The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
Chongwen Yu - One of the best experts on this subject based on the ideXlab platform.
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Fiber motion and the accelerated point distribution in Roller Drafting
Textile Research Journal, 2018Co-Authors: Kudakwashe D Mupfudze, Yuanying Shen, Chongwen YuAbstract:In this study, the tracer fiber method was used to determine the accelerated point distribution in both the break draft and main Drafting zone of the drawing frame with varying different draft para...
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effect of accelerated point distribution on sliver irregularity part ii optimization of draft settings in two zone Roller Drafting system
Journal of The Textile Institute, 2012Co-Authors: William Oxenham, Chongwen YuAbstract:Accelerated point distribution plays a dominant role in discussing sliver irregularity in Drafting. This paper, which is based on a theory developed in an earlier publication, proposes a new method to optimize the draft settings using the minimum coefficient of variation (CV) of fiber accelerated point. The new approach offers advantages over the traditional regressed optimal drafted settings (to yield the least weight variation in drafted slivers) and does not need extensive laboratory trials.
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A study of the Drafting force in Roller Drafting and its influence on sliver irregularity
Journal of The Textile Institute, 2011Co-Authors: William Oxenham, Chongwen YuAbstract:Drafting force is the direct and intuitive factor resulting in fiber motion in a Drafting zone. Utilizing data collected from an ITT Draftometer, this paper discusses the effect of draft ratio and ratch in both the break and the main draft zones on Drafting force and the coefficient of variation (CV) of Drafting force, and how these in turn affect sliver and yarn irregularity. It is shown that: the draft settings in the break draft zone have a significant effect on the Drafting force; the break draft ratio shows distinct relationship with sliver irregularity; the ratch in the main Drafting zone has considerable influence on Drafting force; and in the experiments reported the Drafting force does not directly relate to final yarn irregularity.
You Huh - One of the best experts on this subject based on the ideXlab platform.
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characterizing the dynamic behavior of staple length distributed slivers in Roller Drafting
Fibers and Polymers, 2018Co-Authors: Jung Ho Lim, Jong S Kim, You HuhAbstract:Roller Drafting is often accompanied by an irregularity in the linear density of slivers. In this research, the issue of sliver irregularity was investigated by simulating the dynamic behavior of slivers in the Roller draft zone based on an improved mathematical model describing the movement of slivers with a staple-length distribution. The linear density and velocity of slivers in the draft zone were considered coupled variables. Simulations under certain constraints in the parameters, changing only the sliver viscosity, revealed that the sliver linear density can fluctuate during steady state (the socalled draft wave) in a certain range of sliver viscosity, and those fluctuations can be decomposed into several mode frequencies. However, the draft wave did not appear when slivers with low viscosity were used, suggesting that good open slivers composed of low surfacefriction staples can yield to a good drafted sliver without draft waves.
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manufacturing nanofibrous bundles and the Roller Drafting effects on the bundle properties
Journal of The Textile Institute, 2017Co-Authors: Ganba Tumenulzii, Jung Ho Lim, You HuhAbstract:AbstractThis research reports a new product form made of nanofibers and the method used to produce it. Nanofibers are electrospun into a web form on a moving collector and the web is continuously transformed into a bundle by passage through a condenser. Since the web is made of loops of nanofibers and peeled off from the collector surface, the condensed bundle deforms very easily and is too weak for further processing. Thus, the bundle is drafted through a Roller Drafting system to improve the fiber array in the bundle length direction in various levels of draft temperature, since the temperature may affect the bundle Drafting process and thus the bundle properties. Using a newly designed system, we tried to produce nanofibrous bundle of polyvinylidiene difluoride. The nanofiber arrangement and the tensile properties of the bundle were measured before and after the Roller Drafting process under various conditions. Results showed that the technology suggested in this paper had the feasibility to manufactur...
