Abstract: Main objective of this paper is to establish a link
between inertial forces of the bearings used in construction of wind
power plant and its behavior. Using bearings with lower inertial
forces has the immediate effect of decreasing inertia rotor system,
with significant results in increased energy efficiency, due to
decreased friction forces between rollers and raceways. The F.E.M.
analysis shows the appearance of uniform contact stress at the ends of
the rollers, demonstrated the necessity of production of low mass
bearings. Favorable results are expected in the economic field, by
reducing material consumption and by increasing the durability of
bearings. Using low mass bearings with hollow rollers instead of
solid rollers has an impact on working temperature, on vibrations and
noise which decrease. Implementation of types of hollow rollers of
cylindrical tubular type, instead of expensive rollers with logarithmic
profile, will bring significant inertial forces decrease with large
benefits in behavior of wind power plant.
Abstract: Structure-borne noise is an important aspect of
offshore platform sound field. It can be generated either directly by
vibrating machineries induced mechanical force, indirectly by the
excitation of structure or excitation by incident airborne noise.
Therefore, limiting of the transmission of vibration energy
throughout the offshore platform is the key to control the structureborne
noise. This is usually done by introducing damping treatment
to the steel structures. Two types of damping treatment using onboard
are presented. By conducting a Statistical Energy Analysis
(SEA) simulation on a jack-up rig, the noise level in the source room,
the neighboring rooms, and remote living quarter cabins are
compared before and after the damping treatments been applied. The
results demonstrated that, in the source neighboring room and living
quarter area, there is a significant noise reduction with the damping
treatment applied, whereas in the source room where air-borne sound
predominates that of structure-borne sound, the impact is not
obvious. The conclusion on effective damping treatment in the
offshore platform is made which enable acoustic professionals to
implement noise control during the design stage for offshore crews’
hearing protection and habitant comfortability.
Abstract: Public space is essential to strengthen the social and
urban fabric and the social cohesion; there lies the importance of its
study. Hence, the aim of this paper is to analyze the quality of public
space in the XXI century in both quantitative and qualitative terms. In
this article, the concept of public space includes open spaces such as
parks, public squares and walking areas. To make this analysis, we
take Mexico City as the case study. It has a population of nearly 9
million inhabitants and is composed of sixteen boroughs. For this
analysis, we consider both existing public spaces and the government
intervention for building and improving new and existent public
spaces. Results show that on the one hand, quantitatively there is not
an equitable distribution of public spaces due to both the growth of
the city itself as well as due to the absence of political will to create
public spaces. Another factor is the evolution of this city, which has
been growing merely in a “patched pattern”, where public space has
played no role at all with a total absence of urban design. On the
other hand, qualitatively, even the boroughs with the most public
spaces have not shown interest in making these spaces qualitatively
inclusive and open to the general population aiming for integration.
Therefore, urban projects that privatize public space seem to be the
rule, rather than a rehabilitation effort of the existent public spaces.
Hence, state intervention should reinforce its role as an agent of
social change acting in benefit of the majority of the inhabitants with
the promotion of more inclusive public spaces.
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: In the present study, the properties of Al-Al2O3
nanocomposite hollow sphere structures were investigated. For this
reason, the Al-based nanocomposite hollow spheres with different
amounts of nano-alumina reinforcement (0-10wt %) and different
ratio of thickness to diameter (t/D: 0.06-0.3) were prepared via a
powder metallurgy method. Then, the effect of mentioned parameters
was studied on physical and quasi static mechanical properties of
their related prepared structures (open/closed cell) such as density,
hardness, strength, and energy absorption. It was found that, as the
t/D ratio increases the relative density, compressive strength and
energy absorption increase. The highest values of strength and energy
absorption were obtained from the specimen with 5 wt. % of
nanoparticle reinforcement, t/D of 0.3 (t=1 mm, D=400μm) as 22.88
MPa and 13.24 MJ/m3, respectively. The moderate specific strength
of prepared composites in the present study showed the good
consistency with the properties of others low carbon steel composite
with similar structure.
