Abstract: Starting in 2020, an EU-wide CO2-limitation of
95 g/km is scheduled for the average of an OEMs passenger car fleet.
Taking that into consideration additional improvement measures of
the Diesel cycle are necessary in order to reduce fuel consumption
and emissions while boosting, or at the least, keeping performance
values at the same time.
The present article deals with the possibilities of an optimized
air/water charge air cooler, also called iCAC (indirect Charge Air
Cooler) for a Diesel passenger car amongst extreme-boundary
conditions. In this context, the precise objective was to show the
impact of improved intercooling with reference to the engine working
process (fuel consumption and NOx-emissions). Several extremeboundaries
- e.g. varying ambient temperatures or mountainous
routes - that will become very important in the near future regarding
RDE (Real Driving emissions) were subject of the investigation.
With the introduction of RDE in 2017 (EU6c measure), the
controversial NEDC (New European Driving Cycle) will belong to
the past and the OEMs will have to avoid harmful emissions in any
conceivable real life situation.
This is certainly going to lead to optimization-measurements at the
powertrain, which again is going to make the implementation of
iCACs, presently solely used for the premium class, more and more
attractive for compact class cars. The investigations showed a benefit
in FC between 1 and 3% for the iCAC in real world conditions.
Abstract: Water spray cooling is a technique typically used in
heat treatment and other metallurgical processes where controlled
temperature regimes are required. Water spray cooling is used in
static (without movement) or dynamic (with movement of the steel
plate) regimes. The static regime is notable for the fixed position of
the hot steel plate and fixed spray nozzle. This regime is typical for
quenching systems focused on heat treatment of the steel plate. The
second application of spray cooling is the dynamic regime. The
dynamic regime is notable for its static section cooling system and
moving steel plate. This regime is used in rolling and finishing mills.
The fixed position of cooling sections with nozzles and the
movement of the steel plate produce nonhomogeneous water
distribution on the steel plate. The length of cooling sections and
placement of water nozzles in combination with the nonhomogeneity
of water distribution lead to discontinued or interrupted cooling
conditions. The impact of static and dynamic regimes on cooling
intensity and the heat transfer coefficient during the cooling process
of steel plates is an important issue.
Heat treatment of steel is accompanied by oxide scale growth. The
oxide scale layers can significantly modify the cooling properties and
intensity during the cooling. The combination of static and dynamic
(section) regimes with the variable thickness of the oxide scale layer
on the steel surface impact the final cooling intensity. The study of
the influence of the oxide scale layers with different cooling regimes
was carried out using experimental measurements and numerical
analysis. The experimental measurements compared both types of
cooling regimes and the cooling of scale-free surfaces and oxidized
surfaces. A numerical analysis was prepared to simulate the cooling
process with different conditions of the section and samples with
different oxide scale layers.
Abstract: Particles exhausted from cars have adverse impacts on
human health. The study developed a three-dimensional particle
dispersion numerical model including particle coagulation to simulate
the particle concentration distribution under idling conditions in a
residential underground garage. The simulation results demonstrate
that particle disperses much faster in the vertical direction than that in
horizontal direction. The enhancement of particle dispersion in the
vertical direction due to the increase of cars with engine running is
much stronger than that in the car exhaust direction. Particle dispersion
from each pair of adjacent cars has little influence on each other in the
study. Average particle concentration after 120 seconds exhaust is
1.8-4.5 times higher than the initial total particles at ambient
environment. Particle pollution in the residential underground garage
is severe.
Abstract: Carbon fiber reinforced polymersarewidely used to strengthen steel structural elements. These structural elements are normally subjected to static, dynamic and fatigue loadings during their life-time. CFRP laminate is commonly used to strengthen these structures under the subjected loads. A number of studies have focused on the characteristics of CFRP sheets bonded to steel members under static, dynamic and fatigue loadings. However, there is a gap in understanding the bonding behavior between CFRP laminates and steel members under impact loading. This paper shows the effect of high load rates on this bond. CFRP laminate CFK 150/2000 was used to strengthen steel joints using Araldite 420 epoxy. The results show that applying a high load rate significantly affects the bond strength but has little influence on the effective bond length.
