Abstract: DC-DC converters are widely used in regulated switched mode power supplies and in DC motor drive applications. There are several sources of unwanted nonlinearity in practical power converters. In addition, their operation is characterized by switching that gives birth to a variety of nonlinear dynamics. DC-DC buck and boost converters controlled by pulse-width modulation (PWM) have been simulated. The voltage waveforms and attractors obtained from the circuit simulation have been studied. With the onset of instability, the phenomenon of subharmonic oscillations, quasi-periodicity, bifurcations, and chaos have been observed. This paper is mainly motivated by potential contributions of chaos theory in the design, analysis and control of power converters, in particular and power electronics circuits, in general.
Abstract: The dynamics of the Autonomous Underwater
Vehicles (AUVs) are highly nonlinear and time varying and the hydrodynamic coefficients of vehicles are difficult to estimate
accurately because of the variations of these coefficients with
different navigation conditions and external disturbances. This study presents the on-line system identification of AUV dynamics to obtain
the coupled nonlinear dynamic model of AUV as a black box. This black box has an input-output relationship based upon on-line
adaptive fuzzy model and adaptive neural fuzzy network (ANFN)
model techniques to overcome the uncertain external disturbance and
the difficulties of modelling the hydrodynamic forces of the AUVs instead of using the mathematical model with hydrodynamic parameters estimation. The models- parameters are adapted according
to the back propagation algorithm based upon the error between the
identified model and the actual output of the plant. The proposed
ANFN model adopts a functional link neural network (FLNN) as the
consequent part of the fuzzy rules. Thus, the consequent part of the
ANFN model is a nonlinear combination of input variables. Fuzzy
control system is applied to guide and control the AUV using both
adaptive models and mathematical model. Simulation results show
the superiority of the proposed adaptive neural fuzzy network
(ANFN) model in tracking of the behavior of the AUV accurately
even in the presence of noise and disturbance.
Abstract: XML is a markup language which is becoming the
standard format for information representation and data exchange. A
major purpose of XML is the explicit representation of the logical
structure of a document. Much research has been performed to
exploit logical structure of documents in information retrieval in
order to precisely extract user information need from large
collections of XML documents. In this paper, we describe an XML
information retrieval weighting scheme that tries to find the most
relevant elements in XML documents in response to a user query.
We present this weighting model for information retrieval systems
that utilize plausible inferences to infer the relevance of elements in
XML documents. We also add to this model the Dempster-Shafer
theory of evidence to express the uncertainty in plausible inferences
and Dempster-Shafer rule of combination to combine evidences
derived from different inferences.
Abstract: This paper presents an adaptive nonlinear position
controller with velocity constraint, capable of combining the
input-output linearization technique and Lyapunov stability theory.
Based on the Lyapunov stability theory, the adaptation law of the
proposed controller is derived along with the verification of the overall
system-s stability. Computer simulation results demonstrate that the
proposed controller is robust and it can ensure transient stability of
BLDCM, under the occurrence of a large sudden fault.
Abstract: An application framework provides a reusable design
and implementation for a family of software systems. Application
developers extend the framework to build their particular
applications using hooks. Hooks are the places identified to show
how to use and customize the framework. Hooks define Framework
Interface Classes (FICs) and their possible specifications, which
helps in building reusable test cases for the implementations of these
classes. In applications developed using gray-box frameworks, FICs
inherit framework classes or use them without inheritance. In this
paper, a test-case generation technique is extended to build test cases
for FICs built for gray-box frameworks. A tool is developed to
automate the introduced technique.
Abstract: In this paper, a new model order reduction
phenomenon is introduced at the design stage of linear phase digital
IIR filter. The complexity of a system can be reduced by adopting the
model order reduction method in their design. In this paper a mixed
method of model order reduction is proposed for linear IIR filter. The
proposed method employs the advantages of factor division technique
to derive the reduced order denominator polynomial and the reduced
order numerator is obtained based on the resultant denominator
polynomial. The order reduction technique is used to reduce the delay
units at the design stage of IIR filter. The validity of the proposed
method is illustrated with design example in frequency domain and
stability is also examined with help of nyquist plot.
