Abstract: This paper investigates the characteristics of wall
pressure fluctuations in naturally developing boundary layer flows
on axisymmetric bodies experimentally. The axisymmetric body has
a modified ellipsoidal blunt nose. Flush-mounted microphones are
used to measure the wall pressure fluctuations in the boundary layer
flow over the body. The measurements are performed in a low noise
wind tunnel. It is found that the correlation between the flow regime
and the characteristics of the pressure fluctuations is distinct. The
process from small fluctuation in laminar flow to large fluctuation in
turbulent flow is investigated. Tollmien-Schlichting wave (T-S wave)
is found to generate and develop in transition. Because of the T-S
wave, the wall pressure fluctuations in the transition region are higher
than those in the turbulent boundary layer.
Abstract: Digital images are widely used in computer
applications. To store or transmit the uncompressed images
requires considerable storage capacity and transmission bandwidth.
Image compression is a means to perform transmission or storage of
visual data in the most economical way. This paper explains about
how images can be encoded to be transmitted in a multiplexing
time-frequency domain channel. Multiplexing involves packing
signals together whose representations are compact in the working
domain. In order to optimize transmission resources each 4 × 4
pixel block of the image is transformed by a suitable polynomial
approximation, into a minimal number of coefficients. Less than
4 × 4 coefficients in one block spares a significant amount of
transmitted information, but some information is lost. Different
approximations for image transformation have been evaluated as
polynomial representation (Vandermonde matrix), least squares +
gradient descent, 1-D Chebyshev polynomials, 2-D Chebyshev
polynomials or singular value decomposition (SVD). Results have
been compared in terms of nominal compression rate (NCR),
compression ratio (CR) and peak signal-to-noise ratio (PSNR)
in order to minimize the error function defined as the difference
between the original pixel gray levels and the approximated
polynomial output. Polynomial coefficients have been later encoded
and handled for generating chirps in a target rate of about two
chirps per 4 × 4 pixel block and then submitted to a transmission
multiplexing operation in the time-frequency domain.
Abstract: Fluctuations of Schottky diode parameters in a
structure of the mixer are investigated. These fluctuations are
manifested in two ways. At the first, they lead to fluctuations in the
transfer factor that is lead to the amplitude fluctuations in the signal
of intermediate frequency. On the basis of the measurement data of
1/f noise of the diode at forward current, the estimation of a spectrum
of relative fluctuations in transfer factor of the mixer is executed.
Current dependence of the spectrum of relative fluctuations in
transfer factor of the mixer and dependence of the spectrum of
relative fluctuations in transfer factor of the mixer on the amplitude
of the heterodyne signal are investigated. At the second, fluctuations
in parameters of the diode lead to occurrence of 1/f noise in the
output signal of the mixer. This noise limits the sensitivity of the
mixer to the value of received signal.
Abstract: In this paper, a robust fault detection and isolation
(FDI) scheme is developed to monitor a multivariable nonlinear
chemical process called the Chylla-Haase polymerization reactor,
when it is under the cascade PI control. The scheme employs a radial
basis function neural network (RBFNN) in an independent mode to
model the process dynamics, and using the weighted sum-squared
prediction error as the residual. The Recursive Orthogonal Least
Squares algorithm (ROLS) is employed to train the model to
overcome the training difficulty of the independent mode of the
network. Then, another RBFNN is used as a fault classifier to isolate
faults from different features involved in the residual vector. Several
actuator and sensor faults are simulated in a nonlinear simulation of
the reactor in Simulink. The scheme is used to detect and isolate the
faults on-line. The simulation results show the effectiveness of the
scheme even the process is subjected to disturbances and
uncertainties including significant changes in the monomer feed rate,
fouling factor, impurity factor, ambient temperature, and
measurement noise. The simulation results are presented to illustrate
the effectiveness and robustness of the proposed method.
