Tomsk Polytechnic University

About: Tomsk Polytechnic University is a education organization based out in Tomsk, Russia. It is known for research contribution in the topics: Combustion & Ignition system. The organization has 9190 authors who have published 13224 publications receiving 103735 citations.

Surface alloying of stainless steel 316 with copper using pulsed electron-beam melting of film–substrate system

Abstract: The surface morphology, chemical composition, microstructure, nanohardness, and tribological properties of a film (Cu)–substrate (stainless steel 316) system subjected to pulsed melting with a low-energy (20–30 keV), high-current electron beam (2–3 μs, 2.8–8.4 J/cm 2 ) have been investigated. The film was deposited by sputtering a Cu target in the Ar plasma of a microwave discharge. To prevent the local delamination of the film due to the cratering, the substrates were repeatedly pre-irradiated with 8–10 J/cm 2 . Single pulsed melting of this system resulted in the formation of a diffusion layer of thickness 120–170 nm near the interface, irrespective of the energy density. The layer has the subgrain structure consisting of the γ-Fe-solid solution and submicrometer or nanocrystalline Cu particles. The nanohardness and the wear resistance of the surface layer of thickness 0.5–1 μm, including the molten film and the diffusion layer, non-monotonically vary with energy density, reaching a maximum in the range of 4.3–6.3 J/cm 2 . As the pulse number is increased to five in the same range of energy density, the film dissolves in the substrate, and a ∼2-μm-thick surface layer is formed which contains ∼20 at.% Cu. Under these conditions, the segregation of Cu during resolidification leads to the formation of two-phase nanocrystalline layers separating γ-phase grains.

Model-Independent Study of Structure in B+ →d+D-K+ Decays

Abstract: The only anticipated resonant contributions to $B^+\to D^+D^-K^+$ decays are charmonium states in the $D^+D^-$ channel. A model-independent analysis, using LHCb proton-proton collision data taken at centre-of-mass energies of $\sqrt{s}=7,8,$ and $13$ TeV, corresponding to a total integrated luminosity of 9 fb$^{-1}$, is carried out to test this hypothesis. The description of the data assuming that resonances only manifest in decays to the $D^+D^-$ pair is shown to be incomplete. This constitutes evidence for a new contribution to the decay, potentially one or more new charm-strange resonances in the $D^-K^+$ channel with masses around 2.9 GeV$/c^2$.

Measurement of differential cross sections for the production of top quark pairs and of additional jets in lepton + jets events from p p collisions at s = 13 TeV

Abstract: Differential and double-differential cross sections for the production of top quark pairs in proton-proton collisions at root s = 13 TeV are measured as a function of kinematic variables of the top quarks and the top quark- antiquark (t (t) over bar) system. In addition, kinematic variables and multiplicities of jets associated with the t (t) over bar production are measured. This analysis is based on data collected by the CMS experiment at the LHC in 2016 corresponding to an integrated luminosity of 35.8 fb(-1). The measurements are performed in the lepton + jets decay channels with a single muon or electron and jets in the final state. The differential cross sections are presented at the particle level, within a phase space close to the experimental acceptance, and at the parton level in the full phase space. The results are compared to several standard model predictions that use different methods and approximations. The kinematic variables of the top quarks and the t (t) over bar system are reasonably described in general, though none predict all the measured distributions. In particular, the transverse momentum distribution of the top quarks is more steeply falling than predicted. The kinematic distributions and multiplicities of jets are adequately modeled by certain combinations of next-to-leading-order calculations and parton shower models.