Impedance matching is an essential part of antenna design. The input impedance of an antenna needs to be reasonably close to the amplifier impedance (e.g. 50 Ohm), otherwise the signal is reflected back to the amplifier and not radiated by the antenna. In many applications matching circuits consisting of discrete inductors and capacitors, or transmission lines are used to improve the impedance ...

We quantify the sensitivity of turbine acoustic impedance to aerodynamic design parameters. Impedance boundary conditions are an influential yet uncertain parameter in predicting thermoacoustic stability gas combustors. extend semi-actuator disk model cambered blades, using non-linear time-domain computations vane and stage cascades with forcing for validation data. Discretising aerofoils into ...

Reflection of sound waves, due to acoustic impedance mismatch at the interface of two media, is the principal physical property which allows visualization with ultrasound. In this paper, we investigate reconstruction of the acoustic impedance from ultrasound images for the first time. Similar to spatial compounding, we combine multiple images to improve the estimation. We use phase information ...

This paper describes an approach to the support of interface objects in an object-oriented database, and outlines some of the consequences of representing interface data as database objects. Existing architectures for implementing database interfaces are reviewed, and certain shortcomings identiied, which essentially stem from an impedance mismatch between the database and its interface. It is ...

The wave impedance and the environment impedance are important for the wave-variable based teleoperator. It is difficult to get good performance when the parameters are not proper. The paper addresses how to design the wave based teleoperator when working environment undergoes changed. It is concluded that wave impedance should match environment impedance by discussing how wave impedance and en...

This paper examines the feasibility of cloaking an obstacle using Plate-type Acoustic Metamaterials (PAMs). We present two distinct strategies to cloak this obstacle, either near-zero-density regime a periodic arrangement plates or acoustic doping phenomenon achieve simultaneous zero-phase propagation and impedance matching. The strong limitations induced by viscothermal viscoelastic losses tha...

A one-dimensional acoustic negative refractive index metamaterial based on the transmission line approach is presented. This structure implements the dual transmission line concept extensively investigated in microwave engineering. It consists of an acoustic waveguide periodically loaded with membranes realizing the function of series “capacitances” and transversally connected open channels rea...