Abstract: The outstanding mechanical properties of Carbon
nanotubes (CNTs) have generated great interest for their potential as
reinforcements in high performance cementitious composites. The
main challenge in research is the proper dispersion of carbon
nanotubes in the cement matrix. The present work discusses the role
of dispersion of multiwalled carbon nanotubes (MWCNTs) on the
compressive strength characteristics of hydrated Portland IS 1489
cement paste. Cement-MWCNT composites with different mixing
techniques were prepared by adding 0.2% (by weight) of MWCNTs
to Portland IS 1489 cement. Rectangle specimens of size
approximately 40mm × 40mm ×160mm were prepared and curing of
samples was done for 7, 14, 28 and 35days. An appreciable increase
in compressive strength with both techniques; mixture of MWCNTs
with cement in powder form and mixture of MWCNTs with cement
in hydrated form 7 to 28 days of curing time for all the samples was
observed.
Abstract: Slab sliding system (SSS) with Coulomb friction
interface between slab and supporting frame is a passive structural
vibration control technology. The system can significantly reduce the
slab acceleration and accompanied lateral force of the frame. At the
same time it is expected to cause the slab displacement magnification
by sliding movement. To obtain the general comprehensive seismic
response of a single story structure, inelastic response spectra were
computed for a large ensemble of ground motions and a practical range
of structural periods and friction coefficient values. It was shown that
long period structures have no trade-off relation between force
reduction and displacement magnification with respect to elastic
response, unlike short period structures. For structures with the
majority of mass in the slab, the displacement magnification value can
be predicted according to simple inelastic displacement relation for
inelastically responding SDOF structures because the system behaves
elastically to a SDOF structure.
Abstract: Mangabeira (Hancornia speciosa Gomes), a native plant in Brazil, is found growing spontaneously in various regions of the country. The high perishability of tropical fruits such as mangaba, causes it to be necessary to use technologies that promote conservation, aiming to increase the shelf life of this fruit and add value. The objective of this study was to compare the mangabas lyophilization curves behaviors with different sizes and maturation stages. The fruits were freeze-dried for a period of approximately 45 hours at lyophilizer Liotop brand, model L -108. It has been considered large the fruits between 38 and 58 mm diameter and small, between 23 and 28 mm diameter and the two states of maturation, intermediate and mature. Large size mangabas drying curves in both states of maturation were linear behavior at all process, while the kinetic drying curves related to small fruits, independent of maturation state, had a typical behavior of drying, with all the well-defined steps. With these results it was noted that the time of lyophilization was suitable for small mangabas, a fact that did not happen with the larger one. This may indicate that the large mangabas require a longer time to freeze until reaches the equilibrium level, as it happens with the small fruits, going to have constant moisture at the end of the process. For both types of fruit were analyzed water activity, acidity, protein, lipid, and vitamin C before and after the process.
Abstract: Recently, ‘play of learning’ becomes important and is
emphasized as a useful learning tool. Therefore, interest in
edutainment contents is growing. Storytelling is considered first as a
method that improves the transmission of information and learner's
interest when planning edutainment contents. In this study, we
designed edutainment contents in the form of an adventure game that
applies the storytelling method. This content provides questions and
items constituted dynamically and reorganized learning contents
through analysis of test results. It allows learners to solve various
questions through effective iterative learning. As a result, the learners
can reach mastery learning.
Abstract: Patients under health treatments that involve long
stays at a hospital or health center (e.g. cancer, organ transplants and
severe burns), tend to get bored or depressed because of the lack of
social interaction with family and friends. Such a situation also
affects the evolution and effectiveness of their treatments. In many
cases, the solution to this problem involves extra challenges, since
many patients need to rest quietly (or remain in bed) to their being
contagious. Considering the weak health condition in which usually
are these kinds, keeping them motivated and quiet represents an
important challenge for nurses and caregivers. This article presents a
mobile ubiquitous game called MagicRace, which allows hospitalized
kinds to interact socially with one another without putting to risk
their sensitive health conditions. The game does not require a
communication infrastructure at the hospital, but instead, it uses a
mobile ad hoc network composed of the handheld devices used by
the kids to play. The usability and performance of this application
was tested in two different sessions. The preliminary results show
that users experienced positive feelings from this experience.
