Energy and Environment are two important issues in this decade. Using the clean energy such as s... more Energy and Environment are two important issues in this decade. Using the clean energy such as solar energy generation is growing around word, but with low efficiency. Many parameters from the environment affect the solar photovoltaic panel such as shadow, air pollution and dust. In some experimental setup, there is a small layer that accumulates on top of the photovoltaic (PV). In order to evaluate the effect of dust on Photovoltaic, using two Fix Flat Photovoltaic (FFP) was installed at the Universiti Putra Malaysia. One array is the ‘’Clean array’’ that was cleaned regularly and other is the “Dusty array” that was not cleaned during this research. Data was collected at interval each of 30mins from 1st April to 5th December 2013 for both arrays. Power output and Energy yield for both PV arrays are considered. Findings from this research shows that overly power and energy decrease due to the dust, which accumulates on the surface. The contribution this work with other research was done is we are evaluate the power loss in tropical climate which force with many rainy days
Solar energy, which comes from the sun in the form of solar irradiance, can be directly converte... more Solar energy, which comes from the sun in the form of solar irradiance, can be directly converted to electricity by using photovoltaic (PV) technology. However, the properties related to the nature of semiconductors used in solar cells, has limited the efficiency of PV systems to 1520 %. Thus, in order to increase the efficiency of PV systems, some improvements such as applying sun trackers and maximum power point tracking controllers, has been applied in PV system installation. Although these improvements have increased the efficiency of PV systems, a few studies have shown that the deposition of dust accumulation on the PV panels can significantly decrease the efficiency of PV systems. In this study, two Photovoltaic (PV) arrays were examined, of which one was cleaned weekly and the other was not cleaned at all during the experiment. The panels were installed in Serdang, Malaysia, at coordinates 2°59'20"N 101°43'30"E and under tropical-based ground conditions. To evaluate the effect of all environmental factors on output power, multiple regression analysis was applied
Lightning protection system elements need to be selected from materials which are resistant to co... more Lightning protection system elements need to be selected from materials which are resistant to corrosion and should be protected from fast degradation. However, over the time corrosion will take place in the presence of galvanically dissimilar metals in the same electrolyte (moisture). Historically, copper, aluminium and copper alloys (including bronze and brass) have been used in lightning protection applications as these materials are highly conductive and abundantly available. Corrosive effects on system components are influenced by the environmental factors such as moisture, soil type and temperature that make the corrosion process highly complex in soil. As per many standards on the installation of lightning protection systems, combinations of materials that naturally form electrolytic couples shall not be used, for example copper and steel, especially in the presence of moisture, in which corrosion will be accelerated. Similarly, the conditions within soil will have adverse effects on the ground system elements. Down conductors entering corrosive soil must be protected against corrosion by a protective covering. The paper presents the causes of corrosion and recent developments in minimising the corrosion associated with lightning protection and grounding systems.
Ufer grounding or concrete encased steel reinforcement grounding is a well recommended electrical... more Ufer grounding or concrete encased steel reinforcement grounding is a well recommended electrical engineering practice for many decades. It utilises the extensive metal framework of the building foundation to conduct and disperse undesired charge, such as that in lightning to the surrounding soil masses. With the presence of moisture, concrete can be quite effective in buffering transient charge and mother earth. However in tropical countries where humidity fluctuation is a norm, moisture content may evaporate as fast as it is available. With absence of moisture, concrete has high resistivity and may severely reduce its effectiveness in grounding lightning currents. Therefore, this is an issue if Ufer grounding is practiced in such countries. A viable solution is to prolong the moisture containment within the concrete. One way to achieve that which was experimented in previous work is by introducing bentonite into the concrete mixture. In this work, the best composition of 30% bentonite mixed concrete encasing grounding steel cage which was obtained in previous work was re-employed in high soil resistivity environment. Its performance is measured in terms of steady state grounding resistance variation and will also be compared with two other experimental settings.
Weather surveillance unmanned aerial vehicles (UAV) are susceptible to extreme weather conditions... more Weather surveillance unmanned aerial vehicles (UAV) are susceptible to extreme weather conditions, especially lightning strike. This study focused on the effects of lightning strikes on composite UAV wings and their evaluations. A wing section measured 300x300x27 mm was fabricated using glass fiber-epoxy skins and polystyrene foam core. It was struck with lightning simulated in laboratory at 200 kV according to IEC 60060-1 (2010) and IEC 60060-2 (2010) standards. Thermal imaging and Ultrasonic Propagation Imaging evaluated one of the damages as 40 mm 2 . Visual inspection showed 96 mm 2 of decolorization around this damage, and further investigation is needed to find the decolorization mechanism.
