Abstract: The coefficient diagram method is primarily an algebraic control design method whose objective is to easily obtain
a good controller with minimum user effort. As a matter of fact, if a
system model, in the form of linear differential equations, is known,
the user only need to define a time-constant and the controller order.
The later can be established regarding the expected disturbance type
via a lookup table first published by Koksal and Hamamci in 2004.
However an inaccuracy in this table was detected and pointed-out in
the present work. Moreover the above mentioned table was expanded
in order to enclose any k order type disturbance.
Abstract: Qatar’s primary source of fresh water is through
seawater desalination. Amongst the major processes that are
commercially available on the market, the most common large scale
techniques are Multi-Stage Flash distillation (MSF), Multi Effect
distillation (MED), and Reverse Osmosis (RO). Although commonly
used, these three processes are highly expensive down to high energy
input requirements and high operating costs allied with maintenance
and stress induced on the systems in harsh alkaline media. Beside that
cost, environmental footprint of these desalination techniques are
significant; from damaging marine eco-system, to huge land use, to
discharge of tons of GHG and huge carbon footprint.
Other less energy consuming techniques based on membrane
separation are being sought to reduce both the carbon footprint and
operating costs is membrane distillation (MD).
Emerged in 1960s, MD is an alternative technology for water
desalination attracting more attention since 1980s. MD process
involves the evaporation of a hot feed, typically below boiling point
of brine at standard conditions, by creating a water vapor pressure
difference across the porous, hydrophobic membrane. Main
advantages of MD compared to other commercially available
technologies (MSF and MED) and specially RO are reduction of
membrane and module stress due to absence of trans-membrane
pressure, less impact of contaminant fouling on distillate due to
transfer of only water vapor, utilization of low grade or waste heat
from oil and gas industries to heat up the feed up to required
temperature difference across the membrane, superior water quality,
and relatively lower capital and operating cost.
To achieve the objective of this study, state of the art flat-sheet
cross-flow DCMD bench scale unit was designed, commissioned, and
tested. The objective of this study is to analyze the characteristics and
morphology of the membrane suitable for DCMD through SEM
imaging and contact angle measurement and to study the water
quality of distillate produced by DCMD bench scale unit.
Comparison with available literature data is undertaken where
appropriate and laboratory data is used to compare a DCMD distillate
quality with that of other desalination techniques and standards.
Membrane SEM analysis showed that the PTFE membrane used
for the study has contact angle of 127º with highly porous surface
supported with less porous and bigger pore size PP membrane. Study
on the effect of feed solution (salinity) and temperature on water
quality of distillate produced from ICP and IC analysis showed that
with any salinity and different feed temperature (up to 70ºC) the
electric conductivity of distillate is less than 5 μS/cm with 99.99%
salt rejection and proved to be feasible and effective process capable
of consistently producing high quality distillate from very high feed
salinity solution (i.e. 100000 mg/L TDS) even with substantial
quality difference compared to other desalination methods such as
RO and MSF.
Abstract: The primary objective of this paper is to elimination of the problem of sensitivity to parameter variation of induction motor drive. The proposed sensorless strategy is based on an algorithm permitting a better simultaneous estimation of the rotor speed and the stator resistance including an adaptive mechanism based on the lyaponov theory. To study the reliability and the robustness of the sensorless technique to abnormal operations, some simulation tests have been performed under several cases.
The proposed sensorless vector control scheme showed a good performance behavior in the transient and steady states, with an excellent disturbance rejection of the load torque.
Abstract: This paper realized the 2-DOF controller structure for first order with time delay systems. The co-prime factorization is used to design observer based controller K(s), representing one degree of freedom. The problem is based on H∞ norm of mixed sensitivity and aims to achieve stability, robustness and disturbance rejection. Then, the other degree of freedom, prefilter F(s), is formulated as fixed structure polynomial controller to meet open loop processing of reference model. This model matching problem is solved by minimizing integral square error between reference model and proposed model. The feedback controller and prefilter designs are posed as optimization problem and solved using Particle Swarm Optimization (PSO). To show the efficiency of the designed approach different variety of processes are taken and compared for analysis.
