Abstract: This article is presented an experimental and modeling
study of a four-bed pressure swing adsorption process using
zeolite13X to provide oxygen-enriched air. The binary mixture N2/O2
(79/21 vol %) was used as a feed stream. The effects of purge/feed
ratio (P/F), adsorption pressure, cyclic time and product flow rate on
product purity and recovery under nonisothermal condition were
studied. The adsorption dynamics of process were determined using
a mathematical model incorporated mass and energy balances. A
Mathlab code using finite difference method was developed to solve
the set of coupled differential-algebraic equations, and the simulation
results are agreed well with experimental results.
Abstract: Web-based systems have become increasingly
important due to the fact that the Internet and the World Wide Web
have become ubiquitous, surpassing all other technological
developments in our history. The Internet and especially companies
websites has rapidly evolved in their scope and extent of use, from
being a little more than fixed advertising material, i.e. a "web
presences", which had no particular influence for the company's
business, to being one of the most essential parts of the company's
core business.
Traditional software engineering approaches with process models
such as, for example, CMM and Waterfall models, do not work very
well since web system development differs from traditional
development. The development differs in several ways, for example,
there is a large gap between traditional software engineering designs
and concepts and the low-level implementation model, many of the
web based system development activities are business oriented (for
example web application are sales-oriented, web application and
intranets are content-oriented) and not engineering-oriented.
This paper aims to introduce Increment Iterative extreme
Programming (IIXP) methodology for developing web based
systems. In difference to the other existence methodologies, this
methodology is combination of different traditional and modern
software engineering and web engineering principles.
Abstract: Motivated by the recent work of Herbert, Hayen, Macaskill and Walter [Interval estimation for the difference of two independent variances. Communications in Statistics, Simulation and Computation, 40: 744-758, 2011.], we investigate, in this paper, new confidence intervals for the difference between two normal population variances based on the generalized confidence interval of Weerahandi [Generalized Confidence Intervals. Journal of the American Statistical Association, 88(423): 899-905, 1993.] and the closed form method of variance estimation of Zou, Huo and Taleban [Simple confidence intervals for lognormal means and their differences with environmental applications. Environmetrics 20: 172-180, 2009]. Monte Carlo simulation results indicate that our proposed confidence intervals give a better coverage probability than that of the existing confidence interval. Also two new confidence intervals perform similarly based on their coverage probabilities and their average length widths.
Abstract: The migration of a deformable drop in simple shear
flow at finite Reynolds numbers is investigated numerically by
solving the full Navier-Stokes equations using a finite
difference/front tracking method. The objectives of this study are to
examine the effectiveness of the present approach to predict the
migration of a drop in a shear flow and to investigate the behavior of
the drop migration with different drop sizes and non-unity viscosity
ratios. It is shown that the drop deformation depends strongly on the
capillary number, so that; the proper non-dimensional number for the
interfacial tension is the capillary number. The rate of migration
increased with increasing the drop radius. In other words, the
required time for drop migration to the centreline decreases. As the
viscosity ratio increases, the drop rotates more slowly and the
lubrication force becomes stronger. The increased lubrication force
makes it easier for the drop to migrate to the centre of the channel.
The migration velocity of the drop vanishes as the drop reaches the
centreline under viscosity ratio of one and non-unity viscosity ratios.
To validate the present calculations, some typical results are
compared with available experimental and theoretical data.
Abstract: In this paper, a delayed competitive system with the effect of toxic substances is investigated. With the aid of differential equations with piecewise constant arguments, a discrete analogue of continuous non-autonomous delayed competitive system with the effect of toxic substances is proposed. By using Gaines and Mawhin,s continuation theorem of coincidence degree theory, a easily verifiable sufficient condition for the existence of positive solutions of difference equations is obtained.
Abstract: The purpose of this study was to evaluate the use of
mucus production as a biomarker. This was done by exposing the
mussel Perna perna to various sublethal concentrations of Cu.
Mussels are effective as a bioindicator species as they accumulate Cu
in their tissues. Differences in mucus production rates were evaluated
at different Cu concentrations. The findings of this study indicate that
increasing Cu concentrations had a significant effect on the mucus
production rates over a 24 hour exposure. There were also significant
differences between the mucus production rates at different Cu
concentrations (p < 0.05). Thus, mucus is an essential detoxification
mechanism.
