omar mohamed - Academia.edu (original) (raw)

Papers by omar mohamed

Research paper thumbnail of Applied Newly Developed Technology To Overcome Deepwater Completion Difficulties

Proceedings of SPE/IADC Middle East Drilling and Technology Conference, 2007

Research paper thumbnail of One-Trip Installation of 4-3/4-in Expandable Screen Assembly

SPE/IADC Middle East Drilling and Technology Conference, 2007

... An economics “untenable” gravel-pack deployment in the Mediterranean Sea required isolation a... more ... An economics “untenable” gravel-pack deployment in the Mediterranean Sea required isolation and ... With the planned expandable screen assembly successfully deployed, a circulation was broken and 1.125 ... the Liner Hanger set with only the Hanger giving some difficulty with a ...

Research paper thumbnail of High Gas-Rate Production: Expandable Solutions in the Mediterranean Sea

SPE Annual Technical Conference and Exhibition, 2008

An operator facing the need for sand control in multiple maturing fields investigated the possibi... more An operator facing the need for sand control in multiple maturing fields investigated the possibility of using expandable technologies to address their needs. Years of production and the onset of water production has affected that need. After an extensive study of rock mechanics and properties and how sand production might be initiated based on these properties, the investigation for an optimized sand control technique began. A systematic approach ensued between operator and Service Company in an attempt to define an optimized solution for sand control in each of these fields. Conventional cased hole gravel packs were excluded due to the need for a larger flow area for handling the high gas rates. Open hole gravel packing was investigated yet ruled out due the exposed unstable shales during the packing operations. Ultimately the optimized solution led to the deployment of an expandable screen system to ensure sand control for the remaining life of each well. The undesirable shales w...

Research paper thumbnail of Una estrategia de aceleración basada en submuestreo para el análisis dinámico de puentes de ferrocarril de alta velocidad

Research paper thumbnail of Nickel-titanium shape memory alloys made by selective laser melting: a review on process optimisation

Advances in Manufacturing, 2022

Research paper thumbnail of Modeling, analysis, and optimization of dimensional accuracy of FDM-fabricated parts using definitive screening design and deep learning feedforward artificial neural network

Advances in Manufacturing, 2021

Additive manufacturing (AM) technologies such as fused deposition modeling (FDM) rely on the qual... more Additive manufacturing (AM) technologies such as fused deposition modeling (FDM) rely on the quality of manufactured products and the process capability. Currently, the dimensional accuracy and stability of any AM process is essential for ensuring that customer specifications are satisfied at the highest standard, and variations are controlled without significantly affecting the functioning of processes, machines, and product structures. This study aims to investigate the effects of FDM fabrication conditions on the dimensional accuracy of cylindrical parts. In this study, a new class of experimental design techniques for integrated second-order definitive screening design (DSD) and an artificial neural network (ANN) are proposed for designing experiments to evaluate and predict the effects of six important operating variables. By determining the optimum fabrication conditions to obtain better dimensional accuracies for cylindrical parts, the time consumption and number of complex e...

Research paper thumbnail of Investigation of dimensional variation in parts manufactured by fused deposition modeling using Gauge Repeatability and Reproducibility

IOP Conference Series: Materials Science and Engineering, 2018

Research paper thumbnail of Experimental Study of the Wear Performance of Fused Deposition Modeling Printed Polycarbonate-Acrylonitrile Butadiene Styrene Parts Using Definitive Screening Design and Machine Learning-Genetic Algorithm

Journal of Materials Engineering and Performance, 2021

The purpose of this study is to investigate the influence of fused deposition modeling (FDM) proc... more The purpose of this study is to investigate the influence of fused deposition modeling (FDM) process parameters on the tribological behavior of PC-ABS built prototypes. Wear resistance of FDM manufactured parts in relation to the variation of FDM process parameters was analyzed and studied using definitive screening design and analysis of variance technique. The worn surfaces of some fabricated samples were also analyzed and investigated in this study by scanning electron microscope. Genetic algorithm was applied to optimize the wear resistance and to identify the exact effect of the input parameters. The results obtained from this study would have an impact on the FDM product performance in various industrial applications. This study demonstrates how the manufacturing parameters can be understood in FDM additive manufacturing technology. By implementing a similar approach, the optimum setting of process parameters, which gives the best tribological properties, can be determined whenever a new material is used for the FDM process.

