共查询到20条相似文献,搜索用时 0 毫秒
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Kil-Oung Choi Young-Seok Lee Sun-Tae Hwang Kwang-Pil Lee Keung-Shik Park 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(3):605-608
The manganese sulphate bath method is widely used for measurements of neutron source strength. In this study, the analytical
chemistry method based on the Inductively Coupled Plasma (ICP) spectrometry was used for examining the impurity contents of
MnSO4·H2O, to induce55Mn(n,γ)56Mn reactions. From the analytical results, mainly K, Co, and Zn as well as trace amounts of Cd, Li, etc., have turned out
to be the relevant impurities absorbing the neutrons and the fraction of neutron absorbed by the total impurities was determined
to be 1.37%. 相似文献
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Ali A. Alghamdi 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):359-364
The use of neutron for Non Destructive Imaging (NDI) techniques has many advantages over other (NDI) methods. Using well-established
X-ray imaging techniques can provide easy and direct results with some limitations where the sensitivity for light elements
is very low. On the other hand, neutron is highly sensitive to water content and can provide extra qualitative information.
Comparing the results of the two imaging techniques are investigated in this work with the aim of identifying the palm weevil.
At larva stage of the weevil’s life it is characterized by highly water content in the trunk of the palm tree which itself
composed of spongy watery texture in some types of palm tree. MCNPX 2.5.0 code with neutron radiography tally was used to
obtain the 2D projection then reconstructed to 3D tomography image using OSCaR post processing package. The neutron and photon
mesh tallies is utilized to study the neutron and photon fluences from monoenergetic thermal neutron beam and neutron spectrum.
There are fundamental difficulties in neutron detection which result in misleading information arises from neutron scattering
when constructing cone beam CT neutron images, however, neutron radiography provide better methods for the weevil detection
from 2D projection. 相似文献
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《Journal of computational chemistry》2017,38(19):1727-1739
Cassandra is an open source atomistic Monte Carlo software package that is effective in simulating the thermodynamic properties of fluids and solids. The different features and algorithms used in Cassandra are described, along with implementation details and theoretical underpinnings to various methods used. Benchmark and example calculations are shown, and information on how users can obtain the package and contribute to it are provided. © 2017 Wiley Periodicals, Inc. 相似文献
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We present a new Monte Carlo simulation procedure which is capable of capturing aggregate structures in a suspension where fine particles are dispersed. The algorithm we call the “cluster-moving” Monte Carlo algorithm involves moving aggregates (clusters) as unitary particles at every certain Monte Carlo step. We discuss here the theoretical background of the cluster-moving Monte Carlo algorithm and the availability of the algorithm for simulations of systems where fine particles aggregate. The results of simulations for two model systems, magnetic fluids and colloidal dispersions, have shown that the new algorithm produces much more rapid convergence than the conventional one for unstable dispersion systems and reproduces physically reasonable aggregate structures of fine particles. 相似文献
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The present paper describes an approach based on Monte Carlo simulation for the evaluation of uncertainty of nuclear spent fuel analysis. The mathematical model of measurement was established by examining the dissolution process step by step. The results are consistent with those obtained by the classical propagation of variance approach. This paper shows the importance of taking the process into account in order to give a more reliable uncertainty assessment to the result of a concentration ratio of two isotopes in spent fuel. Indeed, for some radionuclides, the uncertainty associated with the upstream steps of the analysis (“process” uncertainty) can represent up to 95 % of the overall uncertainty. 相似文献
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M. J. Nemati M. Habibi R. Amrollahi 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):221-226
In this paper Monte Carlo simulations have been performed for the attenuation of neutrons radiation produced by a 4 kJ plasma focus device through labyrinth shielding design with various thicknesses. At the test site that will be fired with deuterium and deuterium fusion (D–D) resulting in a yield of about 109 fusion neutrons of 2.45 MeV. This poses a radiological hazard to scientists and personnel operating the device. The goal of this study is to evaluate various shielding options under consideration for the plasma focus operating with D–D fusion. Shields of varying neutrons-shielding effectiveness were investigated using concrete materials. The most effective shield between labyrinth structure allowed almost 9.52E+6 shots per year while keeping personnel under 20 mSv of dose. The most expensive shield that is used labyrinth shield with 75 cm concrete thickness on the walls allowed almost 9E+8 shot per year. 相似文献
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By use of an intramolecular criterion, i.e., the direct proportionality between mean square dimension and chain length, theta conditions for linear chains and ring shaped polymers are evaluated for several types of cubic lattice chains (simple cubic, body centered cubic, and face centered cubic). The properties of the rings are evaluated for the same thermodynamic conditions under which they are prepared thus allowing for a natural amount of knots which have been identified by use of Alexander polynomials. For the limit of infinite chain lengths the same theta parameter is found for linear chains and rings. On the contrary, a significant theta point depression occurs due to an additional excluded volume effect if unknots are exclusively regarded. Parameters characteristic of the shape of rings and chains under theta conditions extrapolated to infinite chain length fairly well coincide with respective data for random walks. Mean square dimensions (characteristic of the size) of theta systems are slightly in excess as compared to nonreversal random walks due to the necessity of avoiding overlaps on a local scale. Furthermore athermal systems are studied as well for comparison; mean square dimensions are described by use of scaling relations with proper short chain corrections, shape parameters are given in the limit of infinite chain length. 相似文献
