Sound Transmission Loss Analysis of a Double Plate-Acoustic Cavity Coupling System with In-Plane Functionally Graded Materials

In this paper, the isogeometric analysis (IGA) is employed to develop an acoustic radiation model for a double plate-acoustic cavity coupling system, with a focus on analyzing the sound transmission loss (STL). The functionally graded (FG) plate exhibits a different material properties in-plane, and the power-law rule is adopted as the governing principle for material mixing. To validate the harmonic response and demonstrate the accuracy and convergence of the isogeometric modeling, ANASYS is utilized to compare with numerical examples. A plane wave serves as the acoustic excitation, and the Rayleigh integral is applied to discretize the radiated plate. The STL results are compared with the literature, confirming the reliability of the coupling system. Finally, the investigation is conducted to study impact of cavity depth and power-law parameter on the STL.

Vibration and sound transmission loss characteristics of porous foam functionally graded sandwich panels in thermal environment

This study investigates the vibration and acoustic properties of porous foam functionally graded(FG)plates under the influence of the temperature field.The dynamics equations of the system are established based on Hamilton's principle by using the higher-order shear deformation theory under the linear displacement-strain assumption.The displacement shape function is assumed according to the four-sided simply-supported(SSSS)boundary condition,and the characteristic equations of the system are derived by combining the motion control equations.The theoretical model of vibro-acoustic coupling is established by using the acoustic theory and fluid-structure coupling solution method under the simple harmonic acoustic wave.The system's natural frequency and sound transmission loss(STL)are obtained through programming calculations and compared with the literature and COMSOL simulation to verify the validity and reliability of the theoretical model.The effects of various factors,such as temperature,porosity coefficients,gradient index,core thickness,width-to-thickness ratio on the vibration,and STL characteristics of the system,are discussed.The results provide a theoretical basis for the application of porous foam FG plates in engineering to optimize vibration and sound transmission properties.

Analysis of Long-Range Transmission Loss in the West Pacific Ocean

A long-range sound propagation experiment was conducted in the West Pacific Ocean in July 2013. Linear frequency-modulated signals with a frequency band of 260-360Hz were transmitted by a transducer hung on a floating ship during the experiment and were received by a horizontal line array towed by another ship sailing away from the transducer. The maximum distance between the two ships was 1029km. Signals were received at the distances 34-220 kin, 612-635 km and 926-1029 kin. Transmission loss versus distance between source and receiver was obtained and compared with the theoretical results predicted by the parabolic equation method program RAM. It is shown that RAM is adequate for estimating the transmission loss for distances up to 1029km. When the water depth is larger than the surface conjugate depth, the ocean bottom rarely influences the transmission loss in the convergence zones. However, in the opposite situation, the ocean bottom contributes significantly to the transmission loss.

Tunable low frequency band gaps and sound transmission loss of a lever-type metamaterial plate

A novel metamaterial plate with subwavelength lever-type resonators is proposed to obtain low frequency broadband band gaps and good sound insulation performance.The band structure is theoretically derived,and the validity of the theoretical method is verified by the finite element method.The formation mechanisms of the band gaps are illustrated by the analysis of the effective dynamic mass density and group velocity.The effect of the lever ratio on the band gaps is analyzed.The results indicate that as the lever ratio increases,the first band gap shifts to lower frequencies,while the bandwidth is widened.Moreover,the sound insulation performance of the proposed metamaterial plate is evaluated via examining the sound transmission loss(STL).Compared with the metamaterial plates without lever accessories,the proposed metamaterial plates with a suitable lever ratio have better sound insulation performance at low frequencies.

An Exact Solution for Acoustic Simulation Based Transmission Loss Optimization of Double-Chamber Silencer

The optimization of the acoustic silencer volume is very important to develop it and to get high-performance,the importance of the silencer was appeared in industrial field to eliminate the noise of the duct by efficient and economical method.The main goal of this research is to optimize the transmission loss(TL)by analytical method of the Double-Chamber Silencer(DCS),the TL has been selected as the main parameter in silencer because it does not based on the source or the termination impedances.First we calculated the power transmission coefficient(PTC)and the TL of an acoustic silencer,then used the Lagrange method to optimize the silencer length.All calculation of silencer data is obtained by solving the governing equations in commercial software Matlab®.A several calculations for different silencer length at many frequency ranges were performed simultaneously.Finally,this research supports the efficient and rapid techniques for DCS optimal design under narrow space.The results show that the acoustic TL is maximized at the desired frequency.

