Acoustic CT System for Temperature Distribution and Wind Velocity Vector Measurement
In this report, a measurement method for cross-sectional temperature and wind velocity distribution is discussed. A novel method based on an acoustic CT technique is proposed. Specifically, the temperature and the wind velocity distributions are estimated simultaneously using the time of flight data of several ultrasonic propagation paths. The temperature and the wind velocity effects can be distinguished by considering sum and difference of the time of flight (TOF) data. Two types of projection data, temperature-oriented data and wind-velocity-oriented data, components are obtained. A filtered back projection method and inverse matrix method are applied to reconstruct the temperature and the wind velocity distributions, respectively. An experimental system is designed and fabricated to realize simultaneous temperature and wind velocity distribution measurements. Through this system, the effectiveness of the proposed measurement method is confirmed.
Tomographic reconstruction of vector fields
The application of tomography to the reconstruction of vector fields is considered. Two different types of interaction between the radiation used for measurement and the investigated vector fields are discussed. A complete reconstruction of a vector field can only be obtained if measurements based on both types of interaction are available. Otherwise, only curl-free or source-free components of the field can be reconstructed. In the case of nonhomogeneous boundary conditions, additional harmonic field components occur. Some experimental results are presented showing the reconstruction of flow velocity fields based on ultrasonic time-of-flight measurements. >
Investigations of dielectric gratings using electrodynamic models based on volume integral equations
Eigenmodes of planar and cylindrical dielectric gratings (DGs) and electromagnetic wave scattering from multiplayer DGs are investigated. The DG characteristics are calculated using numerical-analytical solution of integral equations (IEs).