Abstract: Systems for detection of damages in railway pantographs effectively reduce the cost of maintenance and improve time scheduling. In this paper, we present an approach to design a monitoring tool fitting strong customer requirements such as portability and ease of use. Pantograph has been modeled to estimate its dynamical properties, since no data are available. With the aim to focus on suspensions health, a two Degrees of Freedom (DOF) scheme has been adopted. Parameters have been calculated by means of analytical dynamics. A Finite Element Method (FEM) modal analysis verified the former model with an acceptable error. The detection strategy seeks phase-plots topology alteration, induced by defects. In order to test the suitability of the method, leakage in the dashpot was simulated on the lumped model. Results are interesting because changes in phase plots are more appreciable than frequency-shift. Further calculations as well as experimental tests will support future developments of this smart strategy.
Abstract: Knowledge and IT inputs to other industrial production have become more important as a key factor for the competitiveness of national and regional economies, such as knowledge economies in smart cities. Knowledge and IT industries lead the industrial innovation and technical (r)evolution through low cost, high efficiency in production, and by creating a new value chain and new production path chains, which is referred as knowledge and IT dynamics. This study aims to investigate the knowledge and IT dynamics in Korea, which are analyzed through the input-output model and structural path analysis. Twenty-eight industries were reclassified into seven categories; Agriculture and Mining, IT manufacture, Non-IT manufacture, Construction, IT-service, Knowledge service, Non-knowledge service to take close look at the knowledge and IT dynamics. Knowledge and IT dynamics were analyzed through the change of input output coefficient and multiplier indices in terms of technical innovation, as well as the changes of the structural paths of the knowledge and IT to other industries in terms of new production value creation from 1985 and 2010. The structural paths of knowledge and IT explain not only that IT foster the generation, circulation and use of knowledge through IT industries and IT-based service, but also that knowledge encourages IT use through creating, sharing and managing knowledge. As a result, this paper found the empirical investigation on the knowledge and IT dynamics of the Korean economy. Knowledge and IT has played an important role regarding the inter-industrial transactional input for production, as well as new industrial creation. The birth of the input-output production path has mostly originated from the knowledge and IT industries, while the death of the input-output production path took place in the traditional industries from 1985 and 2010. The Korean economy has been in transition to a knowledge economy in the Smart City.
Abstract: In this paper, a drift assist control system is proposed for remote control (RC) cars to get the perfect drift angle. A steering servo control scheme is given powerfully to assist the drift driving. A gyroscope sensor is included to detect the machine's tail sliding and to achieve a better automatic counter-steering to prevent RC car from spinning. To analysis tire traction and vehicle dynamics is used to obtain the dynamic track of RC cars. It comes with a control gain to adjust counter-steering amount according to the sensor condition. An illustrated example of 1:10 RC drift car is given and the real-time control algorithm is realized by Arduino Uno.
Abstract: Belt conveyors play an important role in continuous dry bulk material transport, especially at the mining industry. Speed control is expected to reduce the energy consumption of belt conveyors. Transient operation is the operation of increasing or decreasing conveyor speed for speed control. According to literature review, current research rarely takes the conveyor dynamics in transient operation into account. However, in belt conveyor speed control, the conveyor dynamic behaviors are significantly important since the poor dynamics might result in risks. In this paper, the potential risks in transient operation will be analyzed. An existing finite element model will be applied to build a conveyor model, and simulations will be carried out to analyze the conveyor dynamics. In order to realize the soft speed regulation, Harrison’s sinusoid acceleration profile will be applied, and Lodewijks estimator will be built to approximate the required acceleration time. A long inclined belt conveyor will be studied with two major simulations. The conveyor dynamics will be given.
Abstract: This paper demonstrates the use of a method of synthesizing process flowsheets using a graphical tool called the GH-plot and in particular, to look at how it can be used to compare the reactions of a combined simultaneous process with regard to their thermodynamics. The technique uses fundamental thermodynamic principles to allow the mass, energy and work balances locate the attainable region for chemical processes in a reactor. This provides guidance on what design decisions would be best suited to developing new processes that are more effective and make lower demands on raw material and energy usage.