Analytical Study on the Rate of Sound Transmission Loss in Single Row Honeycomb Sandwich Panel Using a Numerical Method

Honeycomb structures have recently,replaced with conventional homogeneous materials.Given the fact that sandwich panels containing a honeycomb core are able to adjust geometric parameters,including internal angles,they are suitable for acoustic control applications.The main objective of this study was to obtain a transmission loss curve in a specific honeycomb frequency range along with same overall dimensions and weight.In this study,a finite element model(FEM)in ABAQUS software was used to simulate honeycomb panels,evaluate resonant frequencies,and for acoustic analysis.This model was used to obtain acoustic pressure and then to calculate the sound transmission loss(STL)in MATLAB software.Vibration and acoustic analysis of panels were performed in the frequency range of 1 to 1000 Hz.The models analyzed in this design includes 14-single row-honeycomb designs with angles of−45°,−30°,−15°,0°,+15°,+30°,+45°.The results showed that a-single row and−45°cell angle honeycomb panel in the frequency range of 1 to 1000 Hz had the highest STL as well as the highest number of frequency modes(90 mods).Furthermore,the panel had the highest STL regarding the area under the STL curve(dB∙Hz).The panels containing more frequency mods,have a higher transmission loss.Moreover,the sound transmission loss is more sensitive to the cell angle variable(θ).In other studies,the STL was more sensitive to the number of honeycomb cells in the horizontal and vertical directions,as well as the angle of cells.

Minimizing transmission loss using inspired ant colony optimization and Markov Chain Monte Carlo in underwater WSN environment

In Underwater Wireless Sensor Networks(UWSNs),the most important challenging issues are propagation delay,high error probability,high latency,high communication cost,limited bandwidth,limited memory,low packet delivery ratio,and transmission loss.In our proposed work,the various efforts are taken to minimize the propagation delay and transmission loss during data transmission in an underwater environment.A hybrid mechanism is implemented to improve energy efficiency for faster data transmission in underwater WSN.In the underwater environment of acoustic channel condition,propagation delay and transmission loss lead to high complexity in accessing the information and also it is difficult to obtain the Channel Status Information(CSI).To address this problem,Ant Colony Optimization(ACO)routing with Markov Chain Monte Carlo(MCMC)algorithm is used and to capture the transmission loss in the MCMC approach,CSI Forecast Prediction(FP)algorithm is used.The experimental simulations are evaluated by utilizing the performance evaluation metrics such as Transmission Loss,Probability Density Function,Average Delay and Throughput.From the simulation results it is evident that the proposed algorithm,ACO-MCMC has recorded the minimum transmission loss,increase in probability density function,minimum average delay and maximum throughput of the network when compared to the existing algorithms.

Distributed consensus-based algorithm for social welfare in smart grid with transmission losses

In this paper, we present a distributed consensus-based algorithm to solve the social welfare maximization problem. This is one of typical problems of distributed energy management in smart grid. In this problem, we consider not only the generator and demand, but also the transmission losses which make the feasibility set of the formulated problem a non-convex set. In solving this issue, we find a noticeable result that the primal problem has the same solution with a new convex optimization problem by getting the utmost out of the implied term in practice. Considering the general communication topology among generators and demands, we first design a finite step algorithm to make each generator and demand know the information of parameters of others.Then, we design a distributed algorithm and also prove the optimality and convergence of the proposed algorithm. Finally, the convergence and optimality are examined through extensive simulations.

Estimation of boundary parameters and prediction of transmission loss based upon ray acoustics

Estimation of boundary parameters and prediction of transmission loss using a coherent channel model based upon ray acoustics and sound propagation data collected in field experiments are presented. Comparison between the prediction results and the experiment data indicates that the adopted sound propagation model is valuable, both selection and estimation methods on boundary parameters are reasonable, and the prediction performance of transmission loss is favorable.

Studies on the sound absorption and transmission loss performances of wood-based, natural and wastematerials

The sound absorption and sound transmission loss performances of the natural woods,hard and soft processed woods with attachment of the various natural orwastematerials were investigated in the present study using impedance tube with American Society for Testing Material(ASTM)standards.The sound absorption performances of all natural and all hard processed woods were very poor.It was found that filter mat made by the coconut fibre was the best material for sound absorption improvement of the hard processed woods.The sound absorption performance of the soft processed wood(cork)was better than all natural and all hard processed woods.Among all tested woods,it was found that the cork with attached tea bag made by corn fibre is the best selection for sound absorption application.The transmission loss performances of all natural woods were good.The effects of various materials on the transmission loss performances of all hard processed woods were not very significant.For cork with and without attachment of various materials,their transmission loss performances were not as good as the hard processed woods.Among all tested woods,it was found that Pterocarpus soyauxii and Quercus spp.(natural woods)are the best woods to be used in those applications when prevention of sound transmission is needed.It is recommended that cork is the best wood to be used in those applications where sound absorption and prevention of sound transmission are needed at the same time due to its good sound absorption performance while its ability on prevention of the sound transmission is also acceptable.

