Estimation of overall heat transfer coefficient of cooling system in RF capacitive hyperthermia
The 
study presented in this article involves the estimation of the overall heat 
transfer coefficient of cooling system in RF capacitive hyperthermia 
treatment using inverse problem based on the conjugate gradient method to 
provide improved distribution of temperature. The temperature data computed 
numerically from the direct problem using the finite difference time domain 
method are used to simulate the temperature measurements. The effects of the 
errors and sensor positions upon the precision of the estimated results are 
also considered. The results show that a reasonable estimation of the unknown 
can be obtained. Finally, measurements in a tissue-equivalent phantom are 
employed to appraise the reliability of the presented method. The comparison of 
computed data with measurements shows a good agreement between numerical 
and experimental results.
An inverse heat conduction problem with heat flux measurements
Using heat flux measurements as additional information to solve inverse heat conduction problems was and is still rarely employed. Lot of disadvantages linked to heat flux measurement specificities (local disturbance, intrusive measurement, lack of knowledge and proficiency, etc.) make people prefer temperature measurements which are well documented and very widespread. Solving inverse heat conduction problems with heat flux measurements is quite different than the one which uses temperatures and need to be investigated deeply. In this work, this problem is approached through the solution of a bioengineering problem consisting in the development of a non‐invasive blood perfusion probe. The effort here is focused on the development of a methodology for the estimation of time‐dependent blood perfusion from heat flux measurements. The physical probe incorporates a thin heat flux sensor, which is placed in contact with the tissue region where the perfusion is to be measured. The sensor records the heat flux due to an imposed thermal event, which is achieved by air flow. A one‐dimensional mathematical model is used to simulate the thermal event occurring at the contact region holding between the probe and the tissue. A combined parameter and function estimation procedure is developed to estimate simultaneously time‐dependent blood perfusion and thermal contact conductance between the probe and the tissue. The robustness of the method was demonstrated through several test cases using simulated data. The presented examples include various functional changes in the time evolution of blood perfusion. Results from this study have shown the feasibility of solving inverse problems with heat flux measurements and the two unknowns are estimated with no a priori information about their functional forms. Copyright © 2006 John Wiley & Sons, Ltd.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.