Abstract: The Carrier Frequency Offset (CFO) due to timevarying
fading channel is the main cause of the loss of orthogonality
among OFDM subcarriers which is linked to inter-carrier interference
(ICI). Hence, it is necessary to precisely estimate and compensate the
CFO. Especially for mobile broadband communications, CFO and
channel gain also have to be estimated and tracked to maintain the
system performance. Thus, synchronization pilots are embedded in
every OFDM symbol to track the variations. In this paper, we present
the pilot scheme for both channel and CFO estimation where channel
estimation process can be carried out with only one OFDM symbol.
Additional, the proposed pilot scheme also provides better
performance in CFO estimation comparing with the conventional
orthogonal pilot scheme due to the increasing of signal-tointerference
ratio.
Abstract: In this paper, we evaluate the performance of some wavelet based coding algorithms such as 3D QT-L, 3D SPIHT and JPEG2K. In the first step we achieve an objective comparison between three coders, namely 3D SPIHT, 3D QT-L and JPEG2K. For this purpose, eight MRI head scan test sets of 256 x 256x124 voxels have been used. Results show superior performance of 3D SPIHT algorithm, whereas 3D QT-L outperforms JPEG2K. The second step consists of evaluating the robustness of 3D SPIHT and JPEG2K coding algorithm over wireless transmission. Compressed dataset images are then transmitted over AWGN wireless channel or over Rayleigh wireless channel. Results show the superiority of JPEG2K over these two models. In fact, it has been deduced that JPEG2K is more robust regarding coding errors. Thus we may conclude the necessity of using corrector codes in order to protect the transmitted medical information.
Abstract: Synchronization is a difficult problem in CDMA
satellite communications. Due to the influence of additive noise and
fading in the mobile channel, it is not easy to keep up with the
attenuation and offset. This paper considers a recently proposed
approach to solve the problem of synchronization chaotic Chen
system in CDMA satellite communication in the presence of constant
attenuation and offset. An analytic algorithm that provides closed
form channel and carrier offset estimates is presented. The principle
of this approach is based on adding a compensation block before the
receiver to compensate the distortion of the imperfect channel by
using genetic algorithm.
The resultants presented, show that the receiver is able to recover
rapidly the synchronization with the transmitter.
Abstract: The people are differed by their capabilities, skills and mental agilities. The evolution of human from childhood when they are completely dependent up to adultness the time they gradually set the dependency free is too complicated, by considering they have all started from almost one point but some become cleverer and some less. The main control command of a cybernetic hand should be posted by remaining healthy organs of disabled Person. These commands can be from several channels, which their recording and detecting are different and need complicated study. In this research, we suppose that, this stage has been done or in the other words, the command has been already sent and detected. So the main goal is to control a long hand, upper elbow hand missing, by an interest angle define by disabled. It means that, the system input is the position desired by disables and the output is the elbow-joint angle variation. Therefore the goal is a suitable control design based on neural network theory in order to meet the given mapping.
Abstract: In this paper, we consider the design of pulse shaping
filter using orthogonal Hermite-Rodriguez basis functions. The pulse
shaping filter design problem has been formulated and solved as a
quadratic programming problem with linear inequality constraints.
Compared with the existing approaches reported in the literature, the
use of Hermite-Rodriguez functions offers an effective alternative to
solve the constrained filter synthesis problem. This is demonstrated
through a numerical example which is concerned with the design of
an equalization filter for a digital transmission channel.
Abstract: Modern applications realized onto FPGAs exhibit high connectivity demands. Throughout this paper we study the routing constraints of Virtex devices and we propose a systematic methodology for designing a novel general-purpose interconnection network targeting to reconfigurable architectures. This network consists of multiple segment wires and SB patterns, appropriately selected and assigned across the device. The goal of our proposed methodology is to maximize the hardware utilization of fabricated routing resources. The derived interconnection scheme is integrated on a Virtex style FPGA. This device is characterized both for its high-performance, as well as for its low-energy requirements. Due to this, the design criterion that guides our architecture selections was the minimal Energy×Delay Product (EDP). The methodology is fully-supported by three new software tools, which belong to MEANDER Design Framework. Using a typical set of MCNC benchmarks, extensive comparison study in terms of several critical parameters proves the effectiveness of the derived interconnection network. More specifically, we achieve average Energy×Delay Product reduction by 63%, performance increase by 26%, reduction in leakage power by 21%, reduction in total energy consumption by 11%, at the expense of increase of channel width by 20%.
Abstract: The new status generated by technological advancements and changes in the global economy raises important issues on how communities and organisations need to innovate upon their traditional processes in order to adapt to the challenges of the Knowledge Society. The DialogoS+ European project aims to study the role of and promote social dialogue in the banking sector, strengthen the link between old and new members and make social dialogue at the European level a force for innovation and change, also given the context of the international crisis emerging in 2008- 2009. Under the scope of DialogoS+, this paper describes how the community of Europe-s banking sector trade unions attempted to adapt to the challenges of the Knowledge Society by exploiting the benefits of new channels of communication, learning, knowledge generation and diffusion focusing on the concept of roadmapping. Important dimensions of social dialogue such as collective bargaining and working conditions are addressed.
