Abstract: A novel application of neural network approach to
fault classification and fault location of Medium voltage cables is
demonstrated in this paper. Different faults on a protected cable
should be classified and located correctly. This paper presents the use
of neural networks as a pattern classifier algorithm to perform these
tasks. The proposed scheme is insensitive to variation of different
parameters such as fault type, fault resistance, and fault inception
angle. Studies show that the proposed technique is able to offer high
accuracy in both of the fault classification and fault location tasks.
Abstract: This paper proposes the use of metrics in design space exploration that highlight where in the structure of the model and at what point in the behaviour, prevention is needed against transient faults. Previous approaches to tackle transient faults focused on recovery after detection. Almost no research has been directed towards preventive measures. But in real-time systems, hard deadlines are performance requirements that absolutely must be met and a missed deadline constitutes an erroneous action and a possible system failure. This paper proposes the use of metrics to assess the system design to flag where transient faults may have significant impact. These tools then allow the design to be changed to minimize that impact, and they also flag where particular design techniques – such as coding of communications or memories – need to be applied in later stages of design.
Abstract: Dissolved gas analysis has been accepted as a sensitive, informative and reliable technique for incipient faults detection in power transformers and is widely used. In the last few years this method, which has been recommended by IEEE Power & Energy society, has been applied for fault detection in load tap changers. Regarding the critical role of load tap changers in electrical network and essential of catastrophic failures prevention, it is necessary to choose "condition based preventative maintenance strategy" which leads to reduction in costs, the number of unnecessary visits as well as the probability of interruptions and also increment in equipment reliability. In current work, considering the condition based preventative maintenance strategy, condition assessment of an Elin tap changer was carried out using dissolved gas analysis.
Abstract: In wireless and mobile communications, this progress
provides opportunities for introducing new standards and improving
existing services. Supporting multimedia traffic with wireless networks
quality of service (QoS). In this paper, a grey-fuzzy controller for radio
resource management (GF-RRM) is presented to maximize the number
of the served calls and QoS provision in wireless networks. In a
wireless network, the call arrival rate, the call duration and the
communication overhead between the base stations and the control
center are vague and uncertain. In this paper, we develop a method to
predict the cell load and to solve the RRM problem based on the
GF-RRM, and support the present facility has been built on the
application-level of the wireless networks. The GF-RRM exhibits the
better adaptability, fault-tolerant capability and performance than other
algorithms. Through simulations, we evaluate the blocking rate, update
overhead, and channel acquisition delay time of the proposed method.
The results demonstrate our algorithm has the lower blocking rate, less
updated overhead, and shorter channel acquisition delay.
Abstract: The development of wireless communication technologies has changed our living style in global level. After the international success of mobile telephony standards, the location and time independent voice connection has become a default method in daily telecommunications. As for today, highly advanced multimedia messaging plays a key role in value added service handling. Along with evolving data services, the need for more complex applications can be seen, including the mobile usage of broadcast technologies. Here performance of a system design for terrestrial multimedia content is examined with emphasis on mobile reception. This review paper has accommodated the understanding of physical layer role and the flavour of terrestrial channel effects on the terrestrial multimedia transmission using OFDM keeping DVB-H as benchmark standard.
Abstract: A serious problem on the WWW is finding reliable
information. Not everything found on the Web is true and the
Semantic Web does not change that in any way. The problem will be
even more crucial for the Semantic Web, where agents will be
integrating and using information from multiple sources. Thus, if an
incorrect premise is used due to a single faulty source, then any
conclusions drawn may be in error. Thus, statements published on
the Semantic Web have to be seen as claims rather than as facts, and
there should be a way to decide which among many possibly
inconsistent sources is most reliable. In this work, we propose a trust
model for the Semantic Web. The proposed model is inspired by the
use trust in human society. Trust is a type of social knowledge and
encodes evaluations about which agents can be taken as reliable
sources of information or services. Our proposed model allows
agents to decide which among different sources of information to
trust and thus act rationally on the semantic web.
Abstract: The structural interpretation of a part of eastern Potwar
(Missa Keswal) has been carried out with available seismological,
seismic and well data. Seismological data contains both the source
parameters and fault plane solution (FPS) parameters and seismic data
contains ten seismic lines that were re-interpreted by using well data.
