Abstract: We propose a downlink multiple-input multipleoutput
(MIMO) multi-carrier code division multiple access (MCCDMA)
system with adaptive beamforming algorithm for smart
antennas. The algorithm used in this paper is based on the Least
Mean Square (LMS), with pilot channel estimation (PCE) and the
zero forcing equalizer (ZFE) in the receiver, requiring reference
signal and no knowledge channel. MC-CDMA is studied in a
multiple antenna context in order to efficiently exploit robustness
against multipath effects and multi-user flexibility of MC-CDMA and
channel diversity offered by MIMO systems for radio mobile
channels. Computer simulations, considering multi-path Rayleigh
Fading Channel, interference inter symbol and interference are
presented to verify the performance. Simulation results show that the
scheme achieves good performance in a multi-user system.
Abstract: Increasing energy absorption is a significant parameter
in vehicle design. Absorbing more energy results in decreasing
occupant damage. Limitation of the deflection in a side impact results
in decreased energy absorption (SEA) and increased peak load (PL).
Hence a high crash force jeopardizes passenger safety and vehicle
integrity. The aims of this paper are to determine suitable dimensions
and material of a square beam subjected to side impact, in order to
maximize SEA and minimize PL. To achieve this novel goal, the
geometric parameters of a square beam are optimized using the
response surface method (RSM).multi-objective optimization is
performed, and the optimum design for different response features is
obtained.
Abstract: The dental composites are preferably used as filling
materials due to their esthetic appearances. Nevertheless one of the
major problems, during the application of the dental composites, is
shape change named as “polymerisation shrinkage" affecting clinical
success of the dental restoration while photo-polymerisation.
Polymerisation shrinkage of composites arises basically from the
formation of a polymer due to the monomer transformation which
composes of an organic matrix phase. It was sought, throughout this
study, to detect and evaluate the structural polymerisation shrinkage
of prepared dental composites in order to optimize the effects of
various fillers included in hydroxyapatite (HA)-reinforced dental
composites and hence to find a means to modify the properties of
these dental composites prepared with defined parameters. As a
result, the shrinkage values of the experimental dental composites
were decreased by increasing the filler content of composites and the
composition of different fillers used had effect on the shrinkage of
the prepared composite systems.
Abstract: The flow field and the motion of the free surface in an
oscillating container are simulated numerically to assess the numerical
approach for studying two-phase flows under oscillating conditions.
Two numerical methods are compared: one is to model the oscillating
container directly using the moving grid of the ALE method, and the
other is to simulate the effect of container motion using the oscillating
body force acting on the fluid in the stationary container. The
two-phase flow field in the container is simulated using the level set
method in both cases. It is found that the calculated results by the body
force method coinsides with those by the moving grid method and the
sloshing behavior is predicted well by both the methods. Theoretical
back ground and limitation of the body force method are discussed,
and the effects of oscillation amplitude and frequency are shown.
Abstract: The policies governing the business of any
organization are well reflected in her business rules. The business
rules are implemented by data validation techniques, coded during
the software development process. Any change in business
policies results in change in the code written for data validation
used to enforce the business policies. Implementing the change in
business rules without changing the code is the objective of this
paper. The proposed approach enables users to create rule sets at
run time once the software has been developed. The newly defined
rule sets by end users are associated with the data variables for
which the validation is required. The proposed approach facilitates
the users to define business rules using all the comparison
operators and Boolean operators. Multithreading is used to
validate the data entered by end user against the business rules
applied. The evaluation of the data is performed by a newly
created thread using an enhanced form of the RPN (Reverse Polish
Notation) algorithm.
Abstract: A special case of floating point data representation is block
floating point format where a block of operands are forced to have a joint
exponent term. This paper deals with the finite wordlength properties of
this data format. The theoretical errors associated with the error model for
block floating point quantization process is investigated with the help of error
distribution functions. A fast and easy approximation formula for calculating
signal-to-noise ratio in quantization to block floating point format is derived.
This representation is found to be a useful compromise between fixed point
and floating point format due to its acceptable numerical error properties over
a wide dynamic range.
Abstract: This research simulates one of the natural phenomena,
the ocean wave. Our goal is to be able to simulate the ocean wave at
real-time rate with the water surface interacting with objects. The
wave in this research is calm and smooth caused by the force of the
wind above the ocean surface. In order to make the simulation of the
wave real-time, the implementation of the GPU and the
multithreading techniques are used here. Based on the fact that the
new generation CPUs, for personal computers, have multi cores, they
are useful for the multithread. This technique utilizes more than one
core at a time. This simulation is programmed by C language with
OpenGL. To make the simulation of the wave look more realistic, we
applied an OpenGL technique called cube mapping (environmental
mapping) to make water surface reflective and more realistic.
