ATLAS sensitivity range for the x_s measurement

Previous results for the prospects of B_s mixing measurement in the ATLAS experiment at LHC are updated. The improved analysis method of the studied decay channels B_s -> D_s pi and B_s -> D_s a_1, combined with most recent values for the branching ratios and the B_s lifetime, leads to the new ATLAS sensitivity range for the x_s measurement: x_s^{max} = 42. An extensive study is done in order to estimate how x_s^{max} is influenced by the B-decay proper-time resolution of the vertex detector, as well as by the number of events and by the signal-to-background ratio.Comment: 17 pages, incl. 12 figure

Bs0→Ds−a1+(Ds−→ϕπ−,Ds−→K∗0K−)B_s^0 \to D_s^-a_1^+(D_s^- \to \phi \pi^-, D_s^- \to K^{*0}K^-) decay channel in the ATLAS Bs0B_s^0-mixing studies

It is shown, using a track-level simulation, that the use of the $D_s^- \to K^{*0}K^-$ decay channel for $D_s^-$ reconstruction, in additioon with the previously studied $D_s^- \to \phi \pi^-$ mode, enables two fold gain in the ATLAS $B_s^0$-mixing signal statistics through $B_s^0 \to D_s^-a_1$ $B_s^0$-decay channel. A new modification of the amplitude fit method is suggested for the $x_s$ determination. Some general aspects of the $B_s^0$-mixing phenomenon is illustrated by pictures of Casimir Malevich, Maurits Cornelis Escher and Salvador Dali.Comment: 23 pages, LaTex, 7 figures and 4 picture

Scaling Invariance of Fatigue Crack Growth in Gigacycle Loading Regime

The role of the collective behavior of defect ensembles at the crack tip and the laws of fatigue crack propagation in R4 high strength steel have been studied under conditions of symmetric tension–compression gigacycle loading at 20 kHz. At every stage of the fatigue crack growth, replicas from the sample side surface were taken and studied by the method of three dimensional relief profilometry (using NewView interferometer profilometer) so as to study the scaling invariant laws of defect related structure evolution.This study was supported in part by the Russian Foundation for Basic Research, Project nos. 08-01-00699, 09-01-92005-NNS_a, and 09-01-92441-KE-

Infrared thermography study of the fatigue crack propagation

The work is devoted to the experimental study of heat dissipation process caused by fatigue crack propagation. To investigate a spatial and time temperature evolution at the crack tip set of experiments was carried out using specimens with pre-grown centered fatigue crack. An original mathematical algorithm for experimental data treatment was developed to obtain a power of heat source caused by plastic deformation at crack tip. The algorithm includes spatial-time filtration and relative motion compensation procedures. Based on the results of mathematical data treatment, we proposed a way to estimate the values of J-integral and stress intensity factor for cracks with pronounced the plastic zone

EFFECTIVENESS EVALUATION OF STEEL STRENGTH IMPROVEMENT FOR PYRAMIDAL-PRISMATIC BUNKERS

In accordance with the recommendations of specialized professional literature, steel pyramidal-prismatic bunkers are projected for a service life of 20 years. However, in practice this term is often twice, or even three times lower. This is especially true for complicated operating conditions, in particular the effect of increased loads and low temperatures. Existing design techniques for such structures, both in European practice and the design practice of Ukraine and other CIS countries do not pay attention to these aspects. Therefore, in the practice of operation, the increased accident rate of steel bunker capacities has already become virtually a common occurrence.One of the possible ways to solve this problem is presented, which consists of using instead of traditional steels of ordinary strength with high plastic properties, steels of increased or high strength with reduced plastic properties. At the same time, clear theoretical recommendations are provided for choosing the right steel depending on the operating conditions, primarily when exposed to increased loads. The recommendations are presented in a form convenient for practical engineering applications.The proposed approach allows to reduce the material consumption of structures of this type on average according to theoretical estimates by 25-30% without reducing their bearing capacity. Their durability is also further enhanced by improving performance at low temperatures. Thus, the applied aspect of such a solution to this above problem is the possibility of increasing the overall reliability of steel bunker capacities, as well as reducing the cost of their periodic maintenance and repair work.A practical illustration of the presented approach is also given on the example of the design of bunkers of a bypass track for supplying charge materials for blast furnaces of one of the metallurgical plants of the northern location. As a result, this created the preconditions for monetary savings of about 0.5 million UAH in prices 2019 (about 20,000 USD