Vol. 10, No 1, 2006 < Volumes
(ISSN 1428-6394)

Contents:

  • Michele Caponigro and Stefano Mancini From Quantum Logic to Quantum Computational Logic   abstract | full text
  • Robert Jankowski and Henryk Walukiewicz Conditional Simulation of Spatiotemporal Random Fields of Environmental Contamination   abstract | full text
  • Yongzheng Fu, Yaqiao Cai and Keqi Wu Forecasting the Energy-saving Benefits of Variable-speed Pumps   abstract | full text
  • Andrzej Ambroziak and Paweł Kłosowski A Four-Node 3D Isoparametric Membrane Element   abstract | full text
  • Andrzej Ambroziak and Paweł Kłosowski The Elasto-Viscoplastic Chaboche Model   abstract | full text
  • Jacek Smolka, Andrzej J. Nowak, Derek B. Ingham and Lionel Elliott Numerical Modelling of a Multi-Physical Problem within an Encapsulated Three-Phase Transformer and Its Surrounding   abstract | full text
  • Romuald Rządkowski, Leszek Kwapisz, Marcin Drewczyński, Ryszard Szczepanik and Jammi Srinivasa Rao Free Vibrations Analysis of Shrouded Bladed Discs with One Loose Blade   abstract | full text

Abstracts:

hMichele Caponigro and Stefano Mancini From Quantum Logic to Quantum Computational Logic

We overview the main concepts of quantum logic ranging from the orthodox formulation to the quantum computational aspects.

 

hRobert Jankowski and Henryk Walukiewicz Conditional Simulation of Spatiotemporal Random Fields of Environmental Contamination

The paper considers a method of conditional simulation of spatiotemporal scalar random fields of certain environmental phenomena. The method can be used to predict field values at given space points at specified time, on the basis of field values at other locations and data on second order moment functions in the domain. This approach has been applied to a space-time prognosis of soil contamination fields. The assessment of the spatiotemporal variability of heavy metals' concentrations provides the knowledge needed to monitor and control soil contamination. Empirical data of heavy metal (viz. chromium) concentration in the soil of northern Poland have been used in the study. The acceptance-rejection method has been applied to generate covariance matrices and vectors of discrete field values, taking into account conditional probability distributions. The results of the study show that the considered method can be successfully used to model conditional, spatiotemporal random fields of contamination with relatively small simulation errors.

 

hYongzheng Fu, Yaqiao Cai and Keqi Wu Forecasting the Energy-saving Benefits of Variable-speed Pumps

By calculating the energy-saving benefits of a variable-speed pump, the relation between back pressure and energy-saving benefits is analyzed. Based on the energy-saving benefit calculation for four different pump types using a non-dimensional method, it is shown that when the non-dimensional back pressure, h, and the non-dimensional flow, Q, are equal, then the corresponding non-dimensional energy-saving benefit Ω of variable-speed control are quite close each to other, thereby advancing a forecasting method of energy-saving benefits of variable-speed control. When the method is used to forecast the energy-saving benefits of pumps whose specific speed is between 15 and 190 and the flow – between 5 and 200m3/h (subject to the condition h ≤ 0.9, Q ≥ 0.5), the error will not exceed 6.55% and thus the method proves to be of reference value for the evaluation of the variable-speed energy-saving benefits of other pumps.

 

hAndrzej Ambroziak and Paweł Kłosowski A Four-Node 3D Isoparametric Membrane Element

The paper presents a non-linear finite element procedure for analysis of membrane structures. A four-node quadrilateral finite element is formulated to represent a general curved elastic geometrically non-linear surface. The described isoparametric element is C 0 -continuous, of constant thickness, and assumes a plane stress criterion. A simple numerical example is presented as an application of the described theory.

 

hAndrzej Ambroziak and Paweł Kłosowski The Elasto-Viscoplastic Chaboche Model

The elasto-viscoplastic constitutive equations of the Chaboche model [1] have been developed and modified many times. The aim of the present paper is to present the existing Chaboche model variants and describe its scientific and engineering applications. A compact review of literature on these applications is given, focussed on publications offering a wider and more comprehensive view of the elasto-viscoplastic Chaboche model. The article is an introduction to a comprehensive investigation of the elasto-viscoplastic Chaboche model.

 

hJacek Smolka, Andrzej J. Nowak, Derek B. Ingham and Lionel Elliott Numerical Modelling of a Multi-Physical Problem within an Encapsulated Three-Phase Transformer and Its Surrounding

The paper presents a numerical thermal model of an encapsulated three-phase electrical transformer. The model is based on the multi-physical approach and involves heat transfer analysis coupled with the examination of specific power losses in the coils and the core using electromagnetic field analysis as well as determination of thermal stresses. The thermal boundary conditions (i.e. local heat fluxes) are determined by considering a numerical model of the surrounding air. Additionally, the device is cooled via radiation (from the external walls) and forced convection (a water cooling system). A few different configurations of the cooler and the heat pipes are also analyzed. Moreover, anisotropic material properties were applied for stranded coils and the core. A partial experimental validation of the model has shown that the temperature distribution within the transformer is more realistic and closer to the measurements when compared with the previous analysis limited to heat transfer problems only with uniform internal heat sources and isotropic material properties. The total heat transfer rate indicates that forced convection is the most important heat dissipation mechanism in this model. The significance of the water cooling system has also been established in calculations of crack presence in the model.

 

hRomuald Rządkowski, Leszek Kwapisz, Marcin Drewczyński, Ryszard Szczepanik and Jammi Srinivasa Rao Free Vibrations Analysis of Shrouded Bladed Discs with One Loose Blade

As a failure of rotor blades in a gas turbine was reported, the rotating-mode shapes of flexible shrouded bladed disc assemblies were calculated using a finite element approach. Rotational effects, such as centrifugal stiffening were accounted for, and all couplings between the flexible parts were allowed. The spin softening effects were neglected. A dynamic analysis of the shrouded bladed disc demonstrated that it was designed with a sufficient safety region of resonance. In case of one blade getting loose, it is vibrating in resonance.

 

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