of initial strategies in acoustical design of underground metro stations. The paper searches for practical design solutions by evaluating different materials for providing optimum acoustical conditions in such spaces. Acoustical designs of three metro stations on a new expansion line in Ankara including Sogutozu, Bilkent and ODTU metro stations are presented through computer simulation. Predictions of room acoustical parameters are presented for both platform and ticket office floors in terms of parameters like reverberation time (RT), speech transmission index (STI) and A-weighted sound level (SPL) distribution within spaces. Simulated reverberation times are evaluated in view of legislative requirements. The study confirms the importance of using sound absorbing materials on the ceiling and sidewalls together. The nonwoven material, used behind perforated metal suspended ceilings, has proved effective in reverberation control.

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Keefe, Douglas H. "Acoustical transmission-line model of the middle-ear cavities and mastoid air cells." Journal of the Acoustical Society of America 137, no. 4 (2015): 1877–87. http://dx.doi.org/10.1121/1.4916200.

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MENEMENLIS, D. "Line-averaged measurement of velocity fine structure in the ocean using acoustical reciprocal transmission." International Journal of Remote Sensing 15, no. 2 (1994): 267–81. http://dx.doi.org/10.1080/01431169408954070.

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Ilkorur, Onur, Ismail Yuksek, and Emre Omurlu. "Usage of acoustical filters in transmission line enclosures as a replacement of fiber absorber." Journal of the Acoustical Society of America 117, no. 4 (2005): 2387. http://dx.doi.org/10.1121/1.4785762.

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Pasterkamp, Hans, Ignacio Sanchez, and Yunes Oh. "Teleauscultation: Bringing You to the Bedside." Canadian Respiratory Journal 2, no. 4 (1995): 237–40. http://dx.doi.org/10.1155/1995/530989.

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A custom-made device was used for the acquisition, digitization, compression, storage and telephone transmission of respiratory sounds and airflow data. Acoustical information from two patients at a small community in rural Manitoba was sent over a distance of 500 km via conventional telephone lines. Digital transmission left the respiratory sounds unaffected by telephone line noise. Data processing by computer at the receiving site provided more detail than would have been available on conventional auscultation. This new method for teleauscultation could be of value not only in remote areas but also for the surveillance of patients at home in urban settings.

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Xingguo, Wang, Shu Haisheng, and Zhang Lei. "Vibration and acoustic insulation properties of generalized phononic crystals." European Physical Journal Applied Physics 94, no. 3 (2021): 30902. http://dx.doi.org/10.1051/epjap/2021210036.

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Based on the previous studies, the concept of generalized phononic crystals (GPCs) is further introduced into the cylindrical shell structures, and a type of cylindrical shells of generalized phononic crystals (CS-GPCs) is constructed. Subsequently, the structure field and acoustic-structural coupled field of that composite cylindrical shells are examined respectively in this paper. Considering the Bloch theorem is not capable of explaining the generalized periodic situation existing in this structure field, a new analysis method involving transferring matrix eigenvalue based on the mechanical state vector is proposed to calculate the energy band structure. Through observing the energy band structure, an obvious wave band gap is obtained when the elastic wave propagates in the CS-GPCs for modes with different order, whose forming mechanism includes two aspects, i.e., the wave front expansion effect and the Bragg scattering effect. In addition, we further explore the related influences of the longitudinal wave mode and shear wave mode in structure on these band gaps, and some conclusions are illustrated. For acoustic-structural coupled field, the expressions of the acoustic transmission coefficients for different modes are built, and the frequency responses are numerically calculated to verify the band gap characteristics of the CS-GPCs. Furthermore, the acoustic pressure distribution of the internal and external acoustic fields is also analyzed in detail, and the influence laws of the parameters (offset distance and frequency) of the line source on acoustical pressure distribution and its directivity are explored.

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Chiu, Y. S., and C. F. Chen. "Time Reversal Processing Effect on Foci Structure in a Dynamic Ocean Waveguide." Journal of Mechanics 23, no. 3 (2007): 203–10. http://dx.doi.org/10.1017/s1727719100001234.

