2002_fascicula3
http://arthra.ugal.ro/handle/123456789/536
Mon, 02 Aug 2021 08:12:12 GMT2021-08-02T08:12:12ZImperfect Data in Database Context. How are they Stored in Extended Relational Databases?
http://arthra.ugal.ro/handle/123456789/3747
Imperfect Data in Database Context. How are they Stored in Extended Relational Databases?
Tudorie, Cornelia
Building a more accurate reality model requires taking into account imperfect
information present in our knowledge and language. This paper presents several aspects of
data imperfection in the database context and the appropriate frameworks for their
treatment. It’s concluding that null value, possibility distribution and probability theory are
the best solutions to represent incomplete, imprecise and uncertain data. For each of these
problems there are some relational model extension proposals, including data
representation and relational algebra.
The Annals of "Dunarea de Jos" University of Galati Fascicle III, 2002
Tue, 01 Jan 2002 00:00:00 GMThttp://arthra.ugal.ro/handle/123456789/37472002-01-01T00:00:00ZModeling, Identification and simulation of a Lighting Control System
http://arthra.ugal.ro/handle/123456789/3746
Modeling, Identification and simulation of a Lighting Control System
De Keyser, Robin; Ionescu, Clara Mihaela
This paper presents the results of the first phase in the design of a control
system for closed-loop regulation of the light amount in office-building rooms. This
project is a joint development of Ghent University and Niko Lighting Company. The
final objective is to regulate the light amount in a room at a constant level, irrespective
of the disturbances from outside such as weather conditions. The main benefits would
be a higher level of comfort and a continuous saving of energy. The system will be
made commercially available as a micro-controller-based intelligent light-switch. The
first phase in the project, described in this paper, is the modelling of the lighting system
and the identification of a dynamic model of the system. A simulator, based on the
obtained model, is also presented and validated. The simulator will be used in the
second phase of the project to design, tune and test the controller and to evaluate the
closed-loop system performance under varying environmental conditions (robustness
tests).The project is rather challenging because undesired interaction might occur
between separately controlled zones in a big room.
The Annals of "dunarea de Jos" University of Galati Fascicle III,
Tue, 01 Jan 2002 00:00:00 GMThttp://arthra.ugal.ro/handle/123456789/37462002-01-01T00:00:00ZDetecting the Liquid core in Continuous Casting Slabs by Load Torque Estimation in Unbending Zone
http://arthra.ugal.ro/handle/123456789/3745
Detecting the Liquid core in Continuous Casting Slabs by Load Torque Estimation in Unbending Zone
Bivol, Ion; Roşu, Emil; Ceangă, Emil
The development in continuous casting process has been strongly dominated
by the demands of quality improvement and reduced costs for steel products in recent
years. To achieve these goals consideration has been given by increasing the velocity of
casting process. In that case a portion of a cross section of the slab are still licked in the
unbending zone. Information about the deformation, stress and strain in solid shells is
quit important in terms of the cost quality. These information are obtained by load
torque estimation using the electrical quantities of the drive system for the unbending
zone. A sensor less drive system with induction motor is considerate. The electrical
drive systems are controlled in torque and speed. The measurements of voltage and
current components and the imposed speed are the inputs for the real time load torque
estimator. The estimated load torque is compared with the calculated maximal load
torque for the entirely solidified slab state. From this comparison results the thickens
of the slab licked zone.
The Annals of "Dunareade Jos" University of Galati Fascicle III, 2002
Tue, 01 Jan 2002 00:00:00 GMThttp://arthra.ugal.ro/handle/123456789/37452002-01-01T00:00:00ZA Diferent Approach in the Parameters' Identification of a Jfet Using Genetic Algorithms
http://arthra.ugal.ro/handle/123456789/3744
A Diferent Approach in the Parameters' Identification of a Jfet Using Genetic Algorithms
Belea, Radu; Beldiman, Liviu
The genetic algorithms are developing in three directions: the genetic
algorithms theory, the genetic algorithms programming and the study of the problems
that can be solved with genetic algorithms. In this paper it is presented a study on the
identification of the parameters of a JFET (Junction Field Effect Transistor). The
problem is very exciting because the JFET has two mathematical models: an empirical
one, and an analytic one, both of the models being nonlinear in parameters. In a
parametric identification problem, it is minimized the distance between an experimental
data set and an analytical function, which represent the mathematical model of the
studied phenomenon. Basically, a genetic algorithm can maximize a fitness function,
which is a positive defined function whose maximum is searched. However, genetic
algorithms can also solve minimum problems, on condition that to the minimum
problem can be applied an algebraic transform or a rank based transform in a maximum
problem.
The Annals of "Dunarea de Jos" University of Galati Fascicle III, 2002
Tue, 01 Jan 2002 00:00:00 GMThttp://arthra.ugal.ro/handle/123456789/37442002-01-01T00:00:00Z