Abstract: Rapid prototyping is a new group of manufacturing
processes, which allows fabrication of physical of any complexity
using a layer by layer deposition technique directly from a computer
system. The rapid prototyping process greatly reduces the time and
cost necessary to bring a new product to market. The prototypes
made by these systems are used in a range of industrial application
including design evaluation, verification, testing, and as patterns for
casting processes. These processes employ a variety of materials and
mechanisms to build up the layers to build the part. The present work
was to build a FDM prototyping machine that could control the X-Y
motion and material deposition, to generate two-dimensional and
three-dimensional complex shapes. This study focused on the
deposition of wax material. This work was to find out the properties
of the wax materials used in this work in order to enable better
control of the FDM process. This study will look at the integration of
a computer controlled electro-mechanical system with the traditional
FDM additive prototyping process. The characteristics of the wax
were also analysed in order to optimise the model production process.
These included wax phase change temperature, wax viscosity and
wax droplet shape during processing.
Abstract: The ferrites ZnFe2O4, CdFe2O4 and CuFe2O4 are
synthesized in laboratory conditions using ceramic technology. Their
homogeneity and structure are proven by X-Ray diffraction analysis
and Mössbauer spectroscopy. The synthesized ferrites are subjected
to strong acid and high temperature leaching with solutions of H2SO4,
HCl and HNO3. The results indicate that the highest degree of
leaching of Zn, Cd and Cu from the ferrites is achieved by use of
HCl. The charging of five zinc sulfide concentrates was optimized using
the criterion of minimal amount of zinc ferrite produced when
roasting the concentrates in a fluidized bed. The results obtained are
interpreted in terms of the hydrometallurgical zinc production and
maximum recovery of zinc, copper and cadmium from initial zinc
concentrates after their roasting.
Abstract: The activation volume of 6082T6 aluminum is
investigated at different temperatures for grain size variants. The
deformation activation volume was computed on the basis of the
relationship between the Boltzmann’s constant k, the testing
temperatures, the material strain rate sensitivity and the material yield
stress grain size variants. The material strain rate sensitivity is
computed as a function of yield stress and strain rate grain size
variants. The effect of the material strain rate sensitivity and the
deformation activation volume of 6082T6 aluminum at different
temperatures of 3-D grain are discussed. It is shown that the strain rate sensitivities and activation volume
are negative for the grain size variants during the deformation of
nanostructured materials. It is also observed that the activation
volume vary in different ways with the equivalent radius, semi minor
axis radius, semi major axis radius and major axis radius. From the
obtained results it is shown that the variation of activation volume
increase and decrease with the testing temperature. It was revealed
that, increase in strain rate sensitivity led to decrease in activation
volume whereas increase in activation volume led to decrease in
strain rate sensitivity.
Abstract: Friction stir welding and tungsten inert gas welding
techniques were employed to weld armor grade aluminum alloy to
investigate the effect of welding processes on tensile behavior of
weld joints. Tensile tests, Vicker microhardness tests and optical
microscopy were performed on developed weld joints and base metal.
Welding process influenced tensile behavior and microstructure of
weld joints. Friction stir welded joints showed tensile behavior better
than tungsten inert gas weld joints.
Abstract: This paper presents the influence of the vertical
seismic component on the non-linear dynamics analysis of three
different structures. The subject structures were analyzed and
designed according to recent codes. This paper considers three types
of buildings: 5-, 10-, and 15-story buildings. The non-linear
dynamics analysis of the structures with assuming elastic-perfectlyplastic
behavior was performed using RAM PERFORM-3D software;
the horizontal component was taken into consideration with and
without the incorporation of the corresponding vertical component.
Dynamic responses obtained for the horizontal component acting
alone were compared with those obtained from the simultaneous
application of both seismic components. The results show that the
effect of the vertical component of ground motion may increase the
axial load significantly in the interior columns and, consequently, the
stories. The plastic mechanisms would be changed. The P-Delta
effect is expected to increase. The punching base plate shear of the
columns should be considered. Moreover, the vertical component
increases the input energy when the structures exhibit inelastic
behavior and are taller.
