Abstract: The present study aims to evaluating the effect of
rotor solidity - in terms of chord length for a given rotor diameter - on
the performances of a small vertical axis Darrieus wind turbine. The
proposed work focuses on both power production and rotor power
coefficient, considering also the structural constraints deriving from
the centrifugal forces due to rotor angular velocity. Also the
smoothness of the resulting power curves have been investigated, in
order to evaluate the controllability of the corresponding rotor
architectures.
Abstract: Microbial oil was produced by soil isolated
oleaginous yeast YU5/2 in flask-batch fermentation. The yeast was
identified by molecular genetics technique based on sequence
analysis of the variable D1/D2 domain of the large subunit (26S)
ribosomal DNA and it was identified as Torulaspora globosa. T.
globosa YU5/2 supported maximum values of 0.520 g/L/d, 0.472 g
lipid/g cells, 4.16 g/L, and 0.156 g/L/d for volumetric lipid
production rate, and specific yield of lipid, lipid concentration, and
specific rate of lipid production respectively, when culture was
performed in nitrogen-limiting medium supplemented with 80g/L
glucose. Among the carbon sources tested, maximum cell yield
coefficient (YX/S, g/L), maximum specific yield of lipid (YP/X, g
lipid/g cells) and volumetric lipid production rate (QP, g/L/d) were
found of 0.728, 0.237, and 0.619, respectively, using sweet potato
tubers hydrolysates as carbon source.
Abstract: Power system stabilizers (PSS) are now routinely used in the industry to damp out power system oscillations. In this paper, particle swarm optimization (PSO) technique is applied to design a robust power system stabilizer (PSS). The design problem of the proposed controller is formulated as an optimization problem and PSO is employed to search for optimal controller parameters. By minimizing the time-domain based objective function, in which the deviation in the oscillatory rotor speed of the generator is involved; stability performance of the system is improved. The non-linear simulation results are presented under wide range of operating conditions; disturbances at different locations as well as for various fault clearing sequences to show the effectiveness and robustness of the proposed controller and their ability to provide efficient damping of low frequency oscillations. Further, all the simulations results are compared with a conventionally designed power system stabilizer to show the superiority of the proposed design approach.
Abstract: The scattering effect of light in fog improves the
difficulty in visibility thus introducing disturbances in transport
facilities in urban or industrial areas causing fatal accidents or public
harassments, therefore, developing an enhanced fog vision system
with radio wave to improvise the way outs of these severe problems
is really a big challenge for researchers. Series of experimental
studies already been done and more are in progress to know the
weather effect on radio frequencies for different ranges. According to
Rayleigh scattering Law, the propagating wavelength should be
greater than the diameter of the particle present in the penetrating
medium. Direct wave RF signal thus have high chance of failure to
work in such weather for detection of any object. Therefore an
extensive study was required to find suitable region in the RF band
that can help us in detecting objects with proper shape. This paper
produces some results on object detection using 912 MHz band with
successful detection of the persistence of any object coming under the
trajectory of a vehicle navigating in indoor and outdoor environment.
The developed images are finally transformed to video signal to
enable continuous monitoring.
Abstract: Fuzzy random variables have been introduced as an imprecise concept of numeric values for characterizing the imprecise knowledge. The descriptive parameters can be used to describe the primary features of a set of fuzzy random observations. In fuzzy environments, the expected values are usually represented as fuzzy-valued, interval-valued or numeric-valued descriptive parameters using various metrics. Instead of the concept of area metric that is usually adopted in the relevant studies, the numeric expected value is proposed by the concept of distance metric in this study based on two characters (fuzziness and randomness) of FRVs. Comparing with the existing measures, although the results show that the proposed numeric expected value is same with those using the different metric, if only triangular membership functions are used. However, the proposed approach has the advantages of intuitiveness and computational efficiency, when the membership functions are not triangular types. An example with three datasets is provided for verifying the proposed approach.
Abstract: Improving the performance of the QCL through block diagram as well as mathematical models is the main scope of this paper. In order to enhance the performance of the underlined device, the mathematical model parameters are used in a reliable manner in such a way that the optimum behavior was achieved. These parameters play the central role in specifying the optical characteristics of the considered laser source. Moreover, it is important to have a large amount of radiated power, where increasing the amount of radiated power represents the main hopping process that can be predicted from the behavior of quantum laser devices. It was found that there is a good agreement between the calculated values from our mathematical model and those obtained with VisSim and experimental results. These demonstrate the strength of mplementation of both mathematical and block diagram models.
Abstract: FW4 is a newly developed hot die material widely
used in Forging Dies manufacturing. The right selection of the
machining conditions is one of the most important aspects to take
into consideration in the Electrical Discharge Machining (EDM) of
FW4. In this paper an attempt has been made to develop
mathematical models for relating the Material Removal Rate (MRR),
Tool Wear Ratio (TWR) and surface roughness (Ra) to machining
parameters (current, pulse-on time and voltage). Furthermore, a study
was carried out to analyze the effects of machining parameters in
respect of listed technological characteristics. The results of analysis
of variance (ANOVA) indicate that the proposed mathematical
models, can adequately describe the performance within the limits of
the factors being studied.
