Abstract: Flows over a harmonically oscillating NACA 0012
airfoil are simulated here using a two-dimensional, unsteady,
incompressibleNavier-Stokes solver.Both pure-plunging and
pitching-plunging combined oscillations are considered at a Reynolds
number of 5000. Special attention is paid to the vortex shedding and
interaction mechanism of the motions. For all the simulations
presented here, the reduced frequency (k) is fixed at a value of 2.5
and plunging amplitude (h) is selected to be in the range of 0.2-0.5.
The simulation results show that the interaction mechanism between
the leading and trailing edge vortices has a decisive effect on the
values of the resulting thrust and propulsive efficiency.
Abstract: Sickness absence represents a major economic and
social issue. Analysis of sick leave data is a recurrent challenge to analysts because of the complexity of the data structure which is
often time dependent, highly skewed and clumped at zero. Ignoring these features to make statistical inference is likely to be inefficient
and misguided. Traditional approaches do not address these problems. In this study, we discuss model methodologies in terms of statistical techniques for addressing the difficulties with sick leave data. We also introduce and demonstrate a new method by performing a longitudinal assessment of long-term absenteeism using
a large registration dataset as a working example available from the Helsinki Health Study for municipal employees from Finland during the period of 1990-1999. We present a comparative study on model
selection and a critical analysis of the temporal trends, the occurrence
and degree of long-term sickness absences among municipal employees. The strengths of this working example include the large
sample size over a long follow-up period providing strong evidence in supporting of the new model. Our main goal is to propose a way to
select an appropriate model and to introduce a new methodology for analysing sickness absence data as well as to demonstrate model
applicability to complicated longitudinal data.
Abstract: This paper describes a computer-aided design for
design of the concave globoidal cam with cylindrical rollers and
swinging follower. Four models with different modeling methods are
made from the same input data. The input data are angular input and
output displacements of the cam and the follower and some other
geometrical parameters of the globoidal cam mechanism. The best
cam model is the cam which has no interference with the rollers
when their motions are simulated in assembly conditions. The
angular output displacement of the follower for the best cam is also
compared with that of in the input data to check errors. In this study,
Pro/ENGINEER® Wildfire 2.0 is used for modeling the cam,
simulating motions and checking interference and errors of the
system.
Abstract: An advanced Monte Carlo simulation method, called Subset Simulation (SS) for the time-dependent reliability prediction for underground pipelines has been presented in this paper. The SS can provide better resolution for low failure probability level with efficient investigating of rare failure events which are commonly encountered in pipeline engineering applications. In SS method, random samples leading to progressive failure are generated efficiently and used for computing probabilistic performance by statistical variables. SS gains its efficiency as small probability event as a product of a sequence of intermediate events with larger conditional probabilities. The efficiency of SS has been demonstrated by numerical studies and attention in this work is devoted to scrutinise the robustness of the SS application in pipe reliability assessment. It is hoped that the development work can promote the use of SS tools for uncertainty propagation in the decision-making process of underground pipelines network reliability prediction.
Abstract: A large number of chemical, bio-chemical and pollution-control processes use heterogeneous fixed-bed reactors. The use of finite hollow cylindrical catalyst pellets can enhance conversion levels in such reactors. The absence of the pellet core can significantly lower the diffusional resistance associated with the solid phase. This leads to a better utilization of the catalytic material, which is reflected in the higher values for the effectiveness factor, leading ultimately to an enhanced conversion level in the reactor. It is however important to develop a rigorous heterogeneous model for the reactor incorporating the two-dimensional feature of the solid phase owing to the presence of the finite hollow cylindrical catalyst pellet. Presently, heterogeneous models reported in the literature invariably employ one-dimension solid phase models meant for spherical catalyst pellets. The objective of the paper is to present a rigorous model of the fixed-bed reactors containing finite hollow cylindrical catalyst pellets. The reaction kinetics considered here is the widely used Michaelis–Menten kinetics for the liquid-phase bio-chemical reactions. The reaction parameters used here are for the enzymatic degradation of urea. Results indicate that increasing the height to diameter ratio helps to improve the conversion level. On the other hand, decreasing the thickness is apparently not as effective. This could however be explained in terms of the higher void fraction of the bed that causes a smaller amount of the solid phase to be packed in the fixed-bed bio-chemical reactor.
Abstract: The trial in the city, located 170 kilometers from the
Iranian city of Ahvaz was Omidiyeh. The main factor in this project
includes 4 levels in control (without hormones), use of hormones in
the seed, vegetative and flowering stage respectively. And sub-plots
included 3 varieties of vetch in three levels, with local names, was the
jewel in the study of light and Auxin in the vegetative and
reproductive different times in different varieties of vetch was
investigated. This test has been taken in the plots in a randomized
complete block with four replications. In order to study the effects of
the hormone Auxin in the growth stages (seed, vegetative and
flowering) to control (no hormone Auxin) on three local varieties of
vetch, the essence of light and plant height, number of pods per plant,
seed number The pods, seeds per plant, grain weight, grain yield,
plant dry weight and protein content were measured. Among the
vetch varieties for plant height, number of pods per plant, a seed per
plant, grain weight, grain yield, and plant dry weight and protein
levels of 1 percent of plant and seed number per pod per plant at 5%
level of There was no significant difference. Interactions for grain
yield per plant, grain yield and protein levels of 1 percent and the
number of seeds per pod and seed weight are significant differences
in levels 5 and plant height and plant dry weight of the interaction
were INFLUENCE There was no significant difference in them.