Abstract: This paper proposes a novel e-learning model that is
based on a dynamic formative evaluation. On evaluating the existing
format of e-learning, conditions regarding repetitive learning to
achieve mastery, causes issues for learners to lose tension and become
neglectful of learning. The dynamic formative evaluation proposed is
able to supplement limitation of the existing approaches. Since a
repetitive learning method does not provide a perfect feedback, this
paper puts an emphasis on the dynamic formative evaluation that is
able to maximize learning achievement. Through the dynamic
formative evaluation, the instructor is able to refer to the evaluation
result when making an estimation about the learner. To show the flow
chart of learning, based on the dynamic formative evaluation, the
model proves its effectiveness and validity.
Abstract: The main aim of the current work is to examine if 14N
is candidate to be clusterized nuclei or not. In order to check this
attendance, we have measured the angular distributions for 14N ion
beam elastically scattered on 12C target nuclei at different low
energies; 17.5, 21, and 24.5MeV which are close to the Coulomb
barrier energy for 14N+12C nuclear system. Study of various transfer
reactions could provide us with useful information about the
attendance of nuclei to be in a composite form (core + valence). The
experimental data were analyzed using two approaches;
Phenomenological (Optical Potential) and semi-microscopic (Double
Folding Potential). The agreement between the experimental data and
the theoretical predictions is fairly good in the whole angular range.
Abstract: Several meteorological parameters were used for the
prediction of monthly average daily global solar radiation on
horizontal using recurrent neural networks (RNNs). Climatological
data and measures, mainly air temperature, humidity, sunshine
duration, and wind speed between 1995 and 2007 were used to design
and validate a feed forward and recurrent neural network based
prediction systems. In this paper we present our reference system
based on a feed-forward multilayer perceptron (MLP) as well as the
proposed approach based on an RNN model. The obtained results
were promising and comparable to those obtained by other existing
empirical and neural models. The experimental results showed the
advantage of RNNs over simple MLPs when we deal with time series
solar radiation predictions based on daily climatological data.
Abstract: Industries using conventional fossil fuels have an
interest in better understanding the mechanism of particulate
formation during combustion since such is responsible for emission
of undesired inorganic elements that directly impact the atmospheric
pollution level. Fine and ultrafine particulates have tendency to
escape the flue gas cleaning devices to the atmosphere. They also
preferentially collect on surfaces in power systems resulting in
ascending in corrosion inclination, descending in the heat transfer
thermal unit, and severe impact on human health. This adverseness
manifests particularly in the regions of world where coal is the
dominated source of energy for consumption.
This study highlights the behavior of calcium transformation as
mineral grains verses organically associated inorganic components
during pulverized coal combustion. The influence of existing type of
calcium on the coarse, fine and ultrafine mode formation mechanisms
is also presented. The impact of two sub-bituminous coals on particle
size and calcium composition evolution during combustion is to be
assessed. Three mixed blends named Blends 1, 2, and 3 are selected
according to the ration of coal A to coal B by weight. Calcium
percentage in original coal increases as going from Blend 1 to 3.
A mathematical model and a new approach of describing
constituent distribution are proposed. Analysis of experiments of
calcium distribution in ash is also modeled using Poisson distribution.
A novel parameter, called elemental index λ, is introduced as a
measuring factor of element distribution.
Results show that calcium in ash that originally in coal as mineral
grains has index of 17, whereas organically associated calcium
transformed to fly ash shown to be best described when elemental
index λ is 7.
As an alkaline-earth element, calcium is considered the
fundamental element responsible for boiler deficiency since it is the
major player in the mechanism of ash slagging process. The
mechanism of particle size distribution and mineral species of ash
particles are presented using CCSEM and size-segregated ash
characteristics. Conclusions are drawn from the analysis of
pulverized coal ash generated from a utility-scale boiler.
