Personal monitor glass badge: theoretical dosemeter response calculated with the Monte Carlo transport code MCNPX

This paper describes the results of the simulation of a radiophotoluminescent (RPL) dosemeter with the Monte Carlo transport code MCNPX. The aim of this study is to calculate the response with MCNPX of the RPL dosemeter in terms of equivalent doses H(p) (0.07) and H(p)(10) using X-ray photon radiation qualities N series, together with S-Cs and S-Co nuclide radiation qualities, specified in ISO 4037-1. After comparison with reference values versus experimental results, the deviation of the theoretical responses of the RPL dosemeter proved to be lower than 5 % for reference values and lower than 10 % for experimental results. This good correlation validates the model over the energy range studied.     

Modeling of the solid–liquid bubble interface in partial nucleate boiling

Several models of heat transfer in partial nucleate boiling are identified in order to determine the relationship between the dominant physical parameters. The correlations are different for different models, so the main goal of this analysis is to determine the validity of each model and to identify the most dominant physical phenomenon in the nucleate boiling heat transfer. This is done by comparing the results of different models with a vast range of reliable experimental data. The comparison shows that the Sakashita and Kumada model gives the best results in the nucleate boiling heat transfer. It is also shown that the most dominating phenomenon in isolated partial bubbles zones is the transient conduction taking place mainly under the bubbles. This is in contradiction with a majority of the models that consider convection as the most important mode in the nucleate boiling heat transfer. The selected model can also be extrapolated and used in the case of fully developed bubbles zones.     

Computation of the relaxation and creep functions of elastomers from harmonic shear modulus

The purpose of this paper is to compute the relaxation and creep functions from the data of shear complex modulus, G ^∗(iν). The experimental data are available in the frequency window ν∈[ν_min,ν_max] in terms of the storage G′(ν) and loss G″(ν) moduli. The loss factor h( n) = \fracG"( n)G￠(n)\eta( \nu) = \frac{G'( \nu )}{G'(\nu )} is asymmetrical function. Therefore, a five-parameter fractional derivative model is used to predict the complex shear modulus, G ^∗(iν). The corresponding relaxation spectrum is evaluated numerically because the analytical solution does not exist. Thereby, the fractional model is approximated by a generalized Maxwell model and its rheological parameters (G _k ,τ _k ,N) are determined leading to the discrete relaxation spectrum G(t) valid in time interval corresponding to the frequency window of the input experimental data. Based on the deterministic approach, the creep compliance J(t) is computed on inversing the relaxation function G(t).     

Temperature field,H2 and H2O mass transfer in SOFC single cell: Electrode and electrolyte thickness effects

The temperature increment in electrodes and electrolyte of a fuel cell is mainly attributed to the chemical reaction and the irreversibilities. The aim of this work is to study the increasing temperature of a SOFC single cell under the influence of the electrode and electrolyte thicknesses for its type of heat source. The hydrogen and water field are also discussed according to anode thickness.     

HOS-based image sequence noise removal.

In this paper, a new spatiotemporal filtering scheme is described for noise reduction in video sequences. For this purpose, the scheme processes each group of three consecutive sequence frames in two steps: 1) estimate motion between frames and 2) use motion vectors to get the final denoised current frame. A family of adaptive spatiotemporal L-filters is applied. A recursive implementation of these filters is used and compared with its nonrecursive counterpart. The motion trajectories are obtained recursively by a region-recursive estimation method. Both motion parameters and filter weights are computed by minimizing the kurtosis of error instead of mean squared error. Using the kurtosis in the algorithms adaptation is appropriate in the presence of mixed and impulsive noises. The filter performance is evaluated by considering different types of video sequences. Simulations show marked improvement in visual quality and SNRI measures cost as well as compared to those reported in literature.     

One dimensional transient numerical study of the mass heat and charge transfer in a proton exchange membrane for PEMFC

The objective of our study is to quantify the mass water transferred by various modes: diffusion, convection and migration. For the water transfer, the principal forces considered in the model are, the convection force, the osmotic force (i.e. diffusion) and the electric force (migration). The first of these forces results from a pressure gradient, the second of a concentration gradient and the third of a protons' migration from the anode to the cathode, which has an effect on the dipole of the water molecules (resistance force to the advancement). The numerical tool used to solve the equations' system is the finite element method. The results obtained numerically considering this method are concentration profiles and concentration variation with time and membrane thickness. These results illustrate the contribution of each mass transfer mode.     

Prediction of reliability analysis of composite tubular structure under hygro-thermo-mechanical loading

The present paper focuses on reliability prediction of composite structure under hygro-thermo-mechanical loading, conditioned by Tsai-Wu failure criterion, where the Monte–Carlo method is used to estimate the failure probability(Pf). This model was developed in two steps: first, the development of a deterministic model, based on an analytical and numerical approach, and then, a probabilistic computation. Using the hoop stress for each ply, a sensitivity analysis was performed for random design variables, such as materials properties, geometry, manufacturing, and loading, on composite cylindrical structure reliability. The probabilistic results show the very high increase of failure probability when all parameters are considered.     

Study of the effect of gamma irradiation on the structure and properties of metallocene linear low density polyethylene containing hindered amines

The changes in the carbonyl index, the melt flow rate, the crystalline content and the ultimate tensile properties of metallocene linear low density polyethylene (mLLDPE) films subjected to gamma irradiation from 10 to 800 kGy, were investigated with and without hindered amine stabilizer (HAS). For comparative purposes, unstabilized and HAS stabilized low density polyethylene (LDPE) were also studied. The results indicated that under gamma irradiation, the HAS stabilizer did not have any influence on the oxidative stability of mLLDPE films as compared with unstabilized ones due probably to complexation reactions between the nitroxyl radicals of the stabilizer and the metallocene catalysts leading to inert species. Moreover, higher increases in melt flow index and crystalline content with a fast drop in ultimate tensile properties were observed for higher doses indicating the occurrence of chain scission. It was also found that the metallocene LLDPE structure had no significant effect on the radiation induced oxidative degradation kinetics when compared to LDPE. Whereas, the addition of HAS to LDPE significantly lowered the formation rates of carbonyls and subsequently improved the durability of the material by doubling the half-value-dose.