Abstract: In this paper, an extended study is performed on the
effect of different factors on the quality of vector data based on a
previous study. In the noise factor, one kind of noise that appears in
document images namely Gaussian noise is studied while the previous
study involved only salt-and-pepper noise. High and low levels of
noise are studied. For the noise cleaning methods, algorithms that were
not covered in the previous study are used namely Median filters and
its variants. For the vectorization factor, one of the best available
commercial raster to vector software namely VPstudio is used to
convert raster images into vector format. The performance of line
detection will be judged based on objective performance evaluation
method. The output of the performance evaluation is then analyzed
statistically to highlight the factors that affect vector quality.
Abstract: The empirical mode decomposition (EMD) represents any time series into a finite set of basis functions. The bases are termed as intrinsic mode functions (IMFs) which are mutually orthogonal containing minimum amount of cross-information. The EMD successively extracts the IMFs with the highest local frequencies in a recursive way, which yields effectively a set low-pass filters based entirely on the properties exhibited by the data. In this paper, EMD is applied to explore the properties of the multi-year air temperature and to observe its effects on climate change under global warming. This method decomposes the original time-series into intrinsic time scale. It is capable of analyzing nonlinear, non-stationary climatic time series that cause problems to many linear statistical methods and their users. The analysis results show that the mode of EMD presents seasonal variability. The most of the IMFs have normal distribution and the energy density distribution of the IMFs satisfies Chi-square distribution. The IMFs are more effective in isolating physical processes of various time-scales and also statistically significant. The analysis results also show that the EMD method provides a good job to find many characteristics on inter annual climate. The results suggest that climate fluctuations of every single element such as temperature are the results of variations in the global atmospheric circulation.
Abstract: This paper aims to present the reviews of the
application of neural network in shunt active power filter (SAPF).
From the review, three out of four components of SAPF structure,
which are harmonic detection component, compensating current
control, and DC bus voltage control, have been adopted some of
neural network architecture as part of its component or even
substitution. The objectives of most papers in using neural network in
SAPF are to increase the efficiency, stability, accuracy, robustness,
tracking ability of the systems of each component. Moreover,
minimizing unneeded signal due to the distortion is the ultimate goal
in applying neural network to the SAPF. The most famous
architecture of neural network in SAPF applications are ADALINE
and Backpropagation (BP).
Abstract: This paper presents the mathematical model and
control strategy on DQ frame of shunt active power filter. The
structure of the shunt active power filter is the voltage source inverter
(VSI). The pulse width modulation (PWM) with PI controller is used
in the paper. The concept of DQ frame to apply with the shunt active
power filter is described. Moreover, the detail of the PI controller
design for two current loops and one voltage loop are fully explained.
The DQ axis with Fourier (DQF) method is applied to calculate the
reference currents on DQ frame. The simulation results show that the
control strategy and the design method presented in the paper can
provide the good performance of the shunt active power filter.
Moreover, the %THD of the source currents after compensation can
follow the IEEE Std.519-1992.
Abstract: In this paper we examine the use of global texture analysis based approaches for the purpose of Persian font recognition in machine-printed document images. Most existing methods for font recognition make use of local typographical features and connected component analysis. However derivation of such features is not an easy task. Gabor filters are appropriate tools for texture analysis and are motivated by human visual system. Here we consider document images as textures and use Gabor filter responses for identifying the fonts. The method is content independent and involves no local feature analysis. Two different classifiers Weighted Euclidean Distance and SVM are used for the purpose of classification. Experiments on seven different type faces and four font styles show average accuracy of 85% with WED and 82% with SVM classifier over typefaces
Abstract: Vision based tracking problem is solved through a
combination of optical flow, MACH filter and log r-θ mapping.
Optical flow is used for detecting regions of movement in video
frames acquired under variable lighting conditions. The region of
movement is segmented and then searched for the target. A template
is used for target recognition on the segmented regions for detecting
the region of interest. The template is trained offline on a sequence of
target images that are created using the MACH filter and log r-θ
mapping. The template is applied on areas of movement in
successive frames and strong correlation is seen for in-class targets.
Correlation peaks above a certain threshold indicate the presence of
target and the target is tracked over successive frames.
Abstract: The paper deals with the comparison study of
harmonic detection methods for a shunt active power filter. The
%THD and the power factor value at the PCC point after
compensation are considered for the comparison. There are three
harmonic detection methods used in the paper that are synchronous
reference frame method, synchronous detection method, and DQ axis
with Fourier method. In addition, the ideal current source is used to
represent the active power filter by assuming an infinitely fast
controller action of the active power filter. The simulation results
show that the DQ axis with Fourier method provides the minimum
%THD after compensation compared with other methods. However,
the power factor value at the PCC point after compensation is slightly
lower than that of synchronous detection method.