Abstract: In this paper, analysis of an infinite beam resting on
multilayer tensionless extensible geosynthetic reinforced granular
fill-poor soil system overlying soft soil strata under moving load with
constant velocity is presented. The beam is subjected to a
concentrated load moving with constant velocity. The upper
reinforced granular bed is modeled by a rough membrane embedded
in Pasternak shear layer overlying a series of compressible nonlinear
winkler springs representing the underlying the very poor soil. The
multilayer tensionless extensible geosynthetic layer has been
assumed to deform such that at interface the geosynthetic and the soil
have some deformation. Nonlinear behaviour of granular fill and the
very poor soil has been considered in the analysis by means of
hyperbolic constitutive relationships. Governing differential
equations of the soil foundation system have been obtained and
solved with the help of appropriate boundary conditions. The solution
has been obtained by employing finite difference method by means of
Gauss-Siedal iterative scheme. Detailed parametric study has been
conducted to study the influence of various parameters on the
response of soil–foundation system under consideration by means of
deflection and bending moment in the beam and tension mobilized in
the geosynthetic layer. These parameters include magnitude of
applied load, velocity of load, damping, ultimate resistance of poor
soil and granular fill layer. Range of values of parameters has been
considered as per Indian Railway conditions. This study clearly
observed that the comparisons of multilayer tensionless extensible
geosynthetic reinforcement with poor foundation soil and magnitude
of applied load, relative compressibility of granular fill and ultimate
resistance of poor soil has significant influence on the response of
soil–foundation system.
Abstract: Method of combined teaching laws of classical
mechanics and hydrostatics in non-inertial reference frames for
undergraduate students is proposed. Pressure distribution in a liquid
(or gas) moving with acceleration is considered. Combined effect of
hydrostatic force and force of inertia on a body immersed in a liquid
can lead to paradoxical results, in a motion of pendulum in particular.
The body motion under Stokes force influence and forces in rotating
reference frames are investigated as well. Problems and difficulties in
student perceptions are analyzed.
Abstract: Tool, Die and Mould-making (TDM) firms have been
known to play a pivotal role in the growth and development of the
manufacturing sectors in most economies. Their output contributes
significantly to the quality, cost and delivery speed of final
manufactured parts. Unfortunately, the South African Tool, Die and
Mould-making manufacturers have not been competing on the local
or global market in a significant way. This reality has hampered the
productivity and growth of the sector thus attracting intervention. The
paper explores the shortcomings South African toolmakers have to
overcome to restore their competitive position globally. Results from
a global benchmarking survey on the tooling sector are used to
establish a roadmap of what South African toolmakers can do to
become a productive, World Class force on the global market.
Abstract: The purpose of this article is to make an approach to
the Security Studies, exposing their theories and concepts to
understand the role that they have had in the interpretation of the
changes and continuities of the world order and their impact on
policies in facing the problems of the 21st century. The aim is to
build a bridge between the security studies as a subfield and the
meaning that has been given to the world order. The idea of epistemic
communities serves as a methodological proposal for the different
programs of research in security studies, showing their influence in
the realities of States, intergovernmental organizations and
transnational forces, moving to implement, perpetuate and project a
vision of the world order.
Abstract: This article presents a vibration diagnostic method
designed for Permanent Magnets (PM) electrical machines–traction
motors and generators. Those machines are commonly used in traction
drives of electrical vehicles and small wind or water systems. The
described method is very innovative and unique. Specific structural
properties of machines excited by permanent magnets are used in this
method - electromotive force (EMF) generated due to vibrations. There
was analyzed number of publications, which describe vibration
diagnostic methods, and tests of electrical machines and there was no
method found to determine the technical condition of such machine
basing on their own signals. This work presents field-circuit model,
results of static tests, results of calculations and simulations.
Abstract: In this paper, we provided a literature survey on the
artificial stock problem (ASM). The paper began by exploring the
complexity of the stock market and the needs for ASM. ASM
aims to investigate the link between individual behaviors (micro
level) and financial market dynamics (macro level). The variety of
patterns at the macro level is a function of the AFM complexity. The
financial market system is a complex system where the relationship
between the micro and macro level cannot be captured analytically.