Abstract: Developing young people’s employability is a key
policy issue for ensuring their successful transition to the labour
market and their access to career oriented employment. The youths of
today irrespective of their gender need to acquire the knowledge,
skills and attitudes that will enable them to create or find jobs as well
as cope with unpredictable labour market changes throughout their
working lives. In a study carried out to determine the influence of
gender on job-competencies requirements of chemical-based
industries and undergraduate-competencies acquisition by chemists
working in the industries, all chemistry graduates working in twenty
(20) chemical-based industries that were randomly selected from six
sectors of chemical-based industries in Lagos and Ogun States of
Nigeria were administered with Job-competencies required and
undergraduate-competencies acquired assessment questionnaire. The
data were analysed using means and independent sample t-test. The
findings revealed that the population of female chemists working in
chemical-based industries is low compared with the number of male
chemists; furthermore, job-competencies requirements are found not
to be gender biased while there is no significant difference in
undergraduate-competencies acquisition of male and female
chemists. This suggests that females should be given the same
opportunity of employment in chemical-based industries as their male
counterparts. The study also revealed the level of acquisition of
undergraduate competencies as related to the needs of chemicalbased
industries.
Abstract: Geopolymer concretes are new class of construction
materials that have emerged as an alternative to Ordinary Portland
cement concrete. Considerable researches have been carried out on
material development of geopolymer concrete; however, a few studies
have been reported on the structural use of them. This paper presents
the bond behaviors of reinforcement embedded in fly ash based
geopolymer concrete. The development lengths of reinforcement for
various compressive strengths of concrete, 20, 30 and 40 MPa, and
reinforcement diameters, 10, 16 and 25 mm, are investigated. Total 27
specimens were manufactured and pull-out test according to EN 10080
was applied to measure bond strength and slips between concrete and
reinforcements. The average bond strengths decreased from 23.06MPa
to 17.26 MPa, as the diameters of reinforcements increased from
10mm to 25mm. The compressive strength levels of geopolymer
concrete showed no significant influence on bond strengths in this
study. Also, the bond-slip relations between geopolymer concrete and
reinforcement are derived using non-linear regression analysis for
various experimental conditions.
Abstract: In this work, neural networks methods MLP type were
applied to a database from an array of six sensors for the detection of
three toxic gases. The choice of the number of hidden layers and the
weight values are influential on the convergence of the learning
algorithm. We proposed, in this article, a mathematical formula to
determine the optimal number of hidden layers and good weight
values based on the method of back propagation of errors. The results
of this modeling have improved discrimination of these gases and
optimized the computation time. The model presented here has
proven to be an effective application for the fast identification of
toxic gases.
Abstract: In recent years, the compression of date (Phoenix
dactylifera L.) fruit powders (DP) to obtain date tablets (DT) has
been suggested as a promising form of valorization of non
commercial valuable date fruit (DF) varieties. To further improve
and characterize DT, the present study aims to investigate the
influence of the DP particle size and compression force on some
physical properties of DT. The results show that independently of
particle size, the hardness (y) of tablets increases with the increase of
the compression force (x) following a logarithmic law (y = a ln (bx)
where a and b are the constants of model). Further, a full factorial
design (FFD) at two levels, applied to investigate the erosion %,
reveals that the effects of time and particle size are the same in
absolute value and they are beyond the effect of the compression.
Regarding the disintegration time, the obtained results also by means
of a FFD show that the effect of the compression force exceeds 4
times that of the DP particle size. As final stage, the color parameters
in the CIELab system of DT immediately after their obtaining are
differently influenced by the size of the initial powder.
