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Gary Kocurek - One of the best experts on this subject based on the ideXlab platform.
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aeolian dune interactions and dune field pattern formation white sands dune field new mexico
Sedimentology, 2010Co-Authors: Ryan C. Ewing, Gary KocurekAbstract:Pattern formation is a fundamental aspect of self-organization in fields of bedforms. Time-series aerial photographs and airborne light detection and ranging show that fully developed, crescentic aeolian dunes at White Sands, New Mexico, interact and the dune pattern organizes in systematically similar ways as wind ripples and subaqueous dunes and ripples. Documented interactions include: (i) merging; (ii) lateral linking; (iii) defect repulsion; (iv) bedform repulsion; (v) off-centre collision; (vi) defect creation; and (vii) dune splitting. Merging and lateral linking are constructive interactions that give rise to a more organized pattern. Defect creation and bedform splitting are regenerative interactions that push the system to a more disorganized state. Defect/bedform repulsion and off-centre collision cause significant pattern change, but appear to be neutral in overall pattern development. Measurements of pattern parameters (number of dunes, crest length, defect density, crest spacing and dune height), dune migration rates, and the type and frequency of dune interactions within a 3500 m box transect from the upwind margin to the core of the dune field show that most pattern organization occurs within the upwind field. Upwind dominance by constructive interactions yields to neutral and regenerative interactions in the field centre. This spatial change reflects upwind line source and sediment availability boundary conditions arising from antecedent palaeo-lake topography. Pattern evolution is most strongly coupled to the pattern parameters of dune spacing and defect density, such that spatially or temporally the frequency of bedform interactions decreases as the dunes become further apart and have fewer defects.
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white sands dune field new mexico age dune dynamics and recent accumulations
Sedimentary Geology, 2007Co-Authors: Gary Kocurek, Karen G. Havholm, Ryan C. Ewing, Mary Carr, Y C Nagar, A K SinghviAbstract:Abstract The White Sands Dune Field, situated within the Tularosa Basin in southern New Mexico, is thought to have been largely derived by a stepwise, progressive deflation of Pleistocene Lake Otero strata with the onset of regional aridity. Optically stimulated luminescence (OSL) dating of samples from a core that penetrated the gypsum accumulation of the dune field confirm a time of origin at ∼ 7000 yr. Dune sediment is characterized as lagged influx from previously stored Lake Otero sediment and contemporaneous influx derived from subsequent playas. Sediment became available for aeolian transport and dune-field construction because of a falling water table driven by the regional aridity. The current dune field is primarily a wet aeolian system in which the behavior of the accumulation surface over time is a function of the water table, although surface cementation by gypsum also imparts aspects of a stabilizing system. Dune crests are oriented borderline transverse to the annual transport resultant, and a monitored dune and its cross-strata show that transverse winds from the SW during the late winter and spring account for most of the crest-normal migration, but a significant along-crest component of migration of dune sinuosity occurs with fall and winter winds from the NW and N that strike the crests obliquely. Trenches across three interdune areas show dune sets and interdune strata climbing at about 0.1°. Depth of interdune scour increases with interdune streamwise length, which acts to enhance the probability of dune cross-strata deflation during arid years, but also increases the probability of interdune accumulation because the water table shows a net rise over time. Within the trenches, dune sets show a bundling of foresets between reactivation surfaces, interpreted as annual cycles that reveal lee-face reworking by the oblique NW and N winds and slipface progradation fostered by transverse winds from the SW. A progression from grainflow-dominated to wind-ripple-dominated cross-strata within a single set revealed in the longest trench is consistent with along-crest migration of dune sinuosity. Interdune laminations show light/dark couplets interpreted as annual varves reflecting dry/wet portions of the year. The number of laminations preserved in vertical sections across an interdune area shows that the record is incomplete, and endorses the interpretation of periods of interdune deflation. A calculation of the current accumulation rate as based upon the climbing strata within the trenches is significantly greater than the long-term accumulation rate determined by OSL dates taken from the core. In addition to compaction and possible dissolution of gypsum as partial explanations, the long-term accumulation rate may reflect significant variation in the accumulation rate over time, short-term deflation of accumulations on a regular basis, and/or the presence of unconformities within the gypsum body.
Larry Lessard - One of the best experts on this subject based on the ideXlab platform.
