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[en] Performance characteristics of the Nuclear Thermal Rocket can be enhanced through the use of unconventional nozzles as part of the propulsion system. In this report, the Nuclear Thermal Rocket nozzle testing and evaluation program being conducted at the NASA Lewis Research Center is outlined and the advantages of a plug nozzle are described. A facility description, experimental designs and schematics are given. Results of pretest performance analyses show that high nozzle performance can be attained despite substantial nozzle length reduction through the use of plug nozzles as compared to a convergent-divergent nozzle. Pretest measurement uncertainty analyses indicate that specific impulse values are expected to be within plus or minus 1.17%
[en] Subgroup 19 on Activation Cross Sections of the Working Party on Evaluation Cooperation of the OECD-NEA has recently concluded its activities. The goal of the subgroup was to generate a large set of new measured activation cross sections relevant to nuclear applications and make these data available to the nuclear science community. In addition, modeling efforts and sensitivity studies were undertaken to evaluate the use of measured data and model calculations for the prediction of unknown cross sections. The latter addresses the potential of model calculations to satisfy issues on the High Priority Request List when no measured data are available. In the course of the activities of the subgroup over ninety reaction channels were studied experimentally. All except the most recent of these data have been compiled into EXFOR format by members of the subgroup and submitted to OECD- NEA. As a result most of these data can now be retrieved online from the data centers. A systematic comparison was made with the new evaluated data files JEF3.0/EAF2003, JENDL3.3, and ENDF/B-VI.8 and with the current status of the global parameter systematics of the model code TALYS-0.57. In addition, a considerable number of locally optimized parameter sets were developed. Both the global and local approaches emphasize the use of consistent physics modelling for all important reaction channels and nuclides involved in the decay. Comparison of the two approaches allows assessment of the effort required when model estimates to a certain accuracy must be made. Parameter sensitivity studies were undertaken to further assess the accuracy requirements on model parameters if target uncertainties for the cross sections have been specified. The value of this approach has demonstrated itself and indicates the need for model codes that fit all available experimental data in order to connect the data covariance with the covariance of the model predictions. The work of the subgroup was a joint effort between IRMM, ANL, FZ-Juelich, INRNE Sofia, NIPNE Bucharest, IEP and Atomki Debrecen, JAERI, and Tohoku University. A comprehensive review of the subgroup activities will be presented
[en] The atomic masses are important input parameters for nuclear astrophysics calculations. The Atomic Mass Evaluation (AME) is the most reliable source for comprehensive information related to atomic masses. The latest AME was published in 2003. A new version, which will include the impact of a wealth of new, high-precision experimental data, will be published in December 2012. In this paper we will give the current status of AME2012. The mass surface has been changed significantly compared to AME2003, and the impact on astrophysics calculations is discussed.
[en] We discuss how the presence of environmental effects and quasiparticle agglomerates could better reconcile the edge states theories with the experimental observations for the case of ν = 5/2. The Pfaffian and the anti-Pfaffian models will be compared in connection with experimental results identifying the latter as the best candidate
[en] Mahalanobis distance Δ"2 values are commonly in the range of 0 to +∞ where higher values represent greater distance between class means or points. The increase in Mahalanobis distance is unbounded as the distance multiply. To certain extend, the unbounded distance values pose difficulties in the evaluation and decision for instance in the sensors closeness test. This paper proposes an approach to [0, 1] bounded Mahalanobis distance Δ"2 that enable researcher to easily perform sensors closeness test. The experimental data of four different types of rice based on three different electronic nose sensors namely InSniff, PEN3, and Cyranose320 were analyzed and sensor closeness test seems successfully performed within the [0, 1] bound
[en] We give a short introduction to the calculation of the leading chiral logarithms, and present the results of the recent evaluation of the LLog series for the nucleon mass within the heavy baryon theory. The presented results are the first example of LLog calculation in the nucleon ChPT. We also discuss some regularities observed in the leading logarithmical series for nucleon mass
[en] In this paper we propose a new measure of bivariate asymmetry, based on conditional correlation coefficients. A decomposition of the Pearson correlation coefficient in terms of its conditional versions is studied and an example of application of the proposed measure is given.
[en] An innovative approach to safety analysis of multistate ageing systems is presented. Basic notions of the ageing multistate systems safety analysis are introduced. The system components and the system multistate safety functions are defined. The mean values and variances of the multistate systems lifetimes in the safety state subsets and the mean values of their lifetimes in the particular safety states are defined. The multi-state system risk function and the moment of exceeding by the system the critical safety state are introduced. Applications of the proposed multistate system safety models to the evaluation and prediction of the safty characteristics of the consecutive “m out of n: F” is presented as well.
[en] In the paper a prompt method to evaluate the seismic vulnerability of an ancient structure has been applied to the seismic vulnerability of the fortified structures in Italy, having as basics the elaboration of rather gross information about the state, the consistency and the history of the considered population of fabrics. The procedure proves to be rather effective and able to produce reliable results, despite the poor initial data
[en] The conceptual design of pressure relief systems is an important aspect in the early phase of any cryogenic system design, because a prudent and responsible evaluation of relief systems involves much more than just relief devices. The conceptual design consists of various steps: At first, hazard scenarios must be considered and the worst-case scenario identified. Next, a staged interaction against pressure increase is to be defined. This is followed by the selection of the general type of pressure relief device for each stage, such as safety valve and rupture disc, respectively. Then, a decision concerning their locations, their capacities and specific features must be taken. Furthermore, it is mandatory to consider the inlet pressure drop and the back pressure in the exhaust line for sizing the safety devices. And last but not least, economic and environmental considerations must be made in case of releasing the medium to the atmosphere. The development of the system's safety concept calls for a risk management strategy based on identification and analysis of hazards, and consequent risk mitigation using a system-based approach in compliance with the standards