DC-DC converters play a crucial role in recent and advanced applications, enabling efficient powe... more DC-DC converters play a crucial role in recent and advanced applications, enabling efficient power conversion and management for renewable energy systems, electric vehicles, portable devices, and advanced communication systems. In line with this, the objective of this paper is to introduce a new DC-DC configuration based on the Cuk converter named as Mahafzah converter, which utilizes a coupling capacitor with a lower rated voltage. The paper aims to demonstrate the effectiveness of the proposed converter in terms of improved efficiency, reduced size, and reduced semiconductor device currents compared to the conventional Cuk converter. The proposed configuration comprises the same components as the Cuk converter, but in a different arrangement, without any additional elements. The main advantage of the proposed converter is using a coupling capacitor with a much lower rated voltage than the Cuk converter, resulting in a smaller capacitor size, reduced printed circuit board (PCB) siz...
Solar is a significant renewable energy source. Solar energy can provide for the world’s energy n... more Solar is a significant renewable energy source. Solar energy can provide for the world’s energy needs while minimizing global warming from traditional sources. Forecasting the output of renewable energy has a considerable impact on decisions about the operation and management of power systems. It is crucial to accurately forecast the output of renewable energy sources in order to assure grid dependability and sustainability and to reduce the risk and expense of energy markets and systems. Recent advancements in long short-term memory (LSTM) have attracted researchers to the model, and its promising potential is reflected in the method’s richness and the growing number of papers about it. To facilitate further research and development in this area, this paper investigates LSTM models for forecasting solar energy by using time-series data. The paper is divided into two parts: (1) independent LSTM models and (2) hybrid models that incorporate LSTM as another type of technique. The Root...
The increased usage of renewable energy sources (RESs) and the intermittent nature of the power t... more The increased usage of renewable energy sources (RESs) and the intermittent nature of the power they provide lead to several issues related to stability, reliability, and power quality. In such instances, energy storage systems (ESSs) offer a promising solution to such related RES issues. Hence, several ESS techniques were proposed in the literature to solve these issues; however, a single ESS does not fulfill all the requirements for certain operations and has different tradeoffs for overall system performance. This is mainly due to the limited capability of a single ESS and the potency concerning cost, lifespan, power and energy density, and dynamic response. In order to overcome the tradeoff issue resulting from using a single ESS system, a hybrid energy storage system (HESS) consisting of two or more ESSs appears as an effective solution. Many studies have been considered lately to develop and propose different HESSs for different applications showing the great advantages of usi...
The COVID-19 pandemic has affected every sector in the world, ranging from the education sector t... more The COVID-19 pandemic has affected every sector in the world, ranging from the education sector to the health sector, administration sector, economic sector and others in different ways. Multiple kinds of research have been performed by research centres, education institutions and research groups to determine the extent of how huge of a threat the COVID-19 pandemic poses to each sector. However, detailed analysis and assessment of its impact on every single target within the 17 Sustainable Development Goals (SDGs) have not been discussed so far. We report an assessment of the impact of COVID-19 effect towards achieving the United Nations SDGs. In assessing the pandemic effects, an expert elicitation model is used to show how the COVID-19 severity affects the positive and negative impact on the 169 targets of 17 SDGs under environment, society and economy groups. We found that the COVID-19 pandemic has a low positive impact in achieving only 34 (20.12%) targets across the available S...
Over the last few years, the number of grid-connected photovoltaic systems (GCPVS) has expanded s... more Over the last few years, the number of grid-connected photovoltaic systems (GCPVS) has expanded substantially. The increase in GCPVS integration may lead to operational issues for the grid. Thus, modern GCPVS control mechanisms should be used to improve grid efficiency, reliability, and stability. In terms of frequency stability, conventional generating units usually have a governor control that regulates the primary load frequency in cases of imbalance situations. This control should be activated immediately to avoid a significant frequency variation. Recently, renewable distribution generators such as PV power plants (PVPPs) are steadily replacing conventional generators. However, these generators do not contribute to system inertia or frequency stability. This paper proposes a control strategy for a GCPVS with active power control (APC) to support the grid and frequency stability. The APC enables the PVPP to withstand grid disturbances and maintain frequency within a normal range...
