bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frame Indifference: Fluid Flow in Single Screw Pumps and Extruders
Authors: Campbell G. A. , Sweeney P. A. , Dontula N. , Wang Ch. 
Published: December 2013

Abstract
In this paper we define the extruder analysis in the Eulerian frame. Then, we convert the analysis to the Lagrangian frame to avoid the difficult moving boundary problem. Finally, unlike the classical analysis we convert the solution back to the Eulerian fame before calculation of velocities and flow rates. The single screw pump or extruder has classically been evaluated by leaving the analysis in the Lagrangian reference frame and the flow in the pump is described as due only to down channel drag flow. Since velocity is not frame indifferent, we complete the analysis by transforming the Lagrangian analysis back to the Eulerian solution. The pumping mechanism is quite different when the velocities are properly converted back to the Eulerian frame of reference. This new analysis demonstrates that, if the problem is approached using superposition, the pumping mechanism in a screw pump is due to the “piston like” action of the helix x-component velocity, and that the down channel z-component velocity, drag flow, from the helix and screw core reduce the maximum pump efficiency of the helix by about 50 %.
Structures and Properties of Injection Moldings of β-Crystal Nucleator-Added Polypropylenes
Authors: Fujiyama M. 
Published: December 2013

Abstract
The β-crystal nucleating effect on polypropylene has been compared between γ-quinacridone and quinacridonequinone. While the β-crystal does not form at γ-quinacridone content below 1 ppm where red coloring is recognized on the molded article, much β-crystal forms even at quinacridonequinone content below 1 ppm where brown coloring is not recognized on the molded article. This means that the β-crystal nucleating ability of quinacridonequinone is superior to that of γ-quinacridone. However, both nucleators show a similar change in the physical properties of injection molded article against nucleator content.
Influence of Design on Mixing Efficiency in a Variable Intermeshing Clearance Mixer
Authors: Yao C.-H. , Manas-Zloczower I. 
Published: December 2013

Abstract
The Variable Intermeshing Clearance (VIC) mixer possesses the unique feature of the ability to change the inter-rotor clearance during the compounding process. To improve the mixing performance of the VIC mixer new designs are proposed. A fluid dynamics analysis package-FIDAP, using the finite element method was employed to simulate the flow behavior in the VIC mixer. The problem of time dependent flow boundaries was solved by selecting a number of sequential geometries with 20 degree increments to represent a complete mixing cycle. Dispersive mixing was evaluated in terms of both the shear stress distribution and the elongational flow components generated in the flow field. Distributive mixing was studied numerically by means of tracking the evolution of particles originally gathered as clusters. Our studies indicate that the new design of an enlarged chamber gives overall better dispersive and distributive mixing performance than the traditional VIC. The VIC mixer with both an enlarged chamber and wider rotor blades design shows poorer dispersive mixing but better distributive mixing capability. The effect of inter-rotor clearance on mixing efficiency is also discussed.
Rheological Behaviour of LLDPE/LDPE Blends under Elongational Deformation
Authors: Micic P. , Bhattacharya S. N. , Field G. 
Published: December 2013

Abstract
Blends made of one linear low density polyethylene (LLDPE) and either of two low density polyethylenes (LDPE 1 and LDPE 2) were tested in elongational modes of deformation using elongational viscosity and melt strength test. In addition to rheological measurements the melt miscibility of the blends was ascertained by the differential scanning calorimetry (DSC) test on melt quenched samples. From the results, the relation between melt morphology of the blends and their performance under elongation, as well as the influence of molecular structure in particular long chain branching, on elongational response were determined. It was observed that high resistance to elongational deformation of the blends is linked to the immiscibility of the blend components in the melt. On the other hand the influence of long chain branching is to increase elongational viscosity for the parent polymers, as well as promoting the blend immiscibility and therefore altering elongational performance of the blends.
Numerical Modelling of the Mould Filling Stage in Gas-Assisted Injection Moulding
Authors: Gao D. M. , Nguyen K. T. , Garcia-Rejon A. , Salloum G. 
Published: December 2013

