Abstract: The aerodynamic stall control of a baseline 13-percent
thick NASA GA(W)-2 airfoil using a synthetic jet actuator (SJA) is
presented in this paper. Unsteady Reynolds-averaged Navier-Stokes
equations are solved on a hybrid grid using a commercial software to
simulate the effects of a synthetic jet actuator located at 13% of the
chord from the leading edge at a Reynolds number Re = 2.1x106 and
incidence angles from 16 to 22 degrees. The experimental data for the
pressure distribution at Re = 3x106 and aerodynamic coefficients at
Re = 2.1x106 (angle of attack varied from -16 to 22 degrees) without
SJA is compared with the computational fluid dynamic (CFD)
simulation as a baseline validation. A good agreement of the CFD
simulations is obtained for aerodynamic coefficients and pressure
distribution.
A working SJA has been integrated with the baseline airfoil and
initial focus is on the aerodynamic stall control at angles of attack
from 16 to 22 degrees. The results show a noticeable improvement in
the aerodynamic performance with increase in lift and decrease in
drag at these post stall regimes.
Abstract: Providing authentication for the messages exchanged
between group members in addition to confidentiality is an important
issue in Secure Group communication. We develop a protocol for
Secure Authentic Communication where we address authentication
for the group communication scheme proposed by Blundo et al.
which only provides confidentiality. Authentication scheme used is a
multiparty authentication scheme which allows all the users in the
system to send and receive messages simultaneously. Our scheme is
secure against colluding malicious parties numbering fewer than k.
Abstract: The motion planning technique described in this paper has been developed to eliminate or reduce the residual vibrations of belt-driven rotary platforms, while maintaining unchanged the motion time and the total angular displacement of the platform. The proposed approach is based on a suitable choice of the motion command given to the servomotor that drives the mechanical device; this command is defined by some numerical coefficients which determine the shape of the displacement, velocity and acceleration profiles. Using a numerical optimization technique, these coefficients can be changed without altering the continuity conditions imposed on the displacement and its time derivatives at the initial and final time instants. The proposed technique can be easily and quickly implemented on an actual device, since it requires only a simple modification of the motion command profile mapped in the memory of the electronic motion controller.
Abstract: This paper is devoted to predict laminar and turbulent
heating rates around blunt re-entry spacecraft at hypersonic
conditions. Heating calculation of a hypersonic body is normally
performed during the critical part of its flight trajectory. The
procedure is of an inverse method, where a shock wave is assumed,
and the body shape that supports this shock, as well as the flowfield
between the shock and body, are calculated. For simplicity the
normal momentum equation is replaced with a second order pressure
relation; this simplification significantly reduces computation time.
The geometries specified in this research, are parabola and ellipsoids
which may have conical after bodies. An excellent agreement is
observed between the results obtained in this paper and those
calculated by others- research. Since this method is much faster than
Navier-Stokes solutions, it can be used in preliminary design,
parametric study of hypersonic vehicles.
Abstract: Development of a Robust Supply Chain for Dynamic
Operating Environment as we move further into the twenty first
century, organisations are under increasing pressure to deliver a high
product variation at a reasonable cost without compromise in quality.
In a number of cases this will take the form of a customised or high
variety low volume manufacturing system that requires prudent
management of resources, among a number of functions, to achieve
competitive advantage. Purchasing and Supply Chain management is
one of such function and due to the substantial interaction with
external elements needs to be strategically managed. This requires a
number of primary and supporting tools that will enable the
appropriate decisions to be made rapidly. This capability is
especially vital in a dynamic environment as it provides a pivotal role
in increasing the profit margin of the product. The management of
this function can be challenging by itself and even more for Small
and Medium Enterprises (SMEs) due to the limited resources and
expertise available at their disposal.
This paper discusses the development of tools and concepts
towards effectively managing the purchasing and supply chain
function. The developed tools and concepts will provide a cost
effective way of managing this function within SMEs. The paper
further shows the use of these tools within Contechs, a manufacturer
of luxury boat interiors, and the associated benefits achieved as a
result of this implementation. Finally a generic framework towards
use in such environments is presented.
