Abstract: Cloud Computing refers to applications delivered as
services over the internet, and the datacenters that provide those
services with hardware and systems software. These were earlier
referred to as Software as a Service (SaaS). Scheduling is justified by
job components (called tasks), lack of information. In fact, in a large
fraction of jobs from machine learning, bio-computing, and image
processing domains, it is possible to estimate the maximum time
required for a task in the job. This study focuses on Trust based
scheduling to improve cloud security by modifying Heterogeneous
Earliest Finish Time (HEFT) algorithm. It also proposes TR-HEFT
(Trust Reputation HEFT) which is then compared to Dynamic Load
Scheduling.
Abstract: Investigating the dynamic responses of high rise
structures under the effect of siesmic ground motion is extremely
important for the proper analysis and design of multitoried structures.
Since the presence of infilled walls strongly influences the behaviour
of frame systems in multistoried buildings, there is an increased need
for developing guidelines for the analysis and design of infilled
frames under the effect of dynamic loads for safe and proper design
of buildings. In this manuscript, we evaluate the natural frequencies
and natural periods of single bay single storey frames considering the
effect of infill walls by using the Eigen value analysis and validating
with SAP 2000 (free vibration analysis). Various parameters obtained
from the diagonal strut model followed for the free vibration analysis
is then compared with the Finite Element model, where infill is
modeled as shell elements (four noded). We also evaluated the effect
of various parameters on the natural periods of vibration obtained by
free vibration analysis in SAP 2000 comparing them with those
obtained by the empirical expressions presented in I.S. 1893(Part I)-
2002.
Abstract: A new design of aerostatic thrust bearing is proposed
for high static stiffness. The bearing body, which is mead of polymer
covered with metallic membrane, is held by a circular ring. Such a
support helps form a concave air gap to grasp the air pressure. The
polymer body, which can be made rapidly by either injection or
molding is able to provide extra damping under dynamic loading. The
smooth membrane not only serves as the bearing surface but also
protects the polymer body. The restrictor is a capillary inside a silicone
tube. It can passively compensate the variation of load by expanding
the capillary diameter for more air flux. In the present example, the
stiffness soars from 15.85 N/μm of typical bearing to 349.85 N/μm at
bearing elevation 9.5 μm; meanwhile the load capacity also enhances
from 346.86 N to 704.18 N.
Abstract: Typical load-bearing biological materials like bone,
mineralized tendon and shell, are biocomposites made from both
organic (collagen) and inorganic (biomineral) materials. This
amazing class of materials with intrinsic internally designed
hierarchical structures show superior mechanical properties with
regard to their weak components from which they are formed.
Extensive investigations concentrating on static loading conditions
have been done to study the biological materials failure. However,
most of the damage and failure mechanisms in load-bearing
biological materials will occur whenever their structures are exposed
to dynamic loading conditions. The main question needed to be
answered here is: What is the relation between the layout and
architecture of the load-bearing biological materials and their
dynamic behavior? In this work, a staggered model has been
developed based on the structure of natural materials at nanoscale and
Finite Element Analysis (FEA) has been used to study the dynamic
behavior of the structure of load-bearing biological materials to
answer why the staggered arrangement has been selected by nature to
make the nanocomposite structure of most of the biological materials.
The results showed that the staggered structures will efficiently
attenuate the stress wave rather than the layered structure.
Furthermore, such staggered architecture is effectively in charge of
utilizing the capacity of the biostructure to resist both normal and
shear loads. In this work, the geometrical parameters of the model
like the thickness and aspect ratio of the mineral inclusions selected
from the typical range of the experimentally observed feature sizes
and layout dimensions of the biological materials such as bone and
mineralized tendon. Furthermore, the numerical results validated with
existing theoretical solutions. Findings of the present work emphasize
on the significant effects of dynamic behavior on the natural
evolution of load-bearing biological materials and can help scientists
to design bioinspired materials in the laboratories.
Abstract: The main aim of the presented experiments is to
improve behaviour of sandwich structures under dynamic loading,
such as crash or explosion. This paper describes experimental
investigation on the response of new advanced materials to low and
high velocity load. Blast wave energy absorbers were designed using
two types of porous lightweight raw particle materials based on
expanded glass and ceramics with dimensions of 0.5-1 mm,
combined with polymeric binder. The effect of binder amount on the
static and dynamic properties of designed materials was observed.