Abstract: Reconfigurable antennas represent a recent innovation in antenna design that changes from classical fixed-form, fixed function antennas to modifiable structures that can be adapted to fit the requirements of a time varying system.
The ability to control the operating band of an antenna system can have many useful applications. Systems that operate in an acquire-and-track configuration would see a benefit from active bandwidth control. In such systems a wide band search mode is first employed to find a desired signal then a narrow band track mode is used to follow only that signal. Utilizing active antenna bandwidth control, a single antenna would function for both the wide band and narrow band configurations providing the rejection of unwanted signals with the antenna hardware. This ability to move a portion of the RF filtering out of the receiver and onto the antenna itself will also aid in reducing the complexity of the often expensive RF processing subsystems.
Abstract: In all his novels, Hawthorne, the American writer, created settings in which his moral concerns could be presented through the actions of his characters. He illustrated his concern over the moral fall of man in the nineteenth century obsession for technological advancement. In “The Blithedale Romance” and “The House of Seven Gable” quite vividly, he pictured individualistic moral vices as the result of outside forces which caused social immorality. “The Marble Faun”, in its own turn, has the same type of social moral concerns to present: the story of nineteenth century modern man and his individualistic moral issues which lead to his social moral fall. He depicted the dominant themes of individualistic moral vices which all lead to social alienation and rejection. He showed hypocrisy and evil intentions as leading to social immoral atmosphere.
Abstract: This paper proposes a study of input impedance of 2 types of CMOS active inductors. It derives 2 input impedance formulas. The first formula is the input impedance of the grounded active inductor. The second formula is the input impedance of the floating active inductor. After that, these formulas can be used to simulate magnitude and phase response of input impedance as a function of current consumption with MATLAB. Common mode rejection ratio (CMRR) of the fully differential bandpass amplifier is derived based on superposition principle. CMRR as a function of input frequency is plotted as a function of current consumption.
Abstract: This study presents a new method for detecting the
cutting tool wear based on the measured cutting force signals using
the regression model and I-kaz method. The detection of tool wear
was done automatically using the in-house developed regression
model and 3D graphic presentation of I-kaz 3D coefficient during
machining process. The machining tests were carried out on a CNC
turning machine Colchester Master Tornado T4 in dry cutting
condition, and Kistler 9255B dynamometer was used to measure the
cutting force signals, which then stored and displayed in the DasyLab
software. The progression of the cutting tool flank wear land (VB)
was indicated by the amount of the cutting force generated. Later, the
I-kaz was used to analyze all the cutting force signals from beginning
of the cut until the rejection stage of the cutting tool. Results of the IKaz
analysis were represented by various characteristic of I-kaz 3D
coefficient and 3D graphic presentation. The I-kaz 3D coefficient
number decreases when the tool wear increases. This method can be
used for real time tool wear monitoring.
Abstract: Provision of optical devices without proper instruction
and training may cause frustration resulting in rejection or incorrect
use of the magnifiers. However training in the use of magnifiers
increases the cost of providing these devices. This study compared
the efficacy of providing instruction alone and instruction plus
training in the use of magnifiers. 24 participants randomly assigned
to two groups. 15 received instruction and training and 9 received
instruction only. Repeated measures of print size and reading speed
were performed at pre, post training and follow up. Print size
decreased in both groups between pre and post training maintained at
follow up. Reading speed increased in both groups over time with the
training group demonstrating more rapid improvement. Whilst
overall outcomes were similar, training decreased the time required
to increase reading speed supporting the use of training for increased
efficiency. A cost effective form of training is suggested.
