Mathematical Mode Research Articles

Flexible Flow Shop Scheduling and Energy Saving Optimization Strategy under Low Carbon Target

In order to reduce the carbon emissions of the flow shop which consists of unrelated parallel machine, a kind of scheduling mathematical mode with low carbon emission target is built by analyzing the carbon emissions of the machine tools under different running conditions. Not only the carbon emissions produced in the handling process which is rarely discussed in the previous studies, but also the carbon emissions produced during the start-up and shutdown process of the selected machine tools are considered in the model. Based on this model, a multi-state alternation energy saving optimization strategy is proposed to reduce carbon emissions during the idle waiting period of machine tools. An improved genetic algorithm is employed to solve this optimization problem. In the end, the t cases are studied to validate the strategy.

Technique for operational diagnosis of pipelines of energy systems and complexes

THE PURPOSE. To consider the problems of reliability of pipeline systems of housing and communal services. To analyze existing methods for assessing the technical condition of pipelines. To develop an improved technique that allows you to search for various types of defects in pipelines. To develop a device for inertial excitation of low-frequency diagnostic vibration vibrations. To develop software in the LabVIEW environment for collecting, storing and processing signals from a sensitive sensor (piezoelectric sensor) installed on a pipeline. To conduct a series of experimental studies to te st the proposed methodology. METHODS. The method of inertial excitation of vibrations was used to excite vibrations in the wall of the investigated pipeline. To search for the natural frequencies of vibrations of the pipeline under study, mathematical mode ling methods were used, implemented in the ANSYS software package. During the experiments, the fast Fourier transform method was used to process the signals coming from the piezoelectric sensor. RESULTS. The article presents a technique for assessing the t echnical condition of pipelines, as well as a device for inertial excitation of vibrations. The article presents the results of experimental studies on a fiberglass pipeline, the results showed that when an oscillatory wave passes through the wall of a defect-free pipeline, its amplitude changes insignificantly. If there is a defect in the wall of the investigated pipeline, the vibration amplitude will be much weaker due to the dissipation of vibrational energy in the place of the defect. Thereby, it is pos sible to determine not only the presence of a defect, but also its size by the degree of attenuation of the signal amplitude CONCLUSION. The proposed technique is the basis for the creation of a new measuring and diagnostic complex for vibration control of pipelines.

Dynamic response of vertical shaft Pelton turbine unit for forced vibration

This research work was carried out to model the excitation force imparted by water jet in the form of Fourier series and determine the forced response of Pelton turbine unite of Khulelhani-I hydropower analytically by developing mathematical mode. Amplitude of forced vibration form analytical was compared with simulation result.
 The mathematical model was developed by calculating the kinetic energy of disk and potential energy of both disk and shaft. Hamilton’s principle was used to determine equation of motion and then Galerkin method was used to determine response of the system. Fourier analysis was done to obtain the function in its exact form. The developed methodologies were followed to find the analytical solution of Kulekhani-I unit of 3100 kW rated at 600rpm. A rigid disk (runner and bucket assembly) was situated along end of flexible shaft with fixed support at the shaft.
 First five Fourier components are to be considered in analysis for meaningful representation of forcing function. The amplitude of vibration of Pelton turbine unit with single nozzle in Y-direction (the direction of water jet) obtained by analytical method was closed with that obtained from the ANSYS simulation.

Simulation of Transfer and Spread of Pollutants into the Marine Environment Using a Probabilistic Model of Turbulence

The paper describes the problem and specifies the key sources of marine pollution. A mathematical mode of particle transfer and settling as well as the parameters of environment turbulence are proposed. A 3D diffusion-advective model discussed in the paper was developed on the basis of “wandering particles” method with the use of random numbers generator for nondeterministic processes simulation. But it has a number of specific features as compared with similar models in practical setting of boundary conditions at water-air boundaries and water-bottom boundaries, description of turbulence of different scales, in taking into account the effects of the initial immersion of a heavy jet, in the effect of flocculation as well as taking into account non-conservatism of the impurity. Different simulation results are presented.

Research on Operating Characteristics of Two-Terminal Flexible Direct Transmission with Improved Deadbeat Control

Traditional DC transmission technology has obvious defects in power adjustment speed, loss reduction, protection and control, etc., and it has been unable to meet the diverse needs of electricity consumption. The flexible DC transmission system not only solves the above shortcomings, but also has the advantages of independently controllable power and power supply to passive network. It is widely applied in distributed power generation by new energy, micro grid and other fields. This paper takes the two-terminal flexible DC transmission system as the research object, establishes the mathematical mode of two-terminal flexible DC transmission system, and studies the basic operation mode of the system and the voltage source converter (VSC) control strategy on this basis. Considering the problems of control delay and poor responsiveness of current closed-loop control when the traditional deadbeat control is applied to VSC converters, an improved deadbeat control strategy is proposed to solve the above-mentioned defects by predicting the current sampling at k+2 moment. Finally, the co-simulation is used to verify the correctness and reliability of the above-mentioned method.