Prism shaped specimens were prepared and loaded to obtain physicomechanical
parameters – bulk density, compressive and flexural
strength under quasistatic load, the dynamic response was determined
using Split Hopkinson Pressure bar apparatus. Numerical
investigation of the material behaviour in sandwich structure was
performed using implicit/explicit solver LS-Dyna. As the last step,
the developed material was used as the interlayer of blast resistant
litter bin, and it´s functionality was verified by real field blast tests.
Abstract: Over the years, it has been extensively established that
the practice of assuming a structure being fixed at base, leads to gross
errors in evaluation of its overall response due to dynamic loadings
and overestimations in design. The extent of these errors depends on
a number of variables; soil type being one of the major factor. This
paper studies the effect of Soil Structure Interaction (SSI) on multistorey
buildings with varying under-laying soil types after proper
validation of the effect of SSI. Analysis for soft, stiff and very stiff
base soils has been carried out, using a powerful Finite Element
Method (FEM) software package ANSYS v14.5. Results lead to
some very important conclusions regarding time period, deflection
and acceleration responses.
Abstract: Total hip replacement had been one of the most
successful operations in hip arthritis surgery. The purpose of this
research had been to develop a dynamic hip contact of Thai femoral
bone to analyze the stress distribution on the implant and the strain
distribution on the bone model under daily activities and compared
with the static load simulation. The results showed the different of
maximum von Mises stress 0.14 percent under walking and 0.03
percent under climbing stair condition and the different of equivalent
total strain 0.52 percent under walking and 0.05 percent under
climbing stair condition. The muscular forces should be evaluated
with dynamic condition to reduce the maximum von Mises stress and
equivalent total strain.
Abstract: This study examines analytically the effect of tsunami loads on reinforced concrete (RC) frame buildings. The impact of tsunami wave loads and waterborne objects are analyzed using a typical substandard full-scale two-story RC frame building tested as part of the EU-funded Ecoleader project. The building was subjected to shake table tests in bare condition, and subsequently strengthened using Carbon Fiber Reinforced Polymers (CFRP) composites and retested. Numerical models of the building in both bare and CFRP-strengthened conditions are calibrated in DRAIN-3DX software to match the test results. To investigate the response of wave loads and impact forces, the numerical models are subjected to nonlinear dynamic analyses using force time-history input records. The analytical results are compared in terms of displacements at the floors and at the “impact point” of a boat. The results show that the roof displacement of the CFRP-strengthened building reduced by 63% when compared to the bare building. The results also indicate that strengthening only the mid-height of the impact column using CFRP is more effective at reducing damage when compared to strengthening other parts of the column. Alternative solutions to mitigate damage due to tsunami loads are suggested.
Abstract: In this paper, a coupled damage effect in the
instability of a composite rotor is presented, under dynamic loading
response in the harmonic analysis condition. The analysis of the
stress which operates the rotor is done. Calculations of different
energies and the virtual work of the aerodynamic loads from the rotor
blade are developed. The use of the composite material for the rotor
offers a good stability.
Numerical calculations on the model developed prove that the
damage effect has a negative effect on the stability of the rotor.
The study of the composite rotor in transient system allowed
determining the vibratory responses due to various excitations.
Abstract: Paper presents a study about dynamic effects obtained
from the dynamic load testing of the city highway bridges in Latvia
carried out from 2005 to 2012. 9 prestressed concrete bridges and 4
composite bridges were considered. 11 of 13 bridges were designed
according to the Eurocodes but two according to the previous
structural codes used in Latvia (SNIP 2.05.03-84). The dynamic
properties of the bridges were obtained by heavy vehicle passing the
bridge roadway with different driving speeds and with or without
even pavement. The obtained values of the Dynamic amplification
factor (DAF) and the bridge natural frequency were analyzed and
compared to the values of built-in traffic load models provided in
Eurocode 1. The actual DAF values for even bridge pavement in the
most cases are smaller than the value adopted in Eurocode 1. Vehicle
speed for uneven pavements significantly influence Dynamic
amplification factor values.