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AbstractTime-reversal mirror (TRM) was recently developed for underwater communication system application. This technique has been introduced as an approach to compensate for signal distortion due to multiple path effect in ocean waveguide. TRM is used in this paper for sending a message signal in ocean waveguide, received at time-reversal-array (TRA), and retransmitted to the dynamic ocean environment with an internal solitary wave. The focal structures obtained from different simulating cases are used for bidirectional transmission expediency, and the TRA is used as the relay-line or trunked radio. Ocean waveguide characteristic effects on acoustical properties are also shown in this paper, and focal structure in different ocean environments is analyzed to provide an optimal approach to underwater communication systems and for physical insight's interests.

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Lim, Siong Kang, Kar Poh Foo, Foo Wei Lee, et al. "Acoustic Properties of Lightweight Foamed Concrete with Eggshell Waste as Partial Cement Replacement Material." Sains Malaysiana 50, no. 2 (2021): 537–47. http://dx.doi.org/10.17576/jsm-2021-5002-24.

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Nowadays, almost every industry needs to undergo green and sustainable industrial revolution due to pollutions like waste dumping and noise that deteriorating the environment. Therefore, feasibility study on application of eggshell waste as partial cement replacement in lightweight foamed concrete was conducted by aiming to solve environmental and acoustical issues, i.e. reduce eggshell waste and improve acoustic properties. In this study, compressive strength and acoustic properties of 1300 kg m-3 lightweight foamed concrete with and without 5% eggshell powder as partial cement replacement material were tested. Optimal water to cement ratio of 0.6 was obtained for acoustic properties test by comparing compressive strength result. The result shows that application eggshell powder has generally reduced 7 days compressive strength but improved 28 days compressive strength, and either improve or maintain acoustics properties, in which lightweight foamed concrete that containing eggshell powder has improved noise reduction coefficient at testing ages of 7, 28, and 90 days and improved sound transmission class at testing age of 56 and 90 days. Based on these results, 5% of eggshell powder is feasible to be incorporated into lightweight foamed concrete as partial cement replacement material for sound insulation and strength development purposes.

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Zhang, Jiangyi, Vicente Romero-García, Georgios Theocharis, Olivier Richoux, Vassos Achilleos, and Dimitrios Frantzeskakis. "Dark Solitons in Acoustic Transmission Line Metamaterials." Applied Sciences 8, no. 7 (2018): 1186. http://dx.doi.org/10.3390/app8071186.

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We study dark solitons, namely density dips with a phase jump across the density minimum, in a one-dimensional, weakly lossy nonlinear acoustic metamaterial, composed of a waveguide featuring a periodic array of side holes. Relying on the electroacoustic analogy and the transmission line approach, we derive a lattice model which, in the continuum approximation, leads to a nonlinear, dispersive and dissipative wave equation. The latter, using the method of multiple scales, is reduced to a defocusing nonlinear Schrödinger equation, which leads to dark soliton solutions. The dissipative dynamics of these structures is studied via soliton perturbation theory. We investigate the role—and interplay between—nonlinearity, dispersion and dissipation on the soliton formation and dynamics. Our analytical predictions are corroborated by direct numerical simulations.

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Rani, Jansi J., S. Anusuya, B. Vidhya, and Benedict M. Tephila. "A Study on Techniques of Underwater Optical Communication." Journal of Computational and Theoretical Nanoscience 16, no. 2 (2019): 525–28. http://dx.doi.org/10.1166/jctn.2019.7763.

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In recent years, the higher data rate and a higher degree of accuracy in transmissions have been achieved through wireless communication technology. The underwater communication is one of the trending technologies in wireless communication. The underwater data transmission is carried out by the acoustic waves which produce vibrations of sounds during its transmission. These vibrations have disturbed the creatures present underwater and additionally it may cause some noise. The results of many recent researches have concluded that the vibrations produced by the acoustic waves cause the disturbances in the earth plates and due to which the natural calamities like tsunami, earthquakes etc., have been occurring. The underwater communication is mostly used for military applications and for the transmission of sensitive information within the shortest distance of a particular area. The use of acoustic waves produces a low data rate and increased time delay. In addition to that, these waves are unreliable and complex due to multipath propagations in water. The acoustic waves employ modulation techniques like FSK, PSK and OFDM for the data transmission and consume more energy and power. So lately, the transmission of data in underwater is carried out by using the optical waves. ON–OFF keying technique is most commonly used modulation technique with attractive features such as high data rate, less delay, low power consumption, energy saving, and better accuracy than the other techniques.