Abstract
This paper presents an effective numerical model capable of simulating the filling stage of the gas-assisted injection molding process, particularly the gas penetration phenomenon involving the gas-polymer interaction. A Galerkin Finite Element model is used to model the polymer flow during the filling and gas penetration stages. The polymer flow front and the gas-polymer interface are tracked using a volume tracking technique. Finally, a finite difference technique has been used to calculate the temperature across the thickness. Comparison between numerical simulation predictions and the experimental data for a plate mould as well as for a complex part is presented.
A Composite Model for Solid Conveying, Melting, Pressure and Fill Factor Profiles in Modular Co -Rotating Twin Screw Extruders
Authors: Bawiskar S. , White J. L. 
Published: December 2013

Abstract
A composite model simulation of solids conveying, melting and melt flow in a modular co-rotating twin screw extruder has been developed. This is based on combining existing melt conveying models with new melting and solids conveying models for the various elements of a modular twin screw extruder. Computations are made for axial fill factor, pressure, temperature, melting profiles and also the power consumption, torque, specific energy consumption and average residence times. The results are compared with experiment.
Experimental and Theoretical Study of Rectangular Fiber Melt Spinning
Authors: Noh Y.-W. , Kim S. Y. , Kwon Y. 
Published: December 2013

Abstract
In order to study the process of rectangular fiber melt spinning, experimental and theoretical investigations are conducted. Several different values of such process variables as die dimension, flow rate, take-up speed, quench air speed and temperature, and die temperature are chosen for manufacturing poly(ethylene terephthalate) fibers. Both 1- and 2-dimensional formulations are employed under the Newtonian fluid assumption. Two separate mathematical schemes are then combined via the Picard iteration to provide a convenient tool estimating the process with all variables taken into account and with as little computational effort as possible. From this experiment, it is found that the extrudate exhibits negative swelling in the fiber width direction, which results from the negative second normal stress direction in shear flow inside the die. Fiber cross-section takes elliptical shape at the point of maximum thickness swell and then gets flat as it approaches the take-up point. As to numerical simulation, all the quantities such as fiber dimension, velocity, temperature and tension except variables related to cross-sectional area are relatively well described by this simple theory. Neglect of material elasticity and over-simplification of temperature variation along fiber cross-section are main causes for the deviation of calculated values from experimental data.
Transesterification of Ethylene Acetate Copolymer in a Twin Screw Extruder
Authors: Berzin F. , Vergnes B. 
Published: December 2013

Abstract
The chemical modification of poly(ethylene-co-vinyl acetate) with a primary aliphatic n-alcohol in a modular co-rotating twin screw extruder was investigated. The purpose was to build a theoretical model, able to predict the extent of conversion along the screw axis. First, the influence of operating conditions (throughput, screw speed, barrel temperature and initial reactant concentrations) on the EVA copolymer conversion was experimentally examined. Then, the extent of conversion was computed by coupling flow simulation and reaction kinetics. Theoretical and experimental results were found in good agreement, what allows the prediction of the reaction extent as a function of the processing conditions.
Flow Behaviour of Blends of Poly(ethylene-Co-Acrylic Acid) and Epoxidised Natural Rubber
Authors: Mohanty S. , Bhattacharya A. K. , Nando G. B. , Gupta B. R. 
Published: December 2013

