Najmeddin Arab - Academia.edu (original) (raw)
Papers by Najmeddin Arab
British Journal of Surgery, 2021
To support the global restart of elective surgery, data from an international prospective cohort ... more To support the global restart of elective surgery, data from an international prospective cohort study of 8492 patients (69 countries) was analysed using artificial intelligence (machine learning techniques) to develop a predictive score for mortality in surgical patients with SARS-CoV-2. We found that patient rather than operation factors were the best predictors and used these to create the COVIDsurg Mortality Score (https://covidsurgrisk.app). Our data demonstrates that it is safe to restart a wide range of surgical services for selected patients.
L’Orientation scolaire et professionnelle, 2005
Archives of Foundry Engineering, 2017
Cast irons are good examples of materials which are more sensitive to chemical composition and pr... more Cast irons are good examples of materials which are more sensitive to chemical composition and production conditions. In this research to improve casting quality, solidification and nucleation process in grey cast iron was investigate. In particular, attempts have been made to rationalize variation in eutectic cells with nucleation sites and eutectic solidification undercooling. Four castings with different diameter and similar chemical composition and pouring temperature and different inoculant percentage was casted. The cooling curve and maximum and minimum undercooling for each castings was measured. Also optical metallography and image analyzer has been used to determine the average eutectic cells diameter, and linear and surface densities, and volume density was calculated. The results of this research show a competitive behavior between nucleation sites and eutectic undercooling. Higher nucleation sites and higher eutectic undercooling cause higher eutectic cell density. But i...
Karaman/TMS, 2015
Grain Refinement process is an important stage in production of aluminum castings. There is commo... more Grain Refinement process is an important stage in production of aluminum castings. There is common question for all producer of aluminum castings that how they can be sure about the quality of nucleation. Thermal analysis is an important tool to answer this question. In this research, different types of inoculants were used to investigation of nucleation in A356 aluminum alloy. The cooling curve of each sample was recorded and by using a special computer program, the first derivative was calculated. By calculating zero curve and analyzing the cooling curve, it is possible to predict the quality of nucleation and calculation fraction of solids, latent heat and other information. The result of this research have shown that if maximum undercooling of nucleation was approximately 4 C, the quality of nucleation process will be more reliable.
Journal of Applied Chemical Research, 2009
Introduction In industrial applications, parts with diverse properties are used to compliance the... more Introduction In industrial applications, parts with diverse properties are used to compliance the needs. Among different kinds of metals coatings, conversion coatings can be called divided in two groups: natural and chemical conversion coatings. Natural conversion coatings called oxide coatings are naturally formed on metal substrates, while chemical conversion coatings are oxide coatings that are artificially formed on metal substrates by means of proper chemical bathes. From different kinds of chemical conversion coatings, oxalate, phosphate, chromate and oxide conversion coatings, can be nemed.
international journal of advanced design and manufacturing technology, 2014
There are mainly two methods of deep drawing analysis; experimental and analytical/numerical. Exp... more There are mainly two methods of deep drawing analysis; experimental and analytical/numerical. Experimental analysis can be useful in analyzing the process to determine the process parameters that produce a defect free product, and the analytical/numerical modeling can be used to model and analyze the process through all stages of deformation. This approach is less time consuming and more economical. Sheet metal forming often includes biaxial in-plane deformation with non-proportional strain paths. In deep drawing of cylindrical cup, the deformation in the flange in dominated by pure shear deformation, while it changes to plane strain when the material is drawn into the die. This paper deals with the analysis of deep drawing of circular blanks into axi-symmetric cylindrical cup using numerical modeling. The blank drawability has been related both theoretically and experimentally with the initial diameter of the blank and deep drawing parameters. The strains in the radial and circumf...
Improvement of the mechanical properties and micros tructures of industrial parts can improve wor... more Improvement of the mechanical properties and micros tructures of industrial parts can improve working c onditions, working life and reduce rejection rates and consequent, imp rove environmental effects of industrial developmen ts. In this paper, the effect of Boron content in chemical composition ofM anganese steel on improvement of microstructure and mechanical properties of manganese steels has been investigate d. This improvement can reduce the consumption and rejection rate of castings and consequent environmental protection. T he microstructure was investigated using optical, S EM and FESEM microscopy. In addition, mechanical tests such as t en ile test, hardness and impact tests were perform ed on the samples. Microscopic investigations showed the presence of 0 .007% Boron prevents of formation carbides in grain boundaries and also reduces the carbide sizes and cause uniform di stribution. In the presence of Boron, annealing sol uti n heat treatment, improve the morphology of ...