Abstract: Chatter vibrations, occurring during cutting process,
cause vibration between the cutting tool and workpiece, which
deteriorates surface roughness and reduces tool life. The purpose of
this study is to investigate the influence of cutting parameters and
tool construction on surface roughness and vibration in turning of
aluminum alloy AA2024. A new design of cutting tool is proposed,
which is filled up with epoxy granite in order to improve damping
capacity of the tool. Experiments were performed at the lathe using
carbide cutting insert coated with TiC and two different cutting tools
made of AISI 5140 steel. Taguchi L9 orthogonal array was applied to
design of experiment and to optimize cutting conditions. By the help
of signal-to-noise ratio and analysis of variance the optimal cutting
condition and the effect of the cutting parameters on surface
roughness and vibration were determined. Effectiveness of Taguchi
method was verified by confirmation test. It was revealed that new
cutting tool with epoxy granite has reduced vibration and surface
roughness due to high damping properties of epoxy granite in
toolholder.
Abstract: Fading noise degrades the performance of cellular
communication, most notably in femto- and pico-cells in 3G and 4G
systems. When the wireless channel consists of a small number of
scattering paths, the statistics of fading noise is not analytically
tractable and poses a serious challenge to developing closed
canonical forms that can be analysed and used in the design of
efficient and optimal receivers. In this context, noise is multiplicative
and is referred to as stochastically local fading. In many analytical
investigation of multiplicative noise, the exponential or Gamma
statistics are invoked. More recent advances by the author of this
paper utilized a Poisson modulated-weighted generalized Laguerre
polynomials with controlling parameters and uncorrelated noise
assumptions. In this paper, we investigate the statistics of multidiversity
stochastically local area fading channel when the channel
consists of randomly distributed Rayleigh and Rician scattering
centers with a coherent Nakagami-distributed line of sight component
and an underlying doubly stochastic Poisson process driven by a
lognormal intensity. These combined statistics form a unifying triply
stochastic filtered marked Poisson point process model.
Abstract: Magnetic Resonance Imaging (MRI) is one of the
most important medical imaging modality. Subjective assessment of
the image quality is regarded as the gold standard to evaluate MR
images. In this study, a database of 210 MR images which contains
ten reference images and 200 distorted images is presented. The
reference images were distorted with four types of distortions: Rician
Noise, Gaussian White Noise, Gaussian Blur and DCT compression.
The 210 images were assessed by ten subjects. The subjective scores
were presented in Difference Mean Opinion Score (DMOS). The
DMOS values were compared with four FR-IQA metrics. We have
used Pearson Linear Coefficient (PLCC) and Spearman Rank Order
Correlation Coefficient (SROCC) to validate the DMOS values. The
high correlation values of PLCC and SROCC shows that the DMOS
values are close to the objective FR-IQA metrics.
Abstract: Foundation differential settlement and supported
structure tilting are an occasionally occurred engineering problem.
This may be caused by overloading, changes in ground soil properties
or unsupported nearby excavations. Engineering thinking points
directly toward the logic solution for such problem by uplifting the
settled side. This can be achieved with deep foundation elements
such as micro-piles and macro-piles™, jacked piers, and helical piers,
jet grouted mortar columns, compaction grout columns, cement
grouting or with chemical grouting, or traditional pit underpinning
with concrete and mortar. Although, some of these techniques offer
economic, fast and low noise solutions, many of them are quite the
contrary. For tilted structures, with the limited inclination, it may be much
easier to cause a balancing settlement on the less-settlement side
which shall be done carefully in a proper rate. This principal has been
applied in Leaning Tower of Pisa stabilization with soil extraction
from the ground surface. In this research, the authors attempt to
introduce a new solution with a different point of view. So, the
micro-tunneling technique is presented in here as an intended ground
deformation cause. In general, micro-tunneling is expected to induce
limited ground deformations. Thus, the researchers propose to apply
the technique to form small size ground unsupported holes to produce
the target deformations. This shall be done in four phases: 1.
Application of one or more micro-tunnels, regarding the existing
differential settlement value, under the raised side of the tilted
structure. 2. For each individual tunnel, the lining shall be pulled out
from both sides (from jacking and receiving shafts) in the slow rate.
