Abstract: This paper describes analysis of low velocity transverse impact on fully backed sandwich beams with composite faces from Eglass/epoxy and cores from Polyurethane or PVC. Indentation on sandwich beams has been analyzed with the existing theories and modeled with the FE code ABAQUS, also loadings have been done experimentally to verify theoretical results. Impact on fully backed has been modeled in two cases of impactor energy with SDOF model (single-degree-of-freedom) and indentation stiffness: lower energy for elastic indentation of sandwich beams and higher energy for plastic area in indentation. Impacts have been modeled by ABAQUS. Impact results can describe response of beam in terms of core and faces thicknesses, core material, indentor energy and energy absorbed. The foam core is modeled using the crushable foam material model and response of the foam core is experimentally characterized in uniaxial compression with higher velocity loading to define quasi impact behaviour.
Abstract: The corrugated steel cladding used to cover most of
steel buildings is considered as non-structural element. This research
will reflect the effect of cladding as a shear diaphragm in increasing
the normal elastic capacity of columns. This study is important
because of the lack of information of the behavior of cladding and
secondary members in various codes. Mathematical models for six
different cases are carried by software. The results extracted from the
program have been plotted showing the effects of different variables
on the ultimate load of column. The variables considered in our
research are the spacing between columns and the thickness of the
corrugated sheet representing the sheet stiffness.
Abstract: Frequent pattern discovery over data stream is a hard
problem because a continuously generated nature of stream does not
allow a revisit on each data element. Furthermore, pattern discovery
process must be fast to produce timely results. Based on these
requirements, we propose an approximate approach to tackle the
problem of discovering frequent patterns over continuous stream.
Our approximation algorithm is intended to be applied to process a
stream prior to the pattern discovery process. The results of
approximate frequent pattern discovery have been reported in the
paper.
Abstract: Using the finite element analyses, this paper discusses the effects of temperature-dependent material properties on the stress and temperature fields in a cracked metal plate under the electric current load. The practical and complicated results are obtained when the temperature-dependent material properties are adopted in the analysis. If the simplified (temperature-independent) material properties are used, incorrect results will be obtained.
Abstract: In this paper delamination phenomenon in
Carbon-Epoxy laminated composite material is investigated
numerically. Arcan apparatus and specimen is modeled in ABAQUS
finite element software for different loading conditions and crack
geometries. The influence of variation of crack geometry on
interlaminar fracture stress intensity factor and energy release rate for
various mixed mode ratios and pure mode I and II was studied. Also,
correction factors for this specimen for different crack length ratios
were calculated. The finite element results indicate that for loading
angles close to pure mode-II loading, a high ratio of mode-II to
mode-I fracture is dominant and there is an opposite trend for loading
angles close to pure mode-I loading. It confirms that by varying the
loading angle of Arcan specimen pure mode-I, pure mode-II and a
wide range of mixed-mode loading conditions can be created and
tested. Also, numerical results confirm that the increase of the mode-
II loading contribution leads to an increase of fracture resistance in
the CF/PEI composite (i.e., a reduction in the total strain energy
release rate) and the increase of the crack length leads to a reduction
of interlaminar fracture resistance in the CF/PEI composite (i.e., an
increase in the total interlaminar strain energy release rate).
Abstract: In the present study, fracture behavior of woven
fabric-reinforced glass/epoxy composite laminates under mode III
crack growth was experimentally investigated and numerically
modeled. Two methods were used for the calculation of the strain
energy release rate: the experimental compliance calibration (CC)
method and the Virtual Crack Closure Technique (VCCT). To
achieve this aim ECT (Edge Crack Torsion) was used to evaluate
fracture toughness in mode III loading (out of plane-shear) at
different crack lengths. Load–displacement and associated energy
release rates were obtained for various case of interest. To
calculate fracture toughness JIII, two criteria were considered
including non-linearity and maximum points in load-displacement
curve and it is observed that JIII increases with the crack length
increase. Both the experimental compliance method and the virtual
crack closure technique proved applicable for the interpretation of the
fracture mechanics data of woven glass/epoxy laminates in mode III.
Abstract: Fixed-point simulation results are used for the performance measure of inverting matrices using a reconfigurable processing element. Matrices are inverted using the Cholesky decomposition algorithm. The reconfigurable processing element is capable of all required mathematical operations. The fixed-point word length analysis is based on simulations of different condition numbers and different matrix sizes.
Abstract: This study examined the role of driving experience in hazard perception and categorization using traffic scene pictures. Specifically, young-inexperienced, moderately experienced and very experienced (taxi) drivers observed traffic scene pictures while connected to an eye tracking system and were asked to rate the level of hazardousness of each picture and to mention the three most prominent hazards in it. Target pictures included nine, nearly identical, pairs of pictures where one picture in each pair included an actual hazard as an additional element. Altogether, 22 areas of interest (AOIs) were predefined and included 13 potential hazards and 9 actual hazards. Data analysis included both verbal reports and eye scanning patterns of these AOIs. Generally, both experienced and taxi drivers noted a relatively larger number of potential hazards than young inexperienced drivers Thus, by relating to less salient potential hazards, experienced drivers have demonstrated a better situation model of the traffic environment.