RBIT) for providing their fullest cooperation in conducting this program. We would also like to t... more RBIT) for providing their fullest cooperation in conducting this program. We would also like to thank the institutional heads who allowed their employees to attend the workshops conducted under this program and the principals of the five schools in Sri Lanka who were very supportive in organizing the school program.
International Journal of Applied Electromagnetics and Mechanics
In this paper, by considering the factors that influence the charge height variation along the li... more In this paper, by considering the factors that influence the charge height variation along the lightning channel and using Maxwell's equations, general expressions in time domain for the evaluation of electromagnetic fields at an observation point are proposed. The lightning channel is assumed to be perpendicular to the ground surface and the ground conductivity is considered to be perfect. Our results showed that the proposed method has good agreement with the measured values, as we validated the outcome using fields measured ...
Abstract.-In order to have a fast determination of electromagnetic fields peaks associated with i... more Abstract.-In order to have a fast determination of electromagnetic fields peaks associated with inclined lightning channel, the analytical electromagnetic field expressions were proposed, assuming a pulse shaped return stroke current at channel base and by considering the channel angle and the observation point angle effects on the electromagnetic fields. Also, the return stroke velocity effects on the peaks of electromagnetic fields were processed. The results were compared with the perpendicular ...
Abstract. The electromagnetic fields associated with a lightning channel can have an effect on po... more Abstract. The electromagnetic fields associated with a lightning channel can have an effect on power lines by creating induced voltages on the power networks. The shape of a channel base current especially up to the first value has a great effect on the radiation components of electromagnetic fields, while the electromagnetic fields due to lightning can be evaluated by considering the different field components. This study considers the behavior of the radiation component of the electric field versus current time front changes as the radiation ...
Return stroke current along lightning channel is reckoned as a fundamental factor for the predict... more Return stroke current along lightning channel is reckoned as a fundamental factor for the prediction of electromagnetic fields at observation points, whilst it can be simulated by current models. The most common current model is the engineering model which is more dependent on the height dependent attenuation factor and the return stroke velocity. Yet, the estimation of constant parameters at attenuation factor and return stroke velocity value are complicated. Using measured values and the PSO (particle swarm optimization) optimization method, this paper aimed at determining the values of current velocity along lightning channel and constant parameters in MTLE and MTLL engineering current models and the behaviour of both current models with respect to measured field were processed where the observation point is set at intermediated distance from lightning channel. Moreover, the results were compared with the previous results and were validated with the measured fields. The results illustrated that the MTLL model cannot be as an appropriate current model compared to MTLE current model for the intermediate distance case. Also, the results based on the MTLE model and the initial data determined by PSO algorithm were in good agreement with the measured fields. The proposed method was also capable of setting up appropriate values for unknown parameters in return stroke current models. In addition, the simulated field using the MTLE current model and initial data from PSO algorithm improved the average difference in percent between simulated field and measured field compared to the initial data from previous studies. Streszczenie. W artykule analizuje się prędkość prądu w kanale wyładowania piorunowego. Do tego celu wykorzystuje się dane pomiarowe i algorytm PSO. Metodę tę porównano z klasyczną metodą bazującą na określaniu tłumienia i szybkości uderzenia powrotnego. (Analiza prądu w kanale wyładowania piorunowego na podstawie pomiaru indukcji magnetycznej z wykorzystaniem algorytmu PSO)
Energy and Environment are two important issues in this decade. Using the clean energy such as s... more Energy and Environment are two important issues in this decade. Using the clean energy such as solar energy generation is growing around word, but with low efficiency. Many parameters from the environment affect the solar photovoltaic panel such as shadow, air pollution and dust. In some experimental setup, there is a small layer that accumulates on top of the photovoltaic (PV). In order to evaluate the effect of dust on Photovoltaic, using two Fix Flat Photovoltaic (FFP) was installed at the Universiti Putra Malaysia. One array is the ‘’Clean array’’ that was cleaned regularly and other is the “Dusty array” that was not cleaned during this research. Data was collected at interval each of 30mins from 1st April to 5th December 2013 for both arrays. Power output and Energy yield for both PV arrays are considered. Findings from this research shows that overly power and energy decrease due to the dust, which accumulates on the surface. The contribution this work with other research was done is we are evaluate the power loss in tropical climate which force with many rainy days