Abstract: As the Internet technology has developed rapidly, the
number of identities (IDs) managed by each individual person has
increased and various ID management technologies have been
developed to assist users. However, most of these technologies are
vulnerable to the existing hacking methods such as phishing attacks
and key-logging. If the administrator-s password is exposed, an
attacker can access the entire contents of the stolen user-s data files in
other devices. To solve these problems, we propose here a new ID
management scheme based on a Single Password Protocol. The paper
presents the details of the new scheme as well as a formal analysis of
the method using BAN Logic.
Abstract: Ranking of fuzzy numbers play an important role in
decision making, optimization, forecasting etc. Fuzzy numbers must
be ranked before an action is taken by a decision maker. In this
paper, with the help of several counter examples it is proved that
ranking method proposed by Chen and Chen (Expert Systems with
Applications 36 (2009) 6833-6842) is incorrect. The main aim of this
paper is to propose a new approach for the ranking of generalized
trapezoidal fuzzy numbers. The main advantage of the proposed
approach is that the proposed approach provide the correct ordering
of generalized and normal trapezoidal fuzzy numbers and also the
proposed approach is very simple and easy to apply in the real life
problems. It is shown that proposed ranking function satisfies all
the reasonable properties of fuzzy quantities proposed by Wang and
Kerre (Fuzzy Sets and Systems 118 (2001) 375-385).
Abstract: This paper presented a collaborative education model,
which consists four parts: collaborative teaching, collaborative
working, collaborative training and interaction. Supported by an
e-learning platform, collaborative education was practiced in a data
structure e-learning course. Data collected shows that most of students
accept collaborative education. This paper goes one step attempting to
determine which aspects appear to be most important or helpful in
collaborative education.
Abstract: Financial forecasting using machine learning techniques has received great efforts in the last decide . In this ongoing work, we show how machine learning of graphical models will be able to infer a visualized causal interactions between different banks in the Saudi equities market. One important discovery from such learned causal graphs is how companies influence each other and to what extend. In this work, a set of graphical models named Gaussian graphical models with developed ensemble penalized feature selection methods that combine ; filtering method, wrapper method and a regularizer will be shown. A comparison between these different developed ensemble combinations will also be shown. The best ensemble method will be used to infer the causal relationships between banks in Saudi equities market.
Abstract: People usually have a telephone voice, which means
they adjust their speech to fit particular situations and to blend in with
other interlocutors. The question is: Do we speak differently to
different people? This possibility has been suggested by social
psychologists within Accommodation Theory [1]. Converging toward
the speech of another person can be regarded as a polite speech
strategy while choosing a language not used by the other interlocutor
can be considered as the clearest example of speech divergence [2].
The present study sets out to investigate such processes in the course
of everyday telephone conversations. Using Joos-s [3] model of
formality in spoken English, the researchers try to explore
convergence to or divergence from the addressee. The results
propound the actuality that lexical choice, and subsequently, patterns
of style vary intriguingly in concordance with the person being
addressed.
Abstract: In rotating machinery one of the critical components
that is prone to premature failure is the rolling bearing.
Consequently, early warning of an imminent bearing failure is much
critical to the safety and reliability of any high speed rotating
machines. This study is concerned with the application of Recurrence
Quantification Analysis (RQA) in fault detection of rolling element
bearings in rotating machinery. Based on the results from this study it
is reported that the RQA variable, percent determinism, is sensitive
to the type of fault investigated and therefore can provide useful
information on bearing damage in rolling element bearings.