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Banba, Yutaka. "Transmission line coding method, transmission line decoding method, and apparatus therefor." Journal of the Acoustical Society of America 125, no. 6 (2009): 4108. http://dx.doi.org/10.1121/1.3155493.

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O'Connor, W., and F. Cavanagh. "Transmission line matrix acoustic modelling on a PC." Applied Acoustics 50, no. 3 (1997): 247–55. http://dx.doi.org/10.1016/s0003-682x(96)00069-2.

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Shin, Hyunjun, and J. Stuart Bolton. "The use of microperforated materials as duct liners: Comparison with fibrous linings." Noise Control Engineering Journal 68, no. 4 (2020): 269–82. http://dx.doi.org/10.3397/1/376823.

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The acoustical performance of a microperforated duct liner and a fibrous lining was compared to confirm that a microperforated panel lining can be used to re- place a fibrous liner as a sound attenuator in a duct. Fibrous materials are often used to line ducts in order to attenuate HVAC noise, for example. These treatments are often primarily useful in a limited frequency range owing to the characteristics of non-planar wave propagation in ducts. At the same time, microperforated mate- rials backed by a finite-depth air space are effective in a limited frequency range owing to the nature of the reactive impedance of this combination. Here, it will be shown that microperforated materials may be used to create duct linings that produce attenuation comparable with that of fibrous materials in the latter's high- performance region. The characteristics of the microperforated panel were studied based on the Maa model. To compare the performance of these two linings, theoret- ical, numerical and experimental tools were used. In the various case studies, both extended reaction and locally reacting treatments were considered. For the analyti- cal approach, Morse's theory was applied in the local reaction case. On the other hand, Scott's analysis was used to study the extended reaction case. In the experi- mental work, the transmission losses of various liner configurations were measured in a square impedance tube. To tune the performance of a microperforated sheet to reproduce that of a fibrous material, the hole size, porosity, thickness, density, and air-backing depth were modified. To validate the experimental and analytical data and to handle situations that are not easily modeled using an analytical approach, a finite element model was also used for the calculations. For the finite element model analysis, COMET/VISION and SAFE were used. Since that software does not include explicit microperforated material models, an alternative approach was used. The alternative model was based on the Attala and Sgard model for perforated panels. This alternative approach in which the perforated panel is modeled as a thin porous layer was successfully implemented in finite element form. Finally, it was demonstrated that the microperforated panel can successfully reproduce the acous- tical performance of glass fiber as a duct lining material.

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Lee, Jingeol. "Transmission line based struck string model." Applied Acoustics 111 (October 2016): 1–7. http://dx.doi.org/10.1016/j.apacoust.2016.04.002.

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Santoni, Andrea, Paolo Bonfiglio, Patrizio Fausti, Cristina Marescotti, Valentina Mazzanti, and Francesco Pompoli. "Characterization and Vibro-Acoustic Modeling of Wood Composite Panels." Materials 13, no. 8 (2020): 1897. http://dx.doi.org/10.3390/ma13081897.

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Natural fiber-filled polymers offer good mechanical properties and economic competitiveness compared to traditional materials. Wood flour is one of the most widely used fillers, and the resulting material, known as wood plastic composite (WPC), has already found a wide applicability in many industrial sectors including automotive and building construction. This paper, as a followup of a previous study on a numerical-based approach to optimize the sound transmission loss of WPC panels, presents an extensive numerical and experimental vibro-acoustic analysis of an orthotropic panel made out of WPC boards. Both structural and acoustical excitations were considered. The panel radiation efficiency and its transmission loss were modeled using analytic and semi-analytic approaches. The mechanical properties of the structure, required as input data in the prediction models, were numerically determined in terms of wavenumbers by means of finite element simulations, and experimentally verified. The accuracy of the predicted acoustic performances was assessed by comparing the numerical results with the measured data. The comparisons highlighted a significant influence of the junctions between the WPC boards, especially on the panel’s transmission loss. The radiation efficiency results were mostly influenced by the boundary conditions of the plate-like structure. This latter aspect was further investigated through a finite element analysis.

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Lee, Heow Pueh, and Sanjay Kumar. "Perspectives on the Sonic Environment and Noise Mitigations during the COVID-19 Pandemic Era." Acoustics 3, no. 3 (2021): 493–506. http://dx.doi.org/10.3390/acoustics3030033.