International Journal of Mechanical and Materials Engineering, 2010
A majority of modern electronic and optical devices makes use of the physical properties of singl... more A majority of modern electronic and optical devices makes use of the physical properties of single crystals. Such crystals may be organic, inorganic or semimetallic ,in nature, and they are usually prepared by synthetic methods. When possible the growth of a material from its own melt is the most convenient way of producing single crystals, two of the most widely used techniques for melt growth being the Bagdasarov, Bridgman-Stockbarger and the Czochralski methods. Common to these and to other methods is a container or crucible to hold the molten material. Clearly a useful crucible material must be chemically compatible with the particular substance to be contained. Molybdenum container is a suitable facility to growth single crystals, because its refractory property and chemical stability, but it is a hardly deformed material which its production require special techniques and technology. In this paper, deep drawing process technology for production boat shape molybdenum container ...
Journal of Solid Mechanics, 2014
There are mainly two methods of deep drawing analysis; experimental and analytical/numerical. Exp... more There are mainly two methods of deep drawing analysis; experimental and analytical/numerical. Experimental analysis can be useful in analyzing the process to determine the process parameters that produce a defect free product, and the analytical/numerical modeling can be used to model and analyze the process through all stages of deformation. This approach is less time consuming and more economical. Sheet metal forming often includes biaxial in-plane deformation with non-proportional strain paths. In deep drawing of cylindrical cup, the deformation in the flange in dominated by pure shear deformation, while it changes to plane strain when the material is drawn into the die. This paper deals with the analysis of deep drawing of circular blanks into axisymmetric cylindrical cup using numerical modeling. The blank drawability has been related both theoretically and experimentally with the initial diameter of the blank and deep drawing parameters. The strains in the radial and circumfer...
The use of aluminum in automotive industry is expanding. Aluminum offers a lower weight alternati... more The use of aluminum in automotive industry is expanding. Aluminum offers a lower weight alternative to steel, potentially increasing the efficiency of vehicles. However, the application of aluminum has been only in select areas of use, most notably cast aluminum in the engine, transmission, and wheels. Other areas offer the potential for growth that could significantly expand the amount of aluminum used in vehicles. Cost is the main barrier to increased aluminum use. Related to cos aluminum production technologies that are not yet advanced enough to produce aluminum components at low enough price points for aluminum to compete with traditional automotive materials. The amount of aluminum used in cars and light trucks is growing steadily. However, without new developments in aluminum recycling technologies, sheet from automotive aluminum could eventually flood all current markets for recycled aluminum. Environment-friendly production of automobiles is an important research subject fo...
Rolling is a common method for production of metallic parts in various shapes and sizes. In this ... more Rolling is a common method for production of metallic parts in various shapes and sizes. In this method, the raw material placed between two rigid rolls until take the shape and size. There are two rolling methods, hot rolling and cold rolling. To achieve higher mechanical properties, and better surface quality and dimensional accuracy, the hot rolled sheets undergo the cold rolling process. The friction between the metal and rolls affects the forming process, increase the required load for forming, reduce the surface quality and increase the wear of tools. The simulation of rolling process will be helpful to improve the forming procedure and quality of products. In this research, the Finite Element method is used to model, simulate and analysis the rolling process of St 37 steel sheets in sticky friction plane strain conditions. Because of stress strain behavior of material during the forming process and increase of frictional stress due to forming process, the analysis of forming ...
The use of aluminum in automotive industry is expanding. Aluminum offers a lower weight alternati... more The use of aluminum in automotive industry is expanding. Aluminum offers a lower weight alternative to steel, potentially increasing the efficiency of vehicles. However, the application of aluminum has been only in select areas of use, most notably cast aluminum in the engine, transmission, and wheels. Other areas offer the potential for growth that could significantly expand the amount of aluminum used in vehicles. Cost is the main barrier to increased aluminum use. Related to cos aluminum production technologies that are not yet advanced enough to produce aluminum components at low enough price points for aluminum to compete with traditional automotive materials. The amount of aluminum used in cars and light trucks is growing steadily. However, without new developments in aluminum recycling technologies, sheet from automotive aluminum could eventually flood all current markets for recycled aluminum. Environment-friendly production of automobiles is an important research subject fo...