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analyzing Roller Drafting dynamics with stochastic perturbations simulation approach
Textile Research Journal, 2012Co-Authors: Jong S Kim, Jung H Lim, You HuhAbstract:This research investigates the effects that perturbations in Roller Drafting operations have on fiber bundles in the draft zone. In particular, it examines the effect of perturbations on the thickness of the output bundle. To do so, a test signal was characterized by a stochastic signal with an autocorrelation function and was generated using the Random Phase Spectral (RPS) method. Each stochastic signal represented perturbations in the Roller Drafting. Then, the spatial and temporal distributions of the linear density of the fiber bundle in the Drafting zone were simulated, using the mathematical model that described the bundle flow dynamics in the Roller Drafting process, and the irregularities of the output linear density were estimated. Results showed that changes in the bundle cohesion, input linear density, and draft ratio led to distinctive variations with some special pattern in the output bundle linear density, but changes in the draft process speed did not. For example, perturbations in the bundle cohesion generated a stochastically periodic component in the irregularities of the output linear density. In contrast, periodic attributes generated from perturbations in the input linear density subsided in the output bundle as the perturbation intensity increased. At the same time, the output bundle irregularity was strongly influenced by the perturbation strength of the input linear density. Variation in the draft ratio appeared similarly in the output thickness irregularities. However, variations in the process speed did not influence the output irregularities, indicating that inertial effects of the fiber bundle on the draft dynamics can be neglected.
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analysis of sliver thickness variation from process perturbations in Roller Drafting
Journal of The Textile Institute, 2012Co-Authors: Jong S Kim, Moo W Suh, You HuhAbstract:In processing fiber bundles in staple yarn manufacturing, the bundles are doubled and attenuated to an appropriate thickness via Drafting. The process conditions are optimized with respect to the fiber and bundle properties. Otherwise, the output fiber bundle becomes non-uniform in its linear density. This research deals with finding the changes in linear density of the output bundle when perturbations are applied to the Drafting conditions. Perturbations with specific autocorrelation functions were generated by the random phase spectral method. Along with the stochastically generated test signals, the transient linear density profiles of the fiber bundle in the Drafting zone were simulated by using a mathematical model describing the dynamics of the Roller Drafting, and thus, the linear density of the output bundle could be predicted. Our results showed that the disturbances in input linear density affected the transient profiles of the linear density of the fiber bundle inside the draft zone. It was als...
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numerical analysis of fiber fleece behavior in Roller Drafting in a transient state
Textile Research Journal, 2008Co-Authors: Jong Sung Kim, Chokri Cherif, You HuhAbstract:Fiber bundle thickness irregularity from a roll draft mechanism was analyzed in the time domain on the basis of a theoretical model (Partial Differential Equation, PDE, system) for bundle flow. As the governing equations that consisted of continuity and motion equations turned out to be nonlinear, being coupled between variables, etc., a numerical method was established to solve the problem. In particular, the Forward-Time Central-Space (FTCS) difference formula with an explicit Euler scheme as the Finite Difference Method (FDM) was applied. Then the system of equations, which were in algebraic form, was solved according to given initial and boundary conditions in an iterative fashion. Results from this research confirmed that the theoretical response of the output linear density to the disturbance of Drafting condition agreed very well with experiment. The transient state of the velocity profile faded out more quickly than that of the linear density profile. The response of the output bundle thickness to...
William Oxenham - One of the best experts on this subject based on the ideXlab platform.
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effect of accelerated point distribution on sliver irregularity part ii optimization of draft settings in two zone Roller Drafting system
Journal of The Textile Institute, 2012Co-Authors: William Oxenham, Chongwen YuAbstract:Accelerated point distribution plays a dominant role in discussing sliver irregularity in Drafting. This paper, which is based on a theory developed in an earlier publication, proposes a new method to optimize the draft settings using the minimum coefficient of variation (CV) of fiber accelerated point. The new approach offers advantages over the traditional regressed optimal drafted settings (to yield the least weight variation in drafted slivers) and does not need extensive laboratory trials.
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A study of the Drafting force in Roller Drafting and its influence on sliver irregularity
Journal of The Textile Institute, 2011Co-Authors: William Oxenham, Chongwen YuAbstract:Drafting force is the direct and intuitive factor resulting in fiber motion in a Drafting zone. Utilizing data collected from an ITT Draftometer, this paper discusses the effect of draft ratio and ratch in both the break and the main draft zones on Drafting force and the coefficient of variation (CV) of Drafting force, and how these in turn affect sliver and yarn irregularity. It is shown that: the draft settings in the break draft zone have a significant effect on the Drafting force; the break draft ratio shows distinct relationship with sliver irregularity; the ratch in the main Drafting zone has considerable influence on Drafting force; and in the experiments reported the Drafting force does not directly relate to final yarn irregularity.
