Engineering, Technology & Applied Science Research

Engineering, Technology & Applied Science Research

Basic info

  • Publisher: Engineering, Technology & Applied Science Research
  • Country of publisher: greece
  • Date added to EuroPub: 2017/Jul/24

Subject and more

  • LCC Subject Category: Technological Change, Information Science, Industrial Management, Engineering, Civil Engineering
  • Publisher's keywords: Engineering, Technology, Science Applications
  • Language of fulltext: english

Publication charges

  • Article Processing Charges (APCs): Yes 200 EUR
  • Submission charges: No
  • Waiver policy for charges? No

Editorial information

Open access & licensing

  • Type of License: CC BY
  • License terms
  • Open Access Statement: Yes
  • Year open access content began: 2011
  • Does the author retain unrestricted copyright? True
  • Does the author retain publishing rights? True

Best practice polices

  • Permanent article identifier: None
  • Content digitally archived in: , Other
  • Deposit policy registered in: Sherpa/Romeo

This journal has '621' articles

Pollution Maintenance Techniques in Coastal High Voltage Installations

Pollution Maintenance Techniques in Coastal High Voltage Installations

Authors: K. Siderakis, D. Pylarinos, E. Thalassinakis, I. Vitellas, E. Pyrgioti
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Abstract

Pollution of outdoor high voltage insulators is a common problem for utilities, with a considerable impact to power system reliability. In an effort to prevent possible flashovers due to pollution, many methods have been applied, aiming to improve the insulation performance, either by suppressing the formation of surface conductivity or by increasing the possible insulation level. In the case of substations, the selection of the appropriate technique is complex due to certain issues correlated to the nature of the installation. In this paper, several techniques usually implemented by utilities, are investigated based on the experienced gained in the case of Crete, a Greek island in southern Europe, where due to the coastal development of the power system, the majority of high voltage installations are exposed to intense marine pollution. The technique of coating insulators with Room Temperature Vulcanized Silicone Rubber (RTV SIR) has proved rather efficient and therefore is presented extendedly. Correlation of the material behaviour with environmental conditions is discussed and results from long term monitoring, including environmental parameters and leakage current measurements, in a 150 kV Substation are presented. It is shown that RTV SIR coatings have remarkably suppressed surface activity and that porcelain insulators exhibit different activity period when coated.

Keywords: pollution; RTV SIR; GIS; substation; insulator; leakage current
Automating the Classification of Field Leakage Current Waveforms

Automating the Classification of Field Leakage Current Waveforms

Authors: D. Pylarinos, K. Siderakis, E. Pyrgioti, E. Thalassinakis, I. Vitellas
( 0 downloads)
Abstract

Leakage current monitoring is widely employed to investigate the performance of high voltage insulators and the development of surface activity. Field measurements offer an exact view of experienced activity and insulators’ performance, which are strongly correlated to local conditions. The required long term monitoring however, results to the accumulation of vast amounts of data. Therefore, an identification system for the classification of field leakage current waveforms rises as a necessity. In this paper, a number of 500 leakage current waveforms recorded on a composite post insulator installed at a 150 kV High Voltage Substation suffering from intense marine pollution, are investigated. The insulator was monitored for a period of 13 months. An identification system is designed based on the considered data employing Fourier analysis, wavelet multiresolution analysis and a neural network. Results show the large impact of noise in field measurements and the effectiveness of the discussed system on the considered data set.

Keywords: insulator; leakage current; neural network; wavelet; pattern recognition; STD_MRA; field
Growth mode study of MgCl2 on Au foil and Si (111) 7x7, under Ultra High Vacuum by XPS

Growth mode study of MgCl2 on Au foil and Si (111) 7x7, under Ultra High Vacuum by XPS

Authors: S. Karakalos
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Abstract

The growth mode of MgCl2 on Au foil and Si (111) 7x7 reconstructed surface under UHV conditions, was investigated by X-ray Photoelectron Spectroscopy (XPS). Magnesium chloride grows with the Frank-van der Merve, (FM) growth mode on the Au foil. On Si surface there is evidence for the layer by layer growth of MgCl2 but leaving uncovered silicon areas at the first steps of deposition due to the Si (111)7x7 surface roughness.