Solar energy, which comes from the sun in the form of solar irradiance, can be directly converte... more Solar energy, which comes from the sun in the form of solar irradiance, can be directly converted to electricity by using photovoltaic (PV) technology. However, the properties related to the nature of semiconductors used in solar cells, has limited the efficiency of PV systems to 1520 %. Thus, in order to increase the efficiency of PV systems, some improvements such as applying sun trackers and maximum power point tracking controllers, has been applied in PV system installation. Although these improvements have increased the efficiency of PV systems, a few studies have shown that the deposition of dust accumulation on the PV panels can significantly decrease the efficiency of PV systems. In this study, two Photovoltaic (PV) arrays were examined, of which one was cleaned weekly and the other was not cleaned at all during the experiment. The panels were installed in Serdang, Malaysia, at coordinates 2°59'20"N 101°43'30"E and under tropical-based ground conditions. To evaluate the effect of all environmental factors on output power, multiple regression analysis was applied
Lightning protection system elements need to be selected from materials which are resistant to co... more Lightning protection system elements need to be selected from materials which are resistant to corrosion and should be protected from fast degradation. However, over the time corrosion will take place in the presence of galvanically dissimilar metals in the same electrolyte (moisture). Historically, copper, aluminium and copper alloys (including bronze and brass) have been used in lightning protection applications as these materials are highly conductive and abundantly available. Corrosive effects on system components are influenced by the environmental factors such as moisture, soil type and temperature that make the corrosion process highly complex in soil. As per many standards on the installation of lightning protection systems, combinations of materials that naturally form electrolytic couples shall not be used, for example copper and steel, especially in the presence of moisture, in which corrosion will be accelerated. Similarly, the conditions within soil will have adverse effects on the ground system elements. Down conductors entering corrosive soil must be protected against corrosion by a protective covering. The paper presents the causes of corrosion and recent developments in minimising the corrosion associated with lightning protection and grounding systems.
Ufer grounding or concrete encased steel reinforcement grounding is a well recommended electrical... more Ufer grounding or concrete encased steel reinforcement grounding is a well recommended electrical engineering practice for many decades. It utilises the extensive metal framework of the building foundation to conduct and disperse undesired charge, such as that in lightning to the surrounding soil masses. With the presence of moisture, concrete can be quite effective in buffering transient charge and mother earth. However in tropical countries where humidity fluctuation is a norm, moisture content may evaporate as fast as it is available. With absence of moisture, concrete has high resistivity and may severely reduce its effectiveness in grounding lightning currents. Therefore, this is an issue if Ufer grounding is practiced in such countries. A viable solution is to prolong the moisture containment within the concrete. One way to achieve that which was experimented in previous work is by introducing bentonite into the concrete mixture. In this work, the best composition of 30% bentonite mixed concrete encasing grounding steel cage which was obtained in previous work was re-employed in high soil resistivity environment. Its performance is measured in terms of steady state grounding resistance variation and will also be compared with two other experimental settings.
Weather surveillance unmanned aerial vehicles (UAV) are susceptible to extreme weather conditions... more Weather surveillance unmanned aerial vehicles (UAV) are susceptible to extreme weather conditions, especially lightning strike. This study focused on the effects of lightning strikes on composite UAV wings and their evaluations. A wing section measured 300x300x27 mm was fabricated using glass fiber-epoxy skins and polystyrene foam core. It was struck with lightning simulated in laboratory at 200 kV according to IEC 60060-1 (2010) and IEC 60060-2 (2010) standards. Thermal imaging and Ultrasonic Propagation Imaging evaluated one of the damages as 40 mm 2 . Visual inspection showed 96 mm 2 of decolorization around this damage, and further investigation is needed to find the decolorization mechanism.
RBIT) for providing their fullest cooperation in conducting this program. We would also like to t... more RBIT) for providing their fullest cooperation in conducting this program. We would also like to thank the institutional heads who allowed their employees to attend the workshops conducted under this program and the principals of the five schools in Sri Lanka who were very supportive in organizing the school program.