Abstract: Excavation of shallow tunnels such as subways in urban areas plays a significant role as a life line and investigation of the soil behavior against tunnel construction is one of the vital subjects studied in the geotechnical scope. Nowadays, urban tunnels are mostly drilled by T.B.Ms and changing the applied forces to tunnel lining is one of the most risky matters while drilling tunnels by these machines. Variation of soil cementation can change the behavior of these forces in the tunnel lining. Therefore, this article is designed to assess the impact of tunnel excavation in different soils and several amounts of cementation on applied loads to tunnel lining under static and dynamic loads. According to the obtained results, changing the cementation of soil will affect the applied loadings to the tunnel envelope significantly. It can be determined that axial force in tunnel lining decreases considerably when soil cementation increases. Also, bending moment and shear force in tunnel lining decreases as the soil cementation increases and causes bending and shear behavior of the segments to improve. Based on the dynamic analyses, as cohesion factor in soil increases, bending moment, axial and shear forces of segments decrease but lining behavior of the tunnel is the same as static state. The results show that decreasing the overburden applied to lining caused by cementation is different in two static and dynamic states.
Abstract: Each year nearly nine hundred persons die in head injuries and over fifty thousand persons are severely injured due to non wearing of helmets. In motor cycle accidents, the human head is exposed to heavy impact loading against natural protection. In this work, an attempt has been made for analyzing the helmet with all the standard data. The simulation software ‘ANSYS’ is used to analyze the helmet with different conditions such as bottom fixed-load on top surface, bottom fixed -load on top line, side fixed –load on opposite surface, side fixed-load on opposite line and dynamic analysis. The maximum force of 19.5 kN is applied on the helmet to study the model in static and dynamic conditions. The simulation has been carried out for the static condition for the parameters like total deformation, strain energy, von-Mises stress for different cases. The dynamic analysis has been performed for the parameter like total deformation and equivalent elastic strain. The result shows that these values are concentrated in the retention portion of the helmet. These results have been compared with the standard experimental data proposed by the BIS and well within the acceptable limit.
Abstract: The controller is used to improve the dynamic performance of DC-DC converter by achieving a robust output voltage against load disturbances. This paper presents the performance of PI and Fuzzy controller for a phase- shifted zero-voltage switched full-bridge PWM (ZVS FB- PWM) converters with a closed loop control. The proposed converter is regulated with minimum overshoot and good stability. In this paper phase-shift control method is used as an effective tool to reduce switching losses and duty cycle losses. A 1kW/100KHz dc/dc converter is simulated and analyzed using MATLAB. The circuit is simulated for static and dynamic load (DC motor). It has been observed that performance of converter with fuzzy controller is better than that of PI controller. An efficiency comparison of the converter with a reported topology has also been carried out.
Abstract: Microgrids are increasingly being considered to provide electricity for the expanding energy demand in the grid distribution network and grid isolated areas. However, the technical challenges associated with the operation and controls are immense. Management of dynamic power balances, power flow, and network voltage profiles imposes unique challenges in the context of microgrids. Stability of the microgrid during both grid-connected and islanded mode is considered as the major challenge during its operation. Traditional control methods have been employed are based on the assumption of linear loads. For instance the concept of PQ, voltage and frequency control through decoupled PQ are some of very useful when considering linear loads, but they fall short when considering nonlinear loads. The deficiency of traditional control methods of microgrid suggests that more research in the control of microgrids should be done. This research aims at introducing the dq technique concept into decoupled PQ for dynamic load demand control in inverter interfaced DG system operating as isolated LV microgrid. Decoupled PQ in exact mathematical formulation in dq frame is expected to accommodate all variations of the line parameters (resistance and inductance) and to relinquish forced relationship between the DG variables such as power, voltage and frequency in LV microgrids and allow for individual parameter control (frequency and line voltages). This concept is expected to address and achieve accurate control, improve microgrid stability and power quality at all load conditions.
Abstract: Data replication in data grid systems is one of the important solutions that improve availability, scalability, and fault tolerance. However, this technique can also bring some involved issues such as maintaining replica consistency. Moreover, as grid environment are very dynamic some nodes can be more uploaded than the others to become eventually a bottleneck. The main idea of our work is to propose a complementary solution between replica consistency maintenance and dynamic load balancing strategy to improve access performances under a simulated grid environment.
