Building a mathematical model of technological processes in the acetic acid synthesis reactor

The result of the study reported in this paper is the proposed mathematical model of technological processes occurring in the reactor for acetic acid synthesis. The initial parameters of the reactor considered were the value of the concentration of acetic acid at the reactor outlet, temperature, the level of reaction mass, and pressure in the reactor. The input parameters included the amount of methanol and carbon monoxide supplied. Material and thermal balances of reactor technological processes were used to construct the mathematical model of the reactor. Fisher criterion was applied to test the mathematical model for adequacy. At the specified 5 % level of significance, the value of Fisher criterion for the concentration of acetic acid, temperature, and the level of reaction mass in the reactor does not exceed its critical value for a stationary mode. The reproducibility of the modeling results was tested using the Cochran criterion. The value of the Cochrane criterion, at the predefined 5 % level of significance, for the concentration of acetic acid, temperature, and the level of reaction mass in the reactor does not exceed its critical value for different modes. The relative error for the modeled output parameters was calculated. The relative error of the initial parameters did not exceed the level of 10 %. The model built makes it possible to calculate with satisfactory accuracy the value of the concentration of acetic acid at the reactor output, the temperature and level of the reaction mass in the reactor under a stationary mode. The resulting model could be used to automate the control of technological processes in the acetic acid synthesis reactor under a stationary mode. The study results open additional opportunities to manage the stationary mode of the reactor

Using the Stochastic Gradient Descent Optimization Algorithm on Estimating of Reactivity Ratios

This paper describes an improved method of calculating reactivity ratios by applying the neuronal networks optimization algorithm, named gradient descent. The presented method is integral and has been compared to the following existing methods: Fineman–Ross, Tidwell–Mortimer, Kelen–Tüdös, extended Kelen–Tüdös and Error in Variable Methods. A comparison of the reactivity ratios that obtained different levels of conversions was made based on the Fisher criterion. The new calculation method for reactivity ratios shows better results than these other methods.

Feature Selection of the Rich Model Based on the Correlation of Feature Components

Currently, the popular Rich Model steganalysis features usually contain a large number of redundant feature components which may bring “curse of dimensionality” and large computation cost, but the existing feature selection methods are difficult to effectively reduce the dimensionality when there are many strongly correlated effective feature components. This paper proposes a novel selection method for Rich Model steganalysis features. First, the separability of each feature component in the submodels of Rich Model is measured based on the Fisher criterion, and the feature components are sorted in the descending order based on the separability. Second, the correlation coefficient between any two feature components in each submodel is calculated, and feature selection is performed according to the Fisher value of each component and the correlation coefficients. Finally, the selected submodels are combined as the final steganalysis feature. The results show that the proposed feature selection method can effectively reduce the dimensionalities of JPEG domain and spatial domain Rich Model steganalysis features without affecting the detection accuracies.

MECHANICAL TREATMENT'S STABILITY QUANTITATIVE ASSESSMENT

The ambivalence of the content of the term «stability» of machining processes in the transition to the construction of digital production is established based on the analysis of regulatory and technical documentation regulating the issues of product quality management in mechanical engineering. It is shown that the Fisher criterion can be a quantitative assessment of the stability of processes that are in a state of statistical controllability.

Stability assessment methods of technological processes

Ensuring the stability of quality indicators and product accuracy in modern conditions requires not only classical production measures but also organizational arrangements, which deals with clarifying and modernizing the conceptual apparatus. The study analyzes the methods for assessing the stability of machining, established in the standard process documents regulating the issues of product quality management in mechanical engineering, and reveals the ambiguity of the term ‘stability’ relating to processes under transition to the arrangement of digital production and the use of equipment with adaptive control. The Fisher criterion can be used for quantitatively analyzing the stability of processes under statistical control.

Аnalysis of the epidemiological situation and perinatal HIV infection in the Vologda region

Purpose. To analyze the epidemiological situation and perinatal HIV infection in the Vologda region.Materials and methods. The article provides a retrospective and prospective analysis of data obtained from the forms of state statistical observation and accounting forms of medical documentation, using the Chi-square calculator, Fisher criterion, risk ratio to assess the effectiveness of measures to prevent perinatal HIV transmission in the Vologda region.The results of the study showed that the detection of HIV infection during pregnancy in the Vologda region tends to increase. At the same time, there are still problems such as adherence to dispensary monitoring and treatment in women who have drug dependence, which requires further improvement of the legal framework and clear implementation of approved algorithms by medical professionals.