Abstract: An effective approach for extracting document images from a noisy background is introduced. The entire scheme is divided into three sub- stechniques – the initial preprocessing operations for noise cluster tightening, introduction of a new thresholding method by maximizing the ratio of stan- dard deviations of the combined effect on the image to the sum of weighted classes and finally the image restoration phase by image binarization utiliz- ing the proposed optimum threshold level. The proposed method is found to be efficient compared to the existing schemes in terms of computational complexity as well as speed with better noise rejection.
Abstract: The research on two-wheels balancing robot has
gained momentum due to their functionality and reliability when
completing certain tasks. This paper presents investigations into the
performance comparison of Linear Quadratic Regulator (LQR) and
PID-PID controllers for a highly nonlinear 2–wheels balancing robot.
The mathematical model of 2-wheels balancing robot that is highly
nonlinear is derived. The final model is then represented in statespace
form and the system suffers from mismatched condition. Two
system responses namely the robot position and robot angular
position are obtained. The performances of the LQR and PID-PID
controllers are examined in terms of input tracking and disturbances
rejection capability. Simulation results of the responses of the
nonlinear 2–wheels balancing robot are presented in time domain. A
comparative assessment of both control schemes to the system
performance is presented and discussed.
Abstract: A new approach is adopted in this paper based
on Turk and Pentland-s eigenface method. It was found that the
probability density function of the distance between the projection
vector of the input face image and the average projection vector of
the subject in the face database, follows Rayleigh distribution. In
order to decrease the false acceptance rate and increase the
recognition rate, the input face image has been recognized using two
thresholds including the acceptance threshold and the rejection
threshold. We also find out that the value of two thresholds will be
close to each other as number of trials increases. During the training,
in order to reduce the number of trials, the projection vectors for each
subject has been averaged. The recognition experiments using the
proposed algorithm show that the recognition rate achieves to
92.875% whilst the average number of judgment is only 2.56 times.
Abstract: In this paper, three types of defected ground structure
(DGS) units which are triangular-head (TH), rectangular-head (RH)
and U-shape (US) are investigated. They are further used to low-pass
and band-pass filters designs (LPF and BPF) and the obtained
performances are examined. The LPF employing RH-DGS geometry
presents the advantages of compact size, low-insertion loss and wide
stopband compared to the other filters. It provides cutoff frequency of
2.5 GHz, largest rejection band width of 20 dB from 2.98 to 8.76
GHz, smallest transition region and smallest sharpness of the cutoff
frequency. The BPF based on RH-DGS has the highest bandwidth
(BW) of about 0.74 GHz and the lowest center frequency of 3.24
GHz, whereas the other BPFs have BWs less than 0.7 GHz.
Abstract: In non destructive testing by radiography, a perfect
knowledge of the weld defect shape is an essential step to
appreciate the quality of the weld and make decision on its
acceptability or rejection. Because of the complex nature of the
considered images, and in order that the detected defect region
represents the most accurately possible the real defect, the choice
of thresholding methods must be done judiciously. In this paper,
performance criteria are used to conduct a comparative study of
four non parametric histogram thresholding methods for automatic
extraction of weld defect in radiographic images.
Abstract: This paper focuses on systematic analysis and
controller design of the two-inertia STABILIZATION system,
considering the angular motion on a base body. This approach is
essential to the stabilization system to aim at a target under three or six
degrees of freedom base motion. Four controllers, such as
conventional PDF(Pseudo-Derivative Feedback) controller with
motor speed feedback, PDF controller with load speed feedback,
modified PDF controller with motor-load speed feedback and
feedforward controller added to modified PDF controller, are
suggested to improve reference tracking and disturbance rejection
performance. Characteristics and performance of each controller are
analyzed and validated by simulation in the case of the modified PDF
controller with and without a feedforward controller.
Abstract: This paper treats a discrete-time finite buffer batch arrival queue with a single working vacation and partial batch rejection in which the inter-arrival and service times are, respectively, arbitrary and geometrically distributed. The queue is analyzed by using the supplementary variable and the imbedded Markov-chain techniques. We obtain steady-state system length distributions at prearrival, arbitrary and outside observer-s observation epochs. We also present probability generation function (p.g.f.) of actual waiting-time distribution in the system and some performance measures.
