LUCIANO ONDIR FREIRE
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Resumo IPEN-doc 28578 Some facts about nuclear forces and evidence of their range being longer than people believe2021 - FREIRE, LUCIANO O.; ANDRADE, DELVONEI A. deNuclear forces are believed to have ranges around 2 fermi and beyond that range, only electrostatic force is relevant. Before trying to make theories about the phenomena of nuclear reactions observed in solids, it is important to revise critically the existing experimental literature and nuclear theory to check if current models are coherent and if they could explain the observed phenomena. The first step is to check the current nuclear models, the second is to analyse the neutron cross-section data, the third is to discuss coherence between empirical data and models, the fourth is to identify the order of magnitude of nuclear forces range, the fifth is to revise the full height of Coulomb barrier. It was found one isotope (Gadolinium-157) that can attract a thermal neutron at least at 2781 fermi and repulses neutrons at 179 Fermi. It was also found that the plane projection of volumes where neutrons are directly captured is distinct of the projection of the volume where neutrons are scattered for most isotopes. But Kryptonium, Ruthenium, Xenonium, Iridium, and Mercury elements seem having their scattering volumes covered by the absorption volumes, or not having a scattering volume at all. Ca-44, Ca-48, Ni-64, Se-74, Te-123, Dy-162, Hf-177 and W-186 isotopes seem having a partial screening of their scattering volume by the absorption volume. Resonance capture volumes seem to be independent of direct capture volumes and have interface with scattering volume. Three facts suggest absorption volumes are consequence of nucleons arrangement, assuming an FCC nucleus model. The first is that a single additional neutron may change the order of magnitude of absorption radius (like He-3 to He-4). Second, excited states also change absorption cross-sections, like Na-23 whose first excited state increases absorption cross-section and Cl-37 whose first excited state decreases absorption cross-section. Third, neutron capture resonance depends on existence of an excited state of the compound nucleus (target nucleus plus the neutron) with energy larger than this neutron binding energy. In other words, to have a resonance, the target nucleus needs to have two places available for a neutron, and the energetic distance between them needs to be larger than a minimum (the very neutron binding energy). Compared to Coulomb forces, the nuclear forces attracting neutrons are weak, about 6 orders of magnitude smaller than electrostatic repulsion at mean thermal neutron capture radius.Resumo IPEN-doc 28577 A survey on the evolution of yearly works on Pd-D, Ti-D and Ni-H systems within cold fusion field2021 - FREIRE, LUCIANO O.; ANDRADE, DELVONEI A. deMore than 30 years have been passed since Stanley and Pons press conference announcing the discovery of “Cold Fusion”. This work aims at presenting a general view of the evolution of experimental works in the various sub-fields, like Pd-D, Ti-D, Ni-H systems. For each subfield, this work presents the yearly number of successful and unsuccessful works published in conferences or journals. For Pd-D systems, since 1989, the number of positive results (finding some nuclear reactions) is superior to negative results but there is a trend of reduction of yearly works. Ti-D systems follow the same tendency. Ni-H systems, on the other hand, present a rising tendency besides having a higher ratio of successful/unsuccessful experiments. Perhaps the smaller cost of materials and easier replication is being decisive for new research groups starting in the field, besides enterprises starting advertisement of products based on the Ni-H system.Resumo IPEN-doc 28576 A hypothesis of kinetics and dynamic control of nuclear reactions in solids2021 - FREIRE, LUCIANO O.; ANDRADE, DELVONEI A. deSeveral authors suggested that background noise could influence nuclear reactions in solids, resulting in neutrons or excess heat. Literature shows that repeatability is improving, but the control over the intensity remains out of reach. This work aims at identifying possible causes for intensity variations and proposing solutions to improve controllability. The first step is to search in literature the characteristics of nuclear reactions in solids: input, output, controlling factors and enabling means. The second step is, from solid experimental facts, draw solid conclusions. The third step is developing some assumptions about the phenomenon. For each controlling factor, verify the feasibility of implementation in a heat exchanger with high surface over volume ratio. Finally, present some alternatives of architectures to improve reactions intensity control. A solid conclusion is hot spots come from aneutronic nuclear chain reactions, meaning each energetic charged particle causes the appearance of more than one new charged particle (effective multiplication factor keff>1). Another conclusion is background neutron radiation starts chain reactions and it causes excess heat intensity variations. An assumption is a local keff>1 causes micro explosions terminating the localized reactions because heat propagates faster than the particle population, resulting in low average keff. Therefore, nanoparticles or working temperatures near melting point reduce local keff allowing slow enhancement of particle population up to a level proportional to the background neutrons. A suggestion is to shield the reactors using moderators with neutron absorbers to avoid undesirable power excursions and add a voltage-controlled neutron source to control the excess heat because of the penetrating nature of neutron radiation. Magnetic or electric fields could also help the enhancement of excess heat.Resumo IPEN-doc 26777 The four functions of elementary pipe design from constructal law2019 - FREIRE, L.O.; ANDRADE, D.A. deConstructal law explains the sense of evolution (morphing to improve flows) of beings, but paradoxes do exist as not all vegetables have a tree form. Also, not all animals are optimized for displacement. This work aims at identification of the design functions or objectives that guide evolution under the overall statement of constructal law. This work adopted the system engineering technique of segregation between functions (abstract objectives) and solutions (physical entities). Further, this work introduced the assumptions of flow under external threats and pipes subject to leakages. Results showed that there are always elements doing four functions in pipe element: to reduce flow entropy, to protect flow channel, to retain flow content and to increase flow drive. Although the four functions are always present, natural systems typically privileges some functions over others, depending on environmental pressures. As a solution to improve flows, animal brains also fit in the model of four functions. Human mind seems to have groups of instincts associated to each of the four pipe design functions (fear, attachment, curiosity and greed). Finally, the four functions model unified physics and animal psychology.