Computational approaches, such as simulation, are expected to
comprehend this connection. Agent-based simulation is a simulation
technique commonly used to build AFMs. The paper proceeds by
discussing the components of the ASM. We consider the roles
of behavioral finance (BF) alongside the traditionally risk-averse
assumption in the construction of agent’s attributes. Also, the
influence of social networks in the developing of agents interactions is
addressed. Network topologies such as a small world, distance-based,
and scale-free networks may be utilized to outline economic
collaborations. In addition, the primary methods for developing
agents learning and adaptive abilities have been summarized.
These incorporated approach such as Genetic Algorithm, Genetic
Programming, Artificial neural network and Reinforcement Learning.
In addition, the most common statistical properties (the stylized facts)
of stock that are used for calibration and validation of ASM are
discussed. Besides, we have reviewed the major related previous
studies and categorize the utilized approaches as a part of these
studies. Finally, research directions and potential research questions
are argued. The research directions of ASM may focus on the macro
level by analyzing the market dynamic or on the micro level by
investigating the wealth distributions of the agents.
Abstract: Currently there are many use of threaded reinforcing
bars in construction fields because those do not need additional screw
processing when connecting reinforcing bar by threaded coupler. In
this study, reinforced concrete bridge piers using threaded rebar
coupler system at the plastic hinge area were tested to evaluate seismic
performance. The test results showed that threads of the threaded rebar
coupler system could be loosened while under tension-compression
cyclic loading because tolerance and rib face angle of a threaded rebar
coupler system are greater than that of a conventional ribbed rebar
coupler system. As a result, cracks were concentrated just outside of
the mechanical coupler and stiffness of reinforced concrete bridge pier
decreased. Therefore, it is recommended that connection ratio of
mechanical couplers in one section shall be below 50% in order that
cracks are not concentrated just outside of the mechanical coupler.
Also, reduced stiffness of the specimen should be considered when
using the threaded rebar coupler system.
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: The Composite Shear Walls (CSW) with steel encased
profiles can be used as lateral-load resisting systems for buildings
that require considerable large lateral-load capacity. The aim of this
work is to propose the experimental work conducted on CSW having
L section folded plate (L shape steel made-up sections) as
longitudinal reinforcement in boundary regions. The study in this
paper present the experimental test conducted on CSW having L
section folded plate as longitudinal reinforcement in boundary
regions. The tested 1/3 geometric scaled CSW has aspect ratio of 3.2.
L-shape structural steel materials with 2L-19x57x7mm dimensions
were placed in shear wall boundary zones. The seismic behavior of
CSW test specimen was investigated by evaluating and interpreting
the hysteresis curves, envelope curves, rigidity and consumed energy
graphs of this tested element. In addition to this, the experimental
results, deformation and cracking patterns were evaluated, interpreted
and suggestions of the design recommendations were proposed.
Abstract: The current paper presents an extensive bottom-up
framework for assessing building sector-specific vulnerability to
climate change: energy supply and demand. The research focuses on
the application of downscaled seasonal models for estimating energy
performance of buildings in Greece. The ARW-WRF model has
been set-up and suitably parameterized to produce downscaled
climatological fields for Greece, forced by the output of the CFSv2
model. The outer domain, D01/Europe, included 345 x 345 cells of
horizontal resolution 20 x 20 km2 and the inner domain, D02/Greece,
comprised 180 x 180 cells of 5 x 5 km2 horizontal resolution. The
model run has been setup for a period with a forecast horizon of 6
months, storing outputs on a six hourly basis.
Abstract: The goal of this paper is to present the diagnostic
contribution that the screening instrument, Mini-Mental State
Examination-2: Expanded Version (MMSE-2:EV), brings in
detecting the cognitive impairment or in monitoring the progress of
degenerative disorders. The diagnostic signification is underlined by
the interpretation of the MMSE-2:EV scores, resulted from the test
application to patients with mild and major neurocognitive disorders.
