Abstract: Since 1920, the industry has almost completely
changed the rivets production techniques for the manufacture of
permanent welding join production of structures and manufacture of
other products. The welding arc is the process more widely used in
industries. This is accomplished by the heat of an electric arc which
melts the base metal while the molten metal droplets are transferred
through the arc to the welding pool, protected from the atmosphere
by a gas curtain. The GMAW (Gas metal arc welding) process is
influenced by variables such as: current, polarity, welding speed,
electrode: extension, position, moving direction; type of joint,
welder's ability, among others. It is remarkable that the knowledge
and control of these variables are essential for obtaining satisfactory
quality welds, knowing that are interconnected so that changes in one
of them requiring changes in one or more of the other to produce the
desired results. The optimum values are affected by the type of base
metal, the electrode composition, the welding position and the quality
requirements. Thus, this paper proposes a new methodology, adding
the variable vibration through a mechanism developed for GMAW
welding, in order to improve the mechanical and metallurgical
properties which does not affect the ability of the welder and enables
repeatability of the welds made. For confirmation metallographic
analysis and mechanical tests were made.
Abstract: While choosing insulating oil, characteristic features
such as thermal cooling, endurance, efficiency and being
environment-friendly should be considered. Mineral oils are referred
as petroleum-based oil. In this study, vegetable oils investigated as an
alternative insulating liquid to mineral oil. Dissipation factor,
breakdown voltage, relative dielectric constant and resistivity
changes with the frequency and voltage of mineral, rapeseed and nut
oils were measured. Experimental studies were performed according
to ASTM D924 and IEC 60156 standards.
Abstract: Residential buildings consume significant amounts of
energy and produce large amount of emissions and waste. However,
there is a substantial potential for energy savings in this sector which
needs to be evaluated over the life cycle of residential buildings. Life
Cycle Assessment (LCA) methodology has been employed to study
the primary energy uses and associated environmental impacts of
different phases (i.e., product, construction, use, end of life, and
beyond building life) for residential buildings. Four different
alternatives of residential buildings in Vancouver (BC, Canada) with
a 50-year lifespan have been evaluated, including High Rise
Apartment (HRA), Low Rise Apartment (LRA), Single family
Attached House (SAH), and Single family Detached House (SDH).
Life cycle performance of the buildings is evaluated for embodied
energy, embodied environmental impacts, operational energy,
operational environmental impacts, total life-cycle energy, and total
life cycle environmental impacts. Estimation of operational energy
and LCA are performed using DesignBuilder software and Athena
Impact estimator software respectively.
The study results revealed that over the life span of the buildings,
the relationship between the energy use and the environmental
impacts are identical. LRA is found to be the best alternative in terms
of embodied energy use and embodied environmental impacts; while,
HRA showed the best life-cycle performance in terms of minimum
energy use and environmental impacts. Sensitivity analysis has also
been carried out to study the influence of building service lifespan
over 50, 75, and 100 years on the relative significance of embodied
energy and total life cycle energy. The life-cycle energy requirements
for SDH are found to be a significant component among the four
types of residential buildings. The overall disclose that the primary
operations of these buildings accounts for 90% of the total life cycle
energy which far outweighs minor differences in embodied effects
between the buildings.
Abstract: Brownfields are one of the most important problems
that must be solved by today's cities. The topic of this article is
description of developing a comprehensive transformation of postindustrial
area of the former iron factory national cultural heritage
lower Vítkovice. City of Ostrava used to be industrial superpower of
the Czechoslovak Republic, especially in the area of coal mining and
iron production, after declining industrial production and mining in
the 80s left many unused areas of former factories generally
brownfields and backfields. Since the late 90s we are observing how
the city officials or private entities seeking to remedy this situation.
Regeneration of brownfields is a very expensive and long-term
process. The area is now rebuilt for tourists and residents of the city
in the entertainment, cultural, and social center. It was necessary do
the reconstruction of the industrial monuments. Equally important
was the construction of new buildings, which helped reusing of the
entire complex. This is a unique example of transformation of
technical monuments and completion of necessary new objects, so
that the area could start working again and reintegrate back into the
urban system.
