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Swell
Kinds of Swell Terms modified by Swell Selected Abstracts3D imaging of a reservoir analogue in point bar deposits in the Ferron Sandstone, Utah, using ground-penetrating radarGEOPHYSICAL PROSPECTING, Issue 3 2004Xiaoxian Zeng ABSTRACT Most existing reservoir models are based on 2D outcrop studies; 3D aspects are inferred from correlation between wells, and so are inadequately constrained for reservoir simulations. To overcome these deficiencies, we have initiated a multidimensional characterization of reservoir analogues in the Cretaceous Ferron Sandstone in Utah. Detailed sedimentary facies maps of cliff faces define the geometry and distribution of reservoir flow units, barriers and baffles at the outcrop. High-resolution 2D and 3D ground-penetrating radar (GPR) images extend these reservoir characteristics into 3D to allow the development of realistic 3D reservoir models. Models use geometric information from mapping and the GPR data, combined with petrophysical data from surface and cliff-face outcrops, and laboratory analyses of outcrop and core samples. The site of the field work is Corbula Gulch, on the western flank of the San Rafael Swell, in east-central Utah. The outcrop consists of an 8,17 m thick sandstone body which contains various sedimentary structures, such as cross-bedding, inclined stratification and erosional surfaces, which range in scale from less than a metre to hundreds of metres. 3D depth migration of the common-offset GPR data produces data volumes within which the inclined surfaces and erosional surfaces are visible. Correlation between fluid permeability, clay content, instantaneous frequency and instantaneous amplitude of the GPR data provides estimates of the 3D distribution of fluid permeability and clay content. [source] The Effect of Orientation on Extrusion Cast Metallocene Polyethylenes and the Role of Processing Conditions in the Die Swell of Metallocene and Conventional PolyethylenesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1-2 2004B.G. Millar Cast films were prepared from a range of metallocene polyethylenes (mPEs) of varied co-monomer types (hexene, octene) using a Killion single-screw extruder, using different haul off speeds (8,4 m/min) and die gaps (700,250 m,m). Samples with greater orientation in one direction had increased tensile strength and shrinkage in that direction. DSC analysis showed crystallinity to decrease with decreasing haul of speed. Extrusion of mPEs and conventional linear low density polyethylenes (LLDPEs) by single capillary rheology showed that die swell increased with increasing extrusion rate and decreasing melt temperature. Increased die swell was found for the broader molecular weight distribution (M.W.D.) LLDPEs and in the higher molecular weight resins. Furthermore, long chain branching was found to increase die swell. [source] Characteristics of Oil Sources from the Chepaizi Swell, Junggar Basin, ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2010LIU Luofu Abstract: So far there has been no common opinion on oil source of the Chepaizi swell in the Junggar Basin. Therefore, it is difficult to determine the pathway system and trend of hydrocarbon migration, and this resulted in difficulties in study of oil-gas accumulation patterns. In this paper, study of nitrogen compounds distribution in oils from Chepaizi was carried out in order to classify source rocks of oils stored in different reservoirs in the study area. Then, migration characteristics of oils from the same source were investigated by using nitrogen compounds parameters. The results of nitrogen compounds in a group of oil/oil sand samples from the same source indicate that the oils trapped in the Chepaizi swell experienced an obvious vertical migration. With increasing migration distance, amounts and indices of carbazoles have a regular changing pattern (in a fine linear relationship). By using nitrogen compounds techniques, the analyzed oil/oil sand samples of Chepaizi can be classified into two groups. One is the samples stored in reservoir beds of the Cretaceous and Tertiary, and these oils came from mainly Jurassic source rock with a small amount of Cretaceous rock; the other is those stored in the Jurassic, Permian and Carboniferous beds, and they originated from the Permian source. In addition, a sample of oil from an upper Jurassic reservoir (Well Ka 6), which was generated from Jurassic coal source rock, has a totally different nitrogen compound distribution from those of the above-mentioned two groups of samples, which were generated from mudstone sources. Because of influence from fractionation of oil migration, amounts and ratios of nitrogen compounds with different structures and polarities change regularly with increasing migrating distance, and as a result the samples with the same source follow a good linear relationship in content and ratio, while the oil samples of different sources have obviously different nitrogen compound distribution owing to different organic matter types of their source rocks. These conclusions of oil source study are identical with those obtained by other geochemical bio-markers. Therefore, nitrogen compounds are of great significance in oil type classification and oil/source correlation. [source] MULTIDISCIPLINARY PAIN ABSTRACTS: 34PAIN PRACTICE, Issue 1 2004Article first published online: 15 MAR 200 Because recent studies emphasized the role of peripherally distributed N-methyl-D-aspartate (NMDA) receptors in processing the nociceptive information, the authors investigated whether peripheral application of the ointment containing ketoconazole (KET) is able to attenuate the symptoms of local neuropathic pain. They applied ointment containing KET (0.25%,1.5%) to the affected area on limbs in five patients with complex regional pain syndrome type I (CRPS I) and in two patients with type II (CRPS II). One to 2 weeks later, they observed improvement of the report of pain intensity, measured by the visual analog scale, in four patients with acute early dystrophic stage of CRPS I. Swelling of the affected limbs subsided as well. No apparent changes were noticed in one patient with chronic atrophic stage of CRPS I and in both patients with CRPS II. The authors concluded that