Evaluation of Transmission Losses of Various Battery Electric Vehicles

Transmission losses in battery electric vehicles have compared to internal combustion engine powertrains a larger share in the total energy consumption and play therefore a major role.Furthermore,the power flows not only during propulsion through the transmissions,but also during recuperation,whereby efficiency improvements have a double effect.The investigation of transmission losses of electric vehicles thus plays a major role.In this paper,three simulation models of the Institute of Automotive Engineering(the lossmap-based simulation model,the modular simulation model,and the 3D simulation model)are presented.The lossmap-based simulation model calculates transmission losses for electric and hybrid transmissions,where three spur gear transmission concepts for battery electric vehicles are investigated.The transmission concepts include a single-speed transmission as a reference and two two-speed transmissions.Then,the transmission lossmaps are integrated into the modular simulation model(backward simulation)and in the 3D simulation model(forward simulation),which improves the simulation results.The modular simulation model calculates the optimal operation of the transmission concepts and the 3D simulation model represents the more realistic behavior of the transmission concepts.The different transmission concepts are investigated in Worldwide Harmonized Light Vehicle Test Cycle and evaluated in terms of transmission losses as well as the total energy demand.The map-based simulation model allows the transmission losses to be broken down into the individual component losses,thus allowing transmission concepts to be examined and evaluated in terms of their efficiency in the early development stage to develop optimum powertrains for electric axle drives.By considering transmission losses in detail with a high degree of accuracy,less efficient concepts can be eliminated at an early development stage.As a result,only relevant concepts are built as prototypes,which reduces development costs.

An experimental investigation on sound transmission loss and vibration reduction of a vessel in water

Experimental results of sound transmission loss in a range of frequency through bubbly curtains were obtained, where the air content was in a wide range by means of varying pressure differences and the diameters of the pores of bubble-produce apparatus . Vibration reduction of a vessel in water due to the bubbly curtain was found.

Influence of intra-cavity loss on transmission characteristics of fiber Bragg grating Fabry–Perot cavity

A theoretical model of the fiber Bragg grating Fabry–Perot（FBG-FP） transmission spectrum considering loss of FBG and intra-cavity fiber is presented. Several types of FBG-FPs are inscribed experimentally, and their spectra are measured.The results confirm that weak intra-cavity loss is enhanced at the resonance transmission peak, that is, loss of transmission peaks is observably larger than other wavelengths. For FBG-FPs with multi resonance peaks, when the resonance peak wavelength is closer to the Bragg wavelength, the more significant loss effect of resonance transmission peak is exhibited.The measured spectra are fitted with the presented theoretical model. The fitted coefficient of determinations are near 1,which proves the validity of the theoretical model. This study can be applied to measure FBG loss more accurately, without a reference light. It can play an important role in FBG and FBG-FP writing process optimization and application parameter optimization.

Suppression of low-frequency ultrasound broadband vibration using star-shaped single-phase metamaterials

In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation properties,which is configured by hybrid arc and sharp-angle convergent star-shaped lattices.The effect of the dispersion relation and the bandgap characteristic for the scatterers in star-shaped are simulated and analyzed.The target bandgap width is extended by optimizing the geometry parameters of arc and sharp-angle convergent lattices.The proposed metamaterial configured by optimized hybrid lattices exhibits remarkable broad bandgap characteristics by bandgap complementarity,and the simulation results verify a 99%vibration attenuation amplitude can be obtained in the frequency of20 k Hz—100 k Hz.After the fabrication of the proposed hybrid configurational star-shaped metamaterial by 3D printing technique,the transmission loss experiments are performed,and the experimental results indicate that the fabricated metamaterial has the characteristics of broadband vibration attenuation and an amplitude greater than 85%attenuation for the target frequency.These results demonstrate that the hybrid configurational star-shaped metamaterials can effectively widen the bandgap and realize high efficiency attenuation,which has capability for the vibration attenuation in the application of highprecise equipment.

Wave transmission through laminated composite double-walled cylindrical shell lined with porous materials

A study on free harmonic wave propagation in a double-walled cylindrical shell, whose walls sandwich a layer of porous materials, is presented within the framework of the classic theory for laminated composite shells. One of the most effective components of the wave propagation through the porous core is estimated with the aid of a flat panel with the same geometrical properties. By considering the effective wave component, the porous layer is modeled as a fluid with equivalent properties. Thus, the model is simplified as a double-walled cylindrical shell trapping the fluid media. Finally, the transmission loss （TL） of the structure is estimated in a broadband frequency, and then the results are compared.