Abstract
Processability and rheological properties of the blends of poly(ethylene-Co-acrylic acid) (PEA) and epoxidised natural rubber (ENR) have been studied by a Monsanto Processibility Tester (MPT). The blends were found to be miscible during reactive processing due to chemical interaction via esterification reaction at higher proportion of PEA. The rheological properties were studied at three different temperatures (120°C, 130°C and 150°C), five different shear rates in the range from 122s−1 to 2452s−1 and at three different shear stresses (i.e., 400, 500 and 600 kPa). The melt viscosities of the blends at 120°C and 130°C show a positive deviation at lower shear rates and shear stress and at higher proportions of PEA and a negative deviation at higher shear rates and shear stress and lower proportion of PEA, where as at higher temperature (i.e. at 150°C) of melt processing the viscosities show positive deviation (at all shear rates for all the blends) with respect to that calculated by additivity rule. This variation in melt viscosities has been explained on the basis of chemical reaction via esterification leading to grafted structure i.e., PEA-g-ENR.
Processing/Structure Relationships of Mica-Filled PE-Films with Low Oxygen Permeability
Authors: Xanthos M. , Faridi N. , Li Y. 
Published: December 2013

Abstract
Lamellar microstructures can decrease gas and vapor permeability by increasing the diffusive path or the so-called “tortuosity” in plastic films. In this research, phlogopite mica flakes were used as oxygen barrier materials in films produced in a blown film extrusion line. Both high and low density polyethylenes as well as their blends were used as matrices with mica concentrations not exceeding 10-wt.-%. A decrease in oxygen permeability of both low density and high density polyethylene films was achieved with increasing volume fraction of mica. Film morphologies indicated strong flow-induced orientation of the flakes in overlapping, discontinuous layers that were reasonably well oriented parallel to the surface of the films. Melt shear viscosity and melt strength of the mica compounds and tensile properties of films were also examined and correlated with processability. Overall, it was found that, by contrast to the LDPE compounds, optimization of the barrier properties of the HDPE films was a compromise between the desired reduction in permeability and the loss in processability and film ductility. The experimentally determined elastic modulus values were found to be in relatively good agreement with predictions from flake reinforcement theories. A predictive model for the analysis of the permeability results, assuming that both mica flakes and the crystalline domains of the films were impermeable to oxygen, was able to describe the permeability results in spite of several simplifying assumptions.
Free Radical Grafting of Glycidyl Methacrylate onto PP in a Co-rotating Twin Screw Extruder
Authors: Hu G.-H. , Cartier H. 
Published: December 2013

Abstract
A typical free radical grafting system is composed of a polymer substrate, a vinyl bearing monomer and a free radical initiator (usually a peroxide). When the reaction is to be carried out in a co-rotating twin screw extruder, there are two main ways to feed the chemicals to the extruder: either they are fed together to the main hopper (one-pot feeding) or only the polymer is fed to the main hopper and the grafting monomer and the peroxide are injected downstream either just before or after the first kneading zone (sequential feeding).
In this study, we investigate the influence of feeding mode on the free radical grafting. We use the free radical grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) as a model system. It is found that GMA's grafting yields are very close between the one-pot feeding and the sequential feeding just before the first kneading zone. However, those obtained with the sequential feeding just after the first kneading zone are much lower. This dramatic difference is closely related to the mixing environments GMA and the peroxide are subjected to. When GMA and the peroxide are injected before the kneading zone where the screw channel is fully filled, GMA and the peroxide are forced to mix with PP. When they are fed to the extruder just after the kneading zone, however, they simply drip on the highly viscous PP. As such, before the grafting takes place between PP and GMA, the peroxide may have started to decompose and GMA may have started to polymerize. It is recommended that low molecular weight ingredients be fed to the extruder through a fully filled zone.
Predicting Drop Breakup in Complex Flows from Model Flow Experiments
Authors: Bigio D. I. , Marks C. R. , Calabrese R. V. 
Published: December 2013