Keywords: growth mode; MgCl2; Au foil; Si(111)7x7; UHV; XPS
Exprerimental Evaluation of a Dedicated Pinhole SPECT System for Small Animal Imaging and Scintimammography

Exprerimental Evaluation of a Dedicated Pinhole SPECT System for Small Animal Imaging and Scintimammography

Authors: S. David, M. Georgiou, E. Fysikopoulos, G. Loudos
( 0 downloads)
Abstract

Nuclear medicine (SPECT and PET) provides functional information, which is complementary to the structural. In cancer imaging radiopharmaceuticals allow visualization of cancer cells functionality, thus small cell population can be imaged. This allows early diagnosis, as well as fast assessment of response to therapy. Our system is a single head gamma camera based on an R3292 position sensitive photomultiplier tube (PSPMT), coupled to a 10cm in diameter CsI:Tl crystal. We have assessed two CsI:Tl crystals with pixel size of 2x2mm2 and 3x3mm2 respectively. Three collimators were tested: a) a hexagonal, 1.1mm in diameter, general purpose parallel hole collimator b) a 1mm pinhole and c) a 2mm pinhole. Systems were tested using capillary phantoms. All measurements were carried out in photon counting mode with gamma radiation produced by 99mTc. Using the 2x2mm2 crystal and the 1mm pinhole collimator - a resolution better than 1mm was achieved. This allows very detailed imaging of small animals. Using the 3x3mm2 and the 2mm pinhole collimator a resolution of 1.3mm was possible with suitable sensitivity for breast imaging. Those results indicate that this system is suitable for animal and breast studies. The next step will be clinical evaluation of the camera.

Keywords: dedicated gamma camera; PSPMT; small animal imaging; scintimammography; pinhole
A Novel Structure for Vector Control of Symmetrical Six-Phase Induction Machines with Three Current Sensors

A Novel Structure for Vector Control of Symmetrical Six-Phase Induction Machines with Three Current Sensors

Authors: H. P. Nabi, P. Dadashi, A. Shoulaie
( 0 downloads)
Abstract

Vector control is one of the most popular multiphase induction machine drive methods due to its dynamic performance. Since all phase currents are needed in vector control drive, by increasing phase numbers, the number of required current sensors increases which is one of the disadvantages of vector control in multiphase machine drives. In this paper vector control of a symmetrical six-phase induction machine with a novel configuration is presented. The aforementioned configuration is designed in a simple way that only three current sensors will be needed. Analytical equations are extracted in this paper to show that some of current components which do not contribute in torque production will be eliminated due to the proposed scheme. Simulation and experimental results are provided to verify the benefits of the proposed configuration.

Keywords: symmetrical six-phase induction machine; vector control; current sensor; multiphase drives
Mobile Phone Brand Categorization vs. Users' Security Practices

Mobile Phone Brand Categorization vs. Users' Security Practices

Authors: I. Androulidakis, G. Kandus
( 0 downloads)
Abstract

In the present paper, we correlated the brand of mobile phone to users’ security practices, statistically processing a large pool of the responses of 7172 students in 17 Universities of 10 Eastern and Southern Europe countries. Users show different behavior in an array of characteristics, according to the brand of the mobile phone they are using. As such, there is a categorization of areas, different for each brand, where users are clearly lacking security mind, possibly due to lack of awareness. Such a categorization can help phone manufacturers enhance their mobile phones in regards to security, preferably transparently for the user.

Keywords: mobile phone security; brand profiling, security practices; survey
A Custom-made MATLAB Based Software to Manage Leakage Current Waveforms

A Custom-made MATLAB Based Software to Manage Leakage Current Waveforms

Authors: D. Pylarinos
( 0 downloads)
Abstract

Leakage current (LC) monitoring is a widely employed tool for monitoring the performance of high voltage insulators. LC waveform monitoring is required to acquire a view of the phenomena experienced since the type of LC waveform’s shape is correlated with different types of electrical activity. In case of field monitoring, specially designed measuring systems, capable of operating under field conditions, have to be installed. The Greek Public Power Corporation (PPC) has issued a large project for monitoring the performance of outdoor insulators. A commercially available LC measuring system, was purchased and installed by PPC. The system was able to monitor various outdoor insulators, record several statistical values and intermittently record a LC waveform. The provided software lacked some capabilities that were required for certain research areas and a custom made software had to be developed. In this paper, two stand-alone MATLAB based softwares, “Leakage Current Waveform File Converter” and “Leakage Current Waveform Viewer”, both equipped with a user friendly GUI, are presented. The first software was developed in order to automatically convert multiple files from the CSV format (as extracted from the measuring system) to the MAT format in order to allow data compactness and further processing. The latter software was developed in order to offer a tool for collective viewing, printing and extraction to JPEG format, of LC waveforms in groups of user-defined numbers. The latter function gives the opportunity for easy and fast creation of waveform archives.

