Abstract: In this paper, a numerical simulation of a finned store
separating from a wing-pylon configuration has been studied and
validated. A dynamic unstructured tetrahedral mesh approach is
accomplished by using three grid sizes to numerically solving the
discretized three dimensional, inviscid and compressible Euler
equations. The method used for computations of separation of an
external store assuming quasi-steady flow condition. Computations of
quasi-steady flow have been directly coupled to a six degree-offreedom
(6DOF) rigid-body motion code to generate store
trajectories. The pressure coefficients at four different angular cuts
and time histories of various trajectory parameters and wing pressure
distribution during the store separation are compared for every grid
size with published experimental data.
Abstract: In the current work, a three-dimensional geometry of a
75% stenosed blood vessel is analyzed. Large eddy simulation (LES)
with the help of a dynamic subgrid scale Smagorinsky model is
applied to model the turbulent pulsatile flow. The geometry, the
transmural pressure and the properties of the blood and the elastic
boundary were based on clinical measurement data. For the flexible
wall model, a thin solid region is constructed around the 75%
stenosed blood vessel. The deformation of this solid region was
modelled as a deforming boundary to reduce the computational cost
of the solid model. Fluid-structure interaction is realized via a twoway
coupling between the blood flow modelled via LES and the
deforming vessel. The information of the flow pressure and the wall
motion was exchanged continually during the cycle by an arbitrary
Lagrangian-Eulerian method. The boundary condition of current time
step depended on previous solutions. The fluctuation of the velocity
in the post-stenotic region was analyzed in the study. The axial
velocity at normalized position Z=0.5 shows a negative value near
the vessel wall. The displacement of the elastic boundary was
concerned in this study. In particular, the wall displacement at the
systole and the diastole were compared. The negative displacement at
the stenosis indicates a collapse at the maximum velocity and the
deceleration phase.
Abstract: The flora of Bozdağ (Konya) and its surroundings
were investigated between 2003 and 2005 years; 700 herbarium
specimens belonging to 482 taxa, 257 genera and 57 families were
collected and identified from the area. The families which have the
most taxa in research area are Asteraceae 67 (14.0%), Fabaceae 60
(12.6%), Lamiaceae 57 (11.9%), Brassicaceae 34 (7.1%), Poaceae
30 (6.3%), Rosaceae 24 (5.0%), Caryophyllaceae 23 (4.8%),
Liliaceae 19 (4.0%), Boraginaceae 17 (3.6%), and Apiaceae 13
(2.7%).
The research area is in the district of Konya and is in the B4
square according to the Grid System. The phytogeographic elements
are represented in the study area as follows; Irano-Turanian 91
(18.9%), Mediterranean 72 (14.9%), Euro-Siberian 21 (4.3%). The
phytogeographic regions of 273 (56.6%) taxa are either multi-regional
or unknown. The number of endemic taxa is 79 (16.3%).
Abstract: Wireless Sensor Networks (WSNs) have wide variety
of applications and provide limitless future potentials. Nodes in
WSNs are prone to failure due to energy depletion, hardware failure,
communication link errors, malicious attacks, and so on. Therefore,
fault tolerance is one of the critical issues in WSNs. We study how
fault tolerance is addressed in different applications of WSNs. Fault
tolerant routing is a critical task for sensor networks operating in
dynamic environments. Many routing, power management, and data
dissemination protocols have been specifically designed for WSNs
where energy awareness is an essential design issue. The focus,
however, has been given to the routing protocols which might differ
depending on the application and network architecture.
Abstract: To determine the potential of a low cost Irish
engineered timber product to replace high cost solid timber for use in
bending active structures such as gridshells a single Irish engineered
timber product in the form of orientated strand board (OSB) was
selected. A comparative study of OSB and solid timber was carried
out to determine the optimum properties that make a material suitable
for use in gridshells. Three parameters were identified to be relevant
in the selection of a material for gridshells. These three parameters
are the strength to stiffness ratio, the flexural stiffness of
commercially available sections, and the variability of material and
section properties. It is shown that when comparing OSB against
solid timber, OSB is a more suitable material for use in gridshells that
are at the smaller end of the scale and that have tight radii of
curvature. Typically, for solid timber materials, stiffness is used as an
indicator for strength and engineered timber is no different. Thus, low
flexural stiffness would mean low flexural strength. However, when
it comes to bending active gridshells, OSB offers a significant
advantage. By the addition of multiple layers, an increased section
size is created, thus endowing the structure with higher stiffness and
higher strength from initial low stiffness and low strength materials
while still maintaining tight radii of curvature. This allows OSB to
compete with solid timber on large scale gridshells. Additionally, a
preliminary sustainability study using a set of sustainability indicators
was carried out to determine the relative sustainability of building a
large-scale gridshell in Ireland with a primary focus on economic
viability but a mention is also given to social and environmental
aspects. For this, the Savill garden gridshell in the UK was used as
the functional unit with the sustainability of the structural roof
skeleton constructed from UK larch solid timber being compared
with the same structure using Irish OSB. Albeit that the advantages of
using commercially available OSB in a bending active gridshell are
marginal and limited to specific gridshell applications, further study
into an optimised engineered timber product is merited.