Abstract: In this work, a method of time delay estimation for
dual-channel acoustic signals (speech, music, etc.) recorded under
reverberant conditions is investigated. Standard methods based on
cross-correlation of the signals show poor results in cases involving
strong reverberation, large distances between microphones and
asynchronous recordings. Under similar conditions, a method based
on cross-correlation of temporal envelopes of the signals delivers a
delay estimation of acceptable quality. This method and its properties
are described and investigated in detail, including its limits of
applicability. The method’s optimal parameter estimation and a
comparison with other known methods of time delay estimation are
also provided.
Abstract: Urban road dust comprises of a range of potentially
toxic metal elements and plays a critical role in degrading urban
receiving water quality. Hence, assessing the metal composition and
concentration in urban road dust is a high priority. This study
investigated the variability of metal composition and concentrations
in road dust in 4 different urban land uses in Gold Coast, Australia.
Samples from 16 road sites were collected and tested for selected 12
metal species. The data set was analyzed using both univariate and
multivariate techniques. Outcomes of the data analysis revealed that
the metal concentrations inroad dust differs considerably within and
between different land uses. Iron, aluminum, magnesium and zinc are
the most abundant in urban land uses. It was also noted that metal
species such as titanium, nickel, copper and zinc have the highest
concentrations in industrial land use. The study outcomes revealed
that soil and traffic related sources as key sources of metals deposited
on road surfaces.
Abstract: In today’s business environment, companies should
make strategic decisions to gain sustainable competitive advantage.
Order selection is a crucial issue among these decisions especially for
steel production industry. When the companies allocate a high
proportion of their design and production capacities to their ongoing
projects, determining which customer order should be chosen among
the potential orders without exceeding the remaining capacity is the
major critical problem. In this study, it is aimed to identify and
prioritize the evaluation factors for the customer order selection
problem. Conjoint Analysis is used to examine the importance level
of each factor which is determined as the potential profit rate per unit
of time, the compatibility of potential order with available capacity,
the level of potential future order with higher profit, customer credit
of future business opportunity, and the negotiability level of
production schedule for the order.
Abstract: Waste of certain process can be the input source of
other sectors in order to reduce environmental pollution. Today there
are more and more solid wastes are generated, but only very small
amount of those are recycled. So, the threatening of environmental
pressure to public health is very serious. The methods considered for
the treatment of solid waste are biogas tanks or processing to make
animal feed and fertilizer, however, they did not perform well. An
alternative approach is growing mushrooms on waste residues. This
is regarded as an environmental friendly solution with potential
economical benefit. The substrate producers do their best to produce
quality substrate at low cost. Apart from other methods, this can be
achieved by employing biologically degradable wastes used as the
resource material component of the substrate. Mushroom growing is
a significant tool for the restoration, replenishment and remediation
of Earth’s overburdened ecosphere. One of the rational methods of
waste utilization involves locally available wastes. The present study
aims to find out the yield of mushroom grown on locally available
waste for free and to conserve our environment by recycling wastes.
Abstract: In this paper, a numerical algorithm using a coupled Galerkin-Differential Quadrature (DQ) method is proposed for the solution of dam-reservoir interaction problem. The governing differential equation of motion of the dam structure is discretized by the Galerkin method and the DQM is used to discretize the fluid domain. The resulting systems of ordinary differential equations are then solved by the Newmark time integration scheme. The mixed scheme combines the simplicity of the Galerkin method and high accuracy and efficiency of the DQ method. Its accuracy and efficiency are demonstrated by comparing the calculated results with those of the existing literature. It is shown that highly accurate results can be obtained using a small number of Galerkin terms and DQM sampling points. The technique presented in this investigation is general and can be used to solve various fluid-structure interaction problems.