Abstract: The dynamical contouring error is a critical element for the accuracy of machine tools. The contouring error is defined as the difference between the processing actual path and commanded path, which is implemented by following the command curves from feeding driving system in machine tools. The contouring error is resulted from various factors, such as the external loads, friction, inertia moment, feed rate, speed control, servo control, and etc. Thus, the study proposes a 2D compensating system for the contouring accuracy of machine tools. Optical method is adopted by using stable frequency laser diode and the high precision position sensor detector (PSD) to performno-contact measurement. Results show the related accuracy of position sensor detector (PSD) of 2D contouring accuracy compensating system was ±1.5 μm for a calculated range of ±3 mm, and improvement accuracy is over 80% at high-speed feed rate.
Abstract: In this paper, an estimation accuracy of multiple moving
talker tracking using a microphone array is improved. The tracking
can be achieved by the adaptive method in which two algorithms are integrated, namely, the PAST (Projection Approximation Subspace
Tracking) algorithm and the IPLS (Interior Point Least Square) algorithm. When either talker begins to speak again after a silent
period, an appropriate feasible region for an evaluation function of
the IPLS algorithm might not be set. Then, the tracking fails due to the incorrect updating. Therefore, if an increment of the number of
active talkers is detected, the feasible region must be reset. Then, a low cost realization is required for the high speed tracking and a high
accuracy realization is desired for the precise tracking. In this paper,
the directions roughly estimated using the delayed-sum-array method
are used for the resetting. Several results of experiments performed in
an actual room environment show the effectiveness of the proposed method.
Abstract: This paper looks into detailed investigation of
thermal-hydraulic characteristics of the flow field in a fuel rod
model, especially near the spacer. The area investigate represents a
source of information on the velocity flow field, vortex, and on the
amount of heat transfer into the coolant all of which are critical for
the design and improvement of the fuel rod in nuclear power plants.
The flow field investigation uses three-dimensional Computational
Fluid Dynamics (CFD) with the Reynolds stresses turbulence model
(RSM). The fuel rod model incorporates a vertical annular channel
where three different shapes of spacers are used; each spacer shape is
addressed individually. These spacers are mutually compared in
consideration of heat transfer capabilities between the coolant and
the fuel rod model. The results are complemented with the calculated
heat transfer coefficient in the location of the spacer and along the
stainless-steel pipe.
Abstract: The RR interval series is non-stationary and unevenly
spaced in time. For estimating its power spectral density (PSD) using
traditional techniques like FFT, require resampling at uniform
intervals. The researchers have used different interpolation
techniques as resampling methods. All these resampling methods
introduce the low pass filtering effect in the power spectrum. The
lomb transform is a means of obtaining PSD estimates directly from
irregularly sampled RR interval series, thus avoiding resampling. In
this work, the superiority of Lomb transform method has been
established over FFT based approach, after applying linear and
cubicspline interpolation as resampling methods, in terms of
reproduction of exact frequency locations as well as the relative
magnitudes of each spectral component.
Abstract: The recycling of concrete, bricks and masonry rubble
as concrete aggregates is an important way to contribute to a
sustainable material flow. However, there are still various
uncertainties limiting the widespread use of Recycled Concrete
Aggregates (RCA). The fluctuations in the composition of grade
recycled aggregates and their influence on the properties of fresh and
hardened concrete are of particular concern regarding the use of
RCA. Most of problems occurring while using recycled concrete
aggregates as aggregates are due to higher porosity and hence higher
water absorption, lower mechanical strengths, residual impurities on
the surface of the RCA forming weaker bond between cement paste
and aggregate. So, the reuse of RCA is still limited. Efficient
polymer based treatment is proposed in order to reuse RCA easier.
The silicon-based polymer treatments of RCA were carried out and
were compared. This kind of treatment can improve the properties of
RCA such as the rate of water absorption on treated RCA is
significantly reduced.
Abstract: The major problem that wireless communication
systems undergo is multipath fading caused by scattering of the
transmitted signal. However, we can treat multipath propagation as
multiple channels between the transmitter and receiver to improve
the signal-to-scattering-noise ratio. While using Single Input
Multiple Output (SIMO) systems, the diversity receivers extract
multiple signal branches or copies of the same signal received from
different channels and apply gain combining schemes such as Root
Mean Square Gain Combining (RMSGC). RMSGC asymptotically
yields an identical performance to that of the theoretically optimal
Maximum Ratio Combining (MRC) for values of mean Signal-to-
Noise-Ratio (SNR) above a certain threshold value without the need
for SNR estimation. This paper introduces an improvement of
RMSGC using two different issues. We found that post-detection and
de-noising the received signals improve the performance of RMSGC
and lower the threshold SNR.
