Abstract: Among all FACTS devices, the unified power flow
controller (UPFC) is considered to be the most versatile device.
This is due to its capability to control all the transmission system
parameters (impedance, voltage magnitude, and phase angle). With
the growing interest in UPFC, the attention to develop a mathematical
model has increased. Several models were introduced for UPFC in
literature for different type of studies in power systems. In this paper
a novel comparison study between two dynamic models of UPFC
with their proposed control strategies.
Abstract: This work proposes a fuzzy methodology to support
the investment decisions. While choosing among competitive
investment projects, the methodology makes ranking of projects
using the new aggregation OWA operator – AsPOWA, presented in
the environment of possibility uncertainty. For numerical evaluation
of the weighting vector associated with the AsPOWA operator the
mathematical programming problem is constructed. On the basis of
the AsPOWA operator the projects’ group ranking maximum criteria
is constructed. The methodology also allows making the most
profitable investments into several of the project using the method
developed by the authors for discrete possibilistic bicriteria problems.
The article provides an example of the investment decision-making
that explains the work of the proposed methodology.
Abstract: Recent perceived climate variability raises concerns
with unprecedented hydrological phenomena and extremes.
Distribution and circulation of the waters of the Earth become
increasingly difficult to determine because of additional uncertainty
related to anthropogenic emissions. The world wide observed
changes in the large-scale hydrological cycle have been related to an
increase in the observed temperature over several decades. Although
the effect of change in climate on hydrology provides a general
picture of possible hydrological global change, new tools and
frameworks for modelling hydrological series with nonstationary
characteristics at finer scales, are required for assessing climate
change impacts. Of the downscaling techniques, dynamic
downscaling is usually based on the use of Regional Climate Models
(RCMs), which generate finer resolution output based on atmospheric
physics over a region using General Circulation Model (GCM) fields
as boundary conditions. However, RCMs are not expected to capture
the observed spatial precipitation extremes at a fine cell scale or at a
basin scale. Statistical downscaling derives a statistical or empirical
relationship between the variables simulated by the GCMs, called
predictors, and station-scale hydrologic variables, called predictands.
The main focus of the paper is on the need for using statistical
downscaling techniques for projection of local hydrometeorological
variables under climate change scenarios. The projections can be then
served as a means of input source to various hydrologic models to
obtain streamflow, evapotranspiration, soil moisture and other
hydrological variables of interest.
Abstract: A generalized vortex lattice method for complex
lifting surfaces with flap and aileron deflection is formulated. The
method is not restricted by the linearized theory assumption and
accounts for all standard geometric lifting surface parameters:
camber, taper, sweep, washout, dihedral, in addition to flap and
aileron deflection. Thickness is not accounted for since the physical
lifting body is replaced by a lattice of panels located on the mean
camber surface. This panel lattice setup and the treatment of different
wake geometries is what distinguish the present work form the
overwhelming majority of previous solutions based on the vortex
lattice method. A MATLAB code implementing the proposed
formulation is developed and validated by comparing our results to
existing experimental and numerical ones and good agreement is
demonstrated. It is then used to study the accuracy of the widely used
classical vortex-lattice method. It is shown that the classical approach
gives good agreement in the clean configuration but is off by as much
as 30% when a flap or aileron deflection of 30° is imposed. This
discrepancy is mainly due the linearized theory assumption
associated with the conventional method. A comparison of the effect
of four different wake geometries on the values of aerodynamic
coefficients was also carried out and it is found that the choice of the
wake shape had very little effect on the results.
Abstract: An analysis of the Australian Diabetes Screening
Study estimated undiagnosed diabetes mellitus [DM] prevalence in a
high risk general practice based cohort. DM prevalence varied from
9.4% to 18.1% depending upon the diagnostic criteria utilised with
age being a highly significant risk factor. Utilising the gold standard
oral glucose tolerance test, the prevalence of DM was 22-23% in
those aged >= 70 years and
Abstract: It is well known, that any interpolating polynomial
p (x, y) on the vector space Pn,m of two-variable polynomials with
degree less than n in terms of x and less than m in terms of y, has
various representations that depends on the basis of Pn,m that we
select i.e. monomial, Newton and Lagrange basis e.t.c.. The aim of
this short note is twofold : a) to present transformations between the
coordinates of the polynomial p (x, y) in the aforementioned basis
and b) to present transformations between these bases.
