Finite difference time-domain methods are well suited to study sound propagation in the context of transportation noise. In this paper, time-domain boundary conditions are considered for impedance models classically used for outdoor grounds. These impedance models have usually been obtained in the frequency domain and cannot be translated directly into the time domain. The derivation of the time-domain boundary condition is based on the approximation of the impedance as a sum of well-chosen template functions. Because of the forms of the template functions, the recursive convolution technique can be applied; this is a fast and computationally efficient method to calculate a discrete convolution. The impedance boundary conditions are validated using a linearized Euler equations solver in one-and three-dimensional geometries; comparisons with analytical solutions in the time and frequency domains are presented. The methods used to identify the coefficients of the template functions are shown to be of great importance. Among the three methods described, the optimization method in the frequency domain can be recommended, because it can be applied to many impedance models and allows the values of the coefficients to be constrained, which is needed to obtain accurate numerical results. Nomenclature B= Gaussian half-width, m c 0 = speed of sound, m=s d L = porous layer thickness, m f = frequency, Hz Im = imaginary part j = imaginary unit k = complex wave number, m 1 p = pressure, Pa q = tortuosity Re = real part S = number of first-order systems in the impedance approximation s f = coefficient of the selective filter T = number of second-order systems in the impedance approximation t = time, s v = velocity component normal to impedance surface, m=s Z = complex impedance, kg=m 2 =s = ratio of specific heats L = sound pressure level relative to the free field, dB t = time step, s x = spatial mesh size, m 0 = air density, kg=m 3 0 , e = flow resistivity, Pa s=m 2 = porosity ! = angular frequency, rad=s

The aim of this study was to compare ultrasonographic findings on tape position, angulation and mobility following three surgical anti-incontinence procedures (trans-obturator tape (TOT), tension-free vaginal tape (TVT), tension-free vaginal tape obturator (TVT-O)) and to correlate these data with clinical signs of cures and failures and de novo voiding disorders. In this prospective study, vesicourethral static and dynamic analysis of 81 patients (30 TOT, 28 TVT, 23 TVT-O) were evaluated using introital ultrasonography. Width, position and appearance of the tape were similar in all three groups, i.e. like a "V" at rest, round angulation on Valsalva and closed angulation at maximum retaining. Moreover, closer angulation on Valsalva was associated with voiding disorders. Closer angulation at retaining was associated with de novo urge incontinence. Larger angulation of the tape at rest appeared to be significantly associated with recurrent stress incontinence. Ultrasonography could a be useful tool assessing anti-incontinence procedures and investigating post-operative voiding disorders.

International audienceBroadband noise generated aerodynamically is the dominant source for a modern wind turbine. In this paper, trailing edge noise and turbulent inflow noise are modeled using Amiet’s theory to predict wind turbine noise spectra, directivity and amplitude modulation. First, by comparing model predictions with wind tunnel experiments from the literature, we show that a wall pressure spectral model that includes the effect of an adverse pressure gradient is needed to correctly predict trailing edge noise spectra. Then, we adapt the model to rotating blades and compare sound power level spectra of trailing edge noise with field measurements, assuming a constant wind speed profile. A good agreement is found at frequencies higher than approximately 1000 Hz, but the levels are underestimated at lower frequencies. Finally, we account for wind shear and atmospheric turbulence effects using the Monin-Obukhov similarity theory. On the one hand, we show that angle of attack variations due to wind shear can produce a significant change in the wall pressure spectra of some blade sections, especiallyin stable atmospheric conditions, even though this effect is not clearly seen on the trailing edge noise spectra at the receiver. On the other hand, turbulent inflow noise does vary with atmospheric conditions, and contributes significantly to the noise radiated by a wind turbine at low frequencies. When both mechanisms are considered, the predicted sound power level spectra are in good agreement with measurements

In this retrospective study of 314 patients undergoing surgery for ovarian dermoid cysts, conducted over a 20-year period, we evaluated the impact of the routine use of laparoscopic surgery without recourse to laparotomy to retrieve the specimen, using an endoscopic retrieval bag placed under the cyst to prevent intraperitoneal spillage of cyst contents, and subsequent postoperative granulomatous peritonitis. Accidental cyst rupture was more frequent when a total laparoscopic approach was used (26/174 or 15% versus 39/140 or 28%; P = 0.005), but there were no cases of intraperitoneal spillage when an endoscopic bag was used. Two cases of granulomatous peritonitis developed out of 26 women with intraperitoneal spillage of cyst contents (8%). We conclude that the risk of granulomatous peritonitis can be minimised by undertaking laparoscopic removal of dermoid cysts with the routine intraoperative use of an endoscopic retrieval bag to prevent intraperitoneal spillage of cyst contents.

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To cite this version:Benjamin Cotté. Coupling of an aeroacoustic model and a parabolic equation code for long range wind turbine noise propagation. Journal of Sound and Vibration, Elsevier, 2018, 422, pp.343-357. 10.1016/j.jsv.2018 Coupling of an aeroacoustic model and a parabolic equation code for long range wind turbine noise propagation source approximation that is often used in wind turbine noise propagation models is finally assessed. This approximation exaggerates the interference dips in the spectra, and is not able to correctly predict the amplitude modulation.

Abstract-A platform to study ultrasound as a source for wireless energy transfer and communication for implanted medical devices is described. A tank is used as a container for a pair of electroacoustic transducers, where a control unit is fixed to one wall of the tank and a transponder can be manually moved in three axes and rotate using a mechanical system. The tank is filled with water to allow acoustic energy and data transfer, and the system is optimized to avoid parasitic effects due to cables, reflection paths and cross talk problems. A printed circuit board is developed to test energy scavenging such that enough acoustic intensity is generated by the control unit to recharge a battery loaded to the transponder. In the same manner, a second printed circuit board is fabricated to study transmission of information through acoustic waves.Index Terms-biomedical telemetry, energy scavenging, implanted medical devices, ultrasound, sensor networks, wireless communication.

Milk contaminated with melamine resulted in an important health hazard that affected many babies in China recently. Ultrasonic characterization of adulterated milk may detect gross levels of melamine contamination. Sound speed and density measurements were made in skim milk as a function of melamine adulteration. An ultrasonic measurement technique to implement milk quality control is discussed.