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Papers by Mohamed Youssef

Journal of Atmospheric and Solar-Terrestrial Physics, 2016

Different models are introduced to predict the daily global solar radiation in different location... more Different models are introduced to predict the daily global solar radiation in different locations but there is no specific model based on the day of the year is proposed for many locations around the world. In this study, more than 20 years of measured data for daily global solar radiation on a horizontal surface are used to develop and validate seven models to estimate the daily global solar radiation by day of the year for ten cities around Egypt as a case study. Moreover, the generalization capability for the best models is examined all over the country. The regression analysis is employed to calculate t he coefficients of different suggested models. The statistical indicators namely, RMSE, MABE, MAPE, r and R 2 are calculated to evaluate the performance of the developed models. Based on the validation with the available data, the results show that the hybrid sine and cosine wave model and 4th order polynomial model have the best performance among other suggested models. Consequently, these two models coupled with suitable coefficients can be used for estimating the daily global solar radiation on a horizont al surface for each city, and also for all the locations around the studied region. It is believed that the established models in this work are applicable and significant for quick estimation for the average daily global solar radiation on a horizontal sur face with higher accuracy. The values of global solar radiation generated by this approach can be utilized in the design and estimation of the performance of different solar applications.

Applied Energy, 2016

This study presents new ambient-temperature-based models for estimating global solar radiation as... more This study presents new ambient-temperature-based models for estimating global solar radiation as alternatives to the widely used sunshine-based models owing to the unavailability of sunshine data at all locations around the world. Seventeen new temperature-based models are established, validated and compared with other three models proposed in the literature (the Annandale, Allen and Goodin models) to estimate the monthly average daily global solar radiation on a horizontal surface. These models are developed using a 20-year measured dataset of global solar radiation for the case study location (Lat. 30°51′N and long. 29°34′E), and then, the general formulae of the newly suggested models are examined for ten different locations around Egypt. Moreover, the local formulae for the models are established and validated for two coastal locations where the general formulae give inaccurate predictions. Mostly common statistical errors are utilized to evaluate the performance of these models and identify the most accurate model. The obtained results show that the local formula for the most accurate new model provides good predictions for global solar radiation at different locations, especially at coastal sites. Moreover, the local and general formulas of the most accurate temperature-based model also perform better than the two most accurate sunshine-based models from the literature. The quick and accurate estimations of the global solar radiation using this approach can be employed in the design and evaluation of performance for different solar applications.

Thermal Science, 2017

The unavailability of the solar radiation measurements for different locations around the world l... more The unavailability of the solar radiation measurements for different locations around the world leads to develop various empirical models to estimate the global solar radiation. In this consider, this study aims to investigate the performance of different solar radiation models to predict the monthly average daily global solar radiation on a horizontal surface. To achieve this, the measured global solar radiation data for a case study location are used. The model predictions are compared with the measured data to introduce the most accurate model for estimating the global solar radiation. The performance of each model is evaluated based on the different statistical indicators. The results show that the Robaa model has the best performance among the other models. Consequently, it can be used for estimating global solar radiation on a horizontal surface in the location under consideration. The accurate estimations of the global solar radiation using this approach can be used in the de...

Most of scientists looking for a stable, reliable, cheap, clean and renewable source of energy af... more Most of scientists looking for a stable, reliable, cheap, clean and renewable source of energy after the growth in using the fossil fuel. One of the most promising devices is Fuel cell. This step has taken to guide the researchers whom want to optimize to study these electrochemical devices. In this study model for direct methanol fuel cell (DMFC) and proton exchange membrane fuel cell (PEMFC) has been developed using software Comsol mutiphysics. The two models were validated by published experimental data. Model output for DMFC is compared by the output of PEMFC. This study is carried out to define the suitable of DMFC and PEMFC for different applications.

