Abstract: In this research, the laminar heat transfer of natural convection on vertical surfaces has been investigated. Most of the studies on natural convection have been considered constantly whereas velocity and temperature domain, do not change with time, transient one are used a lot. Governing equations are solved using a finite volume approach. The convective terms are discretized using the power-law scheme, whereas for diffusive terms the central difference is employed. Coupling between the velocity and pressure is made with SIMPLE algorithm. The resultant system of discretized linear algebraic equations is solved with an alternating direction implicit scheme. Then a configuration of rectangular fins is put in different ways on the surface and heat transfer of natural convection on these surfaces without sliding is studied and finally optimization is done.
Abstract: Component-Based software engineering provides an
opportunity for better quality and increased productivity in software
development by using reusable software components [10]. One of the
most critical aspects of the quality of a software system is its
performance. The systematic application of software performance
engineering techniques throughout the development process can help
to identify design alternatives that preserve desirable qualities such
as extensibility and reusability while meeting performance objectives
[1]. In the present scenario, software engineering methodologies
strongly focus on the functionality of the system, while applying a
“fix- it-later" approach to software performance aspects [3]. As a
result, lengthy fine-tunings, expensive extra hard ware, or even
redesigns are necessary for the system to meet the performance
requirements. In this paper, we propose design based,
implementation independent, performance prediction approach to
reduce the overhead associated in the later phases while developing a
performance guaranteed software product with the help of Unified
Modeling Language (UML).
Abstract: This paper describes dynamic analysis using proposed
fast finite element method for a shock absorbing structure including a
sponge. The structure is supported by nonlinear concentrated springs.
The restoring force of the spring has cubic nonlinearity and linear
hysteresis damping. To calculate damping properties for the structures
including elastic body and porous body, displacement vectors as
common unknown variable are solved under coupled condition. Under
small amplitude, we apply asymptotic method to complex eigenvalue
problem of this system to obtain modal parameters. And then
expressions of modal loss factor are derived approximately. This
approach was proposed by one of the authors previously. We call this
method as Modal Strain and Kinetic Energy Method (MSKE method).
Further, using the modal loss factors, the discretized equations in
physical coordinate are transformed into the nonlinear ordinary
coupled equations using normal coordinate corresponding to linear
natural modes. This transformation yields computation efficiency. As
a numerical example of a shock absorbing structures, we adopt double
skins with a sponge. The double skins are supported by nonlinear
concentrated springs. We clarify influences of amplitude of the input
force on nonlinear and chaotic responses.
Abstract: The objective of this work is to produce heterotrophic
microalgal lipid in flask-batch fermentation. Chlorella sp. KKU-S2
supported maximum values of 0.374 g/L/d, 0.478 g lipid/g cells, and
0.112 g/L/d for volumetric lipid production rate, and specific yield of
lipid, and specific rate of lipid production, respectively when culture
was performed on BG-11 medium supplemented with 50g/L glucose.
Among the carbon sources tested, maximum cell yield coefficient
(YX/S, g/L), maximum specific yield of lipid (YP/X, g lipid/g cells) and
volumetric lipid production rate (QP, g/L/d) were found of 0.728,
0.237, and 0.619, respectively, using sugarcane molasses as carbon
source. The main components of fatty acid from extracted lipid were
palmitic acid, stearic acid, oleic acid and linoleic acid which similar
to vegetable oils and suitable for biodiesel production.
Abstract: In this paper, we present a new learning algorithm for
anomaly based network intrusion detection using improved self
adaptive naïve Bayesian tree (NBTree), which induces a hybrid of
decision tree and naïve Bayesian classifier. The proposed approach
scales up the balance detections for different attack types and keeps
the false positives at acceptable level in intrusion detection. In
complex and dynamic large intrusion detection dataset, the detection
accuracy of naïve Bayesian classifier does not scale up as well as
decision tree. It has been successfully tested in other problem
domains that naïve Bayesian tree improves the classification rates in
large dataset. In naïve Bayesian tree nodes contain and split as
regular decision-trees, but the leaves contain naïve Bayesian
classifiers. The experimental results on KDD99 benchmark network
intrusion detection dataset demonstrate that this new approach scales
up the detection rates for different attack types and reduces false
positives in network intrusion detection.
