Contents:

  • W.Kotonski, Computer Application in Music: A Survey | abstract
  • J.Przewlocki, J.Gorski, Stochastic FEM Analysis of Strip Foundation | abstract
  • P.Klosowski, Numerical Aspects of Dynamic, Geometrically Non-Linear Calculations of Elasto-Viscoplastic Plates | abstract
  • M.Gerigk, Modern Numerical Techniques for the Ships Safety Estimation in Critical Conditions | abstract
  • T.Matuszek and H.Olszewski, Liquid Energy Analysis for the Spray Nozzle Jet Parameters Optimisation | abstract
  • A.Witkowska, J.Rybicki, R.Laskowski, G.Mancini, S.Feliziani, W.Alda, Short- and Medium-Range Order in Bismuth-Silicate Glasses: A Molecular Dynamics Study | abstract

From the History of Science and Technology in Ancient Gdansk:

  • A.Januszajtis, The shipbuilding in Gdansk till 1945 | abstract

Abstracts:

h W.Kotonski, Computer Application in Music: A Survey

Two main applications of computers in music - sound synthesis and simulation of the compositional process are presented in this paper. Other applications of computers, such as digital sound recording or editing and mixing of sound tracks are also objects of discussion.

 

h J.Przewlocki, J.Gorski, Stochastic FEM Analysis of Strip Foundation

The paper affords a stochastic description of a random soil medium subjected to an external loading. The strip foundation on a soil layer in the 3-D and the 2-D strain states is analysed. It is assumed that the soil medium is statistically homogeneous and its mechanical behaviour governed by the linear elasticity theor y. It is also assumed that elastic parameters can be modelled as the multidimens ional random fields. Stochastic 2-D and 3-D finite element methods (SFEM), based on the Monte Carlo technique were used. The influence of elements supports atta ched along vertical planes on standard deviations of displacements and stresses is discussed. Local averages of random field of elastic parameters are introduce d. The convergence of applied in SFEM simulation algorithm was tested. The analy sis performed enables determination of the standard deviations of components of the stress tensor and the displacement vector for the 3-D state, based on the so lution for the 2-D plane strain state.

 

h P.Klosowski, Numerical Aspects of Dynamic, Geometrically Non-Linear Calculations of Elasto-Viscoplastic Plates

In the paper numerical aspects of elasto-viscoplastic dynamic calculations of ci rcular plates are presented. Numerical results are compared with experiments car ried out in the laboratory. Each plate is calculated using the self-built comput er program based on the finite element method. The Gaussian quadtrature is used for the surface integration and some difficulties concerning the choice of the o rder of this integration are discussed. To integrate the constitutive equations (the first order differential equations), and the equations of motion (the secon d order differential equations), it is necessary to use proper value of the time step. Some remarks on selection of this value are given. Density of the finite element mesh used for discretisation of the plate is studied. It was found that the number of elements has bigger influence on the quality of the results than t he number of layers used to describe the changes of stresses through the thickne ss of the plate. Finally, some comments on the choice of the model of damping ar e made. An approximate method of introduction of this factor in the calculations is presented.

 

h M.Gerigk, Modern Numerical Techniques for the Ships Safety Estimation in Critical Conditions

In this paper a method for a ship safety estimation at the preliminary stage of design is briefly presented. Solving a few hydrostatic and dynamical problems may be taken into account using the method with special regards to the ships safety estimation in critical conditions. The critical conditions may concem the problems of survivability caused due to the cargo and/or ballast shift, waves and wind impact including the ingress of external water into the watertight compartments of a ship.
The theoretical and computational models are briefly described. Using the computational model the safety assessment may be done for the initial event and scenario development assumed. Then, either some seakeeping, stability, damage stability or survivability related characteristics should be evaluated for the risk assessment. Both the seakeeping and stability characteristics are treated as the initial conditions for the risk assessment regarding the damage stability and survivability, and it usually follows from the hazard scenario development. The risk assessment is the base for the safety estimation. This is done according to the IMO regulations.
The computational model incorporates the modern numerical techniques and is briefly described by introducing the logical structure of design system, logical structure of computational model and a few application methods used. The model enables to estimate the safety combining the influence of the hull form parameters, arrangement of internal spaces, loading condition including both the cargo distribution and permeability and impact of exciting forces. The exciting forces may follow from both the external and internal sources. And they are as follows: waves, wind and cargo and ballast shift.

 

h T.Matuszek and H.Olszewski, Liquid Energy Analysis for the Spray Nozzle Jet Parameters Optimisation

In the paper numerical analysis of the liquid energy regarding the spray nozzle jet parameters optimisation for a cleaning process has been presented. Special attention has been paid to the comparison between the energy contained in the stream of liquid going out from a nozzle, and the energy needed to remove fouling at the surface. In the example a lot of parameters influencing those energies have been taken into account. It has been found that the proposed analysis of the liquid energy and the energy needed for cleaning is an adequate description of geometry and parameters of equipment and devices, especially in the Clean In Point (CIP) systems.

 

h A.Witkowska, J.Rybicki, R.Laskowski, G.Mancini, S.Feliziani, W.Alda, Short- and Medium-Range Order in Bismuth-Silicate Glasses: A Molecular Dynamics Study

We report on the results of classical molecular dynamics (MD) simulations of str ucture of amorphous 15 Bi2O3 85 SiO2 [% mol] and 40 Bi2O3 60 SiO2 [% mol], and their totally reduced forms, 15 Bi2 85 SiO2 [% mol], and 40 Bi2 60 SiO2 [% mol], respectively. The simulations have been perfo rmed in the isobaric-isoenthalpic ensemble, using a two-body interaction potential. The set of the potential parameters was constructed as a suitable com bination of the parameters which were previously proposed for pure Bi2O3, and SiO2. Both unreduced, and reduced sy stems were initially prepared as well equilibrated hot melts, and then slowly co oled down to 300K. The structural information from the MD simulations was obtained from radial and angular distribution functions, static structural factors, Voronoi polyhedra sta tistics, and ring analysis.
The simulation results can be summarised as follows. In unreduced glass with 15% [mol] Bi2O3 contents, the silicon structural units (mainly regular tetrahedra) form continuous network, whereas in 40% [mol] Bi2O3 glass these units are disconnected. In both unreduced systems Bi ions have mainly six-fold oxygen co-ordination, and no dominating structural unit can be individuated. However, the distorted bismu th units form a continuous network. In both totally reduced glasses (15% Bi2 85% SiO2, and 40% Bi2 60% SiO2 [% mol]), the silica network is built entirely from corner shari ng SiO4 tetrahedra. The structure of the silica subsystem is similar to that of pure *-SiO2. After the reduction, the Bi-Bi co-ordination significantly increases, whereas the first neighbour distance decreases. Moreover, partial static structural fact ors for Bi-Bi pairs indicate that the medium-range order in reduced glasses exhi bits greater periodicity than in unreduced glasses. Neutral Bi atoms form small clusters within the silica matrix.

 

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