Abstract: A DC-to-DC converter for applications involving a
source with widely varying voltage conditions with loads requiring
constant voltage from full load down to no load is presented.
The switching regulator considered is a Buck converter with Pulse
Skipping Modulation control whereby pulses applied to the switch
are blocked or released on output voltage crossing a predetermined
value. Results of the study on the performance of regulator circuit
are presented. The regulator regulates over a wide input voltage range
with slightly higher ripple content and good transient response. Input
current spectrum indicates a good EMI performance with crowding
of components at low frequency range.
Abstract: Sinc-collocation scheme is one of the new techniques
used in solving numerical problems involving integral equations. This
method has been shown to be a powerful numerical tool for finding
fast and accurate solutions. So, in this paper, some properties of the
Sinc-collocation method required for our subsequent development
are given and are utilized to reduce integral equation of the first
kind to some algebraic equations. Then convergence with exponential
rate is proved by a theorem to guarantee applicability of numerical
technique. Finally, numerical examples are included to demonstrate
the validity and applicability of the technique.
Abstract: Calcium [Ca2+] dynamics is studied as a potential form
of neuron excitability that can control many irregular processes like
metabolism, secretion etc. Ca2+ ion enters presynaptic terminal and
increases the synaptic strength and thus triggers the neurotransmitter
release. The modeling and analysis of calcium dynamics in neuron
cell becomes necessary for deeper understanding of the processes
involved. A mathematical model has been developed for cylindrical
shaped neuron cell by incorporating physiological parameters like
buffer, diffusion coefficient, and association rate. Appropriate initial
and boundary conditions have been framed. The closed form solution
has been developed in terms of modified Bessel function. A computer
program has been developed in MATLAB 7.11 for the whole
approach.
Abstract: In this paper, the effect of transmission codes on the
performance of coherent square M-ary quadrature amplitude
modulation (CSMQAM) under hybrid selection/maximal-ratio
combining (H-S/MRC) diversity is analysed. The fading channels are
modeled as frequency non-selective slow independent and identically
distributed Rayleigh fading channels corrupted by additive white
Gaussian noise (AWGN). The results for coded MQAM are
computed numerically for the case of (24,12) extended Golay code
and compared with uncoded MQAM under H-S/MRC diversity by
plotting error probabilities versus average signal to noise ratio (SNR)
for various values L and N in order to examine the improvement in
the performance of the digital communications system as the number
of selected diversity branches is increased. The results for no
diversity, conventional SC and Lth order MRC schemes are also
plotted for comparison. Closed form analytical results derived in this
paper are sufficiently simple and therefore can be computed
numerically without any approximations. The analytical results
presented in this paper are expected to provide useful information
needed for design and analysis of digital communication systems
over wireless fading channels.
Abstract: There are two major variants of the Simplex
Algorithm: the revised method and the standard, or tableau method.
Today, all serious implementations are based on the revised method
because it is more efficient for sparse linear programming problems.
Moreover, there are a number of applications that lead to dense linear
problems so our aim in this paper is to present some computational
results on parallel implementation of dense Simplex Method. Our
implementation is implemented on a SMP cluster using C
programming language and the Message Passing Interface MPI.
Preliminary computational results on randomly generated dense
linear programs support our results.
Abstract: In the past 20 years the economy of the Czech
Republic has experienced substantial changes. In the 1990s the
development was affected by the transformation which sought to
establish the right conditions for privatization and creation of
elementary market relations. In the last decade the characteristic
elements such as private ownership and corresponding institutional
framework have been strengthened. This development was marked by
the accession of the Czech Republic to the EU. The Czech Republic
is striving to reduce the difference between its level of economic
development and the quality of institutional framework in
comparison with other developed countries. The process of finding
the adequate solutions has been hampered by the negative impact of
the world financial crisis on the Czech Republic and the standard of
living of its inhabitants. This contribution seeks to address the
question of whether and to which extent the economic development
of the transitive Czech economy is affected by the change in
behaviour of households and their tendency to consumption, i.e. in
the sense of reduction or increase in demand for goods and services.
It aims to verify whether the increasing trend of household
indebtedness and decreasing trend of saving pose a significant risk in
the Czech Republic. At a general level the analysis aims to contribute
to finding an answer to the question of whether the debt increase of
Czech households is connected to the risk of "eating through" the
borrowed money and whether Czech households risk falling into a
debt trap. In addition to household indebtedness risks in the Czech
Republic the analysis will focus on identification of specifics of the
transformation phase of the Czech economy in comparison with the
EU countries, or selected OECD countries.
