R. Sharkawy - Academia.edu (original) (raw)

Papers by R. Sharkawy

Research paper thumbnail of Particle Detection in Oil Using Acoustic and Electrical Based Techniques in Correlation with an Inference Method

2005 IEEE Instrumentationand Measurement Technology Conference Proceedings

Partial discharge (PD) measurement is a proven flaw detection technique for finding defects in th... more Partial discharge (PD) measurement is a proven flaw detection technique for finding defects in the insulating materials and thus accessing the integrity of the tested insulation. The different PD measurement techniques as well as the interpretation of the measurement results have been important research topics in the recent years. This paper contributes to the detection of the presence of free

Research paper thumbnail of Dynamic performance of Dstatcom used for voltage regulation in distribution system

2015 Australasian Universities Power Engineering Conference (AUPEC), 2015

Research paper thumbnail of Acoustic-based particle detection in oil using artificial neural networks

2001 IEEE Porto Power Tech Proceedings (Cat. No.01EX502), 2001

This paper contributes to the detection of the presence of free conducting particles in oil-insul... more This paper contributes to the detection of the presence of free conducting particles in oil-insulated apparatus based on particle-produced acoustics. Acoustic signals are generally produced-under AC-by particle collision against the tank walls. The work uses an inference engine to test for particle contamination in oil by deliberate application of an AC test voltage. The work proposes subjecting the oil-insulated systems

Research paper thumbnail of Evidence that altered motility contributes in host defence in nematode infection

Research paper thumbnail of Hypercontractility of intestinal muscle can be adoptively transferred by Th2 polarized lymphocytes

Research paper thumbnail of Colonic 5-HT and muscle responses to the same infectious agent differ in Th1 and Th2 dominant environments

Research paper thumbnail of The role of CD1d1 in host defense in intestinal nematode infection

Research paper thumbnail of Induction of colonic fibrosis in mice by intramural gene transfer of monocyte chemoattractant protein

Research paper thumbnail of Intramural overexpression of monocyte chemoattractant protein-1 in mouse colon induces fibrosis via T-cell-dependent mechanism

Research paper thumbnail of Critical role of MCP-1 in the pathogenesis of experimental colitis in the context of immune and enterochromaffin cells

American journal of physiology. Gastrointestinal and liver physiology, 2006

Mucosal changes in inflammatory bowel disease (IBD) are characterized by ulcerative lesions accom... more Mucosal changes in inflammatory bowel disease (IBD) are characterized by ulcerative lesions accompanied by a prominent infiltrate of inflammatory cells including lymphocytes, macrophages, and neutrophils and alterations in 5-hydroxytryptamine (5-HT)-producing enterochromaffin (EC) cells. Mechanisms involved in recruiting and activating these cells are thought to involve a complex interplay of inflammatory mediators. Studies in clinical and experimental IBD have shown the upregulation of various chemokines including monocyte chemoattractant protein (MCP)-1 in mucosal tissues. However, precise information on the roles of this chemokine or the mechanisms by which it takes part in the pathogenesis of IBD are not clear. In this study, we investigated the role of MCP-1 in the development of hapten-induced experimental colitis in mice deficient in MCP-1. Our results showed a significant reduction in the severity of colitis both macroscopically and histologically along with a decrease in mo...

Research paper thumbnail of Enhancement of Voltage Security within High Voltage Transmission Systems Utilizing FACTS

International Conference on Software Technology and Engineering, 3rd (ICSTE 2011), 2011

Research paper thumbnail of Synthesis and characterization of Cu(II), Co(II) and Ni(II) complexes of a number of sulfadrug azodyes and their application for wastewater treatment

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014

The azodye ligand (HL(1)) was synthesized from the coupling of sulfaguanidine diazonium salt with... more The azodye ligand (HL(1)) was synthesized from the coupling of sulfaguanidine diazonium salt with 2,4-dihydroxy-benzaldehyde while the two ligands, HL(2) and HL(3), were prepared by the coupling of sulfadiazine diazonium salt with salicylaldehyde (HL(2)) and 2,4-dihydroxy-benzaldehyde (HL(3)). The prepared ligands were characterized by elemental analysis, IR, (1)H NMR and mass spectra. Cu(II), Co(II) and Ni(II) complexes of the prepared ligands have been synthesized and characterized by various spectroscopic techniques like IR, UV-Visible as well as magnetic and thermal (TG and DTA) measurements. It was found that all the ligands behave as a monobasic bidentate which coordinated to the metal center through the azo nitrogen and α-hydroxy oxygen atoms in the case of HL(1) and HL(3). HL(2) coordinated to the metal center through sulfonamide oxygen and pyrimidine nitrogen. The applications of the prepared complexes in the oxidative degradation of indigo carmine dye exhibited good catalytic activity in the presence of H2O2 as an oxidant. The reactions followed first-order kinetics and the rate constants were determined. The degradation reaction involved the catalytic action of the azo-dye complexes toward H2O2 decomposition, which can lead to the generation of HO radicals as a highly efficient oxidant attacking the target dye. The detailed kinetic studies and the mechanism of these catalytic reactions are under consideration in our group.

