Abstract: Numerical studies have been carried out using a two
dimensional code to examine the influence of pressure / thrust
transient of solid propellant rockets at liftoff. This code solves
unsteady Reynolds-averaged thin-layer Navier–Stokes equations by
an implicit LU-factorization time-integration method. The results
from the parametric study indicate that when the port is narrow there
is a possibility of increase in pressure / thrust-rise rate due to
relatively high flame spread rate. Parametric studies further reveal
that flame spread rate can be altered by altering the propellant
properties, igniter jet characteristics and nozzle closure burst pressure
without altering the grain configuration and/or the mission
demanding thrust transient. We observed that when the igniter
turbulent intensity is relatively low the vehicle could liftoff early due
to the early flow choking of the rocket nozzle. We concluded that the
high pressurization-rate has structural implications at liftoff in
addition to transient burning effect. Therefore prudent selection of the
port geometry and the igniter, for meeting the mission requirements,
within the given envelop are meaningful objectives for any designer
for the smooth liftoff of solid propellant rockets.
Abstract: Multiple criteria decision making (MCDM) is an approach to ranking the solutions and finding the best one when two or more solutions are provided. In this study, MCDM approach is proposed to select the most suitable scheduling rule of robotic flexible assembly cells (RFACs). Two MCDM approaches, Analytic Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) are proposed for solving the scheduling rule selection problem. The AHP method is employed to determine the weights of the evaluation criteria, while the TOPSIS method is employed to obtain final ranking order of scheduling rules. Four criteria are used to evaluate the scheduling rules. Also, four scheduling policies of RFAC are examined to choose the most appropriate one for this purpose. A numerical example illustrates applications of the suggested methodology. The results show that the methodology is practical and works in RFAC settings.
Abstract: Several methods are available for weight and shape
optimization of structures, among which Evolutionary Structural
Optimization (ESO) is one of the most widely used methods. In ESO,
however, the optimization criterion is completely case-dependent.
Moreover, only the improving solutions are accepted during the
search. In this paper a Simulated Annealing (SA) algorithm is used
for structural optimization problem. This algorithm differs from other
random search methods by accepting non-improving solutions. The
implementation of SA algorithm is done through reducing the
number of finite element analyses (function evaluations).
Computational results show that SA can efficiently and effectively
solve such optimization problems within short search time.
Abstract: This paper presents an application of Artificial Neural Network (ANN) to forecast actual cost of a project based on the earned value management system (EVMS). For this purpose, some projects randomly selected based on the standard data set , and it is produced necessary progress data such as actual cost ,actual percent complete , baseline cost and percent complete for five periods of project. Then an ANN with five inputs and five outputs and one hidden layer is trained to produce forecasted actual costs. The comparison between real and forecasted data show better performance based on the Mean Absolute Percentage Error (MAPE) criterion. This approach could be applicable to better forecasting the project cost and result in decreasing the risk of project cost overrun, and therefore it is beneficial for planning preventive actions.
Abstract: User satisfaction is one of the most used success
indicators in the research of information system (IS). Literature
shows user expectations have great influence on user satisfaction.
Both expectation and satisfaction of users are important for Hospital
Information Systems (HIS). Education, IS experience, age, attitude
towards change, business title, sex and working unit of the hospital,
are examined as the potential determinant of the medical users’
expectations. Data about medical user expectations are collected by
the “Expectation Questionnaire” developed for this study.
Expectation data are used for calculating the Expectation Meeting
Ratio (EMR) with the evaluation framework also developed for this
study. The internal consistencies of the answers to the questionnaire
are measured by Cronbach´s Alpha coefficient. The multivariate
analysis of medical user’s EMRs of HIS is performed by forward
stepwise binary logistic regression analysis. Education and business
title is appeared to be the determinants of expectations from HIS.
