The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Milford A. Hanna - One of the best experts on this subject based on the ideXlab platform.
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Functional properties of extruded foam composites of starch acetate and corn cob fiber
Industrial Crops and Products, 2004Co-Authors: Junjie Guan, Milford A. HannaAbstract:Abstract With increasing concerns about environmental protection and garbage handling, natural renewable materials such as starch, cellulose and other natural fibers become more and more popular in packaging materials manufacturing. In this study, physical and mechanical properties of extruded foam composites, prepared from starch acetate and cellulose/corn cob, were evaluated. A split-plot experimental design was used to compare selected functional properties of foams produced from starch acetate blended with ground corncobs, compared to blending with cellulose, and with different ethanol contents. Extrusions were conducted in a twin-screw extruder with 160 °C barrel temperature and 225 rpm screw speed. Physical properties of extrudates were measured including Radial Expansion ratio, unit density, bulk density, and water absorption index. Mechanical properties including unit spring index, bulk spring index, and compression strength were measured. Scanning electron microscopy was used to compare the macromolecular structures of the two types of starch acetate blends. Blending with corncobs significantly hindered Radial Expansion of starch acetate foams, whereas cellulose did not affect Expansion significantly. Higher compression strength was obtained with higher corncob content. Although ethanol penetration assisted in the formation of a starch acetate–fiber matrix, corncob blends produced inferior linkages and cell development in the foams than foams produced with cellulose blends.
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physical and functional properties of twin screw extruded whey protein concentrate corn starch blends
Lwt - Food Science and Technology, 1997Co-Authors: Francois P Matthey, Milford A. HannaAbstract:Abstract Use as a minor component in corn starch extrudates may provide an outlet for underutilized whey protein concentrate (WPC). Several physico-chemical and functional properties of corn starch–WPC extrudates were determined in this study. This information can be used for process scaling-up purposes and for tailoring such extrudates to specific applications. Blends of whey protein concentrate and corn starch were extrusion-cooked with a co-rotating intermeshing twin-screw extruder at 220 g/kg moisture content, 140 rpm screw speed and 140 °C barrel temperature. A split-plot experiment was conducted to investigate four levels of amylose in starch (main plots) with four levels of WPC in WPC–corn starch blends (sub-plots). The design was a randomized complete block with the three replications being three different WPC sources. Studied ranges were 0, 250, 500 and 700 g/kg for amylose and 0, 100, 200 and 300 g/kg for WPC. Measured properties were shear strength (51.4 to 361 kPa), Radial Expansion ratio (4.32 to 13.1), specific mechanical energy (SME) (240 to 383 J/kg), water absorption index (WAI) (1.98 to 8.57), % water solubility index (% WSI) (9.51 to 67.6%), total color difference (8.08 to 35.9) and % apparent amylose content (0–66%) of extrudates. The WPC source affected several extrudate properties. Data were modeled with polynomial regression. Waxy starch differed from amylose starches in terms of % WSI, WAI, and SME. Significant interactions between levels of amylose and WPC were found for Radial Expansion ratio, total color change and apparent amylose content. This suggested the presence of a physico-chemical interaction between amylose and WPC.
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Expansion characteristics of extruded corn grits
Lwt - Food Science and Technology, 1996Co-Authors: Yusuf Ali, Milford A. Hanna, Rangaswami ChinnaswamyAbstract:Abstract Yellow corn grits with 180 g/kg moisture content (dry basis) were extrusion cooked in a Brabender single-screw laboratory scale extruder with various combinations of barrel temperature (100–200 °C) and screw speed (80–200 rpm). Bulk densities, solid densities, Expansion properties, and total, open and closed pore volumes were determined. Extrudate bulk density, measured by glass bead displacement, was highly correlated with the bulk density based on the actual dimensions of the extrudates. Overall and Radial Expansion increased with temperature and screw speed whereas axial Expansion decreased. Axial Expansion was affected mostly by surging. The pore volumes had an increasing trend with temperature and screw speed.
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screw configuration effects on corn starch Expansion during extrusion
Journal of Food Science, 1994Co-Authors: Avtar S Sokhey, Anantha N R Kollengode, Milford A. HannaAbstract:Normal corn starch was extrusion cooked in a Brabender single-screw extruder. Three screws with no mixing, one mixing or two mixing elements were used to extrude the samples through a 3 mm cylindrical die nozzle at 140°C barrel temperature and 140 rpm screw speed. Dependent variables included overall and Radial Expansion ratios, bulk density and specific mechanical energy (SME). Extrudates were ground and re-extruded using the same three screws, and the same extrusion conditions. Significant differences (P < 0.05) in bulk density, SME and Radial Expansion ratio were found on re-extrusion. No changes occurred in overall Expansion ratio (P < 0.05).