Research paper thumbnail of On the measurements of the dielectric constant and dissipation factor of various elastomers

2012 IEEE International Power Modulator and High Voltage Conference (IPMHVC), 2012

Research paper thumbnail of Novel alpha-transform distance relaying scheme

Proceedings of 1996 Canadian Conference on Electrical and Computer Engineering, 1996

This paper presents a simple novel distance relaying scheme based on the 3-cl alpha (a)-hyperplan... more This paper presents a simple novel distance relaying scheme based on the 3-cl alpha (a)-hyperplane of (Va-I,-Pa)

Research paper thumbnail of A novel measurement technique for extra high voltage bus bar fault detection

2012 11th International Conference on Environment and Electrical Engineering, 2012

This paper introduces a new fault detection tool for Extra High Voltage (EHV) busbars. The new to... more This paper introduces a new fault detection tool for Extra High Voltage (EHV) busbars. The new tool is to be used by extra high speed digital relays to detect busbar faults besides differentiating between close up line faults and busbar ones. The suggested tool uses a new technique that squares both of the instantaneous voltage signal and its complement to

Research paper thumbnail of Ac and DC flashover voltages of polyvinyl chloride insulating material

International Conference on Electrical, Electronic and Computer Engineering, 2004. ICEEC '04., 2004

This article presents the results of a study done to evaluate the ac (50Hz) and dc flashover volt... more This article presents the results of a study done to evaluate the ac (50Hz) and dc flashover voltages of polyvinyl chloride insulating material. The ac and dc voltages have been measured for different sets of samples at different temperatures. Also, the effect of inorganic filler such as; Alumina trihydrate with various concentrations on the constitution of polyvinyl chloride material has

Research paper thumbnail of An investigation into the electrical properties of rubber blends for insulators

2007 Electrical Insulation Conference and Electrical Manufacturing Expo, 2007

This paper focuses on testing silicone rubber (SiR) and ethylene-propylene-diene monomer (EPDM) b... more This paper focuses on testing silicone rubber (SiR) and ethylene-propylene-diene monomer (EPDM) blends which are applied as outdoor high voltage insulating materials. The study undertakes an investigation of the properties of aged specimens of SiR, EPDM and a blend of SiR/EPDM materials by exposure to ultra-violet radiation. Microscopic surface observations are demonstrated to inspect surface degradation after aging for blends

Research paper thumbnail of Analysis of the dynamic behavior of a DFIG during grid disturbances using active crowbar protection

ABSTRACT Nowadays, wind power has been developed very fast in the world and the installed capacit... more ABSTRACT Nowadays, wind power has been developed very fast in the world and the installed capacity of wind turbine has been increased rapidly. Doubly Fed Induction Generator (DFIG) has been applied very popularly for its many advantages. When the grid voltage dip occurs, a crowbar beside the Rotor Side Converter (RSC) is usually activated. In this paper the effect of the active crowbar resistance are studied and analysed. The active crowbar is control to limit the rotor current and dc-link voltage. Simulation results based on MATLAB/SIMULINK are discussed.

Research paper thumbnail of High impedance fault detection on radial distribution and utilization systems

Proceedings of 1996 Canadian Conference on Electrical and Computer Engineering, 1996

The paper presents a simple relaying detection scheme for high impedance faults (HIF) in radial u... more The paper presents a simple relaying detection scheme for high impedance faults (HIF) in radial utilization and distribution feeders. The scheme is based on the concept of quasistatic ripple harmonics, sub and super harmonic frequencies usually associated with low level currents during arcing faults due to high impedance type (HIF) faults.

Research paper thumbnail of Partial Discharge Pattern Classification Using the Fuzzy Decision Tree Approach

IEEE Transactions on Instrumentation and Measurement, 2005

Partial discharge (PD) measurement is a proven flaw detection technique for finding cavities that... more Partial discharge (PD) measurement is a proven flaw detection technique for finding cavities that are defects in the insulating material. In this paper, a novel approach for the classification of cavity sizes, based on their maximum PD charge transfer-applied voltage (1Q-V) characteristics using a fuzzy decision tree system, is proposed. The (1Q-V) partial discharge patterns for different cavity sizes are represented by features extracted from their pulse shapes, and the classification rules are directly extracted from the data using the decision tree. The decision rules obtained from the decision tree are then converted to the fuzzy IF-then rules, and the back-propagation algorithm is utilized to tune the parameters of the membership functions employed in the fuzzy classifier. The neuro-fuzzy classification technique is shown to provide successful classification of void sizes in an easily interpretive fashion.