Research paper thumbnail of A brief overview of solar and wind energy in Libya: Current trends and the future development

IOP Conference Series: Materials Science and Engineering, 2018

Libya is one of the oil exporters and natural gas exporters to become one of the top lists of pri... more Libya is one of the oil exporters and natural gas exporters to become one of the top lists of primary energy sources in the world. On the other hand, Libya, like other countries in the world suffers from high energy consumption, high conventional energy prices and environment issues, combined with rapid demand growth. As a result, the Renewable Energy Authority of Libya (REAOL) has been founded to promote the development of renewable energy in Libya to increase the utilization of renewable energy from 6% to 10% by the year of 2020. This study corresponds to a revision of the current scenario of energy resources; provide future potential of renewable energy resources in Libya and implementation of the future projects for the utilization of renewable energy. This study shows that there is huge potential for renewable energy in Libya, especially solar and wind. The Libyan government will have to be more aggressive targets to promotion of renewable energy to achieve environmental sustainability in Libya.

Research paper thumbnail of Experimental investigation for dynamic stiffness and dimensional accuracy of FDM manufactured part using IV-Optimal response surface design

Rapid Prototyping Journal, 2017

Purpose Fused deposition modeling (FDM) has become an increasingly important process among the av... more Purpose Fused deposition modeling (FDM) has become an increasingly important process among the available additive manufacturing technologies in various industries. Although there are many advantages of FDM process, a downside of its industrial application is the attainable dimensional accuracy with tight tolerance without compromising the mechanical performance. This paper aims to study the effects of six FDM operating parameters on two conflicting responses, namely, dynamic stiffness and dimensional stability of FDM produced PC-ABS parts. This study also aims to determine the optimal process settings using graphical optimization that satisfy the dynamic mechanical properties without compromising the dimensional accuracy. Design/methodology/approach The regression models based upon IV-optimal response surface methodology are developed to study the variation of dimensional accuracy and dynamic mechanical properties with changes in process parameter settings. Statistical analysis was ...

Research paper thumbnail of Experimental investigation of the influence of fabrication conditions on dynamic viscoelastic properties of PC-ABS processed parts by FDM process

IOP Conference Series: Materials Science and Engineering, 2016

This paper presents optimization studies on manufacturing parameters for fused deposition modelli... more This paper presents optimization studies on manufacturing parameters for fused deposition modelling (FDM). Layer thickness, air gap, raster angle, build orientation, road width and number of contours are the process variables considered for optimization. Dynamic modulus and glass transition temperature were considered as response parameters. Experiments were designed using fractional factorial design. The effect of each process parameter was investigated using developed regression models and through analysis of variance (ANOVA) technique. The surface characteristics are studied using scanning electron microscope (SEM). Further, performance of optimum conditions was determined and validated by confirmation experiment.

Research paper thumbnail of Investigation on the Flexural Creep Stiffness Behavior of PC–ABS Material Processed by Fused Deposition Modeling Using Response Surface Definitive Screening Design

JOM, 2016

The resistance of polymeric materials to time-dependent plastic deformation is an important requi... more The resistance of polymeric materials to time-dependent plastic deformation is an important requirement of the fused deposition modeling (FDM) design process, its processed products, and their application for long-term loading, durability, and reliability. The creep performance of the material and part processed by FDM is the fundamental criterion for many applications with strict dimensional stability requirements, including medical implants, electrical and electronic products, and various automotive applications. Herein, the effect of FDM fabrication conditions on the flexural creep stiffness behavior of polycarbonate–acrylonitrile-butadiene-styrene processed parts was investigated. A relatively new class of experimental design called “definitive screening design” was adopted for this investigation. The effects of process variables on flexural creep stiffness behavior were monitored, and the best suited quadratic polynomial model with high coefficient of determination (R2) value was developed. This study highlights the value of response surface definitive screening design in optimizing properties for the products and materials, and it demonstrates its role and potential application in material processing and additive manufacturing.