Abstract
New experimental results describing the breakup of drops suddenly subjected to shearing forces sufficient to cause drop breakup are presented. The experiments examine fluids which are immiscible and Newtonian under the conditions studied. These results and other breakup mechanism results are then discussed in the context of combining them with kinematic information on more complex flows in order to predict drop size distributions in processing flows. By analyzing the time scales of various breakage mechanisms studied in simple shear flow and comparing them to the appropriate time scales in more complex flows, the relevant importance of a given mechanism in determining the daughter drop size distribution is predicted. This type of time scale analysis is performed for flow in a cavity and flow in an extruder.
Dorsal spinal arachnoid web diagnosed with the quantitative measurement of cerebrospinal fluid flow on magnetic resonance imaging
Authors: Chang Han Soo , Nagai Atsushi , Oya Soichi , Matsui Toru 
Published: December 2013

An arachnoid web is an abnormal formation of the arachnoid membrane in the spinal subarachnoid space that blocks CSF flow and causes syringomyelia. Although the precise mechanism of syrinx formation is unknown, dissection of the arachnoid web shrinks the syrinx and improves symptoms. Precisely determining the location of the arachnoid web is difficult preoperatively, however, because the fine structure generally cannot be visualized in usual MRI sequences.
In this report the authors describe 2 cases of arachnoid web in which the web was preoperatively identified using quantitative CSF flow analysis of MRI. By analyzing cardiac-gated phase-contrast cine-mode MRI in multiple axial planes, the authors precisely localized the obstruction of CSF flow on the dorsal side of the spinal cord in both patients. This technique also revealed a 1-way valve-like function of the arachnoid webs. Imaging led to the early diagnosis of myelopathy related to the derangement of CSF flow and allowed the authors to successfully excise the webs through limited surgical exposure.
Le concept de genre au cidff : un outil de travail pour l'insertion
Authors: Charles Frédéric , Fortino Sabine 
Published: December 2013

Dans le cas singulier d’un réseau d’associations intervenant en faveur de la défense des droits des femmes (les Centres d’information sur les droits des femmes et des familles ou cidff ), nous nous proposons d’analyser comment les théories du genre sont appropriées puis ‘travaillées’ par les professionnel∙le∙s du réseau dans le cadre de leur activité à destination des femmes précaires en insertion. L’article présente quelques dispositifs particulièrement innovants qui tentent de concilier lutte contre le chômage, « avancée en mixité des emplois » et émancipation des femmes. Il en montre aussi les limites dans un contexte de désengagement de l’État et de difficultés financières récurrentes mettant parfois à mal le fonctionnement et les missions initiales des associations.
Notre visite du 28 mars 2013 à l'école de la Neuville
Authors: Jacquet-Francillon François , Savio Camille Suzanne 
Published: December 2013

Résumé : L’école de la Neuville a été créée en 1973 sur les bases de la pédagogie institutionnelle, avec des orientations thérapeutiques. L’école accueille en internat des enfants de 6 à 15 ans en difficulté avec l’institution scolaire. Lors de leur visite, les auteurs sont pris en charge par deux élèves qui les guident à travers l’établissement ; ils dialoguent avec une classe sur son fonctionnement, voient l’internat (qui sépare filles et garçons), observent deux petites réunions où le groupe traite des petits conflits de la vie quotidienne, et assistent au « Grand conseil » qui s’occupe du bilan et de la régulation générale de l’école. Le document qu’ils présentent nous fait aussi part de leurs impressions, de leurs réflexions sur la portée et la valeur à leurs yeux de ce type de « pédagogie active » : circulation de la parole, égalité et réciprocité, prise en compte de chacun dans sa personne et sa dignité, respect fluide des règles, une éducation qui pourrait être exemplaire, « parvenue à un haut degré d’humanité ».
Jacotot, Rancière : essai de contextualisation historique
Authors: Grèzes-Rueff François 
Published: December 2013

