Abstract: Digital images are widely used in computer
applications. To store or transmit the uncompressed images
requires considerable storage capacity and transmission bandwidth.
Image compression is a means to perform transmission or storage of
visual data in the most economical way. This paper explains about
how images can be encoded to be transmitted in a multiplexing
time-frequency domain channel. Multiplexing involves packing
signals together whose representations are compact in the working
domain. In order to optimize transmission resources each 4 × 4
pixel block of the image is transformed by a suitable polynomial
approximation, into a minimal number of coefficients. Less than
4 × 4 coefficients in one block spares a significant amount of
transmitted information, but some information is lost. Different
approximations for image transformation have been evaluated as
polynomial representation (Vandermonde matrix), least squares +
gradient descent, 1-D Chebyshev polynomials, 2-D Chebyshev
polynomials or singular value decomposition (SVD). Results have
been compared in terms of nominal compression rate (NCR),
compression ratio (CR) and peak signal-to-noise ratio (PSNR)
in order to minimize the error function defined as the difference
between the original pixel gray levels and the approximated
polynomial output. Polynomial coefficients have been later encoded
and handled for generating chirps in a target rate of about two
chirps per 4 × 4 pixel block and then submitted to a transmission
multiplexing operation in the time-frequency domain.
Abstract: In wireless sensor network, sensor node transmits the
sensed data to the sink node in multi-hop communication
periodically. This high traffic induces congestion at the node which is
present one-hop distance to the sink node. The packet transmission
and reception rate of these nodes should be very high, when
compared to other sensor nodes in the network. Therefore, the energy
consumption of that node is very high and this effect is known as the
“funneling effect”. The tree based-data aggregation technique
(TBDA) is used to reduce the energy consumption of the node. The
throughput of the overall performance shows a considerable decrease
in the number of packet transmissions to the sink node. The proposed
scheme, TBDA, avoids the funneling effect and extends the lifetime
of the wireless sensor network. The average case time complexity for
inserting the node in the tree is O(n log n) and for the worst case time
complexity is O(n2).
Abstract: The occurrences of precipitation, also commonly
referred as rain, in the form of "convective" and "stratiform" have
been identified to exist worldwide. In this study, the radar return
echoes or known as reflectivity values acquired from radar scans
have been exploited in the process of classifying the type of rain
endured. The investigation use radar data from Malaysian
Meteorology Department (MMD). It is possible to discriminate the
types of rain experienced in tropical region by observing the vertical
characteristics of the rain structure. .Heavy rain in tropical region
profoundly affects radiowave signals, causing transmission
interference and signal fading. Required wireless system fade margin
depends on the type of rain. Information relating to the two
mentioned types of rain is critical for the system engineers and
researchers in their endeavour to improve the reliability of
communication links. This paper highlights the quantification of
percentage occurrences over one year period in 2009.
Abstract: Cadmium oxide (CdO) nanoparticles have been
prepared by chemical coprecipitation method. The synthesized
nanoparticles were characterized by X-ray diffraction analysis
(XRD), scanning electron microscopy (SEM), transmission electron
microscopy (TEM), UV analysis, and dielectric studies. The
crystalline nature and particle size of the CdO nanoparticles were
characterized by Powder X-ray diffraction analysis (XRD). The
morphology of prepared CdO nanoparticles was studied by scanning
electron microscopy. The particle size was studied using the
transmission electron microscopy (TEM).The optical properties were
obtained from UV-Vis absorption spectrum. The dielectric properties
of CdO nanoparticles were studied in the frequency range of 50 Hz–5
MHz at different temperatures. The frequency dependence of the
dielectric constant and dielectric loss is found to decrease with an
increase in the frequency at different temperatures. The ac
conductivity of CdO nanoparticle has been studied.
