Abstract: In the Top Right Access point Minimum Length Corridor (TRA-MLC) problem [1], a rectangular boundary partitioned into rectilinear polygons is given and the problem is to find a corridor of least total length and it must include the top right corner of the outer rectangular boundary. A corridor is a tree containing a set of line segments lying along the outer rectangular boundary and/or on the boundary of the rectilinear polygons. The corridor must contain at least one point from the boundaries of the outer rectangle and also the rectilinear polygons. Gutierrez and Gonzalez [1] proved that the MLC problem, along with some of its restricted versions and variants, are NP-complete. In this paper, we give a shorter proof of NP-Completeness of TRA-MLC by findig the reduction in the following way.
Abstract: One important objective in Precision Agriculture is to minimize the volume of herbicides that are applied to the fields through the use of site-specific weed management systems. In order to reach this goal, two major factors need to be considered: 1) the similar spectral signature, shape and texture between weeds and crops; 2) the irregular distribution of the weeds within the crop's field. This paper outlines an automatic computer vision system for the detection and differential spraying of Avena sterilis, a noxious weed growing in cereal crops. The proposed system involves two processes: image segmentation and decision making. Image segmentation combines basic suitable image processing techniques in order to extract cells from the image as the low level units. Each cell is described by two area-based attributes measuring the relations among the crops and the weeds. From these attributes, a hybrid decision making approach determines if a cell must be or not sprayed. The hybrid approach uses the Support Vector Machines and the Fuzzy k-Means methods, combined through the fuzzy aggregation theory. This makes the main finding of this paper. The method performance is compared against other available strategies.
Abstract: The malfunction of thermal protection system (TPS) caused by aerodynamic heating is a latent trouble to aircraft structure safety. Accurately predicting the structure temperature field is quite important for the TPS design of hypersonic vehicle. Since Thornton’s work in 1988, the coupled method of aerodynamic heating and heat transfer has developed rapidly. However, little attention has been paid to the influence of structural deformation on aerodynamic heating and structural temperature field. In the flight, especially the long-endurance flight, the structural deformation, caused by the aerodynamic heating and temperature rise, has a direct impact on the aerodynamic heating and structural temperature field. Thus, the coupled interaction cannot be neglected. In this paper, based on the method of static aero-thermo-elasticity, considering the influence of aero-thermo-elasticity deformation, the aerodynamic heating and heat transfer coupled results of hypersonic vehicle wing model were calculated. The results show that, for the low-curvature region, such as fuselage or center-section wing, structure deformation has little effect on temperature field. However, for the stagnation region with high curvature, the coupled effect is not negligible. Thus, it is quite important for the structure temperature prediction to take into account the effect of elastic deformation. This work has laid a solid foundation for improving the prediction accuracy of the temperature distribution of aircraft structures and the evaluation capacity of structural performance.
Abstract: In the power quality analysis non-stationary nature
of voltage distortions require some precise and powerful analytical
techniques. The time-frequency representation (TFR) provides a
powerful method for identification of the non-stationary of the
signals. This paper investigates a comparative study on two
techniques for analysis and visualization of voltage distortions with
time-varying amplitudes. The techniques include the Discrete
Wavelet Transform (DWT), and the S-Transform. Several power
quality problems are analyzed using both the discrete wavelet
transform and S–transform, showing clearly the advantage of the S–
transform in detecting, localizing, and classifying the power quality
problems.
Abstract: One of the main research directions in CAD/CAM
machining area is the reducing of machining time.
The feedrate scheduling is one of the advanced techniques that
allows keeping constant the uncut chip area and as sequel to keep
constant the main cutting force. They are two main ways for feedrate
optimization. The first consists in the cutting force monitoring, which
presumes to use complex equipment for the force measurement and
after this, to set the feedrate regarding the cutting force variation. The
second way is to optimize the feedrate by keeping constant the
material removal rate regarding the cutting conditions.
In this paper there is proposed a new approach using an extended
database that replaces the system model.
The feedrate scheduling is determined based on the identification
of the reconfigurable machine tool, and the feed value determination
regarding the uncut chip section area, the contact length between tool
and blank and also regarding the geometrical roughness.
The first stage consists in the blank and tool monitoring for the
determination of actual profiles. The next stage is the determination
of programmed tool path that allows obtaining the piece target
profile.
