Abstract: The use of wind energy for electricity generation is
growing rapidly across the world and in Portugal. However, the
geographical characteristics of the country along with the average
wind regime and with the environmental restrictions imposed to these
projects create limitations to the exploit of the onshore wind
resource. The best onshore wind spots are already committed and the
possibility of offshore wind farms in the Portuguese cost is now
being considered. This paper aims to make a contribution to the
evaluation of offshore wind power projects in Portugal. The technical
restrictions are addressed and the strategic, environmental and
financial interest of the project is analysed from the private company
and public points of view. The results suggest that additional support
schemes are required to ensure private investors interest for these
projects. Assuming an approach of direct substitution of energy
sources for electricity generation, the avoided CO2 equivalent
emissions for an offshore wind power project were quantified. Based
on the conclusions, future research is proposed to address the
environmental and social impacts of these projects.
Abstract: This paper presents the experimental results of
comparison between leakage currents and discharge currents. The leakage currents were obtained on polluted porcelain insulator.
Whereas, the discharge currents were obtained on lightly artificial
polluted porcelain specimen. The conducted measurements were
leakage current or discharge current and applied voltage. The insulator or specimen was in a hermetically sealed chamber, and the
current waveforms were analyzed using FFT.
The result indicated that the leakage current (LC) on low RH condition the fifth harmonic would be visible, and followed by the
seventh harmonic. The insulator had capacitive property. Otherwise,
on 99% relative humidity, the fifth harmonic would also be visible,
and the phase angle reached up to 12.2 degree. Whereas, on discharge current, the third harmonic would be visible, and followed
by fifth harmonic. The third harmonic would increase as pressure reduced. On this condition, the specimen had a non-linear characteristics
Abstract: It is claimed that a new style of urban planning and
policy intertwined with ICT is emerging and urban planning and ICT
policy are no longer considered as separate disciplines. The
interactions between electronic spaces and urban spaces are so
complex and uncertain that confront urban planners and policy makers
with great challenges. However, the assumption about the relationship
between ICT and urban planning is mainly based on North American
and European experiences. In the light of empirical evidence from
Taipei City, this paper shows that this new type of urban planning and
policy intertwined with ICT has existed in Asian city for a decade as
well. Based on these results, this paper further reviews how the Taipei
City government implements this new type of urban ICT planning and
the validity and realism of its underlying assumptions. Finally, it also
explores the extent to which urban ICT planning could promote
positive synergies between physical and electronic developments.
Abstract: Space Vector Modulation (SVM) is an optimum Pulse Width Modulation (PWM) technique for an inverter used in a variable frequency drive applications. It is computationally rigorous and hence limits the inverter switching frequency. Increase in switching frequency can be achieved using Neural Network (NN) based SVM, implemented on application specific chips. This paper proposes a neural network based SVM technique for a Voltage Source Inverter (VSI). The network proposed is independent of switching frequency. Different architectures are investigated keeping the total number of neurons constant. The performance of the inverter is compared for various switching frequencies for different architectures of NN based SVM. From the results obtained, the network with minimum resource and appropriate word length is identified. The bit precision required for this application is identified. The network with 8-bit precision is implemented in the IC XCV 400 and the results are presented. The performance of NN based general purpose SVM with higher bit precision is discussed.
Abstract: This paper addresses integration issues in supply
chain, and tries to investigate how different aspects of integration are
linked with some product features. Integration in this study is
interpreted as "internal", "upstream" (supply), and "downstream"
(demand). Two features of product innovative and quality are
considered. To examine the relationships between supply chain
integrations – as mentioned above, and product features, this research
follows the survey method in automotive industry.The results imply
that supply chain upstream integration has a higher impact on product
quality, comparing to internal and supply chain downstream
integrations. It is also found that the influence of supply chain
downstream integration on product innovation is greater than other
variables. In brief, this study mainly tackles the importance of
specific level of supply chain integrations and its effects on two
product features.