Abstract: This paper investigates the impact of the hand-hold
positions on both antenna performance and the specific absorption
rate (SAR) induced in the user-s head. A cellular handset with
external antenna operating at GSM-900 frequency is modeled and
simulated using a finite difference time-domain (FDTD)-based
platform SEMCAD-X. A specific anthropomorphic mannequin
(SAM) is adopted to simulate the user-s head, whereas a semirealistic
CAD-model of three-tissues is designed to simulate the
user-s hand. The results show that in case of the handset in hand close
to head at different positions; the antenna total efficiency gets
reduced to (14.5% - 5.9%) at cheek-position and to (27.5% to 11.8%)
at tilt-position. The peak averaged SAR1g values in head close to
handset without hand, are 4.67 W/Kg and 2.66 W/Kg at cheek and
tilt-position, respectively. Due to the presence of hand, the SAR1g in
head gets reduced to (3.67-3.31 W/Kg) at cheek-position and to
(1.84-1.64 W/Kg) at tilt-position, depending on the hand-hold
position.
Abstract: In today-s competitive market, most companies
develop manufacturing systems that can help in cost reduction and
maximum quality. Human issues are an important part of
manufacturing systems, yet most companies ignore their effects on
production performance. This paper aims to developing an integrated
workforce planning system that incorporates the human being.
Therefore, a multi-objective mixed integer nonlinear programming
model is developed to determine the amount of hiring, firing,
training, overtime for each worker type. This paper considers a
workforce planning model including human aspects such as skills,
training, workers- personalities, capacity, motivation, and learning
rates. This model helps to minimize the hiring, firing, training and
overtime costs, and maximize the workers- performance. The results
indicate that the workers- differences should be considered in
workforce scheduling to generate realistic plans with minimum costs.
This paper also investigates the effects of human learning rates on the
performance of the production systems.
Abstract: An experiment was performed in the south of
Morocco in order to evaluate the effect of deficit irrigation by treated
wastewater on chickpea production. We applied six irrigation
treatments on a local variety of chickpea by supplying alternatively
50 or 100% of ETm in a completely randomized design.
We found a highly significant difference between treatments in
terms of biomass production. Drought stress during the vegetative
period showed highest yield with 6.5 t/ha which was more than the
yield obtained for the control (4.9 t/ha). The optimal crop stage in
which deficit irrigation can be applied is the vegetative growth stage,
as the crop has a chance to develop its root system, to be able to
cover the plant needs for water and nutrient supply during the rest of
cycle, and non stress conditions during the flowering and seed filling
stages allow the plant to optimize its photosynthesis and carbon
translocation, therefore increase its productivity.
Abstract: This paper predicts the effect of the user-s hand-hold
position on the Total Isotropic Sensitivity (TIS) of GSM900/1800
mobile phone antennas of realistic in-use conditions, where different
semi-realistic mobile phone models, i.e., candy bar and clamshell, as
well as different antenna types, i.e., external and internal, are
simulated using a FDTD-based platform. A semi-realistic hand model
consisting of three tissues and the SAM head are used in simulations.
The results show a considerable impact on TIS of the adopted mobile
phone models owing to the user-s hand presence at different
positions, where a maximum level of TIS is obtained while grasping
the upper part of the mobile phone against head. Maximum TIS
levels are recorded in talk position for mobile phones with external
antenna and maximum differences in TIS levels due to the hand-hold
alteration are recorded for clamshell-type phones.
Abstract: Islamic institutions in Malaysia play a variety of
socioeconomic roles such as poverty alleviation. To perform this role,
these institutions face a major task in identifying the poverty group.
Most of these institutions measure and operationalize poverty from
the monetary perspective using variables such as income, expenditure
or consumption. In practice, most Islamic institutions in Malaysia use
the monetary approach in measuring poverty through the
conventional Poverty Line Income (PLI) method and recently, the
had al kifayah (HAK) method using total necessities of a household
from an Islamic perspective. The objective of this paper is to present
the PLI and also the HAK method. This micro-data study would
highlight the similarities and differences of both the methods.A
survey aided by a structured questionnaire was carried out on 260
selected head of households in the state of Selangor. The paper
highlights several demographic factors that are associated with the
three monetary indicators in the study, namely income, PLI and
HAK. In addition, the study found that these monetary variables are
significantly related with each other.
