ENGINEERING TRANSACTIONS
ROZPRAWY INŻYNIERSKIE
A QUARTERLY JOURNAL
Abstracts of papers for
vol. 48, no. 1 (2000)
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Next issue
vol. 48, no. 2 (2000)
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- L. Płoniecki, W. Trąmpczyński, W. Gierulski, J. Cendrowicz, K. Sokołowski:
Computer control system for heavy machine features motion and its
application for automatic generation of cutting tools trajectories according
to the given criteria
- J. Banaszak and S.J. Kowalski:
Stresses in viscoelastic sphere dried convectively
- A. Ciarkowski:
Improved representation for the first precursor in the Lorentz medium
- V. Bozhydarnyk:
On the problem of bending of transversally isotropic plates
- A. Foryś and J. Snamina:
Objective functions in monocriterial and multicriterial optimizations
problems against a loss of dynamic stability
- L. Płoniecki, W. Trąmpczyński, W. Gierulski, J. Cendrowicz, K. Sokołowski:
Computer control system for heavy machine features motion and its
application for automatic generation of cutting tools trajectories according
to the given criteria
- The computer control system for heavy machine (loaders, excavators) fixtures
motion is presented and discussed in the paper. It enables the automatic
generation of cutting tool (buckets) trajectories to fulfil the assigned
criteria, for example the minimum unit energy criterion or the maximum
disposable force criterion. The performance of the system was investigated
using the laboratory stand built in semitechnical scale and the model
cohesive soil. The tool shape in the stand corresponds to the shape of the
bucket of the Waryński excavator K-111.
Contents
- J. Banaszak and S.J. Kowalski:
Stresses in viscoelastic sphere dried convectively
- The deformations and the drying-induced stresses in a saturated porous
elastic and viscoelastic sphere dried convectively are analysed. The
considerations are confined to'the constant drying rate period. The solution
of the problem is obtained using both the Laplace transformations and the
numerical finite difference method. The drying experiment was performed on
spheres made of three different clay sorts in order to validate the results
obtained by numerical analysis. The results obtained are presented in
graphical form.
Contents
- A. Ciarkowski:
Improved representation for the first precursor in the Lorentz medium
- The best methods available nowadays for modelling the propagation of very
short (duration less than 100 fs), ultrawideband electromagnetic signals in
physical media are the asymptotic ones. Numerical methods loose their
traditional leadership due to their inability to handle rapid oscillations
of the propagating signal. Therefore it is important to create accurate
asymptotic models of propagation which can be used as a reference. In this
paper a new description of primary precursor in a dispersive Lorentz medium
is given, based on uniform asymptotic theory of evaluation of integrals and
a new approximate solution to the distant saddle point equation. The new
representation of the signal in the medium is illustrated graphically and
compared with the Oughstun-Sherman representation.
Contents
- V. Bozhydarnyk:
On the problem of bending of transversally isotropic plates
- The possibility of analysis of transversally isotropic plates of medium
thickness by means of representing the displacements in the form of finite
series along the lateral coordinate is examined. Differential equations of
the twelfth order are derived. Conditions on the plate boundaries are
determined. Examples of numerical calculations are presented. The article is
a sequel to papers [11-13].
Contents
- A. Foryś and J. Snamina:
Objective functions in monocriterial and multicriterial optimizations
problems against a loss of dynamic stability
- The paper concerns the specification and comparison of numerical examples of
optimization of beams in the state of periodic parametric resonance with
respect to different measures of the phenomena considered, i.e., with respect
to different optimization criteria - some objective functions in
monocriterion and multicriterial optimization. A formulation of monocriterion
and multicriterial optimization problems for mechanical elements, subjected
to a parametrically exciting force periodic in time, is given.
In multicriterial optimization the scalar objective functions characterizing
the parametric resonance are introduced. The paper deals with the problems
of finding the control function - function of the shape (the area of
cross-section of the beam) which maximizes or minimizes the objective
functions under the constraint of constant volume. In some cases the
optimization problems under conditions of parametric resonance reduce to
the optimization problems with respect to natural frequency. The examples of
parametric optimization against loss of stability are solved and analysed.
Contents
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