Abstract: This study assessed the effects of climate change on
Thai soybeans under simulation situations. Our study is focused on
temperature variability and effects on growth, yield, and genetic
changes in 2 generations of Chiang Mai 60 cultivars. In the
experiment, soybeans were exposed to 3 levels of air temperature for
8 h day-1 in an open top chamber for 2 cropping periods. Air
temperature levels in each treatment were controlled at 30-33°C (±
2.3) for LT-treatment, 33-36°C ( ± 2.4) for AT-treatment, and 36-40
°C ( ± 3.2) for HT-treatment, respectively. Positive effects of high
temperature became obvious at the maturing stage when yield
significantly increased in both cropping periods. Results in growth
indicated that shoot length at the pre-maturing stage
(V3-R3) was more positively affected by high temperature than at the
maturing stage. However, the positive effect on growth under high
temperature was not found in the 2nd cropping period. Finally, genetic
changes were examined in phenotype characteristics by the AFLPs
technique. The results showed that the high temperature factor clearly
caused genetic change in the soybeans and showed more alteration in
the 2nd cropping period.
Abstract: The paper describes the workings for four models of
CONWIP systems used till date; the basic CONWIP system, the
hybrid CONWIP system, the multi-product CONWIP system, and the
parallel CONWIP system. The final novel model is introduced in this
paper in a general form. These models may be adopted for analysis
for both simulation studies and implementation on the shop floor. For
each model, input parameters of interest are highlighted and their
impacts on several system performance measures are addressed.
Abstract: We investigate the sufficient condition under which each positive b-weakly compact operator is Dunford-Pettis. We also investigate the necessary condition on which each positive b-weakly compact operator is Dunford-Pettis. Necessary condition on which each positive b-weakly compact operator is weakly compact is also considered. We give the operator that is semi-compact, but it is not bweakly. We present a necessary and sufficient condition under which each positive semi-compact operator is b-weakly compact.
Abstract: The voice signal in Voice over Internet protocol (VoIP) system is processed through the best effort policy based IP network, which leads to the network degradations including delay, packet loss jitter. The work in this paper presents the implementation of finite impulse response (FIR) filter for voice quality improvement in the VoIP system through distributed arithmetic (DA) algorithm. The VoIP simulations are conducted with AMR-NB 6.70 kbps and G.729a speech coders at different packet loss rates and the performance of the enhanced VoIP signal is evaluated using the perceptual evaluation of speech quality (PESQ) measurement for narrowband signal. The results show reduction in the computational complexity in the system and significant improvement in the quality of the VoIP voice signal.
Abstract: The research investigates the “impact of VLE on mathematical concepts acquisition of the special education needs (SENs) students at KS4 secondary education sector" in England. The overall aim of the study is to establish possible areas of difficulties to approach for above or below knowledge standard requirements for KS4 students in the acquisition and validation of basic mathematical concepts. A teaching period, in which virtual learning environment (Fronter) was used to emphasise different mathematical perception and symbolic representation was carried out and task based survey conducted to 20 special education needs students [14 actually took part]. The result shows that students were able to process information and consider images, objects and numbers within the VLE at early stages of acquisition process. They were also able to carry out perceptual tasks but with limiting process of different quotient, thus they need teacher-s guidance to connect them to symbolic representations and sometimes coach them through. The pilot study further indicates that VLE curriculum approaches for students were minutely aligned with mathematics teaching which does not emphasise the integration of VLE into the existing curriculum and current teaching practice. There was also poor alignment of vision regarding the use of VLE in realisation of the objectives of teaching mathematics by the management. On the part of teacher training, not much was done to develop teacher-s skills in the technical and pedagogical aspects of VLE that is in-use at the school. The classroom observation confirmed teaching practice will find a reliance on VLE as an enhancer of mathematical skills, providing interaction and personalisation of learning to SEN students.
