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Item type:Publication, Theoretical and experimental study of the LR-115 detector response in a non-commercial radon monitor(Elsevier, 2020-06-01)B.trαcks, a simulation program for SSNTD's sensitivity, has been developed to study the response of LR-115 (cellulose nitrate) and CR-39 (poly allyl glycol carbonate) nuclear track detectors. Detectors are located inside detector holders and are used for radon measurements. The program incorporates a variety of special features gathered together to achieve good agreement between theoretical approach and experimental results. The input parameters to study the detector response are radon exposure, geometry and dimensions of a detector holder (it can be cylindrical, conical or semi-spherical), entrance type for radon gas, detector type, and V function (four different functions were selected from literature). The output results are detector response and radon progeny distribution onto internal chamber walls. In this article, the response of the LR-115, which is placed inside a non-commercial-conductive radon monitor based on diffusion chambers called G2, was theoretically and experimentally studied. The common Monte Carlo simulation procedure and an alternative approach that replicates how monitors are exposed to different radon exposures were used as theoretical approaches. Experimental methodology was conducted in a radon test chamber from Italy (MI.AM s.r.l.). Comparison results of both theoretical and experimental methodology are presented and discussed. One of the major results, among others, shows that the monitor material (conductive or non-conductive) does not influence the LR-115 response. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Robust beta regression modeling with errors-in-variables: a Bayesian approach and numerical applications(Springer Science+Business Media, 2021-09-14)Beta regression models have become a popular tool for describing and predicting limited-range continuous data such as rates and proportions. However, these models can be severely affected by outlying observations that the beta distribution does not handle well. A robust alternative to the modeling with the beta distribution is considering the rectangular beta (RB) distribution, which is an extension of the former one. The RB distribution can deal with heavy tails and is therefore more flexible than the beta distribution. Regression modeling where covariates are measured with error is a frequent issue in different areas. This paper derives robust regression modeling for proportions with errors-in-variables using the RB distribution under a new parametrization recently proposed in the literature. We use a Bayesian approach to estimate the model parameters with a specification of prior distributions and a computational implementation carried out via the Gibbs sampling. Monte Carlo simulations allow us to conduct numerical evaluation to detect the statistical performance of the approach considered. Then, an illustration with real-world data is presented to show its potential uses. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Surface-Bulk 2D Spin-Crossover Nanoparticles within Ising-Like Model Solved by Using Entropic Sampling Technique(MDPI, 2023-03-01)We model the thermal effects in different 2D spin-crossover (SCO) square lattices within the frame of the Ising-like model using Monte Carlo entropic sampling (MCES) method to enhance the scan of macrostates beyond the most probable thermal ones. In fact, MCES allows access to the metastable states, and it is then well adapted to study thermal hysteresis properties. In this contribution, we distinguish, for the first time, the interaction between molecules located in bulk at the surface and those connecting the bulk and surface regions of an SCO lattice. In addition, an extra ligand field contribution is assigned to surface molecules through an interaction parameter (Formula presented.). In the absence of environmental effects on surface nanoparticles, a single thermal hysteresis loop increasing with the lattice size is simulated with a unique bulk and surface equilibrium temperature (Formula presented.). When environmental effects are accounted for, a two-step behavior associated with two hysteresis loops of widths ΔTS (for the surface) and ΔTB (for the bulk) with an intermediate plateau 14 K wide is obtained in the thermal dependence of the high-spin (HS) fraction for the 6 × 6 lattice. The surface and bulk equilibrium temperatures are then different, both decreasing towards lower values, and the (Formula presented.) parameter controls the three states’ behavior as well as the hysteresis loop interval. Size effects show that the equilibrium temperature is governed by the surface atoms for a small lattice size (5 × 5) and by the bulk atoms for a large lattice size (7 × 7). Moreover, a change in the size of the lattice results in a variation of the order–disorder (or Curie) temperature, TO.D., and the surface equilibrium temperature, Teq, while only TO.D. changes in bulk. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A Comparative Study Between Monte Carlo Entropic Sampling Method and Local Mean Field Investigations of Thermal Properties of Spin-Crossover Nanoparticles Based on Ising-Like Model(OAE Publishing Inc., 2023-12-01)The thermally induced transitions between low-spin (LS) and high-spin (HS) configurations of spin-crossover (SCO) nanoparticles are simulated, focusing on the effects of localized surface and bulk interactions on the average magne-tization of 2D square lattices. The thermal behaviors and hysteresis cycles are investigated within the framework of the Ising model Hamiltonian and are conducted following two approaches: local mean field approximation (LMFA) and Monte Carlo entropic sampling (MCES) techniques. The results obtained by these two methods are compared for the two square lattice sizes, 6 × 6 and 7 × 7. Thus, when the bulk-surface interaction term is set to zero, the two approaches lead to identical values of the surface and bulk transition temperatures separated by a long intermediate plateau in both cases. Although hysteresis curves exhibit a similar shape, LMFA shows slightly larger widths ΔT than MCES. On increasing bulk-surface interaction term, the two methods lead to different shifts in equilibrium temperature values for both bulk and surface components, respectively, to lower and higher values by MCES. In general, it is found that LMFA shifts surface equilibrium temperature differently to lower values and enhances the hysteresis effect, particularly for surface molecules. On the other hand, for the 7 × 7 square lattice, the equilibrium temperatures are slightly higher by 1.5% and 3.2% for bulk and surface molecules, respectively, with a narrower hysteresis width in the surface. Moreover, with the MCES method, an abrupt transition instead of a hysteresis transition is calculated for surface molecules (Formula Presented). - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Simulation of diffusion and decay of radon/thoron exhaled from a wall and its newly created progeny. Response of a bare LR-115 detector placed on the wall(Elsevier BV, 2025-06-01)Monte Carlo techniques were used to simulate the air diffusion of exhaled radon/thoron atoms from a wall, the formation and decay of different radioactive species during transport, and the response of a bare LR-115 detector placed on the exhaling surface. The spatial distributions of radionuclide decays and the detector's partial sensitivities to radon/thoron and their progeny were determined. The simulation results were numerically validated through comparisons with published theoretical and experimental data. From the simulated experiments, the contributions of different species to the total track density and what the detector might measure in the studied configuration and assumed parameters were inferred. It was shown that near the wall, where the effective volumes of all species are located, the number of radon atoms was approximately constant, while that of thoron decreased to about 30% relative to the number of exhaled atoms, and the equilibrium factors of both gases were very low. A negligible contribution of 220Rn and 216Po to the track density is expected if the distance between detector's edges and support exceeds 5–6 times the thoron characteristic diffusion length. For similar detector and support sizes, these atoms can significantly contribute to the track density if thoron exhalation rate from wall is high. The advantages and limitations of the detector exposure method for estimating indoor radon concentrations are analyzed. Finally, a simple method is suggested for more accurate radon measurements using the bare LR-115 detector placed on a wall.1