Abstract: When evaluating the capacity of a generation park to
cover the load in transmission systems, traditional Loss of Load
Expectation (LOLE) and Expected Energy not Served (EENS)
indices can be used. If those indices allow computing the annual
duration and severity of load non covering situations, they do not take
into account the fact that the load excess is generally shifted from one
penury state (hour or quarter of an hour) to the following one. In this
paper, a sequential Monte Carlo framework is introduced in order to
compute adjusted LOLE and EENS indices. Practically, those
adapted indices permit to consider the effect of load excess transfer
on the global adequacy of a generation park, providing thus a more
accurate evaluation of this quantity.
Abstract: Opportunistic Routing (OR) increases the
transmission reliability and network throughput. Traditional routing
protocols preselects one or more predetermined nodes before
transmission starts and uses a predetermined neighbor to forward a
packet in each hop. The opportunistic routing overcomes the
drawback of unreliable wireless transmission by broadcasting one
transmission can be overheard by manifold neighbors. The first
cooperation-optimal protocol for Multirate OR (COMO) used to
achieve social efficiency and prevent the selfish behavior of the
nodes. The novel link-correlation-aware OR improves the
performance by exploiting the miscellaneous low correlated forward
links. Context aware Adaptive OR (CAOR) uses active suppression
mechanism to reduce packet duplication. The Context-aware OR
(COR) can provide efficient routing in mobile networks. By using
Cooperative Opportunistic Routing in Mobile Ad hoc Networks
(CORMAN), the problem of opportunistic data transfer can be
tackled. While comparing to all the protocols, COMO is the best as it
achieves social efficiency and prevents the selfish behavior of the
nodes.
Abstract: This article proposes a hybrid algorithm for spectrum
allocation in cognitive radio networks based on the algorithms
Analytical Hierarchical Process (AHP) and Technique for Order of
Preference by Similarity to Ideal Solution (TOPSIS) to improve the
performance of the spectrum mobility of secondary users in cognitive
radio networks. To calculate the level of performance of the proposed algorithm a
comparative analysis between the proposed AHP-TOPSIS, Grey
Relational Analysis (GRA) and Multiplicative Exponent Weighting
(MEW) algorithm is performed. Four evaluation metrics are used.
These metrics are accumulative average of failed handoffs,
accumulative average of handoffs performed, accumulative average
of transmission bandwidth, and accumulative average of the
transmission delay. The results of the comparison show that AHP-TOPSIS Algorithm
provides 2.4 times better performance compared to a GRA Algorithm
and, 1.5 times better than the MEW Algorithm.
Abstract: This paper presents a case study of using STATCOM to enhance the performance of Al-Qatraneh 33-kV transmission line. The location of the STATCOM was identified by maintaining minimum voltage drops at the 110 load nodes. The transmission line and the 110 load nodes have been modeled by MATLAB/Simulink. The suggested STATCOM and its location will increase the transmission capability of this transmission line and overcome the overload expected in the year 2020. The annual percentage loading rise has been considered as 14.35%. A graphical representation of the line-to-line voltages and the voltage drops at different load nodes is illustrated.
Abstract: Wireless Sensor Network (WSN) routing is complex
due to its dynamic nature, computational overhead, limited battery
life, non-conventional addressing scheme, self-organization, and
sensor nodes limited transmission range. An energy efficient routing
protocol is a major concern in WSN. LEACH is a hierarchical WSN
routing protocol to increase network life. It performs self-organizing
and re-clustering functions for each round. This study proposes a
better sensor networks cluster head selection for efficient data
aggregation. The algorithm is based on Tabu search.