Abstract: The aim of this study was to establish the feasibility of a minute incremental exercise testing protocol in young asthma children. Twenty-two children with clinically diagnosed mild to moderate asthma volunteered to participate. The maximum incremental exercise test was performed using a cycle ergometer with an electromagnetic braking. A warm-up unloaded for 2 minutes then the workload was started at 40 watts for 2 minutes, and then stepwise increments of 8 watts per 2 minutes were applied. The pedaling frequency was set at 50 rpm. Ventilation and gas exchange were measured with a breath-by-breath automatic metabolic measurement system. Results showed that this test was well tolerated by all asthmatic children. Most of the children reached the VO2 plateau and satisfied the criteria for maximal respiratory exchange ratio of ≥ 1. This Study demonstrated that this testing protocol was suitable for young asthmatic children.
Abstract: This work deals with problems of tool axis inclination angles in ball-end milling. Tool axis inclination angle contributes to improvement of functional surface properties (surface integrity - surface roughness, residual stress, micro hardness, etc.), decreasing cutting forces and improving production. By milling with ball-end milling tool, using standard way of cutting, when work piece and cutting tool contain right angle, we have zero cutting speed on edge. At this point cutting tool only pushes material into the work piece. Here we can observe the following undesirable effects - chip contraction, increasing of cutting temperature, increasing vibrations or creation of built-up edge. These effects have negative results – low quality of surface and decreasing of tool life (in the worse case even it is pinching out). These effects can be eliminated with the tilt of cutting tool or tilt of work piece.
Abstract: This paper introduces the effective speckle reduction of
synthetic aperture radar (SAR) images using inner product spaces in
undecimated wavelet domain. There are two major areas in projection
onto span algorithm where improvement can be made. First is the use
of undecimated wavelet transformation instead of discrete wavelet
transformation. And second area is the use of smoothing filter namely
directional smoothing filter which is an additional step. Proposed
method does not need any noise estimation and thresholding
technique. More over proposed method gives good results on both
single polarimetric and fully polarimetric SAR images.
Abstract: The steady state response of bond graphs representing
passive and active suspension is presented. A bond graph with
preferred derivative causality assignment to get the steady state
is proposed. A general junction structure of this bond graph
is proposed. The proposed methodology to passive and active
suspensions is applied.
Abstract: Crawling movement as a motive mode seen in nature
of some animals such as snakes possesses a specific syntactic and
dynamic analysis. Serpentine robot designed by inspiration from
nature and snake-s crawling motion, is regarded as a crawling robot.
In this paper, a serpentine robot with spiral motion model will be
analyzed. The purpose of this analysis is to calculate the vertical and
tangential forces along snake-s body and to determine the parameters
affecting on these forces. Two types of serpentine robots have been
designed in order to examine the achieved relations explained below.
Abstract: The availability of broadband internet and increased
access to computers has been instrumental in the rise of internet
literacy in Malaysia. This development has led to the adoption of
online shopping by many Malaysians. On another note, the
Government has supported the development and production of local
herbal products. This has resulted in an increase in the production and
diversity of products by SMEs. The purpose of this study is to
evaluate the influence of the Malaysian demographic factors and
selected attitudinal characteristics in relation to the online purchasing
of herbal products. In total, 1054 internet users were interviewed
online and Chi-square analysis was used to determine the relationship
between demographic variables and different aspects of online
shopping for herbal products. The overall results show that the
demographic variables such as age, gender, education level, income
and ethnicity were significant when considering the online shopping
antecedents of trust, quality of herbal products, perceived risks and
perceived benefits.
Abstract: Although the STL (stereo lithography) file format is
widely used as a de facto industry standard in the rapid prototyping
industry due to its simplicity and ability to tessellation of almost all
surfaces, but there are always some defects and shortcoming in their
usage, which many of them are difficult to correct manually. In
processing the complex models, size of the file and its defects grow
extremely, therefore, correcting STL files become difficult. In this
paper through optimizing the exiting algorithms, size of the files and
memory usage of computers to process them will be reduced. In spite
of type and extent of the errors in STL files, the tail-to-head
searching method and analysis of the nearest distance between tails
and heads techniques were used. As a result STL models sliced
rapidly, and fully closed contours produced effectively and errorless.