Abstract: This paper proposes and implements an core transform architecture, which is one of the major processes in HEVC video compression standard. The proposed core transform architecture is implemented with only adders and shifters instead of area-consuming multipliers. Shifters in the proposed core transform architecture are implemented in wires and multiplexers, which significantly reduces chip area. Also, it can process from 4×4 to 16×16 blocks with common hardware by reusing processing elements. Designed core transform architecture in 0.13um technology can process a 16×16 block with 2-D transform in 130 cycles, and its gate count is 101,015 gates.
Abstract: There are several ways of improving the performance of a vapor compression refrigeration cycle. Use of an ejector as expansion device is one of the alternative ways. The present paper aims at evaluate the performance improvement of a vapor compression refrigeration cycle under a wide range of operating conditions. A numerical model is developed and a parametric study of important parameters such as condensation (30-50°C) and evaporation temperatures (-20-5°C), nozzle and diffuser efficiencies (0.75-0.95), subcooling and superheating degrees (0-15K) are investigated. The model verification gives a good agreement with the literature data. The simulation results revealed that condensation temperature has the highest effect (129%) on the performance improvement ratio while superheating has the lowest one (6.2%). Among ejector efficiencies, the diffuser efficiency has a significant effect on the COP of ejector expansion refrigeration cycle. The COP improvement percentage decreases from 10.9% to 4.6% as subcooling degrees increases by 15K.
Abstract: The aim of the current work is to present a comparison among three popular optimization methods in the inverse elastostatics problem (IESP) of flaw detection within a solid. In more details, the performance of a simulated annealing, a Hooke & Jeeves and a sequential quadratic programming algorithm was studied in the test case of one circular flaw in a plate solved by both the boundary element (BEM) and the finite element method (FEM). The proposed optimization methods use a cost function that utilizes the displacements of the static response. The methods were ranked according to the required number of iterations to converge and to their ability to locate the global optimum. Hence, a clear impression regarding the performance of the aforementioned algorithms in flaw identification problems was obtained. Furthermore, the coupling of BEM or FEM with these optimization methods was investigated in order to track differences in their performance.
Abstract: True stress-strain curve of railhead steel is required to
investigate the behaviour of railhead under wheel loading through elasto-plastic Finite Element (FE) analysis. To reduce the rate of wear, the railhead material is hardened through annealing and
quenching. The Australian standard rail sections are not fully hardened and hence suffer from non-uniform distribution of the
material property; usage of average properties in the FE modelling can potentially induce error in the predicted plastic strains. Coupons
obtained at varying depths of the railhead were, therefore, tested under axial tension and the strains were measured using strain gauges as well as an image analysis technique, known as the Particle Image Velocimetry (PIV). The head hardened steel exhibit existence of three distinct zones of yield strength; the yield strength as the ratio of the average yield strength provided in the standard (σyr=780MPa) and
the corresponding depth as the ratio of the head hardened zone along
the axis of symmetry are as follows: (1.17 σyr, 20%), (1.06 σyr, 20%-80%) and (0.71 σyr, > 80%). The stress-strain curves exhibit limited plastic zone with fracture occurring at strain less than 0.1.
Abstract: This paper presents a wavelet transform and Support
Vector Machine (SVM) based algorithm for estimating fault location
on transmission lines. The Discrete wavelet transform (DWT) is used
for data pre-processing and this data are used for training and testing
SVM. Five types of mother wavelet are used for signal processing to
identify a suitable wavelet family that is more appropriate for use in
estimating fault location. The results demonstrated the ability of SVM
to generalize the situation from the provided patterns and to
accurately estimate the location of faults with varying fault resistance.
Abstract: The log periodogram regression is widely used in empirical
applications because of its simplicity, since only a least squares
regression is required to estimate the memory parameter, d, its good
asymptotic properties and its robustness to misspecification of the
short term behavior of the series. However, the asymptotic distribution
is a poor approximation of the (unknown) finite sample distribution
if the sample size is small. Here the finite sample performance of different
nonparametric residual bootstrap procedures is analyzed when
applied to construct confidence intervals. In particular, in addition to
the basic residual bootstrap, the local and block bootstrap that might
adequately replicate the structure that may arise in the errors of the
regression are considered when the series shows weak dependence in
addition to the long memory component. Bias correcting bootstrap
to adjust the bias caused by that structure is also considered. Finally,
the performance of the bootstrap in log periodogram regression based
confidence intervals is assessed in different type of models and how
its performance changes as sample size increases.
