Mathematical Model Of Process Research Articles

Modeling of the conditions of the process of biotransformation of fish raw materials by bacterial starter cultures

Abstract In food biotechnology, special attention is given to the biotransformation by promising strains of bacterial starter cultures to obtain food products with improved quality characteristics and functional properties. Biotransformation using bacterial starter cultures may be a means to increase the shelf life of fish products, enhance their organoleptic properties, and increase their nutritional value through the formation of metabolites of their activity, which are the main factors of bioconservation and synthesis of vitamins and other biologically active substances. The probiotic properties of bacterial starter cultures will significantly influence the optimization of the indigenous microflora of the gastrointestinal tract, thereby strengthening the human body and its immune system overall to maintain a healthy lifestyle. The development of this trend is associated with the interest of the Russian population in products with a probiotic focus. In this regard, an analysis of data on the justification of the use of bacterial starter cultures for the biotransformation of fish raw materials has been conducted, and the necessary bacterial starter cultures have been selected. Based on theoretical and practical foundations, mathematical models of the biotransformation process by bacterial starter cultures have been constructed depending on the properties of fish raw materials and the biotechnological characteristics of the introduced microorganisms. The conducted research has been used to develop subsequent technological regimes for the biotransformation of fish raw materials by bacterial starter cultures as the basis for the formulations of “fast food” products containing functional components, which is justified by the accelerated pace of life and the desire of modern society to monitor their diet by consuming products that support a healthy lifestyle.

Оценка альтернатив: новые подходы принятия решений в условиях определенности

The decision-making process plays an important role in the development of society in general and the effective management of organizations in particular. In today's world, where the complexity of tasks and the competitive environment are constantly growing, making the right and informed decisions becomes a key element of success. Any person, group of people or organization is constantly faced with the need to choose between several possible courses of action, called alternatives, whether in the personal sphere or in the work of organizations. To effectively make complex decisions within the activities of organizations, models for making optimal decisions have been developed. The most popular of them is the model of decision-making under conditions of certainty, when the outcome of the decision is not influenced by random factors. All this confirms the relevance of scientific research in the field of decision making. Aim. The purpose of the study is to develop a methodology for assessing the degree of attractiveness of alternatives based on objective quantitative or subjective qualitative criteria, which will improve the quality of decisions made. The methodology is based on mathematical models for processing information containing the characteristics of alternatives according to evaluation criteria. Materials and methods. The methodology for evaluating alternatives presented in the work is based on mathematical models of information processing, which are based on methods of mathematical modeling, optimization methods, linear programming, theory of fuzzy sets, theory of latent variables, as well as methods of decision-making under conditions of uncertainty and methods of expert assessment. Results. The relevance of the development of a model for evalua¬ting construction projects according to quantitative criteria is shown, ways of solving the tasks are given and justified. A mathematical model has been developed that makes it possible to evaluate construction projects by objective indicators based on the theory of fuzzy sets and the Rush model for estimating latent variables. On the basis of numerical methods, the adequacy of the received estimates of construction projects is substantiated, the methodology for implementing computational procedures necessary for the practical implementation of evaluation models is described. Conclusion. The application of the given methodology in the decision-making procedure under conditions of certainty will improve the quality of decisions made and reduce the risks of their implementation.

Electrocoagulation process with Fe/Al electrodes to eliminate pollutants from real and synthetic wastewater

This work investigated the effect of a victorious parameter of electrocoagulation (EC) on the removal of turbidity through batch reactor using Fe and Al electrodes. Synthetic (Sol 1, Sol 2) and natural wastewater (Sol 3) with different sodium chloride content were examined under different current densities (CD) and operating time. For the examined solutions conductivity, pH, total suspended solids (TSS) dissolved oxygen (DO) and energy consumption were measured. A novel approach examined the effect of solutions with selected operating parameters on Fe and Al corrosion using chemical and electrochemical tests. Using experimental data collected during the various parameters, a mathematical model of the electrocoagulation process was generated and assessed. FE-SEM images and EDX analyses for Fe and Al electrodes and XRD of coagulant particles, floc, generated by EC were also investigated. According to the findings, the ideal circumstances for the turbidity elimination from the examined solution were found to be as CD = 11 mA/cm2, pH ⁓ 7, and operating time = 20 min. Under these optimal circumstances, Al electrodes showed superior efficacy in removing than Fe electrodes for all examined solutions. The turbidity removal efficiency and the energy consumption were also found to be affected by NaCl content. The turbidity removal efficiencies reached their maximum value of 99 % for sol 3 where NaCl content was 3.45 × 10−1 M and energy consumption was 1.667 kWh/m3 by using Al anode.

