Ultrasound attenuation dependence on air compression or expansion processes

In this work variation of ultrasonic attenuation coefficient is analyzed in terms of air compression or expansion processes. In\ud closed spaces changing air volume, the ultrasound attenuation coefficient depends on thermodynamic processes which occur\ud during the air volume change. Two limiting cases are possible: 1) if the change of air volume is very slow or intensive heat\ud exchange occurs between the system and surrounding environments, so the system stays in a thermodynamic equilibrium;\ud therefore an isothermal process occurs; 2) if the change of air volume is very fast or the working environment has a good thermal\ud insulation, so the heat exchange between the system and the surrounding environment does not occur. In this case an adiabatic\ud process is presented. The attenuation coefficient of ultrasound varies very differently depending on the process (isothermal or\ud adiabatic) that occurs during the change of air volume. In particular, these differences occur when measurements are carried out in\ud a frequency range above 500 kHz during air compression. Initial relative air humidity has high influence on the ultrasonic signals\ud attenuation. Carrying out ultrasonic measurements in such systems, due to reliability of the measurements it is necessary to\ud evaluate thermodynamic process and ultrasound attenuation variation during the process. Oversaturated water vapour may occur\ud during the measurement process, therefore the measurement conditions become more complicated.\ud Keywords: attenuation of acoustic signals in air, relative humidity, isothermal process, adiabatic proces

Influence of ultrasonic radiation on the amorphous zeolite - Portland cement system

This paper considers the investigation of influence of an amorphous synthetic\ud zeolite with inserted $Ca^{2+}$ ions additive (ASZ) on the hydration temperature of Portland cement paste. In this investigation the sonicated Portland cement paste is compared to the non-sonicated paste; and then the cement paste hydration process is analyzed by the means of temperature measurements. The temperature measurement results confirm that the sonication process accelerates the exothermic chemical reaction between the Portland cement and water

Frequency selection for air-coupled ultrasonic measurements in closed chambers

In this work it is shown that a change in attenuation coefficient of ultrasound signal\ud depends on a nature of thermodynamic process when air-coupled ultrasonic\ud measurements are carried out in closed systems. Therefore, for the air-coupled ultrasonic\ud measurements in such systems, it is necessary to choose measurement system\ud parameters in advance according to the thermodynamic process is taking place in the\ud systems

Lane marker parameters for vehicle's steering signal prediction

The work considers road lane parameters that correlate with steering angle of a car and which are suitable for accurate prediction of steering signal using neural network technique. Four different parameters, which can be used in driver's assistance system and are based on position, angles and curvature of the lane marker, are proposed and their correspondence to steering signal is analyzed. The steering signal is predicted with the precision of 95% to 97%, depending on a combination of the visually-based parameters provided for the neural network. The work is performed using signals from real road driving

Estimation of lane marker parameters with high correlation to steering signal

This paper considers the design and analysis of lane marker parameters in 2-D images. Five different parameters, which have high correlation to the steering angle of a vehicle, are proposed, and their correspondence to the steering signal is analyzed. The parameters are based on the position, angle, area, and curvature of the lane marker and have not been reported in the literature before, except the curvature. A new derivative-free method is proposed for curvature estimation. The stability of the proposed parameters is analyzed with respect to the look-ahead distance. Possible application of the parameters for overtaking detection is presented. This paper is performed using signals from real country road driving

Lane marker parameters for vehicle's steering signal prediction

The work considers road lane parameters that correlate with steering angle of a car and which are suitable for accurate prediction of steering signal using neural network technique. Four different parameters, which can be used in driver's assistance system and are based on position, angles and curvature of the lane marker, are proposed and their correspondence to steering signal is analyzed. The steering signal is predicted with the precision of 95% to 97%, depending on a combination of the visually-based parameters provided for the neural network. The work is performed using signals from real road driving