Abstract: Load balancing in distributed computer systems is the
process of redistributing the work load among processors in the
system to improve system performance. Most of previous research in
using fuzzy logic for the purpose of load balancing has only
concentrated in utilizing fuzzy logic concepts in describing
processors load and tasks execution length. The responsibility of the
fuzzy-based load balancing process itself, however, has not been
discussed and in most reported work is assumed to be performed in a
distributed fashion by all nodes in the network. This paper proposes a
new fuzzy dynamic load balancing algorithm for homogenous
distributed systems. The proposed algorithm utilizes fuzzy logic in
dealing with inaccurate load information, making load distribution
decisions, and maintaining overall system stability. In terms of
control, we propose a new approach that specifies how, when, and by
which node the load balancing is implemented. Our approach is
called Centralized-But-Distributed (CBD).
Abstract: Series of experimental tests were conducted on a
section of a 660 kW wind turbine blade to measure the pressure
distribution of this model oscillating in plunging motion. In order to
minimize the amount of data required to predict aerodynamic loads
of the airfoil, a General Regression Neural Network, GRNN, was
trained using the measured experimental data. The network once
proved to be accurate enough, was used to predict the flow behavior
of the airfoil for the desired conditions.
Results showed that with using a few of the acquired data, the
trained neural network was able to predict accurate results with
minimal errors when compared with the corresponding measured
values. Therefore with employing this trained network the
aerodynamic coefficients of the plunging airfoil, are predicted
accurately at different oscillation frequencies, amplitudes, and angles
of attack; hence reducing the cost of tests while achieving acceptable
accuracy.
Abstract: The complex shape of the human pelvic bone was
successfully imaged and modeled using finite element FE processing.
The bone was subjected to quasi-static and dynamic loading
conditions simulating the effect of both weight gain and impact.
Loads varying between 500 – 2500 N (~50 – 250 Kg of weight) was
used to simulate 3D quasi-static weight gain. Two different 3D
dynamic analyses, body free fall at two different heights (1 and 2 m)
and forced side impact at two different velocities (20 and 40 Km/hr)
were also studied. The computed resulted stresses were compared for
the four loading cases, where Von Misses stresses increases linearly
with the weight gain increase under quasi-static loading. For the
dynamic models, the Von Misses stress history behaviors were
studied for the affected area and effected load with respect to time.
The normalization Von Misses stresses with respect to the applied
load were used for comparing the free fall and the forced impact load
results. It was found that under the forced impact loading condition
an over lapping behavior was noticed, where as for the free fall the
normalized Von Misses stresses behavior was found to nonlinearly
different. This phenomenon was explained through the energy
dissipation concept. This study will help designers in different
specialization in defining the weakest spots for designing different
supporting systems.
Abstract: Geosynthetics have proved to be suitable for
reinforced soil retaining walls. Based on the increasing uses of
geosynthetic reinforced soil systems in the regions, which bear
frequent earthquakes, the study of dynamic behavior of structures
seems necessary. Determining the reinforcement forces is; therefore,
one of the most important and main points of discussions in
designing retaining walls, by which we prevent from conservative
planning. Thus, this paper intended to investigate the effects of such
parameters as wall height, acceleration type, vertical spacing of
reinforcement, type of reinforcement and soil type on forces and
deformation through numerical modeling of the geosynthetic
reinforced soil retaining walls (GRSRW) under dynamic loading with
finite difference method by using FLAC. The findings indicate rather
positive results with each parameter.
Abstract: Hydrodynamic pressures acting on upstream of concrete dams during an earthquake are an important factor in designing and assessing the safety of these structures in Earthquake regions. Due to inherent complexities, assessing exact hydrodynamic pressure is only feasible for problems with simple geometry. In this research, the governing equation of concrete gravity dam reservoirs with effect of fluid viscosity in frequency domain is solved and then compared with that in which viscosity is assumed zero. The results show that viscosity influences the reservoir-s natural frequency. In excitation frequencies near the reservoir's natural frequencies, hydrodynamic pressure has a considerable difference in compare to the results of non-viscose fluid.