Obtaining cyclopentanone from acidic wastewater of caprolactam production

It has been shown that adipic acid released from the by-products of caprolactam production is a promising raw material for the production of cyclopentanone. The thermal stability of calcium adipate was investigated by the derivatographic method and the conditions were selected that ensure the yield of at least 50% of the target cyclopentanone with a purity of at least 99%

Stress-strain state and stability of composite sandwich shells with a scaling zone between the core and facings

A finite element model is presented for analysing the strength and stability of sandwich shells of arbitrary configuration with an adhesion failure zone between the core and one of the facings. The model is based on the following assumptions: both facings are laminated Timoshenko-type composite shells; in the core only transverse shear stresses and normal stresses in the thickness direction have non-zero values; in the adhesion failure zone a free slip in the tangential plane, and a unilateral contact along the normal are possible; in the stability problem the prebuckling state is assumed to be linear. Displacements and rotation angles of the normals towards the facings, as well as stresses in the core are taken as global degrees of freedom. The algebraic problem is solved by using a special step-by-step procedure of determining the contract area in the scaling zone and employing unilateral restrictions to some of the unknowns. Numerical examples are also given

Stress-strain state and stability of composite sandwich shells with a scaling zone between the core and facings

A finite element model is presented for analyzing the strength and stability of sandwich shells of arbitrary configuration with an adhesion failure zone between the core and one of the facings. The model is based on the assumptions that both facings are laminated Timoshenko-type composite shells, only transverse shear stresses in the core and normal stresses in the thickness direction have nonzero values, a free slip in the tangential plane in the adhesion failure zone and unilateral contact along the normal are possible, and the prebuckling state in the stability problem is linear. Biquadratic nine-node approximations for all functions and numerical integration were used. The displacements and rotation angles of the normals toward the facings as well as stresses in the core are taken as global degrees of freedom. The algebraic problem is solved using a special step-by-step procedure of determining the contact area in the scaling zone and employing unilateral constraints for some of the unknowns. Numerical examples are also given. © 1994 Plenum Publishing Corporation

Numerical analysis method for studying local forms of stability loss of bearing layers of three-layered shells using mixed forms

A revised formulation of linearized stability problems of three-layered shells with a sofi filler has been presented. The form of stability loss of the rigid layers is mixed in the shells when the moment precritical stress-strain state (SSS) is reached and is localized in the principal moment SSS zones. If the filler thickness is much greater than the thickness of the rigid layers, the size of the bulges and thickness of the filler have the same order of magnitude. Thus, a very fine grid must be used for a numerical solution of the stability loss equations, which poses considerable computational difficulties. A numerical analysis method is proposed for the local forms of mixed mode stability loss of the rigid layers of a three-layered shell. Using this method, the solution of equations for the precritical SSS by the finite element scheme is found but an analytical solution of reduced stability loss equations is presented for estimating the critical load. This solution is an asymptotic approximation for local modes of stability loss implemented into design. © 1995 Plenum Publishing Corporation

Combined algorithm of the realization of the method of least modules.

The methods of software realization of the approximate method of calculating the estimates of the smallest modules (the Mudrov method), the combined method of variational-weighted quadratic approximations and coordinate-wise descent, and the method of search for estimating the coefficients of linear regression models are considered. Based on the results of the study, it was found that the root-mean-square deviation in calculating the coefficients of the linear function y (x) = kx + b in the combined method is less than in calculating the coefficients by the Mudrov method.Рассмотрены способы программной реализации приближенного метода вычисления оценок наименьших модулей (метода Мудрова), комбинированного метода вариационно-взвешенных квадратичных приближений и покоординатного спуска и метода перебора для оценивания коэффициентов линейных регрессионных моделей. По результатам исследования выявлено, что среднеквадратичное отклонение при вычислении коэффициентов линейной функции y(x)=kx+b+ε в комбинированном методе меньше, чем при вычислении коэффициентов методом Мудрова

Stress analysis of helicopter main rotor torsion bar

The results of stress analysis for the main rotor torsion bar of the ANSAT helicopter based on the finite element method are presented. The analysis was performed for the base types of loading in the linear statement. The analysis results agree well with the experimental data. © Allerton Press, Inc., 2009

Tensor analyzing power Ayy in deuteron inclusive breakup at large Pt and spin structure of deuteron at short internucleonic distances

The Ayy data for deuteron inclusive breakup off hydrogen and carbon at a deuteron momentum of 9.0 GeV/c and large Pt of emitted protons are presented. The large values of Ayy independent of the target mass reflect the sensitivity of the data to the deuteron spin structure. The data obtained at fixed $x$ and plotted versus Pt clearly demonstrate the dependence of the deuteron spin structure at short internucleonic distances on two variables. The data are compared with the calculations using Paris, CD-Bonn and Karmanov's deuteron wave functions.Comment: 4 pages, 2 figures, talk given at the SPIN2004 Conf., 10-16 Oct. 2004, Triest, Ital

Obtaining cyclopentanone in the presence of metal oxides

Received: 01.12.2021. Revised: 13.12.2021. Accepted: 14.12.2021. Available online: 15.12.2021.The possibility of obtaining cyclopentanone by pyrolysis of calcium adipate at different temperatures was considered. The pyrolysis proceeded with the formation of cyclopentanone and cyclopentene. The use of metal salts and metal oxide catalysts for the dehydrogenation of lower alkanes makes it possible to increase the yields of the target products. The best results were achieved in the presence of a «K-16u» catalyst

OBTAINING CYCLOPENTANONE FROM ACIDIC WASTEWATER OF CAPROLACTAM PRODUCTION

The process of oxidation of cyclohexane with atmospheric oxygen, carried out as a separate stage in the production of caprolactam, is characterized by a large amount of oxygen-containing compounds, which are concentrated in acidic wastewater. One of these compounds is adipic acid. The resulting calcium salt of adipic acid decomposes during high-temperature processing to cyclopentanone. Cyclopentanone is an important intermediate in the production of insecticides, biologically active pharmaceuticals. Ketocyclopentane is an intermediate in the synthesis of jasmon. In the pharmaceutical industry it is a precursor in the production of cyclopentobarbital, which is a sedative. Cyclopentanone is also used to produce cyclopentamine, which is an intermediate in the synthesis of fungicides such as pencycuron. The solid concentrate of acidic wastewater was diazomethylated to obtain methyl esters of carboxylic acids