Abstract: In this paper we propose a new criterion for solving
the problem of channel shortening in multi-carrier systems. In a
discrete multitone receiver, a time-domain equalizer (TEQ) reduces
intersymbol interference (ISI) by shortening the effective duration of
the channel impulse response. Minimum mean square error (MMSE)
method for TEQ does not give satisfactory results. In [1] a new
criterion for partially equalizing severe ISI channels to reduce the
cyclic prefix overhead of the discrete multitone transceiver (DMT),
assuming a fixed transmission bandwidth, is introduced. Due to
specific constrained (unit morm constraint on the target impulse
response (TIR)) in their method, the freedom to choose optimum
vector (TIR) is reduced. Better results can be obtained by avoiding
the unit norm constraint on the target impulse response (TIR). In
this paper we change the cost function proposed in [1] to the cost
function of determining the maximum of a determinant subject to
linear matrix inequality (LMI) and quadratic constraint and solve the
resulting optimization problem. Usefulness of the proposed method
is shown with the help of simulations.
Abstract: A color image edge detection algorithm is proposed in
this paper using Pseudo-complement and matrix rotation operations.
First, pseudo-complement method is applied on the image for each
channel. Then, matrix operations are applied on the output image of
the first stage. Dominant pixels are obtained by image differencing
between the pseudo-complement image and the matrix operated
image. Median filtering is carried out to smoothen the image thereby
removing the isolated pixels. Finally, the dominant or core pixels
occurring in at least two channels are selected. On plotting the
selected edge pixels, the final edge map of the given color image is
obtained. The algorithm is also tested in HSV and YCbCr color
spaces. Experimental results on both synthetic and real world images
show that the accuracy of the proposed method is comparable to
other color edge detectors. All the proposed procedures can be
applied to any image domain and runs in polynomial time.
Abstract: The IEEE 802.11e which is an enhanced version of the 802.11 WLAN standards incorporates the Quality of Service (QoS) which makes it a better choice for multimedia and real time applications. In this paper we study various aspects concerned with 802.11e standard. Further, the analysis results for this standard are compared with the legacy 802.11 standard. Simulation results show that IEEE 802.11e out performs legacy IEEE 802.11 in terms of quality of service due to its flow differentiated channel allocation and better queue management architecture. We also propose a method to improve the unfair allocation of bandwidth for downlink and uplink channels by varying the medium access priority level.
Abstract: Advent enhancements in the field of computing have
increased massive use of web based electronic documents. Current
Copyright protection laws are inadequate to prove the ownership for
electronic documents and do not provide strong features against
copying and manipulating information from the web. This has
opened many channels for securing information and significant
evolutions have been made in the area of information security.
Digital Watermarking has developed into a very dynamic area of
research and has addressed challenging issues for digital content.
Watermarking can be visible (logos or signatures) and invisible
(encoding and decoding). Many visible watermarking techniques
have been studied for text documents but there are very few for web
based text. XML files are used to trade information on the internet
and contain important information. In this paper, two invisible
watermarking techniques using Synonyms and Acronyms are
proposed for XML files to prove the intellectual ownership and to
achieve the security. Analysis is made for different attacks and
amount of capacity to be embedded in the XML file is also noticed.
A comparative analysis for capacity is also made for both methods.
The system has been implemented using C# language and all tests are
made practically to get the results.
Abstract: One major source of performance decline in speaker
recognition system is channel mismatch between training and testing.
This paper focuses on improving channel robustness of speaker
recognition system in two aspects of channel compensation technique
and channel robust features. The system is text-independent speaker
identification system based on two-stage recognition. In the aspect of
channel compensation technique, this paper applies MAP (Maximum
A Posterior Probability) channel compensation technique, which was
used in speech recognition, to speaker recognition system. In the
aspect of channel robust features, this paper introduces
pitch-dependent features and pitch-dependent speaker model for the
second stage recognition. Based on the first stage recognition to
testing speech using GMM (Gaussian Mixture Model), the system
uses GMM scores to decide if it needs to be recognized again. If it
needs to, the system selects a few speakers from all of the speakers
who participate in the first stage recognition for the second stage
recognition. For each selected speaker, the system obtains 3
pitch-dependent results from his pitch-dependent speaker model, and
then uses ANN (Artificial Neural Network) to unite the 3
pitch-dependent results and 1 GMM score for getting a fused result.
The system makes the second stage recognition based on these fused
results. The experiments show that the correct rate of two-stage
recognition system based on MAP channel compensation technique
and pitch-dependent features is 41.7% better than the baseline system
for closed-set test.
Abstract: This paper tries to shed light on the existence of a bank lending channel (BLC) in South Eastern European countries (SEE). Based on a VAR framework we test the responsiveness of credit supply to monetary policy shocks. By compiling a new data set and using the reserve requirement ratio, among others, as the policy instrument we measure the effectiveness of the BLC and the buffering effect of the banks in the SEE countries. The results indicate that loan supply is significantly affected by shifts in monetary policy, when demand factors are controlled. Furthermore, by analyzing the effect of the Greek banks in the region we conclude that Greek banks do buffer the negative effects of monetary policy transmission. By having a significant market share of the SEE-s banking markets we argue that Greek banks influence positively the economic growth of SEE countries.
