Range Of Changes In Parameters Research Articles

Collaborative design of atmospheric cutterhead opening and disc cutter arrangement

As the core components of the shield machine, the cutterhead body and the cutter directly interact with the soil, which plays a vital role in tunneling efficiency and performance. For the atmospheric cutterhead, the cutterhead opening and the cutter arrangement are mutually restricted, which brings great challenges to the design of the cutterhead. To solve this problem, an innovative collaborative strategy for cutterhead structure and cutter arrangement is proposed in this paper. By constructing a parametric model, we deeply analyzed the relationship between the cutterhead parameters and the cutter size and defined the feasible range of parameter changes. On this basis, we have developed a set of cutter arrangement specifications to ensure the coordinated operation between the cutter holders and between the cutter holder and the gate, avoiding potential interference problems, and calculating the minimum cutter spacing. In addition, the study also takes into account the various loads on the cutter and constructs a load model specifically for the atmospheric cutterhead. By taking an atmospheric cutterhead with a diameter of 15 m as an example, we elaborate on the implementation process of this method, which not only maximizes the cutterhead opening but also effectively controls the unbalanced load. The methodology of this study provides a new perspective and solution for the design of other types of cutterhead.

Numerical Solutions of Van Der Pol-Mathieu Type Nonlinear Ordinary Differential Equation in Complex Plasma

The description dust plasma behavior via a multi-fluid model, Where it represents that Boltzmann distributed electrons and ions, the dust momentum and Poisson's equations, in addition to the continuity equation that has a source term for the dust grains. The Runge-Kutta technique of fourth order was then used to numerically solve the equation. The solution shows a variety of behaviors under wide range of parameters changes. In particular, the solution of the equation shows a chaotic behavior at α= 1.0. In this study, the chaotic behavior in the plasma complex is graphically studied and discussed for some certain parameters. The aim of this study can be helped the researchers to investigate several nonlinear oscillations in different plasma and fluid mechanics models.

Numerical Solutions of Van Der Pol-Mathieu Type Nonlinear Ordinary Differential Equation in Complex Plasma

The description dust plasma behavior via a multi-fluid model, Where it represents that Boltzmann distributed electrons and ions, the dust momentum and Poisson's equations, in addition to the continuity equation that has a source term for the dust grains. The Runge-Kutta technique of fourth order was then used to numerically solve the equation. The solution shows a variety of behaviors under wide range of parameters changes. In particular, the solution of the equation shows a chaotic behavior at α= 1.0. In this study, the chaotic behavior in the plasma complex is graphically studied and discussed for some certain parameters. The aim of this study can be helped the researchers to investigate several nonlinear oscillations in different plasma and fluid mechanics models.

Study on condensation of oily particles under the influence of water vapor phase transition

To address the problem that oily fine particles are too small to be easily captured by traditional dust removal equipment, which hinders improving the purification efficiency, this paper proposes using the technical principle of water vapor phase transition to conduct experiments and simulations. A set of water vapor experimental devices for fine particles of oil mist is designed, and the data are analyzed by a Grimm spectrometer. The experimental results show the phase change of water vapor has a remarkable effect on the agglomeration of oily fine particles. Phase change condensation makes the particle size of fine particles increase by 5–10 times in a truly brief time, and the polymerization and removal efficiency are greatly improved. To analyze the changes of the coalescence characteristics in a larger range of parameter changes, the Euler multiphase flow model is adopted, the particle condensation growth rate function is introduced by a user-defined function to establish a coalescence model and the heterogeneous condensation growth characteristics of oily particles are analyzed in a supersaturated water vapor environment. The simulation results show that the condensing chamber temperature of the condensing chamber is 283 K, and the lower the air flow rate of the condensing chamber, the more favorable the heterogeneous condensation growth of oil particles. The change rule of agglomeration characteristics of oily particles obtained by experiment and simulation proves the feasibility of improving the removal efficiency of oily fine particles.

