Abstract: Although silicon photonic devices provide a significantly larger bandwidth and dissipate a substantially less power than the electronic devices, they suffer from a large size due to the fundamental diffraction limit and the weak optical response of Si. A potential solution is to exploit Si plasmonics, which may not only miniaturize the photonic device far beyond the diffraction limit, but also enhance the optical response in Si due to the electromagnetic field confinement. In this paper, we discuss and summarize the recently developed metal-insulator-Si-insulator-metal nanoplasmonic waveguide as well as various passive and active plasmonic components based on this waveguide, including coupler, bend, power splitter, ring resonator, MZI, modulator, detector, etc. All these plasmonic components are CMOS compatible and could be integrated with electronic and conventional dielectric photonic devices on the same SOI chip. More potential plasmonic devices as well as plasmonic nanocircuits with complex functionalities are also addressed.
Abstract: This paper describes a steady state model of a multiple
effect evaporator system for simulation and control purposes. The
model includes overall as well as component mass balance equations,
energy balance equations and heat transfer rate equations for area
calculations for all the effects. Each effect in the process is
represented by a number of variables which are related by the energy
and material balance equations for the feed, product and vapor flow
for backward, mixed and split feed. For simulation 'fsolve' solver in
MATLAB source code is used. The optimality of three sequences i.e.
backward, mixed and splitting feed is studied by varying the various
input parameters.
Abstract: The mixture formation prior to the ignition process
plays as a key element in the diesel combustion. Parametric studies of
mixture formation and ignition process in various injection parameter
has received considerable attention in potential for reducing
emissions. Purpose of this study is to clarify the effects of injection
pressure on mixture formation and ignition especially during ignition
delay period, which have to be significantly influences throughout the
combustion process and exhaust emissions. This study investigated
the effects of injection pressure on diesel combustion fundamentally
using rapid compression machine. The detail behavior of mixture
formation during ignition delay period was investigated using the
schlieren photography system with a high speed camera. This method
can capture spray evaporation, spray interference, mixture formation
and flame development clearly with real images. Ignition process and
flame development were investigated by direct photography method
using a light sensitive high-speed color digital video camera. The
injection pressure and air motion are important variable that strongly
affect to the fuel evaporation, endothermic and prolysis process
during ignition delay. An increased injection pressure makes spray tip
penetration longer and promotes a greater amount of fuel-air mixing
occurs during ignition delay. A greater quantity of fuel prepared
during ignition delay period thus predominantly promotes more rapid
heat release.
Abstract: Optimal capacitor allocation in distribution systems
has been studied for a long times. It is an optimization problem
which has an objective to define the optimal sizes and locations of
capacitors to be installed. In this works, an overview of capacitor
placement problem in distribution systems is briefly introduced. The
objective functions and constraints of the problem are listed and the
methodologies for solving the problem are summarized.
Abstract: With the rapid popularization of internet services, it is apparent that the next generation terrestrial communication systems must be capable of supporting various applications like voice, video, and data. This paper presents the performance evaluation of turbo- coded mobile terrestrial communication systems, which are capable of providing high quality services for delay sensitive (voice or video) and delay tolerant (text transmission) multimedia applications in urban and suburban areas. Different types of multimedia information require different service qualities, which are generally expressed in terms of a maximum acceptable bit-error-rate (BER) and maximum tolerable latency. The breakthrough discovery of turbo codes allows us to significantly reduce the probability of bit errors with feasible latency. In a turbo-coded system, a trade-off between latency and BER results from the choice of convolutional component codes, interleaver type and size, decoding algorithm, and the number of decoding iterations. This trade-off can be exploited for multimedia applications by using optimal and suboptimal performance parameter amalgamations to achieve different service qualities. The results are therefore proposing an adaptive framework for turbo-coded wireless multimedia communications which incorporate a set of performance parameters that achieve an appropriate set of service qualities, depending on the application's requirements.