Abstract: The paper deals with the pulsating flow of an incompressible couple stress fluid between permeable beds. The couple stress fluid is injected into the channel from the lower permeable bed with a certain velocity and is sucked into the upper permeable bed with the same velocity. The flow between the permeable beds is assumed to be governed by couple stress fluid flow equations of V. K. Stokes and that in the permeable regions by Darcy-s law. The equations are solved analytically and the expressions for velocity and volume flux are obtained. The effects of the material parameters are studied numerically and the results are presented through graphs.
Abstract: The theoretical investigation is carried out to describe
the effect of increase of pressure waves amplitude in clean and bubbly liquid. The goal of the work is to capture the regime of multiple magnification of acoustic and shock waves in the liquid,
which enables to get appropriate conditions to enlarge collapses of
micro-bubbles. The influence of boundary conditions and frequency
of the governing acoustic field is studied for the case of the
cylindrical acoustic resonator. It has been observed the formation of
standing waves with large amplitude at resonant frequencies. The
interaction of the compression wave with gas and vapor bubbles is
investigated for the convergent channel. It is shown theoretically that
the chemical reactions, which occur inside gas bubbles, provide additional impulse to the wave, that affect strongly on the collapses
of the vapor bubbles
Abstract: This paper discusses the effectiveness of the EEG signal
for human identification using four or less of channels of two different
types of EEG recordings. Studies have shown that the EEG signal
has biometric potential because signal varies from person to person
and impossible to replicate and steal. Data were collected from 10
male subjects while resting with eyes open and eyes closed in 5
separate sessions conducted over a course of two weeks. Features
were extracted using the wavelet packet decomposition and analyzed
to obtain the feature vectors. Subsequently, the neural networks
algorithm was used to classify the feature vectors. Results show that,
whether or not the subjects- eyes were open are insignificant for a 4–
channel biometrics system with a classification rate of 81%. However,
for a 2–channel system, the P4 channel should not be included if data
is acquired with the subjects- eyes open. It was observed that for 2–
channel system using only the C3 and C4 channels, a classification
rate of 71% was achieved.
Abstract: Study fluid flow and heat transfer characteristics of
microchannel in a primary Cross-corrugated(CC) surface recuperators
with corrugations and without corrugations, using CFD method. The
pitch-over-height ratios P/H of Cross-corrugated (CC) surface is from
1.5 to 4.0, included angles β=75º. The study was performed using CFD
software FLUENT to create unit model and simulate fluid
temperature, velocity, heat transfer coefficient and other parameters.
The results from these simulations were compared to experimental
data. It is concluded that, when the Reynolds number is constant, if
increase P/H, j/f will decrease, also the decreasing trend will become
weak. Under the condition of P/H=2.2, if increase the inlet velocity j/f
will decrease; in addition, the heat transfer performance in surface
with corrugation will increase 10% compared to that without
corrugation. The study results can provide the basis to optimize the
design, select the type of heat transfer surface, the scale structure, and
heat-transfer surface arrangement for recuperators.
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: The purpose of this study was to investigate the
response of the newly released Gafchromic HD-V2 film for alpha
particle of 5.5 MeV. Gafchromic HD-V2 was exposed to alpha
particles of energy 5 MeV from 241Am for different durations. Then
the films were scanned with a flatbed scanner. The dose response
curve up to 2200 Gy has been achieved. The film’s reproducibility
and sensitivity were evaluated. The results obtained show that the net
optical density increases almost exponentially with the increase in the
exposure time, and it becomes saturated after prolonged exposure
times. The red channel shows the highest sensitivity, with a value of
4 x 10-3 Gy-1 at netOD of 0.4. The inter-film reproducibility was
measured and the relative uncertainty found was 1.7 %, 2.1 % and 2.3
% for grey, red and green channels, respectively.
Abstract: One of the disadvantages of using OFDM is the larger
peak to averaged power ratio (PAPR) in its time domain signal. The
larger PAPR signal would course the fatal degradation of bit error
rate performance (BER) due to the inter-modulation noise in the nonlinear
channel. This paper proposes an improved DSI (Dummy
Sequence Insertion) method, which can achieve the better PAPR and
BER performances. The feature of proposed method is to optimize
the phase of each dummy sub-carrier so as to reduce the PAPR
performance by changing all predetermined phase coefficients in the
time domain signal, which is calculated for data sub-carriers and
dummy sub-carriers separately. To achieve the better PAPR
performance, this paper also proposes to employ the time-frequency
domain swapping algorithm for fine adjustment of phase coefficient
of the dummy subcarriers, which can achieve the less complexity of
processing and achieves the better PAPR and BER performances
than those for the conventional DSI method. This paper presents
various computer simulation results to verify the effectiveness of
proposed method as comparing with the conventional methods in the
non-linear channel.