Abstract: NiFe2O4 (nickel ferrite), ZnFe2O4 (zinc ferrite) and
Ni0.5Zn0.5Fe2O4 (nickel-zinc ferrite) were prepared by
mechanochemical route in a planetary ball mill starting from mixture
of the appropriate quantities of the Ni(OH)2/Fe(OH)3,
Zn(OH)2/Fe(OH)3 and Ni(OH)2/Zn(OH)2/Fe(OH)3 hydroxide
powders. In order to monitor the progress of chemical reaction and
confirm phase formation, powder samples obtained after 25 h, 18 h
and 10 h of milling were characterized by X-ray diffraction (XRD),
transmission electron microscopy (TEM), IR, Raman and Mössbauer
spectroscopy. It is shown that the soft mechanochemical method, i.e.
mechanochemical activation of hydroxides, produces high quality
single phase ferrite samples in much more efficient way. From the IR
spectroscopy of single phase samples it is obvious that energy of
modes depends on the ratio of cations. It is obvious that all samples
have more than 5 Raman active modes predicted by group theory in
the normal spinel structure. Deconvolution of measured spectra
allows one to conclude that all complex bands in the spectra are made
of individual peaks with the intensities that vary from spectrum to
spectrum. The deconvolution of Raman spectra allows to separate
contributions of different cations to a particular type of vibration and
to estimate the degree of inversion.
Abstract: Increasingly complex modern power systems require
stability, especially for transient and small disturbances. Transient
stability plays a major role in stability during fault and large
disturbance. This paper compares a power system stabilizer (PSS)
and static Var compensator (SVC) to improve damping oscillation
and enhance transient stability. The effectiveness of a PSS connected
to the exciter and/or governor in damping electromechanical
oscillations of isolated synchronous generator was tested. The SVC
device is a member of the shunt FACTS (flexible alternating current
transmission system) family, utilized in power transmission systems.
The designed model was tested with a multi-machine system
consisting of four machines six bus, using MATLAB/SIMULINK
software. The results obtained indicate that SVC solutions are better
than PSS.
Abstract: CuO thin films were deposited by spray ultrasonic
pyrolysis with different precursor solution. Two staring solution slats
were used namely: copper acetate and copper chloride. The influence
of these solutions on CuO thin films proprieties of is instigated. The
X rays diffraction (XDR) analysis indicated that the films deposed
with copper acetate are amorphous however the films elaborated with
copper chloride have monoclinic structure. UV- Visible transmission
spectra showed a strong absorbance of the deposited CuO thin films
in the visible region. Electrical characterization has shown that CuO
thin films prepared with copper acetate have a higher electrical
conductivity.
Abstract: The health care must be a right for people around the
world, but in order to guarantee the access to all, it is necessary to
overcome geographical barriers. Telemedicine take advantage of
Information Communication Technologies to deploy health care
services around the world. To achieve those goals, it is necessary to
use existing last mile solution to create access for home users, which
is why is necessary to establish the channel characteristics for those
kinds of services. This paper presents an analysis of network
performance of last mile solution for the use of IPTV broadcasting
with the application of streaming for telemedicine apps.
Abstract: Spectrum handover is a significant topic in the
cognitive radio networks to assure an efficient data transmission in
the cognitive radio user’s communications. This paper proposes a
comparison between three spectrum handover models: VIKOR, SAW
and MEW. Four evaluation metrics are used. These metrics are,
accumulative average of failed handover, accumulative average of
handover performed, accumulative average of transmission
bandwidth and, accumulative average of the transmission delay. As a difference with related work, the performance of the three
spectrum handover models was validated with captured data of
spectrum occupancy in experiments performed at the GSM frequency
band (824 MHz - 849 MHz). These data represent the actual behavior
of the licensed users for this wireless frequency band. The results of the comparison show that VIKOR Algorithm
provides a 15.8% performance improvement compared to SAW
Algorithm and, it is 12.1% better than the MEW Algorithm.
Abstract: This paper develops a multiple channel assignment
model, which allows to take advantage of spectrum opportunities in
cognitive radio networks in the most efficient way. The developed
scheme allows making several assignments of available and
frequency adjacent channel, which require a bigger bandwidth, under
an equality environment. The hybrid assignment model it is made by
two algorithms, one that makes the ranking and selects available
frequency channels and the other one in charge of establishing the
Max-Min Fairness for not restrict the spectrum opportunities for all
the other secondary users, who also claim to make transmissions.