Abstract: With the increasing population and intensive land use,
huge traffic demand is generating worldwide both in developing and
developed countries. As a developing country, Bangladesh is also
facing the same problem in recent years by producing huge numbers
of daily trips. As a matter of fact, extensive traffic demand is
increasing day by day. Also, transport system in Dhaka is
heterogeneous, reflecting the heterogeneity in the socio-economic
and land use patterns. Trips produced here are for different purposes
such as work, business, educational etc. Due to the significant
concentration of educational institutions a large share of the trips are
generated by educational purpose. And one of the major percentages
of educational trips is produced by university going students and
most of them are travelled by car, bus, train, taxi, rickshaw etc. The
aim of the study was to find out the university students’ perception on
public transit ridership. A survey was conducted among 330 students
from eight different universities. It was found out that 26% of the
trips produced by university going students are travelled by public
bus service and only 5% are by train. Percentage of car share is 16%
and 12% of the trips are travelled by private taxi. It has been
observed from the study, students those who prefer bus instead of
other options, 42 percent of their family resides outside Dhaka. And
those who prefer walking, of them, over 40 percent students’ family
reside outside of Dhaka and of them over 85 percent students have a
tendency to live in a mess. On the contrary, students travelling by car
represents, most of their family reside in Dhaka. The study also
revealed that the most important reason that restricts students not to
use public transit is poor service. Negative attitudes such as
discomfort, uneasiness in using public transit also reduces the usage
of public transit. The poor waiting area is another major cause of not
using public transit. Insufficient security also plays a significant role
in not using public transit. On the contrary, the fare is not a problem
for students those who use public transit as a mode of transportation.
Students also think stations are not far away from their home or
institution and they do not need to wait long for the buses or trains. It
was also found accessibility to public transit is moderate.
Abstract: The market competition is moving from the single
firm to the whole supply chain because of increasing competition and
growing need for operational efficiencies and customer orientation.
Supply chain management allows companies to look beyond their
organizational boundaries to develop and leverage resources and
capabilities of their supply chain partners. This creates competitive
advantages in the marketplace and because of this SCM has acquired
strategic importance. Lean Approach is a management strategy that focuses on reducing
every type of waste present in an organization. This approach is
becoming more and more popular among supply chain managers. The supply chain application of lean approach is not frequent. In
particular, it is not well studied which are the impacts of lean
approach principles in a supply chain context. In literature there are
only few studies aimed at understanding the qualitative impact of the
lean approach in supply chains. Therefore, the goal of this research
work is to study the impacts of lean principles implementation along
a supply chain. To achieve this, a simulation model of a threeechelon
multi-product supply chain has been built. Kanban system (and several priority policies) and setup time
reduction degrees are implemented in the lean-configured supply
chain to apply pull and lot-sizing decrease principles respectively. To
evaluate the benefits of lean approach, lean supply chain is compared
with an EOQ-configured supply chain. The simulation results show
that Kanban system and setup-time reduction improve inventory
stock level. They also show that logistics efforts are affected to lean
implementation degree. The paper concludes describing
performances of lean supply chain in different contexts.