Abstract: In this study, some physical and mechanical properties
of jujube fruits, were measured and compared at constant moisture
content of 15.5% w.b. The results showed that the mean length, width
and thickness of jujube fruits were 18.88, 16.79 and 15.9 mm,
respectively. The mean projected areas of jujube perpendicular to
length, width, and thickness were 147.01, 224.08 and 274.60 mm2,
respectively. The mean mass and volume were 1.51 g and 2672.80
mm3, respectively. The arithmetic mean diameter, geometric mean
diameter and equivalent diameter varied from 14.53 to 20 mm, 14.5
to 19.94 mm, and 14.52 to 19.97 mm, respectively. The sphericity,
aspect ratio and surface area of jujube fruits were 0.91, 0.89 and
926.28 mm2, respectively. Whole fruit density, bulk density and
porosity of jujube fruits were measured and found to be 1.52 g/cm3,
0.3 g/cm3 and 79.3%, respectively. The angle of repose of jujube fruit
was 14.66° (±0.58°). The static coefficient of friction on galvanized
iron steel was higher than that on plywood and lower than that on
glass surface. The values of rupture force, deformation, hardness and
energy absorbed were found to be between 11.13-19.91N, 2.53-
4.82mm, 3.06-5.81N mm and 20.13-39.08 N/mm, respectively.
Abstract: This paper proposes a method that discovers time series event patterns from textual data with time information. The patterns are composed of sequences of events and each event is extracted from the textual data, where an event is characteristic content included in the textual data such as a company name, an action, and an impression of a customer. The method introduces 7 types of time constraints based on the analysis of the textual data. The method also evaluates these constraints when the frequency of a time series event pattern is calculated. We can flexibly define the time constraints for interesting combinations of events and can discover valid time series event patterns which satisfy these conditions. The paper applies the method to daily business reports collected by a sales force automation system and verifies its effectiveness through numerical experiments.
Abstract: The essentiality of maintenance assessment and
maintenance optimization in design stage is analyzed, and the existent
problems of conventional maintenance design method are illuminated.
MDMVM (Maintenance Design Method based Virtual Maintenance)
is illuminated, and the process of MDMVM established, and the
MDMVM architecture is given out. The key techniques of MDMVM
are analyzed, and include maintenance design based KBE (Knowledge
Based Engineering) and virtual maintenance based physically
attribute. According to physical property, physically based modeling,
visual object movement control, the simulation of operation force and
maintenance sequence planning method are emphatically illuminated.
Maintenance design system based virtual maintenance is established in
foundation of maintenance design method.
Abstract: The inherent complexity in nowadays- business
environments is forcing organizations to be attentive to the dynamics
in several fronts. Therefore, the management of technological
innovation is continually faced with uncertainty about the future.
These issues lead to a need for a systemic perspective, able to analyze
the consequences of interactions between different factors. The field
of technology foresight has proposed methods and tools to deal with
this broader perspective. In an attempt to provide a method to analyze
the complex interactions between events in several areas, departing
from the identification of the most strategic competencies, this paper
presents a methodology based on the Delphi method and Quality
Function Deployment. This methodology is applied in a sheet metal
processing equipment manufacturer, as a case study.
Abstract: This paper analyses the unsteady, two-dimensional
stagnation point flow of an incompressible viscous fluid over a flat
sheet when the flow is started impulsively from rest and at the same
time, the sheet is suddenly stretched in its own plane with a velocity
proportional to the distance from the stagnation point. The partial
differential equations governing the laminar boundary layer forced
convection flow are non-dimensionalised using semi-similar
transformations and then solved numerically using an implicit finitedifference
scheme known as the Keller-box method. Results
pertaining to the flow and heat transfer characteristics are computed
for all dimensionless time, uniformly valid in the whole spatial region
without any numerical difficulties. Analytical solutions are also
obtained for both small and large times, respectively representing the
initial unsteady and final steady state flow and heat transfer.
Numerical results indicate that the velocity ratio parameter is found
to have a significant effect on skin friction and heat transfer rate at
the surface. Furthermore, it is exposed that there is a smooth
transition from the initial unsteady state flow (small time solution) to
the final steady state (large time solution).