Abstract: One of the major goals of Spoken Dialog Systems
(SDS) is to understand what the user utters.
In the SDS domain, the Spoken Language Understanding (SLU)
Module classifies user utterances by means of a pre-definite
conceptual knowledge. The SLU module is able to recognize only the
meaning previously included in its knowledge base. Due the vastity
of that knowledge, the information storing is a very expensive
process.
Updating and managing the knowledge base are time-consuming
and error-prone processes because of the rapidly growing number of
entities like proper nouns and domain-specific nouns. This paper
proposes a solution to the problem of Name Entity Recognition
(NER) applied to a SDS domain. The proposed solution attempts to
automatically recognize the meaning associated with an utterance by
using the PANKOW (Pattern based Annotation through Knowledge
On the Web) method at runtime.
The method being proposed extracts information from the Web to
increase the SLU knowledge module and reduces the development
effort. In particular, the Google Search Engine is used to extract
information from the Facebook social network.
Abstract: Three dimensional non-Interlaced carbon fibre
reinforced silicon carbide (3-D-Cf/SiC) composites with pyrocarbon
interphase were fabricated using isothermal chemical vapor
infiltration (ICVI) combined with polymer impregnation pyrolysis
(PIP) process. Polysilazane (PSZ) is used as a preceramic polymer to
obtain silicon carbide matrix. Thermo gravimetric analysis (TGA),
Infrared spectroscopic analysis (IR) and X-ray diffraction (XRD)
analysis were carried out on PSZ pyrolysed at different temperatures
to understand the pyrolysis and obtaining the optimum pyrolysing
condition to yield β-SiC phase. The density of the composites was
1.94 g cm-3 after the 3-D carbon preform was SiC infiltrated for 280 h
with one intermediate polysilazane pre-ceramic PIP process.
Mechanical properties of the composite materials were investigated
under tensile, flexural, shear and impact loading. The values of
tensile strength were 200 MPa at room temperature (RT) and 195
MPa at 500°C in air. The average RT flexural strength was 243 MPa.
The lower flexural strength of these composites is because of the
porosity. The fracture toughness obtained from single edge notched
beam (SENB) technique was 39 MPa.m1/2. The work of fracture
obtained from the load-displacement curve of SENB test was 22.8
kJ.m-2. The composites exhibited excellent impact resistance and the
dynamic fracture toughness of 44.8 kJ.m-2 is achieved as determined
from instrumented Charpy impact test. The shear strength of the
composite was 93 MPa, which is significantly higher compared 2-D
Cf/SiC composites. Microstructure evaluation of fracture surfaces
revealed the signatures of fracture processes and showed good
support for the higher toughness obtained.
Abstract: This paper presents the performance state analysis of
Self-Excited Induction Generator (SEIG) using Artificial Bee Colony
(ABC) optimization technique. The total admittance of the induction
machine is minimized to calculate the frequency and magnetizing
reactance corresponding to any rotor speed, load impedance and
excitation capacitance. The performance of SEIG is calculated using
the optimized parameter found. The results obtained by ABC
algorithm are compared with results from numerical method. The
results obtained coincide with the numerical method results. This
technique proves to be efficient in solving nonlinear constrained
optimization problems and analyzing the performance of SEIG.
Abstract: Male factor infertility due to endocrine disturbances
such as abnormalities in prolactin levels are encountered in a
significant proportion. This case control study was carried out to
determine the effects of prolactin on the male reproductive tract,
using 200 male white rats. The rats were maintained as the control
group (G1), hypoprolactinaemic group (G2), 3 hyperprolactinaemic
groups induced using oral largactil (G3), low dose fluphenazine (G4)
and high dose fluphenazine (G5). After 100 days, rats were subjected
to serum prolactin (PRL) level measurements and for basic seminal
fluid analysis (BSA). The difference between serum PRL
concentrations of rats in G2, G3, G4 and G5 as compared to the
control group were highly significant by Student’s t-test (p
Abstract: This paper presents the design and analysis of Liquid
Crystal (LC) based tunable reflectarray antenna with different design
configurations within X-band frequency range. The effect of LC
volume used for unit cell element on frequency tunability and
reflection loss performance has been investigated. Moreover different
slot embedded patch element configurations have been proposed for
LC based tunable reflectarray antenna design with enhanced
performance. The detailed fabrication and measurement procedure
for different LC based unit cells has been presented. The waveguide
scattering parameter measured results demonstrated that by using the
circular slot embedded patch elements, the frequency tunability and
dynamic phase range can be increased from 180MHz to 200MHz and
120° to 124° respectively. Furthermore the circular slot embedded
patch element can be designed at 10GHz resonant frequency with a
patch volume of 2.71mm3 as compared to 3.47mm3 required for
rectangular patch without slot.