Abstract: The proper selection of the AC-side passive filter
interconnecting the voltage source converter to the power supply is
essential to obtain satisfactory performances of an active power filter
system. The use of the LCL-type filter has the advantage of
eliminating the high frequency switching harmonics in the current
injected into the power supply. This paper is mainly focused on
analyzing the influence of the interface filter parameters on the active
filtering performances. Some design aspects are pointed out. Thus,
the design of the AC interface filter starts from transfer functions by
imposing the filter performance which refers to the significant current
attenuation of the switching harmonics without affecting the
harmonics to be compensated. A Matlab/Simulink model of the entire
active filtering system including a concrete nonlinear load has been
developed to examine the system performances. It is shown that a
gamma LC filter could accomplish the attenuation requirement of the
current provided by converter. Moreover, the existence of an optimal
value of the grid-side inductance which minimizes the total harmonic
distortion factor of the power supply current is pointed out.
Nevertheless, a small converter-side inductance and a damping
resistance in series with the filter capacitance are absolutely needed
in order to keep the ripple and oscillations of the current at the
converter side within acceptable limits. The effect of change in the
LCL-filter parameters is evaluated. It is concluded that good active
filtering performances can be achieved with small values of the
capacitance and converter-side inductance.
Abstract: A study was undertaken to assess the potential of an
Algal Turf Scrubber to remove nitrogen from aquaculture effluent to
reduce environmental pollution. High total ammonia nitrogen
concentrations were introduced to an Algal Turf Scrubber developed
under varying hydraulic surface loading rates of African catfish
(Clarius gariepinus) effluent in a recirculating aquaculture system.
Nutrient removal rates were not affected at total suspended solids
concentration of up to 0.04g TSS/l (P > 0.05). Nitrogen removal
rates 0.93-0.99g TAN/m²/d were recorded at very high loading rates
3.76-3.81 g TAN/m²/d. Total ammonia removal showed ½ order
kinetics between 1.6 to 2.3mg/l Total Ammonia Nitrogen
concentrations. Nitrogen removal increased with its loading, which
increased with hydraulic surface loading rate. Total Ammonia
Nitrogen removal by Algal turf scrubber was higher than reported
values for fluidized bed filters and trickling filters. The algal turf
scrubber also effectively removed nitrate thereby reducing the need
for water exchange.
Abstract: In a world worried about water resources with the
shadow of drought and famine looming all around, the quality of
water is as important as its quantity. The source of all concerns is the
constant reduction of per capita quality water for different uses.
Iran With an average annual precipitation of 250 mm compared to
the 800 mm world average, Iran is considered a water scarce country
and the disparity in the rainfall distribution, the limitations of
renewable resources and the population concentration in the margins
of desert and water scarce areas have intensified the problem.
The shortage of per capita renewable freshwater and its poor
quality in large areas of the country, which have saline, brackish or
hard water resources, and the profusion of natural and artificial
pollutant have caused the deterioration of water quality.
Among methods of treatment and use of these waters one can refer
to the application of membrane technologies, which have come into
focus in recent years due to their great advantages. This process is
quite efficient in eliminating multi-capacity ions; and due to the
possibilities of production at different capacities, application as
treatment process in points of use, and the need for less energy in
comparison to Reverse Osmosis processes, it can revolutionize the
water and wastewater sector in years to come. The article studied the
different capacities of water resources in the Persian Gulf and Oman
Sea watershed basins, and processes the possibility of using
nanofiltration process to treat brackish and non-conventional waters
in these basins.
Abstract: In this paper newly reported Cosh window function is
used in the design of prototype filter for M-channel Near Perfect
Reconstruction (NPR) Cosine Modulated Filter Bank (CMFB). Local
search optimization algorithm is used for minimization of distortion
parameters by optimizing the filter coefficients of prototype filter.
Design examples are presented and comparison has been made with
Kaiser window based filterbank design of recently reported work.
The result shows that the proposed design approach provides lower
distortion parameters and improved far-end suppression than the
Kaiser window based design of recent reported work.
Abstract: Cancers could normally be marked by a number of
differentially expressed genes which show enormous potential as
biomarkers for a certain disease. Recent years, cancer classification
based on the investigation of gene expression profiles derived by
high-throughput microarrays has widely been used. The selection of
discriminative genes is, therefore, an essential preprocess step in
carcinogenesis studies. In this paper, we have proposed a novel gene
selector using information-theoretic measures for biological
discovery. This multivariate filter is a four-stage framework through
the analyses of feature relevance, feature interdependence, feature
redundancy-dependence and subset rankings, and having been
examined on the colon cancer data set. Our experimental result show
that the proposed method outperformed other information theorem
based filters in all aspect of classification errors and classification
performance.