Mathematical Modelling of Engineering Problems, 2022
Network modelling is a critical step in the analysis of distribution networks. It is used to rela... more Network modelling is a critical step in the analysis of distribution networks. It is used to relate the input currents and voltages with the output currents and voltages. This work aims to construct a new admittance matrix for distribution networks. The new admittance matrix is derived based on ABCD matrix, which presents the exact model of different types of power distribution networks considering the unbalance/balanced and single/three phase characteristics. The model takes into account shunt admittances to reflect the accurate performances of the components in the distribution networks, especially in the presence of distributed generation units. The importance of considering shunt admittance is due to the presence of capacitive charging current which can affect the node voltages. Application of the new admittance matrix of distribution networks in Newton-Raphson power flow analysis is performed. The standard IEEE 37 bus system is used to test the validity of the proposed approach...
This paper aims to investigate a hybrid photovoltaic (PV) biogas on-grid energy system in Al-Ghab... more This paper aims to investigate a hybrid photovoltaic (PV) biogas on-grid energy system in Al-Ghabawi territory, Amman, Jordan. The system is accomplished by assessing the system’s reliability and economic viability. Realistic hourly measurements of solar irradiance, ambient temperature, municipal solid waste, and load demand in 2020 were obtained from Jordanian governmental entities. This helps in investigating the proposed system on a real megawatt-scale retrofitting power system. Three case scenarios were performed: loss of power supply probability (LPSP) with total net present cost (TNPC), LPSP with an annualized cost of the system (ACS), and TNPC with the index of reliability (IR). Pareto frontiers were obtained using multi-objective feasibility enhanced particle swarm optimization (MOFEPSO) algorithm. The system’s decision variables were the number of PV panels (Npv) and the number of biogas plant working hours per day (tbiogas). Moreover, three non-dominant Pareto frontier sol...
International Journal of Electrical and Electronic Engineering & Telecommunications, 2020
In a Grid-Connected Photovoltaic System (GCPS), the inverters are applied for integration with th... more In a Grid-Connected Photovoltaic System (GCPS), the inverters are applied for integration with the power grid. This integration brings some issues at the connection point. Therefore, grid-tied inverter control performs a vital role in feeding the power system with good power quality. This study presents a current-controlled Voltage Source Inverter (VSI) strategy for large-scale GCPS generates 1000 kW rated of power. The methodology and structure of the control system are presented. The power quality issues such as harmonics, voltage fluctuation, voltage unbalance, and power factor are limited at the interfacing point into the required limits as imposed by the standards. This study also discusses the controller design and the simulation results are introduced to show its effectiveness. Furthermore, the values obtained may be used to evaluate the power supply quality of various inverter controllers.
Journal of Telecommunication, Electronic and Computer Engineering, 2018
This paper presents power quality analysis on the effects of large-scale photovoltaic power plant... more This paper presents power quality analysis on the effects of large-scale photovoltaic power plant (PVPP) connected to the distribution system of Malaysian grid. For this purpose, the PVPP system with a capacity of 1.5 MW is connected to the medium voltage level of the distribution network through a single-stage voltage source inverter (VSI). Power quality issues at connection point such as current and voltage harmonics distortion and voltage imbalance have been studied based on the standard requirements especially Malaysian standards at different levels of solar irradiation. This analysis is very useful to help researchers and grid operators to study the effects of power quality problems concerning gridconnected PVPP. It can be clearly seen from the measured results that the harmonic distortion and voltage imbalance of the proposed PVPP can meet the Malaysian distribution grid code and national grid standard requirements.
Over the recent years, the installation of photovoltaic (PV) system and integration with electric... more Over the recent years, the installation of photovoltaic (PV) system and integration with electrical grid has become more widespread worldwide. With the significant and rapid increase of photovoltaic power plants (PVPPs) penetration to the electric grid, the power system operation and stability issues become crucial and this leads to continuous evaluation of grid interconnection requirements. For this purpose, the modern grid codes (GCs) require a reliable PV generation system that achieves fault ride-through (FRT) requirements. Therefore, the FRT capability becomes the state of art as one of the challenges faced by the integration of large-scale PV power stations into electrical grid that has not been fully investigated. This research proposes FRT requirements for the connection of PVPPs into Malaysian grid as new requirements. In addition, presents a comprehensive control strategy of large-scale PVPPs to enhance the FRT capability based on modern GCs connection requirements. In ord...