Abstract: The main idea behind in network aggregation is that,
rather than sending individual data items from sensors to sinks,
multiple data items are aggregated as they are forwarded by the
sensor network. Existing sensor network data aggregation techniques
assume that the nodes are preprogrammed and send data to a central
sink for offline querying and analysis. This approach faces two major
drawbacks. First, the system behavior is preprogrammed and cannot
be modified on the fly. Second, the increased energy wastage due to
the communication overhead will result in decreasing the overall
system lifetime. Thus, energy conservation is of prime consideration
in sensor network protocols in order to maximize the network-s
operational lifetime. In this paper, we give an energy efficient
approach to query processing by implementing new optimization
techniques applied to in-network aggregation. We first discuss earlier
approaches in sensors data management and highlight their
disadvantages. We then present our approach “Energy Efficient
Indexed Aggregation" (EEIA) and evaluate it through several
simulations to prove its efficiency, competence and effectiveness.
Abstract: In this paper an open agent-based modular framework
for personalized and adaptive curriculum generation in e-learning
environment is proposed. Agent-based approaches offer several
potential advantages over alternative approaches. Agent-based
systems exhibit high levels of flexibility and robustness in dynamic
or unpredictable environments by virtue of their intrinsic autonomy.
The presented framework enables integration of different types of
expert agents, various kinds of learning objects and user modeling
techniques. It creates possibilities for adaptive e-learning process.
The KM e-learning system is in a process of implementation in
Varna Free University and will be used for supporting the
educational process at the University.
Abstract: Using DNA microarrays the comparative analysis of a
gene expression profiles is carried out in a liver and kidneys of pigs.
The hypothesis of a cross hybridization of one probe with different
cDNA sites of the same gene or different genes is checked up, and it
is shown, that cross hybridization can be a source of essential errors
at revealing of a key genes in organ-specific transcriptome. It is
reveald that distinctions in profiles of a gene expression are well coordinated
with function, morphology, biochemistry and histology of
these organs.
Abstract: This paper presents modern vibration signalprocessing
techniques for vehicle gearbox fault diagnosis, via the
wavelet analysis and the Squared Envelope (SE) technique. The
wavelet analysis is regarded as a powerful tool for the detection of
sudden changes in non-stationary signals. The Squared Envelope
(SE) technique has been extensively used for rolling bearing
diagnostics. In the present work a scheme of using the Squared
Envelope technique for early detection of gear tooth pit. The pitting
defect is manufactured on the tooth side of a fifth speed gear on the
intermediate shaft of a vehicle gearbox. The objective is to
supplement the current techniques of gearbox fault diagnosis based
on using the raw vibration and ordered signals. The test stand is
equipped with three dynamometers; the input dynamometer serves as
the internal combustion engine, the output dynamometers introduce
the load on the flanges of output joint shafts. The gearbox used for
experimental measurements is the type most commonly used in
modern small to mid-sized passenger cars with transversely mounted
powertrain and front wheel drive; a five-speed gearbox with final
drive gear and front wheel differential. The results show that the
approaches methods are effective for detecting and diagnosing
localized gear faults in early stage under different operation
conditions, and are more sensitive and robust than current gear
diagnostic techniques.
Abstract: The approaches to make an agent generate intelligent actions in the AI field might be roughly categorized into two ways–the classical planning and situated action system. It is well known that each system have its own strength and weakness. However, each system also has its own application field. In particular, most of situated action systems do not directly deal with the logical problem. This paper first briefly mentions the novel action generator to situatedly extract a set of actions, which is likely to help to achieve the goal at the current situation in the relaxed logical space. After performing the action set, the agent should recognize the situation for deciding the next likely action set. However, since the extracted action is an approximation of the action which helps to achieve the goal, the agent could be caught into the deadlock of the problem. This paper proposes the newly developed hybrid architecture to solve the problem, which combines the novel situated action generator with the conventional planner. The empirical result in some planning domains shows that the quality of the resultant path to the goal is mostly acceptable as well as deriving the fast response time, and suggests the correlation between the structure of problems and the organization of each system which generates the action.
