Three-dimensional Temperature Distribution Estimation around a Heat Source in Water Using Asymmetric Inverse Abel Transformation

摘要

We propose a new method for measuring three-dimensional (3D) estimation distribution in water around a heat source.By using near infrared (NIR) light, it is possible to measure the total amount of temperature on the optical path. The totalamount of temperature obtained is converted into local temperature distribution based on certain assumption. Theconventional method estimates temperature distribution using symmetric inverse Abel transformation based on thestrong constraint that heat propagates axially symmetrically from the axis passing through the center of the heat sourceupward. There are two points to be improved in the conventional method. The first point to be improved is that thetemperature is assumed to be distributed circularly symmetrically from the axis passing through the heat source center. Infact, in many cases, heat propagates asymmetrically. In this case, the conventional method cannot obtain accurate results.In this paper, we use asymmetric inverse Abel transformation instead symmetric inverse Abel transformation in order toperform asymmetric estimation. The second point to be improved is that the conventional method does not take intoconsideration that heat propagates smoothly. In this paper, we use an optimization algorithm to smooth adjacent surfacesof the temperature distribution. Experiment showed that the proposed method estimated temperature distribution moreaccurately than the conventional method.