Abstract: The persistent nature of perfluorochemicals (PFCs) has attracted global concern in recent years. Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are the most commonly found PFC compounds, and thus their fate and transport play key roles in PFC distribution in the natural environment. The kinetic behavior of PFOS or PFOA on boehmite consists of a fast adsorption process followed by a slow adsorption process which may be attributed to the slow transport of PFOS or PFOA into the boehmite pore surface. The adsorption isotherms estimated the maximum adsorption capacities of PFOS and PFOA on boehmite as 0.877 μg/m2 and 0.633 μg/m2, with the difference primarily due to their different functional groups. The increase of solution pH led to a moderate decrease of PFOS and PFOA adsorption, owing to the increase of ligand exchange reactions and the decrease of electrostatic interactions. The presence of NaCl in solution demonstrated negative effects for PFOS and PFOA adsorption on boehmite surfaces, with potential mechanisms being electrical double layer compression, competitive adsorption of chloride.
Abstract: German electricity European options on futures using
Lévy processes for the underlying asset are examined. Implied
volatility evolution, under each of the considered models, is
discussed after calibrating for the Merton jump diffusion (MJD),
variance gamma (VG), normal inverse Gaussian (NIG), Carr, Geman,
Madan and Yor (CGMY) and the Black and Scholes (B&S) model.
Implied volatility is examined for the entire sample period, revealing
some curious features about market evolution, where data fitting
performances of the five models are compared. It is shown that
variance gamma processes provide relatively better results and that
implied volatility shows significant differences through time, having
increasingly evolved. Volatility changes for changed uncertainty, or
else, increasing futures prices and there is evidence for the need to
account for seasonality when modelling both electricity spot/futures
prices and volatility.
Abstract: Textile structures are engineered and fabricated to
meet worldwide structural applications. Nevertheless, research
varying textile structure on natural fibre as composite reinforcement
was found to be very limited. Most of the research is focusing on
short fibre and random discontinuous orientation of the reinforcement
structure. Realizing that natural fibre (NF) composite had been
widely developed to be used as synthetic fibre composite
replacement, this research attempted to examine the influence of
woven and cross-ply laminated structure towards its mechanical
performances. Laminated natural fibre composites were developed
using hand lay-up and vacuum bagging technique. Impact and
flexural strength were investigated as a function of fibre type (coir
and kenaf) and reinforcement structure (imbalanced plain woven,
0°/90° cross-ply and +45°/-45° cross-ply). Multi-level full factorial
design of experiment (DOE) and analysis of variance (ANOVA) was
employed to impart data as to how fibre type and reinforcement
structure parameters affect the mechanical properties of the
composites. This systematic experimentation has led to determination
of significant factors that predominant influences the impact and
flexural properties of the textile composites. It was proven that both
fibre type and reinforcement structure demonstrated significant
difference results. Overall results indicated that coir composite and
woven structure exhibited better impact and flexural strength. Yet,
cross-ply composite structure demonstrated better fracture resistance.
Abstract: one of the significant factors for improving the
accuracy of Land Surface Temperature (LST) retrieval is the correct
understanding of the directional anisotropy for thermal radiance. In
this paper, the multiple scattering effect between heterogeneous
non-isothermal surfaces is described rigorously according to the
concept of configuration factor, based on which a directional thermal
radiance model is built, and the directional radiant character for urban
canopy is analyzed. The model is applied to a simple urban canopy
with row structure to simulate the change of Directional Brightness
Temperature (DBT). The results show that the DBT is aggrandized
because of the multiple scattering effects, whereas the change range of
DBT is smoothed. The temperature difference, spatial distribution,
emissivity of the components can all lead to the change of DBT. The
“hot spot" phenomenon occurs when the proportion of high
temperature component in the vision field came to a head. On the other
hand, the “cool spot" phenomena occur when low temperature
proportion came to the head. The “spot" effect disappears only when
the proportion of every component keeps invariability. The model
built in this paper can be used for the study of directional effect on
emissivity, the LST retrieval over urban areas and the adjacency effect
of thermal remote sensing pixels.
