Abstract: The material selection in the design of the sandwich
structures is very crucial aspect because of the positive or negative
influences of the base materials to the mechanical properties of the
entire panel. In the literature, it was presented that the selection of the
skin and core materials plays very important role on the behavior of
the sandwich. Beside this, the use of the correct adhesive can make
the whole structure to show better mechanical results and behavior.
In the present work, the static three-point bending tests were
performed on the sandwiches having an aluminum alloy foam core,
the skins made of three different types of fabrics and two different
commercial adhesives (flexible polyurethane and toughened epoxy
based) at different values of support span distances by aiming the
analyses of their flexural performance in terms of absorbed energy,
peak force values and collapse mechanisms. The main results of the
flexural loading are: force-displacement curves obtained after the
bending tests, peak force and absorbed energy values, collapse
mechanisms and adhesion quality. The experimental results presented
that the sandwiches with epoxy based toughened adhesive and the
skins made of S-Glass Woven fabrics indicated the best adhesion
quality and mechanical properties. The sandwiches with toughened
adhesive exhibited higher peak force and energy absorption values
compared to the sandwiches with flexible adhesive. The use of these
sandwich structures can lead to a weight reduction of the transport
vehicles, providing an adequate structural strength under operating
conditions.
Abstract: In the current work, a three-dimensional geometry of a
75% stenosed blood vessel is analyzed. Large eddy simulation (LES)
with the help of a dynamic subgrid scale Smagorinsky model is
applied to model the turbulent pulsatile flow. The geometry, the
transmural pressure and the properties of the blood and the elastic
boundary were based on clinical measurement data. For the flexible
wall model, a thin solid region is constructed around the 75%
stenosed blood vessel. The deformation of this solid region was
modelled as a deforming boundary to reduce the computational cost
of the solid model. Fluid-structure interaction is realized via a twoway
coupling between the blood flow modelled via LES and the
deforming vessel. The information of the flow pressure and the wall
motion was exchanged continually during the cycle by an arbitrary
Lagrangian-Eulerian method. The boundary condition of current time
step depended on previous solutions. The fluctuation of the velocity
in the post-stenotic region was analyzed in the study. The axial
velocity at normalized position Z=0.5 shows a negative value near
the vessel wall. The displacement of the elastic boundary was
concerned in this study. In particular, the wall displacement at the
systole and the diastole were compared. The negative displacement at
the stenosis indicates a collapse at the maximum velocity and the
deceleration phase.
Abstract: Predicting the collapse potential of a structure during
earthquakes is an important issue in earthquake engineering. Many
researchers proposed different methods to assess the collapse
potential of structures under the effect of strong ground motions.
However most of them did not consider degradation and softening
effect in hysteretic behavior. In this study, collapse potential of
SDOF systems caused by dynamic instability with stiffness and
strength degradation has been investigated. An equation was
proposed for the estimation of collapse period of SDOF system which
is a limit value of period for dynamic instability. If period of the
considered SDOF system is shorter than the collapse period then the
relevant system exhibits dynamic instability and collapse occurs.
Abstract: Chemical vapor deposition (CVD) diamond coated
cutting tool has excellent cutting performance, it is the most ideal tool
for the processing of nonferrous metals and alloys, composites,
nonmetallic materials and other difficult-to-machine materials
efficiently and accurately. Depositing CVD diamond coating on the
cemented carbide with high cobalt content can improve its toughness
and strength, therefore, it is very important to research on the
preparation technology and cutting properties of CVD diamond coated
cemented carbide cutting tool with high cobalt content. The
preparation technology of boron-doped diamond (BDD) coating has
been studied and the coated drills were prepared. BDD coating were
deposited on the drills by using the optimized parameters and the SEM
results show that there are no cracks or collapses in the coating.
Cutting tests with the prepared drills against the silumin and aluminum
base printed circuit board (PCB) have been studied. The results show
that the wear amount of the coated drill is small and the machined
surface has a better precision. The coating does not come off during
the test, which shows good adhesion and cutting performance of the
drill.
