Bayesian experiment planning applied to numerical dosimetry

To protect people from electromagnetic field, Basic Restrictions (BR) are defined [1]. These BR fix a limit to be not exceeded. The metric associated with these BR is the Specific Absorption Rate (SAR). Reference Levels (RL) are also defined since the BR are difficult to check in situ. These RL set the maximum allowed electromagnetic field. The compliance to RL guaranties the compliance to BR. To evaluate the SAR in the human body, some anatomical models (phantoms) and numerical methods are used (e.g. Finite Difference in Time Domain). Based on this, studies show that for some configurations the Whole Body SAR (WBSAR) is close to BR. Other studies stressed the variability of the WBSAR due to the variability of human morphology [2]. Despite the computing resources development, the number of the phantoms is very limited. This limited number of phantoms does not allow using usual method such as Monte Carlo to assess the maximal threshold of the WBSAR for a given population. Hence the construction of a model of the WBSAR as a function of morphology is required. Nevertheless, the WBSAR is impacted by the external morphology (height and weight) and the internal morphology (proportion of fat, proportion of muscles...). But there is no statistical data concerning the internal ones. In this paper, the external morphology is focused and the internal morphology is released by considering homogeneous phantoms. A Bayesian sequential experiment planning is proposed. This method consists in refining the region of interest of the WBSAR statistical distribution for a given population. This region of interest is the threshold of the WBSAR at 95% (WBSAR95). This study is conducted in the case of a plane wave vertically polarized and frontally oriented on phantoms. The incident power is equal to 1W/m². The frequency is fixed at 2.1GHz

Plan d'expériences séquentiel appliqué à la dosimétrie numérique

Dans ce papier nous allons proposer une méthodologie consistant à trouver la valeur du Débit d'Absorption Spécifique du Corps Entier (DAS_CE) qui couvre 95% d'une population donnée. Cette méthode repose d'une part sur de l'Inférence Bayesienne et d'autre part sur un modèle paramétrique de prédiction du DAS_CE en fonction de la morphologie ainsi que des outils de simulations numériques

Statistical Analysis of the Whole Body Absorption Depending on Anatomical Human Characteristics at the Frequency of 2.1 GHz

International audienceIn this paper we propose an identification of morphological factors that may impact the Whole Body Specific Absorption Rate (WBSAR). The study is conducted for the case of an exposure to a front plane wave at the 2100MHz frequency carrier. This study is based on the development of different regression models for estimating the WBSAR as a function of morphological factors morphology. For this manner, a database of twelve anatomical human models (phantoms) has been considered. Also, eighteen supplementary phantoms obtained using morphing technique were generated to build the requested relation. The paper presents three models based on external morphological factors like the Body Surface Area (BSA), the Body Mass Index (BMI) or the body mass. These models show good results for families obtained by morphing technique on the estimation of the WBSAR (< 10%) but still less accurate (30%) when applied for different original phantoms. This study stresses the importance of the internal morphological factors such as muscle and fat proportions in the characterization of the WBSAR. The regression models are then improved using internal morphological factors with an estimation error around 10% on the WBSAR. Finally, this study is suited for establishing the statistical distribution of the WBSAR for a given population characterized by its morphology

Multidimensional collocation stochastic method to evaluate the Whole Specific Absorption Rate for a given population

To protect people from Electromagnetic Fields (EMF), ICNIRP has defined limits [1]. The Basic Restrictions (BR) set the maximum values of Specific Absorption Rate (SAR). Since BR are complex to assess ICNIRP has also derived the reference levels (RL) from BR. These RL were established to guaranty the compliance to BR. Several studies with human model (phantoms) show that even below the RL, the WBSAR (Whole Body averaged SAR) may exceed the BR due to the variability of human morphology [2]. The number of phantoms is very limited. Hence, t e characterization of the WBSAR for a given using usual methods such as Monte Carlo is not possible. To bridge this lack of phantoms a model for the WBSAR as a function of morphology is suitable. However, this model requires knowledge on internal morphology (proportion of fat, muscle...) and external ones (mainly height and weight) [5]. Due to the absence of statistical data concerning the internal morphology, the statistical distribution of the WBSAR is difficult to obtain. In this paper, the internal morphology is released by considering one equivalent tissue for the whole body. The stochastic collocation is used to characterize the distribution of the WBSAR for a given population. The study is conducted in the case of a plane wave operating at 2.1 GHz, vertically polarized and frontally oriented on phantoms. The incident power is equal to 1W/m²

