Pressure fluctuations within a turbulent gas flow and their interaction with a shock wave

The interaction of a shock wave with a turbulent air flow is investigated experimentally. The turbulence was created with the aid of a grid. On its reflection from a perforated disc the wave propagated through a turbulent flow. The Mach number of the incident shock was equal to 1.9–4, the Mach number of the reflected wave was equal to 1.6–2.5. We found the autocorrelation functions of pressure fluctuations and their phase diagrams. The turbulent length scale of pressure fluctuations behind the incident shock was determined. The appropriate quantity behind the reflected wave is less of an order as compared with the previous case. It is established that the pressure behind the reflected wave in the turbulent flow is 7–8% higher as compared with the pressure in the laminar flow, if other conditions are the same.     

Dependence of Synthetic Diamond Wear Rate on Lattice Orientation at Traditional Mechanical Treatment

The results of comparative studies of the rate of mechanical polishing of the surface of synthetic diamond in various directions and different crystallographic surface orientations are presented. A free abrasive on a cast-iron disk is used for polishing. A method is proposed for numerical simulation of the polishing of an arbitrarily oriented diamond surface, based on an estimation of changes in the internal energy of the diamond crystal lattice under the action of the abrasive. The method enables determination of the direction of polishing, which ensures the maximum processing rate of a diamond surface of any crystallographic orientation. The validity of the proposed method is confirmed experimentally.     

Addition of halogenoacetic esters to aldehydes and ketones in the presence of Fe(CO)5

The use of complex-forming solvents and variations in the reaction temperature made it possible to prepare α-halogeno β-hydroxy carboxylic esters upon addition of halogenoacetic esters to aldehydes and ketones promoted by iron pentacarbonyl. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 718–720, April, 2000.     

Computer calculations for thermal behavior of Na<Subscript>2</Subscript>CO<Subscript>3</Subscript>-Li<Subscript>2</Subscript>CO<Subscript>3</Subscript> melt

The thermal behavior of Na₂CO₃+Li₂CO₃ melt is studied by the method of thermodynamic simulation. The equilibrium compositions of the gas and salt phases are calculated at different temperatures in the initial argon atmosphere. Basic trends of the variation in the compositions of the melts and the gas phase above the melts in the presence of carbon are determined. The obtained results characterizing the stability of carbonate components in the melt are analyzed.     

On Modal Interaction,Stability and Nonlinear Dynamics of a Model Two D.O.F. Mechanical System Performing Snap-Through Motion

Dynamics of a simple two degrees of freedom (d.o.f.) mechanical system is considered, to illustrate the phenomena of modal interaction. The system has a natural symmetry of shape and is subjected to symmetric loading. Two stable equilibrium configurations are separated by an unstable one, so that the model system can perform cross-well oscillations. Nonlinear statics and dynamics are considered, with the emphasis on detecting conditions for instability of symmetric configurations and analysis of bi-modal non-symmetric motions. Nonlinear local dynamics is analyzed by multiple scales method. Direct numerical integration of original equations of motions is carried out to validate analysis of modulation equations. In global dynamics (analysis of cross-well oscillations) Lyapunov exponents are used to estimate qualitatively a type of motion exhibited by the mechanical system. Modal interactions are demonstrated both in the local dynamics and for snap-through oscillations, including chaotic motions. This mechanical system may be looked upon as a lumped parameters model of continuous elastic structures (spherical segments, cylindrical panels, buckled plates, etc.). Analyses performed in the paper qualitatively describe complicated phenomena in local and global dynamics of original structures.     

Specific mass increment and nonequilibrium crystal growth

Unsteady nonequilibrium crystallization of ammonium chloride from an aqueous solution resulting in the formation of irregular, so-called seaweed, structures is experimentally investigated. It is shown that specific increment of mass for the coexisting structures (or parts thereof) is the same and changes with time (t)$\left(t\right)$ according to the power law a/t−b$a/t-b$, where the factor a=1.87±0.09$a=1.87\pm 0.09$ and the factor b$b$ is determined by the system relaxation time. The normalization of the power law to the total time of structure growth allows obtaining a universal law that describes the specific mass increment with time for both seaweed and dendrite structures (including the non-coexisting ones).     

Reaction of 3-benzoyl-1-methyl-4-phenyl-γ-piperidol with arylamines and arylhydrazines. Synthesis of 3-arylamino-1-oxo-1-phenylpropanes and 1,3 diarylpyrazoles and their fragmentation under electron impact

Upon heating in the presence of arylamines 3-benzoyl-4-hydroxy-1-methyl-4-phenylpiperidine decyclizes via a retroaldol type reaction with subsequent transamination of the intermediate Mannich base to give 3-arylamino-1-oxo-1-phenylpropanes. In the case of the use of arylhydrazines this γ-piperidol recyclizes to give 1,3-diarylpyrazoles and their 4,5-dihydro derivatives. The mass spectroscopic behavior of a series of 3-arylamino-substituted 1-phenylpropanones has been studied. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 544–554, April, 2007.