The Properties of Chromium Steel Overlaying Used as a Hardening Coating for Stop Valve Sealing Surface

AbstractOperational reliability of a pipeline valve depends on the durability of the weld sealing surfaces of the stop device, while the durability of the sealing surface is determined by the coating material properties. To enhance stop valve durability, a new composition for a flux-cored wire was developed, ensuring the generation of the surfacing metal with alloying system Cr-Ni-Mo-Mn-Si-Nb-Ti-B. Such wire provides overall hardening of the coating matrix with carboboride and intermetallic phases, providing an advanced operational reliability of stop valve nodes operating under friction conditions in aggressive environment

S-duality and Topological Strings

In this paper we show how S-duality of type IIB superstrings leads to an S-duality relating A and B model topological strings on the same Calabi-Yau as had been conjectured recently: D-instantons of the B-model correspond to A-model perturbative amplitudes and D-instantons of the A-model capture perturbative B-model amplitudes. Moreover this confirms the existence of new branes in the two models. As an application we explain the recent results concerning A-model topological strings on Calabi-Yau and its equivalence to the statistical mechanical model of melting crystal.Comment: 13 page

Позиционирование как элемент комплекса туристского маркетинга.

В статье определяются понятие, сущность и содержание позиционирования, его место и роль в комплексе маркетинга туристского предприятия. На основе анализа работ российских, белорусских и зарубежных авторов выделены четыре подхода к определению понятия и сущности позиционирования – потребительский, процессный, имиджевый и комплексный. Авторы, придерживаясь комплексного подхода, дают собственное определение указанному понятию, выделяют основные признаки позиционирования, делают выводы о дальнейших направлениях развития теории и практики позиционирования.= In article the concept, essence and the content of positioning, its place and a role of a complex of marketing of the tourist enterprise are defined. On the basis of the analysis of works of the Russian, Belarusian and foreign authors four approaches to definition of concept and essence of positioning – consumer, process, image and complex are allocated. Authors, adhering to an integrated approach, give own definition to the specified concept, allocate the main signs of positioning, draw conclusions about the further directions of development of the theory and practice of positioning

On F-term contribution to effective action

We apply equivariant integration technique, developed in the context of instanton counting, to two dimensional N=2 supersymmetric Yang-Mills models. Twisted superpotential for U(N) model is computed. Connections to the four dimensional case are discussed. Also we make some comments about the eight dimensional model which manifests similar features.Comment: 31 page

Extended Seiberg-Witten Theory and Integrable Hierarchy

The prepotential of the effective N=2 super-Yang-Mills theory perturbed in the ultraviolet by the descendents of the single-trace chiral operators is shown to be a particular tau-function of the quasiclassical Toda hierarchy. In the case of noncommutative U(1) theory (or U(N) theory with 2N-2 fundamental hypermultiplets at the appropriate locus of the moduli space of vacua) or a theory on a single fractional D3 brane at the ADE singularity the hierarchy is the dispersionless Toda chain. We present its explicit solutions. Our results generalize the limit shape analysis of Logan-Schepp and Vershik-Kerov, support the prior work hep-th/0302191 which established the equivalence of these N=2 theories with the topological A string on CP^1 and clarify the origin of the Eguchi-Yang matrix integral. In the higher rank case we find an appropriate variant of the quasiclassical tau-function, show how the Seiberg-Witten curve is deformed by Toda flows, and fix the contact term ambiguity.Comment: 49 page

A combinatorial smoothness criterion for spherical varieties

We suggest a combinatorial criterion for the smoothness of an arbitrary spherical variety using the classification of multiplicity-free spaces, generalizing an earlier result of Camus for spherical varieties of type $A$.Comment: 14 pages, 2 table

Matone's Relation in the Presence of Gravitational Couplings

The prepotential in N=2 SUSY Yang-Mills theories enjoys remarkable properties. One of the most interesting is its relation to the coordinate on the quantum moduli space $u=$ that results into recursion equations for the coefficients of the prepotential due to instantons. In this work we show, with an explicit multi-instanton computation, that this relation holds true at arbitrary winding numbers. Even more interestingly we show that its validity extends to the case in which gravitational corrections are taken into account if the correlators are suitably modified. These results apply also to the cases in which matter in the fundamental and in the adjoint is included. We also check that the expressions we find satisfy the chiral ring relations for the gauge case and compute the first gravitational correction.Comment: 21 page

Target space symmetries in topological theories I

We study realization of the target space diffeomorphisms in the type $C$ topological string. We found that the charges, which generate transformations of the boundary observables, form an algebra, which differs from that of bulk charges by the contribution of the bubbled disks. We discuss applications to noncommutative field theories.Comment: 22pp, one picture; refs added, typos correcte

Deformation of Super Yang-Mills Theories in R-R 3-form Background

We study deformation of N=2 and N=4 super Yang-Mills theories, which are obtained as the low-energy effective theories on the (fractional) D3-branes in the presence of constant Ramond-Ramond 3-form background. We calculate the Lagrangian at the second order in the deformation parameter from open string disk amplitudes. In N=4 case we find that all supersymmetries are broken for generic deformation parameter but part of supersymmetries are unbroken for special case. We also find that classical vacua admit fuzzy sphere configuration. In N=2 case we determine the deformed supersymmetries. We rewrite the deformed Lagrangians in terms of N=1 superspace, where the deformation is interpreted as that of coupling constants.Comment: v2: reference added, v3: published version in JHE

N=1 Superpotentials from Multi-Instanton Calculus

In this paper we compute gaugino and scalar condensates in N=1 supersymmetric gauge theories with and without massive adjoint matter, using localization formulae over the multi--instanton moduli space. Furthermore we compute the chiral ring relations among the correlators of the $N=1^*$ theory and check this result against the multi-instanton computation finding agreement.Comment: 31 pages, uses youngtab.sty, some explanations added, version to appear in JHE