Abstract: Objectives: To determine the nutritional status and
risk factors associated with women practicing geophagia in QwaQwa,
South Africa. Materials and Methods: An observational epidemiological study
design was adopted which included an exposed (geophagia) and nonexposed
(control) group. A food frequency questionnaire, anthropometric measurements and blood sampling were applied to
determine nutritional status of participants. Logistic regression
analysis was performed in order to identify factors that were likely to
be associated with the practice of geophagia. Results: The mean total energy intake for the geophagia group (G)
and control group (C) were 10324.31 ± 2755.00 kJ and 10763.94 ±
2556.30 kJ respectively. Both groups fell within the overweight
category according to the mean Body Mass Index (BMI) of each
group (G= 25.59 kg/m2; C= 25.14 kg/m2). The mean serum iron
levels of the geophagia group (6.929 μmol/l) were significantly lower
than that of the control group (13.75 μmol/l) (p = 0.000). Serum
transferrin (G=3.23g/l; C=2.7054g/l) and serum transferrin saturation
(G=8.05%; C=18.74%) levels also differed significantly between
groups (p=0.00). Factors that were associated with the practice of
geophagia included haemoglobin (Odds ratio (OR):14.50), serumiron
(OR: 9.80), serum-ferritin (OR: 3.75), serum-transferrin (OR:
6.92) and transferrin saturation (OR: 14.50). A significant negative
association (p=0.014) was found between women who were wageearners
and those who were not wage-earners and the practice of
geophagia (OR: 0.143; CI: 0.027; 0.755). These findings seem to
indicate that a permanent income may decrease the likelihood of
practising geophagia. Key Findings: Geophagia was confirmed to be a risk factor for
iron deficiency in this community. The significantly strong
association between geophagia and iron deficiency emphasizes the
importance of identifying the practice of geophagia in women,
especially during their child bearing years.
Abstract: Zinc borate is an important inorganic hydrate borate
material, which can be used as a flame retardant agent and corrosion
resistance material. This compound can loss its structural water
content at higher than 290°C. Due to thermal stability; Zinc Borate
can be used as flame retardant at high temperature process of plastic
and gum. In this study, the ultrasonic reaction of zinc borates were
studied using hydrozincite (Zn5(CO3)2·(OH)6) and boric acid
(H3BO3) raw materials. Before the synthesis raw materials were
characterized by X-Ray Diffraction (XRD) and Fourier Transform
Infrared Spectroscopy (FT-IR). Ultrasonic method is a new
application on the zinc borate synthesis. The synthesis parameters
were set to 90°C reaction temperature and 55 minutes of reaction
time, with 1:1, 1:2, 1:3, 1:4 and 1:5 molar ratio of starting materials
(Zn5(CO3)2·(OH)6 : H3BO3). After the zinc borate synthesis, the
products were analyzed by XRD and FT-IR. As a result, optimum
molar ratio of 1:5 is determined for the synthesis of zinc borates with
ultrasonic method.
Abstract: The effects of wood ash from five common tropical
woods on the ignition point of four common tropical woods in
Nigeria were investigated. The ash and moisture contents of the wood
sawdust from Mahogany (Khaya ivorensis), Opepe (Sarcocephalus
latifolius), Abura (Mitragyna ciliata), Rubber (Heavea brasilensis)
and Poroporo (Sorghum bicolour) used, were determined using a
furnace (Vecstar furnaces, model ECF2, serial no. f3077) and oven
(Genlab laboratory oven, model MINO/040) respectively. The metal
contents of the five wood sawdust ash samples were determined
using a Perkin Elmer optima 3000 dv atomic absorption spectrometer
while the ignition points were determined using Vecstar furnaces
model ECF2. Poroporo had the highest ash content, 2.263g while
rubber had the least, 0.710g. The results for the moisture content
range from 2.971g to 0.903g. Magnesium metal had the highest
concentration of all the metals, in all the wood ash samples; with
mahogany ash having the highest concentration, 9.196ppm while
rubber ash had the least concentration of magnesium metal, 2.196
ppm. The ignition point results showed that the wood ashes from
mahogany and opepe increased the ignition points of the test wood
samples, Danta (Nesogordonia papaverifera), Ekpaya, Akomu
(Pycnanthus angolensis) and Oleku when coated on them while the
ashes from poroporo, rubber and abura decreased the ignition points
of the test wood samples when coated on them. However, Opepe saw
dust ash decreased the ignition point in one of the test wood samples,
suggesting that the metal content of the test wood sample was more
than that of the Opepe saw dust ash. Therefore, Mahogany and Opepe
saw dust ashes could be used in the surface treatment of wood to
enhance their fire resistance or retardancy. However, the caution to
be exercised in this application is that the metal content of the test
wood samples should be evaluated as well.