Measurements made were done for average bandwidth, average
delay, as well as fairness computation for several channel
assignments. Reached results were evaluated with experimental
spectrum occupational data from captured GSM frequency band. The
developed model shows evidence of improvement in spectrum
opportunity use and a wider average transmission bandwidth for each
secondary user, maintaining equality criteria in channel assignment.
Abstract: This study and the field test comparisons were carried
out on the Algerian Derguna – Setif transmission systems. The
transmission line of normal voltage 225 kV is 65 km long,
transported and uses twin bundle conductors protected with two
shield wires of transposed galvanized steel. An iterative finite-element method is used to solve Poisons
equation. Two algorithms are proposed for satisfying the current
continuity condition and updating the space-charge density. A new approach to the problem of corona discharge in
transmission system has been described in this paper. The effect of
varying the configurations and wires number is also investigated. The
analysis of this steady is important in the design of HVDC
transmission lines. The potential and electric field have been
calculating in locations singular points of the system.
Abstract: The main issue in designing a wireless sensor network
(WSN) is the finding of a proper routing protocol that complies with
the several requirements of high reliability, short latency, scalability,
low power consumption, and many others. This paper proposes a
novel routing algorithm that complies with these design
requirements. The new routing protocol divides the WSN into several subnetworks
and each sub-network is divided into several clusters. This
division is designed to reduce the number of radio transmission and
hence decreases the power consumption. The network division may
be changed dynamically to adapt with the network changes and
allows the realization of the design requirements.
Abstract: The shielding ability of a shielding cavity with an
aperture will be greatly degraded at resonance frequencies, and the
resonance modes and frequencies are affected by aperture resonances
and aperture-cavity coupling, which are closely related with aperture
sizes. The equivalent circuit method and numerical method of
Transmission Line Matrix (TLM) are used to analyze the effects of
aperture resonances and aperture-cavity coupling on the
electromagnetic resonances of a cavity with an aperture in this paper.
Both analytical and numerical results show that the resonance modes
of a shielding cavity with an aperture consist of cavity resonance
modes and aperture resonance modes, and the resonance frequencies
will shift with the change of the aperture sizes because of the aperture
resonances and aperture-cavity coupling. Variation rules of
electromagnetic resonances with aperture sizes for a cavity with an
aperture are given, which will be useful for design of shielding
cavities.
Abstract: The aim of this study was to investigate the
photocatalytic activity of polycrystalline phases of bismuth tungstate
of formula Bi2WO6. Polycrystalline samples were elaborated using a
coprecipitation technique followed by a calcination process at
different temperatures (300, 400, 600 and 900°C). The obtained
polycrystalline phases have been characterized by X-ray diffraction
(XRD), scanning electron microscopy (SEM), and transmission
electron microscopy (TEM). Crystal cell parameters and cell volume
depend on elaboration temperature. High-resolution electron
microscopy images and image simulations, associated with X-ray
diffraction data, allowed confirming the lattices and space groups
Pca21. The photocatalytic activity of the as-prepared samples was
studied by irradiating aqueous solutions of Rhodamine B, associated
with Bi2WO6 additives having variable crystallite sizes. The
photocatalytic activity of such bismuth tungstates increased as the
crystallite sizes decreased. The high specific area of the
photocatalytic particles obtained at 300°C seems to condition the
degradation kinetics of RhB.
Abstract: In internet of things (IoT) system, the communication
scheme with reliability and low power is required to connect a
terminal. Cooperative communication can achieve reliability and
lower power than multiple-input multiple-output (MIMO) system.
Cooperative communication increases the reliability with low
power, but decreases a throughput. It has a weak point that the
communication throughput is decreased. In this paper, a novel scheme
is proposed to increase the communication throughput. The novel
scheme is a transmission structure that increases transmission rate.
A decoding scheme according to the novel transmission structure is
proposed. Simulation results show that the proposed scheme increases
the throughput without bit error rate (BER) performance degradation.