A method for predicting methane production from anaerobic digestion of kitchen waste under small sample conditions.

Anaerobic digestion (AD) has the great potential to treat organic waste and achieve remarkable results effectively. However, it is very tough to establish an accurate mechanistic model for this process. Data-driven modeling technology has opened a new door to solving this problem. While when the sample set is small, traditional data-driven modeling methods are often powerless. In this paper, an effective method is proposed for data-driven high-precision modeling in small sample scenarios. A time series generative adversarial network (TimeGAN) is first utilized to augment the original high-quality small-sample data collected during the AD methane production. A novel hybrid kernel extreme learning machine (HKELM) is then designed to form a better structure of the data-driven model, whose regularization coefficient C0 is optimized by the sparrow search algorithm (SSA). Finally, this semi-finished model (SSA-HKELM) is trained by the augmented data to form the final mathematical model (TimeGAN-SSA-HKELM) for the AD methane generation process. Comparative experiments of the methane daily production prediction error haveverified the effectiveness of the method, which can be extended to other similar small sample data-driven modeling scenarios.

Mathematical modeling of the flat ingot casting process or solving automation problems

Aluminum alloys are widely used in the production of aircraft due to their strength, lightness, corrosion resistance, and necessary electrical conductivity. At the same time, aluminum ingots used in further processing of the space industry must be of high quality. Technological problems and defects arise when temperature, speed, and other technological parameters of casting are not observed, or when modes change. At the same time, foundry processes are partially automated; the human factor significantly affects product quality and work safety. Therefore, automation of these complex processes using mathematical models to predict casting parameters is an urgent task. The goal of the work is to create mathematical models available for use in automated process control systems (APCS), as well as for the development of a digital twin. The work presents simplified formulas for modeling the temperature distribution of an aluminum ingot during the casting process, cooling the metal when moving along a metal path, and test calculations of the temperature distribution inside the ingot when the ingot reaches a fixed length. The results of this work can be used to improve the efficiency and accuracy of controlling the process of casting aluminum ingots, to eliminate emergency situations.

SIMULATION THE PROCESSES OF ORGANIC MATERIALS DESTRUCTION AND COMBUSTION PROCESSES CONDITION OF FIRE INTENSEICATION

Problem statement. The rapid occurrence and development of fires are caused by the occurrence of combustible materials and structures in their focus. This complicates, and in some cases makes impossible, effective firefighting, evacuation, and rescue of people and property. In order to correctly assess fire resistance, effectively increase fire resistance, and change the flammability of materials, it is necessary to study the materials burning process. The purpose of the article. To study of the combustion of easily dispersible substances and the development of gaseous reactions and their combination using the example of wood combustion. Methods. We use mathematical modeling of combustion and destructive processes under the high temperatures, taking into account the rules of thermodynamics. Research results. The conducted analysis showed that the selection of the main stages in the simulation of wood combustion is much less developed than in the case of the combustion of gas systems. It is especially difficult to do this to describe the combustion of wood, on the surface of which there is an interaction of masses (and heat) during the combustion of individual components, and the size of the front surface per unit cross-section of the sample may also change over time. Therefore, the definition of the main stage in wood burning should be used mainly in the qualitative analysis of the process, and quantitative models of wood burning should be built, if possible, taking into account all the determining factors characterizing the phenomena. Scientific novelty. For the first time, on the basis of the modeling of organic material combustion is proposed. We determine the patterns of destructive processes, which, depending on the temperature, have common patterns of qualitative and quantitative characteristics. The chemical phasing and its connection with the physical phasing of the transformation of combustible organic materials dispersed in the surface layer with the overall thermal effect of the combustion wave were determined. Practical value. The identification of stages during the wave burning of wood allows for a qualitative display of processes depending on the spatial zone and its distance from the gas zone, which allows predicting the development of protective means of organic materials against combustion.