The graphic representation environment models the tool and blank
regions and, after this, the tool model is positioned regarding the
blank model according to the programmed tool path. For each of
these positions the geometrical roughness value, the uncut chip area
and the contact length between tool and blank are calculated. Each of
these parameters are compared with the admissible values and
according to the result the feed value is established.
We can consider that this approach has the following advantages:
in case of complex cutting processes the prediction of cutting force is
possible; there is considered the real cutting profile which has
deviations from the theoretical profile; the blank-tool contact length
limitation is possible; it is possible to correct the programmed tool
path so that the target profile can be obtained.
Applying this method, there are obtained data sets which allow the
feedrate scheduling so that the uncut chip area is constant and, as a
result, the cutting force is constant, which allows to use more
efficiently the machine tool and to obtain the reduction of machining
time.
Abstract: The autonomous mobile robot was designed and implemented which was capable of navigating in the industrial environments and did a job of picking objects from variable height and delivering it to another location following a predefined trajectory. In developing country like Bangladesh industrial robotics is not very prevalent yet, due to the high installation cost. The objective of this project was to develop an autonomous mobile robot for industrial application using the available resources in the local market at lower manufacturing cost. The mechanical system of the robot was comprised of locomotion, gripping and elevation system. Grippers were designed to grip objects of a predefined shape. Cartesian elevation system was designed for vertical movement of the gripper. PIC18F452 microcontroller was the brain of the control system. The prototype autonomous robot was fabricated for relatively lower load than the industry and the performance was tested in a virtual industrial environment created within the laboratory to realize the effectiveness.
Abstract: Scheduling for the flexible job shop is very important
in both fields of production management and combinatorial
optimization. However, it quit difficult to achieve an optimal solution
to this problem with traditional optimization approaches owing to the
high computational complexity. The combining of several
optimization criteria induces additional complexity and new
problems. In this paper, a Pareto approach to solve the multi
objective flexible job shop scheduling problems is proposed. The
objectives considered are to minimize the overall completion time
(makespan) and total weighted tardiness (TWT). An effective
simulated annealing algorithm based on the proposed approach is
presented to solve multi objective flexible job shop scheduling
problem. An external memory of non-dominated solutions is
considered to save and update the non-dominated solutions during
the solution process. Numerical examples are used to evaluate and
study the performance of the proposed algorithm. The proposed
algorithm can be applied easily in real factory conditions and for
large size problems. It should thus be useful to both practitioners and
researchers.
Abstract: Image mosaicing is a technique that permits to enlarge the field of view of a camera. For instance, it is employed to achieve panoramas with common cameras or even in scientific applications, to achieve the image of a whole culture in microscopical imaging. Usually, a mosaic of cell cultures is achieved through using automated microscopes. However, this is often performed in batch, through CPU intensive minimization algorithms. In addition, live stem cells are studied in phase contrast, showing a low contrast that cannot be improved further. We present a method to study the flat field from live stem cells images even in case of 100% confluence, this permitting to build accurate mosaics on-line using high performance algorithms.
Abstract: Children with hemiplgic cerebral palsy often walk
with diminished reciprocal arm swing so the purpose of this study
was to describe kinematic characteristics in children with hemiplegic
cerebral palsy (CP) during the gait suphases, and find if there is a
correlation between upper(shoulder and elbow) and lower(hip, knee,
and ankle) limb joints either in involved or uninvolved.48 children
with hemiplegic cerebral palsy (18boys, 30girls) with an average age
of (5.1±0.87) years were selected randomly to evaluate joint angles
during gait by 3D motion analysis system with 6 pro reflex cameras
in a sagittal plane for both sides of the body. The results showed
increased shoulder and elbow flexion, increased hip angular
displacement, decreased knee and ankle arcs during gait cycle, also
there is correlation between shoulder and elbow to hip, knee, and
ankle joints during various subphases of gait.
Abstract: Islamic banking is one the most blossoming doctrine in
economic system of the world. The Fast growing awareness about
Islamic financial system has brought strong feeling to Muslims to
confront the western interest-based economic cycle. The Islamic
economic system is emerging as a reliable alternative to the interest
based system. This study is proposed to ascertain the motivational
factors encouraging people to go for Islamic banking in Pakistan.
