1,721,016 research outputs found
A kinetic theory approach to the dispersion relation of water waves
No full textStarting from the integral form of Boltzmann's equation a study is conducted of the propagation of waves in water. Some reasonable approximations are made, including the BGK approximation, and a dispersion relation is found
Neutrons from (α, n) reactions in uranium hexafluoride
No full textAlpha particles emitted in nuclear fuels can represent a neutron source through (α, n) reactions with surrounding nuclei. In the present work, this neutron source is evaluated for the case of uranium hexafluoride: neutron yields as a function of alpha energy and neutron yields integrated over the energy spectrum are given
Diffusion near an interface via Onsager-type equations
No full textOnsager-type transport equations, as were derived in a previous paper by the authors, are applied to the diffusion of test particles near the interface of a scattering medium with a perfect absorber. Temperature and density profiles are obtained for different types of scattering cross-section
Convective circulation and heat flux in a gas
No full textIn a previous paper1, a model had been developed to calculate temperature and density profiles and the fluxes of heat and matter with Onsager-type transport equations. The method is now applied to a 2-dimensional, cylindrically symmetric configuration: a gas between two parallel, circular plates. Such a configuration will exhibit Benard convecting: circulation patterns are obtained, together with temperature and density p-y distributions and the flow of energy. © 1995, Taylor & Francis Group, LLC. All rights reserved
Heat flux and temperature and density profiles in a gas
No full textStarting from Boltzmann's equation, a method is developed for calculating temperature and density profiles and heat flux in a neutral gas in the presence of a temperature gradient and an external force. A generalized barometric law is obtained. The influence of different cross-section models is also investigated. © 1988 Società Italiana di Fisica
Equation of state for dense gases from a self-consistent-field approach in the framework of kinetic theory
No full textThe departure from ideal gas behavior is described by several known equations of state (EoS), developed from a combination of theoretical considerations and experimental correlations. In this work, a different approach, in the framework of kinetic theory, is proposed: from a pairwise potential of the Lennard–Jones type, the interaction between molecules is accounted for by means of a self-consistent force field. The propagation of a perturbation wave in the dense gas or liquid of unperturbed density n0 is described and the isothermal propagation velocity is determined. An EoS is derived and compared to the van der Waals EoS, of which it is found to reproduce the main features
Electron Beams and X-Ray Beams for Interstitial and Intra-Operatory Radiation Therapy.
No full textThe present invention refers to an apparatus for the production of electron beams and X-ray beams for interstitial and intra-operatory radiation therapy, more commonly named IORT (Intra Operative Radio Therapy). More specifically, the invention refers to an apparatus IORT using a Plasma Focus type of machine, coupled to an electron guide which convoys the beam directly to the tissue to be treated with a low-energy, extremely high dose rate of electron or photonic X-ray irradiation
Evaluation of the radiological hazard in electron beam welding
No full textIn electron beam welding a very intense pencil beam of electrons is driven onto the base metal, to melt it and produce the welding. In the interaction of the beam with the metal, strong bremsstrahlung emission of X-ray is generated. Here the generation is evaluated, and the KERMA in air at 1 m is predicted. Results show that a significant radiation hazard is present and serious radiation protection measures are needed
Entropy evolution in reactions
No full textThe purpose of this work is to show the role of distribution funtions of reactant and reaction products in the evolution of the entropy of a system undergoing nuclear or chemical reactions. This analysis is conducted with the help of the H theorem, in the framework of kinetic theory
Thermal Hydraulic and Neutronic Core Model for Jules Horowitz Reactor (JHR) Kinetics Analysis
Full text linkThis report, issued in the frame of task LP2-E.2 of the AdP PAR2008-09 assigned to CIRTEN , outlines the work performed during the period of time spent at the CEA Cadarache Research Centre in the Jules Horowitz Reactor (JHR) project. A thermal hydraulic and neutronic model of JHR core is presented and implemented through a kinetics ca!culation code (DULCINEE). Different shutdown procedures are then considered and ana!yzed in order to verify reactivity insertions and thermal hydraulic feedbacks for core power transients
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