Structural interpretation depicts two broad types of fault sets namely,
thrust and back thrust faults. These faults together give rise to pop up
structures in the study area and also responsible for many structural
traps and seismicity. Seismic interpretation includes time and depth
contour maps of Chorgali Formation while seismological interpretation
includes focal mechanism solution (FMS), depth, frequency,
magnitude bar graphs and renewal of Seismotectonic map. The Focal
Mechanism Solutions (FMS) that surrounds the study area are
correlated with the different geological and structural maps of the area
for the determination of the nature of subsurface faults. Results of
structural interpretation from both seismic and seismological data
show good correlation. It is hoped that the present work will help in
better understanding of the variations in the subsurface structure and
can be a useful tool for earthquake prediction, planning of oil field and
reservoir monitoring.
Abstract: Power system stabilizers (PSS) are now routinely used in the industry to damp out power system oscillations. In this paper, real-coded genetic algorithm (RCGA) optimization technique is applied to design robust power system stabilizer for both singlemachine infinite-bus (SMIB) and multi-machine power system. The design problem of the proposed controller is formulated as an optimization problem and RCGA 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.
Abstract: Occurrence of a multiple-points fault in machine operations could result in exhibiting complex fault signatures, which could result in lowering fault diagnosis accuracy. In this study, a multiple-points defect model (MPDM) is proposed which can simulate fault signature-s dynamics for n-points bearing faults. Furthermore, this study identifies that in case of multiple-points fault in the rotary machine, the location of the dominant component of defect frequency shifts depending upon the relative location of the fault points which could mislead the fault diagnostic model to inaccurate detections. Analytical and experimental results are presented to characterize and validate the variation in the dominant component of defect frequency. Based on envelop detection analysis, a modification is recommended in the existing fault diagnostic models to consider the multiples of defect frequency rather than only considering the frequency spectrum at the defect frequency in order to incorporate the impact of multiple points fault.
Abstract: Power transformers are among the most important and
expensive equipments in the electric power systems. Consequently
the transformer protection is an essential part of the system
protection. This paper presents a new method for locating
transformer winding faults such as turn-to-turn, turn-to-core, turn-totransformer
body, turn-to-earth, and high voltage winding to low
voltage winding. In this study the current and voltage signals of input
and output terminals of the transformer are measured, which the
Fourier transform of measured signals and harmonic analysis
determine the fault's location.
Abstract: This paper presents the development of a wavelet
based algorithm, for distinguishing between magnetizing inrush
currents and power system fault currents, which is quite adequate,
reliable, fast and computationally efficient tool. The proposed
technique consists of a preprocessing unit based on discrete wavelet
transform (DWT) in combination with an artificial neural network
(ANN) for detecting and classifying fault currents. The DWT acts as
an extractor of distinctive features in the input signals at the relay
location. This information is then fed into an ANN for classifying
fault and magnetizing inrush conditions. A 220/55/55 V, 50Hz
laboratory transformer connected to a 380 V power system were
simulated using ATP-EMTP. The DWT was implemented by using
Matlab and Coiflet mother wavelet was used to analyze primary
currents and generate training data. The simulated results presented
clearly show that the proposed technique can accurately discriminate
between magnetizing inrush and fault currents in transformer
protection.
Abstract: In this paper a new fast simplification method is
presented. Such method realizes Karnough map with large
number of variables. In order to accelerate the operation of the
proposed method, a new approach for fast detection of group
of ones is presented. Such approach implemented in the
frequency domain. The search operation relies on performing
cross correlation in the frequency domain rather than time one.
It is proved mathematically and practically that the number of
computation steps required for the presented method is less
than that needed by conventional cross correlation. Simulation
results using MATLAB confirm the theoretical computations.
Furthermore, a powerful solution for realization of complex
functions is given. The simplified functions are implemented
by using a new desigen for neural networks. Neural networks
are used because they are fault tolerance and as a result they
can recognize signals even with noise or distortion. This is
very useful for logic functions used in data and computer
communications. Moreover, the implemented functions are
realized with minimum amount of components. This is done
by using modular neural nets (MNNs) that divide the input
space into several homogenous regions. Such approach is
applied to implement XOR function, 16 logic functions on one
bit level, and 2-bit digital multiplier. Compared to previous
non- modular designs, a clear reduction in the order of
computations and hardware requirements is achieved.
Abstract: It has been defined that the “network is the system".
This implies providing levels of service, reliability, predictability and
availability that are commensurate with or better than those that
individual computers provide today. To provide this requires
integrated network management for interconnected networks of
heterogeneous devices covering both the local campus. In this paper
we are addressing a framework to effectively deal with this issue. It
consists of components and interactions between them which are
required to perform the service fault management. A real-world
scenario is used to derive the requirements which have been applied
to the component identification. An analysis of existing frameworks
and approaches with respect to their applicability to the framework is
also carried out.
