The effect of the slit length on acoustic transfer impedance micro-slit plates (MSPs) is investigated in linear and non-linear regime for a specific geometry. This geometry inspired by slits obtained cutting bending plate. MSPs are with arrays slit-shaped perforations, width order viscous boundary layer thickness. Impedance tube measurements two accurately manufactured compared to numerical sol...

A zero-voltage switching (ZVS) H-bridge phase-shifted low-voltage high-current converter with saturable inductors is proposed in this paper. The introduction of solves the short circuit problem caused by high-frequency on–off power tube, and effectively inhibits voltage oscillation spikes rectifier tube. In addition, when current flowing through inductor does not change rapidly, it exhibits a l...

Urban vegetation, such as vegetated roofs, is highly important for recovering the ecological balance and providing visually pleasant environments. Also, it has potential to reduce urban noise levels. The acoustic surface impedance of roofs can be determined by an in-situ two-microphone technique. However, different initial estimations model parameters retrieve completely sets material propertie...

Abstract The paper describes a design, building and testing low-cost impedance tube for measuring the acoustic parameters of small samples. measurement sound absorption coefficient is based on transfer function two microphone method in accordance with ISO 10534-2 ASTM E 1050 standards. With configuration updates after installation additional microphones apparatus complex material properties can...

OBJECTIVE To demonstrate that a nutritional support intervention, via naso-enteral tube-feeding or gastrostomy, has a significant impact on the nutritional status and body composition in severely malnourished children with cerebral palsy spastic quadriplegia. METHODS Thirteen patients with moderate/severe malnutrition and cerebral palsy spastic quadriplegia who were fed via naso-enteral tube-...

Valveless pumping can be achieved through the periodic compression of a pliant tube asymmetrically from its interfaces to different tubing or reservoirs. A mismatch of characteristic impedance between the flow channels is necessary for creating wave reflection sites. Previous experimental studies of the behaviour of such a pump were continued in order to demonstrate the wave mechanics necessary...

A method is described for characterizing the acoustical properties of flute head joints by measurement ofthe quantities F. =f./(2n -I), wheref. is the frequency of the nth impedance maximum of the head joint as viewed from the end of a short cylindrical tube simulating a part of the flute body and with the embouchure hole completely unobscured. The tube length is chosen to makef•_ 170 Hz. It is...

New acoustic multilayer absorber fabricated by coupling closed-cell metallic foam and open-cell polymeric foam, which aimed to develop a practical use of in the noise control application. In prior, individual sound absorption coefficient both materials with different thicknesses measured impedance tube method as per ASTM E-1050. Using inverse characterization technique, intrinsic properties nee...