Гідродинамічне дослідження групи струменів рідини в апаратах із циліндричними розподільними пристроями

The analysis of existing studies regarding the process of steam condensation from a vapor-gas mixture on liquid jets allows us to conclude that the vast majority of them are experimental in nature, so the results of these studies can be correctly used only for the appropriate range of parameter changes of the liquid and gaseous phases. Also, the subject of research in them is mainly the hydrodynamic mode of a continuous liquid jet along its entire length. During theoretical and experimental studies, it was established that the shape of the jets flowing out of the cylindrical holes counter to the oncoming steam current differs from cylindrical shape, depends on the flow parameters, and is characterized by their rotation with intense wave formation on the jet surfaces. The jets are combined with each other with their subsequent disintegration along the current, dispersed and carried away with the steam current. Accordingly, it is incorrect to apply existing methods of heat transfer calculation to the analysis of heat transfer in this type of jets, only on solid jets of liquid, outside the investigated range of parameters. That is, using classical equations is impossible due to the complexity of calculating the cross-sectional area of jet groups flowing through cylindrical holes, and accordingly, the area of the heat exchange surface. Namely, it is impossible to use the traditional concept of the heat transfer coefficient as a parameter. Therefore, most of the existing calculation methods are based on using dimensionless complexes that describe the degree of change in the temperature of the liquid along the length of the jets under the appropriate geometric conditions. That is, without finding the limits of changes in the continuity of liquid jets, determining the limiting hydrodynamic modes using the existing methods of heat exchange calculation is incorrect.

Optimization of Process Parameters for Powder Bed Fusion Additive Manufacturing Using a Linear Programming Method: A Conceptual Framework

At present, the selection of optimal technological parameters for laser powder bed fusion (LPBF) is determined by the requirements of the fusion process. The main parameters that are commonly varied include laser power (P), scanning speed (v), hatch spacing (h), and layer thickness (t). The productivity of the LPBF process (the increment in the fused volume of the material) is equal to the product of the last three parameters, and the mechanical properties are largely determined by the volumetric fusion energy density, which is equal to the ratio of laser power to productivity. While ensuring maximum process productivity, it is possible to obtain acceptable quality characteristics—mechanical properties, surface roughness, etc.—for a certain range of LPBF technological parameters. In these cases, several quality characteristics act as constraints on the optimization process, and productivity and the key quality characteristics become components of the objective function. Therefore, this article proposes a formalized representation of the optimization problem for the LPBF process, including the derivation of the objective function with the constraint matrix, and provides a solution to the problem using the linear programming (LP) method. The advantages of the proposed method include the guaranteed convergence of the solution with an unlimited number of constraints; the disadvantage concerns the adequacy of the solution, which is limited by a relatively narrow range of parameter changes. The proposed method was tested in determining the optimal LPBF parameters for an HN58MBYu powder LP model that included 13 constraints and an objective function with two target parameters. The obtained results made it possible to increase the productivity by 15% relative to the basic technological parameters.

Influence of working conditions on the condensation efficiency of the prototype condensation hood

AbstractIn the paper performance of the prototype design of the condensation hood is analysed. Results of some experiments/measurements as well as results of CFD simulations are used to investigate the dependence of quantity called the condensation efficiency on selected working parameters. It was found that both the air inlet temperature and the air mass flow rate have significant impact on the performance of the heat exchanger. However, such changes did not influence the condensation efficiency which stays stable at the level of 100% for quite wide range of parameters changes. The same applies to the relative humidity of the inlet air. The only parameter which causes changes of the condensation efficiency is the steam mass flow rate when it exceeds 2.0 g/s. Nevertheless, operation of the hood with the steam mass flow rate up to $$\approx 3.0$$ ≈ 3.0 g/s guarantees that at least 90% of the steam is condensed.