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The pandemic has impacted every facet of our life, society, and environment. It has also affected both the requirement and challenges for acoustic research and applications. The present article attempts to present a summary of the impact of COVID-19 on several aspects of acoustics, from the changes in the sonic environment due to reduced human and industrial activities to natural ventilation requirements for mitigating the transmission of coronavirus while mitigating noise, and, more importantly, discusses the potential impacts and challenges for acoustics in the post-COVID-19 era. The present study specifically examines the effects of COVID-19 on the sonic environment, the acoustic treatment by considering the need for constant disinfection, the noise control on construction and neighborhood activities in response to an increased number of people working from home, and the need for having natural ventilation while mitigating noise at home and offices.

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Zhang, Jiangyi, Vicente Romero-García, Georgios Theocharis, Olivier Richoux, Vassos Achilleos, and Dimitrios J. Frantzeskakis. "High-amplitude sound propagation in acoustic transmission-line metamaterial." Applied Physics Letters 118, no. 10 (2021): 104102. http://dx.doi.org/10.1063/5.0040702.

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Spear, Robert J., and Alexander F. Thornhill. "Transmission line for planar waves." Journal of the Acoustical Society of America 98, no. 1 (1995): 23. http://dx.doi.org/10.1121/1.413770.

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Dong, Wei, and Elizabeth S. Olson. "Middle Ear Forward and Reverse Transmission in Gerbil." Journal of Neurophysiology 95, no. 5 (2006): 2951–61. http://dx.doi.org/10.1152/jn.01214.2005.

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The middle ear transmits environmental sound to the inner ear. It also transmits acoustic energy sourced within the inner ear out to the ear canal, where it can be detected with a sensitive microphone as an otoacoustic emission. Otoacoustic emissions are an important noninvasive measure of the condition of sensory hair cells and to use them most effectively one must know how they are shaped by the middle ear. In this contribution, forward and reverse transmissions through the middle ear were studied by simultaneously measuring intracochlear pressure in scala vestibuli near the stapes and ear canal pressure. Measurements were made in gerbil, in vivo, with acoustic two-tone stimuli. The forward transmission pressure gain was about 20–25 dB, with a phase–frequency relationship that could be fit by a straight line, and was thus characteristic of a delay, over a wide frequency range. The forward delay was about 32 μs. The reverse transmission pressure loss was on average about 35 dB, and the phase–frequency relationship was again delaylike with a delay of about 38 μs. Therefore to a first approximation the middle ear operates similarly in the forward and reverse directions. The observation that the amount of pressure reduction in reverse transmission was greater than the amount of pressure gain in forward transmission suggests that complex motions of the tympanic membrane and ossicles affect reverse more than forward transmission.

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Vyas, Jaishree, and Rymantas Jonas Kažys. "A Review on Nondestructive Techniques and Characteristics of Composite Materials for the Aerospace System." MATEC Web of Conferences 233 (2018): 00003. http://dx.doi.org/10.1051/matecconf/201823300003.

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In the aerospace industry contactless measurement has been a very versatile and adaptable in recent years, mainly because of its diverse applications. Usually ultrasonic measurement requires acoustic contact media which may disserve the sample and varies for different materials. In the operational hand, acoustic contact media like water is also not preferred for on-aircraft inspection. The air coupled inspection technique among other nondestructive testing techniques is often not enticing due to acoustic mismatch and wave propagation. Though, acoustical mismatch of the transducers can be reduced by application of a matching layer and also by using different corresponding transducers. Air-coupled transducers are the captivating alternatives for the inspection. This paper comprises different air coupled inspection techniques i.e. through transmission and guided wave generation as well as its working modes. Various transducer arrangements, the advantages of air-coupled ultrasonic guided wave inspection over other NDT techniques and their specifications are discussed revolving around the materials. Composite materials have superior properties like tensile strength, better heat resistance which cannot be materialized in single. The utilization of composite materials like CFRP, GFRP, other polymers and ceramic composites seeks the improvement in lift to weight ratio. An overall review deals with air coupled techniques and scrutiny of different materials concerning this technique, which includes characteristics of various composite materials used in aerospace industry.