3. If required, according to calculations and site records, an additional
surface load can be applied on the raised foundation side. 4. Finally, a
strengthening soil grouting shall be applied for stabilization after
adjustment. A finite element based numerical model is presented to simulate
the proposed construction phases for different tunneling positions and
tunnels group. For each case, the surface settlements are calculated
and induced plasticity points are checked. These results show the
impact of the suggested procedure on the tilted structure and its
feasibility. Comparing results also show the importance of the
position selection and tunnels group gradual effect. Thus, a new
engineering solution is presented to one of the structural and
geotechnical engineering challenges.
Abstract: In this paper, a novel fuzzy approach is developed
while solving the Dynamic Routing and Wavelength Assignment
(DRWA) problem in optical networks with Wavelength Division
Multiplexing (WDM). In this work, the effect of nonlinear and linear
impairments such as Four Wave Mixing (FWM) and amplifier
spontaneous emission (ASE) noise are incorporated respectively. The
novel algorithm incorporates fuzzy logic controller (FLC) to reduce
the effect of FWM noise and ASE noise on a requested lightpath
referred in this work as FWM aware fuzzy dynamic routing and
wavelength assignment algorithm. The FWM crosstalk products and
the static FWM noise power per link are pre computed in order to
reduce the set up time of a requested lightpath, and stored in an
offline database. These are retrieved during the setting up of a
lightpath and evaluated online taking the dynamic parameters like
cost of the links into consideration.
Abstract: This article describes the results of research focused
on quality of railway freight transport services. Improvement of these
services has a crucial importance in customer considering on the
future use of railway transport. Processes filling the customer
demands and output quality assessment were defined as a part of the
research. In this contribution is introduced the map of quality
planning and the algorithm of applied methodology. It characterizes a
model which takes into account characters of transportation with
linking a perception services quality in ordinary and extraordinary
operation. Despite the fact that rail freight transport has its solid
position in the transport market, lots of carriers worldwide have been
experiencing a stagnation for a couple of years. Therefore, specific
results of the research have a significant importance and belong to
numerous initiatives aimed to develop and support railway transport
not only by creating a single railway area or reducing noise but also
by promoting railway services. This contribution is focused also on
the application of dynamic quality models which represent an
innovative method of evaluation quality services. Through this
conception, time factor, expected, and perceived quality in each
moment of the transportation process can be taken into account.
Abstract: The noise is one of the negative elements which
affects the human health. This article presents the measurement of
emitted noise by road vehicle and its parts during the operation.
Measurement was done in the interior of common passenger cars
with a digital sound meter. The results compare the noise value in
different cars with different body shape, which influences the driver’s
health. Transport has considerable ecological effects; many of them
are detrimental to environmental sustainability. Roads and traffic
exert a variety of direct and mostly detrimental effects on nature.
Abstract: Multiple Input Multiple Output (MIMO) systems are
wireless systems with multiple antenna elements at both ends of the
link. Wireless communication systems demand high data rate and
spectral efficiency with increased reliability. MIMO systems have
been popular techniques to achieve these goals because increased
data rate is possible through spatial multiplexing scheme and
diversity. Spatial Multiplexing (SM) is used to achieve higher
possible throughput than diversity. In this paper, we propose a Zero-
Forcing (ZF) detection using a combination of Ordered Successive
Interference Cancellation (OSIC) and Zero Forcing using
Interference Cancellation (ZF-IC). The proposed method used an
OSIC based on Signal to Noise Ratio (SNR) ordering to get the
estimation of last symbol, then the estimated last symbol is
considered to be an input to the ZF-IC. We analyze the Bit Error Rate
(BER) performance of the proposed MIMO system over Rayleigh
Fading Channel, using Binary Phase Shift Keying (BPSK)
modulation scheme. The results show better performance than the
previous methods.