Research paper thumbnail of Particle Detection in Oil Using Acoustic and Electrical Based Techniques in Correlation with an Inference Method

2005 IEEE Instrumentationand Measurement Technology Conference Proceedings

Partial discharge (PD) measurement is a proven flaw detection technique for finding defects in th... more Partial discharge (PD) measurement is a proven flaw detection technique for finding defects in the insulating materials and thus accessing the integrity of the tested insulation. The different PD measurement techniques as well as the interpretation of the measurement results have been important research topics in the recent years. This paper contributes to the detection of the presence of free

Research paper thumbnail of Dynamic performance of Dstatcom used for voltage regulation in distribution system

2015 Australasian Universities Power Engineering Conference (AUPEC), 2015

Research paper thumbnail of Acoustic-based particle detection in oil using artificial neural networks

2001 IEEE Porto Power Tech Proceedings (Cat. No.01EX502), 2001

This paper contributes to the detection of the presence of free conducting particles in oil-insul... more This paper contributes to the detection of the presence of free conducting particles in oil-insulated apparatus based on particle-produced acoustics. Acoustic signals are generally produced-under AC-by particle collision against the tank walls. The work uses an inference engine to test for particle contamination in oil by deliberate application of an AC test voltage. The work proposes subjecting the oil-insulated systems

Research paper thumbnail of Evidence that altered motility contributes in host defence in nematode infection

Research paper thumbnail of Hypercontractility of intestinal muscle can be adoptively transferred by Th2 polarized lymphocytes

Research paper thumbnail of Colonic 5-HT and muscle responses to the same infectious agent differ in Th1 and Th2 dominant environments

Research paper thumbnail of The role of CD1d1 in host defense in intestinal nematode infection

Research paper thumbnail of Induction of colonic fibrosis in mice by intramural gene transfer of monocyte chemoattractant protein

Research paper thumbnail of Intramural overexpression of monocyte chemoattractant protein-1 in mouse colon induces fibrosis via T-cell-dependent mechanism

Research paper thumbnail of Critical role of MCP-1 in the pathogenesis of experimental colitis in the context of immune and enterochromaffin cells

American journal of physiology. Gastrointestinal and liver physiology, 2006

Mucosal changes in inflammatory bowel disease (IBD) are characterized by ulcerative lesions accom... more Mucosal changes in inflammatory bowel disease (IBD) are characterized by ulcerative lesions accompanied by a prominent infiltrate of inflammatory cells including lymphocytes, macrophages, and neutrophils and alterations in 5-hydroxytryptamine (5-HT)-producing enterochromaffin (EC) cells. Mechanisms involved in recruiting and activating these cells are thought to involve a complex interplay of inflammatory mediators. Studies in clinical and experimental IBD have shown the upregulation of various chemokines including monocyte chemoattractant protein (MCP)-1 in mucosal tissues. However, precise information on the roles of this chemokine or the mechanisms by which it takes part in the pathogenesis of IBD are not clear. In this study, we investigated the role of MCP-1 in the development of hapten-induced experimental colitis in mice deficient in MCP-1. Our results showed a significant reduction in the severity of colitis both macroscopically and histologically along with a decrease in mo...

Research paper thumbnail of Enhancement of Voltage Security within High Voltage Transmission Systems Utilizing FACTS

International Conference on Software Technology and Engineering, 3rd (ICSTE 2011), 2011

Research paper thumbnail of Synthesis and characterization of Cu(II), Co(II) and Ni(II) complexes of a number of sulfadrug azodyes and their application for wastewater treatment

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014

The azodye ligand (HL(1)) was synthesized from the coupling of sulfaguanidine diazonium salt with... more The azodye ligand (HL(1)) was synthesized from the coupling of sulfaguanidine diazonium salt with 2,4-dihydroxy-benzaldehyde while the two ligands, HL(2) and HL(3), were prepared by the coupling of sulfadiazine diazonium salt with salicylaldehyde (HL(2)) and 2,4-dihydroxy-benzaldehyde (HL(3)). The prepared ligands were characterized by elemental analysis, IR, (1)H NMR and mass spectra. Cu(II), Co(II) and Ni(II) complexes of the prepared ligands have been synthesized and characterized by various spectroscopic techniques like IR, UV-Visible as well as magnetic and thermal (TG and DTA) measurements. It was found that all the ligands behave as a monobasic bidentate which coordinated to the metal center through the azo nitrogen and α-hydroxy oxygen atoms in the case of HL(1) and HL(3). HL(2) coordinated to the metal center through sulfonamide oxygen and pyrimidine nitrogen. The applications of the prepared complexes in the oxidative degradation of indigo carmine dye exhibited good catalytic activity in the presence of H2O2 as an oxidant. The reactions followed first-order kinetics and the rate constants were determined. The degradation reaction involved the catalytic action of the azo-dye complexes toward H2O2 decomposition, which can lead to the generation of HO radicals as a highly efficient oxidant attacking the target dye. The detailed kinetic studies and the mechanism of these catalytic reactions are under consideration in our group.