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Knöfel, Björn, Jan Troge, and Welf-Guntram Drossel. "Transmission Acoustics Between End-of-Line Testing and Vehicle Rating." ATZextra worldwide 21, S1 (2016): 6–9. http://dx.doi.org/10.1007/s40111-016-0007-z.

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Anzinger, Sebastian, Johannes Manz, Christian Bretthauer, Ulrich Krumbein, and Alfons Dehé. "Acoustic transmission line based modelling of microscaled channels and enclosures." Journal of the Acoustical Society of America 145, no. 2 (2019): 968–76. http://dx.doi.org/10.1121/1.5090502.

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Holberg, Tuomas, and Marcel Gavriliu. "Non-linearly tapering transmission line speakers." Journal of the Acoustical Society of America 116, no. 3 (2004): 1319. http://dx.doi.org/10.1121/1.1809879.

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WANG, KAI, XIEFENG CHENG, YAMIN CHEN, CHENJUN SHE, KEXUE SUN, and PENGJUN ZHAO. "HEART SOUND MODEL BASED ON CASCADED AND LOSSLESS ACOUSTIC TUBES." Journal of Mechanics in Medicine and Biology 19, no. 05 (2019): 1950031. http://dx.doi.org/10.1142/s0219519419500313.

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In order to further understand the generation mechanism of Heart Sound, we introduce a new method for simulating Heart Sound by using cascaded and lossless acoustic tubes. Based on the theory of acoustics, we abstract the ventricles and arteries inside of the heart as multistage tubes with equal length and different radii. By controlling the radii of tubes, we simulate the process of relaxation and constriction of the ventricles and arteries. Then, we calculate the transfer function of the tubes based on the theory of reflective transmission line. To gain the tubes’ radii, we use formant frequency as the model target parameters and put forward an approximation method. Finally, the experimental results show that compared with traditional model, the model based on cascaded and lossless acoustic tubes could better reflect the state of the ventricles and arteries. Meanwhile, by comparing the model tube radius of normal Heart Sound and pathological Heart Sound, we can give a better explanation to the cause of pathological Heart Sound.

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Ndzana, Fabien II, Alidou Mohamadou, and Timoléon Crépin Kofané. "Modulated waves and chaotic-like behaviours in the discrete electrical transmission line." Journal of Physics D: Applied Physics 40, no. 10 (2007): 3254–62. http://dx.doi.org/10.1088/0022-3727/40/10/035.

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Triwahyanti, Lesa, Ajeng Sekar Cyndana, Yessy Hurly Sefnianti, Ratna Juita Sari, and Amron Amron. "Transmission Loss Estimation of Underwater Sound Based on the Noise Intensity Emmited by MV. Pengayoman IV in Tanjung Intan Cruise Line, Cilacap." E3S Web of Conferences 47 (2018): 04011. http://dx.doi.org/10.1051/e3sconf/20184704011.

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The water is an imperfect acoustic medium, acoustic energy can lost due to absorption and scattering thus resulting in transmission loss. The value of transmission loss in water is an important thing to know, for example in the application of active acoustic. This study aim is to determine the value of transmission loss in Tanjung Intan’s cruise line, Cilacap. The acquisition of vessel's sound data was obtained by hydrophone and vessel data (distance) by CCTV. Both sound data and vessel data were connected to personal computer to record the audio and visual signal synchronously for three consecutive days. Results showed that vessel characteristics such as intensity, frequency and interval duration have a value of 43.35 (dB), 6613.54 (Hz) and 216.15 (ms) respectively. While the value of water absorption coefficient has a range of 500-900 dB/km, the estimated transmission loss value was between 5-11 dB/km.

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Boucher, R. F., and E. E. Kitsios. "Simulation of Fluid Network Dynamics by Transmission Line Modelling." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 200, no. 1 (1986): 21–29. http://dx.doi.org/10.1243/pime_proc_1986_200_090_02.

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The classical solution to the acoustic wave equation reveals decoupled left- and right-going waves carrying pressure and flow. Using a variant of these waves representing power, it is shown that such decoupled waves permit fluid transmission lines in circuits to be modelled simply as pure time delays. It is also demonstrated that lumped inertance and capacitance may be modelled as transmission line stubs. Thus all dynamic elements in a circuit are represented as pure time delays and the only computations required are of wave scattering at junctions. Linear resistance is most easily admitted, especially if it is concentrated at the junctions. Computations on simple circuits are presented and shown to compare favourably with classical ‘lumped’ analyses. The significance of various approximations made is discussed. The method may be applied to fluid circuits of arbitrary size and complexity, and to circuits of other wave-propagating elements.