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cure shrinkage characterization and modeling of a polyester resin containing low profile additives
Composites Part A-applied Science and Manufacturing, 2007Co-Authors: Mohsan Haider, Pascal Hubert, Larry LessardAbstract:Resin Transfer Moulding (RTM) has great potential as an efficient and economical process for fabricating large and complicated composite structural components. The low capital investment cost required and process versatility in component integration and assembly make RTM very attractive for high volume automotive applications. One of the challenges facing the automotive field is the resulting surface finish of manufactured components. The shrinkage associated with the curing of thermoset resins contributes to the poor surface quality. Low profile additives (LPA) are added to the resin to compensate for the cure shrinkage; however their effects on the thermal, rheological and morphological properties of polyester resins are not well understood. In this paper, the effect of LPA on cure kinetics, cure shrinkage and viscosity of a polyester resin is studied through differential scanning calorimetry (DSC) and special rheological techniques. Models are developed to predict cure shrinkage, LPA expansion, cure kinetics and viscosity variations of the resin as a function of processing temperature. Finally, morphological changes in the resin with and without LPA, during isothermal cure, are studied with hot stage optical microscopy. The results show that the LPA content in the range tested had no significant effect on the cure kinetics. However, higher LPA content reduced cure rate and cure shrinkage. A minimum of 10% LPA was required to compensate for cure shrinkage. Shrinkage behavior of all formulations was similar until a degree-of-cure of 0.5. However, resin formulations with higher LPA content showed expansion at later stages during curing.
Corrado Adamo - One of the best experts on this subject based on the ideXlab platform.
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guide d evaluation olfacto gustative des fromages a pâte Dure et semi Dure
Lwt - Food Science and Technology, 1997Co-Authors: Florence Berodier, Pierre Lavanchy, Mario Zannoni, Jeronima Casals, Luis Herrero, Corrado AdamoAbstract:Resume A Guide to the Sensory Evaluation of Smell, Aroma and Taste of Hard and Semi-hard Cheeses Within a European research programme (AIR-CT-94-2039), a group of researchers undertaking sensory analysis of cheese applied itself to standardizing panel training methods. A common methodology to characterize smell, aroma, taste and trigeminal sensations, that is to say olfactory and gustative properties of hard and semi-hard cheeses was determined. These properties were evaluated on five Protected Designation of Origin cheeses (PDO) by panels working in four countries. Without neglecting the importance of texture on aroma perception, the group defined an evaluation scale for the different characteristics. Odours and aromas were classified in odour and aroma families that were tested by the panels. A cheese aroma wheel is proposed. Along with the former methodology for sensory evaluation of texture published in 1993 the present work completes the methodology for the sensory characterization of hard and semi-hard cheeses made from cow milk. Dans le cadre d'un programme europeeen (AIR-CT94-2039 et COST95), un groupe de responsables de l'analyse sensorielle des fromages a travaille sur l'harmonisation des methodes pour entrainer des jurys. Ce travail a conduit a l'elaboration d'une methodologie commune pour caracteriser des odeurs, les aromes, les saveurs et les sensations trigeminales, c'est-a-dire les proprietes olfacto-gustatives des fromages a a pâte Dure et semi-Dure. Ces proprietes ont ete evaluees sur cinq fromages a Appellation d'Origine Protegee (AOP) par des jurys travaillant dans quatre pays differents. Sans negliger l'importance de la texture sur la perception des aromes, le groupe s'est defini un ordre pour l'evaluation des differentes caracteristiques. Les odeurs et les aromes ont ete classes dans des familles d'odeur et d'arome testees par les jurys. Une roue des aromes des fromages est proposee. Tous les descripteurs sont precises par des references. La methodologie proposee permet aussi bien de decrire que de quantifier les caracteristiques olfacto-gustatives des fromages. Finalement, avec la pecedente methodologie mise au point pour l'evaluation de la texture en 1993, ce travail forme un ensemble pour la caracterisation sensorielle des fromages a pâte Dure et semi-Dure au lait de vache.
