Elastography is an emerging ultrasonic imaging technique; it has a broad clinical application for tissue parameter estimation. We designed a real-time system to measure tissue stiffness information ...non-invasively based on transient elastography. The system performance mainly depends on the circuit design before the Analog-to-Digital Converter (A/D), especially the preamplifier part which is very sensitive to the noise. How to improve the signal-to-noise (SNR) is the key factor for the system design. In this paper, the Time Gain Control (TGC) design is discussed as an example of the circuit design. Displacement tracking algorithm based on correlation techniques and differentiation are applied to Radio frequency (RF) signals from tissues mimicking phantom and in vivo experiments; the young's modulus of the tissue is estimated from the strain images. The influences of the SNR to the strain image quality are discussed. At the end, an improvement based on the AD9272 is proposed.
A novel electromagnetic structure, sine waveguide, is introduced. Its electromagnetic characteristics at terahertz range will be reported in this paper. From our calculations, this electromagnetic ...structure possesses quite low transmission loss compared to the rectangular waveguide. So it can be regarded as a good terahertz wave transmission line. As a periodical structure, it possesses filter characteristics, too. In addition, it can also be regarded as a slow wave structure which can support beam-wave interaction in traveling wave tube amplifier for amplifying terahertz wave.
A new blind equalization algorithm based on LMS-Newton gradient is proposed. In order to decline complexity of algorithm and obtain faster convergence speed, a new cost function according to the ...principle of Euclidean distance is designed. The effectiveness of the new algorithm is illustrated by way of computer simulations.