topical application of KET appears to be beneficial for the patients with acute early dystrophic stage of CRPS I because of either its local anesthetic effect or NMDA receptor antagonist action. Patients with chronic atrophic stage of CRPS I and CRPS II patients do not appear to respond to this treatment. [source] RECOGNIZING STRONG AND WEAK OPINION CLAUSESCOMPUTATIONAL INTELLIGENCE, Issue 2 2006Theresa Wilson There has been a recent swell of interest in the automatic identification and extraction of opinions and emotions in text. In this paper, we present the first experimental results classifying the intensity of opinions and other types of subjectivity and classifying the subjectivity of deeply nested clauses. We use a wide range of features, including new syntactic features developed for opinion recognition. We vary the learning algorithm and the feature organization to explore the effect this has on the classification task. In 10-fold cross-validation experiments using support vector regression, we achieve improvements in mean-squared error over baseline ranging from 49% to 51%. Using boosting, we achieve improvements in accuracy ranging from 23% to 96%. [source] Conjugated-Polymer-Based Lateral Heterostructures Defined by High-Resolution PhotolithographyADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Jui-Fen Chang Abstract Solution processing of polymer semiconductors provides a new paradigm for large-area electronics manufacturing on flexible substrates, but it also severely restricts the realization of interesting advanced device architectures, such as lateral heterostructures with defined interfaces, which are easily accessible with inorganic materials using photolithography. This is because polymer semiconductors degrade, swell, or dissolve during conventional photoresist processing. Here a versatile, high-resolution photolithographic method is demonstrated for patterning of polymer semiconductors and exemplify this with high-performance p-type and n-type field-effect transistors (FETs) in both bottom- and top-gate architectures, as well as ambipolar light-emitting field-effect transistors (LEFETs), in which the recombination zone can be pinned at a photolithographically defined lateral heterojunction between two semiconducting polymers. The technique therefore enables the realization of a broad range of novel device architectures while retaining optimum materials performance. [source] Uplift at lithospheric swells,I: seismic and gravity constraints on the crust and uppermost mantle structure of the Cape Verde mid-plate swellGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2010D. J. Wilson SUMMARY Wide-angle seismic data have been used to determine the velocity and density structure of the crust and uppermost mantle beneath the Cape Verdes mid-plate swell. Seismic modelling reveals a ,standard' oceanic crust, ,8 km in thickness, with no direct evidence for low-density bodies at the base of the crust. Gravity anomaly modelling within the constraints and resolution provided by the seismic model, does not preclude, however, a layer of crustal underplate up to 3 km thick beneath the swell crest. The modelling shows that while the seismically constrained crustal structure accounts for the short-wavelength free-air gravity anomaly, it fails to fully explain the long-wavelength anomaly. The main discrepancy is over the swell crest where the gravity anomaly, after correcting for crustal structure, is higher by about 30 mGal than it is over its flanks. The higher gravity can be explained if the top 100 km of the mantle beneath the swell crest is less dense than its surroundings by 30 kg m,3. The lack of evidence for low densities and velocities in the uppermost mantle, and high densities and velocities in the lower crust, suggests that neither a depleted swell root or crustal underplate are the origin of the observed shallower-than-predicted bathymetry and that, instead, the swell is most likely supported by dynamic uplift associated with an anomalously low density asthenospheric mantle. [source] Sea-surface observations of the magnetic signals of ocean swellsGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2004F. E. M. Lilley SUMMARY Ocean swells have a magnetic signal, caused by the motional induction of sea water moving in the steady main magnetic field of Earth. To check the character of such signals at the sea surface, a magnetometer has been set free from a ship to float unrestricted on the surface of the ocean for periods of several days. The path of the floating magnetometer was tracked by satellite; this procedure enabled also the eventual recovery of the magnetometer by the ship. Superimposed upon a background of slow change of magnetic field, as the magnetometer drifted across different patterns of crustal magnetization, are high-frequency signals generated by the strong ocean swell present at the time. These wave-generated signals are typically up to 5 nT trough-to-peak, consistent with theory for their generation by ocean swells several metres trough-to-peak in height. The power spectra of the magnetic signals show a consistent peak at period 13 s, appropriate for the known characteristics of ocean swell in the area. The power spectra then exhibit a strong (,7 power) fall-off as period decreases below 13 s. This strong fall-off is consistent with oceanographic observations of the spectra of surface swell, combined with motional induction theory. [source] Preliminary climatology and improved modelling of south Indian Ocean and Southern Ocean mid-latitude cyclonesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 10 2004Bruce W. Buckley Abstract The intense mid-latitude cyclones that traverse the southern waters of the Indian Ocean, between South Africa and southwestern Western Australia, are among the strongest depressions found anywhere in the world, outside tropical waters. Near-surface winds that exceed storm force (i.e. 24 m/s or 48 knots), and central pressures of 960 hPa and lower, are relatively common for these systems. They pose a constant threat to both open ocean and coastal shipping, and regularly generate severe weather over the populated southwestern corner of Australia. Large ocean waves and swell produce extensive coastal inundation and erosion. There were two main