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l evaluation sensorielle de la texture des fromages a pâte Dure ou semi Dure etude interlaboratoires
Lwt - Food Science and Technology, 1993Co-Authors: Pierre Lavanchy, Florence Berodier, Mario Zannoni, Corrado Adamo, Yolande Noel, Juan Squella, Luis HerreroAbstract:Abstract Dans le cadre du programme FLAIR COST 902, un groupe d'analyse sensorielle des fromages s'est forme pour harmoniser l'entrainement des jurys de degustation et pour avoir une methode commune pour caracteriser les fromages a pâte Dure et semiDure. Cinq fromrages d' 'Appellation d'origine controlee' (AOC) ont ainsi ete etudies. Il s'agit du Comte (Jura francais), du Parmigiano-Reggiano et de la Fontina (Italie), du Mahon (Espagne) et de l'Appenzeller (Suisse). Apres avoir defini l'importance de la texture des fromages entre l'apparence et la flaveur et avoir constate qu'aucune methode de la litteratare n'etait directement applicable, le groupe s'est mis d'accord sur la facon d'apprecier la texture des fromages. Les caracteristiques de surface, meaniques, geometriques ainsi que d'autres sensations kinesthesiques et intra-buccales ont ete etudiees. Pour preciser les perceptions et leurs intensites, des produits alimentaires de reference autres que des fromages sont indiques. Il s'agit, par exemple, de pomme, de biscuit ou de l'interieur d'une peau de banane. De plus, pour permettre l'etude des relations entre l'analyse instrumentale et sensorielle—objectif principal de FLAIR COST—les caracteristiques mecaniques ont ete precisees par des definitions physique et sensorielle, ainsi que par une technique d'evaluation originale. L'ampitude de la perception est donnee par une echelle de sept niveaux, dont trois sont fixes par un produit de reference standardise et connu de tous les pays europeens. Les difficultes semantiques et socio-culturelles ont ete prises en compte. Si ce guide a ete elabore originalement en francais, des traductions en italien, espagnol, allemand et anglais sont prevues dans le cadre de FLAIR COST. Elles sont placees sous la responsabilite des divers auteurs de cette methode. Sensory Evaluation of the Texture of Hard and Semi-hard Cheeses. A Collaborative Study A group for the sensory analysis of cheese was formed as part of the FLAIR COST 902 programme in order to harmonize the training of the tasting panel and to develop a common method for characterizing hard and semi-hard cheese. After placing the importance of cheese texture between its aspect and flavour and having noted that no method described in the literature was directly applicable, the group agreed on a method to appreciate the texture of cheese. The characteristics of surface, mechanical, geometrical and other kinaesthetic and oral sensations were studied. Other reference foods besides cheese, e.g. an apple or a biscuit or the inside of a banana skin, were used to clarify perceptions as well as their intensities. Also, in order to study the relationship between the instrumental and sensory analysis—the principal object of the FLAIR COST project—the mechanical characteristics were clarified by physical and sensory definitions as well as by an original assessment technique. The magnitude of perception is measured on a scale of seven, three of which are set by a standard reference product known in all European countries. Semantic and socio-cultural difficulties were taken into consideration. This guide was originally prepared in French, however, translations into Italian, Spanish, German and English will be made in the future as part of the FLAIR COST project. They are placed under the responsibility of the various authors of this method.
Luis Herrero - One of the best experts on this subject based on the ideXlab platform.
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guide d evaluation olfacto gustative des fromages a pâte Dure et semi Dure
Lwt - Food Science and Technology, 1997Co-Authors: Florence Berodier, Pierre Lavanchy, Mario Zannoni, Jeronima Casals, Luis Herrero, Corrado AdamoAbstract:Resume A Guide to the Sensory Evaluation of Smell, Aroma and Taste of Hard and Semi-hard Cheeses Within a European research programme (AIR-CT-94-2039), a group of researchers undertaking sensory analysis of cheese applied itself to standardizing panel training methods. A common methodology to characterize smell, aroma, taste and trigeminal sensations, that is to say olfactory and gustative properties of hard and semi-hard cheeses was determined. These properties were evaluated on five Protected Designation of Origin cheeses (PDO) by panels working in four countries. Without neglecting the importance of texture on aroma perception, the group defined an evaluation scale for the different characteristics. Odours and aromas were classified in odour and aroma families that were tested by the panels. A cheese aroma wheel is proposed. Along with the former methodology for sensory evaluation of texture published in 1993 the present work completes the methodology for the sensory characterization of hard and semi-hard cheeses made from cow milk. Dans le cadre d'un programme europeeen (AIR-CT94-2039 et COST95), un groupe de responsables de l'analyse sensorielle des fromages a travaille sur l'harmonisation des methodes pour entrainer des jurys. Ce travail a conduit a l'elaboration d'une methodologie commune pour caracteriser des odeurs, les aromes, les saveurs et les sensations trigeminales, c'est-a-dire les proprietes olfacto-gustatives des fromages a a pâte Dure et semi-Dure. Ces proprietes ont ete evaluees sur cinq fromages a Appellation d'Origine Protegee (AOP) par des jurys travaillant dans quatre pays differents. Sans negliger l'importance de la texture sur la perception des aromes, le groupe s'est defini un ordre pour l'evaluation des differentes caracteristiques. Les odeurs et les aromes ont ete classes dans des familles d'odeur et d'arome testees par les jurys. Une roue des aromes des fromages est proposee. Tous les descripteurs sont precises par des references. La methodologie proposee permet aussi bien de decrire que de quantifier les caracteristiques olfacto-gustatives des fromages. Finalement, avec la pecedente methodologie mise au point pour l'evaluation de la texture en 1993, ce travail forme un ensemble pour la caracterisation sensorielle des fromages a pâte Dure et semi-Dure au lait de vache.