Abstract: Springback is a significant problem in the sheet metal
forming process. When the tools are released after the stage of
forming, the product springs out, because of the action of the internal
stresses. In many cases the deviation of form is too large and the
compensation of the springback is necessary. The precise prediction
of the springback of product is increasingly significant for the design
of the tools and for compensation because of the higher ratio of the
yield stress to the elastic modulus.
The main object in this paper was to study the effect of the
anisotropy on the springback for three directions of rolling: 0°, 45°
and 90°. At the same time, we highlighted the influence of three
different metallic materials: Aluminum, Steel and Galvanized steel.
The original of our purpose consist on tests which are ensured by
adapting a U-type stretching-bending device on a tensile testing
machine, where we studied and quantified the variation of the
springback according to the direction of rolling. We also showed the
role of lubrication in the reduction of the springback.
Moreover, in this work, we have studied important characteristics
in deep drawing process which is a springback. We have presented
defaults that are showed in this process and many parameters
influenced a springback.
Finally, our results works lead us to understand the influence of
grains orientation with different metallic materials on the springback
and drawing some conclusions how to concept deep drawing tools. In
addition, the conducted work represents a fundamental contribution
in the discussion the industry application.
Abstract: This paper deals with the effect of a power transformer’s vector group on the basic voltage sag characteristics during unbalanced faults at a meshed or radial power network. Specifically, the propagation of voltage sags through a power transformer is studied with advanced short-circuit analysis. A smart method to incorporate this effect on analytical mathematical expressions is proposed. Based on this methodology, the positive effect of transformers of certain vector groups on the mitigation of the expected number of voltage sags per year (sag frequency) at the terminals of critical industrial customers can be estimated.
Abstract: The objective of this study is to propose a statistical
modeling method which enables simultaneous term structure
estimation of the risk-free interest rate, hazard and loss given default,
incorporating the characteristics of the bond issuing company such as
credit rating and financial information. A reduced form model is used
for this purpose. Statistical techniques such as spline estimation and
Bayesian information criterion are employed for parameter estimation
and model selection. An empirical analysis is conducted using the
information on the Japanese bond market data. Results of the
empirical analysis confirm the usefulness of the proposed method.
Abstract: This paper presents a wavelet transform and Support
Vector Machine (SVM) based algorithm for estimating fault location
on transmission lines. The Discrete wavelet transform (DWT) is used
for data pre-processing and this data are used for training and testing
SVM. Five types of mother wavelet are used for signal processing to
identify a suitable wavelet family that is more appropriate for use in
estimating fault location. The results demonstrated the ability of SVM
to generalize the situation from the provided patterns and to
accurately estimate the location of faults with varying fault resistance.
Abstract: In this paper, Wavelet based ANFIS for finding inter
turn fault of generator is proposed. The detector uniquely responds to
the winding inter turn fault with remarkably high sensitivity.
Discrimination of different percentage of winding affected by inter
turn fault is provided via ANFIS having an Eight dimensional input
vector. This input vector is obtained from features extracted from
DWT of inter turn faulty current leaving the generator phase
winding. Training data for ANFIS are generated via a simulation of
generator with inter turn fault using MATLAB. The proposed
algorithm using ANFIS is giving satisfied performance than ANN
with selected statistical data of decomposed levels of faulty current.
Abstract: Interpolated contour maps drawn for aluminum,
copper and molybdenum in downstream monitoring boreholes of
water dam in Miduk Copper Complex and the values of pH, redox
potential (Eh) and distance from water dam indicate different trends
of variation and behavior of these three elements in downward
groundwater resources. As these maps exhibit, aluminum is dominant
in the most alkaline (pH = 9-11) borehole (MB5) to water dam. The
highest concentration of molybdenum is found in the nearest
borehole (MB6) to water dam. Main concentration of copper is
observed in the most oxidized borehole (MB3 with Eh=293.2mV).
The spatial difference among sampling stations can be attributed to
the existence of faults and diaclases in the geologic structure of
Miduk region which causes the groundwater sampling sites to be
impressed by different contamination sources (toe seepage and upper
seepage water originated from different zones of tailings dump).
Abstract: The very nonlinear nature of the generator and system
behaviour following a severe disturbance precludes the use of
classical linear control technique. In this paper, a new approach of
nonlinear control is proposed for transient and steady state stability
analysis of a synchronous generator. The control law of the generator
excitation is derived from the basis of Lyapunov stability criterion.
The overall stability of the system is shown using Lyapunov
technique. The application of the proposed controller to simulated
generator excitation control under a large sudden fault and wide
range of operating conditions demonstrates that the new control
strategy is superior to conventional automatic voltage regulator
(AVR), and show very promising results.