Abstract: Recently, to cope with the rapidly changing
construction trend with aging infrastructures, modular bridge
technology has been studied actively. Modular bridge is easily
constructed by assembling standardized precast structure members in
the field. It will be possible to construct rapidly and reduce
construction cost efficiently. However, the shape of the transverse
connection of T-type girder newly developed between the segmented
modules is not verified. Therefore, the verification of the connection
shape is needed. In this study, shape of the modular T-girder bridge
transverse connection was analyzed by finite element model that was
verified in study which was verified model of transverse connection
using Abaqus. Connection angle was chosen as the parameter. The
result of analyses showed that optimal value of angle is 130 degree.
Abstract: The construction of a new airport or the extension of
an existing one requires massive investments and many times public
private partnerships were considered in order to make feasible such
projects. One characteristic of these projects is uncertainty with
respect to financial and environmental impacts on the medium to long
term. Another one is the multistage nature of these types of projects.
While many airport development projects have been a success, some
others have turned into a nightmare for their promoters.
This communication puts forward a new approach for airport
investment risk assessment. The approach takes explicitly into
account the degree of uncertainty in activity levels prediction and
proposes milestones for the different stages of the project for
minimizing risk. Uncertainty is represented through fuzzy dual theory
and risk management is performed using dynamic programming. An
illustration of the proposed approach is provided.
Abstract: Azadirachta excelsa or locally known as sentang are
frequently used as a traditional medicine by diabetes patients in
Malaysia. However, less attention has been given to their toxicity
effect. Thus, the study is an attempt to examine the protective effect
of A. excelsa on the pancreas and to determine possible toxicity
mediated by the extract. Diabetes was induced experimentally in rats
by high-fat-diet for 16 weeks followed by intraperitoneal injection of
streptozotocin at dosage of 35 mg/kg of body weight. Declination of
the fasting blood glucose level was observed after continuous
administration of A. excelsa for 14 days twice daily. This is due to the
refining structure of the pancreas. However, surprisingly, the plant
extract reduced the leukocytes, erythrocytes, hemoglobin, MCHC and
lymphocytes. In addition, the rat treated with the plant extract
exhibited increment in AST and eosinocytes level. Overall, the
finding shows that A. excelsa possesses antidiabetic activity by
improving the structure of pancreatic islet of Langerhans but
involved in ameliorating of hematology and biochemical parameters.
Abstract: In this study, six bacterial isolates of a slightly
thermophilic organism from the Sg. Klah hot spring, Malaysia were
successfully isolated and designated as M7T55D1, M7T55D2,
M7T55D3, M7T53D1, M7T53D2 and M7T53D3 respectively. The
bacterial isolates were screened for their cellulose hydrolytic ability
on Carboxymethlycellulose agar medium. The isolated bacterial
strains were identified morphologically, biochemically and
molecularly with the aid of 16S rDNA sequencing. All of the bacteria
showed their optimum growth at a slightly alkaline pH of 7.5 with a
temperature of 55°C. All strains were Gram-negative, non-spore
forming type, strictly aerobic, catalase-positive and oxidase-positive
with the ability to produce thermostable cellulase. Based on BLASTn
results, bacterial isolates of M7T55D2 and M7T53D1 gave the
highest homology (97%) with similarity to Tepidimonas ignava while
isolates M7T55D1, M7T55D3, M7T53D2 and M7T53D3 showed
their closest homology (97%-98%) with Tepidimonas thermarum.
These cellulolytic thermophiles might have a commercial potential to
produce valuable thermostable cellulase.
