The representations of the Hubbard algebra in terms of spin-fermion operators and motion of a hole in an antiferromagnetic state

The representation of the Hubbard operators in terms of the spin$-\frac{1}{2}$ operators and the fermion operator with spin$-\frac{1}{2}$ is proposed. In the low-energy limit this representation is reduced to the representation following from the Hubbard diagramm technique. In framework of this approach motion of a hole in an antiferromagnetic state of the t-J model is considered. It is shown that the primary hole energy is strongly renormalized and the band width has an order of J rather than t. The functional integral for the strongly correlated model induced by the obtained representation is formulated. The representation of the total Hubbard algebra for states in the lower and the upper Hubbard bands is formulated in terms of the spin$-\frac{1}{2}$ and two fermion fields with spin$-\frac{1}{2}$ is formulated.Comment: 12 pp. (LATEX

Heat Transport in Spin Chains with Weak Spin-Phonon Coupling

The heat transport in a system of $S=1/2$ large-$J$ Heisenberg spin chains, describing closely Sr$_2$CuO$_3$ and SrCuO$_2$ cuprates, is studied theoretically at $T\ll J$ by considering interactions of the bosonized spin excitations with optical phonons and defects. Treating rigorously the multi-boson processes, we derive a microscopic spin-phonon scattering rate that adheres to an intuitive picture of phonons acting as thermally populated defects for the fast spin excitations. The mean-free path of the latter exhibits a distinctive $T$-dependence reflecting a critical nature of spin chains and gives a close description of experiments. By the naturalness criterion of realistically small spin-phonon interaction, our approach stands out from previous considerations that require large coupling constants to explain the data and thus imply a spin-Peierls transition, absent in real materials.Comment: 5+ pages main text, 4+ pages supplemental, 4+2 figures, adiabatic approximation to the published versio

Use of Articulated Transport Systems in the Mining Industry

The work is devoted to the possibility and prospects of the use of all-wheels drive articulated transport systems in the mining complex. A comparative analysis of the traditional methods of exporting minerals in open pit mining and the method of using active trailed elements are given. The trailer has a load factor several times higher than the same rate for mining dump trucks. The use of an active trailer makes it possible to reduce the mass of the tractor and trailer by almost 40 tons and increase the specific power of the road train. © Published under licence by IOP Publishing Ltd

N 3-[(E)-Morpholin-4-yl­methyl­idene]-1-phenyl-1H-1,2,4-triazole-3,5-diamine monohydrate

In the title compound, C13H16N6O·H2O, the mean planes of the benzene and 1,2,4-triazole rings form a dihedral angle of 54.80 (5)°. The N atom of the amino group adopts a trigonal–pyramidal configuration. Conjugation in the amidine N=C—N fragment results in sufficient shortening of the formal single bond. In the crystal, inter­molecular N—H⋯O and O—H⋯N hydrogen bonds link mol­ecules into double layers parallel to the bc plane

ANALYSIS OF STRATEGIC PRIORITIES FOR FORMATION OF FINANCIAL DIAGNOSTICS OF MACHINE-BUILDING ENTERPRISES

Introduction. The article suggests the use of matrix methods of strategic analysis to determine the state and prospects of the development of machine-building enterprises in Ukraine. Purpose. Analysis of the factors of influence both external and internal environment in order to establish strategic priorities for the formation of financial diagnostics of machine-building enterprises. Result. The analysis of innovation activity of machine-building enterprises is carried out. It’s been generalized internal and external factors of influence on activity of innovative active machine-building enterprises by SWOT-analysis. The experts evaluated separately the disadvantages and advantages, as well as the strengths and weaknesses that are the main factors in shaping the system of financial diagnostics of machine-building enterprises. According to the SWOT-analysis of the formation of the financial diagnostics system of machine-building enterprises, the main priority directions of the implementation of financial diagnostics are highlighted. The stages of the analysis of priorities at the formation of the system of financial diagnostics of machine-building enterprises are offered. It is proposed to evaluate and form clusters on the basis of financial indicators of the enterprises reflecting the influence of all factors, both external and internal environment, with the purpose of forming a system of financial diagnostics of machine-building enterprises. The analysis of indicators was conducted on the basis of 22 enterprises of the machine-building industry. 4 clusters of machine building enterprises are allocated. The criterion for clustering quality is the correlation between group and intra cluster variance. Studies show that only on the basis of a timely and reliable assessment of the financial state there is the possibility of developing and adopting sound management decisions. Conclusions. The results of research should become the basis for supporting innovative machine-building enterprises, which determine the need for further research and development in order to improve the theory and practice of financial diagnostics of machine-building enterprises