Abstract: Wireless Sensor Network is Multi hop Self-configuring
Wireless Network consisting of sensor nodes. The deployment of
wireless sensor networks in many application areas, e.g., aggregation
services, requires self-organization of the network nodes into clusters.
Efficient way to enhance the lifetime of the system is to partition the
network into distinct clusters with a high energy node as cluster head.
The different methods of node clustering techniques have appeared in
the literature, and roughly fall into two families; those based on the
construction of a dominating set and those which are based solely on
energy considerations. Energy optimized cluster formation for a set
of randomly scattered wireless sensors is presented. Sensors within a
cluster are expected to be communicating with cluster head only. The
energy constraint and limited computing resources of the sensor nodes
present the major challenges in gathering the data. In this paper we
propose a framework to study how partially correlated data affect the
performance of clustering algorithms. The total energy consumption
and network lifetime can be analyzed by combining random geometry
techniques and rate distortion theory. We also present the relation
between compression distortion and data correlation.
Abstract: Value engineering is an efficacious contraption for
administrators to make up their minds. Value perusals proffer the
gaffers a suitable instrument to decrease the expenditures of the life
span, quality amelioration, structural improvement, curtailment of the
construction schedule, longevity prolongation or a merging of the
aforementioned cases. Subjecting organizers to pressures on one
hand and their accountability towards their pertinent fields together
with inherent risks and ambiguities of other options on the other hand
set some comptrollers in a dilemma utilization of risk management
and the value engineering in projects manipulation with regard to
complexities of implementing projects can be wielded as a
contraption to identify and efface each item which wreaks
unnecessary expenses and time squandering sans inflicting any
damages upon the essential project applications. Of course It should
be noted that implementation of risk management and value
engineering with regard to the betterment of efficiency and functions
may lead to the project implementation timing elongation. Here time
revamping does not refer to time diminishing in the whole cases. his
article deals with risk and value engineering conceptualizations at
first. The germane reverberations effectuated due to its execution in
Iran Khodro Corporation are regarded together with the joint features
and amalgamation of the aforesaid entia; hence the proposed
blueprint is submitted to be taken advantage of in engineering and
industrial projects including Iran Khodro Corporation.
Abstract: The experimental design was 4 x 5 factorial with three
replications in fully controlled research greenhouse in Department of
Soil Sciences and Plant Nutrition, Faculty of Agriculture, University
of Selcuk in the year of 2009. Determination of tolerant chickpea
genotypes to drought was made in the research. Additionally,
sophisticated effects of drought on plant growth and development,
biochemical and physical properties or physical defense mechanisms
were presented. According to the results, the primary genotypes were
Ilgın YP (0.0063 g/gh) for leaf water capacity, 22235 70.44(%) for
relative water content, 22159 (82.47%) for real water content,
22159 (5.03 mg/l) for chlorophyll a+b, Ilgın YP (125.89 nmol
H2O2.dak-1/ mg protein-1) for peroxidase, Yunak YP (769.67
unit/ mg protein-1) for superoxide dismutase, Seydişehir YP
(16.74 μg.TA-1) for proline, Gökçe (80.01 nmol H2O2.dak-1/ mg
protein-1) for catalase. Consequently, all the genotypes
increased their enzyme activity depending on the increasing of
drought stress consider with the effects of drought stress on leaf
enzyme activity. Chickpea genotypes are increasing enzyme
activity against to drought stress.
Abstract: Today-s children, who are born into a more colorful,
more creative, more abstract and more accessible communication
environment than their ancestors as a result of dizzying advances in
technology, have an interesting capacity to perceive and make sense
of the world. Millennium children, who live in an environment where
all kinds of efforts by marketing communication are more intensive
than ever are, from their early childhood on, subject to all kinds of
persuasive messages. As regards advertising communication, it
outperforms all the other marketing communication efforts in
creating little consumer individuals and, as a result of processing of
codes and signs, plays a significant part in building a world of seeing,
thinking and understanding for children. Children who are raised with
metaphorical expressions such as tales and riddles also meet that fast
and effective meaning communication in advertisements.