These pulsing factors are determined by generation of hypothesis that
there are certain factors which are urging people to opt Islamic
banking system and to see the differences in their ranking by applying
Friedman test. These factors include: Economically derived factors
such as stability of Islamic banks in crisis, profit and loss sharing
doctrine and equity sharing etc. This study also highlights the
religiously derived factors such as interest free banking, Shariah
tenets and supervisory of Islamic Shariah board and sociopsychological
factors.
Abstract: the cursive nature of the Arabic writing makes it
difficult to accurately segment characters or even deal with the whole
word efficiently. Therefore, in this paper, a printed Arabic sub-word
recognition system is proposed. The suggested algorithm utilizes
geometrical moments as descriptors for the separated sub-words.
Three types of moments are investigated and applied to the printed
sub-word images after dividing each image into multiple parts using
windowing. Since moments are global descriptors, the windowing
mechanism allows the moments to be applied to local regions of the
sub-word. The local-global mixture of the proposed scheme increases
the discrimination power of the moments while keeping the
simplicity and ease of use of moments.
Abstract: The growing problem of youth unemployment in
Egypt after the 25th January Revolution has directed the attention of
some human resource experts towards considering remote
employment as a partial remedy for the unemployed youth instead of
the unavailable traditional jobs, a trend which will also help with the
congested offices and unsolved traffic problem in Cairo and spread
a flexible work culture, but despite of that, the main issue remains
unresolved for these organizations to deal with the system challenges.
In the past few years, in developed countries, there has been a
growing trend for many companies to shift to remote employment
instead of the traditional office employment for many reasons: due to
the growing technological advances that helped some employees do
their work from home on a part time basis, the need for achieving an
employee-s work balance in the middle of unbalanced complicated
life, top management focus on employee-s productivity rather their
time spent at work. The objective of this paper is to study and analyze
the advantages and challenges that Egypt-s labor force will be facing
in their implementation of remote or virtual employment in both
government and private organizations after the 25th January
revolution. Therefore, the research question will be: What are the
advantages and different challenges that Egyptian organizations
might face in their implementation for remote employment system
and how can they manage these challenges for the system to work
effectively? The study is divided into six main parts: the introduction,
objective and importance of the study, research problem,
methodology, experience of some countries that implemented remote
employment, advantages and challenges of implementing remote
employment in Egypt and then the conclusion which discuses the
results and recommendations of the study.
Abstract: The use of wind energy for electricity generation is
growing rapidly across the world and in Portugal. However, the
geographical characteristics of the country along with the average
wind regime and with the environmental restrictions imposed to these
projects create limitations to the exploit of the onshore wind
resource. The best onshore wind spots are already committed and the
possibility of offshore wind farms in the Portuguese cost is now
being considered. This paper aims to make a contribution to the
evaluation of offshore wind power projects in Portugal. The technical
restrictions are addressed and the strategic, environmental and
financial interest of the project is analysed from the private company
and public points of view. The results suggest that additional support
schemes are required to ensure private investors interest for these
projects. Assuming an approach of direct substitution of energy
sources for electricity generation, the avoided CO2 equivalent
emissions for an offshore wind power project were quantified. Based
on the conclusions, future research is proposed to address the
environmental and social impacts of these projects.
Abstract: In this paper, we first give the representation of the general solution of the following inverse eigenvalue problem (IEP): Given X ∈ Rn×p and a diagonal matrix Λ ∈ Rp×p, find nontrivial real-valued symmetric arrow-head matrices A and B such that AXΛ = BX. We then consider an optimal approximation problem: Given real-valued symmetric arrow-head matrices A, ˜ B˜ ∈ Rn×n, find (A, ˆ Bˆ) ∈ SE such that Aˆ − A˜2 + Bˆ − B˜2 = min(A,B)∈SE (A−A˜2 +B −B˜2), where SE is the solution set of IEP. We show that the optimal approximation solution (A, ˆ Bˆ) is unique and derive an explicit formula for it.
