Abstract: Modernizing legacy applications is the key issue facing IT managers today because there's enormous pressure on organizations to change the way they run their business to meet the new requirements. The importance of software maintenance and reengineering is forever increasing. Understanding the architecture of existing legacy applications is the most critical issue for maintenance and reengineering. The artifacts recovery can be facilitated with different recovery approaches, methods and tools. The existing methods provide static and dynamic set of techniques for extracting architectural information, but are not suitable for all users in different domains. This paper presents a simple and lightweight pattern extraction technique to extract different artifacts from legacy systems using regular expression pattern specifications with multiple language support. We used our custom-built tool DRT to recover artifacts from existing system at different levels of abstractions. In order to evaluate our approach a case study is conducted.
Abstract: A nonlinear optimal controller with a fuzzy gain
scheduler has been designed and applied to a Line-Of-Sight (LOS)
stabilization system. Use of Linear Quadratic Regulator (LQR)
theory is an optimal and simple manner of solving many control
engineering problems. However, this method cannot be utilized
directly for multigimbal LOS systems since they are nonlinear in
nature. To adapt LQ controllers to nonlinear systems at least a
linearization of the model plant is required. When the linearized
model is only valid within the vicinity of an operating point a gain
scheduler is required. Therefore, a Takagi-Sugeno Fuzzy Inference
System gain scheduler has been implemented, which keeps the
asymptotic stability performance provided by the optimal feedback
gain approach. The simulation results illustrate that the proposed
controller is capable of overcoming disturbances and maintaining a
satisfactory tracking performance.
Abstract: This paper presents the influence of preloading on a)
the contact tractions, b) slip levels and c) stresses at the dovetail
blade-disc interface of an aero-engine through a three-dimensional
(3D) finite element (FE) modeling and analysis. The preloading is
applied by an interference fit at the dovetail interface and the bulk
loading is applied through the rotational speed of rotor. Preloading at
the dovetail interface reduces the peak contact pressure developed
due to bulk loading up to 35%, and reduces the peak contact pressure
and stress difference between top and bottom contact edges.
Increasing the level of preloading reduces the cyclic stress amplitude
at the interface up to certain values of preload and as a consequence,
an improvement in fatigue life could be expected. Fretting damage,
due to vibration and wind milling effect during engine ground
condition, can be minimized by preloading the dovetail interface.
Abstract: The effect of Alumina nanoparticle size on thermophysical
properties, heat transfer performance and pressure loss characteristics of
Aviation Turbine Fuel (ATF)-Al2O3 nanofluids is studied experimentally for
the proposed application of regenerative cooling of semi-cryogenic rocket
engine thrust chambers. Al2O3 particles with mean diameters of 50 nm or 150
nm are dispersed in ATF. At 500C and 0.3% particle volume concentration,
the bigger particles show increases of 17% in thermal conductivity and 55% in
viscosity, whereas the smaller particles show corresponding increases of 21%
and 22% for thermal conductivity and viscosity respectively. Contrary to these
results, experiments to study the heat transfer performance and pressure loss
characteristics show that at the same pumping power, the maximum
enhancement in heat transfer coefficient at 500C and 0.3% concentration is
approximately 47% using bigger particles, whereas it is only 36% using
smaller particles.
Abstract: This paper presents a formalisation of the different existing code mutation techniques (polymorphism and metamorphism) by means of formal grammars. While very few theoretical results are known about the detection complexity of viral mutation techniques, we exhaustively address this critical issue by considering the Chomsky classification of formal grammars. This enables us to determine which family of code mutation techniques are likely to be detected or on the contrary are bound to remain undetected. As an illustration we then present, on a formal basis, a proof-of-concept metamorphic mutation engine denoted PB MOT, whose detection has been proven to be undecidable.
Abstract: The daily increase of organic waste materials resulting
from different activities in the country is one of the main factors for
the pollution of environment. Today, with regard to the low level of
the output of using traditional methods, the high cost of disposal
waste materials and environmental pollutions, the use of modern
methods such as anaerobic digestion for the production of biogas has
been prevailing. The collected biogas from the process of anaerobic
digestion, as a renewable energy source similar to natural gas but
with a less methane and heating value is usable. Today, with the help
of technologies of filtration and proper preparation, access to biogas
with features fully similar to natural gas has become possible. At
present biogas is one of the main sources of supplying electrical and
thermal energy and also an appropriate option to be used in four
stroke engine, diesel engine, sterling engine, gas turbine, gas micro
turbine and fuel cell to produce electricity. The use of biogas for
different reasons which returns to socio-economic and environmental
advantages has been noticed in CHP for the production of energy in
the world. The production of biogas from the technology of anaerobic
digestion and its application in CHP power plants in Iran can not only
supply part of the energy demands in the country, but it can
materialize moving in line with the sustainable development. In this
article, the necessity of the development of CHP plants with biogas
fuels in the country will be dealt based on studies performed from the
economic, environmental and social aspects. Also to prove the
importance of the establishment of these kinds of power plants from
the economic point of view, necessary calculations has been done as
a case study for a CHP power plant with a biogas fuel.
