Abstract: A biocompatible ferrofluid have been prepared by coprecipitation
of FeCl2.4H2O and FeCl3.6H2O under ultrasonic
irradiation and with NaOH as alkaline agent. Cystein was also used
as capping agent in the solution. Magnetic properties of the produced
ferrofluid were then determined by VSM test and magnetite
nanoparticles were characterized by XRD and TEM techniques. The
effect of surfactant to Fe ion weight ratio was also studied during this
project by using two different amount of Dextran. Results showed the
presence of a biocompatible superparamagnetic ferrofluid including
magnetite nanoparticles with particle size ranging under 20 nm. The
increase in the surfactant content results in the narrowing of the size
distribution and reduction of the particle size and more solution
stability.
Abstract: Automatic tube current modulation (ATCM) systems are available for all CT manufacturers and are used for the majority of patients. Understanding how the systems work and their influence on patient dose and image quality is important for CT users, in order to gain the most effective use of the systems. In the present study, a new phantom was used for evaluating dose distribution and image quality under the ATCM operation for the Toshiba Aquilion 64 CT scanner using different ATCM options and a fixed mAs technique. A routine chest, abdomen and pelvis (CAP) protocol was selected for study and Gafchromic film was used to measure entrance surface dose (ESD), peripheral dose and central axis dose in the phantom. The results show the dose reductions achievable with various ATCM options, in relation with the target noise. The doses and image noise distribution were more uniform when the ATCM system was implemented compared with the fixed mAs technique. The lower limit set for the tube current will affect the modulations especially for the lower dose option. This limit prevented the tube current being reduced further and therefore the lower dose ATCM setting resembled a fixed mAs technique. Selection of a lower tube current limit is likely to reduce doses for smaller patients in scans of chest and neck regions.
Abstract: The motivation for adaptive modulation and coding is
to adjust the method of transmission to ensure that the maximum
efficiency is achieved over the link at all times. The receiver
estimates the channel quality and reports it back to the transmitter.
The transmitter then maps the reported quality into a link mode. This
mapping however, is not a one-to-one mapping. In this paper we
investigate a method for selecting the proper modulation scheme.
This method can dynamically adapt the mapping of the Signal-to-
Noise Ratio (SNR) into a link mode. It enables the use of the right
modulation scheme irrespective of changes in the channel conditions
by incorporating errors in the received data. We propose a Markov
model for this method, and use it to derive the average switching
thresholds and the average throughput. We show that the average
throughput of this method outperforms the conventional threshold
method.
Abstract: This study aimed at developing a forecasting model on the number of Dengue Haemorrhagic Fever (DHF) incidence in Northern Thailand using time series analysis. We developed Seasonal Autoregressive Integrated Moving Average (SARIMA) models on the data collected between 2003-2006 and then validated the models using the data collected between January-September 2007. The results showed that the regressive forecast curves were consistent with the pattern of actual values. The most suitable model was the SARIMA(2,0,1)(0,2,0)12 model with a Akaike Information Criterion (AIC) of 12.2931 and a Mean Absolute Percent Error (MAPE) of 8.91713. The SARIMA(2,0,1)(0,2,0)12 model fitting was adequate for the data with the Portmanteau statistic Q20 = 8.98644 ( x20,95= 27.5871, P>0.05). This indicated that there was no significant autocorrelation between residuals at different lag times in the SARIMA(2,0,1)(0,2,0)12 model.
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: Biodiesel production results in glycerol production as
the main by-product in biodiesel industry.One of the utilizations of
glycerol obtained from biodiesel production is as a cement grinding
aid (CGA). Results showed that crude glycerol content was 40.19%
whereas pure glycerol content was 82.15%. BSS value of the cement
with CGA supplementation was higher than that of nonsupplemented
cement (blank) indicating that CGA-supplemented
cement had higher fineness than the non-supplemented one. It was
also found that pure glycerol 95% and TEA 5% at 80ºC was the
optimum CGA used to result in finest cement with BSS value of
4.836 cm2/g. Residue test showed that the smallest percent residue
value (0.11%) was obtained in cement with supplementation of pure
glycerol 95% and TEA 5%. Results of residue test confirmed those of
BSS test showing that cement with supplementation of pure glycerol
95% and TEA 5% had the finest particle size.
