|
Issue
1, Volume 6, January 2011
Title of the Paper:
Simulation of Adaptive Control Applied on Tubular Chemical Reactor
DOWNLOAD
FULL PDF
Authors:
Jiri Vojtesek, Petr Dostal
Abstract: Simulation has a big importance nowadays when the speed of computers
grows rapidly and the price is on the other hand decreasing. The paper is
focused on the simulation of the steady-state and dynamic behaviour of the
nonlinear system represented by the tubular chemical reactor with the
co-current and countercurrent cooling in the jacket. These analyses are then
used for the choice of the suitable control strategy. The adaptive controller
used here is based on the choice of the External Linear Model as a linear
representation of the originally nonlinear system parameters of which are
identified recursively. The polynomial method together with spectral
factorization and pole-placement method used in control synthesis satisfies
the basic control requirements. The resulted hybrid controller provides good
control results although the system has strongly nonlinear behaviour.
Keywords:
Tubular chemical reactor, Adaptive control, Recursive identification,
Polynomial approach, External Linear Model
Title of the Paper:
Study of Non-Stationary Heat Conduction in a Plane Plate for Symmetric and
Asymmetric Problem
DOWNLOAD
FULL PDF
Authors:
Hana Charvatova, Dagmar Janacova, Karel Kolomaznik
Abstract: In the paper we deal with study of the problems of non-stationary
heat conduction in a plane plate. In the first part of paper we formulate
mathematic model for the cases of symmetric and asymmetric heating or cooling
of a solid plate. In the second part we compute various cases of temperature
fields in the plate during the mentioned process by mathematic software Maple.
Finally we present formulated mathematic models using for optimization of two
real technological operations of natural and synthetic polymers processing –
modelling of moulding of plastic material and modeling of temperature field in
wall of tanning drum by enzymatic hydrolysis.
Keywords:
Modeling, Non-stationary Heat Conduction, Plastic Moulding, Tanning Process
Title of the Paper:
Utilization of Mathematica Environment for Designing the Forecast Model of
Heat Demand
DOWNLOAD
FULL PDF
Authors:
Bronislav Chramcov
Abstract: Time series analysis and subsequent forecasting can be an important
part of a process control system. By monitoring key process variables and
using them to predict the future behavior of the process, it may be possible
to determine the optimal time and extent of control action. We can find
applications of this prediction also in the control of the Centralized Heat
Supply System (CHSS), especially for the control of hot water piping heat
output. Knowledge of heat demand is the base for input data for the operation
preparation of CHSS. The course of heat demand can be demonstrated by means of
the Daily Diagram of Heat Supply (DDHS) which demonstrates the course of
requisite heat output during the day. This diagram is of essential importance
for technical and economic considerations. The aim of paper is to give some
background about analysis of time series of heat demand and identification of
forecast model using Time series package which is integrated with the Wolfram
Mathematica environment. The paper illustrates using this environment for
designing the forecast model of heat demand in specific locality.
Keywords:
Prediction, District Heating Control, Box-Jenkins, Control algorithms, Time
series analysis, modelling
Issue
2, Volume 6, April 2011
Title of the Paper:
A Study of Entropy Generation Minimization in an Inclined Channel
DOWNLOAD
FULL PDF
Authors:
Dalia Sabina Cimpean, Ioan Pop
Abstract: An analysis of a mixed convection and entropy generation for a fluid
flow through porous medium, between two inclined parallel plates has been
performed. The entropy generation is estimated via an analytical solution of
the temperature and velocity profiles obtained from the mass, momentum and
energy equations governing the flow and heat transfer of the problem, with the
given conditions. The optimum values of the involved parameters at which the
entropy generation assumes its minimum is calculated. The Bejan number is also
obtained and discussed.