Investigation of Hydraulic Performance Based on Response Surface Methodology for an Agricultural Chemigation Proportional Injector

Injectors are key pieces of equipment for chemigation systems, and their hydraulic performance has a significant effect on chemigation systems and crops. In order to investigate the influence of different working parameters on hydraulic performance for a water-powered proportional injector (PI), three key parameters of inlet and injection flow rate were researched using a one-factor experimental design method. The regression equations between different factors and response variables were established through a response surface method based on one-factor experimental results. Lastly, a mathematical model of the actual injection ratio was established. Some experiments under different, randomly selected parameter combinations were carried out to verify the prediction precision of the mathematical mode. The results showed that the injection flow rate increased first within the differential pressure of 0.05 to 0.10 MPa and then tended towards stability with increasing differential pressure. The injection flow rate decreased by increasing the viscosity and the change in the injection flow rate was small enough when the viscosity was greater than 500 mPa·s. The impact factors, in order of significance, for inlet flow rate were differential pressure, viscosity of injection liquid and setting injection ratio. The impact factors, in order of significance, for injection flow rate were viscosity of injection liquid, setting injection ratio and differential pressure. The regressive model for predicting the actual injection ratio was validated using an experiment and the relative deviation between calculated value and tested value was less than 5.98%, which indicated that the mathematical model had high credibility.

Adaptive Trajectory Tracking Safety Control of Air Cushion Vehicle with Unknown Input Effective Parameters

This paper studies the trajectory tracking control problem of an Air Cushion Vehicle (ACV) with yaw rate error constraint, input effective parameters, model uncertainties and external wind disturbance. Firstly, based on the four-degree of freedom (DOF) vector mathematical mode of ACV, the radial basis function neural network (RBFNN) is adopted to provide the estimation of model uncertainties and external wind disturbance. Then, an adaptive Nussbaum gain-based approach is incorporated with the backstepping control scheme to handle the unknown input efficient parameters. To avoid the complicated derivative of the virtual control laws, the command filter and auxiliary systems are introduced in backstepping. Furthermore, combing a barrier Lyapunov function (BLF) with backstepping technique, a novel trajectory tracking safety controller is designed to ensure all signals of the closed-loop system are uniformly ultimately bounded, while the yaw rate error is within the pre-set safe range. Finally, the simulation results show the effectiveness of the controller scheme.

A Model-Based Strategy With Robust Parameter Mismatch for Online HRC Diagnosis and Location in PMSM Drive System

This article proposes a model-based strategy with robust parameter mismatch for online high resistance connection (HRC) diagnosis and localization in surface-mounted permanent magnet synchronous machine (PMSM) drive system. The mathematical mode of the PMSM with the HRC is established in the abc stationary frame and dq rotating frame. Based on the model, the voltage distortion estimator is applied to estimate the voltage distortions caused by the HRC. According to the voltage distortions, a new fault characteristic signal is defined and is analyzed under different fault conditions. Based on the defined signal, the fault indicators being insensitive to the parameter mismatch are defined to diagnose the fault and locate the faulty phases. By the proposed method, not only the HRC can be detected, but also the fault severity can be assessed and the faulty phases can be located, where no additional equipment or measurement devices are needed. Both the simulation and experimental results verify that the proposed method can effectively achieve online HRC diagnosis and location in the PMSM drive system.

Analysis of DC inter-electrode fault overvoltage in AC/DC hybrid power system

AC/DC hybrid power system has become an important distribution system for high-proportion distributed renewable energy consumption and multi-energy supply. Among the DC-side fault overvoltage, the inter-electrode fault overvoltage is the most harmful to the system. In order to analyze the principle of overvoltage generation, this paper establishes a mathematical model for AC/DC hybrid power system, and researches the mechanism of inter-electrode fault overvoltage generation on the DC side of the system, and builds a Matlab/Simulink simulation model so that gets the simulation analysis results of lOkV DC and ±375V DC side in the system. The research shows that the system high-frequency mathematical model relation which obtained according to the mathematical mode is belongs to the coupled nonlinear time-varying system. The DC-side overvoltage development can be divided into three stages: after happening of the fault until the converter station is locked, after the converter station is locked until the fault is removed, after removal of the fault until the converter station is unlocked. Through modeling and simulation, it is verified that the development process of overvoltage is consistent with the theoretical analysis. According to the research conclusion, the method of ‘arrester + parallel resistance + grounding device’ is proposed to protect the DC side overvoltage of the system.