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l evaluation sensorielle de la texture des fromages a pâte Dure ou semi Dure etude interlaboratoires
Lwt - Food Science and Technology, 1993Co-Authors: Pierre Lavanchy, Florence Berodier, Mario Zannoni, Corrado Adamo, Yolande Noel, Juan Squella, Luis HerreroAbstract:Abstract Dans le cadre du programme FLAIR COST 902, un groupe d'analyse sensorielle des fromages s'est forme pour harmoniser l'entrainement des jurys de degustation et pour avoir une methode commune pour caracteriser les fromages a pâte Dure et semiDure. Cinq fromrages d' 'Appellation d'origine controlee' (AOC) ont ainsi ete etudies. Il s'agit du Comte (Jura francais), du Parmigiano-Reggiano et de la Fontina (Italie), du Mahon (Espagne) et de l'Appenzeller (Suisse). Apres avoir defini l'importance de la texture des fromages entre l'apparence et la flaveur et avoir constate qu'aucune methode de la litteratare n'etait directement applicable, le groupe s'est mis d'accord sur la facon d'apprecier la texture des fromages. Les caracteristiques de surface, meaniques, geometriques ainsi que d'autres sensations kinesthesiques et intra-buccales ont ete etudiees. Pour preciser les perceptions et leurs intensites, des produits alimentaires de reference autres que des fromages sont indiques. Il s'agit, par exemple, de pomme, de biscuit ou de l'interieur d'une peau de banane. De plus, pour permettre l'etude des relations entre l'analyse instrumentale et sensorielle—objectif principal de FLAIR COST—les caracteristiques mecaniques ont ete precisees par des definitions physique et sensorielle, ainsi que par une technique d'evaluation originale. L'ampitude de la perception est donnee par une echelle de sept niveaux, dont trois sont fixes par un produit de reference standardise et connu de tous les pays europeens. Les difficultes semantiques et socio-culturelles ont ete prises en compte. Si ce guide a ete elabore originalement en francais, des traductions en italien, espagnol, allemand et anglais sont prevues dans le cadre de FLAIR COST. Elles sont placees sous la responsabilite des divers auteurs de cette methode. Sensory Evaluation of the Texture of Hard and Semi-hard Cheeses. A Collaborative Study A group for the sensory analysis of cheese was formed as part of the FLAIR COST 902 programme in order to harmonize the training of the tasting panel and to develop a common method for characterizing hard and semi-hard cheese. After placing the importance of cheese texture between its aspect and flavour and having noted that no method described in the literature was directly applicable, the group agreed on a method to appreciate the texture of cheese. The characteristics of surface, mechanical, geometrical and other kinaesthetic and oral sensations were studied. Other reference foods besides cheese, e.g. an apple or a biscuit or the inside of a banana skin, were used to clarify perceptions as well as their intensities. Also, in order to study the relationship between the instrumental and sensory analysis—the principal object of the FLAIR COST project—the mechanical characteristics were clarified by physical and sensory definitions as well as by an original assessment technique. The magnitude of perception is measured on a scale of seven, three of which are set by a standard reference product known in all European countries. Semantic and socio-cultural difficulties were taken into consideration. This guide was originally prepared in French, however, translations into Italian, Spanish, German and English will be made in the future as part of the FLAIR COST project. They are placed under the responsibility of the various authors of this method.