Majlesi Journal of …, 2010
Page 1. ﻪﻧاﻮﺟ عﻮﻧ ﺮﻴﺛﺎﺗ ﻲﺳرﺮﺑ ژﺎﻴﻟآ دﺎﻤﺠﻧا يﺎﻫﺮﺘﻣارﺎﭘ و ﻲﮕﻧادﺰﻳر ﺮﺑ از A356 ﻲﻨﺤﻨﻣ ﻲﺗراﺮﺣ ﺰﻴﻟﺎﻧآ ﻚ... more Page 1. ﻪﻧاﻮﺟ عﻮﻧ ﺮﻴﺛﺎﺗ ﻲﺳرﺮﺑ ژﺎﻴﻟآ دﺎﻤﺠﻧا يﺎﻫﺮﺘﻣارﺎﭘ و ﻲﮕﻧادﺰﻳر ﺮﺑ از A356 ﻲﻨﺤﻨﻣ ﻲﺗراﺮﺣ ﺰﻴﻟﺎﻧآ ﻚﻤﻛ ﻪﺑ نﺪﺷ دﺮﺳ يﺎﻫ بﺮﻋ ﻦﻳﺪﻟا ﻢﺠﻧ 1 ، ﻲﺒﻴﺒﺣ رﺪﻔﺻ 2 ، ﺪﻨﻣدﻮﺳ يﺪﻬﻣ 3 ، ﻲﻔﻳﺮﺷ ﺪﻤﺣا 1 1-،ﺪﺷرا سﺎﻨﺷرﺎﻛ هوﺎﺳ ﺪﺣاو ﻲﻣﻼﺳا دازآ هﺎﮕﺸﻧاد 2-،رﺎﻳدﺎﺘﺳا ناﺪﻤﻫ ﺎﻨﻴﺳ ﻲﻠﻋﻮﺑ هﺎﮕﺸﻧاد 3-ا ،رﺎﻳدﺎﺘﺳ ﻪﻴﻣورا رﻮﻧ مﺎﻴﭘ هﺎﮕﺸﻧاد Najmeddin Arab@yahoo.com هﺪﻴﻜﭼ ...
British Journal of Surgery, 2021
To support the global restart of elective surgery, data from an international prospective cohort ... more To support the global restart of elective surgery, data from an international prospective cohort study of 8492 patients (69 countries) was analysed using artificial intelligence (machine learning techniques) to develop a predictive score for mortality in surgical patients with SARS-CoV-2. We found that patient rather than operation factors were the best predictors and used these to create the COVIDsurg Mortality Score (https://covidsurgrisk.app). Our data demonstrates that it is safe to restart a wide range of surgical services for selected patients.
L’Orientation scolaire et professionnelle, 2005
Archives of Foundry Engineering, 2017
Cast irons are good examples of materials which are more sensitive to chemical composition and pr... more Cast irons are good examples of materials which are more sensitive to chemical composition and production conditions. In this research to improve casting quality, solidification and nucleation process in grey cast iron was investigate. In particular, attempts have been made to rationalize variation in eutectic cells with nucleation sites and eutectic solidification undercooling. Four castings with different diameter and similar chemical composition and pouring temperature and different inoculant percentage was casted. The cooling curve and maximum and minimum undercooling for each castings was measured. Also optical metallography and image analyzer has been used to determine the average eutectic cells diameter, and linear and surface densities, and volume density was calculated. The results of this research show a competitive behavior between nucleation sites and eutectic undercooling. Higher nucleation sites and higher eutectic undercooling cause higher eutectic cell density. But i...
Karaman/TMS, 2015
Grain Refinement process is an important stage in production of aluminum castings. There is commo... more Grain Refinement process is an important stage in production of aluminum castings. There is common question for all producer of aluminum castings that how they can be sure about the quality of nucleation. Thermal analysis is an important tool to answer this question. In this research, different types of inoculants were used to investigation of nucleation in A356 aluminum alloy. The cooling curve of each sample was recorded and by using a special computer program, the first derivative was calculated. By calculating zero curve and analyzing the cooling curve, it is possible to predict the quality of nucleation and calculation fraction of solids, latent heat and other information. The result of this research have shown that if maximum undercooling of nucleation was approximately 4 C, the quality of nucleation process will be more reliable.
