368 research outputs found
Swelling Mechanism of Lattice with the Ingrowth of the Defects in UO2
Swelling of uranium dioxide with ingrowth of defects by irradiation is not
fully understood. Experimental and theoretical groups have attempted to explain
this phenomenon with various complex theories. In this study, experimental
lattice expansion and super saturation of the lattice were well reproduced by
molecular dynamics simulation method. From the resemblance with the
experimental data, here it is manifested that only oxygen frenkel pairs were
created in the fission induced lattice while alpha particle radiation causes
both oxygen and considerable amount of uranium defects. Moreover, in this work,
defects are divided into two sub-groups as obstruction and distortion and it is
shown that obstruction type frenkel pairs merely responsible for the lattice
swelling for both fission and alpha particle radiation. Evidently relative
lattice expansion varies linearly with the obstruction type of survived uranium
defects. Additionally, at high concentrations, some of the obstruction type
uranium frenkel pairs forming double or triple structures with oxygens in their
octahedral cages which increase the slope of the linear dependence.Comment: 24 pages, 12 figure
Actinide and Lanthanide Dioxide Lattice Dilatation Mechanisms with Defect Ingrowth
{\alpha}-particle irradiated single-crystal isostructural oxide lattices
(CmO2, AmO2, CeO2, UO2, NpO2, PuO2, ThO2) were modeled by molecular dynamics
simulation method. Lattice parameter changes with IFP cation defects displayed
exponential increases. These data were compatible with the available lattice
parameter changes with {\alpha}-particle dose experiments. Pre- and post- peaks
emerged around principal peaks of irradiated oxide cation-cation radial
distribution functions, which indicate obstruction and distortion type defects,
respectively. Dependence of lattice dilatations on the number of obstruction
type cation defects was examined. In a previous study, obstruction type uranium
defects were found to be directly responsible for the UO2 lattice swelling and
there was a linear relationship between them. It was also determined that this
linear equation has two different slopes at low and high defect concentrations.
In this paper, it was found that these phenomena were not specific to UO2 and
applicable to all fluorite-structured actinide and lanthanide dioxides studied
here. These findings provide clues about the existence of more general law.Comment: 44 pages, 8 Figures, 4 Tables, Supplementary Materia
Multiagent cooperation for solving global optimization problems: an extendible framework with example cooperation strategies
This paper proposes the use of multiagent cooperation for solving global optimization problems through the introduction of a new multiagent environment, MANGO. The strength of the environment lays in itsflexible structure based on communicating software agents that attempt to solve a problem cooperatively. This structure allows the execution of a wide range of global optimization algorithms described as a set of interacting operations. At one extreme, MANGO welcomes an individual non-cooperating agent, which is basically the traditional way of solving a global optimization problem. At the other extreme, autonomous agents existing in the environment cooperate as they see fit during run time. We explain the development and communication tools provided in the environment as well as examples of agent realizations and cooperation scenarios. We also show how the multiagent structure is more effective than having a single nonlinear optimization algorithm with randomly selected initial points
Comparison of life quality of pregnant adolescents with that of pregnant adults in Turkey
Objectives. This study aimed to determine the quality of life of pregnant adolescents aged < 20 years and pregnant adults aged between 20-29 years, to evaluate the effects of gestational periods on the quality of life, and to compare the quality of life scores of pregnant adolescents and adults
Video fire detection - Review
This is a review article describing the recent developments in Video based Fire Detection (VFD). Video surveillance cameras and computer vision methods are widely used in many security applications. It is also possible to use security cameras and special purpose infrared surveillance cameras for fire detection. This requires intelligent video processing techniques for detection and analysis of uncontrolled fire behavior. VFD may help reduce the detection time compared to the currently available sensors in both indoors and outdoors because cameras can monitor "volumes" and do not have transport delay that the traditional "point" sensors suffer from. It is possible to cover an area of 100 km2 using a single pan-tilt-zoom camera placed on a hilltop for wildfire detection. Another benefit of the VFD systems is that they can provide crucial information about the size and growth of the fire, direction of smoke propagation. © 2013 Elsevier Inc. © 2013 Elsevier Inc. All rights reserved
Waterpipe (narghile) smoking among medical and non-medical university students in Turkey
Objectives. This investigation was performed in order to determine the prevalence rate of waterpipe smoking in students of Erciyes University and the effects of some socio-demographic factors
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