This volume is the current 43-rd thematic issue of the Riga Technical University (RTU)
collection of scientific articles "Boundary Field Problems and Computer Simulation"
in series "Computer Science". The collection continues (since 1999, with slightly
changed title) the lasting international series "Boundary Field Problems and Computers",
issued by RTU since 1966.
Scientific papers regarding simulation results and methodics of model formulation in
hydrogeology, electrodynamics, hydrodynamics, ecology, optical waveguides, signal
processing, and insurance models.
The volume may be of importance to specialists and students interested in computer
simulation of various environmental phenomena.
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(C) Riga Technical University, 2001
Editorial Board*):
A.Spalvins, Dr.sc.ing., RTU - Editor-in Chief
J.Bleiers, Dr.sc.ing., RTU
M.Antimirov, Dr.hab.phys., RTU
P.Greber, Dr.hab.ing., Dresden Institute of Technology
R.Thunvik, Dr.hab.ing., Royal Institute of Technology (Stockholm)
A.Majewski, Dr.hab.ing., Warsaw University of Technology
R.Janbickis, M.sc.ing., RTU - Secretary
*) Address:
Riga Technical University,
Environment Modelling Centre
1 Meza Street, Riga, LV-1048, Latvia
Phone: +371 7089511; Fax: +371 7089531
E-mail: emc@egle.cs.rtu.lv
URL: http://www.rtu.lv/www_emc/emc_home.htm
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Contents
- Kaczmarek T. and C. Kaczmarek:
A NONLINEAR LIGHTGUIDE AS A TRANSMISSION MEDIUM OF ULTRASHORT CHIRPED
HYPERBOLIC SECANT SHAPE AND GAUSSIAN PULSES (Page 5)
Abstract (HTML) | Full Text (PDF; 373KB)
- Kaczmarek Z.:
WAREFORM RECONSTRUCTION OF IMPACT FORCE USING A FREQUENCY DOMAIN
TECHNIQUE AND ONE-POINT STRAIN MEASUREMENT (12)
Abstract (HTML) | Full Text (PDF; 323KB)
- Duong N.X. and V.K. Krutch:
COMPUTATIONAL MODELLING OF FLOW AND POLLUTION TRANSPORTATION IN OPEN
CHANNEL WITH COMPLICATED GEOMETRY AND BOTTOM RELIEF (19)
Abstract (HTML) | Full Text (PDF; 304KB)
- Kolishkin A. and I. Volodko:
ON THE LINEAR STABILITY OF UNSTEADY FLOW IN A PLANE CHANNEL (26)
Abstract (HTML)
- Antimirov M. and I. Dzenite:
BOUNDARY SHELLS OF HYDROGEOLOGICAL MODELS AS INTERPOLATION DEVICES (32)
Abstract (HTML)
- Antimirov M. and I. Dzenite:
EXACT SOLUTION OF THE PROBLEM ON THE VECTOR POTENTIAL OF A WIRE
OF FINITE LENGTH WITH CURRENT BY INTEGRAL TRANSFORMS (40)
Abstract (HTML)
- Ligere J.:
ON A DEPENDENCE BETWEEN THE SMOOTHNESS OF THE BOUNDARY VELOCITY
OF THE FLUID AND THE FULL PRESSURE FORCE AT THE ENTRANCE OF THE REGION (48)
Abstract (HTML)
- Matvejevs An. and Al. Matvejevs:
JOINT LIFE AND LAST SURVIVOR BENEFITS FOR MARRIED COUPLES (59)
Abstract (HTML)
- Bleiers J. and J. Lavendels:
CONTROL OF BACKGROUND TASKS IN THE HARD REAL TIME SIGNAL
PROCESSING ENVIRONMENT OF TELECOMMUNICATION SYSTEMI> (69)
Abstract (HTML)
- Bleiers J., Kalejs A., Linis G. and N. Veselis:
DSP-BASED TESTING OF COMPUTER TELEPHONY SYSTEMS
(74)
Abstract (HTML)
- Burovs G.:
TOPOLOGICAL MODELS OF INFORMATION TECHNOLOGIES OF DISCRETE
PROCESSING OF SIGNALS
(82)
Abstract (HTML)
- Burovs G. and A. Varslavs:
ALGORITHMS OF IDENTIFICATION OF REGRESSIVE MODELS PARAMETERS
WITH USE OF THE MAKING OPERATOR (94)
Abstract (HTML)
- Burovs G., I. Iltins and M. Iltina:
SUPPORT OF REAL TIME TASKS IN THE SIGNAL PROCESSING ENVIRONMENT
OF TELECOMMUNICATION SYSTEM (101)
Abstract (HTML)
- Spalvins A., Slangens J., Janbickis R., Lace I., Eglite I., Skibelis V. and A. Macans:
KNOW - HOW TECHNOLOGIES DEVELOPED FOR MODELLING
HYDROGEOLOGICAL PROCESSES (109)
Abstract (HTML) | Full Text (PDF; 261KB)
- Spalvins A., Slangens J., Janbickis R. and I. Lace:
MODELLING OF DISSOLVED OIL PRODUCT MIGRATION IN GROUNDWATER
AT THE FORMER RUMBULA AIRBASE, LATVIA (124)
Abstract (HTML)
| Full Text (PDF; 149KB)
| Fig.1 (PDF; 345KB)
| Fig.2 (PDF; 221KB)
| Fig.3 (PDF; 405KB)
- Spalvins A., Slangens J., Janbickis R. and I. Lace:
NEW SUBSIDIARY TOOLS FOR THE MODELING SYSTEM REMO (138)
Abstract (HTML) | Full Text (PDF; 177KB)
- Spalvins A., Slangens J., Janbickis R., Lace I. and P. Hein:
MODELLING OF GROUNDWATER FLOW DYNAMICS AND CONTAMINANT
TRANSPORT PROCESSES FOR THE BERNAU AREA, GERMANY (143)