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Veerababu, D., and B. Venkatesham. "Transmission loss of lined Helmholtz resonator with annular air gap: A Green's function based approach." Noise Control Engineering Journal 69, no. 2 (2021): 112–21. http://dx.doi.org/10.3397/1/376912.

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The present article discusses a Green's function-based semi-analytical method to predict the transmission loss of a lined Helmholtz resonator with annular air gap. In the analysis, the walls of the chamber are assumed to be acoustically rigid except at the neck portion where it is treated as a piston source moving with uniform velocity. The Green's function is developed as the summation of eigenfunctions of the central duct. The cumulative effect of the lined portion and the annular air gap including the perforated screens is incorporated as the reflection coefficient in the eigenfunctions. By using the Kirchhoff-Helmholtz integral equation, the velocity potential generated by the piston inside the chamber is evaluated. A transfer matrix relating the acoustic pressure and volume velocity across the neck in the main duct is formulated. The effect of the neck length is included as an added inertance to the impedance in the transfer matrix. The results obtained from the proposed method are validated with the developed numerical models and the experimental data available in the literature. A parametric study has been conducted to investigate the effect of porosity of the perforated screens, thickness and flow resistivity of the absorptive material on the transmission loss of the chamber.

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Han, Jianning, Shuai Tang, Rui Wang, and Wen Wang. "Acoustic wave transmission channel based on phononic crystal line defect state." AIP Advances 9, no. 6 (2019): 065201. http://dx.doi.org/10.1063/1.5098819.

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Jackson, C. M. "Finite-difference, time-domain analysis of a folded acoustic transmission line." IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 52, no. 3 (2005): 371–74. http://dx.doi.org/10.1109/tuffc.2005.1417259.

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Tyutekin, V. V. "Acoustic characteristics of a multichannel transmission line of longitudinal-flexural type." Acoustical Physics 49, no. 1 (2003): 91–96. http://dx.doi.org/10.1134/1.1537394.

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Escolano, José, Basilio Pueo, and José J. Lopez. "A comprehensive discrete-time computer modeling of acoustic Transmission Line loudspeakers." Applied Acoustics 72, no. 10 (2011): 742–53. http://dx.doi.org/10.1016/j.apacoust.2011.04.003.

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Minin, Oleg, and Igor Minin. "LENS QUASI-OPTICAL TRANSMISSION LINE WITH OPTICAL CONTRAST CLOSE TO 1." Interexpo GEO-Siberia 8 (2019): 93–99. http://dx.doi.org/10.33764/2618-981x-2019-8-93-99.

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The quasi-optical transmission line with optical contrast close to 1 is considered. Such devices can be used to study the effect of laser radiation on biological media, in microwave, terahertz, optical and X-ray wavelength ranges, as well as in acoustics. The use of composite refractive lenses, which are a set of identical spherical lenses arranged one after another on the same optical axis and with a refractive index close to one, reduces the loss of reflection in such a lens. Reducing the focal length in such refractive lenses is possible by increasing the number of refractive surfaces.

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Jiang, Cheng, JianLong Li, and Wen Xu. "The Use of Underwater Gliders as Acoustic Sensing Platforms." Applied Sciences 9, no. 22 (2019): 4839. http://dx.doi.org/10.3390/app9224839.

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Underwater gliders travel through the ocean by buoyancy control, which makes their motion silent and involves low energy consumption. Due to those advantages, numerous studies on underwater acoustics have been carried out using gliders and different acoustic payloads have been developed. This paper aims to illustrate the use of gliders in underwater acoustic observation and target detection through experimental data from two sea trials. Firstly, the self-noise of the glider is analyzed to illustrate its feasibility as an underwater acoustic sensing platform. Then, the ambient noises collected by the glider from different depths are presented. By estimating the transmission loss, the signal receiving ability of the glider is assessed, and a simulation of target detection probability is performed to show the advantages of the glider over other underwater vehicles. Moreover, an adaptive line enhancement is presented to further reduce the influence of self-noise. Meanwhile, two hydrophones are mounted at both ends of the glider to form a simple array with a large aperture and low energy consumption. Thus, the target azimuth estimation is verified using broadband signals, and a simple scheme to distinguish the true angle from the port‒starboard ambiguity is presented. The results indicate that the glider does have advantages in long-term and large-scale underwater passive sensing.

