Lagrangian and Eulerian velocity structure functions in hydrodynamic turbulence

The Lagrangian and Eulerian transversal velocity structure functions of fully developed fluid turbulence are found basing on the Navier-Stokes equation. The structure functions are shown to obey the scaling relations inside the inertial range. The scaling exponents are calculated analytically without using dimensional considerations. The obtained values are in a very good agreement with recent numerical and experimental data.Comment: 4 pages, 1 figur

Dielectric properties of silicon nitride ceramics produced by free sintering

The silicon nitride ceramics with a beneficial combination of low dielectric losses and improved physical properties was fabricated by cold isostatic pressing and pressureless sintering. The fine grain microstructure, three-phase composition based on the β-SiAlON, the small amount of the glass phase and relatively small porosity promote a unique combination of a low thermal conductivity 14.51 W m¯¹ K¯¹ and low dielectric loss 1.4·10¯¯³. A novel method is proposed to overcome the main drawbacks of the commercial and high-cost technologie

Microstructure and phase composition of cold Isostatically pressed and pressureless sintered silicon nitride

The microstructure and physical properties of new Y₂O₃ and Al₂O₃ oxide-doped silicon nitride ceramics fabricated by cold isostatic pressing and free sintering were investigated. The phase composition of produced material was also studied by X-ray diffraction at room and elevated temperature. The fabricated ceramics featured a microstructure of Si₅AlON₇ grains with a fine-grained α-Si₃N₄ with a small amount of Y₂SiAlON₅. Described ceramics is attractive for many high-temperature structural applications due to beneficial combination of fine-grained structure with improved mechanical properties and small weight los