Keywords:
Entropy Generation, Mixed Convection Parameter, Porous Medium, Bejan number
Title of the Paper:
Experimental Identification of Arrhenius Equation Parameters for Control
Purposes
DOWNLOAD
FULL PDF
Authors:
Lubomir Macku
Abstract: In the process control area, there are a lot of systems with
nonlinear behaviour. Specific case of such nonlinear system is an exothermic
chemical reactor. The reactor nonlinearity can arise from different reasons.
One of them is the changeable reaction speed, which depends on the reactants
concentration and the in-reactor temperature. The second dependence is
described by Arrhenius equation. Knowledge of the Arrhenius equation
parameters is a key for correct mathematical model composition and also for
safe and successful control. Some possibilities of the parameters
determination are described in the literature. However, they are complicated
and not very suitable for online identification of a real process. A new
approach developed by the author is introduced in this article. The
possibility of identification the reaction rate and its temperature dependence
from a measured temperature profiles are shown. The identification method
including all necessary derivation is described. Also the results of
experimentally measured data identification are presented.
Keywords:
Rate constant, exothermic process, semi-batch reactor, identification,
simulation, control
Title of the Paper:
Study of Non-Stationary Heat Conduction in a Plane Plate for Symmetric and
Asymmetric Problem
DOWNLOAD
FULL PDF
Authors:
Hana Charvatova, Dagmar Janacova, Karel Kolomaznik
Abstract: In the paper we deal with study of the problems of non-stationary
heat conduction in a plane plate. In the first part of paper we formulate
mathematic model for the cases of symmetric and asymmetric heating or cooling
of a solid plate. In the second part we compute various cases of temperature
fields in the plate during the mentioned process by mathematic software Maple.
Finally we present formulated mathematic models using for optimization of two
real technological operations of natural and synthetic polymers processing –
modelling of moulding of plastic material and modeling of temperature field in
wall of tanning drum by enzymatic hydrolysis.
Keywords:
Modeling, Non-stationary Heat Conduction, Plastic Moulding, Tanning Process
Issue
3, Volume 6, July 2011
Title of the Paper:
Choosing Suitable Shielding Gas for Thermal Optimization of GTAW Process
DOWNLOAD
FULL PDF
Authors:
A. Moarrefzadeh
Abstract: Thermal effects of Gas Tungsten Arc (GTA) and temperature field from
it on workpiece (copper) and shielding gas type, is the main key of process
optimization for GTAW. Energy source properties of GTA strongly depend on
physical property of a shielding gas. In this paper, carbon dioxide (CO2) was
used as an alternative gas for its low cost. The basic energy source
properties of CO2 GTA were numerically predicted ignoring the oxidation of the
electrodes. It was predicted that CO2 GTA would have excellent energy source
properties comparable to that of He, Ar GTA.
Keywords:
Numerical simulation, Tungsten, Copper, Shielding gas, Argon, Helium, CO2,
GTAW
Title of the Paper:
Temperature Evolution in a WC-6%Co Cutting Tool During Turning Machining:
Experiment And Finite Element Simulations
DOWNLOAD
FULL PDF
Authors:
T. Kagnaya, M. Lazard, L. Lambert, C. Boher, T. Cutard
Abstract: The present paper focuses on thermal simulations and temperature
measurements in a cutting tool during the machining process. The experimental
studies deal with turning an AISI 1045 steel with cemented carbide insert
(WC-%6Co). During machining, transient temperatures are measured at two points
in cutting tool using the embedded thermocouple method. Three cutting force
components are simultaneously recorded. The thermal simulations are based on
the calculation of the heat flux from cutting forces and heat partition
coefficient. Results obtained by thermal simulations are in good agreement
with experimental ones.
