Abstract: This paper describes the development of a fully
automated measurement software for antenna radiation pattern
measurements in a Compact Antenna Test Range (CATR). The
CATR has a frequency range from 2-40 GHz and the measurement
hardware includes a Network Analyzer for transmitting and
Receiving the microwave signal and a Positioner controller to control
the motion of the Styrofoam column. The measurement process
includes Calibration of CATR with a Standard Gain Horn (SGH)
antenna followed by Gain versus angle measurement of the Antenna
under test (AUT). The software is designed to control a variety of
microwave transmitter / receiver and two axis Positioner controllers
through the standard General Purpose interface bus (GPIB) interface.
Addition of new Network Analyzers is supported through a slight
modification of hardware control module. Time-domain gating is
implemented to remove the unwanted signals and get the isolated
response of AUT. The gated response of the AUT is compared with
the calibration data in the frequency domain to obtain the desired
results. The data acquisition and processing is implemented in
Agilent VEE and Matlab. A variety of experimental measurements
with SGH antennas were performed to validate the accuracy of
software. A comparison of results with existing commercial
softwares is presented and the measured results are found to be
within .2 dBm.
Abstract: Wireless LAN technologies have picked up
momentum in the recent years due to their ease of deployment, cost
and availability. The era of wireless LAN has also given rise to
unique applications like VOIP, IPTV and unified messaging.
However, these real-time applications are very sensitive to network
and handoff latencies. To successfully support these applications,
seamless roaming during the movement of mobile station has become
crucial. Nowadays, centralized architecture models support roaming
in WLANs. They have the ability to manage, control and
troubleshoot large scale WLAN deployments. This model is managed
by Control and Provision of Wireless Access Point protocol
(CAPWAP). This paper covers the CAPWAP architectural solution
along with its proposals that have emerged. Based on the literature
survey conducted in this paper, we found that the proposed
algorithms to reduce roaming latency in CAPWAP architecture do
not support seamless roaming. Additionally, they are not sufficient
during the initial period of the network. This paper also suggests
important design consideration for mobility support in future
centralized IEEE 802.11 networks.
Abstract: After Apple's first introduction its smart phone, iPhone
in the end of 2009 in Korea, the number of Korean smarphone users
had been rapidly increasing so that the half of Korean population
became smart phone users as of February, 2012. Currently, smart
phones are positioned as a major digital media with powerful
influences in Korea. And, now, Koreans are leaning new information,
enjoying games and communicating other people every time and
everywhere. As smart phone devices' performances increased, the
number of usable services became more while adequate GUI
developments are required to implement various functions with smart
phones. The strategy to provide similar experiences on smart phones
through familiar features based on employment of existing media's
functions mostly contributed to smart phones' popularization in
connection with smart phone devices' iconic GUIs.
The spread of Smart phone increased mobile web accesses.
Therefore, the attempts to implement PC's web in the smart phone's
web are continuously made. The mobile web GUI provides familiar
experiences to users through designs adequately utilizing the smart
phone's GUIs. As the number of users familiarized to smart phones
and mobile web GUIs, opposite to reversed remediation from many
parts of PCs, PCs are starting to adapt smart phone GUIs.
This study defines this phenomenon as the reversed remediation,
and reviews the reversed remediation cases of Smart phone GUI'
characteristics of PCs. For this purpose, the established study issues
are as under:
· what is the reversed remediation?
· what are the smart phone GUI's characteristics?
· what kind of interrelationship exist s between the smart phone and
PC's web site?
It is meaningful in the forecast of the future GUI's change by
understanding of characteristics in the paradigm changes of PC and
smart phone's GUI designs. This also will be helpful to establish
strategies for digital devices' development and design.
Abstract: This paper explores the implementation of adaptive
coding and modulation schemes for Multiple-Input Multiple-Output
Orthogonal Frequency Division Multiplexing (MIMO-OFDM) feedback
systems. Adaptive coding and modulation enables robust and
spectrally-efficient transmission over time-varying channels. The basic
premise is to estimate the channel at the receiver and feed this estimate
back to the transmitter, so that the transmission scheme can be
adapted relative to the channel characteristics. Two types of codebook
based channel feedback techniques are used in this work. The longterm
and short-term CSI at the transmitter is used for efficient channel
utilization. OFDM is a powerful technique employed in communication
systems suffering from frequency selectivity. Combined with
multiple antennas at the transmitter and receiver, OFDM proves to be
robust against delay spread. Moreover, it leads to significant data rates
with improved bit error performance over links having only a single
antenna at both the transmitter and receiver. The coded modulation
increases the effective transmit power relative to uncoded variablerate
variable-power MQAM performance for MIMO-OFDM feedback
system. Hence proposed arrangement becomes an attractive approach
to achieve enhanced spectral efficiency and improved error rate
performance for next generation high speed wireless communication
systems.
