Abstract: This paper presents a studyof the impact of reference
node locations on the accuracy of the indoor positioning systems. In
particular, we analyze the localization accuracy of the RSSI database
mapping techniques, deploying on the IEEE 802.15.4 wireless
networks. The results show that the locations of the reference nodes
used in the positioning systems affect the signal propagation
characteristics in the service area. Thisin turn affects the accuracy of the wireless indoor positioning system. We found that suitable
location of reference nodes could reduce the positioning error upto 35 %.
Abstract: The goal of admission control is to support the Quality
of Service demands of real-time applications via resource reservation
in IP networks. In this paper we introduce a novel Dynamic
Admission Control (DAC) mechanism for IP networks. The DAC
dynamically allocates network resources using the previous network
pattern for each path and uses the dynamic admission algorithm to
improve bandwidth utilization using bandwidth brokers. We evaluate
the performance of the proposed mechanism through trace-driven
simulation experiments in view point of blocking probability,
throughput and normalized utilization.
Abstract: In hypersonic environments, the aerothermal effect
makes it difficult for the optical side windows of optical guided
missiles to withstand high heat. This produces cracking or breaking,
resulting in an inability to function. This study used computational
fluid mechanics to investigate the external cooling jet conditions of
optical side windows. The turbulent models k-ε and k-ω were
simulated. To be in better accord with actual aerothermal
environments, a thermal radiation model was added to examine
suitable amounts of external coolants and the optical window
problems of aero-thermodynamics. The simulation results indicate that
when there are no external cooling jets, because airflow on the optical
window and the tail groove produce vortices, the temperatures in these
two locations reach a peak of approximately 1600 K. When the
external cooling jets worked at 0.15 kg/s, the surface temperature of
the optical windows dropped to approximately 280 K. When adding
thermal radiation conditions, because heat flux dissipation was faster,
the surface temperature of the optical windows fell from 280 K to
approximately 260 K. The difference in influence of the different
turbulence models k-ε and k-ω on optical window surface temperature
was not significant.
Abstract: The increasing popularity of wireless technologies
and mobile computing devices has enabled new application areas and
research. One of these new areas is pervasive systems in urban
environments, because urban environments are characterized by high
concentration of these technologies and devices. In this paper we will
show the process of pervasive system design in urban environments,
using as use case a local zoo in Cali, Colombia. Based on an
ethnographic studio, we present the design of a pervasive system for
urban computing based on service oriented architecture to controlled
environment of Cali Zoo. In this paper, the reader will find a
methodological approach for the design of similar systems, using
data collection methods, conceptual frameworks for urban
environments and considerations of analysis and design of service
oriented systems.
Abstract: The mobile users with Laptops need to have an
efficient access to i.e. their home personal data or to the Internet from
any place in the world, regardless of their location or point of
attachment, especially while roaming outside the home subnet. An
efficient interpretation of packet losses problem that is encountered
from this roaming is to the centric of all aspects in this work, to be
over-highlighted. The main previous works, such as BER-systems,
Amigos, and ns-2 implementation that are considered to be in
conjunction with that problem under study are reviewed and
discussed. Their drawbacks and limitations, of stopping only at
monitoring, and not to provide an actual solution for eliminating or
even restricting these losses, are mentioned. Besides that, the
framework around which we built a Triple-R sequence as a costeffective
solution to eliminate the packet losses and bridge the gap
between subnets, an area that until now has been largely neglected, is
presented. The results show that, in addition to the high bit error rate
of wireless mobile networks, mainly the low efficiency of mobile-IP
registration procedure is a direct cause of these packet losses.
Furthermore, the output of packet losses interpretation resulted an
illustrated triangle of the registration process. This triangle should be
further researched and analyzed in our future work.
Abstract: Next generation wireless/mobile networks will be IP based cellular networks integrating the internet with cellular networks. In this paper, we propose a new architecture for a high speed transport system and a mobile management protocol for mobile internet users in a transport system. Existing mobility management protocols (MIPv6, HMIPv6) do not consider real world fast moving wireless hosts (e.g. passengers in a train). For this reason, we define a virtual organization (VO) and proposed the VO architecture for the transport system. We also classify mobility as VO mobility (intra VO) and macro mobility (inter VO). Handoffs in VO are locally managed and transparent to the CH while macro mobility is managed with Mobile IPv6. And, from the features of the transport system, such as fixed route and steady speed, we deduce the movement route and the handoff disruption time of each handoff. To reduce packet loss during handoff disruption time, we propose pre-registration scheme using pre-registration. Moreover, the proposed protocol can eliminate unnecessary binding updates resulting from sequence movement at high speed. The performance evaluations demonstrate our proposed protocol has a good performance at transport system environment. Our proposed protocol can be applied to the usage of wireless internet on the train, subway, and high speed train.
