ENGINEERING TRANSACTIONS
ROZPRAWY IN¯YNIERSKIE
A QUARTERLY JOURNAL
- W. Bodaszewski:
Algorithms of the method of statically admissible discontinuous stress fields (SADSF)
Part IV. Inegration of fields around nodes into planar complex fields
- Wei-Chiang Wu:
Joint DOAs-timings estimation for uplink DS/CDMA communication
system based on ESPRIT-MUSIC algorithm
- S.P. Gadaj, E.A. Pieczyska, W.K. Nowacki:
Stress and temperature changes of polymer woven belts subjected
to mechanical loading
- Y. Lahiouel, K. Chaoui, L. Khezzar,
A. Haddad, Z. Azari:
Optimisation of water distribution networks design by minimizing
the total length
- A. Mahdjoub, L. Zighed:
New designs for graded refractive index antireflection coatings
- I. Sielamowicz:
Experimental analysis of granular material flows using the
technique of digital particle image velocimetry
- W. Bodaszewski:
Algorithms of the method of statically admissible discontinuous stress fields (SADSF)
Part IV. Inegration of fields around nodes into planar complex fields
- Summary of Part IV: In this part of the paper, the author presents
a general concepts of algorithms of two program modules that
integrate component fields around nodes into planar complex
fields. The first module, the auxiliary one called module
C, is used to construct the objects of incidence of the
regions and the lines that are generated automatically, based on
a freehand sketch of the field structure - which can be drawn,
for example, on the monitor screen by means of a mouse. The proper
integration, however, is performed by the second module, called
module B, which utilises both the incidences brought in
by module C, and the solutions of component systems of
stress discontinuity lines around nodes - the latter obtained
using the module called A. The individual partial
problems are still demonstrated here, and the example of the
already known solution of the field type f90 is used for this
purpose.
- Attention is also focussed on the effects of partial autonomy that
are revealed in the integration problems. These effects consist in
decoupling of two systems of conditions: the one defined on
geometrical parameters, and that based on stress parameters. The
conditions are utilised, for example, in the algorithms of the
application version software for finding particularly complicated
fields that could contain as much as several dozens of homogeneous
regions. An example of such a solution is shown along with its
application to forming complex elements of a structure. The
example confirms once again great potential of the SADSF method.
Contents
- Wei-Chiang Wu:
Joint DOAs-timings estimation for uplink DS/CDMA communication
system based on ESPRIT-MUSIC algorithm
- This paper proposes a blind algorithm to jointly estimate the
direction-of-arrivals (DOAs) and timings (time-delays) in
asynchronous DS/CDMA multiuser communication system. Making use of
the space-time characteristics of an antenna-array DS/CDMA model,
it is shown that the multiple signal classification (MUSIC)
algorithm and the estimation of signal parameters via rotational
invariance (ESPRIT) technique that are widely used in array signal
processing, can be applied to extract the direction-of-arrival
(DOA) and timing information. Multiuser timing estimation is based
on a MUSIC-like algorithm while ESPRIT is applied to estimate the
DOA for each user. More specifically, the proposed algorithm is
computationally efficient since it reduces the multiuser
parameters' estimation problem to a set of single-user's parameter
estimation problems. It requires only two eigendecomposition (EVD)
and several (depending on the number of subscribers)
one-dimensional searches. Computer simulations under different
scenarios not only show the accuracy but also demonstrate that the
proposed ESPRIT-MUSIC based DOA-timing estimator is near-far resistant.
Contents
- S.P. Gadaj, E.A. Pieczyska, W.K. Nowacki:
Stress and temperature changes of polymer woven belts subjected
to mechanical loading
- The experimental results obtained during low-cyclic tensile
deformation of woven polyamide belts were presented. The
temperature and mechanical characteristics of tension, low-cyclic
loading, unloading and stress relaxation processes were found. The
temperature changes accompanying the woven belt deformation turned
out to differ from those, which were found for the sheet polyamide
solid specimens. Such temperature results were caused both by the
effects of the material as well as by the effects of the fibrous
belt structure. The maximal temperature increments observed during
subsequent cycles of loading reached 10 K. The cycling test
actually did not affect the stress-strain characteristics of the
belts, so it can be concluded that the used belt structure ensures
their safe application for various cyclic loadings.
Contents
- Y. Lahiouel, K. Chaoui, L. Khezzar,
A. Haddad, Z. Azari:
Optimisation of water distribution networks design by minimizing
the total length
- The aim of the present work is to establish a new algorithm for
the optimization of the design of water distribution networks. The
proposed algorithm makes it possible to connect the nodes and the
sources using the shortest path to obtain a final looped
configuration. A novel method, the "minimal length algorithm",
is proposed. It uses the advantages of existing methods and
exceeds their limitations. Some of the well-known existing methods
are the shortest path algorithm, the minimum spanning tree
algorithm and a novel method published previously. The developed
algorithm is implemented into a user-friendly interactive computer
program which allows the design of looped systems with minimal
length ensuring least cost, reliability of the network and hence
the availability of water.
Contents
- A. Mahdjoub, L. Zighed:
New designs for graded refractive index antireflection coatings
- The constant progress in thin layers technology, especially the
graded index inhomogeneous dielectrics, allows the realization of
antireflection coatings (ARC) that are less sensitive to thickness
and to the incidence angle. Graded refractive index silicon
oxynitrides are deposited by Electron Cyclotron Resonance
Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) controlled
in-situ by monochromatic ellipsometry. While avoiding the
complexity of the classical multilayer ARCs, the obtained AR
coatings permit to obtain the same performances, or furthermore to
improve the cells efficiency. Different suggested profiles are
optimized by simulation, then they are realized and characterized
by spectroscopic ellipsometry and reflectance measurement. The
photogenerated current can be enhanced by 45%, and weighted
reflectance (between 300 and 1100 nm) reduced to 5.6%. The
passivating properties of oxinitrides recommend the use of these
AR coatings on texturized surfaces. The weighted reflectance would
decrease to less than 1% and short-circuit current will thus be
enhanced by 52.79%.
Contents
- I. Sielamowicz:
Experimental analysis of granular material flows using the
technique of digital particle image velocimetry
- This paper presents the results of experiments of granular flows
carried out for two configurations - in a plane model with
vertical walls and in a wedge-shaped model. Both models were built
of plexiglass and replicate the geometry of a silo. The flow
processes of central and eccentric discharge were recorded by a
high resolution camera (SensiCam) through the transparent walls of
the models. PIV measurements allow to obtain the following data of
the flow: the plug flow zone evolution, velocity magnitude
contours, velocity fields, velocity distributions on certain
levels in the models, traces of individual particles. Local
deformations and stresses in the material may be also determined.
The models were filled in a natural way through a pipe placed
vertically in the symmetry axis above the models or through a
sieve. In the case of the plane model, three cases of eccentric
flows were investigated. Dynamic behaviour of the flowing
materials recorded by the new measurement technique DPIV, commonly
used in fluid mechanics, now applied for granular material flows,
is analyzed. Uniform and repeatable packing of the materials with
no particle segregation was obtained. Three different grain types
were used in the experiments (amaranthus, flax-seed and
buckwheat). These grains represent different physical properties
and exhibit the phenomenon of static electricity of the materials
when flowing and sliding over plexiglass.
Contents
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