Ryan C. Ewing - One of the best experts on this subject based on the ideXlab platform.
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aeolian dune interactions and dune field pattern formation white sands dune field new mexico
Sedimentology, 2010Co-Authors: Ryan C. Ewing, Gary KocurekAbstract:Pattern formation is a fundamental aspect of self-organization in fields of bedforms. Time-series aerial photographs and airborne light detection and ranging show that fully developed, crescentic aeolian dunes at White Sands, New Mexico, interact and the dune pattern organizes in systematically similar ways as wind ripples and subaqueous dunes and ripples. Documented interactions include: (i) merging; (ii) lateral linking; (iii) defect repulsion; (iv) bedform repulsion; (v) off-centre collision; (vi) defect creation; and (vii) dune splitting. Merging and lateral linking are constructive interactions that give rise to a more organized pattern. Defect creation and bedform splitting are regenerative interactions that push the system to a more disorganized state. Defect/bedform repulsion and off-centre collision cause significant pattern change, but appear to be neutral in overall pattern development. Measurements of pattern parameters (number of dunes, crest length, defect density, crest spacing and dune height), dune migration rates, and the type and frequency of dune interactions within a 3500 m box transect from the upwind margin to the core of the dune field show that most pattern organization occurs within the upwind field. Upwind dominance by constructive interactions yields to neutral and regenerative interactions in the field centre. This spatial change reflects upwind line source and sediment availability boundary conditions arising from antecedent palaeo-lake topography. Pattern evolution is most strongly coupled to the pattern parameters of dune spacing and defect density, such that spatially or temporally the frequency of bedform interactions decreases as the dunes become further apart and have fewer defects.
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white sands dune field new mexico age dune dynamics and recent accumulations
Sedimentary Geology, 2007Co-Authors: Gary Kocurek, Karen G. Havholm, Ryan C. Ewing, Mary Carr, Y C Nagar, A K SinghviAbstract:Abstract The White Sands Dune Field, situated within the Tularosa Basin in southern New Mexico, is thought to have been largely derived by a stepwise, progressive deflation of Pleistocene Lake Otero strata with the onset of regional aridity. Optically stimulated luminescence (OSL) dating of samples from a core that penetrated the gypsum accumulation of the dune field confirm a time of origin at ∼ 7000 yr. Dune sediment is characterized as lagged influx from previously stored Lake Otero sediment and contemporaneous influx derived from subsequent playas. Sediment became available for aeolian transport and dune-field construction because of a falling water table driven by the regional aridity. The current dune field is primarily a wet aeolian system in which the behavior of the accumulation surface over time is a function of the water table, although surface cementation by gypsum also imparts aspects of a stabilizing system. Dune crests are oriented borderline transverse to the annual transport resultant, and a monitored dune and its cross-strata show that transverse winds from the SW during the late winter and spring account for most of the crest-normal migration, but a significant along-crest component of migration of dune sinuosity occurs with fall and winter winds from the NW and N that strike the crests obliquely. Trenches across three interdune areas show dune sets and interdune strata climbing at about 0.1°. Depth of interdune scour increases with interdune streamwise length, which acts to enhance the probability of dune cross-strata deflation during arid years, but also increases the probability of interdune accumulation because the water table shows a net rise over time. Within the trenches, dune sets show a bundling of foresets between reactivation surfaces, interpreted as annual cycles that reveal lee-face reworking by the oblique NW and N winds and slipface progradation fostered by transverse winds from the SW. A progression from grainflow-dominated to wind-ripple-dominated cross-strata within a single set revealed in the longest trench is consistent with along-crest migration of dune sinuosity. Interdune laminations show light/dark couplets interpreted as annual varves reflecting dry/wet portions of the year. The number of laminations preserved in vertical sections across an interdune area shows that the record is incomplete, and endorses the interpretation of periods of interdune deflation. A calculation of the current accumulation rate as based upon the climbing strata within the trenches is significantly greater than the long-term accumulation rate determined by OSL dates taken from the core. In addition to compaction and possible dissolution of gypsum as partial explanations, the long-term accumulation rate may reflect significant variation in the accumulation rate over time, short-term deflation of accumulations on a regular basis, and/or the presence of unconformities within the gypsum body.
