Modeling of ion-implanted atoms diffusion during the epitaxial growth of the layer

The equation of impurity diffusion due to formation, migration, and dissolution of the pairs "impurity atom - intrinsic point defect" taking into account the nonuniform distributions of nonequilibrium point defects and drift of the pairs in the field of elastic stresses is presented in the coordinate system associated with the moving surface of the growing epitaxial layer. The analytical solution of this equation for the low fluence ion implantation has been obtained.Comment: 3 pages, 2 figure

Singularity deep inside the spherical charged black hole core

We study analytically the spacelike singularity inside a spherically-symmetric, charged black hole coupled to a self-gravitating spherical massless scalar field. We assume spatial homogeneity, and find a generic solution in terms of a formal series expansion. This solution is tested against fully-nonlinear and inhomogeneous numerical simulations. We find full compliance between our analytical solution and the pointwise behavior of the singularity in the numerical simulations. This is a strong scalar-curvature monotonic spacelike singularity, which connects to a weak null singularity at asymptotically-late advanced time.Comment: 6 pages, to be published in Phys. Rev.

Self force on static charges in Schwarzschild spacetime

We study the self forces acting on static scalar and electric test charges in the spacetime of a Schwarzschild black hole. The analysis is based on a direct, local calculation of the self forces via mode decomposition, and on two independent regularization procedures: A spatially-extended particle model method, and on a mode-sum regularization prescription. In all cases we find excellent agreement with the known exact results.Comment: 21 pages, 9 Encapsulated PostScript figures, submitted to Class. Quantum Gra

Numerical investigation of the late-time Kerr tails

The late-time behavior of a scalar field on fixed Kerr background is examined in a numerical framework incorporating the techniques of conformal compactification and hyperbolic initial value formulation. The applied code is 1+(1+2) as it is based on the use of the spectral method in the angular directions while in the time-radial section fourth order finite differencing, along with the method of lines, is applied. The evolution of various types of stationary and non-stationary pure multipole initial states are investigated. The asymptotic decay rates are determined not only in the domain of outer communication but along the event horizon and at future null infinity as well. The decay rates are found to be different for stationary and non-stationary initial data, and they also depend on the fall off properties of the initial data toward future null infinity. The energy and angular momentum transfers are found to show significantly different behavior in the initial phase of the time evolution. The quasinormal ringing phase and the tail phase are also investigated. In the tail phase, the decay exponents for the energy and angular momentum losses at future null infinity are found to be smaller than at the horizon which is in accordance with the behavior of the field itself and it means that at late times the energy and angular momentum falling into the black hole become negligible in comparison with the energy and angular momentum radiated toward future null infinity. The energy and angular momentum balances are used as additional verifications of the reliability of our numerical method.Comment: 33 pages, 12 figure

The Speciality Index as invariant indicator in the BKL Mixmaster Dynamics

The speciality index, which has been mainly used in Numerical Relativity for studying gravitational waves phenomena as an indicator of the special or non-special Petrov type character of a spacetime, is applied here in the context of Mixmaster cosmology, using the Belinski-Khalatnikov-Lifshitz map. Possible applications for the associated chaotic dynamics are discussed

Physics of the interior of a black hole with an exotic scalar matter

We use a numerical code to consider the nonlinear processes arising when a Reissner-Nordstrom black hole is irradiated by an exotic scalar field (modelled as a free massless scalar field with an opposite sign for its energy-momentum tensor). These processes are quite different from the processes arising in the case of the same black hole being irradiated by a pulse of a normal scalar field. In our case, we did not observe the creation of a spacelike strong singularity in the T-region of the space-time. We investigate the antifocusing effects in the gravity field of the exotic scalar field with the negative energy density and the evolution of the mass function. We demonstrate the process of vanishing of the black hole when it is irradiated by a strong pulse of an exotic scalar field.Comment: 16 pages, 16 figures. Text has been rewritten and restructured, Penrose diagrams have been added, appendix with convergence tests has been added. Co-author has been added. Conclusions are unchange

Plastic Reconstruction of Dehenerative Achilles Tendon Ruptures Using the Bioprosthesis of Xenopericardium