Creating Fuzzy Models from Limited Data

The design of experiments is a methodological approach in which measurement experiments are carefully planned to obtain highly informative data. This paper addresses the challenge of constructing mathematical models for complex nonlinear processes when the available measurement data have low information content. This problem often arises when data are collected without the guidance of an experimental modeling expert. We examine two practical examples to illustrate this issue: a textile wastewater decolorization process and atmospheric corrosion of structural metal materials. In both cases, the measured data were insufficient to construct highly accurate models. It is, therefore, necessary to make a trade-off between model complexity and accuracy by adapting modeling techniques to work effectively with the limited data available. The main aim of the paper is, therefore, to focus on simple but effective techniques that allow as much information as possible to be extracted from low-quality measurements and to maximize the usefulness of the model for its intended purpose.

Improvement of mathematical model for catalytic reforming process with a stationary catalyst layer

Improvement of mathematical model for catalytic reforming process with a stationary catalyst layer

Mathematical Modeling of the Heat Transfer Process in Spherical Objects with Flat, Cylindrical and Spherical Defects

This paper proposes a method for determining the optimal parameters for the thermal testing of plant tissues of fruits and vegetables containing surface and subsurface defects in the form of areas of plant tissues with different thermophysical characteristics. Based on well-known mathematical models for objects of predominantly flat, cylindrical and spherical shapes containing flat, spherical and cylindrical regions of defects, numerical solutions of three-dimensional, non-stationary temperature fields were found, making it possible to measure the power and time of the thermal exposure of the sample surface to the radiation from infrared lamps using the finite element method. This made it possible to ensure the reliable detection of a temperature contrast of up to 4 °C between the defect and defect-free regions of the test object using modern thermal imaging cameras. In this case, subsurface defects can be detected at a depth of up to 3 mm from the surface. To determine the parameters of mathematical models of temperature fields, such as thermal conductivity and a coefficient of the thermal diffusivity of plant tissues, a new method of a pulsed heat flux from a flat heater is proposed; this differs in the method of processing experimental data and makes it possible to determine the required characteristics with high accuracy during the active stage of the experiment in a period not exceeding 1–3 min.

Mathematical modeling and performance evaluations of a wood drying process using photovoltaic thermal and double-pass solar air collectors

This research conducts a novel and complete 4E assessments and introduces an innovative method for examining solar wood drying systems. The software TRNSYS and MATLAB programming are combined to simulate and create a numerical program. This novel combination allows for a thorough examination that goes beyond conventional assessments of wood drying. The aim is to evaluate the effectiveness of a solar wood dryer using two different collectors, a double-pass and a photovoltaic thermal collectors, in terms of four key aspects: energy, exergy, economic, and environmental. Further, the drying process was investigated under various climates in three African cities (Errachidia, Dakar, and Nouakchott). The moisture content of wood was reduced from 74% to 12% in the three cities. Elaborate simulations were performed and the results were confirmed by experimental validation, using methods including Mean Absolute Error, Mean Relative Error, and Root Mean Square Error. The primary findings of this study are the following: In the double-pass dryer, the drying time required in Errachidia, Dakar, and Nouakchott was 139h, 189h, and 170h, respectively. Whereas in the photovoltaic thermal dryer, it needed 192h in Errachidia, 210h in Dakar, and 189h in Nouakchott. Further, using photovoltaic thermal, the dryer exhibited superior exergy efficiency compared to the use of double pass collector. Photovoltaic thermal collector reduces yearly CO2 emissions by an average of 54.87, 66.2, and 44.11 tonnesCO2 in Errachidia, Dakar, and Nouakchott, respectively. In contrast, double pass collector reduces CO2 emissions by an average of 38.49, 57.9, and 38.56 tonnesCO2 in Errachidia, Dakar, and Nouakchott, respectively, throughout the year. Further, the solar dryer, using double pass collector, has a shorter payback time than using photovoltaic thermal collector, indicating a quicker economic return.

