Statistics: Methods and Applications.

Early fault diagnosis of bearing and stator faults of the single-phase induction motor using acoustic signals

We present a bibliography on moving and free boundary problems for the heatdiffusion equation, particularly regarding the Stefan and related problems. It contains 5869 titles referring to 588 scientific Journals, 122 books, 88 symposia (having at least 3 contributions on the subject), 30 collections, 59 thesis and 247 technical reports. It tries to give a comprehensive account of the western existing mathematicalphysical-engineering literature on this research field. RESUMEN Se presenta una bibliografía sobre problemas de frontera móvil y libre para la ecuación del calor-difusión, en particular sobre el problema de Stefan y problemas relacionados. Contiene 5869 títulos distribuidos en 588 revistas científicas, 122 libros, 88 simposios (teniendo al menos 3 contribuciones en el tema), 30 colecciones, 59 tesis y 247 informes técnicos o prepublicaciones. Se da un informe amplio de la bibliografía matemática, física y de las ingenierías existente en occidente sobre este tema de investigación. Primary Mathematics Subject Classification Number (*): 35R35, 80A22 Secondary Mathematics Subject Classification Number (*): 35B40, 35C05, 35C15, 35Kxx, 35R30, 46N20, 49J20, 65Mxx, 65Nxx, 76R50, 76S05, 76T05, 93C20. (*) Following the 1991 Mathematics Subject Classification compiled by Mathematical Reviews and Zentralblatt fur Mathematik. Primary key words: Enthalpy formulation or method, Filtration, Free boundary problems, Freezing, Melting, Moving boundary problems, Mushy region, Phase-change problem, Solidification, Stefan problem. Secondary key words: Continuous mechanics, Diffusion process, Functional analysis, Heat conduction, Mathematical methods, Numerical methods, Partial differential equations, Variational inequalities, Weak solutions. Palabras claves primarias: Método o formulación en entalpía, Filtración, Problemas de frontera libre, Congelación, Derretimiento, Problemas de frontera móvil, Región pastosa, Problema de cambio de fase, Solidificación, Problema de Stefan. Palabras claves secundarias: Mecánica del continuo, Procesos difusivos, Análisis funcional, Conducción del calor, Métodos matemáticos, Métodos numéricos, Ecuaciones diferenciales a derivadas parciales, Inecuaciones variacionales, Soluciones débiles. El manuscrito fue recibido y aceptado en octubre de 1999. D.A. Tarzia, A bibliography on FBP. The Stefan problem, MAT Serie A, # 2 (2000). 3

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A bibliography on moving-free boundary problems for the heat-diffusion equation. The stefan and related problems

Acoustic based fault diagnosis of three-phase induction motor

A criterion for void closure in large ingots during hot forging

The mathematical modelling of thermo-mechanical processing of steel during multi-pass shape rolling

Prediction of mechanical properties of heavy forgings

The paper presents the results of experimental and theoretical work leading to mathematical modelling of phenomena accompanying the deformation of steel which is still subjected to the last phase of the solidification process. Physical simulations of deformation of steel at such extra high temperature performed with the aid of advanced testing machines (for example GLEEBLE 3800 simulator) are very expensive and extremely difficult due to extra high temperature, simultaneous deformation and solidification of the metal and its very unstable behaviour. The Authors has presented dedicated computer program taking into consideration the density changes and analytical form of the compressibility condition. The aim of the modelling was the reconstruction of the temperature, strain and stress changes inside steel samples subjected to both deformation and final stage of solidification. The presented program enables the right interpretation of very high temperature tests. It is equipped with inverse analysis described in the current paper. Application of the system makes possible the identification of strain-stress curve parameters and lowering testing cost. In Fig. 1 the example flow stress versus strain curve (temperature 1460 °C, tool velocity - 20 mm/s) is presented. Fig. 2 shows comparison of measured and predicted loads for the discussed case. 
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Figure 1
Flow stress vs strain at temperature 1460°C and tool velocity 20 mm/s.


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Figure 2
Comparison of measured and predicted loads at temperature 1460°C and tool velocity 20 mm/s.

Computer Modelling of Deformation of Steel Samples with Mushy Zone

Modelling of heat transfer, plastic flow and microstructural evolution during shape rolling

This paper reports the results of theoretical and experimental work leading to the construction of a dedicated finite element method (FEM) system allowing the computer simulation of physical phenomena accompanying the steel sample testing at temperatures that are characteristic for integrated casting and rolling of steel processes, which was equipped with graphical, database oriented pre- and postprocessing. The kernel of the system is a numerical FEM solver based on a coupled thermomechanical model with changing density and mass conservation condition given in analytical form. The system was also equipped with an inverse analysis module having crucial significance for interpretation of results of compression tests at temperatures close to the solidus level. One of the advantages of the solution is the negligible volume loss of the deformation zone due to the analytical form of mass conservation conditions. This prevents FEM variational solution from unintentional specimen volume loss caused by numerical errors, which is inevitable in cases where the condition is written in its numerical form. It is very important for the computer simulation of deformation processes to be running at temperatures characteristic of the last stage of solidification. The still existing density change in mushy steel causes volume changes comparable to those caused by numerical errors. This paper reports work concerning the adaptation of the model to simulation of plastic behavior of axial-symmetrical steel samples subjected to compression at temperature levels higher than 1400 ° C. The emphasis is placed on the computer aided testing procedure leading to the determination of mechanical properties of steels at temperatures that are very close to the solidus line. Example results of computer simulation using the developed system are presented as well.

Miroslaw Glowacki

Papers

The mathematical modelling of thermo-mechanical processing of steel during multi-pass shape rolling

Prediction of mechanical properties of heavy forgings

Computer Modelling of Deformation of Steel Samples with Mushy Zone

Modelling of heat transfer, plastic flow and microstructural evolution during shape rolling

The Physical and Computer Modeling of Plastic Deformation of Low Carbon Steel in Semisolid State