Abstract: P16/INK4A is tumor suppressor protein that plays a critical role in cell cycle regulation. Loss of P16 protein expression has been implicated in pathogenesis of many cancers, including lymphoma. Therefore, we sought to investigate if loss of P16 protein expression is associated with lymphoma and/or any specific lymphoma subtypes (Hodgkin-s lymphoma (HL) and nonHodgkin-s lymphoma (NHL)). Fifty-five lymphoma cases consisted of 30 cases of HL and 25 cases of NHL, with an age range of 3 to 78 years, were examined for loss of P16 by immunohistochemical technique using a specific antibody reacting against P16. In total, P16 loss was seen in 33% of all lymphoma cases. P16 loss was identified in 47.7% of HL cases. In contrast, only 16% of NHL showed loss of P16. Loss of P16 was seen in 67% of HL patients with 50 years of age or older, whereas P16 loss was found in only 42% of HL patients with less than 50 years of age. P16 loss in HL is somewhat higher in male (55%) than in female (30%). In subtypes of HL, P16 loss was found exclusively in all cases of lymphocyte depletion, lymphocyte predominance and unclassified cases, whereas P16 loss was seen in 39% of mixed cellularity and 29% of nodular sclerosis cases. In low grade NHL patients, P16 loss was seen in approximately one-third of cases, whereas no or very rare of P16 loss was found in intermediate and high grade cases. P16 loss did not show any correlation with age or gender of NHL patients. In conclusion, the high rate of P16 loss seen in our study suggests that loss of P16 expression plays a critical role in the pathogenesis of lymphoma, particularly with HL.
Abstract: this paper focuses on designing of PSS and SVC
controller based on chaos and PSO algorithms to improve the
stability of power system. Single machine infinite bus (SMIB) system
with SVC located at the terminal of generator has been considered to
evaluate the proposed controllers where both SVC and PSS have the
same controller. The coefficients of PSS and SVC controller have
been optimized by chaos and PSO algorithms. Finally the system
with proposed controllers has been simulated for the special
disturbance in input power of generator, and then the dynamic
responses of generator have been presented. The simulation results
showed that the system composed with recommended controller has
outstanding operation in fast damping of oscillations of power system.
Abstract: Nodes in mobile Ad Hoc Network (MANET) do not
rely on a central infrastructure but relay packets originated by other
nodes. Mobile ad hoc networks can work properly only if the
participating nodes collaborate in routing and forwarding. For
individual nodes it might be advantageous not to collaborate, though.
In this conceptual paper we propose a new approach based on
relationship among the nodes which makes them to cooperate in an
Adhoc environment. The trust unit is used to calculate the trust
values of each node in the network. The calculated trust values are
being used by the relationship estimator to determine the relationship
status of nodes. The proposed enhanced protocol was compared with
the standard DSR protocol and the results are analyzed using the
network simulator-2.
Abstract: This paper presents a cold chain monitoring system which focuses on assessment of quality and dynamic pricing information about food in cold chain. Cold chain is composed of many actors and stages; however it can be seen as a single entity since a breakdown in temperature control at any stage can impact the final quality of the product. In a cold chain, the shelf life, quality, and safety of perishable food throughout the supply chain is greatly impacted by environmental factors especially temperature. In this paper, a prototype application is implemented to retrieve timetemperature history, the current quality and the dynamic price setting according to changing quality impacted by temperature fluctuations in real-time.
Abstract: Work-life balance has been acknowledged and
promoted for the sake of employee retention. It is essential for a
manager to realize the human resources situation within a company to
help employees work happily and perform at their best. This paper
suggests knowledge management and critical thinking are useful to
motivate employees to think about their work-life balance. A
qualitative case study is presented, which aimed to discover the
meaning of work-life balance-s meaning from the perspective of Thai
knowledge workers and how it affects their decision-making towards
work resignation. Results found three types of work-life balance
dimensions; a work- life balance including a workplace and a private
life setting, an organizational working life balance only, and a worklife
balance only in a private life setting. These aspects all influenced
the decision-making of the employees. Factors within a theme of an
organizational work-life balance were involved with systematic
administration, fair treatment, employee recognition, challenging
assignments to gain working experience, assignment engagement,
teamwork, relationship with superiors, and working environment,
while factors concerning private life settings were about personal
demands such as an increasing their salary or starting their own
business.
Abstract: In this contribution, a way to enhance the performance of the classic Genetic Algorithm is proposed. The idea of restarting a Genetic Algorithm is applied in order to obtain better knowledge of the solution space of the problem. A new operator of 'insertion' is introduced so as to exploit (utilize) the information that has already been collected before the restarting procedure. Finally, numerical experiments comparing the performance of the classic Genetic Algorithm and the Genetic Algorithm with restartings, for some well known test functions, are given.
Abstract: The recent trend in field oriented control (FOC) is towards the use of sensorless techniques that avoid the use of speed sensor and flux sensor. Sensors are replaced by estimators or observers to minimise the cost and increase the reliability. In this paper an anlyse of perfomance of a MRAS used in sensorless control of induction motors and sensitvity to machine parameters change are studied.
Abstract: The experimental thermal performance of two heat
exchangers in closed-wet cooling tower (CWCT) was investigated in
this study. The test sections are heat exchangers which have multi path
that is used as the entrance of cooling water and are consisting of
bare-type copper tubes between 15.88mm and 19.05mm. The process
fluids are the cooling water that flows from top part of heat exchanger
to bottom side in the inner side of tube, and spray water that flows
gravitational direction in the outer side of it. Air contacts its outer side
of that as it counterflows. Heat and mass transfer coefficients and
cooling capacity were calculated with variations of process fluids,
multi path and different diameter tubes to figure out the performance
of characteristics of CWCT.