Proton exchange membrane fuel cell (PEMFC) is one of the most promising types of clean and renewa... more Proton exchange membrane fuel cell (PEMFC) is one of the most promising types of clean and renewable energy. PEMFC is a device that converts chemical energy to electrical energy. In this study the numerical model has been developed by using MATLAB program to optimize the fuel cell operating conditions to achieve high power density and efficiency for PEMFC. The two main parameters that were considered in this work were cell temperature and air to fuel ratio. The numerical results were validated by experimental data which obtained in our laboratory by using Fuel cell test system (Scribner Associates Model 850e).

Performance Assessment of Different Global Solar Radiation Models – Case Study: New Borg El-Arab city, Egypt, Apr 8, 2017

The unavailability of the solar radiation measurements for different locations around the world l... more The unavailability of the solar radiation measurements for different locations around the world leads to develop various empirical models to estimate the global solar radiation. In this consider, this study aims to investigate the performance of different solar radiation models to predict the monthly average daily global solar radiation on a horizontal surface. To achieve this, the measured global solar radiation data for a case study location are used. The models predications are compared with the measured data to introduce the most accurate model for estimating the global solar radiation. The performance of each model is evaluated based on the different statistical indicators. The results show that the Robaa model has the best performance among the other models. Consequently, it can be used for estimating global solar radiation on a horizontal surface in the location under consideration. The accurate estimations of the global solar radiation using this approach can be used in the design and evaluation of performance for different solar applications.

An accurate knowledge of solar radiation considers the first step in solar energy availability as... more An accurate knowledge of solar radiation considers the first step in solar energy availability assessment, also it is the primary input for various solar energy applications. In this regard, due to the lack of the solar radiation measurements, several models around the world have been proposed for estimating solar radiation. Generally, sunshine duration is the most common parameter used for estimating global solar radiation. Although, sunshine based models can't be apply at several locations, due to the unavailability of sunshine. Accordingly, this study aims to investigate the performance of 31 non-sunshine based models in estimating the monthly average of daily global solar radiation on a horizontal surface. For achieving this, over than 20 years of measured global solar radiation data in the location of the study (Latitude 30˚51 ̀ N and longitude 29˚34 ̀ E) are utilized for establishing and validating the models. The models are divided into six categories; (1) Only function of temperature; (2) Only function of cloud cover; (3) Only function of relative humidity; (4) Function of extraterrestrial solar radiation and solar declination angle; (5) Function of temperature and cloud cover; (6) Function of temperature and relative humidity. The mostly common statistical indicators are used to differentiate between the performances of these models and to identify the best model. The best model for every category is distinguished as well as the most accurate models among all models recognized. According to the results, some models are completely improper for applying in the region of the study, and other differ in the performance of prediction. Besides, InciTürk Toğrul model and Can Ertekin model (Eq. 19 and 18) which based on extraterrestrial radiation and solar declination showed the best performance, with excellent coefficient of determination values (R^2 ≥ 0.99). Therefore, InciTürkToğrul model and Can Ertekin model are the recommended models for estimating monthly average daily global solar radiation on a horizontal surface.

Performance Assessment of Different Day-of-the-Year-based Models for Estimating Global Solar Radiation-Case Study: Egypt, Sep 28, 2016

Different models are introduced to predict the daily global solar radiation in different location... more Different models are introduced to predict the daily global solar radiation in different locations but there is no specific model based on the day of the year is proposed for many locations around the world. In this study, more than 20 years of measured data for daily global solar radiation on a horizontal surface are used to develop and validate seven models to estimate the daily global solar radiation by day of the year for ten cities around Egypt as a case study. Moreover, the generalization capability for the best models is examined all over the country. The regression analysis is employed to calculate the coefficients of different suggested models. The statistical indicators namely, RMSE, MABE, MAPE, r and R 2 are calculated to evaluate the performance of the developed models. Based on the validation with the available data, the results show that the hybrid sine and cosine wave model and 4th order polynomial model have the best performance among other suggested models. Consequently, these two models coupled with suitable coefficients can be used for estimating the daily global solar radiation on a horizontal surface for each city, and also for all the locations around the studied region. It is believed that the established models in this work are applicable and significant for quick estimation for the average daily global solar radiation on a horizontal surface with higher accuracy. The values of global solar radiation generated by this approach can be utilized in the design and estimation of the performance of different solar applications.