Análisis de la transferencia de calor de un sistema de refrigeración a partir de nanofluidos

In the last decade one of the main opportunity areas of the cooler systems is increase their efficiency; for this, it has been innovating in materials and working fluids mainly. In the last decade one of the main areas of opportunity in refrigeration systems is the reference to increase their efficiency. For this, it has been innovating in materials and fluids of work mainly. In this work, the analysis of the transfer of calories in liquid cooling systems is analyzed by adding nanoparticles. These systems have different industrial and refrigeration applications in electronic systems. In the present work a configuration of the refrigeration system to be used is proposed. The analysis consists of the mathematical mode from the design of the geometry and the trajectory of the flow in the pipeline, in addition to a simulation in Computational Fluid Dynamics (CFD) of the system. The conditions are presented in the results.

Green Supply Chain Management Optimization Based On NSGA II Method

Green Supply Chain Management (GSCM) is the adopted by many companies due to the government policies of various countries. The optimization technique can be applied in the GSCM to increase the profit of the company. In this research, Non-dominated Sorting Genetic Algorithm-II (NSGA-II) technique is applied for the optimization of GSCM to increase the performance. The NSGA-II method has the advantage of choosing the solution closer to the pareto-solution and uses the elitist technique to preserve the best solution in the next generation. Mathematical model of the GSCM system is established and data is provided as input to the mathematical mode. Data is generated in three types, small scale, medium scale and large scale. The proposed NSGA-II method has high performance in the optimization technique compared to existing method. The proposed NSGA-II method has the Number of Pareto Solution (NPS) metrics of 17 for large scale data, while existing method has 14.

Stochastic Optimization Model of Medium-Term Forecasting of Reserve of Financial Resources for Natural Fires Elimination

The most large-scale and frequent, due to the physical and g graphical location, natural disasters in some regions of Europe, natural fires. It cannot be denied that natural fires cause signific damage to the economies of the regions. The authors consider possibility of using stochastic economic and mathematical mode reduce the negative economic impact of forest fires on the regio economy, by optimizing the planning and distribution of finan resources for the medium-term planning period. The develop optimization criterion for planning regional reserves to prevent n ative economic consequences from natural fires is given. Exp mental modeling based on the official reporting statistical data the Russia region is carried out. The model is quite general in nat and can be used to solve similar problems not only for the Russ regions, but also in European and other countries where one has face the same problems.

Prediction of the limiting redrawing ratio

Redrawing process is used for reducing the lateral dimensions and increasing the depth of the cylinder cup, which was formed by deep drawing. To determine the optimum values of the process parameters, it is necessary to know the redrawability. In this paper, a new mathematical mode is established to predict the limiting redrawing ratio (LDR), which is based on Hill’s anisotropic criteria, tensile instability in the cup wall and sheet bending/unbending theory around the die arc radius. The maximum and minimum thickness ratio (tmax/tmin) of cup wall and friction effect were considered in the model. The calculation from the model is in good agreement with the results of finite element simulation, and also was confirmed by the experiments of commercially pure titanium (TA1) cup redrawing processing. The effects of various material properties, friction coefficient μ, radius of the die arc rd, half die cone anger α, half die opening ro, cup maximum thickness tmax, cup thickness ration tmax/tmin have been discussed to understand and control redrawing process for improving redrawablity.

Research on Alignment in the Construction of Parallel Corpus

Parallel corpora are of great value in the field of machine translation and cross-language information retrieval. Benefiting from the development of machine learning and deep learning, the technology of the construction of corpus evolves from vocabulary alignment, phrase alignment to chunk alignment. The high quality of automatic bilingual chunks alignment in corpus plays an important role in the performance improvement of machine translation systems, especially in computer-aided translation systems. In the study, the degree of adhesion and relaxation is used to measure the tightness and looseness of the inter-word connection when a chunk is identified, which can be expressed by a mathematical mode. The task of chunk alignment in the construction of a parallel corpus can be described as the three steps: input bilingual sentences, segment chunks, and semantic alignment. At present, most algorithms are based on statistical methods, and the output alignment results are machine-oriented.