Abstract (HTML)
| Full Text (PDF; 185KB)
| Fig.1 (PDF; 254KB)
| Fig.2 (PDF; 148KB)
| Fig.4 (PDF; 376KB)
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Abstracts of papers
Kaczmarek T. and C. Kaczmarek
A nonlinear lightguide as a transmission medium of ultrashort chirped hyperbolic secant shape and Gaussian pulses
Kielce University of Technology, Institute of Telecommunications and Photonics, Kielce, Poland
Warsaw University of Technology, Institute of Electronic Systems, Warszawa, Poland
ABSTRACT: The propagation of ultrashort chirped hyperbolic secant shape and Gaussian pulses
in a nonlinear lossless fiber is considered. Nonlinear Schrödinger Equation is solved numerically
for complex ini-tial conditions using the Split-Step Fourier and the Beam Propagation Methods.
It is demonstrated that a hy-perbolic secant shape pulse is less sensitive to destructive
influence of the initial chirp than a Gaussian pulse.
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Kaczmarek Z.
Waveform reconstruction of impact force using a frequency domain technique and one-point strain measurement
Kielce University of Technology, Institute of Electrotechnics and Metrology, Kielce, Poland
ABSTRACT: In the paper a transformational impact force reconstruction method is presented,
which fea-tures a one-point strain measurement in a mechanical transducer. To determine the
spectral transmittance of a section of the mechanical transducer necessary in the reconstruction process,
strain waves propagating in the transducer are used: the incident, and the first reflected one, created
by the impact. Restrictions concern-ing the impact duration as well as the strain gauge localization
on the mechanical transducer are given, which assure the non interference of the above mentioned waves
in the strain gauges. The reconstruction results of impact force waveforms generated during impacts of
steel spheres in the front face of a steel bar are pre-sented. The consistency of the obtained
reconstruction results with the Hertz Impact Theory with respect to the duration and amplitude of the
impact force was evaluated.
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N.X. Duong & V.K. Khrutch
Computational modelling of flow and pollution transportation in open channel
with complicated geometry and bottom relief
Dnipropetrovsk National University, Dnipropetrovsk, Ukraine
ABSTRACT: A 2-D depth-average computational model based on the shallow water theory including
as-pects of non-uniform bottom relief has been developed. An explicit differential scheme formulated
on the "one-sign" transport matrixes has been used for solving the boundary problem of non-conservative from.
Corrections to the differential scheme are proposed to provide good agreement with available basic
solutions of the equations system. In couple with the flow module, the diffusive-transport equation
has also been solved respectively at each time step to predict the depth-average concentration or
surface concentration of pollution spreading in a channel that contained islets.
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Kolishkin A. and I. Volodko
On the linear stability of unsteady flow in a plane channel
Institute of Engineering Mathematics, Riga Technical University, Latvia
ABSTRACT: Unsteady flows of incompressible fluid under abrupt change in pressure and flow rate
are of great interest to engineers. Such flows often occur in applications. The transient flow of
a viscous incom-pressible fluid during short time interval followed by a sudden change of total
fluid flux is studied in the pre-sent paper. Exact analytical solutions for flow velocity in a
plane channel are found by the method of Laplace transform. The analysis of the solution indicates
that there are two typical time scales related to the transient fluid flow: short (convective)
time scale and long (diffusive) time scale. Therefore the solution is presented in two useful
forms suitable for engineering calculations for short values of the time (in terms of the
complemen-tary error functions) and for long values of the time (in terms of an infinite series).