International Journal of Applied Electromagnetics and Mechanics
In this paper, by considering the factors that influence the charge height variation along the li... more In this paper, by considering the factors that influence the charge height variation along the lightning channel and using Maxwell's equations, general expressions in time domain for the evaluation of electromagnetic fields at an observation point are proposed. The lightning channel is assumed to be perpendicular to the ground surface and the ground conductivity is considered to be perfect. Our results showed that the proposed method has good agreement with the measured values, as we validated the outcome using fields measured ...
Abstract.-In order to have a fast determination of electromagnetic fields peaks associated with i... more Abstract.-In order to have a fast determination of electromagnetic fields peaks associated with inclined lightning channel, the analytical electromagnetic field expressions were proposed, assuming a pulse shaped return stroke current at channel base and by considering the channel angle and the observation point angle effects on the electromagnetic fields. Also, the return stroke velocity effects on the peaks of electromagnetic fields were processed. The results were compared with the perpendicular ...
Abstract. The electromagnetic fields associated with a lightning channel can have an effect on po... more Abstract. The electromagnetic fields associated with a lightning channel can have an effect on power lines by creating induced voltages on the power networks. The shape of a channel base current especially up to the first value has a great effect on the radiation components of electromagnetic fields, while the electromagnetic fields due to lightning can be evaluated by considering the different field components. This study considers the behavior of the radiation component of the electric field versus current time front changes as the radiation ...
Return stroke current along lightning channel is reckoned as a fundamental factor for the predict... more Return stroke current along lightning channel is reckoned as a fundamental factor for the prediction of electromagnetic fields at observation points, whilst it can be simulated by current models. The most common current model is the engineering model which is more dependent on the height dependent attenuation factor and the return stroke velocity. Yet, the estimation of constant parameters at attenuation factor and return stroke velocity value are complicated. Using measured values and the PSO (particle swarm optimization) optimization method, this paper aimed at determining the values of current velocity along lightning channel and constant parameters in MTLE and MTLL engineering current models and the behaviour of both current models with respect to measured field were processed where the observation point is set at intermediated distance from lightning channel. Moreover, the results were compared with the previous results and were validated with the measured fields. The results illustrated that the MTLL model cannot be as an appropriate current model compared to MTLE current model for the intermediate distance case. Also, the results based on the MTLE model and the initial data determined by PSO algorithm were in good agreement with the measured fields. The proposed method was also capable of setting up appropriate values for unknown parameters in return stroke current models. In addition, the simulated field using the MTLE current model and initial data from PSO algorithm improved the average difference in percent between simulated field and measured field compared to the initial data from previous studies. Streszczenie. W artykule analizuje się prędkość prądu w kanale wyładowania piorunowego. Do tego celu wykorzystuje się dane pomiarowe i algorytm PSO. Metodę tę porównano z klasyczną metodą bazującą na określaniu tłumienia i szybkości uderzenia powrotnego. (Analiza prądu w kanale wyładowania piorunowego na podstawie pomiaru indukcji magnetycznej z wykorzystaniem algorytmu PSO)
Journal of Atmospheric and Solar-terrestrial Physics, 66 (2004) 1733
Pulse trains of irregular pulse characteristics and erratic amplitudes are observed in lightning ... more Pulse trains of irregular pulse characteristics and erratic amplitudes are observed in lightning flashes. These are termed “chaotic pulse trains” in this study. The average width of the individual pulses of these pulse trains is in the range of a few microseconds, with the lower limit of individual measurements extending into the sub-microsecond region. The typical pulse separation lies in the range of 2–View the MathML source. The pulse duration shows a consistent distribution with the most probable value at 400–View the MathML source. Chaotic pulse trains occur most often immediately prior to subsequent strokes. However, they occur also a few milliseconds to several tens of milliseconds prior to return strokes and sometimes do not precede return strokes at all. Twenty-six percent of the total subsequent strokes recorded in this study were preceded by chaotic pulse trains. A few of these pulse trains have occurred in a sequence of several tens of millisecond intervals in between return strokes. We have also found them to occur within very intense cloud flashes. These chaotic pulse trains have features that are different from those of other known pulse trains reported in the lightning literature. Hence, they may be caused by a physical process that has not yet been identified.
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Papers by Chandima Gomes