Abstract: This paper proposes five level diode clamped Z source
Inverter. The existing PWM techniques used for ZSI are restricted for
two level. The two level Z Source Inverter have high harmonic
distortions which effects the performance of the grid connected PV
system. To improve the performance of the system the number of
voltage levels in the output waveform need to be increased. This
paper presents comparative analysis of a five level diode clamped Z
source Inverter with different carrier based Modified Pulse Width
Modulation techniques. The parameters considered for comparison
are output voltage, voltage gain, voltage stress across switch and total
harmonic distortion when powered by same DC supply. Analytical
results are verified using MATLAB.
Abstract: Wind energy offers a significant advantage such as no
fuel costs and no emissions from generation. However, wind energy
sources are variable and non-dispatchable. The utility grid is able to
accommodate the variability of wind in smaller proportion along with
the daily load. However, at high penetration levels, the variability can
severely impact the utility reserve requirements and the cost
associated with it. In this paper the impact of wind energy is
evaluated in detail in formulating the total utility cost. The objective
is to minimize the overall cost of generation while ensuring the
proper management of the load. Overall cost includes the curtailment
cost, reserve cost and the reliability cost, as well as any other penalty
imposed by the regulatory authority. Different levels of wind
penetrations are explored and the cost impacts are evaluated. As the
penetration level increases significantly, the reliability becomes a
critical question to be answered. Here we increase the penetration
from the wind yet keep the reliability factor within the acceptable
limit provided by NERC. This paper uses an economic dispatch (ED)
model to incorporate wind generation into the power grid. Power
system costs are analyzed at various wind penetration levels using
Linear Programming. The goal of this study is show how the
increases in wind generation will affect power system economics.
Abstract: In this paper, we consider the vehicle routing problem
with mixed fleet of conventional and heterogenous electric vehicles
and time dependent charging costs, denoted VRP-HFCC, in which
a set of geographically scattered customers have to be served by a
mixed fleet of vehicles composed of a heterogenous fleet of Electric
Vehicles (EVs), having different battery capacities and operating
costs, and Conventional Vehicles (CVs). We include the possibility
of charging EVs in the available charging stations during the routes
in order to serve all customers. Each charging station offers charging
service with a known technology of chargers and time dependent
charging costs. Charging stations are also subject to operating time
windows constraints. EVs are not necessarily compatible with all
available charging technologies and a partial charging is allowed.
Intermittent charging at the depot is also allowed provided that
constraints related to the electricity grid are satisfied.
The objective is to minimize the number of employed vehicles and
then minimize the total travel and charging costs.
In this study, we present a Mixed Integer Programming Model and
develop a Charging Routing Heuristic and a Local Search Heuristic
based on the Inject-Eject routine with different insertion methods. All
heuristics are tested on real data instances.
Abstract: The mechanics of rip currents are complex, involving
interactions between waves, currents, water levels and the bathymetry,
that present particular challenges for numerical models. Here,
the effects of a grid-spacing dependent horizontal mixing on the
wave-current interactions are studied. Near the shore, wave rays
diverge from channels towards bar crests because of refraction by
topography and currents, in a way that depends on the rip current
intensity which is itself modulated by the horizontal mixing. At
low resolution with the grid-spacing dependent horizontal mixing,
the wave motion is the same for both coupling modes because the
wave deviation by the currents is weak. In high resolution case,
however, classical results are found with the stabilizing effect of
the flow by feedback of waves on currents. Lastly, wave-current
interactions and the horizontal mixing strongly affect the intensity
of the three-dimensional rip velocity.