Abstract: Urban Search and Rescue (USAR) is a functional
capability that has been developed to allow the United Kingdom Fire
and Rescue Service to deal with ‘major incidents’ primarily involving
structural collapse. The nature of the work undertaken by USAR
means that staying out of a damaged or collapsed building structure is
not usually an option for search and rescue personnel. As a result
there is always a risk that they themselves could become victims. For
this paper, a systematic and investigative review using desk research
was undertaken to explore the role which structural engineering can
play in assisting search and rescue personnel to conduct structural
assessments when in the field. The focus is on how search and rescue
personnel can assess damaged and collapsed building structures, not
just in terms of structural damage that may been countered, but also
in relation to structural stability. Natural disasters, accidental
emergencies, acts of terrorism and other extreme events can vary
significantly in nature and ferocity, and can cause a wide variety of
damage to building structures. It is not possible or, even realistic, to
provide search and rescue personnel with definitive guidelines and
procedures to assess damaged and collapsed building structures as
there are too many variables to consider. However, understanding
what implications damage may have upon the structural stability of a
building structure will enable search and rescue personnel to better judge
and quantify risk from a life-safety standpoint. It is intended that this
will allow search and rescue personnel to make informed decisions
and ensure every effort is made to mitigate risk, so that they
themselves do not become victims.
Abstract: Since columns are the most important elements of the
structures, failure of one column in a critical location can cause a
progressive collapse. In this respect, the repair and strengthening of
columns is a very important subject to reduce the building failure and
to keep the columns capacity. Twenty columns with different
parameters is tested and analysis. Eleven typical confined reinforced
concrete (RC) columns with different types of techniques are
assessment. And also, four confined concrete columns with plastic
tube (PVC) are tested with and with four paralleling tested of
unconfined plain concrete. The techniques of confined RC columns
are mortar strengthening, Steel rings strengthening, FRP
strengthening. Moreover, the technique of confined plain concrete
(PC) column is used PVC tubes. The columns are tested under
uniaxial compressive loads studied the effect of confinement on the
structural behavior of circular RC columns. Test results for each
column are presented in the form of crack patterns, stress-strain
curves. Test results show that confining of the RC columns using
different techniques of strengthening results significant improvement
of the general behavior of the columns and can used in construction.
And also, tested confined PC columns with PVC tubes results shown
that the confined PC with PVC tubes can be used in economical
building. The theoretical model for predicted column capacity is
founded with experimental factor depends on the confined techniques
used and the strain reduction.
Abstract: This study carried out comparative seismic
performance of reinforced concrete frames infilled by masonry walls
with different heights. Partial and fully infilled reinforced concrete
frames were modeled for the research objectives and the analysis
model for a bare reinforced concrete frame was also established for
comparison. Non–linear static analyses for the studied frames were
performed to investigate their structural behavior under extreme
seismic loads and to find out their collapse mechanism. It was
observed from analysis results that the strengths of the partial infilled
reinforced concrete frames are increased and their ductilities are
reduced, as infilled masonry walls are higher. Especially, reinforced
concrete frames with higher partial infilled masonry walls would
experience shear failures. Non–linear dynamic analyses using 10
earthquake records show that the bare and fully infilled reinforced
concrete frame present stable collapse mechanism while the reinforced
concrete frames with partially infilled masonry walls collapse in more
brittle manner due to short-column effects.
Abstract: At present, the evaluation of voltage stability
assessment experiences sizeable anxiety in the safe operation of
power systems. This is due to the complications of a strain power
system. With the snowballing of power demand by the consumers
and also the restricted amount of power sources, therefore, the system
has to perform at its maximum proficiency. Consequently, the
noteworthy to discover the maximum ability boundary prior to
voltage collapse should be undertaken. A preliminary warning can be
perceived to evade the interruption of power system’s capacity. The
effectiveness of line voltage stability indices (LVSI) is differentiated
in this paper. The main purpose of the indices used is to predict the
proximity of voltage instability of the electric power system. On the
other hand, the indices are also able to decide the weakest load buses
which are close to voltage collapse in the power system. The line
stability indices are assessed using the IEEE 14 bus test system to
validate its practicability. Results demonstrated that the implemented
indices are practically relevant in predicting the manifestation of
voltage collapse in the system. Therefore, essential actions can be
taken to dodge the incident from arising.
Abstract: The financial crises caused a collapse in prices of
most asset classes, raising the attention on alternative investments
such as sukuk, a smaller, fast growing but often misunderstood
market. We study diversification benefits of sukuk, their correlation
with other asset classes and the effects of their inclusion in
investment portfolios of institutional and retail investors, through a
comprehensive comparison of their risk/return profiles during and
after the financial crisis.
We find a beneficial performance adjusted for the specific
volatility together with a lower correlation especially during the
financial crisis. The distribution of sukuk returns is positively skewed
and leptokurtic, with a risk/return profile similarly to high yield
bonds. Overall, our results suggest that sukuk present diversification
opportunities, a significant volatility-adjusted performance and lower
correlations especially during the financial crisis.
Our findings are relevant for a number of institutional investors.