Abstract: The purpose of this paper is to provide an overview on methodological aspects of the information technology outsourcing (ITO) surveys, in an attempt to improve the data quality and reporting in survey research. It is based on a review of thirty articles on ITO surveys and focuses on two commonly explored dimensions of ITO, namely what are outsourced and why should there be ITO. This study highlights weaknesses in ITO surveys including lack of a clear definition of population, lack of information regarding the sampling method used, not citing the response rate, no information pertaining to pilot testing of survey instrument and absence of information on internal validity in the use or reporting of surveys. This study represents an attempt with a limited scope to point to shortfalls in the use survey methodology in ITO, and thus raise awareness among researchers in enhancing the reliability of survey findings.
Abstract: This paper reports the results of an experimental study
conducted to characterise the gas-liquid multiphase flows
experienced within a vertical riser transporting a range of gas-liquid
flow rates. The scale experiments were performed using an
air/silicone oil mixture within a 6 m long riser. The superficial air
velocities studied ranged from 0.047 to 2.836 m/ s, whilst
maintaining a liquid superficial velocity at 0.047 m/ s. Measurements
of the mean cross-sectional and time average radial void fraction
were obtained using a wire mesh sensor (WMS). The data were
recorded at an acquisition frequency of 1000 Hz over an interval of
60 seconds. For the range of flow conditions studied, the average
void fraction was observed to vary between 0.1 and 0.9. An analysis
of the data collected concluded that the observed void fraction was
strongly affected by the superficial gas velocity, whereby the higher
the superficial gas velocity, the higher was the observed average void
fraction. The average void fraction distributions observed were in
good agreement with the results obtained by other researchers. When
the air-silicone oil flows were fully developed reasonably symmetric
profiles were observed, with the shape of the symmetry profile being
strongly dependent on the superficial gas velocity.
Abstract: This paper describes an automated event detection and location system for water distribution pipelines which is based upon low-cost sensor technology and signature analysis by an Artificial
Neural Network (ANN). The development of a low cost failure sensor which measures the opacity or cloudiness of the local water
flow has been designed, developed and validated, and an ANN based system is then described which uses time series data produced by
sensors to construct an empirical model for time series prediction and
classification of events. These two components have been installed,
tested and verified in an experimental site in a UK water distribution
system. Verification of the system has been achieved from a series of
simulated burst trials which have provided real data sets. It is concluded that the system has potential in water distribution network
management.
Abstract: The Learning Management Systems present learning
environment which offers a collection of e-learning tools in a
package that allows a common interface and information sharing
among the tools. South East European University initial experience
in LMS was with the usage of the commercial LMS-ANGEL. After a
three year experience on ANGEL usage because of expenses that
were very high it was decided to develop our own software. As part
of the research project team for the in-house design and development
of the new LMS, we primarily had to select the features that would
cover our needs and also comply with the actual trends in the area of
software development, and then design and develop the system. In
this paper we present the process of LMS in-house development for
South East European University, its architecture, conception and
strengths with a special accent on the process of migration and
integration with other enterprise applications.
Abstract: This paper presents a design method of self-tuning
Quantitative Feedback Theory (QFT) by using improved deadbeat
control algorithm. QFT is a technique to achieve robust control with
pre-defined specifications whereas deadbeat is an algorithm that
could bring the output to steady state with minimum step size.
Nevertheless, usually there are large peaks in the deadbeat response.
By integrating QFT specifications into deadbeat algorithm, the large
peaks could be tolerated. On the other hand, emerging QFT with
adaptive element will produce a robust controller with wider
coverage of uncertainty. By combining QFT-based deadbeat
algorithm and adaptive element, superior controller that is called selftuning
QFT-based deadbeat controller could be achieved. The output
response that is fast, robust and adaptive is expected. Using a grain
dryer plant model as a pilot case-study, the performance of the
proposed method has been evaluated and analyzed. Grain drying
process is very complex with highly nonlinear behaviour, long delay,
affected by environmental changes and affected by disturbances.