Research paper thumbnail of Investigation of dynamic elastic deformation of parts processed by fused deposition modeling additive manufacturing

Advances in Production Engineering & Management, 2016

Fused deposition modeling (FDM) has been recognized as an effective technology to manufacture 3D ... more Fused deposition modeling (FDM) has been recognized as an effective technology to manufacture 3D dimensional parts directly from a digital computer aided design (CAD) model in a layer-by-layer style. Although it has become a significantly important manufacturing process, but it is still not well accepted additive manufacturing technology for load-carrying parts under dynamic and cyclic conditions due to many processing parameters affecting the part properties. The purpose of this study is to characterize the FDM manufactured parts by detecting how the individual and interactive FDM process parameters will influence the performance of manufactured products under dynamic and cyclic conditions. Experiments were conducted through fractional factorial design and artificial neural network (ANN). Effect of each parameter on the dynamic modulus of elasticity was investigated using analysis of variance (ANOVA) technique. Furthermore, optimal processing parameters were determined and validated by conducting verification experiment. The results showed that both ANN and fractional factorial models provided good quality predictions, yet the ANN showed the superiority of a properly trained ANN in capturing the nonlinear relationship of the system over fractional factorial for both data fitting and estimation capabilities.

Research paper thumbnail of Analytical Modelling and Optimization of the Temperature-Dependent Dynamic Mechanical Properties of Fused Deposition Fabricated Parts Made of PC-ABS

Materials, 2016

Fused deposition modeling (FDM) additive manufacturing has been intensively used for many industr... more Fused deposition modeling (FDM) additive manufacturing has been intensively used for many industrial applications due to its attractive advantages over traditional manufacturing processes. The process parameters used in FDM have significant influence on the part quality and its properties. This process produces the plastic part through complex mechanisms and it involves complex relationships between the manufacturing conditions and the quality of the processed part. In the present study, the influence of multi-level manufacturing parameters on the temperature-dependent dynamic mechanical properties of FDM processed parts was investigated using IV-optimality response surface methodology (RSM) and multilayer feed-forward neural networks (MFNNs). The process parameters considered for optimization and investigation are slice thickness, raster to raster air gap, deposition angle, part print direction, bead width, and number of perimeters. Storage compliance and loss compliance were considered as response variables. The effect of each process parameter was investigated using developed regression models and multiple regression analysis. The surface characteristics are studied using scanning electron microscope (SEM). Furthermore, performance of optimum conditions was determined and validated by conducting confirmation experiment. The comparison between the experimental values and the predicted values by IV-Optimal RSM and MFNN was conducted for each experimental run and results indicate that the MFNN provides better predictions than IV-Optimal RSM.

Research paper thumbnail of Experimental Investigations of Process Parameters Influence on Rheological Behavior and Dynamic Mechanical Properties of FDM Manufactured Parts

Materials and Manufacturing Processes, 2015

Fused deposition modelling (FDM) has gained popularity in industry because of its ability to manu... more Fused deposition modelling (FDM) has gained popularity in industry because of its ability to manufacture complex parts. But when it comes to the manufacturing of functional products, the advantages of FDM is not so distinct due to the high number of intervening parameters and complex optimal settings set up. This paper investigates the influence of process parameters on the rheological and dynamic mechanical properties of FDM manufactured parts. In this study, an attempt has been made to establish an empirical relationship between the FDM input parameters and the properties involved using IV-optimal response surface methodology and statistical analysis. Further, optimized process parameters were established to maximize the rheological and dynamic mechanical properties through the graphical optimization. The optimization results show that the parameters with the most significant effect on the rheological and dynamic mechanical properties are the layer thickness, the air gap, the road width and the number of contours. The results also show that by taking into consideration the number of contours, the functionality of manufactured part is improved significantly.