Abstract: Effective evaluation of software development effort is an important issue during project plan. This study provides a model to predict development effort based on the software size estimated with function points. We generalize the average amount of effort spent on each phase of the development, and give the estimates for the effort used in software building, testing, and implementation. Finally, this paper finds a strong correlation between software defects and software size. As the size of software constantly increases, the quality remains to be a matter which requires major concern.
Abstract: The Influence Diagrams (IDs) is a kind of Probabilistic Belief Networks for graphic modeling. The usage of IDs can improve the communication among field experts, modelers, and decision makers, by showing the issue frame discussed from a high-level point of view. This paper enhances the Time-Sliced Influence Diagrams (TSIDs, or called Dynamic IDs) based formalism from a Discrete Event Systems Modeling and Simulation (DES M&S) perspective, for Exploring Analysis (EA) modeling. The enhancements enable a modeler to specify times occurred of endogenous events dynamically with stochastic sampling as model running and to describe the inter- influences among them with variable nodes in a dynamic situation that the existing TSIDs fails to capture. The new class of model is named Dynamic-Stochastic Influence Diagrams (DSIDs). The paper includes a description of the modeling formalism and the hiberarchy simulators implementing its simulation algorithm, and shows a case study to illustrate its enhancements.
Abstract: Some of the students' problems in writing skill stem
from inadequate preparation for the writing assignment. Students
should be taught how to write well when they arrive in language
classes. Having selected a topic, the students examine and explore the
theme from as large a variety of viewpoints as their background and
imagination make possible. Another strategy is that the students
prepare an Outline before writing the paper. The comparison between
the two mentioned thought provoking techniques was carried out
between the two class groups –students of Islamic Azad University of
Dezful who were studying “Writing 2" as their main course. Each
class group was assigned to write five compositions separately in
different periods of time. Then a t-test for each pair of exams between
the two class groups showed that the t-observed in each pair was
more than the t-critical. Consequently, the first hypothesis which
states those who utilize Brainstorming as a thought provoking
technique in prewriting phase are more successful than those who
outline the papers before writing was verified.
Abstract: In this study, stress distributions on dental implants
made of functionally graded biomaterials (FGBM) are investigated
numerically. The implant body is considered to be subjected to axial
compression loads. Numerical problem is assumed to be 2D, and
ANSYS commercial software is used for the analysis. The cross
section of the implant thread varies as varying the height (H) and the
width (t) of the thread. According to thread dimensions of implant
and material properties of FGBM, equivalent stress distribution on
the implant is determined and presented with contour plots along
with the maximum equivalent stress values. As a result, with
increasing material gradient parameter (n), the equivalent stress
decreases, but the minimum stress distribution increases. Maximum
stress values decrease with decreasing implant radius (r). Maximum
von Mises stresses increases with decreasing H when t is constant.
On the other hand, the stress values are not affected by variation of t
in the case of H = constant.
Abstract: The design of weight is one of the important parts in
fuzzy decision making, as it would have a deep effect on the evaluation
results. Entropy is one of the weight measure based on objective
evaluation. Non--probabilistic-type entropy measures for fuzzy set
and interval type-2 fuzzy sets (IT2FS) have been developed and applied
to weight measure. Since the entropy for (IT2FS) for decision
making yet to be explored, this paper proposes a new objective
weight method by using entropy weight method for multiple attribute
decision making (MADM). This paper utilizes the nature of IT2FS
concept in the evaluation process to assess the attribute weight based
on the credibility of data. An example was presented to demonstrate
the feasibility of the new method in decision making. The entropy
measure of interval type-2 fuzzy sets yield flexible judgment and
could be applied in decision making environment.