Abstract: A new fast growing trend in tourism is ecotourism, in
which tourists visit natural ecosystems under low impact, nonconsumptive
and locally oriented activities. Through these activities
species and habitats are maintained and typically, underdeveloped
regions are emphasized. Ecotourism provides a great alternative,
especially for rural and undeveloped area. At the same time, despite
its many benefits, it also poses many risks for the naturally protected
areas. If ecotourism is practiced improperly degradation and
irreversible damages could be the unwanted result. In addition, the
lack of MSc programs in the field of Ecotourism in Europe makes it a
necessity to be developed. Such an MSc program is being
implemented with the lead partner the Technical University of
Madrid. The entire partnership has six Universities, seven SMEs and
one National Park from seven different countries all over Europe.
The MSc will have 10 educational modules that will be available
online and will prepare professionals that will be able to implement
ecotourism in a sustainable way. Only through awareness and
education a sustainable ecotourism will be achieved in the protected
areas of Europe.
Abstract: The conventional Wi-Fi backscatter system can only
process one-to-one communication between the Wi-Fi reader and the
Wi-Fi tag. For improvement of throughput of the conventional system,
this paper proposes the multi-to-multi communication system. In the
proposed system, the interference by the multi-to-multi
communication is effectively cancelled by the orthogonal multiple
access based on the identification code of the tag. Although the
overhead is generated by the procedure for the multi-to-multi
communication, because the procedure is processed by the Wi-Fi
protocol, the overhead is insignificant for the entire communication
procedure. From the numerical results, it is confirmed that the
proposed system has nearly proportional increased throughput in
according to the number of the tag that simultaneously participates in
communication.
Abstract: In this paper, an experiment was conducted to assess
the impact of online deliberation on citizens’ attitudes. Specifically,
this research compared pre and post deliberation opinions of
participants who deliberated online via an asynchronous platform
regarding the issue of political opinion polls. Results indicate that
online deliberation had a positive effect on citizens’ attitudes since it
was found that following deliberation participants changed their
views regarding public opinion polls. Specifically, online deliberation
improved discussants perceptions regarding the reliability of polls,
while suppressing their negative views about the misuse of polls by
media, polling organizations and politicians.
Abstract: The reduction of phosphorus and sulfur in engine oil
are the main topics of this paper. Very reproducible boundary
lubrication tests were conducted as part of Design of Experiment
software (DOE) to study the behavior of fluorinated catalyst iron
fluoride (FeF3), and polutetrafluoroethylene or Teflon (PTFE) in
developing environmentally friendly (reduced P and S) anti-wear
additives for future engine oil formulations. Multi-component
Chevron fully formulated oil (GF3) and Chevron plain oil were used
with the addition of PTFE and catalyst to characterize and analyze
their performance. Lower phosphorus blends were the goal of the
model solution. Experiments indicated that new sub-micron FeF3
catalyst played an important role in preventing breakdown of the
tribofilm.
Abstract: It is a major challenge to build a bridge superstructure
that has long-term durability and low maintenance requirements. A
solution to this challenge may be to use new materials or to
implement new structural systems. Fiber Reinforced Polymer (FRP)
composites have continued to play an important role in solving some
of persistent problems in infrastructure applications because of its
high specific strength, light weight, and durability. In this study, the
concept of the hybrid FRP-concrete structural systems is applied to a
bridge superstructure. The hybrid FRP-concrete bridge superstructure
is intended to have durable, structurally sound, and cost effective
hybrid system that will take full advantage of the inherent properties
of both FRP materials and concrete. In this study, two hybrid FRP-concrete
bridge systems were investigated. The first system consists
of trapezoidal cell units forming a bridge superstructure. The second
one is formed by arch cells. The two systems rely on using cellular
components to form the core of the bridge superstructure, and an
outer shell to warp around those cells to form the integral unit of the
bridge. Both systems were investigated analytically by using finite
element (FE) analysis. From the rigorous FE studies, it was
concluded that first system is more efficient than the second.
Abstract: The main objective of this study was to determine the
effects of Nitrogen fixing bacteria and manure application on the seed
yield and yield components in black cumin (Nigella sativa L.). The
experiment was carried out at the RAN Research Station in
Firouzkouh in 2012. A 4×4 factorial experiment, arranged in a
randomized complete blocks designed with three replications.
