This article presents an agile passive-mixer-first superheterodyne RF front-end that utilizes a gigahertz acoustic filter as its intermediate-frequency (IF) load-essentially mixer-first acoustic-filtering front-end. The passive mixer frequency-translates sharp but fixed-frequency response to much higher and mixer-clock-defined tunable frequency while preserves input matching, high linearity, in...

permeability is a key parameter in reservoir characterization. in fact, without accurate information about reservoir permeability, there is no good solution for reservoir engineering problems. up to now, permeability values of a reservoir have been calculated through laboratory measurements or well testing methods. these methods are useful but they cannot describe a reservoir reliably and preci...

In this paper we describe a system which we have developed to measure cat ear canal specific acoustic impedance Zsp, magnitude and phase, as a function of frequency, for frequencies between 200 Hz and 33 kHz, and impedance magnitude between 4.0 to 4.0×105 [Rayles] (MKS). The object to be measured is placed at the end of a 3.5 mm diameter sound delivery tube. After a simple calibration procedure...

In a weakly coupled structural-acoustic problem, the boundary conditions may be composed by two conditions. One is a velocity boundary condition, which can be obtained from a dynamic structural analysis and the other is an acoustic impedance boundary condition. The acoustic impedance boundary condition is used for modeling acoustic absorbent behavior at boundaries proportional to the velocity d...

In this paper, the underlying concept of acoustic liner is an electroacoustic transducer which acoustic impedance can be changed by electrical means, be it passive or active. Among the different ways to obtain variable acoustic properties on an electroacoustic transducer's voicing face is the shunting of the transducer's electrical input. With such shunt devices, the acoustic impedance that the...

Because all microstrip antennas have to be matched to the standard generator impedance or load, the input impedance matching method for antenna is particularly important. In this paper a new methodology in achieving matching impedance of a planar microstrip antenna for wireless application is described. The method is based on embedding an Interdigital capacitor. The fine results obtained by usi...

Variable acoustic properties can be obtained at the diaphragm of an electroacoustic transducer, with the help of very basic control strategies, among which is the simple electrical shunting of the transducer. These shunt techniques are compared to active feedback techniques for controlling the acoustic impedance of an electroacoustic transducer. It is shown here that the formulation of feedback...

Inverse filtering of oral airflow using closed-phase linear prediction is expected to preserve the effects of source-filter interactions in the glottal airflow pulse. Under incomplete glottal closure, the glottal airflow estimation is more challenging due to a lowered glottal impedance, increased subglottal coupling, and violated all-pole assumption. To account for these effects, a model-based ...

The input acoustic impedance of musical wind instruments necessarily has a dramatic variation with frequency. Our technique uses an acoustic current source whose output is calibrated on a purely resistive load, provided by a ‘semi-infinite’ cylindrical pipe. The frequencies, amplitudes and phases of the sinusoidal components in the stimulus are chosen explicitly to provide the desired frequency...

Ultra-broadband sound absorption with periodic gradient impedance matching is of great concern in the research acoustic materials. This study investigates composite metamaterials comprising micro-perforated plates (MPPs) and subsequent Fabry–Pérot(FP) channels. Based on theory, ultra-broadband has been realized through a design 36 channels whose thickness only 50 mm. Also, average coefficient 8...