Tasneem Pervez - One of the best experts on this subject based on the ideXlab platform.
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microstructure evolution of ultra fine grain low carbon steel tubular undergoing Radial Expansion process
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Omar S Alabri, Tasneem Pervez, Majid Almaharbi, Rashid KhanAbstract:Abstract Tubular Expansion is a cold metal forming process where diameteral change is achieved by propagating a conical mandrel through the tubular either by mechanical pull or hydraulic push. Cold metal forming alters post-Expansion mechanical and microstructural properties of tubular material, which may lead to premature failure during operation. In order to prevent tubular from failure, its post-Expansion material and mechanical properties must be investigated thoroughly. Initial grains morphology, distribution of phases, and subsequent variation in material and mechanical properties due to Expansion process of low-carbon LSX-80 steel tubular are investigated in the current study. The observed microstructure is typical of high strength steels with a mixture of carbon-poor and carbon-rich regions. A noticeable volume fraction of martensite phase was also observed. Presence of smaller grains in the material is a clear indication of the application of grain refinement mechanism to improve strength and toughness. Microhardness and Charpy impact tests were done on unexpanded and expanded sections of tubular in order to determine their mechanical properties. In addition, fractographic analysis was accomplished and obtained results showed that the morphology of the fractured surface was nearly alike at the macroscopic scale throughout the range of Expansion ratios considered in this study. However, at the fine microscopic scale, the fractured surface was mostly ductile at low Expansion ratio, while it was mainly brittle at large Expansion ratio. Hence, an Expansion ratio in the vicinity of 15% is highly recommended for the current tubular material in order to have adequate safe margin for down-hole application. An alternative material has to be selected and/or developed in order to realize the goal of achieving higher Expansion ratio (≥30%) while preserving the tubular structural integrity after Expansion.
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structural behavior of solid expandable tubular undergoes Radial Expansion process analytical numerical and experimental approaches
International Journal of Solids and Structures, 2013Co-Authors: Omar S Alabri, Tasneem PervezAbstract:Abstract Today’s structures have to meet increasingly rigorous requirements during operation. The economic and human costs of failure during service impose a great responsibility on organizations and individuals who develop new products as well as those who select/integrate products in a final engineering design. A crucial aspect for successful product development and/or inclusion is the careful selection of the best material(s), derived from an informed awareness of the capabilities and opportunities afforded by all candidate materials, together with a design that takes full benefit of those competencies. Thick-wall tubular is an example where all these issues are playing a major role in deciding their industrial applications. Given for their desirable features of high strength and geometrical shape, they are widely used in aerospace, marine, military, automotive, oil and gas, and many other fields. This paper focuses on developing analytical solution to investigate the structural response of thick-wall tubulars undergo plastic deformation due to expanding them using a rigid mandrel of conical shape. Volume incompressible condition together with the Levy–Mises flow rule were used to develop the equations which relate the Expansion ratio of the tubular to the length and thickness variations. Besides, Tresca’s yield criterion was used to include the plastic behavior of the tubular material. Further to this, a numerical model of the tubular Expansion process was also developed using the commercial finite element software ABAQUS. Experiments of tubular Expansion have been conducted using a full-scale test-rig in the Engineering Research Laboratory at Sultan Qaboos University to validate the analytical and numerical solutions. The developed analytical and numerical models are capable of predicting the stress field in the Expansion zone, the force required for Expansion, as well as the length and thickness variations induced in the tubular due to the Expansion process. Comparison between analytical, experimental, and simulation results showed that a good agreement has been attained for various parameters.
Jian X - One of the best experts on this subject based on the ideXlab platform.