Nitrogen fixing bacteria at 4 levels (control, Azotobacter,
Azospirillum and Azotobacter + Azospirillum) and manure
application at 4 levels (0, 2.5, 5 and 7.5 ton ha-1) were used at this
investigation. The present results have shown that the highest height,
1000 seeds weight, seed number per follicle, follicle yield, seed yield
and harvest index were obtained after using Azotobacter and
Azospirillum, simultaneously. Manure application only effects on
follicle yield and by 5ton manure ha-1 the highest follicle yield
obtained. Results of this investigation showed that the maximum seed
yield obtained when Aotobacter+Azospirillum inoculated with black
cumin seeds and 5 ton manure ha-1 applied. According to the results
of this investigation the integrated management of Azotobacter and
Azospirillum with manure application is the best treatment for
achieving the maximum quantitative charactersitics of Black cumin.
Abstract: The paper provides a comprehensive analysis of the
sustainable development in the Belgrade Metropolitan Region - BMA
(level NUTS 2) preliminary evaluating the three chosen components:
1) economic growth and developmental changes; 2) competitiveness;
and 3) territorial concentration and industrial specialization. First, we
identified the main results of development changes and economic
growth by applying Shift-share analysis on the metropolitan level.
Second, the empirical evaluation of competitiveness in the BMA is
based on the analysis of absolute and relative values of eight
indicators by Spider method. Paper shows that the consideration of
the national share, industrial mix and metropolitan/regional share in
total Shift share of the BMA, as well as economic/functional
specialization of the BMA indicate very strong process of
deindustrialization. Allocative component of the BMA economic
growth has positive value, reflecting the above-average sector
productivity compared to the national average. Third, the important
positive role of metropolitan/regional component in decomposition of
the BMA economic growth is highlighted as one of the key results.
Finally, comparative analysis of the industrial territorial
concentration in the BMA in relation to Serbia is based on location
quotient (LQ) or Balassa index as a valid measure. The results
indicate absolute and relative differences in decrease of industry
territorial concentration as well as inefficiency of utilizing territorial
capital in the BMA. Results are important for the increase of regional
competitiveness and territorial distribution in this area as well as for
improvement of sustainable metropolitan and sector policies,
planning and governance on this level.
Abstract: There have been rigorous research and development
of unmanned aerial vehicles in the field of search and rescue (SAR)
operation recently. UAVs reduce unnecessary human risks while
assisting rescue efforts through aerial imagery, topographic mapping
and emergency delivery. The application of UAVs in offshore and
nearshore marine SAR missions is discussed in this paper. Projects
that integrate UAV technology into their systems are introduced to
highlight the great advantages and capabilities of UAVs. Scenarios
where UAVs could provide invaluable assistance are also suggested.
Abstract: Si ion implantation was widely used to synthesize
specimens of SiO2 containing supersaturated Si and subsequent high
temperature annealing induces the formation of embedded
luminescent Si nanocrystals. In this work, the potentialities of excimer
UV-light (172 nm, 7.2 eV) irradiation and rapid thermal annealing
(RTA) to enhance the photoluminescence and to achieve low
temperature formation of Si nanocrystals have been investigated. The
Si ions were introduced at acceleration energy of 180 keV to fluence of
7.5 x 1016 ions/cm2. The implanted samples were subsequently
irradiated with an excimer-UV lamp. After the process, the samples
were rapidly thermal annealed before furnace annealing (FA).
Photoluminescence spectra were measured at various stages at the
process. We found that the luminescence intensity is strongly
enhanced with excimer-UV irradiation and RTA. Moreover, effective
visible photoluminescence is found to be observed even after FA at
900 oC, only for specimens treated with excimer-UV lamp and RTA.
We also prepared specimens of Si nanocrystals embedded in a SiO2 by
reactive pulsed laser deposition (PLD) in an oxygen atmosphere. We
will make clear the similarities and differences with the way of
preparation.
