nawfal ali - Academia.edu (original) (raw)

Papers by nawfal ali

Research paper thumbnail of 0 CV-Nawfal K Ali, 2020

Research paper thumbnail of Design and implementation of programmable multi-mode GNSS signal simulator

2010 IEEE 12th International Conference on Communication Technology, 2010

ABSTRACT

Research paper thumbnail of An Effect of Binary Fluid on the Thermal Performance of Pulsation Heat Pipe

International Journal of Applied Mechanics and Engineering, 2022

A pulsation heat pipe is an efficient heat pipe used in many engineering applications. This study... more A pulsation heat pipe is an efficient heat pipe used in many engineering applications. This study aims to test the effect of working fluids on the thermal performance of pulsation heat pipe. Seven turned pulsation heat pipes were designed and manufactured from a copper pipe with a 3.5 mm inner diameter. The lengths of an evaporation part, an adiabatic passage, and a condenser part were 300 mm, 210 mm, and 300 mm, respectively. In this study, three different fluids were used as the working fluid: distilled water, methanol, and binary fluid (a mixture of water and methanol) with a 50% filling ratio. Compared to water, the experimental results suggested that methanol had a better thermal performance when used as a working fluid in the PHP. On the other hand, a binary fluid enhanced the lower thermal performance of water (29% reduction in the thermal resistance and a 20% increase in the effective thermal conductivity of the PHP).

Research paper thumbnail of The Effect of Darrieus and Savonius Wind Turbines Position on the Performance of the Hybrid Wind Turbine at Low Wind Speed

This paper presents an experimental and numerical simulation to investigate a hybrid vertical axi... more This paper presents an experimental and numerical simulation to investigate a hybrid vertical axis wind turbine model highly efficient which can be worked at low wind speed by studying the aerodynamic characteristics of four models of hybrid VAWTs. The hybrid WT consists of the SWT having two blades and the DWT type straight having two blades. Four models were constructed to study experimentally and numerically to choose the best model. Two models were DWT in the upper and SWT in the lower, also two models were SWT in the upper and DWT in the lower. The phase stage angle between the turbines is 0o and 90o . The experimental and numerical results showed that the performance of hybrid WT where DWT in the upper and SWT in the lower with phase stage 90o is better than in the other models, it can be started to work at a wind velocity of 2.2 m/s. At the wind velocity 3 m/s, the values of the parameters are the rotational speed (198 rpm), the CP (0.3195), the CT (0.2003), the TSR (1.6) and...

Research paper thumbnail of Effect of Conventional Multistage Savonius wind Turbines on the Performance of the Turbine at Low Wind Velocity

Journal of Advanced Research in Dynamical and Control Systems, 2019

This paper presents a model for the evaluation of the optimal design of Savonius vertical wind tu... more This paper presents a model for the evaluation of the optimal design of Savonius vertical wind turbine by CFD analysis and experimental tests, through analyzing the stage number, number of blades and tip speed ratio. For this purpose, a full validation campaign has been carried out through a systematic comparison of numerical simulations with wind tunnel experiments data and other references for grid dependency and correlation coefficient. In this case, results show that the correlation coefficient (0.936) better than the correlation coefficient (0.93) in reference [17]. Also, grid dependency was included and described by average y+ values between 1-5.The experiments were done for all Savonius wind turbine models by using a subsonic wind tunnel under open type test section with airflow speed was 3 m/s and different tip speed ratio TSR. The results show that the power coefficient Cp increases when TSR increases to a certain value then decreases for all models. The torque coefficient CT decreases when TSR increases for all models. Savonius wind turbine performance with two blades rotor good agreement was obtained between experimental and numerical results gave better results than other models at low wind speed. The maximum experimental Cp and CT for two brackets rotor are 0.23 at TSR 0.685 and 0.402 at TSR 0.175 respectively.