Abstract: The present paper concerns with the influence of fiber
packing on the transverse plastic properties of metal matrix
composites. A micromechanical modeling procedure is used to
predict the effective mechanical properties of composite materials at
large tensile and compressive deformations. Microstructure is
represented by a repeating unit cell (RUC). Two fiber arrays are
considered including ideal square fiber packing and random fiber
packing defined by random sequential algorithm. The
micromechanical modeling procedure is implemented for
graphite/aluminum metal matrix composite in which the
reinforcement behaves as elastic, isotropic solids and the matrix is
modeled as an isotropic elastic-plastic solid following the von Mises
criterion with isotropic hardening and the Ramberg-Osgood
relationship between equivalent true stress and logarithmic strain.
The deformation is increased to a considerable value to evaluate both
elastic and plastic behaviors of metal matrix composites. The yields
strength and true elastic-plastic stress are determined for
graphite/aluminum composites.
Abstract: Post cracking behavior and load –bearing capacity of
the steel fiber reinforced high-strength concrete (SFRHSC) are
dependent on the number of fibers are crossing the weakest crack
(bridged the crack) and their orientation to the crack surface. Filling
the mould by SFRHSC, fibers are moving and rotating with the
concrete matrix flow till the motion stops in each internal point of the
concrete body. Filling the same mould from the different ends
SFRHSC samples with the different internal structures (and different
strength) can be obtained. Numerical flow simulations (using Newton
and Bingham flow models) were realized, as well as single fiber
planar motion and rotation numerical and experimental investigation
(in viscous flow) was performed. X-ray pictures for prismatic
samples were obtained and internal fiber positions and orientations
were analyzed. Similarly fiber positions and orientations in cracked
cross-section were recognized and were compared with numerically
simulated. Structural SFRHSC fracture model was created based on
single fiber pull-out laws, which were determined experimentally.
Model predictions were validated by 15x15x60cm prisms 4 point
bending tests.
Abstract: Food and fibre production in arid and semi-arid regions has emerged as one of the major challenges for various socio-economic and political reasons such as the food security and self-sufficiency. Productive use of the renewable water resources has risen on top ofthe decision-making agenda. For this reason, efficient operation and maintenance of modern irrigation and drainage schemes become part and parcel and indispensible reality in agricultural policy making arena. The aim of this paper is to investigate the complexity of operating and maintaining such schemes, mainly focussing on challenges which enhance and opportunities that impedsustainable food and fibre production. The methodology involved using secondary data complemented byroutine observations and stakeholders views on issues that influence the O&M in the Dez command area. The SPSS program was used as an analytical framework for data analysis and interpretation.Results indicate poor application efficiency in most croplands, much of which is attributed to deficient operation of conveyance and distribution canals. These in turn, are reportedly linked to inadequate maintenance of the pumping stations and hydraulic structures like turnouts,flumes and other control systems particularly in the secondary and tertiary canals. Results show that the aforementioned deficiencies have been the major impediment to establishing regular flow toward the farm gates which subsequently undermine application efficiency and tillage operationsat farm level. Results further show that accumulative impact of such deficiencies has been the major causes of poorcrop yield and quality that deem production system in these croplands uneconomic. Results further show that the present state might undermine the sustainability of agricultural system in the command area. The overall conclusion being that present water management is unlikely to be responsive to challenges that the sector faces. And in the absence of coherent measures to shift the status quo situation in favour of more productive resource use, it would be hard to fulfil the objectives of the National Economic and Socio-cultural Development Plans.
Abstract: Eight steel reinforced concrete beams (SRC), were
fabricated and tested under earthquake type cyclic loading. The
effectiveness of intermediate stiffeners, such as mid-span stiffener and
plastic hinge zone stiffeners, in enhancing composite action and
ductility of SRC beams was investigated. The effectiveness of
strengthened beam-to-column (SBC) and weakened beam-to-column
(WBC) connections in enhancing beam ductility was also studied. It
was found that: (1) All the specimens possessed fairly high flexural
ductility and were found adequate for structures in high seismic zones.
(2) WBC connections induced stress concentration which caused extra
damage to concrete near the flange tapering zone. This extra damage
inhibited the flexural strength development and the ductility of the
specimens with WBC connections to some extent. (3) Specimens with
SBC connections demonstrated higher flexural strength and ductility
compared to specimens with WBC connections. (4) The intermediate
stiffeners, especially combination of plastic hinge zone stiffener and
mid span stiffeners, have an obvious effect in enhancing the ductility
of the beams with SBC connection.