Abstract: This paper presents results of compressive strength,
capillary water absorption, and density tests conducted on concrete
containing recycled aggregate (RCA) which is obtained from
structural waste generated by the construction industry in Turkey. In
the experiments, 0%, 15%, 30%, 45% and 60% of the normal
(natural) coarse aggregate was replaced by the recycled aggregate.
Maximum aggregate particle sizes were selected as 16 mm, 22,4 mm
and 31,5 mm; and 0,06%, 0,13% and 0,20% of air-entraining agent
(AEA) were used in mixtures. Fly ash and superplasticizer were used
as a mineral and chemical admixture, respectively. The same type
(CEM I 42.5) and constant dosage of cement were used in the study.
Water/cement ratio was kept constant as 0.53 for all mixture. It was
concluded that capillary water absorption, compressive strength, and
density of concrete decreased with increasing RCA ratio. Increasing
in maximum aggregate particle size and amount of AEA also affect
the properties of concrete significantly.
Abstract: This study investigates the effects of the lead angle
and chip thickness variation on surface roughness during the
machining of compacted graphite iron using ceramic cutting tools
under dry cutting conditions. Analytical models were developed for
predicting the surface roughness values of the specimens after the
face milling process. Experimental data was collected and imported
to the artificial neural network model. A multilayer perceptron model
was used with the back propagation algorithm employing the input
parameters of lead angle, cutting speed and feed rate in connection
with chip thickness. Furthermore, analysis of variance was employed
to determine the effects of the cutting parameters on surface
roughness. Artificial neural network and regression analysis were
used to predict surface roughness. The values thus predicted were
compared with the collected experimental data, and the
corresponding percentage error was computed. Analysis results
revealed that the lead angle is the dominant factor affecting surface
roughness. Experimental results indicated an improvement in the
surface roughness value with decreasing lead angle value from 88° to
45°.
Abstract: Elastomeric polymer foam has been used widely in
the automotive industry, especially for isolating unwanted vibrations.
Such material is able to absorb unwanted vibration due to its
combination of elastic and viscous properties. However, the ‘creep
effect’, poor stress distribution and susceptibility to high
temperatures are the main disadvantages of such a system.
In this study, improvements in the performance of elastomeric
foam as a vibration isolator were investigated using the concept of
Foam Filled Fluid (FFFluid). In FFFluid devices, the foam takes the
form of capsule shapes, and is mixed with viscous fluid, while the
mixture is contained in a closed vessel. When the FFFluid isolator is
affected by vibrations, energy is absorbed, due to the elastic strain of
the foam. As the foam is compressed, there is also movement of the
fluid, which contributes to further energy absorption as the fluid
shears. Also, and dependent on the design adopted, the packaging
could also attenuate vibration through energy absorption via friction
and/or elastic strain.
The present study focuses on the advantages of the FFFluid
concept over the dry polymeric foam in the role of vibration isolation.
This comparative study between the performance of dry foam and the
FFFluid was made according to experimental procedures. The paper
concludes by evaluating the performance of the FFFluid isolator in
the suspension system of a light vehicle. One outcome of this
research is that the FFFluid may preferable over elastomer isolators
in certain applications, as it enables a reduction in the effects of high
temperatures and of ‘creep effects’, thereby increasing the reliability
and load distribution. The stiffness coefficient of the system has
increased about 60% by using an FFFluid sample. The technology
represented by the FFFluid is therefore considered by this research
suitable for application in the suspension system of a light vehicle.
Abstract: The literature on language teaching and second
language acquisition has been largely driven by monolingual
ideology with a common assumption that a second language (L2) is
best taught and learned in the L2 only. The current study challenges
this assumption by reporting learners' positive perceptions of tertiary
level teachers' code switching practices in Vietnam. The findings of
this study contribute to our understanding of code switching practices
in language classrooms from a learners' perspective.
Data were collected from student participants who were working
towards a Bachelor degree in English within the English for Business
Communication stream through the use of focus group interviews.