Abstract: Markov games can be effectively used to design
controllers for nonlinear systems. The paper presents two novel
controller design algorithms by incorporating ideas from gametheory
literature that address safety and consistency issues of the
'learned' control strategy. A more widely used approach for
controller design is the H∞ optimal control, which suffers from high
computational demand and at times, may be infeasible. We generate
an optimal control policy for the agent (controller) via a simple
Linear Program enabling the controller to learn about the unknown
environment. The controller is facing an unknown environment and
in our formulation this environment corresponds to the behavior rules
of the noise modeled as the opponent. Proposed approaches aim to
achieve 'safe-consistent' and 'safe-universally consistent' controller
behavior by hybridizing 'min-max', 'fictitious play' and 'cautious
fictitious play' approaches drawn from game theory. We empirically
evaluate the approaches on a simulated Inverted Pendulum swing-up
task and compare its performance against standard Q learning.
Abstract: Defense and Aerospace environment is continuously
striving to keep up with increasingly sophisticated Information
Technology (IT) in order to remain effective in today-s dynamic and
unpredictable threat environment. This makes IT one of the largest
and fastest growing expenses of Defense. Hundreds of millions of
dollars spent a year on IT projects. But, too many of those millions
are wasted on costly mistakes. Systems that do not work properly,
new components that are not compatible with old ones, trendy new
applications that do not really satisfy defense needs or lost through
poorly managed contracts.
This paper investigates and compiles the effective strategies that
aim to end exasperation with low returns and high cost of
Information Technology acquisition for defense; it tries to show how
to maximize value while reducing time and expenditure.
Abstract: In this paper we present the first Arabic sentence
dataset for on-line handwriting recognition written on tablet pc. The
dataset is natural, simple and clear. Texts are sampled from daily
newspapers. To collect naturally written handwriting, forms are
dictated to writers. The current version of our dataset includes 154
paragraphs written by 48 writers. It contains more than 3800 words
and more than 19,400 characters. Handwritten texts are mainly
written by researchers from different research centers. In order to use
this dataset in a recognition system word extraction is needed. In this
paper a new word extraction technique based on the Arabic
handwriting cursive nature is also presented. The technique is applied
to this dataset and good results are obtained. The results can be
considered as a bench mark for future research to be compared with.
Abstract: Due to urbanization, trees and plants which covered a great land mass of the earth and are an excellent carbon dioxide (CO2) absorber through photosynthesis are being replaced by several concrete based structures. It is therefore important to have these cement based structures absorb the large volume of carbon dioxide which the trees would have removed from the atmosphere during their useful lifespan. Hence the need for these cement based structures to be designed to serve other useful purposes in addition to shelter. This paper reviews the properties of Sodium carbonate and sugar as admixtures in concrete with respect to improving carbon sequestration in concrete.
Abstract: This study deals with a multi-criteria optimization
problem which has been transformed into a single objective
optimization problem using Response Surface Methodology (RSM),
Artificial Neural Network (ANN) and Grey Relational Analyses
(GRA) approach. Grey-RSM and Grey-ANN are hybrid techniques
which can be used for solving multi-criteria optimization problem.
There have been two main purposes of this research as follows.
1. To determine optimum and robust fiber dyeing process
conditions by using RSM and ANN based on GRA,
2. To obtain the best suitable model by comparing models
developed by different methodologies.
The design variables for fiber dyeing process in textile are
temperature, time, softener, anti-static, material quantity, pH,
retarder, and dispergator. The quality characteristics to be evaluated
are nominal color consistency of fiber, maximum strength of fiber,
minimum color of dyeing solution. GRA-RSM with exact level
value, GRA-RSM with interval level value and GRA-ANN models
were compared based on GRA output value and MSE (Mean Square
Error) performance measurement of outputs with each other. As a
result, GRA-ANN with interval value model seems to be suitable
reducing the variation of dyeing process for GRA output value of the
model.
Abstract: Science parks are often established to drive regional
economic growth, especially in countries with emerging economies.