Abstract: Several wireless networks security standards have been proposed and widely implemented in both business and home environments in order to protect the network from unauthorized access. However, the implementation of such standards is usually achieved by network administrators without even knowing the standards- weaknesses and strengths. The intention of this paper is to evaluate and analyze the impact over the network-s security due to the implementation of the wireless networks security standards WEP, WPA and WLAN 802.1X.
Abstract: If an unsteady heat transfer or heat impulse happens in
part of the cryogenic pipeline system of large space environment
simulation equipment while running in vacuum environment, it will
lead to abnormal flow of the cryogenic fluid in the pipeline. When the
situation gets worse, the cryogenic fluid in the pipeline will have phase
change and a gas block which results in the malfunction of the
cryogenic pipeline system. Referring to the structural parameter of a
typical cryogenic pipeline system and the basic equation, an analytical
model and a calculation model for cryogenic pipeline system can be
built. The various factors which influence the thermal resistance of a
cryogenic pipeline system can be analyzed and calculated by using the
qualitative analysis relation deduced for thermal resistance of pipeline.
The research conclusion could provide theoretical support for the
design and operation of a cryogenic pipeline system
Abstract: This study describes the preparation of a novel proton
conducting membranes based on bacterial cellulose (BC) modified by
grafting of 2-acrylamido-2-methyl-1 -propanesulfonic acid (AMPS)
through UV-induced graft polymerization. These AMPS-g-BC
membranes have been characterized by various techniques including
FTIR, SEM and TGA, to find their successful grafting of AMPS on
BC, surface morphology and thermal stability, respectively. Physical
properties of AMPS-g-BC membranes have been assessed in terms of
Lamda value( λ ), ion exchange capacity(IEC) and proton
conductivity. The relationship between degree of grafting and AMPS
concentration used for grafting has been determined by weight gain
method. An optimum proton conductivity equal to 2.89x10-2 S cm-1
and IEC value equal to 1.79 mmol g-1 have been obtained when 20
wt% AMPS concentration is used for grafting (i.e. the corresponding
membrane is notated as AMPS20-g-BC).
Abstract: Business and IT alignment has continued as a
top concern for business and IT executives for almost three
decades. Many researchers have conducted empirical studies on
the relationship between business-IT alignment and performance.
Yet, these approaches, lacking a social perspective, have had little
impact on sustaining performance and competitive advantage. In
addition to the limited alignment literature that explores
organisational learning that is represented in shared understanding,
communication, cognitive maps and experiences.
Hence, this paper proposes an integrated process that enables
social and intellectual dimensions through the concept of
organisational learning. In particular, the feedback and feedforward
process which provide a value creation across dynamic
multilevel of learning. This mechanism enables on-going
effectiveness through development of individuals, groups and
organisations, which improves the quality of business and IT
strategies and drives to performance.
Abstract: The three-dimensional incompressible flow past a
rectangular open cavity is investigated, where the aspect ratio of the
cavity is considered as 4. The principle objective is to use large-eddy
simulation to resolve and control the large-scale structures, which are
largely responsible for flow oscillations in a cavity. The flow past an
open cavity is very common in aerospace applications and can be a
cause of acoustic source due to hydrodynamic instability of the shear
layer and its interactions with the downstream edge. The unsteady
Navier-stokes equations have been solved on a staggered mesh using
a symmetry-preserving central difference scheme. Synthetic jet has
been used as an active control to suppress the cavity oscillations in
wake mode for a Reynolds number of ReD = 3360. The effect of
synthetic jet has been studied by varying the jet amplitude and
frequency, which is placed at the upstream wall of the cavity. The
study indicates that there exits a frequency band, which is larger than
a critical value, is effective in attenuating cavity oscillations when
blowing ratio is more than 1.0.