Analysis of DC Power Transmission Using High T_c Superconducting Cables

A conceptual superconducting DC cable model is designed and its magnetic fields distribution is analyzed with Ansoft/Maxwell soft. A DC Power transmission system is also studied by using the Matlab/Simulink. With the DC Line and AC Ground Fault, the system losses analysis is introduced.The analysis results mainly include the magnetic fields distribution of the HTS cable model with Ansoft/Maxwell, the system loss, the DC Line and AC Ground Fault with Matlab/Simulation.

Power transmission through double-walled laminated composite panels considering porous layer-air gap insulation

The acoustic behavior of double-walled laminated composite panels consisting of two porous and air gap middle layers is studied within the classical laminated plate theory （CLPT）. Thus, viscous and inertia coupling in a dynamic equation, as well as stress transfer, thermal and elastic coupling of porous material ave based on the Biot theory. In addition, the wave equations are extracted according to the vibration equation of composite layers. The transmission loss （TL） of the structure is then calculated by solving these equations simultaneously. Statistical energy analysis （SEA） is developed to divide the structure into specific subsystems, and power transmission is extracted with balancing power flow equations of the subsystems. Comparison between the present work and the results reported elsewhere shows excellent agreement. The results also indicate that, although favorable enhancement is seen in noise control particularly at high frequencies, the corresponding parameters associated with fluid phase and solid phase of the porous layer are important on TL according to the boundary condition interfaces. Finally, the influence of composite material and stacking sequence on power transmission is discussed.

Analytical model of sound transmission through laminated composite cylindrical shells considering transverse shear deformation

Composite structures are often used in the aerospace industry due to the advantages offered by a high strength to weight ratio. Sound transmission through an infinite laminated composite cylindrical shell is studied in the context of the transmission of airborne sound into the aircraft interior. The shell is immersed in an external fluid medium and contains internal fluid. Airflow in the external fluid medium moves with a constant velocity. An exact solution is obtained by simultaneously solving the first-order shear deformation theory （FSDT） of a laminated composite shell and the acoustic wave equations. Transmission losses （TL） obtained from numerical solutions are compared with those of other authors. The effects of structural properties and flight conditions on TL are studied for a range of values, especially, the Mach number, stack sequences, and the angle of warp. Additionally, comparisons of the transmission losses are made between the classical thin shell theory （CST） and FSDT for laminated composite and isotropic cylindrical shells.

浅水声学通信中的多路径几何信道模型

Using the underwater acoustic channel(UWA)for information dissemination requires a high data rate.However,some phenomena like refraction,reflection,phase shift,and high attenuation are undesirably apparent when the subject of using UWA is raised.Accordingly,sound communication would be a highly challenging task to be accomplished.Therefore,proposing a model of acoustic underwater communication channels is critical because of the multipath interference originating from the surface and bottom of the ocean.In this contribution,a straightforward geometry channel model for vertical and horizontal marine communications is presented.To do so,transmission loss and channel impulse response are analyzed as a function of transmitter and receiver distance,water depth,and reflection rate.The results of the model proposed in this paper are in very good agreement with those available in the literature.Initial findings indicate that the delay spread of horizontal communication with a 1000 m range reaches79 ms and 0.3 s for 30 m vertical communication.

Research on Hydrodynamic Interference Suppression of Bottom-Mounted Monitoring Platform with Fairing Structure

In the disturbance of unsteady flow field under the sea, the monitoring accuracy and precision of the bottom-mounted acoustic monitoring platform will decrease. In order to reduce the hydrodynamic interference, the platform wrapped with fairing structure and separated from the retrieval unit is described. The suppression effect evaluation based on the correlation theory of sound pressure and particle velocity for spherical wave in infinite homogeneous medium is proposed and the difference value between them is used to evaluate the hydrodynamic restraining performance of the bottom-mounted platform under far field condition. Through the sea test, it is indicated that the platform with sparse layers fairing structure(there are two layers for the fairing, in which the inside layer is 6-layers sparse metal net, and the outside layer is 1-layer polyester cloth, and then it takes sparse layers for short) has no attenuation in the sound pressure response to the sound source signal, but obvious suppression in the velocity response to the hydrodynamic noise. The effective frequency of the fairing structure is decreased below 10 Hz, and the noise magnitude is reduced by 10 d B. With the comparison of different fairing structures, it is concluded that the tighter fairing structure can enhance the performance of sound transmission and flow restraining.