aims in this study. The first aim was to develop a preliminary climatology of these intense mid-latitude cyclones, for the region 20,60 °S, 30,130 °E. The climatology, which is the first that we are aware of for this notoriously data-sparse region, is based largely upon satellite observations, particularly scatterometer data, and is supplemented by ship, buoy and all available land observations. The climatology revealed that, historically, the frequency and intensity of the mid-latitude cyclones in this domain have been significantly underestimated. This underestimation has resulted in analyses that have serious flaws, and the resultant operational forecasts provided to the duty forecasters in the regional forecast centre located in Perth, Western Australia, are of highly variable quality. A number of other climatological features of these storms are discussed in this article. The second aim was to identify the factors that can contribute to a significant improvement in model forecasts of these storms. So far, there have been very few studies of explosively developing cyclones over this part of the world. Results are presented here from a series of high-resolution numerical simulations of an intense cool season Southern Ocean cyclone that developed in 2003, using the HIRES numerical weather prediction model developed by L.M. Leslie. Here, we examine the sensitivity of the cyclone predictions to both model resolution and the initial analyses. The predicted variables of most interest are the central pressure, maximum sustained near-surface wind speeds, extent of storm-force winds, and the horizontal and vertical structure of the storm. Increased detail in the initial state is provided mainly by the assimilation into the archived global operational analyses of high-resolution satellite-derived data, including QuikSCAT scatterometer winds and sea-surface temperatures. The combination of increased horizontal and vertical model resolution, and improved initial model states, was found to produce numerical forecasts with significantly more accurate wind speeds than those obtained from the coarser resolution operational models, which also did not have the benefits of all the additional data. Finally, areas of future research are outlined, including coupling the HIRES atmospheric model with ocean and wave models, to improve forecasts of the sea state, including wind wave heights, swell and storm surges. Copyright © 2004 Royal Meteorological Society [source] Concrete canal lining cracking in low to medium plastic soils,IRRIGATION AND DRAINAGE, Issue 2 2002H. Rahimi sol plastique; gonflement; revêtement bétonique; Iran Abstract Failure of concrete irrigation canal linings in the form of cracking, rupture, uplifting and opening of joints, causes loss of water and money in many countries. Following the appearance of extensive cracking of concrete linings in one of the Shoeybieh sugar cane industry farms in the Khoozestan province of Iran, extensive research work was conducted to identify the main causes. In this paper, the final results of the research are presented. The testing program consisted of laboratory as well as field tests, including identification, chemical and mechanical tests of soil samples taken from the borrow pits and canal embankments. Dispersivity tests were performed using pin-hole and chemical methods. Swelling tests were conducted using the ASTM standard and ISSMFE method. The field test includes measurement of deformations of the concrete lining and embankment of an actual lined canal resulting from the filling of the canal with water. The canal was 60 m in length. The deformations were recorded by surveying the elevations of steel bars driven to different depths under the canal lining and at different points in the canal and its embankment sections. The results of laboratory tests showed the soil to have low to medium plasticity with a classification of CL-ML, having less than 1% soluble content, and being nondispersive. Swelling tests conducted by the ASTM and ISSMFE methods showed completely different results. The ISSMFE method resulted in a high free swell potential, while the ASTM method indicated a low to medium potential. The results of full-scale field tests were all in favor of the ISSMFE method. The greatest difference between the results of the two methods was found to be due to the different compaction methods used during construction of the canal, as well as the moisture content of the soil sample being prepared for the swell tests. The flocculent structure and lower compaction water content of soil samples in the ISSMFE method resulted in much higher free swell. The similarity between compaction methods used in the field and the static effort used in the ISSMFE method, as well as very low soil water content of the canal embankments during lining operations, were found to be the main reasons for swelling of the soil and the eventual cracking of the concrete linings. Copyright © 2002 John Wiley & Sons, Ltd. RÉSUMÉ L'écroulement du revêtement bétonique des canaux d'irrigation en forme de fissure, de la rupture, de la sous-pression et de l'ouverture des joints, est la cause de la perte d' eau et par conséquence des fonds publics de plusieurs pays dans le monde entier. Après avoir observé ce phénomène dans des canaux d'irrigation d'un grand projet de canne à sucre à Shoeybieh dans la région de Khozestan, située au sud de l'Iran, une équipe de recherche a été engagée pour trouver les causes principales de cetécroulement. Cet article présente les résultats finaux de cette recherche. Le programme consiste de deux types d'essai, en laboratoire et sur le terrain. Les échantillons du sol pour l'essai mécanique et chimique ont été pris dans des emprunts de terre et la digue du canal. Les essais de dispersivité ont été faits par les méthodes de pin-hole et de chimique. La méthode del ISSMFE et la standard del ASTM ont été utilisés pour les essais de gonflement du sol. Le mesurage de la déformation d'un canal revêté en béton et aussi de digue du canal a été fait par rempliz le canal avee de l'eau. Le canal avait une longueur de 60 m. La déformation a été observée en examinant les élévations à plusieurs points sur la profondeur du canal en dessous de la partie revêtée et aussi la digue du canal par un instrument