Abstract: The Institute of Product Development is dealing
with the development, design and dimensioning of micro components
and systems as a member of the Collaborative Research
Centre 499 “Design, Production and Quality Assurance of
Molded micro components made of Metallic and Ceramic Materials".
Because of technological restrictions in the miniaturization
of conventional manufacturing techniques, shape and
material deviations cannot be scaled down in the same proportion
as the micro parts, rendering components with relatively
wide tolerance fields. Systems that include such components
should be designed with this particularity in mind, often requiring
large clearance. On the end, the output of such systems
results variable and prone to dynamical instability. To save
production time and resources, every study of these effects
should happen early in the product development process and
base on computer simulation to avoid costly prototypes. A
suitable method is proposed here and exemplary applied to a
micro technology demonstrator developed by the CRC499. It
consists of a one stage planetary gear train in a sun-planet-ring
configuration, with input through the sun gear and output
through the carrier. The simulation procedure relies on ordinary
Multi Body Simulation methods and subsequently adds
other techniques to further investigate details of the system-s
behavior and to predict its response. The selection of the relevant
parameters and output functions followed the engineering
standards for regular sized gear trains. The first step is to
quantify the variability and to reveal the most critical points of
the system, performed through a whole-mechanism Sensitivity
Analysis. Due to the lack of previous knowledge about the system-s
behavior, different DOE methods involving small and
large amount of experiments were selected to perform the SA.
In this particular case the parameter space can be divided into
two well defined groups, one of them containing the gear-s profile
information and the other the components- spatial location.
This has been exploited to explore the different DOE techniques
more promptly. A reduced set of parameters is derived for
further investigation and to feed the final optimization process,
whether as optimization parameters or as external perturbation
collective. The 10 most relevant perturbation factors and 4 to 6
prospective variable parameters are considered in a new, simplified
model. All of the parameters are affected by the mentioned
production variability. The objective functions of interest
are based on scalar output-s variability measures, so the
problem becomes an optimization under robustness and reliability constrains. The study shows an initial step on the development
path of a method to design and optimize complex micro
mechanisms composed of wide tolerated elements accounting
for the robustness and reliability of the systems- output.
Abstract: The purpose of this work was to study the effect of the
irrigation using waste water with various electric conductivities (T(0,92ds/m), EC3 (3ds/m) and EC6 (6ds/m) on three varieties of
quinoa cultivated in a field south of Morocco. The follow up of the evolution of the chemical and agronomic parameters throughout the
culture made it possible to determine the responses to the saline stress in arid conditions. Results showed that the salinity caused the
depression of plant-s height, and reduced the fresh and dry weight in
the different parts of the three varieties plants. The increase of the irrigation water EC didn-t affect the yield for the varieties. Thus,
quinoa resisted to salinity and proved a behavior of a facultative halophyte crop. In fact, the cultivation of this using treated wastewater is feasible especially in arid areas for a sustainable use of
water resources.
Abstract: In this paper a new concept of partial complement of a graph G is introduced and using the same a new graph parameter, called completion number of a graph G, denoted by c(G) is defined. Some basic properties of graph parameter, completion number, are studied and upperbounds for completion number of classes of graphs are obtained , the paper includes the characterization also.
Abstract: The objective of this research was to study influence
parameters affecting to mechanical property of austenitic stainless
steel grade 304 (AISI 304) with Gas Metal Arc Welding (GMAW).
The research was applying factorial design experiment, which have
following interested parameters: welding current at 80, 90, and 100
Amps, welding speeds at 250, 300, and 350 mm/min, and shield gas
of 75% Ar + 25% CO2, 70% Ar + 25% CO2 + 5% O2 and 69.5% Ar +
25% CO2 + 5% O2 + 0.5% He gas. The study was done in following
aspects: ultimate tensile strength and elongation. A research study of
ultimate tensile strength found that main factor effect, which had the
highest strength to AISI 304 welding was shield gas of 70% Ar +
25% CO2 + 5% O2 at average of 954.81 N/mm2. Result of the highest
elongation was showed significantly different at interaction effect
between shield gas of 69.5%Ar+25%CO2+5%O2+.5%He and
welding speed at 250 mm/min at 47.94%.
Abstract: Due to some reasons, observed images are degraded which are mainly caused by noise. Recently image denoising using the wavelet transform has been attracting much attention. Waveletbased approach provides a particularly useful method for image denoising when the preservation of edges in the scene is of importance because the local adaptivity is based explicitly on the values of the wavelet detail coefficients. In this paper, we propose several methods of noise removal from degraded images with Gaussian noise by using adaptive wavelet threshold (Bayes Shrink, Modified Bayes Shrink and Normal Shrink). The proposed thresholds are simple and adaptive to each subband because the parameters required for estimating the threshold depend on subband data. Experimental results show that the proposed thresholds remove noise significantly and preserve the edges in the scene.