Journal of Applied Chemical Research, 2009
Introduction In industrial applications, parts with diverse properties are used to compliance the... more Introduction In industrial applications, parts with diverse properties are used to compliance the needs. Among different kinds of metals coatings, conversion coatings can be called divided in two groups: natural and chemical conversion coatings. Natural conversion coatings called oxide coatings are naturally formed on metal substrates, while chemical conversion coatings are oxide coatings that are artificially formed on metal substrates by means of proper chemical bathes. From different kinds of chemical conversion coatings, oxalate, phosphate, chromate and oxide conversion coatings, can be nemed.
international journal of advanced design and manufacturing technology, 2014
There are mainly two methods of deep drawing analysis; experimental and analytical/numerical. Exp... more There are mainly two methods of deep drawing analysis; experimental and analytical/numerical. Experimental analysis can be useful in analyzing the process to determine the process parameters that produce a defect free product, and the analytical/numerical modeling can be used to model and analyze the process through all stages of deformation. This approach is less time consuming and more economical. Sheet metal forming often includes biaxial in-plane deformation with non-proportional strain paths. In deep drawing of cylindrical cup, the deformation in the flange in dominated by pure shear deformation, while it changes to plane strain when the material is drawn into the die. This paper deals with the analysis of deep drawing of circular blanks into axi-symmetric cylindrical cup using numerical modeling. The blank drawability has been related both theoretically and experimentally with the initial diameter of the blank and deep drawing parameters. The strains in the radial and circumf...
Improvement of the mechanical properties and micros tructures of industrial parts can improve wor... more Improvement of the mechanical properties and micros tructures of industrial parts can improve working c onditions, working life and reduce rejection rates and consequent, imp rove environmental effects of industrial developmen ts. In this paper, the effect of Boron content in chemical composition ofM anganese steel on improvement of microstructure and mechanical properties of manganese steels has been investigate d. This improvement can reduce the consumption and rejection rate of castings and consequent environmental protection. T he microstructure was investigated using optical, S EM and FESEM microscopy. In addition, mechanical tests such as t en ile test, hardness and impact tests were perform ed on the samples. Microscopic investigations showed the presence of 0 .007% Boron prevents of formation carbides in grain boundaries and also reduces the carbide sizes and cause uniform di stribution. In the presence of Boron, annealing sol uti n heat treatment, improve the morphology of ...
International Journal of Mechanical and Materials Engineering, 2010
A majority of modern electronic and optical devices makes use of the physical properties of singl... more A majority of modern electronic and optical devices makes use of the physical properties of single crystals. Such crystals may be organic, inorganic or semimetallic ,in nature, and they are usually prepared by synthetic methods. When possible the growth of a material from its own melt is the most convenient way of producing single crystals, two of the most widely used techniques for melt growth being the Bagdasarov, Bridgman-Stockbarger and the Czochralski methods. Common to these and to other methods is a container or crucible to hold the molten material. Clearly a useful crucible material must be chemically compatible with the particular substance to be contained. Molybdenum container is a suitable facility to growth single crystals, because its refractory property and chemical stability, but it is a hardly deformed material which its production require special techniques and technology. In this paper, deep drawing process technology for production boat shape molybdenum container ...
Journal of Solid Mechanics, 2014
There are mainly two methods of deep drawing analysis; experimental and analytical/numerical. Exp... more There are mainly two methods of deep drawing analysis; experimental and analytical/numerical. Experimental analysis can be useful in analyzing the process to determine the process parameters that produce a defect free product, and the analytical/numerical modeling can be used to model and analyze the process through all stages of deformation. This approach is less time consuming and more economical. Sheet metal forming often includes biaxial in-plane deformation with non-proportional strain paths. In deep drawing of cylindrical cup, the deformation in the flange in dominated by pure shear deformation, while it changes to plane strain when the material is drawn into the die. This paper deals with the analysis of deep drawing of circular blanks into axisymmetric cylindrical cup using numerical modeling. The blank drawability has been related both theoretically and experimentally with the initial diameter of the blank and deep drawing parameters. The strains in the radial and circumfer...