Method of Identification of Combat Vehicles Based on Yolo

A method for recognizing contours of objects in a video data stream is proposed. Data will be uploaded using a video camera in real time and object recognition will be performed. We will use the YOLO network – a method of identifying and recognizing objects in real time. Recognized objects will be recorded in a video sequence showing the contours of the objects. The approach proposed in the project reasonably synthesizes methods of artificial intelligence, theories of computer vision on the one hand, and pattern recognition on the other; it makes it possible to obtain control influences and mathematical functions for decision-making at every moment of time with the possibility of analyzing the influence of external factors and forecasting the flow of processes, and refers to the fundamental problems of mathematical modeling of real processes. The installation of the neural network is shown in detail. The characteristics of the neural network are shown and its capabilities are substantiated. Approaches to computer vision for object extraction are shown. Well-known methods are methods of expanding areas, methods based on clustering, contour selection, and methods using a histogram. The work envisages building a system for rapid identification of combat vehicles based on the latest image filtering methods developed using deep learning methods. The time spent on identifying the machine will be 10 –20 % shorter, thanks to the developed new information technology for detecting objects in conditions of rapidly changing information.

К уточнению понятий «концепт» и «концептология» (Подсказка читателя)

The “concept” as a basis for the construction of the science “conceptology” is studied. The question of the concept structure, the language of its description and the possibility of using mathematics for this purpose is discussed. Conceptology is considered as a scientific understanding of political reality in interrelation with social and natural reality. The characteristics of the spaces related to the mentioned types of reality and peculiarities of their conjugation in the concept structure are analyzed. The reasons for the ineffectiveness of mathematical modeling of social processes in the era of 1970s and the chances of success of modern researchers are analyzed. It is concluded that it is possible to develop the science of politics to a level comparable in its rigor, clarity and accuracy of forecasting with physics or mathematics.

Аналіз впливу на прохідність автобронетанкової техніки конструктивних факторів та методика її збільшення шляхом автоматичного регулювання тиску повітря в шинах коліс

The purpose of the study is to analyze and determine the influence of various factors on the patency of armored vehicles (AMT) operated by the National Guard of Ukraine. Determination of the change in patency during the movement of AMT in different road and climatic conditions. Analysis of static and dynamic loads, which are characteristic of AMT movement over rough terrain, and their impact on the efficiency of the vehicle. The theoretical component of the study was carried out using mathematical modeling of the work process of regulating the air pressure in tires of AMT wheels, using the example of changes in the characteristics of adhesion coefficients with the supporting surface and rolling resistance depending on the change in pressure and load on the tires of the wheels when the AMT is moving off-road. As a result of mathematical modeling, the dependences of air pressure in tires of AMT wheels were obtained, depending on the coefficient of rolling resistance and the load on each of the wheels. Which, in turn, makes it possible to move to a sufficiently complete mathematical modeling of the movement of AMT on off-road, taking into account the reference cross-country ability. In the process of theoretical research, the structural parameters of the impact on the patency of AMT were analyzed quite completely, and a generalized comparative indicator of the patency parameters of vehicles was proposed. When analyzing it, it was found that the AMT tire and, specifically, the change in air pressure in it, have a significant impact on the bearing capacity. The authors propose to use the following evaluation criteria as criteria for assessing the efficiency of the passability when driving on deformable surfaces: a generalized comparative indicator of the parameters of the passability of vehicles. As a result of consideration of which, a significant influence on the patency parameters of the tires and directly the air pressure in them was established. Regulation and change of the air pressure in the tires of the wheels depending on the change in the coefficient of rolling resistance as well as the change in the load on each wheel, which are the ratio of the work that is spent on the traction force when overcoming different degrees of heaviness of the resistance of the supporting surfaces with the effect of deformation. And the load that falls on each of the AMT wheels allowed us to draw conclusions about the improvement of the regular tire pressure regulation system (RPRS) of the wheels.