Abstract: Speeded-Up Robust Feature (SURF) is commonly used for feature matching in stereovision because of their robustness towards scale changes and rotational changes. However, SURF feature cannot cope with large viewpoint changes or skew distortion. This paper introduces a method which can help to improve the wide baseline-s matching performance in term of accuracy by rectifying the image using two vanishing points. Simplified orientation correction was used to remove the false matching..
Abstract: GSM has undoubtedly become the most widespread
cellular technology and has established itself as one of the most
promising technology in wireless communication. The next
generation of mobile telephones had also become more powerful and
innovative in a way that new services related to the user-s location
will arise. Other than the 911 requirements for emergency location
initiated by the Federal Communication Commission (FCC) of the
United States, GSM positioning can be highly integrated in cellular
communication technology for commercial use. However, GSM
positioning is facing many challenges. Issues like accuracy,
availability, reliability and suitable cost render the development and
implementation of GSM positioning a challenging task. In this paper,
we investigate the optimal mobile position tracking means. We
employ an innovative scheme by integrating the Kalman filter in the
localization process especially that it has great tracking
characteristics. When tracking in two dimensions, Kalman filter is
very powerful due to its reliable performance as it supports
estimation of past, present, and future states, even when performing
in unknown environments. We show that enhanced position tracking
results is achieved when implementing the Kalman filter for GSM
tracking.
Abstract: Selected Mapping (SLM) is a PAPR reduction technique, which converts the OFDM signal into several independent signals by multiplication with the phase sequence set and transmits one of the signals with lowest PAPR. But it requires the index of the selected signal i.e. side information (SI) to be transmitted with each OFDM symbol. The PAPR reduction capability of the SLM scheme depends on the selection of phase sequence set. In this paper, we have proposed a new phase sequence set generation scheme based on M-ary chaotic sequence and a mapping scheme to map quaternary data to concentric circle constellation (CCC) is used. It is shown that this method does not require SI and provides better SER performance with good PAPR reduction capability as compared to existing SLMOFDM methods.
Abstract: In this paper, an alternating implicit block method for
solving two dimensional scalar wave equation is presented. The
new method consist of two stages for each time step implemented
in alternating directions which are very simple in computation. To
increase the speed of computation, a group of adjacent points is
computed simultaneously. It is shown that the presented method
increase the maximum time step size and more accurate than the
conventional finite difference time domain (FDTD) method and other
existing method of natural ordering.
Abstract: This paper presents a particle swarm optimization
(PSO) based approach for multiple object tracking based on histogram
matching. To start with, gray-level histograms are calculated to
establish a feature model for each of the target object. The difference
between the gray-level histogram corresponding to each particle in the
search space and the target object is used as the fitness value. Multiple
swarms are created depending on the number of the target objects
under tracking. Because of the efficiency and simplicity of the PSO
algorithm for global optimization, target objects can be tracked as
iterations continue. Experimental results confirm that the proposed
PSO algorithm can rapidly converge, allowing real-time tracking of
each target object. When the objects being tracked move outside the
tracking range, global search capability of the PSO resumes to re-trace
the target objects.
Abstract: The number of people using SNS with their mobile devices is soaring. This research focuses on the Twitter service that has the most third-party applications and delved into the fact that there were not sufficient studies on the UX design aspects of Twitter applications. Among social network services which have emerged as a major social topic lately, this research try to analyze the UX design of the Twitter application which is also called micro-blogging service. Therefore this research sets its goal to draw components of the UX design aspect of the Tweeter application on which there are not enough analysis yet. Moreover, this research suggests improvement of mobile application which will assure better users- experience. In order to analyze the UX design aspect of the mobile twitter application, with relevant document and user research, evaluating factors of the UX Design which would affect users- experience were organized. The subjects for cases were selected among six paid and free social networking applications that had been consistently ranked from 1st to 100th in the Korean application store during May, 2012 after closely monitoring the rank. From May 15th to May 11th in 2012, in accordance with the evaluating standard, surveys were conducted in a form of interviews with 20 subjects who have used the Twitter application to find out problems and solutions for the UX design of the mobile Twitter application.
Abstract: A method is presented for obtaining the error probability for block codes. The method is based on the eigenvalueeigenvector properties of the code correlation matrix. It is found that under a unary transformation and for an additive white Gaussian noise environment, the performance evaluation of a block code becomes a one-dimensional problem in which only one eigenvalue and its corresponding eigenvector are needed in the computation. The obtained error rate results show remarkable agreement between simulations and analysis.