Abstract: Job Scheduling plays an important role for efficient
utilization of grid resources available across different domains and
geographical zones. Scheduling of jobs is challenging and NPcomplete.
Evolutionary / Swarm Intelligence algorithms have been
extensively used to address the NP problem in grid scheduling.
Artificial Bee Colony (ABC) has been proposed for optimization
problems based on foraging behaviour of bees. This work proposes a
modified ABC algorithm, Cluster Heterogeneous Earliest First Min-
Min Artificial Bee Colony (CHMM-ABC), to optimally schedule
jobs for the available resources. The proposed model utilizes a novel
Heterogeneous Earliest Finish Time (HEFT) Heuristic Algorithm
along with Min-Min algorithm to identify the initial food source.
Simulation results show the performance improvement of the
proposed algorithm over other swarm intelligence techniques.
Abstract: Shortfall of electrical energy in Pakistan is a challenge
adversely affecting its industrial output and social growth. As
elsewhere, Pakistan derives its electrical energy from a number of
conventional sources. The exhaustion of petroleum and conventional
resources, the rising costs coupled with extremely adverse climatic
effects are taking its toll especially on the under-developed countries
like Pakistan. As alternate, renewable energy sources like hydropower,
solar, wind, even bio-energy and a mix of some or all of them
could provide a credible alternative to the conventional energy
resources that would not only be cleaner but sustainable as well. As a
model, solar energy-based power grid for the near future has been
attempted to offset the energy shortfalls as a mix with our existing
sustainable natural energy resources. An assessment of solar energy
potential for electricity generation is being presented for fulfilling the
energy demands with higher level of reliability and sustainability.
This model is based on the premise that solar energy potential of
Pakistan is not only reliable but also sustainable. This research
estimates the present & future approaching renewable energy
resource specially the impact of solar energy based power grid for
mitigating energy shortage in Pakistan.
Abstract: As the current status and growth of Indian automobile
industry is remarkable, transportation sectors are the main concern in
terms of energy security and climate change. Due to rising demand of
fuel and its dependency on foreign countries that affects the GDP of
nation, suggests that penetration of electrical vehicle will increase in
near future. So in this context analysis is done if the 10 percent of
conventional vehicles including cars, three wheelers and two
wheelers becomes electrical vehicles in near future which is also a
part of Nations Electric Mobility Mission Plan then the saving which
improves the nation’s economy is analyzed in detail. Whether the
Indian electricity grid is capable of taking this load with current
generation and demand all over the country is also analyzed in detail.
Current situation of Indian grid is analyzed and how the gap between
generation and demand can be reduced is discussed in terms of
increasing generation capacity and energy conservation measures.
Electrical energy conservation measures in Industry and especially in
rural areas have been analyzed to improve performance of Indian
electricity grid in context of electrical vehicle penetration in near
future. Author was a part of Vishvakarma yojna in which energy
losses were measured in 255 villages of Gujarat and solutions were
suggested to mitigate them and corresponding reports was submitted
to the authorities of Gujarat government.
Abstract: Batteries of electric vehicles (BEV) are becoming
more attractive with the advancement of new battery technologies
and promotion of electric vehicles. BEV batteries are recharged on
board vehicles using either the grid (G2V for Grid to Vehicle) or
renewable energies in a stand-alone application (H2V for Home to
Vehicle). This paper deals with the modeling, sizing and control of a
photovoltaic stand-alone application that can charge the BEV at
home. The modeling approach and developed mathematical models
describing the system components are detailed. Simulation and
experimental results are presented and commented.
Abstract: Nowadays, Photovoltaic-PV Farms/ Parks and large
PV-Smart Grid Interface Schemes are emerging and commonly
utilized in Renewable Energy distributed generation. However, PVhybrid-
Dc-Ac Schemes using interface power electronic converters
usually has negative impact on power quality and stabilization of
modern electrical network under load excursions and network fault
conditions in smart grid. Consequently, robust FACTS based
interface schemes are required to ensure efficient energy utilization
and stabilization of bus voltages as well as limiting switching/fault
onrush current condition. FACTS devices are also used in smart grid-
Battery Interface and Storage Schemes with PV-Battery Storage
hybrid systems as an elegant alternative to renewable energy
utilization with backup battery storage for electric utility energy and
demand side management to provide needed energy and power
capacity under heavy load conditions. The paper presents a robust
interface PV-Li-Ion Battery Storage Interface Scheme for
Distribution/Utilization Low Voltage Interface using FACTS
stabilization enhancement and dynamic maximum PV power tracking
controllers.