2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE), 2014

Journal of Atmospheric and Solar-Terrestrial Physics, 2016

Different models are introduced to predict the daily global solar radiation in different location... more Different models are introduced to predict the daily global solar radiation in different locations but there is no specific model based on the day of the year is proposed for many locations around the world. In this study, more than 20 years of measured data for daily global solar radiation on a horizontal surface are used to develop and validate seven models to estimate the daily global solar radiation by day of the year for ten cities around Egypt as a case study. Moreover, the generalization capability for the best models is examined all over the country. The regression analysis is employed to calculate t he coefficients of different suggested models. The statistical indicators namely, RMSE, MABE, MAPE, r and R 2 are calculated to evaluate the performance of the developed models. Based on the validation with the available data, the results show that the hybrid sine and cosine wave model and 4th order polynomial model have the best performance among other suggested models. Consequently, these two models coupled with suitable coefficients can be used for estimating the daily global solar radiation on a horizont al surface for each city, and also for all the locations around the studied region. It is believed that the established models in this work are applicable and significant for quick estimation for the average daily global solar radiation on a horizontal sur face with higher accuracy. The values of global solar radiation generated by this approach can be utilized in the design and estimation of the performance of different solar applications.

Applied Energy, 2016

This study presents new ambient-temperature-based models for estimating global solar radiation as... more This study presents new ambient-temperature-based models for estimating global solar radiation as alternatives to the widely used sunshine-based models owing to the unavailability of sunshine data at all locations around the world. Seventeen new temperature-based models are established, validated and compared with other three models proposed in the literature (the Annandale, Allen and Goodin models) to estimate the monthly average daily global solar radiation on a horizontal surface. These models are developed using a 20-year measured dataset of global solar radiation for the case study location (Lat. 30°51′N and long. 29°34′E), and then, the general formulae of the newly suggested models are examined for ten different locations around Egypt. Moreover, the local formulae for the models are established and validated for two coastal locations where the general formulae give inaccurate predictions. Mostly common statistical errors are utilized to evaluate the performance of these models and identify the most accurate model. The obtained results show that the local formula for the most accurate new model provides good predictions for global solar radiation at different locations, especially at coastal sites. Moreover, the local and general formulas of the most accurate temperature-based model also perform better than the two most accurate sunshine-based models from the literature. The quick and accurate estimations of the global solar radiation using this approach can be employed in the design and evaluation of performance for different solar applications.

Thermal Science, 2017

The unavailability of the solar radiation measurements for different locations around the world l... more The unavailability of the solar radiation measurements for different locations around the world leads to develop various empirical models to estimate the global solar radiation. In this consider, this study aims to investigate the performance of different solar radiation models to predict the monthly average daily global solar radiation on a horizontal surface. To achieve this, the measured global solar radiation data for a case study location are used. The model predictions are compared with the measured data to introduce the most accurate model for estimating the global solar radiation. The performance of each model is evaluated based on the different statistical indicators. The results show that the Robaa model has the best performance among the other models. Consequently, it can be used for estimating global solar radiation on a horizontal surface in the location under consideration. The accurate estimations of the global solar radiation using this approach can be used in the de...

Most of scientists looking for a stable, reliable, cheap, clean and renewable source of energy af... more Most of scientists looking for a stable, reliable, cheap, clean and renewable source of energy after the growth in using the fossil fuel. One of the most promising devices is Fuel cell. This step has taken to guide the researchers whom want to optimize to study these electrochemical devices. In this study model for direct methanol fuel cell (DMFC) and proton exchange membrane fuel cell (PEMFC) has been developed using software Comsol mutiphysics. The two models were validated by published experimental data. Model output for DMFC is compared by the output of PEMFC. This study is carried out to define the suitable of DMFC and PEMFC for different applications.

Proton exchange membrane fuel cell (PEMFC) is one of the most promising types of clean and renewa... more Proton exchange membrane fuel cell (PEMFC) is one of the most promising types of clean and renewable energy. PEMFC is a device that converts chemical energy to electrical energy. In this study the numerical model has been developed by using MATLAB program to optimize the fuel cell operating conditions to achieve high power density and efficiency for PEMFC. The two main parameters that were considered in this work were cell temperature and air to fuel ratio. The numerical results were validated by experimental data which obtained in our laboratory by using Fuel cell test system (Scribner Associates Model 850e).

