Development of Age-Estimation System Using Thermoluminescence

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Thermoluminescence (TL) is a calorescence phenomenon observed while heating minerals. TL from the natural mineral is particularly useful as a method of age determination in the archaeological and geological fields. Since the TL quantity depends on the heating rate of the specimens, constant raising of the temperature for the control system is necessary. In actual measurement it is important to obtain a stable measurement value in temperature range 150-400ﾟC.However, even the commercial apparatus for TL measurement usually fails this requirement.This paper progress a new TL age-estimating method. To establish for this, three temperature control methods are designed and a measurement system for TL intensity is developed. Firstly, the H infinity control scheme is introduced to archive the improvement of tracking characteristics of low-frequency domain and robust stability in the high-frequency domain. Secondly, model predictive control scheme has proposed. This method avoid the linearization of a non-linear system and provides and provides robustness against non-linear input. Finally, the optimal digital feedback control algorithm based on impulse response of the system is applied to this control system. These control schemes show that the system can precisely control the constant raising temperature within permissive error of 1 degree for the temperature range 100-400ﾟC.The age is estimated by calculating the proportion of the annual cumulative dose at sampling area to the sum of natural cumulative dose that obtained TL by integrated intensity measured at a constant rising temperature. The measured age estimation data is reasonable comparing with currently in use.