THE AIRCRAFT ENGINE PROPELLER MAIN CHARACTERISTICS DETERMINATION IMPROVED METHOD

An improved method of the fixed and variable pitch propeller aerodynamic characteristics determining that based on the vortex theory is presented. It is shown that the design of propellers has it`s peculiarities, it does not take into account a number of factors that affect the propeller operation to one or another degree. This actualized the special purpose unmanned aerial vehicles engines propellers aerodynamic characteristics calculating methodology improvement. Since the use of the propeller profiles performances in the design requires the air compressibility correction introduction already after the selection of the propeller, that complicates the design, therefore the mathematical model of the variable-pitch propeller working process has been improved based on the profile model with the correct consideration of the Mach and Reynolds numbers influence on the aerodynamic characteristics of the air screw. This advantage of the developed airfoil model allows the design and verification of a subsonic propeller for ground and flight operations. Methods of design and verification calculations of propeller blades are presented. Verification of the improved methodology was carried out by comparing calculated data with known experimental data. The reliability of the improved aircraft engine propeller main performances determination methodology is substantiated by the correct application of the numerical and experimental methods of aerodynamics, the consistency of theoretical provisions with experimental data. The satisfactory coincidence of the calculated data obtained by the improved method of the engine propeller main performances determination allowed us to draw a conclusion concerning its efficiency. The improved technique for the main performances of an aircraft engine propeller determination does not require knowledge on the propeller profiles aerodynamic characteristics from which the blade is drawn, since these characteristics are calculated based on known geometric data, taking into account the Mach and Reynolds numbers. This allows you to design and build a subsonic propeller of both fixed pitch and variable pitch.

Analysis of the privacy-performance tradeoff of reference testing in Forensic Investigative Genetic Genealogy.

During an investigation using Forensic Investigative Genetic Genealogy, which is a novel approach for solving violent crimes and identifying human remains, reference testing-when law enforcement requests a DNA sample from a person in a partially constructed family tree-is sometimes used when an investigation has stalled. Because the people considered for a reference test have not opted in to allow law enforcement to use their DNA profile in this way, reference testing is viewed by many as an invasion of privacy and by some as unethical. We generalize an existing mathematical optimization model of the genealogy process by incorporating the option of reference testing. Using simulated versions of 17 DNA Doe Project cases, we find that reference testing can solve cases more quickly (although many reference tests are required to substantially hasten the investigative process), but only rarely (<1%) solves cases that cannot otherwise be solved. Through a mixture of mathematical and computational analysis, we find that the most desirable people to test are at the bottom of a path descending from an ancestral couple that is most likely to be related to the target. We also characterize the rare cases where reference testing is necessary for solving the case: when there is only one descending path from an ancestral couple, which precludes the possibility of identifying an intersection (e.g., marriage) between two descendants of two different ancestral couples.

A Physical Insight into Computational Fluid Dynamics and Heat Transfer

Mathematical equations that describe all physical processes are valid only under certain assumptions. One of them is the minimum scales used for the given description. In fact, this prohibits the use of derivatives in the mathematical models of the physical processes. This article represents a derivative-free approach for the mathematical modelling. The proposed approach for CFD and numerical heat transfer is based on the conservation and phenomenological laws, and physical constraints on the minimum problem-dependent spatial and temporal scales (for example, on the average free path of molecules and the average time of their collisions for gases). This leads to the derivative-free governing equations (the discontinuum approximation) that are very convenient for numerical simulation. The theoretical analysis of governing equations describing the fundamental conservation laws in the continuum and discontinuum approximations is given. The article demonstrates the derivative-free approach based on the correctly defined macroparameters (pressure, temperature, density, etc.) for the mathematical description of physical and chemical processes. This eliminates the finite-difference, finite-volume, finite-element or other approximations of the governing equations from the computational algorithms.