Long term investors, such as life insurers would benefit from sukuk’s
protective features during financial crisis yet keeping return and
growth opportunities, whereas banks would gain due to their role of
placers, advisors, market makers or underwriters.
Abstract: Collapsible soils go through radical rearrangement of
their particles when triggered by water, stress or/and vibration,
causing loss of volume. This loss of volume in soil as seen in
foundation failures has caused millions of dollars’ worth of damages
to public facilities and infrastructure and so has an adverse effect on
the society and people. Despite these consequences and the several
studies that are available, more research is still required in the study
of soil collapsibility. Discerning the pedogenesis (formation) of soils
and investigating the combined effects of the different geological soil
properties is key to elucidating and quantifying soils collapsibility.
This study presents a novel laboratory testing regime that would be
undertaken on soil samples where the effects of soil type, compactive
variables (moisture content, density, void ratio, degree of saturation)
and loading are analyzed. It is anticipated that results obtained would
be useful in mapping the trend of the combined effect thus the basis
for evaluating soil collapsibility or collapse potentials encountered in
construction with volume loss problems attributed to collapse.
Abstract: This study offers a comprehensive review of the
research papers published in the field of cooling towers and gives an
insight into the latest developments of the natural draught cooling
towers. Different modeling, analysis and design techniques are
summarized and the challenges are discussed. The 118 references
included in this paper are mostly concentrated on the review of the
published papers after 2005. The present paper represents a complete
collection of the studies done for cooling towers and would give an
updated material for the researchers and design engineers in the field
of hyperbolic cooling towers.
Abstract: Metallic foams have good potential for lightweight
structures for impact and blast mitigation. Therefore it is important to
find out the optimized foam structure (i.e. cell size, shape, relative
density, and distribution) to maximise energy absorption. In this
paper, quasistatic compression and microstructural characterization
of closed-cell aluminium foams of different pore size and cell
distributions have been carried out. We present results for two
different aluminium metal foams of density 0.49-0.51 g/cc and 0.31-
0.34 g/cc respectively that have been tested in quasi-static
compression. The influence of cell geometry and cell topology on
quasistatic compression behaviour has been investigated using optical
microscope and computed tomography (micro-CT) analysis. It is
shown that the deformation is not uniform in the structure and
collapse begins at the weakest point.
Abstract: This paper presents the voltage problem location
classification using performance of Least Squares Support Vector
Machine (LS-SVM) and Learning Vector Quantization (LVQ) in
electrical power system for proper voltage problem location
implemented by IEEE 39 bus New- England. The data was collected
from the time domain simulation by using Power System Analysis
Toolbox (PSAT). Outputs from simulation data such as voltage, phase
angle, real power and reactive power were taken as input to estimate
voltage stability at particular buses based on Power Transfer Stability
Index (PTSI).The simulation data was carried out on the IEEE 39 bus
test system by considering load bus increased on the system. To verify
of the proposed LS-SVM its performance was compared to Learning
Vector Quantization (LVQ). The results showed that LS-SVM is faster
and better as compared to LVQ. The results also demonstrated that the
LS-SVM was estimated by 0% misclassification whereas LVQ had
7.69% misclassification.
Abstract: The use of low quality concrete has been identified as one of the main causes of the incessant collapse of buildings in Nigeria. Emphasis has been on the use of poor quality aggregates, poor workmanship and the use of lean concrete mix with low cement quantity as the reasons for the low quality of concrete used for building construction in Nigeria. Surveys conducted revealed that in the construction of most privately owned buildings where concrete trial mixes and concrete compressive strength quality assurance tests are not conducted, concretes used for building constructions are produced using the 1:2:4 mix ratio irrespective of the cement grade/strength class. In this paper, the possible role of the use of inappropriate cement grade/strength class as a cause of the incessant collapse of building in Nigeria is investigated. Investigation revealed that the compressive strengths of concrete cubes produced with Portland-limestone cement grade 32.5 using 1:2:4 and 1:1.5:3 mix ratios are less than the 25MPa and 30MPa cube strengths generally recommended for building superstructures and foundations respectively. Conversely, the compressive strengths of concrete cubes produced with Portland-limestone cement grade 42.5 using 1:2:4 and 1:1.5:3 mix ratios exceed the 25MPa and 30MPa generally recommended for building superstructures and foundations respectively. Thus, it can be concluded that the use of inappropriate cement grade (Portland-limestone cement grade 32.5), particularly for the construction of building foundations is a potential cause of the incessant collapse of buildings in Nigeria. It is recommended that the Standards Organisation of Nigeria should embark on creating awareness for Nigerians, particularly, the home owners and the roadside craftsmen that Portland-limestone cement grade 32.5 should not be used for the construction of building load-carrying members, particularly, building foundations in order to reduce the incessant incidence of collapsed building.