Performance comparisons have been performed between the
proposed self-tuning QFT-based deadbeat, standard QFT and
standard dead-beat controllers. The efficiency of the self-tuning QFTbased
dead-beat controller has been proven from the tests results in
terms of controller’s parameters are updated online, less percentage
of overshoot and settling time especially when there are variations in
the plant.
Abstract: The present study has been taken to explore the
screening of in vitro antimicrobial activities of D-galactose-binding
sponge lectin (HOL-30). HOL-30 was purified from the marine
demosponge Halichondria okadai by affinity chromatography. The
molecular mass of the lectin was determined to be 30 kDa with a
single polypeptide by SDS-PAGE under non-reducing and reducing
conditions. HOL-30 agglutinated trypsinized and glutaraldehydefixed
rabbit and human erythrocytes with preference for type O
erythrocytes. The lectin was subjected to evaluation for inhibition of
microbial growth by the disc diffusion method against eleven human
pathogenic gram-positive and gram-negative bacteria. The lectin
exhibited strong antibacterial activity against gram-positive bacteria,
such as Bacillus megaterium and Bacillus subtilis. However, it did
not affect against gram-negative bacteria such as Salmonella typhi
and Escherichia coli. The largest zone of inhibition was recorded of
Bacillus megaterium (12 in diameter) and Bacillus subtilis (10 mm in
diameter) at a concentration of the lectin (250 μg/disc). On the other
hand, the antifungal activity of the lectin was investigated against six
phytopathogenic fungi based on food poisoning technique. The lectin
has shown maximum inhibition (22.83%) of mycelial growth of
Botrydiplodia theobromae at a concentration of 100 μg/mL media.
These findings indicate that the lectin may be of importance to
clinical microbiology and have therapeutic applications.
Abstract: A total of 33,680 nuclear power plants (NPPs) workers were monitored and recorded from 1990 to 2007. According to the record, the average individual radiation dose has been decreasing continually from it 3.20 mSv/man in 1990 to 1.12 mSv/man at the end of 2007. After the International Commission on Radiological Protection (ICRP) 60 recommendation was generalized in South Korea, no nuclear power plant workers received above 20 mSv radiation, and the numbers of relatively highly exposed workers have been decreasing continuously. The age distribution of radiation workers in nuclear power plants was composed of mainly 20-30- year-olds (83%) for 1990 ~ 1994 and 30-40-year-olds (75%) for 2003 ~ 2007. The difference in individual average dose by age was not significant. Most (77%) of NPP radiation exposures from 1990 to 2007 occurred mostly during the refueling period. With regard to exposure type, the majority of exposures were external exposures, representing 95% of the total exposures, while internal exposures represented only 5%. External effective dose was affected mainly by gamma radiation exposure, with an insignificant amount of neutron exposure. As for internal effective dose, tritium (3H) in the pressurized heavy water reactor (PHWR) was the biggest cause of exposure.
Abstract: This paper presents the optimal design and development
of an axial flux motor for blood pump application. With the design
objective of maximizing the motor efficiency and torque, different
topologies of AFPM machine has been examined. Selection of
optimal magnet fraction, Halbach arrangement of rotor magnets and
the use of Soft Magnetic Composite (SMC) material for the stator
core results in a novel motor with improved efficiency and torque
profile. The results of the 3D Finite element analysis for the novel
motor have been shown.
Abstract: Attachment of the circulating monocytes to the
endothelium is the earliest detectable events during formation of
atherosclerosis. The adhesion molecules, chemokines and matrix
proteases genes were identified to be expressed in atherogenesis.