Two methods for the plastic reconstruction of degenerative Achilles tendon ruptures have been developed, using biological xenopericardium prosthetics. 21 patients were operated. In cases of tendon gliding surface deformation, the insulating plastic reconstruction was used in 14 of them by wrapping the suture area with xenopericardium; the replacement plastic reconstruction was applied in 7 patients. In case of an unrecoverable defect, the tendons were replaced with a specially formed prosthesis. The long-term results of the use of xenopericardium prostheses were compared with the traditional methods. The study involved 120 patients, divided into 5 groups according to the type of surgery: the closed perirocous suture of the Achilles tendon (25 patients), the open stitching of the ruptured tendon (28 patients), the plastic tendon by Chernavsky (24 patients), the tendon plastics by the lavsan ribbon (22 patients) and the tendon grafting with xenopericardium bioprostheses (21 patients). The results were evaluated by the method of Leppilahti J. (1998). The results obtained suggest that the application of xenopericardial prosthetics leads to a significant increase in the number of excellent and good results in comparison with the other methods

The late-time singularity inside non-spherical black holes

It was long believed that the singularity inside a realistic, rotating black hole must be spacelike. However, studies of the internal geometry of black holes indicate a more complicated structure is typical. While it seems likely that an observer falling into a black hole with the collapsing star encounters a crushing spacelike singularity, an observer falling in at late times generally reaches a null singularity which is vastly different in character to the standard Belinsky, Khalatnikov and Lifschitz (BKL) spacelike singularity. In the spirit of the classic work of BKL we present an asymptotic analysis of the null singularity inside a realistic black hole. Motivated by current understanding of spherical models, we argue that the Einstein equations reduce to a simple form in the neighborhood of the null singularity. The main results arising from this approach are demonstrated using an almost plane symmetric model. The analysis shows that the null singularity results from the blueshift of the late-time gravitational wave tail; the amplitude of these gravitational waves is taken to decay as an inverse power of advanced time as suggested by perturbation theory. The divergence of the Weyl curvature at the null singularity is dominated by the propagating modes of the gravitational field. The null singularity is weak in the sense that tidal distortion remains bounded along timelike geodesics crossing the Cauchy horizon. These results are in agreement with previous analyses of black hole interiors. We briefly discuss some outstanding problems which must be resolved before the picture of the generic black hole interior is complete.Comment: 16 pages, RevTeX, 3 figures included using psfi

Features of planning and realization of economy technologies of stamping of purveyance rectangular and round in a plan

Бурко, В. А. Особенности проектирования и реализации ресурсосберегающих технологий штамповки поковок прямоугольных и круглых в плане / В. А. Бурко // Вісник Приазовського державного технічного університету : зб. наукових праць / ПДТУ. – Маріуполь, 2012. – Вип. 25. – С. 87–94. – (Серія : Технічні науки).В статье рассмотрены особенности проектирования технологий штамповки поковок прямоугольных и круглых в плане и расчета переходов, выявлено различие подходов в определении важных технологических характеристик у многих авторов. Установлена необходимость привести имеющуюся и накопленную информацию в унифицированную систему понятий и определений.У статті розглянуті особливості проектування технологій штампування поковок прямокутних і круглих в плані і розрахунку переходів, виявлена відмінність підходів у визначенні важливих технологічних характеристик у багатьох авторів. Встановлена необхідність привести існуючу і накопичену інформацию в уніфіковану систему понять і визначень.In the article the features of planning of technologies of stamping of purveyance are considered rectangular and round in a plan and calculation of transitions, distinction of approaches is exposed in determination of important technological descriptions for many authors. A necessity to drive present and accumulated information to the compatible system of concepts and determinations is set

Analytical treatment of critical collapse in 2+1 dimensional AdS spacetime: a toy model

We present an exact collapsing solution to 2+1 gravity with a negative cosmological constant minimally coupled to a massless scalar field, which exhibits physical properties making it a candidate critical solution. We discuss its global causal structure and its symmetries in relation with those of the corresponding continously self-similar solution derived in the $\Lambda=0$ case. Linear perturbations on this background lead to approximate black hole solutions. The critical exponent is found to be $\gamma = 2/5$.Comment: 22 pages, 6 figures. Major changes in the discussions of Sects. 2 and 5. The value of the critical exponent has been revised to \gamma = 2/