Keywords: leakage current; waveform; data; software; GUI; matlab
Model and Reduction of Inactive Times in a Maintenance Workshop Following a Diagnostic Error

Model and Reduction of Inactive Times in a Maintenance Workshop Following a Diagnostic Error

Authors: L. Meva'a, R. Danwe, T. Beda
( 0 downloads)
Abstract

The majority of maintenance workshops in manufacturing factories are hierarchical. This arrangement permits quick response in advent of a breakdown. Reaction of the maintenance workshop is done by evaluating the characteristics of the breakdown. In effect, a diagnostic error at a given level of the process of decision making delays the restoration of normal operating state. The consequences are not just financial loses, but loss in customers’ satisfaction as well. The goal of this paper is to model the inactive time of a maintenance workshop in case that an unpredicted catalectic breakdown has occurred and a diagnostic error has also occurred at a certain level of decision-making, during the treatment process of the breakdown. We show that the expression for the inactive times obtained, is depended only on the characteristics of the workshop. Next, we propose a method to reduce the inactive times.

Keywords: hierachical system; catalectic breakdown; diagnostic error; model; inactive time
Optimum Scheme for Insulation System in HV Generator Based on Electromagnetic Analysis

Optimum Scheme for Insulation System in HV Generator Based on Electromagnetic Analysis

Authors: D. Azizi, A. Gholami
( 0 downloads)
Abstract

Electrical insulations are one of the basic parts of electrical machinery in any sizes and characteristics. Focusing on insulating, studies on the operation of industrial-electrical machinery came to the fact that the most important part of a machine is the Stator. This fact reveals the requirement for inspection of the electrical machine insulation along with the electromagnetic tensions. Therefore with respect to insulation system improvement of stator, the HV generator can be optimized. Dielectric parameters such as insulation thickness, spacing, material types, geometry of winding and slot are major design consideration. A very powerful method available to analyze electromagnetic performance is Finite Element Method (FEM) which is used in this paper. The analysis of various stator coil and slot configurations are used to design the better dielectric system to reduce electrical stresses in order to increase the power of generator in the same volume of core. These processes of optimization have been done according the proposed algorithm. In this algorithm the technical constraints have been considered. This paper describes the process used to perform classical design and improvement analysis of stator slot’s insulation with respect to objective function and constraints.

Keywords: insulation; FEM; machine; magnetic; thermal
Simulation and RTDS Hardware Implementation of SHAF for Mitigation of Current Harmonics with p-q and Id-Iq Control Strategies Using PI Controller

Simulation and RTDS Hardware Implementation of SHAF for Mitigation of Current Harmonics with p-q and Id-Iq Control Strategies Using PI Controller

Authors: S. Mikkili, A. K. Panda
( 0 downloads)
Abstract

Control strategies for extracting the three-phase reference currents for shunt active power filters are compared, evaluating their performance under different source conditions in MATLAB/Simulink environment and also with Real Time Digital Simulator (RTDS) Hardware. When the supply voltages are balanced and sinusoidal, the two control strategies are converging to the same compensation characteristics but when the supply voltages are distorted and/or un-balanced sinusoidal, these control strategies result in different degrees of compensation in harmonics. The p-q control strategy is unable to yield an adequate solution when source voltages are not ideal. Extensive Simulations are carried out with PI controller for both p-q and Id-Iq control strategies for different voltage conditions and adequate results were presented. The 3-ph 4-wire SHAF system is also implemented on RTDS Hardware to further verify its effectiveness. The detailed simulation and RTDS Hardware results are included.

Keywords: harmonic compensation; SHAF; p-q control strategy; Id-Iq control strategy; PI controller; RTDS hardware
Investigation of Leakage Current Waveforms Recorded in a Coastal High Voltage Substation

Investigation of Leakage Current Waveforms Recorded in a Coastal High Voltage Substation

Authors: D. Pylarinos, K. Siderakis, E. Pyrgioti, E. Thalassinakis, I. Vitellas
( 0 downloads)
Abstract

Leakage current monitoring is a widely employed technique to monitor the performance of outdoor insulation. The evaluation of leakage current waveforms recorded in the field, offers significant information since insulation’s performance is strongly linked with local conditions, and the waveforms’ shape correlate to different types of surface activity. In this paper, an investigation of leakage current waveforms recorded in a 150 kV coastal Substations suffering which suffers intense marine pollution is presented. Investigation of the recorded waveforms verified the basic waveform shapes described in the literature. Further, several variations of the basic types and complex waveforms, as well as field related waveforms, are presented. The need for added categorization criteria in the case of field measurements is discussed.