However, mixed findings regarding the performances of science park
firms are found in the literature. This study tries to explain these
mixed findings by taking a relational approach and exploring
(un)intended knowledge transfers between new technology-based
firms (NTBFs) in the emerging South African economy. Moreover,
the innovation outcomes of these NTBFs are examined by using a
multi-dimensional construct. Results show that science park location
plays a significant role in explaining innovative sales, but is
insignificant when a different indicator of innovation outcomes is
used. Furthermore, only for innovations that are new to the firms,
both science park location and intended knowledge transfer via
informal business relationships have a positive impact; whereas
social relationships have a negative impact.
Abstract: A number of previous studies were rarely considered
the effects of transient non-uniform balloon expansion on evaluation
of the properties and behaviors of stents during stent expansion, nor
did they determine parameters to maximize the performances driven
by mechanical characteristics. Therefore, in order to fully understand
the mechanical characteristics and behaviors of stent, it is necessary to
consider a realistic modeling of transient non-uniform balloon-stent
expansion. The aim of the study is to propose design parameters
capable of improving the ability of vascular stent through a
comparative study of seven commercial stents using finite element
analyses of a realistic transient non-uniform balloon-stent expansion
process. In this study, seven representative commercialized stents were
evaluated by finite element (FE) analysis in terms of the criteria based
on the itemized list of Food and Drug Administration (FDA) and
European Standards (prEN). The results indicate that using stents
composed of opened unit cells connected by bend-shaped link
structures and controlling the geometrical and morphological features
of the unit cell strut or the link structure at the distal ends of stent may
improve mechanical characteristics of stent. This study provides a
better method at the realistic transient non-uniform balloon-stent
expansion by investigating the characteristics, behaviors, and
parameters capable of improving the ability of vascular stent.
Abstract: A two-parameter fatigue model explicitly accounting for the cyclic as well as the mean stress was used to fit static and fatigue data available in literature concerning carbon fiber reinforced composite laminates subjected tension-tension fatigue. The model confirms the strength–life equal rank assumption and predicts reasonably the probability of failure under cyclic loading. The model parameters were found by best fitting procedures and required a minimum of experimental tests.
Abstract: Cross layer optimization based on utility functions has
been recently studied extensively, meanwhile, numerous types of
utility functions have been examined in the corresponding literature.
However, a major drawback is that most utility functions take a fixed
mathematical form or are based on simple combining, which can
not fully exploit available information. In this paper, we formulate a
framework of cross layer optimization based on Adaptively Weighted
Utility Functions (AWUF) for fairness balancing in OFDMA networks.
Under this framework, a two-step allocation algorithm is
provided as a sub-optimal solution, whose control parameters can be
updated in real-time to accommodate instantaneous QoS constrains.
The simulation results show that the proposed algorithm achieves
high throughput while balancing the fairness among multiple users.
Abstract: Paced Auditory Serial Addition Test (PASAT) has
been used as a common research tool for different neurological
disorders like Multiple Sclerosis. Recently, technology let
researchers to introduce a new versions of the visual test, the paced
visual serial addition test (PVSAT). In this paper, the computerized
version of these two tests is introduced. Beside the number of true
responses are interpreted, the reaction time of subjects are calculated
by the software. We hypothesize that paying attention to the reaction
time may be valuable. For this purpose, sixty eight female normal
subjects and fifty eight male normal subjects are enrolled in the
study. We investigate the similarity between the PASAT3 and
PVSAT3 in number of true responses and the new criterion (the
average reaction time of each subject). The similarity between two
tests were rejected (p-value = 0.000) which means that these two test
differ. The effect of sex in the tests were not approved since the pvalues
of different between PASAT3 and PVSAT3 in both sex is the
same (p-value = 0.000) which means that male and female subjects
performed the tests at no different level of performance. The new
criterion shows a negative correlation with the age which offers aged
normal subjects may have the same number of true responses as the
young subjects but they have latent responses. This will give prove
for the importance of reaction time.