Accurate numerical computation of loaded tooth surface contact pressure and stress distributions for spiral bevel gears by considering time-varying meshing characteristics

In order to meet the high strength demand from gear transmission in industrial applications, identification of loaded tooth contact performance using loaded tooth contact analysis (LTCA) has become an increasing important design stage for spiral bevel gears. To distinguish with the conventional simulated loaded tooth contact analysis (SLTCA) applying commercial finite element software, a numerical loaded tooth contact analysis (NLTCA) method is proposed to determine the loaded contact pressure and stress. In particular, focusing on the time-varying meshing characteristics of loaded tooth contact, the loaded contact pressure and stress distributions on both instantaneous and whole contact ellipses of tooth surface are determined by the proposed NLTCA, respectively. First, the universal mathematical tooth surface mode is established by applying machine settings satisfying the universal motion concept (UMC). Moreover, the curvature analysis of the contact points is performed to determine the loaded tooth surface contact pattern as the input for the proposed numerical analytical calculation method. In the identifications of loaded contact pressure and stress, their distributions having the different directions in both the instantaneous contact ellipse and the whole loaded contact pattern are taken into account. Finally, the numerical instances are given to verify the proposed methodology.

The Mechanics of Conceptual Thinking

Description of the mechanics of conceptual thinking that stems from interaction sequences between the limbic system and the verbal areas of the neocortex. Description of the rise of the attention level to full active awareness when a feeling of uneasiness due to a verbal stimulus is triggered by the amygdala, followed by an active cogitation process involving the verbal areas of the neocortex, ending in the strengthening in the neocortex by the hippocampus of a synaptic network corresponding to a modified verbal sequence that removes or reduces the feeling of uneasiness that initiated the sequence. Description of the generalization abilitythat emerges from the use of articulated languages, acquired by education, from which conceptual thinking andalso the collectively intelligible mathematical language emerge that also develops to various degrees in some individuals by education. Description of the mathematical thinking mode, about whose engrams have been located in the neocortex in areas that do not overlap the verbal areas.

Does language really matter when solving mathematical word problems in a second language? A cognitive load perspective

ABSTRACTIn a bilingual educational setting, even when mathematical word problems are presented in one’s first language, students may still perform poorly if cognitive constraints such as working memory limitations are not taken into consideration. The purpose of this study was to investigate the conditions under which learners are better able to solve word problems when presented in different modes (Reading Only, Listening Only and Reading and Listening). One hundred and thirty-two students from a federal institution in the United Arab Emirates participated in the study. Results indicated that Listening Only was negatively related to performance regardless of language. The study also found that solving mathematical word problems in English and Arabic was positively related to performance only when a dual mode, both Reading and Listening, was used. When solving mathematical word problems, both language and mode of instruction matter. Educational implications are discussed.

Two-dimensional Numerical Simulation of Continuous Reverse-flow Oxidation of Ultralow Heating Value Coalbed Methane

In order to investigate the continuous reverse-flow oxidation of ultralow heating value coalbed methane, a two-dimensional mathematical mode for the continuous reverse-flow oxidation of ultralow heating value coalbed methane was set up. The software FLUENT was used to simulate the thermal structure of the oxidation bed and the effect of operating conditional parameters. The result indicates that: the temperature field of oxidation bed presents trapezium. There exists obvious difference in temperature at the both ends of oxidation bed, and it is helpful to preheat the fresh gas and recover the flue gas heat. Comparing with the conventional porous media combustion, the continuous reverse-flow oxidation has lower peak temperature and outlet temperature, and the methane conversion rate remains high. With the increase of methane concentration, the high-temperature zone widens, the both of temperature and outlet temperature rise, and the reaction area moves to inlet continuously. As the inlet velocity increases, the peak of temperature and outlet temperature both rises significantly, and the reaction area shifts toward to outlet continuously. With the increase of wall heat loss, the peak of temperature and the whole temperature of oxidation bed both reduce, the high-temperature zone becomes narrow obviously, and the reaction area is far away from the inlet.

Geometrical Model for Characterization of Foot Deformity using 3D imaging

The present work focuses on the first stage of the development of a mathematical mode for objective assessment of foot arch geometrical characteristics using 3D scanning approach. The model is a first step in the development of multi-parametric assessment that aims to bridge the existing mismatch between professional visual based assessment and objective measurement and objective indices. One of the perceived reasons for this is that the objective indices are applied to plane projections, i.e. 3D characteristics are inferred from partial 2D information. Hence a modified index using 3D scan data was developed and assessed. Based on this single index and statistical analysis, population result matched closely reported values by professional assessors. The overlap, i.e. type 1 and type 2 errors, were reduced but still require further refinement. The next step in the artificial intelligence type multi-criteria decision making is to utilize the Gaussian curve at a global shape level using ellipsoids for shape characterization. The work on this is still in progress as key characteristics for image reconstruction need to be finalized as well as the degree of complexity of the shape approximation.

Fuzzy logic control based on genetic algorithm for a multi-source excitations floating raft active vibration isolation system

The floating raft active vibration isolation system itself is a complex system with high nonlinearity, strong coupling, and multi-source excitations, so it is difficult to build a mathematical mode...