Abstract: In the current Grid environment, efficient workload
management presents a significant challenge, for which there are
exorbitant de facto standards encompassing resource discovery,
brokerage, and data transfer, among others. In addition, the real-time
resource status, essential for an optimal resource allocation strategy,
is often not readily accessible. To address these issues and provide a
cleaner abstraction of the Grid with the potential of generalizing into
arbitrary resource-sharing environment, this paper proposes a new
Condor-based pilot mechanism applied in the PanDA architecture,
PanDA-PF WMS, with the goal of providing a more generic yet
efficient resource allocating strategy. In this architecture, the PanDA
server primarily acts as a repository of user jobs, responding to pilot
requests from distributed, remote resources. Scheduling decisions are
subsequently made according to the real-time resource information
reported by pilots. Pilot Factory is a Condor-inspired solution for a
scalable pilot dissemination and effectively functions as a resource
provisioning mechanism through which the user-job server, PanDA,
reaches out to the candidate resources only on demand.
Abstract: Scarcity of water resources and huge costs of
establishing new hydraulic installations necessitate optimal
exploitation from existing reservoirs. Sustainable management and
efficient exploitation from existing finite water resources are
important factors in water resource management, particularly in the
periods of water insufficiency and in dry regions, and on account of
competitive allocations in the view of exploitation management. This
study aims to minimize reservoir water release from a determined
rate of demand. A numerical model for water optimal exploitation
has been developed using GAMS introduced by the World Bank and
applied to the case of Meijaran dam, northern Iran. The results
indicate that this model can optimize the function of reservoir
exploitation while required water for lower parts of the region will be
supplied. Further, allocating optimal water from reservoir, the
optimal rate of water allocated to any group of the users were
specified to increase benefits in curve dam exploitation.
Abstract: This paper presents an alternative strategy of queuing
handover called Pseudo Last Useful Instant PLUI scheme for Low
Earth Orbit Mobile Satellite Systems LEO MSSs. The PLUI scheme
uses the same approach as the Last Useful Instant LUI scheme
previously proposed in literature, with less complex implementation.
Simulation tests were carried out using Dynamic Channel Allocation
DCA in order to evaluate the performance of this scheme and also an
analytical approach has been presented to allow the performance
evaluation of Fixed Channel Allocation FCA, with different
handover queuing disciplines. The results show that performances
achieved by the proposed strategy are close to those achieved using
the LUI scheme.
Abstract: The mobile systems are powered by batteries.
Reducing the system power consumption is a key to increase its
autonomy. It is known that mostly the systems are dealing with time
varying signals. Thus, we aim to achieve power efficiency by smartly
adapting the system processing activity in accordance with the input
signal local characteristics. It is done by completely rethinking the
processing chain, by adopting signal driven sampling and processing.
In this context, a signal driven filtering technique, based on the level
crossing sampling is devised. It adapts the sampling frequency and
the filter order by analysing the input signal local variations. Thus, it
correlates the processing activity with the signal variations. It leads
towards a drastic computational gain of the proposed technique
compared to the classical one.
Abstract: Power system stabilizers (PSS) are now routinely used in the industry to damp out power system oscillations. In this paper, particle swarm optimization (PSO) technique is applied to design a robust power system stabilizer (PSS). The design problem of the proposed controller is formulated as an optimization problem and PSO is employed to search for optimal controller parameters. By minimizing the time-domain based objective function, in which the deviation in the oscillatory rotor speed of the generator is involved; stability performance of the system is improved. The non-linear simulation results are presented under wide range of operating conditions; disturbances at different locations as well as for various fault clearing sequences to show the effectiveness and robustness of the proposed controller and their ability to provide efficient damping of low frequency oscillations. Further, all the simulations results are compared with a conventionally designed power system stabilizer to show the superiority of the proposed design approach.
