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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.


Lubarda V.A.,University of California at San Diego | Lubarda V.A.,Montenegrin Academy of science and Arts
Acta Mechanica | Year: 2013

The free-surface shape of a liquid in a uniformly rotating cylinder in the presence of surface tension is determined before and after the onset of dewetting at the bottom of the cylinder. Two scenarios of liquid withdrawal from the bottom are considered, with and without deposition of thin film behind the liquid. The governing non-linear differential equations for the axisymmetric liquid shapes are solved numerically by an iterative procedure similar to that used to determine the equilibrium shape of a liquid drop deposited on a solid substrate. The numerical results presented are for cylinders with comparable radii to the capillary length of liquid in the gravitational or reduced gravitational fields. The capillary effects are particularly pronounced for hydrophobic surfaces, which oppose the rotation-induced lifting of the liquid and intensify dewetting at the bottom surface of the cylinder. The free-surface shape is then analyzed under zero gravity conditions. A closed-form solution is obtained in the rotation range before the onset of dewetting, while an iterative scheme is applied to determine the liquid shape after the onset of dewetting. A variety of shapes, corresponding to different contact angles and speeds of rotation, are calculated and discussed. © 2013 Springer-Verlag Wien.


Karaman G.S.,Montenegrin Academy of science and Arts
Ecologica Montenegrina | Year: 2016

One new species of the family Niphargidae (Amphipoda Gammaridea), Niphargus frontalis, sp. n. is described from the subterranean waters of Frontale, Coldigioco, Italy, and its relations to other similar Niphargus species from Italy is discussed. The species Typhlogammarus mrazeki Schäf. 1906 (fam. Typhlogammaridae) is mentioned from new locality in Montenegro and the variability of this species is presented.


Karaman G.S.,Montenegrin Academy of science and Arts
Ecologica Montenegrina | Year: 2016

From the subterranean waters of the Velika Bukovicka špilja Cave near Bukovica village (Tomislavgrad region, Bosnia and Herzegovina) is described and figured one new species of the family Niphargidae (Amphipoda, Gammaridea), Niphargus bukovicensis, sp. n. This species is characterized by presence of elevated number of spines on dactylus of pereopods 6 and 7 only, by numerous setae along dactylus outer margin of gnathopods 1-2, pointed epimeral plate 3 and by elongated inner and outer ramus of uropod 3 in males. The taxonomical relation of this species regarding other similar members of genus Niphargus Schiödte, 1849, is discussed.


Karaman G.S.,Montenegrin Academy of science and Arts
Ecologica Montenegrina | Year: 2016

Two new taxa of the family Niphargidae (Crustacea Amphipoda) from Italy are presented. Niphargus rotundus, sp. n., described and figured from Montelupo Albeze, 450 m a.s.l (Cuneo, Piemonte), and Niphargus sestaputeanus, sp. n., described and figured from Sesta Godano, Passo del Rastrello, 1000 m a.s.l. (La Spezia). The both taxa, based on the morphological characters, are close to the Niphargus puteanus Koch- Complex and its taxonomial position within genus Niphargus is discussed.


Karaman G.S.,Montenegrin Academy of science and Arts
Ecologica Montenegrina | Year: 2016

New species of the family Niphargidae (Amphipoda Gammaridea), Niphargus impexus, sp. n. is described and figured from the well in Iraklion on Crete Island, Greece, and its taxonomical position within the genus Niphargus is discussed. The species Niphargus salonitanus S. Karaman, 1950 is discovered at the first time on the Lastovo Island (spring Lokanj in Uble village) in the Adriatic Sea, and distribution of this species is mentioned.


Karaman G.S.,Montenegrin Academy of science and Arts
Ecologica Montenegrina | Year: 2015

Two species of subterranean Amphipoda from the fresh waters of western Dinarid Mountains on Balkan Peninsula are treated in this work: Niphargus bosniacus described from Mračna pećina Cave in Bosnia and Herzegovina by Stanko Karaman (1943) and known from this locality only, was collected again from the type-locality and redescribed and figured in detail, and its relationship to some other taxa of genus Niphargus are treated. The species Typhlogammarus mrazeki Schäferna, 1906, known from several localities in Montenegro, Herzegovina, southern and central Croatia, was discovered now in the Tunel Sv. Ilija near village Zagvozd on Biokovo Mt. above Makarska (Croatia).


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.


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
International Journal of Solids and Structures | Year: 2011

The image force exerted by the free surface of a cylindrical circular void on a nearby straight dislocation depends on whether the dislocation has arrived at its location by the emission from the surface of the void, or by the glide from infinity. In the context of elasticity theory, in the first case, the dislocation has been created by imposing the displacement discontinuity along the cut from the free surface of the void to the center of the dislocation, and, in the second case, from the center of the dislocation to infinity. The explicit expressions for the two corresponding image forces are derived and compared. It is shown that the attraction from the free surface of the void is stronger in the first case, particularly for smaller voids. Furthermore, in the case of dislocation emitted from the surface of the void, the interaction energy depends on the cut used to impose the displacement discontinuity, but not in the case of a dislocation approaching the void from infinity. The relevance of the obtained results for the materials science problems is discussed. © 2010 Elsevier Ltd. All rights reserved.

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