Functional fish products with jerusalem artichoke

The article provides basic information about the functional properties of fish culinary products developed on the basis of freshly frozen pollock fish with additives of vegetable powders: jerusalem artichoke powder, basil, tomato, paprika, dill, and onion and carrot were used as vegetable raw materials. The influence of the duration of heat treatment of products from pollock cutlet mass on sensory characteristics, the value of moisture-retaining ability, the size of the particles of crushed muscle tissue of model samples of minced meat is considered. Rational parameters of heat treatment of functional minced fish products have been established. The influence of a vegetable additive from Jerusalem artichoke on the functional and technological characteristics of minced fish systems has been studied. The safety indicators of finished products prepared on the basis of heat-treated fish raw materials with the addition of jerusalem artichoke powder, flavoring additives and vegetable raw materials are investigated. This determines the main task of research and is relevant and promising. The purpose of the development of new specialized products is to obtain enriched model compositions for the manufacture of high-quality functional minced products in an industrial way. The article presents data on the optimization of the ingredient composition of fish culinary products, taking into account the technological properties of raw materials and storage conditions. The list of ingredients with immunomodulatory and antioxidant properties and the possibility of their use in the preparation of specialized fish culinary products for rational and specialized nutrition is scientifically substantiated. Optimization was carried out using modern programs that provide mathematical modeling of product formulations in the realized range of parameter changes. The qualitative and quantitative prescription composition is modeled in accordance with sanitary norms and requirements of the SanPiN 2.3/2.4.3590–20 requirements for food products of the population.

Robust Stabilization via Super-Stable Systems Techniques

In this paper, we propose a direct method for the synthesis of robust systems operating under parametric uncertainty of the control plant model. The developed robust control procedures are based on the assumption that the structural properties of the nominal system are conservated over the entire range of parameter changes. The invariant-to-parametric-uncertainties transformation of the initial model to a regular form makes it possible to use the concept of super-stable systems for the synthesis of a stabilizing feedback. It is essential that the synthesis of super-stable systems is carried out not on the basis of assigning eigenvalues to the matrix of the close-loop system, but in terms of its elements. The proposed approach is applicable to a wide class of linear systems with parametric uncertainties and provides a given degree of stability.

Influence of additions on the structure of the free fares

The article provides basic information about the functional properties of flour culinary products developed on the basis of rice and corn flour with additives of powders of vegetable origin: jerusalem artichoke, sea buckthorn, apples, carrots, tomato, paprika, dill, daminaria, and stevia extract was used as a sweetener. Balanced nutritionally adapted nutrition, corresponding to the physiological needs of schoolchildren, gender and individual characteristics of children aged 7–11 years, is necessary for the full development of physical and intellectual abilities. In this connection, the development of flour culinary products nutritionally adapted to the peculiarities of baby food, the optimization of the ingredient composition of flour culinary products, taking into account the technological properties of raw materials and biomedical recommendations for the diet of this category of nutritionists will contribute not only to achieving the best results in their development, physical and mental improvement, but will also prevent a number of alimentary-dependent diseases and conditions of this category of the population. This determines the main task of research and is relevant and promising. The purpose of the development of new specialized products is to obtain enriched gluten-free compositions for the production of high-quality pancake tape by an industrial method. The article presents data on the optimization of the ingredient composition of flour culinary products, considering the technological properties of raw materials and biomedical recommendations for the nutrition of schoolchildren of grades 1–4. The list of ingredients with immunomodulatory and antioxidant properties and the possibility of their use in the preparation of specialized flour culinary products for school meals is scientifically substantiated. Optimization was carried out using modern programs providing mathematical modeling of product formulations in the realized range of parameter changes. The qualitative and quantitative prescription composition is modeled in accordance with sanitary norms and requirements of the SanPiN 2.3/2.4.3590–20 requirements for children's food products, considering their physical exertion. The relationship between the mass fraction of protein components (rice and corn flour and egg white) and physico-chemical indicators of the quality of flour culinary products for the nutrition of schoolchildren has been established. It is experimentally proved that the use of the developed recipe compositions will contribute to an increase in the content of protein, fats, carbohydrates, vitamins, minerals, increase the biological value and the total content of water-soluble antioxidants in flour culinary products for the nutrition of students aged 7–11 years.