Abstract: The Institute of Product Development is dealing
with the development, design and dimensioning of micro components
and systems as a member of the Collaborative Research
Centre 499 “Design, Production and Quality Assurance of
Molded micro components made of Metallic and Ceramic Materials".
Because of technological restrictions in the miniaturization
of conventional manufacturing techniques, shape and
material deviations cannot be scaled down in the same proportion
as the micro parts, rendering components with relatively
wide tolerance fields. Systems that include such components
should be designed with this particularity in mind, often requiring
large clearance. On the end, the output of such systems
results variable and prone to dynamical instability. To save
production time and resources, every study of these effects
should happen early in the product development process and
base on computer simulation to avoid costly prototypes. A
suitable method is proposed here and exemplary applied to a
micro technology demonstrator developed by the CRC499. It
consists of a one stage planetary gear train in a sun-planet-ring
configuration, with input through the sun gear and output
through the carrier. The simulation procedure relies on ordinary
Multi Body Simulation methods and subsequently adds
other techniques to further investigate details of the system-s
behavior and to predict its response. The selection of the relevant
parameters and output functions followed the engineering
standards for regular sized gear trains. The first step is to
quantify the variability and to reveal the most critical points of
the system, performed through a whole-mechanism Sensitivity
Analysis. Due to the lack of previous knowledge about the system-s
behavior, different DOE methods involving small and
large amount of experiments were selected to perform the SA.
In this particular case the parameter space can be divided into
two well defined groups, one of them containing the gear-s profile
information and the other the components- spatial location.
This has been exploited to explore the different DOE techniques
more promptly. A reduced set of parameters is derived for
further investigation and to feed the final optimization process,
whether as optimization parameters or as external perturbation
collective. The 10 most relevant perturbation factors and 4 to 6
prospective variable parameters are considered in a new, simplified
model. All of the parameters are affected by the mentioned
production variability. The objective functions of interest
are based on scalar output-s variability measures, so the
problem becomes an optimization under robustness and reliability constrains. The study shows an initial step on the development
path of a method to design and optimize complex micro
mechanisms composed of wide tolerated elements accounting
for the robustness and reliability of the systems- output.
Abstract: Utilization of various sensors has made it possible to
extend capabilities of industrial robots. Among these are vision
sensors that are used for providing visual information to assist robot
controllers. This paper presents a method of integrating a vision
system and a simulation program with an industrial robot. The vision
system is employed to detect a target object and compute its location
in the robot environment. Then, the target object-s information is sent
to the robot controller via parallel communication port. The robot
controller uses the extracted object information and the simulation
program to control the robot arm for approaching, grasping and
relocating the object. This paper presents technical details of system
components and describes the methodology used for this integration.
It also provides a case study to prove the validity of the methodology
developed.
Abstract: The advancement in wireless technology with the wide
use of mobile devices have drawn the attention of the research and
technological communities towards wireless environments, such as
Wireless Local Area Networks (WLANs), Wireless Wide Area
Networks (WWANs), and mobile systems and ad-hoc networks.
Unfortunately, wired and wireless networks are expressively different
in terms of link reliability, bandwidth, and time of propagation delay
and by adapting new solutions for these enhanced
telecommunications, superior quality, efficiency, and opportunities
will be provided where wireless communications were otherwise
unfeasible. Some researchers define 4G as a significant improvement
of 3G, where current cellular network’s issues will be solved and data
transfer will play a more significant role. For others, 4G unifies
cellular and wireless local area networks, and introduces new routing
techniques, efficient solutions for sharing dedicated frequency bands,
and an increased mobility and bandwidth capacity. This paper
discusses the possible solutions and enhancements probabilities that
proposed to improve the performance of Transmission Control
Protocol (TCP) over different wireless networks and also the paper
investigated each approach in term of advantages and disadvantages.
Abstract: This paper features the proposed modeling and design
of a Robust Decentralized Periodic Output Feedback (RDPOF)
control technique for the active vibration control of smart flexible
multimodel Euler-Bernoulli cantilever beams for a multivariable
(MIMO) case by retaining the first 6 vibratory modes. The beam
structure is modeled in state space form using the concept of
piezoelectric theory, the Euler-Bernoulli beam theory and the Finite
Element Method (FEM) technique by dividing the beam into 4 finite
elements and placing the piezoelectric sensor / actuator at two finite
element locations (positions 2 and 4) as collocated pairs, i.e., as
surface mounted sensor / actuator, thus giving rise to a multivariable
model of the smart structure plant with two inputs and two outputs.