Research paper thumbnail of Terrestrial and Marine Microfloras of the Paleocene/Eocene Boundary Salzburg County, Austria

Research paper thumbnail of The Krappfeld Microflora, Carinthia (Austria): A Presumable ETM-2 Flora, Sem Investigation of Palynomorphs

Research paper thumbnail of Effect of Viscum album on acute hepatic damage caused by carbon tetrachloride in rats

Turkish Journal of Medical Sciences

Aim: To investigate the effect of Viscum album, a plant used for the treatment of hepatocellular ... more Aim: To investigate the effect of Viscum album, a plant used for the treatment of hepatocellular carcinoma that has immune-modulating properties, on acute hepatic injury in rats. Materials and methods: Hepatotoxicity was induced by CCl 4 orally (0.28 mL/kg). Rats received either Viscum album at 1 of 2 dose levels (0.1 or 0.2 mL/kg) once weekly subcutaneously alone or with silymarin (25 mg/kg, orally), or silymarin (25 mg/kg) once daily orally for 1 month, starting at the time of administration of CCl 4 . Liver damage was assessed by determining liver serum enzyme activities and by hepatic histopathology. Results: Viscum album administration decreased the increases in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP), and also prevented the development of hepatic necrosis caused by CCl 4 . The effect of Viscum album was dose-dependent. Viscum album administered at 0.1 or 0.2 mL/kg caused significant reduction in the elevated plasma...

Research paper thumbnail of دراسة تحليلية للأهداف المسجلة في بطولة كأس الأمم الأفريقية لكرة القدم والتي أقيمت بتونس في الفترة من 24 يناير حتى 14 فبراير 2004م

ملخص البحث دراسة تحليلية للأهداف المسجلة في بطولة كأس الأمم الأفريقية لكرة القدم والتي أقيمت بتون... more ملخص البحث دراسة تحليلية للأهداف المسجلة في بطولة كأس الأمم الأفريقية لكرة القدم والتي أقيمت بتونس في الفترة من 24 يناير حتى 14 فبراير 2004م * د . عمر أحمـد على محمد ـــــــــــــــ يهدف البحث إلى التعرف على نسبة الأهداف المسجلة من المواقف الهجومية المتحركة والثابتة في كرة القدم ، وأيضاً التعرف على نسبة الأهداف المسجلة بالقدمين والرأس ، وكذا تحديد أكثر الأماكن التي يحرز منها الأهداف ثم التعرف على نسبة التهديف في البطولة ، وقد اختار الباحث أهداف مباريات بطولة كأس الأمم الأفريقية بتونس 2004 كعينة للبحث ، وقد استخدم الباحث المنهج الوصفي ، واستخدم الباحث شرائط الفيديو المسجل عليها جميع مباريات البطولة ، واستمارات الملاحظة العلمية كأداة لجمع المادة العلمية ، وقد قام الباحث بتحليل جميع الأهداف التي سجلت في مباريات الأدوار التمهيدية والنهائية للبطولة والتي بلغت 88 ثمانية وثمانون هدفاً في 32 مباراة . ومن أهم النتائج التى توصلت إليها الدراسة أن أكثر الأهداف المسجلة كانت باستخدام المواقف الهجومية المتحركة ، وأن نسبة كبيرة من الأهداف سجلت بالقدم اليمنى ، وأن الجزء الأمامي لمنطقة الجزاء من أكثر...