Numerical Study of Natural Convection of Biological Nanofluid Flow Prepared from Tea Leaves under the Effect of Magnetic Field

The heat transfer of a biological nanofluid (N/F) in a rectangular cavity with two hot triangular blades is examined in this work. The properties used for nanoparticles (N/Ps) are derived from a N/P prepared naturally from tea leaves. Silver N/Ps are distributed in a 50–50 water/ethylene glycol solution. The cavity’s bottom wall is extremely hot, while the upper wall is extremely cold. The side walls are insulated, and the enclosure is surrounded by a horizontal magnetic field (M/F). The equations are solved using the control volume technique and the SIMPLE algorithm. Finally, the Nu is determined by changing the dimensions of the blade, the Rayleigh number (Ra), and the Hartmann number (Ha). Finally, a correlation is expressed for the Nu in the range of parameter changes. The results demonstrate that an increment in the Ra from 103 to 105 enhances the Nu more than 2.5 times in the absence of an M/F. An enhancement in the strength of the M/F, especially at the Ra of 105, leads to a dramatic reduction in the Nu. An increase in the height of the triangular blade intensifies the amount of Nu in weak and strong convection. The enlargement of the base of the triangular blade first enhances and then decreases as the Nu. The addition of 5% silver biological N/Ps to the fluid enhances the Nu by 13.7% in the absence of an M/F for high Ras.

ДОСЛІДЖЕННЯ АПЕРІОДИЧНОГО РЕЖИМУ ПІД ЧАС ПЕРЕХІДНОГО ПРОЦЕСУ В КОЛИВНОМУ КОЛІ З МЕТОЮ ПЕРЕТВОРЕННЯ ЕНЕРГІЇ ЕЛЕКТРИЧНОГО СТРУМУ НА ТЕПЛО ДЖОУЛЯ

Purpose. Research initiated by revealing the paradox of disturbed energy balance based on the position of the virial theorem and studying examples of the Van de Graaf generator, a capacitor containing a ferroelectric, and a heat pump capable of providing an energy conversion factor greater than 100%, as well as an idealized theoretical known as the Maxwell demon, showed the possibility of increasing the efficiency of converting current energy into Joule heat. Methodology. The results are verified by comparing the relative efficiency of the conversion of current energy into heat in the oscillatory, critical and aperiodic modes of the transient process in a series oscillating circuit. Mathematical modeling in a wide range of parameter changes has shown the advantage of using the aperiodic transient mode of a series oscillating circuit to convert current energy into heat, compared to the power supply of an electric heating system, which is based on the established method. Experimental tests of the experimental sample fully confirm the qualitative results of mathematical modeling. Results. An achievable limit level of conversion efficiency in the active resistance of energy accumulated by inductance and capacitance according to the virial theorem is established. Originality. For the first time, the application of the aperiodic transient mode in a series oscillatory circuit is proposed in order to convert the energy of current to Joule heat. Practical value. As a practical result, a method of converting current energy into pulse energy has been developed, which implements the algorithm of simultaneous energy accumulation by inductance and capacitance, and its simultaneous conversion in a series oscillating circuit, for which a patent has been obtained. Possibilities of application of the developed method for the purpose of induction heating of metals by Foucault currents as replacement of a method of shock excitation of fluctuations are studied. To this end, the conductivity of metals, which causes the flow of Foucault currents, should be considered as the introduction of equivalent active resistance in the oscillating circuit. The introduction of the method will not require changes in the process equipment, except for the power supply scheme, and should eliminate the fundamental disadvantage of the method of shock excitation of powerful oscillations, which is low efficiency.