Abstract: In this paper we are interested in classification problems
with a performance constraint on error probability. In such
problems if the constraint cannot be satisfied, then a rejection option
is introduced. For binary labelled classification, a number of SVM
based methods with rejection option have been proposed over the
past few years. All of these methods use two thresholds on the SVM
output. However, in previous works, we have shown on synthetic data
that using thresholds on the output of the optimal SVM may lead to
poor results for classification tasks with performance constraint. In
this paper a new method for supervised classification with rejection
option is proposed. It consists in two different classifiers jointly
optimized to minimize the rejection probability subject to a given
constraint on error rate. This method uses a new kernel based linear
learning machine that we have recently presented. This learning
machine is characterized by its simplicity and high training speed
which makes the simultaneous optimization of the two classifiers
computationally reasonable. The proposed classification method with
rejection option is compared to a SVM based rejection method
proposed in recent literature. Experiments show the superiority of
the proposed method.
Abstract: An effort has been taken to simulate the combustion
and performance characteristics of biodiesel fuel in direct injection
(D.I) low heat rejection (LHR) diesel engine. Comprehensive
analyses on combustion characteristics such as cylinder pressure,
peak cylinder pressure, heat release and performance characteristics
such as specific fuel consumption and brake thermal efficiency are
carried out. Compression ignition (C.I) engine cycle simulation was
developed and modified in to LHR engine for both diesel and
biodiesel fuel. On the basis of first law of thermodynamics the
properties at each degree crank angle was calculated. Preparation and
reaction rate model was used to calculate the instantaneous heat
release rate. A gas-wall heat transfer calculations are based on the
ANNAND-s combined heat transfer model with instantaneous wall
temperature to analyze the effect of coating on heat transfer. The
simulated results are validated by conducting the experiments on the
test engine under identical operating condition on a turbocharged D.I
diesel engine. In this analysis 20% of biodiesel (derived from
Jatropha oil) blended with diesel and used in both conventional and
LHR engine. The simulated combustion and performance
characteristics results are found satisfactory with the experimental
value.
Abstract: The frontal area in the brain is known to be involved in
behavioral judgement. Because a Kanji character can be discriminated
visually and linguistically from other characters, in Kanji character
discrimination, we hypothesized that frontal event-related potential
(ERP) waveforms reflect two discrimination processes in separate
time periods: one based on visual analysis and the other based
on lexcical access. To examine this hypothesis, we recorded ERPs
while performing a Kanji lexical decision task. In this task, either a
known Kanji character, an unknown Kanji character or a symbol was
presented and the subject had to report if the presented character was
a known Kanji character for the subject or not. The same response
was required for unknown Kanji trials and symbol trials. As a preprocessing
of signals, we examined the performance of a method
using independent component analysis for artifact rejection and found
it was effective. Therefore we used it. In the ERP results, there
were two time periods in which the frontal ERP wavefoms were
significantly different betweeen the unknown Kanji trials and the
symbol trials: around 170ms and around 300ms after stimulus onset.
This result supported our hypothesis. In addition, the result suggests
that Kanji character lexical access may be fully completed by around
260ms after stimulus onset.
Abstract: This paper deals with the synthesis of fuzzy state feedback controller of induction motor with optimal performance. First, the Takagi-Sugeno (T-S) fuzzy model is employed to approximate a non linear system in the synchronous d-q frame rotating with electromagnetic field-oriented. Next, a fuzzy controller is designed to stabilise the induction motor and guaranteed a minimum disturbance attenuation level for the closed-loop system. The gains of fuzzy control are obtained by solving a set of Linear Matrix Inequality (LMI). Finally, simulation results are given to demonstrate the controller-s effectiveness.