Abstract: Since the last decade, there has been a rapid growth in
digital multimedia, such as high-resolution media files and threedimentional
movies. Hence, there is a need for large digital storage
such as Hard Disk Drive (HDD). As such, users expect to have a
quieter HDD in their laptop. In this paper, a jury test has been
conducted on a group of 34 people where 17 of them are students
who are the potential consumer, and the remaining are engineers who
know the HDD. A total 13 HDD sound samples have been selected
from over hundred HDD noise recordings. These samples are
selected based on an agreed subjective feeling. The samples are
played to the participants using head acoustic playback system, which
enabled them to experience as similar as possible the same
environment as have been recorded. Analysis has been conducted and
the obtained results have indicated different group has different
perception over the noises. Two neural network-based acoustic
annoyance models are established based on back propagation neural
network. Four psychoacoustic metrics, loudness, sharpness,
roughness and fluctuation strength, are used as the input of the
model, and the subjective evaluation results are taken as the output.
The developed models are reasonably accurate in simulating both
training and test samples.
Abstract: Lots of motors have been being used in industry.
Therefore many researchers have studied about the failure diagnosis of
motors. In this paper, the effect of measuring environment for
diagnosis of gear fault connected to a motor shaft is studied. The fault
diagnosis is executed through the comparison of normal gear and
abnormal gear. The measured FFT data are compared with the normal
data and analyzed for q-axis current, noise and vibration. For bad and
good environment, the diagnosis results are compared. From these, it
is shown that the bad measuring environment may not be able to detect
exactly the motor gear fault. Therefore it is emphasized that the
measuring environment should be carefully prepared.
Abstract: This paper addresses the issue of resource allocation
in the emerging cognitive technology. Focusing the Quality of
Service (QoS) of Primary Users (PU), a novel method is proposed for
the resource allocation of Secondary Users (SU). In this paper, we
propose the unique Utility Function in the game theoretic model of
Cognitive Radio which can be maximized to increase the capacity of
the Cognitive Radio Network (CRN) and to minimize the
interference scenario. Utility function is formulated to cater the need
of PUs by observing Signal to Noise ratio. Existence of Nash
Equilibrium for the postulated game is established.
Abstract: In this paper, a spatial multiple-kernel fuzzy C-means (SMKFCM) algorithm is introduced for segmentation problem. A linear combination of multiples kernels with spatial information is used in the kernel FCM (KFCM) and the updating rules for the linear coefficients of the composite kernels are derived as well. Fuzzy cmeans (FCM) based techniques have been widely used in medical image segmentation problem due to their simplicity and fast convergence. The proposed SMKFCM algorithm provides us a new flexible vehicle to fuse different pixel information in medical image segmentation and detection of MR images. To evaluate the robustness of the proposed segmentation algorithm in noisy environment, we add noise in medical brain tumor MR images and calculated the success rate and segmentation accuracy. From the experimental results it is clear that the proposed algorithm has better performance than those of other FCM based techniques for noisy medical MR images.
Abstract: The Adaptive Line Enhancer (ALE) is widely used for
enhancing narrowband signals corrupted by broadband noise. In this
paper, we propose novel ALE methods to improve the enhancing
capability. The proposed methods are motivated by the fact that the
output of the ALE is a fine estimate of the desired narrowband signal
with the broadband noise component suppressed. The proposed
methods preprocess the input signal using ALE filter to regenerate a
finer input signal. Thus the proposed ALE is driven by the input signal
with higher signal-to-noise ratio (SNR). The analysis and simulation
results are presented to demonstrate that the proposed ALE has better
performance than conventional ALE’s.