While home energy prices keep rising, homeowners nowadays are searching for the right options to ... more While home energy prices keep rising, homeowners nowadays are searching for the right options to reduce their electricity bills. Besides, the increase in power consumption can contribute to environmental pollution. Therefore, the proper management of energy in the domestic sector is a vital element for creating a sustainable environment and cost reduction. In this study, the most domestic household appliances consumption of energy are modelled and analysed using the fuzzy logic controller (FLC) in order to permit the home energy management system (HEMS) to perform energy utilization estimation and cost analysis. These appliances are the heating ventilation and air conditioning (HVAC), electric water heater (EWH), and lighting, respectively. The developed system can help to analyse the appliances’ energy consumption and cost sceneries during peak and off-peak hours. The modelling of a fuzzy-based domestic appliances controller for HEMS takes the peak and non-peak tariff of Malaysian ...
In the transportation sector, electric battery bus (EBB) deployment is considered to be a potenti... more In the transportation sector, electric battery bus (EBB) deployment is considered to be a potential solution to reduce global warming because no greenhouse gas (GHG) emissions are directly produced by EBBs. In addition to the required charging infrastructure, estimating the energy consumption of buses has become a crucial precondition for the deployment and planning of electric bus fleets. Policy and decision-makers may not have the specific tools needed to estimate the energy consumption of a particular bus network. Therefore, many state-of-the-art studies have proposed models to determine the energy demand of electric buses. However, these studies have not critically reviewed, classified and discussed the challenges of the approaches that are applied to estimate EBBs’ energy demands. Thus, this manuscript provides a detailed review of the forecasting models used to estimate the energy consumption of EBBs. Furthermore, this work fills the gap by classifying the models for estimatin...
A large-scale adoption of electric buses (EBs) is a promising solution to mitigate greenhouse gas... more A large-scale adoption of electric buses (EBs) is a promising solution to mitigate greenhouse gas emissions from the transportation sector. In the upcoming decades, the development of EB technologies will be initiated worldwide, including in Malaysia. Government policies to support EB deployments have been widely established. Therefore, Malaysia’s National Automotive Policy has stated a roadmap of policies to promote a national groundwork accordingly. Following the elaboration of Malaysia’s goals for EBs deployments by 2014 and 2020, there are crucial associated topics for EBs implementation, including EB innovations and technologies adoption. This study presents a deep discussion about the groundwork of EB innovations that have been initiated in Malaysia to meet the roadmap targets. This paper also comprehensively reviews the technical specifications of EB innovation technologies, including Electric Bus Innovation Malaysia, Malaysia Automotive Institute, and Go Auto prototypes. In ...
Wind energy is the most used renewable energy worldwide second only to hydropower. However, the s... more Wind energy is the most used renewable energy worldwide second only to hydropower. However, the stochastic nature of wind speed makes it harder for wind farms to manage the future power production and maintenance schedules efficiently. Many wind speed prediction models exist that focus on advance neural networks and/or preprocessing techniques to improve the accuracy. Since most of these models require a large amount of historic wind data and are validated using the data split method, the application to real-world scenarios cannot be determined. In this paper, we present a multi-step univariate prediction model for wind speed data inspired by the residual U-net architecture of the convolutional neural network (CNN). We propose a residual dilated causal convolutional neural network (Res-DCCNN) with nonlinear attention for multi-step-ahead wind speed forecasting. Our model can outperform long-term short-term memory networks (LSTM), gated recurrent units (GRU), and Res-DCCNN using slid...
The generation and integration of photovoltaic power plants (PVPPs) into the utility grid have in... more The generation and integration of photovoltaic power plants (PVPPs) into the utility grid have increased dramatically over the past two decades. In this sense, and to ensure a high quality of the PVPPs generated power as well as a contribution on the power system security and stability, some of the new power quality requirements imposed by different grid codes and standards in order to regulate the installation of PVPPs and ensure the grid stability. This study aims to investigate the recent integration requirements including voltage sag, voltage flicker, harmonics, voltage unbalance, and frequency variation. Additionally, compliance controls and methods to fulfill these requirements are developed. In line with this, a large-scale three-phase grid-connected PVPP is designed. A modified inverter controller without the use of any extra device is designed to mitigate the sage incidence and achieve the low-voltage ride-through requirement. It can efficiently operate at normal conditions...