Abstract: In the present work homogeneous silica film on
silicon was fabricated by colloidal silica sol. The silica sol precursor
with uniformly granular particle was derived by the alkaline
hydrolysis of tetraethoxyorthosilicate (TEOS) in presence of glycerol
template. The film was prepared by dip coating process. The
templated hetero-structured silica film was annealed at elevated
temperatures to generate nano- and meso porosity in the film. The
film was subsequently annealed at different temperatures to make it
defect free and abrasion resistant. The sol and the film were
characterized by the measurement of particle size distribution,
scanning electron microscopy, XRD, FTIR spectroscopy,
transmission electron microscopy, atomic force microscopy,
measurement of the refractive index, thermal conductivity and
abrasion resistance. The porosity of the films decreased whereas
refractive index and dielectric constant of it `increased with the
increase in the annealing temperature. The thermal conductivity of
the films increased with the increase in the film thickness. The
developed porous silica film holds strong potential for use in
different areas.
Abstract: Combustion of sprays is of technological importance, but its flame behavior is not fully understood. Furthermore, the multiplicity of dependent variables such as pressure, temperature, equivalence ratio, and droplet sizes complicates the study of spray combustion. Fundamental study on the influence of the presence of liquid droplets has revealed that laminar flames within aerosol mixtures more readily become unstable than for gaseous ones and this increases the practical burning rate. However, fundamental studies on turbulent flames of aerosol mixtures are limited particularly those under near mono-dispersed droplet conditions. In the present work, centrally ignited expanding flames at near atmospheric pressures are employed to quantify the burning rates in gaseous and aerosol flames. Iso-octane-air aerosols are generated by expansion of the gaseous pre-mixture to produce a homogeneously distributed suspension of fuel droplets. The effects of the presence of droplets and turbulence velocity in relation to the burning rates of the flame are also investigated.
Abstract: This paper demonstrates how the soft systems
methodology can be used to improve the delivery of a module in data warehousing for fourth year information technology students.
Graduates in information technology needs to have academic skills
but also needs to have good practical skills to meet the skills requirements of the information technology industry. In developing
and improving current data warehousing education modules one has to find a balance in meeting the expectations of various role players such as the students themselves, industry and academia. The soft
systems methodology, developed by Peter Checkland, provides a
methodology for facilitating problem understanding from different world views. In this paper it is demonstrated how the soft systems methodology can be used to plan the improvement of data
warehousing education for fourth year information technology students.
Abstract: Corner detection and optical flow are common techniques for feature-based video stabilization. However, these algorithms are computationally expensive and should be performed at a reasonable rate. This paper presents an algorithm for discarding irrelevant feature points and maintaining them for future use so as to improve the computational cost. The algorithm starts by initializing a maintained set. The feature points in the maintained set are examined against its accuracy for modeling. Corner detection is required only when the feature points are insufficiently accurate for future modeling. Then, optical flows are computed from the maintained feature points toward the consecutive frame. After that, a motion model is estimated based on the simplified affine motion model and least square method, with outliers belonging to moving objects presented. Studentized residuals are used to eliminate such outliers. The model estimation and elimination processes repeat until no more outliers are identified. Finally, the entire algorithm repeats along the video sequence with the points remaining from the previous iteration used as the maintained set. As a practical application, an efficient video stabilization can be achieved by exploiting the computed motion models. Our study shows that the number of times corner detection needs to perform is greatly reduced, thus significantly improving the computational cost. Moreover, optical flow vectors are computed for only the maintained feature points, not for outliers, thus also reducing the computational cost. In addition, the feature points after reduction can sufficiently be used for background objects tracking as demonstrated in the simple video stabilizer based on our proposed algorithm.
Abstract: The Information and Communication Technologies
(ICTs), and the Wide World Web (WWW) have fundamentally
altered the practice of teaching and learning world wide. Many
universities, organizations, colleges and schools are trying to apply
the benefits of the emerging ICT. In the early nineties the term
learning object was introduced into the instructional technology
vernacular; the idea being that educational resources could be broken
into modular components for later combination by instructors,
learners, and eventually computes into larger structures that would
support learning [1]. However in many developing countries, the use
of ICT is still in its infancy stage and the concept of learning object
is quite new. This paper outlines the learning object design
considerations for developing countries depending on learning
environment.