Abstract: The noteworthy point in the advancement of Brain Machine Interface (BMI) research is the ability to accurately extract features of the brain signals and to classify them into targeted control action with the easiest procedures since the expected beneficiaries are of disabled. In this paper, a new feature extraction method using the combination of adaptive band pass filters and adaptive autoregressive (AAR) modelling is proposed and applied to the classification of right and left motor imagery signals extracted from the brain. The introduction of the adaptive bandpass filter improves the characterization process of the autocorrelation functions of the AAR models, as it enhances and strengthens the EEG signal, which is noisy and stochastic in nature. The experimental results on the Graz BCI data set have shown that by implementing the proposed feature extraction method, a LDA and SVM classifier outperforms other AAR approaches of the BCI 2003 competition in terms of the mutual information, the competition criterion, or misclassification rate.
Abstract: This paper describes a new algorithm of arrangement
in parallel, based on Odd-Even Mergesort, called division and
concurrent mixes. The main idea of the algorithm is to achieve that
each processor uses a sequential algorithm for ordering a part of the
vector, and after that, for making the processors work in pairs in
order to mix two of these sections ordered in a greater one, also
ordered; after several iterations, the vector will be completely
ordered. The paper describes the implementation of the new
algorithm on a Message Passing environment (such as MPI). Besides,
it compares the obtained experimental results with the quicksort
sequential algorithm and with the parallel implementations (also on
MPI) of the algorithms quicksort and bitonic sort. The comparison
has been realized in an 8 processors cluster under GNU/Linux which
is running on a unique PC processor.
Abstract: In order to encourage the construction of green homes
(GH) in Malaysia, a simple and attainable framework for designing
and building GHs is needed. This can be achieved by aligning GH
principles against Cole-s 'Sustainable Building Criteria' (SBC). This
set of considerations was used to categorize the GH features of three
case studies from Malaysia. Although the categorization of building
features is useful at exploring the presence of sustainability
inclinations of each house, the overall impact of building features in
each of the five SBCs are unknown. Therefore, this paper explored
the possibility of quantifying the impact of building features
categorized in SBC1 – “Buildings will have to adapt to the new
environment and restore damaged ecology while mitigating resource
use" based on existing GH assessment tools and methods and other
literature. This process as reported in this paper could lead to a new
dimension in green home rating and assessment methods.
Abstract: Restoration of endodontically treated teeth is a
common problem in dentistry, related to the fractures occurring in
such teeth and to concentration of forces little information regarding
variation of basic preparation guidelines in stress distribution has
been available. To date, there is still no agreement in the literature
about which material or technique can optimally restore
endodontically treated teeth. The aim of the present study was to
evaluate the influence of the core height and restoration materials on
corono-radicular restored upper first premolar. The first step of the
study was to achieve 3D models in order to analyze teeth, dowel and
core restorations and overlying full ceramic crowns. The FEM model
was obtained by importing the solid model into ANSYS finite
element analysis software. An occlusal load of 100 N was conducted,
and stresses occurring in the restorations, and teeth structures were
calculated. Numerical simulations provide a biomechanical
explanation for stress distribution in prosthetic restored teeth. Within
the limitations of the present study, it was found that the core height
has no important influence on the stress generated in coronoradicular
restored premolars. It can be drawn that the cervical regions
of the teeth and restorations were subjected to the highest stress
concentrations.
Abstract: Waiting times and queues are a daily problem for theme parks. Fast lines or priority queues appear as a solution for a specific segment of customers, that is, tourists who are willing to pay to avoid waiting. This paper analyzes the fast line system and explores the factors that affect the decision to purchase a fast line pass. A greater understanding of these factors may help companies to design appropriate products and services. This conceptual paper was based on a literature review in marketing and consumer behavior. Additional research was identified in related disciplines such as leisure studies, psychology, and sociology. A conceptual framework of the factors influencing the decision to purchase a fast line pass is presented.