Abstract: In population dynamics the study of both, the
abundance and the spatial distribution of the populations in a
given habitat, is a fundamental issue a From ecological point of
view, the determination of the factors influencing such changes
involves important problems. In this paper a mathematical model to
describe the temporal dynamic and the spatiotemporal dynamic of the
interaction of three populations (pollinators, plants and herbivores) is
presented. The study we present is carried out by stages: 1. The
temporal dynamics and 2. The spatio-temporal dynamics. In turn,
each of these stages is developed by considering three cases which
correspond to the dynamics of each type of interaction. For instance,
for stage 1, we consider three ODE nonlinear systems describing
the pollinator-plant, plant-herbivore and plant-pollinator-herbivore,
interactions, respectively. In each of these systems different types of
dynamical behaviors are reported. Namely, transcritical and pitchfork
bifurcations, existence of a limit cycle, existence of a heteroclinic
orbit, etc. For the spatiotemporal dynamics of the two mathematical
models a novel factor are introduced. This consists in considering
that both, the pollinators and the herbivores, move towards those
places of the habitat where the plant population density is high.
In mathematical terms, this means that the diffusive part of the
pollinators and herbivores equations depend on the plant population
density. The analysis of this part is presented by considering pairs of
populations, i. e., the pollinator-plant and plant-herbivore interactions
and at the end the two mathematical model is presented, these models
consist of two coupled nonlinear partial differential equations of
reaction-diffusion type. These are defined on a rectangular domain
with the homogeneous Neumann boundary conditions. We focused
in the role played by the density dependent diffusion term into
the coexistence of the populations. For both, the temporal and
spatio-temporal dynamics, a several of numerical simulations are
included.
Abstract: In the situation of great acceleration of changes and the need for new developments in the cities on one hand and conservation and regeneration approaches on the other hand, place identity and its relation with heritage context have taken on new importance. This relation is generally mutual and complex one. The significant point in this relation is that the process of identifying something as heritage rather than just historical phenomena, brings that which may be inherited into the realm of identity. In planning and urban design as well as environmental psychology and phenomenology domain, place identity and its attributes and components were studied and discussed. However, the relation between physical environment (especially heritage) and identity has been neglected in the planning literature. This article aims to review the knowledge on this field and develop a model on the influence and relation of these two major concepts (heritage and identity). To build this conceptual model, we draw on available literature in environmental psychology as well as planning on place identity and heritage environment using a descriptive-analytical methodology to understand how they can inform the planning strategies and governance policies. A cross-disciplinary analysis is essential to understand the nature of place identity and heritage context and develop a more holistic model of their relationship in order to be employed in planning process and decision making. Moreover, this broader and more holistic perspective would enable both social scientists and planners to learn from one another’s expertise for a fuller understanding of community dynamics. The result indicates that a combination of these perspectives can provide a richer understanding—not only of how planning impacts our experience of place, but also how place identity can impact community planning and development.
Abstract: Graphene, a single-atom sheet, has been considered as
the most promising material for making future nanoelectromechanical
systems as well as purely electrical switching with graphene
transistors. Graphene-based devices have advantages in scaled-up
device fabrication due to the recent progress in large area graphene
growth and lithographic patterning of graphene nanostructures. Here
we investigated its mechanical responses of circular graphene
nanoflake under the nanoindentation using classical molecular
dynamics simulations. A correlation between the load and the
indentation depth was constructed. The nanoindented force in this
work was applied to the center point of the circular graphene nanoflake
and then, the resonance frequency could be tuned by a nanoindented
depth. We found the hardening or the softening of the graphene
nanoflake during its nanoindented-deflections, and such properties
were recognized by the shift of the resonance frequency. The
calculated mechanical parameters in the force-vs-deflection plot were
in good agreement with previous experimental and theoretical works.
This proposed schematics can detect the pressure via the deflection
change or/and the resonance frequency shift, and also have great
potential for versatile applications in nanoelectromechanical systems.
