atom transfer radical polymerization (atrp) of styrene was carried out at 105°c and a monte carlo simulation was employed to model the system. the variations of monomer conversion, the initiator concentration, average molecular weight, and molecular weight distribution were evaluated as the reaction proceeded. according to the results obtained, for similar reaction time, monomer conversion is h...

background: the presence of a wedge filter in the beam trajectory can modify the beam quality and cause some changes in the dosimetry parameters which are usually difficult to be measured directly and accurately. material and methods: in this study the mcnp-4c monte carlo code was used to simulate the 9 mv photon beam generated by a linear accelerator. upon getting a good agreement between the ...

exposure buildup factors have been calculated by monte carlo method for point isotropic gamma ray sources, penetrating a two-layer spherical shield of water surrounded by lead, and the effect of bremsstrahlung radiation on buildup factors has, in particular, been investigated, the results of which are in good agreement with previous works. the buildup factors were then calculated for various co...

serum albumin is the most aboundant protein in blood plasma. its two major roles aremaintaining osmotic pressure and depositing and transporting compounds. in this paper,albumin-methanol solution simulation is carried out by three techniques including montecarlo (mc), molecular dynamic (md) and langevin dynamic (ld) simulations. byinvestigating energy changes by time and temperature (between 27...

introduction: scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. accurate estimation of scatter in projection data of spect is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. methods: the objective of this paper is to develop and validate a scatter correction technique t...

Monte Carlo simulation methods apply a random sampling and modifications can be made of this method is by using variance reduction techniques (VRT). VRT objective is to reduce the variance due to Monte Carlo methods become more accurate with a variance approaching zero and the number of samples approaches infinity, which is not practical in the real situation (Chen, 2004). These techniques are ...

Light reflectance by semi-infinite turbid media is modeled by a hybrid of Monte Carlo simulation and diffusion theory, which combines the accuracy of Monte Carlo simulation near the source and the speed of diffusion theory distant from the source. For example, when the turbid medium has the following optical properties--absorption coefficient 1 cm-1, scattering coefficient 100 cm-1, anisotropy ...

in this paper, drift change point estimation in the mean of polynomial profiles is considered. for this purpose, the proposed change point estimator is computed using maximum likelihood approach. performance of the proposed estimator is evaluated using monte carlo simulations when t2 control chart issues an out-of-control signal. simulation results show that the performance of the proposed esti...