Abstract: This paper explains the results of an investigation on the analysis of flush end plate steel connections by means of finite element method. Flush end plates are a highly indeterminate type of connection, which have a number of parameters that affect their behavior. Because of this, experimental investigations are complicated and very costly. Today, the finite element method provides an ideal method for analyzing complicated structures. Finite element models of these types of connections under monotonic loading have previously been investigated. A numerical model, which can predict the cyclic behavior of these connections, is of critical importance, as dynamic experiments are more costly. This paper summarizes a study to develop a three-dimensional finite element model that can accurately capture the cyclic behavior of flush end plate connections. Comparisons between FEM results and experimental results obtained from full-scale tests have been carried out, which confirms the accuracy of the finite element model. Consequently, design equations for this connection have been investigated and it is shown that these predictions are not precise in all cases. The effect of end plate thickness and bolt diameter on the overall behavior of this connection is discussed. This research demonstrates that using the appropriate configuration, this connection has the potential to form a plastic hinge in the beam--desirable in seismic behavior.
Abstract: Dynamic systems, which in mathematical point of view are those governed by differential equations, are much more difficult to study and to predict their behavior in comparison with static systems which are governed by algebraic equations. Economical systems such as market are among complicated dynamic systems. This paper tries to adopt a very simple mathematical model for market and to study effect of supply and demand function on behavior of the market while the supply side experiences a lag due to production restrictions.
Abstract: The Proton Exchange Membranes (PEM) are largely studied because they operate at low temperatures and they are suitable for mobile applications. However, there are some deficiencies in their operation, mainly those that use ethanol as a hydrogen source, that require a certain attention. Therefore, this research aimed to develop Nafion® composite membranes, mixing clay minerals, kaolin and halloysite to the polymer matrix in order to improve the ethanol molecule retentions and, at the same time, to keep the system’s protonic conductivity. The modified Nafion/Kaolin, Nafion/Halloysite composite membranes were prepared in weight proportion of 0.5, 1.0 and 1.5. The membranes obtained were characterized as to their ethanol permeability, protonic conductivity and water absorption. The composite morphology and structure are characterized by SEM and EDX and the thermal behavior is determined by TGA and DSC. The analysis of the results shows ethanol permeability reduction from 48% to 63%. However, the protonic conductivity results are lower in relation to pure Nafion®. As to the thermal behavior, the Nafion® composite membranes were stable up to a temperature of 325ºC.
Abstract: Climate considerations are essential dimensions in the assessment of thermal comfort and indoor environments inside Egyptian housing. The primary aim of this paper is to analyze the indoor environment of new housing in the new city of Assiut in the Southern Upper Egypt zone, in order to evaluate its thermal environment and determine the acceptable indoor operative temperatures. The psychrometric charts for ASHRAE Standard 55 and ACS used in this study would facilitate an overall representation of the climate in one of the hottest months in the summer season. This study helps to understand and deal with this problem and work on a passive cooling ventilation strategy in these contexts in future studies. The results that demonstrated the indoor temperature is too high, ranges between 31°C to 40°C in different natural ventilation strategies. This causes the indoor environment to be far from the optimum comfort operative temperature of ACS except when using air conditioners. Finally, this study is considered a base for developing a new system using natural ventilation with passive cooling strategies.
Abstract: Pioneer networked systems assume that connections are reliable, and a faulty operation will be considered in case of losing a connection. Transient connections are typical of mobile devices. Areas of application of data sharing system such as these, lead to the conclusion that network connections may not always be reliable, and that the conventional approaches can be improved. Nigerian commercial banking industry is a critical system whose operation is increasingly becoming dependent on information technology (IT) driven information system. The proposed solution to this problem makes use of a hierarchically clustered network structure which we selected to reflect (as much as possible) the typical organizational structure of the Nigerian commercial banks. Representative transactions such as data updates and replication of the results of such updates were used to simulate the proposed model to show its applicability.
Abstract: We present in this work the performances of a mobile omnidirectional robot through evaluating its management of the redundancy of actuation. Thus we come to the predictive control implemented.
The distribution of the wringer on the robot actions, through the inverse pseudo of Moore-Penrose, corresponds to a « geometric ›› distribution of efforts. We will show that the load on vehicle wheels would not be equi-distributed in terms of wheels configuration and of robot movement.
Thus, the threshold of sliding is not the same for the three wheels of the vehicle. We suggest exploiting the redundancy of actuation to reduce the risk of wheels sliding and to ameliorate, thereby, its accuracy of displacement. This kind of approach was the subject of study for the legged robots.