A Mathematical Modeling of Computer Numerical Control Skiving Process for Manufacturing Helical Face Gears Using Sensitivity Matrix Combined With Levenberg–Marquardt Algorithm

Abstract Currently, numerous studies have applied gear skiving processes to produce face gear. However, there remains a significant challenge in achieving a flexible computing model for manufacturing a precise tooth surface for face gear. This study proposes a novel mathematical model that combines the cutter modification method and computer numerical control (CNC)-axis motion modification methods within a unified “closed-loop optimization.” This approach aims to enhance the tooth surface accuracy of skived helical face gears by determining optimal coefficients. Applying the Levenberg–Marquardt algorithm and sensitivity matrix enables the calculation of new polynomial coefficients, ensuring the attainment of gear surfaces with an accuracy grade of B6 (according to the ANSI/AGMA 2009-B01 standard) for each target surface. The proposed methodology involves the generation of a helical skiving cutter using a corrected rack. Subsequently, the cutting path on the CNC machine is optimized by incorporating additional motions expressed in polynomials. A comprehensive skiving simulation is conducted to achieve the desired face-gear surface, which is corrected by specified polynomial coefficients. The proposed model is validated through numerical and machining simulations using vericut software. The results affirm the practicality and efficacy of our approach in achieving the desired accuracy in producing helical face gears through power skiving processes.

Calculation of the heat stabilizer effective parameters depending on its location relative to the pile

Maintaining the soil in a frozen state in a cryolithozone is necessary for preventing the collapse of structures. The most effective technical solution for this is the use of two-phase passive heat stabilizers. Monitoring the state of permafrost soil allows to accept technical decisions that prevent soil thawing. Calculation the effective parameters of such decisions requires mathematical modeling of thermal and hydrodynamic processes. An approach is proposed to effectively compensate the heat flux from the pile on the ground, assuming the location of the heat stabilizer in the same well with the pile or at a slight distance from it. The aim of the work is to calculate the effective parameters of the heat stabilizer depending on its location relative to the pile. The developed mathematical model assumes the five tasks: 1) blowing the above-ground part of the heat stabilizer with air; 2) movement of liquid refrigerant to the bottom of the heat stabilizer; 3) cooling of the casing of the heat stabilizer with an two-phase flow of refrigerant; 4) heat exchange in the system refrigerant — the casing — frozen soil; 5) compensation of heat flow from the pile into the ground with heat flow from the ground into the heat stabilizer. The first problem is solved on the basis of an empirical criterion equation. The second and third tasks are solved using the laws of conservation of mass, momentum and energy. The fourth and fifth tasks involve solving the equation of thermal conductivity. As a result of calculations, the effective parameters of the heat stabilizer were obtained. The minimum lateral dimensions of the heat stabilizer casing have been established to compensate the heat flow from the pile into the ground. The time of freezing front reaching the pile from the heat stabilizer located at a distance of 0.5 m from one of its corners has been determined.

Shortcut model to evaluate the performance of continuous preferential crystallization for conglomerates forming chiral systems

The separation of two enantiomers of a chiral molecule is one of the most difficult tasks for separation technology. Among the available methods, Preferential Crystallization (PC) offers a relatively simple and efficient possibility to separate pairs of enantiomers of conglomerate forming chiral systems. To estimate the potential and to design PC processes, mathematical process models are required. Recently, a short-cut model (SCM) was developed which was found capable to predict the course of batch-wise operated PC until nucleation of the unseeded counter-enantiomer terminates the exploitable production period. In this paper the SCM is reformulated in a dimensionless way and extended to describe also more productive continuous operation of PC. Characteristic dimensionless numbers are demonstrated to be instructive to evaluate effects of system specific kinetic parameters and to identify suitable operating conditions. The sensitivity of the continuous PC process with respect to the most relevant model parameters is investigated based on simulation results. Finally, the role of the SCM in the workflow of designing continuous PC processes is summarized.

Numerical and experimental studies on the heat transfer characteristics and process optimization of the billet soaking furnace

The precision of furnace temperature control in the soaking furnace is critical to the quality of billet heating. This paper develops a three-dimensional(3D) mathematical model of the heating process of steel billets in the soaking furnace, which can be monitored online in real time. The accuracy of the model was verified by black-box experiments. A comparative analysis of the model’s simulated and experimental data revealed a hit rate exceeding 70 % (with a relative error margin within ± 5 %). Leveraging this mathematical model, we propose a direct optimization strategy that effectively saves 24 % of heating time, accelerates the process of achieving temperature uniformity within the billet, and boosts overall heating effectiveness. This approach offers potential for broader application in optimizing the heating processes of various materials.