Abstract: The aim of this study is to examine the relationship
between organizational commitment which is defined as a strong
belief in and acceptance of the organization’s goals and values, and
burnout syndrome and organizational cynicism. Accordingly, a field
research based on survey method was conducted on the employees of
a health institution operating in the province of Konya. The findings
of the research show that there is a positive statistically significant
relationship between organizational cynicism and burnout while
there is a negative statistically significant relationship between
organizational commitment and burnout. Furthermore, it has been
also realized that there is a negative and statistically significant
relationship between organizational commitment and organizational
cynicism.
Abstract: This study and the field test comparisons were carried
out on the Algerian Derguna – Setif transmission systems. The
transmission line of normal voltage 225 kV is 65 km long,
transported and uses twin bundle conductors protected with two
shield wires of transposed galvanized steel. An iterative finite-element method is used to solve Poisons
equation. Two algorithms are proposed for satisfying the current
continuity condition and updating the space-charge density. A new approach to the problem of corona discharge in
transmission system has been described in this paper. The effect of
varying the configurations and wires number is also investigated. The
analysis of this steady is important in the design of HVDC
transmission lines. The potential and electric field have been
calculating in locations singular points of the system.
Abstract: An industrial system for the production of white
liquor of a paper industry, Klabin Paraná Papéis, formed by ten
reactors was modeled, simulated, and analyzed. The developed model
considered possible water losses by evaporation and reaction, in
addition to variations in volumetric flow of lime mud across the
reactors due to composition variations. The model predictions agreed
well with the process measurements at the plant and the results
showed that the slaking reaction is nearly complete at the third
causticizing reactor, while causticizing ends by the seventh reactor.
Water loss due to slaking reaction and evaporation occurs more
pronouncedly in the slaking reaction than in the final causticizing
reactors; nevertheless, the lime mud flow remains nearly constant
across the reactors.
Abstract: This article presents an alternative collapse capacity
intensity measure in the three elements form which is influenced by
the spectral ordinates at periods longer than that of the first mode
period at near and far source sites. A parameter, denoted by β, is
defined by which the spectral ordinate effects, up to the effective
period (2T1), on the intensity measure are taken into account. The
methodology permits to meet the hazard-levelled target extreme
event in the probabilistic and deterministic forms. A MATLAB code
is developed involving OpenSees to calculate the collapse capacities
of the 8 archetype RC structures having 2 to 20 stories for regression
process. The incremental dynamic analysis (IDA) method is used to
calculate the structure’s collapse values accounting for the element
stiffness and strength deterioration. The general near field set
presented by FEMA is used in a series of performing nonlinear
analyses. 8 linear relationships are developed for the 8structutres
leading to the correlation coefficient up to 0.93. A collapse capacity
near field prediction equation is developed taking into account the
results of regression processes obtained from the 8 structures. The
proposed prediction equation is validated against a set of actual near
field records leading to a good agreement. Implementation of the
proposed equation to the four archetype RC structures demonstrated
different collapse capacities at near field site compared to those of
FEMA. The reasons of differences are believed to be due to
accounting for the spectral shape effects.
Abstract: In this study, it has been studied to determine the
relationship between business performance and strategic flexibility,
which is defined to be the strategic choice that provides the ability of
rapidly responding the changes of the dynamic environment of the
companies, for having competitive advantages. In this context a field
study has been conducted over 56 companies, which are active in
informatics and electronics sectors in TEKNOKENT. As a result of
the study it has been determined that; strategic flexibility has an
effect on business performance and there is a positive and
statistically significant relationship between strategic flexibility and
business performance.
Abstract: Lyophilization, also called freeze-drying, is an
important dehydration technique mainly used for pharmaceuticals.
Food industry also uses lyophilization when it is important to retain
most of the nutritional quality, taste, shape and size of dried products
and to extend their shelf life. Vacuum-Induced during freezing cycle
(VI) has been used in order to control ice nucleation and,
consequently, to reduce the time of primary drying cycle of
pharmaceuticals preserving quality properties of the final product.