Jong S Kim - One of the best experts on this subject based on the ideXlab platform.
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characterizing the dynamic behavior of staple length distributed slivers in Roller Drafting
Fibers and Polymers, 2018Co-Authors: Jung Ho Lim, Jong S Kim, You HuhAbstract:Roller Drafting is often accompanied by an irregularity in the linear density of slivers. In this research, the issue of sliver irregularity was investigated by simulating the dynamic behavior of slivers in the Roller draft zone based on an improved mathematical model describing the movement of slivers with a staple-length distribution. The linear density and velocity of slivers in the draft zone were considered coupled variables. Simulations under certain constraints in the parameters, changing only the sliver viscosity, revealed that the sliver linear density can fluctuate during steady state (the socalled draft wave) in a certain range of sliver viscosity, and those fluctuations can be decomposed into several mode frequencies. However, the draft wave did not appear when slivers with low viscosity were used, suggesting that good open slivers composed of low surfacefriction staples can yield to a good drafted sliver without draft waves.
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analyzing Roller Drafting dynamics with stochastic perturbations simulation approach
Textile Research Journal, 2012Co-Authors: Jong S Kim, Jung H Lim, You HuhAbstract:This research investigates the effects that perturbations in Roller Drafting operations have on fiber bundles in the draft zone. In particular, it examines the effect of perturbations on the thickness of the output bundle. To do so, a test signal was characterized by a stochastic signal with an autocorrelation function and was generated using the Random Phase Spectral (RPS) method. Each stochastic signal represented perturbations in the Roller Drafting. Then, the spatial and temporal distributions of the linear density of the fiber bundle in the Drafting zone were simulated, using the mathematical model that described the bundle flow dynamics in the Roller Drafting process, and the irregularities of the output linear density were estimated. Results showed that changes in the bundle cohesion, input linear density, and draft ratio led to distinctive variations with some special pattern in the output bundle linear density, but changes in the draft process speed did not. For example, perturbations in the bundle cohesion generated a stochastically periodic component in the irregularities of the output linear density. In contrast, periodic attributes generated from perturbations in the input linear density subsided in the output bundle as the perturbation intensity increased. At the same time, the output bundle irregularity was strongly influenced by the perturbation strength of the input linear density. Variation in the draft ratio appeared similarly in the output thickness irregularities. However, variations in the process speed did not influence the output irregularities, indicating that inertial effects of the fiber bundle on the draft dynamics can be neglected.
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analysis of sliver thickness variation from process perturbations in Roller Drafting
Journal of The Textile Institute, 2012Co-Authors: Jong S Kim, Moo W Suh, You HuhAbstract:In processing fiber bundles in staple yarn manufacturing, the bundles are doubled and attenuated to an appropriate thickness via Drafting. The process conditions are optimized with respect to the fiber and bundle properties. Otherwise, the output fiber bundle becomes non-uniform in its linear density. This research deals with finding the changes in linear density of the output bundle when perturbations are applied to the Drafting conditions. Perturbations with specific autocorrelation functions were generated by the random phase spectral method. Along with the stochastically generated test signals, the transient linear density profiles of the fiber bundle in the Drafting zone were simulated by using a mathematical model describing the dynamics of the Roller Drafting, and thus, the linear density of the output bundle could be predicted. Our results showed that the disturbances in input linear density affected the transient profiles of the linear density of the fiber bundle inside the draft zone. It was als...
Kudakwashe D Mupfudze - One of the best experts on this subject based on the ideXlab platform.
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Fiber motion and the accelerated point distribution in Roller Drafting
Textile Research Journal, 2018Co-Authors: Kudakwashe D Mupfudze, Yuanying Shen, Chongwen YuAbstract:In this study, the tracer fiber method was used to determine the accelerated point distribution in both the break draft and main Drafting zone of the drawing frame with varying different draft para...