Abstract: Due to the interference effects, the intrinsic
aerodynamic parameters obtained from the individual component
testing are always fundamentally different than those obtained for
complete model testing. Consideration and limitation for such testing
need to be taken into account in any design work related to the
component buildup method. In this paper, the scaled model of a
straight rectangular canard of a hybrid buoyant aircraft is tested at 50
m/s in IIUM-LSWT (Low Speed Wind Tunnel). Model and its
attachment with the balance are kept rigid to have results free from
the aeroelastic distortion. Based on the velocity profile of the test
section’s floor; the height of the model is kept equal to the
corresponding boundary layer displacement. Balance measurements
provide valuable but limited information of overall aerodynamic
behavior of the model. Zero lift coefficient is obtained at -2.2o and
the corresponding drag coefficient was found to be less than that at
zero angle of attack. As a part of the validation of low fidelity tool,
plot of lift coefficient plot was verified by the experimental data and
except the value of zero lift coefficients, the overall trend has under
predicted the lift coefficient. Based on this comparative study, a
correction factor of 1.36 is proposed for lift curve slope obtained
from the panel method.
Abstract: The spindle system is one of the most important
components of machine tool. The dynamic properties of the spindle
affect the machining productivity and quality of the work pieces.
Thus, it is important and necessary to determine its dynamic
characteristics of spindles in the design and development in order to
avoid forced resonance. The finite element method (FEM) has been
adopted in order to obtain the dynamic behavior of spindle system.
For this reason, obtaining the Campbell diagrams and determining the
critical speeds are very useful to evaluate the spindle system
dynamics. The unbalance response of the system to the center of
mass unbalance at the cutting tool is also calculated to investigate the
dynamic behavior. In this paper, we used an ANSYS Parametric
Design Language (APDL) program which based on finite element
method has been implemented to make the full dynamic analysis and
evaluation of the results. Results show that the calculated critical
speeds are far from the operating speed range of the spindle, thus, the
spindle would not experience resonance, and the maximum
unbalance response at operating speed is still with acceptable limit.
ANSYS Parametric Design Language (APDL) can be used by spindle
designer as tools in order to increase the product quality, reducing
cost, and time consuming in the design and development stages.
Abstract: Propagation of arbitrary amplitude nonlinear Alfven
waves has been investigated in low but finite β electron-positron-ion
plasma including full ion dynamics. Using Sagdeev pseudopotential
method an energy integral equation has been derived. The Sagdeev
potential has been calculated for different plasma parameters and it
has been shown that inclusion of ion parallel motion along the
magnetic field changes the nature of slow shear Alfven wave solitons
from dip type to hump type. The effects of positron concentration,
plasma-β and obliqueness of the wave propagation on the solitary
wave structure have also been examined.
Abstract: This paper presents modeling and simulation of
flexible robot in an underwater environment. The underwater
environment completely contrasts with ground or space environment.
The robot in an underwater situation is subjected to various dynamic
forces like buoyancy forces, hydrostatic and hydrodynamic forces.
The underwater robot is modeled as Rayleigh beam. The developed
model further allows estimating the deflection of tip in two
directions. The complete dynamics of the underwater robot is
analyzed, which is the main focus of this investigation. The control of
robot trajectory is not discussed in this paper. Simulation is
performed using Symbol Shakti software.
Abstract: Acoustic properties of polymeric liquids are high
sensitive to free gas traces in the form of fine bubbles. Their presence
is typical for such liquids because of chemical reactions, small
wettability of solid boundaries, trapping of air in technological
operations, etc. Liquid temperature influences essentially its
rheological properties, which may have an impact on the bubble
pulsations and sound propagation in the system. The target of the
paper is modeling of the liquid temperature effect on single bubble
dynamics and sound dispersion and attenuation in polymeric solution
with spherical gas bubbles. The basic sources of attenuation (heat
exchange between gas in microbubbles and surrounding liquid,
rheological and acoustic losses) are taken into account. It is supposed
that in the studied temperature range the interface mass transfer has a
minor effect on bubble dynamics. The results of the study indicate
that temperature raise yields enhancement of bubble pulsations and
increase in sound attenuation in the near-resonance range and may
have a strong impact on sound dispersion in the liquid-bubble
mixture at frequencies close to the resonance frequency of bubbles.
Abstract: We used live E. coli containing synthetic genetic
oscillators to study how the degree of synchrony between the genetic
circuits of sister cells changes with temperature. We found that both
the mean and the variability of the degree of synchrony between the
fluorescence signals from sister cells are affected by temperature.
Also, while most pairs of sister cells were found to be highly
synchronous in each condition, the number of asynchronous pairs
increased with increasing temperature, which was found to be due to
disruptions in the oscillations. Finally we provide evidence that these
disruptions tend to affect multiple generations as opposed to
individual cells. These findings provide insight in how to design
more robust synthetic circuits and in how cell division can affect their
dynamics.