Keywords: field; insulator; leakage current; noise; waveform; monitoring; pollution
Effect of Adaptation Gain in Model Reference Adaptive Controlled Second Order System

Effect of Adaptation Gain in Model Reference Adaptive Controlled Second Order System

Authors: P. Swarnkar, S. Jain, R. K. Nema
( 0 downloads)
Abstract

Adaptive control involves modifying the control law used by the controller to cope with the fact that the parameters of the system being controlled change drastically due to change in environmental conditions or in system itself. This technique is based on the fundamental characteristic of adaptation of living organism. The adaptive control process is one that continuously and automatically measures the dynamic behavior of plant, compares it with the desired output and uses the difference to vary adjustable system parameters or to generate an actuating signal in such a way so that optimal performance can be maintained regardless of system changes. Nature of adaptation mechanism for controlling the system performance is greatly affected by the value of adaptation gain. It is observed that for the lower order system wide range of adaptation gain can be used to study the performance of the system. As the order of the system increases the applicable range of adaptation gain becomes narrow. This paper deals with application of model reference adaptive control scheme to second order system with different values of adaptation gain. The rule which is used for this application is MIT rule. Simulation is done in MATLAB and simulink and the results are compared for varying adaptation mechanism due to variation in adaptation gain.

Keywords: model reference; adaptive control; MIT rule; adaptation; mechanism; gain
Comparative Assessment of Gate Drive Control Schemes in High Frequency Converter

Comparative Assessment of Gate Drive Control Schemes in High Frequency Converter

Authors: N. Z. Yahaya, K. M. Begam, M. Awan
( 0 downloads)
Abstract

Several gate drive control schemes are simulated and the results show that the Fixed Duty ratio (FDR) can help drive synchronous rectifier buck converter (SRBC) correctly with low dead time and hence reduce body diode conduction loss. Even though FDR is prone to cross-conduction effects, the design is simple. Apart from that, Adaptive Gate Delay (AGD) and Predictive Gate Delay (PGD) control schemes have also shown high level of efficiency. However, AGD generates more losses. Even though the total switching loss in PGD has not improved much of only 1 %, more than 82 % efficiency has been achieved in spite of the advantage in FDR and AGD schemes.

Keywords: gate drive control; high frequency; PSpice simulation; synchronous rectifier buck converter
Application of using Hybrid Renewable Energy in Saudi Arabia

Application of using Hybrid Renewable Energy in Saudi Arabia

Authors: E. A. Al-Ammar, N. H. Malik, M. Usman
( 0 downloads)
Abstract

One of the major world wide concerns of the utilities is to reduce the emissions from traditional power plants by using renewable energy and to reduce the high cost of supplying electricity to remote areas. Hybrid power systems can provide a good solution for such problems because they integrate renewable energy along with the traditional power plants. In Kingdom of Saudi Arabia a remote village called Al-Qtqt, was selected as a case study in order to investigate the ability to use a hybrid power system to provide the village with its needs of electricity. The simulation of this hybrid power system was done using HOMER software.

Keywords: hybrid; renewable energy; HOMER; photovoltaic; wind energy
Prograph Based Analysis of Single Source Shortest Path Problem with Few Distinct Positive Lengths

Prograph Based Analysis of Single Source Shortest Path Problem with Few Distinct Positive Lengths

Authors: B. Bhowmik, S. Nag Chowdhury
( 0 downloads)
Abstract

In this paper we propose an experimental study model S3P2 of a fast fully dynamic programming algorithm design technique in finite directed graphs with few distinct nonnegative real edge weights. The Bellman-Ford’s approach for shortest path problems has come out in various implementations. In this paper the approach once again is re-investigated with adjacency matrix selection in associate least running time. The model tests proposed algorithm against arbitrarily but positive valued weighted digraphs introducing notion of Prograph that speeds up finding the shortest path over previous implementations. Our experiments have established abstract results with the intention that the proposed algorithm can consistently dominate other existing algorithms for Single Source Shortest Path Problems. A comparison study is also shown among Dijkstra’s algorithm, Bellman-Ford algorithm, and our algorithm.

Keywords: shortest path; negative weight cycle; weight matrix; variants; program-graph; SPL; dense network; scanned vertices; relaxation

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