Research paper thumbnail of On the measurements of the dielectric constant and dissipation factor of various elastomers

2012 IEEE International Power Modulator and High Voltage Conference (IPMHVC), 2012

Research paper thumbnail of Novel alpha-transform distance relaying scheme

Proceedings of 1996 Canadian Conference on Electrical and Computer Engineering, 1996

This paper presents a simple novel distance relaying scheme based on the 3-cl alpha (a)-hyperplan... more This paper presents a simple novel distance relaying scheme based on the 3-cl alpha (a)-hyperplane of (Va-I,-Pa)

Research paper thumbnail of A novel measurement technique for extra high voltage bus bar fault detection

2012 11th International Conference on Environment and Electrical Engineering, 2012

This paper introduces a new fault detection tool for Extra High Voltage (EHV) busbars. The new to... more This paper introduces a new fault detection tool for Extra High Voltage (EHV) busbars. The new tool is to be used by extra high speed digital relays to detect busbar faults besides differentiating between close up line faults and busbar ones. The suggested tool uses a new technique that squares both of the instantaneous voltage signal and its complement to

Research paper thumbnail of Ac and DC flashover voltages of polyvinyl chloride insulating material

International Conference on Electrical, Electronic and Computer Engineering, 2004. ICEEC '04., 2004

This article presents the results of a study done to evaluate the ac (50Hz) and dc flashover volt... more This article presents the results of a study done to evaluate the ac (50Hz) and dc flashover voltages of polyvinyl chloride insulating material. The ac and dc voltages have been measured for different sets of samples at different temperatures. Also, the effect of inorganic filler such as; Alumina trihydrate with various concentrations on the constitution of polyvinyl chloride material has

Research paper thumbnail of An investigation into the electrical properties of rubber blends for insulators

2007 Electrical Insulation Conference and Electrical Manufacturing Expo, 2007

This paper focuses on testing silicone rubber (SiR) and ethylene-propylene-diene monomer (EPDM) b... more This paper focuses on testing silicone rubber (SiR) and ethylene-propylene-diene monomer (EPDM) blends which are applied as outdoor high voltage insulating materials. The study undertakes an investigation of the properties of aged specimens of SiR, EPDM and a blend of SiR/EPDM materials by exposure to ultra-violet radiation. Microscopic surface observations are demonstrated to inspect surface degradation after aging for blends

Research paper thumbnail of Analysis of the dynamic behavior of a DFIG during grid disturbances using active crowbar protection

ABSTRACT Nowadays, wind power has been developed very fast in the world and the installed capacit... more ABSTRACT Nowadays, wind power has been developed very fast in the world and the installed capacity of wind turbine has been increased rapidly. Doubly Fed Induction Generator (DFIG) has been applied very popularly for its many advantages. When the grid voltage dip occurs, a crowbar beside the Rotor Side Converter (RSC) is usually activated. In this paper the effect of the active crowbar resistance are studied and analysed. The active crowbar is control to limit the rotor current and dc-link voltage. Simulation results based on MATLAB/SIMULINK are discussed.

Research paper thumbnail of High impedance fault detection on radial distribution and utilization systems

Proceedings of 1996 Canadian Conference on Electrical and Computer Engineering, 1996

The paper presents a simple relaying detection scheme for high impedance faults (HIF) in radial u... more The paper presents a simple relaying detection scheme for high impedance faults (HIF) in radial utilization and distribution feeders. The scheme is based on the concept of quasistatic ripple harmonics, sub and super harmonic frequencies usually associated with low level currents during arcing faults due to high impedance type (HIF) faults.

Research paper thumbnail of Partial Discharge Pattern Classification Using the Fuzzy Decision Tree Approach

IEEE Transactions on Instrumentation and Measurement, 2005

Partial discharge (PD) measurement is a proven flaw detection technique for finding cavities that... more Partial discharge (PD) measurement is a proven flaw detection technique for finding cavities that are defects in the insulating material. In this paper, a novel approach for the classification of cavity sizes, based on their maximum PD charge transfer-applied voltage (1Q-V) characteristics using a fuzzy decision tree system, is proposed. The (1Q-V) partial discharge patterns for different cavity sizes are represented by features extracted from their pulse shapes, and the classification rules are directly extracted from the data using the decision tree. The decision rules obtained from the decision tree are then converted to the fuzzy IF-then rules, and the back-propagation algorithm is utilized to tune the parameters of the membership functions employed in the fuzzy classifier. The neuro-fuzzy classification technique is shown to provide successful classification of void sizes in an easily interpretive fashion.