The cases were selected from current practice, in order to cover vast
and significant neurocognitive pathology: mild cognitive impairment,
Alzheimer’s disease, vascular dementia, mixed dementia, Parkinson’s
disease, conversion of the mild cognitive impairment into
Alzheimer’s disease. The MMSE-2:EV version was used: it was
applied one month after the initial assessment, three months after the
first reevaluation and then every six months, alternating the blue and
red forms. Correlated with age and educational level, the raw scores
were converted in T scores and then, with the mean and the standard
deviation, the z scores were calculated. The differences of raw scores
between the evaluations were analyzed from the point of view of
statistic signification, in order to establish the progression in time of
the disease. The results indicated that the psycho-diagnostic approach
for the evaluation of the cognitive impairment with MMSE-2:EV is
safe and the application interval is optimal. In clinical settings with a
large flux of patients, the application of the MMSE-2:EV is a safe
and fast psychodiagnostic solution. The clinicians can draw objective
decisions and for the patients: it does not take too much time and
energy, it does not bother them and it doesn’t force them to travel
frequently.
Abstract: In recent years, fire accidents have been steadily
increased and the amount of property damage caused by the accidents
has gradually raised. Damaging building structure, fire incidents bring
about not only such property damage but also strength degradation and
member deformation. As a result, the building structure undermines its
structural ability. Examining the degradation and the deformation is
very important because reusing the building is more economical than
reconstruction. Therefore, engineers need to investigate the strength
degradation and member deformation well, and make sure that they
apply right rehabilitation methods. This study aims at evaluating
deformation characteristics of fire damaged and rehabilitated normal
strength concrete beams through both experiments and finite element
analyses. For the experiments, control beams, fire damaged beams and
rehabilitated beams are tested to examine deformation characteristics.
Ten test beam specimens with compressive strength of 21MPa are
fabricated and main test variables are selected as cover thickness of
40mm and 50mm and fire exposure time of 1 hour or 2 hours. After
heating, fire damaged beams are air-recurred for 2 months and
rehabilitated beams are repaired with polymeric cement mortar after
being removed the fire damaged concrete cover. All beam specimens
are tested under four points loading. FE analyses are executed to
investigate the effects of main parameters applied to experimental
study. Test results show that both maximum load and stiffness of the
rehabilitated beams are higher than those of the fire damaged beams.
In addition, predicted structural behaviors from the analyses also show
good rehabilitation effect and the predicted load-deflection curves are
similar to the experimental results. For the further, the proposed
analytical method can be used to predict deformation characteristics of
fire damaged and rehabilitated concrete beams without suffering from
time and cost consuming of experimental process.
Abstract: This paper presents the experimental investigation on
the bond behavior of geo polymer concrete. The bond behavior of
geo polymer concrete cubes of grade M35 reinforced with 16 mm
TMT rod is analyzed. The results indicate that the bond performance
of reinforced geo polymer concrete is good and thus proves its
application for construction.
Abstract: In recent years, honeycomb fiber reinforced plastic
(FRP) sandwich panels have been increasingly used in various
industries. Low weight, low price and high mechanical strength are
the benefits of these structures. However, their mechanical properties
and behavior have not been fully explored. The objective of this
study is to conduct a combined numerical-statistical investigation of
honeycomb FRP sandwich beams subject to torsion load. In this
paper, the effect of geometric parameters of sandwich panel on
maximum shear strain in both face and core and angle of torsion in a
honeycomb FRP sandwich structures in torsion is investigated. The
effect of Parameters including core thickness, face skin thickness,
cell shape, cell size, and cell thickness on mechanical behavior of the
structure were numerically investigated. Main effects of factors were
considered in this paper and regression equations were derived.
Taguchi method was employed as experimental design and an
optimum parameter combination for the maximum structure stiffness
has been obtained. The results showed that cell size and face skin
thickness have the most significant impacts on torsion angle,
maximum shear strain in face and core.
Abstract: These Monolayer and multilayer coatings of CrN and
AlCrN deposited on 100Cr6 (AISI 52100) substrate by PVD
magnetron sputtering system. The microstructures of the coatings
were characterized using atomic force microscopy (AFM). The AFM
analysis revealed the presence of domes and craters that are
uniformly distributed over all surfaces of the various layers.
Nanoindentation measurement of CrN coating showed maximum
hardness (H) and modulus (E) of 14 GPa and 190 GPa, respectively.
The measured H and E values of AlCrN coatings were found to be 30
GPa and 382 GPa, respectively. The improved hardness in both the
coatings was attributed mainly to a reduction in crystallite size and
decrease in surface roughness. The incorporation of Al into the CrN
coatings has improved both hardness and Young’s modulus.