Abstract: In this article, a method has been offered to classify
normal and defective tiles using wavelet transform and artificial
neural networks. The proposed algorithm calculates max and min
medians as well as the standard deviation and average of detail
images obtained from wavelet filters, then comes by feature vectors
and attempts to classify the given tile using a Perceptron neural
network with a single hidden layer. In this study along with the
proposal of using median of optimum points as the basic feature and
its comparison with the rest of the statistical features in the wavelet
field, the relational advantages of Haar wavelet is investigated. This
method has been experimented on a number of various tile designs
and in average, it has been valid for over 90% of the cases. Amongst
the other advantages, high speed and low calculating load are
prominent.
Abstract: Over a million tonnes of cigarette butts (CBs) are produced worldwide annually. These CBs accumulate in the environment due to the poor biodegradability of the cellulose acetate filters and pose a serious environmental risk. This paper presents some of the results from a continuing study on recycling CBs into fired clay bricks. Properties including compressive strength, flexural strength, density, water absorption and thermal conductivity of fired clay bricks are reported and discussed. Furthermore, leaching of heavy metals from the manufactured clay bricks was tested. The results show that the density of fired bricks was reduced by about 8 – 30 %, depending on the percentage of CBs incorporated into the raw materials. The compressive strength of bricks tested was 12.57, 5.22 and 3.00 MPa for 2.5, 5.0 and 10 % CB content respectively. Water absorption and initial rate of absorption values increased as density, and hence porosity, of bricks decreased with increasing CB volume. The leaching test results revealed trace amounts of heavy metals.
Abstract: This paper presents a novel control strategy of a threephase
four-wire Unified Power Quality (UPQC) for an improvement
in power quality. The UPQC is realized by integration of series and
shunt active power filters (APFs) sharing a common dc bus capacitor.
The shunt APF is realized using a thee-phase, four leg voltage source
inverter (VSI) and the series APF is realized using a three-phase,
three leg VSI. A control technique based on unit vector template
technique (UTT) is used to get the reference signals for series APF,
while instantaneous sequence component theory (ISCT) is used for
the control of Shunt APF. The performance of the implemented
control algorithm is evaluated in terms of power-factor correction,
load balancing, neutral source current mitigation and mitigation of
voltage and current harmonics, voltage sag and swell in a three-phase
four-wire distribution system for different combination of linear and
non-linear loads. In this proposed control scheme of UPQC, the
current/voltage control is applied over the fundamental supply
currents/voltages instead of fast changing APFs currents/voltages,
there by reducing the computational delay and the required sensors.
MATLAB/Simulink based simulations are obtained, which support
the functionality of the UPQC. MATLAB/Simulink based
simulations are obtained, which support the functionality of the
UPQC.
Abstract: A high-frequency low-power sinusoidal quadrature
oscillator is presented through the use of two 2nd-order low-pass
current-mirror (CM)-based filters, a 1st-order CM low-pass filter and
a CM bilinear transfer function. The technique is relatively simple
based on (i) inherent time constants of current mirrors, i.e. the
internal capacitances and the transconductance of a diode-connected
NMOS, (ii) a simple negative resistance RN formed by a resistor load
RL of a current mirror. Neither external capacitances nor inductances
are required. As a particular example, a 1.9-GHz, 0.45-mW, 2-V
CMOS low-pass-filter-based all-current-mirror sinusoidal quadrature
oscillator is demonstrated. The oscillation frequency (f0) is 1.9 GHz
and is current-tunable over a range of 370 MHz or 21.6 %. The
power consumption is at approximately 0.45 mW. The amplitude
matching and the quadrature phase matching are better than 0.05 dB
and 0.15°, respectively. Total harmonic distortions (THD) are less
than 0.3 %. At 2 MHz offset from the 1.9 GHz, the carrier to noise
ratio (CNR) is 90.01 dBc/Hz whilst the figure of merit called a
normalized carrier-to-noise ratio (CNRnorm) is 153.03 dBc/Hz. The
ratio of the oscillation frequency (f0) to the unity-gain frequency (fT)
of a transistor is 0.25. Comparisons to other approaches are also
included.
Abstract: In this paper, we propose a chaotic cipher system consisting of Improved Volterra Filters and the mapping that is created from the actual voice by using Radial Basis Function Network. In order to achieve a practical system, the system supposes to use the digital communication line, such as the Internet, to maintain the parameter matching between the transmitter and receiver sides. Therefore, in order to withstand the attack from outside, it is necessary that complicate the internal state and improve the sensitivity coefficient. In this paper, we validate the robustness of proposed method from three perspectives of "Chaotic properties", "Randomness", "Coefficient sensitivity".