Abstract: This work was one of the tasks of the
Manufacturing2Client project, whose objective was to develop a
frontal deflector to be commercialized in the automotive industry,
using new project and manufacturing methods. In this task, in
particular, it was proposed to develop the ability to predict
computationally the aerodynamic influence of flow in vehicles, in an
effort to reduce fuel consumption in vehicles from class 3 to 8. With
this aim, two deflector models were developed and their aerodynamic
performance analyzed. The aerodynamic study was done using the
Computational Fluid Dynamics (CFD) software Ansys CFX and
allowed the calculation of the drag coefficient caused by the vehicle
motion for the different configurations considered. Moreover, the
reduction of diesel consumption and carbon dioxide (CO2) emissions
associated with the optimized deflector geometry could be assessed.
Abstract: Machining parameters are very important in
determining the surface quality of any material. In the past decade,
some new engineering materials were developed for the
manufacturing industry which created a need to conduct an
investigation on the impact of the said parameters on their surface
roughness. Polyurethane (PU) block is widely used in the automotive
industry to manufacture parts such as checking fixtures that are used
to verify the dimensional accuracy of automotive parts. In this paper,
the design of experiment (DOE) was used to investigate on the effect
of the milling parameters on the PU block. Furthermore, an analysis
of the machined surface chemical composition was done using
scanning electron microscope (SEM). It was found that the surface
roughness of the PU block is severely affected when PU undergoes a
flood machining process instead of a dry condition. In addition the
stepover and the silicon content were found to be the most significant
parameters that influence the surface quality of the PU block.
Abstract: The computational fluid dynamics (CFD) study of
stirred tank with the air-water interface are carried out in the presence
of different types of the impeller and with or without baffles. A
multiple reference frame (MRF) approach with the volume of fluid
(VOF) method is used to capture the air-water interface. The RANS
(Reynolds Averaged Navier-Stokes) equations with k-ε turbulence
model are solved to predict the flow behavior of water and air phase
which are treated as a different phases. The predicted results have
shown that the VOF method is able to capture the interface in the
unbaffled tank. While, the VOF method is showing an unfeasible
results in the baffled tank with high rotational impeller speed. For
continuous stirred tank, the air-water interface is disturbed by the
inflow and the level of water is also increased with time.
Abstract: Exact solution of an unsteady flow of elastico-viscous
electrically conducting fluid through a porous media in a tube of
elliptical cross section under the influence of constant pressure
gradient and magnetic field has been obtained in this paper. Initially,
the flow is generated by a constant pressure gradient. After attaining
the steady state, the pressure gradient is suddenly withdrawn and the
resulting fluid motion in a tube of elliptical cross section by taking
into account of the transverse magnetic field and porosity factor of
the bounding surface is investigated. The problem is solved in twostages
the first stage is a steady motion in tube under the influence of
a constant pressure gradient, the second stage concern with an
unsteady motion. The problem is solved employing separation of
variables technique. The results are expressed in terms of a nondimensional
porosity parameter (K), magnetic parameter (m) and
elastico-viscosity parameter (β), which depends on the Non-
Newtonian coefficient. The flow parameters are found to be identical
with that of Newtonian case as elastic-viscosity parameter and
magnetic parameter tends to zero and porosity tends to infinity. It is
seen that the effect of elastico-viscosity parameter, magnetic
parameter and the porosity parameter of the bounding surface has
significant effect on the velocity parameter.
Abstract: Brown seaweeds are abundant in Portuguese coastline
and represent an almost unexploited marine economic resource. One
of the most common species, easily available for harvesting in the
northwest coast, is Saccorhiza polyschides grows in the lowest shore
and costal rocky reefs. It is almost exclusively used by local farmers
as natural fertilizer, but contains a substantial amount of valuable
compounds, particularly alginates, natural biopolymers of high
interest for many industrial applications.