The calculated velocity pro-files for short times are similar to those obtained by other authors
experimentally and numerically.
Linear stability of unsteady flow in a plane channel is investigated by quasi-steady approach.
It is shown that the critical Reynolds numbers decrease considerably on a short (convective) time scale,
therefore the additional energy dissipation due to formation of secondary flows takes place in transient flows.
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Antimirov M. and I. Dzenite
Evaluation of new classes of definite integrals and its applications to eddy current testing
Institute of Engineering Mathematics, Riga Technical University, Latvia
ABSTRACT: New classes of definite integrals are evaluated in closed form by means
of divergent integrals, which converge in the sense of Abel (Antimirov et al. 1993).
The integrands of these integrals are either combination of irrational and trigonometric
functions or combination of irrational and Bessel functions. The applications of particular
cases of these integrals for closed form solutions of some eddy current testing prob-lems
are considered.
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Antimirov M. and I. Dzenite
Exact solution of the problem on the vector potential of a wire of finite length with current by integral transforms
Institute of Engineering Mathematics, Riga Technical University, Latvia
ABSTRACT: Exact solution for the problem of spreading of electromagnetic waves from
a wire of finite length is obtained in the exact formulation without using the dipole approximation.
Current in the wire is varied according to the harmonic law. Solution for the vector potential is
obtained in the form of integral of an elementary function. The result obtained is used to
construct a solution for the problem of spreading of electromagnetic waves from a rectangular
frame with current. The solution for the problem of spreading of electromagnetic waves from
a linear harmonic oscillator is obtained by using the dipole approximation in the exact
solution found in the present paper.
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Ligere J.
On a dependence between the smoothness of the boundary velocity of the fluid and the full pressure force at the entrance of the region
Institute of Engineering Mathematics, Riga Technical University, Latvia
ABSTRACT: Analytical solution of two problems on inflow of the viscous fluid through
the plane split of finite width or through the round hole into half-space is obtained
in the Stokes approximation. The velocity of the fluid at the entrance of the region is
given ether as a constant (i.e. as a function with finite jump) or as a parabola (i.e. as
the continuous function). It is shown that in the first case the full pressure force at
the en-trance of the region is equal to infinity and consequently such flow is physically unreal.
In the second case the full pressure the entrance of the region has finite value. In the case
of the plane split the solution is ob-tained in terms of elementary functions but in the case
of round hole the solution is obtained in the form of integrals involving Bessel functions.
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Matvejevs An. and Al. Matvejevs
Joint life and last survivor benefits for married couples
Riga Technical University, Riga, Latvia
ABSTRACT: Three kinds of the insurance policies for the net premium calculation for married
couples are considered. The net premium equation principle is used in all premium calculations.
The particular quality of the additional pension assurance is the individual form of its undertaking
and the limitation of annual (monthly) pension payments. Due to this fact the biggest interest to the
individual insurance show people after age 40-45 years, when the insurance premium rates are so high
that most people can't buy such policies. So, the discussed form of the joint life insurance could be
proposed to the participant of the pension plan when he or she is reached the pension age and wants
to buy the life insurance policy for the accumulated capital of pension.
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Bleiers J.1) and J. Lavendels2)
Control of background tasks in the hard real time signal processing environment of telecommunication system.
1) Riga Technical University, Environment Modelling Centre, Latvia
2) Riga Technical University, Software Department, Latvia
ABSTRACT: A multiprocessor signal processing environment for telecommunication system where
multiple signal processing back ground tasks are supported by every DSP is discussed.
Two types of back ground control procedure are observed. Interrupting service routine
includes unvarying block of executing algo-rithms and links for parallel functions.
Each of control methods can be used in signal processing software.
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Bleiers J.1), A. Kalejs1), G. Linis2) and N. Veselis2)
Closed form solutions of some eddy current problems
1) Riga Technical University, Riga, Latvia
2) Institute of Mathematics and Computer Science of the University of Latvia, Riga, Latvia
ABSTRACT: Many new communication applications become reality thanks to integration
of computer and telecommunication technologies. A distinctive key element in computer-based
communication systems is an additional switching bus. Several different standards exist
today for computer telephony buses. Testing and evaluation of communication systems built
to the computer telephony standards is an important aspect of the development.
The presented article describes main particularities, basic requirements and timing
evaluations of testing in computer telephony systems with H.100 and MVIP90 standard switching buses.
The computer telephony bus tester is designed using a digital signal processor and integral
bit error tester devices. The general principles of testing methods, block diagrams of tester
equipment and software architecture are discussed.