Five such multivariable models are obtained by varying the
dimensions (aspect ratios) of the aluminum beam, thus giving rise to
a multimodel of the smart structure system. Using model order
reduction technique, the reduced order model of the higher order
system is obtained based on dominant eigen value retention and the
method of Davison. RDPOF controllers are designed for the above 5
multivariable-multimodel plant. The closed loop responses with the
RDPOF feedback gain and the magnitudes of the control input are
observed and the performance of the proposed multimodel smart
structure system with the controller is evaluated for vibration control.
Abstract: In this paper we proposed a novel method to acquire
the ROI (Region of interest) of unsupervised and touch-less palmprint
captured from a web camera in real-time. We use Viola-Jones
approach and skin model to get the target area in real time. Then an
innovative course-to-fine approach to detect the key points on the hand
is described. A new algorithm is used to find the candidate key points
coarsely and quickly. In finely stage, we verify the hand key points
with the shape context descriptor. To make the user much comfortable,
it can process the hand image with different poses, even the hand is
closed. Experiments show promising result by using the proposed
method in various conditions.
Abstract: Due to some reasons, observed images are degraded which are mainly caused by noise. Recently image denoising using the wavelet transform has been attracting much attention. Waveletbased approach provides a particularly useful method for image denoising when the preservation of edges in the scene is of importance because the local adaptivity is based explicitly on the values of the wavelet detail coefficients. In this paper, we propose several methods of noise removal from degraded images with Gaussian noise by using adaptive wavelet threshold (Bayes Shrink, Modified Bayes Shrink and Normal Shrink). The proposed thresholds are simple and adaptive to each subband because the parameters required for estimating the threshold depend on subband data. Experimental results show that the proposed thresholds remove noise significantly and preserve the edges in the scene.
Abstract: The RK1GL2X3 method is a numerical method for solving initial value problems in ordinary differential equations, and is based on the RK1GL2 method which, in turn, is a particular case of the general RKrGLm method. The RK1GL2X3 method is a fourth-order method, even though its underlying Runge-Kutta method RK1 is the first-order Euler method, and hence, RK1GL2X3 is considerably more efficient than RK1. This enhancement is achieved through an implementation involving triple-nested two-point Gauss- Legendre quadrature.
Abstract: Non-uniform current distribution in polymer
electrolyte membrane fuel cells results in local over-heating,
accelerated ageing, and lower power output than expected. This
issue is very critical when fuel cell experiences water flooding. In
this work, the performance of a PEM fuel cell is investigated under
cathode flooding conditions. Two-dimensional partially flooded
GDL models based on the conservation laws and electrochemical
relations are proposed to study local current density distributions
along flow fields over a wide range of cell operating conditions.
The model results show a direct association between cathode inlet
humidity increases and that of average current density but the
system becomes more sensitive to flooding. The anode inlet
relative humidity shows a similar effect. Operating the cell at
higher temperatures would lead to higher average current densities
and the chance of system being flooded is reduced. In addition,
higher cathode stoichiometries prevent system flooding but the
average current density remains almost constant. The higher anode
stoichiometry leads to higher average current density and higher
sensitivity to cathode flooding.
Abstract: Renewable energy resources are inexhaustible, clean as compared with conventional resources. Also, it is used to supply regions with no grid, no telephone lines, and often with difficult accessibility by common transport. Satellite earth stations which located in remote areas are the most important application of renewable energy. Neural control is a branch of the general field of intelligent control, which is based on the concept of artificial intelligence. This paper presents the mathematical modeling of satellite earth station power system which is required for simulating the system.Aswan is selected to be the site under consideration because it is a rich region with solar energy. The complete power system is simulated using MATLAB–SIMULINK.An artificial neural network (ANN) based model has been developed for the optimum operation of earth station power system. An ANN is trained using a back propagation with Levenberg–Marquardt algorithm. The best validation performance is obtained for minimum mean square error. The regression between the network output and the corresponding target is equal to 96% which means a high accuracy. Neural network controller architecture gives satisfactory results with small number of neurons, hence better in terms of memory and time are required for NNC implementation. The results indicate that the proposed control unit using ANN can be successfully used for controlling the satellite earth station power system.