Alginates are natural polysaccharides present in cell walls of
brown seaweed, highly biocompatible, with particular properties that
make them of high interest for the food, biotechnology, cosmetics
and pharmaceutical industries. Conventional extraction processes are
based on thermal treatment. They are lengthy and consume high
amounts of energy and solvents. In recent years, microwave-assisted
extraction (MAE) has shown enormous potential to overcome major
drawbacks that outcome from conventional plant material extraction
(thermal and/or solvent based) techniques, being also successfully
applied to the extraction of agar, fucoidans and alginates. In the
present study, acid pretreatment of brown seaweed Saccorhiza
polyschides for subsequent microwave-assisted extraction (MAE) of
alginate was optimized. Seaweeds were collected in Northwest
Portuguese coastal waters of the Atlantic Ocean between May and
August, 2014. Experimental design was used to assess the effect of
temperature and acid pretreatment time in alginate extraction.
Response surface methodology allowed the determination of the
optimum MAE conditions: 40 mL of HCl 0.1 M per g of dried
seaweed with constant stirring at 20ºC during 14h. Optimal acid
pretreatment conditions have enhanced significantly MAE of
alginates from Saccorhiza polyschides, thus contributing for the
development of a viable, more environmental friendly alternative to
conventional processes.
Abstract: Social media continues to grow, and user interfaces
may become more appealing if cultural characteristics are
incorporated into their design.
Facebook was designed in the west, and the original language was
English. Subsequently, the words in the user interface were translated
to other languages, including Arabic.
Arabic words are written from right to left, and English is written
from left to right. The translated version may misrepresent the
original design and users’ preferences may be influenced by their
culture, which should be considered in the user interface design.
Previous research indicates that users are more comfortable when
interacting with a user interface, which relates to their own culture.
Therefore, this paper, using a survey, investigates the preferences of
Saudi Arabians on the Arabic version of the user interface of
Facebook.
Abstract: The main purpose of this work was verify the
influence of the accelerated carbonation in the physical and
mechanical properties of the hybrid composites, reinforced with
micro and nanofibers and composites with microfibers. The
composites were produced by the slurry vacuum dewatering method,
followed by pressing. It was produced using two formulations: 8% of
eucalyptus pulp + 1% of the nanofibrillated cellulose and 9% of
eucalyptus pulp, both were subjected to accelerated carbonation. The
results showed that the accelerated carbonation contributed to
improve the physical and mechanical properties of the hybrid
composites and of the composites reinforced with microfibers
(eucalyptus pulp).
Abstract: We model and simulate the combined effect of fiber
dispersion and frequency chirp of a directly modulated high-speed
laser diode on the figures of merit of a non-amplified 40-Gbps optical
fiber link. We consider both the return to zero (RZ) and non-return to
zero (NRZ) patterns of the pseudorandom modulation bits. The
performance of the fiber communication system is assessed by the
fiber-length limitation due to the fiber dispersion. We study the
influence of replacing standard single-mode fibers by non-zero
dispersion-shifted fibers on the maximum fiber length and evaluate
the associated power penalty. We introduce new dispersion
tolerances for 1-dB power penalty of the RZ and NRZ 40-Gbps
optical fiber links.
Abstract: Animal fats (camel, sheep, goat, rabbit and chicken)
and vegetable oils (corn, sunflower, palm oil and olive oil) were
substituted with different proportions (1, 5, 10 and 20%) of lard.