The use of aluminum in automotive industry is expanding. Aluminum offers a lower weight alternati... more The use of aluminum in automotive industry is expanding. Aluminum offers a lower weight alternative to steel, potentially increasing the efficiency of vehicles. However, the application of aluminum has been only in select areas of use, most notably cast aluminum in the engine, transmission, and wheels. Other areas offer the potential for growth that could significantly expand the amount of aluminum used in vehicles. Cost is the main barrier to increased aluminum use. Related to cos aluminum production technologies that are not yet advanced enough to produce aluminum components at low enough price points for aluminum to compete with traditional automotive materials. The amount of aluminum used in cars and light trucks is growing steadily. However, without new developments in aluminum recycling technologies, sheet from automotive aluminum could eventually flood all current markets for recycled aluminum. Environment-friendly production of automobiles is an important research subject fo...
Rolling is a common method for production of metallic parts in various shapes and sizes. In this ... more Rolling is a common method for production of metallic parts in various shapes and sizes. In this method, the raw material placed between two rigid rolls until take the shape and size. There are two rolling methods, hot rolling and cold rolling. To achieve higher mechanical properties, and better surface quality and dimensional accuracy, the hot rolled sheets undergo the cold rolling process. The friction between the metal and rolls affects the forming process, increase the required load for forming, reduce the surface quality and increase the wear of tools. The simulation of rolling process will be helpful to improve the forming procedure and quality of products. In this research, the Finite Element method is used to model, simulate and analysis the rolling process of St 37 steel sheets in sticky friction plane strain conditions. Because of stress strain behavior of material during the forming process and increase of frictional stress due to forming process, the analysis of forming ...
The use of aluminum in automotive industry is expanding. Aluminum offers a lower weight alternati... more The use of aluminum in automotive industry is expanding. Aluminum offers a lower weight alternative to steel, potentially increasing the efficiency of vehicles. However, the application of aluminum has been only in select areas of use, most notably cast aluminum in the engine, transmission, and wheels. Other areas offer the potential for growth that could significantly expand the amount of aluminum used in vehicles. Cost is the main barrier to increased aluminum use. Related to cos aluminum production technologies that are not yet advanced enough to produce aluminum components at low enough price points for aluminum to compete with traditional automotive materials. The amount of aluminum used in cars and light trucks is growing steadily. However, without new developments in aluminum recycling technologies, sheet from automotive aluminum could eventually flood all current markets for recycled aluminum. Environment-friendly production of automobiles is an important research subject fo...
Majlesi Journal of …, 2010
Page 1. ﻪﻧاﻮﺟ عﻮﻧ ﺮﻴﺛﺎﺗ ﻲﺳرﺮﺑ ژﺎﻴﻟآ دﺎﻤﺠﻧا يﺎﻫﺮﺘﻣارﺎﭘ و ﻲﮕﻧادﺰﻳر ﺮﺑ از A356 ﻲﻨﺤﻨﻣ ﻲﺗراﺮﺣ ﺰﻴﻟﺎﻧآ ﻚ... more Page 1. ﻪﻧاﻮﺟ عﻮﻧ ﺮﻴﺛﺎﺗ ﻲﺳرﺮﺑ ژﺎﻴﻟآ دﺎﻤﺠﻧا يﺎﻫﺮﺘﻣارﺎﭘ و ﻲﮕﻧادﺰﻳر ﺮﺑ از A356 ﻲﻨﺤﻨﻣ ﻲﺗراﺮﺣ ﺰﻴﻟﺎﻧآ ﻚﻤﻛ ﻪﺑ نﺪﺷ دﺮﺳ يﺎﻫ بﺮﻋ ﻦﻳﺪﻟا ﻢﺠﻧ 1 ، ﻲﺒﻴﺒﺣ رﺪﻔﺻ 2 ، ﺪﻨﻣدﻮﺳ يﺪﻬﻣ 3 ، ﻲﻔﻳﺮﺷ ﺪﻤﺣا 1 1-،ﺪﺷرا سﺎﻨﺷرﺎﻛ هوﺎﺳ ﺪﺣاو ﻲﻣﻼﺳا دازآ هﺎﮕﺸﻧاد 2-،رﺎﻳدﺎﺘﺳا ناﺪﻤﻫ ﺎﻨﻴﺳ ﻲﻠﻋﻮﺑ هﺎﮕﺸﻧاد 3-ا ،رﺎﻳدﺎﺘﺳ ﻪﻴﻣورا رﻮﻧ مﺎﻴﭘ هﺎﮕﺸﻧاد Najmeddin Arab@yahoo.com هﺪﻴﻜﭼ ...