Abstract: Mapping between local and global coordinates is an
important issue in finite element method, as all calculations are
performed in local coordinates. The concern arises when subparametric
are used, in which the shape functions of the field variable
and the geometry of the element are not the same. This is particularly
the case for C* elements in which the extra degrees of freedoms
added to the nodes make the elements sub-parametric. In the present
work, transformation matrix for C1* (an 8-noded hexahedron
element with 12 degrees of freedom at each node) is obtained using
equivalent C0 elements (with the same number of degrees of
freedom). The convergence rate of 8-noded C1* element is nearly
equal to its equivalent C0 element, while it consumes less CPU time
with respect to the C0 element. The existence of derivative degrees
of freedom at the nodes of C1* element along with excellent
convergence makes it superior compared with it equivalent C0
element.
Abstract: This paper presents a compact thermoelectric power generator system based on temperature difference across the element. The system can transfer the burning heat energy to electric energy directly. The proposed system has a thermoelectric generator and a power control box. In the generator, there are 4 thermoelectric modules (TEMs), each of which uses 2 thermoelectric chips (TEs) and 2 cold sinks, 1 thermal absorber, and 1 thermal conduction flat board. In the power control box, there are 1 storing energy device, 1 converter, and 1 inverter. The total net generating power is about 11W. This system uses commercial portable gas stoves or burns timber or the coal as the heat source, which is easily obtained. It adopts solid-state thermoelectric chips as heat inverter parts. The system has the advantages of being light-weight, quite, and mobile, requiring no maintenance, and havng easily-supplied heat source. The system can be used a as long as burning is allowed. This system works well for highly-mobilized outdoors situations by providing a power for illumination, entertainment equipment or the wireless equipment at refuge. Under heavy storms such as typhoon, when the solar panels become ineffective and the wind-powered machines malfunction, the thermoelectric power generator can continue providing the vital power.
Abstract: In this study the behavior of interlaminar fracture of
carbon-epoxy thermoplastic laminated composite is investigated
numerically and experimentally. Tests are performed with Arcan
specimens. Testing with Arcan specimen gives the opportunity of
utilizing just one kind of specimen for extracting fracture properties
for mode I, mode II and different mixed mode ratios of materials with
exerting load via different loading angles. Variation of loading angles
in range of 0-90° made possible to achieve different mixed mode
ratios. Correction factors for various conditions are obtained from
ABAQUS 2D finite element models which demonstrate the finite
shape of Arcan specimens used in this study. Finally, applying the
correction factors to critical loads obtained experimentally, critical
interlaminar fracture toughness of this type of carbon- epoxy
composite has been attained.
Abstract: Data stream analysis is the process of computing
various summaries and derived values from large amounts of data
which are continuously generated at a rapid rate. The nature of a
stream does not allow a revisit on each data element. Furthermore,
data processing must be fast to produce timely analysis results. These
requirements impose constraints on the design of the algorithms to
balance correctness against timely responses. Several techniques
have been proposed over the past few years to address these
challenges. These techniques can be categorized as either dataoriented
or task-oriented. The data-oriented approach analyzes a
subset of data or a smaller transformed representation, whereas taskoriented
scheme solves the problem directly via approximation
techniques. We propose a hybrid approach to tackle the data stream
analysis problem. The data stream has been both statistically
transformed to a smaller size and computationally approximated its
characteristics. We adopt a Monte Carlo method in the approximation
step. The data reduction has been performed horizontally and
vertically through our EMR sampling method. The proposed method
is analyzed by a series of experiments. We apply our algorithm on
clustering and classification tasks to evaluate the utility of our
approach.
Abstract: Transportation is of great importance in the current
life of human beings. The transportation system plays many roles,
from economical development to after-catastrophe aids such as
rescue operation in the first hours and days after an earthquake. In
after earthquakes response phase, transportation system acts as a
basis for ground operations including rescue and relief operation,
food providing for victims and etc. It is obvious that partial or
complete obstruction of this system results in the stop of these
operations. Bridges are one of the most important elements of
transportation network. Failure of a bridge, in the most optimistic
case, cuts the relation between two regions and in more developed
countries, cuts the relation of numerous regions. In this paper, to
evaluate the vulnerability and estimate the damage level of Tehran
bridges, HAZUS method, developed by Federal Emergency
Management Agency (FEMA) with the aid of National Institute of
Building Science (NIBS), is used for the first time in Iran. In this
method, to evaluate the collapse probability, fragility curves are
used. Iran is located on seismic belt and thus, it is vulnerable to
earthquakes. Thus, the study of the probability of bridge collapses, as
an important part of transportation system, during earthquakes is of
great importance. The purpose of this study is to provide fragility
curves for Gisha Bridge, one of the longest steel bridges in Tehran,
as an important lifeline element. Besides, the damage probability for
this bridge during a specific earthquake, introduced as scenario
earthquakes, is calculated. The fragility curves show that for the
considered scenario, the probability of occurrence of complete
collapse for the bridge is 8.6%.
