For several decades Proportional-Integral-Derivative control (PID) has been successfully used for a wide variety of industrial processes and remains the most used method. Recent work concerning the tuning of PID control coefficients has been proven to provide both robust and near-optimal performance using a Frequency Loop Shaping (FLS) procedure. The FLS tuning method minimizes the difference b...

A tire pressure measuring system based on surface acoustic wave (SAW) sensors is presented. Since SAW sensors are powered by the energy of the RF field no battery is required, which is a major drawback of conventional systems. A successful combination of a SAW reflective delay line with a capacitive pressure sensor is shown. With a new way of matching the sensor impedance to the SAW reflector i...

In this paper, the elastic properties of passive materials (matching, backing and lens materials) for ultrasound transducers are explored at room temperature in the frequency range of 25-65MHz using the ultrasonic spectroscopy method. AlurninaJEPOTEK 301 and tungsten/EPO-TEK 301 composites were fabricated and measured. Experimental results display a monotonic rise in acoustic impedance of the c...

A two-dimensional analytical solution is developed to determine the acoustic performance of a perforated single-pass, concentric cylindrical silencer filled with fibrous material. To account for the wave propagation through absorbing fiber and perforations, the complex characteristic impedance, wave number, and perforation impedance are employed. With expressions for the eigenvalues and eigenfu...

High-quality broadband ultrasound transducers yield superior imaging performance in biomedical ultrasonography. However, proper design to perfectly bridge the energy between the active piezoelectric material and the target medium over the operating spectrum is still lacking. Here, we demonstrate a new anisotropic cone-structured acoustic metamaterial matching layer that acts as an inhomogeneous...

Among structural acoustics methods, the electro-mechanical (E/M) impedance method is a new method that is easy to implement on complex structures with minimum instrumentation and straightforward results. This new acoustic method benefits from the advent of commercially available low-cost piezoceramics that have opened new opportunities for structural identification. The structural dynamics is i...

The nonlinear corrections for a Helmholtz resonator type impedance based on systematic asymptotic solution of the pertaining equations has been formulated in [1]. The length of the cavity considered was much smaller compared to the typical acoustic wavelength of interest so that the pressure inside could be assumed to be uniform. This way, the cavity worked as a spring to the external excitatio...

This paper describes the acoustic properties of a range of epoxy resins prepared by photocuring that are suitable for application in piezoelectric ultrasonic transducer matching layers. Materials, based on blends of diglycidyl ether of Bisphenol A and 1,4-cyclohexanedimethanol diglycidyl ether, are described. Furthermore, in order to vary the elastic character of the base resin, samples contain...

A model for calculating the acoustic characteristics of 3-D vocal tract con guration is presented. A mode-matching technique and an impedance transformation are used to calculate the higher-order modes in this model where both propagative and evanescent higher-order modes are considered. A cascaded structure of rectangular acoustic tubes is introduced as an approximation of the real vocal tract...

Highly sensitive air-coupled ultrasonic sensors are essential for various applications such as testing of composite materials. One of the major challenges for the development of air-coupled ultrasonic sensors is the impedance matching to air. With a lower acoustic impedance than the usual piezoelectric materials, charged cellular polypropylene film (cPP) offers better matching to air with a sim...