Abstract: This paper presents the comparative study of coded
data methods for finding the benefit of concealing the natural data
which is the mercantile secret. Influential parameters of the number
of replicates (rep), treatment effects (τ) and standard deviation (σ)
against the efficiency of each transformation method are investigated.
The experimental data are generated via computer simulations under
the specified condition of the process with the completely
randomized design (CRD). Three ways of data transformation consist
of Box-Cox, arcsine and logit methods. The difference values of F
statistic between coded data and natural data (Fc-Fn) and hypothesis
testing results were determined. The experimental results indicate
that the Box-Cox results are significantly different from natural data
in cases of smaller levels of replicates and seem to be improper when
the parameter of minus lambda has been assigned. On the other hand,
arcsine and logit transformations are more robust and obviously,
provide more precise numerical results. In addition, the alternate
ways to select the lambda in the power transformation are also
offered to achieve much more appropriate outcomes.
Abstract: In this work we present a solution for DAGC (Digital
Automatic Gain Control) in WLAN receivers compatible to IEEE 802.11a/g standard. Those standards define communication in 5/2.4
GHz band using Orthogonal Frequency Division Multiplexing OFDM modulation scheme. WLAN Transceiver that we have used
enables gain control over Low Noise Amplifier (LNA) and a
Variable Gain Amplifier (VGA). The control over those signals is
performed in our digital baseband processor using dedicated hardware block DAGC. DAGC in this process is used to automatically control the VGA and LNA in order to achieve better
signal-to-noise ratio, decrease FER (Frame Error Rate) and hold the
average power of the baseband signal close to the desired set point.
DAGC function in baseband processor is done in few steps: measuring power levels of baseband samples of an RF signal,accumulating the differences between the measured power level and
actual gain setting, adjusting a gain factor of the accumulation, and
applying the adjusted gain factor the baseband values. Based on the measurement results of RSSI signal dependence to input power we have concluded that this digital AGC can be implemented applying
the simple linearization of the RSSI. This solution is very simple but also effective and reduces complexity and power consumption of the
DAGC. This DAGC is implemented and tested both in FPGA and in ASIC as a part of our WLAN baseband processor. Finally, we have integrated this circuit in a compact WLAN PCMCIA board based on MAC and baseband ASIC chips designed from us.
Abstract: Analysis of heart rate variability (HRV) has become a
popular non-invasive tool for assessing the activities of autonomic
nervous system. Most of the methods were hired from techniques
used for time series analysis. Currently used methods are time
domain, frequency domain, geometrical and fractal methods. A new
technique, which searches for pattern repeatability in a time series, is
proposed for quantifying heart rate (HR) time series. These set of
indices, which are termed as pattern repeatability measure and
pattern repeatability ratio are able to distinguish HR data clearly
from noise and electroencephalogram (EEG). The results of analysis
using these measures give an insight into the fundamental difference
between the composition of HR time series with respect to EEG and
noise.
Abstract: In this paper, the existence of periodic solutions of a delayed competitive system with the effect of toxic substances is investigated by using the Gaines and Mawhin,s continuation theorem of coincidence degree theory on time scales. New sufficient conditions are obtained for the existence of periodic solutions. The approach is unified to provide the existence of the desired solutions for the continuous differential equations and discrete difference equations. Moreover, The approach has been widely applied to study existence of periodic solutions in differential equations and difference equations.
Abstract: Deep Brain Stimulation or DBS is a surgical treatment for Parkinson-s Disease with three stimulation parameters: frequency, pulse width, and voltage. The parameters should be selected appropriately to achieve effective treatment. This selection now, performs clinically. The aim of this research is to study chaotic behavior of recorded tremor of patients under DBS in order to present a computational method to recognize stimulation optimum voltage. We obtained some chaotic features of tremor signal, and discovered embedding space of it has an attractor, and its largest Lyapunov exponent is positive, which show tremor signal has chaotic behavior, also we found out, in optimal voltage, entropy and embedding space variance of tremor signal have minimum values in comparison with other voltages. These differences can help neurologists recognize optimal voltage numerically, which leads to reduce patients' role and discomfort in optimizing stimulation parameters and to do treatment with high accuracy.