spécifique. Les résultats des essais de laboratoire montrent que les sols qui ont une plasticité entre petite et moyenne situés dans la classification de CL-ML ayant moins d'un pour cent de contenude soluble sont non-dispersifes. Les essais de gonflement par les méthodes de l'ASTM et l'ISSME montrent des résultats tout à fait différents. La méthode ISSMFE montre un potentiel de gonflement assez élevé, tandis que la méthode ASTM montre un potentiel entre petit et moyen. Les résultats des essais en champs d'étude confirme la méthode ISSMFE. La plus grande différence entre le résultat de deux méthodes est à cause d'usage de plusieurs méthodes de compaction dans la période de la construction du canal. La structure floculée du sol ayant une humidité moins compactée dans la méthode ISSMFE montre un gonflement plus élevée du sol. Les méthodes similaires de compaction utilisées dans le champs d'étude et énergie statique utilisée par la méthode ISSFE, et aussi une petite humidité de digue du canal en période de revêtement sont les causes principales de gonflement et éventuellement de fissure. Copyright © 2002 John Wiley & Sons, Ltd. [source] Effects of diatomite on extrudate swell behavior of polypropylene composite meltsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010J. Z. Liang Abstract Extrudate swell (i.e., die swell) is an important parameter for characterization of melt elasticity during extrusion of polymeric melts, and die swell ratio (B) is usually used to describe quantitatively the melt swell degree. The B of the polypropylene (PP) composites filled with diatomite particles was measured by means of a melt flow rate instrument to investigate the effects of the filler content and size on the die swell behavior of the composite system melts under the experimental conditions with temperature from 210 to 230°C and load varying from 1.2 to 7.5 kg. The particle diameters were 5, 7, and 13 ,m, and the filler volume fractions were 5, 10, and 15%, respectively. The results showed that the B of the composites decreased nonlinearly with an increase of the filler volume fraction, whereas it increased as a quadratic function with an increase of the particle diameter when the load and temperature were fixed. It might be attributed to the interaction between the inclusions and the matrix, leading to blocking the recovery of the elastic deformation as the composite melts left from the die exit. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effects of quasi-nanogel particles on the rheological and mechanical properties of natural rubber: A new insightJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Suman Mitra Abstract The influence of sulfur-crosslinked, quasi-nanosized gels on the rheological and mechanical properties of raw natural rubber (NR) was investigated. Latex gels with different crosslink densities were prepared through the variation of the sulfur-to-accelerator ratio. These gels were characterized by dynamic light scattering, solvent swelling, and mechanical properties. The gels were mixed with raw NR latex at concentrations of 2, 4, 8, and 16 phr, and their effect on the rheological properties of NR was studied by Monsanto processability tester. The presence of gel in raw NR reduced the apparent shear viscosity and die swell considerably. Initially, the viscosity decreased up to a 8 phr gel loading and then increased with an increase in the gel loading. However, the change in the viscosity was related to the crosslink density of the gels. A new empirical equation relating the viscosity, volume fraction of the gels, and crosslink density was proposed. The die swell of gel-filled raw NR was at least 10% lower than that of unfilled raw NR and decreased with an increase in the gel loading. The effect of the gels on the die swell properties was explained through the calculation of the principal normal stress difference of gel-filled NR systems. Scanning electron photomicrographs of the extrudates revealed much better surface smoothness for the gel-filled virgin rubber systems than for the unfilled rubber. The addition of the gels to raw NR increased the modulus and tensile strength, whereas the elongation at break decreased. The effect of the gels on the dynamic mechanical properties of NR was also investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Simulation of particle migration in free-surface flowsAICHE JOURNAL, Issue 10 2010Kyung Hoon Min Abstract The migration of particles in free surface flows using the diffusive flux model was investigated. As the free-surface flows, a planar jet flow and a slot coating flow were chosen. The suspension was assumed to be a Newtonian fluid with a particle concentration dependent viscosity. The governing equations were solved numerically by the finite volume method, and the free-surface problem was handled by the volume of the fraction model. The result shows that even though the velocity profile is fully developed and becomes flat, the particle distribution never reaches the uniform distribution for both of the cases. It is also shown that the die swell of the free jet is reduced compared to the Newtonian fluid and when the particle loading is 0.5, die contraction is observed. The change in die swell characteristics is purely due to particle migration since the suspension model does not show normal stress differences. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Development of a bulgur-like product using extrusion cookingJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2003Hamit Köksel Abstract In this study we (1) developed a new bulgur-like foodstuff using a durum wheat cultivar and an extrusion technique, (2) investigated the physicochemical properties of the extrudates produced and (3) sensorially evaluated the end-product after cooking. Durum wheat was processed in a laboratory-scale co-rotating twin-screw extruder with different levels of moisture content of the feed (367, 417 and 455,g,kg,1), screw speed (150 and 200,rpm) and feed rate (2.4 and 2.9,kg,h,1) to develop the bulgur-like product. The effects of extrusion conditions on system variables (die pressure and specific mechanical energy (SME)), physical properties (die swell and bulk density), pasting properties (peak, trough and final viscosities) and cooking and sensory properties