Abstract: Thousands of masters athletes participate
quadrennially in the World Masters Games (WMG), yet this cohort
of athletes remains proportionately under-investigated. Due to a
growing global obesity pandemic in context of benefits of physical
activity across the lifespan, the BMI trends for this unique population
was of particular interest. The nexus between health, physical
activity and aging is complex and has raised much interest in recent
times due to the realization that a multifaceted approach is necessary
in order to counteract the obesity pandemic. By investigating age
based trends within a population adhering to competitive sport at
older ages, further insight might be gleaned to assist in understanding
one of many factors influencing this relationship.BMI was derived
using data gathered on a total of 6,071 masters athletes (51.9% male,
48.1% female) aged 25 to 91 years ( =51.5, s =±9.7), competing at
the Sydney World Masters Games (2009). Using linear and loess
regression it was demonstrated that the usual tendency for prevalence
of higher BMI increasing with age was reversed in the sample. This
trend in reversal was repeated for both male and female only sub-sets
of the sample participants, indicating the possibility of improved
prevalence of BMI with increasing age for both the sample as a
whole and these individual sub-groups.This evidence of improved
classification in one index of health (reduced BMI) for masters
athletes (when compared to the general population) implies there are
either improved levels of this index of health with aging due to
adherence to sport or possibly the reduced BMI is advantageous and
contributes to this cohort adhering (or being attracted) to masters
sport at older ages.
Abstract: The mechanism behind the electromigration and
thermomigration failure in flip-chip solder joints with Cu-pillar bumps
was investigated in this paper through using finite element method.
Hot spot and the current crowding occurrs in the upper corner of
copper column instead of solders of the common solder ball. The
simulation results show that the change in thermal gradient is
noticeable, which might greatly affect the reliability of solder joints
with Cu-pillar bumps under current stressing. When the average
applied current density is increased from 1×104 A/cm2 to 3×104 A/cm2
in solders, the thermal gradient would increase from 74 K/cm to 901
K/cm at an ambient temperature of 25°C. The force from thermal
gradient of 901 K/cm can nearly induce thermomigration by itself.
With the increase in applied current, the thermal gradient is growing. It
is proposed that thermomigration likely causes a serious reliability
issue for Cu column based interconnects.
Abstract: Several wireless networks security standards have been proposed and widely implemented in both business and home environments in order to protect the network from unauthorized access. However, the implementation of such standards is usually achieved by network administrators without even knowing the standards- weaknesses and strengths. The intention of this paper is to evaluate and analyze the impact over the network-s security due to the implementation of the wireless networks security standards WEP, WPA and WLAN 802.1X.
Abstract: The three-dimensional incompressible flow past a
rectangular open cavity is investigated, where the aspect ratio of the
cavity is considered as 4. The principle objective is to use large-eddy
simulation to resolve and control the large-scale structures, which are
largely responsible for flow oscillations in a cavity. The flow past an
open cavity is very common in aerospace applications and can be a
cause of acoustic source due to hydrodynamic instability of the shear
layer and its interactions with the downstream edge. The unsteady
Navier-stokes equations have been solved on a staggered mesh using
a symmetry-preserving central difference scheme. Synthetic jet has
been used as an active control to suppress the cavity oscillations in
wake mode for a Reynolds number of ReD = 3360. The effect of
synthetic jet has been studied by varying the jet amplitude and
frequency, which is placed at the upstream wall of the cavity. The
study indicates that there exits a frequency band, which is larger than
a critical value, is effective in attenuating cavity oscillations when
blowing ratio is more than 1.0.
Abstract: In this paper, we proposed a method to design a
model-following adaptive controller for linear/nonlinear plants.
Radial basis function neural networks (RBF-NNs), which are known
for their stable learning capability and fast training, are used to
identify linear/nonlinear plants. Simulation results show that the
proposed method is effective in controlling both linear and nonlinear
plants with disturbance in the plant input.
Abstract: The main objectif of this paper is to present a tool that
we have developed subject to characterize and modelling indoor radio
channel propagation at millimetric wave. The tool is based on the
ray tracing technique (RTT). As, in realistic environment we cannot
neglect the significant impact of Human Body Shadowing and other
objects in motion on indoor 60 GHz propagation channel. Hence,
our proposed model allows a simulation of propagation in a dynamic
indoor environment. First, we describe a model of human body.
Second, RTT with this model is used to simulate the propagation
of millimeter waves in the presence of persons in motion. Results
of the simulation show that this tool gives results in agreement with
those reported in the literature. Specially, the effects of people motion
on temporal channel properties.