IEEE Transactions on Biomedical Engineering

Eight different discrete time mean frequency estimators for complex Doppler signals are derived and analyzed. The estimators are well suited for use in multigated Doppler ultrasound measurements of blood velocity profiles. Approximate expressions for bias and variance of the estimators are derived. A general scheme for extending the analyzing range of discrete time Doppler frequency estimators abo... View full abstract»

This paper describes a control algorithm for a system built to deliver and control, for artificially ventilated patients, O2 and CO2 concentrations of either the inspiratory, expiratory, or alveolar gases without using an external supply of CO2. The system used is composed of a slightly modified respirator and a rebreathing bag controlled by a microcomputer. If αand ßdenote the relati... View full abstract»

In principle, orthoses employing electrically stimulated muscles can be improved by the incorporation of closed-loop control systems to regulate muscle output. One obstacle to attaining acceptable closed-loop control systems is the muscle recruitment characteristic, a memoryless, nonlinear, time-varying relationship between the recruitment modulation stimulus parameter (pulsewidth or amplitude) an... View full abstract»

The ability to predict complete temperature profiles from temperature measurements at a few locations is an important and difficult problem in cancer hyperthermia treatments; it is especially difficult because of a lack of knowledge of the tissue blood perfusion patterns and magnitudes. This paper describes an attempt to determine some of the characteristics of the problem so that it may be solved... View full abstract»

A set of quantitative data about signal processing effects on the evaluation of amplitude, duration, and peak-velocity of single saccadic eye movements, as well as on the evaluation of the coefficients of amplitude-peak velocity and amplitude-duration characteristics of a family of saccades, is given. The following aspects of signal processing are theoretically discussed, experimentally supported,... View full abstract»

Image analysis techniques are described for the automatic detection, segmentation, feature description, and classification of tissue components, in liver tissue images. The result of the analysis is a quantitative description of the tissue, based on statistics of the components. A software package for analysis of these images has been developed by combining some newly developed algorithms with oth... View full abstract»

The basic mechanisms of electromagnetic heating of metal implants in cancer therapy are considered. Using several models, it is pointed out that the quadrature-induced currents should be maximized to make the most efficient use of the implants, insofar as optimizing the power dissipated per unit volume of ferromagnetic material. View full abstract»

Traditionally, analog circuits have been used for signal conditioning of electrocardiograms. As an alternative, algorithms implemented as programs on microprocessors can do similar filtering tasks. Also, digital filter algorithms can perform processes that are difficult or impossible using analog techniques. Presented here are a set of real-time digital filters each implemented as a subroutine. By... View full abstract»

Filtering CT images to remove noise, and thereby enhance the signal-to-noise ratio in the images, is a difficult process because CT noise is of a broad-band spatial-frequency character, overlapping frequencies of interest in the signal. We present a measurement of the noise power spectrum of a CT scanner and show that some form of spatially variant filtering of CT images can be beneficial if the f... View full abstract»

An improved SIRT-style reconstruction algorithm has been suggested using a beam concept for linear first-order microwave tomographic imaging. The results of applying the algorithm on a small-scale model having a simplified data-collecting arrangement have been extremely encouraging and indicate the possibility for achieving a high-resolution microwave imaging system. However, the contrast in the p... View full abstract»

The continued interest in diagnostic applications of ultrasound has led to a need for more detailed knowledge of the ultrasonic properties of biological tissues. This communication describes an experimental system based on a Z-80 microprocessor which communicates with other devices via an STD bus for measuring ultrasound velocity in biological tissues as a function of temperature. Data have been c... View full abstract»