This procedure has not been applied in freeze drying of foods. The
present work aims to investigate the effect of VI on the lyophilization
drying time, final moisture content, density and reconstitutional
properties of mango (Mangifera indica L.) slices (MS) and mango
pulp-maltodextrin dispersions (MPM) (30% concentration of total
solids). Control samples were run at each freezing rate without using
induced vacuum. The lyophilization endpoint was the same for all
treatments (constant difference between capacitance and Pirani
vacuum gauges). From the experimental results it can be concluded
that at the high freezing rate (0.4°C/min) reduced the overall process
time up to 30% comparing process time required for the control and
VI of the lower freeze rate (0.1°C/min) without affecting the quality
characteristics of the dried product, which yields a reduction in costs
and energy consumption for MS and MPM freeze drying. Controls
and samples treated with VI at freezing rate of 0.4°C/min in MS
showed similar results in moisture and density parameters.
Furthermore, results from MPM dispersion showed favorable values
when VI was applied because dried product with low moisture
content and low density was obtained at shorter process time
compared with the control. There were not found significant
differences between reconstitutional properties (rehydration for MS
and solubility for MPM) of freeze dried mango resulting from
controls, and VI treatments.
Abstract: The Radio Frequency Identification (RFID) technology
has a diverse base of applications, but it is also prone to security
threats. There are different types of security attacks which limit the
range of the RFID applications. For example, deploying the RFID
networks in insecure environments could make the RFID system
vulnerable to many types of attacks such as spoofing attack, location
traceability attack, physical attack and many more. Therefore, security
is often an important requirement for RFID systems. In this paper,
RFID mutual authentication protocol is implemented based on mobile
agent technology and timestamp, which are used to provide strong
authentication and integrity assurances to both the RFID readers and
their corresponding RFID tags. The integration of mobile agent
technology and timestamp provides promising results towards
achieving this goal and towards reducing the security threats in RFID
systems.
Abstract: In the present study we have investigated axial
buckling characteristics of nanocomposite beams reinforced by
single-walled carbon nanotubes (SWCNTs). Various types of beam
theories including Euler-Bernoulli beam theory, Timoshenko beam
theory and Reddy beam theory were used to analyze the buckling
behavior of carbon nanotube-reinforced composite beams.
Generalized differential quadrature (GDQ) method was utilized to
discretize the governing differential equations along with four
commonly used boundary conditions. The material properties of the
nanocomposite beams were obtained using molecular dynamic (MD)
simulation corresponding to both short-(10,10) SWCNT and long-
(10,10) SWCNT composites which were embedded by amorphous
polyethylene matrix. Then the results obtained directly from MD
simulations were matched with those calculated by the mixture rule
to extract appropriate values of carbon nanotube efficiency
parameters accounting for the scale-dependent material properties.
The selected numerical results were presented to indicate the
influences of nanotube volume fractions and end supports on the
critical axial buckling loads of nanocomposite beams relevant to
long- and short-nanotube composites.
Abstract: Clustering is a process of grouping objects and data
into groups of clusters to ensure that data objects from the same
cluster are identical to each other. Clustering algorithms in one of the
area in data mining and it can be classified into partition, hierarchical,
density based and grid based. Therefore, in this paper we do survey
and review four major hierarchical clustering algorithms called
CURE, ROCK, CHAMELEON and BIRCH. The obtained state of
the art of these algorithms will help in eliminating the current
problems as well as deriving more robust and scalable algorithms for
clustering.
Abstract: An analytical 4-DOF nonlinear model of a de Laval
rotor-stator system based on Energy Principles has been used
theoretically and experimentally to investigate fault symptoms in a
rotating system. The faults, namely rotor-stator-rub, crack and
unbalance are modeled as excitations on the rotor shaft. Mayes
steering function is used to simulate the breathing behaviour of the
crack. The fault analysis technique is based on waveform signal,
orbits and Fast Fourier Transform (FFT) derived from simulated and
real measured signals. Simulated and experimental results manifest
considerable mutual resemblance of elliptic-shaped orbits and FFT
for a same range of test data.