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N. M. Spyrou J. B. Awotwi-Pratt A. M. Williams 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(2):287-291
An activation analysis facility based on an isotopic neutron source (185 GBq 241Am/Be) which can perform both prompt and cyclic activation analysis on bulk samples, has been used for more than 20 years
in many applications including 'in vivo' activation analysis and the determination of the composition of bio-environmental
samples, such as, landfill waste and coal. Although the comparator method is often employed, because of the variety in shape,
size and elemental composition of these bulk samples, it is often difficult and time consuming to construct appropriate comparator
samples for reference. One of the obvious problems is the distribution and energy of the neutron flux in these bulk and comparator
samples. In recent years, we have attempted to adopt the absolute method based on a monostandard and to make calculations
using a Monte Carlo code (MCNP4C2) to explore this further. In particular, a model of the irradiation facility has been made
using the MCNP4C2 code in order to investigate the factors contributing to the quantitative determination of the elemental
concentrations through prompt gamma neutron activation analysis (PGNAA) and most importantly, to estimate how the neutron
energy spectrum and neutron dose vary with penetration depth into the sample. This simulation is compared against the scattered
and transmitted neutron energy spectra that are experimentally and empirically determined using a portable neutron spectrometry
system.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Yoon Seonkwang Seo Hee Kim Young-Su Lee Chaehun Kim Ho-Dong 《Journal of Radioanalytical and Nuclear Chemistry》2021,330(2):481-491
Journal of Radioanalytical and Nuclear Chemistry - It is well known that prompt neutrons from nuclear fissions show anisotropic emission properties that have been studied for nuclear safeguards... 相似文献
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A new method using Monte Carlo source simulation of interference reactions in neutron activation analysis experiments has been developed. The neutron spectrum at the sample location has been simulated using the Monte Carlo code MCNP and the contributions of different elements to produce a specified gamma line have been determined. The produced response matrix has been used to measure peak areas and the sample masses of the elements of interest. A number of benchmark experiments have been performed and the calculated results verified against known values. The good agreement obtained between the calculated and known values suggests that this technique may be useful for the elimination of interference reactions in neutron activation analysis. 相似文献
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Algorithm and application of Monte Carlo simulation for multi-dispersive copolymerization system 总被引:1,自引:0,他引:1
A Monte Carlo algorithm has been established for multi-dispersive copolymerization system, based on the experimental data of copolymer molecular weight and dispersion via GPC measurement. The program simulates the insertion of every monomer unit and records the structure and microscopical sequence of every chain in various lengths. It has been applied successfully for the ring-opening copolymerization of 2,2-dimethyltrimethylene carbonate (DTC) with δ-caprolactone (δ-CL). The simulation coincides with the experimental results and provides microscopical data of triad fractions, lengths of homopolymer segments, etc., which are difficult to obtain by experiments. The algorithm presents also a uniform frame for copolymerization studies under other complicated mechanisms. 相似文献
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Kilby Seth Jin Zhongmin Avachat Ashish Kanies Bryant Woolstenhulme Nicolas Lee Hyoung K. Graham Joseph 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(1):445-446
Journal of Radioanalytical and Nuclear Chemistry - In the original article, Equation 4 was incorrectly published. The correct equation is provided in this correction 相似文献
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This paper discusses the applicability of the integrated reverse Monte Carlo and Voronoi-Delaunay approach to local structure analysis and medium-scale structure determination of liquid metals. The advantages of this approach are shown: generation of 3D structural models using experimental diffraction data and subsequent structure determination by atomic coordinate analysis.Original Russian Text Copyright © 2004 by A. S. Roik, V. P. Kazimirov, and V. E. SokolskiiTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 683–691, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
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Four rate enhancing cases of nitroxide‐mediated living free‐radical polymerizations are simulated by the Monte Carlo method to investigate the effects of parameters on kinetics and molecular weight distribution of the resulting polymers. In all cases the equilibrium between growing and dormant chains shifts in favor of the growing chains under corresponding reaction conditions. The polymerization rates are therefore increased substantially without much loss in control of molecular weight and distribution of the products. The optimization of rate‐enhancement in living free‐radical polymerization is also discussed. 相似文献
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Chávez Mde L de Pablo L de Pablo JJ 《Langmuir : the ACS journal of surfaces and colloids》2004,20(24):10764-10770
Monte Carlo molecular simulations of the hydration of K-saturated Wyoming-type montmorillonite at constant stress in the NPzzT ensemble and at constant chemical potential in the grand canonical muVT ensemble, under basin-like conditions of 353 K and 625 bar, show a strong tendency of the K+ ions to adhere to the siloxane surface, forming predominant inner-sphere complexes with tetrahedral oxygen atoms and adsorbed water molecules. Simulations in the grand canonical ensemble predict that none of the K-montmorillonite hydrates, the one-, two-, and three-layer hydrates, are stable in this environment of high depth, temperature, and pressure. The most nearly stable configuration corresponds to the one-layer hydrate, characterized by a d001 spacing of 12.75 A, the adsorbed water being 60 molecules/layer or 180.83 mg of H2O/g of clay, an internal energy of -22.73 kcal/mol, an interlayer density of 0.365 g/mL, and a pressure tensor, Pzz, of 1999.9 bar. The interlayer structure consists of two close layers of water molecules 0.50 A from the midplane, with broad shoulders on the sides, the protons oriented toward the midplane and the siloxane surfaces, and the K+ ions close to the clay surfaces and on the interlayer midplane. 相似文献