Abstract: Two cultivars ('Rutuliai', 'Saint Perrie') and five
hybrids ('Tolstoi', 'Brooklyn', 'Tocayo', 'Benito', 'Tourist') of edible
tomato (Lycopersicon esculentum Mill.) were investigated at the
LRCAF Institute of Horticulture. The following fruit quality
parameters were evaluated: the amount of lycopene, β-carotene,
ascorbic acid, total and inverted sugar, sucrose, dry matter soluble
solids in fresh tomato matter, also were determined fruit skin and
flesh firmness, color indexes (CIE L*a*b*) and calculated hue angle
(h°) with chroma (C).
Abstract: This paper proposes the analysis and design of robust
fuzzy control to Stochastic Parametrics Uncertaint Linear systems.
This system type to be controlled is partitioned into several linear
sub-models, in terms of transfer function, forming a convex polytope,
similar to LPV (Linear Parameters Varying) system. Once defined the
linear sub-models of the plant, these are organized into fuzzy Takagi-
Sugeno (TS) structure. From the Parallel Distributed Compensation
(PDC) strategy, a mathematical formulation is defined in the frequency
domain, based on the gain and phase margins specifications,
to obtain robust PI sub-controllers in accordance to the Takagi-
Sugeno fuzzy model of the plant. The main results of the paper are
based on the robust stability conditions with the proposal of one
Axiom and two Theorems.
Abstract: Revolutions Applications such as telecommunications, hands-free communications, recording, etc. which need at least one microphone, the signal is usually infected by noise and echo. The important application is the speech enhancement, which is done to remove suppressed noises and echoes taken by a microphone, beside preferred speech. Accordingly, the microphone signal has to be cleaned using digital signal processing DSP tools before it is played out, transmitted, or stored. Engineers have so far tried different approaches to improving the speech by get back the desired speech signal from the noisy observations. Especially Mobile communication, so in this paper will do reconstruction of the speech signal, observed in additive background noise, using the Kalman filter technique to estimate the parameters of the Autoregressive Process (AR) in the state space model and the output speech signal obtained by the MATLAB. The accurate estimation by Kalman filter on speech would enhance and reduce the noise then compare and discuss the results between actual values and estimated values which produce the reconstructed signals.
Abstract: In this paper, we present a vertical wire NMOS
device fabricated using CMOS compatible processes. The
impact of temperature on various device parameters is
investigated in view of usual increase in surrounding
temperature with device density.
Abstract: The paper presents the results of microhardness and
microstructure of low carbon steel surface melted using carbon
dioxide laser with a wavelength of 10.6μm and a maximum output
power of 2000W. The processing parameters such as the laser power,
and the scanning rate were investigated in this study. After surface
melting two distinct regions formed corresponding to the melted zone
MZ, and the heat affected zone HAZ. The laser melted region
displayed a cellular fine structures while the HAZ displayed
martensite or bainite structure. At different processing parameters,
the original microstructure of this steel (Ferrite+Pearlite) has been
transformed to new phases of martensitic and bainitic structures. The
fine structure and the high microhardness are evidence of the high
cooling rates which follow the laser melting. The melting pool and
the transformed microstructure in the laser surface melted region of
carbon steel showed clear dependence on laser power and scanning
rate.
Abstract: Modeling and vibration of a flexible link manipulator
with tow flexible links and rigid joints are investigated which can
include an arbitrary number of flexible links. Hamilton principle and
finite element approach is proposed to model the dynamics of
flexible manipulators. The links are assumed to be deflection due to
bending. The association between elastic displacements of links is
investigated, took into account the coupling effects of elastic motion
and rigid motion. Flexible links are treated as Euler-Bernoulli beams
and the shear deformation is thus abandoned. The dynamic behavior
due to flexibility of links is well demonstrated through numerical
simulation. The rigid-body motion and elastic deformations are
separated by linearizing the equations of motion around the rigid
body reference path. Simulation results are shown on for both
position and force trajectory tracking tasks in the presence of varying
parameters and unknown dynamics remarkably well. The proposed
method can be used in both dynamic simulation and controller
design.
Abstract: Drop-in of R-22 alternatives in refrigeration and air conditioning systems requires a redesign of system components to improve system performance and reliability with the alternative refrigerants. The present paper aims at design adiabatic capillary tubes for R-22 alternatives such as R-417A, R-422D and R-438A. A theoretical model has been developed and validated with the available experimental data from literature for R-22 over a wide range of both operating and geometrical parameters. Predicted lengths of adiabatic capillary tube are compared with the lengths of the capillary tube needed under similar experimental conditions and majority of predictions are found to be within 4.4% of the experimental data. Hence, the model has been applied for R-417A, R- 422D and R-438A and capillary tube selection charts and correlations have been computed. Finally a comparison between the selected refrigerants and R-22 has been introduced and the results showed that R-438A is the closest one to R-22.
Abstract: To increase precision and reliability of automatic control systems, we have to take into account of random factors affecting the control system. Thus, operational matrix technique is used for statistical analysis of first order plus time delay system with uniform random parameter. Examples with deterministic and stochastic disturbance are considered to demonstrate the validity of the method. Comparison with Monte Carlo method is made to show the computational effectiveness of the method.