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HEIN, STEFAN, WERNER KOCH, and LOTHAR NANNEN. "Fano resonances in acoustics." Journal of Fluid Mechanics 664 (October 26, 2010): 238–64. http://dx.doi.org/10.1017/s0022112010003757.

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In contrast to completely open systems, laterally confined domains can sustain localized, truly trapped modes with nominally zero radiation loss. These discrete resonant modes cannot be excited linearly by the continuous propagating duct modes due to symmetry constraints. If the symmetry of the geometry is broken the trapped modes become highly localized quasi-trapped modes which can interfere with the propagating duct modes. The resulting narrowband Fano resonances with resonance and antiresonance features are a generic phenomenon in all scattering problems with multiple resonant pathways. This paper deals with the classical scattering of acoustic waves by various obstacles such as hard-walled single and multiple circular cylinders or rectangular and wedge-like screens in a two-dimensional duct without mean flow. The transmission and reflection coefficients as well as the (complex) resonances are computed numerically by means of the finite-element method in conjunction with two different absorbing boundary conditions, namely the complex scaling method and the Hardy space method. The results exhibit the typical asymmetric Fano line shapes near the trapped-mode resonances if the symmetry of the geometry is broken.

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Kozyrev, A. B., and D. W. van der Weide. "Nonlinear left-handed transmission line metamaterials." Journal of Physics D: Applied Physics 41, no. 17 (2008): 173001. http://dx.doi.org/10.1088/0022-3727/41/17/173001.

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Glover, Jennifer, and Dan O'Boy. "Acoustic space filling curve metamaterials for grazing flow in Jet engine inlets." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 6 (2021): 394–406. http://dx.doi.org/10.3397/in-2021-1458.

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Acoustic metamaterials research has grown exponentially in the past 10 years driven by the advances in manufacturing and an increased understanding of damaging environment noise. 2020 was the first noise reduction target as set by Advisory Council for Aircraft Research and Innovation in Europe with a relative 50% decrease. This was missed by current Jet engine noise control technology; however, metamaterials offer an encouraging alternative. Space Filling Curves (SFC) have the potential to provide a lightweight, thin, high performance acoustic liner. SFC have a history in mathematical geometry dating back to the 1890's but are a comparatively new addition to acoustics. They are designed with a sub-wavelength curled cross-section creating a maze-like pattern which slows acoustic wave propagation through the liner enabling characteristics such as negative refraction and low frequency attenuation. This paper contains a comparison of some of the most promising SFC metamaterial acoustic liner designs, in terms of the fundamental theory of the design category and a discussion of the reflection, absorption and transmission characteristics in terms of a grazing flow conditions. Computer simulation and impedance tube based experimental testing compares the designs. The paper concludes with future application for aeroacoustics with particular focus on the engine inlet.

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Park, Kyu-Chil, and Jong Rak Yoon. "Transmission Line Matrix Modeling for Analysis of Surface Acoustic Wave Hydrogen Sensor." Japanese Journal of Applied Physics 50, no. 7S (2011): 07HD06. http://dx.doi.org/10.7567/jjap.50.07hd06.

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Yamada, Toru, Kazuhide Uriu, Toru Jibu, Koji Seo, Ken-ya Hashimoto, and Masatsune Yamaguchi. "High Accuracy Modeling Method for Transmission Line on Surface Acoustic Wave Substrates." IEEJ Transactions on Electronics, Information and Systems 127, no. 8 (2007): 1171–76. http://dx.doi.org/10.1541/ieejeiss.127.1171.

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Park, Kyu-Chil, and Jong Rak Yoon. "Transmission Line Matrix Modeling for Analysis of Surface Acoustic Wave Hydrogen Sensor." Japanese Journal of Applied Physics 50, no. 7 (2011): 07HD06. http://dx.doi.org/10.1143/jjap.50.07hd06.