Abstract: Boiling process is characterized by the rapid
formation of vapour bubbles at the solid–liquid interface (nucleate
boiling) with pre-existing vapour or gas pockets. Computational fluid
dynamics (CFD) is an important tool to study bubble dynamics. In
the present study, CFD simulation has been carried out to determine
the bubble detachment diameter and its terminal velocity. Volume of
fluid method is used to model the bubble and the surrounding by
solving single set of momentum equations and tracking the volume
fraction of each of the fluids throughout the domain. In the
simulation, bubble is generated by allowing water-vapour to enter a
cylinder filled with liquid water through an inlet at the bottom. After
the bubble is fully formed, the bubble detaches from the surface and
rises up during which the bubble accelerates due to the net balance
between buoyancy force and viscous drag. Finally when these forces
exactly balance each other, it attains a constant terminal velocity. The
bubble detachment diameter and the terminal velocity of the bubble
are captured by the monitor function provided in FLUENT. The
detachment diameter and the terminal velocity obtained are compared
with the established results based on the shape of the bubble. A good
agreement is obtained between the results obtained from simulation
and the equations in comparison with the established results.
Abstract: This paper presents dynamic models of distributed
generators (DG) and investigates dynamic behavior of the DG units
in the micro grid system. The DG units include photovoltaic and fuel
cell sources. The voltage source inverter is adopted since the
electronic interface which can be equipped with its controller to keep
stability of the micro grid during small signal dynamics. This paper
also introduces power management strategies and implements the DG
load sharing concept to keep the micro grid operation in gridconnected
and islanding modes of operation. The results demonstrate
the operation and performance of the photovoltaic and fuel cell as
distributed generators in a micro grid. The entire control system in
the micro grid is developed by combining the benefits of the power
control and the voltage control strategies. Simulation results are all
reported, confirming the validity of the proposed control technique.
Abstract: We investigate relaxation dynamics of a quantum
dipole emitter (QDE), e.g., a molecule or quantum dot, located near a
metal nanoparticle (MNP) exhibiting a dipolar localized surface
plasmon (LSP) resonance at the frequency of the QDE radiative
transition. It is shown that under the condition of the QDE-MNP
characteristic relaxation time being much shorter than that of the
QDE in free-space but much longer than the LSP lifetime. It is also
shown that energy dissipation in the QDE-MNP system is relatively
weak with the probability of the photon emission being about 0.75, a
number which, rather surprisingly, does not explicitly depend on the
metal absorption characteristics. The degree of entanglement
measured by the concurrency takes the maximum value, while the
distances between the QDEs and metal ball approximately are equal.
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: In a multi-cultural learning context, where ties are
weak and dynamic, combining qualitative with quantitative research
methods may be more effective. Such a combination may also allow
us to answer different types of question, such as about people’s
perception of the network. In this study the use of observation,
interviews and photos were explored as ways of enhancing data from
social network questionnaires. Integrating all of these methods was
found to enhance the quality of data collected and its accuracy, also
providing a richer story of the network dynamics and the factors that
shaped these changes over time.
Abstract: Bir El Djir is an important coastal township in Oran
department, located at 450 Km far away from Algiers on northwest of
Algeria. In this coastal area, the urban sprawl is one of the main
problems that reduce the limited highly fertile land. So, using the
remote sensing and GIS technologies have shown their great
capabilities to solve many earth resources issues.
The aim of this study is to produce land use and cover map for the
studied area at varied periods to monitor possible changes that may
occurred, particularly in the urban areas and subsequently predict
likely changes. For this, two spatial images SPOT and Landsat
satellites from 1987 and 2014 respectively were used to assess the
changes of urban expansion and encroachment during this period
with photo-interpretation and GIS approach.
The results revealed that the town of Bir El Djir has shown a
highest growth rate in the period 1987-2014 which is 1201.5 hectares
in terms of area. These expansions largely concern the new real estate
constructions falling within the social and promotional housing
programs launched by the government.
The most urban expansion is characterized by the new
construction in the form of spontaneous or peripheral precarious
habitat, but also unstructured slums settled especially in the
southeastern part of town.