5,550 research outputs found

    Monte Carlo Simulation of Sinusoidally Modulated Superlattice Growth

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    The fabrication of ZnSe/ZnTe superlattices grown by the process of rotating the substrate in the presence of an inhomogeneous flux distribution instead of successively closing and opening of source shutters is studied via Monte Carlo simulations. It is found that the concentration of each compound is sinusoidally modulated along the growth direction, caused by the uneven arrival of Se and Te atoms at a given point of the sample, and by the variation of the Te/Se ratio at that point due to the rotation of the substrate. In this way we obtain a ZnSe1−x_{1-x}Tex_x alloy in which the composition xx varies sinusoidally along the growth direction. The period of the modulation is directly controlled by the rate of the substrate rotation. The amplitude of the compositional modulation is monotonous for small angular velocities of the substrate rotation, but is itself modulated for large angular velocities. The average amplitude of the modulation pattern decreases as the angular velocity of substrate rotation increases and the measurement position approaches the center of rotation. The simulation results are in good agreement with previously published experimental measurements on superlattices fabricated in this manner

    Estimation of Effective Plant Area Index for South Korean Forests Using LiDAR System

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    Light Detection and Ranging (LiDAR) systems can be used to estimate both vertical and horizontal forest structure. Woody components, the leaves of trees and the understory can be described with high precision, using geo-registered 3D-points. Based on this concept, the Effective Plant Area Indices (PAIe) for areas of Korean Pine (Pinus koraiensis), Japanese Larch (Larix leptolepis) and Oak (Quercus spp.) were estimated by calculating the ratio of intercepted and incident LIDAR laser rays for the canopies of the three forest types. Initially, the canopy gap fraction (GLiDAR) was generated by extracting the LiDAR data reflected from the canopy surface, or inner canopy area, using k-means statistics. The LiDAR-derived PAIe was then estimated by using GLIDAR with the Beer-Lambert law. A comparison of the LiDAR-derived and field-derived PAIe revealed the coefficients of determination for Korean Pine, Japanese Larch and Oak to be 0.82, 0.64 and 0.59, respectively. These differences between field-based and LIDAR-based PAIe for the different forest types were attributed to the amount of leaves and branches in the forest stands. The absence of leaves, in the case of both Larch and Oak, meant that the LiDAR pulses were only reflected from branches. The probability that the LiDAR pulses are reflected from bare branches is low as compared to the reflection from branches with a high leaf density. This is because the size of the branch is smaller than the resolution across and along the 1 meter LIDAR laser track. Therefore, a better predictive accuracy would be expected for the model if the study would be repeated in late spring when the shoots and leaves of the deciduous trees begin to appear

    Properties of Milk Supplemented with Peanut Sprout Extract Microcapsules during Storage

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    This study was carried out to investigate the physicochemical and sensory properties of milk with added powdered peanut sprout extract microcapsules (PPSEM) during the storage at 4°C for 16 d. The size of PPSEM varies from 3 to 10 μm as observed by the scanning electron microscopy (SEM). The pH values of all samples ranged from 6.8 to 6.6 during the storage. Release of resveratrol for 0.5 and 1% PPSEM addition was about 0.89 μl/ml and TBARS value found to lower during storage of 16 d. The a* and b* color values of high concentrations (1.5, 2.0, 2.5 and 3.0%) of PPSEM-added milk samples were significantly increased during the storage (p<0.05). The sensory test revealed that the overall acceptability of PPSEM (0.5 and 1%) added milk sample were quite similar to that of control. Based on the data, it was concluded that the low concentrations of the microcapsules (0.5 and 1.0%, w/v) could be suitable to produce the microcapsule-supplemented milk without significant adverse effects on the physicochemical and sensory properties of milk

    Elastic pp Scattering at LHC Energies

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    We consider the first LHC data for elastic pp scattering in the framework of Regge theory with multiple Pomeron exchanges. The simplest eikonal approach allows one to describe differential elastic cross sections at LHC, as well as pp and pˉp\bar{p}p scattering at lower collider energies, on a reasonable level.Comment: 11 pages, 5 figures, and 1 tabl
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