DC-DC converters play a crucial role in recent and advanced applications, enabling efficient powe... more DC-DC converters play a crucial role in recent and advanced applications, enabling efficient power conversion and management for renewable energy systems, electric vehicles, portable devices, and advanced communication systems. In line with this, the objective of this paper is to introduce a new DC-DC configuration based on the Cuk converter named as Mahafzah converter, which utilizes a coupling capacitor with a lower rated voltage. The paper aims to demonstrate the effectiveness of the proposed converter in terms of improved efficiency, reduced size, and reduced semiconductor device currents compared to the conventional Cuk converter. The proposed configuration comprises the same components as the Cuk converter, but in a different arrangement, without any additional elements. The main advantage of the proposed converter is using a coupling capacitor with a much lower rated voltage than the Cuk converter, resulting in a smaller capacitor size, reduced printed circuit board (PCB) siz...
Solar is a significant renewable energy source. Solar energy can provide for the world’s energy n... more Solar is a significant renewable energy source. Solar energy can provide for the world’s energy needs while minimizing global warming from traditional sources. Forecasting the output of renewable energy has a considerable impact on decisions about the operation and management of power systems. It is crucial to accurately forecast the output of renewable energy sources in order to assure grid dependability and sustainability and to reduce the risk and expense of energy markets and systems. Recent advancements in long short-term memory (LSTM) have attracted researchers to the model, and its promising potential is reflected in the method’s richness and the growing number of papers about it. To facilitate further research and development in this area, this paper investigates LSTM models for forecasting solar energy by using time-series data. The paper is divided into two parts: (1) independent LSTM models and (2) hybrid models that incorporate LSTM as another type of technique. The Root...
The increased usage of renewable energy sources (RESs) and the intermittent nature of the power t... more The increased usage of renewable energy sources (RESs) and the intermittent nature of the power they provide lead to several issues related to stability, reliability, and power quality. In such instances, energy storage systems (ESSs) offer a promising solution to such related RES issues. Hence, several ESS techniques were proposed in the literature to solve these issues; however, a single ESS does not fulfill all the requirements for certain operations and has different tradeoffs for overall system performance. This is mainly due to the limited capability of a single ESS and the potency concerning cost, lifespan, power and energy density, and dynamic response. In order to overcome the tradeoff issue resulting from using a single ESS system, a hybrid energy storage system (HESS) consisting of two or more ESSs appears as an effective solution. Many studies have been considered lately to develop and propose different HESSs for different applications showing the great advantages of usi...
The COVID-19 pandemic has affected every sector in the world, ranging from the education sector t... more The COVID-19 pandemic has affected every sector in the world, ranging from the education sector to the health sector, administration sector, economic sector and others in different ways. Multiple kinds of research have been performed by research centres, education institutions and research groups to determine the extent of how huge of a threat the COVID-19 pandemic poses to each sector. However, detailed analysis and assessment of its impact on every single target within the 17 Sustainable Development Goals (SDGs) have not been discussed so far. We report an assessment of the impact of COVID-19 effect towards achieving the United Nations SDGs. In assessing the pandemic effects, an expert elicitation model is used to show how the COVID-19 severity affects the positive and negative impact on the 169 targets of 17 SDGs under environment, society and economy groups. We found that the COVID-19 pandemic has a low positive impact in achieving only 34 (20.12%) targets across the available S...
Over the last few years, the number of grid-connected photovoltaic systems (GCPVS) has expanded s... more Over the last few years, the number of grid-connected photovoltaic systems (GCPVS) has expanded substantially. The increase in GCPVS integration may lead to operational issues for the grid. Thus, modern GCPVS control mechanisms should be used to improve grid efficiency, reliability, and stability. In terms of frequency stability, conventional generating units usually have a governor control that regulates the primary load frequency in cases of imbalance situations. This control should be activated immediately to avoid a significant frequency variation. Recently, renewable distribution generators such as PV power plants (PVPPs) are steadily replacing conventional generators. However, these generators do not contribute to system inertia or frequency stability. This paper proposes a control strategy for a GCPVS with active power control (APC) to support the grid and frequency stability. The APC enables the PVPP to withstand grid disturbances and maintain frequency within a normal range...
