Search results for "characteristic impedance"

showing 3 items of 3 documents

Experimental investigation of the effect of moisture on the acoustic properties of lightweight substrates used in green envelopes

2021

International audience; Substrates are used in green walls and roofs to supply air and water to the roots of the growing plants. These substrates are porous with micropores which store water and macropores which facilitate drainage and air entry. Effect of moisture on acoustic absorption is studied for two lightweight substrates: coir dust and perlite. Measurement of dry and moistened substrates are conducted to evaluate their effective speed of sound, attenuation, characteristic impedance, compressibility and density between 100 Hz and 1000 Hz using an impedance tube and the three microphone-two load method. Effect of moisture on these quantities is found to depend strongly upon the intera…

010302 applied physics[SPI.ACOU]Engineering Sciences [physics]/Acoustics [physics.class-ph]Materials scienceAcoustics and UltrasonicsMacroporeMoistureAcoustic porous mediumLightweight substrateSound absorption;Lightweight substrate;Acoustic porous medium;Moisture;Green envelopeGreen envelope01 natural sciencesCharacteristic impedance[SPI.MAT]Engineering Sciences [physics]/MaterialsSubstrate (building)Speed of sound0103 physical sciencesPerliteSound absorptionComposite material[SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/MicroelectronicsPorosity010301 acousticsMicroscale chemistryMoisture
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Calculation of the characteristic impedance of microstrips using a full-wave 2-D FDTD scheme

1997

The frequency dependence of the characteristic impedance of microstrip lines has been investigated by many authors using 3D-FDTD formulations. In the present letter, a two-dimensional FDTD scheme is used to calculate both the propagation constant and the characteristic impedance of the fundamental quasi-TEM mode in a microstrip which, in fact, is a hybrid mode. Because of the substantial reduction of computer resources required for the calculations, this method can be used as a design tool. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 58–60, 1997.

Engineeringbusiness.industryFinite-difference time-domain methodMode (statistics)Condensed Matter PhysicsAtomic and Molecular Physics and OpticsMicrostripCharacteristic impedanceElectronic Optical and Magnetic MaterialsComputational physicsScheme (mathematics)Electronic engineeringElectrical and Electronic EngineeringPropagation constantbusinessReduction (mathematics)MicrowaveMicrowave and Optical Technology Letters
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Power Line Communication in Medium Voltage Systems: Characterization of MV Cables

2008

The aim of this paper is to illustrate the development of a theoretical and experimental study on the characterization of medium voltage (MV) cables in the frequency range 25-200 kHz. Two transmission line configurations, line-ground and line-line, were considered in order to evaluate the main parameters, such as the characteristic impedance and the attenuation constant alpha. A simplified model of the line-ground configuration is proposed which allows one to evaluate the characteristic impedance and the attenuation constant by means of geometrical dimensions. The model was verified by experimental measurements on commonly used MV cables, RG7H1R, with an aluminium core of different sections…

power line communicationEngineeringbusiness.industryAttenuationAcousticsmedium voltage cablesEnergy Engineering and Power TechnologyAttenuation constantCharacteristic impedancelaw.inventionpower system communicationElectric power transmissionlawTransmission lineAttenuation coefficientElectrical networkElectronic engineeringcharacteristic impedanceAttenuation constant characteristic impedance medium voltage cables power line communication power system communication.Electrical and Electronic EngineeringbusinessElectrical impedanceVoltage
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