Abstract: The approach in analyzing defects on different pipe lines is conducted through Failure Assessment Diagram (FAD). These methods of analyses have further extended in recent years. This approach is used to identify and stress out a solution for the defects which randomly occur with gas pipes such are corrosion defects, gauge defects, and combination of defects where gauge and dents are included. Few of the defects are to be analyzed in this paper where our main focus will be the fracture of cast Iron pipes, elastic-plastic failure and plastic collapse of X52 steel pipes for gas transport. We need to conduct a calculation of probability of the defects in order to predict and avoid such costly defects.
Abstract: Concrete sewer pipes are known to suffer from a process of hydrogen sulfide gas induced sulfuric acid corrosion. This leads to premature pipe degradation, performance failure and collapses which in turn may lead to property and health damage. The above work reports on a field study undertaken in working sewer manholes where the parameters of effluent temperature and pH as well as ambient temperature and concentration of hydrogen sulfide were continuously measured over a period of two months. Early results suggest that effluent pH has no direct effect on hydrogen sulfide build up; on average the effluent temperature is 3.5°C greater than the ambient temperature inside the manhole and also it was observed that hydrogen sulfate concentration increases with increasing temperature.
Abstract: The tremendous loss of life that resulted in the aftermath of recent earthquakes in developing countries is mostly due to the collapse of non-engineered and semi-engineered building structures. Such structures are used as houses, schools, primary healthcare centers and government offices. These building are classified structurally into two categories viz. non-engineered and semi-engineered. Non-engineered structures include: adobe, unreinforced masonry (URM) and wood buildings. Semi-engineered buildings are mostly low-rise (up to 3 story) light concrete frame structures or masonry bearing walls with reinforced concrete slab. This paper presents an overview of the typical damage observed in non-engineered structures and their most likely causes in the past earthquakes with specific emphasis on the performance of such structures in the 2005 Kashmir earthquake. It is demonstrated that seismic performance of these structures can be improved from life-safety viewpoint by adopting simple low-cost modifications to the existing construction practices. Incorporation of some of these practices in the reconstruction efforts after the 2005 Kashmir earthquake are examined in the last section for mitigating seismic risk hazard.
Abstract: Article presents a short overview of the architects’ profession over time with outlined work of the architectural theoreticians.
In the continuation is described a former affiliation of Slovenia as well as the spatial planning documents that were in use until the Slovenia joint Yugoslavia (last part in 1919). This legislation from former Austro-Hungarian monarchy was valid almost until 1950 in some parts of Yugoslavia even longer. Upon that will be mentioned some valid Slovenian spatial documents which will be compared with the German legislation.
Analyzed will be the number of architect and spatial planners in Slovenia and also their number upon certain region in Slovenia. Based on that will be given also the number from statistical office of Slovenia of the number of buildings between years 2007 and 2012, and described also the collapse of the major construction companies in Slovenia and consequences of that.
At the end will be outlined the morality and ethics by spatial interventions and lack of the architectural law in Slovenia as well as the problematic of minimal collaboration between the Ministry of infrastructure and spatial planning with the profession.
Abstract: Uncertainty of system operating conditions is one of the causative reasons which may render to the instability of a transmission system. For that reason, accurate assessment of transmission reliability margin (TRM) is essential to ensure effective power transfer between areas during the occurrence of system uncertainties. The power transfer is also called as the available transfer capability (ATC) which is the information required by the utilities and marketers to instigate selling and buying the electric energy. This paper proposes a computationally effective approach to estimate TRM and ATC by considering the uncertainties of system cascading collapse and transmission line outages. In accordance to the results that have been obtained, the proposed method is essential for the transmission providers which could help the power marketers and planning sectors in the operation and reserving transmission services based on the ATC calculated.
Abstract: Over the past few decades, power system industry in many developing and developed countries has gone through a restructuring process of the industry where they are moving towards deregulated power industry. This situation will lead to competition among the generation and distribution companies to provide quality and efficient production of electric energy, which will reduce the price of electricity. Therefore it is important to obtain an accurate value of the available transfer capability (ATC) and transmission reliability margin (TRM) in order to ensure the effective power transfer between areas during the occurrence of uncertainties in the system. In this paper, the TRM and ATC is determined by taking into consideration the uncertainties of the system operating condition and system cascading collapse by applying the bootstrap technique. A case study of the IEEE RTS-79 is employed to verify the robustness of the technique proposed in the determination of TRM and ATC.