The aims of this work were to measure the entrance and exit dose for patient treated for head and neck tumors. The target absorbed dose was determined from the exit and entrance dose measurement. Twenty patients were evaluated. The results were compared to the calculated values and the midline dose was determinate and compared with the prescribed dose. 80 entrance doses and 80 exit doses measurements were performed. The average difference from expected values was 1.93% for entrance dose (SD 1.92%) and –0.34% for exit dose (SD 4.1%). The target absorbed dose differed from prescribed dose values by 2.94% (1.97%) for the results using the Noël method and 3.34% (SD: 2.29%) with the Rizzotti method. The total uncertainty budget in the measurement of the absorbed entrance and exit dose with diode, including diode reading, correction factors and diode calibration coefficient, is determined as 3.02% (1 s). Simple in vivo dose measurements are an additional safeguard against major setup errors and calculation or transcription errors that were missed during pre-treatment chart check.

A micro-scale model of a solid oxide fuel cell (SOFC) involving the mass transfer together with the electrochemical reaction, the electron and ion transports through the respective spherically shaped electron- and ion-conducting particles inside the electrodes was mathematically developed. Couples of useful dimensionless parameters were introduced in order to represent the characteristics of the cell. The predicted cell performance was showed according to various operating and design conditions. The effects of micro-scale electrode geometry on the cell performance were also taken into account. Parametric study according to the volumetric fraction of ionic and electronic conducting particles was conducted in order to examine the effects of operating conditions on the cell overpotentials. The study results substantiate the fact that SOFC overpotential could be effectively decreased by increasing the operating temperature as well as operating pressure. This present study reveals the working mechanisms of SOFC at the microscale level, while demonstrating the use of micro-scale relations to enhance the SOFC performance. The accuracy of the presented model was validated by comparing to already existing experimental results from the available literatures.

Within the framework of the dielectric-continuum model, the equations of motion for p-polarization field in wurtzite quantum well are solved for the propagating optical phonon modes. The polarization eigenvector and the dispersion relation are derived by using the determinate method. The dispersion relation and phonon modes properties of the propagating optical phonons are investigated for GaN/AlN single QW. The numerical results show that the propagating phonons have a quantization character by a quantum number n that define its order. The propagating optical phonons are more dispersive for decreasing n, and the bands formed by the dispersion curves are narrower for higher order modes. The wave vector and width of quantum well have more important effect on phonon energy, with the increase of wave vector or width of quantum well, the energy of propagating optical phonon modes decrease in TO domain (between A1 (TO) and E1 (TO) frequency of GaN), and increase in LO domain (between GaN A1 (LO) and E1 (LO) frequency of GaN). The strain effects of QW structures have clear influence on the dispersion behavior of propagating optical phonons. The frequency of the propagating optical phonon modes is increased due to the strains of the QW structure.

The contact angle (Θ) of molten Sn and Sn-Ag alloys (0.5, 1.5, 3.5, 6 wt.% Ag) on Cu substrates have been studied by using sessile drop method at various temperatures (230, 250, 275 and 300 °C). Experimental results showed that additions of Ag to Sn resulted in a continuous decrease in the Θ up to 3.5 wt.% above which the Θ value was increased. Increasing alloy temperature also decreased the Θ proportionally. Experimental results revealed that a correlation between the Θ, alloy composition and the alloy temperature exists which yielded an empirical model to predict the Θ at a given Ag content and temperature for a given Sn-Ag alloy. The empirical model predicts the Θ reasonably well with the present work and the other published works.

PEM fuel cell performance and lifetime strongly depend on the polymer membrane and MEA hydration. As the internal moisture is very sensitive to the operating conditions (temperature, stoichiometry, load current, water management…), keeping the optimal working point is complex and requires real-time monitoring. This article focuses on PEM fuel cell stack health diagnosis and more precisely on stack fault detection monitoring. This paper intends to define new, simple and effective methods to get relevant information on usual faults or malfunctions occurring in the fuel cell stack. For this purpose, the authors present a fault detection method using simple and non-intrusive on-line technique based on the space signature of the cell voltages. The authors have the objective to minimize the number of embedded sensors and instrumentation in order to get a precise, reliable and economic solution in a mass market application. A very low number of sensors are indeed needed for this monitoring and the associated algorithm can be implemented on-line. This technique is validated on a 20-cell PEMFC stack. It demonstrates that the developed method is particularly efficient in flooding case. As a matter of fact, it uses directly the stack as a sensor which enables to get a quick feedback on its state of health.