Research paper thumbnail of An Experimental and Numerical Investigation on Darrieus Vertical Axis Wind Turbine Types at Low Wind Speed

This paper presents a model for the evaluation of the optimal design of Darrieus vertical axis wi... more This paper presents a model for the evaluation of the optimal design of Darrieus vertical axis wind turbine by CFD analysis and experimental tests, through analyzing six models of Darrieus wind turbines, number of blades and tip speed ratio. For this purpose, a full investigation campaign has been carried out through a systematic comparison of numerical simulations with wind tunnel experiments data. The airfoil profile used in the turbine blades was DU06W200 and constant geometry dimensions to turbines. The experiments were done for all Darrieus wind turbine models by using a subsonic wind tunnel under open type test section with airflow speed range (3-7.65) m/s and different tip speed ratio TSR. The results show that Darrieus WT straight type can be self-starting at the wind velocity 3 m/s, where other types cannot be starting at less than wind speed 5 m/s. The rotational speed (N) increases for all models with the wind velocity increase. The power coefficient (CP) increases when t...

Research paper thumbnail of Fast Reaction to Sudden Concept Drift in the Absence of Class Labels

Applied Sciences, Jan 14, 2020

A data stream can be considered as a sequence of examples that arrive continuously and are potent... more A data stream can be considered as a sequence of examples that arrive continuously and are potentially unbounded, such as web page visits, sensor readings and call records. One of the serious and challenging problems that appears in a data stream is concept drift. This problem occurs when the relation between the input data and the target variable changes over time. Most existing works make an optimistic assumption that all incoming data are labelled and the class labels are available immediately. However, such an assumption is not always valid. Therefore, a lack of class labels aggravates the problem of concept drift detection. With this motivation, we propose a drift detector that reacts naturally to sudden drifts in the absence of class labels. In a novel way, the proposed detector reacts to concept drift in the absence of class labels, where the true label of an example is not necessary. Instead of monitoring the error estimates, the proposed detector monitors the diversity of a pair of classifiers, where the true label of an example is not necessary to determine whether components disagree. Using several datasets, an experimental evaluation and comparison is conducted against several existing detectors. The experiment results show that the proposed detector can detect drifts with less delay, runtime and memory usage.

Research paper thumbnail of 0 CV-Nawfal K Ali, 2020

Research paper thumbnail of Design and implementation of programmable multi-mode GNSS signal simulator

2010 IEEE 12th International Conference on Communication Technology, 2010

ABSTRACT

Research paper thumbnail of An Effect of Binary Fluid on the Thermal Performance of Pulsation Heat Pipe

International Journal of Applied Mechanics and Engineering, 2022

A pulsation heat pipe is an efficient heat pipe used in many engineering applications. This study... more A pulsation heat pipe is an efficient heat pipe used in many engineering applications. This study aims to test the effect of working fluids on the thermal performance of pulsation heat pipe. Seven turned pulsation heat pipes were designed and manufactured from a copper pipe with a 3.5 mm inner diameter. The lengths of an evaporation part, an adiabatic passage, and a condenser part were 300 mm, 210 mm, and 300 mm, respectively. In this study, three different fluids were used as the working fluid: distilled water, methanol, and binary fluid (a mixture of water and methanol) with a 50% filling ratio. Compared to water, the experimental results suggested that methanol had a better thermal performance when used as a working fluid in the PHP. On the other hand, a binary fluid enhanced the lower thermal performance of water (29% reduction in the thermal resistance and a 20% increase in the effective thermal conductivity of the PHP).

Research paper thumbnail of The Effect of Darrieus and Savonius Wind Turbines Position on the Performance of the Hybrid Wind Turbine at Low Wind Speed

This paper presents an experimental and numerical simulation to investigate a hybrid vertical axi... more This paper presents an experimental and numerical simulation to investigate a hybrid vertical axis wind turbine model highly efficient which can be worked at low wind speed by studying the aerodynamic characteristics of four models of hybrid VAWTs. The hybrid WT consists of the SWT having two blades and the DWT type straight having two blades. Four models were constructed to study experimentally and numerically to choose the best model. Two models were DWT in the upper and SWT in the lower, also two models were SWT in the upper and DWT in the lower. The phase stage angle between the turbines is 0o and 90o . The experimental and numerical results showed that the performance of hybrid WT where DWT in the upper and SWT in the lower with phase stage 90o is better than in the other models, it can be started to work at a wind velocity of 2.2 m/s. At the wind velocity 3 m/s, the values of the parameters are the rotational speed (198 rpm), the CP (0.3195), the CT (0.2003), the TSR (1.6) and...