Development of models and methods for creating a digital twin of plant within the cyber-physical system for precision farming management

The paper discusses creation of a digital twin (DT) of plant for an intelligent cyber-physical system for managing precision farming. A new approach to formalization of DT knowledge is proposed to form expert knowledge within the subject area based on the ontological specification of stages of plant growth and development and multi-agent technology for creating stage agents and coordinated dynamic recalculation of stage duration and yield forecast based on events in the environment. The paper proposes a method for calculating the forecast for duration of plant development stages and yield based on expert knowledge. A “tube” model of the range of changes in parameters of plant development for each stage has been developed. The paper also introduces a method for calculating the yield forecast, as well as the dates of beginning and end for each plant development stage within the “tube” during their normal development and in case of critical situations, for example, frost or drought. Ontology of plant development is constructed for implementation of the “tube” model of environmental parameters, which is converted into a digital form within the ontology editor, available for use by agents. The paper describes the structure and functions of a smart plant DT, built on the basis of a knowledge base and a module for multi-agent planning of plant development stages (for example, wheat), integrated with external weather forecast and fact services. A brief description of the created prototype of the intelligent plant DT system in Java is given. Using the system, agronomists can create their own knowledge bases and DTs of the cultivated plants for each field or even field section. The system will be useful in modern crop production for precision farming, not only “place-wise” but also “time-wise”, i.e. in terms of the best time for performing agrotechnical operations.

Effects of Geomagnetic Storms in the Low-Latitude Ionosphere

A wide range of changes in parameters of the low-latitude ionosphere has been revealed during the periods of three intense geomagnetic storms that occurred in different seasons of 2015. Ionospheric parameters, according to the data from ionosondes (ionograms), include critical frequencies fоF2, foE, and foEs; the degree of diffuseness of signals; the presence of lateral reflections; the multihop pattern of vertical-incidence ionospheric sounding (VIS); the effect of blocking signal reflections from the F2 layer by the Es layer; and the presence of М-type modes. The analysis was based on the data from ionosondes at low-latitude stations in Athens, Greece, and Nicosia, Cyprus. The following results were obtained. The spring storm was characterized by the presence of lateral reflections, greater diffuseness in the F2 layer, and an increased number of reflections during VIS during daytime hours compared to nighttime hours. The summer storm was characterized by very frequent appearance of sporadic Es layers, the occurrence of М-type reflections, and the effect of blocking. The specific analysis of the winter storm shows that the thick Es layer stretched along the Earth’s surface over a distance of no less than 800 km and had a lifetime of about 7 h.

Development of a model for energy management in office buildings by neural networks (case study: Bandar Abbas)

Building optimization measures are implemented to reduce energy consumption and environmental pollution. If energy reduction and optimization in the buildings are not measured, the national economy will be severely damaged. The energy consumption in buildings can be reduced by up to 50% by performing optimization measures in the building sector and applying Article 19 of National Building Regulations. In this study, the effective parameters on energy optimization were identified using questionnaires and expert opinions and then, the energy consumption and carbon dioxide were calculated by entering the parameters into DesignBuilder software. The parameters included types of wall and ceiling, area of windows, type of windows, and insulation of wall and ceiling, each of which contain different modes. In order to limit the problem space, a range of parameters changes in a specified interval was selected. Since it is impossible to model all probable modes, first a finite number of models was tested using the software and then, the interaction of inputs with two important outputs (energy and carbon dioxide) was obtained by training two separate neural networks. The network training facilitates the calculation of the amount of energy and carbon dioxide needed for any desired input needless of DesignBuilder software.

Substantiation of Thin-Walled Structures Parameters Using Nonlinear Models and Method of Response Surface Analysis

The article deals with the development of approach for providing of structural strength of complicated thin-walled machine-building structures, which operate in the conditions of geometric and physical nonlinearities using design solution validation. The developed approach is based on the use of mathematical model for stress-strain state taking into account geometric and physical nonlinearities and methods of approximation for constructing functions describing the evaluated characteristics of the object under study. The various factors behind the search for design solutions (including characteristics of strength, rigidity, technological and economic factors), are being added into this function. The developed algorithm for rational parameters search, which takes into account the peculiarities of the response surface shape observed in solving applied problems, is applied to them. In this case, the solution is sought over the whole range of parameter changes. Thus, in the search process, global trends of changes in design decisions are taken into account, and not local ones, as in other approaches. This allows obtain a rational solution that is stable to changes in parameters, which are possible in course of design work and production conditions. Investigations are illustrated on the freight rail-car, tractor cabin frame, carrier personnel hull.