Abstract: Nowadays companies in all sectors are looking for the
sources of competitive advantages. Holistic marketing approach
searches for their emergence based on the integration of all
components and elements across the organization. Modern marketing
sees the sources of competitive advantage in implementing the latest
managerial practices, motivation, intelligent project management,
knowledge management, collaborative marketing, CSR and, in the
recent years, also in the business process optimization. With the use
of modern tools including business process management and business
process modelling the company can markedly increase its internal
efficiency which can lead not only to lowering the costs but to
creating the environment for optimal customer care, positive
corporate culture and for origination of innovations as well. In the
article the authors analyze the recent trend in this area and introduce
suggestions to companies to identify and optimize the key processes
that have a significant impact of the company´s competitiveness.
Abstract: The range of the output power is a very important and evident limitation of two-level inverters. In order to overcome this disadvantage, multilevel inverters are introduced. Recently, Cascade H-Bridge inverters have emerged as one of the popular converter topologies used in numerous industrial applications. The modulation switching strategies such as phase shifted carrier based Pulse Width Modulation (PWM) technique and Stair case modulation with Selective Harmonic Elimination (SHE) PWM technique are generally used. NR method is used to solve highly non linear transcendental equations which are formed by SHEPWM method. Generally NR method has a drawback of requiring good initial guess but in this paper a new approach is implemented for NR method with any random initial guess. A three phase CHB 11-level inverter is chosen for analysis. MATLAB/SIMULINK programming environment and harmonic profiles are compared. Finally this paper presents a method at fundamental switching frequency with least % THDV.
Abstract: A power cable is widely used for power supply in
power distributing networks and power transmission lines. Due to
limitations in the production, delivery and setting up power cables,
they are produced and delivered in several separate lengths. Cable
itself, consists of two cable terminations and arbitrary number of
cable joints, depending on the cable route length. Electrical stress
control is needed to prevent a dielectric breakdown at the end of the
insulation shield in both the air and cable insulation. Reliability of
cable joint depends on its materials, design, installation and operating
environment. The paper describes design and performance results for
new modeled cable joints. Design concepts, based on numerical
calculations, must be correct. An Equivalent Electrodes
Method/Boundary Elements Method-hybrid approach that allows
electromagnetic field calculations in multilayer dielectric media,
including inhomogeneous regions, is presented.
Abstract: Electronic seal is an electronic device to check the
authenticity and integrity of freight containers at the point of arrival.
While RFID-based eSeals are gaining more acceptances and there are
also some standardization processes for these devices, a recent
research revealed that the current RFID-based eSeals are vulnerable to
various attacks. In this paper, we provide a feasible solution to
enhance the security of active RFID-based eSeals. Our approach is to
use an authentication and key agreement protocol between eSeal and
reader device, enabling data encryption and integrity check. Our
protocol is based on the use of block cipher AES, which is reasonable
since a block cipher can also be used for many other security purposes
including data encryption and pseudo-random number generation. Our
protocol is very simple, and it is applicable to low-end active RFID
eSeals.
Abstract: Evaluation of contact pressure, surface and
subsurface contact stresses are essential to know the functional
response of surface coatings and the contact behavior mainly depends
on surface roughness, material property, thickness of layer and the
manner of loading. Contact parameter evaluation of real rough
surface contacts mostly relies on statistical single asperity contact
approaches. In this work, a three dimensional layered solid rough
surface in contact with a rigid flat is modeled and analyzed using
finite element method. The rough surface of layered solid is
generated by FFT approach. The generated rough surface is exported
to a finite element method based ANSYS package through which the
bottom up solid modeling is employed to create a deformable solid
model with a layered solid rough surface on top. The discretization
and contact analysis are carried by using the same ANSYS package.
The elastic, elastoplastic and plastic deformations are continuous in
the present finite element method unlike many other contact models.
The Young-s modulus to yield strength ratio of layer is varied in the
present work to observe the contact parameters effect while keeping
the surface roughness and substrate material properties as constant.