Abstract: This paper tries to study the effect of geosynthetic inclusion on the improvement of the load-settlement characters of two layered soil. In addition, the effect of geogrid and geotextile in reduction of the required thickness of subbase layer in unpaved roads is studied. Considering the vast application of bearing ratio tests in road construction projects, this test is used in present investigation. Bearing ratio tests were performed on two layered soil including a granular soil layer at the top (as the subbase layer) and a weak clayey soil placed at the bottom (as the subgrade layer). These tests were performed for different conditions including unreinforced and reinforced by geogrid and geotextile and three thicknesses for top layer soil (subbase layer). In the reinforced condition the reinforcing element was placed on the interface of the top granular layer and the beneath clayey layer to study the separation effect of geosynthetics. In all tests the soils (both granular and clayey soil layers) were compacted according to optimum water content. At the end, the diagrams were plotted and were compared with each other. Furthermore, a comparison between geogrids and geotextiles behaviors on two layer soil is done in this paper. The results show an increase in compression strength of reinforced specimen in comparison with unreinforced soil sample. The effect of geosynthetic inclusion reduces by increasing the subbase thickness. In addition it was found that geogrids have more desirable behavior rather than geotextiles due to interlocking with the subbase layer aggregates.
Abstract: This paper proposes an implementation for the
directed diffusion paradigm aids in studying this paradigm-s
operations and evaluates its behavior according to this
implementation. The directed diffusion is evaluated with respect to
the loss percentage, lifetime, end-to-end delay, and throughput.
From these evaluations some suggestions and modifications are
proposed to improve the directed diffusion behavior according to
this implementation with respect to these metrics. The proposed
modifications reflect the effect of local path repair by introducing a
technique called Loop-free Local Path Repair (LLPR) which
improves the directed diffusion behavior especially with respect to
packet loss percentage by about 92.69%. Also LLPR improves the
throughput and end-to-end delay by about 55.31% and 14.06%
respectively, while the lifetime decreases by about 29.79%.
Abstract: Multi-level voltage source inverters offer several
advantages such as; derivation of a refined output voltage with
reduced total harmonic distortion (THD), reduction of voltage ratings
of the power semiconductor switching devices and also the reduced
electro-magnetic-interference problems etc. In this paper, new
carrier-overlapped phase-disposition or sub-harmonic sinusoidal
pulse width modulation (CO-PD-SPWM) and also the carrieroverlapped
phase-disposition space vector modulation (CO-PDSVPWM)
schemes for a six-level diode-clamped inverter topology
are proposed. The principle of the proposed PWM schemes is similar
to the conventional PD-PWM with a little deviation from it in the
sense that the triangular carriers are all overlapped. The overlapping
of the triangular carriers on one hand results in an increased number
of switchings, on the other hand this facilitates an improved spectral
performance of the output voltage. It is demonstrated through
simulation studies that the six-level diode-clamped inverter with the
use of CO-PD-SPWM and CO-PD-SVPWM proposed in this paper is
capable of generating multiple levels in its output voltage. The
advantages of the proposed PWM schemes can be derived to benefit,
especially at lower modulation indices of the inverter and hence this
aspect of the proposed PWM schemes can be well exploited in high
power applications requiring low speeds of operation of the drive.
Abstract: The main objectif of this paper is to present a tool that
we have developed subject to characterize and modelling indoor radio
channel propagation at millimetric wave. The tool is based on the
ray tracing technique (RTT). As, in realistic environment we cannot
neglect the significant impact of Human Body Shadowing and other
objects in motion on indoor 60 GHz propagation channel. Hence,
our proposed model allows a simulation of propagation in a dynamic
indoor environment. First, we describe a model of human body.
Second, RTT with this model is used to simulate the propagation
of millimeter waves in the presence of persons in motion. Results
of the simulation show that this tool gives results in agreement with
those reported in the literature. Specially, the effects of people motion
on temporal channel properties.
Abstract: Optimal capacitor allocation in distribution systems
has been studied for a long times. It is an optimization problem
which has an objective to define the optimal sizes and locations of
capacitors to be installed. In this works, an overview of capacitor
placement problem in distribution systems is briefly introduced. The
objective functions and constraints of the problem are listed and the
methodologies for solving the problem are summarized.