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Pilipetskii, A. N., and C. R. Menyuk. "Suppression of the acoustic effect in soliton information transmission by line coding." Optics Letters 22, no. 1 (1997): 28. http://dx.doi.org/10.1364/ol.22.000028.

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Yamada, Toru, Kazuhide Uriu, Toru Jibu, Koji Seo, Ken-Ya Hashimoto, and Masatsune Yamaguchi. "High-accuracy modeling method for transmission line on surface acoustic wave substrates." Electronics and Communications in Japan 92, no. 2 (2009): 49–55. http://dx.doi.org/10.1002/ecj.10230.

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Bangayan, Philbert, Abeer Alwan, and Shrikanth Narayanan. "A transmission‐line model of the lateral approximants." Journal of the Acoustical Society of America 100, no. 4 (1996): 2663. http://dx.doi.org/10.1121/1.417474.

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Mobley, J. Phil, and Samuel Gilman. "Performance of a liquid‐filled audio transmission line." Journal of the Acoustical Society of America 93, no. 4 (1993): 2332. http://dx.doi.org/10.1121/1.406306.

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Sisto, Renata, and Arturo Moleti. "The reflectivity function of the cochlear transmission line." Journal of the Acoustical Society of America 117, no. 4 (2005): 2564. http://dx.doi.org/10.1121/1.4809452.

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Wu, Haopeng, Yongle Wu, Zhiguo Lai, Weimin Wang, and Qinghua Yang. "A Hybrid Film-Bulk-Acoustic-Resonator/Coupled-Line/Transmission-Line High Selectivity Wideband Bandpass FBAR Filter." IEEE Transactions on Microwave Theory and Techniques 68, no. 8 (2020): 3389–96. http://dx.doi.org/10.1109/tmtt.2020.2989264.

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RIENSTRA, SJOERD W., and WALTER EVERSMAN. "A numerical comparison between the multiple-scales and finite-element solution for sound propagation in lined flow ducts." Journal of Fluid Mechanics 437 (June 22, 2001): 367–84. http://dx.doi.org/10.1017/s0022112001004438.

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An explicit, analytical, multiple-scales solution for modal sound transmission through slowly varying ducts with mean flow and acoustic lining is tested against a numerical finite-element solution solving the same potential flow equations. The test geometry taken is representative of a high-bypass turbofan aircraft engine, with typical Mach numbers of 0.5–0.7, circumferential mode numbers m of 10–40, dimensionless wavenumbers of 10–50, and both hard and acoustically treated inlet walls of impedance Z = 2 − i. Of special interest is the presence of the spinner, which incorporates a geometrical complexity which could previously only be handled by fully numerical solutions. The results for predicted power attenuation loss show in general a very good agreement. The results for iso-pressure contour plots compare quite well in the cases where scattering into many higher radial modes can occur easily (high frequency, low angular mode), and again a very good agreement in the other cases.

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Mansy, Hansen A., Robert A. Balk, William H. Warren, et al. "Pneumothorax effects on pulmonary acoustic transmission." Journal of Applied Physiology 119, no. 3 (2015): 250–57. http://dx.doi.org/10.1152/japplphysiol.00148.2015.

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Pneumothorax (PTX) is an abnormal accumulation of air between the lung and the chest wall. It is a relatively common and potentially life-threatening condition encountered in patients who are critically ill or have experienced trauma. Auscultatory signs of PTX include decreased breath sounds during the physical examination. The objective of this exploratory study was to investigate the changes in sound transmission in the thorax due to PTX in humans. Nineteen human subjects who underwent video-assisted thoracic surgery, during which lung collapse is a normal part of the surgery, participated in the study. After subjects were intubated and mechanically ventilated, sounds were introduced into their airways via an endotracheal tube. Sounds were then measured over the chest surface before and after lung collapse. PTX caused small changes in acoustic transmission for frequencies below 400 Hz. A larger decrease in sound transmission was observed from 400 to 600 Hz, possibly due to the stronger acoustic transmission blocking of the pleural air. At frequencies above 1 kHz, the sound waves became weaker and so did their changes with PTX. The study elucidated some of the possible mechanisms of sound propagation changes with PTX. Sound transmission measurement was able to distinguish between baseline and PTX states in this small patient group. Future studies are needed to evaluate this technique in a wider population.

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Journal articles on the topic 'Acoustical transmission line'

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