Mathematical Modelling of Engineering Problems, 2022
Network modelling is a critical step in the analysis of distribution networks. It is used to rela... more Network modelling is a critical step in the analysis of distribution networks. It is used to relate the input currents and voltages with the output currents and voltages. This work aims to construct a new admittance matrix for distribution networks. The new admittance matrix is derived based on ABCD matrix, which presents the exact model of different types of power distribution networks considering the unbalance/balanced and single/three phase characteristics. The model takes into account shunt admittances to reflect the accurate performances of the components in the distribution networks, especially in the presence of distributed generation units. The importance of considering shunt admittance is due to the presence of capacitive charging current which can affect the node voltages. Application of the new admittance matrix of distribution networks in Newton-Raphson power flow analysis is performed. The standard IEEE 37 bus system is used to test the validity of the proposed approach...
This paper aims to investigate a hybrid photovoltaic (PV) biogas on-grid energy system in Al-Ghab... more This paper aims to investigate a hybrid photovoltaic (PV) biogas on-grid energy system in Al-Ghabawi territory, Amman, Jordan. The system is accomplished by assessing the system’s reliability and economic viability. Realistic hourly measurements of solar irradiance, ambient temperature, municipal solid waste, and load demand in 2020 were obtained from Jordanian governmental entities. This helps in investigating the proposed system on a real megawatt-scale retrofitting power system. Three case scenarios were performed: loss of power supply probability (LPSP) with total net present cost (TNPC), LPSP with an annualized cost of the system (ACS), and TNPC with the index of reliability (IR). Pareto frontiers were obtained using multi-objective feasibility enhanced particle swarm optimization (MOFEPSO) algorithm. The system’s decision variables were the number of PV panels (Npv) and the number of biogas plant working hours per day (tbiogas). Moreover, three non-dominant Pareto frontier sol...
International Journal of Electrical and Electronic Engineering & Telecommunications, 2020
In a Grid-Connected Photovoltaic System (GCPS), the inverters are applied for integration with th... more In a Grid-Connected Photovoltaic System (GCPS), the inverters are applied for integration with the power grid. This integration brings some issues at the connection point. Therefore, grid-tied inverter control performs a vital role in feeding the power system with good power quality. This study presents a current-controlled Voltage Source Inverter (VSI) strategy for large-scale GCPS generates 1000 kW rated of power. The methodology and structure of the control system are presented. The power quality issues such as harmonics, voltage fluctuation, voltage unbalance, and power factor are limited at the interfacing point into the required limits as imposed by the standards. This study also discusses the controller design and the simulation results are introduced to show its effectiveness. Furthermore, the values obtained may be used to evaluate the power supply quality of various inverter controllers.
Journal of Telecommunication, Electronic and Computer Engineering, 2018
This paper presents power quality analysis on the effects of large-scale photovoltaic power plant... more This paper presents power quality analysis on the effects of large-scale photovoltaic power plant (PVPP) connected to the distribution system of Malaysian grid. For this purpose, the PVPP system with a capacity of 1.5 MW is connected to the medium voltage level of the distribution network through a single-stage voltage source inverter (VSI). Power quality issues at connection point such as current and voltage harmonics distortion and voltage imbalance have been studied based on the standard requirements especially Malaysian standards at different levels of solar irradiation. This analysis is very useful to help researchers and grid operators to study the effects of power quality problems concerning gridconnected PVPP. It can be clearly seen from the measured results that the harmonic distortion and voltage imbalance of the proposed PVPP can meet the Malaysian distribution grid code and national grid standard requirements.
Over the recent years, the installation of photovoltaic (PV) system and integration with electric... more Over the recent years, the installation of photovoltaic (PV) system and integration with electrical grid has become more widespread worldwide. With the significant and rapid increase of photovoltaic power plants (PVPPs) penetration to the electric grid, the power system operation and stability issues become crucial and this leads to continuous evaluation of grid interconnection requirements. For this purpose, the modern grid codes (GCs) require a reliable PV generation system that achieves fault ride-through (FRT) requirements. Therefore, the FRT capability becomes the state of art as one of the challenges faced by the integration of large-scale PV power stations into electrical grid that has not been fully investigated. This research proposes FRT requirements for the connection of PVPPs into Malaysian grid as new requirements. In addition, presents a comprehensive control strategy of large-scale PVPPs to enhance the FRT capability based on modern GCs connection requirements. In ord...
