Wind turbine sound propagation: Comparison of a linearized Euler equations model with parabolic equation methods.

Noise generated by wind turbines is significantly impacted by its propagation in the atmosphere. Hence, for annoyance issues, an accurate prediction of sound propagation is critical to determine noise levels around wind turbines. This study presents a method to predict wind turbine sound propagation based on linearized Euler equations.

Validity of the effective sound speed approximation in parabolic equation models for wind turbine noise propagation.

Parabolic equation (PE) based methods are widely used in outdoor acoustics because they can solve acoustic propagation problems above a mixed ground in a refractive and scattering atmosphere. However, recent research has shown phase error due to the effective sound speed approximation (ESSA). To overcome these limitations, a new PE formulation derived without the ESSA has been proposed recently.

Synthesis of wind turbine trailing edge noise in free field.

The proposed sound synthesis tool converts a physics-based frequency-domain model of wind turbine trailing edge noise to a time-domain signal while accounting for the appropriate time shift due to the propagation between the moving blades and the fixed observer. A window function that implements cross-fading between consecutive signal grains is proposed and a method to objectively estimate the influence of the synthesis parameters is described. As the synthesis tool is independent of the aerodynamic noise model, it can be readily adapted to auralize other noise sources such as turbulent inflow noise or stall noise.

Environmental parameters sensitivity analysis for the modeling of wind turbine noise in downwind conditions.

Modeling a wind turbine sound field involves taking into account the main aeroacoustic sources that are generally dominant for modern wind turbines, as well as environmental phenomena such as atmospheric conditions and ground properties that are variable in both time and space. A crucial step to obtain reliable predictions is to estimate the relative influence of environmental parameters on acoustic emission and propagation, in order to determine the parameters that induce the greatest variability on sound pressure level. Thus, this study proposes a Morris sensitivity analysis of a wind turbine noise emission model combined with a sound propagation model in downwind conditions.

Staphylococcus capitis isolated from bloodstream infections: a nationwide 3-month survey in 38 neonatal intensive care units.

To increase the knowledge about S. capitis in the neonatal setting, we conducted a nationwide 3-month survey in 38 neonatal intensive care units (NICUs) covering 56.6% of French NICU beds.

Dynamical properties of piano soundboards.

In pianos, the transfer of energy from strings to soundboard and the radiation of sound are highly dependent on the dynamical properties of the soundboard. In this paper, a numerical study is conducted for various rib configurations, showing that even slight irregularities in rib spacing can induce a strong localization of the soundboard velocity pattern. The effective vibrating area can be further reduced due to the spatial filtering effect of the bridge.

Theoretical study for safe and efficient energy transfer to deeply implanted devices using ultrasound.

The goal of this paper is to prove that a safe and efficient energy transfer is possible between an external transducer located on the patient's skin and a device deeply implanted in the abdomen. An ultrasound propagation model based on the Rayleigh-Sommerfeld diffraction integral is coupled with the data from the Visible Human Project to account for the geometry of the organs in the body. The model is able to predict the amount of acoustic power received by the device for different acoustic paths.

In-vitro platform to study ultrasound as source for wireless energy transfer and communication for implanted medical devices.

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.

Suitable acoustic paths to transfer energy in depth using ultrasound.

The goal of this study is to optimize the transfer of acoustic energy deep in the body. In order to find suitable acoustic paths for the energy transfer to be efficient, we propose a model of ultrasound propagation that takes into account a realistic geometry of the tissue layers inside the human body. The data from the Visible Human Project is used to identify the tissues between the transducer array and the target point located on the epicard of the heart.

Time-domain simulations of sound propagation in a stratified atmosphere over an impedance ground.

Finite-difference time-domain simulations of broadband sound propagation in a stratified atmosphere are presented. A method recently proposed to obtain an impedance time-domain boundary condition is implemented in a linearized Euler equations solver, which enables to study long range sound propagation over an impedance ground. Some features of the pressure pulse evolution with time are analyzed in both upward-and downward-refracting conditions, and the time-domain simulations are compared to parabolic equation calculations in the frequency domain to show the effectiveness of the proposed impedance boundary condition.

Clinical and ultrasonographic correlations following three surgical anti-incontinence procedures (TOT, TVT and TVT-O).

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.

[Peritoneum and laparoscopic environment].

Laparoscopic surgery takes place in a closed environment, the peritoneal cavity distended by the pneumoperitoneum whose parameters, such as pressure, composition, humidity and temperature of the gas, may be changed and adapted to influence the intra and postoperative surgical processes. Such changes were impossible in the "open" environment. This review includes recent data on peritoneal physiology, which are relevant for surgeons, and on the effects of the pneumoperitoneum on the peritoneal membrane.