Abstract: The electromagnetic spectrum is a natural resource
and hence well-organized usage of the limited natural resources is the
necessities for better communication. The present static frequency
allocation schemes cannot accommodate demands of the rapidly
increasing number of higher data rate services. Therefore, dynamic
usage of the spectrum must be distinguished from the static usage to
increase the availability of frequency spectrum. Cognitive radio is not
a single piece of apparatus but it is a technology that can incorporate
components spread across a network. It offers great promise for
improving system efficiency, spectrum utilization, more effective
applications, reduction in interference and reduced complexity of
usage for users. Cognitive radio is aware of its environmental,
internal state, and location, and autonomously adjusts its operations
to achieve designed objectives. It first senses its spectral environment
over a wide frequency band, and then adapts the parameters to
maximize spectrum efficiency with high performance. This paper
only focuses on the analysis of Bit-Error-Rate in cognitive radio by
using Particle Swarm Optimization Algorithm. It is theoretically as
well as practically analyzed and interpreted in the sense of
advantages and drawbacks and how BER affects the efficiency and
performance of the communication system.
Abstract: In this paper we present a linear autozeroing ultra lowvoltage amplifier. The autozeroing performed by all ULV circuits is important to reduce the impact of noise and especially avoid power supply noise in mixed signal low-voltage CMOS circuits. The simulated data presented is relevant for a 90nm TSMC CMOS process.
Abstract: A numbers of important developments have led to an
increasing attractiveness for very high speed electrical machines
(either motor or generator). Specifically the increasing switching
speed of power electronics, high energy magnets, high strength
retaining materials, better high speed bearings and improvements in
design analysis are the primary drivers in a move to higher speed. The
design challenges come in the mechanical design both in terms of
strength and resonant modes and in the electromagnetic design
particularly in respect of iron losses and ac losses in the various
conducting parts including the rotor. This paper describes detailed
design work which has been done on a 50,000 rpm, 50kW permanent
magnet( PM) synchronous machine. It describes work on
electromagnetic and rotor eddy current losses using a variety of
methods including both 2D finite element analysis
Abstract: In this paper we propose a robust environmental sound classification approach, based on spectrograms features driven from log-Gabor filters. This approach includes two methods. In the first methods, the spectrograms are passed through an appropriate log-Gabor filter banks and the outputs are averaged and underwent an optimal feature selection procedure based on a mutual information criteria. The second method uses the same steps but applied only to three patches extracted from each spectrogram.
To investigate the accuracy of the proposed methods, we conduct experiments using a large database containing 10 environmental sound classes. The classification results based on Multiclass Support Vector Machines show that the second method is the most efficient with an average classification accuracy of 89.62 %.
Abstract: This paper investigates the nature of the development
of two-dimensional laminar flow of an incompressible fluid at the
reversed stagnation-point. ". In this study, we revisit the problem
of reversed stagnation-point flow over a flat plate. Proudman and
Johnson (1962) first studied the flow and obtained an asymptotic
solution by neglecting the viscous terms. This is no true in neglecting
the viscous terms within the total flow field. In particular it is pointed
out that for a plate impulsively accelerated from rest to a constant
velocity V0 that a similarity solution to the self-similar ODE is
obtained which is noteworthy completely analytical.
Abstract: This research paper presents some methods to assess the performance of Wigner Ville Distribution for Time-Frequency representation of non-stationary signals, in comparison with the other representations like STFT, Spectrogram etc. The simultaneous timefrequency resolution of WVD is one of the important properties which makes it preferable for analysis and detection of linear FM and transient signals. There are two algorithms proposed here to assess the resolution and to compare the performance of signal detection. First method is based on the measurement of area under timefrequency plot; in case of a linear FM signal analysis. A second method is based on the instantaneous power calculation and is used in case of transient, non-stationary signals. The implementation is explained briefly for both methods with suitable diagrams. The accuracy of the measurements is validated to show the better performance of WVD representation in comparison with STFT and Spectrograms.
Abstract: In this paper variation of spot price and total profits of
the generating companies- through wholesale electricity trading are
discussed with and without Central Generating Stations (CGS) share
and seasonal variations are also considered. It demonstrates how
proper analysis of generators- efficiencies and capabilities, types of
generators owned, fuel costs, transmission losses and settling price
variation using the solutions of Optimal Power Flow (OPF), can
allow companies to maximize overall revenue. It illustrates how
solutions of OPF can be used to maximize companies- revenue under
different scenarios. And is also extended to computation of Available
Transfer Capability (ATC) is very important to the transmission
system security and market forecasting. From these results it is
observed that how crucial it is for companies to plan their daily
operations and is certainly useful in an online environment of
deregulated power system. In this paper above tasks are demonstrated
on 124 bus real-life Indian utility power system of Andhra Pradesh
State Grid and results have been presented and analyzed.
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: The proposed multiplexer-based novel 1-bit full
adder cell is schematized by using DSCH2 and its layout is generated
by using microwind VLSI CAD tool. The adder cell layout
interconnect analysis is performed by using BSIM4 layout analyzer.
The adder circuit is compared with other six existing adder circuits
for parametric analysis. The proposed adder cell gives better
performance than the other existing six adder circuits in terms of
power, propagation delay and PDP. The proposed adder circuit is
further analyzed for interconnect analysis, which gives better
performance than other adder circuits in terms of layout thickness,
width and height.