Research paper thumbnail of Mathematical Modelling for Coal Fired Supercritical Power Plants and Model Parameter Identification Using Genetic Algorithms

Lecture Notes in Electrical Engineering, 2011

The paper presents the progress of our study of the whole process mathematical model for a superc... more The paper presents the progress of our study of the whole process mathematical model for a supercritical coal-fired power plant. The modelling procedure is rooted from thermodynamic and engineering principles with reference to the previously published literatures. Model unknown parameters are identified using Genetic Algorithms (GAs) with 600MW supercritical power plant on-site measurement data. The identified parameters are verified with

Research paper thumbnail of Applied Newly Developed Technology To Overcome Deepwater Completion Difficulties

Proceedings of SPE/IADC Middle East Drilling and Technology Conference, 2007

Research paper thumbnail of One-Trip Installation of 4-3/4-in Expandable Screen Assembly

SPE/IADC Middle East Drilling and Technology Conference, 2007

... An economics “untenable” gravel-pack deployment in the Mediterranean Sea required isolation a... more ... An economics “untenable” gravel-pack deployment in the Mediterranean Sea required isolation and ... With the planned expandable screen assembly successfully deployed, a circulation was broken and 1.125 ... the Liner Hanger set with only the Hanger giving some difficulty with a ...

Research paper thumbnail of High Gas-Rate Production: Expandable Solutions in the Mediterranean Sea

SPE Annual Technical Conference and Exhibition, 2008

An operator facing the need for sand control in multiple maturing fields investigated the possibi... more An operator facing the need for sand control in multiple maturing fields investigated the possibility of using expandable technologies to address their needs. Years of production and the onset of water production has affected that need. After an extensive study of rock mechanics and properties and how sand production might be initiated based on these properties, the investigation for an optimized sand control technique began. A systematic approach ensued between operator and Service Company in an attempt to define an optimized solution for sand control in each of these fields. Conventional cased hole gravel packs were excluded due to the need for a larger flow area for handling the high gas rates. Open hole gravel packing was investigated yet ruled out due the exposed unstable shales during the packing operations. Ultimately the optimized solution led to the deployment of an expandable screen system to ensure sand control for the remaining life of each well. The undesirable shales w...

Research paper thumbnail of Una estrategia de aceleración basada en submuestreo para el análisis dinámico de puentes de ferrocarril de alta velocidad

Research paper thumbnail of Nickel-titanium shape memory alloys made by selective laser melting: a review on process optimisation

Advances in Manufacturing, 2022

Research paper thumbnail of Modeling, analysis, and optimization of dimensional accuracy of FDM-fabricated parts using definitive screening design and deep learning feedforward artificial neural network

Advances in Manufacturing, 2021

Additive manufacturing (AM) technologies such as fused deposition modeling (FDM) rely on the qual... more Additive manufacturing (AM) technologies such as fused deposition modeling (FDM) rely on the quality of manufactured products and the process capability. Currently, the dimensional accuracy and stability of any AM process is essential for ensuring that customer specifications are satisfied at the highest standard, and variations are controlled without significantly affecting the functioning of processes, machines, and product structures. This study aims to investigate the effects of FDM fabrication conditions on the dimensional accuracy of cylindrical parts. In this study, a new class of experimental design techniques for integrated second-order definitive screening design (DSD) and an artificial neural network (ANN) are proposed for designing experiments to evaluate and predict the effects of six important operating variables. By determining the optimum fabrication conditions to obtain better dimensional accuracies for cylindrical parts, the time consumption and number of complex e...

Research paper thumbnail of Investigation of dimensional variation in parts manufactured by fused deposition modeling using Gauge Repeatability and Reproducibility

IOP Conference Series: Materials Science and Engineering, 2018

Research paper thumbnail of Experimental Study of the Wear Performance of Fused Deposition Modeling Printed Polycarbonate-Acrylonitrile Butadiene Styrene Parts Using Definitive Screening Design and Machine Learning-Genetic Algorithm

Journal of Materials Engineering and Performance, 2021

The purpose of this study is to investigate the influence of fused deposition modeling (FDM) proc... more The purpose of this study is to investigate the influence of fused deposition modeling (FDM) process parameters on the tribological behavior of PC-ABS built prototypes. Wear resistance of FDM manufactured parts in relation to the variation of FDM process parameters was analyzed and studied using definitive screening design and analysis of variance technique. The worn surfaces of some fabricated samples were also analyzed and investigated in this study by scanning electron microscope. Genetic algorithm was applied to optimize the wear resistance and to identify the exact effect of the input parameters. The results obtained from this study would have an impact on the FDM product performance in various industrial applications. This study demonstrates how the manufacturing parameters can be understood in FDM additive manufacturing technology. By implementing a similar approach, the optimum setting of process parameters, which gives the best tribological properties, can be determined whenever a new material is used for the FDM process.