Abstract: This research presents a system for post processing of
data that takes mined flat rules as input and discovers crisp as well as
fuzzy hierarchical structures using Learning Classifier System
approach. Learning Classifier System (LCS) is basically a machine
learning technique that combines evolutionary computing,
reinforcement learning, supervised or unsupervised learning and
heuristics to produce adaptive systems. A LCS learns by interacting
with an environment from which it receives feedback in the form of
numerical reward. Learning is achieved by trying to maximize the
amount of reward received. Crisp description for a concept usually
cannot represent human knowledge completely and practically. In the
proposed Learning Classifier System initial population is constructed
as a random collection of HPR–trees (related production rules) and
crisp / fuzzy hierarchies are evolved. A fuzzy subsumption relation is
suggested for the proposed system and based on Subsumption Matrix
(SM), a suitable fitness function is proposed. Suitable genetic
operators are proposed for the chosen chromosome representation
method. For implementing reinforcement a suitable reward and
punishment scheme is also proposed. Experimental results are
presented to demonstrate the performance of the proposed system.
Abstract: The counter flow solar air heaters, with four
transverse fins and wire mesh layers are constructed and investigated
experimentally for thermal efficiency at a geographic location of
Cyprus in the city of Famagusta. The absorber plate is replaced by
sixteen steel wire mesh layers, 0.18 x 0.18cm in cross section
opening and a 0.02cm in diameter. The wire mesh layers arranged in
three groups, first and second include 6 layers, while the third include
4 layers. All layers fixed in the duct parallel to the glazing and each
group separated from the others by wood frame thickness of 0.5cm to
reduce the pressure drop. The transverse fins arranged in a way to
force the air to flow through the bed like eight letter path with flow
depth 3cm. The proposed design has increased the heat transfer rate,
but on other hand causes a high pressure drop. The obtained results
show that, for air mass flow rate range between 0.011-0.036kg/s, the
thermal efficiency increases with increasing the air mass flow. The
maximum efficiency obtained is 65.6% for the mass flow rate of
0.036kg/s. Moreover, the temperature difference between the outlet
flow and the ambient temperature, ΔT, reduces as the air mass flow
rate increase. The maximum difference between the outlet and
ambient temperature obtained was 43°C for double pass for minimum
mass flow rate of 0.011kg/s. Comparison with a conventional solar
air heater collector shows a significantly development in the thermal
efficiency.
Abstract: Recordings from recent earthquakes have provided evidence that ground motions in the near field of a rupturing fault differ from ordinary ground motions, as they can contain a large energy, or “directivity" pulse. This pulse can cause considerable damage during an earthquake, especially to structures with natural periods close to those of the pulse. Failures of modern engineered structures observed within the near-fault region in recent earthquakes have revealed the vulnerability of existing RC buildings against pulse-type ground motions. This may be due to the fact that these modern structures had been designed primarily using the design spectra of available standards, which have been developed using stochastic processes with relatively long duration that characterizes more distant ground motions. Many recently designed and constructed buildings may therefore require strengthening in order to perform well when subjected to near-fault ground motions. Fiber Reinforced Polymers are considered to be a viable alternative, due to their relatively easy and quick installation, low life cycle costs and zero maintenance requirements. The objective of this paper is to investigate the adequacy of Artificial Neural Networks (ANN) to determine the three dimensional dynamic response of FRP strengthened RC buildings under the near-fault ground motions. For this purpose, one ANN model is proposed to estimate the base shear force, base bending moments and roof displacement of buildings in two directions. A training set of 168 and a validation set of 21 buildings are produced from FEA analysis results of the dynamic response of RC buildings under the near-fault earthquakes. It is demonstrated that the neural network based approach is highly successful in determining the response.
Abstract: The changing economic climate has made global
manufacturing a growing reality over the last decade, forcing
companies from east and west and all over the world to
collaborate beyond geographic boundaries in the design,
manufacture and assemble of products. The ISO10303 and
ISO14649 Standards (STEP and STEP-NC) have been
developed to introduce interoperability into manufacturing
enterprises so as to meet the challenge of responding to
production on demand. This paper describes and illustrates a
STEP compliant CAD/CAPP/CAM System for the manufacture
of rotational parts on CNC turning centers. The information
models to support the proposed system together with the data
models defined in the ISO14649 standard used to create the NC
programs are also described. A structured view of a STEP
compliant CAD/CAPP/CAM system framework supporting the
next generation of intelligent CNC controllers for turn/mill
component manufacture is provided. Finally a proposed
computational environment for a STEP-NC compliant system
for turning operations (SCSTO) is described. SCSTO is the
experimental part of the research supported by the specification
of information models and constructed using a structured
methodology and object-oriented methods. SCSTO was
developed to generate a Part 21 file based on machining
features to support the interactive generation of process plans
utilizing feature extraction. A case study component has been
developed to prove the concept for using the milling and turning
parts of ISO14649 to provide a turn-mill CAD/CAPP/CAM
environment.