Abstract: The majority of existing predictors for time series are
model-dependent and therefore require some prior knowledge for the
identification of complex systems, usually involving system
identification, extensive training, or online adaptation in the case of
time-varying systems. Additionally, since a time series is usually
generated by complex processes such as the stock market or other
chaotic systems, identification, modeling or the online updating of
parameters can be problematic. In this paper a model-free predictor
(MFP) for a time series produced by an unknown nonlinear system or
process is derived using tracking theory. An identical derivation of the
MFP using the property of the Newton form of the interpolating
polynomial is also presented. The MFP is able to accurately predict
future values of a time series, is stable, has few tuning parameters and
is desirable for engineering applications due to its simplicity, fast
prediction speed and extremely low computational load. The
performance of the proposed MFP is demonstrated using the
prediction of the Dow Jones Industrial Average stock index.
Abstract: Software crisis refers to the situation in which the developers are not able to complete the projects within time and budget constraints and moreover these overscheduled and over budget projects are of low quality as well. Several methodologies have been adopted form time to time to overcome this situation and now in the focus is component based software engineering. In this approach, emphasis is on reuse of already existing software artifacts. But the results can not be achieved just by preaching the principles; they need to be practiced as well. This paper highlights some of the very basic elements of this approach, which has to be in place to get the desired goals of high quality, low cost with shorter time-to-market software products.
Abstract: Cyprus- offshore aquaculture industry has promising
prospects taking into account that Cyprus is an island. Its production
trend is increasing overtaking bigger countries such Greece and Italy.
However, current mooring systems seem to be under-performing
acting as obstacles for its future development. Furthermore, shallow
coastal waters scarcity due to competing industries dictates future
development to come by moving further from shore exposing fish
farms and subsequently mooring systems to harsher environmental
loadings. It is, therefore, of paramount importance to design mooring
systems based on engineering and scientific principles and leave
behind the present “trial and error" methods. This paper presents the
current state of Cyprus- offshore aquaculture industry and focuses of
its mooring designs by proposing a new methodology for designing
more reliable systems, hence ensuring its future.
Abstract: We present an implementation of an Online Exhibition System (OES) web service(s) that reflects our experiences with using web service development packages and software process models. The system provides major functionality that exists in similar packages. While developing such a complex web service, we gained insightful experience (i) in the traditional software development processes: waterfall model and evolutionary development and their fitness to web services development, (ii) in the fitness and effectiveness of a major web services development kit.
Abstract: This paper presents the optimal controller design of
the generator control unit in the aircraft power system. The adaptive
tabu search technique is applied to tune the controller parameters
until the best terminal output voltage of generator is achieved. The
output response from the system with the controllers designed by the
proposed technique is compared with those from the conventional
method. The transient simulations using the commercial software
package show that the controllers designed from the adaptive tabu
search algorithm can provide the better output performance compared
with the result from the classical method. The proposed design
technique is very flexible and useful for electrical aircraft engineers.
Abstract: Analytical investigation of the sedimentation
processes in the river engineering and hydraulic structures is of vital
importance as this can affect water supply for the cultivating lands in
the command area. The reason being that gradual sediment formation
behind the reservoir can reduce the nominal capacity of these dams.
The aim of the present paper is to analytically investigate
sedimentation process along the river course and behind the storage
reservoirs in general and the Eastern Intake of the Dez Diversion weir
in particular using the SHARC software. Results of the model
indicated the water level at 115.97m whereas the real time
measurement from the river cross section was 115.98 m which
suggests a significantly close relation between them. The average
transported sediment load in the river was measured at 0.25mm ,
from which it can be concluded that nearly 100% of the suspended
loads in river are moving which suggests no sediment settling but
indicates that almost all sediment loads enters into the intake. It was
further showed the average sediment diameter entering the intake to
be 0.293 mm which in turn suggests that about 85% of suspended
sediments in the river entre the intake. Comparison of the results
from the SHARC model with those obtained form the SSIIM
software suggests quite similar outputs but distinguishing the
SHARC model as more appropriate for the analysis of simpler
problems than other model.
Abstract: High Power Lasers produce an intense burst of
Bremmstrahlung radiation which has potential applications in broadband
x-ray radiography. Since the radiation produced is through the
interaction of accelerated electrons with the remaining laser target,
these bursts are extremely short – in the region of a few ps. As a
result, the laser-produced x-rays are capable of imaging complex
dynamic objects with zero motion blur.
Abstract: The leisure boatbuilding industry has tight profit margins that demand that boats are created to a high quality but with low cost. This requirement means reduced design times combined with increased use of design for production can lead to large benefits. The evolutionary nature of the boatbuilding industry can lead to a large usage of previous vessels in new designs. With the increase in automated tools for concurrent engineering within structural design it is important that these tools can reuse this information while subsequently feeding this to designers. The ability to accurately gather this materials and parts data is also a key component to these tools. This paper therefore aims to develop an architecture made up of neural networks and databases to feed information effectively to the designers based on previous design experience.