Performance Assessment of Different Global Solar Radiation Models – Case Study: New Borg El-Arab city, Egypt, Apr 8, 2017

The unavailability of the solar radiation measurements for different locations around the world l... more The unavailability of the solar radiation measurements for different locations around the world leads to develop various empirical models to estimate the global solar radiation. In this consider, this study aims to investigate the performance of different solar radiation models to predict the monthly average daily global solar radiation on a horizontal surface. To achieve this, the measured global solar radiation data for a case study location are used. The models predications are compared with the measured data to introduce the most accurate model for estimating the global solar radiation. The performance of each model is evaluated based on the different statistical indicators. The results show that the Robaa model has the best performance among the other models. Consequently, it can be used for estimating global solar radiation on a horizontal surface in the location under consideration. The accurate estimations of the global solar radiation using this approach can be used in the design and evaluation of performance for different solar applications.

An accurate knowledge of solar radiation considers the first step in solar energy availability as... more An accurate knowledge of solar radiation considers the first step in solar energy availability assessment, also it is the primary input for various solar energy applications. In this regard, due to the lack of the solar radiation measurements, several models around the world have been proposed for estimating solar radiation. Generally, sunshine duration is the most common parameter used for estimating global solar radiation. Although, sunshine based models can't be apply at several locations, due to the unavailability of sunshine. Accordingly, this study aims to investigate the performance of 31 non-sunshine based models in estimating the monthly average of daily global solar radiation on a horizontal surface. For achieving this, over than 20 years of measured global solar radiation data in the location of the study (Latitude 30˚51 ̀ N and longitude 29˚34 ̀ E) are utilized for establishing and validating the models. The models are divided into six categories; (1) Only function of temperature; (2) Only function of cloud cover; (3) Only function of relative humidity; (4) Function of extraterrestrial solar radiation and solar declination angle; (5) Function of temperature and cloud cover; (6) Function of temperature and relative humidity. The mostly common statistical indicators are used to differentiate between the performances of these models and to identify the best model. The best model for every category is distinguished as well as the most accurate models among all models recognized. According to the results, some models are completely improper for applying in the region of the study, and other differ in the performance of prediction. Besides, InciTürk Toğrul model and Can Ertekin model (Eq. 19 and 18) which based on extraterrestrial radiation and solar declination showed the best performance, with excellent coefficient of determination values (R^2 ≥ 0.99). Therefore, InciTürkToğrul model and Can Ertekin model are the recommended models for estimating monthly average daily global solar radiation on a horizontal surface.

Performance Assessment of Different Day-of-the-Year-based Models for Estimating Global Solar Radiation-Case Study: Egypt, Sep 28, 2016

Different models are introduced to predict the daily global solar radiation in different location... more Different models are introduced to predict the daily global solar radiation in different locations but there is no specific model based on the day of the year is proposed for many locations around the world. In this study, more than 20 years of measured data for daily global solar radiation on a horizontal surface are used to develop and validate seven models to estimate the daily global solar radiation by day of the year for ten cities around Egypt as a case study. Moreover, the generalization capability for the best models is examined all over the country. The regression analysis is employed to calculate the coefficients of different suggested models. The statistical indicators namely, RMSE, MABE, MAPE, r and R 2 are calculated to evaluate the performance of the developed models. Based on the validation with the available data, the results show that the hybrid sine and cosine wave model and 4th order polynomial model have the best performance among other suggested models. Consequently, these two models coupled with suitable coefficients can be used for estimating the daily global solar radiation on a horizontal surface for each city, and also for all the locations around the studied region. It is believed that the established models in this work are applicable and significant for quick estimation for the average daily global solar radiation on a horizontal surface with higher accuracy. The values of global solar radiation generated by this approach can be utilized in the design and estimation of the performance of different solar applications.

2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE), 2014