Research paper thumbnail of A brief overview of solar and wind energy in Libya: Current trends and the future development

IOP Conference Series: Materials Science and Engineering, 2018

Libya is one of the oil exporters and natural gas exporters to become one of the top lists of pri... more Libya is one of the oil exporters and natural gas exporters to become one of the top lists of primary energy sources in the world. On the other hand, Libya, like other countries in the world suffers from high energy consumption, high conventional energy prices and environment issues, combined with rapid demand growth. As a result, the Renewable Energy Authority of Libya (REAOL) has been founded to promote the development of renewable energy in Libya to increase the utilization of renewable energy from 6% to 10% by the year of 2020. This study corresponds to a revision of the current scenario of energy resources; provide future potential of renewable energy resources in Libya and implementation of the future projects for the utilization of renewable energy. This study shows that there is huge potential for renewable energy in Libya, especially solar and wind. The Libyan government will have to be more aggressive targets to promotion of renewable energy to achieve environmental sustainability in Libya.

Research paper thumbnail of Experimental investigation for dynamic stiffness and dimensional accuracy of FDM manufactured part using IV-Optimal response surface design

Rapid Prototyping Journal, 2017

Purpose Fused deposition modeling (FDM) has become an increasingly important process among the av... more Purpose Fused deposition modeling (FDM) has become an increasingly important process among the available additive manufacturing technologies in various industries. Although there are many advantages of FDM process, a downside of its industrial application is the attainable dimensional accuracy with tight tolerance without compromising the mechanical performance. This paper aims to study the effects of six FDM operating parameters on two conflicting responses, namely, dynamic stiffness and dimensional stability of FDM produced PC-ABS parts. This study also aims to determine the optimal process settings using graphical optimization that satisfy the dynamic mechanical properties without compromising the dimensional accuracy. Design/methodology/approach The regression models based upon IV-optimal response surface methodology are developed to study the variation of dimensional accuracy and dynamic mechanical properties with changes in process parameter settings. Statistical analysis was ...

Research paper thumbnail of Experimental investigation of the influence of fabrication conditions on dynamic viscoelastic properties of PC-ABS processed parts by FDM process

IOP Conference Series: Materials Science and Engineering, 2016

This paper presents optimization studies on manufacturing parameters for fused deposition modelli... more This paper presents optimization studies on manufacturing parameters for fused deposition modelling (FDM). Layer thickness, air gap, raster angle, build orientation, road width and number of contours are the process variables considered for optimization. Dynamic modulus and glass transition temperature were considered as response parameters. Experiments were designed using fractional factorial design. The effect of each process parameter was investigated using developed regression models and through analysis of variance (ANOVA) technique. The surface characteristics are studied using scanning electron microscope (SEM). Further, performance of optimum conditions was determined and validated by confirmation experiment.

Research paper thumbnail of Investigation on the Flexural Creep Stiffness Behavior of PC–ABS Material Processed by Fused Deposition Modeling Using Response Surface Definitive Screening Design

JOM, 2016

The resistance of polymeric materials to time-dependent plastic deformation is an important requi... more The resistance of polymeric materials to time-dependent plastic deformation is an important requirement of the fused deposition modeling (FDM) design process, its processed products, and their application for long-term loading, durability, and reliability. The creep performance of the material and part processed by FDM is the fundamental criterion for many applications with strict dimensional stability requirements, including medical implants, electrical and electronic products, and various automotive applications. Herein, the effect of FDM fabrication conditions on the flexural creep stiffness behavior of polycarbonate–acrylonitrile-butadiene-styrene processed parts was investigated. A relatively new class of experimental design called “definitive screening design” was adopted for this investigation. The effects of process variables on flexural creep stiffness behavior were monitored, and the best suited quadratic polynomial model with high coefficient of determination (R2) value was developed. This study highlights the value of response surface definitive screening design in optimizing properties for the products and materials, and it demonstrates its role and potential application in material processing and additive manufacturing.