The literature has documented that this method of interviewing has a
number of distinct advantages over individual student interviews. For
instance, group interactions generated by focus groups create a more
natural environment than that of an individual interview because they
include a range of communicative processes in which each individual
may influence or be influenced by others - as they are in their real
life. The process of interaction provides the opportunity to obtain the
meanings and answers to a problem that are "socially constructed
rather than individually created" leading to the capture of real-life
data. The distinct feature of group interaction offered by this
technique makes it a powerful means of obtaining deeper and richer
data than those from individual interviews. The data generated
through this study were analysed using a constant comparative
approach. Overall, the students expressed positive views of this
practice indicating that it is a useful teaching strategy. Teacher code
switching was seen as a learning resource and a source supporting
language output. This practice was perceived to promote student
comprehension and to aid the learning of content and target language
knowledge. This practice was also believed to scaffold the students'
language production in different contexts. However, the students
indicated their preference for teacher code switching to be
constrained, as extensive use was believed to negatively impact on
their L2 learning and trigger cognitive reliance on the L1 for L2
learning. The students also perceived that when the L1 was used to a
great extent, their ability to develop as autonomous learners was
negatively impacted.
This study found that teacher code switching was supported in
certain contexts by learners, thus suggesting that there is a need for
the widespread assumption about the monolingual teaching approach
to be re-considered.
Abstract: Ant Colony Optimization (ACO) is a promising
modern approach to the unused combinatorial optimization. Here
ACO is applied to finding the shortest during communication link
failure. In this paper, the performances of the prim’s and ACO
algorithm are made. By comparing the time complexity and program
execution time as set of parameters, we demonstrate the pleasant
performance of ACO in finding excellent solution to finding shortest
path during communication link failure.
Abstract: Aging infrastructures became a serious social problem.
This brought out the increased need for the legislation of a new strict
guideline for infrastructure management. Although existing guidelines
provided basics of how to evaluate and manage the condition of
infrastructures, they needed improvements for their evaluation
procedures. Most guidelines mainly focused on the structural
condition of infrastructures and did not properly reflect service aspects
of infrastructures such as performance, public demand, capacity, etc.,
which were significantly valuable to public. Regardless of the
importance, these factors were often neglected in infrastructure
evaluations, because they were quite subjective and difficult to
quantify in rational manner. Thus, this study proposed a framework to
properly identify and evaluate the service indicators. This study
showed that service indicators could be grouped into two categories
and properly evaluated using AHP and Fuzzy. Overall, proposed
framework is expected to assist governmental agency in establishing
effective investment strategies for infrastructure improvements.
Abstract: Waste Load Allocation (WLA) strategies usually
intend to find economic policies for water resource management.
Water quality trading (WQT) is an approach that uses discharge
permit market to reduce total environmental protection costs. This
primarily requires assigning discharge limits known as total
maximum daily loads (TMDLs). These are determined by monitoring
organizations with respect to the receiving water quality and
remediation capabilities. The purpose of this study is to compare two
approaches of TMDL assignment for WQT policy in small catchment
area of Haraz River, in north of Iran. At first, TMDLs are assigned
uniformly for the whole point sources to keep the concentrations of
BOD and dissolved oxygen (DO) at the standard level at checkpoint
(terminus point). This was simply simulated and controlled by
Qual2kw software. In the second scenario, TMDLs are assigned
using multi objective particle swarm optimization (MOPSO) method
in which the environmental violation at river basin and total treatment
costs are minimized simultaneously. In both scenarios, the equity
index and the WLA based on trading discharge permits (TDP) are
calculated. The comparative results showed that using economically
optimized TMDLs (2nd scenario) has slightly more cost savings rather
than uniform TMDL approach (1st scenario). The former annually
costs about 1 M$ while the latter is 1.15 M$. WQT can decrease
these annual costs to 0.9 and 1.1 M$, respectively. In other word,
these approaches may save 35 and 45% economically in comparison
with command and control policy. It means that using multi objective
decision support systems (DSS) may find more economical WLA,
however its outcome is not necessarily significant in comparison with
uniform TMDLs. This may be due to the similar impact factors of
dischargers in small catchments. Conversely, using uniform TMDLs
for WQT brings more equity that makes stakeholders not feel that
much envious of difference between TMDL and WQT allocation. In
addition, for this case, determination of TMDLs uniformly would be
much easier for monitoring. Consequently, uniform TMDL for TDP
market is recommended as a sustainable approach. However,
economical TMDLs can be used for larger watersheds.