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laser spark ignition and combustion characteristics of methane air mixtures
Combustion and Flame, 1998Co-Authors: Jian X, Dennis R Alexander, Dana E PoulainAbstract:Ignition breakdown kernels of methane-air mixtures initiated by laser-induced sparks and by conventional electric sparks arc compared during initial stages. Experiments were conducted using a four-stroke (Otto-cycle) single-cylinder typical high-pressure combustion chamber. The piston is cycled in the cylinder by using an electric motor driven hydraulic ram. An cxcimer laser beam, either produced from krypton fluoride gas (λ = 248 nm) or argon fluoride gas (λ = 193 nm), or a Nd:YAG laser beam (λ = 1064 nm) is focused into a combustion chamber to initiate ignition. Conventional electric spark ignition is used as a basis for comparison between the two different ignition methods and the resultant early breakdown kernel characteristics. A streak camera is used to investigate and record the initial stages of kernel formation. Both a breakdown and a Radial Expansion wave of the ignition plasma are observed for certain laser ignition conditions of methane-air mixtures under typical internal combustion (IC) engine conditions. Results indicate that only certain wavelengths used for producing laser ignition produce a Radial Expansion wave. Laser ignition kernel size is calculated and laser-supported breakdown velocity is calculated by using Raizer's theory and is compared with measured results. Laser ignition results in a 4–6 ms decrease in the time for combustion to reach peak pressure than is obtained when using electric spark ignition in the same combustion chamber and under the same ignition conditions.
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laser spark ignition and combustion characteristics of methane air mixtures
Combustion and Flame, 1998Co-Authors: Jian X, Dennis R Alexander, Dana E PoulainAbstract:Ignition breakdown kernels of methane-air mixtures initiated by laser-induced sparks and by conventional electric sparks arc compared during initial stages. Experiments were conducted using a four-stroke (Otto-cycle) single-cylinder typical high-pressure combustion chamber. The piston is cycled in the cylinder by using an electric motor driven hydraulic ram. An cxcimer laser beam, either produced from krypton fluoride gas (λ = 248 nm) or argon fluoride gas (λ = 193 nm), or a Nd:YAG laser beam (λ = 1064 nm) is focused into a combustion chamber to initiate ignition. Conventional electric spark ignition is used as a basis for comparison between the two different ignition methods and the resultant early breakdown kernel characteristics. A streak camera is used to investigate and record the initial stages of kernel formation. Both a breakdown and a Radial Expansion wave of the ignition plasma are observed for certain laser ignition conditions of methane-air mixtures under typical internal combustion (IC) engine conditions. Results indicate that only certain wavelengths used for producing laser ignition produce a Radial Expansion wave. Laser ignition kernel size is calculated and laser-supported breakdown velocity is calculated by using Raizer's theory and is compared with measured results. Laser ignition results in a 4–6 ms decrease in the time for combustion to reach peak pressure than is obtained when using electric spark ignition in the same combustion chamber and under the same ignition conditions.
Omar S Alabri - One of the best experts on this subject based on the ideXlab platform.
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microstructure evolution of ultra fine grain low carbon steel tubular undergoing Radial Expansion process
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Omar S Alabri, Tasneem Pervez, Majid Almaharbi, Rashid KhanAbstract:Abstract Tubular Expansion is a cold metal forming process where diameteral change is achieved by propagating a conical mandrel through the tubular either by mechanical pull or hydraulic push. Cold metal forming alters post-Expansion mechanical and microstructural properties of tubular material, which may lead to premature failure during operation. In order to prevent tubular from failure, its post-Expansion material and mechanical properties must be investigated thoroughly. Initial grains morphology, distribution of phases, and subsequent variation in material and mechanical properties due to Expansion process of low-carbon LSX-80 steel tubular are investigated in the current study. The observed microstructure is typical of high strength steels with a mixture of carbon-poor and carbon-rich regions. A noticeable volume fraction of martensite phase was also observed. Presence of smaller grains in the material is a clear indication of the application of grain refinement mechanism to improve strength and toughness. Microhardness and Charpy impact tests were done on unexpanded and expanded sections of tubular in order to determine their mechanical properties. In addition, fractographic analysis was accomplished and obtained results showed that the morphology of the fractured surface was nearly alike at the macroscopic scale throughout the range of Expansion ratios considered in this study. However, at the fine microscopic scale, the fractured surface was mostly ductile at low Expansion ratio, while it was mainly brittle at large Expansion ratio. Hence, an Expansion ratio in the vicinity of 15% is highly recommended for the current tubular material in order to have adequate safe margin for down-hole application. An alternative material has to be selected and/or developed in order to realize the goal of achieving higher Expansion ratio (≥30%) while preserving the tubular structural integrity after Expansion.