Fatty acid composition in TG and 2-MG were determined using
lipase hydrolysis and gas chromatography before and after
adulteration. Results indicated that, genuine lard had a high
proportion (60.97%) of the total palmitic acid at 2-MG. However, it
was 8.70%, 16.40%, 11.38%, 10.57%, 29.97 and 8.97% for camel,
beef, sheep, goat, rabbit and chicken, respectively. It could be noticed
also the position-2-MG is mostly occupied by unsaturated fatty acids
among all tested fats except lard. Vegetable oils (corn, sunflower,
palm oil and olive oil) revealed that the levels of palmitic acid
esterifies at 2-MG position was 6.84, 1.43, 9.86 and 1.70%,
respectively. It could be observed also the studied oils had a higher
level of unsaturated fatty acids in the same position, compared with
animal fats under investigation. Moreover, palmitic acid esterifies at
2-MG and PAEF increased gradually as the substituted levels
increased among all tested fat and oil samples. Statistical analysis
showed that the PAEF correlated well with lard level. The detection
of lard in some commercial processed foods (5 French fries, 4 Butter
fats, 5 processed meat and 6 candy samples) was carried out. Results
revealed that 2 samples of French fries and 4 samples of processed
meat contained lard due to their higher PAEF, while butter fat and
candy were free of lard.
Abstract: Regardless of the manufacturing process used,
subtractive or additive, material, purpose and application, produced
components are conventionally solid mass with more or less complex
shape depending on the production technology selected. Aspects
such as reducing the weight of components, associated with the low
volume of material required and the almost non-existent material
waste, speed and flexibility of production and, primarily, a high
mechanical strength combined with high structural performance, are
competitive advantages in any industrial sector, from automotive,
molds, aviation, aerospace, construction, pharmaceuticals, medicine
and more recently in human tissue engineering. Such features,
properties and functionalities are attained in metal components
produced using the additive technique of Rapid Prototyping from
metal powders commonly known as Selective Laser Melting (SLM),
with optimized internal topologies and varying densities. In order to
produce components with high strength and high structural and
functional performance, regardless of the type of application, three
different internal topologies were developed and analyzed using
numerical computational tools. The developed topologies were
numerically submitted to mechanical compression and four point
bending testing. Finite Element Analysis results demonstrate how
different internal topologies can contribute to improve mechanical
properties, even with a high degree of porosity relatively to fully
dense components. Results are very promising not only from the
point of view of mechanical resistance, but especially through the
achievement of considerable variation in density without loss of
structural and functional high performance.
Abstract: This paper focuses on the dynamic behavior of
reinforced concrete (RC) slabs. Therefore, the theoretical modal
analysis was performed using two different types of boundary
conditions. Modal analysis method is the most important dynamic
analyses. The analysis would be modal case when there is no external
force on the structure. By using this method in this paper, the effects
of freely and simply supported boundary conditions on the
frequencies and mode shapes of RC square slabs are studied. ANSYS
software was employed to derive the finite element model to
determine the natural frequencies and mode shapes of the slabs.
Then, the obtained results through numerical analysis (finite element
analysis) would be compared with the exact solution. The main goal
of the research study is to predict how the boundary conditions
change the behavior of the slab structures prior to performing
experimental modal analysis. Based on the results, it is concluded
that simply support boundary condition has obvious influence to
increase the natural frequencies and change the shape of the mode
when it is compared with freely supported boundary condition of
slabs. This means that such support conditions have the direct
influence on the dynamic behavior of the slabs. Thus, it is suggested
to use free-free boundary condition in experimental modal analysis to
precisely reflect the properties of the structure. By using free-free
boundary conditions, the influence of poorly defined supports is
interrupted.
Abstract: The fuzzy composition of objects depicted in images
acquired through MR imaging or the use of bio-scanners has often
been a point of controversy for field experts attempting to effectively
delineate between the visualized objects. Modern approaches in
medical image segmentation tend to consider fuzziness as a
characteristic and inherent feature of the depicted object, instead of
an undesirable trait. In this paper, a novel technique for efficient
image retrieval in the context of images in which segmented objects
are either crisp or fuzzily bounded is presented. Moreover, the
proposed method is applied in the case of multiple, even conflicting,
segmentations from field experts. Experimental results demonstrate
the efficiency of the suggested method in retrieving similar objects
from the aforementioned categories while taking into account the
fuzzy nature of the depicted data.