Frequency control in an islanded hybrid microgrid using frequency response analysis tools

A hybrid microgrid has numerous decentralised control loops. Therefore, coordination among hybrid microgrid subsystems with desired performance is essential. This study presents a practical control approach for efficient tuning of proportional–integral (PI) controllers and leads compensators in islanded hybrid microgrids. This method is based on the frequency response characteristic and root-locus trajectory. It is used to minimise the frequency deviations of an AC hybrid microgrid. The presented well-tuned controllers are tuned based on droop mechanism, and coordination among hybrid microgrid subsystems with desired damping coefficient and stability margin. Then, the system performance is analysed under several disturbances. The results are compared with PI controllers tuned by Ziegler–Nichols method. As well, the robustness of the proposed approach in a wide range of parameter changes is investigated. Eigenvalue analysis and simulation results show that the minimum frequency deviations and desired relative stability of the hybrid microgrid subsystems are achieved by the proposed controllers. To show generality and efficiency of the proposed approach, the presented method is applied to a different hybrid microgrid model used in the literature. For this purpose, in order to control the frequency deviations in the stand-alone mode, presented well-tuned controller is compared with intelligent fuzzy and particle swarm optimisation-fuzzy controllers.

Triple-Layer Control System for Molten Carbonate Fuel Cell–Gas Turbine Hybrid System

The control system of molten carbonate fuel cell (MCFC) coupled with a gas turbine (GT) should be based on the multilayer structure (two- or three-layers), wherein the third layer is connected with the power output from the system and can be considered separately. Simulation model of the MCFC–GT hybrid system (HS) was built. The simulator is based on a zero-dimensional modeling of the individual elements of the system. The simulator was used for mapping the main components behavior (MCFC and GT separately). On the basis of the obtained maps of the performances and adopted restrictions on technical–operational nature, the operation line for the first line of the control strategy was obtained. The control system which realizes the obtained control strategy was built in reality. Then, the hardware-based models of the main elements were created based on the electric equipment. The hardware–software model was connected to the control system and adequate simulations were performed. The presented results indicate that the analyzed MCFC–GT HS possesses a high operation and control flexibility while at the same time maintaining stable thermal efficiency. Operation of the system is possible over a wide range of parameter changes.

Mathematical model on surface reaction diffusion in the presence of front chemical reaction

The article discusses a mathematical model of solid-phase diffusion over substance surface accompanied a frontal chemical reaction. The purpose of our article is to describe the concentration distribution and surface reacted layer growth. The model is a system parabolic equations, complicated with the presence of mobile front. It takes account of diffusive fluxes redistribution, sublimation from the surface, chemical reaction reversibility. The asymptotic approximation of the obtained nonlinear problem is constructed. Numerical solution was also carried out. Both numerical and analytical solutions conform to each other in a wide range of parameter changes, whereas observed differences are explained. It was obtained that the reaction front at the substrate surface grows as the fourth root of time in the assumed absence of evaporation and reaction reversibility. In the presence of evaporation the logarithmic distribution law ln(t) is obtained. The theoretical possibility of sharp deceleration and stop of reaction product layer growth is obtained.

Economic Scheduling of the Electric Transmission/ Distribution Substations in Jeddah City with Parametric Results

This paper is devoted to economically scheduling the number of electric transmission/ distribution substations for long-term time horizon (2011 – 2020). The schedule aims at minimizing the total costs while maintaining the problem constraints based on a dynamic programming model. There are many parameters affecting the solution of the problem, these parameters are: initial value of the substation building cost, percentage of yearly increase in the substation building cost, percentage of discount for buying more than one substation, and present and future values of the operation cost. The proposed dynamic programming model will provide Saudi Electricity Company (SEC) with a systematic procedure to arrive at the best decision based on the optimal combination of the number of substations to be built in each year during the planning time horizon. It gives also an overview for the sensitivity range of parameter changes for the same optimal solution, and gives other optimal solution ranges for more changes in the parameters.