Abstract: One of the most important challenging factors in
medical images is nominated as noise. Image denoising refers to the
improvement of a digital medical image that has been infected by
Additive White Gaussian Noise (AWGN). The digital medical image
or video can be affected by different types of noises. They are
impulse noise, Poisson noise and AWGN. Computed tomography
(CT) images are subjects to low quality due to the noise. Quality of
CT images is dependent on absorbed dose to patients directly in such
a way that increase in absorbed radiation, consequently absorbed
dose to patients (ADP), enhances the CT images quality. In this
manner, noise reduction techniques on purpose of images quality
enhancement exposing no excess radiation to patients is one the
challenging problems for CT images processing. In this work, noise
reduction in CT images was performed using two different
directional 2 dimensional (2D) transformations; i.e., Curvelet and
Contourlet and Discrete Wavelet Transform (DWT) thresholding
methods of BayesShrink and AdaptShrink, compared to each other
and we proposed a new threshold in wavelet domain for not only
noise reduction but also edge retaining, consequently the proposed
method retains the modified coefficients significantly that result good
visual quality. Data evaluations were accomplished by using two
criterions; namely, peak signal to noise ratio (PSNR) and Structure
similarity (Ssim).
Abstract: In this study, failure analysis of pipe system at a micro
hydroelectric power plant is investigated. Failure occurred at the pipe
system in the powerhouse during shut down operation of the water
flow by a valve. This locking had caused a sudden shock wave, also
called “Water-hammer effect”, resulting in noise and inside pressure
increase. After visual investigation of the effect of the shock wave on
the system, a circumference crack was observed at the pipe flange
weld region. To establish the reason for crack formation, calculations
of pressure and stress values at pipe, flange and welding seams were
carried out and concluded that safety factor was high (2.2), indicating
that no faulty design existed. By further analysis, pipe system and
hydroelectric power plant was examined. After observations it is
determined that the plant did not include a ventilation nozzle (air
trap), that prevents the system of sudden pressure increase inside the
pipes which is caused by water-hammer effect. Analyses were carried
out to identify the influence of water-hammer effect on inside
pressure increase and it was concluded that, according Jowkowsky’s
equation, shut down time is effective on inside pressure increase. The
valve closing time was uncertain but by a shut down time of even one
minute, inside pressure would increase by 7.6 bar (working pressure
was 34.6 bar). Detailed investigations were also carried out on the
assembly of the pipe-flange system by considering technical
drawings. It was concluded that the pipe-flange system was not
installed according to the instructions. Two of five weld seams were
not applied and one weld was carried out faulty. This incorrect and
inadequate weld seams resulted in; insufficient connection of the pipe
to the flange constituting a strong notch effect at weld seam regions,
increase in stress values and the decrease of strength and safety
factor.
Abstract: It is an indispensible strategy to adopt greenery
approach on architectural bases so as to improve ecological habitats,
decrease heat-island effect, purify air quality, and relieve surface
runoff as well as noise pollution, all of which are done in an attempt to
achieve sustainable environment. How we can do with plant design to
attain the best visual quality and ideal carbon dioxide fixation depends
on whether or not we can appropriately make use of greenery
according to the nature of architectural bases. To achieve the goal, it is
a need that architects and landscape architects should be provided with
sufficient local references. Current greenery studies focus mainly on
the heat-island effect of urban with large scale. Most of the architects
still rely on people with years of expertise regarding the adoption and
disposition of plantation in connection with microclimate scale.
Therefore, environmental design, which integrates science and
aesthetics, requires fundamental research on landscape environment
technology divided from building environment technology. By doing
so, we can create mutual benefits between green building and the
environment. This issue is extremely important for the greening design
of the bases of green buildings in cities and various open spaces. The
purpose of this study is to establish plant selection and allocation
strategies under different building sunshade levels. Initially, with the
shading of sunshine on the greening bases as the starting point, the
effects of the shades produced by different building types on the
greening strategies were analyzed. Then, by measuring the PAR
(photosynthetic active radiation), the relative DLI (daily light integral)
was calculated, while the DLI Map was established in order to
evaluate the effects of the building shading on the established
environmental greening, thereby serving as a reference for plant
selection and allocation. The discussion results were to be applied in
the evaluation of environment greening of greening buildings and
establish the “right plant, right place” design strategy of multi-level
ecological greening for application in urban design and landscape
design development, as well as the greening criteria to feedback to the
eco-city greening buildings.