The contacting asperities attain elastic, elastoplastic and plastic states
with their continuity and asperity interaction phenomena is inherently
included. The resultant contact parameters show that neighboring
asperity interaction and the Young-s modulus to yield strength ratio
of layer influence the bulk deformation consequently affect the
interface strength.
Abstract: A design of communication area for infrared
electronic-toll-collection systems to provide an extended
communication interval in the vehicle traveling direction and
regular boundary between contiguous traffic lanes is proposed.
By utilizing two typical low-cost commercial infrared LEDs with
different half-intensity angles Φ1/2 = 22◦ and 10◦, the radiation
pattern of the emitter is designed to properly adjust the spatial
distribution of the signal power. The aforementioned purpose
can be achieved with an LED array in a three-piece structure
with appropriate mounting angles. With this emitter, the influence
of the mounting parameters, including the mounting height and
mounting angles of the on-board unit and road-side unit, on the
system performance in terms of the received signal strength and
communication area are investigated. The results reveal that, for
our emitter proposed in this paper, the ideal ”long-and-narrow”
characteristic of the communication area is very little affected by
these mounting parameters. An optimum mounting configuration is
also suggested.
Abstract: In this paper, genetic algorithm (GA) is proposed for
the design of an optimization algorithm to achieve the bandwidth
allocation of ATM network. In Broadband ISDN, the ATM is a highbandwidth;
fast packet switching and multiplexing technique. Using
ATM it can be flexibly reconfigure the network and reassign the
bandwidth to meet the requirements of all types of services. By
dynamically routing the traffic and adjusting the bandwidth
assignment, the average packet delay of the whole network can be
reduced to a minimum. M/M/1 model can be used to analyze the
performance.
Abstract: This paper presents a method for determining the
uniaxial tensile properties such as Young-s modulus, yield strength
and the flow behaviour of a material in a virtually non-destructive
manner. To achieve this, a new dumb-bell shaped miniature
specimen has been designed. This helps in avoiding the removal of
large size material samples from the in-service component for the
evaluation of current material properties. The proposed miniature
specimen has an advantage in finite element modelling with respect
to computational time and memory space. Test fixtures have been
developed to enable the tension tests on the miniature specimen in a
testing machine. The studies have been conducted in a chromium
(H11) steel and an aluminum alloy (AR66). The output from the
miniature test viz. load-elongation diagram is obtained and the finite
element simulation of the test is carried out using a 2D plane stress
analysis. The results are compared with the experimental results. It is
observed that the results from the finite element simulation
corroborate well with the miniature test results. The approach seems
to have potential to predict the mechanical properties of the
materials, which could be used in remaining life estimation of the
various in-service structures.
Abstract: Model-based approaches have been applied successfully
to a wide range of tasks such as specification, simulation, testing, and
diagnosis. But one bottleneck often prevents the introduction of these
ideas: Manual modeling is a non-trivial, time-consuming task.
Automatically deriving models by observing and analyzing running
systems is one possible way to amend this bottleneck. To
derive a model automatically, some a-priori knowledge about the
model structure–i.e. about the system–must exist. Such a model
formalism would be used as follows: (i) By observing the network
traffic, a model of the long-term system behavior could be generated
automatically, (ii) Test vectors can be generated from the model,
(iii) While the system is running, the model could be used to diagnose
non-normal system behavior.
The main contribution of this paper is the introduction of a model
formalism called 'probabilistic regression automaton' suitable for the
tasks mentioned above.
Abstract: Support vector machines (SVMs) have shown
superior performance compared to other machine learning techniques,
especially in classification problems. Yet one limitation of SVMs is
the lack of an explanation capability which is crucial in some
applications, e.g. in the medical and security domains. In this paper, a
novel approach for eclectic rule-extraction from support vector
machines is presented. This approach utilizes the knowledge acquired
by the SVM and represented in its support vectors as well as the
parameters associated with them. The approach includes three stages;
training, propositional rule-extraction and rule quality evaluation.
Results from four different experiments have demonstrated the value
of the approach for extracting comprehensible rules of high accuracy
and fidelity.