of the bulgur-like products were determined. The results indicated that increased feed moisture content resulted in significant decreases in the die pressure and SME values of the extruded durum wheat products. As the moisture content and screw speed increased, the changes in die swell values were not significant. The lowest die swell and highest bulk density values were obtained at the highest feed moisture content. The extrusion variables also affected the pasting properties of the extrudates. Significant increases in each of the pasting properties occurred when the moisture content of the feed was increased. Some of the sensory properties (bulkiness, firmness, stickiness and taste,aroma) improved significantly as the feed moisture content increased, indicating better quality. Increased feed moisture content significantly improved cooking quality as determined by a decrease in colorimetric test results. Extrusion seems to be promising for the production of dry, relatively inexpensive bulgur-like products with acceptable sensory properties. © 2003 Society of Chemical Industry [source] Kinetics of Demixing and Remixing Transitions in Aqueous Solutions of Poly(N -isopropylacrylamide): A Temperature-Jump 1H NMR StudyMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 21 2006Pavel V. Yushmanov Abstract Summary: The time course of the coil-to-globule collapse and intermolecular aggregation of poly(N -isopropylacrylamide) in aqueous solution upon exceeding the lower critical solution temperature (LCST) are investigated by temperature-jump 1H NMR spectroscopy. After the temperature jump, we record the time dependences of (i) the mobile fraction of the polymer chain as revealed by the intensity of the liquid-like NMR signal, (ii) the local mobility of those chains as revealed by the transverse relaxation time T2, and (iii) their self-diffusion coefficient D. The same data are also reported at their temperature-dependent long-time limits. The results suggest a sudden, faster than one second, collapse and intermolecular aggregation into globules and a slower reorganization/redistribution of the individual chains among and within the globular and mobile states. We found that all molecular changes are reversible if the temperature remains less than ca. 6,8 K above the LCST for less than a few minutes; under those conditions, experiments upon sudden temperature quench below the LCST show that the aggregates disintegrate and swell into coils in less than a few seconds. 1H NMR signal intensity of the methyl groups of 1 wt.-% PNIPAM dissolved in 0.1 M NaCl solution in D2O in a temperature-jump experiment from 300 to 312 K. The data were recorded by the 90°,,,(180°,2, -)n -detection of the CPMG pulse sequence. [source] ENVIRONMENTAL FACTORS INFLUENCING THE DISTRIBUTION OF SOUTHERN RIGHT WHALES (EUBALAENA AUSTRALIS) ON THE SOUTH COAST OF SOUTH AFRICA I: BROAD SCALE PATTERNSMARINE MAMMAL SCIENCE, Issue 3 2004Simon H. Elwen Abstract Aerial surveys over the last 32 yr have shown that the distribution of southern right whales Eubalaena australis along the south coast of South Africa is markedly discontinuous, but highly predictable. A GIS was used at a variety of scales to investigate whether this pattern was related to environmental characteristics. Whale distribution was analyzed as density per 20-min bin of longitude over two temporal and spatial scales, namely 15 bins for 32 yr, and a wider scale but shorter time period, 23 bins for 19 yr, as well as using three years of GPS accuracy data (15 bins) for finer scale analysis. Environmental factors tested were depth, distance from shore, sea floor slope, protection from swell, protection from wind, and shore type. The majority of whales were concentrated in areas that provided reasonable protection from open ocean swell and seasonal winds, and had sedimentary floors with gentle slopes. They generally avoided exposed rocky shorelines. Cow-calf pairs were found significantly closer to shore and in shallower water than unaccompanied whales, particularly off sandy beaches. Habitat choice at this time of year may be related both to energy conservation for calves and lactating females (calm sea conditions) and to protection of the new-born. [source] ENVIRONMENTAL FACTORS INFLUENCING THE DISTRIBUTION OF SOUTHERN RIGHT WHALES (EUBALAENA AUSTRALIS) ON THE SOUTH COAST OF SOUTH AFRICA II: WITHIN BAY DISTRIBUTIONMARINE MAMMAL SCIENCE, Issue 3 2004Simon H. Elwen Abstract Environmental factors are thought to strongly influence the distribution and predictability of the coastal distribution of southern right whales (Eubalaena australis) off South Africa. Preferred habitat had generally shallow sloping sedimentary floors and was characteristically protected from open ocean swell and prevalent seasonal winds. This study investigated whether habitat choices at smaller scales (within bays) were similar. Fine scale distribution patterns (GPS) from three years' surveys (1997, 1999, 2000) were analyzed separately within the three main concentration areas St Sebastian Bay, De Hoop, and Walker Bay (containing ,73% of cow-calf pairs and ,49% of unaccompanied adults in the whole survey region). Whale density at this scale of within particular bays did not correlate well with predicted variables, but Chi-squared analysis strongly supported results at broader scales, in all bays. Post-hoc"choice" tests between similar areas differing in only one variable revealed that cow-calves preferred (presumed) sandy substrates and especially protection from swell. The strength and predictability of preferences shown at fine scale (where individual movement and weather variability could have great influence) provide strong support for findings at larger scales and emphasize the importance of environmental factors in the habitat choice of wintering right whales. [source] Investigation of the relationships between die build up and die swellPOLYMER ENGINEERING & SCIENCE, Issue 2 2009Todd A. Hogan Die build up (DBU) is a common problem encountered during extrusion of polymers where material accumulates around the die exit and may cause defects in the surface of the product. This study was initiated to better understand the fundamental relationships between DBU and die swell. The study was conducted on a strand die extrusion system using an ethylene-octene polyolefin elastomer resin. This study demonstrated that die swell is not a root cause of DBU. It was shown that at constant shear rate, increasing the die L/D ratio results in an increase in DBU, while die swell decreases. The important variables influencing DBU for the resin used in this study were: the shear rate or shear stress in capillary portion of the die, the nominal residence time that the resin is exposed to the high shear stress in the die capillary, and the concentration of oligomers present in the resin or generated during processing. These data support the conclusion that DBU is due to the shear-induced migration of oligomeric species in the polymer to the die surface. Higher shear rates and stresses in the die promote this migration and result in a higher concentration of oligomeric species near the die wall. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers [source] Rheological characterization of HDPE/sisal fiber compositesPOLYMER ENGINEERING & SCIENCE, Issue 10 2007Smita Mohanty The present paper summarizes an experimental study on the molten viscoelastic behavior of HDPE/sisal composites under steady and dynamic mode. Variations of the melt viscosity and die swell of the composites with an increase in shear rate, fiber loading, and coupling agent concentration have been investigated using capillary rheometer. The shear rate , at the wall was calculated using Rabinowitsch correction applied to the apparent shear rate values. It was observed that the melt viscosity of the composites increased with the addition of fibers and maleic anhydride-grafted PE (MAPE). Die swell of HDPE also decreased with the addition of sisal fibers and MAPE. Further, the dynamic viscoelastic behavior of the composites was measured employing parallel plate rheometer. Time,temperature superposition was applied to generate various viscoelastic master curves. Temperature sweeps were also carried out to study the flow activation energy determined from Arrhenius equation. The fiber,matrix morphology of the extrudates was also examined using scanning electron microscopy. POLYM. ENG. SCI., 47:1634,1642, 2007. © 2007 Society of Plastics Engineers [source] A comprehensive experimental study and numerical modeling of parison formation in extrusion blow molding,POLYMER ENGINEERING & SCIENCE, Issue 1 2007Azizeh-Mitra Yousefi Parison dimensions in extrusion blow molding are affected by two phenomena, swell due to stress relaxation and sag drawdown due to gravity. It is well established that the parison swell and sag are strongly dependent on the die geometry and the operating conditions. The availability of a modeling technique ensures a more accurate prediction of the entire blow molding process, as the proper prediction of the parison formation is the input for the remaining process phases. This study considers both the simulated and the experimental effects of the die geometry, the operating conditions, and the resin properties on the parison dimensions using high density polyethylene. Parison programming with a moving mandrel and the flow rate evolution in intermittent extrusion are also considered. The parison dimensions are measured experimentally by using the pinch-off mold technique on two industrial scale machines. The finite element software BlowParison® developed at IMI is used to predict the parison formation, taking into account the swell, sag, and nonisothermal effects. The comparison between the predicted parison/part dimensions and the corresponding experimental data demonstrates the efficiency of numerical tools in the prediction of the final part thickness and weight distributions. POLYM. ENG. SCI., 47:1,13, 2007. © 2006 Society of Plastics Engineers [source] A parallel coextrusion technique for simultaneous measurements of radial die swell and velocity profiles of a polymer melt in a capillary rheometerPOLYMER ENGINEERING & SCIENCE, Issue 10 2004N.-T. Intawong This article proposes a new experimental technique to simultaneously measure radial die swell and velocity profiles of polystyrene melt flowing in the capillary die of a constant shear rate rheometer. The proposed technique was based on parallel coextrusion of colored melt-layers into uncolored melt-stream from the barrel into and out of the capillary die. The size (thickness) ratio of the generated melt layers flowing in and out of the die was monitored to produce the extrudate swell ratio for any given radial position across the die diameter. The radial velocity profiles of the melt were measured by introducing relatively light and small particles into the melt layers, and the times taken for the particles to travel for a given distance were measured. The proposed experimental technique was found to be both very simple and useful for the simultaneous and accurate measurement of radial die swell and velocity profiles of highly viscous fluids in an extrusion process. The variations in radial die swell profiles were explained in terms of changes in melt velocity, shear rate, and residence time at radial positions across the die. The radial die swell and velocity profiles for PS melt determined experimentally in this work were accurate to 92.2% and 90.8%, respectively. The overall die swell ratio of the melt ranged from 1.25 to 1.38. The overall die swell ratio was found to increase with increasing piston speed (shear rate). The radial extrudate swell profiles could not be reasoned by the shear rate change, but were closely linked with the development of the velocity profiles of the melt in the die. The die swell ratio was high at the center (,1.9) and low (,0.9) near the die wall. The die swell ratio at the center of the die reduced slightly as the piston speed was increased. Polym. Eng. Sci. 44:1960,1969, 2004. © 2004 Society of Plastics Engineers. [source] Compensating for die swell in the design of profile diesPOLYMER ENGINEERING & SCIENCE, Issue 10 2003W. A. Gifford Because of the effects of die swell, the final shape of an extrudate is often substantially different from that of the exit opening of the die. As a result, the design of profile dies producing complex shapes often involves more than just "balancing" the die but also compensating for the effects of die swell. Typically, a successful design of such dies is