Elmar Trautenberg

Digital Processing of Ultrasonic Data by Deconvolution

Abstrocr-Digital deconvolution of ultrasonic echo signals improves resolution and quality of ultrasonic images. Filtering usual B-scan images with a special digital fdter increases the lateral resolution by 50 percent. The filter is constructed from the measured signal amplitudes across the transmitter beam. By an empirical approach, it is optimized for low noise and high resolution. This method for lateral filtering produces good results for a great variety of test objects. The quality of the filter is maintained over a great range of depth, where the original beamwidth varies about 30 percent. This filtering method has high stability, such that application on measured profdes that are heavily disturbed does not increase noise nor produce disturbances.

Method for processing ultrasonic echo signals of both directionally reflecting as well as nondirectionally scattering objects, particularly for ultrasonic image processing in the field of substance or tissue investigation

In an exemplary embodiment, the processing techniques of computerized x-ray tomography are applied to improve resolution transverse to the depth direction, for example with the use of compound ultrasonic scanning. In this way, an improved preliminary image for representing non-directionally scattering image points is attained. The ultrasonic echo signals are also processed to provide a preliminary image based predominantly or exclusively on directionally reflecting image points. The respective preliminary images for each image point or point region are then suitably combined to provide a stored ultrasonic image capable of display of the scanned region of improved accuracy, resolution, and freedom from noise.

On the finite element simulation of fluid motion with high Reynolds or Grashof number

Abstract Numerical Simulation of free convection problems with usual Finite Element (FE) formulations run into stability problems for large Grashof numbers. This is true even for simple models. In regions where the stream velocity or the temperature field is constant along the stream lines, the stiffness matrix may become ill-conditioned for large stream velocities although its physical contribution vanishes. Besides a costly increase in the number of elements and corresponding decrease of the length unit, a change in the unit system can not improve the matrix condition. The ill-conditioning arises from the usual decomposition of the nonlinear convective terms into a velocity-dependent stiffness matrix which represents a differential operator and a solution vector on which the stiffness matrix operates. The problem should be solved by an adapted choice of the matrix representation of the nonlinear convective terms. Alternatively - and necessarily for Newton-Raphson iteration of the nonlinear equations - the ill-conditioning terms may be neglected within those elements, where their physical contribution is negligible.