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Burovs G.
Topological models of information technologies of discrete processing of signals
Riga Technical University, Institute of Information Technology, Latvia
ABSTRACT: The application of topological principles in models of signals discrete
processing is considered. In them the information mapping operators with properties of
topological invariancy are used (Burovs 2001). The optimization of identification models
is carried out at the expense of parameters adjustment of the information mapping operators.
They are formed of regressive models parameters and dynamic discrete parameters.
It allows to strengthen the quasi-isometric models property and to increase accuracy
of the signals parameters estimation. The numerical experiment of processing of 6 order
dynamic process has confirmed efficiency of the offered information technologies.
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Burovs G.1) and A. Varslavs2)
Algorithms of identification of regressive models parameters with use of the making operator
1) Riga Technical University, Institute of Information Technology, Latvia
2) Unibank, Riga, Latvia
ABSTRACT: The identification task of analog dynamic objects and processes with use of
regressive models (RM) is examined. The regression parameters are calculated by the decision
of difference equations systems. They turn out as dimensionless values. They have a discrete nature,
as depend on ways of discrete processing of analog signals and of their access period ?.
The constraint of regression parameters with the physical characteristics of object is
shown in the ciphered kind. Therefore they are difficult for using in tasks of technical
objects control and optimization of economic processes. In work the transformation
algorithm of regression parameters RM in estimates of the object analog operator is developed.
Last more precisely present the object physical properties. The algorithm is generated as mapping
operation of the generating discrete operator of RM (GORM) in the analog operator.
It is the inverse type task. Therefore regular properties of algorithm are sensitive
to influence of the interfering factors. The reasons of their infringements are investigated.
The alternative approached algorithm is developed. With the purposes of reliability increase
of identi-fication estimates is offered to share with exact algorithm.
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Burovs G.1), I. Iltins2) and M. Iltina2)
Statistical regularization of identification algorithm
1) Institute of Information Technology, Riga Technical University, Latvia
2) Institute of Engineering Mathematics, Riga Technical University, Latvia
ABSTRACT: The use of identification algorithms (IA) described in Iltins & Burov (2000)
often leads to solution of badly determined equation systems. It creates an unpredictable
influence of errors to the calculated result. There is described a possibility to improve
the stability of the computing process using the statistical regularization in it.
It is a variant of the well-known Monte-Carlo method. As it is shown in the article,
it is possible to use IA in cases, where it would not be possible to use them earlier
without the help of the statistical regularization method.
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Spalvins A., Slangens J., Janbickis R., Lace I., Eglite I., Skibelis V. and A. Macans
Know - how technologies developed for modelling hydrogeological processes
Environment Modelling Centre, Riga Technical University, Latvia
ABSTRACT: Since 1993, the team of the Environment Modelling Centre (EMC) of the
Riga Technical University has been active in developing special software for creating
hydrogeological models (HM). These new tools have been applied in conjunction with
commercial ones for solving practical problems regarding drink-ing water supply and
dynamics of contaminated groundwater. The new software tools and main projects EMC
has dealt with are considered.
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Spalvins A., Slangens J., Janbickis R. and I. Lace
Modelling of dissolved oil product migration in groundwater at the former Rumbula airbase, Latvia
Environment Modelling Centre, Riga Technical University, Latvia
ABSTRACT: To estimate the risk caused by migration of dissolved in groundwater
jet fuel products to the Daugava river, the 3D-hydrogeological model (HM) has been created
for the former Rumbula airbase. The nearby Getlini waste disposal site is also included.
Due to a bioremediation, only a small part of fuel reaches Daugava. Contaminants coming
from Getlini are mostly caught by two ditches falling into this river.
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Spalvins A., Slangens J., Janbickis R. and I. Lace
New subsidiary tools for the modeling system REMO
Environment Modelling Centre, Riga Technical University, Latvia
ABSTRACT: New subsidiary software tools have been developed for the modeling system REMO.
These tools may be used for formulating hydrogeological models (HM) and for computing balance
of 3D groundwater flows.
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Spalvins A.1), J. Slangens1), R. Janbickis1), I. Lace1) and P. Hein2)
Modelling of groundwater flow dynamics and contaminant transport processes for the Bernau area, Germany
1) Environment Modelling Centre, Riga Technical University, Latvia
2) Hydrogeological company INGAAS GmbH, Germany
ABSTRACT: The Bernau place in Germany is heavily polluted with tetrachlorethane.
To help in solving the remedy problem of the place, a system of hydrogeological models
(HM) has been developed by the Environment Modelling Centre (EMC) of the Riga Technical University.
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