achieved only through much "cut and try," However, with the use of a fully three-dimensional finite element flow algorithm along with quick mesh generating capabilities, the usual cut and try involved in the design of many profile dies can be greatly reduced, if not eliminated. This paper demonstrates how the effects of die swell can be compensated for in the design of profile dies. For profiles with one plane of symmetry, this includes compensating for the sideways translation of the extrudate as well as the change in shape that the extrudate experiences. Completely asymmetric profiles undergo a "twisting" downstream of the die. This twisting, which appears not to have been reported in the literature (at least for isothermal extrusion), is also accounted for here, along with the change in shape that the extrudate undergoes. The translation or twisting of profiles downstream of a die is often attributed to non-Newtonian or non-isothermal effects. Only isothermal Newtonian examples are considered here. These results clearly show that asymmetry of the profile will result in a translation and twisting of the extrudate even in the isothermal Newtonian case. [source] Nonisothermal two-dimensional film casting of a viscous polymerPOLYMER ENGINEERING & SCIENCE, Issue 8 2000Spencer Smith A model is presented for simulating two-dimensional, nonisothermal film casting of a viscous polymer. The model accommodates the effects of inertia and gravity, and allows the thickness of the film to vary across the width, but it excludes film sag and die swell. Based on the simulation results, three factors are shown to contribute to reducing neck-in and promoting a uniform thickness: the self-weight of the material, for low viscosity polymers; nonuniform thickness and/or velocity profiles at the die; and cooling of the film, especially when localized cooling jets are employed. [source] Overall numerical simulation of extrusion blow molding processPOLYMER ENGINEERING & SCIENCE, Issue 8 2000Shin-Ichiro Tanifuji This paper focuses on the overall numerical simulation of the parison formation and inflation process of extrusion blow molding. The competing effects due to swell and drawdown in the parison formation process were analyzed by a Lagrangian Eulerian (LE) finite element method (FEM) using an automatic remeshing technique. The parison extruded through an annular die was modeled as an axisymmetric unsteady nonisothermal flow with free surfaces and its viscoelastic properties were described by a K-BKZ integral constitutive equation. An unsteady die-swell simulation was performed to predict the time course of the extrudate parison shape under the influence of gravity and the parison controller. In addition, an unsteady large deformation analysis of the parison inflation process was also carried out using a three-dimensional membrane FEM for viscoelastic material. The inflation sequence for the parison molded into a complex-shaped mold cavity was analyzed. The numerical results were verified using experimental data from each of the sub-processes. The greatest advantage of the overall simulation is that the variation in the parison dimension caused by the swell and drawdown effect can be incorporated into the inflation analysis, and consequently, the accuracy of the numerical prediction can be enhanced. The overall simulation technique provides a rational means to assist the mold design and the determination of the optimal process conditions. [source] Rheological behavior of highly filled ethylene propylene diene rubber compoundsPOLYMER ENGINEERING & SCIENCE, Issue 5 2000M. G. Markovic The rheological behavior of highly filled ethylene propylene diene rubber (EPDM) compounds was studied with respect to the effect of curative system, grafted rubber, shear rate, temperature and die swell using a Monsanto Processability Tester (MPT) to gain an understanding of the molecular parameters that control the surface finish. All systems show pseudoplastic behavior. At a particular shear rate, shear viscosity increases with blend ratio. The dependence of flow behavior on extrusion velocity indicates a surface effect. The extrudate die swell and maximum recoverable deformation are related by a linear relationship, which is independent of sulfur/accelerator ratio, extrusion temperature and shear rates and blend ratio. The principal normal stress difference increases nonlinearly with shear stress. Activation energy decreases with shear rate in most cases. The faster relaxing system produces extrudate of better surface quality. [source] Melt viscoelasticity of polyethylene terephthalate resins for low density extrusion foamingPOLYMER ENGINEERING & SCIENCE, Issue 3 2000uintans The rheological properties of conventional polyethylene terephthalate (PET) resins are not particularly suitable for low density extrusion foaming with physical blowing agents; as a result, chemically modified resins through chain extension/branching reactions are often used. Such resins have overall higher melt viscosity and higher melt strength/melt "elasticity" than unmodified materials. In this work, following a review of the prior art on PET chemical modification, an unmodified and a chemically modified resin were selected and characterized for their melt viscoelastic properties including shear and dynamic complex viscosity over a broad shear rate/frequency range, storage and loss modulus, and die swell. Certain rheological models were found to provide better fits of the entire viscosity curve for the unmodified vs. the modified resin. Foamed extrudates having variable densities (from about 1.2 to 0.2 g/cc), were prepared by carbon dioxide injection in monolayer flat sheet extrusion equipment. Foams with increasingly lower density, below 0.5 g/cc, were obtained by increasing gas pressure only in the case of the chemically modified resin. The effects of variables such as concentration of the physical blowing agent, resin rheology, resin thermal properties and choice of process conditions are related to product characteristics including density, cell size and crystallinity. [source] Hydrogels as smart biomaterialsPOLYMER INTERNATIONAL, Issue 9 2007ich Kope Abstract Hydrogels were the first biomaterials rationally designed for human use. Beginning with the pioneering work of Wichterle