Abstract: Water recycling represents an important challenge for many countries, in particular in countries where this natural resource is rare. On the other hand, in many operations, water is used as a cooling medium, as a high proportion of water consumed in industry is used for cooling purposes. Generally this water is rejected directly to the nature. This reject will cause serious environment damages as well as an important waste of this precious element.. On way to solve these problems is to reuse and recycle this warm water, through the use of natural cooling medium, such as air in a heat exchanger unit, known as a cooling tower. A poor performance, design or reliability of cooling towers will result in lower flow rate of cooling water an increase in the evaporation of water, an hence losses of water and energy. This paper which presents an experimental investigate of thermal and hydraulic performances of a mechanical cooling tower, enables to show that the water evaporation rate, Mev, increases with an increase in the air and water flow rates, as well as inlet water temperature and for fixed air flow rates, the pressure drop (ΔPw/Z) increases with increasing , L, due to the hydrodynamic behavior of the air/water flow.
Abstract: Fixed-point simulation results are used for the
performance measure of inverting matrices by Cholesky
decomposition. The fixed-point Cholesky decomposition algorithm
is implemented using a fixed-point reconfigurable processing
element. The reconfigurable processing element provides all
mathematical operations required by Cholesky decomposition. The
fixed-point word length analysis is based on simulations using
different condition numbers and different matrix sizes. Simulation
results show that 16 bits word length gives sufficient performance
for small matrices with low condition number. Larger matrices and
higher condition numbers require more dynamic range for a fixedpoint
implementation.
Abstract: The integral form of equations of motion of composite
beams subjected to varying time loads are discretized using a
developed finite element model. The model consists of a straight five
node twenty-two degrees of freedom beam element. The stability
analysis of the beams is studied by solving the matrix form
characteristic equations of the system. The principle of virtual work
and the first order shear deformation theory are employed to analyze
the beams with large deformation and small strains. The regions of
dynamic instability of the beam are determined by solving the
obtained Mathieu form of differential equations. The effects of nonconservative
loads, shear stiffness, and damping parameters on
stability and response of the beams are examined. Several numerical
calculations are presented to compare the results with data reported
by other researchers.
Abstract: A subsea hydrocarbon production system can undergo planned and unplanned shutdowns during the life of the field. The thermal FEA is used to simulate the cool down to verify the insulation design of the subsea equipment, but it is also used to derive an acceptable insulation design for the cold spots. The driving factors of subsea analyses require fast responding and accurate models of the equipment cool down. This paper presents cool down analysis carried out by a Krylov subspace reduction method, and compares this approach to the commonly used FEA solvers. The model considered represents a typical component of a subsea production system, a closed valve on a dead leg. The results from the Krylov reduction method exhibits the least error and requires the shortest computational time to reach the solution. These findings make the Krylov model order reduction method very suitable for the above mentioned subsea applications.
Abstract: In the context of business incubation (BI) as strategic
enablers, this paper critically reviews the literature relating to the
strategic benefits of BI in the Middle East. The taxonomy of BI
benefits in the strategic elements on 1) type, 2) financial model, 3)
services, 4) objectives, 5) number of clients, 6) number of graduates,
and 7) jobs creation. Understanding the importance of BI benefits can
be significant in the economic development although most incubators
lead to diversify the economy. Thus, taxonomies of the benefits of BI
are produced from both the academic literature and published case
studies. In this way, a classification of strategic benefits elements as
they relate to incubators has been developed to provide a greater
understanding of the benefits needed to obtain a specific element.
The result of this paper is Business incubators is aimed
entrepreneurship, jobs creation, research commercialization and
profitable enterprises in Middle Eastern countries.
Abstract: Composite steel shear wall is a lateral load resisting system which consists of a steel plate with concrete wall attached to one or both sides to prevent it from elastic buckling. The composite behavior is ensured by utilizing high-strength bolts. This paper investigates the effect of distance between bolts, and for this purpose 14 one-story one-bay specimens with various bolts spacing were modeled by finite element code which is developed by the authors. To verify the model, numerical results were compared with a valid experiment which illustrate proper agreement. Results depict increasing the distance between bolts would improve the seismic ever, this increase must be limited, because of large distances will cause widespread buckling of the steel plate in free subpanels between bolts and would result in no improvement. By comparing the results in elastic region, it was observed initial stiffness is not affected by changing the distance.
Abstract: In this paper, the thermo-electro-structural coupledfield
in a cracked metal plate is studied using the finite element
analysis. From the computational results, the compressive stresses
reveal near the crack tip. This conclusion agrees with the past
reference. Furthermore, the compressive condition can retard and stop
the crack growth during the Joule heating process.