Optimizing Solar Energy Production in Partially Shaded PV Systems with PSO-INC Hybrid Control

Partial shading, from obstacles such as buildings or trees, is a major challenge for photovoltaic systems, causing unpredictable fluctuations in solar energy production and underlining the need for advanced energy management strategies. In this paper, we propose an innovative approach that combines hybrid metaheuristic optimization with maximum power point tracking control (MPPT), using particle swarm optimization (PSO) in conjunction with the incremental conductance (IC) algorithm. We compare the proposed method with the conventional Perturb and Observation (PO) algorithm. The choice of PO as a comparison method is due to its simplicity, its familiarity with the scientific literature, its low cost of implementation. The main objective of swarm optimization combined with the IC algorithm lies in its ability to overcome the challenges posed by partial shading, ensuring accurate and efficient tracking of the point of maximum power, thanks to dynamic adaptation to variations in solar irradiation, thus enhancing the performance and resilience of the photovoltaic system. This approach  is of crucial importance, offering considerable potential for solving the complex challenges associated with partial shading. Our results show that this hybrid MPPT algorithm offers superior tracking efficiency 98% , faster convergence 500ms , better stability and increased robustness compared to traditional MPPT approaches. The system is composed of a PV and a boost converter that connects the input to the resistive load. The algorithms were implemented with MATLAB/Simulink as the simulation tool. These results not only reinforce the viability of sustainable energy solutions, but also open the way for the development of more sustainable energy solutions.The perspectives of this work are oriented towards a practical and extended integration of the proposed hybrid approach in real photovoltaic systems, with a particular emphasis on experimental validation

A comparative study between the effect of 17-β estradiol and antioxidants combination on some menopausal changes in oophorectomised rats

Background: As oxidative stress is proposed to be responsible for many of the menopause associated disorders, antioxidants may play an important role in this situation. The aim of this work was to compare between the effects of oestrogen replacement therapy and antioxidant supplements of vitamin C and low dose of vitamin A on some menopause associated changes in oophorectomised rats. Materials and methods: Forty albino female rats were divided into 4 groups: normal control group, oophorectomised group, oophorectomised group treated with 17-β estradiol (oophorectomised + E2) and oophorectomised group treated with vitamins (oophorectomised + vit).The following were measured: total antioxidant (TAO) and malondialdehyde (MDA), lipid profile, serum insulin, glucose and homeostasis model assessment-insulin resistance (HOMA-IR), bone specific alkaline phosphatase (BALP), urinary hydroxyproline, weight gain and visceral fat. Results: A positive correlation was found between MDA and low density lipoprotein-cholesterol (LDL) (r = 0.694 and P = 0.000), HOMA-IR (r = 0.691 and P = 0.000.) and BALP (r = 0.563 and P = 0.000) and urinary hydroxyproline level (r = 0.761 and P = 0.000). Those results denoted that OS might be a cause of dyslipidemia, insulin resistance and osteoporosis associated with menopause. Both E2 and vitamins in oophorectomised rats led to a significant decrease in MDA (F = 33.402, P = 0.000), weight gain, visceral fat (F = 7.589, p = 0.000 and F = 3.748, P = .019, respectively), cholesterol (F = 40.748, P = 0.0001), LDL cholesterol (F = 55.168, P = 0.0001), and significant increase in HDL (F = 18.393, P = 0.0001) and TAO levels (F = 14.781, P = 0.000) compared to oophorectomised rats. Also, both treatments led to a significant decrease of HOMA-IR (F = 18.933, P = 0.000, respectively), BALP (F = 13.202, P = 0.000) and urinary hydroxylproline (F = 220.012, P = 0.000). An interesting finding was detected where oophorectomised rats showed a decrease in triglyceride level which was significantly increased by E2 administration whereas antioxidant administration produced no change (F = 34.267, P = 0.0001). Conclusion: Our results denote similar effects of both E2 and antioxidant’ supplements (vitamin C and low dose vitamin A) administration in surgically induced menopause in rats regarding oxidative stress, weight gain, atherogenic lipid profile changes, insulin sensitivity and bone turnover. However differences between preclinical and clinical studies must be taken into consideration especially when moving from animal studies to clinical trials