Research paper thumbnail of Effect of Conventional Multistage Savonius wind Turbines on the Performance of the Turbine at Low Wind Velocity

Journal of Advanced Research in Dynamical and Control Systems, 2019

This paper presents a model for the evaluation of the optimal design of Savonius vertical wind tu... more This paper presents a model for the evaluation of the optimal design of Savonius vertical wind turbine by CFD analysis and experimental tests, through analyzing the stage number, number of blades and tip speed ratio. For this purpose, a full validation campaign has been carried out through a systematic comparison of numerical simulations with wind tunnel experiments data and other references for grid dependency and correlation coefficient. In this case, results show that the correlation coefficient (0.936) better than the correlation coefficient (0.93) in reference [17]. Also, grid dependency was included and described by average y+ values between 1-5.The experiments were done for all Savonius wind turbine models by using a subsonic wind tunnel under open type test section with airflow speed was 3 m/s and different tip speed ratio TSR. The results show that the power coefficient Cp increases when TSR increases to a certain value then decreases for all models. The torque coefficient CT decreases when TSR increases for all models. Savonius wind turbine performance with two blades rotor good agreement was obtained between experimental and numerical results gave better results than other models at low wind speed. The maximum experimental Cp and CT for two brackets rotor are 0.23 at TSR 0.685 and 0.402 at TSR 0.175 respectively.

Research paper thumbnail of An Experimental and Numerical Investigation on Darrieus Vertical Axis Wind Turbine Types at Low Wind Speed

This paper presents a model for the evaluation of the optimal design of Darrieus vertical axis wi... more This paper presents a model for the evaluation of the optimal design of Darrieus vertical axis wind turbine by CFD analysis and experimental tests, through analyzing six models of Darrieus wind turbines, number of blades and tip speed ratio. For this purpose, a full investigation campaign has been carried out through a systematic comparison of numerical simulations with wind tunnel experiments data. The airfoil profile used in the turbine blades was DU06W200 and constant geometry dimensions to turbines. The experiments were done for all Darrieus wind turbine models by using a subsonic wind tunnel under open type test section with airflow speed range (3-7.65) m/s and different tip speed ratio TSR. The results show that Darrieus WT straight type can be self-starting at the wind velocity 3 m/s, where other types cannot be starting at less than wind speed 5 m/s. The rotational speed (N) increases for all models with the wind velocity increase. The power coefficient (CP) increases when t...

Research paper thumbnail of Fast Reaction to Sudden Concept Drift in the Absence of Class Labels

Applied Sciences, Jan 14, 2020

A data stream can be considered as a sequence of examples that arrive continuously and are potent... more A data stream can be considered as a sequence of examples that arrive continuously and are potentially unbounded, such as web page visits, sensor readings and call records. One of the serious and challenging problems that appears in a data stream is concept drift. This problem occurs when the relation between the input data and the target variable changes over time. Most existing works make an optimistic assumption that all incoming data are labelled and the class labels are available immediately. However, such an assumption is not always valid. Therefore, a lack of class labels aggravates the problem of concept drift detection. With this motivation, we propose a drift detector that reacts naturally to sudden drifts in the absence of class labels. In a novel way, the proposed detector reacts to concept drift in the absence of class labels, where the true label of an example is not necessary. Instead of monitoring the error estimates, the proposed detector monitors the diversity of a pair of classifiers, where the true label of an example is not necessary to determine whether components disagree. Using several datasets, an experimental evaluation and comparison is conducted against several existing detectors. The experiment results show that the proposed detector can detect drifts with less delay, runtime and memory usage.