Keywords:
turning machining, WC-%6Co, tool/chip contact, temperature, heat transfer
Title of the Paper:
Approximations of Quantum Corrected Energy-Transport Model with Non-parabolic
Energy Relaxation Time
DOWNLOAD
FULL PDF
Authors:
Ren-Chuen Chen, Jinn-Liang Liu
Abstract: An energy transport model coupled with the density gradient method
as quantum mechanical corrections has been proposed and numerically
investigated. We called it quantum corrected energy-transport model, QCET
model. This model used a parabolic approximation for the energy relaxation
time but this is often inadequate to describe advanced semiconductor
phenomena. In this paper we extend the QCET model to consider the nonparabolic
band diagrams in the sense of Kane. We get explicit expressions of energy
relaxation time involving the non-parabolic band effects. An adaptive
algorithm for solving this model is applied to solve the problem. Numerical
simulations on diodes with the length down to 30 nm using this model have been
performed and adaptive meshes are given to demonstrate the accuracy and
efficiency of the algorithm. It shows that the energy-band nonparabolicity
effect is significant for nano-scale semiconductor devices.
Keywords:
Quantum corrected energy-transport model, Energy-band non-parabolicity,
Semiconductor simulation
Issue
4, Volume 6, October 2011
Title of the Paper:
Numerical Simulation of Forest Fires Based on 2D Model
DOWNLOAD
FULL PDF
Authors:
A. A. Kuleshov, E. E. Myshetskaya
Abstract: The problem of numerical simulation of forest fires is considered. A
two-dimensional two-phase mathematical model, the numerical method and the
results of a demonstrative numerical simulation of the process of forest fire
spread are presented.
Keywords:
Forest fire, mathematical model, numerical method, numerical simulation
Title of the Paper:
The Study of Corrosion in Oil and Gas Transfer Pipeline and its Removal by
Nano-Composite Coating
DOWNLOAD
FULL PDF
Authors:
E. Noveiri, E. M. Goodarzi
Abstract: Corrosion healthy in equipment of big industries such as oil
industries as well as the quality of its transmission is an important and
basic problem which disregarding of this phenomenon causes to stop production
and consequently cost repairing. In this paper a kind of nano-composite
coating is used to prevent atmospheric corrosion and under insulation
corrosion. This coating that consist of 03 percent of acrylic resin water
based and 03 percent of nano-composite as well as the nanometer tunnel (the
thickness of tunnels is only a few nano meters) covers the surface completely,
so that there is not any microscopic space for air penetration (percolation).
In addition to the hydrophobic properties will remove the moisture from the
insulation surface. Thus this nano-coating insulation prevents from reaching
moisture oil and gas transfer pipeline, also this type of insulation is
semi-transparent. In the other hands, its space beneath is visible each time.
In order to test this nano-coating, GM0453P test this has been approved as
environmental corrosion test was used. After the first stage of test, the
surface without coverage was corroded entirely, but the coated part was tested
successfully without any effect of corrosion after 45 stages. Although there
are numerous ways and materials to create resistance against corrosion, but
insulation and anti corrosion properties aren’t considered synchronous; the
coverage used in this test includes both properties.
Keywords:
Nano-composite coating; atmospheric corrosion; under insulation corrosion; oil
and gas transfer pipeline
Title of the Paper:
Material and Heat Transfer Rate in the Gas-Lquid System
DOWNLOAD
FULL PDF
Authors:
Tatjana Mosorinac, Maja Ivanovic-Knezevic, Srdjan Pejanovic, Mihailo
Perunicic, Nevenka Boskovic-Vragolovic
Abstract: In this paper substance transfer rate in the multistage system was
investigated. Substance transfer between liquid and gas phases in a
distillation packed column with packing was examined. Substance and heat
transfer rate were examined and substance transfer coefficients were
determined. Efficiency of substance transfer were examined by height of
transfer units and volumetric substance transfer coefficients. Based on
derived mathematical model the total height of transfer units and individual
height of transfer units for the liquid and gas phases were determined. The
investigation was performed by computer simulation and experiments. Several
correlation models for height of transfer units and substance transfer
coefficients were studied.
Keywords:
Multistage system, height of transfer units, substance transfer coefficient,
binary system, distillation column
|