Abstract: This paper presents the variation of the dynamic
characteristics of a spindle with the change of bearing preload. The
correlations between the variation of bearing preload and fundamental
modal parameters were first examined by conducting vibration tests on
physical spindle units. Experimental measurements show that the
dynamic compliance and damping ratio associated with the
dominating modes were affected to vary with variation of the bearing
preload. When the bearing preload was slightly deviated from a
standard value, the modal frequency and damping ability also vary to
different extent, which further enable the spindle to perform with
different compliance. For the spindle used in this study, a standard
preload value set on bearings would enable the spindle to behave a
higher stiffness as compared with others with a preload variation. This
characteristic can be served as a reference to examine the variation of
bearing preload of spindle in assemblage or operation.
Abstract: In order to evaluate the performance of a unified power
flow controller (UPFC), mathematical models for steady state and
dynamic analysis are to be developed. The steady state model is
mainly concerned with the incorporation of the UPFC in load flow
studies. Several load flow models for UPFC have been introduced
in literature, and one of the most reliable models is the decoupled
UPFC model. In spite of UPFC decoupled load flow model simplicity,
it is more robust compared to other UPFC load flow models and it
contains unique capabilities. Some shortcoming such as additional
set of nonlinear equations are to be solved separately after the load
flow solution is obtained. The aim of this study is to investigate the
different control strategies that can be realized in the decoupled load
flow model (individual control and combined control), and the impact
of the location of the UPFC in the network on its control parameters.
Abstract: Most flexible rotors can be considered as beam-like
structures. In many cases, rotors are modeled as one-dimensional
bodies, made basically of beam-like shafts with rigid bodies attached
to them. This approach is typical of rotor dynamics, both analytical
and numerical, and several rotor dynamic codes, based on the finite
element method, follow this trend. In this paper, a finite element
model based on Timoshenko beam elements is utilized to analyze the
lateral dynamic behavior of a certain rotor-bearing system in
operating conditions.
Abstract: Biological conversion of biomass to methane has
received increasing attention in recent years. Grasses have been
explored for their potential anaerobic digestion to methane. In this
review, extensive literature data have been tabulated and classified.
The influences of several parameters on the potential of these
feedstocks to produce methane are presented. Lignocellulosic
biomass represents a mostly unused source for biogas and ethanol
production. Many factors, including lignin content, crystallinity of
cellulose, and particle size, limit the digestibility of the hemicellulose
and cellulose present in the lignocellulosic biomass. Pretreatments
have used to improve the digestibility of the lignocellulosic biomass.
Each pretreatment has its own effects on cellulose, hemicellulose and
lignin, the three main components of lignocellulosic biomass. Solidstate
anaerobic digestion (SS-AD) generally occurs at solid
concentrations higher than 15%. In contrast, liquid anaerobic
digestion (AD) handles feedstocks with solid concentrations between
0.5% and 15%. Animal manure, sewage sludge, and food waste are
generally treated by liquid AD, while organic fractions of municipal
solid waste (OFMSW) and lignocellulosic biomass such as crop
residues and energy crops can be processed through SS-AD. An
increase in operating temperature can improve both the biogas yield
and the production efficiency, other practices such as using AD
digestate or leachate as an inoculant or decreasing the solid content
may increase biogas yield but have negative impact on production
efficiency. Focus is placed on substrate pretreatment in anaerobic
digestion (AD) as a means of increasing biogas yields using today’s
diversified substrate sources.
Abstract: The emergence of the Semantic Web technology
increases day by day due to the rapid growth of multiple web pages.
Many standard formats are available to store the semantic web data.
The most popular format is the Resource Description Framework
(RDF). Querying large RDF graphs becomes a tedious procedure
with a vast increase in the amount of data. The problem of query
optimization becomes an issue in querying large RDF graphs.
Choosing the best query plan reduces the amount of query execution
time. To address this problem, nature inspired algorithms can be used
as an alternative to the traditional query optimization techniques. In
this research, the optimal query plan is generated by the proposed
SAPSO algorithm which is a hybrid of Simulated Annealing (SA)
and Particle Swarm Optimization (PSO) algorithms. The proposed
SAPSO algorithm has the ability to find the local optimistic result
and it avoids the problem of local minimum. Experiments were
performed on different datasets by changing the number of predicates
and the amount of data. The proposed algorithm gives improved
results compared to existing algorithms in terms of query execution
time.