Résumé : Les thèses de Rancière et de Jacotot ont ceci de commun qu’elles font chacune rupture dans leur époque en faisant de l’égalité (des intelligences / des positions) le principe directeur de tout projet d’émancipation par l’instruction ; de là découle leur caractère anarchique, voire utopique. L’article se propose cependant de replacer les deux auteurs dans leur contexte historique : l’expérience des Écoles centrales et le protestantisme, le statut de l’élève et la dissymétrie de la relation “enseignante” – questions qu’il met en relation avec la construction en Europe de l’individu démocratique (obéissance à des normes collectives vs libération de l’initiative individuelle) et la “révolution culturelle” des années 1960 qui réaffirme de façon radicale l’impérialité de l’idée d’égalité.
Concurrent Generation of Functional Smooth Muscle and Endothelial Cells via a Vascular Progenitor
Authors: Marchand Melanie , Anderson Erica K. , Phadnis Smruti M. , Longaker Michael T. , Cooke John P. , Chen Bertha , Reijo Pera Renee A. 
Published: December 2013

AbstractSmooth muscle cells (SMCs) and endothelial cells (ECs) are typically derived separately, with low efficiencies, from human pluripotent stem cells (hPSCs). The concurrent generation of these cell types might lead to potential applications in regenerative medicine to model, elucidate, and eventually treat vascular diseases. Here we report a robust two-step protocol that can be used to simultaneously generate large numbers of functional SMCs and ECs from a common proliferative vascular progenitor population via a two-dimensional culture system. We show here that coculturing hPSCs with OP9 cells in media supplemented with vascular endothelial growth factor, basic fibroblast growth factor, and bone morphogenetic protein 4 yields a higher percentage of CD31+CD34+ cells on day 8 of differentiation. Upon exposure to endothelial differentiation media and SM differentiation media, these vascular progenitors were able to differentiate and mature into functional endothelial cells and smooth muscle cells, respectively. Furthermore, we were able to expand the intermediate population more than a billionfold to generate sufficient numbers of ECs and SMCs in parallel for potential therapeutic transplantations.
Multiecho scheme advances surface NMR for aquifer characterization
Authors: Grunewald Elliot , Walsh David 
Published: December 2013

AbstractSurface nuclear magnetic resonance (NMR) is increasingly used as a method to noninvasively characterize aquifers. This technology follows a successful history of NMR logging, applied over decades to estimate hydrocarbon reservoir properties. In contrast to logging, however, surface methods have utilized relatively simple acquisition sequences, from which pore‐scale properties may not be reliably and efficiently estimated. We demonstrate for the first time the capability of sophisticated multiecho measurements to rapidly record a surface NMR response that more directly reflects aquifer characteristics. Specifically, we develop an adaptation of the multipulse Carr‐Purcell‐Meiboom‐Gill (CPMG) sequence, widely used in logging, to measure the T2 relaxation response in a single scan. We validate this approach in a field surface NMR data set and by direct comparison with an NMR log. Adoption of the CPMG marked a landmark advancement in the history of logging NMR; we have now realized this same advancement in the surface NMR method.
Asthenospheric Pacific‐Atlantic flow barriers and the West Scotia Ridge extinction
Authors: Martos Yasmina M. , Galindo‐Zaldívar Jesús , Catalán Manuel , Bohoyo Fernando , Maldonado Andrés 
Published: December 2013

AbstractThe Drake Passage is considered a gateway for oceanic and asthenospheric flows since its opening, entailing widespread consequences for climate and plate tectonics, respectively. Both the surface and the 50 km upward continued Bouguer anomaly maps of the Scotia Sea and surrounding areas, based on Gravity Recovery and Climate Experiment gravity satellite data, improve our knowledge of deep lithospheric structures and the asthenosphere. We show that the West Scotia Sea is likely to be underlain by an anomalously low‐density upper mantle. Gravity data are compatible with variable lithospheric thicknesses related to asthenospheric currents. The new data suggest that the development of the Shackleton Fracture Zone since the middle Miocene was probably a main factor that determined the evolution of the eastward Pacific mantle flows and the extinction of the West Scotia Sea oceanic spreading around 6 Ma ago. Deep lithospheric roots are likely to divert asthenospheric currents around them, flowing eastward through Drake Passage.