and Lím on three-dimensional polymers that swell in water, we review the design, synthesis, properties, and applications of hydrogels. The field of hydrogels has moved forward at a dramatic pace. The development of suitable synthetic methods encompassing traditional chemistry to molecular biology has been used in the design of hydrogels mimicking basic processes of living systems. Stimuli-sensitive hydrogels, hydrogels with controlled degradability, genetically engineered poly(amino acid) polymers reversibly self-assembling in precisely defined three-dimensional structures, and hybrid polymers composed of two distinct classes of molecules are just some examples of these exciting novel biomaterials. The biocompatibility of hydrogels and their applications from implants to nanomaterials are also reviewed. Copyright © 2007 Society of Chemical Industry [source] The Effect of Orientation on Extrusion Cast Metallocene Polyethylenes and the Role of Processing Conditions in the Die Swell of Metallocene and Conventional PolyethylenesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1-2 2004B.G. Millar Cast films were prepared from a range of metallocene polyethylenes (mPEs) of varied co-monomer types (hexene, octene) using a Killion single-screw extruder, using different haul off speeds (8,4 m/min) and die gaps (700,250 m,m). Samples with greater orientation in one direction had increased tensile strength and shrinkage in that direction. DSC analysis showed crystallinity to decrease with decreasing haul of speed. Extrusion of mPEs and conventional linear low density polyethylenes (LLDPEs) by single capillary rheology showed that die swell increased with increasing extrusion rate and decreasing melt temperature. Increased die swell was found for the broader molecular weight distribution (M.W.D.) LLDPEs and in the higher molecular weight resins. Furthermore, long chain branching was found to increase die swell. [source] Characteristics of Oil Sources from the Chepaizi Swell, Junggar Basin, ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2010LIU Luofu Abstract: So far there has been no common opinion on oil source of the Chepaizi swell in the Junggar Basin. Therefore, it is difficult to determine the pathway system and trend of hydrocarbon migration, and this resulted in difficulties in study of oil-gas accumulation patterns. In this paper, study of nitrogen compounds distribution in oils from Chepaizi was carried out in order to classify source rocks of oils stored in different reservoirs in the study area. Then, migration characteristics of oils from the same source were investigated by using nitrogen compounds parameters. The results of nitrogen compounds in a group of oil/oil sand samples from the same source indicate that the oils trapped in the Chepaizi swell experienced an obvious vertical migration. With increasing migration distance, amounts and indices of carbazoles have a regular changing pattern (in a fine linear relationship). By using nitrogen compounds techniques, the analyzed oil/oil sand samples of Chepaizi can be classified into two groups. One is the samples stored in reservoir beds of the Cretaceous and Tertiary, and these oils came from mainly Jurassic source rock with a small amount of Cretaceous rock; the other is those stored in the Jurassic, Permian and Carboniferous beds, and they originated from the Permian source. In addition, a sample of oil from an upper Jurassic reservoir (Well Ka 6), which was generated from Jurassic coal source rock, has a totally different nitrogen compound distribution from those of the above-mentioned two groups of samples, which were generated from mudstone sources. Because of influence from fractionation of oil migration, amounts and ratios of nitrogen compounds with different structures and polarities change regularly with increasing migrating distance, and as a result the samples with the same source follow a good linear relationship in content and ratio, while the oil samples of different sources have obviously different nitrogen compound distribution owing to different organic matter types of their source rocks. These conclusions of oil source study are identical with those obtained by other geochemical bio-markers. Therefore, nitrogen compounds are of great significance in oil type classification and oil/source correlation. [source] Chlorotoxin does not inhibit volume-regulated, calcium-activated and cyclic AMP-activated chloride channelsBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2000Chantal Maertens It was the aim of this study to look for a high-affinity and selective polypeptide toxin, which could serve as a probe for the volume-regulated anion channel (VRAC) or the calcium-activated chloride channel (CaCC). We have partially purified chlorotoxin, including new and homologous short chain insectotoxins, from the crude venom of Leiurus quinquestriatus quinquestriatus (Lqq) by means of gel filtration chromatography. Material eluting between 280 and 420 min, corresponding to fractions 15,21, was lyophilized and tested on VRAC and CaCC, using the whole-cell patch-clamp technique. We have also tested the commercially available chlorotoxin on VRAC, CaCC, the cystic fibrosis transmembrane conductance regulator (CFTR) and on the glioma specific chloride channel (GCC). VRAC and the correspondent current, ICl,swell, was activated in Cultured Pulmonary Artery Endothelial (CPAE) cells by a 25% hypotonic solution. Neither of the fractions 16,21 significantly inhibited ICl,swell (n=4,5). Ca2+ -activated Cl, currents, ICl,Ca, activated by loading T84 cells via the patch pipette with 1 ,M free Ca2+, were not inhibited by any of the tested fractions (15,21), (n=2,5). Chlorotoxin (625 nM) did neither effect ICl,swell nor ICl,Ca (n=4,5). The CFTR channel, transiently transfected in COS cells and activated by a cocktail containing IBMX and forskolin, was not affected by 1.2 ,M chlorotoxin (n=5). In addition, it did not affect currents through GCC. We conclude that submicromolar concentrations of chlorotoxin do not block volume-regulated, Ca2+ -activated and CFTR chloride channels and that it can not be classified as a general chloride channel toxin. British Journal of Pharmacology (2000) 129, 791,801; doi:10.1038/sj.bjp.0703102 [source] | |||||||||||||||||||||||||