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Lubarda V.A.,University of California at San Diego | Lubarda V.A.,Montenegrin Academy of science and Arts
International Journal of Plasticity | Year: 2011

Among all directions available for dislocation emission from the surface of a cylindrical circular void, the direction of the most likely emission is determined. It is shown that this direction is different from the direction of the maximum shear stress at the surface of the void due to the applied loading. The critical stress and the direction of the dislocation emission are determined for circular nanovoids under remote uniaxial, pure shear, and arbitrary biaxial loading. The analysis includes effects of the loading orientation relative to the discrete slip plane orientation. It is shown that dislocations are emitted more readily from larger nanovoids and that wider dislocations are emitted under lower applied stress than narrow dislocations. Different mechanisms, under much lower stress, operate for growth of the micron-size voids. © 2010 Elsevier Ltd. All rights reserved.

One new species of the genus Niphargus Schiödte, 1849 (Amphipoda, Gammaridea, Niphargidae) from the subterranean waters (springs) above Ravno Vrdovo in Dinara Mountain, Croatia, is described. Niphargus radzai sp. n. belongs to the artificial group within Niphargus with elevated number of setae along outer margin of dactylus in gnathopods 1 and 2 and dactylus of some or all pereopods provided with additional spines along inner margin. The differences between N. radzai and some other similar members of this group of taxa are discussed. Copyright © 2014 Magnolia Press.

Antovic N.M.,University of Montenegro | Vukotic P.,Montenegrin Academy of science and Arts | Svrkota N.,Center for Ecotoxicological Research | Andrukhovich S.K.,B. I. Stepanov Institute of Physics
Journal of Environmental Radioactivity | Year: 2012

The 239+240Pu activity concentrations in soil from Montenegro (six samples from three localities) have been measured for the first time. The alpha and gamma-spectrometric measurements are used to determine the 239+240Pu/ 137Cs activity ratio, and it was found to be with an average of 0.02 and standard deviation of 0.007. This average activity ratio was applied to estimate 239+240Pu in soil samples from the other 21 localities at which 137Cs activity concentrations were measured. In this research obtained (either experimentally or estimated) 239+240Pu activity concentrations (0.036-8.265 Bq kg -1) are comparable with those measured in some other European countries. On the basis of the results obtained in the present study and a survey of relevant literature, it is possible to conclude that Chernobyl contribution to 137Cs contamination of Montenegro soils is dominant, whilst Pu contamination comes from the global fallout of nuclear weapon tests. © 2012 Elsevier Ltd.

Lubarda V.A.,University of California at San Diego | Lubarda V.A.,Montenegrin Academy of science and Arts | Talke K.A.,University of California at San Diego
Langmuir | Year: 2011

The extent of a droplet's spreading over a flat, smooth solid substrate and its equilibrium height in the presence of gravity are determined approximately, without a numerical solution of the governing nonlinear differential equation, by assuming that the droplet takes on the shape of an oblate spheroidal cap and by minimizing the corresponding free energy. The comparison with the full numerical evaluations confirms that the introduced approximation and the obtained results are accurate for contact angles below about 120° and for droplet sizes on the order of the capillary length of the liquid. The flattening effect of gravity is to increase the contact radius and decrease the height of the droplet, with these being more pronounced for higher values of the Bond number. © 2011 American Chemical Society.

Lubarda V.A.,University of California at San Diego | Lubarda V.A.,Montenegrin Academy of science and Arts
Mechanism and Machine Theory | Year: 2014

The mechanics of belt friction before the state of gross slip is considered. The variation of the belt force within the contact region is evaluated based on the assumption of gradual growth of slip from the pull-end to the hold-end of the belt, as the pull force increases towards its Euler's value. The local pressure and friction forces exerted by the belt on the cylinder are also determined. Both flat and V-shaped belts are considered. The total pressure and friction forces are evaluated at an arbitrary stage of slip growth. They are neither proportional nor orthogonal to each other, unless the state of gross slip is reached throughout the contact range. © 2014 Elsevier Ltd. All rights reserved.

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