New method to determine FAO number of maize, Zea mays L.

FAO numbers are generally calculated from the grain moisture at harvest, which has decreased substantially in recent decades. In many countries maize is now harvested with a grain moisture of around 20 %. However, the lower the grain moisture at harvest, the smaller the difference in grain moisture between the maturity groups and/or individual hybrids. The reliability of grain moisture measurements has not improved parallel to the decline in the differences between hybrids, making it difficult to determine the maturity dates of the hybrids reliably. A new method has been elaborated to solve this problem and has been successfully used for the last two years in official trials in Hungary. The new method has several advantages: (a) more maturity parameters are taken into consideration, so the evaluation of more data improves reliability, (b) regression between the maturity parameters and the FAO number is calculated using several standards, thus reducing the effect of the G x E interaction and the experimental error. As a result, the annual fluctuation in the FAO number for each 1 % grain moisture is reduced

Computational Investigation and Experimental Verification of Multiplicity Counting from the Continuous Signals of Fission Chambers

In a series of previous publications, we suggested an alternative method to the pulse-counting based multiplicity counting technique for the characterisation of special nuclear materialscollision number expansion. The new method uses the continuous signals of fission chambers, and the multiplicity rates, i.e. the singles, doubles and triples rates are extracted from the auto- and cross-covariances of one or more fission chambers. Until recently only the theory of the method was elaborated. The purpose of the work described in this report was to verify the method and investigate its performance and applicability through detailed simulations as well as with a dedicated experiment. Numerical simulations of the method were performed by a code specially developed for this study, and pilot measurements were performed at the critical assembly KUCA of the Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS). This report gives an account of both the work performed and the results of the study

Simulation of a research reactor reactivity transient with deterministic and GPU-assisted Monte Carlo reactor kinetics codes

Reactor kinetic codes are crucial in safety assessment. Validating spatial and high temporal resolution kinetic solvers without thermal feedback is problematic as measurements seldom involve detailed spatial and fine temporal resolution. Benchmarking of deterministic codes thus often resorts to code-to-code comparison against Monte Carlo codes, which can only recently treat direct time dependence. In this paper, we have attempted to compare results from the GUARDYAN directly time-dependent Monte Carlo code and the SEnTRi transient driver developed for the PARTISN deterministic transport code to low power transient measured at the BME Training Reactor. Code-to-measurement comparisons were successful, despite a major uncertainty in the actual timing of the reactivity insertion and withdrawal originating from the instrumentation of the pneumatic rabbit system. Code-to-code comparisons concluded that time dependence was correctly implemented in both GUARDYAN and SEnTRi; furthermore, a hypothetical scenario was set up involving an instantaneous insertion of a negative reactivity into the BME TR core in order to compare spatially and temporally dependent fluxes. The simulations demonstrated the appearance of higher-order modes, and results showed a relatively good match, although fidelity of the comparison could be further improved by reducing the statistical uncertainty of the results provided by GUARDYAN

Multiplicity counting using the two- and three point statistics of fission chamber signals – Theory and experimental demonstration

In two earlier papers [1,2] we investigated the possibility of extracting traditional multiplicity count rates from the cumulants of fission chamber signals in current mode. The first three cumulants were derived for up to three detectors. It was shown that if all neutrons emitted from the sample simultaneusly are also detected simultaneously, the multiplicity rates can be retrieved from the cumulants of the detector current, but the method breaks down if the detections of neutrons of common origin take place with a time delay spread wider than the pulse shape. To remedy these shortcomings, in this work we extended the theory to two- and three-point distributions (correlations). It was found that the integrals of suitably chosen two- and three-point moments with respect to the time differences become independent of the probability density of the time delays of detections. With this procedure, the multiplicity rates can be retrieved from the detector currents for arbitrary time delay distributions. To demonstrate the practical applicability of the proposed method, pilot measurements are performed. A description of the experimental setup and some preliminary experimental results are presented in the paper

Lepidocrocite-like structure of the TiO2 monolayer grown on Ag(100)

Titanium oxide ultrathin films were grown on Ag(100) by evaporation of titanium in an O2 atmosphere. The growth of the oxide films was monitored by means of XPS. The Ti2p XPS spectra indicate the formation of films with a TiO2 stoichiometry in the whole range of coverages studied here. The STM results show that titania films appear to grow as islands of uniform thickness up to the completion of the first layer. Up to the formation of one complete monolayer, a (5 1) LEED pattern is observed. This pattern can be interpreted as a coincidence mesh and the lattice parameters of the oxide layer are very close to those of TiO2 films with a lepidocrocite-like structure. However, the STM images show a long-range coincidence between the periodicity of the oxide film and that of the substrate along the short side of the oxide unit cell revealing that this lattice parameter is not exactly equal to that of the substrate. Above the monolayer coverage, additional spots become visible in the LEED pattern which can be interpreted in terms of the unit cell of rutile (110). The structural determination was carried out for the monolayer of titania by means of XPD and LEED intensity analysis. The results of these investigations demonstrate that the titania monolayer has a lepidocrocite-like structure. The DFT calculations carried out for the titania monolayer show the higher stability of the lepidocrocite structure with respect to other structures derived from crystallographic planes of bulk TiO2 phases. Moreover, these calculations allow us to determine the oxide–substrate interface energy as well as to clarify the effect of the strain on the stability of the oxide layer

Diphosphetes-substituent stabilized ring systems

Bertrand G, Eisfeld W, Nyulaszi L, Reau R, Regitz M, Szieberth D. Diphosphetes-substituent stabilized ring systems. JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2. 2000;(11):2324-2327

Steady-state neutronic measurements and comprehensive numerical analysis for the BME training reactor

This paper describes steady-state reactor physics measurements and calculations that were performed for the Training Reactor of Budapest University of Technology and Economics (BME TR) with the purpose of benchmarking. Based on the available geometry specifications and material compositions a model of BME TR was created with the well-validated, general-purpose Serpent 2 Monte Carlo code. Uncertain parameters (such as fuel density and control rod positions) were adjusted to related measurements. The Serpent 2 model was used for the generation of group constants, examining several homogenization schemes. Models were created in the PARCS diffusion code, the SPNDYN diffusion and SP3 code and the PARTISN discrete ordinates code. Various Monte Carlo and deterministic calculations were performed with the adjusted models and the results were then compared with actual measured data. The calculations and measurements show good agreement, this way the Serpent model was successfully validated, while the deterministic models make a good basis for more complex benchmarks in the future, such as transients with thermal-hydraulic feedback. (C) 2021 The Author(s). Published by Elsevier Ltd