Abstract This paper investigates the impact of different matching layers on ultrasonic transducers’ performance. Matching are mostly used to solve acoustic impedance problem between piezoelectric element and test specimen. To design good layers, we merged metal–polymer mass–spring systems. Their thickness was also optimized using quarter-wavelength approach. Silver, alumina, copper served as ma...

As the number of publicly-available datasets are likely to grow, the demand of establishing the links between these datasets is also getting higher and higher. For creating such links we need to match their schemas. Moreover, for using these datasets in meaningful ways, one often needs to match not only two, but several schemas. This matching process establishes a (potentially large) set of att...

This paper presents kinematic and dynamic analysis of a holonomic vehicle with continuously-variable transmission. Four ball wheels, independently actuated by DC motors, enable for moving the vehicle in any direction within the plane and rotating it around its center. The angle between the two beams holding the balls can be changed to alter the gear ratio and other dynamic characteristics of th...

We proposed a new expression of speech feature called orientation patterns which keeps its ability of detection higher in averaging of time domain. Because of this, we achieved to reduce number of frames in reference and input pattern in DP matching algorithm, then the calculation load were reduced. We constructed long term speech retrieval system by using this new expression. This system has R...

In acoustic intensity estimation, adding a microphone at the probe center removes errors associated with pressure averaging. Analytical bias errors are presented for a one-dimensional, three-microphone probe for active intensity, reactive intensity, and specific acoustic impedance in a monopole field. Traditional estimation is compared with the Phase and Amplitude Gradient Estimator (PAGE) meth...

Acoustic impedance of perforations in contact with fibrous material, as well as air alone, is experimentally determined in the absence of mean flow. Different porosities 2.1, 8.4, 13.6, and 25.2 % and hole diameters 0.249 and 0.498 cm are applied for perforations, along with two fiber filling densities 100 and 200 kg/m3 to illustrate the effect of variations in such parameters on the perforatio...

This paper investigates wave-based analysis and impedance matching for the ladder electric networks. The results are a generalized version of our previous work for the cascade connected damped mass-spring systems. We first clarify the class of the ladder networks which satisfies the three conditions for the propagation constants to be analyzed by the wave-based analysis. Secondly, for the class...

Traditional didjeridus have a broad range of bore geometries with many details not immediately apparent to a player, and are therefore suitable for examining the relationship between perceived quality and physical properties. Seven experienced players assessed the overall playing quality of 38 didjeridus that spanned a wide range of quality, pitch, and geometry, as well as 11 plastic cylindrica...

Electromagnetics has an important role in power and energy industry. In this paper, the concept of rectenna is introduced firstly. The history of rectenna for wireless energy harvesting and transmission is then reviewed. Finally examples are employed to illustrate some rectenna design and measurement issues such as rectenna impedance matching and its conversion efficiency. It is also shown that...

Today’s modern commercial and military communication systems are demanding better performance with regards to power, effi ciency, linearity and operating bandwidth. As such, extra considerations must be placed on designing the internal components of the systems, including the low-noise and power amplifi ers, to maximize performance. In order to reach higher effi ciencies, signifi cant research ...