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structural behavior of solid expandable tubular undergoes Radial Expansion process analytical numerical and experimental approaches
International Journal of Solids and Structures, 2013Co-Authors: Omar S Alabri, Tasneem PervezAbstract:Abstract Today’s structures have to meet increasingly rigorous requirements during operation. The economic and human costs of failure during service impose a great responsibility on organizations and individuals who develop new products as well as those who select/integrate products in a final engineering design. A crucial aspect for successful product development and/or inclusion is the careful selection of the best material(s), derived from an informed awareness of the capabilities and opportunities afforded by all candidate materials, together with a design that takes full benefit of those competencies. Thick-wall tubular is an example where all these issues are playing a major role in deciding their industrial applications. Given for their desirable features of high strength and geometrical shape, they are widely used in aerospace, marine, military, automotive, oil and gas, and many other fields. This paper focuses on developing analytical solution to investigate the structural response of thick-wall tubulars undergo plastic deformation due to expanding them using a rigid mandrel of conical shape. Volume incompressible condition together with the Levy–Mises flow rule were used to develop the equations which relate the Expansion ratio of the tubular to the length and thickness variations. Besides, Tresca’s yield criterion was used to include the plastic behavior of the tubular material. Further to this, a numerical model of the tubular Expansion process was also developed using the commercial finite element software ABAQUS. Experiments of tubular Expansion have been conducted using a full-scale test-rig in the Engineering Research Laboratory at Sultan Qaboos University to validate the analytical and numerical solutions. The developed analytical and numerical models are capable of predicting the stress field in the Expansion zone, the force required for Expansion, as well as the length and thickness variations induced in the tubular due to the Expansion process. Comparison between analytical, experimental, and simulation results showed that a good agreement has been attained for various parameters.
Dana E Poulain - One of the best experts on this subject based on the ideXlab platform.
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laser spark ignition and combustion characteristics of methane air mixtures
Combustion and Flame, 1998Co-Authors: Jian X, Dennis R Alexander, Dana E PoulainAbstract:Ignition breakdown kernels of methane-air mixtures initiated by laser-induced sparks and by conventional electric sparks arc compared during initial stages. Experiments were conducted using a four-stroke (Otto-cycle) single-cylinder typical high-pressure combustion chamber. The piston is cycled in the cylinder by using an electric motor driven hydraulic ram. An cxcimer laser beam, either produced from krypton fluoride gas (λ = 248 nm) or argon fluoride gas (λ = 193 nm), or a Nd:YAG laser beam (λ = 1064 nm) is focused into a combustion chamber to initiate ignition. Conventional electric spark ignition is used as a basis for comparison between the two different ignition methods and the resultant early breakdown kernel characteristics. A streak camera is used to investigate and record the initial stages of kernel formation. Both a breakdown and a Radial Expansion wave of the ignition plasma are observed for certain laser ignition conditions of methane-air mixtures under typical internal combustion (IC) engine conditions. Results indicate that only certain wavelengths used for producing laser ignition produce a Radial Expansion wave. Laser ignition kernel size is calculated and laser-supported breakdown velocity is calculated by using Raizer's theory and is compared with measured results. Laser ignition results in a 4–6 ms decrease in the time for combustion to reach peak pressure than is obtained when using electric spark ignition in the same combustion chamber and under the same ignition conditions.
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laser spark ignition and combustion characteristics of methane air mixtures
Combustion and Flame, 1998Co-Authors: Jian X, Dennis R Alexander, Dana E PoulainAbstract:Ignition breakdown kernels of methane-air mixtures initiated by laser-induced sparks and by conventional electric sparks arc compared during initial stages. Experiments were conducted using a four-stroke (Otto-cycle) single-cylinder typical high-pressure combustion chamber. The piston is cycled in the cylinder by using an electric motor driven hydraulic ram. An cxcimer laser beam, either produced from krypton fluoride gas (λ = 248 nm) or argon fluoride gas (λ = 193 nm), or a Nd:YAG laser beam (λ = 1064 nm) is focused into a combustion chamber to initiate ignition. Conventional electric spark ignition is used as a basis for comparison between the two different ignition methods and the resultant early breakdown kernel characteristics. A streak camera is used to investigate and record the initial stages of kernel formation. Both a breakdown and a Radial Expansion wave of the ignition plasma are observed for certain laser ignition conditions of methane-air mixtures under typical internal combustion (IC) engine conditions. Results indicate that only certain wavelengths used for producing laser ignition produce a Radial Expansion wave. Laser ignition kernel size is calculated and laser-supported breakdown velocity is calculated by using Raizer's theory and is compared with measured results. Laser ignition results in a 4–6 ms decrease in the time for combustion to reach peak pressure than is obtained when using electric spark ignition in the same combustion chamber and under the same ignition conditions.