Abstract: Wetting characteristics of reactive (Sn–0.7Cu solder)
and non– reactive (castor oil) wetting of liquids on Cu and Ag plated
Al substrates have been investigated. Solder spreading exhibited
capillary, gravity and viscous regimes. Oils did not exhibit noticeable
spreading regimes. Solder alloy showed better wettability on Ag
coated Al substrate compared to Cu plating. In the case of castor oil,
Cu coated Al substrate exhibited good wettability as compared to Ag
coated Al substrates. The difference in wettability during reactive
wetting of solder and non–reactive wetting of oils is attributed to the
change in the surface energies of Al substrates brought about by the
formation of intermetallic compounds (IMCs).
Abstract: This article proposes a voltage-mode
multifunction filter using differential voltage current
controllable current conveyor transconductance amplifier
(DV-CCCCTA). The features of the circuit are that: the
quality factor and pole frequency can be tuned independently
via the values of capacitors: the circuit description is very
simple, consisting of merely 1 DV-CCCCTA, and 2
capacitors. Without any component matching conditions, the
proposed circuit is very appropriate to further develop into
an integrated circuit. Additionally, each function response
can be selected by suitably selecting input signals with
digital method. The PSpice simulation results are depicted.
The given results agree well with the theoretical anticipation.
Abstract: In this article, we aim to discuss the formulation of two explicit group iterative finite difference methods for time-dependent two dimensional Burger-s problem on a variable mesh. For the non-linear problems, the discretization leads to a non-linear system whose Jacobian is a tridiagonal matrix. We discuss the Newton-s explicit group iterative methods for a general Burger-s equation. The proposed explicit group methods are derived from the standard point and rotated point Crank-Nicolson finite difference schemes. Their computational complexity analysis is discussed. Numerical results are given to justify the feasibility of these two proposed iterative methods.
Abstract: The dynamic spectrum allocation solutions such as
cognitive radio networks have been proposed as a key technology to
exploit the frequency segments that are spectrally underutilized.
Cognitive radio users work as secondary users who need to
constantly and rapidly sense the presence of primary users or
licensees to utilize their frequency bands if they are inactive. Short
sensing cycles should be run by the secondary users to achieve
higher throughput rates as well as to provide low level of interference
to the primary users by immediately vacating their channels once
they have been detected. In this paper, the throughput-sensing time
relationship in local and cooperative spectrum sensing has been
investigated under two distinct scenarios, namely, constant primary
user protection (CPUP) and constant secondary user spectrum
usability (CSUSU) scenarios. The simulation results show that the
design of sensing slot duration is very critical and depends on the
number of cooperating users under CPUP scenario whereas under
CSUSU, cooperating more users has no effect if the sensing time
used exceeds 5% of the total frame duration.
Abstract: Xanthan gum is one of the major commercial
biopolymers. Due to its excellent rheological properties xanthan gum
is used in many applications, mainly in food industry. Commercial
production of xanthan gum uses glucose as the carbon substrate;
consequently the price of xanthan production is high. One of the
ways to decrease xanthan price, is using cheaper substrate like
agricultural wastes. Iran is one of the biggest date producer countries.
However approximately 50% of date production is wasted annually.
The goal of this study is to produce xanthan gum from waste date
using Xanthomonas campestris PTCC1473 by submerged
fermentation. In this study the effect of three variables including
phosphor and nitrogen amount and agitation rate in three levels using
response surface methodology (RSM) has been studied. Results
achieved from statistical analysis Design Expert 7.0.0 software
showed that xanthan increased with increasing level of phosphor.
Low level of nitrogen leaded to higher xanthan production. Xanthan
amount, increasing agitation had positive influence. The statistical
model identified the optimum conditions nitrogen amount=3.15g/l,
phosphor amount=5.03 g/l and agitation=394.8 rpm for xanthan. To
model validation, experiments in optimum conditions for xanthan
gum were carried out. The mean of result for xanthan was 6.72±0.26.
The result was closed to the predicted value by using RSM.