The main results were summarized as follows: The results show this
experiment is reliable with values of heat and mass transfer
coefficients comparing to values of correlations. Heat and mass
transfer coefficients and cooling capacity of two paths are higher than
these with one path using 15.88 and 19.05mm tubes. Cooling capacity
per unit volume with 15.88mm tube using one and two paths are
higher than 19.05mm tube due to increase of surface area per unit
volume.
Abstract: The purpose of this study is to derive optimal shapes of
a body located in viscous flows by the finite element method using the
acoustic velocity and the four-step explicit scheme. The formulation
is based on an optimal control theory in which a performance function
of the fluid force is introduced. The performance function should be
minimized satisfying the state equation. This problem can be transformed
into the minimization problem without constraint conditions
by using the adjoint equation with adjoint variables corresponding to
the state equation. The performance function is defined by the drag
and lift forces acting on the body. The weighted gradient method
is applied as a minimization technique, the Galerkin finite element
method is used as a spatial discretization and the four-step explicit
scheme is used as a temporal discretization to solve the state equation
and the adjoint equation. As the interpolation, the orthogonal basis
bubble function for velocity and the linear function for pressure
are employed. In case that the orthogonal basis bubble function is
used, the mass matrix can be diagonalized without any artificial
centralization. The shape optimization is performed by the presented
method.
Abstract: Linear cryptanalysis methods are rarely used to improve the security of chaotic stream ciphers. In this paper, we apply linear cryptanalysis to a chaotic stream cipher which was designed by strictly using the basic design criterion of cryptosystem – confusion and diffusion. We show that this well-designed chaos-based stream cipher is still insecure against distinguishing attack. This distinguishing attack promotes the further improvement of the cipher.
Abstract: In this article the influence of higher frequency effects
in addition to a special damper design on the electrical behavior of a
synchronous generator main exciter machine is investigated. On the
one hand these machines are often highly stressed by harmonics from
the bridge rectifier thus facing additional eddy current losses. On the
other hand the switching may cause the excitation of dangerous
voltage peaks in resonant circuits formed by the diodes of the
rectifier and the commutation reactance of the machine. Therefore
modern rotating exciters are treated like synchronous generators
usually modeled with a second order equivalent circuit. Hence the
well known Standstill Frequency Response Test (SSFR) method is
applied to a test machine in order to determine parameters for the
simulation. With these results it is clearly shown that higher
frequencies have a strong impact on the conventional equivalent
circuit model. Because of increasing field displacement effects in the
stranded armature winding the sub-transient reactance is even smaller
than the armature leakage at high frequencies. As a matter of fact this
prevents the algorithm to find an equivalent scheme. This issue is
finally solved using Laplace transfer functions fully describing the
transient behavior at the model ports.
Abstract: In this paper, a technique is proposed to implement
an artificial voltage-controlled capacitance or inductance which can
replace the well-known varactor diode in many applications. The
technique is based on injecting the current of a voltage-controlled
current source onto a fixed capacitor or inductor. Then, by controlling
the transconductance of the current source by an external bias voltage,
a voltage-controlled capacitive or inductive reactance is obtained.
The proposed voltage-controlled reactance devices can be designed
to work anywhere in the frequency spectrum. Practical circuits for the
proposed voltage-controlled reactances are suggested and simulated.
Abstract: The purposes of this research were to study the citizen
participation in preventing illegal drugs in one of a poor and small
community of Bangkok, Thailand and to compare the level of
participation and concern of illegal drugs problem by using
demographic variables. This paper drew upon data collected from a
local citizens survey conducted in Bangkok, Thailand during summer
of 2012. A total of 200 respondents were elicited as data input for,
and one way ANOVA test. The findings revealed that the overall
citizen participation was in the level of medium. The mean score
showed that benefit from the program was ranked as the highest and
the decision to participate was ranked as second while the follow-up
of the program was ranked as the lowest.
In terms of the difference in demographic such as gender, age,
level of education, income, and year of residency, the hypothesis
testing’s result disclosed that there were no difference in their level
of participation. However, difference in occupation showed a
difference in their level of participation and concern which was
significant at the 0.05 confidence level.
Abstract: Traditional principal components analysis (PCA)
techniques for face recognition are based on batch-mode training
using a pre-available image set. Real world applications require that
the training set be dynamic of evolving nature where within the
framework of continuous learning, new training images are
continuously added to the original set; this would trigger a costly
continuous re-computation of the eigen space representation via
repeating an entire batch-based training that includes the old and new
images. Incremental PCA methods allow adding new images and
updating the PCA representation. In this paper, two incremental
PCA approaches, CCIPCA and IPCA, are examined and compared.
Besides, different learning and testing strategies are proposed and
applied to the two algorithms. The results suggest that batch PCA is
inferior to both incremental approaches, and that all CCIPCAs are
practically equivalent.