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Silicon Carbide (SiC), a wide band gap semiconductor, is
gaining acceptability in
electronic devices, particularly in high temperature and harsh environment
applications where conventional materials such as silicon and
Gallium Arsenide cease to provide sustainability. The performance enhancements
offered by the next generation of SiC high power devices will see an enormous
growth in SiC power device markets in the next few years. For this growth to occur,
it is imperative that substrate and epitaxial material quality increases to meet
the needs of the targeted applications. In the paper titled, "Wet Thermal
Oxidation of Epitaxial 4H-SiC Substrate: An Experimental Process for Device
Fabrication", Sanjeev Kumar Gupta, Ameer Azam and Jamil Akhtar, report the optimization
of an experimental technique for the growth of
SiO2 on epitaxial 4H-SiC substrate. The reaction mechanisms and the growth dynamics have been
quantitatively studied by analyzing the statistical plot with different oxidation time.
Analog signal processing using current-mode circuits makes use of electric
current signals. This has a number of advantages over the conventional voltage
mode circuits which utilize electric voltages. Current-mode approach to signal
processing has often claimed to provide one or more of the following advantages:
higher frequency range of operation, lower power consumption, higher slew
rates, improved linearity, and better accuracy. The current-mode circuits require
less number of active and passive components for the realization of filter
functions, compared to voltage-mode circuits. Further, the addition of filter responses in
the current mode circuits require no additional hardware and is therefore economical.
The current mode analog signal processing is also popular due to its suitability
for Integarated Circuit (IC) fabrication techniques such as Complementary Metal
Oxide Semiconductor (CMOS). The paper "A Novel Design of CMOS DO-CCII for Use
in Current-Mode Applications", by Hassan J Motlak, Syed A
Imam and S Naseem Ahmad, proposes a new second generation Current Conveyor (CMOS CCII)
based on the resistive compensation technique. P-spice simulations for MIETEC 0.5 mm CMOS technology show that the current mode and voltage mode bandwidths
are 2.3 GHz and 3.3 GHz respectively, with power consumption of 2 mW. This
result is consistent with many earlier reports which suggest that resistive
compensation technique is a very simple and powerful technique used to improve the
bandwidth of CMOS DO-CCII without extra power consumption.
Segmentation refers to the process of partitioning a digital image into
multiple regions (sets of pixels). The goal of segmentation is to simplify and/or
change the representation of an image into something that is more meaningful
and easier
to analyze. Image segmentation is typically used to locate objects
and boundaries (lines, curves, etc.) in images. The result of image segmentation
is a set of regions that collectively cover the entire image, or a set of
contours extracted from the image. Each of the pixels in a region is similar with
respect to some characteristic or computed property, such as color, intensity, or
texture. Adjacent regions are significantly different with respect to the
same characteristic. The survey paper, "Role of Metaheuristics Optimization
Approach in Image Segmentation Techniques", by Tilottama
Goswami, emphasizes the recent use and increasing growth of the metaheuristics approach based
on natural computing inspired by natural and biological systems for solving
the image segmentation specific to various domain specific applications. This
paper works towards bridging the gap with regard to
drawbacks of the state-of-the-art solution of various segmentation techniques and the available
metaheuristic techniques and technologies like particle swarm optimization, ant
colony optimization and genetic algorithms.
In today's increasingly electronic society and rapid advances of
electronic commerce on the Internet, plastic money has replaced paper money. The use
of credit cards for purchases has become convenient and necessary. However,
a growing number of credit card transactions provide more opportunities for
credit card fraud. Quick and efficient fraud detection systems go a long way in
reducing the losses due to credit card fraud and act as deterents. Since only one
financial transaction in a few thousands is fraudulent,
no prediction success less than 99.9% is acceptable. In their paper titled,
"Credit Card Fraud Detection Using Artificial Neural Networks with a
Rule-Based Component", Ogwueleka Francisca Nonyelum and Inyiama Hyacinth
Chibueze, have reported how the advanced data mining techniques and neural
network algorithm can be combined successfully to obtain a high fraud coverage
combined with a low false alarm rate.
The authors have developed a detection system that uses a four-stage
model in the algorithm to reduce the error in fraud detection. A performance
analysis of the system developed performed comparatively better than the
two commercially available products.
The generation of multiple beams using antenna array is required in a number
of communication systems like mobile and cellular communications. A multiple
beam forming network controls the amplitude and phase of the beam at each
antenna element. Using bootlace lens as a microwave lens for multiple beam formation
is well known for its design simplicity. In their paper, "Design of Bootlace Lens
Beam Forming Network of Three Input Ports", G S Tomar, Ravi Pratap Singh
Kushwah and P K Singhal report the design specifications, fabrication and testing of
equal height circular bootlace lens with tapered line section. The lens fabricated
is reported to involve less design complexities and covers an angular area from
+28o to -30o.
The field of antenna engineering is central to all wireless technologies and
plays a vital role in the successful deployment of network systems. Some of
the requirements imposed on an antenna are as follows: it should be relatively
cheap and easy to manufacture; should be light in weight and compact, with a low
profile but robust body; and should be environment-friendly. The microstrip patch
antenna fulfills these requirements, although nonrelenting efforts are still on to
further miniaturize the antenna. IUP has in recent years
published a number of important results on microstrip anntena by a research team
from Gulburga University, Karnataka, India. The paper titled, "A Comparative Study
of Compact Stacked Rectangular Microstrip Antennas Using a Pair of T-shaped Slots",
is another contribution by the team, Ravi M Yadahalli, Vani R M and P V
Hunagund, where the effect of embedding a pair of T-shaped slots in the lower and
upper patches of stacked rectangular microstrip antenna is studied. Simulation
techniques were used to obtain their effect on the bandwidth. After verifying the
results experimentally, the authors conclude that the T-shaped slots in the lower patch
result in greater compactness of the antenna. The microstrip antenna with slots
embedded in both the patches, however, show larger bandwidth.
--
Elizabeth Zacharias
Consulting Editor |