Research paper thumbnail of Investigation of dynamic elastic deformation of parts processed by fused deposition modeling additive manufacturing

Advances in Production Engineering & Management, 2016

Fused deposition modeling (FDM) has been recognized as an effective technology to manufacture 3D ... more Fused deposition modeling (FDM) has been recognized as an effective technology to manufacture 3D dimensional parts directly from a digital computer aided design (CAD) model in a layer-by-layer style. Although it has become a significantly important manufacturing process, but it is still not well accepted additive manufacturing technology for load-carrying parts under dynamic and cyclic conditions due to many processing parameters affecting the part properties. The purpose of this study is to characterize the FDM manufactured parts by detecting how the individual and interactive FDM process parameters will influence the performance of manufactured products under dynamic and cyclic conditions. Experiments were conducted through fractional factorial design and artificial neural network (ANN). Effect of each parameter on the dynamic modulus of elasticity was investigated using analysis of variance (ANOVA) technique. Furthermore, optimal processing parameters were determined and validated by conducting verification experiment. The results showed that both ANN and fractional factorial models provided good quality predictions, yet the ANN showed the superiority of a properly trained ANN in capturing the nonlinear relationship of the system over fractional factorial for both data fitting and estimation capabilities.

Research paper thumbnail of Analytical Modelling and Optimization of the Temperature-Dependent Dynamic Mechanical Properties of Fused Deposition Fabricated Parts Made of PC-ABS

Materials, 2016

Fused deposition modeling (FDM) additive manufacturing has been intensively used for many industr... more Fused deposition modeling (FDM) additive manufacturing has been intensively used for many industrial applications due to its attractive advantages over traditional manufacturing processes. The process parameters used in FDM have significant influence on the part quality and its properties. This process produces the plastic part through complex mechanisms and it involves complex relationships between the manufacturing conditions and the quality of the processed part. In the present study, the influence of multi-level manufacturing parameters on the temperature-dependent dynamic mechanical properties of FDM processed parts was investigated using IV-optimality response surface methodology (RSM) and multilayer feed-forward neural networks (MFNNs). The process parameters considered for optimization and investigation are slice thickness, raster to raster air gap, deposition angle, part print direction, bead width, and number of perimeters. Storage compliance and loss compliance were considered as response variables. The effect of each process parameter was investigated using developed regression models and multiple regression analysis. The surface characteristics are studied using scanning electron microscope (SEM). Furthermore, performance of optimum conditions was determined and validated by conducting confirmation experiment. The comparison between the experimental values and the predicted values by IV-Optimal RSM and MFNN was conducted for each experimental run and results indicate that the MFNN provides better predictions than IV-Optimal RSM.

Research paper thumbnail of Experimental Investigations of Process Parameters Influence on Rheological Behavior and Dynamic Mechanical Properties of FDM Manufactured Parts

Materials and Manufacturing Processes, 2015

Fused deposition modelling (FDM) has gained popularity in industry because of its ability to manu... more Fused deposition modelling (FDM) has gained popularity in industry because of its ability to manufacture complex parts. But when it comes to the manufacturing of functional products, the advantages of FDM is not so distinct due to the high number of intervening parameters and complex optimal settings set up. This paper investigates the influence of process parameters on the rheological and dynamic mechanical properties of FDM manufactured parts. In this study, an attempt has been made to establish an empirical relationship between the FDM input parameters and the properties involved using IV-optimal response surface methodology and statistical analysis. Further, optimized process parameters were established to maximize the rheological and dynamic mechanical properties through the graphical optimization. The optimization results show that the parameters with the most significant effect on the rheological and dynamic mechanical properties are the layer thickness, the air gap, the road width and the number of contours. The results also show that by taking into consideration the number of contours, the functionality of manufactured part is improved significantly.