Abstract: This document details the process of developing a
wireless device that captures the basic movements of the foot (plantar
flexion, dorsal flexion, abduction, adduction.), and the knee
movement (flexion). It implements a motion capture system by using
a hardware based on optical fiber sensors, due to the advantages in
terms of scope, noise immunity and speed of data transmission and
reception. The operating principle used by this system is the detection
and transmission of joint movement by mechanical elements and
their respective measurement by optical ones (in this case infrared).
Likewise, Visual Basic software is used for reception, analysis and
signal processing of data acquired by the device, generating a 3D
graphical representation in real time of each movement. The result is
a boot in charge of capturing the movement, a transmission module
(Implementing Xbee Technology) and a receiver module for
receiving information and sending it to the PC for their respective
processing.
The main idea with this device is to help on topics such as
bioengineering and medicine, by helping to improve the quality of
life and movement analysis.
Abstract: Retention in the IT profession is critical for
organizations to stay competitive and operate reliably in the dynamic
business environment. Most organizations rely on compensation and
rewards as primary tools to enhance retention of employees. In this
quantitative survey-based study conducted at a large global bank, we
analyze the perceptions of 575 information technology (IT) software
professionals in India and Malaysia and find that fairness of rewards
has very little impact on retention likelihood. It is far more important
to actively involve employees in organizational activities. In
addition, our findings indicate that involvement is far more important
than information flow: the typical organizational communication to
keep employees informed.
Abstract: This paper aims to develop an algorithm of finite
capacity material requirement planning (FCMRP) system for a multistage
assembly flow shop. The developed FCMRP system has two
main stages. The first stage is to allocate operations to the first and
second priority work centers and also determine the sequence of the
operations on each work center. The second stage is to determine the
optimal start time of each operation by using a linear programming
model. Real data from a factory is used to analyze and evaluate the
effectiveness of the proposed FCMRP system and also to guarantee a
practical solution to the user. There are five performance measures,
namely, the total tardiness, the number of tardy orders, the total
earliness, the number of early orders, and the average flow-time. The
proposed FCMRP system offers an adjustable solution which is a
compromised solution among the conflicting performance measures.
The user can adjust the weight of each performance measure to
obtain the desired performance. The result shows that the combination
of FCMRP NP3 and EDD outperforms other combinations
in term of overall performance index. The calculation time for the
proposed FCMRP system is about 10 minutes which is practical for
the planners of the factory.
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: Superplastic deformation and high temperature load
relaxation behavior of coarse-grained iron aluminides with the
composition of Fe-28 at.% Al have been investigated. A series of load
relaxation and tensile tests were conducted at temperatures ranging
from 600 to 850oC. The flow curves obtained from load relaxation
tests were found to have a sigmoidal shape and to exhibit stress vs.
strain rate data in a very wide strain rate range from 10-7/s to 10-2/s.
Tensile tests have been conducted at various initial strain rates ranging
from 3×10-5/s to 1×10-2/s. Maximum elongation of ~500 % was
obtained at the initial strain rate of 3×10-5/s and the maximum strain
rate sensitivity was found to be 0.68 at 850oC in binary Fe-28Al alloy.
Microstructure observation through the optical microscopy (OM) and
the electron back-scattered diffraction (EBSD) technique has been
carried out on the deformed specimens and it has revealed the
evidences for grain boundary migration and grain refinement to occur
during superplastic deformation, suggesting the dynamic
recrystallization mechanism. The addition of Cr by the amount of 5
at.% appeared to deteriorate the superplasticity of the binary iron
aluminide. By applying the internal variable theory of structural
superplasticity, the addition of Cr has been revealed to lower the
contribution of the frictional resistance to dislocation glide during high
temperature deformation of the Fe3Al alloy.
Abstract: with increasing circuits- complexity and demand to
use portable devices, power consumption is one of the most
important parameters these days. Full adders are the basic block of
many circuits. Therefore reducing power consumption in full adders
is very important in low power circuits. One of the most powerconsuming
modules in full adders is XOR/XNOR circuit. This paper
presents two new full adders based on two new logic approaches. The
proposed logic approaches use one XOR or XNOR gate to implement
a full adder cell. Therefore, delay and power will be decreased. Using
two new approaches and two XOR and XNOR gates, two new full
adders have been implemented in this paper. Simulations are carried
out by HSPICE in 0.18μm bulk technology with 1.8V supply voltage.
The results show that the ten-transistors proposed full adder has 12%
less power consumption and is 5% faster in comparison to MB12T
full adder. 9T is more efficient in area and is 24% better than similar
10T full adder in term of power consumption. The main drawback of
the proposed circuits is output threshold loss problem.
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.