While home energy prices keep rising, homeowners nowadays are searching for the right options to ... more While home energy prices keep rising, homeowners nowadays are searching for the right options to reduce their electricity bills. Besides, the increase in power consumption can contribute to environmental pollution. Therefore, the proper management of energy in the domestic sector is a vital element for creating a sustainable environment and cost reduction. In this study, the most domestic household appliances consumption of energy are modelled and analysed using the fuzzy logic controller (FLC) in order to permit the home energy management system (HEMS) to perform energy utilization estimation and cost analysis. These appliances are the heating ventilation and air conditioning (HVAC), electric water heater (EWH), and lighting, respectively. The developed system can help to analyse the appliances’ energy consumption and cost sceneries during peak and off-peak hours. The modelling of a fuzzy-based domestic appliances controller for HEMS takes the peak and non-peak tariff of Malaysian ...
In the transportation sector, electric battery bus (EBB) deployment is considered to be a potenti... more In the transportation sector, electric battery bus (EBB) deployment is considered to be a potential solution to reduce global warming because no greenhouse gas (GHG) emissions are directly produced by EBBs. In addition to the required charging infrastructure, estimating the energy consumption of buses has become a crucial precondition for the deployment and planning of electric bus fleets. Policy and decision-makers may not have the specific tools needed to estimate the energy consumption of a particular bus network. Therefore, many state-of-the-art studies have proposed models to determine the energy demand of electric buses. However, these studies have not critically reviewed, classified and discussed the challenges of the approaches that are applied to estimate EBBs’ energy demands. Thus, this manuscript provides a detailed review of the forecasting models used to estimate the energy consumption of EBBs. Furthermore, this work fills the gap by classifying the models for estimatin...
A large-scale adoption of electric buses (EBs) is a promising solution to mitigate greenhouse gas... more A large-scale adoption of electric buses (EBs) is a promising solution to mitigate greenhouse gas emissions from the transportation sector. In the upcoming decades, the development of EB technologies will be initiated worldwide, including in Malaysia. Government policies to support EB deployments have been widely established. Therefore, Malaysia’s National Automotive Policy has stated a roadmap of policies to promote a national groundwork accordingly. Following the elaboration of Malaysia’s goals for EBs deployments by 2014 and 2020, there are crucial associated topics for EBs implementation, including EB innovations and technologies adoption. This study presents a deep discussion about the groundwork of EB innovations that have been initiated in Malaysia to meet the roadmap targets. This paper also comprehensively reviews the technical specifications of EB innovation technologies, including Electric Bus Innovation Malaysia, Malaysia Automotive Institute, and Go Auto prototypes. In ...
Wind energy is the most used renewable energy worldwide second only to hydropower. However, the s... more Wind energy is the most used renewable energy worldwide second only to hydropower. However, the stochastic nature of wind speed makes it harder for wind farms to manage the future power production and maintenance schedules efficiently. Many wind speed prediction models exist that focus on advance neural networks and/or preprocessing techniques to improve the accuracy. Since most of these models require a large amount of historic wind data and are validated using the data split method, the application to real-world scenarios cannot be determined. In this paper, we present a multi-step univariate prediction model for wind speed data inspired by the residual U-net architecture of the convolutional neural network (CNN). We propose a residual dilated causal convolutional neural network (Res-DCCNN) with nonlinear attention for multi-step-ahead wind speed forecasting. Our model can outperform long-term short-term memory networks (LSTM), gated recurrent units (GRU), and Res-DCCNN using slid...
The generation and integration of photovoltaic power plants (PVPPs) into the utility grid have in... more The generation and integration of photovoltaic power plants (PVPPs) into the utility grid have increased dramatically over the past two decades. In this sense, and to ensure a high quality of the PVPPs generated power as well as a contribution on the power system security and stability, some of the new power quality requirements imposed by different grid codes and standards in order to regulate the installation of PVPPs and ensure the grid stability. This study aims to investigate the recent integration requirements including voltage sag, voltage flicker, harmonics, voltage unbalance, and frequency variation. Additionally, compliance controls and methods to fulfill these requirements are developed. In line with this, a large-scale three-phase grid-connected PVPP is designed. A modified inverter controller without the use of any extra device is designed to mitigate the sage incidence and achieve the low-voltage ride-through requirement. It can efficiently operate at normal conditions...
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Papers by Ali Al-shetwi