Children-s perception of metaphors, which help grasp the “product
and its promise" both verbally and visually and facilitate association
between them is the subject of this study. Stimulating and activating
imagination, metaphors have unique advantages in promoting the
product and its promise especially in regard to print advertisements,
which have certain limitations. This study deals comparatively with
both literal and metaphoric versions of print advertisements
belonging to various product groups and attempts to discover to what
extent advertisements are liked, recalled, perceived and are
persuasive. The sample group of the study, which was conducted in
two elementary schools situated in areas that had different socioeconomic
features, consisted of children aged 12.
Abstract: Aerospace vehicles are subjected to non-uniform
thermal loading that may cause thermal buckling. A study was
conducted on the thermal post-buckling of shape memory alloy
composite plates subjected to the non-uniform tent-like temperature
field. The shape memory alloy wires were embedded within the
laminated composite plates to add recovery stress to the plates. The
non-linear finite element model that considered the recovery stress of
the shape memory alloy and temperature dependent properties of the
shape memory alloy and composite matrix along with its source
codes were developed. It was found that the post-buckling paths of
the shape memory alloy composite plates subjected to various tentlike
temperature fields were stable within the studied temperature
range. The addition of shape memory alloy wires to the composite
plates was found to significantly improve the post-buckling behavior
of laminated composite plates under non-uniform temperature
distribution.
Abstract: We have proposed an information filtering system
using index word selection from a document set based on the
topics included in a set of documents. This method narrows
down the particularly characteristic words in a document set
and the topics are obtained by Sparse Non-negative Matrix
Factorization. In information filtering, a document is often
represented with the vector in which the elements correspond
to the weight of the index words, and the dimension of the
vector becomes larger as the number of documents is
increased. Therefore, it is possible that useless words as index
words for the information filtering are included. In order to
address the problem, the dimension needs to be reduced. Our
proposal reduces the dimension by selecting index words
based on the topics included in a document set. We have
applied the Sparse Non-negative Matrix Factorization to the
document set to obtain these topics. The filtering is carried out
based on a centroid of the learning document set. The centroid
is regarded as the user-s interest. In addition, the centroid is
represented with a document vector whose elements consist of
the weight of the selected index words. Using the English test
collection MEDLINE, thus, we confirm the effectiveness of
our proposal. Hence, our proposed selection can confirm the
improvement of the recommendation accuracy from the other
previous methods when selecting the appropriate number of
index words. In addition, we discussed the selected index
words by our proposal and we found our proposal was able to
select the index words covered some minor topics included in
the document set.
Abstract: The effect of autofrettage process in strain hardened
thick-walled pressure vessels has been investigated theoretically by
finite element modeling. Equivalent von Mises stress is used as yield
criterion to evaluate the optimum autofrettage pressure and the
optimum radius of elastic-plastic junction. It has been observed that
the optimum autofrettage pressure increases along with the working
pressure. For two different working pressures, the effect of the ratio
of outer to inner radius (b/a=k) value on the optimum autofrettage
pressure is also noticed. The Optimum autofrettage pressure solely
depends on K value rather than on the inner or outer radius.
Furthermore, percentage reduction of von Mises stresses is compared
for different working pressures and different k values. Maximum von
Mises stress developed at different autofrettage pressure is equated
for elastic perfectly plastic and elastic-plastic material with different
slope of strain hardening segment. Cylinder material having higher
slope of strain hardening segment provides better benedictions in the
autofrettage process.
Abstract: The study investigated the educational implications
that can be derived from the work of a variety of celebrated figures
such as Piaget, Vygotsky, and Bruner that will be helpful in the field
of language learning. However, the writer believed these views were
previously expressed not full–fledged by Comenius who has been
described by Howatt (1984) as a genius–the one that the history of
language teaching can claim. And we owe to him more than anyone.
Abstract: This paper examines economic and Information and Communication Technology (ICT) development influence on recently increasing Internet purchases by individuals for European Union member states. After a growing trend for Internet purchases in EU27 was noticed, all possible regression analysis was applied using nine independent variables in 2011. Finally, two linear regression models were studied in detail. Conducted simple linear regression analysis confirmed the research hypothesis that the Internet purchases in analyzed EU countries is positively correlated with statistically significant variable Gross Domestic Product per capita (GDPpc). Also, analyzed multiple linear regression model with four regressors, showing ICT development level, indicates that ICT development is crucial for explaining the Internet purchases by individuals, confirming the research hypothesis.