Research paper thumbnail of Terrestrial and Marine Microfloras of the Paleocene/Eocene Boundary Salzburg County, Austria

Research paper thumbnail of The Krappfeld Microflora, Carinthia (Austria): A Presumable ETM-2 Flora, Sem Investigation of Palynomorphs

Research paper thumbnail of Effect of Viscum album on acute hepatic damage caused by carbon tetrachloride in rats

Turkish Journal of Medical Sciences

Aim: To investigate the effect of Viscum album, a plant used for the treatment of hepatocellular ... more Aim: To investigate the effect of Viscum album, a plant used for the treatment of hepatocellular carcinoma that has immune-modulating properties, on acute hepatic injury in rats. Materials and methods: Hepatotoxicity was induced by CCl 4 orally (0.28 mL/kg). Rats received either Viscum album at 1 of 2 dose levels (0.1 or 0.2 mL/kg) once weekly subcutaneously alone or with silymarin (25 mg/kg, orally), or silymarin (25 mg/kg) once daily orally for 1 month, starting at the time of administration of CCl 4 . Liver damage was assessed by determining liver serum enzyme activities and by hepatic histopathology. Results: Viscum album administration decreased the increases in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP), and also prevented the development of hepatic necrosis caused by CCl 4 . The effect of Viscum album was dose-dependent. Viscum album administered at 0.1 or 0.2 mL/kg caused significant reduction in the elevated plasma...

Research paper thumbnail of دراسة تحليلية للأهداف المسجلة في بطولة كأس الأمم الأفريقية لكرة القدم والتي أقيمت بتونس في الفترة من 24 يناير حتى 14 فبراير 2004م

ملخص البحث دراسة تحليلية للأهداف المسجلة في بطولة كأس الأمم الأفريقية لكرة القدم والتي أقيمت بتون... more ملخص البحث دراسة تحليلية للأهداف المسجلة في بطولة كأس الأمم الأفريقية لكرة القدم والتي أقيمت بتونس في الفترة من 24 يناير حتى 14 فبراير 2004م * د . عمر أحمـد على محمد ـــــــــــــــ يهدف البحث إلى التعرف على نسبة الأهداف المسجلة من المواقف الهجومية المتحركة والثابتة في كرة القدم ، وأيضاً التعرف على نسبة الأهداف المسجلة بالقدمين والرأس ، وكذا تحديد أكثر الأماكن التي يحرز منها الأهداف ثم التعرف على نسبة التهديف في البطولة ، وقد اختار الباحث أهداف مباريات بطولة كأس الأمم الأفريقية بتونس 2004 كعينة للبحث ، وقد استخدم الباحث المنهج الوصفي ، واستخدم الباحث شرائط الفيديو المسجل عليها جميع مباريات البطولة ، واستمارات الملاحظة العلمية كأداة لجمع المادة العلمية ، وقد قام الباحث بتحليل جميع الأهداف التي سجلت في مباريات الأدوار التمهيدية والنهائية للبطولة والتي بلغت 88 ثمانية وثمانون هدفاً في 32 مباراة . ومن أهم النتائج التى توصلت إليها الدراسة أن أكثر الأهداف المسجلة كانت باستخدام المواقف الهجومية المتحركة ، وأن نسبة كبيرة من الأهداف سجلت بالقدم اليمنى ، وأن الجزء الأمامي لمنطقة الجزاء من أكثر...

Research paper thumbnail of Mathematical Modelling for Coal Fired Supercritical Power Plants and Model Parameter Identification Using Genetic Algorithms

Lecture Notes in Electrical Engineering, 2011

The paper presents the progress of our study of the whole process mathematical model for a superc... more The paper presents the progress of our study of the whole process mathematical model for a supercritical coal-fired power plant. The modelling procedure is rooted from thermodynamic and engineering principles with reference to the previously published literatures. Model unknown parameters are identified using Genetic Algorithms (GAs) with 600MW supercritical power plant on-site measurement data. The identified parameters are verified with