Abstract: Group contribution methods such as the UNIFAC are
of major interest to researchers and engineers involved synthesis,
feasibility studies, design and optimization of separation processes as
well as other applications of industrial use. Reliable knowledge of
the phase equilibrium behavior is crucial for the prediction of the fate
of the chemical in the environment and other applications. The
objective of this study was to predict the solubility of selected
volatile organic compounds (VOCs) in glycol polymers and
biodiesel. Measurements can be expensive and time consuming,
hence the need for thermodynamic models. The results obtained in
this study for the infinite dilution activity coefficients compare very
well those published in literature obtained through measurements. It
is suggested that in preliminary design or feasibility studies of
absorption systems for the abatement of volatile organic compounds,
prediction procedures should be implemented while accurate fluid
phase equilibrium data should be obtained from experiment.
Abstract: ZnO+Ga2O3 functionally graded thin films (FGTFs)
were examined for their potential use as Solar cell and organic light
emitting diodes (OLEDs). FGTF transparent conducting oxides (TCO)
were fabricated by combinatorial RF magnetron sputtering. The
composition gradient was controlled up to 10% by changing the
plasma power of the two sputter guns. A Ga2O3+ZnO graded region
was placed on the top layer of ZnO. The FGTFs showed up to 80%
transmittance. Their surface resistances were reduced to < 10% by
increasing the Ga2O3: pure ZnO ratio in the TCO. The FGTFs- work
functions could be controlled within a range of 0.18 eV. The
controlled work function is a very promising technology because it
reduces the contact resistance between the anode and Hall transport
layers of OLED and solar cell devices.
Abstract: Data mining and knowledge engineering have become a tough task due to the availability of large amount of data in the web nowadays. Validity and reliability of data also become a main debate in knowledge acquisition. Besides, acquiring knowledge from different languages has become another concern. There are many language translators and corpora developed but the function of these translators and corpora are usually limited to certain languages and domains. Furthermore, search results from engines with traditional 'keyword' approach are no longer satisfying. More intelligent knowledge engineering agents are needed. To address to these problems, a system known as Multilingual Word Semantic Network is proposed. This system adapted semantic network to organize words according to concepts and relations. The system also uses open source as the development philosophy to enable the native language speakers and experts to contribute their knowledge to the system. The contributed words are then defined and linked using lexical and semantic relations. Thus, related words and derivatives can be identified and linked. From the outcome of the system implementation, it contributes to the development of semantic web and knowledge engineering.
Abstract: The contribution is dealing with the influence of high speed parameters on the quality of machined surface. In general the principle of high speed cutting lies in achieving faster machine times with concurrent increase in accuracy and quality of the machined areas in largely irregular, mathematically hard to define shapes. High speed machining is a highly effective method of machining with the following goals: increasing of machining productivity, increasing of quality of the machined surface, improving of machining economy, improving of ecological aspects of machining. This article is based on an experiment performed by the Department of Machining and Assembly of the Faculty of Mechanical Engineering of VŠBTechnical University of Ostrava.
Abstract: Circular tubes have been widely used as structural
members in engineering application. Therefore, its collapse behavior
has been studied for many decades, focusing on its energy absorption
characteristics. In order to predict the collapse behavior of members,
one could rely on the use of finite element codes or experiments.
These tools are helpful and high accuracy but costly and require
extensive running time. Therefore, an approximating model of tubes
collapse mechanism is an alternative for early step of design. This
paper is also aimed to develop a closed-form solution of thin-walled
circular tube subjected to bending. It has extended the Elchalakani et
al.-s model (Int. J. Mech. Sci.2002; 44:1117-1143) to include the
rate of energy dissipation of rolling hinge in the circumferential
direction. The 3-D geometrical collapse mechanism was analyzed by
adding the oblique hinge lines along the longitudinal tube within the
length of plastically deforming zone. The model was based on the
principal of energy rate conservation. Therefore, the rates of internal
energy dissipation were calculated for each hinge lines which are
defined in term of velocity field. Inextensional deformation and
perfect plastic material behavior was assumed in the derivation of
deformation energy rate. The analytical result was compared with
experimental result. The experiment was conducted with a number of
tubes having various D/t ratios. Good agreement between analytical
and experiment was achieved.
Abstract: The present work describes an experimental
investigation concerning the determination of viscosity behavior with
shear rate and temperature of edible oils: canola; sunflower; corn;
soybean and the no edible oil: Jatropha curcas. Besides these, it was
tested a blend of canola, corn and sunflower oils as well as sunflower
and soybean biodiesel. Based on experiments, it was obtained shear
stress and viscosity at different shear rates of each sample at 40ºC, as
well as viscosity of each sample at various temperatures in the range
of 24 to 85ºC. Furthermore, it was compared the curves obtained for
the viscosity versus temperature with the curves obtained by
modeling the viscosity dependency on temperature using the Vogel
equation. Also a test in a stationary engine was performed in order to
study the energy generation using blends of soybean oil and soybean
biodiesel with diesel.