Study Of Ultrasonic Thermometry System Based On Particle Swarm Optimization

Energy problem has become the core issues of all countries in the world, the application of new technology for major technical transformation in energy intensive industries represented by chemical and metallurgical is imminent, the use of microwave heating instead of traditional heating can greatly improve the utilization rate of energy and achieve the goal of energy conservation and emissions reduction. However some technology bottleneck problem still exist in the large-scale industrial application of microwave heating, it is difficult to keep the application of high power microwave source efficient, safe and reliable. The existence of these problems is down to a lack of an effective measure for information acquisition, processing and control during the interaction process between microwave and time-varying medium, and the perception and reconstruction of internal temperature distribution of medium is the key to the effectiveness of the control. Considering the particularity of industrial processing environment, traditional way of thermometry is difficult to realize temperature measuring requirements, using ultrasonic thermometry technology will break through the limitation of the common way of thermometry.As a kind of non-contact temperature measuring method, ultrasonic thermometry technology has wide range of measuring and small interference to the temperature field, it is convenient for sensor arrangement, it is able to make real-time response to transient changes of the temperature field, and achieve continuous measurement of temperature field under some special environment such as the strong corrosion, strong electromagnetic interference and strong vibration, so ultrasonic thermometry technology is widely used in measuring temperature field in industrial boiler combustion, Marine hydrothermal, warehouse storage, as well as plasma chamber, nuclear reactor, turbine inlet air, inert gas, temperature standard and other areas.Using the characteristic of ultrasonic flight velocity in the medium will change as the medium temperature changing, ultrasonic thermometry technology can obtain the medium temperature indirectly through measuring ultrasonic time-of-flight in the medium under different temperatures. Therefore, accurate measurement of ultrasonic time-of-flight is a key factor to the accuracy of ultrasonic thermometry, because ultrasonic time-of-flight is difficult to determine, this paper proposes a method of measuring ultrasonic time-of-flight based on the Particle Swarm Optimization algorithm. First, give the transmitting transducer a group of dual excitation transmit signals, then use the Hilbert transform method to calculate the envelope of the two received echo signals respectively, use mixed exponential model to fit the rising edge of echo envelope, after the optimization object function of least square method is designed, finally use the Particle Swarm Optimization algorithm to estimate parameters, find the split point of the two rising edge of echo envelope, thereby obtain the ultrasonic time-of-flight, and then the temperature value on the flight path will be obtained. This paper describes the design and build of the hardware and software of the ultrasonic thermometry system in detail, and a series of experiments on a physical platform of three paths in the two-dimensional have been carried out to verify the method proposed in this paper, through counting and analyzing the experimental data and results, prove the measuring method proposed by this paper combined with the ultrasonic thermometry system designed by the paper is able to achieve high temperature measurement accuracy.