Digital simulation and validation of the proposed scheme is done
using MATLAB/Simulink software environment for Low Voltage-
Distribution/Utilization system feeding a hybrid Linear-Motorized
inrush and nonlinear type loads from a DC-AC Interface VSC-6-
pulse Inverter Fed from the PV Park/Farm with a back-up Li-Ion
Storage Battery.
Abstract: This paper describes a logical method to enhance
security on the grid computing to restrict the misuse of the grid
resources. This method is an economic and efficient one to avoid the
usage of the special devices. The security issues, techniques and
solutions needed to provide a secure grid computing environment are
described. A well defined process for security management among
the resource accesses and key holding algorithm is also proposed. In
this method, the identity management, access control and
authorization and authentication are effectively handled.
Abstract: Frequency stability of microgrids under islanded
operation attracts particular attention recently. A new cooperative
frequency control strategy based on centralized multi-agent system
(CMAS) is proposed in this study. Based on this strategy, agents sent
data and furthermore each component has its own to center operating
decisions (MGCC).After deciding on the information, they are
returned. Frequency control strategies include primary and secondary
frequency control and disposal of multi-stage load in which this study
will also provide a method and algorithm for load shedding. This
could also be a big problem for the performance of micro-grid in
times of disaster. The simulation results show the promising
performance of the proposed structure of the controller based on
multi agent systems.
Abstract: This paper presents a study on Proportional Resonant
(PR) current control with additional PR harmonic compensators for
Grid Connected Photovoltaic (PV) Inverters. Both simulation and
experimental results will be presented. Testing was carried out on a
3kW Grid-Connected PV Inverter which was designed and
constructed for this research.
Abstract: In this study, we aim to demonstrate a microgrid
system experimental simulation for an easy understanding of a
large-scale microgrid system. This model is required for industrial
training and learning environments. However, in order to create an
exact representation of a microgrid system, the laboratory-scale
system must fulfill the requirements of a grid-connected inverter, in
which power values are assigned to the system to cope with the
intermittent output from renewable energy sources. Aside from that,
during fluctuations in load capacity, the grid-connected system must
be able to supply power from the utility grid side and microgrid side in
a balanced manner. Therefore, droop control is installed in the
inverter’s control board to maintain a balanced power sharing in both
sides. This power control in a stand-alone condition and droop control
in a grid-connected condition must be implemented in order to
maintain a stabilized system. Based on the experimental results, power
control and droop control can both be applied in the system by
comparing the experimental and reference values.
Abstract: In new energy development, wind power has boomed.
It is due to the proliferation of wind parks and their operation in
supplying the national electric grid with low cost and clean resources.
Hence, there is an increased need to establish a proactive
maintenance for wind turbine machines based on remote control and
monitoring. That is necessary with a real-time wireless connection in
offshore or inaccessible locations while the wired method has many
flaws. The objective of this strategy is to prolong wind turbine
lifetime and to increase productivity. The hardware of a remote
control and monitoring system for wind turbine parks is designed. It
takes advantage of GPRS or Wi-Max wireless module to collect data
measurements from different wind machine sensors through IP based
multi-hop communication. Computer simulations with Proteus ISIS
and OPNET software tools have been conducted to evaluate the
performance of the studied system. Study findings show that the
designed device is suitable for application in a wind park.
Abstract: This paper presents reliability indices evaluation of the
rotor core magnetization of the induction motor operated as a self
excited induction generator by using probability distribution approach
and Monte Carlo simulation. Parallel capacitors with calculated
minimum capacitive value across the terminals of the induction motor
operated as a SEIG with unregulated shaft speed have been connected
during the experimental study. A three phase, 4 poles, 50Hz, 5.5 hp,
12.3A, 230V induction motor coupled with DC Shunt Motor was
tested in the electrical machine laboratory with variable reactive loads.
Based on this experimental study, it is possible to choose a reliable
induction machines operated as a SEIG for unregulated renewable
energy application in remote area or where grid is not available.
Failure density function, cumulative failure distribution function,
survivor function, hazard model, probability of success and
probability of failure for reliability evaluation of the three phase
induction motor operating as a SEIG have been presented graphically
in this paper.