Volume 11 (2011): Issue 6 (January 2011)

This paper presents a complete system that can be used to measure and to stimulate sucking abilities of premature babies. The system integrates measurement and stimulation capabilities that can be used separately or together. The sensing unit includes mainly a pressure sensor, a conditioning circuit and a microcontroller device. The stimulation unit includes a miniature and low-cost pneumatic pump, an electro-valve, and a conditioning circuit. The microcontroller is shared by both units. The system's software includes a routine that is used to define the waveform parameters of the synthesized pressure signals, a wavelet based routine that is used to process measurement data and a software component to perform fault detection and diagnosis. The system capabilities include self-calibration and self-testing. Throughout the paper several implementation details and experimental results will be presented and discussed.

T-wave alternans (TWA) allows for identification of patients at an increased risk of ventricular arrhythmia. Stress test, which increases heart rate in controlled manner, is used for TWA measurement. However, the TWA detection and analysis are often disturbed by muscular interference. The evaluation of wavelet based denoising methods was performed to find optimal algorithm for TWA analysis. ECG signals recorded in twelve patients with cardiac disease were analyzed. In seven of them significant T-wave alternans magnitude was detected. The application of wavelet based denoising method in the pre-processing stage increases the T-wave alternans magnitude as well as the number of BSPM signals where TWA was detected.

An original method is proposed for estimating the position and velocity of a moving ball using a single line-scan camera. The method consists of two steps: firstly, the ball's initial position and velocity are determined by several key points in the image, and secondly, these parameters are further refined by a model-based optimization algorithm. The algorithm achieves accurate parameter estimation by matching the projection contour of the real ball and that of the same size sphere model. Finally, the relevance and accuracy of the method are experimentally confirmed on synthetic and real images.

A new model for the sample of square cross section with cuboid geometry including the effect of heat loss from the surface of the sample was tested using the theory of sensitivity coefficients. Theoretical calculation of model uncertainty and derived analytical formulas are presented. Results of the uncertainty analysis set out the range of experimental conditions under which the model is valid and the uncertainty of estimated parameters is low. Propagation of error for non-stochastic dynamic measurements based on the sensitivity coefficients shows limitations related to a range of model validity. The analysis improves the accuracy of measurements. The model was used for data evaluation of thermophysical parameters measured on the sandstone from the locality Pravčická brána. Evaluation procedure was tested on experimental data measured under different experimental conditions. In conclusion, the discussion of the experiment optimization is presented.

A microcontroller (AT89C51) based electronics has been designed and developed for high precision calibrator based on Digiquartz pressure transducer (DQPT) for the measurement of high hydrostatic pressure up to 275 MPa. The input signal from DQPT is converted into a square wave form and multiplied through frequency multiplier circuit over 10 times to input frequency. This input frequency is multiplied by a factor of ten using phased lock loop. Octal buffer is used to store the calculated frequency, which in turn is fed to microcontroller AT89C51 interfaced with a liquid crystal display for the display of frequency as well as corresponding pressure in user friendly units. The electronics developed is interfaced with a computer using RS232 for automatic data acquisition, computation and storage. The data is acquired by programming in Visual Basic 6.0. This system is interfaced with the PC to make it a computer controlled system. The system is capable of measuring the frequency up to 4 MHz with a resolution of 0.01 Hz and the pressure up to 275 MPa with a resolution of 0.001 MPa within measurement uncertainty of 0.025%. The details on the hardware of the pressure measuring system, associated electronics, software and calibration are discussed in this paper.

The knowledge of moisture content in cement based material is important especially for the safety in field work. In this paper, a non-destructive and contactless free space method is used for measurement of moisture content in cement based materials (mortar) at microwave frequencies. The measurement system consists of a 17 GHz dielectric resonator oscillator (DRO) as a microwave source, a Power Meter as the detector, and a pair of lens horn antennas to transmit and receive the microwave signal. An empirical formula of moisture content was obtained by using a relationship between attenuation and moisture content. This model is best for prediction of moisture content greater than 2% with percentage mean error of 3%.

A linear heating system has been developed using field programmable gate array (FPGA) for the measurement of thermoluminescence (TL) in alkali halides and other related compounds. Thermoluminescence plays an essential part in radiation dosimetry. This system measures the temperature and the amount of light emitted by the sample for TL studies. This work proposed an architectural framework, verilog HDL code for protocols for reading temperature from Thermocouple through ADC, processing of data (amount of light energy) in FPGA, sending control signal to the heater and displaying the temperature in LCD. This work shows performance improvement 3 times in comparison with conventional embedded system. The power consumption is also comparatively lower.