Synthesis of 2-acylmethyl- and 2-acylmethylenebenzo-1,3-dithioles from α-alkynyl ketones

The reaction of -alkynyl ketones with o-phenylenedithiol, which leads to the formation of 2-acylmethylbenzo-1,3-dithioles, was investigated. Reactions of the latter with hydrazine hydrate and hydroxylamine and oxidation were realized. Difficult-to-obtain 2-acylmethylenebenzo-1,3-dithioles were obtained by the reaction of -bromoalkynyl ketones with o-phenylenedithiol. The IR and PMR spectra of the synthesized compounds are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 329–332, March, 1981.     

Synthesis of 1,5-diaryl-3-tetrazolylformazans

Several 1,5-diphenyl-3-tetrazolylformazans were synthesized by reaction of 1,5-diaryl-3-cyanoformazans with sodium azide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1679–1681, December, 1977.     

Reactions of 1,3-dibromopropyne with 1-aroyl-2,2-dimethylhydrazines as a new method for the synthesis of substituted 1,3,4-oxadiazinium bromides

Reactions of 1-aroyl-2,2-dimethylhydrazines with 1,3-dibromopropyne in MeOH or MeCN at 20—50 °C yield 2-aryl-6-bromomethylidene-4,4-dimethyl-5H-1,3,4-oxadiazinium bromides.     

Basic relations of the theory of thermoviscoelastic plates with distributed sensors

The basic relations of the thermomechanics of thin-walled viscoelastic plates with distributed piezoelectric sensors under monogarmonic mechanical loading are presented. To describe the thermomechanical behavior of materials, the concept of complex characteristics is used. Numerical and variational methods are used to study the forced resonant vibrations of viscoelastic plates with distributed piezoelectric sensors. The effect of dissipative heating on the readings of the sensors of a circular viscoelastic plate undergoing axisymmetric resonant bending vibrations is analyzed as an example     

Parametric Vibrations of a Three-Layer Conical Piezoshell

Based on the Kirchhoff-Love hypotheses and adequate supplementary hypotheses for the distribution of electric field quantities, a model for parametric vibrations of composite shells of revolution made of a passive (without a piezoeffect) middle layer and two active (with a piezoeffect) surface layers under the action of harmonic mechanical and electric loads is developed. The dissipative material properties are taken into account by linear viscoelastic models. Since the vibrations on the boundary of the main domain of dynamic instability (MDDI) are harmonic, the investigation of this domain, in a first approximation, is reduced to generalized eigenvalue problems, which are solved by the finite-element method. The problem on parametric vibrations of a three-layer conical shell under harmonic mechanical loading is considered. The influence of the shell thickness, dissipation, and electric boundary conditions on the MDDI is investigated. Two limiting cases of electric boundary conditions are considered, where the electrodes are short-circuited or not. The curves presented show a considerable influence of the electric boundary conditions on the characteristics of the MDDI, namely on its width and position on the frequency axis and on the critical parameter of excitation.     

Reaction of methyl propiolate with thiosemicarbazones

Methyl propiolate reacts with thiosemicarbazones in methanol in the presence of triethylamine to give 2-benzylidene(thenylidene, or furfurlidene)azino-3H-1,3-thiazin-4-ones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 123–125, January, 1988.     

Influence of the temperature of dissipative heating on the damping of forced resonance vibrations of a simply supported viscoelastic cylindrical panel with the help of piezoelectric actuators

We consider the problem of active damping of the forced resonance vibrations of a viscoelastic cylindrical panel with the help of piezoelectric actuators. The end faces of the panel are assumed to be simply supported and heat-insulated. An analytical solution of the problem of electromechanics is obtained. On this basis, the dissipative function is calculated, and the energy equation is solved. We also analyze the influence of the temperature of dissipative heating on the efficiency of active damping of the forced vibrations of a cylindrical panel.     

Active damping of vibrations of plates subject to unknown pressure

An approach to the active damping of the forced resonant vibrations of orthotropic thermoviscoelastic plates with distributed sensors and actuators is proposed. The mechanical load is assumed unknown and is determined from the sensors’ indications. The problem of active damping of an isotropic thermoviscoelastic rectangular plate with hinged edges is solved as an example. A formula for the voltage to be applied to the actuator to damp the forced vibrations in the first mode is derived. The effect of the dimensions of the sensor and actuator and the dissipative properties of the materials on the effectiveness of active damping is studied