Expressions of these genes may influence structural integrity of the
luminal endothelium. The aim of this study is to relate changes in the
ultrastructural morphology of the aortic luminal surface and gene
expressions of the endothelial surface, chemokine and MMP-12 in
normal and hypercholesterolemic rabbits. Luminal endothelial
surface from rabbit aortic tissue was examined by scanning electron
microscopy (SEM) using low vacuum mode to ascertain
ultrastructural changes in development of atherosclerotic lesion. Gene
expression of adhesion molecules, MCP-1 and MMP-12 were studied
by Real-time PCR. Ultrastructural observations of the aortic luminal
surface exhibited changes from normal regular smooth intact
endothelium to irregular luminal surface including marked globular
appearance and ruptures of the membrane layer. Real-time PCR
demonstrated differentially expressed of studied genes in
atherosclerotic tissues. The appearance of ultrastructural changes in
aortic tissue of hypercholesterolemic rabbits is suggested to have
relation with underlying changes of endothelial surface molecules,
chemokine and MMP-12 gene expressions.
Abstract: In-vitro mouse co-culture of E14 embryonic stem cells
(ESCs) and OP9 stromal cells can recapitulate the earliest stages of
haematopoietic development, not accessible in human embryos,
supporting both haemogenic precursors and their primitive
haematopoietic progeny. 1α, 25-Dihydroxy-vitamin D3 (VD3) has
been demonstrated to be a powerful differentiation inducer for a wide
variety of neoplastic cells, and could enhance early differentiation of
ESCs into blood cells in E14/OP9 co-culture. This study aims to
ascertain whether VD3 is key in promoting differentiation and
suppressing proliferation, by separately investigating the effects of
VD3 on the proliferation phase of the E14 cell line and on stromal
OP9 cells.The results showed that VD3 inhibited the proliferation of
the cells in a dose-dependent manner, quantitatively by decreased cell
number, and qualitatively by alkaline-phosphatase staining that
revealed significant differences between VD3-treated and untreated
cells, characterised by decreased enzyme expression (colourless
cells). Propidium-iodide cell-cycle analyses showed no significant
percentage change in VD3-treated E14 and OP9 cells within their G
and S-phases, compared to the untreated controls, despite the
increased percentage of G-phase compared to the S-phase in a dosedependent
manner. These results with E14 and OP9 cells indicate that
adequate VD3 concentration enhances cellular differentiation and
inhibits proliferation. The results also suggest that if E14 and OP9
cells were co-cultured andVD3-treated, there would be furtherenhanced
differentiation of ESCs into blood cells.
Abstract: During recent years wind turbine technology has
undergone rapid developments. Growth in size and the optimization
of wind turbines has enabled wind energy to become increasingly
competitive with conventional energy sources. As a result today-s
wind turbines participate actively in the power production of several
countries around the world. These developments raise a number of
challenges to be dealt with now and in the future. The penetration of
wind energy in the grid raises questions about the compatibility of the
wind turbine power production with the grid. In particular, the
contribution to grid stability, power quality and behavior during fault
situations plays therefore as important a role as the reliability. In the
present work, we addressed two fault situations that have shown their
influence on the generator and the behavior of the wind over the
defects which are briefly discussed based on simulation results.
Abstract: In this study, the contact problem of a layered composite which consists of two materials with different elastic constants and heights resting on two rigid flat supports with sharp edges is considered. The effect of gravity is neglected. While friction between the layers is taken into account, it is assumed that there is no friction between the supports and the layered composite so that only compressive tractions can be transmitted across the interface. The layered composite is subjected to a uniform clamping pressure over a finite portion of its top surface. The problem is reduced to a singular integral equation in which the contact pressure is the unknown function. The singular integral equation is evaluated numerically and the results for various dimensionless quantities are presented in graphical forms.
Abstract: In this paper, all-optical signal processors that perform
both microwave mixing and bandpass filtering in a radio-over-fiber
(RoF) link are presented. The key device is a Mach-Zehnder
modulator (MZM) which performs all-optical microwave mixing. An
up-converted microwave signal is obtained and other unwanted
frequency components are suppressed at the end of the fiber span.