Papers by Keyword: Mathematical Modeling

Paper TitlePage

Authors: F. Campo, Jairo A. Escobar Gutiérrez
Abstract: This work develops a mathematical model that explains the ball mills operational speed. The scope of the model is defined by the powder as the number of particles per cm3 and the Relevance defined as the ratio between different forces. In this study, the Relevance is defined as the ratio between superficial tension and inertial forces. The conditions for a free flowing powder and a single particle are differenced and non-dimensional numbers are found. The model proposed use the friction force between mill walls and the powder mass is related by a friction coefficient that can be calculated from angle repose. An experimental approach proves that the suppositions made in order to develop the model were adequate in this way the existence of the non-dimensional numbers is confirmed. It is also discussed the use of non-dimensional numbers to increase processing speeds with by increasing gravity clarifying that a given Relevancy, it is not dependent of the non-dimensional numbers. Thus, the model can help in the design process of ball mills with a deeper understanding of the phenomena.
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Authors: P. Råback, Risto M. Nieminen, Rositza Yakimova, M. Tuominen, Erik Janzén
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Authors: Zhang Ping You
Abstract: As servo-control system becomes more and more complicated, traditional simulation method can't meet the increasing demand for servo-control system, an dynamic simulation approach for servo-control system is introduced With Simulink software platform. Taking an mechanical hydraulic servo-control system as sample, the mathematical model for the system is established by standard procedures firstly. Then the simulation model of this servo-control system are constructed with block diagram module in Simulink. Finally, dynamic simulation test are performed to validate the effectiveness of the method with simple operation of the software. The simulation results shows that the dynamic simulation approach with Simulink is an effective and convenient way to research the dynamical characteristics for servo-control system.
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Authors: I. Tsikis, Frank A. Coutelieris
Abstract: This work presents a mathematical model to support the electrical energy production in a specific area by using Renewable Energy Sources (RES). More precisely, three RES types (namely, wind, solar and hydropower) are considered while biomass is used to satisfy thermal demands. The actual goal of the model is to generate one or more scenarios for the efficient production of electrical energy for a specific area by selecting the most suitable RES in terms of energy efficiency and cost effectiveness. More specifically the decision criteria are the minimization of installation and operational costs produced for each scenario and the maximization of the electrical energy produced by the specific power plant. Finally, feasibility analyses for selected case studies as well as an evaluation against similar best practices are also carried out for each scenario proposed.
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Authors: G. Sankara Narayanan, Durairaj Vasudevan
Abstract: Unconventional machining process finds heavy application in aerospace, automobile and in production industries where accuracy is most needed. This process is chosen over other traditional methods because of the advent of composite and high strength materials, multifaceted parts and also because of its elevated precision. Regularly in unconventional machines, trial and error method is used to fix the values of process parameters. An algorithm incorporating Artificial Neural Network (ANN) is proposed to create mathematical model functionally relating process parameters and operating parameters of a wire cut electric discharge machine (WEDM) and copper is the work piece. This is accomplished by training a learning algorithm of feed forward neural network with back propagation. The required data used for training and testing the ANN is obtained by conducting trial runs in wire cut electric discharge machine. Proposed algorithm paves reduction in time for fixing the values for the process parameters and thus reduces the production time along with reduction in cost of machining processes and thereby increases the production as well as the efficiency. The programs for training and testing the neural network are developed, using matlab 7.0.1 package.
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Authors: Qi Zhang, La Dao Yang, Heng Wen
Abstract: A two-dimensional (2-D) heat transfer and solidification model has been established and applied to calculate the temperature distribution and solid shell thickness profile of a continuous casting slab in a steel plant. A finite difference method was used for the numerical simulation. For thermal analysis, the 2-D slice unsteady-state heat conduction equation with enthalpy convention was used. Meanwhile, non-linear material properties of specific heat and thermal conductivity as well as phase changes during solidification were considered in the model. The temperature distribution and solid shell thickness calculated by mathematical model agree with those predicted by industrial and experimental measurements. The model could also be used to predict the optimum process parameters on casting speed, heat removal rates and the water distribution of secondary cooling zone.
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Authors: Shu Qin Wu, Yao Ming Li
Abstract: The paper introduces the precision processing technology of grinding using magnetic fluid and presents the working mechanism of magnetic-fluid grinding. Based on Preston Equation, it also establishes a mathematical modeling for magnetic-fluid grinding, which is used to study the relationships between the effects of grinding and the variation of such technological parameters as the revolving speed of work-piece, the intensity of magnetic field, the distance between work-piece surface and magnetic center, the size of the magnetic fluid and grinding time, etc. Analysis on the grinding of Si3N4 ceramic-balls proves that the model has been well established.
406
Authors: M. Stasiek, Andreas Öchsner
Abstract: A numerical approach for the segregation of atomic oxygen at Ag/MgO interfaces is presented. A general segregation kinetics is considered and the coupled system of differ- ential equations is solved due to a one-dimensional finite difference scheme which accounts for concentration-dependent diffusion coefficients. Based on a model oxide distribution, the influence of the concentration-dependency is numerically investigated and compared with the solution for constant coefficients. In addition, the numerical approach allows for the consider- ation of general boundary conditions, specimen sizes and time-dependent material and process parameters.
360
Authors: Andreas Öchsner, Michael Stasiek, José Grácio
Abstract: A numerical approach for the segregation of atomic oxygen at Ag/MgO interfaces is presented. A general segregation kinetics is considered and the coupled system of partial differential equations is solved due to a one-dimensional finite difference scheme. Based on a model oxide distribution, the influence of the oxide distribution is numerically investigated and compared with the solution for equidistant arrangements. The numerical approach allows for the consideration of general boundary conditions, specimen sizes and time-dependent material and process parameters. Furthermore, a numerical procedure to convert two-dimensional microstructures into representative one-dimensional distributions is described.
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Authors: Carmen Ema Panaite, Aristotel Popescu, Oana Dodun, Konstantinos Papakostas
Abstract: Global challenges related to fossil fuels depletion, climate changes and growth of population with a higher comfort demand require a significant change of heating and cooling perspective in the building sector, from currently mainly fossil combustion to renewable energy sources. Solar heating and cooling may have an important role in providing an economically feasible and environmentally sustainable long-term solution to these essential requirements. This paper presents a brief overview on the available solar cooling technologies focus on thermally driven methods. A market study is also carried out and the potential of solar cooling is emphasized.
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